JP6582777B2 - Engine cooling system - Google Patents

Description

  The present invention relates to an engine cooling system applied to a vehicle engine or the like.

  Generally, a vehicular engine cooling system includes a water pump, an engine internal flow path disposed downstream of the water pump, and a cooling circuit including a radiator disposed downstream of the engine internal flow path. Then, cooling water is sequentially sent from the water pump to the engine internal flow path and the radiator, and then returned to the water pump. For convenience, the water pump, the radiator, and the cooling circuit are referred to as a first water pump, a first radiator, and a first cooling circuit, respectively.

Japanese Patent Laying-Open No. 2015-1339

  On the other hand, a water-cooled intercooler that cools intake air by exchanging heat with cooling water is known. In order to send cooling water to the intercooler, it is conceivable to additionally provide a second cooling circuit. In this case, as the configuration of the second cooling circuit, an inlet portion branched from the outlet side of the first water pump, a second radiator disposed downstream of the inlet portion, and a first radiator disposed downstream of the second radiator. One having an outlet portion joined to the inlet side of the water pump is conceivable.

  When such a configuration is adopted, it is effective to make the flow rate of the cooling water flowing through the second cooling circuit smaller than the flow rate of the cooling water flowing through the first cooling circuit. Because the retention time of the cooling water in the second radiator can be lengthened, the temperature of the cooling water discharged from the second radiator can be lowered below the temperature of the cooling water in the first cooling circuit, and the cooling performance of the water cooling intercooler can be improved. It is. Moreover, it is because a cooler cooling water can be made to merge with a 1st cooling circuit, and can be made to flow into an engine internal flow path, and the engine cooling performance can also be improved. Thus, the second cooling circuit has an assist effect that assists the cooling performance of the first cooling circuit.

  However, when the above configuration is adopted, there are the following problems. That is, when the flow rate of the cooling water flowing through the second cooling circuit is increased, more low-temperature cooling water is joined to the first cooling circuit, and the cooling performance of the engine can be improved. However, on the other hand, the residence time of the cooling water in the second radiator is shortened, the cooling performance of the intercooler is lowered, and the intake air temperature rises. That is, the cooling performance of the engine and the intake air temperature are in a trade-off relationship with the flow rate of the cooling water flowing through the second cooling circuit.

  Accordingly, the present invention has been made in view of such circumstances, and an object thereof is to provide an engine cooling system capable of improving the cooling performance of the engine and simultaneously reducing the intake air temperature.

According to one aspect of the invention,
A first cooling circuit comprising: a first water pump; an engine internal passage disposed downstream of the first water pump; and a first radiator disposed downstream of the engine internal passage. A first cooling circuit configured to sequentially send cooling water from one water pump to the flow path in the engine and the first radiator, and then return to the first water pump;
An inlet portion branched from the outlet side of the first water pump, a second radiator disposed downstream of the inlet portion, and a downstream portion of the second radiator and joined to the inlet side of the first water pump A second cooling circuit having an outlet portion to be
A third cooling circuit independent of the first and second cooling circuits, comprising a third water pump, and a water-cooled intercooler and a third radiator disposed downstream of the third water pump; A third cooling circuit configured to send cooling water from the third water pump to the intercooler and the third radiator and then return to the third water pump;
An engine cooling system is provided.

  Preferably, the flow rate of the cooling water flowing through the third cooling circuit is made smaller than the flow rate of the cooling water flowing through the second cooling circuit.

  Preferably, the second radiator and the third radiator are integrated.

  According to the present invention, an excellent effect of improving the cooling performance of the engine and simultaneously reducing the intake air temperature is exhibited.

It is a schematic block diagram which shows the cooling system of the engine which concerns on a comparative example. It is a graph which shows the relationship of trade-off. It is a schematic structure figure showing an engine cooling system concerning an embodiment of the present invention. It is a schematic block diagram which shows an integrated radiator.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  First, for convenience, before describing the embodiments of the present invention, comparative examples assumed before the idea of the present invention will be described.

  FIG. 1 is a schematic configuration diagram illustrating an engine cooling system according to a comparative example. Such a cooling system is applied to an engine mounted on a vehicle.

  As shown in the figure, the cooling system 1 includes a first cooling circuit X and a second cooling circuit Y through which engine coolant is circulated or circulated. The first cooling circuit X is a circuit mainly for cooling the engine 2, and the second cooling circuit Y mainly sends cooling water to the water-cooled intercooler 3, and intake air that passes through the intercooler 3. This is a circuit for performing cooling. The intercooler 3 transmits the heat of the intake air I introduced from the intake air inlet 3A to the cooling water, and discharges the intake air I whose temperature has been lowered through the intake air outlet 3B. The engine 2 has a turbocharger (not shown), and is cooled when intake air whose temperature has risen due to supercharging of the turbocharger passes through the intercooler 3.

  The first cooling circuit X is disposed on the first water pump (W / P) 4, the engine internal flow path 5 disposed on the downstream side of the first water pump 4, and the downstream side of the engine internal flow path 5. A first radiator 6 as a high-temperature radiator (HT RAD), and the cooling water is sequentially sent from the first water pump 4 to the engine internal flow path 5 and the first radiator 6 and then returned to the first water pump 4. It is configured.

  Specifically, the first water pump 4 is installed in the engine 2 and driven by a crankshaft, and is disposed at the upstream end of a loop-shaped engine internal flow path 5 formed inside the engine. And at the time of a drive, a cooling water is discharged to the flow path 5 in an engine. A thermostat (T / S) 7 is provided on the downstream side of the engine internal flow path 5, and when the valve is opened, cooling water that has become hot after engine cooling is sent to the first radiator 6. The thermostat 7 is connected to the inlet of the first radiator 6 via the inlet pipe 8. The outlet of the first radiator 6 is connected to the inlet of the first water pump 4 via the outlet pipe 9. The flow direction of the cooling water A flowing through the first cooling circuit X is indicated by an arrow in the figure.

  The second cooling circuit Y includes an inlet portion 11 branched from the outlet side of the first water pump 4, a second radiator 12 serving as a low-temperature radiator (LT RAD) disposed on the downstream side of the inlet portion 11, and a second The above-described intercooler 3 disposed on the downstream side of the radiator 12 and the outlet portion 13 disposed on the downstream side of the intercooler 3 and joined to the inlet side of the first water pump 4 are provided. A branch point of the inlet portion 11 is indicated by P1, and a junction point of the outlet portion 13 is indicated by P2. The flow direction of the cooling water B flowing through the second cooling circuit Y is indicated by an arrow in the figure.

  The “outlet side of the first water pump 4” is the position of the flow path at or near the outlet of the first water pump 4, and before the cooling water receives heat from the engine 2 and substantially increases its temperature. The flow path position. Therefore, it includes the upstream side or upstream end of the engine internal flow path 5 as shown. Further, when the first water pump 4 and the engine internal flow path 5 are connected not directly but via a pipe, such a flow path in the pipe is also included in the “exit side of the first water pump 4”. Further, “the inlet side of the first water pump 4” refers to the flow path position at the inlet of the first water pump 4 or the upstream side of the first water pump 4 and downstream of the outlet of the first radiator 6. Therefore, it includes the flow path in the outlet pipe 9 described above.

  The inlet of the second radiator 12 is connected via an inlet pipe 14 to the upstream end of the engine internal flow path 5, particularly to the branch point P1. Therefore, the upstream end portion of the inlet pipe 14 forms the aforementioned inlet portion 11. The outlet of the second radiator 12 is connected to the cooling water inlet of the intercooler 3 via the outlet pipe 15. The cooling water outlet of the intercooler 3 is connected to the outlet pipe 9, particularly its junction P <b> 2 via the pipe 16. Therefore, the downstream end portion of the pipe 16 forms the outlet portion 13 described above.

  In the configuration of this comparative example, when the first water pump 4 is driven when the thermostat 7 is opened, the coolant flows from the first water pump 4 to the engine internal flow path 5, the thermostat 7, the inlet pipe 8, and the first radiator. 6, flows in the outlet pipe 9 in order, and returns to the first water pump 4. That is, the cooling water is circulated in the first cooling circuit X. In this process, the cooling water that has received heat from the engine 2 in the engine internal flow path 5 and becomes high temperature is cooled by exchanging heat with outside air when passing through the first radiator 6.

  On the other hand, the cooling water branched from the engine internal flow path 5 to the inlet pipe 14 at the branch point P1 flows in order through the inlet pipe 14, the second radiator 12, the intercooler 3, and the pipe 16 to the outlet pipe 9 at the junction P2. Merged. In this process, the cooling water is cooled by exchanging heat with the outside air when passing through the second radiator 12, and the cooled cooling water exchanges heat with the intake air in the intercooler 3 to cool the intake air.

  Here, the second cooling circuit Y is configured such that the flow rate of the cooling water B flowing through the second cooling circuit Y is smaller than the flow rate of the cooling water A flowing through the first cooling circuit X. In addition, the 1st cooling circuit X here is except the part (the 1st water pump 4 is in the middle) between the junction P2 and the branch point P1 in a cooling water flow direction among the 1st cooling circuits X. Say part.

  In this way, the residence time of the cooling water B of the second cooling circuit Y in the second radiator 12 becomes longer, and the temperature of the cooling water discharged from the second radiator 12 is higher than the temperature of the cooling water A of the first cooling circuit X. Also decreases. Since the cooling water whose temperature has decreased is sent to the intercooler 3, the cooling performance of the intercooler 3 can be improved, and the temperature of the intake air discharged from the intercooler 3 can be reduced. This is advantageous for improving the charging efficiency of intake air.

  In addition, although the temperature rises slightly in the intercooler 3, the cooling water whose temperature has been reduced in this way is merged with the first cooling circuit X, so the temperature of the cooling water A flowing through the first cooling circuit X is also lowered. . Specifically, on the inlet side of the first water pump 4, the cooling water B of the second cooling circuit Y whose temperature has decreased is merged with the first cooling circuit X, and the temperature of the cooling water A of the first cooling circuit X decreases. Is done. The cooling performance of the engine can be improved by the first water pump 4 supplying the cooling water A whose temperature has decreased to the in-engine flow path 5. As described above, the second cooling circuit Y has an assist effect for assisting the cooling performance of the first cooling circuit X to the first radiator 6. In addition, by using such a second cooling circuit Y, the temperature of the cooling water flowing out from the engine internal flow path 5 (referred to as the engine outlet temperature) and the cooling water flowing into the first radiator 6 are compared with the case where this is not used. The temperature (referred to as the first radiator inlet temperature) also decreases. In general, the temperature of the cooling water B of the second cooling circuit Y is lower than the temperature of the cooling water A of the first cooling circuit X.

  However, this comparative example has the following problems. That is, when the flow rate of the cooling water B flowing through the second cooling circuit Y is increased, more low-temperature cooling water is joined to the first cooling circuit X, and the cooling performance of the engine can be improved. However, on the other hand, the residence time of the cooling water B in the 2nd radiator 12 becomes short, and the temperature of the cooling water B discharged | emitted from the 2nd radiator 12 rises. As a result, the cooling performance of the intercooler 3 decreases, and the intake air temperature increases. That is, the cooling performance of the engine and the intake air temperature have a trade-off relationship with the flow rate of the cooling water B flowing through the second cooling circuit Y.

  This trade-off relationship is shown in FIG. The horizontal axis of the graph is the flow rate QB of the cooling water B flowing through the second cooling circuit Y, and the vertical axis is the temperature. In the figure, a line a indicates the first radiator inlet temperature TH, and a line b indicates the intake air temperature Ta. It is assumed that the flow rate of the cooling water A in the first cooling circuit X is constant. As shown in the figure, as the flow rate QB of the second cooling circuit Y increases, the first radiator inlet temperature TH tends to decrease, but the intake air temperature Ta tends to increase. From the viewpoint of engine cooling performance, a high flow rate QB2 is preferable, but from the viewpoint of intake air temperature, it is preferable to set a low flow rate QB1. Thus, the requirements of both are incompatible, and the configuration of the comparative example is not necessarily preferable if both are desired to be compatible.

  In order to solve this problem, the present inventor has come up with the present invention. Embodiments of the present invention will be described below.

  FIG. 3 is a schematic configuration diagram showing an engine cooling system according to an embodiment of the present invention. Such a cooling system is based on a comparative cooling system. In the following description, the same parts as those in the comparative example are denoted by the same reference numerals in the drawing, and the description thereof will be omitted. The description will focus on differences from the comparative example.

  The cooling system 1 according to the present embodiment also includes a first cooling circuit X and a second cooling circuit Y. However, the configuration of the second cooling circuit Y is different, the intercooler 3 and the pipe 16 are not provided, and the outlet pipe 15 is connected to the outlet pipe 9 of the first cooling circuit X, particularly the junction P2. Therefore, the downstream end portion of the outlet pipe 15 forms the outlet portion 13 of the second cooling circuit Y.

  On the other hand, the cooling system 1 according to the present embodiment includes a third cooling circuit Z that is independent of the first cooling circuit X and the second cooling circuit Y. The third cooling circuit Z includes a third water pump 21, the above-described water-cooled intercooler 3 disposed on the downstream side of the third water pump 21, and a low-temperature radiator (LT RAD) disposed on the downstream side of the intercooler 3. ) As a third radiator 22, and the cooling water is sequentially sent from the third water pump 21 to the intercooler 3 and the third radiator 22, and then returned to the third water pump 21. The flow direction of the cooling water C flowing through the third cooling circuit Z is indicated by arrows in the figure. In addition, since there is no water pump in the 2nd cooling circuit Y, what is called a 2nd water pump does not exist for convenience.

  In the present embodiment, the third water pump 21 is an electric water pump having a variable discharge flow rate regardless of the engine speed. The outlet of the third water pump 21 is connected to the cooling water inlet of the intercooler 3 via the pipe 23, and the cooling water outlet of the intercooler 3 is connected to the inlet of the third radiator 22 via the pipe 24. The outlet of the radiator 22 is connected to the inlet of the third water pump 21 via a pipe 25.

  When the third water pump 21 is driven, the cooling water C passes through the pipe 23, the intercooler 3, the pipe 24, the third radiator 22, and the pipe 25 in this order from the third water pump 21 and returns to the third water pump 21. It is. The point that the cooling water C exchanges heat with the intake air when passing through the intercooler 3 to cool the intake air, and the point that the cooling water C is cooled by exchanging heat with outside air when passing through the third radiator 22 is the same as described above. It is.

  In the present embodiment, since the third cooling circuit Z is independent of the first and second cooling circuits X and Y, the flow rate of the third cooling circuit Z is set to the flow rate of the first and second cooling circuits X and Y. Can be set independently. The flow rate of the third cooling circuit Z can be arbitrarily controlled by controlling the driving amount of the third water pump 21 by an electronic control unit (ECU) 100 constituting a control unit or a control unit.

  In the present embodiment, the second radiator 12 and the third radiator 22 are integrated. Thereby, the whole system can be made compact. FIG. 4 shows an example of such an integrated radiator 30. In the present embodiment, the radiator 30 is a so-called cross-flow type in which cooling water flows in the horizontal direction, but may be a so-called down-flow type in which cooling water flows from top to bottom.

  The radiator 30 includes left and right headers 31 and 32 and a radiator core 33 that connects them. As is well known, the radiator core 33 has a plurality of tubes connected to the left and right headers 31 and 32 and cooling fins attached to the tubes. The left and right headers 31 and 32 are divided into upper and lower portions by partition walls 34 and 35. Accordingly, the upper portion of the radiator 30 substantially forms the second radiator 12, and the lower portion of the radiator 30 forms the third radiator 22. An inlet 36 is provided in one of the headers 31, 32 in the upper portion of the radiator 30, and an outlet 37 is provided in the other. Similarly, an inlet 38 is provided in one of the headers 31, 32 in the lower portion of the radiator 30, and an outlet 39 is provided in the other. In the present embodiment, the arrangement of the inlet and the outlet is reversed left and right in the upper part and the lower part, and the directions of the cooling water B flowing through the second radiator 12 and the cooling water C flowing through the third radiator 22 are opposite to each other. Has been. However, the arrangement of the inlet and outlet may be the same on the left and right, and the flow direction may be the same.

  In the present embodiment, the flow rate of the cooling water C flowing through the third cooling circuit Z is made smaller than the flow rate of the cooling water B flowing through the second cooling circuit Y. Specifically, the third water pump 21 is controlled to obtain such a flow rate of the cooling water C. Then, the aforementioned trade-off problem can be solved.

  That is, referring to FIG. 2, the flow rate of the cooling water B flowing through the second cooling circuit Y is, for example, a relatively large QB2 in order to improve the engine cooling performance. In the comparative example, the intake air temperature Ta is increased at the flow rate QB2, but in the present embodiment, since the intercooler 3 is not included in the second cooling circuit Y, it is not necessary to increase the intake air temperature Ta. Only the assist effect of the first cooling circuit X is obtained by the second cooling circuit Y. On the other hand, the flow rate of the cooling water C flowing through the third cooling circuit Z is, for example, a value equal to a relatively small QB1. Thereby, the residence time of the cooling water C in the 3rd radiator 22 can be lengthened, and intake temperature Ta can be reduced. In general, the temperature of the cooling water C in the third cooling circuit Z is lowered from the temperature of the cooling water B in the second cooling circuit Y. Thus, according to the present embodiment, it is possible to improve the cooling performance of the engine and simultaneously reduce the intake air temperature.

  In the present embodiment, since the first water pump 4 is driven by the engine, the flow rates of the first cooling circuit X and the second cooling circuit Y increase / decrease according to the operating state of the engine. The flow rate of the 1st cooling circuit X and the 2nd cooling circuit Y increases, so that it increases. In the present embodiment, the ECU 100 can increase / decrease the driving amount of the third water pump 21 and the flow rate of the third cooling circuit Z in accordance with the increase / decrease of the flow rate.

  Although the embodiments of the present invention have been described in detail above, various other embodiments of the present invention are conceivable. For example, the present invention can be applied to cooling systems other than those for vehicles. The first water pump 4 may be electric. The third water pump 21 is not limited to an electric type, and may be a mechanical type driven by the engine 2. In the third cooling circuit Z, the arrangement of the intercooler 3 and the third radiator 22 may be reversed, and the intercooler 3 may be arranged on the downstream side of the third radiator 22 with the third water pump 21 as a starting point.

  The embodiment of the present invention is not limited to the above-described embodiment, and includes all modifications, applications, and equivalents included in the concept of the present invention defined by the claims. Therefore, the present invention should not be construed as being limited, and can be applied to any other technique belonging to the scope of the idea of the present invention.

DESCRIPTION OF SYMBOLS 1 Cooling system 3 Water-cooled intercooler 4 1st water pump 5 Engine flow path 6 1st radiator 11 Inlet part 12 2nd radiator 13 Outlet part 21 3rd water pump 22 3rd radiator 30 Integrated radiator X 1st cooling circuit Y second cooling circuit Z third cooling circuit

Claims (2)

A first cooling circuit having a first water pump driven by a crankshaft, an engine internal passage disposed downstream of the first water pump, and a first radiator disposed downstream of the engine internal passage. A first cooling circuit configured to sequentially send cooling water from the first water pump to the flow path in the engine and the first radiator, and then return to the first water pump;
An inlet portion branched from the first cooling circuit at a branch point located on the outlet side of the first water pump and on the upstream side from the upstream end portion of the flow path in the engine , disposed on the downstream side of the inlet portion A second cooling circuit, and a second cooling circuit having an outlet portion arranged downstream of the second radiator and joined to an inlet side of the first water pump;
A third cooling circuit independent of the first and second cooling circuits, comprising: an electric third water pump; and a water-cooled intercooler and a third radiator disposed downstream of the third water pump. A third cooling circuit configured to send cooling water from the third water pump to the intercooler and the third radiator and then return to the third water pump;
A control unit for controlling the third water pump;
Equipped with a,
The control unit is
In accordance with the increase or decrease of the flow rate of the first cooling circuit and the second cooling circuit according to the increase or decrease of the engine speed, the driving amount of the third water pump is increased or decreased,
The engine cooling system , wherein the third water pump is controlled so that a flow rate of the cooling water flowing through the third cooling circuit is smaller than a flow rate of the cooling water flowing through the second cooling circuit . The engine cooling system according to claim 1 , wherein the second radiator and the third radiator are integrated.

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