JP2008038667A - Multi-cylinder engine - Google Patents

Abstract

A multi-cylinder engine capable of more evenly distributing an air-fuel mixture to each cylinder.
In a multi-cylinder engine, a butterfly valve is used as a throttle valve, a tip end portion of an injector is disposed behind a valve shaft of the throttle valve, and a central axis line of the injector is connected to the injector. Assuming an extension axis 8b of the injector 8 extending into the throttle intake passage 6 through the tip portion 9, on a projection view orthogonal to the central axis 6a of the throttle intake passage 6, on both sides of the valve shaft 12 of the throttle valve 7. The direction of the injector 8 is set so that the extension axis 8b of the injector 8 is biased to any one of the passage space 6d and 6e.
[Selection] Figure 1

Description

  The present invention relates to a multi-cylinder engine, and more particularly, to a multi-cylinder engine that can more uniformly distribute an air-fuel mixture to each cylinder.

As a conventional multi-cylinder engine, as in the present invention, an intake distribution passage is attached to a cylinder head, and an air-fuel mixture is distributed to a plurality of cylinders through the intake distribution passage, and a throttle body is provided at a single distribution passage inlet of the intake distribution passage. And a liquid fuel and a gas fuel are switched and supplied to the throttle body (see, for example, Patent Document 1).
This type of multi-cylinder engine has an advantage that an air-fuel mixture can be supplied to each cylinder with a single throttle body.

  However, the conventional multi-cylinder engine has a problem because a carburetor is used to supply liquid fuel to the throttle body.

Japanese Patent Laid-Open No. 10-220295 (see FIGS. 1 and 2)

The above prior art has the following problems.
<Problem> There is a possibility that the distribution of the air-fuel mixture to each cylinder may become uneven.
Since the carburetor is used to supply the liquid fuel to the throttle body, the atomization of the liquid fuel is insufficient, and the concentration distribution of the air-fuel mixture in the intake air distribution passage tends to be uneven. Distribution may be uneven.

  An object of the present invention is to provide a multi-cylinder engine that can solve the above-described problems, that is, a multi-cylinder engine that can more uniformly distribute the air-fuel mixture to each cylinder.

Invention specific matters of the invention according to claim 1 are as follows.
As illustrated in FIG. 6, an intake air distribution passage (2) is attached to the cylinder head (1), and the air-fuel mixture is distributed to a plurality of cylinders (3) through the intake air distribution passage (2). As illustrated, a multi-cylinder engine in which a throttle body (5) is attached to a single distribution passage inlet (4) of the intake distribution passage (2) and liquid fuel is supplied to the throttle body (5). In
As illustrated in FIGS. 1A and 1B, a throttle intake passage (6) is provided in the throttle body (5), and a throttle valve (7) is disposed in the throttle intake passage (6). An injector (8) is attached to the throttle body (5), and the tip (9) of the injector (8) faces the throttle intake passage (6) downstream of the throttle valve (7). 8) Open the liquid fuel injection port (10) at the tip (9),
As illustrated in FIGS. 1 (A) and 2, the direction of the central axis (6a) of the throttle intake passage (6) is the front-rear direction and the downstream side of the valve shaft (12) of the throttle valve (7). As later
A butterfly valve is used for the throttle valve (7), the tip (9) of the injector (8) is disposed behind the valve shaft (12) of the throttle valve (7), and the central axis of the injector (8) is arranged. Assuming the extension axis (8b) of the injector (8) extending from (8a) through the tip (9) of the injector (8) into the throttle intake passage (6),
As illustrated in FIGS. 4A and 4B, on the projection orthogonal to the center axis 6a of the throttle intake passage 6, the extension axis 8b of the injector 8 is the throttle valve. The injector (8) is oriented so as to be biased to any one of the passage spaces (6d) (6e) located on both sides of the valve shaft (12) of (7). A multi-cylinder engine characterized by setting.

(Invention according to Claim 1)
<Effect> Distribution of the air-fuel mixture to each cylinder can be made more uniform.
As illustrated in FIGS. 4 (A) and 4 (B), they are located on both sides of the valve shaft (12) of the throttle valve (7) on the projection orthogonal to the central axis (6a) of the throttle intake passage (6). Since the direction of the injector (8) is set so that the extension axis (8b) of the injector (8) is biased in any one of the passage spaces (6d) in the passage space (6d) (6e) The fuel spray that tends to be hidden behind the throttle valve (7) is biased in the passage space (6d) on one side, and is directly hit by high-speed intake air that passes through the space (6d). The concentration distribution of the air-fuel mixture in the intake air distribution passage (2) becomes more uniform, and the air-fuel mixture distribution to each cylinder (3) can be made more uniform.

(Invention according to Claim 2)
In addition to the effect of the invention according to claim 1, the following effect is achieved.
<Effect> A function capable of more evenly distributing the air-fuel mixture to each cylinder is high.
As illustrated in FIGS. 1A and 2, the angle formed by the injection axis 10a of the liquid fuel injection port 10 with respect to the extension axis 8b of the injector 8 is 30 ° or less. As described above, since the direction of the liquid fuel injection port (10) is set, the liquid fuel injected from the liquid fuel injection port (10) concentrates in the passage space (6d) on one side, and the liquid is directly discharged by the intake air. The atomization of the fuel is promoted, the concentration distribution of the air-fuel mixture in the intake air distribution passage (2) becomes more uniform, and the function of making the air-fuel mixture distribution to each cylinder (3) more uniform is high.

(Invention according to claim 3)
In addition to the effect of the invention according to claim 2, the following effect is achieved.
<Effect> A function capable of more evenly distributing the air-fuel mixture to each cylinder is high.
As illustrated in FIG. 1B, since a plurality of liquid fuel injection ports (10) are provided, the opening area of the liquid fuel injection port (10) is reduced, and the liquid fuel injected from the liquid fuel injection port (10) is reduced. Oil droplets can be refined. Also, the angle formed by the injection axis (10a) of each liquid fuel injection port (10) with respect to the extension axis (8b) of the injector (8) is set to 5 ° or more, so that each liquid fuel injection port The overlapping of the sprays of the liquid fuel injected from (10) is suppressed, and it is possible to suppress the oil droplets of the liquid fuel from becoming large due to the combination. For these reasons, the vaporization of the liquid fuel is promoted, the concentration distribution of the air-fuel mixture in the intake air distribution passage (2) can be made more uniform, and the distribution of the liquid air-fuel mixture to each cylinder (3) can be further improved. Highly uniform function.

<Effect> Even when the throttle opening is small, the function of evenly distributing the air-fuel mixture to each cylinder is high.
Since the liquid droplets of the liquid fuel can be miniaturized and the increase of the droplets of the liquid fuel due to the coupling can be suppressed, the fine oil droplets of the liquid fuel injected from the liquid fuel injection port (10) Even when the throttle valve is directly hit and the throttle opening is small, the vaporization of the liquid fuel is promoted, and the concentration distribution of the air-fuel mixture in the intake air distribution passage (2) can be made more uniform. It has a high function to make the distribution of the air-fuel mixture more uniform.

(Invention of Claim 4)
In addition to the effects of the inventions according to claims 1 to 3, the following effects are produced.
<Effect> It has a high function of evenly distributing the air-fuel mixture to each cylinder regardless of the operating state.
As exemplified in FIG. 1A, the liquid fuel injected from the liquid fuel injection port (10) collides with the inner peripheral surface of the insulator (14). For this reason, during idling operation at a low intake speed, a part of the liquid fuel stays attached to the inner peripheral surface of the insulator (14) and is reserved in the insulator (14) before entering the intake distribution passage (2). Thus, the air-fuel mixture concentration in the intake air distribution passage (2) is made more uniform. In addition, during high load continuous operation at a high intake speed, part of the liquid fuel that collided with the inner peripheral surface of the insulator (14) flows into the intake distribution passage (2) by pushing in the intake air, and the temperature is increased by high load continuous operation. Is rapidly vaporized on the inner surface of the intake distribution passage (2), and the mixture concentration in the intake distribution passage (2) is made more uniform.
From the above, regardless of the operation state, the air-fuel mixture concentration in the intake air distribution passage (2) is made more uniform, and the function of evenly distributing the air-fuel mixture to each cylinder (3) is high.

(Invention according to claim 5)
In addition to the effects of the inventions according to claims 1 to 3, the following effects are produced.
<Effect> It has a high function of evenly distributing the air-fuel mixture to each cylinder regardless of the operating state.
Referring to FIG. 1 (A), the liquid fuel injected from the liquid fuel injection port (10) is supplied to the inner peripheral surface of the intake passage outlet (13) of the throttle intake passage (6) and the insulator (14). In the idling operation where the intake speed is slow, a part of the liquid fuel adheres to the inner peripheral surface of the intake passage outlet (13) and the inner peripheral surface of the insulator (14). It is preliminarily vaporized in the intake passage outlet (13) and the insulator (14) before entering the intake distribution passage (2), and the mixture concentration in the intake distribution passage (2) is made more uniform. The Further, during high load continuous operation at a high intake speed, a part of the liquid fuel colliding with the inner peripheral surface of the intake passage outlet (13) and the inner peripheral surface of the insulator (14) is pushed into the intake distribution passage (2 ) And is rapidly vaporized on the inner surface of the intake distribution passage (2) where the temperature is increased due to continuous high-load operation, and the mixture concentration in the intake distribution passage (2) is made more uniform.
From the above, regardless of the operation state, the air-fuel mixture concentration in the intake air distribution passage (2) is made more uniform, and the function of evenly distributing the air-fuel mixture to each cylinder (3) is high.

(Invention of Claim 6)
In addition to the effects of the invention according to any one of claims 1 to 5, the following effects are provided.
<Effect> The function of distributing the air-fuel mixture more uniformly to each cylinder is high.
As illustrated in FIG. 1A, the passage inlet (18a) of the intake pressure introduction passage (18) is opened on the inner peripheral surface of the throttle intake passage (6) upstream of the injector (8). Therefore, the liquid fuel injected from the liquid fuel injection port (10) of the injector (8) is moved away from the passage inlet (18a) of the intake pressure introduction passage (18) by the flow of intake air, and the intake pressure introduction passage (18). Liquid fuel is difficult to enter. For this reason, the detection of the intake pressure by the intake pressure detection sensor (15) is stabilized, there is no problem that the fuel injection amount from the injector (8) fluctuates unnecessarily, and the air-fuel mixture is more evenly distributed to each cylinder (3). High functionality.

<Effect> The fuel supply device becomes compact.
As illustrated in FIG. 1A, since the intake pressure detection sensor (15) is attached to the throttle body (5) together with the injector (8), the fuel supply related parts are integrated into the throttle body (5) and the fuel is supplied. The supply device becomes compact.

(Invention of Claim 7)
In addition to the effect of the invention according to claim 6, the following effect is achieved.
<Effect> The function of distributing the air-fuel mixture more uniformly to each cylinder is high.
Since the direction of the intake pressure introduction passage (18) is set so that the angle formed by the intake pressure introduction passage (18) is 45 ° or more with respect to the transverse extension line (19a) illustrated in FIG. 4 (A). Even if the direction of the intake pressure introduction passage (18) is closer to the tangential direction than the radial direction of the throttle intake passage (6) and the passage cross-sectional area of the intake introduction passage (18) is reduced, the intake pressure introduction passage (18) The opening area of the passage inlet (18a) can be increased. For this reason, the passage cross-sectional area of the intake introduction passage (18) is reduced to make it less susceptible to the influence of intake pressure pulsation, and at the same time, the opening area of the passage inlet (18a) of the intake passage (18) is increased. It is possible to prevent clogging of the liquid fuel at the passage inlet (18a). For this reason, the detection of the intake pressure by the intake pressure detection sensor (15) is stabilized, there is no problem that the fuel injection amount from the injector (8) fluctuates unnecessarily, and the air-fuel mixture is more evenly distributed to each cylinder (3). High functionality.

<Effect> It is easy to cut the intake pressure introduction passage.
Since the direction of the intake pressure introduction passage (18) is set so that the angle formed by the intake pressure introduction passage (18) with respect to the transverse extension line (19a) illustrated in FIG. There is no problem that the direction of the intake pressure introduction passage (18) is too close to the tangential direction of the inner peripheral surface of the throttle intake passage (6), and the intake pressure introduction passage (18) can be easily machined.

(Invention of Claim 8)
In addition to the effect of the invention according to claim 7, the following effect is achieved.
<Effect> It is easy to cut the intake pressure introduction passage.
As illustrated in FIG. 4 (A), the intake pressure introduction passage (18) forms the transverse extension line (19a) on the projection orthogonal to the central axis (6a) of the throttle intake passage (6). Since the direction of the intake pressure introduction passage (18) is set so that the angle (18α) is 45 ° or more, the direction of the intake pressure introduction passage (18) is too close to the axial length direction of the throttle intake passage (6). Thus, there is no problem that the intake pressure introduction passage (18) becomes unnecessarily long, and the intake pressure introduction passage (18) can be easily machined. Further, as illustrated in FIG. 4A, the intake pressure introduction passage (18) with respect to the transverse extension line (19a) on the projection orthogonal to the central axis (6a) of the throttle intake passage (6). Since the direction of the intake pressure introduction passage (18) is set so that the angle (18α) formed by the angle is 18 ° or less, the direction of the intake pressure introduction passage (18) is set on the inner peripheral surface of the throttle intake passage (6). There is no problem of being too close to the tangential direction, and the intake pressure introduction passage (18) can be easily machined.

(Invention according to claim 9)
In addition to the effect of the invention according to claim 7 or claim 8, the following effect is achieved.
<Effect> The function of distributing the air-fuel mixture more uniformly to each cylinder is high.
As illustrated in FIG. 5B, a butterfly valve is used for the throttle valve (7), and is parallel to the central axis (6a) of the throttle intake passage (6) and the valve shaft (12) of the throttle valve (7). On the projected view, the passage inlet (18a) of the intake pressure introduction passage (18) is arranged so that the passage inlet (18a) of the intake pressure introduction passage (18) overlaps the central axis (6a) of the throttle intake passage (6). The high-speed intake air that passes by the side of the throttle valve (6) passes by the side of the passage inlet (18a) of the intake pressure introduction passage (18), and the passage inlet (18a) of the intake pressure introduction passage (18). ) Is sucked toward the throttle intake passage (18) by the negative pressure of the intake air, and the liquid fuel is not easily clogged at the passage inlet (18a) of the intake pressure introduction passage (18).
In addition, the intake pressure introduction passage (18) is inclined downward from the passage outlet (18b) toward the passage inlet (18b), and on the above projection view, with respect to the extension axis (6c) of the throttle intake passage (6). The direction of the intake pressure introduction passage (18) was set so that the angle (18β) formed by the intake pressure introduction passage (18) was 45 ° or more and 75 ° or less. For this reason, compared with the case where the angle (18β) is less than 45 °, the liquid fuel that has entered the intake pressure introduction passage (18) tends to flow out by its own weight. Further, compared with the case where the angle (18β) exceeds 75 °, the passage cross-sectional area of the intake introduction passage (18) is increased by the length of the intake pressure introduction passage (18) in the axial direction of the throttle intake passage (6). Compared to the above, the opening area of the passage inlet (18a) of the intake introduction passage (18) can be made larger, the passage cross-sectional area of the intake introduction passage (18) can be reduced, and it is less susceptible to the pulsation of the intake pressure. At the same time, the opening area of the passage inlet (18a) of the intake passage (18) can be increased to prevent clogging of liquid fuel in the passage inlet (18a).
For the above reasons, the detection of the intake pressure by the intake pressure detection sensor (15) is stabilized, the problem that the fuel injection amount from the injector (8) fluctuates unnecessarily is eliminated, and the air-fuel mixture is more evenly distributed to each cylinder (3). The function that can be distributed to is high.

(Invention according to claim 10)
In addition to the effects of the invention according to any one of claims 6 to 9, the following effects are provided.
<Effect> The function of distributing the air-fuel mixture more uniformly to each cylinder is high.
As illustrated in FIG. 5A, an attachment hole (20) is formed downward, an intake pressure detection sensor (15) is attached to the attachment hole (20), and a liquid fuel is provided below the attachment hole (20). Since the reservoir (21) is provided and the passage outlet (18b) of the intake pressure introduction passage (18) is opened above the liquid fuel reservoir (21), the liquid fuel that has entered the intake pressure introduction passage (18) In addition to flowing out from the passage inlet (18a) of the intake pressure introduction passage (18) to the throttle intake passage (6), it may flow out from the passage outlet (18b) of the intake pressure introduction passage (18) to the liquid fuel reservoir (21). The clogging of the liquid fuel in the intake pressure introduction passage (18) hardly occurs. Further, since the liquid fuel or dust that has entered the intake pressure introduction passage (18) is collected in the liquid fuel reservoir (21) and does not contact the intake pressure detection sensor (15), the malfunction or sensitivity of the intake pressure detection sensor (15) is reduced. Decline can be prevented. For this reason, the detection of the intake pressure by the intake pressure detection sensor (15) is stabilized, there is no problem that the fuel injection amount from the injector (8) fluctuates unnecessarily, and the air-fuel mixture is more evenly distributed to each cylinder (3). High functionality.

(Invention of Claim 11)
In addition to the effects of the invention according to any one of claims 6 to 10, the following effects are achieved.
<Effect> The fuel supply device becomes compact.
As illustrated in FIG. 3A, an injector (8) is arranged after the throttle input arm (22), and a mounting hole (20) of the intake pressure detection sensor (15) is placed beside the throttle input arm (22). Since the boss (20a) is arranged, the rear space and the lateral space of the throttle input arm (22) can be used effectively as the arrangement space for the injector (8) and the boss (20a), respectively, and fuel supply related parts can be used as a throttle. The fuel supply device is made compact by being integrated into the body (5).

(Invention of Claim 12)
In addition to the effect of the invention according to claim 11, the following effect is achieved.
<Effect> The number of parts can be reduced.
As illustrated in FIG. 3A, the boss (20a) of the mounting hole (20) of the intake pressure detection sensor (15) is also used as a stopper for swinging the throttle input arm (22). (22) It is not necessary to provide a dedicated swing stopper, and the number of parts can be reduced.

(Invention of Claim 13)
In addition to the effects of the invention according to any one of claims 1 to 12, the following effects are provided.
<Effect> A function capable of more evenly distributing the air-fuel mixture to each cylinder is high.
As illustrated in FIG. 4A, the extension axis (8b) of the injector (8) is the valve axis of the throttle valve (7) on the projection orthogonal to the central axis (6a) of the throttle intake passage (6). Since the direction of the injector (8) is set so as to be parallel to (12), the flight distance of the fuel spray can be made relatively long, the atomization of the liquid fuel is promoted, and the intake distribution passage ( The air-fuel mixture concentration in 2) is made more uniform, and the function of evenly distributing the air-fuel mixture to each cylinder (3) is high.

(Invention according to Claim 14)
In addition to the effects of the invention according to any one of claims 1 to 12, the following effects are provided.
<Effect> A function capable of more evenly distributing the air-fuel mixture to each cylinder is high.
As illustrated in FIG. 4B, the tip end portion (9) of the injector (8) is disposed directly behind the valve shaft (12) of the throttle valve (7), and the central axis line of the throttle intake passage (6) ( On the projection orthogonal to 6a), the orientation of the injector (8) was set so that the extension axis (8b) of the injector (8) was inclined with respect to the valve shaft (12) of the throttle valve (7). Therefore, it is possible to inject liquid fuel in a direction where the flight distance of the spray fuel is long and easy to receive direct intake air intake, the atomization of the liquid fuel is promoted, and the concentration distribution of the air-fuel mixture in the intake air distribution passage (2) is The function is more uniform and the distribution of the air-fuel mixture to each cylinder (3) is more uniform.

  Embodiments of the present invention will be described with reference to the drawings. FIGS. 1 to 7 are views for explaining a multi-cylinder engine according to an embodiment of the present invention. In this embodiment, a vertical water-cooled in-line three-cylinder engine will be described.

The outline of the embodiment of the present invention is as follows.
As shown in FIG. 7, in this engine, the cylinder head (1) is assembled to the upper part of the cylinder block (24), the head cover (25) is assembled to the upper part of the cylinder head (1), and the lower part of the cylinder block (25) is assembled. An oil pan (26) is assembled, a gear case (27) is assembled at the front of the cylinder block (24), and a flywheel (28) is arranged at the rear of the cylinder block (24). An engine cooling fan (29) is disposed at the front of the gear case (27).

  As shown in FIG. 6, the intake air distribution passage (2) is attached to the cylinder head (1), and the air-fuel mixture is distributed to the plurality of cylinders (3) through the intake air distribution passage (2). A throttle body (5) is attached to the single distribution passage inlet (4) of the fuel tank, and liquid fuel is supplied to the throttle body (5).

  Although the intake distribution passage (2) is generally called an intake manifold, it is particularly called the intake distribution passage (2) because it has a box shape without branch pipes. As shown in FIG. 6, the number of cylinders (3) is three, and these will be referred to as the first cylinder, the second cylinder, and the third cylinder from the engine cooling fan (29) side. The single distribution passage inlet (4) is arranged at the end of the intake distribution passage (2) on the third cylinder side, and is viewed in a direction parallel to the cylinder center axis (30) as shown in FIG. With the flywheel (28) side as the rear, it is directed obliquely at an angle of 60 ° with respect to the crankshaft central axis (31). The liquid fuel supplied to the throttle body (5) is gasoline.

The structure of the fuel supply device is as follows.
As shown in FIG. 1A, a throttle intake passage (6) is provided in the throttle body (5), a throttle valve (7) is disposed in the throttle intake passage (6), and the throttle body (5 1), an injector (8) is attached, and the tip (9) of this injector (8) is placed in the throttle intake passage (6) downstream of the throttle valve (7), as shown in FIG. 1 (B). Thus, the liquid fuel injection port (10) is opened at the tip (9) of the injector (8).
An intake pipe connection pipe (34) is attached to the intake passage inlet (6b) of the throttle intake path (6), and a lead-out end portion of the intake pipe (35) led out from an air cleaner (not shown) to the intake pipe connection pipe (34). Is connected. As shown in FIG. 7, the throttle valve (7) is linked to the speed control lever (43) via the mechanical governor (42).

The relationship between the throttle valve and the injector is as follows.
As shown in FIG. 1 (A) and FIG. 2, the direction of the central axis (6a) of the throttle intake passage (6) is the front-rear direction, and the downstream side of the valve shaft (12) of the throttle valve (7) is rearward. As described above, a butterfly valve is used as the throttle valve (7), and the tip (9) of the injector (8) is disposed behind the valve shaft (12) of the throttle valve (7). Assuming an extension axis (8b) of the injector (8) extending from the central axis (8a) through the tip (9) of the injector (8) into the throttle intake passage (6), shown in FIG. Thus, on the projection orthogonal to the central axis (6a) of the throttle intake passage (6), the passage space (6d) (6e) located on both sides of the valve shaft (12) of the throttle valve (7). Of the injector (8) so that the extension axis (8b) of the injector (8) is biased in one passage space (6d). Is set. This one passage space (6d) is closer to the first cylinder.

  As shown in FIG. 4 (A), on the projection orthogonal to the central axis (6a) of the throttle intake passage (6), the extension axis (8b) of the injector (8) is the throttle valve (7). The direction of the injector (8) is set so as to be parallel to the valve shaft (12). Further, as shown in FIG. 4B, the tip end portion (9) of the injector (8) is arranged directly behind the valve shaft (12) of the throttle valve (7), and the center of the throttle intake passage (6) is arranged. On the projection orthogonal to the axis (6a), the injector (8) is arranged such that the extension axis (8b) of the injector (8) is inclined with respect to the valve shaft (12) of the throttle valve (7). The direction may be set. The angle (8α) formed by the extension axis (8b) of the injector (8) with respect to the valve axis (12) of the throttle valve (7) on the projection orthogonal to the central axis (6a) of the throttle intake passage (6). ) Is set to 30 °. This angle (8α) is preferably 15 ° or more and 45 ° or less. As shown in FIG. 2, “behind the valve shaft (12)” refers to the central axis (6a) of the throttle intake passage (6) from the valve shaft (12) when viewed in a direction parallel to the valve shaft (12). The position which moved back along.

The configuration of the liquid fuel injection port is as follows.
As shown in FIG. 1 (B), four liquid fuel injection ports (10) are provided, and as shown in FIG. 1 (A) and FIG. 2, a throttle intake passage (6) is connected to each liquid fuel injection port (10). ) Assuming the injection axis (10a) of the liquid fuel injection port (10) extending inward, the injection axis (10a) of the liquid fuel injection port (10) with respect to the extension axis (8b) of the injector (8). The direction of the liquid fuel injection port (10) is set so that the angle formed by From the viewpoint of concentrating the liquid fuel injected from the liquid fuel injection port (10) in the passage space (6d) on one side, the angle is preferably 30 ° or less, more preferably 25 ° or less, and most preferably 20 ° or less. desirable. Further, from the viewpoint of suppressing the overlapping of the sprays of the liquid fuel injected from the liquid fuel injection ports (10) and suppressing the oil droplets of the liquid fuel from becoming larger due to the coupling, the angle is desirably 5 ° or more. 7 ° or more is more desirable, and 10 ° or more is most desirable. Therefore, from both viewpoints, the angle is preferably 5 ° or more and 30 ° or less, more preferably 7 ° or more and 25 ° or less, and most preferably 10 ° or more and 20 ° or less. There may be a single liquid fuel injection port (10). In this case, the extension axis (8b) of the injector (8) may coincide with the injection axis (10a) of the liquid fuel injection port (10).

The structure related to the injection direction of the injector is as follows.
As shown in FIG. 1 (A), a cylindrical insulator (14) is provided between a distribution passage inlet (4) of the intake distribution passage (2) and an intake passage outlet (13) of the throttle intake passage (6). Is interposed. The injector (8) is inclined so that the tip (9) of the injector (8) having the liquid fuel injection port (10) faces the downstream side of the throttle intake passage (6), and the injector (8) With the extension axis (8b) directed toward the inner peripheral surface of the insulator (14), the liquid fuel injected from the liquid fuel injection port (10) becomes the inner periphery of the intake passage outlet (13) of the throttle intake passage (6). Colliding with the surface and the inner peripheral surface of the insulator (14).
Instead of this structure, the extension axis (8b) of the injector (8) is directed from the liquid fuel injection port (10) toward the inner peripheral surface of the intake passage outlet (13) of the throttle intake passage (6). The liquid fuel may collide with the inner peripheral surface of the intake passage outlet (13) of the throttle intake passage (6) and the inner peripheral surface of the insulator (14).

The control structure for liquid fuel injection and the like is as follows.
As shown in FIG. 1A, the control means (17) includes an intake pressure detection sensor (15) for detecting the intake pressure of the throttle intake passage (6) and an engine speed sensor (16) for detecting the engine speed. 6), the control means (17) controls the liquid fuel injection amount and liquid fuel injection timing from the injector (8) based on the intake pressure and the engine speed based on the intake pressure and the engine speed. The ignition timing of the spark plug (36) shown in FIG. The intake pressure detection sensor (15) has a function of detecting the intake air temperature, and the control means (17) corrects the liquid fuel injection amount based on the intake air temperature. The control means (17) is a microcomputer.

The structure related to the intake pressure detection sensor is as follows.
As shown in FIG. 1 (A), the intake pressure detection sensor (15) is attached to the throttle body (5) together with the injector (8). An intake pressure introduction passage (18) for introducing the intake pressure in the throttle intake passage (6) to the intake pressure detection sensor (15) is provided in the peripheral wall of the throttle intake passage (6) of the throttle body (5). Yes. The throttle inlet passage (6a) has a passage inlet (18a) of the intake pressure introduction passage (18) upstream of the injector (8) and downstream of the valve shaft (12) of the throttle valve (7). ).

The setting of the direction of the intake pressure introduction passage is as follows.
As shown in FIG. 4 (A), a transverse line (19) crossing the throttle intake passage (6) having a circular cross section in the radial direction and toward the passage inlet (18a) of the intake pressure introduction passage (18); Assuming a transverse extension line (19a) extending from the transverse line (19) to the outside of the throttle intake passage (6) through the passage inlet (18a) of the intake pressure introduction passage (18), this transverse extension line The direction of the intake pressure introduction passage (18) to be drilled is set so that the angle formed by the intake pressure introduction passage (18) is 60 ° with respect to (19a). Even if the direction of the intake pressure introduction passage (18) is closer to the tangential direction than the radial direction of the throttle intake passage (6) and the passage cross-sectional area of the intake introduction passage (18) is reduced, the intake pressure introduction passage (18) From the viewpoint of making it possible to increase the opening area of the passage inlet (18a), the angle is preferably 45 ° or more, more preferably 50 ° or more, and 55 ° or more. Is more desirable. Further, there is no problem that the direction of the intake pressure introduction passage (18) is too close to the tangential direction of the inner peripheral surface of the throttle intake passage (6), and from the viewpoint of facilitating the machining of the intake pressure introduction passage (18), The angle is desirably 75 ° or less, more desirably 70 ° or less, and most desirably 65 ° or less. Therefore, from both viewpoints, the angle is preferably 45 ° or more and 75 ° or less, more preferably 50 ° or more and 70 ° or less, and 55 ° or more and 65 ° or less. Most desirable.

  As shown in FIG. 4 (A), the intake pressure introduction passage (18) with respect to the transverse extension line (19a) on a projection orthogonal to the central axis (6a) of the throttle intake passage (6). The direction of the intake pressure introduction passage (18) is set so that the angle (18α) formed by The direction of the intake pressure introduction passage (18) is too close to the axial direction of the throttle intake passage (6) to avoid the problem that the intake pressure introduction passage (18) becomes unnecessarily long. From the viewpoint of facilitating processing, this angle (18α) is preferably 45 ° or more, more preferably 50 ° or more, and most preferably 55 ° or more. Further, there is no problem that the direction of the intake pressure introduction passage (18) is too close to the tangential direction of the inner peripheral surface of the throttle intake passage (6), and from the viewpoint of facilitating the machining of the intake pressure introduction passage (18), The angle (18α) is desirably 75 ° or less, more desirably 70 ° or less, and most desirably 65 ° or less. Therefore, from both viewpoints, the angle (18α) is preferably 45 ° or more and 75 ° or less, more preferably 50 ° or more and 70 ° or less, and 55 ° or more and 65 ° or less. It is most desirable to do.

As shown in FIG. 5 (B), a butterfly valve is used for the throttle valve (7), and a central axis (6a) of the throttle intake passage (6) and a valve shaft (12) of the throttle valve (7) are provided. A passage of the intake pressure introduction passage (18) so that the passage inlet (18a) of the intake pressure introduction passage (18) overlaps the central axis (6a) of the throttle intake passage (6) on a parallel projection. An inlet (18a) is arranged.
The intake pressure introduction passage (18) is inclined downward from the passage outlet (18b) toward the passage inlet (18b), and from the central axis (6a) of the throttle intake passage (6) to the throttle intake passage (6). Assuming an extension axis (6c) extending outside the throttle intake passage (6) through the passage inlet (6b), as shown in FIG. 5 (B), the central axis (6a) of the throttle intake passage (6) is shown. And an angle formed by the intake pressure introduction passage (18) with respect to the extension axis (6c) of the throttle intake passage (6) on a projection parallel to the valve shaft (12) of the throttle valve (7) The direction of the intake pressure introduction passage (18) is set so that (18β) is 60 °.

  From the viewpoint of facilitating the flow of liquid fuel that has entered the intake pressure introduction passage (18) by its own weight, the angle (18β) is preferably 45 ° or more, more preferably 50 ° or more, and 55 °. The above is most desirable. The intake pressure introduction passage (18) is elongated in the axial direction of the throttle intake passage (6), and the opening of the passage inlet (18a) of the intake introduction passage (18) is larger than the passage sectional area of the intake introduction passage (18). From the viewpoint of increasing the area, the angle (18β) is desirably 75 ° or less, more desirably 70 ° or less, and most desirably 65 ° or less. From both viewpoints, the angle (18β) is preferably 45 ° or more and 75 ° or less, more preferably 50 ° or more and 70 ° or less, and 55 ° or more and 65 ° or less. Is most desirable.

The configuration of the mounting hole of the intake pressure detection sensor is as follows.
As shown in FIG. 5 (A), a mounting hole (20) for the intake pressure detection sensor (15) is formed in the throttle body (5), and the intake pressure introduction passage (18) is formed in the mounting hole (20). Communicate. The attachment hole (20) is formed downward, an intake pressure detection sensor (15) is attached to the attachment hole (20), and a liquid fuel reservoir (21) is provided below the attachment hole (20). A passage outlet (18b) of the intake pressure introduction passage (18) is opened at an upper portion of the reservoir (21).

The arrangement of parts to be attached to the throttle body is as follows.
As shown in FIG. 3A, the direction of the central axis (6a) of the throttle intake passage (6) is the front-rear direction, and the downstream side of the valve shaft (12) of the throttle valve (7) is the rear. The injector (8) is disposed after the throttle input arm (22) with the direction orthogonal to the front-rear direction as the horizontal direction when viewed in a direction parallel to the valve shaft (12) of the valve (7), and the throttle A boss (20a) of the mounting hole (20) of the intake pressure detection sensor (15) is disposed beside the input arm (22). The boss (20a) of the mounting hole (20) of the intake pressure detection sensor (15) is also used as a stopper for swinging the throttle input arm (22).

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view for explaining a throttle body and its peripheral parts of a multi-cylinder engine according to an embodiment of the present invention. FIG. 1 (A) is a longitudinal side view, and FIG. FIG. It is the II-II sectional view taken on the line of FIG. FIG. 3A is a plan view and FIG. 3B is a side view illustrating the throttle body of FIG. 1. 4A is a view taken in the direction of the arrow IV in FIG. 3B, and FIG. 4B is a schematic diagram illustrating an example of changing the direction of the injector. FIG. 5A is a cross-sectional view taken along line VV in FIG. 3A, and FIG. 5B is a longitudinal side view of the throttle body. 1 is a plan view of a multi-cylinder engine according to an embodiment of the present invention. It is a side view of the engine of FIG.

Explanation of symbols

(1) Cylinder head
(2) Intake distribution passage
(3) Cylinder
(4) Distribution passage entrance
(5) Throttle body
(6) Throttle intake passage
(6a) Center axis
(6b) Inlet passage entrance
(6c) Extension axis
(6d) Aisle space
(6e) Aisle space
(7) Throttle valve
(8) Injector
(8a) Center axis
(8b) Extension axis
(9) Tip
(10a) Injection axis
(11) Gas fuel outlet
(12) Valve stem
(13) Inlet passage exit
(14) Insulator
(15) Intake pressure detection sensor
(16) Engine speed sensor
(17) Control means
(18) Intake pressure introduction passage
(18a) Passage entrance
(18b) Passage exit
(18α) Angle
(18β) Angle
(19) Crossing line
(19a) Transverse extension line
(20) Mounting hole
(20a) Boss
(21) Liquid fuel reservoir

Claims (14)

An intake distribution passage (2) is attached to the cylinder head (1), and an air-fuel mixture is distributed to a plurality of cylinders (3) through the intake distribution passage (2). A single distribution passage inlet of the intake distribution passage (2) In a multi-cylinder engine in which a throttle body (5) is attached to (4) and liquid fuel is supplied to the throttle body (5),
A throttle intake passage (6) is provided in the throttle body (5), a throttle valve (7) is arranged in the throttle intake passage (6), and an injector (8) is attached to the throttle body (5). The tip (9) of the injector (8) faces the throttle intake passage (6) downstream of the throttle valve (7), and a liquid fuel injection port (9) is inserted into the tip (9) of the injector (8). 10)
The direction of the central axis (6a) of the throttle intake passage (6) is the front-rear direction, and the downstream side of the valve shaft (12) of the throttle valve (7) is the rear.
A butterfly valve is used as the throttle valve (7), and the tip (9) of the injector (8) is disposed behind the valve shaft (12) of the throttle valve (7). The central axis of the injector (8) Assuming the extension axis (8b) of the injector (8) extending from (8a) through the tip (9) of the injector (8) into the throttle intake passage (6),
Among the passage inner spaces (6d) and (6e) located on both sides of the valve shaft (12) of the throttle valve (7) on the projection orthogonal to the central axis (6a) of the throttle intake passage (6), A multi-cylinder engine characterized in that the direction of the injector (8) is set so that the extension axis (8b) of the injector (8) is biased in any one of the passage spaces (6d). The multi-cylinder engine according to claim 1,
Assuming an injection axis (10a) of the liquid fuel injection port (10) extending from the liquid fuel injection port (10) into the throttle intake passage (6), with respect to the extension axis (8b) of the injector (8), A multi-cylinder engine characterized in that the direction of the liquid fuel injection port (10) is set so that an angle formed by an injection axis (10a) of the liquid fuel injection port (10) is 30 ° or less. The multi-cylinder engine according to claim 2,
A plurality of the liquid fuel injection ports (10) are provided, and the angle formed by the injection axis (10a) of each liquid fuel injection port (10) with respect to the extension axis (8b) of the injector (8) is 5 ° or more, respectively. The multi-cylinder engine is characterized in that the direction of the liquid fuel injection port (10) is set as described above. The multi-cylinder engine according to any one of claims 1 to 3,
A cylindrical insulator (14) is interposed between the distribution passage inlet (4) of the intake distribution passage (2) and the intake passage outlet (13) of the throttle intake passage (6);
The injector (8) is inclined so that the tip (9) of the injector (8) having the liquid fuel injection port (10) faces the downstream side of the throttle intake passage (6), and the injector (8) The extension axis (8b) is directed toward the inner peripheral surface of the insulator (14) so that the liquid fuel injected from the liquid fuel injection port (10) collides with the inner peripheral surface of the insulator (14). Multi-cylinder engine characterized by The multi-cylinder engine according to any one of claims 1 to 3,
A cylindrical insulator (14) is interposed between the distribution passage inlet (4) of the intake distribution passage (2) and the intake passage outlet (13) of the throttle intake passage (6);
The injector (8) is inclined so that the tip (9) of the injector (8) faces the downstream side of the throttle intake passage (6), and the extension axis (8b) of the injector (8) is used as the throttle intake passage. The liquid fuel injected from the liquid fuel injection port (10) toward the inner peripheral surface of the intake passage outlet (13) of (6) is the inner peripheral surface of the intake passage outlet (13) of the throttle intake passage (6). And a multi-cylinder engine that collides with the inner peripheral surface of the insulator (14). The multi-cylinder engine according to any one of claims 1 to 5,
An intake pressure detection sensor (15) for detecting the intake pressure of the throttle intake passage (6) and an engine speed sensor (16) for detecting the engine speed are connected to the injector (8) via a control means (17). In cooperation, the control means (17) controls the liquid fuel injection amount from the injector (8) based on the intake pressure and the engine speed,
The intake pressure detection sensor (15) is attached to the throttle body (5) together with the injector (8),
An intake pressure introduction passage (18) for introducing the intake pressure in the throttle intake passage (6) to the intake pressure detection sensor (15) is provided in the peripheral wall of the throttle intake passage (6) of the throttle body (5),
A multi-cylinder engine characterized in that a passage inlet (18a) of the intake pressure introduction passage (18) is opened upstream of the injector (8) on an inner peripheral surface of the throttle intake passage (6). . The multi-cylinder engine according to claim 6,
The throttle intake passage (6) having a circular cross section crosses the throttle intake passage (6) in the radial direction and extends to the passage inlet (18a) of the intake pressure introduction passage (18), and the suction line from the transverse line (19). Assuming a transverse extension line (19a) extending outside the throttle intake passage (6) through the passage inlet (18a) of the pressure introduction passage (18), the intake pressure is increased with respect to the transverse extension line (19a). A multi-cylinder engine characterized in that the direction of the intake pressure introduction passage (18) to be drilled is set so that the angle formed by the introduction passage (18) is not less than 45 ° and not more than 75 °. The multi-cylinder engine according to claim 7,
An angle (18α) formed by the intake pressure introduction passage (18) with respect to the transverse extension line (19a) is 45 ° or more on the projection orthogonal to the central axis (6a) of the throttle intake passage (6). The multi-cylinder engine is characterized in that the direction of the intake pressure introduction passage (18) is set so as to be 75 ° or less. The multi-cylinder engine according to claim 7 or 8,
A butterfly valve is used as the throttle valve (7), and the intake pressure is shown on a projection parallel to the central axis (6a) of the throttle intake passage (6) and the valve shaft (12) of the throttle valve (7). The passage inlet (18a) of the intake pressure introduction passage (18) is arranged so that the passage inlet (18a) of the introduction passage (18) overlaps the central axis (6a) of the throttle intake passage (6).
The intake pressure introduction passage (18) is inclined downward from the passage outlet (18b) toward the passage inlet (18b), and from the central axis (6a) of the throttle intake passage (6) to the throttle intake passage (6). Assuming an extension axis (6c) extending outside the throttle intake passage (6) through the passage inlet (6b), the central axis (6a) of the throttle intake passage (6) and the valve shaft of the throttle valve (7) On the projection parallel to (12), the angle (18β) formed by the intake pressure introduction passage (18) with respect to the extension axis (6c) of the throttle intake passage (6) is 45 ° or more and 75 °. A multi-cylinder engine characterized in that the direction of the intake pressure introduction passage (18) is set as follows. The multi-cylinder engine according to any one of claims 6 to 9,
A mounting hole (20) for the intake pressure detection sensor (15) is formed in the throttle body (5), and the intake pressure introduction passage (18) is communicated with the mounting hole (20).
The attachment hole (20) is formed downward, the intake pressure detection sensor (15) is attached to the attachment hole (20), and a liquid fuel reservoir (21) is provided below the attachment hole (20). A multi-cylinder engine characterized in that a passage outlet (18b) of the intake pressure introduction passage (18) is opened at an upper portion of a fuel reservoir (21). The multi-cylinder engine according to any one of claims 6 to 10,
The direction of the central axis (6a) of the throttle intake passage (6) is the front-rear direction, and the downstream side of the valve shaft (12) of the throttle valve (7) is the rear.
Looking in a direction parallel to the valve shaft (12) of the throttle valve (7), the direction perpendicular to the front-rear direction is defined as the left-right lateral direction.
The injector (8) is disposed after the throttle input arm (22), and the boss (20a) of the mounting hole (20) of the intake pressure detection sensor (15) is disposed beside the throttle input arm (22). Multi-cylinder engine characterized by that. The multi-cylinder engine according to claim 11, wherein
A multi-cylinder engine characterized in that a boss (20a) of a mounting hole (20) of the intake pressure detection sensor (15) is also used as a stopper for swinging the throttle input arm (22). The multi-cylinder engine according to any one of claims 1 to 12,
On the projection orthogonal to the central axis (6a) of the throttle intake passage (6), the extension axis (8b) of the injector (8) is oriented in parallel with the valve shaft (12) of the throttle valve (7). The multi-cylinder engine is characterized in that the direction of the injector (8) is set as described above. The multi-cylinder engine according to any one of claims 1 to 12,
The tip (9) of the injector (8) is disposed directly behind the valve shaft (12) of the throttle valve (7),
On the projection orthogonal to the central axis (6a) of the throttle intake passage (6), the extension axis (8b) of the injector (8) is inclined with respect to the valve shaft (12) of the throttle valve (7). Thus, the multi-cylinder engine characterized by setting the direction of the injector (8).

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