Cooling System

Abstract

Provided is a cooling system and a control method thereof, which are capable of discharging air in a coolant flow path, rapidly raising the coolant temperature during preheating to rapidly perform preheating, and additionally rapidly lowering the coolant temperature when knocking occurs to suppress knocking at an early stage. The cooling system 1 includes: a main passage L1 (L1a to L1c) that circulates coolant between the internal combustion engine 2 and the radiator 3; a sub-passage L2 (L2a to L2c) that circulates coolant between the internal combustion engine and the heat exchangers 4, 5, 6; a thermostat 7 that opens and closes the main passage L1 according to the coolant temperature; a thermostat bypass passage L3 (L3a, L3b) that bypasses the thermostat and connects the internal combustion engine and the radiator; and an electric valve 8 that opens and closes the sub-passage and the thermostat bypass passage.

Description

Technical Field

[0001] The present invention relates to a cooling system for an internal combustion engine. Background Art

[0002] In an existing cooling system for an internal combustion engine, in order to distribute coolant for cooling the internal combustion engine to various devices such as a radiator, a heating heat exchanger, an AT (automatic transmission) / CVT (continuously variable transmission), and an EGR (exhaust gas recirculation), an electric valve is provided.

[0003] As this electric valve, in order to prevent the coolant from overheating without circulating to the radiator in the event of a failure (when a malfunction occurs), an electric valve with a thermal valve (thermostat valve) having a safety function is used.

[0004] For example, in Patent Document 1, a cooling system using this electric valve with a thermal valve is shown. Based on Figure 4 、 Figure 5 A cooling system using the electric valve with a thermal valve described in Patent Document 1 will be described.

[0005] As Figure 4 shown in, in a circulation system (cooling system) 50 for automotive coolant, an electric valve 51 with a thermal valve is disposed on the side of a cylinder head CH of an internal combustion engine ENG.

[0006] Moreover, this electric valve 51 with a thermal valve distributes the coolant pressurized by a water pump WP and passing through the inside of the cylinder head CH to a heating heat exchanger HT, an oil cooler OC, and a radiator RAD side via a first pipe L1 to a third pipe L3, respectively, and controls the respective flow rates.

[0007] As Figure 5 shown in, this electric valve 51 with a thermal valve includes a speed reducer accommodated in a speed reducer accommodation portion 52, a valve body accommodated in a valve body accommodation portion 53, and an electric motor accommodated in a motor accommodation portion 54. Moreover, it is configured such that the rotation of the electric motor is decelerated by the speed reducer and the valve body rotates (operates) by a rotary shaft connected to the speed reducer. The aforementioned electric motor is controlled by an electronic control unit (ECU) mounted on the vehicle, and the valve body is rotationally controlled via the speed reducer according to the vehicle state.

[0008] Figure 5 A first communication port E1 of the aforementioned electric valve 51 with a thermal valve shown in is connected to Figure 4 a first pipe L1 shown in, and communicates with the heating heat exchanger HT. In addition, a second communication port E2 is connected to a second pipe L2 and communicates with the oil cooler OC. A third communication port E3 is connected to a third pipe L3 and communicates with the radiator RAD.

[0009] In addition, although not shown in the drawings, a thermal valve serving as a fail-safe mechanism is provided at the aforementioned third communication port E3. The thermal valve can communicate the valve body accommodating portion 53 with the third communication port E3 when the valve body cannot be driven due to a failure or the like, or when a predetermined pressure or temperature is reached.

[0010] Once the thermal valve serving as a fail-safe mechanism opens when the coolant temperature becomes high during a failure (fail), it ensures the supply path of the coolant to the radiator RAD and prevents overheating of the internal combustion engine ENG.

[0011] In addition, in the cooling system of an existing internal combustion engine, a thermostat is sometimes used to open and close the coolant passage. As the thermostat, a thermostat having a micro valve (jigul valve) for venting air described in Patent Document 2 (sometimes also referred to as a "chattering valve") is generally used.

[0012] In the thermostat having the micro valve for venting air, it operates in the following manner: it opens and closes the coolant passage according to the coolant temperature.

[0013] Prior Art Documents

[0014] Patent Documents

[0015] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2017-133622.

[0016] Patent Document 2: Japanese Utility Model Publication No. 53-146827. Summary of the Invention

[0017] Problems to be Solved by the Invention

[0018] However, in the case of the aforementioned electric valve with a thermal valve, the electric valve generally has a function of cooling the internal combustion engine and a function of distributing the coolant to each device such as a heating heat exchanger, an AT (automatic transmission) / CVT (continuously variable transmission), and an EGR (exhaust gas recirculation). Furthermore, since the thermal valve serving as a fail-safe mechanism and the electric valve are integrally provided, there is a problem as follows: it is large-sized, the mountability on a vehicle is poor, and in addition, the cost is high.

[0019] As one method for solving this problem, it is considered to configure the electric valve with a thermal valve in three functions. In this case, the function of cooling the internal combustion engine and the function as a fail-safe mechanism when the electric valve fails are aggregated in the existing WAX type thermostat, and the function of the electric valve is concentrated on distributing the coolant to each device, so that it can be miniaturized, the mountability on a vehicle can be improved, and a cost reduction can also be pursued.

[0020] In addition, in vehicles using existing electric valves, in order to shorten the warm-up time of the internal combustion engine and improve fuel consumption performance (fuel consumption) (sometimes also referred to as the number of kilometers traveled per liter of fuel), the flow rate of the coolant passing through the radiator is throttled for a constant time immediately after starting the internal combustion engine. However, in the case of using an existing thermostat, in order to vent the air in the coolant flow path, a thermostat (thermal valve) equipped with a micro-valve for venting air is required.

[0021] The micro-valve for venting air is structured to be closed by the pressure of the coolant. In the case of using a thermostat equipped with this micro-valve for venting air, even when the thermostat is closed, the coolant leaks from the micro-valve for venting air. Therefore, it is difficult to rapidly raise the coolant temperature during preheating (warming) and thus rapidly warm up. In addition, although existing electric valves can instantaneously change the coolant temperature to a desired temperature, in the case of separating this function and using an existing thermostat, there is a response delay compared to the electric valve. Therefore, a new problem arises in that it is difficult to rapidly lower the coolant temperature during knocking and suppress knocking at an early stage.

[0022] The present invention is made to solve the above problems, and an object thereof is to provide a cooling system that has good mountability, can vent the air in the coolant flow path, can rapidly raise the coolant temperature during preheating and thus rapidly perform preheating, and can rapidly lower the coolant temperature during knocking and suppress knocking at an early stage.

[0023] Means for Solving the Problems

[0024] The cooling system according to the present invention made to solve the above problems is characterized by including: an internal combustion engine; a radiator that releases heat from the coolant for cooling the internal combustion engine; one or more heat exchangers other than the radiator; a main passage that circulates the coolant between the internal combustion engine and the radiator; a thermostat that includes a temperature sensing unit that senses the temperature of the coolant and opens and closes the main passage according to the temperature of the coolant; a sub-passage that circulates the coolant between the internal combustion engine and the heat exchanger through a chamber in which the temperature sensing unit is disposed; a thermostat bypass passage that bypasses the thermostat and connects the internal combustion engine and the radiator; and an electric valve that opens and closes the sub-passage and the thermostat bypass passage.

[0025] In the cooling system of the present invention, a thermostat can be used to open and close the main passage, circulating the coolant passing through the radiator through the internal combustion engine. Additionally, the circulation of the coolant passing through the radiator to the internal combustion engine can be stopped. Further, the aforementioned electric valve is used to open and close the sub-passage for circulating the coolant between the internal combustion engine and the heat exchanger and the thermostat bypass passage (thermostat bypass path). Thus, the coolant passing through the radiator bypasses the thermostat, or the distribution of the coolant supplied to the heat exchanger changes.

[0026] In addition, the heat exchanger refers to a device supplied with coolant such as a heating heat exchanger, an ATF (Automatic Transmission Fluid) heating device (or a CVT (Continuously Variable Transmission) oil heating device), an EGR (Exhaust Gas Recirculation), a throttle body, etc. Additionally, bypassing the thermostat means bypassing (avoiding) the part of the thermostat opened and closed by the valve body.

[0027] According to the above configuration, the thermostat opens and closes the main passage according to the temperature of the coolant. The coolant can circulate through the radiator to the internal combustion engine, and additionally, the circulation of the coolant passing through the radiator to the internal combustion engine can be stopped. Thus, there is no need to provide a thermal valve as a fail-safe mechanism in the electric valve. That is, even when the electric valve fails, the aforementioned thermostat opens the main passage, thereby preventing overheating of the internal combustion engine ENG, etc.

[0028] Thus, the thermal valve can be eliminated from the electric valve. Furthermore, the electric valve only needs to be able to open and close only the sub-passage and the thermostat bypass passage, so it can be miniaturized. Moreover, if the electric valve becomes smaller, the mountability is improved, and the cost can be reduced.

[0029] More specifically, the miniaturized electric valve does not need to be arranged around the water pump of the engine. As long as it is in the middle of the thermostat bypass passage and the sub-passage, it can be arranged anywhere.

[0030] Moreover, the electric valve opens and closes the thermostat bypass passage that bypasses the thermostat. Therefore, even if the microswitch is eliminated from the thermostat, by using the electric valve to open the thermostat bypass passage, the air in the coolant flow path can be discharged through this thermostat bypass passage.

[0031] That is, according to the above configuration, the microswitch can be eliminated from the thermostat, thus preventing coolant leakage from the microswitch part. Thereby, the coolant temperature can rise rapidly during preheating for rapid preheating, and additionally, the coolant temperature can drop rapidly during knocking to suppress knocking at an early stage.

[0032] Additionally, it can also be that the aforementioned thermostat of the cooling system according to the present invention includes a heater for heating the aforementioned temperature sensing part.

[0033] If this is done, then during continuous high-load driving such as uphill driving, the temperature sensing unit (temperature sensing part) is heated by the heater, so that the state of the thermostat being open can be stably maintained. Therefore, even during high-load driving, the temperature of the coolant can be maintained at a low temperature.

[0034] In addition, in the cooling system according to the present invention, it may also be that when the ignition device switch of the internal combustion engine is turned off during startup, the electric valve opens the thermostat bypass passage.

[0035] If this is done, then in the state where the ignition device switch is turned off and the internal combustion engine is stopped, the air in the coolant flow path can be discharged through the thermostat bypass passage. Therefore, for example, even if the internal combustion engine stops before the temperature of the coolant reaches the valve opening temperature of the thermostat, the air in the coolant flow path can be discharged.

[0036] In addition, the cooling system according to the present invention may also include a control device for controlling the opening and closing of the electric valve. The control device is configured as follows: when it is determined that the internal combustion engine is performing warm-up operation, the electric valve is used to close the sub-passage and the thermostat bypass passage; when it is determined that the warm-up operation is completed, the electric valve is used to close the thermostat bypass passage and open the sub-passage; when it is determined that knocking occurs, even when it is determined that the warm-up operation is completed, the electric valve is used to open the thermostat bypass passage.

[0037] If this is done, then during the warm-up operation of the internal combustion engine when the temperature of the coolant is low, the main passage is closed by the thermostat, and the sub-passage and the thermostat bypass passage are closed by the electric valve. Therefore, the flow of the coolant flow path in the cooling system stops, and the temperature of the coolant can rise rapidly to quickly perform preheating. In addition, when the warm-up operation is completed, the sub-passage is opened, so that the thermostat can sense the temperature of the coolant and the thermostat can open the valve. In addition, when knocking occurs, the thermostat bypass passage is opened, so that the temperature of the coolant can drop rapidly to suppress knocking at an early stage.

[0038] Effects of the Invention

[0039] According to the present invention, a cooling system and its control method can be obtained, which have good mountability, can discharge the air in the coolant flow path, can rapidly increase the temperature of the coolant during preheating to quickly perform preheating, and can rapidly decrease the temperature of the coolant when knocking occurs to suppress knocking at an early stage. Description of the Drawings

[0040] Figure 1It is a schematic configuration diagram of the cooling system according to the first embodiment of the present invention.

[0041] Figure 2 It is for Figure 1 The cross-sectional view of the thermostat of the cooling system.

[0042] Figure 3 It is a schematic configuration diagram of the cooling system according to the second embodiment of the present invention.

[0043] Figure 4 It is a schematic configuration diagram of an existing cooling system.

[0044] Figure 5 It shows for Figure 4 The perspective view of the electric valve of the cooling system. Detailed implementation mode

[0045] Hereinafter, based on Figure 1 , Figure 2 The cooling system and its control method according to the first embodiment of the present invention will be described.

[0046] (Overview of the cooling system)

[0047] For example, as shown in Figure 1 , the cooling system 1 according to the present invention cools the internal combustion engine 2, and circulates the coolant that circulates between the water jacket 2a of the internal combustion engine 2 and the radiator 3 through each device (heat exchanger) such as the heating heat exchanger 4, the ATF (Automatic Transmission Fluid) heating device (or CVT (Continuously Variable Transmission) oil heating device) 5, and the EGR (Exhaust Gas Recirculation) 6, and the coolant is used separately in each device.

[0048] In addition, the foregoing each device (heat exchanger) is an example, and it can also be used for a throttle body.

[0049] The cooling system 1 includes: a thermostat 7 that opens and closes the main passage L1 for circulating the coolant between the water jacket 2a of the internal combustion engine 2 and the radiator 3; a sub-passage L2 that communicates with the chamber (second chamber 7b) accommodating the temperature sensing portion 7B8 of the thermostat 7, and circulates the coolant between the water jacket 2a and heat exchangers other than the radiator 3 such as the heating heat exchanger 4, the ATF heating device (or CVT oil heating device) 5, and the EGR 6; and an electric valve 8 that opens and closes the sub-passage L2 to change the distribution of the coolant supplied to each heat exchanger.

[0050] In addition, the aforementioned electric valve 8 opens and closes a thermostat bypass passage (thermostat bypass path) L3 that bypasses the thermostat 7. When the electric valve 8 opens the thermostat bypass passage L3, the internal combustion engine 2 communicates with the radiator 3. Thus, the coolant that cools the internal combustion engine 2 can circulate between the internal combustion engine 2 and the radiator 3 without passing through the thermostat 7.

[0051] Hereinafter, this cooling system 1 will be described in detail.

[0052] (Passages of the cooling system)

[0053] As Figure 1 shown, the cooling system 1 includes a main passage L1 that circulates coolant between the internal combustion engine 2 and the radiator 3. In the present embodiment, the main passage L1 includes a first main passage L1a, a second main passage L1b, and a third main passage L1c.

[0054] The aforementioned first main passage L1a connects the coolant outlet of the water jacket 2a of the internal combustion engine 2 to the coolant inlet of the radiator 3. The aforementioned second main passage L1b connects the coolant outlet of the radiator 3 to the thermostat 7. The aforementioned third main passage L1c connects the thermostat 7 to the suction port of the water pump 9.

[0055] Moreover, the coolant sucked from the third main passage L1c and discharged from the water pump 9 is transported to the water jacket 2a. In this way, the coolant flows through the internal combustion engine 2 and the radiator 3 through the main passage L1. The thermostat 7 opens and closes the connection portion between the second main passage L1b and the third main passage L1c in the main passage L1 according to the temperature of the coolant.

[0056] In addition, the cooling system 1 includes a sub-passage L2 that circulates coolant between the internal combustion engine 2 and the heating heat exchanger 4, the ATF heating device (or CVT oil heating device) 5, and the EGR 6. In the present embodiment, the sub-passage L2 includes a first sub-passage L2a, a second sub-passage L2b, a third sub-passage L2c, and a fourth sub-passage L2d.

[0057] The aforementioned first sub-passage L2a connects the coolant outlet of the water jacket 2a to each heat exchanger such as the heating heat exchanger 4, the ATF heating device (or CVT oil heating device) 5, and the EGR 6.

[0058] The aforementioned second sub-passage L2b connects each of the heat exchangers to the electric valve 8. The aforementioned third sub-passage L2c connects the electric valve 8 to the room (the second chamber 7b described later) where the temperature sensing unit 7B8 of the thermostat 7 is disposed.

[0059] The aforementioned fourth sub-passage L2d connects the second chamber 7b to the suction port of the water pump 9.

[0060] The fourth sub-passage L2d and the third main passage L1c share a pipeline. That is, the third main passage L1c is also connected to the second chamber 7b of the temperature sensing unit 7B8 where the thermostat 7 is disposed. The thermostat 7 senses the temperature around the temperature sensing unit 7B8 in the second chamber 7b and permits or cuts off the communication between the second main passage L1b and the third main passage L1c.

[0061] In addition, the opening and closing of the second sub-passage L2b leading to each heat exchanger such as the heating heat exchanger 4, the ATF heating device (or CVT oil heating device) 5, and the EGR 6 is performed by the electric valve 8. Thus, the distribution of the coolant supplied to each heat exchanger is changed.

[0062] In addition, the cooling system 1 includes a thermostat bypass passage L3 that bypasses the aforementioned thermostat 7 and circulates the coolant between the internal combustion engine 2 and the radiator 3.

[0063] In the present embodiment, the thermostat bypass passage L3 includes an upstream passage L3a that connects a midway point of the second main passage L1b to the electric valve 8 and a downstream passage L3b that connects the electric valve 8 to a midway point of the third main passage L1c.

[0064] As described above, the second main passage L1b is connected to the radiator 3, and the third main passage L1c is connected to the water pump 9. Therefore, even when the thermostat 7 closes the main passage L1, if the electric valve 8 opens the thermostat bypass passage L3, the coolant flowing out from the water jacket 2a also goes to the water pump 9 through the first main passage L1a, the radiator 3, the second main passage L1b, the thermostat bypass passage L3, and the third main passage L1c.

[0065] (Thermostat)

[0066] As Figure 1 shown, the thermostat 7 is housed in a housing 7A.

[0067] The interior of the housing 7A is partitioned into two chambers 7a and 7b by a valve body 7B1 of the thermostat 7 described later. If one of these two chambers is taken as the first chamber 7a and the other as the second chamber 7b, the second main passage L1b is connected to the first chamber 7a, and the third main passage L1c is connected to the second chamber (room) 7b.

[0068] As Figure 2 shown, the thermostat 7 includes: a thermocouple 7B2 as a temperature sensing working body; a valve body 7B1 that is driven by the thermocouple 7B2 to leave and seat on a valve seat 7B3 to open and close the main passage L1; a spring 784 as a biasing member that always biases the valve body 7B1 in the direction of closing the valve (the direction of seating on the valve seat 7B3); and a cylindrical holder 7B9 into which the coolant from the third sub-passage L2c flows.

[0069] The thermocouple 7B2 includes: a piston guide 7B5; a piston 7B7 that is guided by the piston guide 7B5 and moves forward and backward simultaneously, and the tip of which engages with a piston receiving portion 7B6; and a temperature sensing portion (temperature sensing part) 7B8 that incorporates wax as a thermal expansion body that expands or contracts according to the temperature change of the coolant to move the piston 7B7 forward and backward.

[0070] The aforementioned retainer 7B9 is disposed on the outer periphery of the temperature sensing portion 7B8, and the coolant flowing from the third sub-passage L2c to the fourth sub-passage L2d passes through the inside of the retainer 7B9 and the hole 7B10 of the retainer 7B9.

[0071] Moreover, if the coolant around the temperature sensing portion 7B8 rises above a predetermined temperature, the wax inside the temperature sensing portion 7B8 expands, and the piston 7B7 is pushed out, and the valve body 7B1 separates from the valve seat 7B3 to open the main passage L1.

[0072] That is, if the valve body 7B1 of the thermostat 7 separates from the valve seat 7B3, the two chambers 7a and 7b are communicated via the gap formed therebetween, and the second main passage L1b and the third main passage L1c are communicated. As a result, the cooled coolant passing through the radiator 3 is supplied to the internal combustion engine 2 through the main passage L1.

[0073] In addition, if the temperature of the coolant around the temperature sensing portion 7B8 drops compared to the predetermined temperature, the wax built into the temperature sensing portion 7B8 contracts, and the piston 7B7 is pushed back via the valve body 7B1 using the biasing force of the spring 7B4, and the valve body 7B1 seats on the valve seat 7B3 to close the main passage L1.

[0074] In this way, if the thermostat 7 is closed, the communication between the two chambers 7a and 7b is cut off, and as a result, the communication between the second main passage L1b and the third main passage L1c is cut off.

[0075] Here, an example of the thermostat has been described, but the configuration of the thermostat can be appropriately changed.

[0076] For example, if the retainer 7B9 is provided on the outer periphery of the temperature sensing portion as described above, when the thermostat 7 is provided on the coolant inlet side of the internal combustion engine 2, the temperature sensitivity of the thermostat 7 can be made good, but the retainer 7B9 can also be omitted. In addition, the thermostat 7 can also include a sub-valve body that opens and closes the sub-passage L2 in addition to the valve body 7B1.

[0077] In addition, in the present embodiment, the valve seat 7B3 is formed in the frame 7C including the piston receiving portion 7B6 of the thermostat 7, but it can also be that the housing 7A achieves the function of the frame 7C, and the valve seat 7B3 is formed in the housing 7A. Furthermore, the retainer 7B9 can also be provided integrally with the housing 7A.

[0078] (Electric valve 8)

[0079] The electric valve 8 can be applied to valves for general use. For example, the thermal valve as a fail-safe mechanism can also be removed by using the electric valve shown in the aforementioned Patent Document 1. Hereinafter, an example of the electric valve 8 will be described.

[0080] The electric valve 8 includes a speed reducer accommodated in the speed reducer accommodation part, a valve body accommodated in the valve body accommodation part, and an electric motor accommodated in the motor accommodation part. Moreover, it is configured such that the rotation of the aforementioned electric motor is decelerated by the speed reducer, and the valve body rotates (operates) by connecting to the rotating shaft of the speed reducer. The aforementioned electric motor is controlled by a control device (ECU) mounted on the vehicle, and the valve body (rotary valve body) is rotationally controlled via the speed reducer according to the vehicle state.

[0081] By rotationally driving the valve body, the second sub-passage L2b connected to each heat exchanger such as the heating heat exchanger 4, the ATF (Automatic Transmission Fluid) heating device (or CVT (Continuously Variable Transmission) oil heating device) 5, and the EGR (Exhaust Gas Recirculation) 6 is opened and closed, and the distribution of the coolant supplied to the heat exchanger is changed.

[0082] In addition, the valve body of the electric valve 8 is not limited to the aforementioned rotary valve body, and may also be a spool valve body that performs linear movement. In addition, a solenoid valve can also be used to directly open and close the valve.

[0083] (Operation and function of the cooling system)

[0084] Through the driver's selection, and based on information from various sensors provided on the vehicle, the electric valve 8 is opened and closed by electronic control, thereby opening and closing the second sub-passage L2b. As a result, a state is achieved in which coolant is supplied to or not supplied to the heating heat exchanger 4, the ATF heating device (or CVT oil heating device) 5, and the EGR 6.

[0085] In addition, the opening and closing of the thermostat bypass passage L3 is performed by electronic control of the electric valve 8 based on information from various sensors provided on the vehicle according to the state of the internal combustion engine and the temperature of the coolant.

[0086] Furthermore, in a state where the ignition device of the internal combustion engine 2 is turned off (OFF) and the internal combustion engine is stopped, the electric valve 8 is in a non-energized state. In such a non-energized state, the electric valve 8 is set to open the thermostat bypass passage L3. If this is done, even in a state where the temperature of the coolant is low and the thermostat 7 is closed, air in the coolant flow path can be discharged through the thermostat bypass passage L3.

[0087] Therefore, there is no need to provide a microswitch for bleeding air in the thermostat 7, and the microswitch is omitted in the thermostat 7. That is, even when using the thermostat 7 without a microvalve for bleeding air, it is possible to bleed the air in the coolant flow path.

[0088] Next, an example of electronic control will be described.

[0089] If the ignition device is turned on (ON), after the control device determines whether various electrical devices such as the electric valve 8 are normal, the internal combustion engine 2 starts and warm-up operation begins. In addition, when the control device determines that it is in warm-up operation, it outputs an instruction to close the sub-path L2 by the electric valve 8 and close the thermostat bypass path L3. The determination of whether it is in warm-up operation can be made based on the temperature of the coolant detected by the temperature sensor or based on the time since the start of the internal combustion engine 2.

[0090] Thus, during warm-up operation, the connection of the sub-path L2 and the thermostat bypass path L3 is cut off by the electric valve 8.

[0091] In addition, during warm-up operation, the temperature of the coolant is low, the thermostat 7 is closed, and the connection of the main path L1 is also cut off. At this time, since there is no microswitch provided in the thermostat 7, the cooled coolant passing through the radiator 3 does not leak from the position where the microswitch was previously provided, so the temperature of the coolant rises rapidly and preheating is carried out quickly.

[0092] Next, when the control device determines that the warm-up operation of the internal combustion engine 2 is completed, it outputs an instruction to close the thermostat bypass path L3 by the electric valve 8, and outputs an instruction to selectively open the second sub-path L2b connected to each heat exchanger such as the heating heat exchanger 4, the ATF (Automatic Transmission Fluid) heating device (or the CVT (Continuously Variable Transmission) oil heating device) 5, and the EGR (Exhaust Gas Recirculation) 6 according to the temperature of the coolant.

[0093] Thus, the coolant heated by the internal combustion engine 2 reaches the temperature sensing portion 7B8 of the thermostat 7 through the sub-path L2, and the thermostat 7 can sense the temperature of the heated coolant.

[0094] At this time, if the temperature of the coolant reaches the opening temperature of the thermostat 7, the thermostat 7 opens the main path L1, and the cooled coolant passing through the radiator 3 is supplied to the internal combustion engine 2 through the main path L1.

[0095] In addition, even during warm-up operation, for example, when the control device determines that heating is required, it can output an instruction to open the second sub-path L2b leading to the heating heat exchanger 4 by the electric valve 8.

[0096] Next, when the control device determines that knocking has occurred, even after it is determined that warm-up operation has ended, an instruction is output to open the thermostat bypass passage L3 by the electric valve 8. The determination of whether knocking has occurred can be made based on information from a knocking sensor or on information detected by other sensors.

[0097] If the temperature of the coolant becomes high, knocking occurs. Therefore, the thermostat 7 opens the main passage L1, and further the electric valve 8 opens the thermostat bypass passage L3, so that the temperature of the coolant can be rapidly decreased, and knocking can be suppressed at an early stage.

[0098] Furthermore, when the control device determines that knocking has occurred, an instruction may also be output to open the thermostat bypass passage L3 and close the sub-passage L2 by the electric valve 8. If this is done, the flow rate of the coolant flowing to the radiator 3 increases, and thus knocking can be suppressed at an earlier stage.

[0099] (Operation and function of a cooling system using an electronically controlled thermostatic valve)

[0100] As the thermostat, an electronically controlled thermostat in which a heater for heating the temperature sensing portion 7B8 is provided in the thermocouple 7B2 can also be used.

[0101] When using a thermostat 7 of a type that is not electronically controlled and does not have a built-in heater, if the thermostat 7 opens and the cooled coolant flows into the second chamber 7b where the temperature sensing portion 7B8 is disposed, the valve body 7B1 of the thermostat 7 moves in the closing direction, and the flow rate of the coolant passing through the main passage L1 decreases.

[0102] In contrast, when using an electronically controlled thermostat, the temperature sensing portion 7B8 can be heated by the heater to maintain the electronically controlled thermostat in an open valve state.

[0103] Thus, even in a continuous high-load driving mode such as uphill driving, the temperature of the coolant can be maintained at a low temperature.

[0104] (Second Embodiment)

[0105] In the first embodiment, the case where the thermostat 7 is provided on the coolant inlet side of the internal combustion engine 2 has been described, but it may be provided on the outlet side of the internal combustion engine 2 as shown in Figure 3 . In addition, the same reference numerals are given to the same or corresponding components as those in the first embodiment, and their detailed descriptions are omitted.

[0106] Regarding the cooling system 10 of this second embodiment, as shown in Figure 3As shown, the main passage L11 that circulates the coolant between the internal combustion engine 2 and the radiator 3 includes a first main passage L11a, a second main passage L11b, and a third main passage L11c.

[0107] The aforementioned first main passage L11a connects the coolant outlet of the water jacket 2a of the internal combustion engine 2 to the thermostat 7, the aforementioned second main passage L11b connects the thermostat 7 to the coolant inlet of the radiator 3, and the aforementioned third main passage L11c connects the coolant outlet of the radiator 3 to the suction port of the water pump 9.

[0108] Moreover, the coolant sucked from the third main passage L11c and discharged from the water pump 9 is transported to the water jacket 2a. In this way, the coolant flows through the internal combustion engine 2 and the radiator 3 via the main passage L11. The thermostat 7 opens and closes the connection portion between the first main passage L11a and the second main passage L11b in the main passage L11 according to the temperature of the coolant.

[0109] In addition, the cooling system 10 includes a sub-passage L12 that circulates the coolant between the internal combustion engine 2 and the heating heat exchanger 4, the ATF heating device (or CVT oil heating device) 5, and the EGR 6. In this embodiment, the sub-passage L12 includes a first sub-passage L12a, a second sub-passage L12b, a third sub-passage L12c, and a fourth sub-passage L12d.

[0110] The aforementioned first sub-passage L12a connects the coolant outlet of the water jacket 2a to the second chamber 7b of the temperature sensing portion 7B8 of the thermostat 7.

[0111] The aforementioned second sub-passage L12b connects the second chamber 7b of the temperature sensing portion 7B8 of the thermostat 7 to the electric valve 8.

[0112] The aforementioned third sub-passage L12c connects the electric valve 8 to each heat exchanger such as the heating heat exchanger 4, the ATF heating device (or CVT oil heating device) 5, and the EGR 6.

[0113] The aforementioned fourth sub-passage L12d connects each of the aforementioned heat exchangers to the suction port of the water pump 9.

[0114] The aforementioned first sub-passage L12a and the first main passage L11a share a pipeline. That is, the first main passage L11a is also connected to the second chamber 7b of the temperature sensing portion 7B8 of the thermostat 7. The thermostat 7 senses the temperature around the temperature sensing portion 7B8 in the second chamber 7b and permits or cuts off the communication between the first main passage L11a and the second main passage L11b.

[0115] In addition, the opening and closing of the third sub-passage L12c leading to each heat exchanger such as the heating heat exchanger 4, the ATF heating device (or CVT oil heating device) 5, and the EGR 6 is performed by the electric valve 8, whereby the distribution of the coolant supplied to each heat exchanger is changed.

[0116] In addition, the cooling system 10 includes a thermostat bypass passage L13 that bypasses the aforementioned thermostat 7 and circulates the coolant between the internal combustion engine 2 and the radiator 3.

[0117] In the present embodiment, the thermostat bypass passage L13 connects the electric valve 8 to the middle of the second main passage L11b.

[0118] Moreover, even when the thermostat 7 closes the main passage L11, if the electric valve 8 opens the thermostat bypass passage L13, the coolant flowing out from the water jacket 2a passes through the first main passage L11a, the second sub-passage L12b, the thermostat bypass passage L13, the second main passage L11b, the radiator 3, and the third main passage L11c to reach the water pump 9.

[0119] In the second embodiment configured as described above, the same thermostat 7 and electric valve 8 as those in the first embodiment are provided, and thus the switching between the case where the coolant for cooling the internal combustion engine 2 passes through the thermostat 7 and the case where it bypasses the thermostat 7 is performed.

[0120] As a result, in this second embodiment as well, similar to the first embodiment, air in the coolant can be discharged, the coolant temperature can be rapidly increased during preheating for rapid preheating, and in addition, when knocking occurs, the coolant temperature can be rapidly decreased to suppress knocking at an early stage, and the same effects as those in the first embodiment can be obtained.

[0121] Reference Signs

[0122] 1, 10 Cooling system

[0123] 2 Internal combustion engine

[0124] 3 Radiator

[0125] 4 Heating heat exchanger (heat exchanger)

[0126] 5 ATF heating device or CVT oil heating device (heat exchanger)

[0127] 6 EGR (heat exchanger)

[0128] 7 Thermostat

[0129] 7A Housing

[0130] 7a First chamber

[0131] 7b Second chamber (room)

[0132] 8 Electric valve

[0133] 9 Water pump

[0134] L1, L11 Main passage

[0135] L2, L12 Sub - passage

[0136] L3, L13 Thermostat bypass passage.

Claims

1. A cooling system, characterized in that, Comprising: An internal combustion engine; A radiator that releases heat from a coolant used to cool the internal combustion engine; One or more heat exchangers other than the radiator; A main passage that circulates the coolant between the internal combustion engine and the radiator; A thermostat that includes a temperature sensing portion for sensing the temperature of the coolant and opens and closes the main passage according to the temperature of the coolant; A sub-passage that circulates the coolant between the internal combustion engine and the heat exchanger through a chamber in which the temperature sensing portion is disposed; A thermostat bypass passage that bypasses the thermostat and connects the internal combustion engine and the radiator; and An electric valve that opens and closes the sub-passage and the thermostat bypass passage.

2. The cooling system according to claim 1, wherein: The thermostat includes a heater for heating the temperature sensing portion.

3. The cooling system according to claim 1 or 2, wherein: When the ignition device switch for starting the internal combustion engine is turned off, the electric valve opens the thermostat bypass passage.

4. The cooling system according to claim 1, wherein: A control device for controlling the opening and closing of the electric valve is provided, The control device When it is determined that the internal combustion engine is performing warm-up operation, closes the sub-passage and the thermostat bypass passage using the electric valve, When it is determined that the warm-up operation has ended, closes the thermostat bypass passage and opens the sub-passage using the electric valve, When it is determined that knocking has occurred, even when it is determined that the warm-up operation has ended, opens the thermostat bypass passage using the electric valve.

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