Cooling path structure for internal combustion engine

Abstract

A urea injector path (P2) includes: a radiator passage path (P2A) that branches from a radiator path (P1) after the passage thereof through a radiator core (30b); a radiator bypass path that branches from the radiator path (P1) before the passage thereof through the radiator core (30b); a merged path (P2C) that merges the radiator passage path (P2A) and the radiator bypass path (P2B); a first thermo valve (3) that adjusts the flow rate of cooling water from the radiator passage path (P2A) and the radiator bypass path (P2B) to the merged path (P2C); and a urea injector 36 that is provided on the merged path (P2C). The first thermo valve (3) controls the flow rate of the cooling water from the radiator passage path (P2A) to the merged path (P2C) and the flow rate of the cooling water from the radiator bypass path (P2B) to the merged path (P2C) in accordance with the water temperature (T) of the cooling water.

Description

Cooling passage structure of an internal combustion engine

[0001] The present invention relates to a cooling path structure for an internal combustion engine.

[0002] In water-cooled internal combustion engines installed in vehicles such as automobiles, coolant is circulated by a water pump. Generally, the coolant flows through various devices that require cooling, such as the cylinder head and urea injectors of the internal combustion engine, and then returns to the water pump via a radiator, which is a heat exchanger that cools the coolant using factors such as the wind generated by the vehicle.

[0003] Patent Document 1 discloses connecting a urea solution supply valve cooling circuit that circulates coolant between the internal combustion engine cooling circuit and the urea solution supply valve. The invention of Patent Document 1 aims to provide an exhaust gas purification device for an internal combustion engine that can cool the urea solution supply valve to an appropriate temperature and reduce the size of an electric water pump disposed in the urea solution supply valve cooling circuit.

[0004] Japanese Patent Publication No. 2018-96310

[0005] Fig. 2 of Patent Document 1 shows the flow of coolant during operation after the internal combustion engine has been warmed up. As shown in Fig. 2, coolant that has not passed through the core portion of the radiator, indicated by reference numeral 34B, is supplied to the urea water supply valve, indicated by reference numeral 36. Since the coolant is relatively hot after the internal combustion engine has been warmed up, if high-temperature coolant that has not passed through the core portion of the radiator is supplied to the urea water supply valve, there is a possibility that the urea water supply valve will not be properly cooled.

[0006] Furthermore, Figure 3 of Patent Document 1 shows the flow of coolant during operation before the internal combustion engine has been warmed up. As shown in Figure 3, coolant that has passed through a core portion of a radiator that has been designated by the reference numeral 34B is supplied to the urea water supply valve designated by the reference numeral 36. The coolant before the internal combustion engine has been warmed up is relatively cold, and if this low-temperature coolant passes through the radiator and is further cooled before being supplied to the urea water supply valve, there is a possibility that the urea water supply valve will not be warmed up properly.

[0007] Devices that require cooling and warming with cooling water are not limited to the urea water supply valve, but also include various other devices such as a heater core and an EGR cooler. It is desirable for such devices to be cooled and warmed appropriately to meet desired temperature conditions.

[0008] The present invention has been made in consideration of the above-mentioned circumstances, and its purpose is to provide a cooling path structure for an internal combustion engine that can supply cooling water so as to meet the temperature conditions of devices that require cooling and warming.

[0009] For example, the present invention comprises the following configuration. a first flow rate adjustment valve that adjusts the flow rate of the cooling water from the radiator through the radiator bypass path to the confluence path, and a target device that is provided on the confluence path, wherein the first flow rate adjustment valve adjusts the flow rate of the cooling water from the radiator through the radiator path to the confluence path and the flow rate of the cooling water from the radiator through the radiator path to the confluence path, and the flow rate of the cooling water from the radiator bypass path to the confluence path, in accordance with a temperature of the cooling water.

[0010] According to the present invention, it is possible to provide a cooling path structure for an internal combustion engine that can supply cooling water so as to satisfy the temperature conditions of devices that require cooling and warming.

[0011] Fig. 1 is a diagram showing the cooling path structure of an internal combustion engine. Fig. 2 is a diagram showing the flow of coolant when the coolant temperature T is less than a first temperature T1 (T<T1). Fig. 3 is a diagram showing the flow of coolant when the coolant temperature T is equal to or greater than the first temperature T1 and less than a second temperature T2 (T1≦T<T2). Fig. 4 is a diagram showing the flow of coolant when the coolant temperature T is equal to or greater than the second temperature T2 and less than a third temperature T3 (T2≦T<T3). Fig. 5 is a diagram showing the flow of coolant when the coolant temperature T is equal to or greater than the third temperature T3 (T3≦T).

[0012] Hereinafter, a cooling path structure of an internal combustion engine according to an embodiment of the present invention will be described with reference to the drawings. In the following, the terms "upstream" and "downstream" refer to the upstream and downstream of the cooling water relative to the water pump 6.

[0013] FIG. 1 is a diagram showing the cooling path structure of an internal combustion engine. FIG. 2 is a diagram showing the flow of coolant when the coolant temperature T is less than a first temperature T1 (T<T1). FIG. 3 is a diagram showing the flow of coolant when the coolant temperature T is equal to or greater than the first temperature T1 and less than a second temperature T2 (T1≦T<T2). FIG. 4 is a diagram showing the flow of coolant when the coolant temperature T is equal to or greater than a second temperature T2 and less than a third temperature T3 (T2≦T<T3). FIG. 5 is a diagram showing the flow of coolant when the coolant temperature T is equal to or greater than a third temperature T3 (T3≦T). In FIGS. 2 to 5, solid arrows indicate paths through which coolant circulates, and dashed arrows indicate paths through which coolant does not circulate. Note that the second temperature T2 is higher than the first temperature T1, and the third temperature T3 is higher than the second temperature T2 (T1<T2<T3). For example, the first temperature T1 is 70°C, the second temperature T2 is 80°C, and the third temperature T3 is 85°C.

[0014] As shown in FIG. 1, a cooling path structure 1 for an internal combustion engine 2 includes a plurality of paths through which cooling water circulates, and is a structure for cooling and warming up the internal combustion engine 2 and various devices arranged in the plurality of paths. The cooling path structure 1 of the internal combustion engine 2 includes a first thermostatic valve 3 as a first flow control valve, a second thermostatic valve 4 as a second flow control valve, a water pump (W / P) 6, a cylinder block (C / B) 8, a cylinder head (C / H) 10, an oil cooler (O / C) 13, an EGR cooler (EGR / C) 14, a heater core (HEATER) 16, an EGR valve (EGR / V) 18, an EGR bypass valve (EGR / BV) 20, a turbocharger (T / C) 24, a radiator (RA) 30, a reserve tank (hot bottle) (HB) 32, an electric water pump (E-W / P) 34, and a urea injector 36 (target device).

[0015] The internal combustion engine 2 of this embodiment is a reciprocating engine mounted on a vehicle, in which pistons rotate a crankshaft. The internal combustion engine 2 is a diesel engine equipped with an exhaust gas recirculation system. However, the type of the internal combustion engine 2 is not limited thereto, and it may be, for example, a gasoline engine or an internal combustion engine without an exhaust gas recirculation system.

[0016] The cooling path structure 1 of the internal combustion engine 2 also includes a plurality of paths for supplying coolant to various devices. The cooling path structure 1 of this embodiment includes a radiator path P1, a urea injector path P2, a bypass path P3, an EGR valve path P4, a heater path P5, a supercharger path P6, an air bleed path P7, and a main engine cooling path P8.

[0017] <Radiator path P1 (first path) and main engine cooling path P8> The radiator path P1 can be called the first path that circulates coolant between the internal combustion engine 2 and the radiator 30. The most upstream end of the radiator path P1 is connected to the downstream end of the main engine cooling path P8 that passes through the internal combustion engine 2, and the most downstream end of the radiator path P1 is connected to the second thermostatic valve 4 that is provided upstream of the internal combustion engine 2. The radiator path P1 includes a radiator upstream path P1A that connects the main engine cooling path P8 and the radiator 30, and a radiator downstream path P1B that connects the radiator 30 and the second thermostatic valve 4.

[0018] The radiator 30 has a radiator core 30b as a heat exchanger, an upper tank 30a as a first tank connected to the upstream side of the radiator core 30b and storing the coolant before passing through the radiator core 30b, and a lower tank 30c as a second tank connected to the downstream side of the radiator core 30b and storing the coolant after passing through the radiator core 30b. The radiator core 30b is a heat exchanger having a plurality of fins and exchanging heat between the coolant and the outside air of the vehicle to cool the coolant.

[0019] The coolant circulating through the radiator path P1 passes through the radiator upstream path P1A and the upper tank 30a and the radiator core 30b to be cooled, and then passes through the lower tank 30c and the radiator downstream path P1B to reach the second thermo valve 4. Note that the radiator 30 in this embodiment is a vertical flow radiator that flows coolant from top to bottom, but the type of radiator is not limited thereto, and for example, a horizontal flow radiator that flows coolant horizontally may be used.

[0020] The second thermostatic valve 4, which serves as a second flow control valve, is a device that adjusts the amount of cooling water flowing through a plurality of paths. The second thermostatic valve 4 is connected to the most downstream of each of the paths P1, P3, P5, and P7, and can control the flow rate of cooling water flowing through each of the paths P1, P3, P5, and P7 by varying the opening of a port through which cooling water enters the second thermostatic valve 4 from each of the paths P1, P3, P5, and P7. For example, the second thermostatic valve 4 is a rotary valve having a rotary valve, and the size of the opening area of ​​each port is changed by rotating the rotary valve.

[0021] As described above, the second thermostatic valve 4 of this embodiment is connected to the most downstream portion of the radiator path (first path) P1 and is capable of adjusting the flow rate of the coolant flowing from the radiator 30 to the internal combustion engine 2. When the coolant temperature T is lower than the third temperature T3 (T<T3), as shown in FIGS. 2 to 4 , the second thermostatic valve 4 closes the radiator path P1 to prevent the coolant cooled by the radiator 30 from flowing into the internal combustion engine 2, thereby facilitating the warm-up of the internal combustion engine 2. On the other hand, when the coolant temperature T is equal to or higher than the third temperature T3 (T3≦T), as shown in FIG. 5 , the second thermostatic valve 4 opens the radiator path P1 to allow the coolant to flow from the radiator 30 into the internal combustion engine 2, thereby facilitating the cooling of the internal combustion engine 2.

[0022] A water pump 6 that supplies cooling water to each path is connected downstream of the second thermostatic valve 4. In this embodiment, the water pump 6 is a mechanical pump that receives driving force from the crankshaft of the internal combustion engine 2 to rotate an impeller.

[0023] A main engine cooling path P8 is connected downstream of the water pump 6. The main engine cooling path P8 includes a first water jacket (not shown) formed around the cylinders of the cylinder block 8 and a second water jacket (not shown) formed in the cylinder head. The main engine cooling path P8 is a path formed by the first water jacket and the second water jacket. The upstream end of the first water jacket is connected to the water pump 6, and the downstream end is connected to the radiator upstream path P1A.

[0024] Furthermore, the heater path P5 is connected to the first water jacket upstream of its downstream end, i.e., upstream of the point where it connects to the radiator upstream path P1A. Because the radiator path P1 is a path for lowering the temperature of the coolant in the radiator 30, it is preferable in terms of cooling the internal combustion engine body to supply the coolant to the radiator 30 after passing through the main engine cooling path P8 for as long as possible to absorb as much heat from the internal combustion engine 2 body as possible. On the other hand, since the coolant passing through the heater path P5 is supplied to the oil cooler 13 and used to cool the engine oil, it is preferable that the temperature of the coolant in the heater path P5 be as low as possible. In the cooling path structure 1 for the internal combustion engine 2 of this embodiment, the connection point between the heater path P5 and the main engine cooling path P8 is located upstream of the connection point between the radiator path P1 and the main engine cooling path P8. In other words, the coolant supplied to the heater path P5 passes through the internal combustion engine 2 body a shorter distance than the coolant supplied to the radiator path P1. This allows the heater path P5 to be supplied with coolant at a lower temperature than the radiator path P1, thereby enabling more efficient cooling of the engine oil.

[0025] The second water jacket is connected to the first water jacket, and coolant flows in from the first water jacket and is discharged to the first water jacket. An air bleeding path P7, which will be described later, is also connected to the second water jacket.

[0026] <Urea injector path P2 (second path)> The urea injector path P2 can be referred to as a second path that branches off from the radiator path (first path) P1 and returns the coolant to the internal combustion engine 2. The urea injector path P2 is provided with, in this order from the upstream side, a first thermostatic valve 3, an electric water pump 34, and a urea injector 36.

[0027] The urea injector path P2 includes a radiator passing path P2A that branches off from the radiator path P1 and through which coolant that has passed through the radiator core 30b flows, a radiator bypass path P2B that branches off from the radiator path P1 and through which coolant that has not passed through the radiator core 30b flows, a confluence path P2C where the radiator passing path P2A and the radiator bypass path P2B converge, and a first thermostatic valve 3 that serves as a first flow control valve.

[0028] In this embodiment, the most upstream of the radiator passing path P2A is connected to the lower tank (second tank) 30c of the radiator 30, and the most upstream of the radiator bypass path P2B is connected to the upper tank (first tank) 30a of the radiator 30. Note that the radiator passing path P2A does not need to be directly connected to the lower tank (second tank) 30c of the radiator 30, as long as it branches off from a location after passing through the radiator core 30b, and may be connected to, for example, the radiator downstream path P1B of the radiator path P1. Also, the radiator bypass path P2B does not need to be directly connected to the upper tank (first tank) 30a of the radiator 30, as long as it branches off from a location before passing through the radiator core 30b, and may be connected to, for example, the radiator upstream path P1A of the radiator path P1.

[0029] The most upstream portion of the merging path P2C is connected to the radiator passing path P2A and the radiator bypass path P2B, and the most downstream portion of the merging path P2C is connected to the heater path P5 downstream of the heater core 16. An electric water pump 34 and a urea injector 36 are arranged in this order from the upstream side on the merging path P2C.

[0030] The first thermostatic valve 3 adjusts the flow rate of coolant from the radiator passage P2A and the radiator bypass passage P2B to the merged passage P2C. In this embodiment, the first thermostatic valve 3 is provided at the upstream end of the merged passage P2C, i.e., at the junction of the radiator passage P2A and the radiator bypass passage P2B. That is, the most upstream portion of the merged passage P2C is connected to the radiator passage P2A and the radiator bypass passage P2B via the first thermostatic valve 3. The first thermostatic valve 3 has a known structure, such as a wax-type temperature control valve incorporating a wax element and a spring. The wax-type temperature control valve does not require external power or a temperature sensor to operate the first thermostatic valve 3, making it less expensive and simpler in configuration than a solenoid valve or the like. In particular, the first thermostatic valve 3 does not require a power supply even after the internal combustion engine 2 is stopped, which is advantageous in terms of regulating the coolant temperature after the internal combustion engine 2 is stopped.

[0031] Note that the first flow rate control valve is not limited to the above-described mechanical first thermostatic valve 3, as long as it controls the flow rate of coolant from the radiator passing path P2A to the junction path P2C and the flow rate of coolant from the radiator bypass path P2B to the junction path P2C in accordance with the coolant temperature. For example, the first flow rate control valve may be an electromagnetic valve equipped with a temperature sensor, or a first thermostatic valve 3 may be provided in each of the radiator passing path P2A and the radiator bypass path P2B.

[0032] The first thermostatic valve 3 can appropriately adjust the temperature T of the coolant supplied to the merging path P2C. Therefore, when the urea injector 36, which is a device that requires cooling and warming, is arranged in the merging path P2C as in this embodiment, the coolant can be supplied so as to satisfy the temperature conditions of the urea injector 36. Furthermore, since the coolant whose temperature has been appropriately adjusted is returned to the internal combustion engine 2, the internal combustion engine 2 can be efficiently cooled and warmed up.

[0033] 2 , when the coolant temperature T is lower than a first temperature T1 (T<T1), the first thermostatic valve 3 closes the radiator passage P2A to prevent the coolant from flowing from the radiator passage P2A into the junction passage P2C, and opens the radiator bypass passage P2B to allow the coolant to flow from the radiator bypass passage P2B into the junction passage P2C. If the coolant were allowed to flow from the radiator passage P2A into the junction passage P2C when T<T1 and the coolant temperature is relatively low, the low-temperature coolant that has passed through the radiator core 30b and cooled would be supplied to the urea injector 36, which could adversely affect the function of the urea injector 36. Furthermore, since the cooled low-temperature coolant also circulates through other paths, it may adversely affect the warm-up performance of the internal combustion engine 2 and various devices (oil cooler 13, EGR cooler 14, heater core 16, EGR valve 18, EGR bypass valve 20, and turbocharger 24). Therefore, in this embodiment, the coolant is only allowed to flow from the radiator bypass path P2B into the merging path P2C, thereby facilitating the warm-up of the internal combustion engine 2 and various devices.

[0034] On the other hand, as shown in FIGS. 4 and 5 , when the coolant temperature T is equal to or higher than a second temperature T2 (T2≦T), the first thermostatic valve 3 opens the radiator passage P2A to allow the coolant to flow from the radiator passage P2A to the junction passage P2C, and closes the radiator bypass passage P2B to prevent the coolant from flowing from the radiator bypass passage P2B to the junction passage P2C. When T2≦T and the coolant temperature is relatively high, the coolant needs to be cooled to cool the urea injector 36. Therefore, in this embodiment, the coolant is only allowed to flow from the radiator passage P2A that has passed through the radiator core 30b to the junction passage P2C, thereby promoting cooling of the urea injector 36. Furthermore, the cooled coolant also flows back into the internal combustion engine 2 and various devices, which may adversely affect the cooling performance of the internal combustion engine 2 and various devices. Therefore, in this embodiment, the cooling water is only allowed to flow from the radiator passage P2A to the merging passage P2C, thereby promoting the cooling of the internal combustion engine 2 and various devices.

[0035] 3 , when the coolant temperature T is equal to or higher than a first temperature T1 and lower than a second temperature T2 (T1≦T<T2), the first thermostatic valve 3 opens the radiator passing path P2A and the radiator bypass path P2B to allow the coolant to flow from the radiator passing path P2A to the merging path P2C and the coolant to flow from the radiator bypass path P2B to the merging path P2C. That is, the relatively low-temperature coolant from the radiator passing path P2A and the relatively high-temperature coolant from the radiator bypass path P2B are mixed together to adjust the temperature of the coolant supplied to the urea injector 36.

[0036] The drive of the electric water pump 34 is controlled by a control device (not shown), and the amount of coolant circulating in the urea injector path P2 can be adjusted. Unlike the mechanical water pump 6, which is powered by the internal combustion engine 2, the electric water pump 34 has a power source (such as a 12V battery) separate from the internal combustion engine 2, and therefore can be controlled to drive even after the internal combustion engine 2 is stopped. Therefore, for example, even when the internal combustion engine 2 is stopped when the coolant temperature is high, the electric water pump 34 can be driven to circulate coolant through the urea injector path P2 and cool the urea injector 36.

[0037] The urea injector 36 is a component of a urea SCR (Selective Catalytic Reduction) system and supplies urea water to a selective catalytic reduction catalyst in the exhaust pipe of the internal combustion engine 2. In the urea SCR system, urea water added to exhaust gas is hydrolyzed into ammonia by the heat of the exhaust. When the exhaust gas containing the ammonia flows into the selective catalytic reduction catalyst, NOx in the exhaust gas is reduced into nitrogen and water using the ammonia as a reducing agent. If the temperature of the urea injector 36 is too low, the urea water will freeze inside the urea injector 36, and the frozen urea water will not be able to melt, making it impossible to inject the urea water. Furthermore, if the temperature of the urea injector 36 is too high, the urea injector 36 will be damaged. As described above, the urea injector 36 has a temperature limit for use. However, as described above, the junction path P2C in which the urea injector 36 is located is supplied with cooling water at an appropriate temperature, so that the temperature conditions for the urea injector 36 can be satisfied.

[0038] <Bypass Path P3 (Third Path)> The bypass path P3 can be referred to as a third path that branches off from the radiator upstream path P1A of the radiator path (first path) P1 and returns the coolant to the internal combustion engine 2. In this embodiment, the bypass path P3 is connected to the radiator upstream path P1A. Regardless of the open / close state of the second thermostatic valve 4, flowing a portion of the coolant heading toward the radiator 30 via the radiator upstream path P1A into the bypass path P3 has the effect of releasing the water pressure of the coolant and reducing the load on the piping constituting each path and the water pump 6. Furthermore, during warm-up operation, when the coolant temperature T is relatively low, the coolant circulates through the bypass path P3 without passing through the radiator core 30b, thereby allowing the coolant to warm up quickly and facilitating the warm-up of the internal combustion engine 2 and various devices.

[0039] <EGR valve path P4 and heater path P5> The most upstream portion of the EGR valve path P4 is connected to the radiator upstream path P1A of the radiator path P1, and the most downstream portion of the EGR valve path P4 is connected to the heater path P5 downstream of the heater core 16. An EGR valve 18 and an EGR bypass valve 20 are arranged in the EGR valve path P4 in this order from the upstream side.

[0040] The most upstream portion of the heater path P5 is connected to the main engine cooling path P8, and the most downstream portion of the heater path P5 is connected to the second thermo valve 4. An oil cooler 13, an EGR cooler 14, and a heater core 16 are arranged in the heater path P5 in this order from the upstream side.

[0041] The cooling path structure 1 of this embodiment has an exhaust gas recirculation (EGR) device that circulates exhaust gas from the internal combustion engine 2 into the intake air. The EGR device is provided with an EGR valve 18 that controls the amount of exhaust gas introduced into the intake air. The EGR gas circulated by the EGR device is cooled by an EGR cooler 14.

[0042] As described above, the most downstream portions of the urea injector path P2 and the EGR valve path P4 are connected to the heater path P5 downstream of the heater core 16. Therefore, when the port of the second thermo valve 4 to which the heater path P5 is connected opens, the coolant flows through the urea injector path P2, the EGR valve path P4, and the heater path P5.

[0043] The oil cooler 13 is a heat exchanger that exchanges heat between the engine oil filled in the internal combustion engine 2 and the cooling water. In this embodiment, the oil cooler 13 is attached to the main body of the internal combustion engine 2.

[0044] The heater core 16 is a heat exchanger of an air conditioner that supplies conditioned air to the interior of the vehicle. The heater core 16 absorbs heat from the coolant and heats the conditioned air.

[0045] <Supercharger path P6> The most upstream portion of the supercharger path P6 branches off from the main engine cooling path P8, and the most downstream portion of the supercharger path P6 is connected to the reserve tank 32. A supercharger 24 is disposed in the supercharger path P6. The supercharger 24 is a device that supercharges the intake air of the internal combustion engine 2. Cooling water flowing through the supercharger path P6 cools the supercharger 24.

[0046] <Air bleeding path P7> The most upstream portion of the air bleeding path P7 is connected to the cylinder head 10 of the internal combustion engine 2, and the most downstream portion of the air bleeding path P7 is connected to the second thermostatic valve 4. In the air bleeding path P7, an upper tank 30a of the radiator 30 and a reserve tank 32 are arranged in this order from the upstream side.

[0047] The air bleed path P7 includes an upstream air bleed path P7A connecting the cylinder head 10 and the upper tank 30a, a midstream air bleed path P7B connecting the upper tank 30a and the reserve tank 32, and a downstream air bleed path P7C connecting the reserve tank 32 and the second thermo valve 4.

[0048] The reserve tank 32 functions as a tank for temporarily storing the coolant, and also functions as a tank for forming a layer of coolant and air to bleed the coolant. Therefore, the coolant circulating through the air bleed path P7 is bled by the reserve tank 32. In particular, since the reserve tank 32 is connected to the upper tank 30a of the radiator 30, it can also bleed the coolant circulating through the urea injector path P2.

[0049] The reserve tank 32 is also connected to the turbocharger 24 via a turbocharger path P6. The turbocharger 24 comes into contact with the exhaust gas, causing the cooling water to become hot, and the air pressure in the cooling water is likely to increase, but by connecting the turbocharger path P6 to the reserve tank 32, it functions as a buffer that suppresses the increase in air pressure.

[0050] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments and various modifications are possible without departing from the spirit and scope of the invention. In particular, the multiple modified examples described in this specification can be arbitrarily combined as needed. For example, although an example has been described in which the first thermostatic valve 3 serving as the first flow control valve is a wax-type temperature control valve and the second thermostatic valve 4 serving as the second flow control valve is a rotary valve, these valves may have any configuration. Furthermore, although the present embodiment describes an internal combustion engine 2 having a turbocharger 24, the turbocharger 24 is not an essential component.

[0051] As described above, the present specification discloses the following:

[0052] (1) A cooling path structure for an internal combustion engine having a plurality of paths through which coolant circulates, wherein the plurality of paths include: a first path for circulating the coolant between the internal combustion engine and a radiator; and a second path branching from the first path, wherein the second path includes: a radiator passing path branching from the first path at a point after the coolant has passed through a heat exchange section of the radiator; a radiator bypass path branching from the first path at a point before the coolant has passed through the heat exchange section of the radiator; a merging path at which the radiator passing path and the radiator bypass path are joined; a first flow rate adjustment valve adjusting the flow rate of coolant from the radiator passing path and the radiator bypass path to the merging path; and a target device provided on the merging path, wherein the first flow rate adjustment valve controls the flow rate of coolant from the radiator passing path to the merging path and the flow rate of coolant from the radiator bypass path to the merging path in accordance with a temperature of the coolant.

[0053] According to the above configuration, the temperature of the cooling water supplied to the merging path can be appropriately adjusted, so that the cooling water can be supplied so as to satisfy the temperature conditions of the target devices installed in the merging path. Furthermore, since the cooling water whose temperature has been appropriately adjusted is circulated to the internal combustion engine and other devices via multiple paths, the internal combustion engine and various devices can be efficiently cooled and warmed up.

[0054] (2) The cooling path structure of an internal combustion engine described in (1), wherein the radiator has the heat exchange portion, a first tank in which the cooling water before passing through the heat exchange portion is stored, and a second tank in which the cooling water after passing through the heat exchange portion is stored, the radiator bypass path is connected to the first tank, and the radiator passing path is connected to the second tank.

[0055] According to the above configuration, the radiator bypass path can be supplied with cooling water at the highest possible temperature immediately before passing through the radiator core, and the radiator through path can be supplied with cooling water at the lowest possible temperature immediately after passing through the radiator core.

[0056] (3) The cooling path structure for an internal combustion engine described in (1) or (2), wherein the first flow control valve, when the temperature of the cooling water is lower than a first temperature T1, inhibits the cooling water from flowing from the radiator passage to the confluence path and allows the cooling water to flow from the radiator bypass path to the confluence path, and when the temperature of the cooling water is equal to or higher than a second temperature T2 higher than the first temperature T1, allows the cooling water to flow from the radiator passage to the confluence path and inhibits the cooling water from flowing from the radiator bypass path to the confluence path.

[0057] According to the above configuration, when T<T1 and the coolant temperature is relatively low, the coolant is allowed to flow from the radiator bypass path to the merging path and the flow of coolant from the radiator passing path to the merging path is suppressed, thereby facilitating the warm-up of the target device. Also, when T2≦T and the coolant temperature is relatively high, the coolant is allowed to flow from the radiator passing path to the merging path and the flow of coolant from the radiator bypass path to the merging path is suppressed, thereby facilitating the cooling of the target device.

[0058] (4) The cooling path structure for an internal combustion engine according to any one of (1) to (3), wherein the target device is a urea injector that supplies urea water into an exhaust pipe of the internal combustion engine.

[0059] According to the above configuration, cooling water at an appropriate temperature is supplied to the urea injector, which has a temperature limit for use, so that the temperature conditions of the urea injector can be satisfied.

[0060] (5) The cooling path structure for an internal combustion engine described in (3), wherein a second flow rate control valve is provided in the first path that can adjust the flow rate of the cooling water flowing from the radiator to the internal combustion engine, and the second flow rate control valve allows the cooling water to flow from the radiator to the internal combustion engine when the temperature of the cooling water is equal to or higher than a third temperature T3 that is higher than the second temperature T2, and suppresses the cooling water from flowing from the radiator to the internal combustion engine when the temperature of the cooling water is lower than the third temperature T3.

[0061] According to the above configuration, when T<T3 and the coolant temperature T is relatively low, the second flow control valve closes the first path to suppress the inflow of coolant from the radiator to the internal combustion engine, thereby facilitating the warm-up of the internal combustion engine and various devices. On the other hand, when T3≦T and the coolant temperature T is relatively high, the second flow control valve opens the first path to allow the inflow of coolant from the radiator to the internal combustion engine. At this time, the first flow control valve allows the inflow of coolant from the radiator passage to the merging passage, thereby facilitating the cooling of the internal combustion engine and various devices.

[0062] (6) The cooling path structure of an internal combustion engine according to (2), wherein a reserve tank for bleeding air from the cooling water is connected to the first tank.

[0063] According to the above configuration, since the reserve tank is connected to the first tank of the radiator, it is possible to more reliably bleed air from the cooling water circulating in the second passage connected to this first tank.

[0064] 1 Cooling path structure 2 Internal combustion engine 3 First thermostatic valve (first flow control valve) 4 Second thermostatic valve (second flow control valve) 6 Water pump (W / P) 8 Cylinder block (C / B) 10 Cylinder head (C / H) 13 Oil cooler (O / C) 14 EGR cooler (EGR / C) 16 Heater core (HEATER) 18 EGR valve (EGR / V) 20 EGR bypass valve (EGR / BV) 24 Turbocharger (T / C) 30 Radiator 30a Upper tank (first tank) 30b Radiator core (heat exchange section) 30c Lower tank (second tank) 32 Hot bottle (HB) (reserve tank) 34 Electric water pump (E-W / P) 36 Urea injector (Urea INJ) (Target device) P1 Radiator path (first path) P1A Radiator upstream path P1B Radiator downstream path P2 Urea injector path (second path) P2A Radiator passing path P2B Radiator bypass path P2C Merging path P3 Bypass path (third path) P4 EGR valve path P5 Heater path P6 Turbocharger path P7 Air bleeding path P7A Air bleeding upstream path P7B Air bleeding midstream path P7C Air bleeding downstream path P8 Main engine cooling path T Coolant temperature T1 First temperature T2 Second temperature T3 Third temperature

Claims

1. A cooling path structure for an internal combustion engine, comprising multiple paths through which cooling water circulates, The aforementioned multiple routes are A first path for circulating the coolant between the internal combustion engine and the radiator, A second path that branches off from the first path, Includes, The second route is, A radiator passage path that branches off from the point after the first passage has passed through the heat exchange section of the radiator, A radiator bypass path is provided independently of the radiator passage path and branches off from the point in the first path before it passes through the heat exchange section of the radiator, The merging path formed by the confluence of the radiator passage path and the radiator bypass path, A first flow control valve adjusts the flow rate of coolant from the radiator passage path and the radiator bypass path to the aforementioned merging path, The target device provided in the aforementioned merging path, Includes, The first flow control valve controls the flow rate of the coolant from the radiator passage to the merging passage and the flow rate of the coolant from the radiator bypass passage to the merging passage, according to the coolant temperature. A cooling path structure for an internal combustion engine characterized by the following features.

2. The aforementioned radiator is, The heat exchange section, A first tank in which the cooling water is stored before passing through the heat exchange section, A second tank in which the cooling water after passing through the heat exchange section is stored, It has, The radiator bypass path is connected to the first tank, The radiator passage is connected to the second tank. The cooling path structure for an internal combustion engine according to claim 1.

3. The first flow control valve is When the water temperature of the coolant is less than the first temperature T1, the inflow of the coolant from the radiator passage to the merging passage is suppressed, while the inflow of the coolant from the radiator bypass passage to the merging passage is permitted. When the water temperature of the coolant is higher than the first temperature T1, the flow of the coolant from the radiator passage to the merging passage is permitted, and the flow of the coolant from the radiator bypass passage to the merging passage is suppressed. Cooling path structure for an internal combustion engine according to claim 1 or 2.

4. The aforementioned device is a urea injector that supplies urea solution into the exhaust pipe of the internal combustion engine. Cooling path structure for an internal combustion engine according to any one of claims 1 to 3.

5. A second flow control valve is provided that can adjust the flow rate of the coolant from the radiator to the internal combustion engine in the first path. The second flow control valve is, When the water temperature of the coolant is higher than the second temperature T2, such as a third temperature T3 or higher, the flow of the coolant from the radiator to the internal combustion engine is permitted. If the water temperature of the coolant is less than the third temperature T3, the flow of the coolant from the radiator to the internal combustion engine is suppressed. The cooling path structure for an internal combustion engine according to claim 3.

6. A reserve tank for bleeding air from the cooling water is connected to the first tank. The cooling path structure for an internal combustion engine according to claim 2.