JP5223389B2 - Cooling device for internal combustion engine - Google Patents

Description

  The present invention relates to a technical field of a cooling device for an internal combustion engine capable of switching a flow path of a coolant such as cooling water.

  As this type of cooling device, for example, there is a device that switches the flow path of the cooling water in the cylinder head water jacket, the cylinder block water jacket, and the radiator according to the state of the internal combustion engine (see Patent Document 1).

  In addition, for example, depending on the state of the internal combustion engine, there are three modes: a warm-up mode in which cooling water flows through the bearing passage, a normal mode in which the cooling water flow is blocked, and a cooling mode in which the cooling water flows through the bearing passage again. There is a cooling device for switching (see Patent Document 2).

Japanese Patent Application Laid-Open No. 2004-270652 JP 2005-220770 A

  According to Patent Document 1 described above, the cylinder block (actually, the cylinder block is actually the cylinder head water jacket) is changed from the cylinder head (actually, the cylinder head water jacket) that is heated to a higher temperature due to warm-up when the internal combustion engine is cold. Circulate cooling water to the water jacket. However, there is a technical problem that the warm-up property of the entire internal combustion engine cannot be sufficiently ensured only by heating the cylinder block with the heat from the cylinder head.

  Further, according to the above-mentioned Patent Document 2, in the warm-up mode, cooling water is first circulated through the bearing passage in order to warm the bearing, and is further circulated through the bearing passage to a heater for air conditioning or the like. However, there is a technical problem that it may take a long time to ensure the warm-up performance of the heater only by the amount of heat of the cooling water flowing through the bearing passage.

  The present invention has been made in view of the above-described problems, and provides a cooling device for an internal combustion engine that can efficiently warm up a portion requiring warm-up, such as a cylinder block or a heater, according to the state of the internal combustion engine, for example. The task is to do.

  In order to solve the above problems, a cooling device for an internal combustion engine according to the present invention has a main body having a cylinder therein, an exhaust manifold connected to an exhaust port of the main body, and heat generation that dissipates or absorbs heat by a refrigerant. A cooling device for cooling an internal combustion engine having means, wherein the first branch flow path passes through or around the wall of the main body, the first branch flow path branches at the branch point, and merges at the merge point And a second branch channel that passes through or around the wall of the exhaust manifold, and a junction channel that connects the junction point to the branch point while having a heat exchange part that passes through or around the heat generating means. A refrigerant flow path through which the refrigerant flows, and a first flow rate of the refrigerant flowing from the first branch flow path to the merge flow path and from the second branch flow path to the merge flow path. Second of the refrigerant flowing A control valve capable of increasing and decreasing the amount, and a relative ratio of the first and second flow rates, at least one of the first and second flow rates, and a sum of the first and second flow rates according to the state of the internal combustion engine Control means for controlling the control valve so as to change at least one of them.

  According to the cooling apparatus for an internal combustion engine of the present invention, the internal combustion engine is cooled as follows. Here, the “internal combustion engine” includes a main body, an exhaust manifold (that is, an exhaust manifold), and heat generation means. The “main body” is, for example, a cylinder block, and the “exhaust manifold” is, for example, an exhaust manifold or a cylinder head. The “heat generating means” is, for example, an EGR (Exhaust Gas Recirculation) cooler, a heater for heating a vehicle or for air conditioning. For example, the EGR cooler plays a role of cooling the exhaust gas flowing through the EGR passage by the refrigerant. For example, the heater plays a role of warming the air in the automobile by the refrigerant. The “refrigerant” is a fluid such as cooling water.

  Heat generated by combustion in the internal combustion engine is transmitted to the main body and the exhaust manifold. At this time, the main body can be cooled, for example, by flowing the refrigerant through the first branch flow path passing through the wall of the cylinder block or around the cylinder. At this time, the more the refrigerant flows through the first branch channel, the more the cooling in the main body is promoted.

  In parallel with or in parallel with the cooling in such a main body, the exhaust manifold is, for example, the refrigerant flowing in the second branch flow path passing through the wall of the cylinder head or around the exhaust port, It can be cooled. At this time, the more the refrigerant flows through the second branch channel, the more the cooling in the exhaust manifold is promoted. High-speed exhaust gas typically flows through the second branch channel on the upper side in the exhaust port. For this reason, high temperature exhaust gas tends to flow to the upper side compared to the lower side in the exhaust port. Accordingly, it is desirable to configure the second branch flow channel so that it is easy to receive the heat of the exhaust, for example, above the exhaust port.

  In parallel with or in parallel with cooling in such a main body or exhaust manifold, the heat generating means is, for example, a heat radiating part (for example, an evaporator) in an EGR cooler, a heat absorbing part (for example, a heater core) in a heater, or the like. Cooling or warming-up is possible by flowing a refrigerant through a certain heat exchange section. At this time, the cooling or warming-up in the heat generating means is promoted as the refrigerant flows in a large amount in the merge channel.

  Here, the second branch flow channel branches off at the branch point with the first branch flow channel and merges at the merge point, and the merge channel connects the merge point to the branch point. Accordingly, the first flow rate and the second flow rate that flow from the first branch flow path to the merge flow path according to the state of the internal combustion engine by the control valve that is a three-way valve, for example, disposed at the merge location under the control of the control means. If the second flow rate flowing from the branch flow channel to the merge flow channel is increased or decreased, among the relative ratio of the first and second flow rates, at least one of the first and second flow rates, and the total of the first and second flow rates, At least one can be changed. The “control valve” is composed of, for example, a three-way valve, and the control means is composed of, for example, a part of an ECU including a processor, a memory, and the like.

  Here, according to the research of the present inventor, the following has been found. In the cold start of the internal combustion engine, it is desirable to preferentially warm up the internal combustion engine and the exhaust purification catalyst from the viewpoint of improving fuel efficiency, exhaust purification, etc. From the viewpoint of improvement, it is also desired to warm up a heater for heating a vehicle, which is an example of heat generation means, for example in winter. For example, waste heat from an EGR cooler, which is an example of heat generation means, can be used for warming up the heater. Immediately after the internal combustion engine is started, a small amount of EGR gas (that is, recirculated to the intake port) depending on the operating state. Exhaust) is diverted. For this reason, the warm-up performance of the heater cannot be ensured only by the heat amount of the EGR cooler that cools a small amount of EGR gas.

  Therefore, according to the present invention, when the main body is to be cooled by changing the first and / or second flow rates as described above, the main body can be more preferentially cooled and the exhaust manifold is to be cooled. Can cool the exhaust manifold more preferentially. In particular, when the heat generating means is to be cooled or warmed up, the heat generating means can be cooled or warmed up at the expense of more or less warming up of the main body or the exhaust manifold. That is, the heat of the exhaust can be positively used for warming up the heater, for example, by the refrigerant flowing through the second branch flow path. Therefore, for example, it is possible to ensure the warm-up property of the heater by combining the heat quantity of the exhaust gas and the heat quantity of the EGR cooler. The present invention, for example, prioritizes warming up of the internal combustion engine and the exhaust purification catalyst during the cold start of the internal combustion engine under the control of the control means, and when the exhaust purification catalyst has been warmed up, For example, the heater can be warmed up using heat.

  For example, the “state of the internal combustion engine” is a “first stage” in which warming up of the internal combustion engine and the exhaust purification catalyst is preferentially performed, for example, a “second stage” in which warming up of a heater which is an example of a heat generation unit is performed. Also, it may be three stages of “third stage” for optimizing the temperatures of the internal combustion engine and the exhaust purification catalyst. The “state of the internal combustion engine” may be more simply the temperature of the main body or the exhaust manifold or the temperature of the heater, or may be the rotational speed and load of the internal combustion engine.

  Specifically, for example, in the “first stage” immediately after the start of the internal combustion engine, the control means sets the first and second flow rates to zero, and sets the refrigerant flow in the first and second branch flow paths. Stop. Then, due to the combustion cycle, the temperature of the refrigerant stagnating in the first branch flow path (that is, the main body portion) and the second branch flow path (that is, the exhaust manifold portion) rises, and exhaust gas discharged from the internal combustion engine The purification catalyst is warmed up. Therefore, it is possible to preferentially warm up the internal combustion engine and the exhaust purification catalyst.

  For example, in the “second stage” after the exhaust purification catalyst has been warmed up, the control means is configured such that the first flow rate is continuously reduced to zero, the second flow rate is set to a predetermined amount, and only the refrigerant from the second branch flow path. Shed. Then, for example, the heater can be warmed up using the heat of the exhaust gas by the refrigerant flowing through the second branch flow path.

  For example, in the “third stage” after the heater is warmed up, the control means changes the relative ratio of the first and second flow rates according to the operating state (for example, the rotational speed and the load) of the internal combustion engine. Let Then, the refrigerant ratio of the main body and the exhaust manifold is changed, and the temperatures of the internal combustion engine and the exhaust purification catalyst are optimized.

  As described above, the first and / or second flow rates are changed in accordance with the state of the internal combustion engine, so that the internal combustion engine, the exhaust purification catalyst, and the heat generating means such as a heater are warmed up stepwise. be able to. Thereby, each part of an internal combustion engine, an exhaust gas purification catalyst, and a heat generation means can be warmed up more efficiently than when warming up all at once. Further, since the heat of the exhaust is used for warming up the heat generating means, fuel efficiency can be improved.

  In one aspect of the cooling apparatus for an internal combustion engine according to the present invention, the control means changes the at least one according to a warm-up state of the internal combustion engine from a cold state as the state. Control the valve.

  According to this aspect, the “warm-up state from when the engine is cold” is, for example, the above-described three stages, and the internal combustion engine, the exhaust gas is changed by changing the first and / or second flow rate at each stage. Each part of the purification catalyst and the heat generating means can be efficiently warmed up.

  In another aspect of the cooling apparatus for an internal combustion engine according to the present invention, the control means controls the control valve so that the first flow rate and the second flow rate are each zero after the cold start of the internal combustion engine. .

  According to this aspect, after the cold start, the flow of the refrigerant in the first and second branch flow paths is stopped. This stop time is, for example, several seconds, tens of seconds, tens of seconds or the like. Thereby, the temperature of the refrigerant stagnating in the main body and the exhaust manifold, and the temperature of the exhaust purification catalyst (for example, the NOx storage catalyst or the EGR catalyst) to which the exhaust discharged from the internal combustion engine is guided can be raised at an early stage.

In another aspect of the cooling apparatus for an internal combustion engine according to the present invention, the internal combustion engine is disposed in the exhaust manifold or an exhaust passage connected to the exhaust manifold, and further includes an exhaust purification catalyst that purifies the exhaust. and, wherein, the catalyst temperature of the exhaust gas purifying catalyst as an indicator of the state, if it exceeds the first temperature threshold value, the only such that the refrigerant flows from the second branch flow path control valve To control.

According to this aspect, the “exhaust purification catalyst ” is, for example, an EGR catalyst . Specifically, when the catalyst temperature exceeds the first temperature threshold, it is determined that the warm-up of the EGR catalyst has ended (in other words, the EGR catalyst has become active), and the refrigerant flows only from the second branch flow path. Washed away. With this refrigerant, for example, heat generation means such as a heater can be warmed up.

  In another aspect of the cooling apparatus for an internal combustion engine according to the present invention, the control means is configured such that the temperature of the refrigerant flowing through the first branch flow path as an index indicating the state exceeds a second temperature threshold value. The control valve is controlled so that the refrigerant flows from both the first and second branch flow paths.

  Specifically, according to this aspect, when the temperature of the refrigerant in the main body exceeds the second temperature threshold, the heat generating means such as a heater is warmed up (in other words, the heat generating means is warmed up). To a sufficient refrigerant temperature), the refrigerant flows from the first and second branch flow paths. With this refrigerant, the internal combustion engine and the exhaust purification catalyst (in other words, exhaust gas) can be cooled.

  In this aspect, the control means may control the control valve so as to change the relative ratio according to the rotational speed and load of the internal combustion engine as the state.

  With this configuration, the “load” is, for example, a torque or an air filling rate, and is proportional to the rotational speed. The relative ratio is set based on, for example, a map showing the relationship between the rotational speed and the air filling rate. “Air filling rate” is, for example, the rate or ratio of air that is filled or sucked into the combustion chamber. Typically, the higher the rotational speed and the higher the air filling rate, the higher the exhaust temperature. Specifically, for example, when the rotation speed is low and the air filling rate is low, the first flow rate to the second flow rate is 9 to 1, and when the rotation number is high and the air filling rate is high, it is 8 to 2. . Thus, the higher the temperature of the exhaust, the higher the ratio of the second flow rate, and the flow rate of the refrigerant for cooling the exhaust purification catalyst (in other words, the exhaust) is increased, thereby cooling the internal combustion engine and the exhaust purification catalyst. Can be performed appropriately. Therefore, for example, if the internal combustion engine and the exhaust purification catalyst are appropriately cooled in the high rotation and high load operation region (that is, the lambda region) in the internal combustion engine, the lambda region is expanded and the exhaust purification catalyst is Since the fuel injection amount is not increased in response to the excessive temperature rise, the fuel consumption can be further improved.

  In another aspect of the cooling apparatus for an internal combustion engine according to the present invention, the internal combustion engine further includes an EGR passage communicating with the exhaust manifold or the exhaust passage connected to the exhaust manifold to the intake side of the internal combustion engine, The heat generating means includes an EGR cooler that cools the EGR passage.

  According to this aspect, the EGR passage typically returns a part of the exhaust discharged from the internal combustion engine to the intake system of the internal combustion engine. The EGR cooler cools part of the exhaust gas recirculated through the EGR passage. As a result, the heat generating means such as a heater disposed downstream of the EGR cooler in the refrigerant flow path can be warmed up using the waste heat of the EGR cooler in addition to the heat of the exhaust.

  In another aspect of the cooling apparatus for an internal combustion engine according to the present invention, the main body portion and the exhaust manifold portion are integrally formed.

  According to this aspect, in the exhaust manifold, the second branch flow path is disposed, for example, close to the upper side of the exhaust port, so that the heat of the exhaust can be efficiently absorbed by the refrigerant. Note that “consisting integrally” means that the material is continuously formed from the same material or formed from different materials and is firmly bonded, and at least heat conduction between the main body and the exhaust manifold. Is configured to be performed without air.

  In another aspect of the cooling apparatus for an internal combustion engine according to the present invention, the control valve is a three-way valve, and the control means switches the three-way valve in accordance with the state.

  According to this aspect, the three-way valve includes, for example, a position connecting the first branch flow path and the merge flow path, a position connecting the second branch flow path and the merge flow path, the first branch flow path and the second flow path. The position is switched to four positions: a position where the branch flow path and the merge flow path are connected, and a position where no flow paths are connected. The three-way valve can change the first and / or second flow rate at each position, for example. Thereby, the flow rate of the refrigerant for cooling the internal combustion engine and the exhaust purification catalyst (in other words, the exhaust gas) can be changed easily and reliably, thereby appropriately cooling the internal combustion engine and the exhaust purification catalyst. it can.

  In another aspect of the cooling device for an internal combustion engine according to the present invention, the circulation path passes through or around the wall of the main body portion, is connected in parallel with the refrigerant flow path, and is part of the merging flow path. And the heat exchanger for exchanging heat with the outside by means of the refrigerant, the heat exchange means for exchanging heat with the outside by the refrigerant, and the refrigerant in the middle of the circulation path. The apparatus further comprises a circulating pump means and a thermostat arranged at a location where the main flow path and the merge flow path merge.

  According to this aspect, for example, the pump means, the main body, the heat exchange means, and the thermostat are arranged in the “main flow path” from the upstream of the refrigerant flow path. The “pump means” is, for example, a water pump, and the “heat exchange means” is, for example, a radiator. The “thermostat” circulates the refrigerant by, for example, a bottom bypass flow type. For example, the thermostat opens the water channel arranged in the merge channel so that the refrigerant flowing through the merge channel is circulated in the second and third stages described above. For example, in the third stage described above, the thermostat opens and closes the water channel disposed in the main channel at the specified temperature of the refrigerant, and merges the main channel and the merge channel. By this merging, the temperature of the internal combustion engine can be optimized by sending the refrigerant that has passed through the heat exchange means to the pump means.

  The operation and other advantages of the present invention will become apparent from the best mode for carrying out the invention described below.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  First, a configuration of a cooling device for an internal combustion engine according to an embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic plan view showing an outline of the cooling apparatus for an internal combustion engine according to the embodiment, and FIG. 2 is a cross-sectional view showing the arrangement of the second branch flow paths shown in FIG.

  In FIG. 1, a cooling device 100 for an internal combustion engine 10 according to the embodiment includes a circulation path 1 and an ECU 40 in order to optimize the temperatures of the internal combustion engine 10, the EGR catalyst 31, and the heater 27. The circulation path 1 is a refrigerant flow path including a main flow path 2, a first branch flow path 3, a second branch flow path 4, and a merge flow path 5. ECU40 controls each part including the internal combustion engine 10 arrange | positioned at these four flow paths 2-5 collectively. Arrows in the respective flow paths 2 to 5 indicate directions in which cooling water, which is an example of the “refrigerant” according to the present embodiment, flows.

  In FIG. 2, the internal combustion engine 10 is a lean combustion engine, and includes a main body portion 11 including a cylinder head and an exhaust manifold upper portion 14. The main body 11 includes a plurality of cylinders 12. A piston 13 is disposed inside each cylinder 12, and the main flow path 2 and the first branch flow path 3 are passed through the wall of each cylinder 12. Each cylinder 12 has a pent roof type combustion chamber, and an intake manifold (intake port) 15, an exhaust manifold (exhaust port) 16, a spark plug 17, and a fuel passage (not shown) are connected to the combustion chamber. Has been. An intake valve, an exhaust valve, and an injection valve (not shown) are arranged at locations where the intake manifold 15, the exhaust manifold 16 and the fuel passage are connected. An EGR passage 18 to be described later is connected to the exhaust manifold 16 and the intake manifold 15.

  As shown in FIG. 1, a water pump 21, a radiator 22, and a thermostat 23 are arranged in the main channel 2 in order from the upstream side. The main flow path 2 passes through the wall of the cylinder 12 in the main body 11.

  A water pump (hereinafter referred to as “W / P”) 21 pumps (in other words, circulates) cooling water along the main flow path 2 as an example of “pump means” according to the present embodiment.

  The radiator 22 radiates the cooling water heated by the main body 11 as an example of the “heat exchanging means” according to the present embodiment. The cooling water cooled by heat dissipation flows into the thermostat 23.

  The thermostat 23 is disposed at a junction P2 where the main channel 2 and the junction channel 5 merge, and includes a valve (not shown). The valve opens and closes at a specified temperature. The thermostat 23 can adjust the temperature of the cooling water flowing through the main flow path 2 and / or the merge flow path 5 by opening and closing the valve. The thermostat 23 returns the cooling water to the W / P 21 in a state where the valve is opened (that is, circulates in the main flow path 2).

  The circulation channel 1 is branched into the first and second branch channels 3 and 4 at the branch point P1, and is joined again at the junction point P2. A three-way valve 24 is disposed at the junction P2. The first and second branch channels 3 and 4 are partially connected in parallel with the main channel 2.

  Similar to the main flow path 2, the first branch flow path 3 passes through the wall of the cylinder 12 in the main body 11. The cooling water that has passed through the main body 11 flows to the three-way valve 24. A cooling water temperature measurement unit 30 is disposed between the main body 11 and the three-way valve 24 in the first branch flow path 3. The cooling water temperature measurement unit 30 measures the temperature W1 of the cooling water and sends the measurement result to the ECU 40.

  As shown in FIG. 2, the second branch flow path 4 is arranged in the upper part of the exhaust manifold 14 so as to pass through the upper part of the exhaust manifold 16. The exhaust manifold upper part 14 is configured integrally with the main body 11 as an example of the “exhaust manifold” according to the present embodiment. The cooling water that has passed through the exhaust manifold upper part 4 flows to the three-way valve 24.

  The three-way valve 24 includes two valves (not shown) and an actuator (not shown). The three-way valve 24 drives the actuator to change the opening degree of each valve, so that the first connection position that connects the first branch flow path 3 and the merge flow path 5, and the second branch flow path 4 and the merge flow. A second connection position for connecting the path 5, a third connection position for connecting the first branch flow path 3, the second branch flow path 4 and the merge flow path 5, and a fourth connection position for connecting no flow paths. The four connection positions are switched. Further, in the present embodiment, the three-way valve 24 further includes a first flow rate F1 that is a flow rate of cooling water flowing from the first branch flow channel 3 to the merge flow channel 5 and the second branch flow channel 4 at the third connection position. The mutual ratio of the second flow rate F2 that is the flow rate of the cooling water flowing in the merge channel 5 can be changed. The cooling water that has passed through the three-way valve 24 flows to the EGR cooler 26.

  The merge channel 5 is a channel that connects the merge point P3 to the branch point P1. In the merging flow path 5, an EGR cooler 26, a heater 27, the above-described thermostat 23, and the above-described W / P 21 are disposed in order from the upstream side.

  The EGR cooler 26 is disposed in the EGR passage 18 as an example of “heat generation means” according to the present embodiment. As shown in FIG. 2, the EGR passage 18 communicates from the exhaust manifold 16 to the intake manifold 15 to recirculate part of the exhaust from the internal combustion engine 10.

  An EGR catalyst 31 is disposed upstream of the EGR cooler 26 in the EGR passage 18. The EGR catalyst 31 purifies the exhaust gas flowing through the EGR passage 18. The EGR catalyst 31 includes a catalyst filter and a catalyst temperature measuring unit 32. The catalyst temperature measuring unit 32 measures the temperature C1 of the catalyst filter and sends the measurement result to the ECU 40.

  The EGR cooler 26 includes an evaporator (not shown) that is an example of a “heat exchange unit” according to the present embodiment. The merging channel 5 passes around the evaporator in the EGR cooler 26. The EGR cooler 26 cools the EGR passage 18 that has been warmed by the high-temperature exhaust gas using the cooling water. The cooling water warmed by this cooling flows to the heater 27.

  The heater 27 can change the room temperature of the vehicle including the internal combustion engine 10 as an example of the “heat generating unit” according to the present embodiment. The heater 27 includes a heater core (not shown) that is an example of the “heat exchange unit” according to the present embodiment. The merge channel 5 passes around the heater core in the heater 27. The heater 27 warms up the heater core with cooling water. The cooling water cooled by the warm-up reaches the branch point P1 via the thermostat 23 and the W / P 21.

  The ECU 40 can switch the connection position of the three-way valve 24 and the coolant flow rate according to the warm-up state of the internal combustion engine 10 from when the engine is cold. The ECU 40 presets the warm-up state from when the engine is cold in three stages of “warm-up initial stage”, “warm-up middle stage”, and “warm-up end”. The ECU 40 includes a determination unit 40a, and the determination unit 40a uses the two indicators of the temperature of the EGR catalyst 31 measured by the catalyst temperature measurement unit 32 and the temperature of the cooling water measured by the cooling water temperature measurement unit 30. To determine the transition between the three stages. In addition to the control of the three-way valve 24, the ECU 40 controls the W / P 21 and the thermostat 23 according to the state of the internal combustion engine 10 (that is, three stages and the operating state), and the main body unit 11, EGR catalyst. 31 and the temperature of the heater 27 are optimized.

  Next, the three stages and the control of the three-way valve 24 in each stage will be specifically described with reference to FIG. Here, FIG. 3 is a map for determining the relative ratio of the first and second flow rates according to the present embodiment.

  Of the three stages, the “warm-up initial stage” is a period from the time when the internal combustion engine 10 is started until the temperature C1 of the EGR catalyst 31 is equal to or lower than the first temperature threshold value C0 when cold. At this time, the ECU 40 switches the three-way valve 24 to the fourth connection position, and the first flow rate F1 and the second flow rate F2 are set to zero.

  In the “warm-up middle stage” stage shifted from the “warm-up initial stage” stage, the temperature W1 of the cooling water is equal to or lower than the second temperature threshold value W0 from the time when the temperature C1 of the EGR catalyst 31 exceeds the first temperature threshold value C0. It is time until. At this time, the ECU 40 switches the three-way valve 24 to the second connection position, the first flow rate F1 is continuously set to zero, and the second flow rate F2 is set to a predetermined amount.

  The “warm-up end” stage shifted from the “warm-up middle stage” stage is after the time when the temperature W1 of the cooling water exceeds the second temperature threshold value W0. At this time, the ECU 40 switches the three-way valve 24 to the third connection position, and the coolant flows through all the refrigerant flow paths 2 to 5 (that is, the circulation flow path 1). The first and second flow rates F1 and F2 may be determined based on the exhaust manifold upper cooling water ratio map shown in FIG.

In FIG. 3, in the exhaust manifold upper cooling water ratio map, the rotation speed (rpm) is set on the horizontal axis, and the air filling rate (KL) (in other words, torque) is set on the vertical axis. As a function of the above, an equal exhaust temperature line for dividing each region of the exhaust manifold upper cooling water flow rate ratio is shown. In the map, the higher the rotation speed and the higher the air filling rate, the higher the temperature of the exhaust gas. Therefore, the second flow rate F2 that passes through the upper part 14 of the exhaust manifold 14 with respect to the first flow rate F1 that passes through the main body 11. The ratio of is increased. That is, the second flow rate F2 flowing from the exhaust manifold upper part 14 (second branch flow path 4) to the EGR cooler 26 and the heater 27 (merging flow path 5) increases as the exhaust gas temperature increases. In the present embodiment, for example, when the air filling rate is relatively low, the ratio of the first flow rate F1 to the second flow rate F2 is 90:10. Further, when the air filling rate is relatively high, the first flow rate F1 to the second flow rate F2 has a ratio of 80 to 20.
(First control process)
Next, a first control process of the control valve by the control means according to the present embodiment will be described with reference to FIG. FIG. 4 is a flowchart showing the first control process of the control valve according to this embodiment. In the first control process, the three-way valve 24 is switched according to three stages, and the sum of the first and second flow rates F1 and F2 changes.

  In FIG. 4, the ECU 40 first determines whether or not the internal combustion engine 10 has been started (step S51). If the internal combustion engine 10 has not been started (step S51: NO), until the internal combustion engine 10 is started. It will be in a standby state. On the other hand, when the internal combustion engine 10 is started (step S51: YES), it is determined whether or not the coolant temperature W1 measured by the coolant temperature measurement unit 30 is lower than the second temperature threshold value W0 (step S52). ). If the result of this determination is higher than the second temperature threshold value W0 (step S52: NO), the process of step S57 is executed.

  On the other hand, if the result of determination in step S52 is that the temperature W1 of the cooling water is lower than the second temperature threshold value W0 (step S52: YES), W / P21 is stopped as the “warm-up initial” stage (step S53). . At this time, the first flow rate F1 and the second flow rate F2 are each zero. Subsequently, it is determined whether or not the catalyst temperature C1 measured by the catalyst temperature measuring unit 32 is higher than the first temperature threshold C0 (step S54), and when the catalyst temperature C1 is lower than the first temperature threshold C0 (step S54). : NO), and a standby state is maintained until the catalyst temperature C1 becomes higher than the first temperature threshold value C0.

  On the other hand, as a result of the determination in step S54, when the catalyst temperature C1 is higher than the first temperature threshold value C0 (step S54: YES), the W / P 21 is activated and passes through the exhaust manifold upper part 14 as the “warm-up middle stage” stage. Cooling water flows only through the second branch flow path 4 (step S55). Subsequently, it is again determined whether or not the coolant temperature W1 by the coolant temperature measurement unit 30 is higher than the second temperature threshold value W0 (step S56). As a result of this determination, when the temperature is lower than the second temperature threshold value W0 (step S56: NO), the process of step S55 (that is, the cooling water is allowed to flow only through the second branch flow path 4) is continuously executed.

  On the other hand, as a result of the determination in step S56, when the temperature W1 of the cooling water is higher than the second temperature threshold value W0 (step S56: YES), the cooling water is supplied to all the refrigerant flow paths 2 to 5 as the “warm-up completion” stage. (Step S57). Thereby, the first control process of the example is ended.

Thus, the internal combustion engine 10, the EGR catalyst 31, and the heater 27 are warmed up stepwise by changing the first and / or second flow rates F1, F2 according to the three stages of the internal combustion engine 10. It can be carried out. Thereby, each part of the internal combustion engine 10, the EGR catalyst 31, and the heater 27 can be warmed up efficiently.
(Second control process)
Next, the second control process of the control valve by the control means according to the present embodiment will be described with reference to FIG. FIG. 5 is a flowchart showing the second control process of the control valve according to this embodiment. In the second control process, in the “warm-up completion” stage, the relative ratio of the first and second flow rates F1, F2 changes according to the rotation speed of the internal combustion engine 10 and the air filling rate.

  In FIG. 5, as in the first control process, when the internal combustion engine 10 is first started by the ECU 40 (step S51: YES), the temperature W1 of the cooling water flowing through the first branch flow path 3 becomes the second temperature threshold value. It is determined whether the temperature is lower than W0 (step S52). When the temperature is lower than the second temperature threshold value W0 (step S52: YES), W / P21 is stopped as the “warm-up initial” stage (step S53). Subsequently, it is determined whether or not the catalyst temperature C1 of the EGR catalyst 31 is higher than the first temperature threshold value C0 (step S54). When the catalyst temperature C1 is higher than the first temperature threshold value C0 (step S54: YES), “warm-up middle stage” As a stage, the W / P 21 is operated, and the cooling water is allowed to flow only in the second branch flow path 4 (step S55). Subsequently, it is again determined whether or not the temperature W1 of the cooling water is higher than the second temperature threshold value W0 (step S56).

  As a result of the determination in step S56, when the temperature W1 of the cooling water is higher than the second temperature threshold value W0 (step S56: YES), the rotational speed and the air filling rate of the internal combustion engine are read as the “warm-up completion” stage. (Step S61) Based on these rotational speed and air filling rate, the ratio of the second flow rate F2 to the first flow rate F1 is read from the exhaust manifold upper cooling water ratio map of FIG. 3 (Step S62). Subsequently, the valve opening degree of the three-way valve 24 is switched corresponding to the read ratio, and the cooling water of the first and second flow rates F1, F2 corresponding to the ratio is flowed (step S63). Thereby, a series of 2nd control processing is complete | finished.

  Thus, the higher the temperature of the exhaust, the higher the ratio of the second flow rate F2, and the flow rate of cooling water for cooling the exhaust (in other words, the EGR catalyst 31) is increased, so the internal combustion engine 10 and the EGR catalyst 31 are increased. Can be appropriately cooled. Therefore, the area of lambda can be expanded and fuel consumption can be further improved.

  The present invention is not limited to the above-described embodiments, and can be appropriately changed without departing from the spirit or concept of the invention that can be read from the claims and the entire specification.

It is a schematic block diagram which shows the cooling device of the internal combustion engine which concerns on embodiment. It is sectional drawing which shows the 2nd branch flow path in the exhaust manifold part of FIG. It is a function which shows the ratio of the 2nd flow rate to the 1st flow rate in an embodiment. It is a flowchart which shows the 1st control process of the control valve in embodiment. It is a flowchart which shows the 2nd control process of the control valve in embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 3 ... 1st branch flow path, 4 ... 2nd branch flow path, 5 ... Merge flow path, 10 ... Internal combustion engine, 11 ... Main body part, 14 ... Exhaust manifold upper part, 24 ... Three-way valve, 40 ... ECU, 100 ... Cooling device

Claims (9)

A cooling device for cooling an internal combustion engine having a main body having a cylinder therein, an exhaust manifold connected to an exhaust port of the main body, and heat generation means for radiating or absorbing heat by a refrigerant,
A first branch passage that passes through or around the wall of the main body, a first branch passage that branches at the first branch passage and a branch point, merges at a junction, and passes through or around the wall of the exhaust manifold. A refrigerant flow path through which the refrigerant flows, including a bifurcated flow path, and a merge flow path that has a heat exchange section that passes through or around the heat generation means and connects the merge position to the branch position;
Control that can be increased or decreased in the first flow rate of the refrigerant that flows from the first branch flow channel to the merge flow channel and the second flow rate of the refrigerant that flows from the second branch flow channel to the merge flow channel, which is arranged at the merge point. A valve,
At least one of the relative ratio of the first and second flow rates, at least one of the first and second flow rates, and the total of the first and second flow rates is changed according to the state of the internal combustion engine. Control means for controlling the control valve as described above,
The internal combustion engine is disposed in the exhaust manifold or an exhaust passage connected to the exhaust manifold, and further includes an exhaust purification catalyst that purifies the exhaust ,
The control means controls the control valve so that the refrigerant flows only from the second branch flow path when the catalyst temperature of the exhaust purification catalyst as an index indicating the state exceeds a first temperature threshold. A cooling device for an internal combustion engine.   The said control means controls the said control valve so that said at least one may be changed according to the warming-up state from the time of the engine cold of the said internal combustion engine as said state. Cooling device for internal combustion engine.   3. The internal combustion engine according to claim 1, wherein the control unit controls the control valve so that the first flow rate and the second flow rate are each zero after the cold start of the internal combustion engine. 4. Cooling system. When the temperature of the refrigerant flowing through the first branch flow path as an index indicating the state exceeds a second temperature threshold, the control means removes the refrigerant from both the first and second branch flow paths. The cooling device for an internal combustion engine according to any one of claims 1 to 3, wherein the control valve is controlled so as to flow.   5. The cooling apparatus for an internal combustion engine according to claim 4, wherein the control means controls the control valve so as to change the relative ratio according to a rotation speed and a load of the internal combustion engine as the state. . The internal combustion engine further includes an EGR passage communicating from the exhaust manifold or an exhaust passage connected to the exhaust manifold to the intake side of the internal combustion engine,
The cooling device for an internal combustion engine according to any one of claims 1 to 5, wherein the heat generating means includes an EGR cooler that cools the EGR passage.   The cooling device for an internal combustion engine according to any one of claims 1 to 6, wherein the main body portion and the exhaust manifold portion are integrally formed. The control valve is a three-way valve,
The cooling device for an internal combustion engine according to any one of claims 1 to 7, wherein the control means switches the three-way valve in accordance with the state. A main channel that passes through or around the wall of the main body, is partially connected in parallel with the refrigerant channel and forms a circulation path together with a part of the merge channel, and the refrigerant flows through the main channel;
A heat exchanging means disposed in the middle of the main flow path and exchanging heat with the outside by the refrigerant;
A pump means disposed in the middle of the circulation path for circulating the refrigerant;
The cooling apparatus for an internal combustion engine according to any one of claims 1 to 8, further comprising: a thermostat disposed at a location where the main flow path and the merge flow path merge.

Images