JP2732716B2 - Air blast valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air blast valve.

[0002]

2. Description of the Related Art A nozzle port is formed at one end of a compressed air passage, the nozzle port is disposed in an engine combustion chamber, and an opening / closing valve for controlling the opening / closing of the nozzle port is provided at the nozzle port. The seat is formed in a conical shape that expands outward, and the valve body of the on-off valve is seated on this valve seat, and a terminal conical portion that extends outward following the valve seat has a larger divergence angle than the valve seat. An air blast valve, which is formed in a conical shape that expands outward and allows fuel supplied to the compressed air passage to be ejected from the nozzle port when the open / close valve is opened by compressed air supplied to the compressed air passage. It is known (see Japanese Patent Application Laid-Open No. 63-500323). In this air blast valve, a part of the compressed air ejected from the nozzle orifice spreads out in a substantially conical shape along the end conical wall surface due to the wall surface adhesion effect and flows out. At the time of engine low load operation, the particle size of the fuel spray becomes small, and the fuel spray is ejected along the above-mentioned conical air flow. Therefore, a fuel spray having a large injection angle is formed. On the other hand, at the time of engine high load operation, the inertia force of the fuel spray is large because the particle diameter of the fuel spray is large, so that the fuel spray travels straight without spreading outward in the radial direction along the above-mentioned conical air flow. I do. Thus, fuel spray having a smaller injection angle is formed during engine high load operation than during engine low load operation.
As described above, in the air blast valve, the injection angle of the fuel spray is increased or decreased as a whole over the entire circumference of the fuel spray according to the engine load.

[0003]

However, depending on the shape of the combustion chamber, it is necessary to change the injection direction of the fuel spray in order to prevent the injected fuel from adhering to the spark plug or the inner wall surface of the cylinder. It may be. However, with the above air blast valve, the injection angle of the fuel spray can be increased or decreased as a whole,
There is a problem that the injection direction of the fuel spray cannot be changed.

[0004]

According to the present invention, a nozzle port is formed at one end of a compressed air passage, and an opening / closing valve for controlling the opening / closing of the nozzle port is provided at the nozzle port. In an air blast valve in which fuel supplied to an air passage is ejected from a nozzle opening when an on-off valve is opened by compressed air supplied to a compressed air passage, a valve seat formed at the nozzle opening is outwardly positioned. The valve body of the on-off valve is seated on the valve seat, and the tip of the valve seat is inclined with respect to the axis of the on-off valve. It is formed so that it can be done.

[0005]

The distal end of the valve seat is inclined with respect to the axis of the on-off valve, so that the distal end of the valve seat has the outermost portion located at the outermost position in the axial direction of the on-off valve, and the outermost portion. There is an innermost part located inside.

[0006] When the on-off valve is opened, the compressed air in the compressed air passage is ejected from the nozzle port at a high speed while spreading conically along the inner wall surface of the conical valve seat. The air located inside the jet air flow is entrained in the jet air flow that is jetted while spreading in a conical shape, and as a result, the pressure in the inner region surrounded by the jet air flow decreases. On the other hand, air outside the air blast valve is entrained outside the jet airflow. Here, the blast air flow portion squirted from the nozzle port portion where the valve seat tip is located more inward than the outermost portion is squirted from the nozzle port portion located at the outermost portion. Because it comes into contact with the air outside of the air blast valve earlier than the blown air flow part, the outer air flow part that is blown out from the nozzle port part located inside from the outermost part is The entrainment flow is generated earlier than the entrainment flow on the outer side of the jet airflow portion ejected from the nozzle opening located at the outermost portion. While the flow rate of the outer entrainment flow is high, the pressure outside the jet air flow becomes low similarly to the pressure inside the jet air flow. Then, as the outer entrained flow is progressively decelerated, the pressure outside the jet air flow gradually approaches the overall pressure in the area around it, i.e., the area outside the jet air flow. The pressure outside the region of the jet air flow is high because it is an open space, and therefore the pressure outside the jet air flow increases as the outer entrained flow is decelerated. Here, the outer entrainment flow with respect to the jet airflow portion jetted from the nozzle opening portion located inward from the outermost portion has an earlier generation time as described above, so that the deceleration is also early. Occurs. As a result, the pressure on the outside of the jet airflow portion ejected from the nozzle port located inside the outermost portion rises, and the pressure on the outside becomes higher than the pressure on the inside. As a result, the jet air flow portion is bent inward. This degree of bending increases from the outermost part to the innermost part, and the jet airflow part jetted from the nozzle opening located at the innermost part is bent the most.
As described above, when the ejection airflow portion ejected from the nozzle opening portion located inward from the outermost portion is bent inward, the inner region surrounded by the ejection airflow is compressed, so The pressure in the inner region is increased, so that the pressure difference between the outer and inner pressures of the blast air flow is almost eliminated. As a result, the ejected air flow portion ejected from the nozzle opening located at the outermost portion maintains the flow direction which spreads in a conical shape without being bent inward.

Thus, a jet air flow is formed from the nozzle opening located at the outermost part along the cone of the valve seat, and the injection angle gradually increases from the outermost part toward the innermost part. A reduced jet airflow is formed. That is, a jet airflow inclined with respect to the axis of the on-off valve is formed.

[0008] When the particle size of the fuel spray ejected from the nozzle opening is small, the fuel spray is ejected along the jet air flow described above. Therefore, a fuel spray which is totally inclined with respect to the axis of the on-off valve is formed. On the other hand, when the particle size of the fuel spray is large, the inertia force of the fuel spray is large, so that the fuel spray is jetted symmetrically with respect to the axis of the on-off valve without following the jet airflow.

[0009]

4 to 7 show a case where the present invention is applied to a two-stroke internal combustion engine. 4 to 7, 1 is a cylinder block, 2 is a piston, 3 is a cylinder head, 4 is a combustion chamber, 5 is a spark plug, 6 is a pair of air supply valves, 7 is an air supply port, and 8 is a pair. , 9 indicates an exhaust port, and 10 indicates an air blast valve. As shown in FIG. 8, in the two-stroke internal combustion engine shown in FIGS. 4 to 7, the exhaust valve 8 opens before the air supply valve 6, and the exhaust valve 8 closes before the air supply valve 6. . That is, when the piston 2 descends, first, the exhaust valve 8 opens, and the burned gas in the combustion chamber 4 is discharged into the exhaust port 9. Next, when the air supply valve 6 is opened, fresh air sent from a supercharger (not shown) is supplied to the air supply port 7.
From the combustion chamber 4. Next, when the piston 2 rises past the bottom dead center, the exhaust valve 8 closes, and then the air supply valve 6 closes. Immediately before or after the exhaust valve 8 closes, fuel is injected together with compressed air from the air blast valve 10, and the injected fuel is ignited by the spark plug 5. As shown in FIG. 5 and FIG.
A mask wall 11 that closes the opening of the supply valve 6 on the side of the exhaust valve 8 over the full opening period of the supply valve 6 is formed on the inner wall surface.
Therefore, when the air supply valve 6 is opened, fresh air flows into the combustion chamber 4 through the opening of the air supply valve 6 opposite to the exhaust valve 8, and this fresh air then flows as shown by an arrow W in FIG. Since the gas flows in a loop in the combustion chamber 4, good loop scavenging is performed.

As shown in FIGS. 4 and 6, a groove 12 is formed on the top surface of the piston 2 from below the spark plug 5 to below the tip of the air blast valve 10. In the two-stroke internal combustion engine shown in FIGS. 4 and 6, the groove 12 has a symmetrical shape with respect to a vertical plane KK including the spark plug 5 and the air blast valve 10, and is viewed from above the piston 2. As shown in FIG. 6, the concave groove 12 has a drop-like shape whose width gradually increases from the air blast valve 10 side toward the spark plug 5 side.
Further, as shown in FIG. 4, the cross-sectional shape of the concave groove 12 along the vertical plane KK has a slightly concave shape below the spark plug 5 toward the side opposite to the air blast valve 10 and the air from there. The blast valve 10 has a shape that is gently inclined upward toward the lower side. When the piston 2 reaches the top dead center, the ignition plug 5 enters the groove 12.

Referring to FIG. 4, the air blast valve 10 includes a nozzle port 15 disposed in the combustion chamber 4, an opening / closing valve 16 for controlling the opening / closing of the nozzle port 15, and an air blast valve 10 extending outward.
A valve seat 17 that expands substantially conically up to the distal end surface of the valve, a valve element 18 of an on-off valve 16 that can be seated on the conical valve seat 17, a solenoid 19 that drives the on-off valve 16, and compressed air. Inlet 20
And a compressed air passage 21 that passes through the solenoid 19 from the compressed air inlet 20 and then bends once in the lateral direction and then passes around the on-off valve 16 to the nozzle port 15, and is disposed in the compressed air passage 21. And a fuel injection valve 22. The compressed air inlet 20 is connected to a compressed air supply pump 23, so that the compressed air passage 21 is always filled with compressed air. On the other hand, fuel is injected into the compressed air passage 21 from the fuel injection valve 22. When the solenoid 19 is excited and the valve element 18 opens the nozzle port 15, the compressed air is supplied with fuel along with the nozzle port.
From 15, it is injected into the combustion chamber 4.

FIGS. 1 to 3 are enlarged views of the tip of the air blast valve 10 of the first embodiment. Here, FIG. 1 shows a state where the valve element 18 of the on-off valve 16 is closed, and FIG. 3 shows a state where the valve element 18 is at the maximum lift. Referring to FIGS. 1 to 3, a valve seat which expands in a substantially conical shape outwardly to the tip end surface of the air blast valve 10 is provided at the nozzle port 15.
17 are formed. In the embodiment shown in FIGS. 1 to 3, the opening angle θ of the conical valve seat 17 is formed at about 60 °.
On the other hand, the valve element 18 of the on-off valve 16 is formed in a substantially hemispherical shape whose cross-sectional area gradually increases outward. When the on-off valve 16 is closed, the valve element 18 is seated on the conical valve seat 17 and the nozzle port 15 is closed as shown in FIG.
The tip portion 17a of the valve seat 17 is formed to be inclined with respect to the axis A of the on-off valve 16. Further, since the distal end portion 17a of the valve seat 17 is located in a single plane, its cross section is straight as shown in FIGS. Note that the distal end portion 17a of the valve seat 17 may be in a curved plane, and in this case, the cross section is curved. The valve seat tip portion 17a has an innermost innermost portion 17b and an outermost outermost portion.
17c. The length of the generatrix of the cone of the conical valve seat 17 is
It becomes the longest at the outermost part 17c, gradually decreases toward the innermost part 17b, and becomes the shortest at the innermost part 17b. As shown in FIG. 3, the outermost portion 17c is the valve body when the valve body 18 is at the maximum lift.
And the innermost portion 17b is a valve body.
It is formed so as to be located more inward than the valve body end face 18a when the maximum lift of the valve body 18 is performed. Note that the outermost portion 17c may be formed so that the valve element 18 protrudes outward from the valve element end face 18a during the maximum lift. As shown in FIG. 1, the innermost portion 17b is formed so as to be substantially flush with the valve body end surface 18a when the on-off valve 16 is closed.

Next, referring to FIGS. 9 to 11, fuel and compressed air nozzle ports 15 in the air blast valve 10 of the present invention will be described.
The form of ejection from the nozzle will be described. 9 and FIG.
10 shows a case where the particle size of the fuel spray ejected from the nozzle port 15 is small, and FIG. 11 shows a case where the particle size of the fuel spray is large.

As shown in FIG. 9, when the on-off valve 16 is opened, the compressed air in the compressed air passage 21 is expelled from the nozzle port 15 at a high speed while spreading conically along the inner wall surface of the conical valve seat 17. Can be The air located inside the jet air flow 27 is entrained in the jet air flow 27 ejected while spreading in a conical shape, and as a result, the pressure in the inner region 29 surrounded by the jet air flow 27 decreases. . On the other hand, air outside the air blast valve 10 is also entrained outside the jet airflow 27. Here, the nozzle port portion where the valve seat tip portion 17a is located more inward than the outermost portion 17c, that is, the position where the cone generatrix of the conical valve seat 17 is shorter than the cone generatrix in the outermost portion 17c The jet air flow portion jetted from the nozzle port portion of the air blast valve 10 is earlier than the jet air flow portion jetted from the nozzle port portion located at the outermost portion 17c. Since it comes into contact with air, the outer entrained flow with respect to the ejected air flow portion ejected from the nozzle port portion located inward from the outermost portion 17c is reduced by the outermost portion 17c.
Is generated earlier than the outer entrainment flow for the jet air flow portion jetted from the nozzle port portion located at the position. While the flow rate of the outer entrainment flow is high, the pressure outside the jet air flow 27 becomes low similarly to the pressure inside the jet air flow 27. Then, as the outer entrained flow is gradually decelerated, the pressure outside of the jet air flow 27 gradually approaches the overall pressure in the area around it, i.e., the region 30 outside the jet air flow 27. Since the outer region 30 of the jet air flow 27 is an open space, its pressure is high, and thus the jet air flow 27
The pressure outside of will be higher. Where the outermost part
As described above, the outer entrainment flow with respect to the jet air flow portion jetted from the nozzle port portion located inside of 17c is generated earlier, and thus the deceleration also occurs earlier. As a result, the pressure on the outside of the jet airflow portion jetted from the nozzle port portion located inside the outermost portion 17c rises, and the pressure on the outside becomes higher than the pressure on the inside. The difference causes the blast air stream to bend inward. This degree of bending increases from the outermost part 17c to the innermost part 17b,
The jet airflow portion jetted from the nozzle port portion located at b is bent most greatly. As described above, when the ejection airflow portion ejected from the nozzle opening located inside the outermost portion 17c is bent inward, the inner region 29 surrounded by the ejection airflow 27 is compressed. Therefore, the pressure in the inner region 29 is increased, and the pressure difference between the pressure outside and the pressure inside the jet air flow 27 is almost eliminated. As a result, the ejected air flow portion ejected from the nozzle opening located at the outermost portion 17c maintains the flow direction which spreads in a conical shape without being bent inward.

Thus, a jet air flow is formed along the cone of the valve seat 17 from the nozzle port located at the outermost portion 17c, and is injected from the outermost portion 17c toward the innermost portion 17b. A jet airflow having a gradually decreasing angle is formed. That is, a jet air flow inclined with respect to the axis A of the on-off valve 16 is formed.

When the particle size of the fuel spray ejected from the nozzle port 15 is small, the fuel spray
As shown in (2), the air is jetted on the jet air flow 27 described above. Therefore, a fuel spray which is totally inclined with respect to the axis A of the on-off valve 16 is formed. On the other hand, when the particle size of the fuel spray is large, the inertia force of the fuel spray is large, so that the fuel spray is ejected symmetrically to the axis A of the on-off valve 16 without flowing in the ejected air flow 27 as shown in FIG. I'm sullen.

Next, with reference to FIGS. 8, 12 and 13,
A method for injecting fuel from the air blast valve 10 in the two-cycle internal combustion engine shown in FIGS. 4 to 7 will be described. FIG. 8 shows the opening timing of the supply / exhaust valve, the timing of fuel injection from the fuel injection valve 22 into the compressed air passage 21, and the opening timing of the on-off valve 16, that is, the opening timing of the air blast valve 10. . FIG. 12 shows the inside of the combustion chamber 4 during low engine load operation, and FIG. 13 shows the combustion chamber 4 during high engine load operation.
The inside is shown. Also, as shown in FIGS. 12 and 13, the air blast valve 10 is provided at the innermost portion of the valve seat tip portion 17a.
17b is disposed on the inner wall surface of the cylinder head 3 so as to be located above, that is, on the side opposite to the top surface of the piston 2.

At the time of engine low load operation, as shown in FIGS. 8 and 12, after the exhaust valve 8 and the air supply valve 6 are closed, a concave groove extends from the nozzle port 15 of the air blast valve 10 in the middle stage of the compression stroke.
Fuel is ejected toward the 12 concave inner wall surfaces. During low engine load operation, the fuel injection amount is small, and the particle size of the fuel spray injected from the nozzle port 15 is small. As a result, as shown in FIG. 9 and FIG. 10, the fuel spray which is totally inclined in the direction of the outermost portion 17c of the valve seat tip portion 17a is ejected. Therefore, as shown in FIG. 12, even when fuel is ejected from the air blast valve 10 in the middle stage of the compression stroke in which the piston 2 is at a relatively low position, all the ejected fuel collides with the concave inner wall surface of the concave groove 12. Can be done. Since the concave inner wall surface of the concave groove 12 is formed in such a shape as to enclose the fuel spray F as described above, the concave groove 12
The fuel colliding on the concave inner wall surface is prevented from being scattered from the inside of the groove 12 to the outside, so that almost all the ejected fuel is retained in the groove 12. Also, since fuel is ejected when the piston 2 is at a relatively low position,
Sufficient time is provided for the fuel to vaporize well before ignition by the spark plug 5 is performed. Thus, even during low engine load operation with a small fuel injection amount, a well-burned combustible air-fuel mixture can be collected around the ignition plug 5, and as a result, good ignition and subsequent good combustion are obtained. be able to. Further, even if the depth of the groove 12 is not so large, all the injected fuel can be collected in the groove 12, so that a high compression ratio can be secured.

On the other hand, at the time of engine high load operation, fuel is injected from the air blast valve 10 into the combustion chamber 4 when the air supply valve 6 is closed or before and after the air supply valve 6 is closed. During high engine load operation, the fuel injection amount is large, and the particle size of the fuel spray ejected from the nozzle port 15 increases. As a result, as shown in FIG. 11 and FIG.
Since the fuel spray having a large injection angle and spreading in a conical shape is ejected from the entire circumference of the fuel injection pipe 15, a large amount of the ejected fuel spray is diffused in a wide range in the combustion chamber 4. Therefore, the fuel and the air are sufficiently mixed to form a homogeneous air-fuel mixture in the entire combustion chamber 4, and a required high engine output is secured.

The conical valve seat 17 and the valve element 18 are shown in FIG.
3 can take various shapes other than the shape shown in FIG. Hereinafter, some other embodiments will be described with reference to FIGS. Note that the same reference numerals are used for similar components.

First, a second embodiment will be described with reference to FIG. In this embodiment, a cylindrical portion 18 is provided below the valve body 18.
b is formed. In this embodiment, the valve seat tip 17a
Is formed so that the valve element 18 is positioned more inward than the valve element end face 18a during the maximum lift. Also, the valve seat tip 17a
The outermost portion 17c is formed so as to be substantially flush with the valve body end surface 18a when the on-off valve 16 is closed.

Next, a third embodiment will be described with reference to FIG. In this embodiment, a conical portion 18 is provided below the valve body 18.
c is formed. Valve body end face 18a, that is, conical portion
The lower surface of 18c is formed so as to be inclined in the same direction as the inclination direction of the valve seat tip portion 17a in substantially the same manner. Valve element 18
When the on-off valve 16 is closed, the valve body end face 18a is closed.
It is formed so that it may become almost flush.

Next, a fourth embodiment will be described with reference to FIGS. As shown in FIG. 16, in this embodiment, the valve element 18 is a cylindrical portion 18 of the valve element 18 of the second embodiment.
The shape is such that a guide portion 18d is further provided below b. Referring to FIG. 17, the outer periphery of the guide portion 18d has an oval shape and coincides with the outer periphery of the cylindrical portion 18b at a position corresponding to the innermost portion 17b of the valve seat tip portion 17a. Tip
The amount of protrusion from the columnar portion 18b increases toward the position corresponding to the outermost portion 17c of the outermost portion 17a.
It is formed such that the amount of protrusion from the cylindrical portion 18b at the position corresponding to c is maximized. Referring to FIG. 16, the upper surface of the guide portion 18d is formed as a smooth surface corresponding to the surface of the valve seat 17, and the lower surface of the guide portion 18d, that is, the valve body end surface 18a is inclined similarly to the valve seat tip portion 17a. It is formed so that. The valve element 18 is formed such that the valve element end face 18a protrudes outward from the valve seat tip 17a even when the on-off valve 16 is closed. In this embodiment, the fuel spray can be inclined more greatly.

FIG. 18 shows a fifth embodiment. In this embodiment, only a part of the valve seat tip 17a is inclined with respect to the axis A of the on-off valve 16. The valve element 18 has the same shape as the valve element 18 of the first embodiment. Also in this example,
When the particle size of the fuel spray ejected from the nozzle port 15 is small, it is possible to form a fuel spray that is totally inclined with respect to the axis A of the on-off valve 16.

The sixth to eighth embodiments shown in FIGS. 19 to 21 are similar to the valve seats of the fifth embodiment shown in FIG.
This is a combination of the valve element 18 of the third embodiment.

[0026]

When the particle size of the fuel spray ejected from the air blast valve is small, it is possible to obtain a fuel spray which is entirely inclined with respect to the axis of the on-off valve. on the other hand,
When the particle size of the fuel spray ejected from the air blast valve is large, a fuel spray symmetrical with respect to the axis of the on-off valve can be obtained.

[Brief description of the drawings]

FIG. 1 is an enlarged side sectional view of a distal end portion of an air blast valve according to a first embodiment when the valve is closed.

FIG. 2 is an enlarged bottom view taken along arrow II of FIG.

FIG. 3 is an enlarged side cross-sectional view of a distal end portion of the air blast valve according to the first embodiment when the valve is opened.

FIG. 4 is a side sectional view of the two-stroke internal combustion engine taken along line IV-IV in FIG. 5;

FIG. 5 is a bottom view of the cylinder head of FIG. 4;

FIG. 6 is a plan view of a piston.

FIG. 7 is a side sectional view taken along line VII-VII of FIG. 5;

FIG. 8 is a diagram showing the opening timing of an air supply / exhaust valve, the opening timing of an air blast valve, and the like.

FIG. 9 is an enlarged cross-sectional view for explaining the ejection form of the fuel spray when the particle diameter of the fuel spray is small.

FIG. 10 is an enlarged sectional view taken along line XX of FIG. 9;

FIG. 11 is an enlarged cross-sectional view for explaining a jetting form of the fuel spray when the particle diameter of the fuel spray is large.

FIG. 12 is a diagram for explaining a state in a combustion chamber during low engine load operation.

FIG. 13 is a diagram for explaining a state in a combustion chamber during an engine high-load operation.

FIG. 14 is an enlarged side sectional view of a distal end portion of the air blast valve according to the second embodiment.

FIG. 15 is an enlarged side sectional view of a distal end portion of the air blast valve according to the third embodiment.

FIG. 16 is an enlarged side sectional view of a distal end portion of an air blast valve according to a fourth embodiment.

17 is an enlarged bottom view as viewed along arrow XVII in FIG. 16;

FIG. 18 is an enlarged side sectional view of a distal end portion of an air blast valve according to a fifth embodiment.

FIG. 19 is an enlarged side sectional view of a distal end portion of an air blast valve according to a sixth embodiment.

FIG. 20 is an enlarged side sectional view of a distal end portion of an air blast valve according to a seventh embodiment.

FIG. 21 is an enlarged side sectional view of a distal end portion of an air blast valve according to an eighth embodiment.

[Explanation of symbols]

 10 ... Air blast valve 15 ... Nozzle port 16 ... On / off valve 17 ... Valve seat 17a ... Valve seat tip 18 ... Valve

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor ▲ Kushi ▼ Takahiro Toyota 1st Toyota Town, Toyota, Aichi Prefecture Inside Toyota Motor Co., Ltd. (72) Inventor Hiroshi Nomura 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Stock In-house (56) References JP-A 1-315663 (JP, A) JP-A 3-15655 (JP, A) JP-A 51-123423 (JP, A) JP-A 63-500323 (JP, A) ) Hikaru 2-103169 (JP, U)

Claims (1)

(57) [Claims] 1. A nozzle port is formed at one end of a compressed air passage, and an opening / closing valve for controlling the opening / closing of the nozzle port is provided at the nozzle port, and fuel supplied to the compressed air passage is introduced into the compressed air passage. In the air blast valve, which is made to jet from the nozzle port when the open / close valve is opened by the supplied compressed air, a valve seat formed at the nozzle port is directed outward to reach a tip end surface of the air blast valve. An air blast formed in such a shape as to expand in a substantially conical shape until the valve element of the on-off valve is seated on the valve seat, and the tip of the valve seat is inclined with respect to the axis of the on-off valve. valve.