Engine air inlet channel adopting machining technology and having low flow resistance characteristic

Abstract

The invention discloses an engine air inlet channel adopting a machining process and having a low flow resistance characteristic. The specific structure of the engine air inlet channel is that the engine air inlet channel is divided into five parts from an inlet to an outlet. The ratio of the diameter of the outlet to the diameter of the inlet of the air inlet channel ranges from 1.0 to 1.1. The height of the valve seat ring determines the length of the outlet of the air inlet channel, and the included angle between the axis of the inlet of the air inlet channel and the bottom plane of the cylinder cover ranges from 12 degrees to 20 degrees. The included angle between the axis of the valve boss and the bottom plane of the cylinder cover ranges from 70 degrees to 80 degrees, and the optimal tumble ratio is obtained by adjusting the included angle between the axis of the valve boss and the bottom plane of the cylinder cover. The arc radius of the large arc section of the air inlet channel is determined according to the diameter of the air inlet channel outlet. The lower end point of the small linear section is the vertex of the valve seat ring; the upper end point of the small linear section is an intersection point with the wall surface of the inlet section channel of the air inlet channel, and the specific position of the intersection point is determined according to the slope of the small linear section, the deviation of the inner profile tolerance and dimensional tolerance of the air channel caused by the casting process is eliminated, the consistency of the circulation section is ensured, the flow resistance is reduced, and the circulation performance is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of internal combustion engine structures, and particularly relates to an engine intake port with low flow resistance characteristics and a processing method thereof. Background Art

[0002] At present, the application of internal combustion engines consumes a large amount of petroleum resources. Energy conservation and emission reduction are of great significance for reducing petroleum consumption and greenhouse gas emissions, reducing dependence on foreign petroleum, and protecting the environment. From the perspective of energy utilization, reducing the pressure loss of the engine intake port can reduce fuel consumption and improve fuel utilization rate, thereby saving non-renewable resources such as petroleum. If the pressure loss problem of the traditional engine intake port is optimized, the operating cost of the engine can be significantly reduced. In addition to enhancing environmental benefits, it also means higher economic benefits for enterprises.

[0003] One end of the engine intake port is connected to the intake manifold; the other end is connected to the combustion chamber, and the intake is controlled by the intake valve. Reducing the pressure loss of the engine intake port is crucial for improving the performance and efficiency of the engine. Excessive pressure loss in the intake port will relatively reduce the intake air volume, and usually be accompanied by energy loss, thus affecting the combustion efficiency and power output of the engine. Reducing the pressure loss can significantly improve the combustion efficiency and the thermal efficiency of the engine. Improper design of the intake port may lead to flow separation and generation of shock waves. These phenomena will increase the pressure loss and airflow disturbance to generate noise, and may even cause engine surge. Therefore, it is of great significance to optimize the design of the intake port.

[0004] Most of the intake ports of traditional engines are obtained through casting processes. Using casting processes often results in deviations in the internal surface profile and dimensional tolerances of the air passages, making the fluid flow performance lower than the design target. In addition, the cast air passages mostly have a spatial curved surface structure. Due to casting deviations, it is difficult to ensure the consistency of the flow cross-section, thereby increasing the flow resistance. Using mechanical processing methods can better solve this problem, but the core technology of mechanical processing lies in how to meet the intake air volume and airflow movement intensity required for in-cylinder combustion of the engine.

[0005] Accordingly, the present invention proposes an engine intake port that adopts a machining process and has low flow resistance characteristics, so as to reduce the pressure loss of the engine intake port, increase the intake air volume of the engine, and thus improve the overall performance, efficiency, and stability of the engine. Summary of the Invention

[0006] The object of the present invention is to provide an engine intake port that adopts a machining process and has low flow resistance characteristics.

[0007] To solve the above problems, the technical solution of the present invention is as follows: An engine intake passage adopting a machining process and having a low flow resistance characteristic, the structure of which is: The engine intake passage includes an inlet section, a valve boss, a large arc section, a small straight section, and an outlet section in appearance. The outlet section of the intake passage is connected to the combustion chamber of the cylinder head, and the ratio of the outlet diameter to the inlet diameter of the intake passage is between 1.0 and 1.1. The included angle between the central axis of the intake passage inlet and the bottom plane of the cylinder head ranges from 12° to 20°, and the outlet section is coaxial with the valve boss. The included angle between the central axis of the valve boss and the bottom plane of the cylinder head ranges from 70° to 80°, and the optimal tumble ratio is obtained by adjusting the included angle between the central axis of the valve boss and the bottom plane of the cylinder head. The radian radius of the large arc section of the intake passage is determined by the outlet diameter of the intake passage. The lower end point of the small straight section is the vertex of the valve seat ring, and the upper end point of the small straight section intersects with the passage wall surface of the intake passage inlet section. The specific position of this intersection point is determined by the slope of the small straight section. The arc length of the large arc section starts from the end point of the intake passage inlet section and ends at the vertex of the intake passage outlet section. Therefore, the length of the small straight section corresponds to the arc length range of the large arc section. The length of the outlet section of the intake passage is determined by the height of the valve seat ring, and the length of the outlet section of the intake passage is 2 - 5 mm larger than the height of the valve seat ring.

[0008] The processing method of the engine intake passage adopting a machining process and having a low flow resistance characteristic is as follows: The large arc section is processed by two processes using different rotation axes to form an intersection line. Since the same arc is used for rotational machining, the projection of its intersection line is a straight line AB, where the left end point A is located on the side close to the small straight section; the right end point B is located on the large arc section. Make a straight line perpendicular to the projection line segment AB at point C on the outlet end face of the intake passage, and mark the intersection point as F. Make a perpendicular line at the 1 / 2 position of the line segment FA and mark it as G; make a perpendicular line at the 1 / 2 position of the projection line segment AB of the intersection line and mark it as H. The center line I of G and H is the axis of the small straight section, and the included angle between this axis and the bottom plane of the cylinder head is the slope of the small straight section. Thus, the specific position of the intersection point of the small straight section and the passage wall surface of the intake passage inlet section can be determined.

[0009] Through the design and adjustment of parameters such as the inlet diameter, outlet diameter, outlet section length, included angle between the inlet axis and the bottom plane of the cylinder head, included angle between the valve boss axis and the bottom plane of the cylinder head, inner arc radius of the intake passage, and valve boss diameter of the engine intake passage, the present invention innovatively reflects the improvement of the engine combustion efficiency and energy utilization rate. Among them, the determination of the position of the small straight section in the intake passage is described in detail, which is very effective for reducing the frictional pressure loss of the engine intake passage and increasing the intake air volume.

[0010] The features and beneficial effects of the present invention are as follows: By manufacturing the engine intake duct through machining, it can better solve the deviations in the inner surface profile and dimensional tolerances caused by the traditional casting process, so that the actual fluid flow performance of the engine intake duct is closer to the designed fluid flow performance compared with the use of the traditional casting process. In addition, traditional cast intake ducts mostly have complex spatial curved surface structures, and it is difficult to ensure the consistency of the flow cross-section due to casting deviations, thus increasing the flow resistance. However, by using the machined engine intake duct of the present invention, this problem can be better solved, enabling the flow cross-sectional area inside the intake duct to have better consistency, thereby reducing the pressure loss of the engine intake duct, increasing the engine intake air volume and the intensity of air flow movement, and thus improving the overall performance, efficiency and stability of the engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 FIG. is a schematic diagram of the external structure of the engine intake duct of the present invention.

[0012] Figure 2 FIG. is a structural parameter diagram of the engine intake duct of the present invention.

[0013] Figure 3 FIG. is a processing principle and method diagram of the inlet section and the large arc section channel of the engine intake duct.

[0014] Figure 4 FIG. is a processing principle and method diagram of the large arc section and the outlet section channel of the engine intake duct.

[0015] Figure 5 FIG. is a processing principle and method diagram of the small straight section curved surface of the engine intake duct.

[0016] Figure 6 FIG. is a processing principle and method diagram of the intake boss of the intake duct in the present invention.

[0017] Figure 7 FIG. is a schematic diagram of the method principle for determining the position of the small straight section in the present invention.

[0018] Figure 8 FIG. is a sectional structure diagram of the engine intake duct of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] To more clearly understand the technical solution of the present invention, the structure of the present invention will be more completely described below in conjunction with the accompanying drawings and specific embodiments. The given embodiments are only one of the embodiments of the present invention rather than all. Based on this embodiment, all other implementations obtained by those skilled in the art without creative efforts fall within the scope of protection of this application.

[0020] An engine intake port that adopts a machining process and has the characteristic of low flow resistance. Its specific structure is as follows: The engine intake port includes five parts in appearance, namely an inlet section 1, a valve boss 2, a large arc section 3-1, a small straight section 3-2, and an outlet section 4. The outlet section of the intake port is connected to the combustion chamber of the cylinder head. The ratio of the outlet diameter D2 of the intake port to the inlet diameter D1 is between 1.0 and 1.1. The included angle C1 between the central axis of the intake port inlet and the bottom plane of the cylinder head ranges from 12° to 20°; the outlet section is coaxial with the valve boss, and the included angle C2 between the central axis of the valve boss and the bottom plane of the cylinder head ranges from 70° to 80°. The best tumble ratio is obtained by adjusting the included angle between the central axis of the valve boss and the bottom plane of the cylinder head. The radian radius R of the large arc section of the intake port is determined by the outlet diameter of the intake port. The lower end point of the small straight section is the vertex of the valve seat 9, and the upper end point of the small straight section is the intersection point with the channel wall surface of the intake port inlet section. The specific position of this intersection point is determined by the slope of the small straight section. The arc length of the large arc section starts from the end point of the intake port inlet section and ends at the vertex of the intake port outlet section. Therefore, the length of the small straight section corresponds to the arc length range of the large arc section. The length of the outlet section of the intake port is determined by the height of the valve seat, and the length L of the outlet section of the intake port is 2-5 mm larger than the height h of the valve seat.

[0021] The center of the circle of the arc of the large arc section is located above the vertex of the outlet section of the intake port; the end point of the large arc section is connected to the outlet section of the intake port. The cross-sectional diameter of the intake port corresponding to the end point position of the large arc section is equal to the diameter of the outlet section of the intake port, but the ratio of the diameter at the end face of the outlet section to the diameter at the inlet end face of the intake port is between 1.0 and 1.1.

[0022] The processing method of an engine intake port that adopts a machining process and has the characteristic of low flow resistance is as follows: The large arc section is processed by two processes with different rotation axes to form an intersection line. Since the same arc is used for rotational machining, the projection of its intersection line (in the direction of Figure 7) is a straight line AB. The left end point A is located on the side close to the small straight section (that is, point A is not in the inlet / outlet section and there is a small distance from the inlet / outlet section. For easy observation, Figure 7 this distance in the figure is magnified); the right end point B is located on the large arc section (it can be the midpoint, but if the angles C1 and C2 change, point B is no longer the midpoint). Draw a straight line perpendicular to the projection line segment AB at point C on the outlet end face of the intake port, and the intersection point is denoted as F. Draw a perpendicular line at the 1 / 2 position of the line segment FA and denote it as G; draw a perpendicular line at the 1 / 2 position of the projection line segment AB and denote it as H. The center line I of G and H is the axis of the small straight section, and the included angle between this axis and the bottom plane of the cylinder head is the slope of the small straight section. From this, the specific position of the intersection point of the small straight section and the channel wall surface of the intake port inlet section can be determined (such as Figure 7 ).

[0023] The position of the lower endpoint of the small straight line segment is easily determined, which is the vertex at the upper part of the valve seat ring. However, there can be many intersection points (i.e., the upper endpoints of the small straight line segment) between the small straight line segment and the passage wall surface of the inlet passage. Which specific position it intersects at depends on the slope of this small straight line segment. Therefore, the specific position of the intersection point between the small straight line segment and the passage wall surface can be determined by the above method.

[0024] The center of the arc of the large arc segment is located at the upper vertex of the outlet section (straight cylinder section) of the inlet passage; the radius of the arc of the large arc segment of the inlet passage is determined by the outlet diameter of the inlet passage, and the radius is equal to the diameter of the outlet section of the inlet passage. One endpoint of the arc is located on the axis of the valve boss; the other endpoint is located at the endpoint of the outlet section of the inlet passage. This endpoint is not the endpoint where the outlet of the inlet passage is connected to the combustion chamber of the cylinder head (such as Figure 2 ).

[0025] The curved surfaces of the inlet section, large arc segment, and outlet section inside the inlet passage are machined by a forming milling cutter 5. The milling cutter enters from the upper end face of the inlet section and the lower end face of the outlet section of the inlet passage along the central axis of the inlet section and the central axis of the outlet section respectively (such as Figure 3 , Figure 4 ).

[0026] The curved surface of the small straight line segment inside the inlet passage is machined by a T-shaped milling cutter 6 (such as Figure 5 ). At this time, the milling cutter cuts along the axis of the small straight line segment. Since this axis is not the central axis of the inlet passage, a part of the curved surface machined by the forming milling cutter near the large arc segment (inner wall) is retained (this part of the curved surface is deliberately left to ensure fluidity).

[0027] The axis of rotation of the milling cutter and the axis of revolution do not coincide. The axis of rotation refers to the rotation of the tool around itself for cutting, and the axis of revolution refers to the rotation of the tool along the central axis of the intake passage to perform rotary cutting on the cross-section. Select the type of milling cutter according to the characteristics of the inner wall of the intake passage and adjust the position of the axis of rotation. Position the two cutting axes through the cylinder head. To avoid damaging the inner surface of the intake passage, when the milling cutter enters and exits, it remains on the side close to the inlet section of the intake passage.

[0028] The diameter d of the valve boss is determined by the size of the valve guide. The valve boss corresponding to the valve guide hole is machined after casting. A straight shank drill 8 is used to machine a through hole along the axis of the valve boss (such as Figure 6 ). The valve seat ring part is also obtained by milling.

[0029] Considering the influence of the valve 11 in the intake port on the flow cross-sectional area of the intake port, the diameter of the intake port outlet should be slightly larger than that of the intake port inlet. On the premise of ensuring that the flow cross-sectional area of the intake port remains unchanged, the diameter of the intake port outlet is obtained by multiplying the diameter of the intake port inlet by the corresponding proportionality coefficient λ. The value of the intake port inlet diameter D1 is 35 mm, the valve boss diameter d is 12 mm, and the proportionality coefficient λ is selected as 1.02. The diameter of the intake port outlet section, i.e., D2 = D1×λ = 35.7 mm.

[0030] The height h of the valve seat ring is 6 mm, and the machining allowance is taken as 3 mm. Therefore, the length L of the intake port outlet section is taken as 9 mm, and the length of the intake port inlet section is 45 mm.

[0031] The included angle C1 between the central axis of the intake port inlet and the bottom plane of the cylinder head is taken as 16°; the included angle C2 between the central axis of the valve boss and the bottom plane of the cylinder head is taken as 74°. The radius R of the large arc line is also equal to the diameter D2 of the intake port outlet, which is 35.7 mm.

[0032] The upper end surface of the valve boss is connected to the valve guide 10. The lower surface of the intake port outlet section is flush with the lower surface of the valve seat ring. The valve passes through the valve guide and contacts the valve seat ring, occupying a part of the volume of the intake port. The valve, valve guide, valve seat ring and the wall surface of the intake port together constitute the flow boundary of the intake port. The upper side boundary of the central section of the intake port is smooth and continuous. There is no sharp transition between the lower side inlet section and the outlet section, and the change is gentle (as Figure 8 ).

[0033] In this embodiment, the flow cross-sectional area at the inlet of the intake passage is 962 mm 2 , the flow cross-sectional area at the intersection line of the large arc segments is 965 mm 2 , and the flow cross-sectional area at the outlet is 966 mm 2 . The change in the flow cross-sectional area between the intersection line and the inlet is 0.312%, and the change in the flow cross-sectional area between the outlet end and the inlet end is 0.416%. This implementation method can ensure the consistency of the flow cross-section, reduce the pressure loss along the intake port due to the reduction of the flow resistance, and naturally increase the intake air volume of the engine.

[0034] In this embodiment, the angle of the intake manifold outlet and the angle of the intake port inlet need to be strictly consistent. Otherwise, it will lead to differences in the velocity distribution of the fluid at the intake port inlet, and further cause differences in the in-cylinder tumble ratio.

[0035] The consistency deviation of the vortex / tumble ratio of the traditional cast intake port is generally within ±0.1, but the vortex / tumble ratio of the machined type can be controlled within ±0.05.

Claims

1. An engine air intake duct with low flow resistance using a machining process, characterized in that: The engine intake duct includes five parts in appearance, namely, an inlet section (1), a valve boss (2), a large arc section (3-1), a small straight section (3-2), and an outlet section (4). The outlet section of the intake duct is connected to the combustion chamber of the cylinder head. The ratio of the outlet diameter of the intake duct to the inlet diameter is between 1.0 and 1.

1. The value range of the angle between the central axis of the inlet of the intake duct and the bottom plane of the cylinder head is between 12° and 20°. The outlet section is coaxial with the valve boss. The value range of the angle between the central axis of the valve boss and the bottom plane of the cylinder head is between 70° and 80°. By adjusting the central axis of the valve boss and the bottom plane of the cylinder head, the inlet section of the engine intake duct is connected to the combustion chamber of the cylinder head. The angle of the plane is used to obtain the best tumble ratio; the radius of the large arc segment of the intake duct is determined by the intake duct outlet diameter, the lower end point of the small straight line segment is the vertex of the valve seat ring (9), the upper end point of the small straight line segment and the wall of the intake duct inlet section are intersected, and the specific position of the intersection is determined by the slope of the small straight line segment. The arc length of the large arc segment starts from the end point of the intake duct inlet section and ends at the vertex of the intake duct outlet section, so the length of the small straight line segment corresponds to the arc length range of the large arc segment, and the length of the intake duct outlet section is determined by the height of the valve seat ring, and the length of the intake duct outlet section is 2-5 mm larger than the height of the valve seat ring.

2. The engine air intake duct with low flow resistance characteristics using machining technology according to claim 1, characterized in that: The center of the arc of the large arc segment is located at the upper vertex of the inlet duct outlet section; the end point of the large arc segment is connected with the inlet duct outlet section, and the inlet duct cross-sectional diameter corresponding to the end point of the large arc segment is equal to the diameter of the inlet duct outlet section, but the ratio of the diameter at the end face of the outlet section to the diameter at the end face of the inlet duct inlet is between 1.0 and 1.

1.

3. A method for machining an engine intake duct having a low flow resistance characteristic using a machining process according to claim 1, characterized in that: The large arc segment is processed by two processes using different rotating axes to form an intersecting line. Since the same arc is used for rotation processing, the projection of the intersecting line is a straight line. The left endpoint of the straight line segment is located on the side close to the small straight line segment; the right endpoint is located on the large arc segment, and a straight line is drawn at point C on the outlet end face of the intake duct to intersect the projection line segment AB of the intersecting line at right angles. The intersection point is denoted as F, and a perpendicular line is drawn at 1 / 2 of the line segment FA and denoted as G; a perpendicular line is drawn at 1 / 2 of the projection line segment AB of the intersecting line and denoted as H. The center line I of G and H is the axis of the small straight line segment, and the angle between the axis and the bottom plane of the cylinder head is the slope of the small straight line segment, thereby determining the specific position of the intersection of the small straight line segment and the wall of the intake duct inlet section.

4. The method for machining an engine intake duct with low flow resistance characteristics using machining technology according to claim 3, characterized in that: A T-shaped milling cutter (6) is used to perform rotary cutting on the cross section of the air intake duct with the axis of the small straight line segment; and a forming milling cutter (5) is used to perform rotary cutting on the cross section of the air intake duct with the central axis of the air intake duct.

Images