JPH0234446Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention relates to an engine cooling structure in which the inner wall of the cylinder head facing the upper surface of the piston is partially recessed to form a main combustion chamber. .

(Prior art) Conventionally, this type of engine has been developed, for example, by
As disclosed in Publication No. 54-65207, etc., the inner wall of the cylinder head, which serves as the combustion chamber forming wall facing the upper surface of the piston, is partially recessed, and the main combustion chamber is formed within the recess. The compact main combustion chamber shortens the flame propagation distance to rapidly burn the air-fuel mixture, and the small space between the inner wall of the cylinder head other than the main combustion chamber and the top surface of the piston is used as a squish area. The combustion speed of the air-fuel mixture is further increased by the squish flow injected from the squish area into the main combustion chamber, and the rapid combustion of this air-fuel mixture increases the knock resistance, resulting in high compression of the air-fuel mixture and lean burn associated with it. It is well known that it can reduce fuel consumption.

(Problem that the invention aims to solve) However, in this type of engine, the main combustion chamber is biased to one side with respect to the entire combustion chamber, so the heat load around the main combustion chamber tends to be partially high. has. Therefore, when the engine is used as a multi-cylinder engine, the cooling water for cooling the engine rises from inside the cylinder block to the cylinder head around each cylinder, and then flows up into the cylinder head. The main combustion chamber is located at the end opposite to the cooling water outlet of the cylinder head. Depending on the arrangement of the main combustion chamber, there is a risk that the flow rate of cooling water around the main combustion chamber may become insufficient, resulting in a decrease in cooling performance, and there is room for improvement in terms of reliability.

The present invention has been made in view of the above, and its purpose is to move the main combustion chamber of the cylinder located at the end opposite to the cooling water outlet of the cylinder head toward the cooling water outlet. The flow of cooling water at the cylinder head should be directed to the vicinity of the main combustion chamber by appropriately selecting the flow direction of the cooling water and adjusting the flow velocity of the cooling water flowing from the cylinder block to the cylinder head. Therefore, the purpose is to actively flow cooling water around the main combustion chamber of the cylinder to improve its cooling performance.

(Means for Solving the Problems) In order to achieve the above object, the structure of the present invention is such that the inner wall of the cylinder head, which is the combustion chamber forming wall facing the upper surface of the piston, is partially recessed, and the recessed portion A main combustion chamber is formed, while a squish zone is formed on the longitudinal side of the cylinder head of the main combustion chamber, an exhaust port is opened in the main combustion chamber, and an intake port is opened in the squish zone. In a multi-cylinder engine, a cooling water outlet is provided at one longitudinal end of the cylinder head of the engine, and at least a plurality of cooling water inlets of different diameters are provided around the cylinder located at the other end of the cylinder head. , the main combustion chamber of the cylinder located at the other end of the cylinder head is arranged offset toward the above-mentioned cooling water outlet side in the longitudinal direction of the cylinder head, and a large-diameter combustion chamber is opened on the side opposite to the cooling water outlet with respect to this main combustion chamber. The cooling water inlet is arranged closer to the main combustion chamber in the longitudinal direction of the cylinder head than the small diameter inlet.

(Function) With this configuration, at the other end of the cylinder head, the cooling water that has flowed into the cylinder head from the plurality of cooling water inlet ports around the cylinder located at the other end is transferred to the cooling water at one end of the cylinder head. Head to the exit. Therefore, the portion around the main combustion chamber of the cylinder located at the opposite end of the cylinder head to the cooling water outlet passes through the cooling water inlet at the other end of the corner of the cylinder head to the cooling water outlet. It encounters not only the cooling water but also the cooling water flowing toward the cooling water outlet through the vicinity of the cooling water outlet side of the cylinder, and the area around the main combustion chamber has a greater chance of encountering the cooling water, reducing its cooling performance. can be increased.

In addition, the multiple cooling water inlets around the cylinders have different diameters, and the flow rate of the cooling water through the small-diameter cooling water inlet is fast, so after inflowing, the cooling water is concentrated in the upper part of the cooling water passage and flows downstream. This cooling water ensures cooling water for the entire cylinder head. On the other hand, since the flow rate of the cooling water flowing into the large-diameter cooling water inlet is slow, after the cooling water flows in, the cooling water flows toward the lower part of the cooling water passage and toward the downstream side. In addition, the large-diameter cooling water inlet located on the opposite side (upstream side) of the cooling water outlet to the main combustion chamber is closer to the main combustion chamber than the small-diameter inlet. The cooling water that is introduced from the cooling water passage and flows through the lower part of the cooling water passage passes near the main combustion chamber, so that the main combustion chamber can be cooled more effectively.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

In FIGS. 1 to 3, 1 is a cylinder block for forming the first to fourth cylinders 2a to 2d arranged in series in an in-line four-cylinder engine, and 3 is a cylinder block for forming each of the cylinders 2a to 2d. A cooling water passage (water jacket) formed in the cylinder block 1 so as to surround the cylinder bore portion, 4
Reference numeral 5 indicates a piston that reciprocates within each of the cylinders 2a to 2d, and 5 indicates a cylinder head that is bolted to the upper surface of the cylinder block 1 via a gasket 6. A combustion chamber 7 is defined by a portion surrounded by an upper surface 4a and an inner surface (lower surface) of the cylinder head 5. Further, a recess 8 is formed in the cylinder head inner wall 5a as the upper wall of the combustion chamber 7, which faces the upper surface 4a of each piston 4, by partially recessing a half part of the cylinder head 5 in the longitudinal direction. The recess 8 constitutes a main combustion chamber 9 that occupies the main part of the combustion chamber 7, and the portion other than the main combustion chamber 9 is in contact with the inner surface of the cylinder head 5 when the piston 4 approaches the top dead center during the compression stroke. Squeeze zone 2 for blowing out the intake air between the two into the main combustion chamber 9
It is said to be 4. (See Figure 3).

The cylinder head 5 has a cooling water passage 10 (water jacket) through which cooling water flows, and the cooling water passage 10 is opened at a predetermined position around each cylinder 2a to 2d on the inner wall 5a of the cylinder head 5. It communicates with the cooling water passage 3 in the cylinder block 1 through cooling water inlets 11, 11, . . . . On the other hand, a cooling water outlet 23 is opened at one longitudinal end of the cylinder head 5 (the left end in FIGS. 2 and 3) for allowing the cooling water in the cooling water passage 10 to flow out to the outside. (not shown), the cooling water in the cooling water passage 3 of the cylinder block 1 is introduced from each cooling water inlet 11 into the cooling water passage 10 of the cylinder head 5 from the right side in FIGS. 2 and 3. After flowing to the left, the coolant is allowed to flow out of the engine from the coolant outlet 23.

The cylinder head 5 also has an intake port 12 as a downstream end portion of an intake passage for supplying intake air to each combustion chamber 7, and an upstream end portion of an exhaust passage for discharging exhaust gas in the combustion chamber 7. An upstream end opening of the intake port 12 is opened at one side of the cylinder head 5, and a downstream end opening 12a is formed through the cylinder head inner wall facing the upper surface 4a of the piston 4. 5a is opened to the squeeze zone 24 other than the recess 8. On the other hand, the above exhaust port 1
The downstream end opening 3 is located on the other side of the cylinder head 5, and the upstream end opening 13a is located on the bottom surface of the recess 8 in the cylinder head inner wall 5a (the upper wall surface of the main combustion chamber 9).
are opened in each. The downstream end opening 12a of the intake port 12 is opened and closed by an intake valve 15 supported on the upper wall 5b of the cylinder head 5 via a valve guide 14, and the upstream end opening 13a of the exhaust port 13 is also opened and closed by the cylinder head. 5 is opened and closed by an exhaust valve 17 supported on the upper wall 5b of the exhaust valve 5 via a valve guide 16.

The main combustion chamber 9 of the first cylinder 2a located at the other longitudinal end of the cylinder head 5 (the right end in FIGS. 2 and 3) is connected to the cylinder head 5.
The cooling water outlet 23 is located at one end of the cooling water outlet 23 in the longitudinal direction. In addition, the second cylinder 2b
The main combustion chamber 9 is arranged to be biased toward the cooling water outlet 23 side, similar to the first cylinder 2a, and the third
and the respective main combustion chambers 9, 9 of the fourth cylinders 2c, 2d.
are arranged on the opposite side of the cooling water outlet 23, contrary to the first and second cylinders 2a and 2b, and as a result, each intake port 12
The downstream end openings 12a of the cylinders are arranged offset to the side opposite to the center position of the cylinder row.

Further, the cooling water inlets 11, 11, . . . include five cooling water inlets opened at both corners of the inner wall at the other longitudinal end of the cylinder head 5 (the right end in FIGS. 2 and 3). 11a, 11a, 1
1b, 11b, . . . and four cooling holes that open at one end side of the cylinder head 5 (the left end side in FIGS. 2 and 3) with respect to the first cylinder 2a located at the other end in the longitudinal direction of the cylinder head 5. Water inlet 11a, 11
a, 11b, and 11b are included. and,
These nine inlets 11a, 11a,..., 11
b, 11b, . . . are four small-diameter inlets 11a, 11a, .
It is divided into two sizes: 1b, 11b, . . . Also, among the five inlets 11a, 11a, 11b, 11b, ... located on the other end side of the cylinder head 5 (on the right side in Fig. 2) than the main combustion chamber 9, the large diameter inlets 11b, 11b, ... are opened at a position closer to the main combustion chamber 9 side when viewed from the longitudinal direction of the cylinder head 5 than the small-diameter inlet ports 11a, 11a.

Further, as shown by imaginary lines in FIG. 3, a banana-shaped intake pipe 18 constituting an intake passage is connected to the upstream end opening of each intake port 12 that opens on the side surface of the cylinder head 5. ing. That is, this banana-shaped intake pipe 18 has one collecting pipe part 18a, the upstream end is integrally connected to the collecting pipe part 18a in the shape of a banana bunch, and the downstream end is connected to each intake port 1.
2, the four branch pipe sections 18b, 18b,
..., each branch pipe portion 18 of the intake pipe 18
b is curved in an arc shape from the upstream end to the downstream end so as to swell outward with respect to a plane orthogonal to the cylinder row at its central position.

In FIGS. 1 and 2, 19, 19, . . . indicate cooling water passages 10 on the lower surface of the upper wall 5b of the cylinder head 5.
This is a rib extending vertically toward the main combustion chamber 9, and is used to guide cooling water downward to cool the area around the main combustion chamber 9. In FIG. 1, 20, 20, . . . are bearings protruding from the upper surface of the upper wall 5b of the cylinder head 5, which support a camshaft (not shown) that opens and closes the intake and exhaust valves 15 and 17. It is something to do. Furthermore, in FIGS. 2 and 3, 21, 21,
... is a plug hole for mounting a spark plug (not shown) facing the main combustion chamber 9 of each of the cylinders 2a to 2d;
22, 22, . . . are bolt holes into which head bolts (not shown) for bolting the cylinder head 5 to the cylinder block 1 are inserted.

Therefore, in the above embodiment, the engine cooling water flows through the cooling water passage 3 of the cylinder block 1.
After flowing into the cooling water passage 10 of the cylinder head 5 through the cooling water introduction ports 11, 11a, and 11b that open around each cylinder 2a to 2d, the cooling water passage 10 is passed from the first cylinder 2a side to the fourth cylinder. It flows toward the side 2d and flows out of the engine from the cooling water outlet 23.

At that time, the cooling water outlet 2 of the cylinder head 5
Since the main combustion chamber 9 of the first cylinder 2a located at the end opposite to 3 is arranged to be biased towards the cooling water outlet 23 side, the portion around the main combustion chamber 9 of the first cylinder 2a is , located on the opposite side from the cooling water outlet 23, the cooling water flows into the cooling water passage 10 of the cylinder head 5 from the five cooling water inlets 11a, 11a, 11b, 11b, . In addition to being cooled by the flow of cooling water toward 23, the cooling water outlet 23 of the first cylinder 2a
In the figure located near the side, after flowing into the cooling water passage 10 from the four cooling water inlets 11a, 11a, 11b, 11b, it also encounters the flow of cooling water heading towards the cooling water outlet 23, and both It is now cooled by the flow of cooling water, and its cooling performance is improved.

In addition, nine cooling water inlets 11a, 11a, ..., 11b, 11b, around the first cylinder 2a,
... is divided into two types of diameters, small diameter cooling water inlet 1
Since the flow rate of the cooling water flowing in from 1a is fast, after the cooling water flows in, it flows toward the upper part of the cooling water passage 10 and toward the downstream side. This cooling water makes it possible to secure cooling water for the entire cylinder head 5. On the other hand, since the flow rate of the cooling water flowing in through the large-diameter cooling water inlet 11b is slow, after the cooling water flows in, the cooling water flows toward the lower part of the cooling water passage 10 and toward the downstream side. Since the main combustion chamber 9 is formed in the lower part of the cylinder head 5, the cooling water flowing in the lower part of the cooling water passage 10 passes near the main combustion chamber 9, thereby making the main combustion chamber 9 more effective. can be cooled down. Furthermore, five inlets 11a, 11 located closer to the other end of the cylinder head 5 than the main combustion chamber 9
Among a, 11b, 11b, ..., the large diameter inlet 1
1b, 11b, ... are small diameter introduction ports 11a, 11a
Since it is located closer to the main combustion chamber 9 side in the longitudinal direction of the cylinder head 5,
The cooling water immediately after being introduced from the introduction ports 11b, 11b, . . . will flow around the main combustion chamber 9.
Due to these synergistic effects, the heat load around the main combustion chamber 9 of the first cylinder 2a is suppressed from increasing to an extreme degree compared to other parts, thereby improving the reliability of the engine.

Further, at the other end in the longitudinal direction of the cylinder head 5, five cooling water inlets 11a, 11a, 11 are provided at both corners of the inner wall of the cylinder head 5.
b, 11b, ... are provided, it is possible to keep the overall length of the cylinder head 5 shorter than when the cooling water inlet is provided at the center in the width direction of the cylinder head (on the alignment line of the cylinders 2a to 2d). can.

Furthermore, each intake port 12 of the cylinder head 5
The downstream end opening 12a of the intake port 12 is arranged offset to the side opposite to the center position of the cylinder row.
Due to the offset of the downstream end opening 12a of the engine, the direction of the intake swirl (turbulent flow) generated in each combustion chamber 7 during the intake stroke of the engine, and the direction of curvature of each branch pipe portion 18b of the banana-shaped intake pipe 18. Since they match, the intake swirl is assisted and its strength increases, thereby improving the combustibility of the engine.

In the above embodiment, an example has been described in which the engine is applied to a multi-cylinder engine having a banana-shaped intake pipe 18 in which the upstream end of each branch pipe part 18b is integrally connected to the collecting pipe part 18a. As shown in FIG. 4, the intake ports 12' of each cylinder 2a to 2d,
Branch pipe parts 18'b, 18' connected to 12',...
The present invention can also be applied to a multi-cylinder engine having a tournament-type intake pipe 18' in which a predetermined number of intake pipes b, . It is possible to achieve the following effects.

Further, in the above embodiment, the present invention is applied to a four-cylinder engine, but it goes without saying that the present invention can also be applied to a multi-cylinder engine with three cylinders or five or more cylinders.

(Effects of the invention) As explained above, according to the invention, the main combustion chamber in which the exhaust port opens is formed by the partial recess in the inner wall of the cylinder head, and the remaining part constitutes the main combustion chamber in which the intake port opens. In a multi-cylinder engine configured as a cylinder head, a cooling water outlet is provided at one end of the cylinder head, and a plurality of cooling water inlets of different diameters are provided around the cylinder located at least at the end opposite to the cooling water outlet. The main combustion chamber of the cylinder at the end opposite to the cooling water outlet is shifted toward the cooling water outlet side, and the large-diameter inlet located at the opposite end of the cylinder to the main combustion chamber of the cylinder is connected to a small-diameter inlet. Since it is placed closer to the main combustion chamber than the inlet, there are more opportunities for the cooling water to flow around the main combustion chamber of the cylinder at the end opposite to the cooling water outlet. In addition, the large-diameter cooling water inlet can suppress the flow rate of the cooling water and actively direct the cooling water to the vicinity of the main combustion chamber at the bottom of the cylinder. It is possible to improve the cooling performance of the cylinder head of a multi-cylinder engine having a combustion chamber structure, thereby improving reliability.

[Brief explanation of the drawing]

The drawings illustrate the embodiments of the present invention.
2 is a longitudinal sectional view of the engine, FIG. 2 is a cross sectional view of the cylinder head, FIG. 3 is a bottom view of the same, and FIG. 4 is a view corresponding to FIG. 3 schematically showing a modification. 1...Cylinder block, 2a-2b...Cylinder, 3...Cooling water passage, 4...Piston, 4a
...Top surface, 5, 5'...Cylinder head, 5a,
5'a...Inner wall, 7...Combustion chamber, 8...Recess, 9
...Main combustion chamber, 10...Cooling water passage, 11,11
a, 11b... Cooling water inlet, 12, 12'...
Intake port, 13... Exhaust port, 18, 18'
...Intake pipe, 18a, 18'a...Collecting pipe section, 1
8b, 18'b...Branch pipe section, 23...Cooling water outlet, 24...Squeeze zone.

Claims (1)

[Scope of utility model registration request] The inner wall of the cylinder head, which is a combustion chamber-constituting wall facing the upper surface of the piston, is partially recessed, and the recess constitutes the main combustion chamber.On the other hand, there is a ski cylinder on the longitudinal side of the cylinder head of the main combustion chamber. In a multi-cylinder engine in which zones are formed and an exhaust port is opened in the main combustion chamber and an intake port is opened in the combustion zone, a cooling water outlet is provided at one longitudinal end of the cylinder head of the engine. At least, a plurality of cooling water inlets having different diameters are provided around the cylinder located at the other end of the cylinder head, and the main combustion chamber of the cylinder is biased toward the cooling water outlet side in the longitudinal direction of the cylinder head. The large-diameter cooling water inlet opening on the side opposite to the cooling water outlet with respect to the main combustion chamber is arranged closer to the main combustion chamber in the longitudinal direction of the cylinder head than the small-diameter cooling water inlet. The engine cooling structure is characterized by: