JP2012145008A - Internal combustion engine control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine control device capable of suppressing local rise in temperature of cooling water in a cooling water passage of an internal combustion engine.SOLUTION: A heat exchanger 4 is installed at an upper part of an engine. A cooling water passage 4a and a gas passage 4b are provided inside the heat exchanger 4. The cooling water passage 4a is in communication with a water jacket 15. One side of the gas passage 4b is connected to an exhaust system 3, and the other side is switchably connected a secondary air supply device 6 and an EGR device 7 by a switching valve 53 comprising a three-way valve. During a warm-up operation of the engine E, the secondary air supply device 6 and the heat exchanger 4 are connected, the cooling water in the heat exchanger 4 is cooled by secondary air, and the convection of the cooling water is generated between the heat exchanger 4 and the water jacket 15. After the completion of the warm-up operation of the engine E, the EGR device 7 and the heat exchanger 4 are connected, and EGR gas is cooled by the cooling water and supplied to an intake system 2.

Description

  The present invention relates to a control device for an internal combustion engine represented by an automobile engine or the like. In particular, the present invention relates to an improvement of an internal combustion engine provided with a cooling system that stops the flow of cooling water to at least a part of a cooling water flow path during warm-up operation.

  Conventionally, as a cooling device mounted on an automobile engine, a radiator, a thermostat, a water pump, and the like are provided. Further, it is known that the water pump is stopped at the time of cold start (cold start) of the engine, and the flow of the cooling water in the cooling water flow path (water jacket) inside the engine is stopped. (See, for example, Patent Document 1 below). As a result, the temperature of the engine body can be quickly raised, and friction loss at various locations in the engine can be reduced within a short period of time after the engine is started, so that the fuel consumption rate can be improved.

JP 2010-84649 A JP 2008-133772 A JP 58-88418 A

  By the way, in the case of stopping the water pump when the engine is cold-started as described above, a part of the cooling water in the water jacket may be particularly hot. Specifically, the cooling water existing around the combustion chamber has a significantly higher temperature than the cooling water existing in other regions due to an increase in the amount of heat received from the combustion gas.

In such a situation, the following problems may occur.
There is a possibility that only a part of the cooling water in the water jacket will boil and a cooling water leak (for example, a cooling water leak from the mating part of the cylinder block and the cylinder head) may occur.
・ Since the amount of thermal expansion around the combustion chamber in the cylinder block is particularly large and the bore diameter is large, the impact sound caused by the so-called piston swinging phenomenon (the impact sound caused by the piston side colliding with the bore inner wall surface) ) May occur.
・ At the start of water pump operation due to completion of engine warm-up operation, adverse effects on various parts due to high temperature cooling water flowing out of the water jacket to the cooling water circulation circuit (due to rapid thermal expansion, etc.) Adverse effects), and when a water temperature sensor is installed on the water jacket outlet side, adverse effects on engine operating conditions (such as adverse effects on various engine controls) caused by the rapid increase in the temperature detected by the water temperature sensor Concerned.

  As a cooling system for the engine, a water jacket for a cylinder head (hereinafter sometimes referred to as “head-side water jacket”) and a water jacket for a cylinder block (hereinafter referred to as “block-side water jacket”) are used for the water pump. In some cases, the two are connected in parallel to each other (generally referred to as “two-system cooling device”; see, for example, Patent Document 2 above). In this dual cooling system, when the engine is cold started, the cooling water is supplied to the head side water jacket while the cooling water supply to the block side water jacket is stopped (the cooling water is driven by driving the water pump). Even if the water is supplied only to the head side water jacket), the temperature of the cooling water in the block side water jacket becomes extremely high, which may cause the same problem as described above.

  In Patent Document 3, a heat exchanger is provided above the engine, and heat is exchanged between the cooling water whose temperature has increased and the low-temperature secondary fluid introduced from the outside. Is disclosed. However, since the heat exchanger disclosed in Patent Document 3 is arranged as a dedicated heat exchanger for cooling the cooling water with the secondary fluid, the weight of the vehicle body is increased. As a result, the fuel consumption rate of the engine deteriorated. In addition, the production cost is not practical.

  The present invention has been made in view of such points, and the object of the present invention is to cause a local increase in the coolant temperature in the coolant flow path of the internal combustion engine without causing a significant increase in the weight of the vehicle body. An object of the present invention is to provide a control device for an internal combustion engine that can be suppressed.

-Principle of solving the problem-
The solution principle of the present invention taken to achieve the above object is that heat is generated between the cooling water whose temperature is locally increased during the warm-up operation of the internal combustion engine and the secondary air supplied to the exhaust system. By performing the replacement, the temperature of the cooling water is lowered and convection of the cooling water is generated inside the internal combustion engine so that the cooling water temperature is made uniform. Further, the heat exchanger that exchanges heat between the cooling water and the secondary air is made to function as an EGR cooler that cools the EGR gas with the cooling water after the warm-up of the internal combustion engine is completed.

-Solution-
Specifically, the present invention relates to a cooling water circulation that performs a cooling water stop operation for stopping the pumping of the cooling water to at least a part of the cooling water flow path formed in the internal combustion engine body during the warm-up operation of the internal combustion engine. A control apparatus for an internal combustion engine having a circuit is assumed. The control device for the internal combustion engine is provided with a heat exchanger and a path switching control means. The heat exchanger is disposed above the cooling water passage where the pumping of the cooling water is stopped when the cooling water stopping operation is being performed, and the cooling water passage where the pumping of the cooling water is stopped The cooling water is allowed to flow between the two. Further, the path switching control means includes a secondary air from a secondary air supply device that supplies secondary air to the exhaust system of the internal combustion engine and a cooling water inside the heat exchanger during the warm-up operation of the internal combustion engine. Between the EGR gas from the exhaust gas recirculation device that recirculates the exhaust gas to the intake system of the internal combustion engine and the cooling water inside the heat exchanger after the warm-up operation of the internal combustion engine is completed. In order to enable heat exchange, the connection state between the supply path of secondary air to the heat exchanger and the reflux path of EGR gas is switched.

  Due to this specific matter, during the warm-up operation of the internal combustion engine, the path switching control means switches so that the secondary air supply path is connected to the heat exchanger. Thereby, heat exchange is performed between the secondary air from the said secondary air supply apparatus, and the cooling water inside a heat exchanger. That is, the cooling water is cooled by the secondary air. Along with the cooling of the cooling water inside the heat exchanger, the temperature difference between the cooling water flow path and the heat exchanger, where the cooling water pumping is stopped when the cooling water stop operation is being executed, is changed. Caused convection occurs. By this convection, the cooling water temperature in each of the cooling water flow path and the heat exchanger is made uniform, and the fact that locally high-temperature cooling water exists is eliminated.

  On the other hand, after the warm-up operation of the internal combustion engine is completed, switching is performed so that the EGR gas recirculation path is connected to the heat exchanger by the path switching control means. Thereby, heat exchange is performed between the EGR gas from the exhaust gas recirculation device and the cooling water inside the heat exchanger. That is, the EGR gas is cooled by the cooling water. As the EGR gas is cooled, the density of the EGR gas can be increased, and the effect of suppressing the combustion temperature by recirculating the EGR gas can be reliably obtained.

  Thus, in the present solution, the heat exchanger has a function of cooling the cooling water with the secondary air and causing convection in the cooling water during the warm-up operation of the internal combustion engine. After the warm-up operation of the engine is completed, the engine functions as an EGR cooler for cooling the EGR gas. For this reason, the EGR cooler provided in the conventional internal combustion engine can be eliminated, and the above-mentioned heat exchanger is provided without significantly increasing the weight of the vehicle body and greatly increasing the manufacturing cost. It is possible to produce an effect.

  Specific examples of the cooling water circulation circuit to which the above solution can be applied include the following plurality of circuit configurations.

  First, the cooling water circulation circuit is provided with a water pump that pumps cooling water from the cylinder block side water jacket of the internal combustion engine body to the cylinder head side water jacket. In the cooling water stop operation, the water pump is stopped to stop the pumping of the cooling water to both the cylinder block side water jacket and the cylinder head side water jacket.

  The cooling water circulation circuit is provided with a water pump that pumps the cooling water from the cylinder block side water jacket of the internal combustion engine body to the cylinder head side water jacket. In the cooling water stopping operation, the cooling water supply path from the water pump to the cylinder block side water jacket is shut off, so that the cooling water is pumped to both the cylinder block side water jacket and the cylinder head side water jacket. Is to stop.

  Further, the cooling water circulation circuit is configured such that the cooling water can be individually pumped to the cylinder block side water jacket and the cylinder head side water jacket of the internal combustion engine body. In the cooling water stop operation, the pumping of the cooling water to the cylinder block side water jacket is stopped, the cooling water is pumped to the cylinder head side water jacket, and the heat exchanger is connected to the cylinder block side water jacket. The cooling water is arranged between the cylinder block water jacket and the cylinder block water jacket.

  In any of these cooling water circulation circuits, the above-mentioned effect (cooling water temperature during warm-up operation) can be achieved without causing a significant increase in the weight of the vehicle body and a significant increase in manufacturing cost due to the provision of the heat exchanger. And cooling effect of EGR gas after completion of warm-up operation). In addition, when cooling water is stopped, the pumping of cooling water to the cylinder block side water jacket is stopped and the cooling water is pumped to the cylinder head side water jacket. May be provided above the water jacket on the cylinder block side, and can be attached, for example, to the side surface of the cylinder head or the like.

  The heat exchanger is attached to the upper surface of the cylinder head.

  The water pump that pumps the cooling water is configured to be able to switch between driving and stopping without depending on the driving of the internal combustion engine.

  Also, a three-way valve to which a pipe extending from the cooling water passage inside the heat exchanger, a secondary air supply pipe constituting the secondary air supply path, and an exhaust recirculation pipe constituting the EGR gas reflux path are respectively connected. Is provided. The path switching control means switches the three-way valve so that the pipe extending from the cooling water passage inside the heat exchanger and the secondary air supply pipe communicate with each other during the warm-up operation of the internal combustion engine. After the warm-up operation is completed, the three-way valve is switched so that the pipe extending from the cooling water passage inside the heat exchanger and the exhaust gas recirculation pipe are communicated with each other.

  In the present invention, warm-up can be performed without causing a significant increase in the weight of the vehicle body or a significant increase in manufacturing cost due to the provision of a heat exchanger that performs heat exchange between the cooling water and the secondary air or EGR gas. It is possible to achieve the cooling effect of cooling water during operation and the effect of cooling EGR gas after completion of the warm-up operation.

It is a figure which shows typically the cooling water circulation circuit and engine intake / exhaust system which concern on embodiment. It is the bottom view which fractured | ruptured a part of heat exchanger. It is sectional drawing of the heat exchanger in the position corresponding to the III-III line in FIG. It is a block diagram which shows the structure of control systems, such as ECU. It is a flowchart figure which shows the procedure of heat exchange switching operation | movement. It is a schematic diagram for demonstrating the state of the cooling water during the engine warming-up operation, and the supply state of secondary air. It is a schematic diagram for demonstrating the state of the cooling water after the engine warm-up completion, and the supply state of EGR gas. It is a figure which shows typically the cooling water circulation circuit and the intake / exhaust system of an engine in a 1st modification. It is a figure which shows typically the cooling water circulation circuit and the intake / exhaust system of an engine in a 2nd modification.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present embodiment, a case where the present invention is applied to a multi-cylinder gasoline engine (internal combustion engine) mounted on an automobile will be described.

  FIG. 1 is a diagram schematically showing a cooling water circulation circuit 1 and an intake / exhaust system 2 and 3 of an engine according to the present embodiment. Hereinafter, the configuration of the cooling water circulation circuit 1 and the intake and exhaust systems 2 and 3 will be specifically described.

-Cooling water circulation circuit-
As shown in FIG. 1, the cooling water circulation circuit 1 according to this embodiment includes a radiator 11, a thermostat 12, a water pump 13, a heater core 14, and pipes H <b> 1, H <b> 2 that connect these devices 11, 12, 13, 14. H3, H4, H5, H6, and H7 are provided.

  Specifically, the lower tank 11a of the radiator 11 and the first inlet 12a of the thermostat 12 are connected by the lower pipe H1, and the outlet 12c of the thermostat 12 and the suction side of the water pump 13 are connected to the pump suction pipe. Connected by H2.

  Further, the discharge side of the water pump 13 communicates with a water jacket (cooling water flow path) 15 formed in an engine body (hereinafter also referred to simply as “engine”) E.

  The water jacket 15 includes a cylinder block side water jacket 15a formed inside the cylinder block E1, and a cylinder head side water jacket formed inside the cylinder head E2 and connected to the downstream side of the cylinder block side water jacket 15a. 15b. Therefore, in this water jacket 15, the cooling water (heat recovery medium) discharged from the water pump 13 passes through the cylinder block side water jacket 15a and is then introduced into the cylinder head side water jacket 15b.

  Further, the cooling water flowing through the cylinder head side water jacket 15b is taken out from the engine body (internal combustion engine body) E through the take-out pipe H3. The take-out pipe H3 is branched, and one is connected to the upper tank 11b of the radiator 11 by an upper pipe H4. The other of the extraction pipes H3 is connected to the heater core 14 by a heater pipe H5.

  A bypass pipe H6 is connected to the upper pipe H4, and a downstream end of the bypass pipe H6 is connected to the second inlet 12b of the thermostat 12. Further, the heater core 14 and the suction side of the water pump 13 (the pump suction pipe H2) are connected by a heater outlet pipe H7. The above is the basic circuit configuration of the coolant circulation circuit 1. Other circuit configurations (circuit configurations characterized in this embodiment) will be described later.

  Hereinafter, the configuration and function of each device constituting the cooling water circulation circuit 1 will be briefly described.

  The radiator 11 is of a down flow type, and a radiator core 11c is provided between the upper tank 11b and the lower tank 11a. As a result, when cooling water recovered from the engine body E through the upper pipe H4 to the upper tank 11b flows down into the radiator core 11c toward the lower tank 11a, the outside air (air flow by driving air or driving of the cooling fan) is reduced. The cooling water is cooled by exchanging heat between them and dissipating heat to the outside air.

  The thermostat 12 adjusts the temperature of the cooling water by switching the water channel of the cooling water circulation circuit 1. For example, the thermostat 12 uses the thermal expansion of the wax sealed inside, and the valve provided in accordance with the cooling water temperature. It has a mechanism that can be opened and closed.

  When the engine body E is cold, that is, when the coolant temperature is relatively low, the first inlet 12a of the thermostat 12 is closed and the second inlet 12b is opened, so that the water pump 13 At the time of driving, the flow of the cooling water from the lower tank 11a of the radiator 11 toward the water pump 13 is stopped and the cooling water flows from the bypass pipe H6 toward the water pump 13. That is, the cooling water circulation operation without using the radiator 11 is performed.

  On the other hand, after the engine body E has been warmed up, that is, when the coolant temperature is relatively high, the second inlet 12b of the thermostat 12 is closed and the first inlet 12a is opened, and the bypass pipe The flow of the cooling water from H6 toward the water pump 13 is stopped and the cooling water flows from the lower tank 11a of the radiator 11 toward the water pump 13. That is, by performing a cooling water circulation operation in which the cooling water flows through the radiator 11, the heat recovered by the cooling water is released to the atmosphere by the radiator 11.

  The water pump 13 is for generating a water flow in the cooling water circulation circuit 1 and is constituted by an electric water pump that can be switched between driving and stopping independently of driving of the engine E. The water pump 13 is not limited to an electric type, and may be driven by receiving a rotational driving force of a crankshaft that is an output shaft of the engine E. In this case, a clutch mechanism is interposed between the drive shaft of the water pump 13 and the crankshaft. When the engine E is in a driving state, the water pump 13 is driven when the clutch mechanism is in an engaged state, and the clutch mechanism is The water pump 13 is configured to stop when in the released state.

  The heater core 14 is for heating the passenger compartment using the heat of the cooling water, and faces the air duct of an air conditioner (not shown). In other words, the air-conditioned air flowing through the air duct is passed through the heater core 14 when the vehicle interior is heated and supplied to the vehicle interior as warm air, while the air-conditioned air bypasses the heater core 14 in other cases (for example, during cooling). ing.

  Further, as the cooling water circulation operation in the cooling water circulation circuit 1 according to the present embodiment, the water pump 13 is stopped when the engine E is cold started. That is, the temperature of the cylinder block E1 and the cylinder head E2 is quickly increased by stopping the water pump 13 and not circulating the cooling water in the cooling water circulation circuit 1 (cooling in the present invention). (Execution of cooling water stop operation for stopping pumping of cooling water to the water flow path). As a result, the fuel consumption rate is improved by reducing the friction loss at various locations in the engine within a short period after the engine is started. Hereinafter, this operation state is referred to as “cold start initial operation”.

  Then, when the warm-up operation of the engine E is executed for a predetermined period, the water pump 13 is driven. At this time, since the cooling water temperature (the temperature of the cooling water existing in the thermostat 12) is still low, the thermostat 12 has the first inlet 12a closed and the second inlet 12b opened. As described above, the cooling water circulation operation that does not use the radiator 11 is started. That is, the cooling water discharged from the water pump 13 is taken out from the take-out pipe H3 through the cylinder block side water jacket 15a and the cylinder head side water jacket 15b. A part of the cooling water taken out from the take-out pipe H3 returns to the water pump 13 through the upper pipe H4, the bypass pipe H6, the thermostat 12 and the pump suction pipe H2. The other cooling water taken out from the take-out pipe H3 returns to the water pump 13 through the heater pipe H5, the heater core 14, the heater outlet pipe H7, and the pump suction pipe H2. Hereinafter, this operation state is referred to as “semi-warm-up operation”.

  Thereafter, when the warm-up operation of the engine E is completed, the second inlet 12b of the thermostat 12 is closed and the first inlet 12a is opened, and a cooling water circulation operation for flowing cooling water to the radiator 11 is started. It will be. That is, the cooling water discharged from the water pump 13 is taken out from the take-out pipe H3 through the cylinder block side water jacket 15a and the cylinder head side water jacket 15b. A part of the cooling water taken out from the take-out pipe H3 returns to the water pump 13 through the upper pipe H4, the radiator 11, the lower pipe H1, the thermostat 12, and the pump suction pipe H2. The other cooling water taken out from the take-out pipe H3 returns to the water pump 13 through the heater pipe H5, the heater core 14, the heater outlet pipe H7, and the pump suction pipe H2. Hereinafter, this operation state is referred to as “operation after completion of warm-up”.

-Engine E intake and exhaust systems 2,3-
Next, the intake and exhaust systems 2 and 3 of the engine E will be described. The engine E according to the present embodiment supplies an air-fuel mixture obtained by mixing air supplied from the intake system 2 and fuel supplied from a fuel supply system (not shown) at an appropriate air-fuel ratio to the combustion chamber for combustion. After that, the exhaust gas generated by the combustion is discharged from the exhaust system 3 to the atmosphere.

  The intake system 2 includes an intake pipe 21, and an air cleaner 22, a throttle body 23, and a surge tank 24 are provided on the intake pipe 21 from the upstream side to the downstream side of the intake flow. An intake manifold 25 is connected to the downstream end of the intake pipe 21, and intake air is diverted into each cylinder of the engine body E by the intake manifold 25. The internal space of each member constitutes an intake passage for introducing intake air into each cylinder of the engine body E.

  On the other hand, the exhaust system 3 includes an exhaust manifold 31 attached to the engine body E, and an exhaust pipe 32 connected to the exhaust manifold 31, and exhaust gas is exhausted by an internal space between the exhaust manifold 31 and the exhaust pipe 32. An exhaust passage for discharging gas is configured.

  Two catalysts 33 and 34 are installed in the exhaust pipe 32 in series, and the exhaust gas is purified by the two catalysts 33 and 34.

  Of these catalysts 33, 34, the catalyst 33 installed upstream of the exhaust gas flow direction in the exhaust pipe 32 is a so-called start catalyst (S / C). On the other hand, the catalyst 34 installed on the downstream side in the exhaust gas flow direction in the exhaust pipe 32 is a so-called main catalyst (M / C) or underfloor catalyst (U / F).

  These catalysts 33 and 34 are both constituted by, for example, a three-way catalyst. This three-way catalyst exhibits a purifying action in which carbon monoxide (CO), hydrocarbon (HC), and nitrogen oxide (NOx) are collectively changed to harmless components by a chemical reaction.

-Heat exchange structure-
Next, a configuration that characterizes the present embodiment will be described.

  In the engine E in the present embodiment, the heat exchanger 4 is disposed on the upper part of the cylinder head E2. The heat exchanger 4 is for exchanging heat between the cooling water in the cooling water circulation circuit 1 and air or EGR (Exhaust Gas Recirculation) gas. That is, a cooling water passage 4a and a gas passage 4b are provided in the heat exchanger 4, and the cooling water existing in the cooling water passage 4a (or flowing through the cooling water passage 4a) and gas Heat exchange is performed with a gas (secondary air or EGR gas described later) flowing through the passage 4b. This will be specifically described below.

(Heat exchanger 4)
The cooling water passage 4a provided in the heat exchanger 4 is branched from the cylinder head side water jacket 15b. In other words, the cooling water passage 4a is capable of mutual circulation of cooling water with the cylinder head side water jacket 15b. Further, when the water pump 13 is driven, a part of the cooling water flowing through the cylinder head side water jacket 15b flows into the cooling water passage 4a of the heat exchanger 4 and exchanges heat with the gas flowing through the gas passage 4b. After that, it joins the cooling water flowing through the cylinder head side water jacket 15b. The combined cooling water is taken out from the engine body E through the take-out pipe H3.

  On the other hand, the gas passage 4b provided inside the heat exchanger 4 has one end connected to a switching valve (path switching valve) 53 formed of a three-way valve via a low temperature side pipe 51, while the other end is hot. The exhaust manifold 31 is connected via a side pipe 52.

  Here, the structure of the heat exchanger 4 will be specifically described. FIG. 2 is a bottom view in which a part of the heat exchanger 4 is broken (the front surface in FIG. 2 is attached to the upper surface of the cylinder head E2). 3 is a sectional view of the heat exchanger 4 at a position corresponding to the line III-III in FIG. As shown in these drawings, the heat exchanger 4 is configured as a shell and tube type, and includes a cylindrical heat exchanger casing 41 and a plurality of pieces disposed inside the heat exchanger casing 41. Are provided with flat pipes 42, 42,..., And headers (collecting pipes) 43, 44 on the low temperature side and the high temperature side disposed on both sides of the heat exchanger casing 41.

  The heat exchanger casing 41 is formed of a cylindrical body having a rectangular cross section, and is provided at a casing main body portion 45 located at a central portion in the longitudinal direction and both ends of the casing main body portion 45 in the longitudinal direction. Inflow and outflow side enlarged portions 46 and 47 are provided. The casing main body 45 and the enlarged portions 46 and 47 are both rectangular in cross section, and the cross sectional shape of the enlarged portions 46 and 47 is set larger than the cross sectional shape of the casing main body 45. A cooling water inlet 46a for inflowing cooling water from the cylinder head side water jacket 15b is formed in the inflow side enlarged portion 46 located on the left side in the drawing. On the other hand, the outflow side enlarged portion 47 located on the right side in the figure is formed with a cooling water outlet 47a for flowing out the cooling water toward the cylinder head side water jacket 15b. The cooling water passage 4a is configured by the cooling water inlet 46a, the cooling water outlet 47a, and the internal space of the heat exchanger casing 41 (the outer space of the pipes 42, 42,...).

  Each end of the pipes 42, 42,... Penetrates through the partition walls 46b, 47b of the enlarged portions 46, 47 and communicates with the inside of the headers 43, 44. Specifically, the left end of each pipe 42, 42,... In the drawing passes through the partition wall 46 b of the inflow side enlarged portion 46 and communicates with the internal space of the low temperature side header 43, while each pipe 42, 42,. The right end in the figure passes through the partition wall 47 b of the outflow side enlarged portion 47 and communicates with the internal space of the high temperature side header 44.

  The low temperature side pipe 43 is connected to the low temperature side header 43. On the other hand, the high temperature side pipe 52 is connected to the high temperature side header 44. The gas passage 4b is constituted by the internal space of each of the headers 43, 44 and the internal space of the pipes 42, 42,.

  In addition, as a structure of the heat exchanger 4, it is not limited to what was mentioned above, What is necessary is just a structure in which heat exchange is possible between cooling water and gas (secondary air or EGR gas).

(Secondary air supply device and EGR device)
A secondary air supply device 6 and an EGR (exhaust gas recirculation) device 7 are connected to the switching valve 53, and the switching operation of the switching valve 53 causes the secondary air supply device 6 to exchange heat via the low temperature side pipe 51. The state in which the EGR device 7 is connected (communication) to the gas passage 4b of the heat exchanger 4 and the state in which the EGR device 7 is connected (communication) to the gas passage 4b of the heat exchanger 4 via the low temperature side pipe 51 are switched. . Hereinafter, the secondary air supply device 6 and the EGR device 7 will be described.

  The secondary air supply device 6 includes a secondary air supply pipe 61 connected to the switching valve 53. On the secondary air supply pipe 61, the switching valve 53 side (heat exchanger 4 side) from the outside air intake side. An air filter 62, an air pump 63, and an air switching valve 64 are arranged in this order.

  The air filter 62 purifies the outside air introduced into the secondary air supply pipe 61 as the air pump 63 is driven.

  The air pump 63 sucks outside air, passes through the switching valve 53, the low temperature side pipe 51, the heat exchanger 4, and the high temperature side pipe 52 through the secondary air supply pipe 61, and then the exhaust system 3 (specifically, the exhaust gas) of the engine E. This outside air is supplied as secondary air to the manifold 31). Specifically, the air pump 63 is an electric air pump, and the impeller is rotated by power supplied from a battery (storage battery) (not shown) in accordance with a drive command signal from an ECU 8 (see FIG. 4) described later, thereby supplying secondary air. Air (secondary air) is pumped to the pipe 61. Further, since the high temperature side pipe 52 is branched so as to correspond to each cylinder (four cylinders) and connected to the exhaust manifold 31, the pressurized secondary air is diverted to each branch pipe of the exhaust manifold 31. Will be.

  The air switching valve 64 is composed of an electromagnetically driven on / off valve and has a function of opening / closing the secondary air supply pipe 61. When the air switching valve 64 is in the open state, the secondary air is allowed to flow through the secondary air supply pipe 61. On the other hand, when the air switching valve 64 is in the closed state, the circulation of the secondary air in the secondary air supply pipe 61 is prohibited. The air switching valve 64 is a normally closed electromagnetic on-off valve that is closed in a normal state and is opened in accordance with an open command signal from the ECU 8.

  The EGR device 7 is for reducing a combustion temperature in the combustion chamber by recirculating a part of the exhaust gas of the exhaust system 3 to the intake system 2, thereby reducing the amount of NOx generated. Specifically, the EGR device 7 includes an EGR pipe (exhaust gas recirculation pipe) 71 having one end (upstream end) connected to the switching valve 53 and the other end (downstream end) connected to the surge tank 24. An EGR valve 72 is disposed on the EGR pipe 71. The opening degree of the EGR valve 72 is steplessly adjusted by electronic control, and the exhaust gas recirculation amount flowing through the EGR pipe 71 can be freely adjusted.

-Control system-
The operating state of the engine E, the operating state of the secondary air supply device 6 and the EGR device 7, and the switching operation of the switching valve 53 are controlled by an ECU (Electronic Control Unit) 8. As shown in FIG. 4, the ECU 8 includes a CPU (Central Processing Unit) 81, a ROM (Read Only Memory) 82, a RAM (Random Access Memory) 83, a backup RAM 84, and the like.

  The ROM 82 stores various control programs (for example, a control program for the air pump 63 and the air switching valve 64 in the secondary air supply device 6), a map that is referred to when these various control programs are executed, and the like. The CPU 81 executes arithmetic processing based on various control programs and maps stored in the ROM 82. The RAM 83 is a memory that temporarily stores calculation results in the CPU 81, data input from each sensor, and the like. The backup RAM 84 is a non-volatile memory that stores data to be saved when the engine E is stopped.

  The ROM 82, CPU 81, RAM 83, and backup RAM 84 are connected to each other via a bus 87, and are connected to an external input circuit 85 and an external output circuit 86.

  The external input circuit 85 includes an air flow meter 91 that detects the intake air amount, an air-fuel ratio sensor 92 that detects the air-fuel ratio of the exhaust gas, a water temperature sensor 93 that detects the coolant temperature, and a crankshaft that rotates by a predetermined rotation angle. A crank position sensor 94 for transmitting a pulse signal to the engine, an intake air temperature sensor 95 for detecting the temperature of the intake air built in the air flow meter 91, a throttle opening sensor 96 for detecting the opening of the throttle valve, and the opening of the accelerator pedal. An accelerator opening sensor 97 to be detected is connected. Since the configuration and function of each sensor are well known, description thereof is omitted here.

  On the other hand, the external output circuit 86 includes a throttle motor 9A for driving the throttle valve, an injector 9B for injecting fuel into the cylinder of the engine E, an igniter 9C for adjusting the ignition timing of a spark plug (not shown), and the water pump. 13, the air pump 63, the air switching valve 64, the EGR valve 72, the switching valve 53 and the like are connected.

-Heat exchange operation-
Next, the heat exchange operation using the heat exchanger 4 will be described. The outline of this heat exchange operation will be described. During the warm-up operation of the engine E, the switching valve 53 is switched so that the secondary air supply device 6 and the heat exchanger 4 communicate with each other (the solid line in FIG. 1). Secondary air pumped from the secondary air supply device 6 is introduced into the heat exchanger 4 and heat exchange is performed between the heat exchanger 4 and the cooling water inside the heat exchanger 4. Later, it is introduced into the exhaust manifold 31. That is, heat is taken from the cooling water inside the heat exchanger 4 and the temperature of the cooling water is lowered, and then supplied to the exhaust system 3 to increase the oxygen concentration in the exhaust, and the exhaust pipe 32. The secondary combustion of HC and CO is promoted. In addition, between the heat exchanger 4 and the water jacket 15, the cooling water is cooled by the secondary air in the heat exchanger 4, thereby causing convection of cooling water described later (referred to in the present invention). Operation during warm-up operation of internal combustion engine by path switching control means). This operation is performed in the “cold start initial operation” and the “semi-warm-up operation”.

  On the other hand, after the warm-up of the engine E is completed (in the “operation after the completion of warm-up”), the switching valve 53 is switched so as to connect the EGR device 7 and the heat exchanger 4 (shown by a broken line in FIG. 1). A part of the exhaust gas flowing through the exhaust manifold 31 is introduced into the heat exchanger 4, and after exchanging heat with the cooling water inside the heat exchanger 4, the surge tank 24 To be introduced. In other words, the exhaust gas to be recirculated (EGR gas) is cooled by the cooling water inside the heat exchanger 4 and then introduced into the intake system 2 to increase the density of the exhaust gas and join the intake air flowing through the intake system 2. (Operation after completion of warm-up operation of the internal combustion engine by the path switching control means in the present invention). Hereinafter, the operation for switching between these heat exchange states will be described in detail.

  FIG. 5 is a flowchart showing the procedure of the heat exchange switching operation. This flowchart is executed every several milliseconds after the engine E is started or every predetermined rotation angle of the crankshaft.

  First, in step ST1, it is determined whether or not the engine E is warming up. This determination is made based on the coolant temperature detected by the water temperature sensor 93 immediately before the engine is started and the elapsed time after the engine is started. That is, when the coolant temperature immediately before starting the engine has already reached the warm-up completion temperature (for example, 80 ° C.) (for example, when restarted immediately after the engine E is stopped), the engine E is not warming up. As a result, NO is determined in step ST1. On the other hand, if the coolant temperature immediately before the engine start has not reached the warm-up completion temperature, the time until the engine E warm-up operation is completed based on the deviation between the coolant temperature and the warm-up completion temperature. Is calculated in advance. That is, the larger the deviation is, the longer the time until the warm-up operation of the engine E is completed. Then, after the engine E is started, the engine E is in the warming-up operation until the calculated time (the time for determining that the warming-up operation has been completed) is determined as YES in step ST1, while that When time elapses, it is determined that the warm-up operation of the engine E has been completed, and NO is determined in step ST1.

  The operation for calculating the time until the warm-up operation of the engine E is completed is calculated by storing an arithmetic expression using the cooling water temperature just before the engine start and the elapsed time after the engine start as parameters in the ROM 82. I am doing so. Further, a map for determining the time until the warm-up operation is completed from the coolant temperature immediately before the engine start and the elapsed time after the engine start is stored in the ROM 82, and the warm-up operation is completed by referring to this map. You may make it obtain | require time until. Further, the lubricating oil temperature may be detected by an oil temperature sensor (not shown), and it may be determined whether or not the engine E is warming up based on the lubricating oil temperature.

  If the engine E is in the warm-up operation, YES is determined in step ST1, and the process proceeds to step ST2. In step ST2, the switching valve 53 is switched to the secondary air supply device 6 side (switching state indicated by a solid line in FIG. 1). That is, the secondary air supply pipe 61 of the secondary air supply device 6 is connected (communicated) to the gas passage 4 b of the heat exchanger 4 via the low temperature side pipe 51. In step ST3, the air switching valve 64 is opened and the air pump 63 is driven. More specifically, the air pump 63 is driven to open the air switching valve 64 in a state where the internal pressure of the secondary air supply pipe 61 is higher than the internal pressure of the exhaust pipe 32. That is, after driving the air pump 63, the air switching valve 64 is opened. As a result, in a state in which the exhaust gas is prevented from flowing into the secondary air supply pipe 61, the outside air that has passed through the air filter 62 is converted into secondary air through the secondary air supply pipe 61 through the heat exchanger 4 and the exhaust manifold. Lead to 31. That is, the secondary air supply operation to the exhaust system 3 is started. FIG. 6 is a schematic diagram showing a state of cooling water and a supply state of secondary air during the warm-up operation of the engine E. In FIG. 6, an arrow indicated by a solid line indicates the flow of secondary air, and an arrow indicated by a broken line indicates convection of cooling water between the water jacket 15 and the heat exchanger 4 (this convection will be described later). Show.

  By supplying the secondary air, the oxygen concentration in the exhaust gas increases, and secondary combustion of HC and CO in the exhaust pipe 32 is promoted. As a result, by raising the exhaust gas temperature, it is possible to promote the temperature rise of the catalysts 33 and 34 and to improve the exhaust gas purification rate.

  In such an operation state (warm-up operation of the engine E), the water pump 13 is stopped as described above, and the cooling water is not circulated in the cooling water circulation circuit 1. For this reason, in particular, the cooling water existing around the combustion chamber has a higher temperature than the cooling water existing in other regions due to the increased amount of heat received from the combustion gas. The cooling water that has reached a high temperature as described above flows into the cooling water passage 4a of the heat exchanger 4 from the cylinder head side water jacket 15b due to a density difference due to a temperature difference from the cooling water in other regions. Become.

  In the heat exchanger 4, when the outside air (secondary air) introduced from the secondary air supply device 6 flows through the gas passage 4 b of the heat exchanger 4, the outside air and cooling water (cooling water) Heat exchange with the high-temperature cooling water flowing into the passage 4a is performed. By this heat exchange, the cooling water is cooled by the secondary air and the temperature is lowered, and the secondary air is heated by the cooling water and the temperature is raised.

  For this reason, the temperature of the cooling water existing in the cooling water passage 4a of the heat exchanger 4 becomes lower than the temperature of the cooling water in other regions (for example, in the cylinder block side water jacket 15a), and this temperature difference (density difference). ) Causes the cooling water to flow between the engine E and the heat exchanger 4. That is, the cooling water existing in the cooling water passage 4a of the heat exchanger 4 flows into the cylinder head side water jacket 15b and the cylinder block side water jacket 15a, while the cylinder head side water jacket 15b and the cylinder block side water jacket 15a. The cooling water existing in the jacket 15 a flows into the cooling water passage 4 a of the heat exchanger 4.

  Thus, since the cooling water is circulated by the convection while the water pump 13 is stopped, the cooling water passage 4a of the heat exchanger 4, the cylinder head side water jacket 15b, the cylinder block side The cooling water temperature in each of the water jackets 15a is made uniform, and the fact that locally high-temperature cooling water exists is eliminated.

  In this state, since the secondary air is heated by the cooling water and the temperature rises, secondary combustion of HC and CO in the exhaust pipe 32 is further promoted, and the catalysts 33 and 34 It is possible to greatly promote the temperature rise of the.

  When the warm-up operation of the engine E is completed (when the time has elapsed) from the state where the warm-up operation of the engine E is continued, YES is determined in step ST4, the process proceeds to step ST5, and the switching valve 53 is moved. Is switched to the EGR device 7 side (switching state indicated by a broken line in FIG. 1). That is, the EGR device 7 is connected (communicated) to the gas passage 4 b of the heat exchanger 4 through the low temperature side pipe 51. In step ST6, the air switching valve 64 of the secondary air supply device 6 is closed and the air pump 63 is stopped. Thus, when the EGR valve 72 is opened, the EGR gas can be supplied from the exhaust system 3 to the intake system 2.

  In step ST7, control of the EGR valve 72 is executed. That is, the opening degree of the EGR valve 72 is controlled so that an EGR gas recirculation amount corresponding to the operating state of the engine E is obtained. FIG. 7 is a schematic diagram showing the state of cooling water and the state of supply of ERG gas after the completion of warming up of the engine E. In FIG. 7, arrows indicated by solid lines indicate the flow of EGR gas and the flow of cooling water between the engine E and the heat exchanger 4.

  The opening degree control of the EGR valve 72 is performed according to an EGR valve opening degree map stored in the ROM 82, for example. This EGR valve opening map determines the EGR rate using, for example, the engine load and the engine speed as parameters, and according to the intake air amount detected by the air flow meter 91 so as to obtain this EGR rate. The opening degree of the EGR valve 72 is adjusted.

  When the EGR valve 72 is opened and the exhaust gas recirculation operation is started, the combustion temperature in the combustion chamber is lowered, thereby reducing the amount of NOx generated. In this state, since the EGR gas is cooled by cooling water and the temperature is lowered, the density of the EGR gas to be recirculated can be increased, and the effect of recirculating the EGR gas (combustion temperature suppressing effect) Can be obtained reliably.

  On the other hand, if it is determined in step ST1 that the engine E is not warming up, the process proceeds to step ST7 and the control of the EGR valve 72 is executed without executing the secondary air supply operation. For example, when the engine E is stopped from the warm-up operation complete state and restarted immediately thereafter, NO is determined in step ST1, and the control of the EGR valve 72 is executed without executing the secondary air supply operation. Will do.

  If NO is determined in step ST4, the process proceeds to step ST8, and it is determined whether or not the engine E is stopped by an ignition OFF operation or the like. That is, it is determined whether or not the engine E has been stopped before the warm-up operation of the engine E is completed. If the engine E is not stopped and NO is determined in step ST8, the process returns as it is, and the secondary air supply operation described above is continued.

  On the other hand, if the engine E is stopped and YES is determined in step ST8, the process proceeds to step ST9 where the air switching valve 64 of the secondary air supply device 6 is closed and the air pump 63 is stopped and returned. . That is, the air switching valve 64 and the air pump 63 of the secondary air supply device 6 are returned to the initial state. Here, the reason for closing the air switching valve 64 is to prevent the exhaust gas from flowing into the secondary air supply pipe 61 from the exhaust system 3, and moisture contained in the exhaust gas is condensed in the secondary air supply pipe 61. This is to prevent problems due to the occurrence of moisture (preventing that water freezes or the secondary air supply pipe 61 is corroded during low outside air).

  As described above, in the present embodiment, during the warm-up operation of the engine E, the switching valve 53 is switched so that the secondary air supply device 6 and the heat exchanger 4 communicate with each other, thereby cooling the secondary air and the cooling air. Heat is exchanged with water so that cooling water convects between the engine E and the heat exchanger 4. For this reason, while the water pump 13 is in a stopped state, the cooling water is circulated by this convection, so that the high temperature cooling water is locally present. As a result, it is possible to prevent only a part of the cooling water from boiling and causing a cooling water leak, and the amount of thermal expansion around the combustion chamber in the cylinder block E1 is particularly large, resulting in an increase in bore diameter. It is possible to prevent the occurrence of a hitting sound associated with. Further, since the temperature of the cooling water flowing out from the water jacket 15 at the start of driving the water pump 13 is kept relatively low, adverse effects on various parts of the cooling water circulation circuit 1 and adverse effects on the engine operating state can be avoided. it can.

  Further, since the secondary air is heated by the cooling water and the temperature rises, secondary combustion of HC and CO in the exhaust pipe 32 is further promoted, and the temperature of the catalysts 33 and 34 is increased. The exhaust gas purification rate can be improved.

  Further, after the warm-up of the engine E is completed, the switching valve 53 is switched so that the EGR device 7 and the heat exchanger 4 are communicated, and heat exchange is performed between the secondary air and the EGR gas. ing. For this reason, the density of the recirculated EGR gas can be increased, and the effect of recirculating the EGR gas (combustion temperature suppressing effect) can be reliably obtained.

  Thus, the heat exchanger 4 has a function of cooling the cooling water with the secondary air and convection the cooling water between the engine E and the heat exchanger 4 during the warm-up operation of the engine E. After the engine E is warmed up, the engine E functions as an EGR cooler for cooling the EGR gas. For this reason, the EGR cooler with which the conventional engine was equipped can be abolished. As a result, the above effects can be achieved without causing a significant increase in the weight of the vehicle body or a significant increase in manufacturing cost due to the provision of the heat exchanger 4.

-First modification-
The cooling water circulation circuit 1 in the above-described embodiment stops the water pump 13 during the warm-up operation of the engine E. In the present modification, the supply of cooling water to the cylinder block side water jacket 15a and the cylinder head side water jacket 15b is stopped while driving the water pump 13 during the warm-up operation of the engine E. . Here, differences from the above embodiment will be mainly described.

  FIG. 8 is a diagram schematically showing the cooling water circulation circuit 1 and the intake and exhaust systems 2 and 3 of the engine E in the present modification.

  As shown in FIG. 8, the cooling water circulation circuit 1 in the present modification also includes a thermostat 16 on the discharge side of the water pump 13. The heater pipe H5 is provided with an exhaust heat recovery unit 17 for recovering exhaust heat of exhaust gas (applying exhaust gas exhaust heat to cooling water). Since the configuration of the exhaust heat recovery unit 17 is well known, a description thereof is omitted here. In addition, the second outlet 16b in the thermostat 16 and the upstream side of the exhaust heat recovery unit 17 in the heater pipe H5 are connected by an exhaust heat recovery pipe H8.

  When the engine body E is cold, that is, when the coolant temperature is relatively low, the thermostat 16 closes the first outlet 16a and opens the second outlet 16b. The discharged cooling water returns to the water pump 13 via the thermostat 16 through the exhaust heat recovery pipe H8, the exhaust heat recovery unit 17, the heater core 14, and the heater outlet pipe H7. Thereby, the exhaust heat of the exhaust gas recovered by the exhaust heat recovery device 17 is given to the conditioned air flowing in the air duct by the heater core 14 and contributes to the heating of the vehicle interior. The cooling water circulation path in the cooling water circulation circuit 1 at this time is indicated by a thick line in FIG.

  On the other hand, after the warm-up of the engine body E is completed, that is, when the coolant temperature is relatively high, the thermostat 16 closes the second outlet 16b and opens the first outlet 16a. Cooling water discharged from the pump 13 is taken out from the take-out pipe H3 through the water jackets 15a and 15b via the thermostat 16. The flow of the cooling water after being taken out from the take-out pipe H3 is the same as that after the warm-up is completed in the above-described embodiment.

  Other configurations and operations (such as heat exchange switching operation) are the same as those in the above-described embodiment.

  As described above, in the present embodiment, during the warm-up operation of the engine E, the water pump 13 is driven, but the supply of the cooling water to the cylinder block side water jacket 15a and the cylinder head side water jacket 15b is stopped. As a result, the temperatures of the cylinder block E1 and the cylinder head E2 are rapidly increased to reduce the friction loss at various locations in the engine within a short period after the engine is started (for the cooling water flow path in the present invention). Execution of cooling water stop operation to stop pumping of cooling water).

  Even in the configuration having the cooling water circulation circuit 1 configured as described above, the secondary air supply device 6 and the heat exchanger 4 are connected to each other during the warm-up operation of the engine E, as in the case of the above embodiment. The switching valve 53 is switched so as to communicate (see the switching state indicated by the solid line in FIG. 8), and the secondary air pumped from the secondary air supply device 6 is introduced into the heat exchanger 4 and this heat exchange is performed. After exchanging heat with the cooling water inside the vessel 4, the heat is introduced into the exhaust manifold 31. That is, heat is taken from the cooling water inside the heat exchanger 4 and the temperature of the cooling water is lowered, and then supplied to the exhaust system 3 to increase the oxygen concentration in the exhaust, and the exhaust pipe 32. The secondary combustion of HC and CO is promoted. Further, in the heat exchanger 4, the cooling water is convected between the engine E and the heat exchanger 4 by being cooled by the secondary air. Since the cooling water is circulated by this convection, the existence of locally high-temperature cooling water is eliminated.

  On the other hand, after the warm-up of the engine E is completed, the switching valve 53 is switched so that the EGR device 7 and the heat exchanger 4 communicate with each other (see the switching state indicated by the broken line in FIG. 8), and flows through the exhaust manifold 31. Part of the exhaust gas is introduced into the heat exchanger 4, and heat exchange is performed between the heat exchanger 4 and the cooling water inside the heat exchanger 4, and then introduced into the surge tank 24. In other words, the EGR gas to be recirculated is cooled by the cooling water inside the heat exchanger 4 and then introduced into the intake system 2, whereby the density of the exhaust gas can be increased and the effect of recirculating the EGR gas (combustion) It is possible to reliably obtain the temperature suppression effect.

  After the engine E is warmed up, the heat exchanger 4 is made to function as an EGR cooler for cooling the EGR gas, so that the EGR cooler provided in the conventional engine is discarded. Can do. For this reason, the above-described effects can be achieved without causing a significant increase in the weight of the vehicle body or a significant increase in manufacturing cost due to the provision of the heat exchanger 4.

-Second modification-
The cooling water circulation circuit 1 in the above-described embodiment stops the water pump 13 during the warm-up operation of the engine E. In this modification, during the warm-up operation of the engine E, the water pump 13 is driven to stop the supply of the cooling water to the cylinder block side water jacket 15a, while the cooling water is supplied to the cylinder head side water jacket 15b. It is a thing. That is, it is configured as the “dual system cooling device”. Again, differences from the above embodiment will be mainly described.

  FIG. 9 is a diagram schematically showing the coolant circulation circuit 1 and the intake and exhaust systems 2 and 3 of the engine E in the present modification.

  As shown in FIG. 9, the cooling water circulation circuit 1 in this modification includes a thermostat 16 disposed on the discharge side of the water pump 13 and an exhaust heat recovery unit 17 disposed in the heater pipe H5. Then, it is the same as that of the said 1st modification.

  In this modification, the cylinder block side water jacket 15 a and the cylinder head side water jacket 15 b are connected to the water pump 13 in parallel with each other.

  The cylinder block side water jacket 15 a is connected to the first outlet 16 a of the thermostat 16, and the cylinder head side water jacket 15 b is connected to the second outlet 16 b of the thermostat 16. Thereby, the cooling water can be individually pumped to the cylinder block side water jacket 15a and the cylinder head side water jacket 15b.

  And the heat exchanger 4 in this modification is arrange | positioned above the cylinder block E1 (side of the cylinder head E2). The heat exchanger 4 in the present embodiment is also for exchanging heat between the cooling water in the cooling water circulation circuit 1 and air or EGR gas. That is, a cooling water passage 4a and a gas passage 4b are provided in the heat exchanger 4, and the cooling water existing in the cooling water passage 4a (or flowing through the cooling water passage 4a) and gas Heat exchange is performed with the gas (secondary air or EGR gas) flowing through the passage 4b. The cooling water passage 4a communicates with the cylinder block side water jacket 15a, and the cooling water can mutually flow with the cylinder block side water jacket 15a. That is, the cooling water passage 4a can convect the cooling water with the cylinder block side water jacket 15a. The cylinder block-side water jacket 15a is connected to the heater pipe H5 by a take-out pipe H9.

  On the other hand, the gas passage 4 b provided inside the heat exchanger 4 is connected to a switching valve 53 formed of a three-way valve on one end side via a low temperature side pipe 51, while the other end side is connected to a high temperature side pipe 52. Are connected to the exhaust manifold 31.

  The cylinder head side water jacket 15b does not communicate with the cooling water passage 4a of the heat exchanger 4, and is connected to the upper pipe H4 and the heater pipe H5 by the take-out pipe H3.

  When the engine body E is cold, that is, when the coolant temperature is relatively low, the first outlet 16a of the thermostat 16 is closed and the second outlet 16b is opened and discharged from the water pump 13. The cooled water is supplied to the cylinder head side water jacket 15b through the thermostat 16. At this time, since the cooling water is not supplied to the cylinder block-side water jacket 15a, the temperature of the cylinder block E1 can be quickly increased (the cooling water stop for stopping the pumping of the cooling water to a part of the cooling water flow path in the present invention). Execution of action).

  In such a situation, the switching valve 53 is switched to the secondary air supply device 6 side, the air switching valve 64 is opened, and the air pump 63 is driven. Thereby, the secondary air pumped from the secondary air supply device 6 is introduced into the heat exchanger 4, and after exchanging heat with the cooling water inside the heat exchanger 4, the exhaust manifold 31. To be introduced. That is, heat is taken from the cooling water inside the heat exchanger 4 and the temperature of the cooling water is lowered, and then supplied to the exhaust system 3 to increase the oxygen concentration in the exhaust, and the exhaust pipe 32. The secondary combustion of HC and CO is promoted. Further, in the heat exchanger 4, convection is generated between the cooling water passage 4 a of the heat exchanger 4 and the cylinder block side water jacket 15 a by cooling the cooling water with the secondary air.

  Further, after the engine body E has been warmed up, that is, when the coolant temperature is relatively high, both the first outlet 16a and the second outlet 16b of the thermostat 16 are opened and discharged from the water pump 13. The cooled water is supplied to the water jackets 15a and 15b via the thermostat 16.

  In such a situation, the switching valve 53 is switched to the EGR device 7 side. Thus, when the EGR valve 72 is opened, the EGR gas from the exhaust system 3 toward the intake system 2 is recirculated, and a part of the exhaust gas flowing through the exhaust manifold 31 is introduced into the heat exchanger 4. The heat exchanger 4 is introduced into the surge tank 24 after exchanging heat with the cooling water. In other words, the recirculated EGR gas is cooled by the cooling water inside the heat exchanger 4 and then introduced into the intake system 2, thereby increasing the density of the exhaust gas and joining the intake air flowing through the intake system 2. .

  Other configurations and operations (heat exchange switching operation and the like) are the same as those of the above-described embodiment and the first modification.

  With the above configuration and operation, the present modification can also achieve the same effects as those of the above-described embodiment and the first modification.

-Other embodiments-
In the embodiment and each modification described above, the case where the present invention is applied to the automobile engine E has been described. The present invention is not limited to this, and can also be applied to engines used other than automobiles.

  In the second modification, the heat exchanger 4 is disposed above the cylinder block E1 (on the side of the cylinder head E2). However, as in the case of the above embodiment, the cylinder head You may make it attach the heat exchanger 4 to the upper surface of E2.

  Further, the water pump 13 in the above-described embodiment and each modified example is one that can be switched between driving and stopping independently of driving of the engine E (for example, an electric water pump). In the first and second modified examples, since the water pump 13 is driven even when the engine E is cold started, the water pump 13 is linked to the drive of the engine E (directly connected to the crankshaft). Also good.

  INDUSTRIAL APPLICABILITY The present invention is applicable to an engine that includes a cooling water circulation circuit that stops circulation of cooling water during a warm-up operation and that can avoid a local rise in the temperature of the cooling water.

1 Cooling Water Circulation Circuit 13 Water Pump 15 Water Jacket (Cooling Water Channel)
15a Cylinder block side water jacket 15b Cylinder head side water jacket 2 Intake system 3 Exhaust system 4 Heat exchanger 4a Cooling water passage 4b Gas passage 51 Low temperature side piping 52 High temperature side piping 53 Switching valve 6 Secondary air supply device 61 Secondary air Supply piping 7 EGR device (exhaust gas recirculation device)
71 EGR piping (exhaust gas recirculation piping)
E Engine body (Internal combustion engine body)
E1 Cylinder block E2 Cylinder head

Claims (7)

Control of an internal combustion engine having a cooling water circulation circuit for executing a cooling water stop operation for stopping the pumping of the cooling water to at least a part of the cooling water flow path formed in the internal combustion engine body during the warm-up operation of the internal combustion engine In the device
Cooling is performed between the cooling water flow path which is disposed above the cooling water flow path where the cooling water pumping is stopped and the cooling water pumping is stopped when the cooling water stopping operation is being performed. A heat exchanger configured to allow mutual flow of water;
While warming up the internal combustion engine, while exchanging heat between secondary air from a secondary air supply device that supplies secondary air to the exhaust system of the internal combustion engine and cooling water inside the heat exchanger After the warm-up operation of the internal combustion engine is completed, heat exchange can be performed between the EGR gas from the exhaust gas recirculation device that recirculates the exhaust gas to the intake system of the internal combustion engine and the cooling water inside the heat exchanger. A control device for an internal combustion engine, comprising: path switching control means for switching a connection state between a secondary air supply path and an EGR gas recirculation path to the heat exchanger. The control apparatus for an internal combustion engine according to claim 1,
The cooling water circulation circuit is provided with a water pump that pumps cooling water from the cylinder block side water jacket of the internal combustion engine body to the cylinder head side water jacket, and this water pump is stopped in the cooling water stop operation. Thus, the control device for the internal combustion engine is configured to stop the pumping of the cooling water to both the cylinder block side water jacket and the cylinder head side water jacket. The control apparatus for an internal combustion engine according to claim 1,
The cooling water circulation circuit is provided with a water pump that pumps the cooling water from the cylinder block side water jacket of the internal combustion engine body to the cylinder head side water jacket. In the cooling water stop operation, the water pump is connected to the cylinder block side. An internal combustion engine characterized in that the cooling water supply path to the water jacket is cut off to stop the pumping of the cooling water to both the cylinder block side water jacket and the cylinder head side water jacket. Control device. The control apparatus for an internal combustion engine according to claim 1,
The cooling water circulation circuit can individually pump cooling water to each of the cylinder block side water jacket and the cylinder head side water jacket of the internal combustion engine body, and in the cooling water stop operation, cooling to the cylinder block side water jacket is possible. Water pumping is stopped, and cooling water is pumped to the cylinder head side water jacket, and the heat exchanger is disposed above the cylinder block side water jacket and the cylinder block side water jacket. A control device for an internal combustion engine, characterized in that the coolant can mutually flow between the two. The control apparatus for an internal combustion engine according to any one of claims 1 to 3,
The control device for an internal combustion engine, wherein the heat exchanger is attached to an upper surface of a cylinder head. In the control device for an internal combustion engine according to any one of claims 1 to 5,
An internal combustion engine control apparatus characterized in that a water pump for pumping cooling water is configured to be switchable between driving and stopping without depending on the driving of the internal combustion engine. The control apparatus for an internal combustion engine according to any one of claims 1 to 6,
A three-way valve to which a pipe extending from a cooling water passage inside the heat exchanger, a secondary air supply pipe constituting the secondary air supply path, and an exhaust recirculation pipe constituting the EGR gas recirculation path is provided. And
The path switching control means switches the three-way valve so that the pipe extending from the cooling water passage inside the heat exchanger and the secondary air supply pipe communicate with each other during the warm-up operation of the internal combustion engine. A control device for an internal combustion engine configured to switch a three-way valve so that a pipe extending from a cooling water passage inside a heat exchanger and an exhaust gas recirculation pipe communicate with each other after the operation is completed.

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