JP2010065608A - Cooling system of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling system of an internal combustion engine for preventing the internal combustion engine from reaching an excessive temperature rise. <P>SOLUTION: This cooling system of the internal combustion engine includes a circulating passage 2 for circulating cooling water of the internal combustion engine, a water pump 3 for circulating this cooling water, a temperature detecting means (a water temperature sensor 11) for detecting the temperature of the cooling water of the internal combustion engine, a setting means 71 for setting a driving degree of the water pump in response to the temperature of the cooling water detected by the water temperature sensor, and a control means 72 for driving the water pump in response to this driving degree. This cooling system intermittently drives the water pump in response to the driving degree. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a cooling device for an internal combustion engine.

  As a known example of a cooling device for an internal combustion engine, for example, Patent Document 1 can be cited. The engine cooling device described in Patent Document 1 includes a mechanical water pump provided in a cooling water circulation path and connected to an engine crankshaft via a clutch, and an electric water pump provided in the cooling water circulation path. ing. Then, the driving of the clutch and the electric water pump is controlled according to the load information of the engine so that the electric water pump is driven when the engine is lightly loaded and the electric water pump and the mechanical water pump are driven when the engine is heavily loaded. It is.

JP-A-2004-293430 (Claims 1 and 2, FIG. 1, etc.)

  However, in the engine cooling device, the water pump is not turned on until the temperature of the cooling water detected by the water temperature sensor reaches a predetermined temperature. For this reason, until the water pump is turned on, the water temperature rises while the cooling water stays in the engine water jacket, and the engine may excessively rise in temperature.

  Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art and to provide a cooling device for an internal combustion engine that prevents the internal combustion engine from excessively rising in temperature.

  The cooling device for an internal combustion engine of the present invention includes a circulation path through which cooling water for the internal combustion engine circulates, a water pump for circulating the cooling water, temperature detection means for detecting the temperature of the cooling water for the internal combustion engine, and the temperature It is characterized by comprising setting means for setting the driving degree of the water pump according to the temperature of the cooling water detected by the detecting means, and control means for driving the water pump according to the driving degree.

  In the present invention, the temperature of the cooling water can be gradually changed by using the cooling water temperature as a control variable and changing the driving degree of the water pump according to the control variable. Therefore, it is possible to suppress an excessive temperature rise of the internal combustion engine. The “driving degree” of the water pump here may be other than the driving time and driving rate described later as long as it is a means / method capable of increasing / decreasing the capacity of the water pump.

  It is preferable that the setting means sets a driving time for driving the water pump as the driving degree. Thus, by setting the drive time for driving the water pump as the drive degree, it is possible to easily suppress an excessive temperature rise of the internal combustion engine.

  When the temperature of the cooling water is within a predetermined range, the setting means preferably sets the driving time longer as the temperature increases. With this configuration, it is possible to more reliably suppress an excessive temperature increase of the internal combustion engine.

  Preferably, the setting means sets the drive time longer as the load on the internal combustion engine increases. In this way, the load of the internal combustion engine is used as a control variable in addition to the cooling water temperature, and the drive time is increased as the load is higher, so that the drive time of the water pump can be set more accurately. It is possible to more reliably suppress the temperature rise.

  Here, it is preferable that the setting means sets the driving time longer as the rotational speed of the internal combustion engine as a load of the internal combustion engine becomes higher. Thereby, the drive time of a water pump can be set still more accurately, and the excessive temperature rise of an internal combustion engine can be suppressed much more reliably.

  A heater is provided in the circulation path, and the setting means may set the lower limit of the predetermined temperature range lower when the heater is on than when the heater is off. preferable. Thus, when the heater is on, the lower limit of the predetermined temperature range is set to a low value so that the water temperature is lower than the predetermined temperature so that the cooling water (hot water) can flow into the heater. Heating performance can be secured more quickly.

  According to the cooling apparatus for an internal combustion engine of the present invention, it is possible to achieve an excellent effect that an excessive temperature increase of the internal combustion engine can be prevented.

  Hereinafter, the configuration of the cooling device for the internal combustion engine in the present embodiment will be described with reference to FIG. The engine (internal combustion engine) 1 is provided with a water jacket (not shown) through which cooling water for cooling the engine flows. The water jacket is provided with a circulation path 2 that connects the water inlet and outlet of the water jacket and circulates the cooling water. A water pump 3 for circulating the cooling water is provided in the circulation path 2 near the water outlet of the water jacket. In the present embodiment, only the water pump 3 is provided as the water pump, and it is not necessary to provide two water pumps. Therefore, the cost can be reduced. As the water pump 3, a water pump with an electromagnetic clutch is used in the present embodiment, but is not limited thereto.

  In addition, a radiator 4 is interposed in the circulation path 2, and cooling water (hot water) flowing out from the engine 1 flows into the radiator 4, is cooled by the radiator 4, and re-enters the engine 1 through the water pump 3. Is configured to do. In the circulation path 2, a throttle body 5 and a cabin heater 6 are interposed on the upstream side of the radiator 4. Cooling water (warm water) flowing out from the engine 1 passes through the throttle body 5 and the cabin heater 6, It is configured to flow into the water pump 3. That is, the upstream side of the circulation path 2 from the engine 1 to the radiator 4 functions as a hot water passage, and the hot water flows into the throttle body 5 and the cabin heater 6.

  An engine control unit (ECU) 7 for controlling the engine 1 is connected to the water pump 3. The ECU 7 is connected to the engine 1 and various devices for controlling the engine 1. Here, the ECU 7 is connected to the water pump 3 and the cabin heater 6 for explanation, and a water temperature sensor 11 described later. The description is omitted except that it is connected to the throttle opening sensor 12.

  The water temperature sensor 11 is provided in the vicinity of the water outlet of the water jacket in the circulation path 2, measures the temperature of the cooling water flowing out from the engine 1, and sends a signal SG 1 indicating this water temperature to the ECU 7. A throttle opening sensor 12 that measures the opening of a throttle valve (not shown) provided in the throttle body 5 sends a signal SG2 indicating the throttle opening to the ECU 7.

  The ECU 7 changes and sets the drive degree of the water pump 3 according to the water temperature measured by the water temperature sensor 11, and controls the circulation of the cooling water by driving the water pump 3 according to this drive degree. And a control means 72. The setting means 71 and the control means 72 are used to control the coolant so as to circulate appropriately in the circulation path 2 and adjust the temperature of the engine 1. Thus, by adjusting the driving degree of the water pump 3 according to the water temperature, the amount of water flowing through the circulation path 2 can be adjusted, and the water temperature in the circulation path 2 can be gradually raised or lowered. In the present embodiment, the internal combustion engine can be prevented from reaching an excessive temperature rise.

  Here, the drive degree refers to drive time. Thus, by selecting the time as the driving degree, the driving degree can be easily set. In particular, in the present embodiment, a control cycle is set, and the degree of drive means the ratio of the drive time of the water pump in each control cycle, that is, the drive rate (drive time / one control cycle (time)). By providing the control cycle in this way, it is possible to set the drive of the water pump as appropriate between the operation of the engine and the stop of the engine. A specific example of the driving rate will be described with reference to FIG. FIG. 2 is a graph showing the driving of the water pump, in which the horizontal axis represents time and the vertical axis represents the on / off state of the water pump. In FIG. 2, during the first control period, the water pump 3 is driven for T / 4 seconds during the first control period T seconds. Therefore, the drive rate of the water pump 3 in the first control cycle is 25%. Similarly, the drive rate of the water pump 3 is 50% during the second control cycle, the drive rate of the water pump 3 is 75% during the third control cycle, and the water pump during the fourth control cycle. The driving rate of 3 is 100%. As described above, the water pump 3 is intermittently driven by changing the driving rate, whereby the cooling water in the circulation path 2 gradually flows and the water temperature gradually changes. As a result, a sudden change in the water temperature can be prevented, and the water temperature sensor 11 can also measure the temperature appropriately.

  In each control cycle, the ECU 7 sets the drive rate during the control cycle according to the water temperature at the beginning of each control cycle by the setting means 71, and according to the drive rate set during the control cycle by the control means 72. Control is performed to drive the water pump 3 (pulse width modulation). Thus, since the drive rate as a drive degree is set for every control period and the drive rate is set according to water temperature, the excessive rapid rise and fall of water temperature can be relieved.

  The control by the ECU 7 will be described in detail using the flowchart shown in FIG. First, when the engine 1 is started as step S1, initialization is performed (step S2). In the initial setting, the timer recorded in the ECU 7 is reset and the flag indicating that the control cycle is in progress is turned off.

  Next, the process proceeds to step S3, and it is determined whether or not the control period is in effect depending on whether or not the flag indicating that the control period is on. When the flag is off (NO), it is a setting period for setting the driving degree, and the process proceeds to step S4. When the flag in the control cycle is ON (YES), the process proceeds to step S11 described later.

  In step S4, whether or not the water temperature is equal to or lower than the first set water temperature is determined based on whether or not the signal SG1 indicating the water temperature from the water temperature sensor 11 is equal to or higher than a predetermined value. When the temperature is equal to or lower than the first set water temperature (YES), it indicates that the cooling water from the engine 1 is low temperature, which indicates that the engine is not high temperature. Therefore, it is not necessary to circulate the cooling water during the control cycle. In this case, the process proceeds to step S5, and the drive time for driving the water pump 3 with respect to the control cycle is set to zero. If the water temperature is higher than the first set water temperature in step S4 (NO), the process proceeds to step S6.

  In step S6, it is determined whether or not the engine load is equal to or less than a predetermined value based on whether or not the signal SG2 indicating the throttle position from the throttle position sensor 12 is equal to or less than a predetermined value. Note that the predetermined value in step S6 is set according to a control variable described later, and when there are one or more control variables, the predetermined value is determined according to each control variable. Some of the control variables do not have the predetermined value (for example, an on / off signal of the cabin heater 6 as a control variable). In this case, step S6 may be omitted.

  If the throttle opening of the throttle body is higher than the predetermined value in step S6 (NO), the engine 1 is likely to be hot because the engine load is high. Therefore, when the throttle opening is higher than the predetermined value, the process proceeds to step S7, and the drive time for driving the water pump 3 to make the coolant constantly circulate during the control cycle is the same as the control cycle (time). . If the throttle opening is equal to or smaller than the predetermined value in step S6 (YES), the process proceeds to step S8.

  In step S8, it is determined whether the water temperature is lower than the second set water temperature. When the water temperature is equal to or higher than the second set water temperature (NO), it is considered that the engine 1 is at a high temperature because the cooling water of the engine 1 is at a high temperature. Therefore, since it is necessary to circulate the cooling water constantly during the control cycle, the process proceeds to step S7, and the drive time for driving the water pump 3 is made the same as the control cycle.

  On the other hand, if the water temperature is lower than the second set water temperature in step S8 (YES), it indicates that the engine is not so hot. Therefore, in this case, the process proceeds to step S9, and the drive rate in the control cycle is set to drive the water pump 3 intermittently.

  In step S9, the driving rate is determined from the map. Here, as a map, for example, there is a map as shown in FIG. 4, and the driving rate as a gain is set according to the water temperature and the engine load (signal SG2 indicating the throttle opening). In the map shown in FIG. 4, the drive rate is set to increase as the water temperature increases and as the throttle opening increases. For example, at the temperature Ta load Da shown in FIG. 4, the drive rate is 0.1, and at the temperature Tb (Tb> Ta) load Da, the drive rate is 0.4. When the drive rate is set from the water temperature and the engine load obtained in steps S4 and S6 described above, the process proceeds to step S10.

  In step S10, the drive time is calculated from the set drive rate and control cycle. That is, the setting means 71 sets the driving rate by each step from the above-described steps S4 to S10, and calculates the driving time. Thereafter, the drive of the water pump is controlled by the control means 72 in accordance with this drive rate.

  If drive time is set by step S5, S7, S10, it will progress to step S11. In step S11, it is determined whether or not the timer exceeds the control cycle. If the control period has been exceeded (YES), the period is the setting period for setting the drive rate in the next control period, and the process returns to the initial setting in step S2. If it is within the control cycle (NO), the process proceeds to step S12.

  In step S12, whether or not the driving time is in progress is determined by whether or not the timer is within the driving time. When the timer exceeds the drive time (NO), that is, when it is the stop time, the process proceeds to step S13, the control means 72 sends a non-drive signal of the water pump 3 to the water pump 3, and the water pump 3 Stop. If it is within the drive time (YES), the process proceeds to step S14, and the control means 72 sends a drive signal for the water pump 3 to the water pump 3 to drive the water pump 3. It progresses to step S15 after step S13 and step S14.

  In step S15, the flag in the control cycle is turned on, and the process returns to step S3. When the process returns to step S3, since the flag in the control cycle is ON (YES), the process proceeds to step 11 and the water pump 3 is driven by the control means 72 according to the drive rate set by the setting means 71. Alternatively, the water pump 3 is stopped and the process returns to step S3.

  That is, in this embodiment, when the engine is started (step S1) and the initial setting is made (step S2), it is determined that the drive rate is set (step S3), and the drive rate of the water pump 3 is set. Then, the drive time is calculated (steps S4 to S10). Then, it is determined that it is in the control cycle (step S11), and it is further determined whether it is within the driving time (step S12). If it is within the drive time, the water pump 3 is driven (step S14), and if it is during the stop time, the water pump 3 is stopped (step S13). Thereafter, since the flag in the control cycle is turned on (step S15), when returning to step 3, it is determined that the control cycle is in progress, and the process proceeds to step S11. Then, the processes of steps S12 to S15 and S3 are repeated, and when it is determined that the timer has exceeded the control period and the control period has ended (step S11), the process returns to step S2, the initial setting is performed, and the next control period is reached. Setting is made in steps S4 to S10. This is repeated until the engine stops.

  By controlling the engine cooling device as described above, in this embodiment, the water pump 3 can be driven intermittently as shown in FIG. 2, and is adjusted to the engine state (cold state, warm-up state). Thus, the cooling water can be circulated, and in this case, the temperature of the cooling water can be gradually adjusted, so that an excessive temperature rise of the internal combustion engine can be effectively prevented.

  In the above-described embodiment, the throttle opening is detected as the load of the engine 1, and the drive rate is determined in step S9 from the map of the load and the water temperature. The driving rate may be determined from the rate and the on / off signal of the cabin heater 6. That is, the driving rate can be determined by combining at least two selected from the water temperature, the engine speed as the engine load, the throttle opening, and the heater on / off signal. Preferably, the driving rate is determined from the water temperature, at least one selected from the throttle opening, the rotational speed of the engine, the on / off signal of the cabin heater 6 and the vehicle speed. For example, a case where an on / off signal of the cabin heater 6 is applied as a control variable in addition to the throttle opening as a load will be described with reference to a map shown in FIG.

  In the map shown in FIG. 5, as compared with the map shown in FIG. 4, the driving rate generally increases on the low temperature side. That is, the driving rate is 0.1 at the temperature Ta and the load Da shown in FIG. 4, whereas the driving rate is about 0.5 at the temperature Ta and the load Da in FIG. As described above, when the switch of the cabin heater 6 is in the ON state, by increasing the driving rate of the water pump 3, the cooling water (hot water) circulates in the circulation path 2 to ensure the heating performance. In particular, since the drive rate of the pump is set even in a water temperature range lower than that in FIG. 4 (temperature Ta or lower), even if the water temperature is low, the water pump 3 is driven and the hot water is temporarily used as the cabin heater 6. It is possible to flow in.

  In addition, when all of the water temperature, the throttle opening, the rotation speed of the engine 1, and the vehicle speed are set as control variables, the driving rate is determined from the map of FIG. 6 as an example, and the driving rate is further corrected by the vehicle speed. You may decide. According to the map of FIG. 6, the vertical axis indicates the load (throttle opening), the right horizontal axis indicates the engine speed, and the left horizontal axis indicates the water temperature. The throttle opening, engine speed, and water temperature are high. The drive rate is set so as to increase. In this way, the control accuracy increases by increasing the control variables.

  In the present embodiment, the drive rate is determined only when the control variable is equal to or smaller than the predetermined value in step S6. However, step S6 can be omitted. For example, when the engine speed is adopted as the control variable, step S6 may be omitted, and the engine speed may be acquired and the map referred to in step S9.

  In addition, with this configuration, in this embodiment, it is possible to control the flow rate of the cooling water without using a thermostat. That is, conventionally, although each water pump itself has a flow rate controllability, the water pump is operated continuously and the flow rate is controlled by a thermostat. It is possible to control the flow rate without using a thermostat. By not using the thermostat in this way, not only the number of parts is reduced, but also the valve opening response delay when using the thermostat does not occur, so it is possible to efficiently prevent the engine from becoming hot and suppress knocking. it can.

  The internal combustion engine cooling device of the present invention can be used in the automobile manufacturing industry.

It is a figure which shows the structure of the cooling device of an internal combustion engine. It is a figure which shows the drive of a water pump. It is a flowchart explaining the flow of control by ECU. It is a figure for demonstrating the map used by step S10. It is a figure for demonstrating another form of a map. It is a figure for demonstrating another form of a map.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2 Circulation path 3 Water pump 4 Radiator 5 Throttle body 6 Cabin heater 11 Water temperature sensor 12 Throttle opening sensor 71 Setting means 72 Control means

Claims (6)

A circulation path through which the cooling water of the internal combustion engine circulates;
A water pump for circulating the cooling water;
Temperature detecting means for detecting the temperature of the cooling water of the internal combustion engine;
Setting means for setting the drive degree of the water pump according to the temperature of the cooling water detected by the temperature detection means;
A cooling device for an internal combustion engine, comprising: control means for driving the water pump according to the driving degree. 2. The cooling apparatus for an internal combustion engine according to claim 1, wherein the setting means sets a driving time for driving the water pump as the driving degree. 3. The cooling apparatus for an internal combustion engine according to claim 2, wherein when the temperature of the cooling water is within a predetermined temperature range, the setting means sets the drive time longer as the temperature becomes higher. . 4. The cooling apparatus for an internal combustion engine according to claim 3, wherein the setting means sets the drive time longer as the load on the internal combustion engine increases. 5. The cooling apparatus for an internal combustion engine according to claim 4, wherein the setting means sets the drive time longer as the rotational speed of the internal combustion engine as a load of the internal combustion engine increases. A heater is provided in the circulation path, and the setting means sets the lower limit of the predetermined temperature range lower when the heater is on than when the heater is off. The cooling device for an internal combustion engine according to any one of claims 3 to 5, wherein the cooling device is an internal combustion engine.