Engine exhaust structure, engine and motorcycle

Abstract

The present invention relates to an engine exhaust structure, an engine and a motorcycle. The engine exhaust structure comprises a first connecting pipe, a first sleeve, a second connecting pipe and a second sleeve. The inlet of the first connecting pipe is used to be connected to the engine. The first sleeve is closed at one end close to the engine. The first sleeve is sleeved outside the first connecting pipe to form a resonance cavity. The exhaust gas discharged by the first connecting pipe can enter the resonance cavity. The inlet of the second connecting pipe is arranged corresponding to the outlet of the first connecting pipe. The outlet of the second connecting pipe is used to be connected to a muffler, and the inlet size of the second connecting pipe is smaller than the outlet size of the second connecting pipe. The second sleeve is sleeved outside the second connecting pipe and the first sleeve respectively to form a pressure stabilizing cavity. The backflow of exhaust gas is suppressed by the cooperation of the resonance cavity and the pressure stabilizing cavity, and the backflow amount of exhaust gas is reduced, thereby improving the charging efficiency and increasing the torque of the engine. At the same time, the resonance cavity can change the peak value of the reflected exhaust pressure wave to achieve the purpose of noise reduction.

Description

Technical Field

[0001] The present invention relates to the technical field of motorcycles, and in particular to an engine exhaust structure, an engine and a motorcycle. Background Art

[0002] Existing motorcycles include an engine and an exhaust pipe, and the exhaust pipe is connected to the engine. During the operation of the motorcycle, the exhaust gas generated in the combustion chamber of the engine flows out from the engine outlet and is discharged through the exhaust pipe. However, the exhaust gas generates an exhaust pressure reflection wave in the exhaust pipe. During the valve overlap angle period, if a positive pressure wave is reflected in the exhaust pipe, the reflected positive pressure wave will prevent the exhaust gas from being discharged. The exhausted exhaust gas is reflected back into the combustion chamber of the engine, and part of the exhaust gas flows back into the intake duct through the open intake valve, which reduces the charging efficiency of the engine, thereby reducing the engine torque. Summary of the invention

[0003] Based on this, it is necessary to provide an engine exhaust structure to reduce the backflow of exhaust gas, improve the engine's charging efficiency, and increase the engine's torque.

[0004] An engine exhaust structure, comprising:

[0005] a first connecting pipe, wherein an inlet of the first connecting pipe is used to be connected to an engine;

[0006] A first sleeve, wherein one end of the first sleeve close to the engine is closed, and the first sleeve is sleeved outside the first connecting pipe to form a resonant cavity;

[0007] a second connecting pipe, wherein an inlet of the second connecting pipe is arranged corresponding to an outlet of the first connecting pipe, and a size of the inlet of the second connecting pipe is smaller than a size of the outlet of the second connecting pipe;

[0008] The second sleeve is respectively sleeved outside the second connecting pipe and the first sleeve to form a pressure-stabilizing cavity; wherein the exhaust gas discharged from the first connecting pipe can enter the resonance cavity, and the exhaust gas in the resonance cavity can be discharged into the pressure-stabilizing cavity.

[0009] The above engine exhaust structure has at least the following advantages:

[0010] In the above-mentioned engine exhaust structure, the first sleeve is sleeved outside the first connecting pipe to form a resonance cavity; the second sleeve is sleeved outside the first sleeve and the second connecting pipe to form a pressure stabilizing cavity. The pressure stabilizing cavity is connected to the first connecting pipe, the resonance cavity, and the second connecting pipe respectively, and is the load boundary of the first connecting pipe, the resonance cavity, and the second connecting pipe, and directly affects the reflection of the exhaust pressure wave. Under the action of the reflected exhaust pressure wave, when the exhaust gas in the second connecting pipe flows reversely into the first connecting pipe, the resonance cavity can absorb some of the refluxed exhaust gas, thereby reducing the refluxed exhaust gas entering the first connecting pipe; when the first connecting pipe exhausts forward to the second connecting pipe, the exhaust gas stored in the resonance cavity is released and flows to the second connecting pipe, and at the same time, the exhaust gas in the pressure stabilizing cavity also flows to the second connecting pipe, and the exhaust gas backflow is suppressed by the coordinated action of the resonance cavity and the pressure stabilizing cavity, and the backflow of the exhaust gas is reduced, thereby improving the charging efficiency and increasing the torque of the engine. Since the inlet size of the second connecting pipe is smaller than the outlet size of the second connecting pipe, the second connecting pipe plays a role of interception, increasing the amount of exhaust gas flowing back into the resonance cavity, and the increase in exhaust gas in the resonance cavity can better suppress the backflow of exhaust gas and reduce the backflow of exhaust gas, thereby further improving the charging efficiency and increasing the torque of the engine. In addition, the resonance cavity can change the peak value of the reflected exhaust pressure wave, reduce the peak value of the exhaust pressure wave, and increase the trough of the exhaust pressure wave, so that the intensity of the change of the exhaust pressure wave is reduced, so that the amplitude of the pressure change is reduced, thereby achieving the purpose of noise reduction.

[0011] The technical solution is further described below:

[0012] In one embodiment, the equivalent diameter of the pressure stabilizing cavity is larger than the diameter of the first connecting pipe, the equivalent diameter of the first sleeve, and the equivalent diameter of the second connecting pipe.

[0013] In one embodiment, the length of the first connecting tube is greater than that of the first sleeve, and the distance between an end surface of the first sleeve close to the second connecting tube and an end surface of the outlet end of the first connecting tube is 3 mm to 20 mm.

[0014] In one embodiment, the distance between the outer surface of the first connecting tube and the inner wall of the first sleeve is 2 mm to 15 mm.

[0015] In one embodiment, the first casing includes a first pipe section and a second pipe section connected to each other, the second pipe section is arranged close to the second connecting pipe, and the equivalent diameter of the second pipe section is smaller than the diameter of the first pipe section.

[0016] In one embodiment, the second pipe section includes a connecting section and an avoidance section, the connecting section is connected to the first connecting pipe, an inlet and an outlet are formed between the avoidance section and the first connecting pipe, and the pressure stabilizing cavity is connected to the resonant cavity through the inlet and the outlet.

[0017] In one embodiment, one end of the first sleeve close to the second connecting pipe is closed, and a vent hole is provided on the first connecting pipe. The first connecting pipe is connected to the resonant cavity through the vent hole; the resonant cavity is a quarter-wavelength resonant cavity.

[0018] In one embodiment, the engine exhaust structure further includes a catalyst, which is disposed in the second sleeve and located at the outlet of the second connecting pipe; the inner diameter of the inlet of the second connecting pipe is smaller than the diameter of the catalyst core.

[0019] An engine comprises a muffler and the engine exhaust structure, wherein the muffler is connected to the engine exhaust structure.

[0020] In the above-mentioned engine, the first sleeve is sleeved outside the first connecting pipe to form a resonance cavity; the second sleeve is sleeved outside the first sleeve and the second connecting pipe to form a pressure stabilizing cavity. The pressure stabilizing cavity is connected to the first connecting pipe, the resonance cavity, and the second connecting pipe respectively, and is the load boundary of the first connecting pipe, the resonance cavity, and the second connecting pipe, and directly affects the reflection of the exhaust pressure wave. Under the action of the reflected exhaust pressure wave, when the exhaust gas in the second connecting pipe flows reversely into the first connecting pipe, the resonance cavity can absorb some of the refluxed exhaust gas, thereby reducing the refluxed exhaust gas entering the first connecting pipe; when the first connecting pipe exhausts forward to the second connecting pipe, the exhaust gas stored in the resonance cavity is released and flows to the second connecting pipe, and at the same time, the exhaust gas in the pressure stabilizing cavity also flows to the second connecting pipe, and the exhaust gas backflow is suppressed by the coordinated action of the resonance cavity and the pressure stabilizing cavity, and the backflow of the exhaust gas is reduced, thereby improving the charging efficiency and increasing the torque of the engine. Since the inlet size of the second connecting pipe is smaller than the outlet size of the second connecting pipe, the second connecting pipe plays a role of interception, increasing the amount of exhaust gas flowing back into the resonance cavity, and the increase in exhaust gas in the resonance cavity can better suppress the backflow of exhaust gas and reduce the backflow of exhaust gas, thereby further improving the charging efficiency and increasing the torque of the engine. In addition, the resonance cavity can change the peak value of the reflected exhaust pressure wave, reduce the peak value of the exhaust pressure wave, and increase the trough of the exhaust pressure wave, so that the intensity of the change of the exhaust pressure wave is reduced, so that the amplitude of the pressure change is reduced, thereby achieving the purpose of noise reduction.

[0021] A motorcycle comprises the above engine.

[0022] In the above-mentioned motorcycle, the first sleeve is sleeved outside the first connecting pipe to form a resonance cavity; the second sleeve is sleeved outside the first sleeve and the second connecting pipe to form a pressure stabilizing cavity. The pressure stabilizing cavity is connected to the first connecting pipe, the resonance cavity, and the second connecting pipe respectively, and is the load boundary of the first connecting pipe, the resonance cavity, and the second connecting pipe, and directly affects the reflection of the exhaust pressure wave. Under the action of the reflected exhaust pressure wave, when the exhaust gas in the second connecting pipe flows reversely into the first connecting pipe, the resonance cavity can absorb some of the refluxed exhaust gas, thereby reducing the refluxed exhaust gas entering the first connecting pipe; when the first connecting pipe exhausts forward to the second connecting pipe, the exhaust gas stored in the resonance cavity is released and flows to the second connecting pipe, and at the same time, the exhaust gas in the pressure stabilizing cavity also flows to the second connecting pipe, and the exhaust gas backflow is suppressed by the coordinated action of the resonance cavity and the pressure stabilizing cavity, and the backflow of the exhaust gas is reduced, thereby improving the charging efficiency and increasing the torque of the engine. Since the inlet size of the second connecting pipe is smaller than the outlet size of the second connecting pipe, the second connecting pipe plays a role of interception, increasing the amount of exhaust gas flowing back into the resonance cavity, and the increase in exhaust gas in the resonance cavity can better suppress the backflow of exhaust gas and reduce the backflow of exhaust gas, thereby further improving the charging efficiency and increasing the torque of the engine. In addition, the resonance cavity can change the peak value of the reflected exhaust pressure wave, reduce the peak value of the exhaust pressure wave, and increase the trough of the exhaust pressure wave, so that the intensity of the change of the exhaust pressure wave is reduced, so that the amplitude of the pressure change is reduced, thereby achieving the purpose of noise reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A partial schematic diagram of an engine exhaust structure according to an embodiment of the present invention;

[0024] Figure 2 for Figure 1 The cross-sectional view along the AA direction;

[0025] Figure 3 for Figure 1 The cross-sectional view along the BB direction;

[0026] Figure 4 A schematic structural diagram of an engine exhaust structure according to an embodiment of the present invention;

[0027] Figure 5 The figure is a structural exploded view of an engine exhaust structure according to an embodiment of the present invention.

[0028] Description of reference numerals:

[0029] 10. first connecting pipe, 20. first sleeve, 21. first pipe section, 22. second pipe section, 221. first connecting section, 222. second connecting section, 223. first avoidance section, 224. second avoidance section, 30. resonant cavity, 40. second connecting pipe, 50. second sleeve, 60. voltage-stabilizing cavity, 70. catalyst. DETAILED DESCRIPTION

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific implementation disclosed below.

[0031] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The various technical features of the above-described embodiments can be combined arbitrarily. In order to make the description concise, all possible combinations of the various technical features in the above-described embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0033] See also Figure 1 The engine exhaust structure in one embodiment includes a first connecting pipe 10, a first sleeve 20, a second connecting pipe 40 and a second sleeve 50. The inlet of the first connecting pipe 10 is used to connect to the engine, and the outlet of the second connecting pipe 40 is used to connect to the muffler. The first sleeve 20 is closed at one end close to the engine, and the first sleeve 20 is sleeved outside the first connecting pipe 10 to form a resonance cavity 30. The inlet of the second connecting pipe 40 is arranged corresponding to the outlet of the first connecting pipe 10, and the inlet size d1 of the second connecting pipe 40 is smaller than the outlet size d2 of the second connecting pipe 40. Specifically, the inlet of the second connecting pipe 40 is a gradually shrinking structure. The second sleeve 50 is respectively sleeved outside the second connecting pipe 40 and the first sleeve 20 to form a pressure stabilizing cavity 60. Among them, the exhaust gas discharged from the first connecting pipe 10 can enter the resonance cavity 30, and the exhaust gas in the resonance cavity 30 can be discharged into the pressure stabilizing cavity 60.

[0034] In the above engine exhaust structure, the first sleeve 20 is sleeved outside the first connecting pipe 10 to form a resonance cavity 30; the second sleeve 50 is sleeved outside the first sleeve 20 and the second connecting pipe 40 to form a pressure stabilizing cavity 60. The pressure stabilizing cavity 60 is connected to the first connecting pipe 10, the resonance cavity 30, and the second connecting pipe 40 respectively, and is the load boundary of the first connecting pipe 10, the resonance cavity 30, and the second connecting pipe 40, and directly affects the reflection of the exhaust pressure wave. Under the effect of the reflected exhaust pressure wave, when the exhaust gas in the second connecting pipe 40 flows backward into the first connecting pipe 10, the resonant cavity 30 can absorb some of the refluxed exhaust gas, thereby reducing the refluxed exhaust gas entering the first connecting pipe 10; when the first connecting pipe 10 exhausts forward to the second connecting pipe 40, the exhaust gas stored in the resonant cavity 30 is released and flows into the second connecting pipe 40, and at the same time, the exhaust gas in the pressure stabilizing cavity 60 also flows into the second connecting pipe 40, and the coordination of the resonant cavity 30 and the pressure stabilizing cavity 60 suppresses the backflow of the exhaust gas, reduces the backflow amount of the exhaust gas, thereby improving the charging efficiency and increasing the torque of the engine. Since the inlet size of the second connecting pipe 40 is smaller than the outlet size of the second connecting pipe 40, the second connecting pipe plays a role of interception, increasing the amount of exhaust gas flowing back into the resonant cavity 30, and the increase of exhaust gas in the resonant cavity 30 can better suppress the backflow of the exhaust gas, reduce the backflow amount of the exhaust gas, thereby further improving the charging efficiency and increasing the torque of the engine. In addition, the resonance cavity 30 can change the peak value of the reflected exhaust pressure wave, reduce the peak value of the exhaust pressure wave, and raise the trough of the exhaust pressure wave, so that the intensity of the change of the exhaust pressure wave is reduced, and the amplitude of the pressure change is reduced, thereby achieving the purpose of noise reduction.

[0035] For further information, see Figure 1 The outlet of the first connecting pipe 10 and the inlet of the second connecting pipe 40 are arranged at intervals. When the exhaust gas in the second connecting pipe 40 flows back to the first connecting pipe 10, the exhaust gas will first flow back to the pressure stabilizing cavity 60, and will not directly flow back into the first connecting pipe 10. Through the cooperation of the resonance cavity 30 and the pressure stabilizing cavity 60, the backflow of the exhaust gas is suppressed and the backflow amount of the exhaust gas is reduced, thereby improving the charging efficiency of the engine and increasing the torque of the engine.

[0036] In one embodiment, the equivalent diameter of the pressure stabilizing cavity 60 is greater than the diameter of the first connecting pipe 10, the equivalent diameter of the first sleeve 20, and the equivalent diameter of the second connecting pipe 40. The pressure stabilizing cavity 60 is the intersection chamber of the first connecting pipe 10, the resonant cavity 30, and the second connecting pipe 40. Based on the mass flow conservation principle of fluid mechanics, the diameter of the main flow pipe must be greater than the diameter of each branch flow pipe. Therefore, the equivalent diameter of the pressure stabilizing cavity 60 should be greater than the diameter of the first connecting pipe 10, the equivalent diameter of the first sleeve 20, and the equivalent diameter of the second connecting pipe 40.

[0037] In one embodiment, see Figure 1, the length of the first connecting pipe 10 is greater than the length of the first sleeve 20, and the distance d3 between the end face of the first sleeve 20 close to the second connecting pipe 40 and the end face of the outlet end of the first connecting pipe 10 is 3 mm to 20 mm. In this embodiment, in order to support and fix the first sleeve 20, the first sleeve 20 is welded to the first connecting pipe 10. Since the length of the first connecting pipe 10 is greater than the length of the first sleeve 20, it can avoid the welding bead at the welding point between the first connecting pipe 10 and the first sleeve 20 blocking the first connecting pipe 10 and affecting the exhaust smoothness of the first connecting pipe 10. In this embodiment, the first connecting pipe 10 extends out of the first sleeve 20, and the distance d3 between the end of the first sleeve 20 close to the second connecting pipe 40 and the outlet end of the first connecting pipe 10 is 5 mm.

[0038] For further information, see Figure 1 , the distance D between the outer surface of the first connecting pipe 10 and the inner wall of the first sleeve 20 is 2 mm to 15 mm, so that the reflected exhaust pressure wave can fill the resonance cavity 30, the exhaust gas will not form a chaotic airflow in the resonance cavity 30, and the engine exhaust structure can smoothly discharge the exhaust gas to the outside of the second connecting pipe 40. In addition, by limiting the distance D between the outer surface of the first connecting pipe 10 and the inner wall of the first sleeve 20 to a range of 2 mm to 15 mm, the inner diameter of the resonance cavity 30 can be controlled, thereby adjusting the resonance effect of different exhaust systems and engines.

[0039] In one embodiment, see Figure 1 and Figure 3 The first sleeve 20 includes a first pipe section 21 and a second pipe section 22 connected to each other. The second pipe section 22 is arranged close to the second connecting pipe 40, and the equivalent diameter of the second pipe section 22 is smaller than the diameter of the first pipe section 21. Since the size of the second pipe section 22 is smaller than the size of the first pipe section 21, the gas in the resonance cavity 30 can flow to the second connecting pipe 40 at a higher flow rate, which can better suppress the backflow of exhaust gas and reduce the backflow amount of exhaust gas, thereby improving the charging efficiency and increasing the torque of the engine. In this embodiment, the first pipe section 21 and the second pipe section 22 are smoothly connected to increase the smoothness of the exhaust gas flow in the resonance cavity 30.

[0040] Further, the second pipe section 22 includes a connecting section and an avoiding section, the connecting section is connected to the first connecting pipe 10, an inlet and an outlet are formed between the avoiding section and the first connecting pipe 10, and the pressure stabilizing cavity 60 is connected to the resonance cavity 30 through the inlet and the outlet. The exhaust gas in the pressure stabilizing cavity 60 can enter the resonance cavity 30 from the inlet and the outlet, and the exhaust gas in the resonance cavity 30 can be discharged into the pressure stabilizing cavity 60. The first sleeve 20 is connected to the first connecting pipe 10 through the connecting section, which can support and fix the first sleeve 20 on the one hand, and avoid the phenomenon of cracking of the first connecting pipe 10 due to the expansion of the exhaust gas on the other hand.

[0041] Specifically, by adjusting the cross-sectional area of ​​the avoidance section, that is, the size of the inlet and outlet, the exhaust gas backflow of the engine exhaust structure at different speed sections can be suppressed, thereby meeting the improvement of the engine torque at different speed sections. By setting the length of the connecting section and the avoidance section, the cross-sectional area of ​​the avoidance section can be adjusted, thereby suppressing the exhaust gas backflow of the engine exhaust structure at different speed sections.

[0042] For further information, see Figure 2 The connecting section includes a first connecting section 221 and a second connecting section 222, and the avoiding section includes a first avoiding section 223 and a second avoiding section 224. The first connecting section 221 and the second connecting section 222 are arranged opposite to each other, and the first avoiding section 223 and the second avoiding section 224 are arranged opposite to each other, and the first connecting section 221, the first avoiding section 223, the second connecting section 222 and the second avoiding section 224 are sequentially connected to form the second pipe section 22. In this embodiment, the first connecting section 221 and the second connecting section 222 are welded to the first connecting pipe 10 to ensure the connection strength between the first sleeve pipe 20 and the first connecting pipe 10, so as to prevent the first sleeve pipe 20 from being separated from the first connecting pipe 10 during the backflow of the exhaust gas.

[0043] In one embodiment, see Figure 2 The first connecting tube 10 is a circular tube, the first connecting section 221 and the second connecting section 222 are arc sections, and the first sleeve 20 is pressed onto the first connecting tube 10 by a tube pressing process to form the above-mentioned first connecting section 221 and the second connecting section 222.

[0044] Of course, there may be no connecting section between the first connecting pipe 10 and the first sleeve 20. A support frame is provided in the resonance cavity 30, one end of the support frame is connected to the first sleeve 20, and the other end of the support frame is connected to the first connecting pipe 10, so that the first sleeve 20 is supported by the support frame.

[0045] Furthermore, the inlet and outlet of the first sleeve 20 are spaced from the inlet of the second connecting pipe 40, which can reduce the noise generated when the exhaust gas flows. At the same time, the resonance cavity 30 and the pressure stabilizing cavity 60 cooperate to play the role of exhaust silencer and improve the sound quality of the muffler. In addition, the flow direction of the exhaust gas in the resonance cavity 30 is substantially parallel to the flow direction of the exhaust gas in the first connecting pipe 10, which can suppress the exhaust pressure wave and reduce energy loss.

[0046] In another embodiment, one end of the first sleeve 20 close to the second connecting pipe 40 is closed, and a vent is provided on the first connecting pipe 10, and the first connecting pipe 10 is connected to the resonance cavity 30 through the vent. The exhaust gas in the first connecting pipe 10 can enter the resonance cavity 30 from the vent, and the exhaust gas in the resonance cavity 30 can be discharged from the vent to the pressure stabilizing cavity 60. Specifically, the inlet end of the first sleeve 20 is welded to the first connecting pipe 10 to form a closed end, and the exhaust gas in the first connecting pipe 10 enters the resonance cavity 30 through the vent. When the pressure of the exhaust gas in the first connecting pipe 10 is high, the exhaust gas enters the resonance cavity 30 from the vent on the first connecting pipe 10, and when the pressure at the vent and the second connecting pipe 40 is low, the exhaust gas in the resonance cavity 30 flows out from the vent and flows to the pressure stabilizing cavity 60 and the second connecting pipe 40 in sequence to suppress the backflow of the exhaust gas.

[0047] In one embodiment, see Figure 1 , Figure 4 and Figure 5 The engine exhaust structure also includes a catalyst 70, which is disposed in the second sleeve 50 and located at the outlet of the second connecting pipe 40. The exhaust gas in the engine is discharged into the catalyst 70 through the first connecting pipe 10, the pressure stabilizing chamber 60 and the second connecting pipe 40, and the incompletely burned pollutants are converted into harmless substances to protect the environment.

[0048] Specifically, the second connecting tube 40, the catalyst 70 and the second sleeve 50 constitute a catalytic converter, and the second sleeve 50 is the outer tube of the catalytic converter. In order to firmly set the outer tube of the catalytic converter outside the first sleeve 20 and the second connecting tube 40, the outer tube of the catalytic converter is welded outside the first sleeve 20 and the second connecting tube 40. The outer tube of the catalytic converter is sleeved outside the first sleeve 20 and the second connecting tube 40 to form the above-mentioned pressure stabilizing cavity 60, so that there is no need to set up an independent chamber structure, reduce the number of parts, improve the appearance of the product, and reduce the manufacturing cost.

[0049] In addition, the inner diameter of the inlet of the second connecting pipe 40 is smaller than the diameter of the catalyst core 70 to play a flow interception role, thereby increasing the amount of exhaust gas flowing back into the resonance cavity 30. The increase in exhaust gas in the resonance cavity 30 can better suppress the backflow of exhaust gas and reduce the amount of backflow of exhaust gas, thereby further improving the charging efficiency and increasing the torque of the engine.

[0050] In one embodiment, the above-mentioned resonant cavity 30 is a quarter-wavelength resonant cavity 30. In addition to improving the torque of the engine, the quarter-wavelength resonant cavity 30 also has the function of eliminating low-frequency noise, which helps to reduce the acceleration noise of the motorcycle and improve the sound quality of the muffler. Specifically, the resonant cavity 30 can change the peak value of the reflected exhaust pressure wave, reduce the peak value of the exhaust pressure wave, and increase the trough of the exhaust pressure wave, so that the intensity of the change of the exhaust pressure wave is reduced, so that the amplitude of the pressure change is reduced, thereby achieving the purpose of noise reduction.

[0051] The above-mentioned engine exhaust structure can effectively curb the exhaust gas backflow phenomenon by changing the intake area of ​​the resonance cavity 30, the position of the first sleeve 20 (the axial length of the inlet of the first sleeve 20 from the inlet of the first connecting pipe 10 in the exhaust direction), the length of the resonance cavity 30 and the reasonable matching of the equivalent diameter, which helps to improve the engine's charging efficiency and thus increase the engine torque.

[0052] In one embodiment, see Figure 1 An engine includes a muffler and the above-mentioned engine exhaust structure, wherein the muffler is connected to the engine exhaust structure. A first sleeve 20 is sleeved outside the first connecting pipe 10 to form a resonance cavity 30; a second sleeve 50 is sleeved outside the first sleeve 20 and the second connecting pipe 40 to form a pressure stabilizing cavity 60. The pressure stabilizing cavity 60 is respectively connected to the first connecting pipe 10, the resonance cavity 30, and the second connecting pipe 40, and is the load boundary of the first connecting pipe 10, the resonance cavity 30, and the second connecting pipe 40, and directly affects the reflection of the exhaust pressure wave. Under the effect of the reflected exhaust pressure wave, when the exhaust gas in the second connecting pipe 40 flows backward into the first connecting pipe 10, the resonant cavity 30 can absorb some of the refluxed exhaust gas, thereby reducing the refluxed exhaust gas entering the first connecting pipe 10; when the first connecting pipe 10 exhausts forward to the second connecting pipe 40, the exhaust gas stored in the resonant cavity 30 is released and flows into the second connecting pipe 40, and at the same time, the exhaust gas in the pressure stabilizing cavity 60 also flows into the second connecting pipe 40, and the coordination of the resonant cavity 30 and the pressure stabilizing cavity 60 suppresses the backflow of the exhaust gas, reduces the backflow amount of the exhaust gas, thereby improving the charging efficiency and increasing the torque of the engine. Since the inlet size of the second connecting pipe 40 is smaller than the outlet size of the second connecting pipe 40, the second connecting pipe plays a role of interception, increasing the amount of exhaust gas flowing back into the resonant cavity 30, and the increase of exhaust gas in the resonant cavity 30 can better suppress the backflow of the exhaust gas, reduce the backflow amount of the exhaust gas, thereby further improving the charging efficiency and increasing the torque of the engine. In addition, the resonance cavity 30 can change the peak value of the reflected exhaust pressure wave, reduce the peak value of the exhaust pressure wave, and raise the trough of the exhaust pressure wave, so that the intensity of the change of the exhaust pressure wave is reduced, and the amplitude of the pressure change is reduced, thereby achieving the purpose of noise reduction.

[0053] In one embodiment, see Figure 1 A motorcycle includes the above engine. A first sleeve 20 is sleeved outside the first connecting pipe 10 to form a resonance cavity 30; a second sleeve 50 is sleeved outside the first sleeve 20 and the second connecting pipe 40 to form a pressure stabilizing cavity 60. The pressure stabilizing cavity 60 is connected to the first connecting pipe 10, the resonance cavity 30, and the second connecting pipe 40 respectively, and is the load boundary of the first connecting pipe 10, the resonance cavity 30, and the second connecting pipe 40, and directly affects the reflection of the exhaust pressure wave. Under the effect of the reflected exhaust pressure wave, when the exhaust gas in the second connecting pipe 40 flows backward into the first connecting pipe 10, the resonant cavity 30 can absorb some of the refluxed exhaust gas, thereby reducing the refluxed exhaust gas entering the first connecting pipe 10; when the first connecting pipe 10 exhausts forward to the second connecting pipe 40, the exhaust gas stored in the resonant cavity 30 is released and flows into the second connecting pipe 40, and at the same time, the exhaust gas in the pressure stabilizing cavity 60 also flows into the second connecting pipe 40, and the coordination of the resonant cavity 30 and the pressure stabilizing cavity 60 suppresses the backflow of the exhaust gas, reduces the backflow amount of the exhaust gas, thereby improving the charging efficiency and increasing the torque of the engine. Since the inlet size of the second connecting pipe 40 is smaller than the outlet size of the second connecting pipe 40, the second connecting pipe plays a role of interception, increasing the amount of exhaust gas flowing back into the resonant cavity 30, and the increase of exhaust gas in the resonant cavity 30 can better suppress the backflow of the exhaust gas, reduce the backflow amount of the exhaust gas, thereby further improving the charging efficiency and increasing the torque of the engine. In addition, the resonance cavity 30 can change the peak value of the reflected exhaust pressure wave, reduce the peak value of the exhaust pressure wave, and raise the trough of the exhaust pressure wave, so that the intensity of the change of the exhaust pressure wave is reduced, and the amplitude of the pressure change is reduced, thereby achieving the purpose of noise reduction.

[0054] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. An engine exhaust structure, characterized in that: include: a first connecting pipe, wherein an inlet of the first connecting pipe is used to be connected to an engine; A first sleeve, wherein one end of the first sleeve close to the engine is closed, and the first sleeve is sleeved outside the first connecting pipe to form a resonant cavity; a second connecting pipe, wherein an inlet of the second connecting pipe is arranged corresponding to an outlet of the first connecting pipe, and a size of the inlet of the second connecting pipe is smaller than a size of the outlet of the second connecting pipe; A second sleeve, the second sleeve is respectively sleeved outside the second connecting pipe and the first sleeve to form a pressure stabilizing cavity; wherein the exhaust gas discharged from the first connecting pipe can enter the resonant cavity, and the exhaust gas in the resonant cavity can be discharged into the pressure stabilizing cavity; The catalyst is arranged in the second sleeve and is located at the outlet of the second connecting tube. The inner diameter of the inlet of the second connecting tube is smaller than the diameter of the catalyst core.

2. The engine exhaust structure according to claim 1, characterized in that: The equivalent diameter of the pressure stabilizing cavity is larger than the diameter of the first connecting pipe, the equivalent diameter of the first sleeve, and the equivalent diameter of the second connecting pipe.

3. The engine exhaust structure according to claim 1 or 2, characterized in that: The length of the first connecting pipe is greater than that of the first sleeve, and the distance between an end surface of the first sleeve close to the second connecting pipe and an end surface of the outlet end of the first connecting pipe is 3 mm to 20 mm.

4. The engine exhaust structure according to claim 1 or 2, characterized in that: The distance between the outer surface of the first connecting pipe and the inner wall of the first sleeve is 2 mm to 15 mm.

5. The engine exhaust structure according to claim 1 or 2, characterized in that: The first sleeve includes a first pipe section and a second pipe section connected to each other. The second pipe section is arranged close to the second connecting pipe, and the equivalent diameter of the second pipe section is smaller than the diameter of the first pipe section.

6. The engine exhaust structure according to claim 5, characterized in that: The second pipe section includes a connecting section and an avoiding section, the connecting section is connected to the first connecting pipe, an inlet and an outlet are formed between the avoiding section and the first connecting pipe, and the pressure stabilizing cavity is connected to the resonant cavity through the inlet and the outlet.

7. The engine exhaust structure according to claim 1 or 2, characterized in that: One end of the first sleeve close to the second connecting pipe is closed, and a vent hole is provided on the first connecting pipe. The first connecting pipe is connected to the resonant cavity through the vent hole.

8. The engine exhaust structure according to claim 1 or 2, characterized in that: The resonant cavity is a quarter-wavelength resonant cavity.

9. An engine, characterized in that: The invention comprises a muffler and an engine exhaust structure according to any one of claims 1 to 8, wherein the muffler is connected to the engine exhaust structure.

10. A motorcycle, characterized in that: Comprising the engine as claimed in claim 9.

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