Patent Grant
11566559
The present disclosure relates to a precombustion chamber gas engine for combusting an air-fuel mixture in a main combustion chamber (main chamber) by injecting a combustion flame generated in a precombustion chamber (auxiliary chamber) via a plurality of nozzle holes to the main combustion chamber.
A precombustion chamber gas engine is conventionally known as an engine enabling efficient combustion of a lean premixed gas (for instance, Patent Documents 1 and 2). The precombustion chamber gas engine includes a main combustion chamber (main chamber) defined between a piston and a cylinder head and a precombustion chamber disposed adjacent to the main combustion chamber, for instance above the cylinder. The main combustion chamber communicates with the precombustion chamber via a plurality of nozzle holes. By igniting an air-fuel mixture in the precombustion chamber by an ignition device such as an ignition plug, a combustion flame is generated and jetted via each of the nozzle holes disposed at a lower portion of the precombustion chamber, by which a lean premixed gas in the main combustion chamber is combusted. More specifically, a part of a lean premixed gas introduced into the cylinder during the intake stroke of the engine flows into the precombustion chamber via each of the nozzle holes during the compression stroke and is mixed with a precombustion chamber fuel supplied to the precombustion chamber to produce an air-fuel mixture having a concentration suitable for ignition in the precombustion chamber. The air-fuel mixture in this state is ignited by the ignition device, and the combustion flame thereof is injected from the precombustion chamber to the cylinder and serves as a torch to ignite and combust the lean premixed gas in the main combustion chamber. This allows combustion of the lean fuel in the main combustion chamber, thus enabling low fuel consumption. Further, since combustion of the lean mixed gas in the main combustion chamber is performed at a relatively low temperature, generation of NOx is reduced, and low pollution can be achieved.
In such a precombustion chamber gas engine, if the flow of mixed gas from the main chamber to the precombustion chamber via the nozzle holes becomes unstable, an air-fuel mixture having a concentration suitable for ignition is less likely to be formed around an ignition portion of the ignition device (e.g., electrode of ignition plug), which may cause unstable combustion in the precombustion chamber. To solve the above problem, on the basis of findings that the shape of the nozzle hole affects the stability of the flow of mixed gas to be introduced into the precombustion chamber, Patent Document 1 defines the shape of a throat (small-diameter cylinder chamber described later) of the precombustion chamber and the shape of a round-chamfered portion along a rim of a throat-side opening end of the nozzle hole to suppress combustion fluctuation.
Further, as described above, since the air-fuel mixture in the main combustion chamber is ignited by the combustion flame (torch jet) injected from the precombustion chamber to the main combustion chamber via each of the nozzle holes at the combustion stroke, variation of flame propagation of combustion flame of the air-fuel mixture in the main combustion chamber may cause abnormal combustion such as knocking. To solve the above problem, on the basis of findings that the variation of flame propagation speed in the main combustion chamber is caused when the temperature of a cylinder wall surface in an intake region where an intake port is located is lower than the temperature of a cylinder wall surface in an exhaust region where an exhaust port is located, Patent Document 2 discloses that the sum of nozzle hole areas of intake-side nozzle holes disposed in the intake region is made larger than the sum of nozzle hole areas of exhaust-side nozzle holes disposed in the exhaust region. This intends to shorten the time for the flame of an intake-side air-fuel mixture ignited by the torch jet from the intake-side nozzle holes to reach the cylinder wall surface, in order to suppress the occurrence of knocking.
An ignition device (ignition portion) of the precombustion chamber is occasionally difficult to be disposed on the central axis of a cylinder for structure reasons of the precombustion chamber, and thus is disposed away from the central axis of the cylinder in some cases (see
In view of the above, an object of at least one embodiment of the present invention is to provide a precombustion chamber gas engine capable of controlling the variation of flame propagation in a main combustion chamber.
(1) According to at least one embodiment of the present invention, a precombustion chamber gas engine comprises: a main-chamber forming portion forming a main combustion chamber; a precombustion-chamber forming portion forming a precombustion chamber communicating with the main combustion chamber via a plurality of nozzle holes; and an ignition device disposed at an upper portion of an interior of the precombustion chamber and having an ignition portion spaced from a main chamber central axis of the main combustion chamber at a predetermined distance. In a plan view, the precombustion chamber has a near-ignition region in which the ignition portion is disposed and a far-ignition region opposite to the near-ignition region separated by a borderline passing through a precombustion chamber central axis of the precombustion chamber and perpendicular to a straight line passing through the precombustion chamber central axis and the ignition portion. The plurality of nozzle holes includes a specific far nozzle hole which is at least one nozzle hole in the far-ignition region and a specific near nozzle hole which is at least one nozzle hole in the near-ignition region, and a distance between the precombustion chamber central axis and a precombustion-chamber-side opening end of the specific far nozzle hole connected to the precombustion chamber is shorter than a distance between the precombustion chamber central axis and a precombustion-chamber-side opening end of the specific near nozzle hole; or the plurality of nozzle holes includes a specific near nozzle hole which is at least one nozzle hole in the near-ignition region and a specific far nozzle hole which is at least one nozzle hole in the far-ignition region, and a distance between the precombustion chamber central axis and a precombustion-chamber-side opening end of the specific near nozzle hole connected to the precombustion chamber is shorter than a distance between the precombustion chamber central axis and a precombustion-chamber-side opening end of the specific far nozzle hole.
With the above configuration (1), in a plan view of the precombustion chamber of the precombustion chamber gas engine in which the ignition portion of the ignition device (e.g., electrode of ignition plug) is spaced from the central axis of the main combustion chamber (main chamber central axis) at a predetermined distance, the distance between the precombustion chamber central axis and the specific far nozzle hole in a region (ignition-far region) relatively away from the ignition portion is shorter than the distance between the precombustion chamber central axis and the specific near nozzle hole disposed in a region (ignition-near region) relatively close to the ignition portion. Alternatively, the distance between the precombustion chamber central axis and the specific near nozzle hole is shorter than the distance between the precombustion chamber central axis and the specific far nozzle hole. Here, the present inventors have found that the combustion flame produced by ignition by the ignition device reaches a precombustion-chamber-side opening end of a specific near nozzle hole, a portion (bottom center of precombustion chamber) through which the precombustion chamber central axis passes, and a precombustion-chamber-side opening end of a specific far nozzle hole in this order. Further, the present inventors have found that, by forming the precombustion-chamber-side opening end of the specific far nozzle hole adjacent to the bottom center of the precombustion chamber, it is possible to advance the timing at which the combustion flame produced by ignition by the ignition device reaches the precombustion-chamber-side opening end of the specific far nozzle hole. Conversely, the present inventors have found that, by forming the precombustion-chamber-side opening end of the specific near nozzle hole adjacent to the bottom center of the precombustion chamber, it is possible to delay the timing at which the combustion flame reaches the precombustion-chamber-side opening end of the specific near nozzle hole.
Thus, by bringing the precombustion-chamber-side opening end of the specific near nozzle hole or the specific far nozzle hole close to the bottom center of the precombustion chamber, it is possible to reduce the difference between timings at which the combustion flame produced in the precombustion chamber by ignition by the ignition device reaches the respective precombustion-chamber-side opening ends of the specific near nozzle hole and the specific far nozzle hole. Thereby, it is possible to adjust and equalize injection start timing and injection strength of combustion flames (torch jets) injected from respective main-chamber-side opening ends of the specific near nozzle hole and the specific far nozzle hole, and it is possible to suppress the variation of flame propagation in the main combustion chamber. Further, by suppressing the variation of flame propagation in the main combustion chamber, it is possible to suppress knocking caused by delay of flame arrival, and it is possible to improve the engine efficiency.
(2) In some embodiments, in the above configuration (1), the specific near nozzle hole is a nearest nozzle hole having a main-chamber-side opening end connected to the main combustion chamber and closest to the ignition portion among the plurality of nozzle holes in the near-ignition region in a plan view, and the specific far nozzle hole is a farthest nozzle hole having a main-chamber-side opening end farthest from the ignition portion among the plurality of nozzle holes in the far-ignition region in a plan view.
With the above configuration (2), in a plan view of the precombustion chamber, the distance between the precombustion chamber central axis and the precombustion-chamber-side opening end of the nozzle hole (farthest nozzle hole) having the main-chamber-side opening end farthest from the ignition portion is shorter than the distance between the precombustion chamber central axis and the precombustion-chamber-side opening end of the nozzle hole (nearest nozzle hole) having the main-chamber-side opening end closest to the ignition portion. Thereby, it is possible to adjust and advance the timing at which the combustion flame produced by ignition by the ignition device reaches the farthest nozzle hole. Thus, it is possible to bring injection start timing of the farthest nozzle hole close to injection start timing of the nearest nozzle hole which the combustion flame produced by ignition by the ignition device reaches earliest. Consequently, it is possible to suppress the variation of inject start timing at which the flame is injected to the main combustion chamber from each of the nozzle holes, and thus it is possible to efficiently suppress the variation of flame propagation in the main combustion chamber.
(3) In some embodiments, in the above configuration (1) or (2), the distance between the precombustion chamber central axis and the precombustion-chamber-side opening end of the specific far nozzle hole is shorter than an average of distances between the precombustion chamber central axis and respective precombustion-chamber-side opening ends of the plurality of nozzle holes.
With the above configuration (3), by making the distance between the precombustion chamber central axis and the precombustion-chamber-side opening end of the specific far nozzle hole shorter than the average, the distance between the precombustion chamber central axis and the precombustion-chamber-side opening end of the specific far nozzle hole is made shorter than the distance between the precombustion chamber central axis and the precombustion-chamber-side opening end of the specific near nozzle hole.
(4) In some embodiments, in the above configuration (1) or (2), the distance between the precombustion chamber central axis and the precombustion-chamber-side opening end of the specific near nozzle hole is shorter than an average of distances between the precombustion chamber central axis Cs and respective precombustion-chamber-side opening ends of the plurality of nozzle holes.
With the above configuration (4), by making the distance between the precombustion chamber central axis and the precombustion-chamber-side opening end of the specific near nozzle hole shorter than the average, the distance between the precombustion chamber central axis and the precombustion-chamber-side opening end of the specific near nozzle hole is made shorter than the distance between the precombustion chamber central axis and the precombustion-chamber-side opening end of the specific far nozzle hole.
(5) In some embodiments, in any one of the above configurations (1) to (4), an angle of depression of the specific far nozzle hole is equal to an angle of depression of the specific near nozzle hole.
With the above configuration (5), since the angle of depression of the specific far nozzle hole is equal to the angle of depression of the specific near nozzle hole, it is possible to reduce the difference between timings at which the combustion flame produced by ignition by the ignition device reaches the respective precombustion-chamber-side opening ends of the specific near nozzle hole and the specific far nozzle hole, while suppressing the influence on a time required for the combustion flame (torch jet) injected from each of the nozzle holes to propagate to an cylinder wall surface.
(6) According to at least one embodiment of the present invention, a precombustion chamber gas engine comprises: a main-chamber forming portion forming a main combustion chamber; a precombustion-chamber forming portion forming a precombustion chamber communicating with the main combustion chamber via a plurality of nozzle holes; and an ignition device disposed at an upper portion of an interior of the precombustion chamber and having an ignition portion spaced from a main chamber central axis of the main combustion chamber at a predetermined distance. In a plan view, the precombustion chamber has a near-ignition region in which the ignition portion is disposed and a far-ignition region opposite to the near-ignition region separated by a borderline passing through a precombustion chamber central axis of the precombustion chamber and perpendicular to a straight line passing through the precombustion chamber central axis and the ignition portion. The plurality of nozzle holes includes a specific far nozzle hole which is at least one nozzle hole in the far-ignition region and a specific near nozzle hole which is at least one nozzle hole in the near-ignition region, and a nozzle hole length of the specific far nozzle hole is shorter than a nozzle hole length of the specific near nozzle hole.
With the above configuration (6), in a plan view of the precombustion chamber of the precombustion chamber gas engine in which the ignition portion of the ignition device (e.g., electrode of ignition plug) is spaced from the central axis of the main combustion chamber (main chamber central axis) at a predetermined distance, the nozzle hole length of the specific far nozzle hole in a region (ignition-far region) relatively away from the ignition portion in a plan view of the precombustion chamber is shorter than the nozzle hole length of the specific near nozzle hole disposed in a region (ignition-near region) relatively close to the ignition portion. As the nozzle hole length increases, the combustion flame produced by ignition by the ignition device needs time to pass through the nozzle hole. Accordingly, in the precombustion chamber, by setting the nozzle hole length of the specific far nozzle hole which the combustion flame reaches later to be shorter than the nozzle hole length of the specific near nozzle hole which the combustion flame reaches earlier, it is possible to adjust and equalize injection start timing and injection strength of combustion flames (torch jets) injected to the main combustion chamber from the respective main-chamber-side opening ends of the specific far nozzle hole and the specific near nozzle hole, and it is possible to suppress the variation of flame propagation in the main combustion chamber. Further, by suppressing the variation of flame propagation in the main combustion chamber, it is possible to suppress knocking caused by delay of flame arrival, and it is possible to improve the engine efficiency.
(7) In some embodiments, in the above configuration (6), the specific near nozzle hole includes a nearest nozzle hole closest to the ignition portion among the plurality of nozzle holes in the near-ignition region in a plan view, and the specific far nozzle hole includes a farthest nozzle hole farthest from the ignition portion among the plurality of nozzle holes in the far-ignition region in a plan view.
With the above configuration (7), in a plan view of the precombustion chamber, the nozzle hole length of the nozzle hole (farthest nozzle hole) farthest from the ignition portion is shorter than the nozzle hole length of the nozzle hole (nearest nozzle hole) closest to the ignition portion. Thereby, in the precombustion chamber, it is possible to adjust and equalize injection start timing and injection strength of combustion flames (torch jets) injected from the nearest nozzle hole which the combustion flame produced by ignition by the ignition device reaches the earliest and the farthest nozzle hole which the combustion flame reaches the latest, and it is possible to efficiently suppress the variation of flame propagation of the torch jet in the main combustion chamber.
(8) In some embodiments, in the above configuration (6) or (7), the precombustion chamber is formed so as to deviate the precombustion chamber central axis from the main chamber central axis so that a distance between the main chamber central axis and a precombustion-chamber-side opening end of the specific far nozzle hole is longer than a distance between the main chamber central axis and a precombustion-chamber-side opening end of the specific near nozzle hole in the precombustion-chamber forming portion.
With the above configuration (8), for instance, by forming the precombustion chamber to be offset toward the specific far nozzle hole so as to deviate the main chamber central axis from the precombustion chamber central axis in the precombustion-chamber forming portion, the wall thickness of the precombustion chamber formed by the precombustion-chamber forming portion becomes thinner in the vicinity of the specific far nozzle hole than in the vicinity of the specific near nozzle hole. Thus, the nozzle hole length of the specific far nozzle hole is made shorter than the nozzle hole length of the specific near nozzle hole.
(9) According to at least one embodiment of the present invention, a precombustion chamber gas engine comprises: a main-chamber forming portion forming a main combustion chamber; a precombustion-chamber forming portion forming a precombustion chamber communicating with the main combustion chamber via a plurality of nozzle holes; and an ignition device disposed at an upper portion of an interior of the precombustion chamber and having an ignition portion spaced from a main chamber central axis of the main combustion chamber at a predetermined distance. In a plan view, the precombustion chamber has a near-ignition region in which the ignition portion is disposed and a far-ignition region opposite to the near-ignition region separated by a borderline passing through the main chamber central axis and perpendicular to a straight line passing through a precombustion chamber central axis of the precombustion chamber and the ignition portion. The plurality of nozzle holes includes a specific far nozzle hole which is at least one nozzle hole in the ignition-far region, and the specific far nozzle hole has a precombustion-chamber-side opening end having a diameter decreasing with a distance from a connection position with the precombustion chamber.
With the above configuration (9), in a plan view of the precombustion chamber of the precombustion chamber gas engine in which the ignition portion of the ignition device (e.g., electrode of ignition plug) is spaced from the central axis of the main combustion chamber (main chamber central axis) at a predetermined distance, the precombustion-chamber-side opening end of the specific far nozzle hole in a region (ignition-far region) relatively away from the ignition portion in a plan view of the precombustion chamber has a shape (bell-mouth shape) having a diameter decreasing with a distance from the connection position with the precombustion chamber. That is, the precombustion-chamber-side opening end of the specific far nozzle hole is shaped so as to decrease inlet pressure loss with respect to the combustion flame produced by ignition by the ignition device, whereby deceleration of the combustion flame flowing into the precombustion-chamber-side opening end of the specific far nozzle hole is suppressed.
Thereby, it is possible to increase the flow velocity of the combustion flame (torch jet) injected to the main combustion chamber from the specific far nozzle hole, and thus it is possible to adjust and equalize the flow velocity of the torch jet from the specific far nozzle hole and the flow velocity of the torch jet injected from the specific near nozzle hole to the main combustion chamber. Consequently, it is possible to suppress the variation of flame propagation in the main combustion chamber. Further, by suppressing the variation of flame propagation in the main combustion chamber, it is possible to suppress knocking caused by delay of flame arrival, and it is possible to improve the engine efficiency.
(10) In some embodiments, in the above configuration (9), the specific far nozzle hole is a farthest nozzle hole farthest from the ignition portion among the plurality of nozzle holes in the far-ignition region in a plan view.
With the above configuration (10), in a plan view of the precombustion chamber, the precombustion-chamber-side opening end of the nozzle hole (farthest nozzle hole) farthest from the ignition portion has a bell-mouth shape. Thereby, in the precombustion chamber, it is possible to adjust and equalize injection start timing and injection strength of combustion flames (torch jets) injected from the nearest nozzle hole which the combustion flame produced by ignition by the ignition device reaches the earliest and the farthest nozzle hole which the combustion flame reaches the latest, and it is possible to efficiently suppress the variation of flame propagation in the main combustion chamber.
(11) In some embodiments, in any one of the above configurations (1) to (7), (9), and (10), the main chamber central axis coincides with the precombustion chamber central axis.
With the above configuration (11), in the precombustion chamber gas engine in which the precombustion chamber is provided so that the main chamber central axis of the main combustion chamber coincides with the precombustion chamber central axis of the precombustion chamber, and the ignition portion of the ignition device is spaced from the central axis of the main combustion chamber (main chamber central axis) at a predetermined distance, it is possible to suppress the variation of flame propagation in the main combustion chamber.
(12) In some embodiments, in the above configuration (11), the precombustion chamber includes: a small-diameter-cylinder forming portion forming a small-diameter cylinder chamber having a predetermined inner diameter and connected to the plurality of nozzle holes; and a large-diameter-cylinder forming portion forming a large-diameter cylinder chamber which has an inner diameter larger than that of the small-diameter cylinder chamber and in which the ignition portion of the ignition device is disposed, and the main chamber central axis coincides with a precombustion chamber central axis of the small-diameter cylinder chamber.
With the above configuration (12), in the precombustion chamber gas engine in which the precombustion chamber is provided so that the main chamber central axis of the main combustion chamber coincides with the precombustion chamber central axis of the small-diameter cylinder chamber of the precombustion chamber, and the ignition portion of the ignition device is spaced from the central axis of the main combustion chamber (main chamber central axis) at a predetermined distance, it is possible to suppress the variation of flame propagation in the main combustion chamber.
(13) In some embodiments, in any one of the above configurations (1) to (12), the predetermined distance is larger than 10% of a maximum value of an inner diameter of the precombustion chamber.
With the above configuration (13), in the precombustion chamber gas engine in which the ignition portion of the ignition device is spaced from the central axis of the main combustion chamber (main chamber central axis) at a predetermined distance, it is possible to suppress the variation of flame propagation in the main combustion chamber.
According to at least one embodiment of the present invention, there is provided a precombustion chamber gas engine capable of controlling the variation of flame propagation in a main combustion chamber.
Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It is intended, however, that unless particularly identified, dimensions, materials, shapes, relative positions and the like of components described in the embodiments shall be interpreted as illustrative only and not intended to limit the scope of the present invention.
For instance, an expression of relative or absolute arrangement such as “in a direction”, “along a direction”, “parallel”, “orthogonal”, “centered”, “concentric” and “coaxial” shall not be construed as indicating only the arrangement in a strict literal sense, but also includes a state where the arrangement is relatively displaced by a tolerance, or by an angle or a distance whereby it is possible to achieve the same function.
For instance, an expression of an equal state such as “same” “equal” and “uniform” shall not be construed as indicating only the state in which the feature is strictly equal, but also includes a state in which there is a tolerance or a difference that can still achieve the same function.
Further, for instance, an expression of a shape such as a rectangular shape or a cylindrical shape shall not be construed as only the geometrically strict shape, but also includes a shape with unevenness or chamfered corners within the range in which the same effect can be achieved.
On the other hand, an expression such as “comprise”, “include”, “have”, “contain” and “constitute” are not intended to be exclusive of other components.
As shown in
More specifically, in the embodiments shown in
Further, the ignition device 5 has an ignition portion 51 capable of igniting an air-fuel mixture, and is disposed on an engine so that the ignition portion 51 is spaced from the central axis of the main combustion chamber 2r (hereinafter, main chamber central axis Cm) at a predetermined distance D. For instance, the ignition device 5 may be an ignition plug of a spark ignition type. In this case, the ignition portion 51 is a portion including an electrode which generates a spark. The predetermined distance D may be larger than 10% of a maximum value of the inner diameter of the main combustion chamber 2r. As described later, in a case where the precombustion chamber 3r includes a small-diameter cylinder chamber 31r and a large-diameter cylinder chamber 33r, the ignition portion 51 may be disposed in the large-diameter cylinder chamber 33r (constant diameter cylinder portion 33c), and the predetermined distance D may be a maximum value of the inner diameter of the large-diameter cylinder chamber 33r.
On the other hand, the precombustion-chamber forming portion 3 includes a plurality of nozzle holes 4 connecting the precombustion chamber 3r formed in the precombustion-chamber forming portion 3 to the outside. The main combustion chamber 2r communicates with the precombustion chamber 3r via the plurality of nozzle holes 4. More specifically, each of the nozzle holes 4 has a main-chamber-side opening end 41m connected to the main combustion chamber 2r on one side and a precombustion-chamber-side opening end 41s connected to the precombustion chamber 3r on the other side. The precombustion-chamber-side opening end 41s may be connected to the precombustion chamber 3r above a bottom portion 35 including a portion furthest from the top portion where the ignition portion 51 is disposed (see
In the embodiments shown in
However, the present invention is not limited to the present embodiments. In some embodiments, the precombustion chamber 3r may have other shape, for instance, a cylindrical shape having a constant inner diameter.
Further, in some embodiments, as shown in
The precombustion chamber gas engine 1 having the above configuration opens the intake valve 17 and closes the exhaust valve 18 when the piston 14 moves downward at the intake stroke, for instance. As the intake valve 17 opens, a lean premixed gas containing a mixture of a fuel gas and air is introduced into the cylinder 13 through the intake port 15 connected to the intake valve 17. As the precombustion-chamber-fuel-gas supply valve 61 opens, a precombustion chamber fuel gas is introduced into the precombustion chamber 3r. Furthermore, at the compression stroke, the precombustion-chamber-fuel-gas supply valve 61 closes when the piston 14 moves upward. Further, the lean premixed gas introduced into the cylinder 13 through the intake port 15 is compressed as the piston 14 moves upward, and a part of the lean premixed gas is introduced into the precombustion chamber 3r through each of the nozzle holes 4 of the precombustion chamber 3r. The lean premixed gas introduced from the main combustion chamber 2r to the precombustion chamber 3r is mixed with the precombustion chamber fuel gas to produce an air-fuel mixture having a concentration suitable for ignition in the precombustion chamber 3r. The air-fuel mixture in the precombustion chamber 3r is ignited by the ignition device 5 at a predetermined timing when the piston 14 arrives at the vicinity of the compression top dead center, and the air-fuel mixture in the precombustion chamber 3r is thus combusted. A combustion flame caused by this combustion is injected into the cylinder 13 through each of the nozzle holes and ignites the lean premixed gas in the cylinder 13, which leads to combustion of the lean premixed gas in the main combustion chamber 2r.
At this time, the present inventors have found through numerical analysis and the like that in the precombustion chamber gas engine 1 according to the present invention, since the ignition portion 51 of the ignition device 5 is spaced from the main chamber central axis Cm at a predetermined distance D, the timing at which the combustion flame produced by ignition of the air-fuel mixture in the precombustion chamber by the ignition portion 51 reaches each of the nozzle holes 4 varies. Further, they found that, if the timing of arrival of the combustion flame produced by ignition by the ignition device varies among the nozzle holes 4 and if, for instance, the nozzle holes 4 have the same shape, variation occurs in injection start timing at which combustion flame (hereinafter, referred to as torch jet as appropriate) is injected to the main combustion chamber 2r from each of the nozzle holes 4 through a corresponding main-chamber-side opening end 41m and in injection strength thereof. If injection start timing and injection strength of torch jet from each of the nozzle holes 4 vary, flame propagation in the main combustion chamber 2r also varies. The variation of flame propagation in the main combustion chamber 2r causes unburned gas to remain in a region where flame propagation delays, which may cause knocking and degrade thermal efficiency and output power of the precombustion chamber gas engine 1.
In view of this, the present inventors have arrived at suppressing the variation of flame propagation in the main combustion chamber 2r by changing the shape of at least one nozzle hole 4 of the plurality of nozzle holes 4 so as to suppress the variation of injection start timing and injection strength of torch jet injected to the main combustion chamber 2r from each of the nozzle holes 4.
The shape of the plurality of nozzle holes 4 in some embodiments of the present invention will now be described.
In the present invention, in a plan view as shown in
First, embodiments relating to connection position between the precombustion-chamber-side opening end 41s of the nozzle hole 4 and the precombustion chamber 3r will be described with reference to
In some embodiments, as shown in
Alternatively, in some embodiments, as shown in
In the embodiments shown in
Here, the present inventors have found that the combustion flame produced by ignition by the ignition device 5 reaches the precombustion-chamber-side opening end 41s of the specific near nozzle hole 42, a portion (center of bottom portion 35 of precombustion chamber 3r) through which the precombustion chamber central axis Cs passes, and the precombustion-chamber-side opening end 41s of the specific far nozzle hole 43 in this order. Further, the present inventors have found that, by forming the precombustion-chamber-side opening end 41s of the specific far nozzle hole 43 adjacent to the center of the bottom portion of the precombustion chamber 3r, it is possible to advance the timing at which the combustion flame produced by ignition by the ignition device 5 reaches the precombustion-chamber-side opening end 41s of the specific far nozzle hole 43. Conversely, the present inventors have found that, by forming the precombustion-chamber-side opening end 41s of the specific near nozzle hole 42 adjacent to the center of the bottom portion of the precombustion chamber 3r, it is possible to delay the timing at which the combustion flame produced by ignition by the ignition device 5 reaches the precombustion-chamber-side opening end 41s of the specific near nozzle hole 42.
Thus, by bringing the precombustion-chamber-side opening end 41s of the specific near nozzle hole 42 or the specific far nozzle hole 43 close to the center of the bottom portion of the precombustion chamber 3r, it is possible to reduce the difference between timings at which the combustion flame produced by ignition by the ignition device 5 reaches the respective precombustion-chamber-side opening ends 41s of the specific near nozzle hole 42 and the specific far nozzle hole 43. Thereby, it is possible to adjust and equalize injection start timing and injection strength of combustion flames (torch jets) injected from respective main-chamber-side opening ends 41m of the specific near nozzle hole 42 and the specific far nozzle hole 43, and it is possible to suppress the variation of flame propagation in the main combustion chamber 2r. Further, by suppressing the variation of flame propagation in the main combustion chamber 2r, it is possible to suppress knocking caused by delay of flame arrival, and it is possible to improve the engine efficiency.
More specifically, in some embodiments, as shown in
Further, in the embodiment shown in
However, the present invention is not limited to the present embodiments. The specific near nozzle hole 42 may be one or more, a plurality of nozzle holes 4, and the specific far nozzle hole 43 may be one or more, a plurality of nozzle holes 4. In a case where the specific far nozzle hole 43 includes a plurality of nozzle holes 4, they may be arranged so that a nozzle hole 4 with a later arrival timing has a precombustion-chamber-side opening end 41s closer to the precombustion chamber central axis Cs, in accordance with the timing of arrival of the combustion flame produced in the precombustion chamber 3r. Moreover, in a case where the specific near nozzle hole 42 includes a plurality of nozzle holes 4, they may be arranged so that a nozzle hole 4 with an earlier arrival timing has a precombustion-chamber-side opening end 41s closer to the precombustion chamber central axis Cs, in accordance with the timing of arrival of the combustion flame produced in the precombustion chamber 3r. Further, the nearest nozzle hole 42s may not be the specific near nozzle hole 42. Similarly, the farthest nozzle hole 43s may not be the specific far nozzle hole 43.
With the above configuration, in a plan view of the precombustion chamber 3r, the distance rf between the precombustion chamber central axis Cs and the precombustion-chamber-side opening end 41s of the nozzle hole (farthest nozzle hole 43s) having the main-chamber-side opening end 41m farthest from the ignition portion 51 is shorter than the distance rn between the precombustion chamber central axis Cs and the precombustion-chamber-side opening end 41s of the nozzle hole (nearest nozzle hole 42s) having the main-chamber-side opening end 41m closest to the ignition portion 51. Thereby, it is possible to adjust and advance the timing at which the combustion flame produced by ignition by the ignition device 5 reaches the farthest nozzle hole 43s. Thus, it is possible to bring injection start timing of the farthest nozzle hole 43s close to injection start timing of the nearest nozzle hole 42s which the combustion flame reaches earliest. Consequently, it is possible to suppress the variation of inject start timing at which the flame is injected to the main combustion chamber 2r from each of the nozzle holes 4, and thus it is possible to efficiently suppress the variation of flame propagation in the main combustion chamber 2r.
Further, in some embodiments, as shown in
With the above configuration, by making the distance rf between the precombustion chamber central axis Cs and the precombustion-chamber-side opening end 41s of the specific far nozzle hole 43 shorter than the average, the distance rf between the precombustion chamber central axis Cs and the precombustion-chamber-side opening end 41s of the specific far nozzle hole 43 is made shorter than the distance rn between the precombustion chamber central axis Cs and the precombustion-chamber-side opening end 41s of the specific near nozzle hole 42.
In some embodiments, as shown in
With the above configuration, by making the distance rn between the precombustion chamber central axis Cs and the precombustion-chamber-side opening end 41s of the specific near nozzle hole 42 shorter than the average, the distance rn between the precombustion chamber central axis Cs and the precombustion-chamber-side opening end 41s of the specific near nozzle hole 42 is made shorter than the distance rf between the precombustion chamber central axis Cs and the precombustion-chamber-side opening end 41s of the specific far nozzle hole 43 (rn<rf).
Further, in the embodiments as shown in
Second, embodiments relating to shape of the precombustion chamber 3r formed in the precombustion-chamber forming portion 3 (precombustion-chamber cap 19) will be described with reference to
In some embodiments, as shown in
More specifically, in some embodiments, as shown in
Further, in the embodiment shown in
On the other hand, in the embodiment shown in
Accordingly, as shown in
In the embodiments shown in
With the above configuration, for instance, by forming the precombustion chamber 3r to be offset toward the specific far nozzle hole 43 so as to deviate the precombustion chamber central axis Cs from the main chamber central axis Cm in the precombustion-chamber forming portion 3, the wall thickness of the precombustion chamber 3r formed by the precombustion-chamber forming portion 3 becomes thinner in the vicinity of the specific far nozzle hole 43 than in the vicinity of the specific near nozzle hole 42. Thus, the nozzle hole length Lf of the specific far nozzle hole 43 is made shorter than the nozzle hole length Ln of the specific near nozzle hole 42.
Third, embodiments relating to shape of the precombustion-chamber-side opening end 41s of the nozzle hole 4 will be described with reference to
In some embodiments, as shown in
Thereby, it is possible to increase the flow velocity of the torch jet injected to the main combustion chamber 2r from the specific far nozzle hole 43, and thus it is possible to adjust and equalize the flow velocity of the torch jet from the specific far nozzle hole 43 and the flow velocity of the torch jet injected from the specific near nozzle hole 42 to the main combustion chamber 2r. Consequently, it is possible to suppress the variation of flame propagation in the main combustion chamber 2r. Further, by suppressing the variation of flame propagation in the main combustion chamber 2r, it is possible to suppress knocking caused by delay of flame arrival, and it is possible to improve the engine efficiency.
Further, in some embodiments, the specific far nozzle hole 43 may be the farthest nozzle hole 43s. That is, in this case, the precombustion-chamber-side opening end 41s of the farthest nozzle hole 43s has a bell-mouth shape. Thereby, in the precombustion chamber 3r, it is possible to adjust and equalize injection start timing and injection strength of torch jets injected from the nearest nozzle hole 42s which the combustion flame produced by ignition by the ignition device 5 reaches the earliest and the farthest nozzle hole 43s which the combustion flame reaches the latest, and it is possible to efficiently suppress the variation of flame propagation in the main combustion chamber 2r.
The present invention is not limited to the embodiments described above, but includes modifications to the embodiments described above, and embodiments composed of combinations of those embodiments.
For instance, in some embodiments, the precombustion-chamber-side opening end 41s of the specific far nozzle hole 43 in the embodiments relating to connection position between the precombustion-chamber-side opening end 41s of the nozzle hole 4 and the precombustion chamber 3r as shown in
Further, although in the embodiments shown in
| Number | Date | Country | Kind |
|---|---|---|---|
| 2016-238753 | Dec 2016 | JP | national |
This application is a Divisional Application of co-pending application Ser. No. 16/466,553, filed Jun. 4, 2019, which is a National Phase under 35 U.S.C. § 371 of International Application No. PCT/JP2017/043202, filed Nov. 30, 2017, which claims the benefit under 35 U.S.C. § 119(a) to Patent Application No. 2016-238753, filed in Japan on Dec. 8, 2016, all of which are hereby expressly incorporated by reference into the present application.
| Number | Name | Date | Kind |
|---|---|---|---|
| 4066045 | Suzuki | Jan 1978 | A |
| 4098232 | Gleiter | Jul 1978 | A |
| 4124000 | Genslak | Nov 1978 | A |
| 4250852 | Abulkasim ogly Kerimov | Feb 1981 | A |
| 4369746 | Thring | Jan 1983 | A |
| 4719884 | Shinno | Jan 1988 | A |
| 5024193 | Graze, Jr. | Jun 1991 | A |
| 5566654 | Masuda | Oct 1996 | A |
| 5769050 | Ito | Jun 1998 | A |
| 9200559 | Ishii et al. | Dec 2015 | B2 |
| 10077708 | Furukawa | Sep 2018 | B2 |
| 10961899 | Suzuki | Mar 2021 | B2 |
| 20040060536 | Funaki et al. | Apr 2004 | A1 |
| 20060219210 | Bailey et al. | Oct 2006 | A1 |
| 20080168963 | Gagliano | Jul 2008 | A1 |
| 20110146618 | LaPointe et al. | Jun 2011 | A1 |
| 20120103302 | Attard | May 2012 | A1 |
| 20130000598 | Tokuoka et al. | Jan 2013 | A1 |
| 20140060479 | Tozzi | Mar 2014 | A1 |
| 20150184578 | Oda et al. | Jul 2015 | A1 |
| 20160003117 | Cook | Jan 2016 | A1 |
| 20160230646 | Kim | Aug 2016 | A1 |
| 20160252010 | Villeneuve et al. | Sep 2016 | A1 |
| 20170138251 | Watanabe et al. | May 2017 | A1 |
| 20170145899 | Singh | May 2017 | A1 |
| 20170167359 | Maier | Jun 2017 | A1 |
| 20170306917 | Kim | Oct 2017 | A1 |
| 20170314456 | Blaxill et al. | Nov 2017 | A1 |
| 20190323416 | Nomura et al. | Oct 2019 | A1 |
| 20190368410 | Takemoto | Oct 2019 | A1 |
| 20200036166 | Kuhnert | Jan 2020 | A1 |
| 20200080467 | Nomura | Mar 2020 | A1 |
| 20200165961 | Hamada et al. | May 2020 | A1 |
| 20200332705 | Han et al. | Oct 2020 | A1 |
| 20200392892 | Fiveland et al. | Dec 2020 | A1 |
| Number | Date | Country |
|---|---|---|
| 101858245 | Oct 2010 | CN |
| 2 520 780 | Nov 2012 | EP |
| 2927458 | Oct 2015 | EP |
| 2001-3753 | Jan 2001 | JP |
| 2001003753 | Jan 2001 | JP |
| 2001-227344 | Aug 2001 | JP |
| 4975092 | Jul 2012 | JP |
| 2012-149655 | Aug 2012 | JP |
| 2014-62484 | Apr 2014 | JP |
| 2014-129788 | Jul 2014 | JP |
| 2016-3608 | Jan 2016 | JP |
| Entry |
|---|
| Decision of Refusal dated Jun. 23, 2020 issued in counterpart Japanese application No. 2016-238753. |
| Extended European Search Report for European Application No. 17877701.7, dated Jan. 17, 2020. |
| International Preliminary Report on Patentability and Written Opinion of the International Searching Authority, dated Jun. 20, 2019, for International Application No. PCT/JP2017/043202, with an English Translation of the Written Opinion. |
| International Search Report, dated Feb. 20, 2018, for International Application No. PCT/JP2017/043202. |
| Office Action dated Apr. 14, 2020 issued in counterpart Japanese Application No. 2016-238753 with an English Translation. |
| Office Action dated Sep. 17, 2020 issued in counterpart European Patent Application No. 17877701.7. |
| Partial Supplementary European Search Report, dated Oct. 21, 2019, for European Application No. 17877701.7. |
| Number | Date | Country | |
|---|---|---|---|
| 20210404373 A1 | Dec 2021 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 16466553 | US | |
| Child | 17472040 | US |
