JP3594873B2 - Multi-cylinder gasoline engine - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a multi-cylinder gasoline engine, and more particularly to an engine capable of optimizing the concentration of a gasoline mixture supplied to each cylinder.
[0002]
[Prior art]
FIG. 4 shows a conventional multi-cylinder engine.
The configuration of this engine is as follows.
A box-shaped intake manifold 103 is mounted on an intake port side wall surface 102 of a cylinder head 101, and a cab mounting seat 104 is formed at one end of the intake manifold 103. Of the two ends of the intake manifold 103, a cab mounting seat 104 is formed. When one side is regarded as the rear side and the opposite side is regarded as the front side, the outlet side extension line 110a of the central axis 110 of the intake passage 109 of the carburetor 105 is inclined obliquely forward toward the intake port side wall surface 102 of the cylinder head 101. As viewed in a direction parallel to the cylinder center axis 108, the angle α at which the outlet side extension line 110a intersects with the intake port side wall surface 102 is 35 °, and both sides of the throttle valve 106 of the carburetor 105 The gasoline mixture is blown so that the surface 107 faces backward. did.
[0003]
[Problems to be solved by the invention]
In the above prior art, there is a problem that the temperature of the exhaust gas discharged from the rearmost cylinder S3 is high, which raises the overall exhaust gas temperature.
An object of the present invention is to provide a multi-cylinder gasoline engine that can solve the above problems.
[0004]
[Procedure leading to the invention]
The inventors of the present invention have obtained the following findings in experiments preceding the present invention.
That is, in the engine having the above-described configuration, as shown in FIG. 1A, when viewed in a direction parallel to the cylinder center axis 8, the angle α at which the outlet side extension line 10 a intersects with the intake port side wall surface 2 is 30 degrees. When the angle is in the range of 60 ° to 60 °, assuming that the width dimension in the front-rear direction of the rearmost intake port inlet E3 is w, as shown in FIG. The position deviated rearward from the front end 11 of the intake port inlet E3 by about 0.1 w is the optimum intersection P, and as shown in FIG. 1A, the intersection between the outlet side extension line 10a and the intake port side wall surface 2 The concentration of the gasoline mixture supplied to the rearmost cylinder S3 is optimized as X approaches the optimum intersection P at a position about 2w away from the center point 9b of the outlet 9a of the outlet 9a of the intake passage 9 of the carburetor 5. , You can see that the exhaust temperature is low It was.
[0005]
In the prior art, as shown in FIG. 4, the intersection point X is shifted from the optimum intersection point P by more than the dimension 2w or more, and the concentration of the gasoline mixture supplied to the rearmost cylinder S3 is reduced. It has been found that the temperature of the exhaust gas discharged from the rearmost cylinder S3 increases because the mixture becomes thinner than the target appropriate air-fuel mixture and approaches the stoichiometric air-fuel ratio. On the other hand, it was also found that when the intersection X greatly deviates rearward from the optimum intersection P, the concentration of the gasoline mixture supplied to the rearmost portion S3 becomes higher than the appropriate value, causing incomplete combustion and lowering the output.
The inventors of the present invention can optimize the concentration of the gasoline mixture supplied to the rearmost cylinder S3 by bringing the intersection point X closer to the optimum intersection point P based on the above discovery, and achieve high output. The present invention was deemed to be able to lower the exhaust temperature while maintaining the temperature.
[0006]
[Means for Solving the Problems]
(Invention of claim 1)
The configuration of the invention of claim 1 is as follows.
As shown in FIG. 1 (A), a box-shaped intake manifold 3 is mounted on an intake port side wall surface 2 of a cylinder head 1, and a cab mounting seat 4 is formed at one end of the intake manifold 3. Assuming that the side having the cab mounting seat 4 is the rear side and the opposite side is the front side, the outlet side extension line 10 a of the central axis 10 of the intake passage 9 of the carburetor 5 is located on the intake port side of the cylinder head 1. As shown in FIG. 1 (A), when viewed in a direction parallel to the cylinder center axis 8, the angle at which the outlet side extension line 10 a and the intake port side wall surface 2 intersect as shown in FIG. is set to 30 ° to 60 °, and among the two surfaces of the throttle valve 6 of the carburetor 5, the surface 7 to which the gasoline mixture is blown has a rearward posture. In phosphorus engine,
As shown in FIG. 1A, when viewed in a direction parallel to the cylinder center axis 8, the width of the rearmost intake port inlet E3 in the front-rear direction is w, and as shown in FIG. On the side wall surface 2 of the intake port, a position shifted from the front end 11 of the rearmost intake port entrance E3 by a distance of 0.1 w behind is defined as the optimum intersection point P, and a range of 0.5 w each before and after the optimum intersection point P is appropriate. As the intersection area R,
As shown in FIG. 1A, when viewed in a direction parallel to the cylinder center axis 8, the intersection X between the outlet-side extended line 10 a and the intake port side wall surface 2 corresponds to the outlet 9 a of the intake passage 9 of the carburetor 5. A multi-cylinder gasoline engine characterized in that it is located within a proper region R as shown in FIG. 1B at a position distant from the center point 9b by a dimension w to 3w.
[0007]
(Invention of claim 2)
The structure of the invention according to claim 2 is as follows.
The multi-cylinder gasoline engine according to claim 1,
As shown in FIG. 1A, at a position forward of the rearmost intake port entrance E3 and rearward of the foremost intake port entrance E1, the intake port of the cylinder head 1 is moved from the wall of the intake manifold 3 to the rear. A multi-cylinder gasoline engine characterized in that a deflection guide piece (12) projects toward a side wall surface (2).
[0008]
Function and effect of the present invention
(Invention of claim 1)
The invention of claim 1 has the following operation and effect.
When the intersection X is shifted forward from the appropriate range R, the concentration of the gasoline mixture supplied to the rearmost cylinder S3 becomes thinner than the appropriate value, and the exhaust temperature increases. If the intersection X is shifted to the rear of the appropriate range R, the concentration of the gasoline mixture supplied to the rearmost cylinder S3 becomes too rich than the appropriate value, and the output decreases. On the other hand, when the intersection X is located within the appropriate range R, the intersection X is located on the optimal intersection P or close to the optimal intersection P, so that the supply to the rearmost cylinder S3 is performed. The concentration of the gasoline mixture to be discharged is optimized, and the exhaust temperature can be lowered while maintaining high output.
[0009]
(Invention of claim 2)
The invention of claim 2 has the following effect in addition to the effect of the invention of claim 1.
As shown in FIG. 1A, the flow of the gasoline mixture in the intake manifold 3 is adjusted by the deflection guide piece 12, so that the concentration of the gasoline mixture supplied to each of the cylinders S1 to S3 is optimized. be able to.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to the drawings.
1 to 3 are diagrams illustrating a multi-cylinder gasoline engine according to an embodiment of the present invention. In this embodiment, a vertical three-cylinder gasoline engine is used.
The configuration of this engine is as follows.
As shown in FIG. 3, the cylinder head 1 and the head cover 15 are sequentially assembled on the upper part of the cylinder block 13, and the oil pan 16 is assembled on the lower part of the cylinder block 13. A gear case 17 is attached to the front of the cylinder block 13, a cooling fan 19 is attached to the front of the gear case 17, and a flywheel 18 is arranged at the rear of the cylinder block 13. As shown in FIG. 2, a box-shaped intake manifold 3 and a branch-shaped exhaust manifold 14 are mounted on the intake port side wall surface 2 and the exhaust port side wall surface 20 on both sides of the cylinder head 1, respectively. A carburetor 5 is attached to one end of the intake manifold 3. In the carburetor 5, the supply of gas fuel and the supply of gasoline can be switched mutually.
[0011]
The configuration of the cylinder head 1 is as follows.
As shown in FIG. 1A, the cylinder head 1 includes intake ports K1 to K3 of the cylinders S1 to S3. When viewed in a direction parallel to the cylinder center axis 8, the intake ports K <b> 1 to K <b> 3 are formed in a direction orthogonal to the crankshaft axis 21. Assuming that the direction of the crankshaft axis 21 is the front-rear direction, the width dimension in the front-rear direction of each of the intake port inlets E1 to E3 is w, and the adjacent intake port inlets E1 to E3 are separated from each other at intervals of 2w. .
[0012]
The structure of the intake manifold 3 is as follows.
The intake manifold 3 has a box shape, and is entirely open on the side of the cylinder head 1 facing the intake port side wall surface 2. As shown in FIG. 1A, as viewed in a direction parallel to the cylinder center axis 8, each intake port inlet E2 of the intake port K3 of the third cylinder S3 and the intake port K2 of the second cylinder S2 adjacent thereto. When the space between E3 is the rear entrance portion 22, the width between the rear entrance portion 22 and the rear wall portion 24 of the intake manifold 3 facing the rear entrance portion 22 is 3w. Further, when a portion of the intake port side wall surface 2 of the cylinder head 1 excluding the intake port entrance E3 of the intake port K3 of the third cylinder S3 and the portion 22 between the rear entrances is defined as a front portion 23, The width of the left / right separation between the intake manifold 3 and the front wall portion 25 facing the intake manifold 3 is 2w. The rear wall portion 24 and the front wall portion 24 of the intake manifold 3 are connected with a step, and the deflection guide piece 12 projects from the stepped boundary portion 26 toward the intake port side wall portion 2 of the cylinder head 1. As shown in FIG. 3, the deflection guide piece 12 has a plate shape with a small front-rear width, and is formed vertically long along the boundary portion 26.
[0013]
As shown in FIG. 1 (A), a cab mounting seat 4 is formed on the third cylinder S3 side of both ends of the intake manifold 3, and a side of the intake manifold 3 where the cab mounting seat 4 is located. When the rear side and the opposite side are regarded as the front side, the outlet side extension line 10a of the central axis 10 of the intake passage 9 of the carburetor 5 is inclined obliquely forward toward the intake port side wall surface 2 of the cylinder head 1. As shown in FIG. 1 (A), when viewed in a direction parallel to the cylinder center axis 8, the angle α at which the outlet side extension line 10 a intersects the intake port side wall surface 2 is set to 45 °, and the carburetor 5 Of the two surfaces of the throttle valve 6, the surface 7 to which the gasoline mixture is blown has a rearward attitude.
[0014]
Further, as shown in FIG. 1 (B), when viewed in a direction parallel to the cylinder center axis 8, on the intake port side wall surface 2, the front end 11 of the rearmost intake port inlet E3 is shifted rearward by a dimension of 0.1 w. As shown in FIG. 1 (A), the intersection X between the outlet side extension line 10a and the intake port side wall surface 2 is measured from the center point 9b of the outlet 9a of the intake passage 9 of the carburetor 5 as shown in FIG. At a position 2 w away, it is located on the optimum intersection P.
[0015]
In the above embodiment, the concentration of the gasoline mixture supplied to each of the cylinders S1 to S3 is optimized, and the temperature of the exhaust gas discharged from each of the cylinders S1 to S3 can be reduced while maintaining a high output.
[0016]
The structure of the above embodiment can be changed within the following range.
In the above embodiment, the distance between the intake ports E1 to E3 is 2w, but the distance may be changed in the range of w to 3w. If the separation dimension is less than w, the concentration of the gasoline mixture supplied to each of the cylinders other than the last cylinder, that is, the first cylinder S1 and the second cylinder S2 other than the third cylinder S3 is smaller than the appropriate value. It becomes dense and the output decreases due to incomplete combustion. If the distance exceeds 3w, the concentration of the gasoline mixture supplied to the cylinders other than the rearmost cylinder, that is, the first cylinder S1 and the second cylinder S2 other than the third cylinder S3, is lower than the appropriate value. It becomes thinner and closer to the stoichiometric air-fuel ratio, and the temperature of the exhaust gas discharged from these cylinders increases. On the other hand, when the separation dimension is in the range of w to 3w, the gasoline supplied to the cylinders other than the rearmost cylinder, that is, the first cylinder S1 and the second cylinder S2 other than the third cylinder S3, respectively. The concentration of the air-fuel mixture is optimized, and the temperature of the exhaust gas can be reduced while maintaining a high output.
[0017]
In the above-described embodiment, the width between the rear entrance portion 22 and the rear wall portion 24 of the intake manifold 3 opposed to the rear entrance portion 22 is 3 w, but may be changed in the range of 2 w to 4 w. When the left-right separation width is less than 2w, the concentration of the gasoline mixture supplied to the last cylinder, that is, the third cylinder S3, is higher than an appropriate value, and the output is reduced due to incomplete combustion. The concentration of the gasoline mixture supplied to the cylinders other than the rearmost cylinder, that is, the first cylinder S1 and the second cylinder S2 other than the third cylinder S3 becomes thinner than an appropriate value and approaches the stoichiometric air-fuel ratio, The temperature of the exhaust gas discharged from these cylinders increases. If the width of the left and right separation exceeds 4 w, the concentration of the gasoline mixture supplied to the last cylinder, that is, the third cylinder becomes thinner than an appropriate value and approaches the stoichiometric air-fuel ratio. And the concentration of the gasoline mixture supplied to each of the cylinders other than the rearmost cylinder, that is, the first cylinder S1 and the second cylinder S2 other than the third cylinder S3 is adjusted to an appropriate value. And the output decreases due to incomplete combustion. On the other hand, when the left-right separation width is 2w to 4w, the concentration of the gasoline mixture supplied to each of the cylinders S1 to S3 is optimized, and the exhaust temperature is lowered while maintaining high output. be able to.
[0018]
In the above embodiment, as shown in FIG. 1 (A), when viewed in a direction parallel to the cylinder center axis 8, the outlet side extension line 10 a of the center axis 10 of the intake passage 9 of the carburetor 5 and the intake port wall surface 2 are formed. The intersection angle α is 45 °, but this may be changed in the range of 30 ° to 60 °. If the angle α is less than 30 °, the concentration of the gasoline mixture supplied to the last cylinder, that is, the third cylinder S3, becomes thinner than an appropriate value, approaches the stoichiometric air-fuel ratio, and is discharged from this cylinder. And the concentration of the gasoline mixture supplied to each of the cylinders other than the last cylinder, that is, the first cylinder S1 and the second cylinder S2 other than the third cylinder S3, is lower than the appropriate value. It becomes dense and the output decreases due to incomplete combustion. When the angle α exceeds 60 °, the concentration of the gasoline mixture supplied to the last cylinder, that is, the third cylinder S3, becomes higher than an appropriate value, and the output decreases due to incomplete combustion. The concentration of the gasoline mixture supplied to the cylinders other than the last cylinder, that is, the first cylinder S1 and the second cylinder S2 other than the third cylinder S3 becomes thinner than an appropriate value and becomes closer to the stoichiometric air-fuel ratio. Therefore, the temperature of exhaust gas discharged from these cylinders increases. On the other hand, when the angle α is 30 ° to 60 °, the concentration of the gasoline mixture supplied to each of the cylinders S1 to S3 is optimized, and the exhaust temperature is lowered while maintaining high output. be able to. In order to obtain this advantage, it is more desirable that the angle α be 40 ° to 50 °.
[0019]
In the above embodiment, when viewed in a direction parallel to the cylinder center axis, the intersection X between the outlet-side extension line 10a and the intake port side wall surface 2 is separated from the center point 9b of the outlet 9a of the intake passage 9 of the carburetor 5 by a dimension 2w. At the position of the optimum intersection P, the intersection X is defined as a proper intersection region R before and after the optimum intersection P by a range of a size of 0.5 w, and the intersection 9 is defined as the exit 9 a of the intake passage 9 of the carburetor 5. May be located in the appropriate region R at a position away from the center point 9b by a dimension w to 3w.
[0020]
If the intersection X is less than the dimension w from the center point 9b of the outlet 9a of the intake passage 9 of the carburetor 5, the concentration of the gasoline mixture supplied to the last cylinder, that is, the third cylinder S3, is appropriate. And the output decreases due to incomplete combustion, and the gasoline mixture supplied to the cylinders other than the last cylinder, that is, the first cylinder S1 and the second cylinder S2 other than the third cylinder S3, respectively. The concentration becomes lower than the appropriate value, becomes closer to the stoichiometric air-fuel ratio, and the temperature of the exhaust gas discharged from these cylinders increases. When the intersection X is at least 3 wm away from the center point 9b of the outlet 9a of the intake passage 9 of the carburetor 5, the concentration of the gasoline mixture supplied to the last cylinder, that is, the third cylinder is appropriate. And the temperature becomes close to the stoichiometric air-fuel ratio, the temperature of the exhaust gas discharged from this cylinder increases, and the cylinders other than the rearmost cylinder, that is, the first cylinder S1 and the second cylinder other than the third cylinder S3. The concentration of the gasoline mixture supplied to each cylinder S2 becomes higher than an appropriate value, and the output decreases due to incomplete combustion.
[0021]
On the other hand, when the intersection X is shifted to the front side of the appropriate range R, the concentration of the gasoline mixture supplied to the rearmost cylinder S3 becomes lower than the appropriate value, the exhaust temperature increases, and the rearmost cylinder S3 increases. The concentration of the gasoline mixture supplied to each of the first and second cylinders other than the third cylinder S3, ie, the first and second cylinders S1 and S2 other than the third cylinder S3, becomes higher than an appropriate value, and the output decreases due to incomplete combustion. On the other hand, when the intersection X is shifted rearward from the appropriate range R, the concentration of the gasoline mixture supplied to the rearmost cylinder S3 becomes too thicker than the appropriate value, so that the output becomes lower and The concentration of the gasoline mixture supplied to each of the cylinders other than the first cylinder S1 and the second cylinder S2 other than the third cylinder S3 becomes thinner than an appropriate value and approaches the stoichiometric air-fuel ratio. The temperature of the exhaust gas discharged from the cylinder increases. On the other hand, when the intersection X is located in the appropriate region R at a position away from the center point 9b of the outlet 9a of the intake passage 9 of the carburetor 5 by a distance w to 3w, the intersection X is supplied to each of the cylinders S1 to S3. The exhaust gas temperature can be lowered while maintaining a high output by optimizing the concentration of the gasoline mixture.
[Brief description of the drawings]
FIG. 1 is a view for explaining a multi-cylinder gasoline engine according to an embodiment of the present invention. FIG. 1 (A) is a cross-sectional plan view around an intake manifold, and FIG. 1 (B) is a cross-sectional view near a rear intake port inlet. It is an enlarged plan view.
FIG. 2 is an overall plan view of the multi-cylinder gasoline engine of FIG.
FIG. 3 is an overall side view of the multi-cylinder gasoline engine shown in FIG. 1;
FIG. 4 is a cross-sectional plan view of the vicinity of an intake manifold of a multi-cylinder gasoline engine according to the related art.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Cylinder head, 2 ... Intake port side wall surface, 3 ... Intake manifold, 4 ... Cab mounting seat, 5 ... Carburetor, 6 ... Throttle valve, 7 ... Gasoline mixture blowing surface, 8 ... Cylinder center axis, 9 ... Intake Passageway, 9a ... Exit, 9b ... Center point, 10 ... Center axis line, 10a ... Exit side extension line, 11 ... Front end of E3, 12 ... Deflection guide piece.

Claims (2)

A box-shaped intake manifold (3) is mounted on the intake port side wall surface (2) of the cylinder head (1), and a cab mounting seat (4) is formed at one end of the intake manifold (3), and the intake manifold (3) is formed. Of the two end portions, the side with the cab mounting seat (4) is the rear side, and the opposite side is the front side, and the exit side extension line of the central axis (10) of the intake passage (9) of the carburetor (5). (10a) is oriented obliquely forward toward the intake port side wall surface (2) of the cylinder head (1). When viewed in a direction parallel to the cylinder center axis (8), the outlet side extension line (10a). And the intake port side wall surface (2) have an angle α of 30 ° to 60 °. Of the two surfaces of the throttle valve (6) of the carburetor (5), the surface (7) ) Is looking backwards Was formed so as to be, in a multi-cylinder gasoline engine,
When viewed in a direction parallel to the cylinder center axis (8), the width dimension in the front-rear direction of the rearmost intake port entrance (E3) is w, and the rearmost intake port entrance is located on the intake port side wall surface (2). A position shifted by 0.1 w behind the front end (11) of (E3) is defined as an optimal intersection (P), and a range of 0.5 w each before and after this optimal intersection (P) is defined as an appropriate intersection area (R). ,
When viewed in a direction parallel to the cylinder center axis (8), the intersection (X) between the outlet-side extension line (10a) and the intake port side wall surface (2) corresponds to the outlet of the intake passage (9) of the carburetor (5). A multi-cylinder gasoline engine characterized in that it is located within a proper region (R) at a position away from the center point (9b) of (9a) by a dimension w to 3w. The multi-cylinder gasoline engine according to claim 1,
At a position forward of the rearmost intake port inlet (E3) and rearward of the foremost intake port inlet (E1), the intake port side wall surface of the cylinder head (1) extends from the wall of the intake manifold (3). A multi-cylinder gasoline engine characterized in that a deflection guide piece (12) is projected toward (2).

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