Engine cold starting device and method based on air inlet heating system

Abstract

The invention discloses an engine cold starting method based on an air inlet heating system, and relates to the engine cold starting technology, an air loop system is constructed among a throttle valve, a preheating grille and an air inlet manifold, a target heating temperature is set, and before engine cold starting, the real-time air quality in the air loop system is obtained; heating time is calculated according to the target heating temperature and the real-time air quality, and whether the heating time exceeds an expected value or not is judged according to the heating time; if the heating time does not exceed the expected value, after the air in the air loop system reaches the target heating temperature, an engine starting program is executed; and if the heating time exceeds the expected value, balancing the amount of air in the air loop system and the transition duration of operation after the idle speed of the engine is stable. The invention further discloses an engine cold starting device based on the air inlet heating system. The air heating efficiency of the preheating grille is improved, and the cold start reliability of the engine is improved.

Description

Technical Field

[0001] The invention relates to an engine cold start technology, and more particularly to an engine cold start device and method based on an intake air heating system. Background Art

[0002] There are several reasons why the engine is difficult to start at low temperatures:

[0003] First, due to the low air temperature, the atomization and evaporation of the fuel is poor, and the engine is difficult to ignite;

[0004] Second, at low temperatures, the viscosity of the engine oil is low, and the resistance torque that the engine needs to overcome at the moment of starting is large. The starter (electric motor) drags the engine to rotate, usually only to a very low speed (20% of the idle speed), and then the engine starts to ignite, and the work done by combustion overcomes the resistance torque to continuously increase the speed and enter the idle speed. If the engine combustion is not good at this time and fails to overcome the resistance torque to enter the idle speed, the speed will drop under the action of the resistance torque, which will lead to flameout and shutdown.

[0005] like Figure 1 The figure shows the waveform of the engine speed change during the starting process.

[0006] Therefore, in order to solve the cold start problem of the engine, the measures currently usually taken are:

[0007] First, use an air intake grille. After the air intake preheating grille is preheated, a warm air mass is formed around the grille. The starter drags the engine to the starting speed, and the engine can ignite normally after the warm air enters the cylinder. The warm air mass ensures the normal operation of the engine, overcomes the resistance torque and continuously increases the speed to the idle speed. After the engine enters the idle speed, due to the relatively high speed, the pressure and temperature of the compression stroke are also high, which is conducive to the normal operation of the engine. This method is often used in extremely cold areas with temperatures ranging from -40℃ to -20℃. The current problem with this measure is that since the grille can only heat a small group of air near it to become a warm air mass, the warm air mass is quickly consumed after the engine is started. If the engine fails to overcome the resistance and reach the idle speed at this time, under the action of the cold air, the engine combustion deteriorates, and the speed will continue to drop until it stops.

[0008] Second, a boiler is used to heat the engine cooling water and lubricating oil. This technology effectively increases the temperature of the lubricating oil, reduces the viscosity of the lubricating oil, and thus reduces the friction torque of the engine. At the same time, by increasing the temperature of the cooling water, the temperature of the cylinder wall is also increased, which helps to reduce the heat dissipation loss to the cylinder wall during engine combustion, thereby optimizing the combustion efficiency and power output of the engine. Both improvements have helped the engine reach idle speed faster. This method is usually used in conjunction with an intake preheating grille and is suitable for cold starts of engines in extremely cold areas (below -40°C). At present, the challenges faced by this measure mainly come from the complexity of the system and the length of its start-up time, which is usually between 15 minutes and half an hour. In addition, in extremely cold areas, since most vehicles are parked in garages with relatively high temperatures, this measure is relatively less used.

[0009] According to the current method, the commonly used solution is the air intake grille heating method, and the overall layout is as follows: Figure 2 As shown. Its working process is, at low temperature, first open the preheating grille, preheat for 0-60s (time is determined by the ambient temperature), and form a warm air mass near the preheating grille. Start the engine, the warm air mass enters the cylinder, and after reaching the starting speed, it starts to spray and ignite. The engine starts to work, overcomes the resistance torque, and the speed increases to the idle speed. The warm air mass is quickly consumed by the engine, and the engine intake temperature is significantly reduced (such as Figure 3 The preheating grid continues to preheat for 0-120s (the time is determined by the ambient temperature). At this time, the intake air temperature is still very low. The grid heating can only slightly increase the intake air temperature, slightly improve the engine combustion state, and make the engine run stably at idle speed.

[0010] However, during the preheating stage, due to the stagnation of air in the intake duct, a high-temperature air mass is formed near the preheating grille. The continuous heating of the preheating grille causes the temperature of the heating plate to rise to usually over 800°C, triggering the thermal protection mechanism, thereby limiting the heating power of the preheating grille, so that the temperature of the high-temperature air mass no longer continues to rise. In addition, long-term high-temperature operation will significantly shorten the service life of the grille, resulting in frequent preheating grille failures in the market. Due to the limited amount of heated air, only a small mass of warm air can be formed for engine starting. Once the engine is started, before reaching a stable operating state, this mass of warm air is exhausted, and the intake temperature immediately drops back to a low temperature, causing the engine combustion condition to deteriorate, and even misfire shutdown may occur. Therefore, in cold areas, the engine may need to be started repeatedly 2 to 3 times before it can reach the idle speed and enter normal working state. .

[0011] Therefore, the key issues that need to be urgently addressed include the following three points: 1) During the preheating stage before starting, due to stagnation of air flow, a high-temperature air mass is formed near the preheating grille, which leads to low heating efficiency of the preheating grille and the thermal protection mechanism limits the increase in heating power; 2) The reliability risk of the grille heating plate increases significantly under long-term high-temperature operation conditions; 3) Since only a small part of the warm air is used for engine starting, once the engine is started, this part of the warm air is usually exhausted before reaching a stable idle state, and the intake temperature quickly drops to a low temperature level, which causes the engine combustion performance to decline and there is a risk of misfire and shutdown. Summary of the invention

[0012] The technical problem to be solved by the present invention is to provide an engine cold start device and method based on an intake air heating system in view of the deficiencies in the prior art, thereby achieving a cold start of the engine.

[0013] The present invention discloses an engine cold start method based on an intake air heating system, which constructs an air circuit system between a throttle, a preheating grille and an intake manifold, sets a target heating temperature, obtains the real-time air mass in the air circuit system before the engine is cold started, calculates the heating time according to the target heating temperature and the real-time air mass, and determines whether the heating time exceeds an expected value according to the heating time; if the heating time does not exceed the expected value, the engine start procedure is executed after the air in the air circuit system reaches the target heating temperature; if the heating time exceeds the expected value, the amount of air in the air circuit system and the transition time of the engine running after the idle speed is stabilized are balanced.

[0014] Preferably, the heating time is calculated as follows:

[0015]

[0016] Where t is the heating time; m is the real-time air quality in the air circuit system; C V is the constant volume specific heat capacity of air; T Target is the target heating temperature; T Env is the ambient temperature; P haet is the heating power of the preheating grille; η is the heating efficiency of the air circuit system.

[0017] Preferably, the target heating temperature is 0-5°C.

[0018] Preferably, the balancing process is specifically:

[0019] The real-time air quality is adjusted according to the expected value so that the heating time is equal to the expected value; based on the adjusted air quality and the engine's air intake volume, it is judged whether the adjusted air quality can maintain the minimum transition time after the engine idle speed is stabilized; if it cannot be maintained, a time step is added to the heating time with a set heating time step, and the heating time after the increase of the time step is used as the heating target time, and it is re-judged whether the air quality corresponding to the heating target time can meet the minimum transition time after the engine idle speed is stabilized; if not, the quality of the air in the air circuit system is increased so that the air quality in the air circuit system can meet the minimum transition time after the engine idle speed is stabilized.

[0020] Preferably, the transition duration ranges from 20 to 30 seconds.

[0021] An engine cold start device based on an intake air heating system comprises a throttle, a preheating grille, an intake manifold and an ECU; a pressure-stabilizing air storage tank is provided between the throttle and the preheating grille, a return line is provided between the intake manifold and the connection between the throttle and the pressure-stabilizing air storage tank, and an air pump is installed in the return line; the ECU applies the engine cold start method based on the intake air heating system to control the throttle, the preheating grille and the air pump to work.

[0022] Preferably, a one-way valve and a solenoid valve are installed in the return line.

[0023] Preferably, a solenoid valve is installed in the pipeline between the pressure-stabilizing gas storage tank and the preheating grid.

[0024] Beneficial Effects

[0025] The advantages of the present invention are:

[0026] 1. Construct a closed air circuit system and rationally utilize existing engine components to allow air to circulate through the preheating grille for heating. This not only requires fewer overall changes, but also improves the heating efficiency of the preheating grille for air and improves the reliability of engine cold start.

[0027] 2. The pressure-stabilizing air tank is used to store air, which can ensure that the engine runs stably for a short period of time after starting, avoiding the problem of insufficient warm air after the engine starts, causing it to not run completely stably and encounter cold air and stall. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a waveform diagram of the speed change during the engine starting process;

[0029] Figure 2 It is a schematic diagram of the structure of a traditional engine cold start device;

[0030] Figure 3 It is a parameter waveform diagram of the traditional engine cold start process;

[0031] Figure 4 It is a schematic structural diagram of the engine cold starting device of the present invention. DETAILED DESCRIPTION

[0032] The present invention will be further described below in conjunction with the embodiments, but it does not constitute any limitation to the present invention. Any limited number of modifications made by anyone within the scope of the claims of the present invention are still within the scope of the claims of the present invention.

[0033] The present invention provides an engine cold start method based on an intake air heating system. An air circuit system is constructed between the throttle, the preheating grille and the intake manifold. The target heating temperature is set. Before the engine is cold started, the real-time air quality in the air circuit system is obtained. The heating time is calculated based on the target heating temperature and the real-time air quality. The heating time is mainly used to control the heating time of the air in the air circuit system to avoid it being too long and affecting the normal use of the vehicle.

[0034] Specifically, the calculation method of heating time is:

[0035]

[0036] Where t is the heating time; m is the real-time air quality in the air circuit system; C V is the constant volume specific heat capacity of air; T Target is the target heating temperature, wherein the target heating temperature is 0-5°C. Generally speaking, the engine can be started when the target heating temperature reaches 0°C; T Env is the ambient temperature; P haet is the heating power of the preheating grille; η is the heating efficiency of the air circuit system.

[0037] After the heating time is calculated, it is determined whether it exceeds the expected value. If the heating time does not exceed the expected value, the engine start procedure is executed after the air in the air circuit system reaches the target heating temperature. If the heating time exceeds the expected value, the amount of air in the air circuit system and the transition time of the engine running after the idle speed stabilizes are balanced to ensure the balance of various condition parameters during the engine cold start process.

[0038] In this embodiment, the equalization process is specifically as follows:

[0039] The real-time air quality is adjusted according to the expected value so that the heating time is equal to the expected value. After the adjustment, the air quality in the system is less than that before the adjustment. According to the adjusted air quality and the intake volume of the engine, it is judged whether the adjusted air quality can maintain the minimum transition time after the engine idle speed stabilizes. Among them, regarding the transition time, the range is set in 20-30s. That is, if the amount of adjusted air is not enough to maintain the engine idle speed for 20s after stabilization, it is judged that the amount of air in the system is too low, and the number of times is to increase the heating time by one time step by the set heating time step, and the heating time after the increase of the time step is used as the heating target time, and re-judge whether the air quality corresponding to the heating target time can meet the minimum transition time after the engine idle speed stabilizes. After adding a time step on the basis of the original heating time, according to the above formula, the air quality in the system also increases. If at this time the minimum transition time after the engine idle speed stabilizes still cannot be met, the mass of the air in the air circuit system will be increased so that the air mass in the air circuit system can meet the minimum transition time after the engine idle speed stabilizes. In this way, the balance of various parameters is achieved while satisfying the conditions of heating the air in the system and stable operation of the engine after cold start, thereby ensuring the starting time of the entire vehicle and avoiding the problem of excessive starting time.

[0040] See also Figure 4 , an engine cold start device based on an intake air heating system, comprising a throttle, a preheating grille, an intake manifold and an ECU. A pressure-stabilizing air tank is provided between the throttle and the preheating grille, and the function of the pressure-stabilizing air tank is to store enough air to facilitate the engine to run stably for a short period of time during cold start and cold start, that is, the transition period. A return line is provided between the intake manifold and the connection between the throttle and the pressure-stabilizing air tank, and an air pump is installed in the return line. The ECU applies the above-mentioned engine cold start method based on the intake air heating system to control the throttle, the preheating grille and the air pump to work. In addition, a one-way valve and a solenoid valve are installed in the return line. A solenoid valve is installed in the pipeline between the pressure-stabilizing air tank and the preheating grille.

[0041] Before the engine is cold started, close the throttle and turn on the air pump so that the system forms a closed air loop. Open the preheating grille, which continuously heats the air flowing through the grille. At this time, the heating efficiency of the grille is extremely high. When the air temperature in the closed loop is high enough, start the engine and open the throttle at the same time. At this time, there is enough warm air in the intake system to ensure that the engine is in a good combustion state; and after running for a transition period, the temperature of the engine cooling water and lubricating oil increases, and the friction resistance torque decreases. At this time, even if the preheating grille is closed, the engine can still run stably at extremely low intake temperature.

[0042] The above is only a preferred embodiment of the present invention. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the structure of the present invention, which will not affect the effect of the implementation of the present invention and the practicality of the patent.

Claims

1. An engine cold start method based on an intake air heating system, characterized in that: An air circuit system is constructed between the throttle, the preheating grille and the intake manifold, and a target heating temperature is set. Before the engine is cold started, the real-time air mass in the air circuit system is obtained, the heating time is calculated according to the target heating temperature and the real-time air mass, and it is determined whether it exceeds an expected value according to the heating time; if the heating time does not exceed the expected value, the engine starting procedure is executed after the air in the air circuit system reaches the target heating temperature; if the heating time exceeds the expected value, the amount of air in the air circuit system and the transition time of the engine running after the idle speed is stabilized are balanced.

2. The engine cold start method based on the intake air heating system according to claim 1, characterized in that: The calculation method of the heating time is: Where t is the heating time; m is the real-time air quality in the air circuit system; C V is the constant volume specific heat capacity of air; T Target is the target heating temperature; T Env is the ambient temperature; P haet is the heating power of the preheating grille; η is the heating efficiency of the air circuit system.

3. The engine cold start method based on the intake air heating system according to claim 2, characterized in that: The target heating temperature is 0-5°C.

4. The engine cold start method based on the intake air heating system according to claim 1 or 2, characterized in that: The balancing process is specifically as follows: Adjusting the real-time air quality according to the expected value so that the heating time is equal to the expected value; judging whether the adjusted air quality can maintain the minimum transition time after the engine idle speed stabilizes according to the adjusted air quality and the intake volume of the engine; If it cannot be maintained, increase the heating time by one time step with the set heating time step, and use the heating time after increasing the time step as the heating target time, re-judge whether the air quality corresponding to the heating target time can meet the minimum transition time after the engine idle speed stabilizes; if not, increase the air quality in the air circuit system so that the air quality in the air circuit system can meet the minimum transition time after the engine idle speed stabilizes.

5. The engine cold start method based on the intake air heating system according to claim 4, characterized in that: The transition duration ranges from 20 to 30 seconds.

6. An engine cold start device based on an intake air heating system, characterized in that: It includes a throttle, a preheating grille, an intake manifold and an ECU; a pressure-stabilizing air tank is provided between the throttle and the preheating grille, a return line is provided between the intake manifold and the connection between the throttle and the pressure-stabilizing air tank, and an air pump is installed in the return line; the ECU uses the engine cold start method based on the intake heating system as described in any one of claims 1 to 5 to control the throttle, the preheating grille and the air pump to work.

7. The engine cold start device based on the intake air heating system according to claim 6, characterized in that: A one-way valve and a solenoid valve are installed in the reflux pipeline.

8. The engine cold start device based on the intake air heating system according to claim 6, characterized in that: A solenoid valve is installed in the pipeline between the pressure-stabilizing gas storage tank and the preheating grid.

Images