JP2016050545A - Cooling system for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling system for a vehicle, which can make a refrigerant circulate in a low-temperature circuit by a refrigerant pump which makes a refrigerant of a main circuit circulate.SOLUTION: In a main circuit 2, cooling water for cooling an engine 7 can be made to flow in a circulated manner, and a water pump 3 makes the cooling water of the main circuit 2 circulate. A high-temperature heat exchanger 4 is arranged at the main circuit 2 on an upstream side of the water pump 3, and cools the cooling water whose temperature is raised by the engine 7. A low-temperature circuit 5 makes the cooling water which is branched from the main circuit 2 at a downstream side of the water pump 3 and flows in from the main circuit 2 circulate to an intercooler 15 and an EGR cooler 16 for cooling intake air of the engine 7, and after that, makes the cooling water be joined to the main circuit 2 at the upstream side of the water pump 3. A low-temperature heat exchanger 6 is arranged at the low-temperature circuit 5 at an upstream side of the intercooler 15 and the EGR cooler 16, and cools the cooling water which flows in from the main circuit 1.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a vehicle cooling system.

  Patent Document 1 describes a circuit device including a low-temperature circuit for cooling intake air and an engine cooling circuit (main circuit) for cooling an engine. The main circuit includes an engine, an engine thermostat, a refrigerant cooler, and a refrigerant pump, and a supply line is provided to the low-temperature circuit starting from the engine thermostat. The low temperature circuit includes a refrigerant pump, a mixing thermostat, a charge / refrigerant cooler, and a low temperature cooler. A reflux line is provided between the pipes downstream of the mixing thermostat of the low-temperature circuit, upstream of the low-temperature cooler of the low-temperature circuit, downstream of the refrigerant cooler of the engine cooling circuit, and upstream of the refrigerant pump of the engine cooling circuit. .

  During normal operation, the refrigerant in the low-temperature circuit is warmed relatively strongly during circulation through the air supply / refrigerant cooler, at which time the mixing thermostat is closed to the supply line, and the refrigerant enters the low-temperature circuit from the engine cooling circuit. There are two separate circuits that cannot be reached.

  When the engine is warming up, or when the charge air cooling is limited or another operating condition where the charge air must be warmed, the refrigerant enters the charge / refrigerator cooler at a relatively low temperature. In such a case, the mixing thermostat 11 is open to the supply line, and the refrigerant can flow from the engine cooling circuit to the low temperature circuit.

JP-T-2006-522893

  In the above configuration, since the main circuit and the low-temperature circuit are separated in the normal operation state and become two independent circuits, it is necessary to provide a refrigerant pump for circulating the refrigerant in both the main circuit and the low-temperature circuit. This leads to an increase in the size of the device. Further, when the two pumps are driven by the engine, it contributes to deterioration of fuel consumption due to engine drive loss.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a vehicle cooling system capable of circulating a refrigerant in a low-temperature circuit by a refrigerant pump that circulates a refrigerant in a main circuit.

  In order to achieve the above object, the cooling system according to the first aspect of the present invention includes a main circuit, a refrigerant pump, a high-temperature heat exchanger, a low-temperature circuit, and a low-temperature heat exchanger.

  The main circuit can circulate and circulate refrigerant for cooling the engine, and the refrigerant pump circulates refrigerant in the main circuit. The high temperature heat exchanger is provided in the main circuit upstream of the refrigerant pump, and cools the refrigerant whose temperature has been increased by the engine.

  The low-temperature circuit branches from the main circuit on the downstream side of the refrigerant pump, distributes the refrigerant flowing from the main circuit to the intake air cooler that cools the intake air of the engine, and then joins the main circuit on the upstream side of the refrigerant pump . The low-temperature heat exchanger is provided in a low-temperature circuit on the upstream side of the intake air cooler, and cools the refrigerant flowing from the main circuit.

  In the above configuration, the refrigerant whose temperature is increased by the engine flows into the main circuit, is cooled by the high-temperature heat exchanger, and is supplied to the engine again by the refrigerant pump. Further, a part of the refrigerant of the main circuit flowing out from the refrigerant pump flows into the low-temperature circuit, is cooled by the low-temperature heat exchanger, cools the intake air cooler, and then returns to the main circuit on the upstream side of the refrigerant pump.

  The downstream side of the refrigerant pump is the place where the refrigerant reaches the highest pressure state due to the discharge pressure (differential pressure) of the refrigerant pump, and the low-temperature circuit branches from the downstream side of this refrigerant pump, so that the high-pressure refrigerant flows into the cold / hot circuit. To do. Therefore, it is possible to circulate the refrigerant in the low-temperature circuit by the refrigerant pump that circulates the refrigerant in the main circuit without separately providing a refrigerant pump for circulating the refrigerant in the low-temperature circuit.

  Further, since the low-temperature circuit branches on the downstream side of the high-temperature heat exchanger, the refrigerant cooled by the high-temperature heat exchanger is further cooled by the low-temperature heat exchanger of the low-temperature circuit and flows through the intake air cooler. As described above, since the refrigerant cooled by the multistage cooling by the high-temperature heat exchanger and the low-temperature heat exchanger flows through the intake air cooler, it is possible to promote the decrease in the intake air temperature of the engine and improve the fuel consumption.

  In addition, the said structure does not prevent providing the auxiliary pump which assists the distribution | circulation of the refrigerant | coolant of a low-temperature circuit separately. In this case, the auxiliary pump does not need the ability to circulate the refrigerant alone, and only needs to have the ability to circulate the refrigerant by assisting the refrigerant pump. Therefore, a small and low-performance pump can be used.

  The second aspect of the present invention is the cooling system according to the first aspect, and includes low-temperature circuit flow rate changing means capable of increasing or decreasing the amount of refrigerant flowing from the main circuit to the low-temperature circuit.

  In the above configuration, the main circuit that circulates to the engine out of the refrigerant that has flowed out of the refrigerant pump so that both the cooling of the engine by the refrigerant of the main circuit and the cooling of the intake air by the refrigerant of the low-temperature circuit are suitably performed as a whole. The flow rate distribution between the refrigerant and the refrigerant flowing through the low-temperature circuit can be adjusted by the low-temperature circuit flow changing means. The refrigerant flow distribution by the low-temperature circuit flow rate changing means is determined by, for example, the refrigerant temperature of the main circuit, the intake temperature of the engine (gas temperature of the intake manifold of the engine), the outside air temperature, the engine load, and the like.

  A third aspect of the present invention is the cooling system according to the second aspect, comprising engine load detection means and control means.

  The engine load detection means detects the engine load. The control means controls the low temperature circuit flow rate changing means from the main circuit so that a refrigerant having a flow rate that effectively reduces the intake air temperature of the engine with respect to the engine load detected by the engine load detection means flows into the low temperature circuit. Adjust the amount of refrigerant flowing into the low-temperature circuit.

  If the refrigerant flow in the low-temperature circuit is reduced during normal operation when the refrigerant in the engine and main circuit is hot, the temperature of the refrigerant flowing out of the low-temperature heat exchanger decreases and the intake air temperature also decreases. Increases efficiency and contributes to improved fuel efficiency. On the other hand, since the flow rate of the refrigerant joining (returning) from the low-temperature circuit to the main circuit decreases, the temperature of the refrigerant in the main circuit rises, the temperature of the lubricating oil in the engine (oil temperature) also rises, and the friction is reduced. Contributes to improved fuel efficiency.

  In the above configuration, the amount of refrigerant flowing from the main circuit to the low-temperature circuit is adjusted so that the refrigerant having a flow rate that effectively reduces the intake air temperature of the engine with respect to the engine load flows into the low-temperature circuit. The fuel consumption can be improved by simultaneously reducing the intake air temperature by lowering the refrigerant temperature and reducing the friction by increasing the refrigerant temperature of the main circuit.

  According to a fourth aspect of the present invention, there is provided the cooling system according to the third aspect, comprising refrigerant temperature detecting means for detecting the temperature of the refrigerant flowing from the engine into the main circuit, wherein the main circuit is connected to the main bypass line and the control. And a valve.

  The main bypass line communicates the upstream side and the downstream side of the high temperature heat exchanger. The control valve has a high-temperature heat exchange enabled state in which refrigerant flowing from the engine flows to the high-temperature heat exchanger, and high-temperature heat exchange disabled to flow refrigerant flowing from the engine to the main bypass line without flowing to the high-temperature heat exchanger It can be set to the state.

  The control means sets the control valve in a high temperature heat exchange effective state when the temperature of the refrigerant detected by the refrigerant temperature detecting means is equal to or higher than a predetermined temperature and the engine load detected by the engine load detecting means is equal to or higher than the predetermined load. . Further, when the temperature of the refrigerant detected by the refrigerant temperature detecting means is lower than a predetermined temperature, or the temperature of the refrigerant detected by the refrigerant temperature detecting means is equal to or higher than the predetermined temperature and the engine load detected by the engine load detecting means is a predetermined load. If it is less, the control valve is set to a high temperature heat exchange invalid state.

  During warm-up operation when the refrigerant of the engine and the main circuit is at a low temperature, it is preferable to supply the refrigerant to the engine without cooling it with a high-temperature heat exchanger in order to increase the temperature of the engine early. In order to protect the engine, it is preferable to supply a refrigerant cooled by a high-temperature heat exchanger to the engine. However, if the refrigerant is uniformly cooled by the high-temperature heat exchanger during normal operation, there is a possibility that friction reduction due to the high temperature of the refrigerant in the main circuit may be limited. On the other hand, even during normal operation, if the engine load is low and the load is low, the demand for engine protection is low and priority can be given to the high temperature of the refrigerant in the main circuit. For this reason, in order to further improve fuel efficiency by reducing friction while protecting the engine appropriately, cooling of the refrigerant by the high-temperature heat exchanger during normal operation is executed in the high-load operation state and the low-load operation state. Then it is preferable not to execute.

  In the above configuration, when the temperature of the main circuit refrigerant (main circuit refrigerant temperature) is equal to or higher than the predetermined temperature and the engine load is equal to or higher than the predetermined load (high-temperature refrigerant and high-load operation state), the control valve is effective for high-temperature heat exchange. When the refrigerant flows through the high-temperature heat exchanger and the main circuit refrigerant temperature is lower than a predetermined temperature (refrigerant low temperature), or the main circuit refrigerant temperature is higher than the predetermined temperature and the engine load is lower than the predetermined load When it is (high refrigerant temperature and low load operation state), the control valve is set to the high temperature heat exchange invalid state, and the refrigerant does not flow through the high temperature heat exchanger. That is, during the warm-up operation at a low refrigerant temperature, the refrigerant does not flow through the high-temperature heat exchanger, and the engine temperature rises early. Further, during normal operation where the refrigerant is at a high temperature, the refrigerant flows through the high temperature heat exchanger in a high load operation state, and the refrigerant does not flow through the high temperature heat exchanger in a low load operation state. Therefore, the temperature of the engine can be raised early during the warm-up operation, and the engine can be appropriately protected and the fuel consumption can be improved during the normal operation.

  A fifth aspect of the present invention is the cooling system according to any one of the first to third aspects, wherein the main circuit includes a main bypass pipe and a main circuit thermostat, and the low-temperature circuit includes a low-temperature bypass pipe. And a low temperature circuit thermostat.

  The main bypass line communicates the upstream side and the downstream side of the high temperature heat exchanger. The main circuit thermostat causes the refrigerant flowing from the engine to flow to the high-temperature heat exchanger when the temperature of the refrigerant flowing from the engine is equal to or higher than the first predetermined temperature, and the temperature of the refrigerant flowing from the engine is the first predetermined temperature. When the temperature is lower than the temperature, the refrigerant flowing from the engine is circulated to the main bypass pipe without being circulated to the high-temperature heat exchanger.

  The low temperature bypass line communicates the upstream side and the downstream side of the low temperature heat exchanger. When the temperature of the refrigerant flowing from the main circuit is equal to or higher than the second predetermined temperature, the low-temperature circuit thermostat circulates the refrigerant flowing from the main circuit to the low-temperature heat exchanger, and the temperature of the refrigerant flowing from the main circuit is When the temperature is lower than the predetermined temperature of 2, the refrigerant flowing from the main circuit is circulated to the low temperature bypass pipe without being circulated to the low temperature heat exchanger.

  In the above configuration, when the temperature of the refrigerant in the main circuit is lower than the first predetermined temperature and the temperature of the refrigerant in the low-temperature circuit is lower than the second predetermined temperature, the refrigerant in the main circuit passes through the high-temperature heat exchanger. The refrigerant in the low-temperature circuit does not flow through the low-temperature heat exchanger. As described above, during the warm-up operation in which both the refrigerant in the main circuit and the low-temperature circuit are at a low temperature (below the first predetermined temperature and the second predetermined temperature), the refrigerant in both the main circuit and the low-temperature circuit is the heat exchanger. Since it is not cooled, the engine temperature can be raised quickly.

  A sixth aspect of the present invention is the cooling system according to any one of the first to fifth aspects, wherein the main circuit has a main branch pipe. The main branch pipe communicates the upstream side of the high-temperature heat exchanger and the upstream side of the refrigerant pump, and distributes the refrigerant that has branched and entered from the upstream side of the high-temperature heat exchanger to the intake air cooler.

  In the above configuration, the intake air cooler is multi-stage cooled by both the refrigerant in the main circuit (main branch line) and the refrigerant in the low-temperature circuit, so that the reduction in the intake air temperature of the engine can be further promoted to improve fuel efficiency. it can.

  A seventh aspect of the present invention is the cooling system according to any one of the first to sixth aspects, wherein the intake air cooler includes an intercooler and an EGR cooler arranged in series.

  In the above configuration, since the intercooler and the EGR cooler are arranged in series, the intercooler and the EGR cooler can be efficiently cooled even when the refrigerant flow rate in the low-temperature circuit is small, and the intake air temperature is reduced. The fuel consumption can be improved by lowering.

  According to the present invention, the refrigerant can be circulated through the low-temperature circuit by the refrigerant pump that circulates the refrigerant in the main circuit.

It is a lineblock diagram showing typically the cooling system concerning a 1st embodiment of the present invention. It is a block diagram which shows typically the cooling system which concerns on 2nd Embodiment of this invention. It is a block diagram which shows typically the cooling system which concerns on 3rd Embodiment of this invention. It is a figure which shows the relationship of the ratio of the water flow rate of the low temperature circuit with respect to the water flow rate of the main circuit, the engine intake air temperature, and the water temperature of the main circuit. It is a block diagram which shows typically the cooling system which concerns on 4th Embodiment of this invention. It is a block diagram which shows typically the cooling system which concerns on 4th Embodiment of this invention.

  A first embodiment of the present invention will be described below with reference to FIG. The upstream side and the downstream side mean the upstream side and the downstream side in the flow direction of the cooling water (refrigerant) unless otherwise specified.

  As shown in FIG. 1, a vehicle cooling system 1 includes a main circuit 2, a water pump (refrigerant pump) 3, a high-temperature heat exchanger (HT RAD) 4, a low-temperature circuit 5, and a low-temperature heat exchanger (LT RAD) 6. Is provided. The main circuit 2 is a conduit through which cooling water (refrigerant) for cooling the engine 7 can circulate and flow, and the refrigerant water pump 3 circulates the cooling water of the main circuit 2.

  The main circuit 2 is mainly composed of a main upstream line 8, a main downstream line 9, a main bypass line 10, and a main circuit thermostat 11. The main upstream line 8 communicates the outlet side of the cooling path in the engine 7 and the inlet side of the high temperature heat exchanger 5. The main downstream line 9 communicates the outlet side of the high temperature heat exchanger 5 and the inlet side of the cooling path in the engine 8. The main bypass line 10 is connected to the main upstream line 8 (upstream side of the high temperature heat exchanger 5) and the main downstream side line 9 (downstream side of the high temperature heat exchanger 5) via the high temperature heat exchanger 5. Communicate directly with each other.

  The main circuit thermostat 11 is, for example, a wax element type thermostat, and is provided at a branch portion between the main upstream line 8 and the main bypass line 10. When the temperature (water temperature) of the cooling water is equal to or higher than the predetermined temperature (first predetermined temperature) T1, the main circuit thermostat 11 circulates the cooling water to the high temperature heat exchanger 4 and the water temperature is lower than the predetermined temperature T1. Is a pipe on the downstream side of the main upstream pipe line 8 (on the high temperature heat exchanger 4 side) by its own thermal expansion so that the cooling water flows through the main bypass pipe line 10 without flowing through the high temperature heat exchanger 4. Close the road. Cooling water flowing through the main bypass pipe 10 flows into the main downstream pipe 9 from the junction 12 on the downstream side of the high-temperature heat exchanger 4. The main circuit thermostat 11 is connected to the upstream side of the main upstream pipe line 8 and the junction part 12 (on the high temperature heat exchanger 4 side) on the downstream side (on the high temperature heat exchanger 4 side) of the branch portion of the main bypass pipe line 10. ) May be provided in the main downstream pipe line 9.

  The water pump 3 is provided in the main downstream pipe line 9 on the downstream side of the merging portion 12 and circulates the cooling water of the main circuit 2 by flowing the cooling water toward the engine 7.

  The high-temperature heat exchanger 4 is, for example, a radiator, and is disposed on the upstream side of the water pump 3. The high-temperature heat exchanger 4 cools the cooling water that is heated by the engine 7 and flows into the main upstream pipe line 8.

  During normal operation in which the main circuit water temperature is equal to or higher than the predetermined temperature T1, the main circuit thermostat 11 is opened, and the cooling water flowing from the engine 7 into the main circuit 2 is cooled by the high temperature heat exchanger 4 and supplied to the engine 7. Therefore, the engine 7 can be suitably cooled. On the other hand, during the warm-up operation in which the main circuit water temperature is lower than the predetermined temperature T1, such as when the engine 7 is started in an environment where the outside air temperature is low, the main circuit thermostat 11 is closed and the engine 7 Since the cooling water that has flowed into 2 is supplied to the engine 7 without flowing through the high-temperature heat exchanger 4, the temperature of the engine 7 can be raised at an early stage.

  The low-temperature circuit 5 circulates the cooling water flowing in from the main circuit 2 on the downstream side of the water pump 3 to an intake air cooler (intercooler 15 and EGR cooler 16 described later) that cools the intake air of the engine 7. Thereafter, the pipe is joined to the main circuit 2 on the upstream side of the water pump 3, and mainly includes a low temperature upstream pipe 13 and a low temperature downstream pipe 14. The low temperature upstream line 13 communicates the branch portion 17 of the main downstream line 9 downstream of the water pump 3 (between the water pump 3 and the engine 7) and the inlet side of the low temperature heat exchanger 6. The low temperature downstream pipe line 14 communicates the outlet side of the low temperature heat exchanger 6 and the junction 12 of the main downstream pipe line 9. The intermediate portion of the low temperature downstream pipe 14 branches into two paths (low temperature branch pipes 14a and 14b) and joins. The cooling water that has flowed into one of the low-temperature branch pipes 14a flows through the cooling path in the intercooler 15, and the cooling water that has flowed into the other low-temperature branch pipe 14b flows through the cooling path in the EGR cooler. That is, the intercooler 15 and the EGR cooler 16 are arranged in parallel to the low temperature downstream pipe line 14.

  The low-temperature heat exchanger 6 is, for example, a radiator, and is disposed on the upstream side of the intercooler 15 and the EGR cooler 16, and cools the cooling water flowing into the low-temperature circuit 5 from the branch portion 17.

  The intercooler 15 is provided in the flow path of the intake air pressurized (compressed) by the turbo device, and cools the intake air flowing toward the engine 7 with the cooling water of the low-temperature circuit 5. The EGR cooler 16 is provided in a flow path of EGR gas recirculated to the intake air by the EGR device, and cools the EGR gas flowing toward the engine 7 with cooling water of the low-temperature circuit 5.

  According to this embodiment, the cooling water heated by the engine 7 in the normal operation state flows into the main circuit 2, is cooled by the high-temperature heat exchanger 4, and is again supplied to the engine 7 by the water pump 3. Further, a part of the cooling water of the main circuit 2 flowing out from the water pump 3 flows into the low-temperature circuit 5 from the branch portion 17 and is cooled by the low-temperature heat exchanger 6 to cool the intercooler 15 and the EGR cooler 16. Return to the main circuit 2 at the junction 12 on the upstream side of the water pump 3.

  The downstream side of the water pump 3 is a place where the coolant becomes the highest pressure state due to the discharge pressure (differential pressure) of the water pump 3, and the low-temperature circuit 5 branches from the branch portion 17 on the downstream side of the water pump 3. High-pressure cooling water flows into the cooling / heating circuit 5. Therefore, the cooling water can be circulated to the low temperature circuit 5 by the water pump 3 that circulates the cooling water of the main circuit 2 without separately providing a water pump for circulating the cooling water of the low temperature circuit 5.

  Further, since the low-temperature circuit 5 branches from the branch portion 17 on the downstream side of the high-temperature heat exchanger 4, the cooling water cooled by the high-temperature heat exchanger 4 is further cooled by the low-temperature heat exchanger 6 of the low-temperature circuit 5. The cooler 15 and the EGR cooler 16 are distributed. Thus, since the cooling water cooled by the multistage cooling by the high-temperature heat exchanger 4 and the low-temperature heat exchanger 6 flows through the intercooler 15 and the EGR cooler 16, the reduction of the intake temperature of the engine 7 is promoted. Fuel consumption can be improved.

  Next, a second embodiment of the present invention will be described with reference to FIG. In addition, about the structure similar to 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  As shown in FIG. 2, in the cooling system 18 of this embodiment, the intercooler 15 and the EGR cooler 16 are arranged in series. The intercooler 15 is arranged on the upstream side of the EGR cooler 16, and the cooling water flowing into the R 14 between the low temperature heat exchanger 6 and the low temperature downstream side R flows through the cooling path in the intercooler 15, and then in the EGR cooler. It flows through the cooling path and returns from the junction 12 to the main circuit 2.

  According to this embodiment, since the intercooler 15 and the EGR cooler 16 are arranged in series, the intercooler 15 and the EGR cooler can be used even when the flow rate (water flow rate) of the cooling water in the low-temperature circuit is small. 16 can be efficiently cooled, and the fuel consumption can be improved by lowering the intake air temperature.

  Further, since the temperature of the EGR gas (about 600 ° C.) cooled by the EGR cooler 16 is higher than the temperature of intake air (fresh air such as outside air) (200 ° C. or less) cooled by the intercooler 15, the intercooler 15 Is cooled after the EGR cooler 16, the temperature of the cooling water flowing out from the EGR cooler 16 suddenly rises, and there is a possibility that the intercooler 15 is not effectively cooled. 15 is disposed upstream of the EGR cooler 16 and the intercooler 15 is cooled before the EGR cooler 16, so that both the intercooler 15 and the EGR cooler 16 can be reliably cooled.

  Next, a third embodiment of the present invention will be described with reference to FIG. In addition, about the structure similar to the above-mentioned embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  As shown in FIG. 3, in addition to the cooling system 18 of the second embodiment, the cooling system 19 of the present embodiment includes a low-temperature circuit flow control valve (low-temperature circuit flow changing means) 20 and an engine load detector (engine load detection). Means) 21, ECU (Electric Control Unit) 22, and water temperature sensor (refrigerant temperature detection means) 23. In addition, a high temperature heat exchange switching valve (control valve) 24 is provided at a branch portion between the main upstream pipe line 8 and the bypass pipe line 10 in place of the main circuit thermostat 11 (see FIGS. 1 and 2).

  The engine load detection unit 21 is configured by, for example, an accelerator opening sensor, and sequentially detects the load (engine load) of the engine 7 and outputs the detected engine load to the ECU 22.

  The water temperature sensor 23 is provided in the main upstream pipe 8, sequentially detects the temperature (water temperature) of the cooling water flowing into the main circuit 2 from the engine 7, and outputs the detected water temperature to the ECU 22.

  The high-temperature heat exchange switching valve 24 is provided at a branch portion between the main upstream pipeline 8 and the main bypass pipeline 10, and opens the pipeline on the downstream side (high-temperature heat exchanger 4 side) of the main upstream pipeline 8. The high-temperature heat exchange effective state to be switched and the high-temperature heat exchange invalid state to be closed are switched. In the high temperature heat exchange effective state, the cooling water flowing from the engine 7 flows to the high temperature heat exchanger 4. In the high temperature heat exchange invalid state, the cooling water flowing from the engine 7 flows to the main bypass pipe 10 without flowing to the high temperature heat exchanger 4.

  The low-temperature circuit flow control valve 20 is provided at the branch portion 17 of the main downstream pipe 9 and opens and closes the pipe on the low-temperature circuit 5 side, thereby reducing the amount of cooling water flowing from the main circuit 2 to the low-temperature circuit 5. Increase or decrease.

  The ECU 22 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory), and functions as a control unit when the CPU reads and executes a cooling control program stored in the ROM. . Low-temperature circuit flow rate setting information described later is stored in advance in the ROM or RAM (storage unit). The ECU 22 detects the engine load detection unit 21 so that cooling water having a flow rate that effectively reduces the intake air temperature of the engine 7 with respect to the load of the engine 7 detected by the engine load detection unit 21 flows into the low-temperature circuit 5. Based on the engine load, the low-temperature circuit flow control valve 20 is controlled to adjust the inflow amount of the cooling water from the main circuit 2 to the low-temperature circuit 5. In addition, the ECU 22 performs high-temperature heat exchange switching valve 24 based on the engine load detected by the engine load detection unit 21 and the water temperature detected by the water temperature sensor 23 so that the protection of the engine 7 and the improvement of fuel efficiency are suitably performed. Switch the state.

  Next, the control of the low-temperature circuit flow control valve 20 executed by the ECU 22 will be described.

  FIG. 4 shows a low temperature with respect to the flow rate of the cooling water of the main circuit 2 (water flow rate of the main circuit 2) while maintaining the engine load at a constant load during normal operation when the cooling water of the engine 7 and the main circuit 2 becomes high temperature. It is a figure which shows the intake-air temperature of the engine 7 at the time of changing the ratio (branch ratio) of the flow volume of the cooling water of the circuit 5 (water flow volume of the low-temperature circuit 5), and the temperature (water temperature) of the cooling water of the main circuit 2. . In FIG. 4, the water temperature of the main circuit 2 is indicated by a solid line, and the intake air temperature of the engine 7 is indicated by a two-dot chain line.

  As shown in FIG. 4, when the low-temperature circuit flow control valve 20 is throttled from the fully opened state and the branching ratio (water flow rate of the low-temperature circuit 5) is decreased, the temperature of the cooling water flowing out from the low-temperature heat exchanger 6 is decreased. The intake air temperature also decreases. The intake air temperature decreases as the branching ratio decreases, reaches a minimum temperature at a predetermined branching ratio (minimum intake air temperature branching ratio) Rt, and then reverses and rises. Further, when the branching ratio is decreased, the flow rate of the cooling water that joins (returns) from the low-temperature circuit 5 to the main circuit 2 decreases, so that the water temperature of the main circuit 2 rises. When the intake air temperature decreases, the intake air charging efficiency of the engine 7 increases, and the fuel efficiency improves. Further, when the water temperature of the main circuit 2 rises (cooling water becomes high temperature), the temperature of the lubricating oil (oil temperature) in the engine 7 rises and friction is reduced, so that fuel efficiency is improved.

  Since the minimum intake air temperature branching ratio Rt varies depending on the engine load, a low temperature circuit that obtains the minimum intake air temperature branching ratio Rt for each engine load by experiment, simulation, etc. and flows the water amount of the determined minimum intake air temperature branching ratio Rt into the low temperature circuit 5 The opening degree of the flow control valve 20 is obtained as a target opening degree, and the correspondence between the engine load and the target opening degree is stored in advance in the storage unit as low-temperature circuit flow setting information. The low-temperature circuit flow rate setting information may be a table, a map, or the like, or an arithmetic expression.

  The ECU 22 determines the target opening using the engine load detected by the engine load detector 21 and the low-temperature circuit flow rate setting information, and sets the low-temperature circuit flow control valve 20 to the determined target opening. As a result, cooling water having a flow rate that effectively reduces the intake air temperature of the engine 7 with respect to the load of the engine 7 detected by the engine load detection unit 21 flows into the low-temperature circuit 5.

  Next, control of the high temperature heat exchange switching valve 24 executed by the ECU 22 will be described.

  During warm-up operation in which the cooling water of the engine 7 and the main circuit 2 is at a low temperature, the cooling water is supplied to the engine 7 without being cooled by the high temperature heat exchanger 4 in order to increase the temperature of the engine 7 early. Preferably, during normal operation in which the cooling water of the engine 7 and the main circuit 2 is at a high temperature, it is preferable to supply the engine 7 with the cooling water that has been cooled by the high-temperature heat exchanger in order to protect the engine 7. However, when cooling water is uniformly cooled by the high-temperature heat exchanger 4 during normal operation, there is a possibility that friction reduction due to the high temperature of the cooling water in the main circuit 2 may be limited. On the other hand, even during normal operation, if the load on the engine 7 is low and the load is low, the requirement for protection of the engine 7 is low, and it is possible to prioritize the high temperature of the cooling water in the main circuit 2. . Therefore, in order to further improve the fuel efficiency by reducing the friction while appropriately protecting the engine 7, cooling of the cooling water by the high temperature heat exchanger 4 during normal operation is executed in a high load operation state, and the low load It is preferable not to execute in the operating state.

  For this reason, when the water temperature detected by the water temperature sensor 23 is equal to or higher than the predetermined temperature T0 and the engine load detected by the engine load detection unit 21 is equal to or higher than the predetermined load L0, the ECU 22 switches the high temperature heat exchange switching valve 24 to the high temperature heat exchange. Set to enabled state. Further, when the water temperature detected by the water temperature sensor 23 is lower than the predetermined temperature T0, or the water temperature detected by the water temperature sensor 23 is equal to or higher than the predetermined temperature T0, and the engine load detected by the engine load detection unit 21 is lower than the predetermined load L0. If so, the high temperature heat exchange switching valve 24 is set to a high temperature heat exchange invalid state.

  According to this embodiment, the inflow amount of the cooling water from the main circuit 2 to the low temperature circuit 5 so that the cooling water having a flow rate that effectively reduces the intake air temperature of the engine 7 with respect to the engine load flows into the low temperature circuit 5. Therefore, the lowering of the intake air temperature due to the lowering of the cooling water in the low-temperature circuit 5 and the reduction of the friction due to the higher temperature of the cooling water in the main circuit 2 can both be achieved, and fuel efficiency can be improved.

  When the temperature of the cooling water in the main circuit 2 (main circuit water temperature) is equal to or higher than the predetermined temperature T0 and the engine load is equal to or higher than the predetermined load L0 (high water temperature and high load operation state), the high temperature heat exchange switching valve 24 is When the high-temperature heat exchange is set to the effective state and the cooling water flows through the high-temperature heat exchanger 4 and the main circuit water temperature is lower than the predetermined temperature T0 (low water temperature), or the main circuit water temperature is equal to or higher than the predetermined temperature T0 and the engine When the load is less than the predetermined load L0 (high water temperature and low load operation state), the high temperature heat exchange switching valve 24 is set to the high temperature heat exchange invalid state, and the cooling water does not flow through the high temperature heat exchanger 4. That is, during the warm-up operation at a low water temperature, the cooling water does not flow through the high-temperature heat exchanger 4 and the temperature of the engine 7 rises early. Further, during normal operation at a high water temperature, the cooling water flows through the high temperature heat exchanger 4 in a high load operation state, and the cooling water does not flow through the high temperature heat exchanger 4 in a low load operation state. Therefore, the temperature of the engine can be raised early during the warm-up operation, and the engine can be appropriately protected and the fuel consumption can be improved during the normal operation.

  Next, a fourth embodiment of the present invention will be described with reference to FIG. In addition, about the structure similar to the above-mentioned embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  As shown in FIG. 5, in the cooling system 25 of the present embodiment, a low temperature bypass pipe 26 and a low temperature circuit thermostat 27 are provided in the low temperature circuit 5 in addition to the cooling system 19 of the third embodiment.

  The low temperature bypass line 26 includes a low temperature upstream line 13 (upstream side of the low temperature heat exchanger 6) and a low temperature downstream line 14 (downstream side of the low temperature heat exchanger 6 and upstream side of the intercooler 15). Are communicated directly without going through the low-temperature heat exchanger 6.

  The low temperature circuit thermostat 27 is, for example, a wax element type thermostat, and is provided at a branch portion between the low temperature upstream line 13 and the low temperature bypass line 26. When the temperature of the cooling water (water temperature) is equal to or higher than the predetermined temperature (second predetermined temperature) T2, the low-temperature circuit thermostat 27 distributes the cooling water to the low-temperature heat exchanger 6 and the water temperature is lower than the predetermined temperature T2. Is a pipe on the downstream side (low temperature heat exchanger 6 side) of the low temperature upstream pipe line 13 by its own thermal expansion so that the cooling water is allowed to flow to the low temperature bypass line 26 without flowing to the low temperature heat exchanger 6. Close the road. Cooling water flowing through the low temperature bypass pipe 26 flows into the low temperature downstream pipe 14 from the junction 28 on the downstream side of the low temperature heat exchanger 6. The low-temperature circuit thermostat 27 is connected to the low-temperature upstream pipeline 13 and the junction 28 on the downstream side (low-temperature heat exchanger 6 side) of the branch portion of the low-temperature bypass pipeline 26 (on the low-temperature heat exchanger 6 side). ) May be provided in the low temperature downstream pipe line 14. In addition, the predetermined temperature T2 at which the low-temperature circuit thermostat 27 opens and closes the pipe line may be the same as or different from the predetermined temperature T1 at which the main circuit thermostat 11 opens and closes the pipe line.

  According to this embodiment, when the temperature of the water temperature of the main circuit 2 is less than the predetermined temperature T1 and the water temperature of the low-temperature circuit 5 is less than the predetermined temperature T2, the cooling water of the main circuit 2 passes through the high-temperature heat exchanger 4. The cooling water in the low-temperature circuit 5 does not flow through the low-temperature heat exchanger 6. As described above, both the main circuit 2 and the low temperature circuit 5 are in the warm-up operation in which both the cooling water of the main circuit 2 and the low temperature circuit 5 are low in temperature (the first predetermined temperature T1 or lower and the second predetermined temperature T2 or lower). Since the cooling water is not cooled by the heat exchangers 4 and 6, the temperature of the engine 7 can be raised even earlier.

  Next, a fifth embodiment of the present invention will be described with reference to FIG. In addition, about the structure similar to the above-mentioned embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  As shown in FIG. 6, in the cooling system 29 of the present embodiment, a main branch pipeline 30 is provided in the main circuit 2 in addition to the cooling system 1 of the first embodiment.

  The main branch line 30 communicates the main upstream line 8 on the upstream side of the main circuit thermostat 11 and the main downstream line 9 on the upstream side of the water pump 3. The cooling water that has flowed from the main upstream pipe 8 into the main branch pipe 30 flows through the second cooling path in the EGR cooler 15 and flows into the main downstream pipe 9. Since the cooling water of the main circuit 2 has a higher temperature than the cooling water of the low-temperature circuit 5, the second cooling path through which the cooling water of the main circuit 2 flows is arranged upstream in the flow direction of the EGR gas. The cooling path through which the cooling water 5 flows is arranged on the downstream side in the flow direction of the EGR gas.

  According to the present embodiment, the EGR cooler 16 is multi-stage cooled by both the cooling water of the main circuit 2 (main branch pipe 30) and the cooling water of the low-temperature circuit 5, so that the intake air temperature of the engine 7 is reduced. Further promotion can improve fuel consumption.

  As mentioned above, although the embodiment to which the invention made by the present inventor is applied has been described, the present invention is not limited by the discussion and the drawings that form part of the disclosure of the present invention according to this embodiment. That is, it is needless to say that other embodiments, examples, operation techniques, and the like made by those skilled in the art based on this embodiment are all included in the scope of the present invention.

  For example, in the third or fourth embodiment, the main circuit thermostat 11 of the first embodiment may be provided instead of the high temperature heat exchange switching valve 24.

  Similarly to the fifth embodiment, the EGR cooler 16 of the second to fourth embodiments may be multi-stage cooled by the cooling water of the main branch pipeline 30, and the intercooler 15 may be multi-stage cooled by the cooling water of the main branch pipeline 30. It may be cooled.

  In the first or sixth embodiment, the ratio between the flow rate of the cooling water flowing into the intercooler 15 and the flow rate of the cooling water flowing into the EGR cooler 16 can be changed in the branch portions 14c of the low temperature branch pipes 14a and 14b. A flow rate control valve may be provided, and the flow rate control valve may be controlled to open and close so that the intake air temperature of the engine 7 is more efficiently lowered.

  In addition, the first to fifth embodiments do not prevent the provision of an auxiliary pump that assists the circulation of the cooling water in the low-temperature circuit 5. In this case, the auxiliary pump does not need the ability to circulate the cooling water alone, and only needs to be able to circulate the cooling water by assisting the water pump 3, so that a small and low-performance pump can be used. it can.

  The present invention can be applied to various vehicles including an engine as a cooling system suitable for improving fuel consumption.

1, 18, 19, 25, 29 Cooling system 2 Main circuit 3 Water pump (refrigerant pump)
4 High Temperature Heat Exchanger 5 Low Temperature Circuit 6 Low Temperature Heat Exchanger 7 Engine 8 Main Upstream Line 9 Main Downstream Line 10 Main Bypass Line 11 Main Circuit Thermostat 12 Junction 13 Low Temperature Upstream Line 14 Low Temperature Downstream Line Paths 14a and 14b Low-temperature branch line 15 Intercooler (intake air cooler)
16 EGR cooler (intake air cooler)
17 Branch 20 Low-temperature circuit flow control valve (low-temperature circuit flow rate changing means)
21 Engine load detector (engine load detector)
22 ECU (control means)
23 Water temperature sensor (refrigerant temperature detection means)
24 High temperature heat exchange switching valve (control valve)
26 Low-temperature bypass line 27 Low-temperature circuit thermostat 28 Merge section 30 Main branch line

Claims (7)

A main circuit through which refrigerant for cooling the engine circulates and circulates;
A refrigerant pump for circulating the refrigerant of the main circuit;
A high-temperature heat exchanger that is provided in the main circuit upstream of the refrigerant pump and that cools the refrigerant heated by the engine;
The refrigerant branched from the main circuit on the downstream side of the refrigerant pump and circulated from the main circuit to the intake air cooler that cools the intake air of the engine, and then to the main circuit on the upstream side of the refrigerant pump. A low-temperature circuit to merge,
A vehicle cooling system, comprising: a low-temperature heat exchanger provided in the low-temperature circuit upstream of the intake air cooler for cooling the refrigerant flowing from the main circuit. The cooling system according to claim 1,
A vehicle cooling system comprising: a low-temperature circuit flow rate changing means capable of increasing or decreasing the amount of refrigerant flowing from the main circuit to the low-temperature circuit. The cooling system according to claim 2,
Engine load detecting means for detecting the load of the engine;
The low-temperature circuit flow rate changing means is controlled to control the main circuit so that a refrigerant having a flow rate that effectively reduces the intake air temperature of the engine with respect to the engine load detected by the engine load detection means flows into the low-temperature circuit. And a control means for adjusting an inflow amount of the refrigerant from the circuit to the low temperature circuit. A cooling system according to claim 3,
Refrigerant temperature detection means for detecting the temperature of the refrigerant flowing into the main circuit from the engine,
The main circuit includes a main bypass pipe that communicates the upstream side and the downstream side of the high-temperature heat exchanger, a high-temperature heat exchange effective state in which the refrigerant flowing from the engine flows to the high-temperature heat exchanger, and the engine A control valve that can be set to a high-temperature heat exchange invalid state for circulating the refrigerant flowing in from the main bypass pipe without flowing to the high-temperature heat exchanger,
The control means raises the control valve when the refrigerant temperature detected by the refrigerant temperature detection means is equal to or higher than a predetermined temperature and the engine load detected by the engine load detection means is equal to or higher than a predetermined load. When the temperature of the refrigerant detected by the refrigerant temperature detecting means is lower than the predetermined temperature, or the temperature of the refrigerant detected by the refrigerant temperature detecting means is equal to or higher than the predetermined temperature When the engine load detected by the engine load detection means is less than the predetermined load, the control valve is set to the high temperature heat exchange invalid state. The cooling system according to any one of claims 1 to 3,
The main circuit flows from the engine when the temperature of the refrigerant flowing in from the engine is equal to or higher than a first predetermined temperature, and a main bypass line communicating the upstream side and the downstream side of the high-temperature heat exchanger. When the temperature of the refrigerant flowing from the engine is lower than the first predetermined temperature, the refrigerant flowing from the engine is not circulated to the high temperature heat exchanger. A main circuit thermostat that circulates to the main bypass line,
The low-temperature circuit includes the low-temperature bypass pipe that communicates the upstream side and the downstream side of the low-temperature heat exchanger, and the temperature of the refrigerant flowing from the main circuit is equal to or higher than a second predetermined temperature. The refrigerant flowing from the main circuit is circulated to the low temperature heat exchanger, and when the temperature of the refrigerant flowing from the main circuit is lower than the second predetermined temperature, the refrigerant flowing from the main circuit is circulated to the low temperature heat exchanger. And a low-temperature circuit thermostat for circulating to the low-temperature bypass pipe. The cooling system according to any one of claims 1 to 5,
The main circuit communicates the upstream side of the high-temperature heat exchanger and the upstream side of the refrigerant pump, and distributes the refrigerant branched and flowing from the upstream side of the high-temperature heat exchanger to the intake air cooler. A cooling system for a vehicle, characterized by comprising a conduit. The cooling system according to any one of claims 1 to 6,
The intake air cooler includes an intercooler and an EGR cooler arranged in series.

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