JP6687480B2 - Cooling device for internal combustion engine - Google Patents

Description

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

  There is known a technique of circulating cooling water between an internal combustion engine and a radiator in order to suppress a temperature rise of the internal combustion engine. In Patent Document 1, a temperature sensor is used to detect the temperature of the 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 drive time of the water pump according to the temperature of the cooling water (the detection value of the temperature sensor provided in the vicinity of the internal combustion engine) and the load (rotation 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 drive 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 drive time of the water pump based on the temperature at the moment when the temperature sensor detects it. In Patent Document 1, the detection value of the temperature sensor is not compared with the set predetermined temperature during a preset control cycle 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, the temperature change of the cooling water during driving of the water pump (during cooling of the internal combustion engine) cannot be sufficiently coped with, the internal combustion engine cannot be cooled sufficiently, or the internal combustion engine may be 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 cooling water regardless of the drive state (whether it is on or off) of the water pump. That is, the temperature of the cooling water is detected whether the temperature of the cooling water is rising or falling. Thereby, the temperature change of the cooling water can be accurately detected, and the temperature of the cooling water can be maintained in an appropriate range. Further, the cooling device disclosed in the present specification focuses on the fact that there is a time difference between the time when the temperature sensor detects the water temperature and the time when the water temperature starts decreasing due to the driving of the water pump, and after the driving of the water pump is stopped. A switching prohibition period is provided that prohibits switching of the water pump from the off state to the on state even when the temperature of the cooling water (the detection value of the temperature sensor) reaches the temperature at which the water pump should be driven. As a result, the water pump is driven again before the influence of driving the water pump is reflected on the temperature of the cooling water, and the temperature of the cooling water is prevented from excessively decreasing.

  In this specification, the two expressions of "turn on the water pump" and "drive the water pump" are used. "Turning on the water pump" means switching the water pump from a stopped state to a state in which cooling water can be circulated, and "driving the water pump" means turning on the water pump for a predetermined time. To maintain and circulate the cooling water (turn off after a predetermined time). In terms of circulating cooling water, the two parties are essentially in agreement.

  The cooling device for an internal combustion engine disclosed in this 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. The control device determines the drive time of the water pump and switches the water pump to the ON state when the detected value of the temperature sensor exceeds the first predetermined value. Further, 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 when switching the water pump to the on state. To provide.

  The above cooling device also sets a switching prohibition period that prohibits switching the water pump to the on state when the water pump is switched to the on state, so that the effect of driving the water pump (lowering of water temperature) is cooled. Until the water temperature is reflected, it is prohibited to switch the water pump on again. It is possible to prevent the temperature of the cooling water from being excessively lowered and to prevent the internal combustion engine from being overcooled, and it is possible to appropriately control the temperature change of the internal combustion engine.

The schematic of a cooling device is shown. The flowchart for demonstrating control of a water pump is shown. 9 shows a flowchart for determining the water pump drive time. 5 is a timing chart for explaining control of the water pump. 5 is a timing chart for explaining control of the water pump. The relationship between the load of the internal combustion engine and the water pump drive time is shown. The relationship between the load of the internal combustion engine and the switching prohibition period is shown. The temperature change of the cooling water when the cooling device of the example is used is shown.

  The main features of the embodiment are listed below. It should be noted that the technical elements described below are independent technical elements and exhibit technical usefulness alone or in various combinations.

  The cooling device disclosed in this specification is used for cooling 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 motorcycle. The cooling device includes a cooling water passage that connects the radiator and the internal combustion engine. Cooling water is sealed in the cooling water passage, and the cooling water circulates between the radiator and the internal combustion engine to cool the internal combustion engine. Further, the cooling device 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 the driving of the water pump (switching the water pump on and off).

  The control device switches the water pump from the off state to the on state when the detection value of the temperature sensor exceeds the first predetermined value. The control device also determines the drive time of the water pump when switching the water pump to the ON state. The controller drives the water pump for the determined drive time. The driving time of the water pump can be determined by a fixed value or the driving state of the internal combustion engine. Details of the driving time of the water pump will be described later. Note that, although not particularly limited, the temperature sensor detects the temperature of the cooling water every 8 to 50 msec, for example, every 32 msec, regardless of the on / off state of the water pump. In addition, although not particularly limited, the first predetermined value is set to 80 ° C. or higher and lower than 90 ° C., and is 85 ° C. as an example.

  The control device, when the water pump is switched to the ON state, provides a switching prohibition period in which it is prohibited to switch the water pump to the ON state regardless of whether or not the detected value of the temperature sensor exceeds the first predetermined value. . 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. Then, when the water pump is turned on, a switching prohibition period is provided. 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 lowered, the internal combustion engine is overcooled, and the combustion efficiency of the internal combustion engine is prevented from being reduced.

  Note that not only when the water pump is in the off state, even when the temperature sensor detects a temperature exceeding the first predetermined value during the driving of the water pump (when the water pump is in the on state), The drive time is not extended.

  Further, it is preferable that the switching prohibition period is set to be longer than the time from the start of driving the water pump to the start of the temperature decrease of the cooling water. 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 to the time when the water temperature of the cooling water 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. The fixed value is not particularly limited, but the length of the switching prohibition period can be set to 1 second or more and 6 seconds or less.

  Examples of driving conditions of the internal combustion engine include the engine speed, the injector injection time, the throttle opening, the intake pipe pressure, and other loads on the internal combustion engine. When determining the length of the switching prohibition period based on the driving state of the internal combustion engine, a map of the above-mentioned parameters relating 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. Alternatively, the drive time of the water pump can be calculated from a mathematical formula created based on the above-mentioned parameters relating to the internal combustion engine.

  Note that the control device may prohibit the driving of the water pump while the detection value of the temperature sensor is decreasing, in addition to the switching prohibition period or separately from the switching prohibition period. That is, in the case of “(previously detected value of temperature sensor) − (currently detected value of temperature sensor)> 0”, the drive of the water pump is prohibited even if the detected value of the temperature sensor exceeds the first predetermined value. can do.

  As described above, the drive time of the water pump is determined by a fixed value or the drive state of the internal combustion period. When the drive 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 to the ON state and the water pump is driven for a preset drive time (fixed value). Drive the pump. When the drive time of the water pump is a fixed value, the drive 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 to 0.3 seconds or more and 3.0 seconds or less. By setting the drive time of the water pump to 0.3 seconds or more, the drive time becomes longer than the shortest energization time determined by the performance of the motor that drives the water pump, and the water pump can be reliably driven. Further, by setting the driving time of the water pump to 3.0 seconds or less, it is possible to prevent the internal combustion engine from being overcooled.

  Further, the control device may determine the drive time of the water pump based on the drive state of the internal combustion engine. Examples of driving conditions of the internal combustion engine include the engine speed, the injector injection time, the throttle opening, the intake pipe pressure, and other loads on the internal combustion engine. When the drive time of the water pump is determined based on the drive state of the internal combustion engine, it is possible to previously create a map of the above-mentioned parameters relating to the internal combustion engine and the drive time and determine the drive time of the water pump based on the map . Alternatively, the drive time of the water pump can be calculated from a mathematical formula created based on the above-mentioned parameters relating to the internal combustion engine. Even when the drive time of the water pump is determined based on the drive state of the internal combustion engine, the drive time of the water pump is preferably longer than the shortest energization time determined by the performance of the motor that drives the water pump. Typically, the shortest energization time is 0.3 to 0.8 seconds, and one 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 set to the first value after the water pump is driven and before the water pump is turned on next (exceeds the first predetermined value). When a value exceeding the second predetermined value higher than the first predetermined value is detected, the water pump is driven for a longer time than the driving time determined based on the driving state of the internal combustion engine when the water pump is turned on next time. Good. Specifically, when the temperature sensor detects a value exceeding the second predetermined value after the detection value of the temperature sensor exceeds the first predetermined value and driving of the water pump is started for the nth time, the water of the (n + 1) th time is detected. The drive time of the pump is set longer than the drive time of the water pump determined based on the drive state of the internal combustion engine. That is, at 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 corrected to be long is driven. As a result, 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. The first correction 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, or may be a coefficient α to the drive time of the determined water pump. It may be a value calculated by multiplying (α> 1). The coefficient α can be appropriately selected from 1.05 or more and 1.50 or less, and 1.1 is given as an example.

  When determining the driving time of the water pump based on the driving state of the internal combustion engine, the temperature sensor is set to the first value after the water pump is driven and before the water pump is turned on next (exceeds the first predetermined value). When a value less than the third predetermined value lower than the first predetermined value is detected, the water pump is driven for a shorter time than the driving time determined based on the driving state of the internal combustion engine when the water pump is turned on next time. Good. Specifically, if the temperature sensor detects a value less than the third predetermined value after the detection value of the temperature sensor exceeds the first predetermined value and the driving of the water pump is started for the nth time, the water temperature of the (n + 1) th time is detected. The drive time of the pump is set shorter than the drive time of the water pump determined based on the drive state of the internal combustion engine. That is, at the (n + 1) th time, the second 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 corrected to be short is driven. As a result, it is possible to prevent the internal combustion engine from being overcooled.

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

  The cooling device 100 will be described with reference to FIG. 1. 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 arrow 14 direction. The 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 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. The control device to which the detection value of the temperature sensor 12 is sent may be different from the control device that controls the on / off of the water pump 6.

  The operation of the cooling device 100 will be described with reference to FIGS. 2 to 4. 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 the cooling device 100, after the engine 10 is started, the temperature sensor 12 detects the temperature of the cooling water every 32 ms (step S2). The detected temperature is sent to the controller 18.

  As shown in FIG. 4, the temperature of the cooling water rises as the engine 10 is driven (timing t0 to t1). The controller 18 compares the detection 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 of the cooling water is repeatedly detected by the temperature sensor 12 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. The drive time of the water pump 6 (WP drive time) 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 drive time will be described later.

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

  As described above, the cooling device 100 continues to measure the temperature of the cooling water regardless of the state (on state, off state) of the water pump 6, and when the temperature of the cooling water exceeds the first predetermined value, the water pump 6 Is turned on, and the operation of driving the water pump 6 is performed 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 when the driving of the water pump 6 is started, a period (switching prohibition period) for prohibiting turning on the water pump 6 even if 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 at timing t20. That is, in the flow of FIG. 2, when it is determined that the switching prohibition period is in step S6 (step S6: YES), it is determined that the temperature of the cooling water exceeds the first predetermined value in step S4 (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). If the temperature of the cooling water exceeds the first predetermined value and the switching prohibition period is not reached, first, in step S20, the WP drive time is determined based on the drive state of the engine 10. Next, it is determined whether or not the temperature of the cooling water has exceeded the second predetermined value since the water pump 6 was turned on last time (step S22). For example, at timings t3, t8, and t11 of FIG. 4, the temperature of the cooling water has not exceeded 95 ° C. (second predetermined value) since the water pump 6 was turned on last time (timing t1 to t3, t6 to t8). , T8 to t11, step S22: NO). Therefore, at timings t3, t8, and t11, the process proceeds to step S26.

  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, and the WP drive time determined based on the drive state of the engine 10 is corrected to be long, and the first corrected WP drive time is created. The controller 18 continues to drive the water pump 6 until the first corrected WP drive time (time W3 in FIG. 4) ends (steps S12 to S16 in FIGS. 2 and 3).

  Even at the timing t3, an appropriate WP drive time (time W2 in FIG. 4) is set based on the drive state of the engine 10 at that time. Similarly, at timing t6, an appropriate WP drive time is set based on the drive state of the engine 10 at that time. However, if a situation occurs where the load on the engine 10 increases after the timing t3 (for example, sudden acceleration, climbing, etc.), the temperature of the cooling water may exceed the second predetermined value as shown at the timing t4. obtain. In the cooling device 100, when the temperature of the cooling water exceeds the second predetermined value, when the water pump 6 is driven next time, 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 of step S26 onward in FIG. 3 will be continued. In step S26, it is determined whether or not the temperature of the cooling water has become lower than the third predetermined value since the water pump 6 was turned on last time. For example, at timings t3 and t8 in FIG. 4, the temperature of the cooling water is not lower than 75 ° C. (third predetermined value) since the water pump 6 was turned on last time (timings t1 to t3 and t6 to t8). (Step S26: NO). Therefore, at timings t3 and t8, the process proceeds to step S30. In this case, the water pump 6 continues to be driven until the WP drive time (time W2, W4 in FIG. 4) ends without correcting the WP drive time determined based on the drive state of the engine 10 (steps S12 to S16). ).

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

  The above control will be collectively described with reference to FIGS. 1 and 4. 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 off. At timing t1, the temperature sensor 12 detects a temperature equal to or higher than the first predetermined value. The controller 18 turns on the water pump 6 at the timing t1, and drives the water pump 6 for W1 time determined based on the driving state of the engine 10. At the same time, at 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 the timing t2), the temperature sensor 12 detects the temperature equal to or higher than the first predetermined value at the timing t3. The controller 18 turns on the water pump 6 at timing t3, and drives the water pump 6 for W2 determined based on the driving state of the engine 10. At the same time, at 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 end of the period D2 (after the timing t5), at the timing t6, the temperature sensor 12 detects the temperature exceeding the first predetermined value. The controller 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.). Therefore, at timing t6, the water pump 6 is driven for W3 time (first corrected WP drive time) in which the WP drive time is corrected to be long. At the same time, at timing t6, counting of the switching prohibition period (period D3) determined based on the driving state of the engine 10 is started. 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 the timing t7), at the timing t8, the temperature sensor 12 detects the 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 water pump 6 for W4 determined based on the driving state of the engine 10. At the same time, at timing t8, counting of the switching prohibition period (period D4) determined based on the driving state of the engine 10 is started. 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 the timing t10), the temperature sensor 12 detects the temperature exceeding the first predetermined value at the timing t11. The controller 18 turns on the water pump 6 at timing t11, and determines the WP drive time based on the drive 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 the timing t11, the water pump 6 is driven for W5 time (second corrected WP drive time) in which the WP drive time is corrected to be short. At the same time, at timing t11, counting of the switching prohibition period (period D5) determined based on the driving state of the engine 10 is started. During the period D5 (timings 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 drive time based on the drive state of the engine will be described. The horizontal axis of the graph represents the engine speed, and the vertical axis represents the WP drive time. Curves 30, 32, 34 and 36 show the WP drive time when the injector injection time is 2 msec, 4 msec, 6 msec and 8 msec, respectively. As shown in FIG. 6, as the engine speed increases (engine load increases), the WP drive time is set longer. Further, the WP drive time is set longer as the injector injection time becomes longer (engine load increases). Typically, as the engine load increases, the heat generation of the engine increases and the temperature of the cooling water also rises. Therefore, it is possible to prevent the temperature of the cooling water from rising excessively by setting the WP drive time longer as the load on the engine increases. Thus, the engine can be cooled efficiently by setting the WP drive time based on the load of the engine. The cooling device 100 determines the WP drive time based on the graph in FIG. 6 when the temperature sensor 12 detects a temperature exceeding the first predetermined value.

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

  The temperature change of the cooling water when the cooling device 100 is used will be described with reference to FIG. 8. The abscissa of FIG. 8 shows the engine drive time after the engine starts to be driven, and the ordinate shows the temperature of the cooling water (value detected by the temperature sensor). A curve 50 shows the result of using the cooling device 100, that is, the result of providing the switching prohibition period at the same time as the driving of the water pump 6. A 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 the switching prohibition period, and the temperature of the cooling water is the first predetermined temperature. The result shows that the water pump is driven for a predetermined time when the temperature exceeds the value. 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 make the temperature fluctuation of the cooling water smaller than that of 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. As described above, the temperature of the cooling water is detected regardless of the driving state of the water pump, and the switching prohibition period is provided to prohibit the driving of the water pump even if the temperature of the cooling water exceeds the first predetermined value. It was confirmed that the supercooling of the engine could be suppressed and the temperature change of the engine could be suppressed.

  As described above, at the same time as the water pump is driven, the effect of driving the water pump can be obtained by providing the period (switching prohibition period) in which it is prohibited to turn on the water pump again regardless of the detected value of the temperature sensor. It is possible to prevent the water pump from being restarted before being reflected in the temperature change of the water pump. As a result, it is possible to prevent the temperature of the cooling water from dropping excessively and the engine from being overcooled. Further, if the temperature of the cooling water exceeds the predetermined value (second predetermined value) from the previous water pump drive to the current water pump turn-on, the current water pump drive is lengthened, The heat stored in the engine can be removed. Furthermore, if the temperature of the cooling water falls below a predetermined value (third predetermined value) between the previous water pump drive and the current water pump turn-on, by shortening the current water pump drive, It is possible to prevent the engine from being overcooled. Further, the temperature change of the cooling water can be reduced by determining the switching prohibition period and the WP drive time according to the driving state of the engine when the water pump is turned on.

  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 switching prohibition period D and the second prohibition period E are provided. As shown in FIG. 5, during the switching prohibition period D (to timing t31), even if the detection value of the temperature sensor exceeds the first predetermined value (85 ° C.), the water pump is not driven (timing t30). In the example shown in FIG. 5, after the switching prohibition period D ends, the temperature of the cooling water exceeds the first predetermined value at timing t32. However, the water temperature at the timing t32 is lower than the water temperature at the timing t30. That is, the temperature of the cooling water continues to drop even 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. Therefore, the period between “(previously detected value of temperature sensor) − (currently detected value of temperature sensor)> 0” is set as the second switching prohibition period E, and switching of the water pump to the ON state is prohibited. The second switching prohibition period E is when the temperature rise of the cooling water is confirmed as at timings t33 and 34, that is, "(previously detected value of temperature sensor)-(presently detected value of temperature sensor). When ≦ 0 ”is confirmed, the process ends. 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). The supercooling of the engine can be suppressed also by providing the second switching prohibition period E.

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

  Although the embodiments of the present invention have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. Further, the technical elements described in the present specification or the drawings exert technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technique illustrated in the present specification or the drawings achieves a plurality of purposes at the same time, and achieving the one purpose among them has technical utility.

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

Claims (4)

A radiator and an internal combustion engine are connected, and a cooling water passage through which cooling water circulates,
A temperature sensor that detects the temperature of the cooling water,
A water pump that circulates cooling water,
A control device that determines a drive time of the water pump and switches the water pump to an ON state when the detected value of the temperature sensor exceeds a first predetermined value;
Is equipped with
The controller is
When switching the water pump to the ON state, a switching prohibition period is provided to prohibit 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.
Determine the drive time of the water pump based on the drive state of the internal combustion engine,
When the temperature sensor detects a value higher than the first predetermined value and exceeds the second predetermined value, the water pump is driven next time for a time longer than the driving time determined based on the driving state of the internal combustion engine. A cooling device for an internal combustion engine that drives a pump . A radiator and an internal combustion engine are connected, and a cooling water passage through which cooling water circulates,
A temperature sensor that detects the temperature of the cooling water,
A water pump that circulates cooling water,
A control device that determines a drive time of the water pump and switches the water pump to an ON state when the detected value of the temperature sensor exceeds a first predetermined value;
Is equipped with
The controller is
When the water pump is switched to the on state, a switching prohibition period is provided to prohibit switching of the water pump to the on state regardless of whether or not the detected value of the temperature sensor exceeds the first predetermined value.
Determine the drive time of the water pump based on the drive state of the internal combustion engine,
When the temperature sensor detects a value lower than the first predetermined value and less than the third predetermined value, when the water pump is driven next time, the water time is shorter than the drive time determined based on the drive state of the internal combustion engine. A cooling device for an internal combustion engine that drives a pump. Controller, the cooling system of an internal combustion engine according to claim 1 or 2 for determining the length of the switching prohibition period based on a drive state of the internal combustion engine. Controller, while the detected value of the temperature sensor is decreased, claim 1 for inhibiting the switching to the ON state the water pump irrespective of whether or not the detected value of the temperature sensor exceeds a first predetermined value the cooling system of an internal combustion engine according to any one of 3.

Images