1. The utility model provides an engine cylinder cover, includes vertical type intake duct structure, vertical type intake duct structure includes the tangential air flue of keeping away from cylinder cover air flue air inlet relatively and is close to relatively the spiral air flue of cylinder cover air flue air inlet, a serial communication port, the tangential air flue with a side wall of keeping away from corresponding exhaust valve of spiral air flue all is equipped with to corresponding intake valve center convex tumble flow and generates the arch, the tangential air flue with the intake throat of spiral air flue all is equipped with the eccentric chamfer that the center was arranged to the direction skew of corresponding exhaust valve, tumble flow generates bellied center and keeps away from more than its intake valve center that corresponds cylinder cover air flue air inlet, the line that the bellied center of tumble flow generation and corresponding intake valve center is the protruding direction line of tumble flow, the protruding direction line of tumble flow is the tumble flow direction angle with the contained angle of bent axle direction line, and the corresponding tumble direction angle of the tangential air passage is smaller than that of the spiral air passage.

2. The engine cylinder cover according to claim 1, characterized in that the connecting line of the center of the eccentric chamfer and the center of the corresponding intake valve is an eccentric chamfer direction line, and the eccentric chamfer direction line is coincident with or forms an acute included angle with the connecting line of the centers of the corresponding intake valve and the corresponding exhaust valve.

3. The engine cylinder cover according to claim 2, wherein the direction line of the eccentric chamfer corresponding to the spiral air passage forms an acute included angle with the central connecting line of the corresponding intake and exhaust valves, and the center of the eccentric chamfer corresponding to the spiral air passage is closer to the air inlet of the air passage of the cylinder cover than the center of the corresponding intake valve.

4. The engine cylinder head according to claim 2 or 3, characterized in that an included angle between the tumble protrusion direction line and the eccentric chamfer direction line is a tumble direction fitting angle, and the tumble direction fitting angle corresponding to the tangential air passage is smaller than the tumble direction fitting angle corresponding to the spiral air passage.

5. The engine cylinder head according to claim 4, characterized in that the tangential air passages correspond to a tumble direction fitting angle of 0-20 °, and the spiral air passages correspond to a tumble direction fitting angle of 0-40 °.

6. The engine cylinder cover according to claim 1, characterized in that the connecting lines of the centers of the intake and exhaust valves corresponding to the tangential air passages and the spiral air passages are arranged in parallel with the direction line of the crankshaft or form an acute included angle with the direction line of the crankshaft.

7. The engine head of claim 1, characterized in that the tumble flow generating protrusion is located above the intake valve seat ring, an axial projection of the tumble flow generating protrusion on an upper end surface of the intake valve seat ring is a tumble protrusion projection, the tumble protrusion projection forms a bulging region bulging from an inner side edge of the intake valve seat ring to a center of the intake valve seat ring in a radial direction, and a width of the bulging region in a middle portion of the intake valve seat ring in a circumferential direction is larger than widths of both ends of the bulging region.

8. The engine head of claim 7, characterized in that the raised area is a crescent-shaped area with the concave side disposed toward the center of the intake valve seat ring.

9. A gas engine, characterized in that it comprises an engine head according to any one of claims 1 to 8.

Background

With the development of gas engine technology, more and more engine manufacturers are beginning to design and develop gas engines on the basis of diesel engines. Due to the particularity of the combustion mode of the diesel engine, the engine combustion chamber is required to organize the airflow to generate a sufficient swirl ratio in the process of air intake. However, gas engines do not require excessive swirl, but rather, require more tumble flows that organize the gas flow to create a center axis of rotation perpendicular to the center axis of the liner. That is, for a gas engine, the purpose of optimizing combustion can only be achieved if sufficient tumble flow is effectively generated. Wherein, the vortex refers to the organized rotational flow motion of the gas around the axis of the cylinder sleeve.

The air passage design of the traditional diesel engine enables the included angle between the central connecting line of the two inlet valves and the axis of the crankshaft to be 70-110 degrees, and the two inlet valves are vertically arranged or nearly vertically arranged, so that the air inlet passage arrangement structure is also called a vertical air inlet passage, and the two branch air inlet passages are respectively a tangential air passage and a spiral air passage. The structure makes the air inlet direction consistent with the vortex generating direction, but the air inlet direction is nearly vertical to the generating direction required by the tumble flow, and the structure is beneficial to the generation of the vortex of the gas, and the tumble flow is difficult to generate if necessary.

Therefore, how to facilitate the generation of tumble flow required by a gas engine through structural design on the basis of the existing diesel engine is a technical problem which needs to be solved by the technical personnel in the field at present.

Disclosure of Invention

In view of the above, an object of the present invention is to provide an engine cylinder head, which is used for enabling gas entering the engine cylinder jacket to generate a tumble flow effect required by a gas engine by changing a structure of the cylinder head on the basis of an existing diesel engine. Another object of the present invention is to provide a gas engine comprising the above engine head.

In order to achieve the purpose, the invention provides the following technical scheme:

the invention provides an engine cylinder cover, which comprises a vertical air inlet passage structure, wherein the vertical air inlet passage structure comprises a tangential air passage relatively far away from an air inlet of a cylinder cover air passage and a spiral air passage relatively close to the air inlet of the cylinder cover air passage, the side wall surfaces of the tangential air passage and the spiral air passage far away from corresponding exhaust valves are respectively provided with a tumble generation bulge protruding towards the center of the corresponding intake valve, the air inlet throats of the tangential air passage and the spiral air passage are respectively provided with an eccentric chamfer with the center arranged in a manner of offsetting towards the direction of the corresponding exhaust valve, the center of the tumble generation bulge is far away from the air inlet of the cylinder cover air passage relative to the center of the corresponding intake valve, the connecting line of the center of the tumble generation bulge and the center of the corresponding intake valve is a tumble bulge direction line, and the included angle between the tumble bulge direction, and the corresponding tumble direction angle of the tangential air passage is smaller than that of the spiral air passage.

Preferably, the connecting line of the center of the eccentric chamfer and the center of the corresponding intake valve is an eccentric chamfer direction line, and the eccentric chamfer direction line is superposed with the connecting line of the centers of the corresponding intake valve and the corresponding exhaust valve or forms an acute included angle.

Preferably, the direction line of the eccentric chamfer corresponding to the spiral air passage forms an acute included angle with the central connecting line of the corresponding intake valve and the exhaust valve, and the center of the eccentric chamfer corresponding to the spiral air passage is closer to the air inlet of the air passage of the cylinder cover relative to the center of the corresponding intake valve.

Preferably, the included angle between the tumble convex direction line and the eccentric chamfer direction line is a tumble direction fit angle, and the tumble direction fit angle corresponding to the tangential air passage is smaller than the tumble direction fit angle corresponding to the spiral air passage.

Preferably, the tangential air passage corresponds to a tumble direction fitting angle of 0-20 degrees, and the spiral air passage corresponds to a tumble direction fitting angle of 0-40 degrees.

Preferably, the central connecting lines of the air inlet and outlet valves corresponding to the tangential air passage and the spiral air passage are arranged in parallel with the direction line of the crankshaft or form an acute included angle.

Preferably, the tumble flow generating protrusion is located above the intake valve seat ring, an axial projection of the tumble flow generating protrusion on the upper end surface of the intake valve seat ring is a tumble protrusion projection, the tumble protrusion projection forms a protruding region protruding from the inner side edge of the intake valve seat ring to the center of the intake valve seat ring along the radial direction, and the width of the protruding region in the middle of the protruding region in the circumferential direction of the intake valve seat ring is greater than the widths of the two ends of the protruding region.

Preferably, the convex region is a crescent shaped region with the concave side disposed towards the centre of the inlet valve seat insert.

The invention provides an engine cylinder cover which comprises a vertical air inlet passage structure, wherein the vertical air inlet passage structure comprises a tangential air passage relatively far away from an air inlet of a cylinder cover air passage and a spiral air passage relatively close to the air inlet of the cylinder cover air passage, the side wall surfaces of the tangential air passage and the spiral air passage far away from corresponding exhaust valves are respectively provided with a tumble generation bulge protruding towards the center of a corresponding intake valve, the air inlet throat openings of the tangential air passage and the spiral air passage are respectively provided with an eccentric chamfer with the center arranged in a direction of the corresponding exhaust valve in a deviation way, the center of the tumble generation bulge is far away from the air inlet of the cylinder cover air passage relative to the center of the corresponding intake valve, the connecting line of the center of the tumble generation bulge and the center of the corresponding intake valve is a tumble bulge direction line, the included angle between the tumble bulge direction line and the crankshaft direction line is a tumble direction angle, and the tumble direction angle corresponding to the tangential air passage is smaller than the tumble direction angle corresponding to the spiral air passage.

The working principle of the invention is as follows:

when the engine cylinder inhales, the inlet valve is opened, and the gas in the vertical type air inlet channel structure enters the cylinder from the tangential air channel and the spiral air channel respectively. When the airflow passes through the tumble generation protrusion, since the tumble generation protrusion is located on a side wall surface of the air passage away from the corresponding exhaust valve, most of the airflow moves to one side of the exhaust valve due to the tumble generation protrusion. Then, the air flow is reorganized while flowing through the annular passage formed by the intake valve and the intake valve seat ring together, and when the air flow flows into the cylinder through the gap between the eccentric chamfer and the intake valve, since the center of the eccentric chamfer is arranged offset toward the exhaust valve, the eccentric chamfer causes most of the intake air flow to flow toward the exhaust valve side. After entering the cylinder, the intake airflow of the tangential air passage passes through the area below the exhaust valve and forms large-scale tumble motion under the guidance of the cylinder wall. The relative tangential air flue of spiral air flue is close to cylinder cap air flue air inlet more, and the energy of air current is bigger in its interior air current of admitting air than the opposite side air flue, consequently, the air current in the spiral air flue is influenced by flow inertia more easily, moves to the admission valve below of tangential air flue when just getting into the cylinder easily for the regional difficult tissue formation tumble motion in below of spiral air flue and the exhaust valve that corresponds. According to the invention, the corresponding tumble direction angle of the spiral air passage is designed to be larger than that of the tangential air passage, namely, the guide of the tumble generation bulge to the air flow is more deviated to the spiral air passage and the corresponding lower area of the exhaust valve, so that the inertia influence is further overcome, the intake air flow fully occupies the space in the whole cylinder, and further the tumble is further enhanced. At the end of the compression process, when the piston moves upwards to the position near the top dead center, more turbulence can be formed by compression and crushing of the tumble flow, so that enough turbulent kinetic energy is generated, the combustion speed is accelerated, and the performance of the gas engine is favorably improved.

The invention has the following beneficial effects:

1) the invention is suitable for the gas engine with a vertical air inlet structure, can overcome the influence of the flow inertia of the vertical air inlet and is beneficial to generating large-scale tumble motion in the cylinder;

2) the invention guides the intake airflow for three times, further ensuring the organization and the enhancement of large-scale tumble motion;

3) the invention has small change on the air passage structure and small influence on the flow coefficient of the air passage, and ensures that the air flow has enough air inlet energy.

The invention also provides a gas engine comprising the engine cylinder cover. The derivation process of the beneficial effects generated by the gas engine is substantially similar to the derivation process of the beneficial effects brought by the engine cylinder cover, and therefore, the description is omitted here.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a longitudinal cross-sectional view of an engine head in an embodiment of the present invention;

FIG. 2 is a schematic illustration of the tangential air path and the helical air path directing the intake air flow in an embodiment of the present invention;

FIG. 3 is a schematic illustration of the tumble direction angle in an embodiment of the present invention;

FIG. 4 is a schematic diagram of the tumble direction fitting angle in an embodiment of the present invention;

FIG. 5 is a schematic diagram illustrating the effect of tumble flow generated by intake airflow in an embodiment of the present invention;

FIG. 6 is a graph comparing the airway flow coefficient of the present invention and the prior art;

fig. 7 is a graph comparing the tumble ratio of the present invention solution with the prior art solution.

The meaning of the various reference numerals in figures 1 to 5 is as follows:

1-a first air inlet throat, 2-a second air inlet throat, 3-a total air inlet channel, 4-a cylinder cover air passage air inlet, 5-a first air outlet throat, 6-a second air outlet throat, 7-a crankshaft direction line, 8-a central connecting line of two air inlet valves, 9-a first tumble generating bulge, 10-a second tumble generating bulge, 11-a first eccentric chamfer, 12-a second eccentric chamfer, 13-a first eccentric chamfer direction line, 14-a second eccentric chamfer direction line, 15-a first tumble bulge direction line, 16-a second tumble bulge direction line, 17-a first air inlet valve seat ring, 18-a first air inlet valve central line, 19-a tangential air passage and 20-a spiral air passage.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention provides an engine cylinder cover, which comprises a vertical air inlet passage structure, wherein the vertical air inlet passage structure comprises a tangential air passage 19 relatively far away from an air inlet 4 of a cylinder cover air passage and a spiral air passage 20 relatively close to the air inlet 4 of the cylinder cover air passage, as shown in figure 2, the tail end of a total air inlet passage 3 of the vertical air inlet passage structure is branched into two branch air inlet passages of the tangential air passage 19 and the spiral air passage 20, the side wall surfaces of the tangential air passage 19 and the spiral air passage 20 far away from corresponding exhaust valves are respectively provided with a rolling flow generation bulge protruding towards the center of the corresponding intake valve, air inlet throats of the tangential air passage 19 and the spiral air passage 20 are respectively provided with an eccentric chamfer with the center arranged in a manner of offsetting towards the direction of the corresponding exhaust valves, the center of the rolling flow generation bulge is far away from the air inlet 4 of the air passage of the cylinder cover relative to the center of the corresponding intake valve, and the connecting line of the center of the rolling flow generation bulge and the corresponding intake valve is a rolling flow bulge direction line, the included angle between the direction line of the tumble protrusion and the direction line 7 of the crankshaft is a tumble direction angle, and the tumble direction angle corresponding to the tangential air passage 19 is smaller than the tumble direction angle corresponding to the spiral air passage 20.

Specifically, referring to fig. 1 to 3, the extending direction of the total intake duct 3 of the vertical intake duct structure is the same as the extending direction of the central connecting line 8 of the two intake valves, so that the tangential air duct 19 is farther away from the cylinder head air duct intake port 4 than the spiral air duct 20. The included angle between the connecting line of the centers of the two inlet valves corresponding to the vertical type air inlet channel structure (namely the connecting line 8 of the centers of the two inlet valves in fig. 2) and the crankshaft direction line 7 (namely the projection of the crankshaft axis on the bottom surface of the cylinder cover) is 90 degrees or nearly 90 degrees, and is usually between 70 degrees and 110 degrees. In the traditional vertical air inlet structure without the structure of the rolling flow generation bulge and the eccentric chamfer angle, the intake air flow enters the cylinder from the tangential air passage 19 and the spiral air passage 20 and then easily forms vortex motion in the cylinder, in order to form the rolling flow motion in the cylinder, the invention respectively improves the tangential air passage 19 and the spiral air passage 20, and particularly, the wall surfaces of the two branch air inlets are mainly provided with the rolling flow generation bulge and the bottom holes of the two intake throat openings are provided with the eccentric chamfer angle. As shown in fig. 2, a side wall surface of the tangential air passage 19 away from the corresponding exhaust valve (corresponding to the first exhaust throat 5) is provided with a first tumble flow generating protrusion 9 protruding toward the center of the corresponding intake valve, and as shown in fig. 1, the first tumble flow generating protrusion 9 protrudes toward the corresponding first intake valve center line 18. A first eccentric chamfer 11 is arranged at the bottom hole of the air inlet throat (namely, the first air inlet throat 1 in fig. 2) of the tangential air passage 19, and the center of the first eccentric chamfer 11 is arranged in a manner of offsetting towards the direction of the corresponding first exhaust throat 5 relative to the center of the first air inlet throat 1, so that a ventilation gap with a larger width can be formed at one side facing the first exhaust throat 5 when the corresponding air inlet valve is opened, and the air inlet is conveniently guided towards the direction of the first exhaust throat 5. A second tumble generation protrusion 10 protruding towards the center of the corresponding intake valve is arranged on the side wall surface of the spiral air passage 20 far away from the corresponding exhaust valve (corresponding to the second exhaust throat 6), a second eccentric chamfer 12 is arranged at the bottom hole of the intake throat (namely, the second intake throat 2 in fig. 2) of the spiral air passage 20, and the center of the second eccentric chamfer 12 is arranged in a manner of offsetting towards the direction of the corresponding second exhaust throat 6 relative to the center of the second intake throat 2, so that a ventilation gap with a larger width can be formed on one side towards the second exhaust throat 6 when the corresponding intake valve is opened, and the direction of the intake air flowing towards the second exhaust throat 6 is guided conveniently.

Specifically, the centers of the tumble flow generating protrusions in the two branch air inlet passages are farther away from the cylinder head air passage air inlet 4 than the centers of the corresponding air inlet valves, referring to fig. 2, the center of the first tumble flow generating protrusion 9 is farther away from the cylinder head air passage air inlet 4 than the center of the corresponding air inlet valve (equivalent to the center of the first air inlet throat 1), and the center of the second tumble flow generating protrusion 10 is farther away from the cylinder head air passage air inlet 4 than the center of the corresponding air inlet valve (equivalent to the center of the second air inlet throat 2), so that the first tumble flow generating protrusion 9 and the second tumble flow generating protrusion 10 can guide the intake air flow in the corresponding branch air inlet passage to the corresponding exhaust valve direction, and meanwhile, the first tumble flow generating protrusion 9 can also guide the intake air flow to the direction close to the center of the cylinder, and the second tumble flow generating protrusion 9 can also guide the intake air flow to the direction close to the cylinder head air inlet 4, therefore, the combined action of these two tumble flow generating protrusions makes it possible to move the intake air flow in the direction perpendicular to the port duct 3, thereby facilitating the generation of tumble flow motion in the cylinder. The tumble flow of the intake air flow inside the cylinder is schematically shown with reference to the curved line arrow in fig. 5.

The present invention not only designs characteristics of tumble flow generating protrusions in two branch air inlet channels, but also designs difference characteristics of tumble flow generating protrusions in two branch air inlet channels, specifically, a connecting line between a center of a tumble flow generating protrusion and a center of a corresponding air inlet valve is a tumble flow protrusion direction line, an included angle between a tumble flow protrusion direction line and a crankshaft direction line 7 is a tumble flow direction angle, as shown in fig. 3, a connecting line between a center of a first tumble flow generating protrusion 9 and a center of a corresponding air inlet valve is a first tumble flow protrusion direction line 15, an included angle α 1 between the first tumble flow protrusion direction line 15 and the crankshaft direction line 7 is a first tumble flow direction angle, a connecting line between a center of a second tumble flow generating protrusion 10 and a center of a corresponding air inlet valve is a second tumble flow protrusion direction line 16, an included angle α 2 between the second tumble flow protrusion direction line 16 and the crankshaft direction line 7 is a second tumble flow direction angle, and a first tumble flow direction angle α 1 corresponding to a tangential air passage 19 is smaller than a second tumble flow direction α 2 corresponding to a spiral air passage 20 . The reason why the present invention differentially designs the tumble flow generating protrusion features in the two branch air inlets is that, for the vertical air inlet structure, the intake airflow of the tangential air passage 19 is guided by the first tumble flow generating protrusion 9, the first eccentric chamfer 11 and the cylinder wall to easily form tumble motion, and the rotation direction is also relatively stable, so that the first tumble direction angle α 1 can be designed to be relatively small to improve the flow capacity and ensure the airflow intake energy. In the case of the original spiral air duct 20, the intake air flow is affected by the flow inertia after entering the cylinder, and the intake air flow is far away from the cylinder wall when entering the cylinder, the swirl motion is easily formed without further guiding action and the second inlet throat 2 and the area below the second outlet throat 6 are more organized to form a tumble motion because there is not enough flow compensation, so the invention designs the second tumble direction angle alpha 2 to be larger, so that more air flow can be guided toward the second intake throat 2 and the lower region of the second exhaust throat 6 by the second tumble flow generating protrusion 10, meanwhile, the air flow can be guided to the lower part of the second exhaust throat 6 by virtue of the guiding function of the second eccentric chamfer 12, so that the air flow can fully occupy the space in the whole cylinder, and the tumble strength is further enhanced. This scheme is through the differentiation design, has not only strengthened the tumble strength in the jar, can also avoid reducing the flow coefficient of air flue.

The working principle of the invention is as follows:

when the engine cylinder inhales, the inlet valve is opened, and the gas in the vertical type air inlet channel structure enters the cylinder from the tangential air channel 19 and the spiral air channel 20 respectively. When the airflow passes through the tumble generation protrusion, since the tumble generation protrusion is located on a side wall surface of the air passage away from the corresponding exhaust valve, most of the airflow moves to one side of the exhaust valve due to the tumble generation protrusion. Then, the air flow is reorganized while flowing through the annular passage formed by the intake valve and the intake valve seat ring together, and when the air flow flows into the cylinder through the gap between the eccentric chamfer and the intake valve, since the center of the eccentric chamfer is arranged offset toward the exhaust valve, the eccentric chamfer causes most of the intake air flow to flow toward the exhaust valve side. After entering the cylinder, the intake air flow of the tangential air passage 19 passes through the area below the exhaust valve and forms a large-scale tumble motion under the guidance of the cylinder wall. The spiral air passage 20 is closer to the cylinder cover air passage air inlet 4 relative to the tangential air passage 19, and the energy of the air flow in the spiral air passage 20 is larger than that of the air flow in the tangential air passage 19, so that the air flow in the spiral air passage 20 is more easily influenced by the flow inertia and easily moves below the air inlet valve of the tangential air passage 19 when entering the cylinder, and the spiral air passage 20 and the lower area of the corresponding exhaust valve are difficult to organize to form tumble motion. According to the invention, the tumble direction angle corresponding to the spiral air passage 20 is designed to be larger than that of the tangential air passage 19, namely, the guide of the tumble generation bulge to the air flow is more deviated to the lower area of the spiral air passage 20 and the corresponding exhaust valve, so that the inertia influence is further overcome, the intake air flow fully occupies the space in the whole cylinder purposefully, and further the tumble is further enhanced. At the end of the compression process, when the piston moves upwards to the position near the top dead center, more turbulence can be formed by compression and crushing of the tumble flow, so that enough turbulent kinetic energy is generated, the combustion speed is accelerated, and the performance of the gas engine is favorably improved.

It should be noted that, when the intake airflow flows through the annular gap between the intake valve and the bottom hole of the intake throat, because the center of the eccentric chamfer deviates a distance to the exhaust side relative to the center of the intake throat, one side of the annular gap close to the exhaust throat becomes wider, and more airflows can be guided to the lower area of the exhaust throat, so that the eccentric position of the eccentric chamfer determines the flowing direction of most of the airflows. As shown in fig. 3, a line connecting the center of the first eccentric chamfer 11 and the center of the corresponding intake valve is a first eccentric chamfer direction line 13, and a line connecting the center of the second eccentric chamfer 12 and the center of the corresponding intake valve is a second eccentric chamfer direction line 14.

The invention not only designs the eccentric chamfer characteristics at the two air inlet throats, but also designs the difference of the two eccentric chamfer characteristics, specifically, a second eccentric chamfer direction line 14 corresponding to the spiral air passage 20 forms an acute included angle with a central connecting line of the corresponding air inlet and outlet valves, and the center of a second eccentric chamfer 12 corresponding to the spiral air passage 20 is closer to the air inlet 4 of the cylinder cover air passage relative to the center of the corresponding air inlet valve (equivalent to the center of the second air inlet throat 2). So set up, similar with the purpose of the differentiation design of two above-mentioned tumble generation protruding characteristics for second eccentric chamfer 12 can be with the below guide of air current to second exhaust throat 6, and then more is favorable to the air current fully to occupy whole jar inner space, further strengthens tumble intensity.

Preferably, the included angle between the tumble protrusion direction line and the eccentric chamfer direction line is a tumble direction fitting angle, as shown in fig. 4, the included angle θ 1 between the first tumble protrusion direction line 15 corresponding to the tangential air passage 19 and the first eccentric chamfer direction line 13 is a first tumble direction fitting angle, the included angle θ 2 between the second tumble protrusion direction line 16 corresponding to the spiral air passage 20 and the second eccentric chamfer direction line 14 is a second tumble direction fitting angle, and the relationship between the first tumble direction fitting angle θ 1 and the second tumble direction fitting angle θ 2 is designed as follows: theta 1 is less than theta 2. The purpose of performing differential design on the matching angles of the two tumble directions in the scheme is the same as that of performing differential design on the two tumble direction angles, so the description is omitted here.

Preferably, the tangential air duct 19 corresponds to a first tumble direction fitting angle θ 1 of 0-20 °, and the spiral air duct 20 corresponds to a second tumble direction fitting angle θ 2 of 0-40 °.

Preferably, the central connecting lines of the intake valve and the exhaust valve corresponding to the tangential air passage 19 and the spiral air passage 20 are both arranged in parallel or form an acute angle with the crankshaft direction line 7. And the center connecting line of the intake valve and the exhaust valve is the connecting line of the center of the intake valve and the center of the corresponding exhaust valve. Further preferably, the central connecting lines of the two intake and exhaust valves are arranged in parallel with the crankshaft direction line 7.

It should be noted that, there are many options for the specific structural form of the tumble flow generating protrusion in the present invention, for example, the tumble flow generating protrusion is designed into a protrusion structure with a cross section in the shape of a circular arc, a rectangle or other polygons, specifically, the tumble flow generating protrusion is located above the intake valve seat ring, and as illustrated in fig. 1, in this scheme, the first tumble flow generating protrusion 9 is located above the first intake valve seat ring 17 of the first intake throat 1, the axial projection of the tumble flow generating protrusion on the upper end surface of the intake valve seat ring is a tumble protrusion projection, the tumble protrusion projection forms a protrusion area protruding from the inner side edge of the intake valve seat ring to the center of the intake valve seat ring (i.e. the corresponding intake valve center), the width of the middle of the protrusion area in the circumferential direction of the intake valve seat ring is designed to be greater than the widths of the two ends, wherein one side edge of the tumble flow generating protrusion facing the intake valve center is a characteristic edge of the tumble flow protrusion, the characteristic edge of the tumble protrusion can be designed into a linear edge or a curved edge, as shown in fig. 3 and 4, preferably, the characteristic edge of the tumble protrusion is designed into a circular arc edge, and a protruding area formed by the tumble generation protrusion is a crescent area with a concave side facing the center of the intake valve seat ring.

Through experimental verification, please refer to fig. 6, compared with the original vertical air inlet scheme, because the tumble generating protrusion is additionally arranged in the original air passage structure, the flow coefficient at each valve lift stage is reduced; compared with the existing improved scheme (namely the cylinder cover scheme in the prior art, wherein the air inlet channel is internally designed with fish belly type, lower punch guide surface characteristics, eccentric chamfer characteristics and other characteristics for generating tumble flow), the scheme only designs the tumble flow generating convex characteristics in the air channel and designs the eccentric chamfer characteristics in the bottom hole of the air inlet throat, and equivalently realizes the purpose of organizing tumble flow by using less change characteristics, so the flow coefficient at each valve lift stage is higher than that of the existing improved scheme.

Referring to fig. 7, compared with the original vertical air inlet scheme, the scheme can overcome the influence of flow inertia and enable the intake air flow to purposefully occupy the space in the whole cylinder, so that the tumble ratio can be greatly improved; meanwhile, compared with the existing improved scheme, the scheme has a higher flow coefficient than the existing improved scheme in each valve lift stage, so that the scheme can maintain higher air inlet energy, and the higher air inlet energy is helpful for maintaining tumble flow, so that the scheme can generate a higher tumble ratio than the existing improved scheme in each valve lift stage.

The invention has the following beneficial effects:

1) the invention is suitable for the gas engine with a vertical air inlet structure, can overcome the influence of the flow inertia of the vertical air inlet, changes the direction of air flow entering the cylinder in the air inlet process, and is beneficial to generating large-scale tumble motion in the cylinder;

2) the invention guides the intake airflow for three times, further ensuring the organization and the enhancement of large-scale tumble motion;

3) the invention has small change on the air passage structure, and has small influence on the air passage flow coefficient under the condition of effectively enhancing the tumble strength, thereby ensuring that the air flow has enough air inlet energy.

The invention also provides a gas engine comprising the engine cylinder cover. The derivation process of the beneficial effects generated by the gas engine is substantially similar to the derivation process of the beneficial effects brought by the engine cylinder cover, and therefore, the description is omitted here.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.