JP2011214566A - Cooling device for on-vehicle internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling device for an internal combustion engine, capable of suppressing the progress of thermal fatigue in each part of the cooling device including a cylinder head and a cylinder block such as a cylinder bore while suppressing the temperature drop of the cylinder bore whose temperature has risen in a circulation stop period of cooling water to improve fuel economy by suppressing the sudden temperature fluctuation in a circulating path of cooling water when releasing the circulation stop of cooling water.SOLUTION: The cooling device 20 for the internal combustion engine includes a water pump 23 capable of stopping the discharge of cooling water without depending on engine speed, and stops driving of the water pump 23 when an outlet water temperature is lower than a predetermined temperature in engine warming-up. The cooling device 20 further includes an inlet water temperature sensor 72 for detecting an inlet water temperature, and a flow regulating valve 50 regulating to make lower the flow rate of the cooling water flowing into a water jacket 61 as the inlet water temperature is lower after the discharge start of cooling water by the water pump 23.

Description

  The present invention relates to a cooling device for an in-vehicle internal combustion engine that cools an internal combustion engine by circulating cooling water discharged from a water pump through a cooling water circulation path such as a water jacket.

  For example, Patent Document 1 employs an electric water pump as a water pump that discharges cooling water to a cooling water circulation path, and the temperature of the cooling water detected by a water temperature sensor reaches a predetermined temperature when the engine is warmed up. Until now, the water pump is stopped and the circulation of the cooling water in the circulation path is stopped. According to such a cooling device, since the internal combustion engine is not cooled by the cooling water when the engine is cold, the engine warm-up can be promoted, and the fuel consumption is improved due to the early stabilization of the combustion state and the reduction of heat loss. Can be achieved.

JP 2009-216028 A

  By the way, when the cooling water is started to circulate through the circulation path from the state where the circulation of the cooling water is stopped by stopping the driving of the water pump when the engine is warmed up in this way, Then, low-temperature cooling water staying in a portion other than the water jacket flows into the water jacket. For this reason, the cylinder bore whose temperature has increased during the cooling water circulation stop period is cooled, and the heat loss temporarily increases. This increase in the heat loss becomes a factor that hinders the improvement in fuel consumption. Furthermore, as the low-temperature cooling water flows into the water jacket in this way, the high-temperature cooling water whose temperature has risen in the water jacket flows into the other low-temperature parts of the circulation path. Since the stop / execution of the circulation of the cooling water is repeated, a large temperature change occurs in the cylinder bore, the piping through which the cooling water flows, or the heat exchanger provided in the circulation path, so that thermal stress is repeatedly generated in them. There is a possibility that thermal fatigue due to a phenomenon, that is, a thermal cycle, proceeds.

  The present invention has been made in view of such a conventional situation, and an object of the present invention is to circulate the cooling water by suppressing a sudden temperature fluctuation in the circulation path of the cooling water when releasing the circulation stop of the cooling water. An object of the present invention is to improve the fuel consumption by suppressing the temperature drop of the cylinder bore that has risen during the stop period, and to suppress the progress of thermal fatigue in each part of the cooling device including the cylinder head such as the cylinder bore and the cylinder block.

In the following, means for achieving the above object and its effects are described.
The invention according to claim 1 is a water pump capable of stopping the discharge of cooling water without depending on the engine speed, the water jacket and the cooling water flowing out of the water jacket being returned to the water pump and discharged from the pump. An engine warm-up comprising a circulation path including at least an external passage for allowing the cooled water to flow into the water jacket again, and an outlet water temperature sensor for detecting the temperature of the cooling water flowing out from the water jacket to the external passage. When the cooling water temperature detected by the outlet water temperature sensor is less than a predetermined temperature, the cooling system of the on-vehicle internal combustion engine that stops driving the water pump and stops the circulation of the cooling water in the circulation path from the external passage An inlet water temperature sensor for detecting the temperature of the cooling water flowing into the water jacket; When starting the circulation of the cooling water by driving the data pump, the flow rate is set so that the amount of cooling water flowing into the water jacket from the external passage decreases as the cooling water temperature detected by the inlet water temperature sensor is lower. The gist is to provide a flow rate control means for controlling.

  In this invention, when driving the water pump to start circulation of the cooling water, the temperature of the cooling water flowing into the water jacket from the external passage is detected by the inlet water temperature sensor, and the lower the detected cooling water temperature, This is controlled through the flow rate control means so that the amount of cooling water flowing from the external passage into the water jacket is reduced. As a result, the temperature of the cylinder bore suddenly drops due to a large amount of low-temperature cooling water flowing into the water jacket from the external passage, or the cooling due to a large amount of high-temperature cooling water flowing from the water jacket into the external passage. The rapid temperature rise of the apparatus can be suppressed. Accordingly, it is possible to improve the fuel consumption and to suppress the progress of thermal fatigue in each part of the cooling device including the cylinder head such as the cylinder bore and the cylinder block.

  According to a second aspect of the present invention, in the cooling device for an on-vehicle internal combustion engine according to the first aspect, the flow rate control means is detected by the outlet water temperature sensor when the water pump is driven to start circulation of the cooling water. The gist is to control the flow rate so that the amount of cooling water flowing into the water jacket from the external passage increases as the temperature of the cooling water to be increased.

  As described above, fuel consumption can be improved by controlling the flow rate so that the amount of cooling water flowing from the external passage into the water jacket decreases as the cooling water temperature detected by the inlet water temperature sensor decreases. It is possible to suppress the progression of thermal fatigue in each part of the cooling device including the cylinder head such as the cylinder bore and the cylinder block. However, in this way, when the flow rate is controlled so that the amount of cooling water flowing into the water jacket from the external passage is reduced, that is, when the flow rate of the cooling water circulating in the circulation path is limited, the cooling water temperature of the water jacket is There is a concern that local boiling of the cooling water may occur in the vicinity of the cylinder bore.

  In this regard, the flow rate is controlled so that the amount of cooling water flowing into the water jacket from the external passage decreases as the cooling water temperature detected by the inlet water temperature sensor is lower, while the cooling water temperature detected by the outlet water temperature sensor is lower. According to the invention of claim 2, the flow rate is controlled so that the amount of cooling water flowing into the water jacket from the external passage increases as the height increases. According to the invention of claim 2, the cooling water in the water jacket is adopted. This can also be suitably avoided for local boiling.

  According to a third aspect of the present invention, in the cooling device for an on-vehicle internal combustion engine according to the first or second aspect, the external passage is heat provided downstream of the outlet water temperature sensor and upstream of the inlet water temperature sensor. The gist is to include an exchanger.

  Assuming that the amount of cooling water staying in the external passage is very small, even if the cooling water in the external passage flows into the water jacket when the water pump is driven to start circulation of the cooling water, The impact is considered to be relatively small. That is, even if all the low-temperature cooling water staying in the external passage flows into the water jacket in a short period of time, the heat capacity of the entire cooling water is small, so that the temperature of the cooling water of the entire water jacket is greatly reduced. In addition, the temperature of the cylinder bore does not drop suddenly.

  However, in actuality, in the cooling device for an on-vehicle internal combustion engine, an external passage has to be disposed under a situation where various restrictions exist, so that the length becomes long, and the flow resistance is further reduced. Since it is necessary to set the flow path area as large as possible, the heat capacity inevitably increases. That is, the amount of cooling water staying in the external passage, and hence the heat capacity thereof, is not negligible as described above, and particularly when the heat exchanger is provided in the external passage, the heat capacity is further increased. . For this reason, the bad influence resulting from the inflow of the low-temperature cooling water staying in the external passage as described above into the water jacket is unavoidable. Further, when the heat capacity of the cooling water staying in the external passage including the heat exchanger is increased in this way, the water jacket depends on the cooling water temperature in the external passage before starting the circulation of the cooling water and the circulation amount of the cooling water after the circulation starts. The temperature of the cooling water flowing into the water will change in various ways. As a result, the necessity of appropriately setting the circulation amount of the cooling water in accordance with such a temperature transition is naturally increased.

  According to the present invention, such an adverse effect that the low-temperature cooling water staying in the external passage flows into the water jacket is unavoidable, and the temperature of the cooling water flowing into the water jacket varies from time to time. Even if it changes, the cooling water temperature is detected by the inlet water temperature sensor, and the amount of cooling water flowing into the water jacket from the external passage can be controlled based on the detection result. For this reason, rapid cooling of the cylinder bore due to a large amount of low-temperature cooling water flowing into the water jacket from the external passage, or cooling due to a large amount of high-temperature cooling water flowing from the water jacket into the external passage A sudden temperature change at each part of the apparatus can be suppressed. Therefore, the fuel consumption can be further improved, and the progress of thermal fatigue in each part of the cooling device including the cylinder head such as the cylinder bore and the cylinder block can be suitably suppressed. Incidentally, such a heat exchanger is formed inside a throttle body in which a heater core of a heater device for heating a vehicle interior, an EGR cooler for cooling EGR gas flowing in an EGR passage of the EGR device, a throttle valve, and the like are incorporated. And a temperature rising passage through which cooling water flows.

  The flow rate control means adjusts the flow rate of the cooling water flowing from the external passage into the water jacket by changing the cross-sectional area of the flow passage provided in the external passage as in the invention described in claim 4. It can be embodied by a configuration including a flow rate control valve and a control unit that controls the opening degree of the flow rate control valve based on the coolant temperature detected by the inlet water temperature sensor.

  According to a fifth aspect of the present invention, in the on-vehicle internal combustion engine cooling device according to the fourth aspect, the water pump is an engine-driven water pump whose rotational shaft is drivingly connected to the engine output shaft via a clutch. The gist of the invention is that when the clutch is released, the clutch is stopped, and when the clutch is engaged, the clutch is engaged.

  In the engine-driven water pump, the coolant discharge amount is uniquely determined by the rotational speed of the engine output shaft. In other words, the circulation amount of the cooling water in the circulation path is determined regardless of the temperature distribution state of the cooling water staying in the water jacket and other circulation paths. For this reason, when the engine speed is increased by the driver's accelerator operation when driving the water pump and starting the circulation of the cooling water, the circulation amount of the cooling water is accordingly the temperature of the cooling water staying in the circulation path. The problem increases with an abrupt temperature change in the circulation path as described above, and becomes more serious regardless of the distribution state.

  According to the present invention, even when the engine-driven water pump is employed as described above, the water pump discharge amount is substantially finely controlled through the opening adjustment of the flow rate control valve provided in the external passage. The amount of cooling water flowing into the water jacket from the external passage can be controlled based on the cooling water temperature detected by the inlet water temperature sensor. As a result, even when the engine-driven water pump is adopted, when the water pump is driven to start the circulation of the cooling water, the rapid temperature change of the cooling water in the circulation path including the water jacket is suppressed. can do. Therefore, the fuel consumption can be improved, and the progress of thermal fatigue in each part of the cooling device including the cylinder head such as the cylinder bore and the cylinder block can be suppressed.

  The invention according to claim 6 is the cooling device for the on-vehicle internal combustion engine according to any one of claims 1 to 5, wherein a radiator passage for circulating cooling water between the water jacket and the radiator; When the radiator passage is connected and the temperature of the cooling water in the water jacket is lower than a predetermined valve opening temperature, the valve passage closes the radiator passage by the valve body and prohibits the cooling water from flowing into the radiator. A thermostat that allows the radiator passage to communicate with the valve element when the temperature is equal to or higher than the valve opening temperature, and allows the cooling water to flow into the radiator, and the flow rate control means detects the cooling water temperature detected by the outlet water temperature sensor. Is to start the flow rate control from a temperature range lower than the valve opening temperature.

  In the present invention, the flow rate control as described above is started from a temperature range where the cooling water temperature is lower than the opening temperature of the thermostat. Therefore, the water pump is driven when the cooling water temperature is low when the thermostat is closed. Thus, when the circulation of the cooling water is started, a rapid temperature change of the cooling water in the circulation path including the water jacket can be suppressed.

  The invention according to claim 7 is the cooling system for an on-vehicle internal combustion engine according to any one of claims 1 to 6, wherein the external passage is on the downstream side of the outlet water temperature sensor and on the upstream side of the inlet water temperature sensor. A heater core that heats up the air in the vehicle interior by the heat of the cooling water, and that blows the heated air into the vehicle interior; and the air volume of the heater blower is set to the cooling water temperature detected by the outlet water temperature sensor. The gist is to further include a heater device that is set based on the above.

  The heater device mounted on the vehicle is set based on the cooling water temperature detected by the outlet water temperature sensor. For this reason, when the water pump is driven to start circulation of the cooling water, if a large amount of cooling water may flow into the water jacket from the external passage in a short period of time, the water jacket flows out of the water jacket and the outlet water temperature Since the cooling water temperature detected by the sensor temporarily decreases significantly, the air flow of the heater blower temporarily decreases accordingly, in other words, there is a concern that the air flow of the heater blower becomes unstable. The

  In this respect, according to the present invention, when the water pump is driven to start the circulation of the cooling water, the temperature of the cooling water flowing out from the water jacket to the external passage and contacting the outlet water temperature sensor rapidly decreases. It is possible to suppress the air volume of the heater blower from becoming unstable as described above.

  The invention according to claim 8 is the cooling apparatus for the on-vehicle internal combustion engine according to any one of claims 1 to 7, wherein a part of the exhaust gas from the exhaust system is introduced into the intake system as EGR gas and recirculated. An EGR device is further provided, and the recirculation of the EGR gas by the EGR device starts from a temperature range in which the coolant temperature detected by the outlet water temperature sensor is lower than the predetermined temperature.

  When driving the water pump and starting the circulation of cooling water, if a large amount of cooling water may flow into the water jacket from the external passage in a short period of time, it will flow out of the water jacket and be detected by the outlet water temperature sensor. The cooling water temperature to be temporarily decreased greatly. As a result, if the cooling water temperature falls below the control start temperature of the EGR control, the EGR control is temporarily stopped and the exhaust properties are deteriorated.

  In this respect, according to the present invention, when the water pump is driven to start the circulation of the cooling water, the temperature of the cooling water flowing out from the water jacket to the external passage and contacting the outlet water temperature sensor rapidly decreases. It is possible to avoid the temporary stop of the EGR control as described above, and to suppress the deterioration of the exhaust property due to the unnecessary stop of the EGR control.

The schematic diagram which shows typically the structure about one Embodiment which actualized the cooling device of the vehicle-mounted internal combustion engine of this invention. The flowchart which shows the process sequence about the opening degree control of the flow control valve concerning the embodiment. The map which shows the relationship between outlet water temperature and inlet water temperature, and the opening degree of a flow control valve. The timing chart which shows the operation example of the opening degree control of the flow control valve of the embodiment.

With reference to FIGS. 1-4, one Embodiment which actualized the cooling device of the vehicle-mounted internal combustion engine concerning this invention is described.
As shown in FIG. 1, a plurality of cylinder bores 12 a are formed in a cylinder block 12 of an internal combustion engine 1 mounted on a vehicle, and a cylinder head 11 is assembled on the top of the cylinder block 12. An engine combustion chamber is formed by a space defined by the cylinder bores 12a and the like. The internal combustion engine 1 is provided with a cooling device 20 that cools the cylinder head 11 and the cylinder block 12 that rise in temperature due to heat generated in the engine combustion chamber.

Hereinafter, the cooling device 20 will be described.
A water jacket 61 is formed in the cylinder head 11 and the cylinder block 12 so as to surround a cylinder bore 12a that forms an engine combustion chamber. Cooling water discharged from the water pump 23 flows into the water jacket 61. The water pump 23 is an impeller pump and includes a clutch (not shown) interposed between a rotating shaft (not shown) and an engine output shaft (not shown). . When the clutch is engaged, the rotating shaft of the water pump 23 and the engine output shaft are connected, and the water pump 23 is driven. Further, the drive of the water pump 23 is stopped by releasing the connection state between the rotary shaft and the engine output shaft through the clutch. That is, the water pump 23 does not depend on the rotation state of the engine output shaft, and the discharge amount of the cooling water is always “0”. On the other hand, when the clutch is engaged, the rotation shaft of the water pump 23 is rotated with the rotation of the engine output shaft, so that the water pump 23 is in a driving state. When the clutch is engaged in this manner, the water pump 23 changes the rotational speed of its rotating shaft, in other words, its discharge amount in accordance with the rotational speed of the engine output shaft, like a general engine-driven pump. To come.

  In addition, the cooling water discharged from the water pump 23 and flowing into the water jacket 61 in this way rises in temperature due to the heat of the cylinder head 11 and the cylinder block 12, and then partially flows into the bypass passage 64 to cause the thermostat 22 to flow. Is returned to the water pump 23, and a part thereof flows into the external passage 63 and is returned to the water pump 23 via the thermostat 22. Various heat exchangers are provided in the middle of the external passage 63. Specifically, the heater core 31 and the EGR cooler 41 are sequentially provided in the external passage 63 from the upstream side.

  Further, the water jacket 61 is connected to the thermostat 22 via the radiator passage 62. The radiator passage 62 is provided with the radiator 21 that releases heat of the cooling water to the outside. The water jacket 61, the bypass passage 64, the external passage 63 including the heater core 31 and the EGR cooler 41, and the radiator passage 62 including the radiator 21 constitute a circulation path 60 of the cooling device 20.

  The thermostat 22 is a temperature-sensitive flow path that opens and closes autonomously by opening and closing a valve body (not shown) provided in the thermostat 22 according to the temperature of cooling water flowing into the thermostat 22 through the bypass passage 64. It is a switching valve. That is, when the temperature of the cooling water flowing into the thermostat 22 becomes equal to or higher than the valve opening temperature set to a value lower than the predetermined temperature, the thermostat 22 is opened, so that the cooling water is supplied from the water jacket 61 to the radiator passage 62. Will flow in. As a result, the cooling water whose temperature has risen in the water jacket 61 is cooled in the radiator 21.

  Further, in the external passage 63, a flow rate adjustment valve 50 is provided on the downstream side of the EGR cooler 41. The flow rate adjusting valve 50 adjusts the flow rate of the cooling water flowing through the external passage 63 by changing the cross-sectional area of the external passage 63 according to the opening degree α. As a result, the amount of cooling water flowing into the water jacket 61 from the heater core 31 or the EGR cooler 41 is adjusted.

  In addition, in the cooling device 20, an outlet water temperature sensor 71 for detecting the temperature of the cooling water flowing out from the water jacket 61 to the external passage 63 is provided in the external passage 63, and flows into the water jacket 61 from the external passage 63. An inlet water temperature sensor 72 is provided for detecting the temperature of the cooling water. The heater core 31 and the EGR cooler 41 described above are provided downstream of the outlet water temperature sensor 71 and upstream of the inlet water temperature sensor 72 in the external passage 63. Accordingly, the temperature of the cooling water flowing into the heater core 31 and the EGR cooler 41 from the external passage 63 is detected by the outlet water temperature sensor 71, while the cooling water flowing into the water jacket 61 from the heater core 31 and the EGR cooler 41 through the external passage 63 is detected. The water temperature is detected by the inlet water temperature sensor 72.

  Hereinafter, the temperature of the cooling water detected by the inlet water temperature sensor 72 is referred to as “inlet water temperature θin”, and the temperature of the cooling water detected by the outlet water temperature sensor 71 is referred to as “outlet water temperature θout”. Further, when the cooling water temperature θ is simply described, it means “outlet water temperature θout”.

Next, the circulation mode of the cooling water in the cooling device 20 will be described.
When the cooling water temperature θ is lower than the valve opening temperature of the thermostat 22 as in the engine warm-up, the valve is closed so that the radiator passage 62 is closed by the thermostat 22. As a result, the cooling water of the water jacket 61 does not flow into the radiator passage 62 but circulates through the external passage 63 and the bypass passage 64.

  On the other hand, when the cooling water temperature θ becomes equal to or higher than the valve opening temperature of the thermostat 22 as after the engine warm-up, the radiator passage 62 is opened by the thermostat 22 because the valve is opened. As a result, the cooling water flowing out from the water jacket 61 is circulated to the radiator 21 through the radiator passage 62 in addition to the external passage 63 and the bypass passage 64.

  By the way, after the engine is started, it is desirable to complete the engine warm-up at an early stage in order to improve the fuel efficiency and the stability of the combustion state. Therefore, in the cooling device 20 of the present embodiment, the driving of the water pump 23 is stopped until the engine warm-up progresses to some extent, and the circulation of the cooling water in the circulation path 60 is prohibited.

  Specifically, when the cooling water temperature θ is lower than the predetermined temperature θp, the clutch is released and the water pump 23 is stopped. On the other hand, when the coolant temperature θ is equal to or higher than the predetermined temperature θp, the clutch is engaged, and the rotating shaft of the water pump 23 and the engine output shaft are drivingly connected. As a result, the water pump 23 rotates together with the engine output shaft, and discharges cooling water in an amount corresponding to the rotation speed, that is, the engine rotation speed.

  In addition to the cooling device 20, the internal combustion engine 1 is provided with a heater device 30 and an EGR device 40. The heater device 30 raises the temperature of the surrounding air by the heater core 31 described above and blows the heated air into the vehicle interior by the heater blower 32. Further, the EGR device 40 returns a part of the exhaust gas in the exhaust passage (not shown) as EGR gas to the intake passage (not shown) through the EGR passage (not shown). The above-described EGR cooler 41 is provided in the middle of the EGR passage, and cools the EGR gas flowing through the EGR passage through heat exchange with cooling water.

  In addition to the cooling device 20, various devices such as the heater device 30 and the EGR device 40 described above are comprehensively controlled through the control device 70. The control device 70 includes a memory, an A / D conversion circuit, a drive circuit, and the like in addition to the CPU. Various sensors such as an outlet water temperature sensor 71 and an inlet water temperature sensor 72 are connected to the control device 70. Then, the control device 70 appropriately takes in the detection signals of these sensors, thereby controlling the heater blower control for adjusting the air flow rate of the heater blower 32, EGR control for adjusting the EGR gas amount based on the opening degree of the EGR valve, and clutch engagement / Controls such as clutch control for switching the released state are executed.

  Here, in the heater blower control, air heated by the heater blower 32 and heat exchange with the heater core 31 on the condition that the outlet water temperature θout detected by the outlet water temperature sensor 71 is equal to or higher than the control start temperature θh It is blown into the room. Since the control start temperature θh is set lower than the predetermined temperature θp, the heater blower control is started before the cooling water circulation is started. Further, when the outlet water temperature θout becomes equal to or higher than the control start temperature θh, the blower amount of the heater blower 32 is set based on the outlet water temperature θout.

  Further, the EGR control is executed on condition that the outlet water temperature θout detected by the outlet water temperature sensor 71 is equal to or higher than the control start temperature θe. Since the control start temperature θe is set lower than the predetermined temperature θp, the EGR control is started before the cooling water circulation is started.

  By the way, when driving the water pump 23 and starting the circulation of the cooling water from the state where the circulation of the cooling water is stopped by stopping the driving of the water pump 23 at the time of engine warm-up, the following is performed. Concerned. That is, when a large amount of low-temperature cooling water flows from the external passage 63 into the water jacket 61, the temperature of the cylinder bore 12a may be drastically lowered, resulting in deterioration of fuel consumption. In addition, a large amount of low-temperature cooling water flows into the water jacket 61 from the external passage 63 in this way, while a large amount of high-temperature cooling water flows from the water jacket 61 into the external passage 63, so that the temperature of the cooling device 20 is increased. There is a possibility that the thermal fatigue of each part of the cooling device 20 including the cylinder head 11 such as the cylinder bore 12a and the cylinder block 12 may be abruptly changed.

  Furthermore, the low-temperature cooling water present in the external passage 63 flows into the water jacket 61 and flows out of the water jacket 61 into the external passage 63 again, whereby the value of the outlet water temperature θout detected by the outlet water temperature sensor 71 is temporarily increased. Decline. In this case, in the heater blower control, there is a possibility that the air flow rate fluctuates as the outlet water temperature θout of the heater blower 32 fluctuates. Further, in the heater blower control and the EGR control, the outlet water temperature θout temporarily decreases, and as a result, the control water may be unnecessarily stopped as a result of the temperature becoming lower than the above-described control start temperatures θh and θe. There is also.

  Therefore, in this embodiment, when discharge of the cooling water by the water pump 23 is started, the external passage 63 is circulated based on the respective cooling water temperatures θout and θin detected by the outlet water temperature sensor 71 and the inlet water temperature sensor 72. By controlling the flow rate of the cooling water, the rapid temperature decrease of the cylinder bore 12a as described above and the progress of thermal fatigue in each part of the cooling device 20 are suppressed. Specifically, the flow rate adjustment valve 50 is opened so that the amount of cooling water flowing into the water jacket 61 from the external passage 63 decreases as the inlet water temperature θin detected by the inlet water temperature sensor 72 through the flow rate adjustment valve 50 is lower. The degree is controlled. Further, the opening degree of the flow rate adjusting valve 50 is controlled so that the amount of cooling water flowing from the external passage 63 into the water jacket 61 increases as the outlet water temperature θout detected by the outlet water temperature sensor 71 increases.

  By controlling the opening degree α of the flow rate control valve 50 in this way, a specific example of “flow rate control valve opening degree control” for adjusting the amount of cooling water flowing through the external passage 63 as the cooling water circulation starts. Details of the processing will be described with reference to FIG. This process is repeatedly executed by the control device 70 every predetermined calculation cycle.

  First, in step S110, it is determined whether or not the outlet water temperature θout detected from the outlet water temperature sensor 71 is equal to or higher than a predetermined temperature θp. Here, the predetermined temperature θp determines whether or not the engine warm-up has progressed to some extent, in other words, whether or not local boiling occurs in the cooling water in the vicinity of the cylinder bore 12a when the circulation of the cooling water is stopped as it is. This value is preset through a test or the like and stored in the memory of the control device 70. The predetermined temperature θp is set to a value lower than the valve opening temperature of the thermostat 22. When it is determined in step S110 that the cooling water temperature θ is lower than the predetermined temperature θp, the driving of the water pump 23 is prohibited in step S130. That is, the engine warm-up is promoted by stopping the circulation of the cooling water in the circulation path 60.

On the other hand, when it is determined in step S110 that the coolant temperature θ is equal to or higher than the predetermined temperature θp, the water pump 23 is driven in step S120.
Next, in step S140, it is determined whether or not the outlet water temperature θout detected from the outlet water temperature sensor 71 is less than the determination temperature θv. Here, the determination temperature θv is preset through a test or the like as a value for determining whether or not the internal combustion engine 1 is seized when the cooling water is circulated as it is, and is stored in the memory of the control device 70. Has been. When it is determined in step S140 that the outlet water temperature θout is lower than the determination temperature θv, in step S150, the outlet water temperature θout of the cooling water flowing out from the water jacket 61 detected by the outlet water temperature sensor 71 and the inlet water temperature sensor. Based on a map (see FIG. 3) using the coolant inlet water temperature θin flowing into the water jacket 61 detected by 72 as a parameter (see FIG. 3), the opening degree α of the flow control valve 50 is calculated.

Specifically, as the inlet water temperature θin is lower, the opening degree α is set smaller. Further, as the outlet water temperature θout is higher, the opening degree α is set larger.
On the other hand, when it is determined in step S140 that the outlet water temperature θout is equal to or higher than the determination temperature θv, when the flow rate of the cooling water is limited thereafter, the local boiling or seizure of the cooling water temperature in the water jacket 61 is performed. In step S160, the opening degree α of the flow control valve 50 is set to fully open. That is, the flow rate of the cooling water in the external passage 63 becomes maximum when it is assumed that the engine speeds are equal.

  Next, referring to FIG. 4, the outlet water temperature θout, the inlet water temperature θin, the flow rate adjustment valve opening α, the heater blower control execution mode, the EGR control execution mode, the water pump when the series of processes described above are executed. An example of the transition of the driving state 23 will be described.

  When the outlet water temperature θout becomes equal to or higher than the control start temperature θh of the heater blower control at the timing t1 shown in FIG. 4, the heater blower control is started, and the amount of air blown according to the outlet water temperature θout is blown into the vehicle interior.

  Next, when the outlet water temperature θout becomes equal to or higher than the control start temperature θe of EGR control at timing t2, EGR control is started, and an amount of EGR gas corresponding to the engine operating state is returned to the intake passage. At timings t1 and t2, since the outlet water temperature θout is lower than the predetermined temperature θp, the driving of the water pump 23 is stopped, so that the inlet water temperature θin does not change at a low temperature.

  Thereafter, when the outlet water temperature θout becomes equal to or higher than the predetermined temperature θp at the timing t3, the driving of the water pump 23 is started. At this time, the higher the outlet water temperature θout and the inlet water temperature θin, the larger the opening degree α of the flow control valve 50 is set. Further, the inlet water temperature θin after the timing when the circulation of the cooling water is started gradually increases.

  Assuming that such a configuration in which the flow rate adjusting valve 50 is not provided in the external passage 63 is adopted, as shown by the two-dot chain line in FIG. As described above, the situation in which the outlet water temperature θout temporarily falls due to a large change in the amount temporarily occurs. And in such a period when the outlet water temperature θout is temporarily lower than the control start temperature θh of the heater blower control (t5 to t6) and a period temporarily lower than the control start temperature θe of the EGR control (timing t4 to t7), Control will be stopped, leading to instability of the passenger compartment temperature and deterioration of exhaust properties. In the heater blower control, even if the temperature does not fall below the control start temperature θh at which the control is stopped, if the cooling water temperature θ greatly fluctuates, the air flow also fluctuates greatly, so that it is stable in the passenger compartment. This makes it difficult to supply air. However, the flow rate of the cooling water flowing through the external passage 63 so that the outlet water temperature θout does not greatly fall below the predetermined temperature θp after releasing the cooling water circulation stop through the opening degree control of the flow rate adjusting valve 50 described above. Therefore, a large amount of low-temperature cooling water does not flow into the water jacket 61. As a result, the temperature of the cylinder bore 12a is not suddenly decreased, and fuel consumption is not deteriorated. Further, the heater blower control and EGR control are not temporarily stopped, and the temperature in the passenger compartment is not unstable and the exhaust properties are not deteriorated. When the outlet water temperature θout continues to rise and reaches timing t8, the outlet water temperature θout becomes equal to or higher than the determination temperature θv, and the opening degree α of the flow rate control valve 50 is set to be fully open.

According to the control apparatus for an onboard internal combustion engine of the present embodiment, the following effects can be obtained.
(1) When the water pump 23 is driven to start the circulation of the cooling water, the cooling water temperature θ flowing into the water jacket 61 from the external passage 63 is detected by the inlet water temperature sensor 72, and the detected inlet water temperature θin is low. The opening degree α of the flow control valve 50 is set so that the amount of cooling water flowing into the water jacket 61 from the external passage 63 decreases. As a result, a sudden drop in temperature of the cylinder bore 12a due to a large amount of low-temperature cooling water flowing into the water jacket 61 from the external passage 63, or a large amount of high-temperature cooling water flows from the water jacket 61 into the external passage 63. The rapid temperature rise of the cooling device 20 resulting from this can be suppressed. Therefore, it is possible to improve the fuel consumption and to suppress the progress of thermal fatigue in each part of the cooling device 20 including the cylinder head 11 such as the cylinder bore 12a and the cylinder block 12 and the like.

  (2) While setting the opening degree α of the flow control valve 50 so that the amount of cooling water flowing into the water jacket 61 from the external passage 63 decreases as the inlet water temperature θin detected by the inlet water temperature sensor 72 is lower, The opening degree α of the flow control valve 50 is set so that the amount of cooling water flowing into the water jacket 61 from the external passage 63 increases as the outlet water temperature θout detected by the outlet water temperature sensor 71 increases. As a result, local boiling of the cooling water in the water jacket 61 can be suitably avoided.

  (3) In the external passage 63, the heater core 31 and the EGR cooler 41 are provided downstream of the outlet water temperature sensor 71 and upstream of the inlet water temperature sensor 72. Thereby, the low temperature cooling water staying in the heater core 31 and the EGR cooler 41 flows into the water jacket 61, and the temperature of the cylinder bore 12a is drastically reduced. The high temperature cooling water is supplied from the water jacket 61 to the external passage 63. A sudden temperature change in the heater core 31 and the EGR cooler 41 due to a large amount of inflow can be suppressed. Therefore, the fuel consumption can be further improved, and the progress of thermal fatigue in each part of the cooling device 20 including the cylinder head 11 such as the cylinder bore 12a and the cylinder block 12 can be suitably suppressed. Become.

  (4) Even when the engine-driven water pump 23 that discharges the cooling water in an amount corresponding to the engine rotation speed is employed when the clutch is engaged at the start of the circulation of the cooling water, the external passage 63 is provided with a flow rate adjustment valve 50 for adjusting the flow rate of the cooling water, and by adjusting the opening degree α of the flow rate adjustment valve 50, the discharge amount of the water pump 23 is substantially finely controlled. The flow rate of the cooling water flowing into the water jacket 61 can be controlled based on the inlet water temperature θin detected by the inlet water temperature sensor 72. As a result, even in such a configuration employing the engine-driven water pump 23, when the water pump 23 is driven to start the circulation of the cooling water, the cooling water abruptly in the circulation path 60 including the water jacket 61 is rapidly changed. Temperature change can be suppressed. Therefore, fuel consumption can be improved, and the progress of thermal fatigue in each part of the cooling device 20 including the cylinder head 11 such as the cylinder bore 12a and the cylinder block 12 can be suppressed.

  (5) The opening degree control of the flow rate control valve 50 is started from a temperature range in which the outlet water temperature θout is lower than the valve opening temperature of the thermostat 22. Thus, when the water temperature is low and the thermostat 22 is closed, when the water pump 23 is driven to start the circulation of the cooling water, the rapid temperature change of the cooling water in the circulation path 60 including the water jacket 61 is suppressed. Will be able to.

  (6) The opening degree α of the flow control valve 50 is set based on the outlet water temperature θout and the inlet water temperature θin. Accordingly, when the water pump 23 is driven to start the circulation of the cooling water, it is possible to prevent the outlet water temperature θout flowing out from the water jacket 61 to the external passage 63 and contacting the outlet water temperature sensor 71 from rapidly decreasing. Therefore, it becomes possible to prevent the air flow rate of the heater blower 32 from becoming unstable.

  (7) The opening degree α of the flow control valve 50 is set based on the outlet water temperature θout and the inlet water temperature θin. Accordingly, when the water pump 23 is driven to start the circulation of the cooling water, it is possible to prevent the outlet water temperature θout flowing out from the water jacket 61 to the external passage 63 and contacting the outlet water temperature sensor 71 from rapidly decreasing. Therefore, the temporary stop of the EGR control can be avoided, and the deterioration of the exhaust property due to the unnecessary stop of the EGR control can be suppressed.

  (8) The opening degree α of the flow control valve 50 is set based on the outlet water temperature θout and the inlet water temperature θin. As a result, the opening degree α of the flow control valve 50 can be set in a manner more in line with the cooling water temperature θ of the cooling water flowing into the water jacket 61.

(Other embodiments)
The embodiment of the present invention is not limited to the above-described embodiment, and can be carried out, for example, in the following manner. The following modifications are not applied only to the above-described embodiment, and different modifications can be combined with each other.

  In the above embodiment, the opening degree α of the flow control valve 50 is set based on the inlet water temperature θin detected by the inlet water temperature sensor 72 and the outlet water temperature θout detected by the outlet water temperature sensor 71. It can also be changed as follows. That is, the opening degree α of the flow control valve 50 may be set based only on the inlet water temperature θin detected by the inlet water temperature sensor 72. Also in this case, the opening degree α of the flow rate adjusting valve 50 may be set so that the flow rate of the cooling water flowing from the external passage 63 into the water jacket 61 decreases as the inlet water temperature θin decreases. Even if it is such a structure, there can exist the effect of (1) and (3)-(7) mentioned above.

  -Although the heater core 31 and the EGR cooler 41 were illustrated as a heat exchanger in the said embodiment, the kind of heat exchanger is not restricted to this. That is, it may be a temperature rising passage or the like that is formed inside a throttle body in which a throttle valve or the like is built and through which cooling water flows. Even if it is such a structure, there can exist the effect of (1)-(8) mentioned above.

  In the above embodiment, the internal combustion engine 1 includes the heater device 30 and the EGR device 40, but at least one of them can be omitted. Even if it is such a structure, there can exist the effect of (1)-(5), (8).

  In the above embodiment, the inlet water temperature sensor 72 is provided near the inlet of the thermostat 22 in the external passage 63, but the position where the sensor 72 is provided is not limited thereto. For example, it may be provided near the inlets of the cylinder head 11 and the cylinder block 12. Even if it is such a structure, there can exist the effect of (1)-(8) mentioned above.

  In the above embodiment, a clutch is provided in the power transmission system between the engine output shaft and the rotation shaft of the water pump 23, and the power transmission from the engine output shaft to the rotation shaft of the water pump 23 is connected / disconnected by the clutch. However, for example, a belt (not shown) that rotates together with the pulley of the engine output shaft is brought into contact with / separated from the engine output shaft to bring the water pump 23 into contact with or separated from the water pump 23. The power transmission to the rotating shaft can be connected / disconnected.

  In the above embodiment, the engine-driven water pump 23 that can drive / stop the water pump 23 according to the engaged / released state of the clutch is used, but an electric water pump that is driven by a motor is used. You can also. In such a configuration, the flow rate of the cooling water can be limited to a small amount by the electric water pump, so that the detection value from the inlet water temperature sensor 72 is not considered, that is, the configuration in which the inlet water temperature sensor 72 is omitted. Thus, the flow rate of the cooling water in the external passage 63 can be adjusted based only on the outlet water temperature θout.

  In the above embodiment, the heater core 31 and the EGR cooler 41 are arranged downstream of the core 31 so that the cooler 41 is in series. However, the arrangement of these devices can be reversed. Also, these devices may be arranged in parallel. Even if it is such a structure, there can exist the effect of (1)-(8) mentioned above.

  In the above embodiment, heater blower control and EGR control have been described as an example of engine control for taking in coolant temperature θ as control information, but other control modes have been described below. Is mentioned. The present invention can also be applied to these engine controls.

  For example, in the internal combustion engine 1, when the cooling water temperature θ is low, the fuel injection amount is increased and corrected based on the cooling water temperature θ to suppress deterioration of the combustion state. Here, when the circulation of the cooling water is started and the cooling water temperature θ temporarily falls below the predetermined temperature θp, the fuel injection amount increase correction is executed based on the cooling water temperature θ. There is a concern that the fuel injection amount is unnecessarily increased, leading to deterioration of fuel consumption and exhaust properties. However, according to this modification, it is possible to avoid the occurrence of a problem due to such an excessive increase correction of the fuel injection amount. Even if it is such a structure, there can exist the effect of (1)-(5), (8) mentioned above. Further, the present invention can be applied not only to the fuel injection amount but also to the fuel injection timing.

  In the internal combustion engine 1, when the cooling water temperature θ is low, the ignition timing is retarded based on the cooling water temperature θ in order to promote warming up of the catalyst provided in the exhaust passage. Here, when the circulation of the cooling water is started and the cooling water temperature θ is temporarily lower than the predetermined temperature θp, if the ignition timing is retarded based on the cooling water temperature θ, then there is no effect. There is a concern that the ignition timing is retarded as necessary, leading to a decrease in engine output and an excessive temperature increase of the catalyst. However, according to this modification, it is possible to avoid the occurrence of a problem due to such an unnecessary retardation of the ignition timing. Even if it is such a structure, there can exist the effect of (1)-(5), (8) mentioned above.

  In the air-fuel ratio control, the fuel injection amount and the like are feedback corrected so that the air-fuel ratio of the air-fuel mixture burned based on the oxygen concentration in the exhaust gas after the completion of engine warm-up becomes the stoichiometric air-fuel ratio. Update the learning value of. Here, when the circulation of the cooling water is started and the cooling water temperature θ is temporarily lower than the predetermined temperature θp, the air-fuel ratio control is stopped unnecessarily based on the cooling water temperature θ. There is a concern that the air-fuel ratio becomes unstable and the exhaust properties deteriorate. However, according to this modification, it is possible to avoid the occurrence of problems due to such an unnecessary stop of the air-fuel ratio control. Even if it is such a structure, there can exist the effect of (1)-(5), (8) mentioned above.

  -In valve timing control, when the coolant temperature θ is high, such as after engine warm-up is completed, the valve timing is set to the optimum valve timing according to the engine operating condition in order to improve fuel economy and engine output. Timing control is executed. Here, when the circulation of the cooling water is started and the cooling water temperature θ is temporarily lower than the predetermined temperature θp, the valve timing control is stopped based on the cooling water temperature θ. However, there is a concern that the control is stopped and the engine output is reduced and the fuel consumption is deteriorated. However, according to this modification, it is possible to avoid the occurrence of a problem due to such an unnecessary stop of the valve timing control. Even if it is such a structure, there can exist the effect of (1)-(5), (8) mentioned above.

  DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 11 ... Cylinder head, 12 ... Cylinder block, 12a ... Cylinder bore, 20 ... Cooling device, 21 ... Radiator, 22 ... Thermostat, 23 ... Water pump, 30 ... Heater device, 31 ... Heater core, 32 ... Heater blower, DESCRIPTION OF SYMBOLS 40 ... EGR apparatus, 41 ... EGR cooler, 50 ... Flow control valve (flow control means), 60 ... Circulation route, 61 ... Water jacket, 62 ... Radiator passage, 63 ... External passage, 64 ... Detour passage, 70 ... Control device (Flow rate control means, control unit), 71 ... outlet water temperature sensor, 72 ... inlet water temperature sensor.

Claims (8)

A water pump capable of stopping the discharge of cooling water without depending on the engine speed, and the water jacket and the cooling water flowing out from the water jacket are returned to the water pump, and the cooling water discharged from the pump is returned to the water jacket again. A circulation path including at least an external passage for flowing into the engine, and an outlet water temperature sensor for detecting a temperature of cooling water flowing out from the water jacket to the external passage, and is detected by the outlet water temperature sensor when the engine is warmed up. In the cooling system for an on-vehicle internal combustion engine that stops driving the water pump and stops circulation of the cooling water in the circulation path when the cooling water temperature is lower than a predetermined temperature,
An inlet water temperature sensor for detecting the temperature of the cooling water flowing into the water jacket from the external passage;
When driving the water pump to start circulating the cooling water, the lower the cooling water temperature detected by the inlet water temperature sensor, the smaller the amount of cooling water flowing into the water jacket from the external passage. A cooling device for an on-vehicle internal combustion engine, comprising: a flow rate control means for controlling a flow rate. When the flow control means drives the water pump to start circulation of cooling water, the amount of cooling water flowing into the water jacket from the external passage increases as the cooling water temperature detected by the outlet water temperature sensor increases. The cooling device for an in-vehicle internal combustion engine according to claim 1, wherein the flow rate is controlled so as to increase. In the cooling device for an in-vehicle internal combustion engine according to claim 1 or 2,
The external passage includes a heat exchanger provided downstream of the outlet water temperature sensor and upstream of the inlet water temperature sensor. The flow rate control means is
A flow rate adjusting valve that is provided in the external passage and adjusts the flow rate of the cooling water flowing from the external passage into the water jacket by changing the flow passage cross-sectional area;
The on-vehicle internal combustion engine cooling device according to any one of claims 1 to 3, further comprising: a control unit that controls an opening degree of the flow rate control valve based on a cooling water temperature detected by the inlet water temperature sensor. The water pump is an engine-driven water pump whose rotational shaft is drivingly connected to the engine output shaft via a clutch, and is brought into a stopped state when the clutch is released, while the clutch is engaged. The in-vehicle internal combustion engine cooling device according to claim 4, wherein the driving state is achieved. In the cooling device for a vehicle-mounted internal combustion engine according to any one of claims 1 to 5,
A radiator passage for circulating cooling water between the water jacket and the radiator;
When the radiator passage is connected and the temperature of the cooling water in the water jacket is lower than a predetermined valve opening temperature, the valve passage closes the radiator passage by the valve body and prohibits the cooling water from flowing into the radiator. A thermostat that allows the radiator passage to communicate with the valve body when the temperature is equal to or higher than the valve opening temperature, and allows cooling water to flow into the radiator;
The on-vehicle internal combustion engine cooling device, wherein the flow rate control means starts the flow rate control from a temperature range in which the coolant temperature detected by the outlet water temperature sensor is lower than the valve opening temperature. In the cooling device for an in-vehicle internal combustion engine according to any one of claims 1 to 6,
The external passage includes a heater core that is provided on the downstream side of the outlet water temperature sensor and the upstream side of the inlet water temperature sensor and raises the air in the vehicle interior by the heat of the cooling water, and blows the heated air into the vehicle interior And a heater device for setting an air volume of the heater blower based on a cooling water temperature detected by the outlet water temperature sensor. In the cooling device for a vehicle-mounted internal combustion engine according to any one of claims 1 to 7,
An EGR device that recirculates a part of the exhaust gas from the exhaust system as EGR gas introduced into the intake system;
The recirculation of EGR gas by the EGR device is started from a temperature range in which the coolant temperature detected by the outlet water temperature sensor is lower than the predetermined temperature.

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