An engine cooling system test method and system

Abstract

The application provides an engine cooling system test method and system, and belongs to the technical field of vehicle engine cooling systems. The method provided by the embodiment of the application short-circuits the outer circulation cooling pipeline in the engine cooling system, simulates the cold state of the engine, then controls the temperature of the cooling liquid to a target temperature, controls the water pump to operate at different speeds in multiple tests, thereby simulating the variable working condition of the engine, when the engine knocks, the engine is turned off and the outer circulation cooling pipeline is switched from short-circuiting to keeping flowing, test data and temperature in the whole process are recorded, a test working condition diagram under different speeds and a temperature-time relationship diagram are obtained, based on the two diagrams, cooling parameters are obtained, the cooling parameters include the switching temperature of the inner and outer circulation and the target flow of the cooling liquid, so that the engine can adjust the engine temperature through the cooling parameters under the variable working condition, and the combustion efficiency of the engine is improved.

Description

Technical Field

[0001] This application relates to the field of vehicle engine cooling system technology, and in particular to a test method and system for engine cooling systems. Background Technology

[0002] The vehicle engine is the core of a vehicle's power, and its temperature is a crucial factor affecting combustion efficiency. The engine cooling system is a vital component for regulating engine temperature. This system adjusts engine temperature by controlling cooling parameters, including the switching temperature between the internal and external cooling circulation and the cooling system flow rate at various engine speeds. Therefore, obtaining the cooling parameters of the engine cooling system and using them to regulate engine temperature and improve combustion efficiency during operation is a key research focus in this field.

[0003] Currently, existing technology, after fixing the engine under stable operating conditions, has confirmed the switching temperature between the internal and external circulation of the cooling system and the cooling system flow rate at various engine speeds through multiple tests.

[0004] However, the cooling parameters obtained under stable operating conditions can only reflect the cooling parameters of the cooling system when the engine is running continuously. In the actual operation of hybrid vehicles, the engine is not running continuously. Therefore, adjusting the engine temperature of hybrid vehicles using the cooling parameters obtained under stable operating conditions will result in lower engine combustion efficiency. Summary of the Invention

[0005] This application provides a test method and system for an engine cooling system, used to obtain the switching temperature between the internal and external circulation modes of the engine cooling system under varying operating conditions and the target cooling system flow rate at various engine speeds. This allows for the adjustment of engine temperature and improvement of engine combustion efficiency during engine operation by utilizing these cooling parameters. The technical solution is as follows:

[0006] On the one hand, a test method for an engine cooling system is provided, the method comprising:

[0007] Short-circuit the external circulation cooling pipes in the engine cooling system to maintain the flow of coolant in the internal circulation cooling pipes of the engine cooling system.

[0008] The water pump in the engine cooling system is controlled to run at different speeds during multiple tests to control the coolant temperature to reach the target temperature.

[0009] During each test, the engine is started and raised to the first operating condition within a first time period. Based on the first operating condition, the engine is raised to the second operating condition within a second time period. The first time period is shorter than the second time period.

[0010] Record the temperature of multiple temperature sensors in the engine at multiple first time points. The multiple first time points are time points within a first duration and a second duration. The multiple temperature sensors include a cylinder block temperature sensor, a cylinder head temperature sensor, and a coolant temperature sensor.

[0011] If engine knock is detected, the engine speed is reduced to zero, the external cooling pipe is connected to the internal cooling pipe, and the temperature of multiple temperature sensors in the engine is recorded at multiple second time points. These multiple second time points are the time points after the knock occurred.

[0012] Based on the recorded temperatures at multiple first and second time points, the switching temperatures between internal and external circulation at the corresponding rotation speeds during multiple experiments were obtained.

[0013] Based on the switching temperature of internal and external circulation at different speeds and the test data obtained from multiple tests, test condition diagrams and temperature-time relationship diagrams at different speeds were obtained. Based on the test condition diagrams and temperature-time relationship diagrams, the target flow rate of coolant in the engine cooling system was obtained.

[0014] In some embodiments, the switching temperature between internal and external circulation at a given engine speed is obtained based on temperatures recorded at multiple first and second time points in the engine, including:

[0015] At the same engine speed, the average temperature indicated by the coolant temperature sensor within the third time period before engine knock occurs is taken as the switching temperature between internal and external circulation at that engine speed.

[0016] In some embodiments, after any test is completed, the temperature of the coolant in the engine cooling system is detected by the coolant temperature sensor. If the temperature reaches the switching temperature between the internal and external circulation, the thermostat in the engine cooling system is automatically controlled to connect the external circulation cooling pipe to the internal circulation cooling pipe.

[0017] In some embodiments, the rotational speed in multiple tests decreases sequentially according to the magnitude of the target rotational speed.

[0018] In some embodiments, the target temperature of the coolant is between 25 and 30 degrees Celsius.

[0019] In some embodiments, the first duration is between 5 and 15 seconds.

[0020] In some embodiments, the target flow rate of the coolant in the engine cooling system is obtained based on the test condition diagram and the temperature-time relationship diagram, including:

[0021] Based on the temperature-time relationship graph, the temperature indicated by the cylinder head temperature sensor when engine knock occurs is taken as the limit temperature;

[0022] The cooling system flow rate corresponding to the temperature recorded by the cylinder head temperature sensor when it reaches the limit temperature is used as the target flow rate of coolant in the engine cooling system.

[0023] In some embodiments, the method further includes:

[0024] Temperature sensors are installed at high-temperature points in the engine, including cylinder block temperature sensors and cylinder head temperature sensors.

[0025] The high-temperature points include a first high-temperature point and a second high-temperature point. The first high-temperature point is located between the cylinders in the engine block and on the upper end face of the intake and exhaust sides of the cylinder block, for mounting the cylinder block temperature sensor. The second high-temperature point is located between the two exhaust ports of the combustion chamber in the engine cylinder head and on the upper end face of the intake and exhaust sides of the cylinder head, for mounting the cylinder head temperature sensor.

[0026] On the other hand, an engine cooling system test system is provided, which includes: an engine, an engine cooling system, and test equipment;

[0027] This testing equipment is used to achieve the following functions:

[0028] Short-circuit the external circulation cooling pipes in the engine cooling system to maintain the flow of coolant in the internal circulation cooling pipes of the engine cooling system.

[0029] The water pump in the engine cooling system is controlled to run at different speeds during multiple tests to control the coolant temperature to reach the target temperature.

[0030] During each test, the engine is started and raised to the first operating condition within a first time period. Based on the first operating condition, the engine is raised to the second operating condition within a second time period. The first time period is shorter than the second time period.

[0031] Record the temperature of multiple temperature sensors in the engine at multiple first time points. The multiple first time points are time points within a first duration and a second duration. The multiple temperature sensors include a cylinder block temperature sensor, a cylinder head temperature sensor, and a coolant temperature sensor.

[0032] If engine knock is detected, the engine speed is reduced to zero, the external cooling pipe is connected to the internal cooling pipe, and the temperature of multiple temperature sensors in the engine is recorded at multiple second time points. These multiple second time points are the time points after the knock occurred.

[0033] Based on the recorded temperatures at multiple first and second time points, the switching temperature between internal and external circulation at different rotation speeds during the experiment was obtained.

[0034] Based on the switching temperature of internal and external circulation at different speeds and the test data obtained from multiple tests, test condition diagrams and temperature-time relationship diagrams at different speeds were obtained. Based on the test condition diagrams and temperature-time relationship diagrams, the target flow rate of coolant in the engine cooling system was obtained.

[0035] In some embodiments, temperature sensors are installed at high-temperature points in the engine, including cylinder block temperature sensors and cylinder head temperature sensors.

[0036] The high-temperature points include a first high-temperature point and a second high-temperature point. The first high-temperature point is located between the cylinders in the engine block and on the upper end face of the intake and exhaust sides of the cylinder block, for mounting the cylinder block temperature sensor. The second high-temperature point is located between the two exhaust ports of the combustion chamber in the engine cylinder head and on the upper end face of the intake and exhaust sides of the cylinder head, for mounting the cylinder head temperature sensor. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a schematic diagram of the implementation environment of an engine cooling system test method provided in an embodiment of this application;

[0039] Figure 2 This is a flowchart of a test method for an engine cooling system according to an embodiment of this application;

[0040] Figure 3 This is a test condition diagram provided according to an embodiment of this application;

[0041] Figure 4 This is a temperature-time relationship graph provided according to an embodiment of this application. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0043] In this application, the terms "first," "second," etc., are used to distinguish identical or similar items with essentially the same function. It should be understood that there is no logical or temporal dependency between "first," "second," and "nth," nor are there any restrictions on quantity or execution order.

[0044] In this application, the term "at least one" means one or more, and "multiple" means two or more.

[0045] It should be noted that the information (including but not limited to user device information, user personal information, etc.), data (including but not limited to data used for analysis, data stored, data displayed, etc.) and signals involved in this application are all authorized by the user or fully authorized by all parties, and the collection, use and processing of related data must comply with the relevant laws, regulations and standards of the relevant countries and regions.

[0046] Figure 1 This is a schematic diagram illustrating the implementation environment of a test method for an engine cooling system according to an embodiment of this application. See also... Figure 1 The implementation environment includes engine 100, engine cooling system 101, and test equipment 102.

[0047] The engine includes an engine block 100A and an engine cylinder head 100B. The engine cooling system includes cooling pipes 101A, an engine block water jacket 101B, an engine cylinder head water jacket 101C, an external cooler 101D, a water pump 101E, and a large / small circulation control valve 101F. A coolant temperature sensor 101G is installed in the cooling pipes, which include an internal circulation cooling pipe and an external circulation cooling pipe. The large / small circulation control valve 101F and the water pump 101E are respectively installed at the two junctions of the internal and external circulation cooling pipes. The engine block water jacket 101B covers the outside of the engine block, and the engine cylinder head water jacket 101C covers the outside of the engine cylinder head. Both water jackets are connected to the internal circulation cooling pipe, and the external circulation cooling pipe is connected to the external cooler 101D.

[0048] During the test, coolant flows through the engine block water jacket 101B, engine cylinder head water jacket 101C, internal circulation cooling pipes, and external circulation cooling pipes. The engine block water jacket 101B is used to cool the engine block 100A, the engine cylinder head water jacket 101C is used to cool the engine cylinder head 100B, the internal circulation cooling pipes are used to flow coolant between the water pump 101E, the large and small circulation control valves 101F, and the engine 100, and the external circulation cooling pipes are used to flow coolant between the water pump 101E, the external cooler 101D, the large and small circulation control valves 101F, and the engine 100.

[0049] The external cooler 101D is equipped with a fan to cool the coolant when the coolant in the external circulation cooling pipe is overheated, thereby cooling the engine 100 when the coolant flows through the engine 100.

[0050] The water pump 101E is used to control the flow rate of the cooling system in the internal and external cooling pipes by changing its rotational speed. The water pump 101E can be an external electric water pump or an external mechanical water pump connected to the engine; this embodiment does not limit the specific type.

[0051] The internal circulation cooling pipe is equipped with a temperature sensor, which is used to detect the temperature of the coolant in the cooling system. Based on this temperature, the large and small circulation control valves 101F can be opened and closed to switch the internal and external circulation of the engine 100.

[0052] The testing device 102 is used to set parameters to control the water pump 101E to change its speed and to control the opening and closing of the large and small circulation control valves 101F. The testing device 102 is also used to control the engine 100 to change its engine speed and to record the operating data of the engine 100. The testing device 102 is also used to record the temperature detected by the coolant temperature sensor 101G in the engine 100 and the engine cooling system 101, and to obtain the corresponding relationship graph based on the temperature and operating data.

[0053] Those skilled in the art will understand that the number of the aforementioned water pump, large and small circulation control valves, and coolant temperature sensors can be more or less. For example, there may be only one water pump, large and small circulation control valve, and coolant temperature sensor, or there may be a dozen or more. This application does not limit the number of water pumps, large and small circulation control valves, and coolant temperature sensors.

[0054] Figure 2 This is a flowchart of a test method for an engine cooling system according to an embodiment of this application, such as... Figure 2 As shown, this embodiment of the application uses a test device as an example for explanation. The test method for the engine cooling system includes the following steps 201-207.

[0055] 201. The test equipment short-circuits the external circulation cooling pipes in the engine cooling system while maintaining the flow of coolant in the internal circulation cooling pipes of the engine cooling system.

[0056] The operation of short-circuiting the external circulation cooling pipes in the engine cooling system is achieved by the test equipment controlling the large and small circulation control valves. These valves include a paraffin wax core, a center rod, a main valve, and a bypass valve. The main valve controls the flow rate of coolant in the cooling pipes during external circulation, while the bypass valve controls the flow rate of coolant in the cooling pipes during internal circulation.

[0057] When the engine cooling system is in internal circulation mode, the main valve is closed and the bypass valve is open. At this time, the external circulation cooling pipe is short-circuited, and the coolant in the internal circulation cooling pipe remains in circulation. When the engine cooling system is in external circulation mode, the main valve is open and the bypass valve is closed. At this time, the internal circulation cooling pipe is short-circuited, and the coolant in the external circulation cooling pipe remains in circulation.

[0058] In some embodiments, the process of controlling the opening and closing of the large and small circulation control valves to achieve internal circulation of the engine cooling system includes: when the engine is initially started, the main valve is closed and the bypass valve is fully opened. The coolant flowing out of the engine cylinder head does not flow through the external cooler but directly enters the water pump through the bypass valve. At this time, the external circulation cooling pipes in the cooling system are short-circuited, while the internal circulation cooling pipes remain open. Since the coolant only flows between the engine water jacket and the water pump and does not flow through the external cooler, and the coolant flow rate is relatively small, the cooling effect is weak, and the engine cools down slowly.

[0059] In some embodiments, the process of controlling the opening and closing of the large and small circulation control valves to realize the external circulation of the engine cooling system includes: after the engine has been running for a period of time, the coolant temperature rises, and the paraffin wax, which is solid at room temperature, becomes liquid and covers the area around the center rod, causing the paraffin wax to increase in volume. This increased volume of paraffin wax generates an upward thrust on the lower conical surface of the center rod. Since the center rod is fixed, it generates a downward counter-thrust on the rubber tube containing the paraffin wax, causing the main valve to gradually open and the bypass valve opening to gradually decrease. The coolant flowing out of the engine cylinder head enters the external cooler through the main valve and then enters the water pump through the bypass valve. When the main valve is fully open and the bypass valve is fully closed, all the coolant flowing out of the engine cylinder head enters the external cooler through the main valve. At this time, the external circulation cooling pipes in the cooling system remain open, while the internal circulation cooling pipes are short-circuited. Because the coolant flows between the engine water jacket, water pump, and external cooler, the coolant flow rate is large, the cooling force is strong, and the engine cools down quickly.

[0060] In this embodiment, the operation of initially maintaining the internal circulation cooling pipes in the engine cooling system simulates the state of the engine cooling system during the engine cold start phase. At this time, the cooling system minimizes the flow of external coolant to reduce heat loss and achieve a rapid temperature rise.

[0061] In some embodiments, before conducting the test methods of the present application, it is necessary to install temperature sensors at the high-temperature points of the engine, including cylinder block temperature sensors and cylinder head temperature sensors.

[0062] The engine features two high-temperature points: a first high-temperature point and a second high-temperature point. The first high-temperature point is located between the cylinders in the engine block, and on the upper surfaces of the intake and exhaust sides of the cylinder block, for mounting a cylinder block temperature sensor. The second high-temperature point is located between the two exhaust ports in the combustion chamber of the engine cylinder head, and on the upper surfaces of the intake and exhaust sides of the cylinder head, for mounting a cylinder head temperature sensor. The installation process for the temperature sensor includes: pre-machining sensor mounting holes at these high-temperature points, followed by installation; and then filling the gap between the temperature sensor and the metal using an industrial repair compound. This gap-filling operation prevents reduced temperature accuracy due to gaps between the temperature sensor and the mounting holes.

[0063] The high-temperature point in the engine is the highest temperature that may occur in the engine. Since the combustion chamber and the cylinder in the engine block are the main places where the engine does power during operation, they generate heat energy accordingly, and are therefore considered high-temperature points.

[0064] In some embodiments, after installing the temperature sensor at the high-temperature point of the engine, the test equipment needs to be arranged, such as... Figure 1 As shown, connect the engine, water pump, large and small circulation control valves, cooling pipes, and external cooler.

[0065] 202. The test equipment controls the water pump in the engine cooling system to run at different speeds during multiple tests to control the coolant temperature to reach the target temperature.

[0066] Since a slower water pump speed results in a smaller cooling system flow rate, which in turn reduces the cooling effect on the engine and causes it to heat up faster, and rapid temperature rise is key to fuel economy, the speeds in multiple tests were progressively reduced from the target speed to explore the cooling system flow rate that can achieve the fastest engine temperature rise while ensuring engine reliability. For example, in the first test, the water pump speed was 2500 r / min, and the target speed was set at 500 r / min. In the second test, the water pump speed was 2000 r / min.

[0067] The water pump controls the flow rate of the cooling system in both the internal and external circulation cooling pipes by changing its rotational speed. The faster the pump rotates, the greater the flow rate of the cooling system. In some embodiments, the pump pulley drives the pump bearing and impeller to rotate, causing the coolant in the pump to rotate along with the impeller. Under the action of centrifugal force, the coolant is thrown towards the edge of the pump casing and then flows out from the outlet or water pipe.

[0068] The target temperature determines the engine restart condition for each test; that is, the starting temperature is the same for each test, ensuring the consistency of the test. After each test, the engine is restarted only after the coolant temperature in the cooling system drops to the target temperature, ensuring the continuity of the test.

[0069] In some embodiments, the coolant temperature is maintained at room temperature when the engine is not running, which is between 25 and 30 degrees Celsius. Therefore, the target temperature of the coolant is set between 25 and 30 degrees Celsius, for example, 26 degrees Celsius. This target temperature simulates the temperature during a cold start of the engine, which is closer to reality. Furthermore, using room temperature as the target temperature makes the test easier to operate, requiring no other adjustments; the coolant can simply be brought back to room temperature for the next test.

[0070] 203. During each test, the test equipment starts the engine and raises it to the first operating condition within a first time period. Based on the first operating condition, the engine is raised to the second operating condition within a second time period. The first time period is shorter than the second time period.

[0071] In some embodiments, the first duration is between 5 and 15 seconds, for example, 10 seconds. The first operating condition is a preset target operating condition, including the engine target speed and load. Increasing the engine to the first operating condition within the first duration simulates the actual situation of the engine starting and quickly reaching the target speed and load. By observing the test data of the engine under this first operating condition, the working state of the engine when starting and quickly reaching the target speed and load can be understood. The second operating condition simulates the operating condition of the engine when it tends to stabilize. By observing the test data of the engine under this second operating condition, the actual working state of the engine when it tends to stabilize can be understood. This working state includes changes in engine wall temperature and fuel consumption, etc. The engine wall temperature includes the engine block wall temperature and the engine cylinder head wall temperature.

[0072] The process of transitioning from the first operating condition to the second operating condition is used to simulate the changing operating conditions during actual engine operation, that is, changes in engine load and speed.

[0073] In some embodiments, the engine of a range-extended electric vehicle (REEV) may face variable operating conditions. The REEV is a hybrid electric vehicle that uses both an engine and an electric motor to drive. In actual operation, the engine of the REEV does not work continuously. Under certain circumstances, the operating conditions may change. For example, when the electric motor drives the vehicle, the engine used for power generation is not working and is in a stopped state. When the electric motor is low on power, the engine needs to quickly reach its optimal fuel consumption operating point from the stopped state to generate electricity so that the electric motor can drive the vehicle.

[0074] In some embodiments, variable operating conditions play an important role in engine operation, so it is more practical to explore the engine's operating state under variable operating conditions.

[0075] 204. The test equipment records the temperature of multiple temperature sensors in the engine at multiple first time points. These multiple first time points are time points within a first duration and a second duration. The multiple temperature sensors include a cylinder block temperature sensor, a cylinder head temperature sensor, and a coolant temperature sensor.

[0076] The cylinder block temperature sensor is used to detect the wall temperature of the engine cylinder block, the cylinder head temperature sensor is used to detect the wall temperature of the engine cylinder head, and the coolant temperature sensor is used to detect the outlet water temperature of the water pump in the engine cooling system.

[0077] In some embodiments, by recording the temperatures of the plurality of temperature sensors at the plurality of first time points, it is possible to obtain the temperature changes of the engine block, engine cylinder head, and coolant over time, thereby understanding the cooling effect of the engine cooling system under varying operating conditions, and further improving the cooling parameters of the cooling system during actual engine operation.

[0078] Each experiment will yield the temperature at a certain first time point. Multiple experiments will yield multiple temperatures at a certain first time point. The recorded temperature is the average temperature at a certain first time point obtained after multiple experiments.

[0079] In some embodiments, the temperatures at the plurality of first time points are the average temperatures indicated by the same type of temperature sensor. For example, if there are two cylinder block temperature sensors in the engine block, and the temperatures indicated by the two cylinder block temperature sensors at the first time point of 30 seconds are 150 degrees and 152 degrees respectively, then the cylinder block temperature at the first time point of 30 seconds will be recorded as 151 degrees.

[0080] 205. If engine knock is detected, the test equipment controls the engine speed to drop to zero, connects the external circulation cooling pipe to the internal circulation cooling pipe, and records the temperature of multiple temperature sensors in the engine at multiple second time points. These multiple second time points are the time points after the knock occurred.

[0081] Knocking refers to a sudden, non-prolonged, continuous vibration caused by excessively high engine temperature. When the engine wall temperature exceeds the knock limit, knocking occurs because the coolant temperature in the cooling system is insufficient to maintain a stable engine temperature. Therefore, the engine is shut down, and the external and internal cooling systems are connected, allowing the coolant to flow through an external cooler to enhance cooling and achieve temperature reduction.

[0082] The large and small circulation control valves that connect the external circulation cooling pipes and the internal circulation cooling pipes include mechanical valves and electronic valves. The mechanical valves do not require preset parameters and can open and close the valves according to temperature changes. The electronic valves can be preset to switch the internal and external circulation temperatures. In this embodiment, after any test is completed, the temperature of the coolant in the engine cooling system is detected by the coolant temperature sensor. If the temperature reaches the switching temperature between the internal and external circulation, the large and small circulation control valves in the engine cooling system are automatically controlled to connect the external circulation cooling pipes and the internal circulation cooling pipes.

[0083] In some embodiments, the conditions for shutting down the engine and connecting the external cooling line to the internal cooling line can also be other extreme conditions, such as when the engine wall temperature exceeds the acceptable temperature of the metal or the coolant temperature exceeds 100 degrees.

[0084] By recording temperatures at multiple second time points using these multiple temperature sensors, it is possible to investigate the engine's cooling status after the engine is shut down and the external cooling line is connected to the internal cooling line.

[0085] 206. Based on the recorded temperatures at multiple first and second time points, the testing equipment obtains the switching temperature between internal and external circulation at different rotation speeds during the test.

[0086] The switching temperature between internal and external circulation refers to the coolant temperature indicated by the coolant temperature sensor when the engine cooling system switches from external circulation to internal circulation or vice versa. In other words, it is the temperature of the coolant in the engine cooling system.

[0087] In some embodiments, since the pump speed is different in each test, the test data obtained in each test is different, and each pump speed corresponds to a switching temperature between internal and external circulation.

[0088] In some embodiments, obtaining the switching temperature between internal and external circulation at the specified speed during the test includes: at the same speed, taking the average temperature indicated by the coolant temperature sensor within a third time period before engine knock as the switching temperature between internal and external circulation at that speed.

[0089] The third duration is 5 to 10 seconds. During this third duration, the temperature of the coolant temperature sensor tends to be stable and is closest to the moment when the engine knocks. Therefore, the average temperature indicated during the third duration is more accurate and practically meaningful as the switching temperature between the internal and external circulation at that speed.

[0090] 207. Based on the switching temperature of internal and external circulation at different speeds and the test data obtained from multiple tests, the test equipment obtained test condition diagrams and temperature-time relationship diagrams at different speeds. Based on the test condition diagrams and temperature-time relationship diagrams, the target flow rate of coolant in the engine cooling system was obtained.

[0091] The test condition diagram is used to indicate the test condition data that changes over time during each test, for reference. Figure 3 , Figure 3 This is a test condition diagram provided according to an embodiment of this application, such as... Figure 3 As shown, the horizontal axis represents time, the left vertical axis represents the cooling system flow rate, and the right vertical axis represents the engine speed. The figure shows that the engine speed increased from 0 to 2000 r / min in 10 seconds, and then increased to 5000 r / min from 2000 r / min, before decreasing to 0.

[0092] The temperature-time graph indicates the changes in engine block temperature, cylinder head temperature, and coolant temperature over time during each test. Figure 4 , Figure 4 This is a temperature-time relationship graph provided according to an embodiment of this application, such as... Figure 4 As shown, the horizontal axis represents time and the vertical axis represents temperature. Since the flow rate of the cooling system is different in each test, the corresponding temperature-time relationship graph is different.

[0093] In some embodiments, the target flow rate in the engine cooling system is the target cooling system flow rate at a certain engine speed. This target cooling system flow rate can enable the engine to reach its limit conditions as quickly as possible at that engine speed while ensuring engine reliability. Compared with other cooling system flow rates at that engine speed, it saves time and fuel costs, thereby improving fuel efficiency.

[0094] In some embodiments, the process of obtaining the target flow rate of coolant in the engine cooling system includes the following steps 207A and 207B:

[0095] 207A: Based on the temperature-time relationship graph, the temperature indicated by the cylinder head temperature sensor when engine knock occurs is taken as the limit temperature.

[0096] Here, the extreme temperature is a benchmark. At the same engine speed, the cooling system flow rate that enables the cylinder head temperature sensor to reach this extreme temperature is the target cooling system flow rate.

[0097] In some embodiments, the temperature indicated by the cylinder block temperature sensor when engine knock occurs can also be used as the limit temperature, but this application does not limit this.

[0098] 207B: The cooling system flow rate corresponding to the temperature recorded by the cylinder head temperature sensor when it reaches the limit temperature is used as the target flow rate of coolant in the engine cooling system.

[0099] In some embodiments, each test condition graph corresponds to a temperature-time relationship graph, and the test condition graph and the time in the temperature-time relationship graph correspond one-to-one. Among these multiple test condition graphs, the engine speed at the same time is the same. Therefore, at the same engine speed, each test condition graph has a cylinder head temperature in the temperature-time relationship graph, that is, there are multiple cylinder head temperatures at the same engine speed. Each cylinder head temperature corresponds to a water pump speed, and each water pump speed corresponds to a cooling system flow rate. Therefore, the cooling system flow rate corresponding to the cylinder head temperature at the limit temperature is taken as the target flow rate of coolant in the engine cooling system.

[0100] The method provided in this application involves short-circuiting the external circulation cooling pipe in the engine cooling system to simulate a cold engine state. The coolant temperature is then controlled to a target temperature. The water pump in the engine cooling system is controlled to operate at different speeds during multiple tests, simulating varying engine operating conditions. When engine knock occurs, the engine is shut off, and the external circulation cooling pipe is switched from short-circuited to continuous flow. Test data and temperatures are recorded throughout the process, resulting in test condition diagrams at different speeds and temperature-time relationship diagrams. Based on these diagrams, cooling parameters are obtained, including the switching temperature between internal and external circulation and the target coolant flow rate. This allows the engine to adjust its temperature under varying operating conditions, thereby improving combustion efficiency.

[0101] The above are merely optional embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A test method for an engine cooling system, characterized in that, include: Short-circuit the external circulation cooling pipes in the engine cooling system to maintain the flow of coolant in the internal circulation cooling pipes of the engine cooling system. The water pump in the engine cooling system is controlled to run at different speeds during multiple tests to control the coolant temperature to reach the target temperature. During each test, the engine is started and raised to the first operating condition within a first time period. Based on the first operating condition, the engine is raised to the second operating condition within a second time period. The first time period is shorter than the second time period. Record the temperature of multiple temperature sensors in the engine at multiple first time points. The multiple first time points are time points within a first duration and a second duration. The multiple temperature sensors include a cylinder block temperature sensor, a cylinder head temperature sensor, and a coolant temperature sensor. If engine knock is detected, the engine speed is reduced to zero, the external cooling pipe is connected to the internal cooling pipe, and the temperature of the multiple temperature sensors at multiple second time points is recorded. The multiple second time points are the time points after the knock occurred. Based on the recorded temperatures at multiple first and second time points, the switching temperature between internal and external circulation at the corresponding rotation speed during the multiple tests was obtained. Based on the switching temperature of the internal and external circulation at different speeds and the test data obtained from the multiple test processes, test condition diagrams and temperature-time relationship diagrams at different speeds are obtained. Based on the test condition diagrams and the temperature-time relationship diagrams, the target flow rate of the coolant is obtained.

2. The method according to claim 1, characterized in that, The temperature at which the internal and external circulations switch at the corresponding rotational speeds is obtained based on the recorded temperatures at multiple first and second time points during the multiple tests includes: At the same engine speed, the average temperature indicated by the coolant temperature sensor during the third time period before engine knock occurs is taken as the switching temperature between internal and external circulation at that engine speed.

3. The method according to claim 1, characterized in that, After any test is completed, the temperature of the coolant in the engine cooling system is detected by the coolant temperature sensor. If the temperature reaches the switching temperature between the internal and external circulation, the internal and external circulation control valve in the engine cooling system is automatically controlled to connect the external circulation cooling pipe to the internal circulation cooling pipe.

4. The method according to claim 1, characterized in that, In the multiple tests, the rotational speed was decreased sequentially according to the target rotational speed.

5. The method according to claim 1, characterized in that, The target temperature of the coolant is between 25 and 30 degrees Celsius.

6. The method according to claim 1, characterized in that, The first duration is between 5 and 15 seconds.

7. The method according to claim 1, characterized in that, The step of obtaining the target flow rate of the coolant based on the test condition diagram and the temperature-time relationship diagram includes: Based on the temperature-time relationship graph, the temperature indicated by the cylinder head temperature sensor when the engine knocks is taken as the limit temperature. The cooling system flow rate corresponding to the temperature recorded by the cylinder head temperature sensor when it reaches the limit temperature is used as the target flow rate of the coolant in the engine cooling system.

8. The method according to claim 1, characterized in that, The engine is equipped with cylinder block temperature sensors and cylinder head temperature sensors at high-temperature points. The high-temperature point includes a first high-temperature point and a second high-temperature point. The first high-temperature point includes the position between the cylinders in the engine block and the upper end face of the cylinder block's intake and exhaust sides, for mounting the cylinder block temperature sensor. The second high-temperature point includes the position between the two exhaust holes in the combustion chamber of the engine cylinder head and the upper end face of the cylinder head's intake and exhaust sides, for mounting the cylinder head temperature sensor.

9. An engine cooling system testing system, characterized in that, The engine cooling system test system includes: an engine, an engine cooling system, and test equipment; The testing equipment is used to perform the following functions: Short-circuit the external circulation cooling pipes in the engine cooling system to maintain the flow of coolant in the internal circulation cooling pipes of the engine cooling system. The water pump in the engine cooling system is controlled to run at different speeds during multiple tests to control the coolant temperature to reach the target temperature. During each test, the engine is started and raised to the first operating condition within a first time period. Based on the first operating condition, the engine is raised to the second operating condition within a second time period. The first time period is shorter than the second time period. Record the temperature of multiple temperature sensors in the engine at multiple first time points. The multiple first time points are time points within a first duration and a second duration. The multiple temperature sensors include a cylinder block temperature sensor, a cylinder head temperature sensor, and a coolant temperature sensor. If engine knock is detected, the engine speed is reduced to zero, the external cooling pipe is connected to the internal cooling pipe, and the temperature of the multiple temperature sensors at multiple second time points is recorded. The multiple second time points are the time points after the knock occurred. Based on the recorded temperatures at multiple first and second time points, the switching temperature between internal and external circulation at the corresponding rotation speed during the multiple tests was obtained. Based on the switching temperature of the internal and external circulation at different speeds and the test data obtained from the multiple test processes, test condition diagrams and temperature-time relationship diagrams at different speeds are obtained. Based on the test condition diagrams and the temperature-time relationship diagrams, the target flow rate of the coolant is obtained.

10. The engine cooling system test system according to claim 9, characterized in that, The engine is equipped with cylinder block temperature sensors and cylinder head temperature sensors at high-temperature points. The high-temperature point includes a first high-temperature point and a second high-temperature point. The first high-temperature point includes the position between the cylinders in the engine block and the upper end face of the cylinder block's intake and exhaust sides, for mounting the cylinder block temperature sensor. The second high-temperature point includes the position between the two exhaust holes in the combustion chamber of the engine cylinder head and the upper end face of the cylinder head's intake and exhaust sides, for mounting the cylinder head temperature sensor.

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