A method for monitoring the opening of mechanical pressure relief valves in a high-pressure common rail system

Abstract

This invention discloses a method for monitoring the opening of a mechanical pressure relief valve in a high-pressure common rail system, comprising the following steps: Step 1, real-time monitoring of the actual rail pressure and the target rail pressure; Step 2, calculation of the gradient of the target rail pressure change; Step 3, determining whether to calculate the gradient of the actual rail pressure change based on the gradient of the target rail pressure change; if yes, proceed to Step 4; otherwise, return to Step 2; Step 4, calculating the gradient of the actual rail pressure change, and determining whether the pressure relief valve is open based on the gradient of the actual rail pressure change. This invention monitors the opening status of the pressure relief valve based on the gradients of the target rail pressure change and the actual rail pressure change, which can effectively improve the accuracy of monitoring the opening status of the pressure relief valve, thereby improving the operational reliability of the common rail system.

Description

Technical Field

[0001] This invention belongs to the field of automotive technology, specifically relating to a method for monitoring the opening of a mechanical pressure relief valve in a high-pressure common rail system. Background Technology

[0002] In high-pressure common rail fuel systems, the mechanical pressure relief valve on the fuel rail is a safety device that effectively protects the high-pressure system from damage caused by excessive pressure. However, this component is mechanical, and there are no sensors to directly indicate whether it is open. An electronic control strategy needs to be designed to determine whether the mechanical pressure relief valve is open by monitoring the rail pressure. The traditional approach is to monitor the actual rail pressure. When the actual rail pressure exceeds a certain limit and then suddenly drops, and the magnitude of the pressure drop matches the magnitude of the drop after the electronically controlled pressure relief valve opens, then it is determined that the pressure relief valve is open.

[0003] Traditional technical solutions do not consider the actual rail pressure drop caused by a decrease in the set rail pressure. After the set rail pressure drops, if there is a large injection volume at the same time, the actual rail pressure will also drop rapidly following the set rail pressure. If the drop is sufficient to determine the opening of the mechanical pressure relief valve, the system will mistakenly interpret it as the mechanical pressure relief valve opening and directly enter the limp mode of rail pressure control. That is, the high-pressure oil pump pumps oil at the maximum pumping volume, which affects the life of the fuel rail and engine performance. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of the aforementioned background technology and provide a method for monitoring the opening of a mechanical pressure relief valve in a high-pressure common rail system.

[0005] The technical solution adopted in this invention is: a method for monitoring the opening of a mechanical pressure relief valve in a high-pressure common rail system, step 1, real-time monitoring of the actual rail pressure and the target rail pressure;

[0006] Step 2: Calculate the gradient of the target rail pressure change;

[0007] Step 3: Determine whether to calculate the actual rail pressure change gradient based on the target rail pressure change gradient. If yes, continue to Step 4; otherwise, return to Step 2.

[0008] Step 4: Calculate the gradient of actual rail pressure change, and determine whether the pressure relief valve should be opened based on the gradient of actual rail pressure change.

[0009] Furthermore, the gradient of the target rail pressure change is the absolute value of the difference between the target rail pressure in the current cycle and the target rail pressure in the previous cycle.

[0010] Furthermore, when the gradient of the target rail pressure change is less than or equal to the first threshold, the gradient of the actual rail pressure change is determined and calculated; when the gradient of the target rail pressure change is greater than the first threshold, the gradient of the actual rail pressure change is not calculated, and the process returns to step 2.

[0011] Furthermore, when the gradient of the target orbital pressure change is greater than the first threshold, timing begins. If the timing reaches the set time, the process returns to step 2; otherwise, timing continues until the timing reaches the set time.

[0012] Furthermore, the set time is 2-5 seconds.

[0013] Furthermore, the actual rail pressure change gradient includes a first change gradient and a second change gradient, and the pressure relief valve is determined to be open based on the first change gradient and the second change gradient.

[0014] Furthermore, the process of determining whether the pressure relief valve is open based on the first and second gradient changes is as follows: first, the first gradient change is determined; if the first gradient change is less than or equal to the second threshold, the pressure relief valve is determined not to be open; otherwise, the second gradient change is determined.

[0015] Furthermore, if the second change gradient is less than or equal to the third threshold, it is determined that the pressure relief valve is not open; otherwise, it is determined that the pressure relief valve is open.

[0016] Furthermore, the first gradient change is the absolute value of the difference between the actual rail pressure of the previous cycle and the actual rail pressure of the cycle before that.

[0017] Furthermore, the second gradient is the absolute value of the difference between the actual rail pressure in the current cycle and the actual rail pressure in the previous cycle.

[0018] The beneficial effects of this invention are:

[0019] This invention monitors the opening status of the pressure relief valve based on the gradient of the target rail pressure change and the gradient of the actual rail pressure change, which can effectively improve the accuracy of pressure relief valve opening status monitoring, thereby improving the working reliability of the common rail system.

[0020] In the process of determining the opening status of the pressure relief valve, this invention delays monitoring for a period of time when the target rail pressure change gradient is detected to be greater than a certain value. This can effectively prevent misjudgment, improve engine power and emission performance, and enhance the vehicle driving experience. Attached Figure Description

[0021] Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0022] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0023] This invention is applicable to rail pressure control in high-pressure common rail fuel systems for diesel engines. By monitoring the target rail pressure and the actual rail pressure, it determines the opening status of the mechanical pressure relief valve on the fuel rail, solving the problem of misjudgment of opening caused by traditional methods. Figure 1 As shown, the present invention provides a method for monitoring the opening of a mechanical pressure relief valve in a high-pressure common rail system, comprising the following steps:

[0024] Step 1: Monitor the actual rail pressure and target rail pressure in real time;

[0025] Step 2: Calculate the gradient of the target rail pressure change;

[0026] Step 3: Determine whether to calculate the actual rail pressure change gradient based on the target rail pressure change gradient. If yes, continue to Step 4; otherwise, return to Step 2.

[0027] Step 4: Calculate the gradient of actual rail pressure change, and determine whether the pressure relief valve should be opened based on the gradient of actual rail pressure change.

[0028] In the above scheme, the gradient of the target rail pressure change is the absolute value of the difference between the target rail pressure in the current cycle and the target rail pressure in the previous cycle.

[0029] In the above scheme, when the gradient of the target rail pressure change is less than or equal to the first threshold, the gradient of the actual rail pressure change is calculated; when the gradient of the target rail pressure change is greater than the first threshold, the gradient of the actual rail pressure change is not calculated, and the process returns to step 2 above. The first threshold is calibrated according to actual needs, such as 1000 bar / s.

[0030] In the above scheme, when the gradient of the target rail pressure change is greater than the first threshold, timing begins. If the timing reaches the set time, the process returns to step 2; otherwise, timing continues until the set time is reached. The set time is 2-5 seconds, preferably 3 seconds.

[0031] In the above scheme, the actual rail pressure change gradient includes a first change gradient and a second change gradient, and the pressure relief valve is determined based on the first change gradient and the second change gradient. The first change gradient is the absolute value of the difference between the actual rail pressure of the previous cycle and the actual rail pressure of the cycle before that; the second change gradient is the absolute value of the difference between the actual rail pressure of the current cycle and the actual rail pressure of the previous cycle.

[0032] In the above scheme, the process of determining whether the pressure relief valve is open based on the first and second gradient changes is as follows: First, the first gradient change is judged. If the first gradient change is less than or equal to the second threshold, the pressure relief valve is determined not to be open; otherwise, the second gradient change is judged. If the second gradient change is less than or equal to the third threshold, the pressure relief valve is determined not to be open; otherwise, the pressure relief valve is determined to be open. The second and third thresholds are calibrated according to actual needs; for example, the second threshold can be 1200 bar / s, and the third threshold can be 800 bar / s.

[0033] The monitoring method of this invention not only monitors the actual rail pressure but also the target rail pressure. When the target rail pressure's decreasing gradient is detected to reach a certain level (i.e., the level at which the mechanical pressure relief valve is easily misjudged), the system will not monitor for a period of time until the period has passed, after which the target rail pressure's change gradient will be monitored again. By monitoring the actual rail pressure's change gradient for two consecutive cycles, this method can effectively improve the accuracy of monitoring the pressure relief valve's opening status, thereby improving the reliability of the common rail system.

[0034] It should be understood that the specific order or hierarchy of steps in the disclosed process is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process may be rearranged without departing from the scope of this disclosure. The appended method claims provide elements of various steps in an exemplary order and are not intended to limit the scope to the specific order or hierarchy described.

[0035] To make the description of this disclosure more detailed and complete, illustrative descriptions of the embodiments and specific examples of the present invention have been provided above; however, this is not the only form of implementing or utilizing the specific examples of the present invention. The embodiments cover the features of multiple specific examples and the method steps and their order for constructing and operating these specific examples. However, other specific examples may also be used to achieve the same or equivalent functions and order of steps.

[0036] In the above detailed description, various features are combined together in a single embodiment to simplify this disclosure. This approach to disclosure should not be construed as reflecting an intention that embodiments of the claimed subject matter require more features than are explicitly stated in each claim. Rather, as reflected in the appended claims, the invention is presented with fewer features than all of the features of the single disclosed embodiment. Therefore, the appended claims are hereby explicitly incorporated into the detailed description, wherein each claim stands alone as a preferred embodiment of the invention.

[0037] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Contents not described in detail in this specification belong to prior art known to those skilled in the art.

Claims

1. A method for monitoring the opening of a mechanical pressure relief valve in a high-pressure common rail system, characterized in that, Includes the following steps: Step 1: Monitor the actual rail pressure and target rail pressure in real time; Step 2: Calculate the gradient of the target rail pressure change; Step 3: Determine whether to calculate the actual rail pressure change gradient based on the target rail pressure change gradient. If yes, continue to Step 4; otherwise, return to Step 2. Step 4: Calculate the gradient of actual rail pressure change, and determine whether the pressure relief valve should be opened based on the gradient of actual rail pressure change.

2. The method for monitoring the opening of the mechanical pressure relief valve in a high-pressure common rail system according to claim 1, characterized in that: The gradient of the target rail pressure change is the absolute value of the difference between the target rail pressure in the current cycle and the target rail pressure in the previous cycle.

3. The method for monitoring the opening of the mechanical pressure relief valve in a high-pressure common rail system according to claim 1, characterized in that: When the gradient of the target rail pressure change is less than or equal to the first threshold, the gradient of the actual rail pressure change is calculated; when the gradient of the target rail pressure change is greater than the first threshold, the gradient of the actual rail pressure change is not calculated, and the process returns to step 2.

4. The method for monitoring the opening of the mechanical pressure relief valve in a high-pressure common rail system according to claim 3, characterized in that: When the gradient of the target rail pressure change is greater than the first threshold, timing begins. If the timing reaches the set time, return to step 2; otherwise, timing continues until the timing reaches the set time.

5. The method for monitoring the opening of the mechanical pressure relief valve in a high-pressure common rail system according to claim 4, characterized in that: The set time is 2-5 seconds.

6. The method for monitoring the opening of the mechanical pressure relief valve in a high-pressure common rail system according to claim 1, characterized in that: The actual rail pressure change gradient includes a first change gradient and a second change gradient. The pressure relief valve is determined based on the first change gradient and the second change gradient.

7. The method for monitoring the opening of the mechanical pressure relief valve in a high-pressure common rail system according to claim 6, characterized in that: The process of determining whether the pressure relief valve is open based on the first and second gradient changes is as follows: First, determine the first gradient change. If the first gradient change is less than or equal to the second threshold, then determine that the pressure relief valve is not open; otherwise, continue to determine the second gradient change.

8. The method for monitoring the opening of the mechanical pressure relief valve in a high-pressure common rail system according to claim 7, characterized in that: If the second gradient change is less than or equal to the third threshold, the pressure relief valve is determined to be closed; otherwise, the pressure relief valve is determined to be open.

9. The method for monitoring the opening of the mechanical pressure relief valve in a high-pressure common rail system according to claim 6, characterized in that: The first gradient is the absolute value of the difference between the actual rail pressure in the previous cycle and the actual rail pressure in the cycle before that.

10. The method for monitoring the opening of the mechanical pressure relief valve in a high-pressure common rail system according to claim 6, characterized in that: The second gradient is the absolute value of the difference between the actual rail pressure in the current cycle and the actual rail pressure in the previous cycle.

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