JP2810972B2 - Air blast valve - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an air blast valve.

[Prior Art] A nozzle port formed at one end of a compressed air passage, an on-off valve for controlling the opening and closing of the nozzle port, and a fuel injection valve for injecting fuel into the compressed air passage are provided. 2. Description of the Related Art An air blast valve is known which is disposed in a combustion chamber and in which fuel is ejected from a nozzle port together with compressed air into an engine combustion chamber when an on-off valve is opened (see Japanese Patent Application Laid-Open No. 62-93481). In this air blast valve, the fuel is injected into the compressed air passage twice from the fuel injection valve during one cycle of the engine, that is, after a while after the on-off valve is closed and when the on-off valve is moved to the next position. Before the valve is opened, fuel is injected into the compressed air passage from the fuel injection valve in advance, and then fuel is again injected from the fuel injection valve into the compressed air passage during the opening period of the on-off valve.

By the way, in the air blast valve, when the fuel is injected from the fuel injection valve while the compressed air is flowing in the compressed air passage, a strong shear force acts on the fuel because the relative speed between the compressed air flow and the fuel flow increases. Thus, atomization of the fuel can be improved. In the above-mentioned air blast valve, the latter half fuel injection is performed in the flowing compressed air,
The atomization of the fuel injected at least in the second half becomes good,
Therefore, good combustion is ensured.

[Problems to be solved by the invention]

As described above, in order to improve the atomization of the fuel injected from the air blast valve, the fuel is injected from the fuel injection valve when the compressed air is flowing in the compressed air passage, that is, during the opening period of the on-off valve. Is most preferable. However, if the desired amount of fuel cannot be completely injected only during the opening period of the on-off valve, the fuel injected from the fuel injection valve is retained in the compressed air passage near the nozzle port for as long as possible, Thus, it is preferable that the fuel be atomized as much as possible by the heat of combustion in the engine body during the stagnation period, and that the atomized fuel be ejected from the nozzle port when the on-off valve is opened.

However, in the above-described air blast valve, the first half of the fuel injection is performed from the fuel injection valve after a while after the on-off valve is closed and before the on-off valve is next opened, as described above, and then after a while. Later, the on-off valve starts to open. Accordingly, the period from when the fuel injected in the first half reaches the compressed air passage near the nozzle opening to when the on-off valve is opened, that is, the residence period of the fuel near the nozzle opening is relatively short. During this relatively short residence time, there is a problem that the fuel is not sufficiently atomized by the heat of combustion in the engine body, resulting in deterioration of combustion.

[Means for solving the problem]

According to the present invention, there is provided a nozzle port formed at one end of a compressed air passage, an on-off valve for opening and closing the nozzle port, and a fuel injection valve for injecting fuel into the compressed air passage. In an air blast valve in which fuel is ejected from the nozzle port together with compressed air when the on-off valve is opened, fuel is injected only once from the fuel injection valve every one cycle of the engine, and the on-off valve is opened. The valve is opened only once, the opening timing of the fuel injection valve is set to be substantially the same as the opening timing of the on-off valve, and the opening period of the fuel injection valve is set longer than the opening period of the on-off valve. .

(Operation)

For the fuel injected from the fuel injection valve into the compressed air flowing in the compressed air passage during the opening period of the on-off valve,
Due to the high relative velocity between the compressed air flow and the fuel flow, a strong shearing force acts on the fuel, and as a result, the fuel is finely atomized. Next, the fuel carried to the nozzle port by the compressed air flow by the time of closing the on-off valve is immediately ejected from the nozzle port. On the other hand, the fuel that has not been ejected from the nozzle port by the time the valve closes is relatively long from when it reaches the compressed air passage near the nozzle port until the valve opens in the next engine cycle. It stays in the compressed air passage near the nozzle port over time. During this stagnation period, the fuel is heated by the combustion heat in the engine body and is sufficiently atomized, and then when the on-off valve is opened, the atomized fuel is ejected from the nozzle port.

〔Example〕

Referring to FIG. 1, 1 is a cylinder block, 2 is a piston reciprocating in the cylinder block 1, 3 is a cylinder head fixed on the cylinder block 1, 4
Denotes combustion chambers formed between the piston 2 and the cylinder head 3, respectively. A combustion chamber 4 is provided on the inner wall surface of the cylinder head 3.
An air blast valve 6 for injecting fuel with compressed air toward the inside is disposed. An unillustrated ignition plug is arranged at the center of the inner wall surface of the cylinder head 3.

A compressed air passage 11 extending straight is formed in a housing 10 of the air blast valve 6, and a nozzle port 12 located in the combustion chamber 4 is formed at a distal end of the compressed air passage 11. An on-off valve 13 is arranged in the compressed air passage 11, and a valve element 14 for opening and closing the nozzle port 12 is provided at an outer end of the on-off valve 13.
Are integrally formed. A movable core 16 arranged coaxially with the on-off valve 13 and urged toward the on-off valve 13 by the compression spring 15 and a solenoid 17 for sucking the movable core 16 are arranged in the housing 10. The inner end of the on-off valve 13 is brought into contact with the end face of the movable core 16 by a compression spring 18, and the spring force of the compression spring 18 is stronger than that of the compression spring 15. The valve 14 is closed. When the solenoid 17 is energized, the movable core 16 moves in the direction of the on-off valve 13, and as a result, the valve element 14 of the on-off valve 13 causes the nozzle port 12 to open. On the other hand, a compressed air passage 19 that extends obliquely from the compressed air passage 11 is branched from the compressed air passage 11, and the compressed air passage 19 is connected to a compressed air source 23 via a compressed air passage 21. Therefore, the compressed air passages 21, 19
And 11 are filled with compressed air. A fuel injection valve 25 is mounted in the housing 10, and fuel is injected from a nozzle 26 of the fuel injection valve 25 into the compressed air passage 19.

FIGS. 2 and 3 show the opening period of the supply valve and the exhaust valve, the period of fuel injection from the fuel injection valve 25 and the opening period of the on-off valve 13 in the case of the two-stroke internal combustion engine, that is, Indicates the valve opening period. FIG. 2 shows the engine during low engine speed operation, and FIG. 3 shows the engine during high engine speed operation.

As shown in FIGS. 2 and 3, in this embodiment, the exhaust valve opens earlier than the air supply valve and closes earlier. On-off valve
The valve closing start timing of the thirteenth is determined based on the engine load and the engine speed, and the optimum valve closing start crank angle for the engine load and the engine speed is determined in advance in a map through experiments. On the other hand, the valve opening start timing of the opening and closing valve 31 is set at a time earlier by a predetermined time T ₁ a predetermined than the start timing of closure of the above on-off valve 13. Therefore, the opening period of the on-off valve 13 is a predetermined time T ₁ irrespective of the engine speed.
Thus, the opening period of the on-off valve 13 in terms of the crank angle increases as the engine speed increases. Note that the closing timing of the on-off valve 13 depends on the upper limit of the in-cylinder pressure at which fuel can be injected from the air blast valve 6 into the combustion chamber 4. On the other hand, the opening start timing of the on-off valve 13 is within a range in which fuel injected from the air blast valve 6 into the combustion chamber 4 does not flow into the exhaust port via the exhaust valve during the high engine speed operation shown in FIG. Is determined by

As shown in FIGS. 2 and 3, fuel is injected into the compressed air passage 19 once every one cycle of the engine from the fuel injection valve 25, and the opening timing of the fuel injection valve 25, that is, the fuel The injection start timing is set at substantially the same timing as the opening start timing of the on-off valve 13 described above.

The fuel injection time, that is, the valve-opening period of the fuel injection valve 25 is determined based on the engine load and the engine speed, and optimal values for the engine load and the engine speed are determined in advance by experiments in the form of a map. I have. When the engine speed is constant, the fuel injection time becomes longer as the engine load increases.
The valve closing start timing of the fuel injection valve 25 is set to a timing later than the valve opening start timing of the fuel injection valve 25 by the fuel injection time calculated based on this map.

As can be seen from FIGS. 2 and 3, in this embodiment, the opening of the fuel injection valve 25 is set to be substantially the same as the opening of the on-off valve 13, so that as much fuel as possible is opened and closed. During the valve opening period of 13, the fuel injection valve 25 injects the compressed air into the passage 19. Compressed air is flowing toward the nozzle port 12 in the compressed air passages 21, 19, 11 during the opening period of the on-off valve 13. That is, since the fuel is injected into the flowing compressed air during the opening period of the on-off valve 13, a strong shear force acts on the fuel because the relative speed between the compressed air flow and the fuel flow is large, Thus, atomization of the fuel can be improved. Next, the fuel is carried toward the nozzle port 12 through the compressed air passages 19 and 11 by the compressed air flow. Time T ₂ of the up this injected fuel reaches the nozzle outlet is substantially constant time regardless of the engine speed. Accordingly, the fuel injected from the fuel injection valve 25 is also before the predetermined time T ₂ or higher than the valve closing start timing of the opening and closing valve 13 is immediately combustion from the nozzle port 12 while being atomized as described above by the compressed air flow It is squirted into the chamber 4.

On the other hand, the period from time before predetermined time T ₂ from the start timing of closure of the opening and closing valve 13 to the valve closure start timing of the opening and closing valve 13, i.e., injected from the fuel injection valve 25 in the opening period end of the on-off valve 13 The fuel stays in the compressed air passage 11 near the nozzle port 12. Further, since the fuel injected from the fuel injection valve 25 after the closing of the on-off valve 13 is injected into the compressed air in a stationary state, atomization of the fuel is not very good. This fuel also sequentially reaches the compressed air passage 11 near the nozzle port 12 and stays there. These fuels will be opened and closed in the next engine cycle.
It stays in the compressed air passage 11 near the nozzle port 12 until the valve 13 is opened. In the present embodiment, immediately after the closing of the on-off valve 13, these fuels sequentially arrive in the compressed air passage 11 near the nozzle port 12, so that the time for these fuels to stay near the nozzle port 12 is very long. long. During this stagnation period, these fuels are heated by the combustion heat in the combustion chamber 4 to be sufficiently atomized, and then when the on-off valve 13 is opened, the atomized fuel enters the combustion chamber 4 from the nozzle port 12. It is gushing. Since the atomization or atomization of all the fuel ejected from the air blast valve 6 is improved in this manner, good combustion can be ensured.

〔The invention's effect〕

The atomization and atomization of all the fuel ejected from the air blast valve are improved, and good combustion can be ensured.

[Brief description of the drawings]

FIG. 1 is a side cross-sectional view of an air blast valve, FIG. 2 is a diagram showing an opening period of a supply / exhaust valve, an opening period of an on-off valve, and a fuel injection period during a low engine speed operation, and FIG. FIG. 3 is a diagram showing an opening period of a supply / exhaust valve, an opening period of an on-off valve, and a fuel injection period during an engine high-speed operation. 6 ... Air blast valve, 11,19,21 ... Compressed air passage, 12 ... Nozzle port, 13 ... On / off valve, 25 ... Fuel injection valve.

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Naotaka Cho 1-1-1 Showa-cho, Kariya-shi, Aichi Japan Inside Denso Co., Ltd. (72) Inventor Yutaka Niwa 1-1-1, Showa-cho, Kariya-shi, Aichi Nihon Denso Co., Ltd. (56) References JP-A-3-134262 (JP, A) JP-A-1-271658 (JP, A) JP-A-62-93481 (JP, A) (58) Fields investigated (Int. ⁶ , DB name) F02M 67/02-67/04 F02M 67/12 F02M 61/08 F02M 69/00 F02M 69/04

Claims (1)

(57) [Claims] 1. An on-off valve comprising: a nozzle port formed at one end of a compressed air passage; an on-off valve for controlling the opening and closing of the nozzle port; and a fuel injection valve for injecting fuel into the compressed air passage. In the air blast valve in which fuel is ejected from the nozzle port together with compressed air when the valve is opened, the fuel is injected only once from the fuel injection valve and the open / close valve is opened only once for each cycle of the engine. Setting the valve opening timing of the fuel injection valve to be substantially the same as the valve opening timing of the on-off valve;
An air blast valve in which the opening period of the fuel injection valve is set longer than the opening period of the on-off valve.