A protection method for a cooling water electromagnetic valve of a urea tank

Abstract

The present application discloses a protection method for a cooling water electromagnetic valve of a urea tank. It includes judging the opening and closing of the cooling water electromagnetic valve according to the engine speed, and the cooling water electromagnetic valve is an on-off electromagnetic valve or a proportional electromagnetic valve. The present application prevents the cooling water electromagnetic valve from being damaged by the impact of the cooling water flow, and prevents the problem of the impurities in the cooling water being stuck in the cooling water electromagnetic valve.

Description

Technical Field

[0001] This invention belongs to the technical field of vehicle after-treatment systems, and particularly relates to vehicles equipped with the Urea-SCR after-treatment system, specifically a protection method for the urea tank cooling water solenoid valve. Background Technology

[0002] With the imminent implementation of the China VI emission standards, diesel engine manufacturers are currently developing China VI diesel engines. In order to reduce NOx and particulate emissions in engine exhaust, China VI diesel engines are equipped with an aftertreatment system consisting of a catalytic oxidizer (DOC), a particulate filter (DPF), and a selective oxidation-reduction converter (SCR). Urea is injected into the exhaust pipe through a urea injection system, where it decomposes into NH3, which reacts with NOx to reduce NOx emissions.

[0003] The China VI emission standard requires that after the urea tank is completely frozen, the vehicle should idle for 10-20 minutes in a low-temperature environment of -17℃ to 7℃, and then run at no more than 40% load for no more than 50 minutes, during which time the urea injection system should function normally. To meet these requirements, aftertreatment systems are now equipped with coolant solenoid valves. By opening these valves, engine coolant flows through the urea tank, thawing the urea inside.

[0004] The amount of coolant in an engine is related to its engine speed; the higher the engine speed, the greater the coolant flow. The coolant solenoid valve is susceptible to the impact of coolant flow when opening and closing. If the flow is too large, it may damage the valve plate, therefore appropriate protective measures are necessary.

[0005] Urea solution only freezes below -11℃. Therefore, it does not freeze at temperatures above -11℃, eliminating the need for the cooling water solenoid valve to open for heating. Engine coolant contains impurities. If the solenoid valve remains closed for an extended period, these impurities can accumulate near it, causing it to become stuck and unable to open. This leads to a malfunction and necessitates valve replacement. Therefore, appropriate protective measures are required.

[0006] The existing technical solution is relatively simple. The solenoid valve is turned on when there is a need for heating and defrosting, and turned off when there is no need for heating and defrosting. It does not take into account the impact of water flow on the solenoid valve or the problem of the solenoid valve being blocked by impurities.

[0007] Therefore, the shortcomings of the existing technology are:

[0008] (1) The cooling water solenoid valve will be affected by the flow of cooling water, which is not considered in the current heating and defrosting control method;

[0009] (2) The cooling water solenoid valve is affected by impurities in the engine cooling water, which can cause the cooling water solenoid valve to stick. The current heating and defrosting control method does not take this into account. Summary of the Invention

[0010] The purpose of this invention is to overcome the shortcomings of the aforementioned background technology and provide a protection method for the cooling water solenoid valve of a urea tank. This solves the problems of damage to the cooling water solenoid valve due to cooling water impact and jamming due to impurities.

[0011] The technical solution adopted in this invention is: a protection method for a urea tank cooling water solenoid valve, comprising determining the opening and closing of the cooling water solenoid valve based on the engine speed, wherein the cooling water solenoid valve is a switching solenoid valve or a proportional solenoid valve.

[0012] After the engine starts and runs for a set time T emp1 If the conditions for opening the cooling water solenoid valve are met, then the cooling water solenoid valve is opened and kept open for a period of time T. emp2 If the condition for closing the cooling water solenoid valve is met, then the cooling water solenoid valve will be closed.

[0013] If the cooling water solenoid valve is a proportional solenoid valve, the switching must be completed within a set time t0 when the cooling water solenoid valve needs to be opened or closed. The range of t0 is 5 to 60 seconds.

[0014] The map is read based on the opening change and speed. For example, if the cooling water solenoid valve needs to change from an opening of 10% to 100%, and the switching time is 20 seconds based on the opening change of 90% and the speed of 1500 rpm, then the solenoid valve opening switch is completed within 20 seconds.

[0015] If the cooling water solenoid valve is a switch solenoid valve, the cooling water solenoid valve is opened and closed under the following conditions:

[0016] Cooling water solenoid valve opening conditions: Start timing t1. If the engine speed is less than the first target value N1, then start timing t2. If the engine speed is greater than the first target value N1, then t2 is reset to zero. If t1 is less than the set value S1 and t2 is greater than the set value S2, then the cooling water solenoid valve is opened. If t1 is greater than the set value S1, then the cooling water solenoid valve is opened.

[0017] Cooling water solenoid valve closing conditions: Start timing t3. If the engine speed is less than the second target value N2, start timing t4. If the engine speed is greater than the second target value N2, then t4 is reset to zero. If t3 is less than the set value S3 and t4 is greater than the set value S4, then the cooling water solenoid valve closes. If t3 is greater than the set value S3 and the urea temperature in the urea tank is greater than T... target If so, then the cooling water solenoid valve will be closed.

[0018] The range of the setting value S1 is 30 to 1200 seconds, and the range of the setting value S2 is 0.1 to 30 seconds.

[0019] The first target value N1 is in the range of 600 to 1800 rpm.

[0020] The range of the setting value S3 is 30 to 1200 seconds, and the range of the setting value S4 is 0.1 to 30 seconds.

[0021] The second target value N2 is in the range of 600–1800 rpm; T target The temperature range is 30–60℃.

[0022] T emp1 The range is 0.1–20 h; T emp2 The range is 1 to 1000 seconds.

[0023] The engine speed is measured using an engine speed sensor.

[0024] The coolant solenoid valve self-cleaning function is performed only once in a driving cycle. A driving cycle refers to a continuous process consisting of engine start, (vehicle) operation, engine shutdown, and the time from engine shutdown to the next engine start.

[0025] This invention provides a method for determining the opening and closing of the cooling water solenoid valve based on engine speed, avoiding the problem of excessive water flow surge when the cooling water solenoid valve is opened. It also adds a self-cleaning function to the cooling water solenoid valve, opening the cooling water solenoid valve for a period of time in each driving cycle, allowing the engine coolant to flush away impurities near the solenoid valve, thus preventing the accumulation of too many impurities near the cooling water solenoid valve and causing the solenoid valve to stick.

[0026] This invention prevents the cooling water solenoid valve from being damaged by the impact of cooling water flow, and also prevents impurities in the cooling water from accumulating near the cooling water solenoid valve and causing it to jam. Attached Figure Description

[0027] Figure 1 This is a flowchart of step 1 of the present invention;

[0028] Figure 2 This is a flowchart illustrating the opening conditions of the cooling water solenoid valve according to the present invention.

[0029] Figure 3 This is a flowchart illustrating the closing conditions of the cooling water solenoid valve according to the present invention. Detailed Implementation

[0030] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. 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 only some embodiments of the present invention, and not all embodiments.

[0031] like Figure 1-3 As shown, the present invention includes determining the opening and closing of a cooling water solenoid valve based on engine speed, wherein the cooling water solenoid valve is a switching solenoid valve or a proportional solenoid valve.

[0032] Step 1: After the engine starts and runs for a set time T emp1 If the conditions for opening the cooling water solenoid valve are met, then the cooling water solenoid valve is opened and kept open for a period of time T. emp2 If the condition for closing the cooling water solenoid valve is met, then the cooling water solenoid valve will be closed.

[0033] Step 2: If the cooling water solenoid valve is a proportional solenoid valve, the switching must be completed within a set time t0 when the cooling water solenoid valve needs to be opened or closed. The range of t0 is 5 to 60 seconds.

[0034] The map is read based on the opening change and speed. For example, if the cooling water solenoid valve needs to change from an opening of 10% to 100%, and the switching time is 20 seconds based on the opening change of 90% and the speed of 1500 rpm, then the solenoid valve opening switch is completed within 20 seconds.

[0035] If the cooling water solenoid valve is a switch solenoid valve, the cooling water solenoid valve is opened and closed under the following conditions:

[0036] Cooling water solenoid valve opening conditions: Start timing t1. If the engine speed is less than the first target value N1, then start timing t2. If the engine speed is greater than the first target value N1, then t2 is reset to zero. If t1 is less than the set value S1 and t2 is greater than the set value S2, then the cooling water solenoid valve is opened. If t1 is greater than the set value S1, then the cooling water solenoid valve is opened.

[0037] Cooling water solenoid valve closing conditions: Start timing t3. If the engine speed is less than the second target value N2, start timing t4. If the engine speed is greater than the second target value N2, then t4 is reset to zero. If t3 is less than the set value S3 and t4 is greater than the set value S4, then the cooling water solenoid valve closes. If t3 is greater than the set value S3 and the urea temperature in the urea tank is greater than T... target If so, then the cooling water solenoid valve will be closed.

[0038] The range of the setting value S1 is 30 to 1200 seconds, and the range of the setting value S2 is 0.1 to 30 seconds.

[0039] The first target value N1 is in the range of 600 to 1800 rpm.

[0040] The range of the setting value S3 is 30 to 1200 seconds, and the range of the setting value S4 is 0.1 to 30 seconds.

[0041] The second target value N2 is in the range of 600–1800 rpm; T target The temperature range is 30–60℃.

[0042] T emp1 The range is 0.1–20 h; T emp2 The range is 1 to 1000 seconds.

[0043] The engine speed is measured using an engine speed sensor.

[0044] The coolant solenoid valve self-cleaning function is performed only once in a driving cycle. A driving cycle refers to a continuous process consisting of engine start, (vehicle) operation, engine shutdown, and the time from engine shutdown to the next engine start.

[0045] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

Claims

1. A protection method for a urea tank cooling water solenoid valve, characterized in that: This includes determining the opening and closing of the cooling water solenoid valve based on the engine speed; the cooling water solenoid valve is a switching solenoid valve. The cooling water solenoid valve is opened and closed under the following conditions: Cooling water solenoid valve opening conditions: Start timing t1. If the engine speed is less than the first target value N1, then start timing t2. If the engine speed is greater than the first target value N1, then t2 is reset to zero. If t1 is less than the set value S1 and t2 is greater than the set value S2, then the cooling water solenoid valve is opened. If t1 is greater than the set value S1, then the cooling water solenoid valve is opened. Cooling water solenoid valve closing conditions: Start timing t3. If the engine speed is less than the second target value N2, start timing t4. If the engine speed is greater than the second target value N2, then t4 is reset to zero. If t3 is less than the set value S3 and t4 is greater than the set value S4, then the cooling water solenoid valve closes. If t3 is greater than the set value S3 and the urea temperature in the urea tank is greater than T... target Then the cooling water solenoid valve will be closed; The range of the setpoint S1 is 30~1200s, and the range of the setpoint S2 is 0.1~30s; The first target value N1 is in the range of 600~1800 rpm; The range of the setting value S3 is 30~1200s, and the range of the setting value S4 is 0.1~30s; The second target value N2 is in the range of 600~1800 rpm; T target The temperature range is 30~60℃; After the engine starts and runs for a set time T emp1 If the conditions for opening the cooling water solenoid valve are met, then the cooling water solenoid valve is opened and kept open for a period of time T. emp2 If the condition for closing the cooling water solenoid valve is met, then the cooling water solenoid valve is closed. T emp1 The range is 0.1~20h; T emp2 The range is 1~1000s.

2. The protection method for a urea tank cooling water solenoid valve according to claim 1, characterized in that: The engine speed is measured using an engine speed sensor.

Images