阅读说明：本技术 一种用于大功率甲醇发动机的点火系统及点火方法 (Ignition system and ignition method for high-power methanol engine ) 是由 郭立书 杨永亮 周晓雪 于 2020-05-13 设计创作，主要内容包括：本发明提供了一种用于大功率甲醇发动机的点火系统及点火方法,属于大功率甲醇发动机领域。该点火系统包括：多组火花塞,分别对应布置于所述大功率甲醇发动机的各个气缸缸盖处,每组所述火花塞均包括主火花塞和副火花塞；控制器,用于控制各组所述火花塞以预设顺序依次点火,并控制每组所述火花塞的所述主火花塞和所述副火花塞同时点火。本发明还提供了用于上述点火系统的点火方法。本发明用于大功率甲醇发动机的点火系统和点火方法能够提高燃烧热效率和经济性。(The invention provides an ignition system and an ignition method for a high-power methanol engine, and belongs to the field of high-power methanol engines. The ignition system includes: the high-power methanol engine comprises a plurality of groups of spark plugs, a plurality of groups of spark plugs and a plurality of groups of spark plugs, wherein the plurality of groups of spark plugs are respectively and correspondingly arranged on each cylinder cover of the high-power methanol engine; and the controller is used for controlling the spark plugs of each group to sequentially ignite in a preset sequence and controlling the main spark plug and the auxiliary spark plug of each group to simultaneously ignite. The invention also provides an ignition method for the ignition system. The ignition system and the ignition method for the high-power methanol engine can improve the combustion heat efficiency and the economy.)

1. An ignition system for a high power methanol engine, comprising:

the high-power methanol engine comprises a plurality of groups of spark plugs, a plurality of groups of spark plugs and a plurality of groups of spark plugs, wherein the plurality of groups of spark plugs are respectively and correspondingly arranged on each cylinder cover of the high-power methanol engine;

and the controller is used for controlling the spark plugs of each group to sequentially ignite in a preset sequence and controlling the main spark plug and the auxiliary spark plug of each group to simultaneously ignite.

2. The ignition system for a high power methanol engine according to claim 1,

and the main spark plug and the auxiliary spark plug of each group of spark plugs are respectively positioned on two sides of a central connecting line of an exhaust valve and an intake valve on the cylinder cover of the cylinder.

3. The ignition system for a high-power methanol engine according to claim 1 or 2, characterized by further comprising:

a plurality of ignition coils, each of said ignition coils being connected to both said main spark plug and said auxiliary spark plug of each of said groups of spark plugs;

a plurality of ignition circuits in one-to-one correspondence with the plurality of ignition coils, each of the ignition circuits including an ignition control switch for controlling on/off of the ignition coil to store energy for the ignition coil when powered on and to control the ignition of the main spark plug and the auxiliary spark plug of each group of the spark plugs when powered off;

and the controller is connected with each ignition control switch and is used for controlling the on-off of the ignition loop.

4. The ignition system for a high power methanol engine according to claim 3,

the plurality of ignition control switches are integrated into one igniter.

5. The ignition system for a high power methanol engine as claimed in claim 3, wherein each of the ignition control switches is individually provided as an igniter.

6. An ignition method for a high-power methanol engine, which is used for the ignition system for the high-power methanol engine as claimed in any one of claims 1 to 5, and is characterized by comprising the following steps:

and controlling the ignition plugs of each group to sequentially ignite in a preset sequence, and controlling the main ignition plug and the auxiliary ignition plug of each group to simultaneously ignite.

7. The ignition method for a high-power methanol engine as claimed in claim 6, wherein the step of controlling the ignition plugs of each group to be sequentially ignited in a preset sequence and controlling the main ignition plug and the auxiliary ignition plug of each group to be simultaneously ignited comprises:

determining the ignition time of each group of spark plugs according to the rotating speed and the load of the high-power methanol engine;

and before the ignition time of each group of spark plugs, controlling the ignition coils of the corresponding main spark plugs and the corresponding auxiliary spark plugs to be electrified for preset electrifying time and to be powered off at the ignition time.

8. The ignition method for a high-power methanol engine according to claim 7,

the preset energization time is determined by a calibration experiment aimed at ensuring that the ignition energy meets the requirement for igniting the mixture in the high-power methanol engine.

9. The ignition method for a high-power methanol engine according to claim 7 or 8, characterized in that the preset energization time is determined in accordance with the kind of fuel and the concentration of the mixture.

Technical Field

The invention relates to the field of high-power methanol engines, in particular to an ignition system and an ignition method for a high-power methanol engine.

Background

The lower heating value of methanol fuel is much lower than that of gasoline, which is about 2.2564 times that of methanol, i.e. 2.2564 times that of gasoline fuel. The latent heat of vaporization of methanol is about 3.5806 times that of gasoline, that is, the same mass of fuel is atomized, and the methanol fuel is 3.5806 times that of gasoline fuel, so that the heat absorbed by the methanol fuel when the engine is operated to do the same work externally is about 8.079 times that of gasoline (2.2564 × 3.5806). When the engine works at low temperature, particularly when the engine is started at low temperature, the fuel of the methanol engine is difficult to atomize, the mixed gas is not formed well, and the ignition energy required for normal work of the engine is stronger than that of the traditional gasoline engine. Aiming at the problem that a high-power methanol engine is more difficult to burn than a traditional general methanol engine, the main reasons are as follows: one is that the engine comes from a diesel engine, which is more suitable for compression ignition rather than ignition; secondly, a high-power engine (the displacement is more than 11L, and the power is more than 340 horsepower) has large displacement and large combustion chamber space, and the mixed gas of the methanol engine is difficult to ensure to be reliably combusted by igniting the mixed gas in the combustion chamber by using a spark plug; thirdly, the high-power engine needs larger heat at low temperature, and the methanol mixed gas is more difficult to form, so stronger ignition energy is needed to make up for the deficiency of the quality of the methanol mixed gas.

The existing high-power methanol engine generally adopts the traditional single-spark-plug ignition mode. Because the combustion chamber of the high-power methanol engine has large volume and the concentration of the mixed gas at each part has certain difference, the methanol is difficult to atomize, the mixed gas at the position close to the spark plug is easy to burn, the mixed gas at the position far away from the spark plug is not burnt, and the methanol fuel which is not burnt reduces the economy of the engine on one hand, and on the other hand, the liquid methanol destroys a lubricating oil film between a piston ring and a cylinder sleeve of the engine, accelerates the abrasion of the engine, increases the air leakage of the engine, pollutes engine oil of the engine and influences the emission performance of the engine.

Disclosure of Invention

It is an object of a first aspect of the present invention to provide an ignition system for a high-power methanol engine capable of improving combustion thermal efficiency and economy.

It is another object of the invention to improve the reliability of the system.

It is an object of the second aspect of the present invention to provide an ignition method for a high-power methanol engine capable of improving combustion thermal efficiency and economy.

In particular, the present invention provides an ignition system for a high power methanol engine comprising:

the high-power methanol engine comprises a plurality of groups of spark plugs, a plurality of groups of spark plugs and a plurality of groups of spark plugs, wherein the plurality of groups of spark plugs are respectively and correspondingly arranged on each cylinder cover of the high-power methanol engine;

and the controller is used for controlling the spark plugs of each group to sequentially ignite in a preset sequence and controlling the main spark plug and the auxiliary spark plug of each group to simultaneously ignite.

Optionally, the main spark plug and the auxiliary spark plug of each group of spark plugs are respectively positioned on two sides of a central connecting line of an exhaust valve and an intake valve on the cylinder head.

Optionally, the ignition system for a high power methanol engine further comprises:

a plurality of ignition coils, each of said ignition coils being connected to both said main spark plug and said auxiliary spark plug of each of said groups of spark plugs;

a plurality of ignition circuits in one-to-one correspondence with the plurality of ignition coils, each of the ignition circuits including an ignition control switch for controlling on/off of the ignition coil to store energy for the ignition coil when powered on and to control the ignition of the main spark plug and the auxiliary spark plug of each group of the spark plugs when powered off;

and the controller is connected with each ignition control switch and is used for controlling the on-off of the ignition loop.

Optionally, the plurality of ignition control switches are integrated into one igniter.

Optionally, each of the ignition control switches is individually configured as an igniter.

In particular, the invention also provides an ignition method for the high-power methanol engine, which is used for the ignition system for the high-power methanol engine in any one of the above areas, and comprises the following steps:

and controlling the ignition plugs of each group to sequentially ignite in a preset sequence, and controlling the main ignition plug and the auxiliary ignition plug of each group to simultaneously ignite.

Optionally, the step of controlling the ignition plugs of each group to ignite sequentially in a preset sequence, and controlling the main ignition plug and the auxiliary ignition plug of each group to ignite simultaneously comprises:

determining the ignition time of each group of spark plugs according to the rotating speed and the load of the high-power methanol engine;

and before the ignition time of each group of spark plugs, controlling the ignition coils of the corresponding main spark plugs and the corresponding auxiliary spark plugs to be electrified for preset electrifying time and to be powered off at the ignition time.

Optionally, the preset energization time is determined by a calibration experiment aimed at ensuring that the ignition energy meets the requirement for ignition of the mixture in the high power methanol engine.

Alternatively, the preset energization time is determined in accordance with the kind of fuel and the concentration of the mixture.

The invention initiatively applies the ignition mode of the double spark plugs to the high-power methanol engine, and the main spark plug and the auxiliary spark plug respectively provide ignition energy, so that the ignition energy of the high-power methanol engine is increased, the combustion quality and the combustion speed of the fuel of the engine are obviously improved, and the thermal efficiency of the engine is improved. Moreover, for each cylinder, when one spark plug fails, the engine can still work, only partial combustion efficiency is sacrificed, and the reliability of the system can be improved.

Furthermore, the main spark plug and the auxiliary spark plug of each group of spark plugs are respectively positioned on two sides of a central connecting line of an exhaust valve and an intake valve on a cylinder cover of the cylinder, and the arrangement mode can ensure that mixed gas can be reliably combusted no matter a methanol nozzle positioned in the center of each cylinder or a gasoline nozzle injected by an air inlet channel or a manifold, so that the heat efficiency of the engine is improved.

Furthermore, the preset electrifying time is determined according to the type of the fuel and the concentration of the methanol mixed gas, and the electrifying time of the ignition coil is controlled according to different concentrations of the fuel and the mixed gas, so that the heat productivity of the ignition coil can be reduced, and the reliability of the ignition coil can be improved.

The above and other objects, advantages and features of the present invention will become more apparent to those skilled in the art from the following detailed description of specific embodiments thereof, taken in conjunction with the accompanying drawings.

Drawings

Some specific embodiments of the invention will be described in detail hereinafter, by way of illustration and not limitation, with reference to the accompanying drawings. The same reference numbers in the drawings identify the same or similar elements or components. Those skilled in the art will appreciate that the drawings are not necessarily drawn to scale. In the drawings:

FIG. 1 is a schematic diagram of an ignition system for a high power methanol engine according to one embodiment of the present invention;

FIG. 2 is a layout view of a spark plug for an ignition system of a high power methanol engine according to one embodiment of the present invention;

fig. 3 is an ignition timing diagram of an ignition system for a high power methanol engine according to one embodiment of the present invention.

Detailed Description

Fig. 1 is a schematic diagram of an ignition system for a high power methanol engine according to one embodiment of the present invention. In one embodiment, as shown in fig. 1, the ignition system for a high power methanol engine of the present invention includes a plurality of sets of spark plugs and a controller 20. The multiple groups of spark plugs are respectively and correspondingly arranged on each cylinder head of the high-power methanol engine, and each group of spark plugs comprises a main spark plug 11 and an auxiliary spark plug 12. The controller 20 is configured to control the ignition plugs of each group to sequentially ignite in a preset sequence, and control the main ignition plug 11 and the auxiliary ignition plug 12 of each group to simultaneously ignite.

In the embodiment, the ignition mode of the double spark plugs is applied to the high-power methanol engine for the first time, the main spark plug 11 and the auxiliary spark plug 12 provide ignition energy respectively, so that the ignition energy of the high-power methanol engine is increased, the combustion quality and the combustion speed of engine fuel are obviously improved, and the thermal efficiency of the engine is improved.

Further, for each cylinder, the system can continue to operate when one of the spark plugs fails, only partial combustion efficiency is sacrificed, and reliability of the system can be improved.

Fig. 2 is a layout view of a spark plug of an ignition system for a high-power methanol engine according to an embodiment of the present invention. In one embodiment, as shown in fig. 2, the main spark plug 11 and the auxiliary spark plug 12 of each group of spark plugs are located on both sides of a center-connecting line of the exhaust valve 13 and the intake valve 14 on the cylinder head 50, respectively. Alternatively, the main spark plug 11 and the sub spark plug 12 are located as close to the methanol nozzle 15 as possible.

The main spark plug 11 and the auxiliary spark plug 12 are respectively positioned at two sides of the central connecting line of the intake valve 14 and the exhaust valve 13, and the arrangement mode can ensure that the mixed gas can be reliably combusted no matter for a methanol nozzle 15 positioned at the center of each cylinder or a gasoline nozzle injected by an intake passage or a manifold, thereby improving the thermal efficiency of the engine.

Alternatively, the main spark plug 11 and the sub spark plug 12 of one group of spark plugs are arranged symmetrically.

In other embodiments of the present invention, the ignition system further includes a plurality of ignition coils 31 and a plurality of ignition circuits 30 in one-to-one correspondence with the plurality of ignition coils 31. Each ignition coil 31 is connected to both the main spark plug 11 and the auxiliary spark plug 12 of each group of spark plugs, i.e., one ignition coil 31 corresponds to one group of spark plugs. Each ignition circuit 30 includes an ignition control switch 32 (e.g., a switching power transistor) for controlling the energizing and de-energizing of the ignition coil 31 to store energy for the ignition coil 31 when energized and to control the ignition of the primary spark plug 11 and the secondary spark plug 12 of each group of spark plugs when de-energized. The ignition control switch 32 may be a switching transistor of fig. 2. The controller 20 is connected to each ignition control switch 32 for controlling the on/off of the ignition circuit 30.

That is, in the present embodiment, whether the ignition coil 31 is energized or not is controlled by the ignition control switch 32 in the ignition circuit 30. Alternatively, in other embodiments not shown, other control manners may be adopted to realize the on/off of the ignition coil 31.

Alternatively, the controller 20 is an Engine Controller (ECU).

In one embodiment, as shown in FIG. 2, a plurality of ignition control switches 32 are integrated into one igniter 40. In other embodiments of the present invention, not shown, each ignition control switch 32 is individually configured as an igniter 40, that is, the igniter 40 may be made in one piece or in two pieces, which is not limited herein.

Fig. 1 shows an ignition system of a four-cylinder high-power methanol engine, and an engine controller controls the ignition time of each cylinder by controlling the high and low electric potentials at the input end (A, B, C, D in fig. 1) of an igniter in normal operation.

When the terminal A of the engine ECU sends high potential to the igniter 40, the one-cylinder ignition coil 31 is conducted to charge the one-cylinder ignition coil 31 and increase the energy of the one-cylinder ignition coil 31, and when the ignition of one cylinder is needed, the terminal A of the engine ECU sends low potential to the igniter 40, the one-cylinder ignition coil 31 is cut off, the one-cylinder main spark plug 11 and the one-cylinder auxiliary spark plug 12 simultaneously generate sparks and ignite one-cylinder mixture. When the terminal B of the engine ECU sends high potential to the igniter 40, the two-cylinder ignition coil 31 is conducted to charge the two-cylinder ignition coil 31 and increase the energy of the two-cylinder ignition coil 31, and when the two cylinders need to be ignited, the terminal B of the engine ECU sends low potential to the igniter 40, the two-cylinder ignition coil 31 is cut off, the two-cylinder main spark plug 11 and the two-cylinder auxiliary spark plug 12 simultaneously generate sparks and ignite the two-cylinder mixture. When the terminal C of the engine ECU sends high potential to the igniter 40, the three-cylinder ignition coil 31 is conducted to charge the three-cylinder ignition coil 31 and increase the energy of the three-cylinder ignition coil 31, and when the three cylinders need to be ignited, the terminal C of the engine ECU sends low potential to the igniter 40, the three-cylinder ignition coil 31 is cut off, the three-cylinder main spark plug 11 and the three-cylinder auxiliary spark plug 12 simultaneously generate sparks and ignite the three-cylinder mixture. When the terminal D of the engine ECU sends a high potential to the igniter 40, the four-cylinder ignition coil 31 is turned on to charge the four-cylinder ignition coil 31 and increase the energy of the four-cylinder ignition coil 31, and when the four cylinders need to be ignited, the terminal D of the engine ECU sends a low potential to the igniter 40 and the four-cylinder ignition coil 31 is turned off, and the four-cylinder main spark plug 11 and the four-cylinder auxiliary spark plug 12 simultaneously generate sparks and ignite the four-cylinder mixture. In this way, the engine ECU controls the high and low potentials of the terminal of the igniter 40, thereby controlling the ignition energy and the ignition timing of the main ignition plug 11 and the sub ignition plug 12 of the engine.

The invention also provides an ignition method for the high-power methanol engine, which is used for the ignition system for the high-power methanol engine of any one of the engines, and the method comprises the following steps:

and controlling the ignition plugs of each group to sequentially ignite in a preset sequence, and controlling the main ignition plug and the auxiliary ignition plug of each group to simultaneously ignite.

In the embodiment, the ignition mode of the double spark plugs is applied to the high-power methanol engine for the first time, the main spark plug 11 and the auxiliary spark plug 12 provide ignition energy respectively, so that the ignition energy of the high-power methanol engine is increased, the combustion quality and the combustion speed of engine fuel are obviously improved, and the thermal efficiency of the engine is improved.

Further, for each cylinder, the system can continue to operate when one of the spark plugs fails, only partial combustion efficiency is sacrificed, and reliability of the system can be improved.

In a further embodiment, the step of controlling the ignition of the groups of spark plugs in sequence in a predetermined sequence and controlling the main spark plug and the auxiliary spark plug of each group of spark plugs to ignite simultaneously comprises:

determining the ignition time t0 of each group of spark plugs according to the rotating speed and the load of the high-power methanol engine;

and before the ignition time T0 of each group of the spark plugs, controlling the ignition coils of the corresponding main spark plug 11 and the auxiliary spark plug 12 to be electrified for a preset electrifying time T1 and to be powered off at the ignition time T0.

The engine control system usually stores ignition angle data determined by the engine speed and the engine load, so that the ignition timing is determined. The ignition coil 31 is energized for a time determined to ensure that the ignition energy meets the requirements for ignition of the mixture, and can be calibrated thermodynamically through experience and bench.

In one embodiment, the preset energization time T1 is determined by a calibration experiment targeting the need to ensure that the ignition energy meets the requirements for igniting the mixture in a high power methanol engine. That is, an experiment is performed for the purpose of igniting the mixture gas in the high-power methanol engine, and the value of the preset energization time T1 is obtained, so that the preset energization time T1 can meet the ignition requirement, and the gas combustion in the combustion chamber is ensured to obtain sufficient ignition energy.

In another embodiment, the preset energization time T1 is determined according to the kind of fuel.

By controlling the energization time of the ignition coil 31 in accordance with the fuel, the amount of heat generated by the ignition coil 31 can be reduced, and the reliability of the ignition coil 31 can be improved. For example, methanol is combusted in normal conditions, gasoline is combusted at low temperature start, the energization time is controlled according to the characteristics of gasoline at low temperature, and the energization time is controlled according to the characteristics of methanol at normal operation.

Fig. 3 is an ignition timing diagram of an ignition system for a high power methanol engine according to one embodiment of the present invention. Fig. 3 shows an ignition timing chart of a four-cylinder high-power methanol engine, a1 in fig. 3 shows an ignition timing chart of the main ignition plug 11, a2 shows an ignition timing chart of the auxiliary ignition plug 12, t is an ignition cycle, and t0 is an ignition timing of the main ignition plug 11 of one cylinder. The ignition sequence is one cylinder-three cylinder-four cylinder-two cylinder, and the main spark plug 11 and the auxiliary spark plug 12 of each cylinder are simultaneously ignited. Firstly, a cylinder ignition coil 31 is electrified, energy required by ignition is stored, the electrifying time is determined by calibration (namely T1), and the electrifying time depends on the rotation speed of the engine, the engine load and the like, when the engine ECU judges that one cylinder ignition is required, the cylinder ignition coil 31 is powered off, the main ignition plug 11 and the auxiliary ignition plug 12 simultaneously generate sparks, but the sparks generated by the main ignition plug 11 and the auxiliary ignition plug 12 in the cylinder are opposite in direction, one is from a center pole to a side pole, and the other is from the side pole to the center pole. The engine ECU controls the operation of the spark plugs of the respective cylinders repeatedly in this way immediately after the three-cylinder ignition, the four-cylinder ignition, and the two-cylinder ignition.

The present invention is also applicable to a four-valve engine, taking a two-valve engine as an example.

Thus, it should be appreciated by those skilled in the art that while a number of exemplary embodiments of the invention have been illustrated and described in detail herein, many other variations or modifications consistent with the principles of the invention may be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the invention. Accordingly, the scope of the invention should be understood and interpreted to cover all such other variations or modifications.