Method for identifying a defective injection valve among a plurality of injection valves

Abstract

The invention discloses a method for identifying a faulty injection valve in a plurality of injection valves. The method comprises, after a certain operating time of a vehicle, detecting by a control unit 100 a first pressure gradient of fuel in each of a plurality of injection valves. During the certain operating time of the vehicle, the control unit detects 102 a second pressure gradient for the amount of fuel injected. The control unit compares 104 the first and second pressure gradients relative to a data lookup table. The data lookup table comprises values ​​of the first pressure gradient and the second pressure gradient for the amount of fuel injected. When the first pressure gradient exceeds a threshold limit defined in the data lookup table, the control unit checks 106 whether the second pressure gradient exceeds a threshold value defined in the data lookup table for the amount injected.

Description

Technical Field

[0001] The present invention relates to the field of fuel injection valves. Background Art

[0002] Injection valves are used in fuel injection systems that inject fuel loaded with pressure into the injection valves. Failure of injection valves occurs due to reasons such as wear and abrasion of the material of the injection valves. In the event of failure of one or more injection valves, the injection valves tend to leak excess fuel back into the fuel tank through a return path. In the case of a common rail system with multiple injection valves, it is necessary to detect an injection valve in the group of injection valves that has failed or is about to fail.

[0003] Patent application JP119586A representing the prior art discloses a method and a related device for detecting a fault of an injection valve. In order to detect the fault quickly and accurately, the current pressure drop caused in the common fuel compensation tank at the time of the current fuel injection is compared with the predetermined normal pressure drop, so as to thereby determine the injection defect. In the engine, at a predetermined time point, the electromagnetic coil is excited, and its injection valve 23 sequentially injects high-pressure fuel into the corresponding cylinder, so that the injection into the cylinders with numbers 1, 4, 2, 6, 3, and 5 is sequentially implemented according to the excitation current i1, i4, i2, i6, i3, and i5. In this process, in the common fuel compensation tank, a pressure drop is caused at a position corresponding to each excitation current. The pressure drop is detected by the pressure sensor 13 so as to be input to the microcomputer through an electrical signal. If the current pressure drop is not generated by the excitation current i1 at the time of fuel injection, the current pressure drop is compared with the normal pressure drop, and based on the excitation current i1, it is determined that the injection valve in the cylinder with number 1 causes the injection defect. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] Various modes of the present invention will be disclosed in detail in the specification and will be illustrated in the accompanying drawings:

[0005] Figure 1 A method for identifying a defective injection valve among a plurality of injection valves is shown. DETAILED DESCRIPTION

[0006] Figure 1A method for identifying a faulty injection valve among a plurality of injection valves is shown. The method comprises detecting 100 by a control unit a first pressure gradient of the fuel in each of the plurality of injection valves after a certain operating time of the vehicle. During the certain operating time of the vehicle, the control unit detects 102 a second pressure gradient for the amount of fuel injected. The control unit compares 104 the first and second pressure gradients relative to a data lookup table. The data lookup table comprises values ​​of the first pressure gradient and the second pressure gradient for the amount of fuel injected. When the first pressure gradient exceeds a threshold limit defined in the data lookup table, the control unit checks 106 whether the second pressure gradient exceeds a threshold value defined in the data lookup table for the amount injected.

[0007] The working mode of the method will be described in more detail. The proposed method is used to detect at least one faulty injection valve among a plurality of injection valves, which are present in a common rail system. The function of the injection valve is to inject high-pressure fuel into the engine cylinder. In the event of a failure of one or more injection valves, the injection valve tends to leak excess fuel back into the fuel tank through the return path, and this additional leakage affects the pressure gradient (first pressure gradient). Moreover, the return leakage (i.e. the amount of fuel) of the fuel passing through the pipeline and leaking into the fuel tank also increases, thereby affecting the stability of the fuel injection valve. Therefore, the proposed method is used to detect an injection valve that is about to fail or has failed within a group of fuel injection valves.

[0008] The proposed method uses the pressure gradient of the fuel in the injection valve to detect whether the injection valve has failed. When the fuel injection valve injects fuel into the engine cylinder, the pressure in the common rail system drops because the fuel injection valve that keeps the fuel under pressure now injects the same fuel into the cylinder. However, in the event of a failure of the fuel injection valve, the fuel injection valve allows the fuel to leak further back into the fuel tank through the return path. The pressure gradient check takes place under conditions after the run-in operation (Laufeinlassen), that is, when the ignition is switched to "off". If the injection valve is subject to wear, the pressure in the common rail system is relieved through the return path at a certain rate, wherein the rate of pressure drop increases and this is used as input to check for a specific injection valve failure. A second pressure gradient is detected on the vehicle during an overload operating condition (Überlaufbedingung) of the vehicle and under load.

[0009] The method comprises detecting (100) by a control unit a first pressure gradient of the fuel in each of a plurality of injection valves after a certain operating time of the vehicle. During the certain operating time of the vehicle, the control unit detects 102 a second pressure gradient for the amount of fuel injected. The control unit compares 104 the first and second pressure gradients with respect to a data lookup table. The data lookup table comprises pressure gradients defined for different values ​​of the injection amount. The data lookup table also comprises threshold values ​​for the first and second pressure gradients defined for a specific injection valve. In the event that the first and second pressure gradients exceed the threshold values, this indicates that the injection valve has failed or has been subject to wear. Now, the injection valve that has failed can be detected among the plurality of injection valves.

[0010] In the context of the present disclosure, "setting" or "design" refers to the technical efficacy or technical capability of a component, and the term "setting" or "design" is used to refer to the technical efficacy or technical capability when one or more specified actions are to be implemented or performed. In addition, the use of the term "setting" or "design" in this article refers to the normal technical efficacy or technical capability of a component due to design or structure or composition, and does not refer to any special or abnormal efficacy or capability beyond the scope of normal technical efficacy or technical capability. Therefore, this question needs to be raised.

[0011] It should be understood that the embodiments discussed in the above description are merely illustrative and do not limit the scope of the invention in terms of the type of fuel injection valve used. Many such embodiments and other modifications and changes to the embodiments described in the specification can be envisioned. The scope of the invention is limited only by the scope of the claims.

Claims

1. A method for identifying a defective injection valve among a plurality of injection valves; wherein: The method comprises: After a certain operating time of the vehicle, detecting (100) by a control unit a first pressure gradient of the fuel in each of the plurality of injection valves; During a certain operating time of the vehicle, a second pressure gradient for the injected fuel quantity is detected (102) by the control unit; comparing, by the control unit, the first and second pressure gradients with corresponding pressure gradients stored in a data lookup table (104); and When the first pressure gradient exceeds a threshold limit defined in the data look-up table, it is checked (106) by the control unit whether the second pressure gradient exceeds a threshold value defined in the data look-up table for the injected amount. 2 . The method of claim 1 , wherein the second pressure gradient is detected during an overload operating condition of the vehicle. The method of claim 1 , wherein the second pressure gradient is detected on the vehicle under load conditions.

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