Exhaust system for an engine and vehicle

Abstract

This invention discloses an exhaust system for an engine and a vehicle. The exhaust system includes a cylinder head, a cylinder head combustion chamber formed on the cylinder head, a first exhaust valve and a second exhaust valve disposed within the combustion chamber, and a connecting edge formed between the combustion chamber and the bottom surface of the cylinder head near the first and second exhaust valves. The minimum distance between the connecting edge and the axis of the first exhaust valve is d1, the maximum distance between the axis of the first exhaust valve and the first edge is d2, and the radius of the exhaust valve disc is d, satisfying d1≤d<d2. This invention, by ensuring that the minimum distance d1 between the connecting edge and the line connecting the centers of the first and second exhaust valves, the maximum distance d2 between the line connecting the centers of the first and second exhaust valves and the connecting edge, and the radius d of the exhaust valve disc satisfy d1≤d<d2, allows exhaust gas to be discharged more smoothly from the cylinder head combustion chamber, reducing the residual exhaust gas content in the cylinder and simultaneously reducing in-cylinder knocking.

Description

Technical Field

[0001] This invention relates to the field of automobile engines, and more particularly to an exhaust system for an engine and a vehicle. Background Technology

[0002] With the continuous upgrading of emission and fuel consumption regulations in the automotive industry, the design of engine combustion systems also needs further breakthroughs to meet usage requirements. Advanced ignition timing and reduced pumping losses are important measures to improve fuel efficiency, while the design of the exhaust system has a significant impact on improving pumping losses and reducing residual exhaust gases. Therefore, how to improve the exhaust capacity of the exhaust system and reduce in-cylinder residual exhaust gases has become an urgent problem to be solved in this field. Summary of the Invention

[0003] This invention aims to at least solve one of the technical problems existing in the prior art. Therefore, one object of this invention is to provide an exhaust system for an engine. The exhaust system for an engine according to the invention ensures that the minimum distance d1 between the connecting edge and the axis of the first exhaust valve, the maximum distance d2 between the axis of the first exhaust valve and the connecting edge, and the radius d of the exhaust valve disc satisfy d1≤d≤d2, thereby allowing exhaust gases to be discharged more smoothly from the cylinder head combustion chamber, reducing the residual exhaust gas content in the cylinder, and simultaneously reducing in-cylinder knocking.

[0004] The present invention also proposes a vehicle including the above-described exhaust system.

[0005] An exhaust system for an engine according to the present invention includes: a cylinder head, on which a cylinder head combustion chamber is formed, wherein a first exhaust valve and a second exhaust valve are disposed within the combustion chamber, and a connecting edge is formed between the combustion chamber and the bottom surface of the cylinder head near the first exhaust valve and the second exhaust valve, the connecting edge comprising: a first edge, the first edge being arc-shaped and surrounding at least a portion of the outer periphery of the first exhaust valve; a second edge, the second edge being arc-shaped and surrounding at least a portion of the outer periphery of the second exhaust valve; and a third edge, the third edge connecting the first edge and the second edge, the protrusion direction of the third edge being opposite to the protrusion direction of the first edge and the second edge; a minimum distance d1 between the connecting edge and the line connecting the center of the first exhaust valve and the center of the second exhaust valve, a maximum distance d2 between the line connecting the center of the first exhaust valve and the center of the second exhaust valve and the connecting edge, and the radius of the disc portion of the exhaust valve being d and satisfying: d1 ≤ d < d2.

[0006] The exhaust system for an engine according to the present invention includes a cylinder head, on which cylinder head combustion chambers are formed. The number of cylinder head combustion chambers is configured to be multiple. An engine generally has multiple combustion chambers; for example, a four-cylinder engine means that four combustion chambers are formed in the engine bay. Each combustion chamber has an independent exhaust passage. A first exhaust valve and a second exhaust valve are provided in each combustion chamber. A connecting edge is formed between the combustion chamber and the cylinder head floor near the first and second exhaust valves. The connecting edge is composed of three arc segments, including a first edge, a second edge, and a third edge. The first edge surrounds at least a portion of the outer periphery of the first exhaust valve. The second edge surrounds at least a portion of the outer periphery of the second exhaust valve. The third edge connects the first and second edges, with the protrusion direction of the third edge opposite to that of the first and second edges. The third edge protrudes towards the center of the cylinder head bottom surface. The minimum distance between the connecting edge and the line connecting the center of the first and second exhaust valves is d1, which is also the minimum distance between the third edge and the line connecting the center of the first and second exhaust valves. The maximum distance between the line connecting the center of the first and second exhaust valves and the connecting edge is d2. The radius of the exhaust valve disc is d, satisfying: d1 ≤ d < d2. This configuration can improve the flow coefficient of the exhaust system, expel as much exhaust gas as possible from the cylinder, reduce the residual exhaust gas content in the cylinder, and simultaneously reduce in-cylinder knocking.

[0007] According to one embodiment of the present invention, d1 and d satisfy: 0.8≤d1 / d≤1.

[0008] According to one embodiment of the present invention, d2 and d satisfy: 1.1≤d2 / d≤1.3.

[0009] According to one embodiment of the present invention, at least a portion of the edge of the combustion chamber is formed between the disc portion of the exhaust valve, the width of the gap being e and satisfying: 1mm≤e≤2mm.

[0010] According to one embodiment of the present invention, a first intake valve and a second intake valve are further provided in the cylinder head combustion chamber, and a transition arc surface is formed between the first intake valve and the first exhaust valve; an exhaust-side ridge surface is formed in the cylinder head combustion chamber between the first exhaust valve and the second exhaust valve; wherein the edge of the exhaust-side ridge surface away from the first exhaust valve and the edge of the transition arc surface away from the center of the cylinder head combustion chamber are respectively angled with the axis of the second exhaust valve by α, and α satisfies: 110°≤α≤190°.

[0011] According to one embodiment of the present invention, the venting-side ridge surface protrudes beyond the disc portion of the venting door, and the height difference between the end face of the disc portion of the venting door and the venting-side ridge surface within the included angle α is h, wherein h satisfies 0mm < h ≤ 1mm.

[0012] According to one embodiment of the present invention, the cylinder head combustion chambers are configured as a plurality of symmetrically arranged in the cylinder extension direction; the exhaust system further includes: a first exhaust pipe and a second exhaust pipe, the first exhaust pipe having a first inlet and the second exhaust pipe having a second inlet, the outlet of the first exhaust pipe communicating with the outlet of the second exhaust pipe, the first inlet and the second inlet respectively communicating with two cylinder head combustion chambers symmetrically arranged in the cylinder head extension direction, the angle between the tangent of the outlet end of the first exhaust pipe in the exhaust direction and the tangent of the outlet end of the second exhaust pipe in the exhaust direction being α1, and satisfying: 60°≤α1≤ 120°; a third exhaust pipe and a fourth exhaust pipe, wherein the third exhaust pipe is provided with a third inlet and the fourth exhaust pipe is provided with a fourth inlet, the outlet of the third exhaust pipe is connected to the outlet of the fourth exhaust pipe, the third inlet and the fourth inlet are respectively connected to two cylinder head combustion chambers symmetrically arranged in the cylinder head extension direction, the third exhaust pipe and the fourth exhaust pipe are arranged between the first exhaust pipe and the second exhaust pipe, and the angle between the tangent of the outlet end of the third exhaust pipe in the exhaust direction and the tangent of the outlet end of the fourth exhaust pipe in the exhaust direction is α2, and satisfies: 30°≤α2≤40°.

[0013] According to one embodiment of the present invention, the exhaust system further includes: a first exhaust manifold and a second exhaust manifold, wherein the first exhaust manifold is connected to the first exhaust pipe and the second exhaust pipe respectively, and the second exhaust manifold is connected to the third exhaust pipe and the fourth exhaust pipe respectively, wherein the cross-sectional area of ​​the first exhaust manifold is S1, the cross-sectional area of ​​the second exhaust manifold is S2, and the cross-sectional area of ​​the exhaust outlet of the cylinder head combustion chamber 11 is S3, and satisfies 1≤S1 / S3≤1.8 and 1≤S2 / S3≤1.8.

[0014] According to one embodiment of the present invention, the second exhaust manifold is located at the bottom of the first exhaust manifold.

[0015] The vehicle according to another embodiment of the present invention is briefly described below.

[0016] The vehicle according to the present invention includes the exhaust system described in any of the above embodiments. Since the vehicle according to the present invention includes the exhaust system described in any of the above embodiments, the exhaust performance of the engine of the vehicle according to the present invention is better.

[0017] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0018] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a structural diagram of an exhaust system for an engine according to the present invention; Figure 2 This is a cylinder head structure diagram for an engine exhaust system according to the present invention; Figure 3 This is a partial structural diagram of an exhaust system for an engine according to the present invention; Figure 4 This is a comparison diagram of exhaust performance before and after optimization of the exhaust system for an engine according to the present invention; Figure 5 This is a partial structural diagram of an exhaust system for an engine according to the present invention.

[0019] Figure label: Exhaust system 1; Cylinder head combustion chamber 11, first exhaust valve 111, second exhaust valve 112; First edge 121, second edge 122, third edge 123; First intake valve 131, second intake valve 132; exhaust side ridge surface 141, transition arc surface 142; First exhaust pipe 151, second exhaust pipe 152, third exhaust pipe 153, fourth exhaust pipe 154; First exhaust manifold 161, second exhaust manifold 162. Detailed Implementation

[0020] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0021] With the continuous upgrading of emission and fuel consumption regulations in the automotive industry, the design of engine combustion systems also needs further breakthroughs to meet usage requirements. Advanced ignition timing and reduced pumping losses are important measures to improve fuel efficiency, while the design of the exhaust system has a significant impact on improving pumping losses and reducing residual exhaust gases. Therefore, how to improve the exhaust capacity of the exhaust system and reduce in-cylinder residual exhaust gases has become an urgent problem to be solved in this field.

[0022] The following is for reference. Figures 1-5 An exhaust system for an engine is described according to an embodiment of the present invention.

[0023] The exhaust system for an engine according to the present invention includes a cylinder head, on which a cylinder head combustion chamber 11 is formed. A first exhaust valve 111 and a second exhaust valve 112 are disposed within the combustion chamber. A connecting edge is formed between the combustion chamber and the bottom surface of the cylinder head near the first exhaust valve 111 and the second exhaust valve 112. The connecting edge includes: a first edge 121, which is arc-shaped and surrounds at least a portion of the outer periphery of the first exhaust valve 111; and a second edge 122, which is arc-shaped and surrounds at least a portion of the outer periphery of the second exhaust valve 112. Partial outer periphery; third edge 123, the third edge 123 connects between the first edge 121 and the second edge 122, the protrusion direction of the third edge 123 is opposite to the protrusion direction of the first edge 121 and the second edge 122; the minimum distance between the connecting edge and the line connecting the center of the first exhaust valve 111 and the center of the second exhaust valve 112 is d1, the maximum distance between the line connecting the center of the first exhaust valve 111 and the center of the second exhaust valve 112 and the connecting edge is d2, the radius of the exhaust valve disc is d and satisfies: d1≤d<d2.

[0024] The exhaust system for an engine according to the present invention includes a cylinder head, on which cylinder head combustion chambers 11 are formed. The number of cylinder head combustion chambers 11 is configured to be multiple. An engine generally has multiple combustion chambers; for example, a four-cylinder engine has four combustion chambers. Each combustion chamber has an independent exhaust passage. A first exhaust valve 111 and a second exhaust valve 112 are provided in each combustion chamber. A connecting edge is formed between the combustion chamber and the cylinder head ground near the first exhaust valve 111 and the second exhaust valve 112. The connecting edge is composed of three arc segments, including a first edge 121, a second edge 122, and a third edge 123. The first edge 121 surrounds at least a portion of the outer periphery of the first exhaust valve 111, and the second edge 122 surrounds... At least a portion of the outer periphery of the second exhaust valve 112 has a third edge 123 connecting the first edge 121 and the second edge 122. The protrusion direction of the third edge 123 is opposite to that of the first edge 121 and the second edge 122. The third edge 123 protrudes towards the center of the bottom surface of the cylinder head. The minimum distance between the connecting edge and the line connecting the center of the first exhaust valve 111 and the center of the second exhaust valve 112 is d1, which is the minimum distance between the third edge 123 and the line connecting the center of the first exhaust valve 111 and the center of the second exhaust valve 112. The maximum distance between the line connecting the center of the first exhaust valve 111 and the center of the second exhaust valve 112 and the connecting edge is d2. The radius of the exhaust valve disc is d and satisfies: d1 ≤ d < d2. This setting can improve the flow coefficient of the exhaust system, expel as much exhaust gas as possible from the cylinder, reduce the residual exhaust gas content in the cylinder, and simultaneously reduce in-cylinder knocking.

[0025] According to one embodiment of the present invention, d1 and d satisfy: 0.8≤d1 / d≤1. This can improve the flow coefficient of the exhaust system, expel as much exhaust gas as possible from the cylinder, reduce the residual exhaust gas content in the cylinder, and at the same time reduce in-cylinder knocking.

[0026] According to one embodiment of the present invention, d2 and d satisfy: 1.1≤d2 / d≤1.3. This setting can improve the flow coefficient of the exhaust system, expel as much exhaust gas as possible from the cylinder, reduce the residual exhaust gas content in the cylinder, and at the same time reduce in-cylinder knocking.

[0027] According to one embodiment of the present invention, at least a portion of the edge of the cylinder head combustion chamber 11 is formed between the cylinder head combustion chamber 11 and the exhaust valve disc, the width of the gap being e and satisfying: 1mm≤e≤2mm, which facilitates better exhaust of the in-cylinder exhaust gas and reduces the residual exhaust gas content in the cylinder.

[0028] According to one embodiment of the present invention, a first intake valve 131 and a second intake valve 132 are further provided in the cylinder head combustion chamber 11, and a transition arc surface 142 is formed between the first intake valve 131 and the first exhaust valve 111; an exhaust-side ridge surface 141 is formed in the cylinder head combustion chamber 11 between the first exhaust valve 111 and the second exhaust valve 112; wherein the edge of the exhaust-side ridge surface 141 away from the first exhaust valve 111 and the edge of the transition arc surface 142 away from the center of the cylinder head combustion chamber 11 respectively form an angle α with the axis of the second exhaust valve 112, and α satisfies: 110°≤α≤190°. Among them, a transition arc surface 142 is formed between the first intake valve 131 and the first exhaust valve 111, and another transition arc surface 142 is formed between the second intake valve 132 and the second exhaust valve 112; an exhaust-side ridge surface 141 is formed between the first exhaust valve 111 and the second exhaust valve 112. The edges of the exhaust-side ridge surface 141 away from the first exhaust valve 111 and the edges of the transition arc surface 142 away from the center of the cylinder head combustion chamber 11 are respectively angled with the axis of the second exhaust valve 112 by α, which satisfies: 110°≤α≤190°. This is beneficial to improve the exhaust effect of the first exhaust valve 111 and the second exhaust valve 112, and to discharge the exhaust gas in the cylinder as much as possible, so as to reduce the residual exhaust gas content in the cylinder.

[0029] According to one embodiment of the present invention, the exhaust-side ridge surface 141 protrudes beyond the exhaust valve disc, and the height difference between the exhaust-side ridge surface 141 and the end face of the exhaust valve disc within the included angle α is h, where h satisfies 0mm < h ≤ 1mm. This facilitates the discharge of exhaust gas from the cylinder head combustion chamber 11, reduces residual exhaust gas in the cylinder, and lowers in-cylinder knock.

[0030] According to one embodiment of the present invention, the cylinder head combustion chamber 11 is configured as a plurality of symmetrically arranged in the cylinder extension direction; the exhaust system further includes: a first exhaust pipe 151 and a second exhaust pipe 152, the first exhaust pipe 151 is provided with a first inlet, the second exhaust pipe 152 is provided with a second inlet, the outlet of the first exhaust pipe 151 is connected to the outlet of the second exhaust pipe 152, the first inlet and the second inlet are respectively connected to two cylinder head combustion chambers 11 symmetrically arranged in the cylinder head extension direction, and the angle between the tangent of the outlet end of the first exhaust pipe 151 in the exhaust direction and the tangent of the outlet end of the second exhaust pipe 152 in the exhaust direction is α1, and satisfies: 60°≤α1≤120°. The third exhaust pipe 153 and the fourth exhaust pipe 154 are provided. The third exhaust pipe 153 is provided with a third inlet, and the fourth exhaust pipe 154 is provided with a fourth inlet. The outlet of the third exhaust pipe 153 is connected to the outlet of the fourth exhaust pipe 154. The third inlet and the fourth inlet are respectively connected to two cylinder head combustion chambers 11 symmetrically located in the cylinder head extension direction. The third exhaust pipe 153 and the fourth exhaust pipe 154 are located between the first exhaust pipe 151 and the second exhaust pipe 152. The angle between the tangent of the outlet end of the third exhaust pipe 153 in the exhaust direction and the tangent of the outlet end of the fourth exhaust pipe 154 in the exhaust direction is α2, and satisfies: 30°≤α2≤40°.

[0031] Specifically, the cylinder head combustion chambers 11 are constructed as multiple chambers symmetrically arranged in the cylinder extension direction. Taking a four-cylinder engine as an example, cylinders one, two, three, and four are arranged at intervals in the cylinder head extension direction. The first inlet of the first exhaust pipe 151 is connected to the cylinder head combustion chamber 11 on cylinder one, and the second inlet of the second exhaust pipe 152 is connected to the cylinder head combustion chamber 11 on cylinder four. The outlet of the first exhaust pipe 151 is connected to the outlet of the second exhaust pipe 152, and the outlets of the first exhaust pipe 151 and the second exhaust pipe 152 are combined into one outlet. The angle between the tangent of the outlet end of the first exhaust pipe 151 in the exhaust direction and the tangent of the outlet end of the second exhaust pipe 152 in the exhaust direction is α1, and satisfies: 60°≤α1≤120°. This makes the exhaust system exhaust more smoothly and reduces the mutual interference between cylinder one and cylinder four in their respective exhaust processes. The exhaust system avoids backflow of exhaust gas between the first exhaust pipe 151 and the second exhaust pipe 152. The third inlet of the third exhaust pipe 153 is connected to the cylinder head combustion chamber 11 on the second cylinder, and the fourth inlet of the fourth exhaust pipe 154 is connected to the cylinder head combustion chamber 11 on the third cylinder. The outlet of the third exhaust pipe 153 is connected to the outlet of the fourth exhaust pipe 154. The outlets of the third exhaust pipe 153 and the fourth exhaust pipe 154 are combined into one outlet. The angle between the tangent of the outlet end of the third exhaust pipe 153 in the exhaust direction and the tangent of the outlet end of the fourth exhaust pipe 154 in the exhaust direction is α2, which satisfies: 30°≤α2≤40°. This makes the exhaust system exhaust more smoothly, reduces the mutual interference between the second and third cylinders in their respective exhaust processes, and avoids backflow of exhaust gas between the third exhaust pipe 153 and the fourth exhaust pipe 154.

[0032] According to one embodiment of the present invention, the exhaust system further includes a first exhaust manifold 161 and a second exhaust manifold 162. The first exhaust manifold 161 is connected to the first exhaust pipe 151 and the second exhaust pipe 152, respectively. The second exhaust manifold 162 is connected to the third exhaust pipe 153 and the fourth exhaust pipe 154, respectively. The cross-sectional area of ​​the first exhaust manifold 161 is S1, the cross-sectional area of ​​the second exhaust manifold 162 is S2, and the cross-sectional area of ​​the exhaust outlet of the cylinder head combustion chamber 11 is S3, and satisfies 1≤S1 / S3≤1.8 and 1≤S2 / S3≤1.8. The exhaust system of the present invention connects the outlet of the first exhaust pipe 151 to the outlet of the second exhaust pipe 152 and to the first exhaust manifold 161, and the outlet of the third exhaust pipe 153 to the outlet of the fourth exhaust pipe 154 and to the second exhaust manifold 162. By merging the first exhaust pipe 151 and the second exhaust pipe 152 into a common outlet with an outlet cross-sectional area of ​​S1, and merging the third exhaust pipe 153 and the fourth exhaust pipe 154 into a common outlet with an outlet cross-sectional area of ​​S2, and S1, S2 and S3 satisfy: 1≤S1 / S3≤1.8, 1≤S2 / S3≤1.8, the exhaust gas in the cylinder head combustion chamber 11 is discharged more smoothly and flows into the exhaust pipe, which is beneficial to reduce the exhaust gas in the cylinder and reduce the in-cylinder knock.

[0033] like Figure 4 As shown in the figure, the horizontal axis represents the exhaust valve lift, and the vertical axis represents the exhaust flow coefficient. According to the present invention, the exhaust system for engines achieves an overall improvement in the optimized exhaust flow coefficient.

[0034] According to one embodiment of the present invention, the second exhaust manifold 162 is located at the bottom of the first exhaust manifold 161. The outlet of the first exhaust pipe 151 is connected to the outlet of the second exhaust pipe 152 and is also connected to the first exhaust manifold 161. The outlet of the third exhaust pipe 153 is connected to the outlet of the fourth exhaust pipe 154 and is also connected to the second exhaust manifold 162. The second exhaust manifold 162 is located at the bottom of the first exhaust manifold 161, which allows the exhaust gas to be discharged more smoothly and reduces the exhaust gas in the cylinder.

[0035] The vehicle according to the present invention is briefly described below.

[0036] The vehicle according to the present invention includes the exhaust system described in any of the above embodiments. Since the vehicle according to the present invention includes the exhaust system described in any of the above embodiments, the exhaust performance of the engine of the vehicle according to the present invention is better.

[0037] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0038] In the description of this invention, "first feature" and "second feature" may include one or more of the features.

[0039] In the description of this invention, "a plurality of" means two or more.

[0040] In the description of this invention, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or it may include the first and second features not being in direct contact but being in contact through another feature between them.

[0041] In the description of this invention, the terms "above," "over," and "on top" for the first feature and the second feature include the first feature being directly above or diagonally above the second feature, or simply indicating that the first feature is at a higher horizontal level than the second feature.

[0042] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0043] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. An exhaust system for an engine, characterized in that, include: A cylinder head, on which a cylinder head combustion chamber (11) is formed, wherein a first exhaust valve (111) and a second exhaust valve (112) are disposed, and a connecting edge is formed between the combustion chamber and the bottom surface of the cylinder head near the first exhaust valve (111) and the second exhaust valve (112), the connecting edge comprising: The first edge (121) is arc-shaped and surrounds at least a portion of the outer periphery of the first exhaust valve (111); The second edge (122) is arc-shaped and surrounds at least a portion of the outer periphery of the second exhaust valve (112); The third edge (123) is connected between the first edge (121) and the second edge (122), and the protrusion direction of the third edge (123) is opposite to the protrusion direction of the first edge (121) and the second edge (122); The minimum distance between the connecting edge and the line connecting the center of the first exhaust valve (111) and the center of the second exhaust valve (112) is d1, the maximum distance between the line connecting the center of the first exhaust valve (111) and the center of the second exhaust valve (112) and the connecting edge is d2, and the radius of the disk of the exhaust valve is d and satisfies: d1≤d<d2.

2. The exhaust system for an engine according to claim 1, characterized in that, d1 and d satisfy: 0.8≤d1 / d≤1.

3. The exhaust system for an engine according to claim 1, characterized in that, d2 and d satisfy: 1.1≤d2 / d≤1.

3.

4. The exhaust system for an engine according to claim 1, characterized in that, At least a portion of the edge of the cylinder head combustion chamber (11) is formed with the disc portion of the exhaust valve, the width of the gap being e and satisfying: 1mm≤e≤2mm.

5. The exhaust system for an engine according to claim 1, characterized in that, The cylinder head combustion chamber (11) is also provided with a first intake valve (131) and a second intake valve (132), and a transition arc surface (142) is formed between the first intake valve (131) and the first exhaust valve (111). An exhaust-side roof ridge (141) is formed within the cylinder head combustion chamber (11) between the first exhaust valve (111) and the second exhaust valve (112); wherein The edge of the exhaust side ridge surface (141) away from the first exhaust valve (111) and the edge of the transition arc surface (142) away from the center of the cylinder head combustion chamber (11) are respectively angled with the axis of the second exhaust valve (112) by α, and α satisfies: 110°≤α≤190°.

6. The exhaust system for an engine according to claim 5, characterized in that, The venting side ridge surface (141) protrudes from the plate of the venting door, and the height difference between the end face of the plate of the venting door and the venting side ridge surface (141) within the included angle α is h, where h satisfies 0mm < h ≤ 1mm.

7. The exhaust system for an engine according to claim 1, characterized in that, The cylinder head combustion chamber (11) is configured as a plurality of chambers symmetrically arranged in the cylinder extension direction; The exhaust system also includes: The first exhaust pipe (151) and the second exhaust pipe (152) are provided with a first inlet and a second inlet. The outlet of the first exhaust pipe (151) is connected to the outlet of the second exhaust pipe (152). The first inlet and the second inlet are respectively connected to two cylinder head combustion chambers (11) that are symmetrical in the cylinder head extension direction. The angle between the tangent of the outlet end of the first exhaust pipe (151) in the exhaust direction and the tangent of the outlet end of the second exhaust pipe (152) in the exhaust direction is α1, and satisfies: 60°≤α1≤120°. The third exhaust pipe (153) and the fourth exhaust pipe (154) are provided with a third inlet and a fourth inlet. The outlet of the third exhaust pipe (153) is connected to the outlet of the fourth exhaust pipe (154). The third inlet and the fourth inlet are respectively connected to two cylinder head combustion chambers (11) that are symmetrical in the cylinder head extension direction. The third exhaust pipe (153) and the fourth exhaust pipe (154) are located between the first exhaust pipe (151) and the second exhaust pipe (152). The angle between the tangent of the outlet end of the third exhaust pipe (153) in the exhaust direction and the tangent of the outlet end of the fourth exhaust pipe (154) in the exhaust direction is α2, and satisfies: 30°≤α2≤40°.

8. The exhaust system for an engine according to claim 7, characterized in that, Also includes: The first exhaust manifold (161) and the second exhaust manifold (162) are connected to the first exhaust manifold (151) and the second exhaust manifold (152) respectively, and the second exhaust manifold (162) is connected to the third exhaust manifold (153) and the fourth exhaust manifold (154) respectively. The cross-sectional area of ​​the first exhaust manifold (161) is S1, the cross-sectional area of ​​the second exhaust manifold (162) is S2, and the cross-sectional area of ​​the exhaust outlet of the cylinder head combustion chamber (11) is S3, and satisfies 1≤S1 / S3≤1.8, 1≤S2 / S3≤1.

8.

9. The exhaust system for an engine according to claim 8, characterized in that, The second exhaust manifold (162) is located at the bottom of the first exhaust manifold (161).

10. A vehicle, characterized in that, Includes the exhaust system described in any one of claims 1-9.

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