Engine uniformity control method, device and vehicle

Abstract

This application provides a control method, device, and vehicle for the consistency of each cylinder in an engine. The method includes: acquiring the engine speed and torque to obtain the engine speed and engine torque; determining that the engine is in a low-speed, low-load condition when the engine speed is within a first predetermined range and the engine torque is within a second predetermined range; and controlling the camshaft phase to be delayed relative to the crankshaft phase when the engine is in a low-speed, low-load condition, thereby delaying the opening of the engine's intake valves, thus solving the problem of poor consistency of the actual EGR rate of each cylinder in the prior art.

Description

Technical Field

[0001] This application relates to the field of engine control technology, and more specifically, to a control method, device, and vehicle for the consistency of control across all cylinders of an engine. Background Technology

[0002] Normally, the intake valve of an engine opens before the piston reaches top dead center (TDC). As the piston continues to move upwards, if the cylinder pressure is higher than the intake manifold pressure, some exhaust gas will flow back into the intake manifold's pressure regulating chamber through the intake valve. Influenced by the airflow in the intake manifold, exhaust gas tends to accumulate at the end furthest from the intake manifold inlet. This results in inconsistent actual EGR rates across the engine cylinders, leading to knocking, misfires, and abnormal emissions due to differences in combustion states. This phenomenon is more pronounced under low-speed, low-load engine conditions and gradually diminishes as engine speed or load increases. Summary of the Invention

[0003] The main objective of this application is to provide a control method, device, and vehicle for the consistency of engine cylinders, so as to at least solve the problem of poor consistency of actual EGR rate of engine cylinders in the prior art.

[0004] To achieve the above objectives, according to one aspect of this application, a method for controlling the consistency of each cylinder of an engine is provided, comprising: acquiring the engine speed and torque to obtain the engine speed and engine torque; determining that the engine is in a low-speed, low-load condition when the engine speed is within a first predetermined range and the engine torque is within a second predetermined range; and controlling the camshaft phase to be delayed relative to the crankshaft phase when the engine is in the low-speed, low-load condition, thereby delaying the opening of the engine's intake valves.

[0005] Optionally, when the engine is under low-speed, low-load conditions, controlling the camshaft phase to be delayed relative to the crankshaft phase, thereby delaying the opening of the engine's intake valves, includes: acquiring the accelerator pedal opening change rate and the engine's coolant temperature; and when the accelerator pedal opening change rate is less than an opening threshold, the coolant temperature is greater than a temperature threshold, and the engine is under the low-speed, low-load conditions, controlling the camshaft phase to be delayed relative to the crankshaft phase, thereby delaying the opening of the engine's intake valves.

[0006] Optionally, when the engine is in a low-speed, low-load condition, controlling the camshaft phase to be delayed relative to the crankshaft phase, thereby delaying the opening of the engine's intake valves, further includes: when the duration of the engine being in the low-speed, low-load condition exceeds a duration threshold, controlling the camshaft phase to be delayed relative to the crankshaft phase, thereby delaying the opening of the engine's intake valves.

[0007] Optionally, when the engine is in the low-speed, low-load condition, controlling the camshaft phase to be delayed relative to the crankshaft phase, thereby delaying the opening of the engine's intake valves, further includes: when the engine is in the low-speed, low-load condition, querying a delay angle mapping relationship based on the engine speed and the engine torque to obtain the camshaft phase delay angle, wherein the delay angle mapping relationship is a mapping relationship between the camshaft phase delay angle, the engine speed, and the engine torque; and controlling the camshaft phase to be delayed relative to the crankshaft phase by the camshaft phase delay angle.

[0008] Optionally, before determining that the engine is in a low-speed, low-load condition when the engine speed is within a first predetermined range and the engine torque is within a second predetermined range, the method further includes: adjusting the engine speed and torque, and collecting the maximum difference in EGR rate and the maximum difference in peak cylinder pressure of each cylinder corresponding to each speed and each torque; determining the speed range in which the maximum difference in EGR rate of each cylinder is greater than or equal to a first difference threshold and the maximum difference in peak cylinder pressure of each cylinder is greater than or equal to a second difference threshold as the first predetermined range; and determining the torque range in which the maximum difference in EGR rate of each cylinder is greater than or equal to the first difference threshold and the maximum difference in peak cylinder pressure of each cylinder is greater than or equal to the second difference threshold as the second predetermined range.

[0009] Optionally, before obtaining the camshaft phase delay angle by querying the delay angle mapping relationship based on the engine speed and the engine torque, the method further includes: adjusting the engine speed within a first predetermined range, adjusting the engine torque within a second predetermined range to obtain engine test speed and engine test torque; controlling the camshaft phase to be delayed relative to the crankshaft phase until the maximum difference in EGR rate of each cylinder is less than a first difference threshold and the maximum difference in peak cylinder pressure of each cylinder is less than a second difference threshold, to obtain the camshaft phase delay angle corresponding to the engine test speed and the engine test torque; and establishing the delay angle mapping relationship based on the engine test speed, the engine test torque, and the corresponding camshaft phase delay angle.

[0010] Optionally, when the engine is in the low-speed, low-load condition, after controlling the camshaft phase to be delayed relative to the crankshaft phase, thereby delaying the opening of the engine's intake valves, the method further includes: adjusting the engine's fuel injection quantity according to the engine's intake air volume, so that the air-fuel ratio remains constant.

[0011] Optionally, after delaying the camshaft phase relative to the crankshaft phase to delay the opening of the engine's intake valves, the method further includes: when the engine is not in the low-speed, low-load condition, controlling the camshaft phase to return to its state before the delay relative to the crankshaft phase.

[0012] According to another aspect of this application, a control device for the consistency of each cylinder of an engine is provided, comprising: a first acquisition unit for acquiring the engine speed and torque to obtain the engine speed and engine torque; a first determination unit for determining that the engine is in a low-speed, low-load condition when the engine speed is within a first predetermined range and the engine torque is within a second predetermined range; and a first control unit for controlling the camshaft phase to be delayed relative to the crankshaft phase when the engine is in the low-speed, low-load condition, thereby delaying the opening of the engine's intake valves.

[0013] According to another aspect of this application, a computer program product is provided, comprising a computer program that, when executed by a processor, implements any of the methods described.

[0014] According to another aspect of this application, a vehicle is provided, comprising: one or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the one or more programs including methods for performing any one of the methods described.

[0015] Applying the technical solution of this application, in the above-mentioned control method for the consistency of each cylinder of the engine, the intake valve of the engine opens before the piston exhaust top dead center, resulting in exhaust gas backflow into the intake manifold, which causes the actual EGR rate of each cylinder of the engine to be inconsistent. However, this phenomenon will be gradually eliminated when the speed or load is high. Therefore, this method collects the engine speed and engine torque. If the engine speed is within a first predetermined range and the engine torque is within a second predetermined range, it is determined that the engine is in a low-speed and low-load condition. The camshaft phase is controlled to be delayed relative to the crankshaft phase, so that the opening of the engine intake valve is delayed, thereby reducing the amount of exhaust gas backflow, thereby improving the consistency of the actual EGR rate of each cylinder of the engine, and solving the problem of poor consistency of the actual EGR rate of each cylinder of the engine in the prior art. Attached Figure Description

[0016] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0017] Figure 1A hardware structure block diagram of a mobile terminal for performing a control method for consistent operation of each cylinder of an engine, according to an embodiment of this application, is shown.

[0018] Figure 2 A schematic flowchart of a control method for the consistency of each cylinder of an engine, according to an embodiment of this application, is shown.

[0019] Figure 3 A flowchart illustrating another control method for cylinder consistency of an engine provided according to an embodiment of this application is shown.

[0020] Figure 4 A schematic diagram of a process for adjusting the camshaft phase according to a control target map, provided by an embodiment of this application, is shown.

[0021] Figure 5 A flowchart illustrating another control method for cylinder consistency of an engine provided according to an embodiment of this application is shown.

[0022] Figure 6 A structural block diagram of a control device for the consistency of each cylinder of an engine, according to an embodiment of this application, is shown.

[0023] The above figures include the following reference numerals:

[0024] 102. Processor; 104. Memory; 106. Transmission device; 108. Input / output device. Detailed Implementation

[0025] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0026] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0027] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0028] For ease of description, the following explains some of the nouns or terms used in the embodiments of this application:

[0029] EGR: Exhaust Gas Recirculation, a technology that reduces combustion temperature by recirculating some of the engine's exhaust gases back into the combustion chamber, primarily used to reduce nitrogen oxides (NOx). x )emission.

[0030] As described in the background section, the actual EGR rate of each cylinder in the prior art is inconsistent. To solve this problem, embodiments of this application provide a method, apparatus, and vehicle for controlling the consistency of each cylinder in an engine.

[0031] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0032] The methods and embodiments provided in this application can be executed on a mobile terminal, computer terminal, or similar computing device. Taking running on a mobile terminal as an example, Figure 1 This is a hardware structure block diagram of a mobile terminal for a control method of engine cylinder consistency according to an embodiment of the present invention. Figure 1 As shown, a mobile terminal may include one or more ( Figure 1 Only one is shown in the diagram. A processor 102 (which may include, but is not limited to, a microprocessor MCU or a programmable logic device FPGA, etc.) and a memory 104 for storing data are also shown. The mobile terminal may further include a transmission device 106 for communication functions and an input / output device 108. Those skilled in the art will understand that... Figure 1 The structure shown is for illustrative purposes only and does not limit the structure of the mobile terminal described above. For example, the mobile terminal may also include components that are more... Figure 1 The more or fewer components shown, or having the same Figure 1 The different configurations shown.

[0033] The memory 104 can be used to store computer programs, such as application software programs and modules, like the computer program corresponding to the engine cylinder consistency control method in this embodiment of the invention. The processor 102 executes various functional applications and data processing by running the computer program stored in the memory 104, thereby implementing the above-described method. The memory 104 may include high-speed random access memory and non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some instances, the memory 104 may further include memory remotely located relative to the processor 102, and these remote memories can be connected to the mobile terminal via a network. Examples of the aforementioned networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof. The transmission device 106 is used to receive or send data via a network. Specific examples of the aforementioned networks may include wireless networks provided by the mobile terminal's communication provider. In one example, the transmission device 106 includes a network interface controller (NIC), which can be connected to other network devices via a base station to communicate with the Internet. In one example, the transmission device 106 may be a radio frequency (RF) module, which is used to communicate with the Internet wirelessly.

[0034] This embodiment provides a method that runs on a mobile terminal, computer terminal, or similar computing device. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Also, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0035] Figure 2 This is a flowchart of a control method for the consistency of each cylinder in an engine according to an embodiment of this application. Figure 2 As shown, the method includes the following steps:

[0036] Step S201: Obtain the engine speed and torque to get the engine speed and engine torque;

[0037] Specifically, the engine speed is collected by a speed sensor, and the engine torque is calculated based on the accelerator pedal opening collected by an accelerator pedal opening sensor.

[0038] Step S202: When the engine speed is within a first predetermined range and the engine torque is within a second predetermined range, it is determined that the engine is in a low-speed, low-load operating condition.

[0039] Specifically, by setting a first predetermined range and a second predetermined range corresponding to low-speed and low-load operating conditions, such that the engine speed is within the first predetermined range and the engine torque is within the second predetermined range, it can be determined that the engine is in a low-speed and low-load operating condition.

[0040] Step S203: When the engine is in the low-speed, low-load condition, the camshaft phase is delayed relative to the crankshaft phase, thereby delaying the opening of the engine's intake valve.

[0041] Specifically, when the engine is operating under the aforementioned low-speed and low-load conditions, delaying the intake valve opening time by adjusting the camshaft phase can reduce the amount of exhaust gas returning to the cylinder, thereby improving the consistency of EGR rate across all cylinders.

[0042] In this embodiment, the engine intake valve opens before the piston reaches top dead center, causing exhaust gas to flow back into the intake manifold, resulting in inconsistent actual EGR rates among the engine cylinders. However, this phenomenon gradually disappears when the engine speed or load is high. Therefore, this method collects engine speed and engine torque. If the engine speed is within a first predetermined range and the engine torque is within a second predetermined range, it determines that the engine is in a low-speed, low-load condition. It controls the camshaft phase to be delayed relative to the crankshaft phase, thereby delaying the opening of the engine intake valve to reduce the amount of exhaust gas flowing back, thus improving the consistency of the actual EGR rate among the engine cylinders and solving the problem of poor consistency of the actual EGR rate among the engine cylinders in the prior art.

[0043] To avoid affecting cold start and torque response, one alternative implementation is as follows: Figure 3 As shown, step S203 above includes:

[0044] Step S2031: Obtain the accelerator pedal opening change rate and the engine coolant temperature;

[0045] Step S2032: When the above-mentioned accelerator pedal opening change rate is less than the opening threshold, the above-mentioned water outlet temperature is greater than the temperature threshold, and the above-mentioned engine is in the above-mentioned low speed and low load conditions, the above-mentioned camshaft phase is controlled to be delayed relative to the above-mentioned crankshaft phase, so that the intake valve opening of the above-mentioned engine is delayed.

[0046] In the above embodiments, a temperature threshold, namely temperature limit W1, is set. Only when the outlet water temperature is greater than the temperature threshold is the camshaft phase delayed relative to the crankshaft phase controlled to avoid starting difficulties caused by intake valve opening delay at low temperatures and ensure that the vehicle can start normally in cold conditions. An opening threshold, namely accelerator pedal opening change rate limit W2, is set. Only when the accelerator pedal opening change rate is less than the opening threshold is the camshaft phase delayed relative to the crankshaft phase controlled to avoid deterioration in acceleration responsiveness caused by intake valve opening delay and ensure the driver's driving experience. Therefore, the camshaft phase is delayed relative to the crankshaft phase only when the accelerator pedal opening change rate is less than the opening threshold, the outlet water temperature is greater than the temperature threshold, and the engine is in the low-speed, low-load condition, thus avoiding affecting engine performance.

[0047] To avoid engine malfunction, in an optional implementation, step S203 further includes:

[0048] Step S2033: When the duration of the engine operating under the low-speed, low-load condition exceeds a duration threshold, the camshaft phase is controlled to be delayed relative to the crankshaft phase, thereby delaying the opening of the engine's intake valve.

[0049] In the above embodiments, a time threshold is set, namely the time limit W3 for entering the observation window. When the duration of the engine in the low-speed and low-load condition is greater than the time threshold, it indicates that the engine will be in the low-speed and low-load condition for a long time. This can control the camshaft phase to be delayed relative to the crankshaft phase, thus avoiding abnormal engine status caused by frequent switching.

[0050] To ensure consistency in the actual EGR rate of each cylinder, one optional implementation method is as follows: Figure 4 As shown, step S203 above also includes:

[0051] Step S2034: When the engine is under the low speed and low load condition, the camshaft phase delay angle is obtained by querying the delay angle mapping relationship between the engine speed and the engine torque. The delay angle mapping relationship is the mapping relationship between the camshaft phase delay angle, the engine speed and the engine torque.

[0052] Step S2035: Control the camshaft phase to be delayed relative to the crankshaft phase by the camshaft phase delay angle.

[0053] In the above embodiments, by obtaining the mapping relationship of the engine torque obtained from the test, i.e. the intake valve opening time delay map, the camshaft phase delay angle can be obtained by querying the delay angle mapping relationship between the engine speed and the engine torque. By controlling the camshaft phase to be delayed relative to the crankshaft phase by the camshaft phase delay angle, the EGR rate and peak cylinder pressure of each cylinder can reach a reasonable level.

[0054] In an optional embodiment, to determine the first predetermined range and the second predetermined range, before determining that the engine is in a low-speed, low-load operating condition when the engine speed is within the first predetermined range and the engine torque is within the second predetermined range, the method further includes:

[0055] Step S301: Adjust the engine speed and torque, and collect the maximum difference in EGR rate and the maximum difference in peak cylinder pressure of each cylinder corresponding to each speed and torque.

[0056] Step S302: The speed range in which the maximum difference in EGR rate of each cylinder is greater than or equal to the first difference threshold and the maximum difference in peak cylinder pressure of each cylinder is greater than or equal to the second difference threshold is determined as the first predetermined range.

[0057] Step S303: The torque range in which the maximum difference in EGR rate of each cylinder is greater than or equal to the first difference threshold and the maximum difference in peak cylinder pressure of each cylinder is greater than or equal to the second difference threshold is determined as the second predetermined range.

[0058] In the above embodiments, different types of engines have different parameters, and the first predetermined range and the second predetermined range corresponding to low-speed and low-load conditions are also different. During laboratory testing, the engine speed and torque are adjusted to determine the speed range and torque range where the maximum difference in EGR rate of each cylinder is greater than or equal to the first difference threshold and the maximum difference in peak cylinder pressure of each cylinder is greater than or equal to the second difference threshold. The first predetermined range and the second predetermined range can then be obtained.

[0059] To obtain an accurate camshaft phase delay angle, in one optional implementation, before obtaining the camshaft phase delay angle by querying the delay angle mapping relationship based on the engine speed and engine torque, the method further includes:

[0060] Step S401: Adjust the engine speed within the first predetermined range and adjust the engine torque within the second predetermined range to obtain the engine test speed and engine test torque.

[0061] Step S402: Control the camshaft phase to be delayed relative to the crankshaft phase until the maximum difference in the EGR rate of each cylinder is less than the first difference threshold and the maximum difference in the peak cylinder pressure of each cylinder is less than the second difference threshold, so as to obtain the camshaft phase delay angle corresponding to the engine test speed and the engine test torque.

[0062] Step S403: Establish the delay angle mapping relationship based on the engine test speed, the engine test torque and the corresponding camshaft phase delay angle.

[0063] In the above implementation, the EGR rate of each cylinder is tested during engine calibration, and the peak cylinder pressure of each cylinder is recorded simultaneously. Based on the test results, the operating conditions where the consistency of EGR rate or peak cylinder pressure is relatively poor are identified. The corresponding first and second predetermined ranges are used as observation windows. Within these observation windows, the camshaft phase is adjusted to delay the intake valve opening time, which helps reduce in-cylinder exhaust gas backflow and improve the consistency of EGR rate. This process continues until the consistency of EGR rate and peak cylinder pressure in each cylinder reaches a reasonable level. The camshaft phase delay angle at this point is recorded as a control target map, i.e., the delay angle mapping relationship. Generally, the lower the engine speed and load, the larger the camshaft phase delay angle will be.

[0064] To ensure engine performance, in one optional embodiment, when the engine is under the aforementioned low-speed, low-load operating conditions, the camshaft phase is controlled to be delayed relative to the crankshaft phase, thereby delaying the intake valve opening of the engine. The method further includes:

[0065] Step S501: Adjust the fuel injection quantity of the engine according to the intake air volume of the engine to keep the air-fuel ratio constant.

[0066] In the above embodiments, after the intake valve opening of the engine is delayed, the intake air volume of the engine changes, and the fuel injection volume is dynamically adjusted to maintain a reasonable air-fuel ratio and ensure engine performance.

[0067] To meet the power demands of high speed and high load, in one optional implementation, after controlling the camshaft phase to be delayed relative to the crankshaft phase, thereby delaying the intake valve opening of the aforementioned engine, the method further includes:

[0068] Step S601: When the engine is not in the aforementioned low-speed, low-load operating condition, control the camshaft phase to restore the state before the crankshaft phase is delayed.

[0069] In the above implementation, since the fault caused by the inconsistency of EGR rate of each cylinder will be gradually eliminated as the speed or load increases, when the engine exits the low speed and low load condition, the camshaft phase is controlled to return to the state before the crankshaft phase was delayed, so as to avoid the inconsistency of EGR rate of each cylinder, ensure sufficient intake air volume, thereby ensuring engine performance and meeting the power demand of high speed and high load.

[0070] To enable those skilled in the art to better understand the technical solution of this application, the implementation process of the control method for the consistency of each cylinder of the engine in this application will be described in detail below with reference to specific embodiments.

[0071] This embodiment relates to a specific method for controlling the consistency of each cylinder in an engine, such as... Figure 5 As shown, it includes the following steps:

[0072] Step 1: Determine whether the outlet water temperature is greater than the limit W1 based on the outlet water temperature sensor signal. If yes, proceed to Step 2; otherwise, repeat Step 1.

[0073] Step 2: Determine whether the rate of change of accelerator pedal opening is less than the limit W2 based on the accelerator pedal opening sensor signal. If yes, proceed to Step 3; otherwise, return to Step 1.

[0074] Step 3: Determine whether the current engine speed and torque have entered the observation window based on the signals from the accelerator pedal opening sensor and the engine speed sensor. If yes, proceed to Step 4; otherwise, return to Step 1.

[0075] Step 4: Determine if the duration of the observation window exceeds the limit W3. If yes, proceed to Step 5; otherwise, return to Step 1.

[0076] Step 5: Adjust the camshaft phase based on the signals from the crankshaft phase sensor and camshaft phase sensor to delay the intake valve opening time, and then proceed to Step 6.

[0077] Step Six: Determine whether the phase adjustment meets the preset value based on the intake valve opening time delay map. If yes, proceed to Step Seven; otherwise, return to Step Five.

[0078] Step 7: Dynamically adjust the fuel injection quantity to maintain a reasonable air-fuel ratio. Then return to Step 1.

[0079] This application also provides a control device for the consistency of each cylinder of an engine. It should be noted that the control device for the consistency of each cylinder of an engine in this application can be used to execute the control method for the consistency of each cylinder of an engine provided in this application. This device is used to implement the above embodiments and preferred embodiments, and details already described will not be repeated. As used below, the term "module" can refer to a combination of software and / or hardware that implements a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0080] The following describes the control device for the consistency of each cylinder of the engine provided in the embodiments of this application.

[0081] Figure 6 This is a schematic diagram of a control device for the consistency of each cylinder of an engine according to an embodiment of this application. Figure 6 As shown, the device includes:

[0082] The first acquisition unit 10 is used to acquire the engine speed and torque, and obtain the engine speed and engine torque;

[0083] Specifically, engine speed is collected by a speed sensor, and engine torque is calculated based on speed and power.

[0084] The first determining unit 20 is used to determine that the engine is in a low-speed, low-load operating condition when the engine speed is within a first predetermined range and the engine torque is within a second predetermined range.

[0085] Specifically, by setting a first predetermined range and a second predetermined range corresponding to low-speed and low-load operating conditions, such that the engine speed is within the first predetermined range and the engine torque is within the second predetermined range, it can be determined that the engine is in a low-speed and low-load operating condition.

[0086] The first control unit 30 is used to control the camshaft phase to be delayed relative to the crankshaft phase when the engine is in the low-speed, low-load condition, so that the intake valve opening of the engine is delayed.

[0087] Specifically, when the engine is operating under the aforementioned low-speed and low-load conditions, delaying the intake valve opening time by adjusting the camshaft phase can reduce the amount of exhaust gas returning to the cylinder, thereby improving the consistency of EGR rate across all cylinders.

[0088] In this embodiment, the intake valve of the engine opens before the piston reaches top dead center, causing exhaust gas to flow back into the intake manifold, resulting in inconsistent actual EGR rates among the engine cylinders. However, this phenomenon gradually disappears when the engine speed or load is high. Therefore, this method collects engine speed and engine torque. If the engine speed is within a first predetermined range and the engine torque is within a second predetermined range, it determines that the engine is in a low-speed, low-load condition. It controls the camshaft phase to be delayed relative to the crankshaft phase, thereby delaying the opening of the engine intake valve to reduce the amount of exhaust gas flowing back, thus improving the consistency of the actual EGR rate among the engine cylinders and solving the problem of poor consistency of the actual EGR rate among the engine cylinders in the prior art.

[0089] To avoid affecting cold start and torque response, in one optional implementation, the control unit includes:

[0090] The acquisition module is used to acquire the rate of change of accelerator pedal opening and the engine coolant temperature;

[0091] The first control module is used to control the camshaft phase to be delayed relative to the crankshaft phase when the accelerator pedal opening change rate is less than the opening threshold, the water outlet temperature is greater than the temperature threshold, and the engine is in the low-speed, low-load condition. This results in a delay in the opening of the engine's intake valve.

[0092] In the above embodiments, a temperature threshold, namely temperature limit W1, is set. Only when the outlet water temperature is greater than the temperature threshold is the camshaft phase delayed relative to the crankshaft phase controlled to avoid starting difficulties caused by intake valve opening delay at low temperatures and ensure that the vehicle can start normally in cold conditions. An opening threshold, namely accelerator pedal opening change rate limit W2, is set. Only when the accelerator pedal opening change rate is less than the opening threshold is the camshaft phase delayed relative to the crankshaft phase controlled to avoid deterioration in acceleration responsiveness caused by intake valve opening delay and ensure the driver's driving experience. Therefore, the camshaft phase is delayed relative to the crankshaft phase only when the accelerator pedal opening change rate is less than the opening threshold, the outlet water temperature is greater than the temperature threshold, and the engine is in the low-speed, low-load condition, thus avoiding affecting engine performance.

[0093] To prevent engine malfunctions, in one optional implementation, the control unit further includes:

[0094] The second control module is used to control the camshaft phase to be delayed relative to the crankshaft phase when the duration of the engine being in the low-speed, low-load condition exceeds a duration threshold, thereby delaying the opening of the engine's intake valve.

[0095] In the above embodiments, a time threshold is set, namely the time limit W3 for entering the observation window. When the duration of the engine in the low-speed and low-load condition is greater than the time threshold, it indicates that the engine will be in the low-speed and low-load condition for a long time. This can control the camshaft phase to be delayed relative to the crankshaft phase, thus avoiding abnormal engine status caused by frequent switching.

[0096] To ensure the consistency of the actual EGR rate of each cylinder, in one optional implementation, the control unit further includes:

[0097] The query module is used to query the delay angle mapping relationship based on the engine speed and engine torque when the engine is under the low speed and low load conditions, and obtain the camshaft phase delay angle. The delay angle mapping relationship is the mapping relationship between the camshaft phase delay angle, the engine speed and the engine torque.

[0098] The third control module is used to control the camshaft phase to be delayed relative to the crankshaft phase by the camshaft phase delay angle.

[0099] In the above embodiments, by obtaining the mapping relationship of the engine torque obtained from the test, i.e. the intake valve opening time delay map, the camshaft phase delay angle can be obtained by querying the delay angle mapping relationship between the engine speed and the engine torque. By controlling the camshaft phase to be delayed relative to the crankshaft phase by the camshaft phase delay angle, the EGR rate and peak cylinder pressure of each cylinder can reach a reasonable level.

[0100] In an optional embodiment, to determine the first predetermined range and the second predetermined range, the above-mentioned apparatus further includes:

[0101] The data acquisition unit is used to adjust the engine speed and torque before determining that the engine is in a low-speed, low-load condition when the engine speed is within a first predetermined range and the engine torque is within a second predetermined range, and to acquire the maximum difference in EGR rate and the maximum difference in peak cylinder pressure of each cylinder corresponding to each engine speed and each torque.

[0102] The second determining unit is used to determine the speed range in which the maximum difference in EGR rate of each cylinder is greater than or equal to a first difference threshold and the maximum difference in peak cylinder pressure of each cylinder is greater than or equal to a second difference threshold as the aforementioned first predetermined range.

[0103] The third determining unit is used to determine the torque range in which the maximum difference in EGR rate of each cylinder is greater than or equal to the first difference threshold and the maximum difference in peak cylinder pressure of each cylinder is greater than or equal to the second difference threshold as the second predetermined range.

[0104] In the above embodiments, different types of engines have different parameters, and the first predetermined range and the second predetermined range corresponding to low-speed and low-load conditions are also different. During laboratory testing, the engine speed and torque are adjusted to determine the speed range and torque range where the maximum difference in EGR rate of each cylinder is greater than or equal to the first difference threshold and the maximum difference in peak cylinder pressure of each cylinder is greater than or equal to the second difference threshold. The first predetermined range and the second predetermined range can then be obtained.

[0105] To obtain an accurate camshaft phase delay angle, in one optional embodiment, the above-mentioned device further includes:

[0106] The second acquisition unit is used to obtain the engine speed within the first predetermined range and the engine torque within the second predetermined range before obtaining the camshaft phase delay angle by querying the delay angle mapping relationship based on the engine speed and the engine torque, thereby obtaining the engine speed and torque, and obtaining the engine test speed and engine test torque.

[0107] The test unit is used to control the camshaft phase to be delayed relative to the crankshaft phase until the maximum difference in the EGR rate of each cylinder is less than the first difference threshold and the maximum difference in the peak cylinder pressure of each cylinder is less than the second difference threshold, so as to obtain the camshaft phase delay angle corresponding to the engine test speed and the engine test torque.

[0108] The establishment unit is used to establish the delay angle mapping relationship based on the engine test speed, the engine test torque and the corresponding camshaft phase delay angle.

[0109] In the above implementation, the EGR rate of each cylinder is tested during engine calibration, and the peak cylinder pressure of each cylinder is recorded simultaneously. Based on the test results, the operating conditions where the consistency of EGR rate or peak cylinder pressure is relatively poor are identified. The corresponding first and second predetermined ranges are used as observation windows. Within these observation windows, the camshaft phase is adjusted to delay the intake valve opening time, which helps reduce in-cylinder exhaust gas backflow and improve the consistency of EGR rate. This process continues until the consistency of EGR rate and peak cylinder pressure in each cylinder reaches a reasonable level. The camshaft phase delay angle at this point is recorded as a control target map, i.e., the delay angle mapping relationship. Generally, the lower the engine speed and load, the larger the camshaft phase delay angle will be.

[0110] To ensure engine performance, in one optional embodiment, the above-mentioned device further includes:

[0111] The adjustment unit is used to control the camshaft phase to be delayed relative to the crankshaft phase when the engine is under the aforementioned low-speed and low-load operating conditions, so that after the intake valve opening of the engine is delayed, the fuel injection quantity of the engine is adjusted according to the intake air volume of the engine to keep the air-fuel ratio constant.

[0112] In the above embodiments, after the intake valve opening of the engine is delayed, the intake air volume of the engine changes, and the fuel injection volume is dynamically adjusted to maintain a reasonable air-fuel ratio and ensure engine performance.

[0113] To meet the power demands of high speed and high load, in one optional embodiment, the above-mentioned device further includes:

[0114] The second control unit is used to control the camshaft phase to return to the state before the delay when the engine is not in the low-speed, low-load operating condition, after delaying the intake valve opening of the engine by controlling the camshaft phase to be delayed relative to the crankshaft phase.

[0115] In the above implementation, since the fault caused by the inconsistency of EGR rate of each cylinder will be gradually eliminated as the speed or load increases, when the engine exits the low speed and low load condition, the camshaft phase is controlled to return to the state before the crankshaft phase was delayed, so as to avoid the inconsistency of EGR rate of each cylinder, ensure sufficient intake air volume, thereby ensuring engine performance and meeting the power demand of high speed and high load.

[0116] The aforementioned engine cylinder consistency control device includes a processor and a memory. The first acquisition unit, determination unit, and first control unit are all stored as program units in the memory, and the processor executes the program units stored in the memory to achieve the corresponding functions. All of the above modules are located in the same processor; alternatively, the modules may be located in different processors in any combination.

[0117] The processor contains a kernel, which retrieves the corresponding program units from memory. One or more kernels can be configured, and adjusting kernel parameters can address the problem of inconsistent actual EGR rates across different cylinders in existing engines.

[0118] The memory may include non-permanent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM, and the memory includes at least one memory chip.

[0119] This invention provides a computer-readable storage medium including a stored program, wherein, when the program is executed, it controls the device containing the computer-readable storage medium to perform the control method for the consistency of each cylinder of the engine.

[0120] Specifically, the control methods for the consistency of each cylinder in the engine include:

[0121] Step S201: Obtain the engine speed and torque to get the engine speed and engine torque;

[0122] Specifically, engine speed is collected by a speed sensor, and engine torque is calculated based on speed and power.

[0123] Step S202: When the engine speed is within a first predetermined range and the engine torque is within a second predetermined range, it is determined that the engine is in a low-speed, low-load operating condition.

[0124] Specifically, by setting a first predetermined range and a second predetermined range corresponding to low-speed and low-load operating conditions, such that the engine speed is within the first predetermined range and the engine torque is within the second predetermined range, it can be determined that the engine is in a low-speed and low-load operating condition.

[0125] Step S203: When the engine is in the low-speed, low-load condition, the camshaft phase is delayed relative to the crankshaft phase, thereby delaying the opening of the engine's intake valve.

[0126] Specifically, when the engine is operating under the aforementioned low-speed and low-load conditions, delaying the intake valve opening time by adjusting the camshaft phase can reduce the amount of exhaust gas returning to the cylinder, thereby improving the consistency of EGR rate across all cylinders.

[0127] This invention provides a processor for running a program, wherein the program executes the control method for the consistency of each cylinder of the engine.

[0128] Specifically, the control methods for the consistency of each cylinder in the engine include:

[0129] Step S201: Obtain the engine speed and torque to get the engine speed and engine torque;

[0130] Specifically, engine speed is collected by a speed sensor, and engine torque is calculated based on speed and power.

[0131] Step S202: When the engine speed is within a first predetermined range and the engine torque is within a second predetermined range, it is determined that the engine is in a low-speed, low-load operating condition.

[0132] Specifically, by setting a first predetermined range and a second predetermined range corresponding to low-speed and low-load operating conditions, such that the engine speed is within the first predetermined range and the engine torque is within the second predetermined range, it can be determined that the engine is in a low-speed and low-load operating condition.

[0133] Step S203: When the engine is in the low-speed, low-load condition, the camshaft phase is delayed relative to the crankshaft phase, thereby delaying the opening of the engine's intake valve.

[0134] Specifically, when the engine is operating under the aforementioned low-speed and low-load conditions, delaying the intake valve opening time by adjusting the camshaft phase can reduce the amount of exhaust gas returning to the cylinder, thereby improving the consistency of EGR rate across all cylinders.

[0135] This invention provides a vehicle, which includes a processor, a memory, and a program stored in the memory and executable on the processor. When the processor executes the program, it performs at least the following steps:

[0136] Step S201: Obtain the engine speed and torque to get the engine speed and engine torque;

[0137] Specifically, engine speed is collected by a speed sensor, and engine torque is calculated based on speed and power.

[0138] Step S202: When the engine speed is within a first predetermined range and the engine torque is within a second predetermined range, it is determined that the engine is in a low-speed, low-load operating condition.

[0139] Specifically, by setting a first predetermined range and a second predetermined range corresponding to low-speed and low-load operating conditions, such that the engine speed is within the first predetermined range and the engine torque is within the second predetermined range, it can be determined that the engine is in a low-speed and low-load operating condition.

[0140] Step S203: When the engine is in the low-speed, low-load condition, the camshaft phase is delayed relative to the crankshaft phase, thereby delaying the opening of the engine's intake valve.

[0141] Specifically, when the engine is operating under the aforementioned low-speed and low-load conditions, delaying the intake valve opening time by adjusting the camshaft phase can reduce the amount of exhaust gas returning to the cylinder, thereby improving the consistency of EGR rate across all cylinders.

[0142] This application also provides a computer program product, which, when executed on a data processing device, is suitable for executing an initialization program having at least the following method steps:

[0143] Step S201: Obtain the engine speed and torque to get the engine speed and engine torque;

[0144] Specifically, engine speed is collected by a speed sensor, and engine torque is calculated based on speed and power.

[0145] Step S202: When the engine speed is within a first predetermined range and the engine torque is within a second predetermined range, it is determined that the engine is in a low-speed, low-load operating condition.

[0146] Specifically, by setting a first predetermined range and a second predetermined range corresponding to low-speed and low-load operating conditions, such that the engine speed is within the first predetermined range and the engine torque is within the second predetermined range, it can be determined that the engine is in a low-speed and low-load operating condition.

[0147] Step S203: When the engine is in the low-speed, low-load condition, the camshaft phase is delayed relative to the crankshaft phase, thereby delaying the opening of the engine's intake valve.

[0148] Specifically, when the engine is operating under the aforementioned low-speed and low-load conditions, delaying the intake valve opening time by adjusting the camshaft phase can reduce the amount of exhaust gas returning to the cylinder, thereby improving the consistency of EGR rate across all cylinders.

[0149] It is obvious to those skilled in the art that the modules or steps of the present invention described above can be implemented using general-purpose computing devices. They can be centralized on a single computing device or distributed across a network of multiple computing devices. They can be implemented using computer-executable program code, and thus can be stored in a storage device for execution by a computing device. In some cases, the steps shown or described can be performed in a different order than those described herein, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. Thus, the present invention is not limited to any particular combination of hardware and software.

[0150] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0151] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0152] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0153] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0154] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0155] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, like read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0156] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0157] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0158] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0159] As can be seen from the above description, the embodiments of this application achieve the following technical effects:

[0160] 1) In the engine cylinder consistency control method of this application, the engine intake valve opens before the piston exhaust top dead center, resulting in exhaust gas backflow into the intake manifold, causing the actual EGR rate of each engine cylinder to be inconsistent. However, this phenomenon will gradually disappear when the speed or load is high. Therefore, this method collects engine speed and engine torque. If the engine speed is within a first predetermined range and the engine torque is within a second predetermined range, it is determined that the engine is in a low-speed and low-load condition. The camshaft phase is controlled to be delayed relative to the crankshaft phase, so that the opening of the engine intake valve is delayed, thereby reducing the amount of exhaust gas backflow, thereby improving the consistency of the actual EGR rate of each engine cylinder, and solving the problem of poor consistency of the actual EGR rate of each engine cylinder in the prior art.

[0161] 2) In the engine cylinder consistency control device of this application, the engine intake valve opens before the piston exhaust top dead center, resulting in exhaust gas backflow into the intake manifold, causing the actual EGR rate of each engine cylinder to be inconsistent. However, this phenomenon will gradually disappear when the speed or load is high. Therefore, this method collects the engine speed and engine torque. If the engine speed is within a first predetermined range and the engine torque is within a second predetermined range, it is determined that the engine is in a low-speed and low-load condition. The camshaft phase is controlled to be delayed relative to the crankshaft phase, so that the opening of the engine intake valve is delayed, thereby reducing the amount of exhaust gas backflow, thereby improving the consistency of the actual EGR rate of each engine cylinder, and solving the problem of poor consistency of the actual EGR rate of each engine cylinder in the prior art.

[0162] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. 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 method for controlling the consistency of each cylinder in an engine, characterized in that, include: Obtain the engine speed and torque; When the engine speed is within a first predetermined range and the engine torque is within a second predetermined range, it is determined that the engine is in a low-speed, low-load operating condition. When the engine is in the low-speed, low-load condition, the camshaft phase is delayed relative to the crankshaft phase, thereby delaying the opening of the engine's intake valves. When the engine is operating at low speed and low load, controlling the camshaft phase to be delayed relative to the crankshaft phase, thereby delaying the opening of the engine's intake valves, includes: acquiring the accelerator pedal opening change rate and the engine's coolant temperature; when the accelerator pedal opening change rate is less than an opening threshold, the coolant temperature is greater than a temperature threshold, and the engine is operating at low speed and low load, controlling the camshaft phase to be delayed relative to the crankshaft phase, thereby delaying the opening of the engine's intake valves. Before determining that the engine is in a low-speed, low-load condition when the engine speed is within a first predetermined range and the engine torque is within a second predetermined range, the method further includes: adjusting the engine speed and torque, and collecting the maximum difference in EGR rate and the maximum difference in peak cylinder pressure of each cylinder corresponding to each speed and torque; determining the speed range in which the maximum difference in EGR rate of each cylinder is greater than or equal to a first difference threshold and the maximum difference in peak cylinder pressure of each cylinder is greater than or equal to a second difference threshold as the first predetermined range; and determining the torque range in which the maximum difference in EGR rate of each cylinder is greater than or equal to the first difference threshold and the maximum difference in peak cylinder pressure of each cylinder is greater than or equal to the second difference threshold as the second predetermined range.

2. The method according to claim 1, characterized in that, When the engine is operating at low speed and low load, controlling the camshaft phase to be delayed relative to the crankshaft phase, thereby delaying the opening of the engine's intake valves, further includes: When the duration of the engine operating under the low-speed, low-load condition exceeds a duration threshold, the camshaft phase is controlled to be delayed relative to the crankshaft phase, thereby delaying the opening of the engine's intake valves.

3. The method according to claim 1, characterized in that, When the engine is operating under the low-speed, low-load condition, controlling the camshaft phase to be delayed relative to the crankshaft phase, thereby delaying the intake valve opening of the engine, further includes: When the engine is in the low-speed, low-load condition, the camshaft phase delay angle is obtained by querying the delay angle mapping relationship between the engine speed and the engine torque. The delay angle mapping relationship is the mapping relationship between the camshaft phase delay angle, the engine speed, and the engine torque. The camshaft phase is controlled to be delayed relative to the crankshaft phase by a camshaft phase delay angle.

4. The method according to claim 3, characterized in that, Before obtaining the camshaft phase delay angle based on the engine speed and engine torque lookup delay angle mapping relationship, the method further includes: The engine speed is adjusted within the first predetermined range, and the engine torque is adjusted within the second predetermined range to obtain the engine test speed and engine test torque. The camshaft phase is delayed relative to the crankshaft phase until the maximum difference in EGR rate of each cylinder is less than a first difference threshold and the maximum difference in peak cylinder pressure of each cylinder is less than a second difference threshold, thereby obtaining the camshaft phase delay angle corresponding to the engine test speed and the engine test torque. The delay angle mapping relationship is established based on the engine test speed, the engine test torque, and the corresponding camshaft phase delay angle.

5. The method according to claim 1, characterized in that, When the engine is operating under the low-speed, low-load condition, after controlling the camshaft phase to be delayed relative to the crankshaft phase, thereby delaying the opening of the engine's intake valves, the method further includes: The fuel injection quantity of the engine is adjusted according to the intake air volume of the engine so that the air-fuel ratio remains constant.

6. The method according to claim 1, characterized in that, After controlling the camshaft phase to be delayed relative to the crankshaft phase, thereby delaying the opening of the engine's intake valves, the method further includes: When the engine is not in the low-speed, low-load condition, the camshaft phase is controlled to return to its previous state relative to the crankshaft phase.

7. A control device for the consistency of each cylinder in an engine, characterized in that, include: The first acquisition unit is used to acquire the engine speed and torque, and obtain the engine speed and engine torque; The first determining unit is configured to determine that the engine is in a low-speed, low-load operating condition when the engine speed is within a first predetermined range and the engine torque is within a second predetermined range. A first control unit is configured to control the camshaft phase to be delayed relative to the crankshaft phase when the engine is in the low-speed, low-load condition, thereby delaying the opening of the engine's intake valves. The control unit includes: an acquisition module for acquiring the accelerator pedal opening change rate and the engine coolant temperature; and a first control module for controlling the camshaft phase to be delayed relative to the crankshaft phase, so that the engine intake valve opening is delayed, when the accelerator pedal opening change rate is less than the opening threshold, the coolant temperature is greater than the temperature threshold, and the engine is in the low-speed, low-load condition. The data acquisition unit is used to adjust the engine speed and torque before determining that the engine is in a low-speed, low-load condition when the engine speed is within a first predetermined range and the engine torque is within a second predetermined range, and to acquire the maximum difference in EGR rate and the maximum difference in peak cylinder pressure of each cylinder corresponding to each speed and torque. The second determining unit is used to determine the speed range in which the maximum difference in EGR rate of each cylinder is greater than or equal to a first difference threshold and the maximum difference in peak cylinder pressure of each cylinder is greater than or equal to a second difference threshold as the first predetermined range. The third determining unit is used to determine the torque range in which the maximum difference in EGR rate of each cylinder is greater than or equal to the first difference threshold and the maximum difference in peak cylinder pressure of each cylinder is greater than or equal to the second difference threshold as the second predetermined range.

8. A vehicle, characterized in that, include: One or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the one or more programs comprising methods for performing any one of claims 1 to 6.

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