Engine cooling system

Abstract

This invention provides an engine cooling system, including a cooling device, a radiator, and a valve assembly. The cooling device includes a first cooler and a second cooler. The first cooler is configured to form an intercooler for the engine, and the second cooler is configured to dissipate heat from the engine's EGR system. The valve assembly includes a first valve and a second valve. The first valve is used to regulate the flow rate of the cooling medium exiting the first and second coolers, respectively, to change the temperature of the pressurized air and low-pressure exhaust gas entering the engine cylinders. The connection state of the first and second inlets of the second valve is adjustable to change the temperature of the cooling medium exiting the first valve. The engine cooling system provided by this invention can provide lower exhaust gas temperatures and improve engine power and torque at low speeds.

Description

Technical Field

[0001] This invention belongs to the field of engines, and specifically relates to an engine cooling system. Background Technology

[0002] Currently, a large amount of exhaust gas is generated during the operation of an engine. Since the exhaust gas contains a large amount of CO2, and CO2 cannot be burned and has a high specific heat capacity, it can absorb a large amount of heat. The exhaust gas can be used to lower the temperature of the air-fuel mixture in the engine cylinder.

[0003] To better utilize exhaust gases, a portion of them can be recirculated. Existing exhaust gas recirculation systems use high-pressure exhaust gases. Specifically, the high-pressure exhaust gases generated by the engine are returned to the engine cylinders, where they absorb a significant amount of heat from the engine, thereby reducing the high temperatures generated during engine operation.

[0004] However, high-pressure exhaust gas cannot be delivered to the engine cylinders at low engine speeds, causing the engine temperature to be too high at low speeds, which affects the engine's power and torque. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides an engine cooling system that can provide lower exhaust gas temperatures and improve engine power and torque at low speeds.

[0006] The present invention provides an engine cooling system, including a cooling device, a radiator and a valve device. The cooling device includes a first cooler and a second cooler. The first cooler is configured to form an intercooler of the engine, and the second cooler is configured to dissipate heat from the engine's EGR device.

[0007] The radiator has an outlet for the cooling medium to flow out and an inlet for the cooling medium to flow back. The valve device includes a first valve and a second valve. The first cooler and the second cooler are both connected to the inlet of the radiator via the first valve. The first valve is used to regulate the flow rate of the cooling medium flowing out of the first cooler and the second cooler respectively, so as to change the temperature of the boosted air and low-pressure exhaust gas entering the cylinder of the engine.

[0008] The second valve has a first inlet, a second inlet, and a first outlet. The first inlet is connected to the inlet of the radiator, the second inlet is connected between the first valve and the inlet of the radiator, and the first outlet is connected to the first cooler and the second cooler. The connection state of the first inlet and the second inlet can be adjusted to change the temperature of the cooling medium flowing out of the first valve.

[0009] Optionally, the first cooler and the second cooler are connected in parallel to the first liquid outlet.

[0010] Optionally, when the engine is idling, the first inlet is open and the second inlet is closed; when the engine is in the first operating condition, both the first and second inlets are open; when the engine is in the second operating condition, the first inlet is closed and the second inlet is open, wherein the engine speed in the second operating condition is greater than the engine speed in the first operating condition, and the engine speed in the first operating condition is greater than the engine speed in the idling state.

[0011] Optionally, the second valve is a three-way proportional valve.

[0012] Optionally, the first valve includes a third liquid inlet, a fourth liquid inlet, and a second liquid outlet. The third liquid inlet is connected to the first cooler, the fourth liquid inlet is connected to the second cooler, and the second liquid outlet is connected to the inlet of the radiator.

[0013] Optionally, the opening of the third and fourth liquid inlets can be adjusted separately.

[0014] Optionally, the first valve is a three-way proportional valve.

[0015] Optionally, the engine cooling system also includes a water pump, with the water inlet connected to a first outlet and the water outlet connected to a first cooler and a second cooler.

[0016] Optionally, the water pump is a mechanical centrifugal water pump.

[0017] Optionally, the engine cooling system also includes a controller, with both the first valve and the second valve electrically connected to the controller, which controls the connection state of the first valve and the second valve respectively.

[0018] This invention provides an engine cooling system, including a cooling device, a radiator, and a valve assembly. The cooling device includes a first cooler and a second cooler. The first cooler is configured to form an intercooler for the engine, and the second cooler is configured to dissipate heat from the engine's EGR device. The radiator has an outlet for discharging cooling medium and an inlet for cooling medium recirculation. The valve assembly includes a first valve and a second valve. Both the first and second coolers are connected to the radiator inlet via the first valve. The first valve is used to regulate the flow rate of the cooling medium exiting the first and second coolers, respectively, to change the temperature of the pressurized air and low-pressure exhaust gas entering the engine cylinders. The second valve has a first inlet, a second inlet, and a first outlet. The first inlet is connected to the radiator inlet, the second inlet is connected between the first valve and the radiator inlet, and the first outlet connects both the first and second coolers. The connection state of both the first and second inlets is adjustable to change the temperature of the cooling medium exiting the first valve. The engine cooling system provided by this invention can provide lower exhaust gas temperatures and improve engine power and torque at low speeds. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the engine cooling system provided in an embodiment of the present invention;

[0021] Figure 2 A flowchart of an engine cooling system provided for an embodiment of the present invention.

[0022] Explanation of reference numerals in the attached figures:

[0023] 100 - Engine cooling system;

[0024] 110 - Cooling device;

[0025] 120-Radiator;

[0026] 130 - Valve assembly;

[0027] 140 - Water pump;

[0028] 111 - First Cooler;

[0029] 112 - Second cooler;

[0030] 121 - Export;

[0031] 122 - Entrance;

[0032] 131 - First valve;

[0033] 132 - Second valve;

[0034] 1311 - Third liquid inlet;

[0035] 1312 - Fourth liquid inlet;

[0036] 1313 - Second liquid outlet;

[0037] 1321 - First liquid inlet;

[0038] 1322 - Second liquid inlet;

[0039] 1323 - First liquid outlet;

[0040] 141 - Water inlet end;

[0041] 142 - Water outlet. Detailed Implementation

[0042] To make the above-mentioned objectives, features, and advantages of the embodiments of the present invention more apparent and understandable, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] To better utilize exhaust gases, a portion of them can be recirculated. Existing exhaust gas recirculation systems use high-pressure exhaust gases. Specifically, the high-pressure exhaust gases generated by the engine are returned to the engine cylinders, where they absorb a significant amount of heat from the engine, thereby reducing the high temperatures generated during engine operation.

[0044] However, high-pressure exhaust gas cannot be delivered to the engine cylinders at low engine speeds, causing the engine temperature to be too high at low speeds, which affects the engine's power and torque.

[0045] To address the aforementioned problems, this invention provides an engine cooling system, comprising a first cooler, a second cooler, a radiator, a first valve, and a second valve. The first valve can be used to regulate the flow rate of the cooling medium exiting the first and second coolers, respectively, and the second valve can be used to regulate the temperature of the boosted air and the low-pressure exhaust gas. This allows the engine to provide a lower exhaust gas temperature at low speeds, thereby improving the engine's power and torque at low speeds.

[0046] The specific content of the present invention will now be further described in conjunction with the accompanying drawings and specific embodiments.

[0047] To better utilize exhaust gases, a portion of them can be recirculated. Existing exhaust gas recirculation systems use high-pressure exhaust gases. Specifically, the high-pressure exhaust gases generated by the engine are returned to the engine cylinders, where they absorb a significant amount of heat from the engine, thus reducing the high temperatures generated during engine operation. However, the high-pressure exhaust gases cannot be delivered to the engine cylinders at low engine speeds, causing the engine to overheat at low speeds, affecting engine power and torque.

[0048] The engine cooling system provided by this invention includes a cooling device, a radiator, and a valve device. The cooling device includes a first cooler and a second cooler, and the valve device includes a first valve and a second valve. Since the flow rate of the cooling medium exiting the first and second coolers can be adjusted by the first valve, and the temperature of the boosted air and low-pressure exhaust gas can be adjusted by the second valve, the engine can provide a lower exhaust gas temperature at low speeds. This lower temperature low-pressure exhaust gas further reduces the engine temperature, thereby increasing the engine's power and torque at low speeds.

[0049] During engine operation, the engine temperature gradually increases due to factors such as operating time, power, and speed. When the engine temperature is too high, it will affect the engine's performance and safety. In order to reduce the high temperature generated by the engine during operation and keep the engine temperature within the normal operating range, the engine cooling system is used for regulation.

[0050] Because existing methods directly use exhaust gas discharged from the engine cylinder, which is high-pressure exhaust gas, this invention uses low-pressure exhaust gas discharged from the engine cylinder after further buffering, and then re-transmits it to the engine cylinder before it is pressurized, so that it can work during the engine's compression stroke.

[0051] Figure 1 This is a schematic diagram of the engine cooling system provided in an embodiment of the present invention. Figure 2 A flowchart of an engine cooling system provided for an embodiment of the present invention. (See attached diagram.) Figure 1 and Figure 2 As shown, the engine cooling system 100 includes a cooling device 110, a radiator 120, and a valve device 130. The cooling device 110 is used to reduce the engine temperature and includes a first cooler 111 and a second cooler 112. The first cooler 111 is configured to form an intercooler for the engine to reduce the temperature of the high-temperature compressed air, thereby reducing the engine's thermal load, increasing the intake air volume, and thus increasing the engine's power. The second cooler 112 is configured to dissipate heat from the engine's EGR (Exhaust Gas Recirculation) device to reduce the temperature of the exhaust gas used to recirculate into the engine cylinders, thereby further reducing the temperature of the compressed air in the engine cylinders through cooler exhaust gas, increasing the engine's power.

[0052] Since the first cooler 111 and the second cooler 112 will increase in temperature while cooling the pressurized air and exhaust gas, the radiator 120 has an outlet 121 for the cooling medium to flow out and an inlet 122 for the cooling medium to flow back, so as to cool the first cooler 111 and the second cooler 112 that have increased in temperature.

[0053] Furthermore, the valve device 130 includes a first valve 131 and a second valve 132. The first cooler 111 and the second cooler 112 are both connected to the inlet 122 of the radiator 120 via the first valve 131. The first cooler 111 is connected to the first valve 131 and the second cooler 112 is connected to the first valve 131, or the first cooler 111 and the first valve 131 are not connected and the second cooler 112 is connected to the first valve 131, or the first cooler 111 and the first valve 131 are connected and the second cooler 112 is not connected. This allows the flow rate of the cooling medium flowing out of the first cooler 111 and the second cooler 112 to be adjusted by the first valve 131, thereby changing the temperature of the boosted air and low-pressure exhaust gas entering the cylinder of the engine.

[0054] Specifically, the second valve 132 has a first inlet 1321, a second inlet 1322, and a first outlet 1323. The first inlet 1321 is connected to the inlet 122 of the radiator 120, the second inlet 1322 is connected between the first valve 131 and the inlet 122 of the radiator 120, and the first outlet 1323 is connected to the first cooler 111 and the second cooler 112. The connection state of the first inlet 1321 and the second inlet 1322 can be adjusted to change the temperature of the cooling medium flowing out of the first valve 131.

[0055] Since the flow rate of the cooling medium flowing out of the first cooler 111 and the second cooler 112 can be adjusted by the first valve 131, the temperature of the boosted air and low-pressure exhaust gas entering the cylinder of the engine can be changed. Furthermore, the temperature of the cooling medium flowing out of the first valve 131 can be further reduced by the second valve 132. This allows the engine to provide a lower exhaust gas temperature at low speeds. The lower temperature low-pressure exhaust gas further reduces the engine temperature, thereby increasing the engine's power and torque at low speeds.

[0056] Optionally, the first cooler 111 and the second cooler 112 are connected in parallel to the first outlet 1323. Specifically, since the first cooler 111 and the second cooler 112 are connected in parallel to the first outlet 1323, the cooling medium flowing out of the first outlet 1323 can enter the first cooler 111 and the second cooler 112 according to different engine operating states, so as to regulate the flow rate of the cooling medium flowing out of the first cooler 111 and the second cooler 112, thereby changing the temperature of the boosted air and low-pressure exhaust gas entering the engine cylinder. Furthermore, since the first cooler 111 and the second cooler 112 are connected in parallel to the first outlet 1323, the cooling medium entering the first cooler 111 and the second cooler 112 does not affect each other.

[0057] Optionally, when the engine is idling, the first inlet 1321 is open and the second inlet 1322 is closed; when the engine is in the first operating condition, both the first inlet 1321 and the second inlet 1322 are open; when the engine is in the second operating condition, the first inlet 1321 is closed and the second inlet 1322 is open, wherein the engine speed in the second operating condition is greater than the engine speed corresponding to the first operating condition, and the engine speed corresponding to the first operating condition is greater than the engine speed corresponding to the idling state.

[0058] Specifically, when the engine is idling, the engine temperature is low. The first inlet 1321 is open, and the second inlet 1322 is closed. The cooling medium flowing out of the first cooler 111 and the second cooler 112 does not pass through the radiator 120 and can return to the first cooler 111 or the second cooler 112 to cool the pressurized air or low-pressure exhaust gas. This achieves a lower engine temperature at idle while avoiding unnecessary energy waste caused by the radiator 120 operating. As the engine speed gradually increases, and the engine successively enters the first and second operating conditions, the flow rate of the cooling medium flowing out of the first cooler 111 and the second cooler 112 through the radiator 120 gradually increases. This allows the engine temperature to be further reduced at higher speeds, thereby achieving temperature regulation of the engine under different operating conditions and enabling precise control of the EGR device temperature under different operating conditions.

[0059] Optionally, the second valve 132 is a three-way proportional valve. Specifically, because the second valve 132 is a three-way proportional valve, the resistance to the flow of the cooling medium through the second valve 132 is small. It can precisely adjust the opening and closing of the first inlet 1321, the second inlet 1322, and the first outlet 1323 according to different engine operating conditions. Furthermore, the three-way proportional valve is simple to operate and easy to maintain. When the second valve 132 malfunctions, it is easy to disassemble and replace.

[0060] Optionally, the first valve 131 includes a third inlet 1311, a fourth inlet 1312, and a second outlet 1313. The third inlet 1311 is connected to the first cooler 111, the fourth inlet 1312 is connected to the second cooler 112, and the second outlet 1313 is connected to the inlet 122 of the radiator 120. Specifically, since the third inlet 1311 is connected to the first cooler 111, the fourth inlet 1312 is connected to the second cooler 112, and the second outlet 1313 is connected to the inlet 122 of the radiator 120, when the engine temperature is low, the third inlet 1311 can be opened, the fourth inlet 1312 can be closed, and the second outlet 1313 can be opened. This eliminates the need to further reduce the engine temperature using low-pressure exhaust gas, thereby saving energy consumption in the engine cooling system 100. As the engine temperature rises, the fourth inlet 1312 is gradually opened to utilize low-pressure exhaust gas to reduce the engine temperature and increase engine power.

[0061] Optionally, the opening degrees of the third liquid inlet 1311 and the fourth liquid inlet 1312 can be adjusted separately. Specifically, since the opening degrees of the third liquid inlet 1311 and the fourth liquid inlet 1312 can be adjusted separately, the third liquid inlet 1311 and the fourth liquid inlet 1312 can be limited to only two states: open or closed. The opening degrees of the third liquid inlet 1311 and the fourth liquid inlet 1312 can be gradually adjusted according to different engine operating conditions, thereby meeting the requirements for engine temperature control under different engine speeds and operating conditions.

[0062] Optionally, the first valve 131 is a three-way proportional valve. Specifically, because the first valve 131 is a three-way proportional valve, the resistance of the cooling medium flowing through the first valve 131 is small. The opening and closing of the third inlet 1311, the fourth inlet 1312, and the second outlet 1313 can be precisely adjusted according to different engine operating conditions. Furthermore, the three-way proportional valve is simple to operate and easy to maintain. When the first valve 131 malfunctions, it is easy to disassemble and replace.

[0063] Optionally, the engine cooling system 100 also includes a water pump 140, with its inlet 141 connected to a first outlet 1323 and its outlet 142 connected to a first cooler 111 and a second cooler 112. Specifically, since the inlet 141 of the water pump 140 is connected to the first outlet 1323 and the outlet 142 is connected to the first cooler 111 and the second cooler 112, the cooling medium flowing through the first cooler 111, the second cooler 112, and the radiator 120 can flow to the water pump 140 and then back to the first cooler 111 and the second cooler 112, thus achieving circulation of the cooling medium and saving on the cost of the engine cooling system 100.

[0064] Optionally, the water pump 140 is a mechanical centrifugal water pump 140. Specifically, since the water pump 140 is a mechanical centrifugal water pump 140, it has a small size and a large water output, which can reduce the space waste of the engine cooling system 100, improve the efficiency of cooling medium circulation and transmission, thereby improving the efficiency of engine temperature reduction and better controlling the engine temperature under different operating conditions.

[0065] Optionally, the engine cooling system 100 also includes a controller. Both the first valve 131 and the second valve 132 are electrically connected to the controller, which controls the connection state of the first valve 131 and the second valve 132 respectively. Specifically, since both the first valve 131 and the second valve 132 are electrically connected to the controller, and the controller controls the connection state of the first valve 131 and the second valve 132 respectively, on the one hand, the first valve 131 and the second valve 132 can be controlled remotely without affecting their operation; on the other hand, intelligent opening and closing of the first valve 131 and the second valve 132 can be achieved, thereby precisely controlling the temperature of the EGR device according to different engine speeds and operating conditions.

[0066] The connection process of the engine cooling system 100 provided by the present invention is as follows: The engine cooling system 100 includes a cooling device 110, a radiator 120, and a valve device 130. The cooling device 110 includes a first cooler 111 and a second cooler 112. The first cooler 111 is configured to form an intercooler for the engine, and the second cooler 112 is configured to dissipate heat from the engine's EGR device. The radiator 120 has an outlet 121 for discharging cooling medium and an inlet 122 for allowing cooling medium to return.

[0067] The valve device 130 includes a first valve 131 and a second valve 132. The second valve 132 has a first inlet 1321, a second inlet 1322, and a first outlet 1323. The first inlet 1321 is connected to the inlet 122 of the radiator 120, the second inlet 1322 is connected between the first valve 131 and the inlet 122 of the radiator 120, and the first outlet 1323 connects to the first cooler 111 and the second cooler 112. The first valve 131 includes a third inlet 1311, a fourth inlet 1312, and a second outlet 1313. The third inlet 1311 is connected to the first cooler 111, the fourth inlet 1312 is connected to the second cooler 112, and the second outlet 1313 is connected to the inlet 122 of the radiator 120.

[0068] Specifically, the first cooler 111 and the second cooler 112 are both connected to the inlet 122 of the radiator 120 via the first valve 131. The first valve 131 adjusts the flow rate of the cooling medium flowing out of the first cooler 111 and the second cooler 112 respectively, so as to change the temperature of the boosted air and low-pressure exhaust gas entering the cylinder of the engine.

[0069] Since the flow rate of the cooling medium flowing out of the first cooler 111 and the second cooler 112 can be adjusted by the first valve 131, and the temperature of the boosted air and the low-pressure exhaust gas can be adjusted by the second valve 132, the temperature of the boosted air and the low-pressure exhaust gas entering the cylinder of the engine can be changed. This allows the engine to provide a lower exhaust gas temperature at low speeds, and further reduces the engine temperature by using the lower-temperature low-pressure exhaust gas, thereby increasing the engine's power and torque at low speeds.

[0070] The engine cooling system provided by this invention includes a cooling device, a radiator, and a valve device. The cooling device includes a first cooler and a second cooler. The first cooler is configured to form an intercooler for the engine, and the second cooler is configured to dissipate heat from the engine's EGR device. The radiator has an outlet for discharging cooling medium and an inlet for cooling medium recirculation. The valve device includes a first valve and a second valve. Both the first and second coolers are connected to the radiator inlet via the first valve. The first valve is used to regulate the flow rate of the cooling medium flowing out of the first and second coolers, respectively, to change the temperature of the pressurized air and low-pressure exhaust gas entering the engine cylinders. The second valve has a first inlet, a second inlet, and a first outlet. The first inlet is connected to the radiator inlet, the second inlet is connected between the first valve and the radiator inlet, and the first outlet connects to both the first and second coolers. The connection state of both the first and second inlets is adjustable to change the temperature of the cooling medium flowing out of the first valve. The engine cooling system provided by this invention can provide lower exhaust gas temperatures and improve engine power and torque at low speeds.

[0071] In the description of this invention, it should be understood that the terms "center," "length," "width," "thickness," "top," "bottom," "upper," "lower," "left," "right," "front," "rear," "vertical," "horizontal," "inner," "outer," "axial," and "circumferential," etc., used to indicate orientation or positional relationships are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the indicated position or component must have a specific orientation, or a specific structure and operation, and therefore should not be construed as a limitation of this invention.

[0072] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0073] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0074] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "setting," "connection," "fixing," "screw connection," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components or the interaction between two components. Unless otherwise explicitly limited, those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An engine cooling system, characterized in that, It includes a cooling device, a radiator, and a valve device. The cooling device includes a first cooler and a second cooler. The first cooler is configured to form an intercooler for the engine, and the second cooler is configured to dissipate heat from the engine's EGR device. The radiator has an outlet for the cooling medium to flow out and an inlet for the cooling medium to flow back. The valve device includes a first valve and a second valve. The first cooler and the second cooler are both connected to the inlet of the radiator via the first valve. The first valve is used to adjust the flow rate of the cooling medium flowing out of the first cooler and the second cooler respectively, so as to change the temperature of the boosted air and low-pressure exhaust gas entering the cylinder of the engine. The second valve has a first inlet, a second inlet, and a first outlet. The first inlet is connected to the inlet of the radiator, the second inlet is connected between the first valve and the inlet of the radiator, and the first outlet is connected to the first cooler and the second cooler. The connection state of the first inlet and the second inlet is adjustable to change the temperature of the cooling medium flowing out of the first valve. The first cooler and the second cooler are connected in parallel to the first outlet. The engine cooling system further includes a controller. Both the first valve and the second valve are electrically connected to the controller. The controller is used to dynamically adjust the opening of the first valve and the second valve according to the engine's operating conditions to achieve the distribution of cooling medium flow and precise temperature control. When the engine is idling, the first inlet is open and the second inlet is closed. When the engine is in a first operating condition, both the first inlet and the second inlet are open. When the engine is in a second operating condition, the first inlet is closed and the second inlet is open. The engine speed in the second operating condition is greater than the engine speed in the first operating condition, and the engine speed in the first operating condition is greater than the engine speed in the idling state. The first valve is a three-way proportional valve, used to independently adjust the flow ratio of the cooling medium in the first cooler and the second cooler.

2. The engine cooling system according to claim 1, characterized in that, The second valve is a three-way proportional valve.

3. The engine cooling system according to any one of claims 1-2, characterized in that, The first valve includes a third inlet, a fourth inlet, and a second outlet. The third inlet is connected to the first cooler, the fourth inlet is connected to the second cooler, and the second outlet is connected to the inlet of the radiator.

4. The engine cooling system according to claim 3, characterized in that, The opening degrees of the third liquid inlet and the fourth liquid inlet can be adjusted separately.

5. The engine cooling system according to claim 1, characterized in that, The engine cooling system also includes a water pump, the water pump's inlet end being connected to the first outlet, and the water pump's outlet end being connected to the first cooler and the second cooler.

6. The engine cooling system according to claim 5, characterized in that, The water pump is a mechanical centrifugal water pump.

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