JP2015117581A - Gas engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas engine capable of improving ignitability to an air-fuel mixture while reducing pressure loss of intake air and exhaust air, by largely securing cross-sectional areas of an exhaust port and an intake port.SOLUTION: A gas engine includes a cylinder head 30, a pre-chamber cap projecting into a main combustion chamber from a center of the cylinder head 30, having a pre-chamber inside, and supplying flame generated in the pre-chamber into the main combustion chamber, a gas introduction passage disposed in the cylinder head 30, extended along a central axis C to hold the pre-chamber cap, and introducing a pre-chamber gas into the pre-chamber, and a pre-chamber holder 42 provided with an ignition plug igniting the pre-chamber gas to generate flame. The pre-chamber holder 42 is provided with a cutout portion 50 so that it retracts toward a radial inner side of the central axis C, on a part corresponding to at least one of ports 34, 35 on an outer peripheral face of the pre-chamber holder 42, in a cross section orthogonal to the central axis C.

Description

  The present invention relates to a gas engine having a sub chamber.

  As one type of engine, a gas engine that operates by burning a gaseous fuel (fuel gas) such as natural gas or city gas is known. Since this gas engine can obtain high efficiency and high output, it is widely used mainly for engines for power generation for ordinary use and emergency use, engines for construction machinery, ships, railways, and the like.

  As a gas engine, a cylinder head provided with a sub chamber for ignition is known. In this gas engine, an air-fuel mixture obtained by mixing fuel gas and air is supplied to a main combustion chamber in a cylinder head. Further, fuel gas is also supplied to the sub chamber. When the piston is close to the compression top dead center in the main combustion chamber and the fuel gas in the main combustion chamber is compressed, the fuel gas supplied into the sub chamber is ignited by the spark of the spark plug provided in the sub chamber. The As a result, a flame is generated from the sub chamber and is ejected from a base provided in the sub chamber into the main combustion chamber. Then, the air-fuel mixture in the main combustion chamber is ignited by this flame, and the combustion operation of the gas engine is performed (see, for example, Patent Document 1).

  Here, the sub chamber includes a base for supplying a flame into the main combustion chamber, and a sub chamber holder for holding the base and forming a sub chamber in which fuel gas is supplied. The sub chamber holder includes a sub chamber, a gas introduction path for introducing fuel gas into the sub chamber, and a plug holding hole for holding the spark plug so that the tip portion faces the sub chamber to ignite the fuel gas in the sub chamber. Is provided.

  In the cylinder head, on the roof surface forming the top surface of the main combustion chamber, an intake port for supplying an air-fuel mixture into the main combustion chamber and an exhaust port for discharging an exhaust gas combusting the air-fuel mixture are formed. The sub chamber holder is disposed on the roof surface of the cylinder head so as not to interfere with the intake port or the exhaust port, for example, at the center of the roof surface. The sub chamber holder has a circular outer periphery.

JP 2010-150983 A

However, the gas engine has the following problems.
The diameter of the cylinder and the piston is determined from the displacement of the gas engine, and the area of the roof surface (top surface) of the cylinder head is limited accordingly. In the cylinder head, it is necessary to arrange a sub chamber holder in addition to the intake port and the exhaust port on the roof surface whose area is limited as described above.

  For gas engines, high output and high efficiency are always desired. For this reason, in order to increase the intake efficiency and exhaust efficiency of the fuel gas in the main combustion chamber, it is desired to increase the cross-sectional area of the exhaust port and the intake port. However, since the sub chamber holder is also arranged on the roof surface, there are restrictions on the arrangement and size of the exhaust port and the intake port.

In particular, in the case of a gas engine that performs lean combustion, since the amount of air in the air-fuel mixture is large, it is difficult to ignite with only a spark plug. Therefore, by providing a cross-sectional area of the gas introduction path for supplying fuel to the sub chamber, the fuel ratio in the air-fuel mixture for generating a flame in the sub chamber may be increased.
In this case, a check valve for preventing the backflow of combustion gas is required in the gas introduction path, and the outer diameter of the sub chamber holder is increased. Therefore, when trying to avoid interference with the exhaust port or the intake port, the exhaust port or The cross-sectional area of the intake port is restricted.

  The present invention has been made in view of the above circumstances, and is a gas capable of enhancing the ignitability of an air-fuel mixture while ensuring a large cross-sectional area of an exhaust port and an intake port to reduce pressure loss of intake and exhaust. The purpose is to provide an engine.

In order to solve the above problems, the following configuration is adopted.
The present invention includes a cylinder head in which a plurality of intake and exhaust ports that open toward the main combustion chamber are formed at intervals in the circumferential direction of the central axis, and projects from the cylinder head into the main combustion chamber. A sub-chamber base having a sub-chamber inside and supplying a flame generated in the sub-chamber to the main combustion chamber; and a sub-chamber base provided in the cylinder head and extending along the central axis. A sub-chamber holder provided with a base holding part for holding a gas, a gas introduction path for introducing a sub-chamber gas into the sub-chamber, and a plug holding part for holding a spark plug for igniting the sub-chamber gas to generate a flame; The sub chamber holder recedes inward in the radial direction of the central axis at a portion corresponding to at least one of the ports on the outer peripheral surface of the sub chamber holder in a cross section orthogonal to the central axis. Do Wherein the cormorants cutout portion is formed.

  According to such a gas engine, the area occupied by the sub chamber holder in the cylinder head can be reduced while securing the cross-sectional area of the gas introduction path. Thereby, the cross-sectional area of an exhaust port or an intake port can be earned.

  Furthermore, in the gas engine according to the present invention, a plurality of the cutout portions are provided in a circumferential direction of the outer peripheral surface of the sub chamber holder in the gas engine, and the gas introduction path is arranged on the sub chamber holder on the side where the gas introduction path is disposed. The cutout portion on the side opposite to the side where the gas introduction path is disposed is larger in size than the cutout portion so as to recede toward the radially inner side of the central axis. May be.

  According to such a gas engine, the area occupied by the sub chamber holder in the cylinder head can be further reduced.

  Furthermore, in the gas engine according to the present invention, in the gas engine, the sub chamber holder may be formed such that a cross section perpendicular to the central axis has a polygonal shape including the notch.

  According to such a gas engine, it is possible to easily manufacture a sub chamber holder with a small area in the cylinder head.

  Furthermore, in the gas engine according to the present invention, in the gas engine, a plurality of intake and exhaust ports that open toward the main combustion chamber are formed at intervals in the circumferential direction of the central axis; The cylinder head protrudes from the cylinder head into the main combustion chamber, has a sub chamber inside, and a sub chamber base for supplying a flame generated in the sub chamber to the main combustion chamber, and is provided in the cylinder head. A base holding part that extends along the central axis and holds the sub-chamber base, a gas introduction path for introducing the sub-chamber gas into the sub-chamber, and a spark plug that ignites the sub-chamber gas to generate a flame are held. A sub-chamber holder provided with a plug holding portion, wherein the sub-chamber holder is formed with a large-diameter portion and a small-diameter portion in a circumferential direction around the central axis in a cross section perpendicular to the central axis. Before A small-diameter portion is formed at a portion corresponding to at least one of the ports on the outer peripheral surface of the sub chamber holder, and the large-diameter portion is formed between two ports adjacent to each other in the circumferential direction. It can also be characterized.

  According to such a gas engine, the area occupied by the sub chamber holder in the cylinder head can be reduced while securing the cross-sectional area of the gas introduction path. Thereby, the cross-sectional area of an exhaust port or an intake port can be earned.

  According to the gas engine of the present invention, it is possible to increase the ignitability of the air-fuel mixture while ensuring a large cross-sectional area of the exhaust port and the intake port to reduce the pressure loss of the intake and exhaust.

It is sectional drawing in alignment with the cylinder central axis which shows the structure of the cylinder head periphery of the gas engine which concerns on embodiment of this invention. It is sectional drawing which follows the cylinder central axis which shows the structure around the subchamber of the said gas engine. It is sectional drawing orthogonal to the central axis of the sub chamber holder of the said gas engine. It is sectional drawing orthogonal to the central axis of a subchamber holder which shows the modification of the subchamber holder of the gas engine which concerns on embodiment of this invention. It is sectional drawing orthogonal to the central axis of a subchamber holder which shows the other modification of the subchamber holder of the gas engine which concerns on embodiment of this invention. It is a perspective view which shows the modification of the subchamber holder of the gas engine which concerns on embodiment of this invention.

Hereinafter, a gas engine according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view along a cylinder central axis showing a configuration around a cylinder head of a gas engine according to this embodiment.
As shown in FIG. 1, the gas engine 10 is a sub chamber type gas engine, and includes at least a cylinder block 20, a cylinder head 30, and a sub chamber member 40. The gas engine 10 in this embodiment is a stationary gas engine used for power generation facilities and the like.

  A cylindrical cylinder 21 is formed in the cylinder block 20. A piston 22 is accommodated in the cylinder 21 so as to be capable of linear reciprocation along the central axis C of the cylinder 21. The piston 22 is connected via a connecting rod 23 to a crankshaft 24 housed in a crankcase (not shown). Both ends of the connecting rod 23 are rotatably connected to the piston 22 and the crankshaft 24 via pins 25 and 26, respectively. Accordingly, when the piston 22 linearly moves in the direction along the central axis C in the cylinder 21, the movement of the piston 22 is converted into the rotational movement of the crankshaft 24 by the connecting rod 23.

The cylinder head 30 is connected to an end surface 20 a where the cylinder 21 is opened in the cylinder block 20. Accordingly, the cylinder head 30 has a lid shape that closes the opening of the cylinder 21.
On the surface facing the cylinder block 20 side of the cylinder head 30, a flat surface, a hemispherical surface, or a curved surface surface that is perpendicular to the central axis C of the cylinder 21 is formed in a region facing the cylinder 21. ing.
A main combustion chamber 33 is defined by the cylinder block 20, the cylinder head 30 and the piston 22.

  The cylinder head 30 is formed with an intake port (port) 34 and an exhaust port (port) 35. One end 34 a of the intake port 34 and one end 35 a of the exhaust port 35 are disposed so as to open to the roof surface 31 and face the main combustion chamber 33. In this embodiment, two intake ports 34 and two exhaust ports 35 are formed.

  The intake port 34 and the exhaust port 35 are arranged concentrically with a space in the circumferential direction with respect to the central axis C of the cylinder 21. The two intake ports 34 are arranged adjacent to each other in the circumferential direction of the cylinder 21. Similarly, the two exhaust ports 35 are also arranged adjacent to each other in the circumferential direction of the cylinder 21.

  The intake port 34 has an end (not shown) opposite to the main combustion chamber 33 connected to a mixed gas supply source (not shown). The intake port 34 is supplied with a mixed gas of air and combustion gas from a mixed gas supply source. The intake port 34 is provided with an intake valve 36 at an end 34a on the main combustion chamber 33 side. By moving the intake valve 36 from the closed position to the open position by a valve drive mechanism (not shown), the mixed gas supplied from the mixed gas supply source is supplied from the intake port 34 to the main combustion chamber 33.

  The exhaust port 35 has an end (not shown) opposite to the main combustion chamber 33 connected to an exhaust gas flow path (not shown). The exhaust port 35 is provided with an exhaust valve 37 at an end portion 35a on the main combustion chamber 33 side. By displacing the exhaust valve 37 from the closed position to the open position by a valve drive mechanism (not shown), the exhaust gas of the mixed gas used for combustion in the main combustion chamber 33 passes through the exhaust port 35 from the main combustion chamber 33, It is discharged outside through the exhaust gas flow path.

FIG. 2 is a cross-sectional view along the cylinder central axis showing the configuration around the sub chamber of the gas engine according to this embodiment. FIG. 3 is a cross-sectional view orthogonal to the central axis of the sub chamber holder according to this embodiment.
As shown in FIGS. 1 and 2, the cylinder head 30 is provided with a sub chamber member 40 that forms a sub chamber 41 to which a sub chamber gas is supplied. The sub chamber member 40 is provided so as to be located on the center of the roof surface 31, that is, on an extension line of the center axis C of the cylinder 21. The sub chamber member 40 is arranged so that the central axis thereof overlaps the extension line of the central axis C of the cylinder 21. That is, as shown in FIG. 3, the sub chamber member 40 is positioned at the center of the intake port 34 and the exhaust port 35 that are spaced apart in the circumferential direction around the central axis C of the cylinder 21. Is provided.

As shown in FIG. 2, the sub chamber member 40 includes a sub chamber holder 42 and a sub chamber base 43.
The sub chamber holder 42 is provided in the cylinder head 30. The central axis of the sub chamber holder 42 is provided on an extension line of the central axis C of the cylinder 21. The sub chamber holder 42 is provided adjacent to the gas introduction passage 44 for introducing a sub chamber gas into the sub chamber 41 from the outside, and ignites the sub chamber gas in the sub chamber 41 to flame. A plug holding hole (plug holding portion) 46 for holding the spark plug 45 that generates the cap and a base holding portion 47 for holding the sub chamber base 43 are formed.

  The sub chamber cap 43 is provided so as to protrude into the main combustion chamber 33 from the center of the roof surface 31 of the cylinder head 30. The sub chamber base 43 is formed in a hollow shape, and the internal space thereof is the sub chamber 41. The sub-chamber base 43 is formed with a plurality of ejection holes 43 a for ejecting the flame generated in the sub-chamber 41 into the main combustion chamber 33. The flame is generated by igniting the sub chamber gas in the sub chamber 41 with the spark plug 45.

  The gas introduction path 44 supplies fuel gas (sub chamber gas) to the sub chamber 41 from the outside. A check valve 49 is provided in the gas introduction path 44. The fuel gas is ejected from the gas introduction passage 44 into the sub chamber 41 through the check valve 49.

  The spark plug 45 ignites and burns fuel gas by spark discharge. A tip 45 a of the spark plug 45 protrudes into the sub chamber 41. The spark plug 45 sparks at the tip 45a to ignite and burn the fuel gas supplied from the gas introduction path 44 into the sub chamber 41, thereby generating a flame. The flame generated by this ignition is ejected from the ejection hole 43 a of the sub chamber base 43 into the main combustion chamber 33. By this flame, the mixed gas supplied into the main combustion chamber 33 through the intake port 34 (see FIG. 1) is burned. Then, the piston 22 linearly moves along the central axis C in the cylinder 21 and the gas engine 10 is driven.

  As shown in FIG. 3, the sub chamber holder 42 includes a plurality of notches 50. These notches 50 are formed in portions corresponding to at least one of the intake port 34 and the exhaust port 35 in the sub chamber holder 42 in a cross section orthogonal to the central axis C of the cylinder head 30. The notch 50 is formed so as to recede inward in the radial direction with the central axis C of the sub chamber holder 42 as the center.

  In this embodiment, two intake ports 34 and two exhaust ports 35 are formed, for a total of four, and a total of four linear notches 50 are formed on the outer peripheral surface corresponding to each port in the sub chamber holder 42. Is formed. Further, the sub chamber holder 42 has a linear portion that connects between the notch 50 on the intake port 34 side and the notch 50 on the exhaust port 35 side in a cross section perpendicular to the central axis C of the cylinder head 30. 53 is formed. In addition, corner portions 54 are formed between the notch portions 50 adjacent to each other and between the notch portion 50 and the linear portion 53. That is, the sub chamber holder 42 in this embodiment has a hexagonal cross section perpendicular to the central axis C of the cylinder head 30.

The cross-sectional shape of the sub chamber holder 42 can also be grasped as follows.
That is, the sub chamber holder 42 includes a large diameter portion 51 having a relatively long distance from the central axis C and a central axis C in the circumferential direction around the central axis C in a cross section orthogonal to the central axis C of the cylinder head 30. And a small-diameter portion 52 having a relatively short distance. The small diameter portion 52 corresponding to the notch portion 50 is formed in a portion facing at least one of the intake port 34 and the exhaust port 35, and the large diameter portion 51 corresponding to the corner portion 54 is adjacent to each other. 34, 34 and the exhaust ports 35, 35.

  Therefore, according to the gas engine of the above-described embodiment, the cross-sectional area of the gas introduction passage 44 is ensured to be large by forming the notch portion 50 as compared with the case where the sub chamber holder 42 has a circular cross section. Thus, the space occupied by the sub chamber holder 42 in the cylinder head 30 can be reduced while improving the ignitability. By reducing the cross-sectional area of the sub chamber holder 42, the areas of the intake port 34 and the exhaust port 35 can be increased correspondingly, and the pressure loss of the intake and exhaust can be reduced. As a result, the gas engine 10 can be downsized.

(Other embodiments)
It should be noted that the gas engine according to the present invention is not limited to the above-described embodiment, and includes those in which various modifications are made to the above-described embodiment without departing from the gist of the present invention. That is, the specific shapes, configurations, and the like given in the embodiment are merely examples, and can be changed as appropriate. Various modifications are conceivable within the technical scope.
For example, the notch 50 may be provided at a position corresponding to at least one port among the plurality of ports, and the shapes of the notch 50 and the small diameter portion 52 are not linear but may be arcuate. good.
Moreover, in the said embodiment, although the subchamber holder 42 made hexagonal shape (polygonal shape) the cross-sectional shape orthogonal to the central axis C of the cylinder head 30, it is not restricted to this. For example, as shown in FIG. 4 as a modification, the sub chamber holder 42 may have a quadrangular cross section. Also in this case, the sub chamber holder 42 is directed radially inward to a portion of the sub chamber holder 42 corresponding to at least one of the intake port 34 and the exhaust port 35 in a cross section orthogonal to the central axis C of the cylinder head 30. A notch 50 is formed so as to retreat. The sub chamber holder 42 has a large diameter portion 51 and a small diameter portion 52 in the circumferential direction around the central axis C in a cross section orthogonal to the central axis C of the cylinder head 30. A small diameter portion 52 as the notch portion 50 is formed in a portion facing at least one of the intake port 34 and the exhaust port 35, and the large diameter portion 51 is adjacent to the intake ports 34 and 34 and the exhaust ports 35 and 35. It is formed so that it may be located between. Further, the polygonal shape described above is not limited to a straight line or a circular arc (for example, a star polygon), and may be formed by appropriately combining straight lines and circular arcs. good.

  Further, the sub chamber holder 42 may have an elliptical cross-sectional shape perpendicular to the central axis C of the cylinder head 30. However, the sub-chamber holder 42 is more advantageous in terms of manufacturability if it is provided with the linear notch 50 than the elliptical cross section.

  As another modified example, as shown in FIGS. 5 and 6, the cutout portion 50 </ b> A located on the opposite side to the position where the gas introduction path 44 inside the sub chamber holder 42 is disposed is the gas introduction path 44. As compared with the cutout portion 50B on the side where the is disposed, the dimension of retreating inward in the radial direction may be formed larger. Thereby, the cross-sectional area of the sub chamber holder 42 can be reduced while ensuring the flow passage area of the gas introduction passage 44.

Further, in the sub chamber holder 42, the spark plug 45 is disposed such that the center axis of the spark plug 45 is arranged on an extension line of the center axis C of the cylinder head 30 or in the vicinity of the center axis C of the cylinder head 30. It is preferable. This is to prevent the combustion in the sub chamber 41 from being biased.
Further, the gas introduction path 44 is formed in the vicinity of the ignition plug 45 arranged in this manner. Thus, for example, as shown by a dotted line in FIG. 5, when the circular sub chamber holder 42 is used, an extra portion is formed on the spark plug 45 side, but a large notch portion is formed on the spark plug 45 side. By forming 50A large, the area of the intake port 34 and the exhaust port 35 can be increased more efficiently.

Here, the range in which the cutout portion 50 is provided is a position S where the cylinder head 30 and the sub chamber holder 42 are sealed by the O-ring, with the lower limit being the fitting portion J for fitting the sub chamber holder 42 to the sub chamber base 43. The upper limit is preferable (range indicated by A in FIG. 6).
This is because the sub-chamber base 43 that forms the sub-chamber 41 is preferably formed on an axial object so that there is no bias in combustion, so it is better not to provide the notch 50. Further, in order to seal the sub chamber holder 42 and the cylinder head 30 with the O-ring at the position S, it is preferable that the mounting portion of the O-ring has a circular cross section. In addition, the portion where the O-ring on the upper side of the sub chamber holder 42 is attached does not interfere with the intake port 34 and the exhaust port 35, so there is no need to provide the notch 50.

  Further, the gas engine of the above-described embodiment has been described by taking a stationary gas engine used for power generation facilities as an example, but is not limited to a stationary gas engine.

DESCRIPTION OF SYMBOLS 10 Gas engine 20 Cylinder block 21 Cylinder 30 Cylinder head 33 Main combustion chamber 34 Intake port (port)
35 Exhaust port (port)
40 Subchamber member 41 Subchamber 42 Subchamber holder 43 Subchamber cap 43a Ejection hole 44 Gas introduction path 45 Spark plug 46 Plug holding hole (plug holding portion)
47 Base holding part 50, 50A, 50B Notch part 51 Large diameter part 52 Small diameter part 53 Linear part 54 Corner part

Claims (4)

A cylinder head in which a plurality of ports for intake and exhaust opening toward the main combustion chamber are formed at intervals in the circumferential direction of the central axis;
A sub chamber base that protrudes from the cylinder head into the main combustion chamber, has a sub chamber therein, and supplies a flame generated in the sub chamber to the main combustion chamber;
A base holding portion that is provided in the cylinder head and extends along the central axis and holds the sub chamber base, a gas introduction path for introducing the sub chamber gas into the sub chamber, and the sub chamber gas is ignited. A sub chamber holder provided with a plug holding portion for holding a spark plug for generating a flame,
The sub-chamber holder is notched so as to recede inward in the radial direction of the central axis at a portion corresponding to at least one of the ports on the outer peripheral surface of the sub-chamber holder in a cross section perpendicular to the central axis. A gas engine in which a portion is formed.   A plurality of the notch portions are provided in the circumferential direction of the outer peripheral surface of the sub chamber holder, and the gas introduction path is disposed more than the notch portion on the side where the gas introduction path is disposed in the sub chamber holder. 2. The gas engine according to claim 1, wherein the cutout portion on the opposite side to the side is formed to have a larger size for retreating inward in the radial direction of the central axis.   3. The gas engine according to claim 1, wherein the sub chamber holder has a cross section orthogonal to the central axis formed in a polygonal shape including the notch. 4. A cylinder head in which a plurality of ports for intake and exhaust opening toward the main combustion chamber are formed at intervals in the circumferential direction of the central axis;
A sub chamber base that protrudes from the cylinder head into the main combustion chamber, has a sub chamber therein, and supplies a flame generated in the sub chamber to the main combustion chamber;
A base holding portion that is provided in the cylinder head and extends along the central axis and holds the sub chamber base, a gas introduction path for introducing the sub chamber gas into the sub chamber, and the sub chamber gas is ignited. A sub chamber holder provided with a plug holding portion for holding a spark plug for generating a flame,
The sub chamber holder is formed with a large diameter portion and a small diameter portion in a circumferential direction centering on the central axis in a cross section orthogonal to the central axis, and the small diameter portion is formed on the outer peripheral surface of the sub chamber holder. A gas engine formed in a portion corresponding to at least one of the ports, wherein the large-diameter portion is formed between two ports adjacent to each other in the circumferential direction.

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