Engine ignition control redundancy system of unmanned aircraft

Abstract

The present invention provides a relatively lightweight secondary ignition system by "replicating" the primary ignition system, providing ignition system redundancy when the primary ignition system fails. According to the system, the unmanned aerial vehicle can return to a base or land in a safe area, and greater loss is avoided. The invention provides an ignition system for a drone spark ignition engine, the ignition system comprising a primary ignition system providing a first spark energy and / or an ignition spark of a duration, and a secondary ignition system providing a second spark energy and / or an ignition spark of a duration, the secondary ignition system provides a second spark energy and / or an ignition spark of a duration in order to ignite the fuel-air mixture in the event that the primary ignition system is inoperative or partially operative, and the secondary ignition system provides an ignition spark of a second spark energy and / or duration in order to ignite the fuel-air mixture in the event that the primary ignition system is inoperative or partially operative. Wherein the second spark energy or duration is less than the respective first spark energy or duration.

Description

Technical Field

[0001] The invention relates to an ignition control and an ignition system for an unmanned aerial vehicle engine, and is particularly suitable for the redundancy of the ignition control and ignition system of an unmanned aerial vehicle engine using heavy fuel. Background Art

[0002] Unmanned aerial vehicles (UAVs) are required to have endurance and durability in the air. To help achieve this, non-essential components and control systems are omitted whenever possible and made lightweight.

[0003] The ignition system is an important engine control system. Without the ignition system, the UAV engine will not start or continue to operate. However, minimizing the number of components in the ignition system, especially when it may affect any redundancy capabilities, will lead to an increased risk of engine failure, which may ultimately cause the UAV to crash and harm the safety of life and property on the ground.

[0004] To maintain reliability, more and stronger components can be used. However, this often leads directly to an increase in the weight of the UAV. The robustness of a component often requires more material or features to allow the component to better withstand shock, vibration, extreme temperatures, and temperature changes. This need for component robustness is more relevant to UAVs, which must cope with harsh environmental conditions at high altitudes for a long time. In terms of reliability, there is only one onboard ignition system, and any failure of any part of the ignition system can be devastating to the entire UAV system.

[0005] Therefore, full redundancy of the ignition system is beneficial. This can obviously be achieved by duplicating the main ignition system. The benefit of such duplication of the main ignition system is that the components of both systems are exactly the same, making spare parts and maintenance easier to manage.

[0006] However, two completely identical ignition systems will inevitably increase the overall weight, volume and cost. Taking the above problems into consideration, the present invention provides an ignition system for a UAV, which can not only realize the redundancy of the ignition system, but also reduce the weight of the UAV system and reduce the redundancy cost. Summary of the invention

[0007] The present invention provides an ignition system for a spark ignition engine of an unmanned aerial vehicle, the ignition system comprising a main ignition system and a secondary ignition system, wherein the main ignition system provides an ignition spark with a first spark energy and / or duration so as to burn a fuel-air mixture under normal operating conditions of the engine, and the secondary ignition system provides an ignition spark with a second spark energy and / or duration so as to ignite the fuel-air mixture when the main ignition system fails to work or partially works, wherein the second spark energy or duration is less than the respective first spark energy or duration.

[0008] It is understood that a secondary ignition system having a lower capacity than the primary ignition system of the engine and the primary ignition system of the UAV engine is particularly suitable for redundancy purposes. Such a lower capacity system may be a secondary ignition system wherein the secondary spark energy is lower than the primary ignition system and the discharge spark duration is shorter than the duration of the primary ignition system.

[0009] Thus, compared to the primary ignition system, the secondary ignition system of the present invention can provide sufficient spark energy and spark duration to maintain ignition of the fuel-air mixture under a limited range of operating conditions, and the engine can continue to fly the UAV within a limited range and return to the take-off point or base for maintenance.

[0010] In addition, the secondary ignition system works simultaneously with the primary ignition system. If the control strategy of the engine electronic management unit (ECU) starts the secondary ignition system only after confirming that the primary ignition system has completely failed, the engine may have been shut down and the secondary ignition system is not sufficient to restart the engine, exposing the drone to a dangerous environment.

[0011] If the primary ignition system is operating properly, the simultaneous operation of the primary and secondary sparks during normal engine operation may adversely affect the fuel-air combustion characteristics. For example, if the secondary spark occurs before the primary spark or if the flame front after the primary spark injection does not have enough time to expand before the secondary spark injection, the combustion characteristics will be affected, which may result in poor fuel economy, reduced power or engine combustion instability, thereby reducing engine performance.

[0012] Therefore, the secondary ignition spark is preferably delayed in time relative to the primary ignition spark and may occur after the primary flame front has spread through the combustion chamber. Operating in this manner mitigates any adverse effects that the secondary ignition spark may have on normal combustion and engine operation. Once a primary ignition system failure is detected, if necessary, the delay of the secondary spark may be eliminated and an ignition timing correction may be made to advance the timing of the secondary ignition spark. Also, the engine may thus be placed into a safe operating state, i.e., a "limp home" mode. Operation in a "limp home" mode will typically use or require a retarded spark, so a decision may be made to maintain a retarded timing for the secondary ignition spark.

[0013] The method may include operating a primary ignition system spark and a secondary ignition system spark during normal engine operation, the secondary ignition spark being delayed in time relative to the primary ignition system spark and propagating through respective paths at the primary ignition system flame front.

[0014] When the primary ignition system fails and the secondary ignition system is working, the engine injection pulse width and advance angle, jet pulse width and advance angle can be modified to ensure that the secondary ignition system maintains the engine operation while ensuring that the air-fuel ratio is within a reasonable range. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Ignition Control Redundancy System Example

[0016] Figure 2 When the main ignition system fails, the main and secondary ignition timing adjustment diagram

[0017] Figure 3 Schematic diagram of the engine electronic management unit (ECU) and primary and secondary ignition systems

[0018] Figure 1 In the middle, 100 is the cylinder head, 21 is the main spark plug, 22 is the main ignition coil, 23 is the main high-voltage wire, 31 is the secondary spark plug, 32 is the secondary ignition coil, and 33 is the secondary high-voltage wire;

[0019] Figure 2 In the middle, PIS is the main ignition system spark, SIS is the secondary ignition system spark, S1 is the fault occurrence point, and S2 is the fault detection point;

[0020] Figure 3 In the middle, 1 is the engine electronic management unit (ECU), 12 is the low-pressure area of ​​the ignition system, 13 is the high-pressure area of ​​the ignition system, 20 is the main ignition system, 21 is the main spark plug, 30 is the secondary ignition system, and 31 is the secondary spark plug; DETAILED DESCRIPTION

[0021] Figure 2 Here is a fault example. Both the PIS position and the SIS position occur a few degrees before the top dead center, and the PIS position is more advanced than the SIS position. Before the S1 point is reached, the primary and secondary ignition systems are both in operation, and both spark plugs are igniting. The SIS ignition is delayed relative to the PIS.

[0022] After the S1 point is reached, the primary ignition system fails and the mixture in the combustion chamber is ignited by the secondary ignition system. However, due to the delay in the ignition spark, the ignition timing is not ideal and the maximum pressure in the cylinder is delayed, resulting in relatively large fluctuations in the engine speed.

[0023] Therefore, between S1 and S2, the engine electronic control unit (ECU) detects a malfunction in the primary ignition system and adjusts the secondary ignition system timing to a more advanced position or to the timing of the primary ignition system. This helps stabilize combustion and maintain engine performance and fuel economy.

[0024] When the main ignition system is working normally, the engine will give priority to stratified lean combustion until the S1 point is reached. If the main ignition system fails, the engine injection strategy should be immediately changed to a homogeneous combustion strategy.

[0025] Figure 3 The figure is a schematic diagram of the engine electronic management unit (ECU) and the primary and secondary ignition systems. The engine electronic management unit (ECU) 1 is connected to the primary ignition system 20 and the secondary ignition system 30. When the engine is working normally, the primary ignition system 20 works. If the primary ignition system fails, the secondary ignition system 30 takes over. The engine electronic management unit (ECU) 1 has the ability to detect the failure of the primary ignition system.

[0026] The hardware level includes open circuit load detection, ground short circuit detection, and ignition coil short circuit detection.

[0027] The software level includes fault detection strategies. For example, if the engine speed fluctuates abnormally, the engine electronic management unit (ECU) 1 assumes that the primary ignition system has failed and adjusts the timing of the secondary ignition system to observe the effect to determine the assumption.

[0028] Fault detection may also include the engine electronic management unit (ECU) 1 detecting the high voltage area 13 to determine whether the main spark plug 21 has sparks.

Claims

1. An unmanned aerial vehicle engine ignition control redundancy system, the system comprising a primary ignition system and a secondary ignition system, the primary ignition system providing a stronger main ignition energy to ignite a mixture when the engine is operating normally, and the secondary ignition system providing a relatively small ignition energy slightly later, wherein the duration and ignition energy of the secondary ignition system are both less than those of the primary ignition system.

2. The ignition system of claim 1, wherein the primary ignition system comprises an inductive discharge coil and the secondary ignition system comprises a capacitive discharge coil.

3. According to the ignition system of claims 1 and 2, the primary ignition system includes a primary spark plug and the secondary ignition system includes a secondary spark plug.

4. The ignition system as claimed in the above claims is connected to an engine electronic control unit (ECU).

5. According to the ignition system of claim 4, the engine electronic control unit (ECU) includes a detection device for detecting a main ignition system failure.

6. The ignition system as claimed in the above claim, wherein the primary ignition system and the secondary ignition system operate continuously during the operation of the engine.

7. The ignition system according to claim 6, wherein the secondary ignition system formally intervenes in operation after detecting failure of the primary ignition system.

8. The ignition system according to claim 5, 6, 7, wherein the spark of the secondary ignition system is delayed relative to the spark of the primary ignition system.

9. The ignition system according to claim 5 to 8, wherein after the primary ignition system fails, the secondary ignition system spark advances.

10. The ignition system according to claims 5 to 9, wherein when the engine electronic control unit (ECU) detects that the voltage in the low voltage area is lower than a threshold value, the secondary ignition system ignites in advance.

11. The ignition system according to claims 5 to 10, wherein when the secondary ignition system plays a primary role, the engine electronic control unit (ECU) switches the injection strategy.

12. The ignition system of claim 11, comprising switching the combustion mode between stratified lean combustion and homogeneous combustion.

13. An unmanned aircraft engine according to the method of any one of claims 5 to 12.

Images