An opposed piston two-stroke engine

Abstract

The present invention discloses an opposed-piston two-stroke engine, comprising a cylinder, an intake-side piston and an exhaust-side piston disposed within the cylinder; an EGR input port, an external air inlet, an EGR output port, and an exhaust gas outlet are disposed circumferentially on the cylinder from the intake side to the exhaust side; an intercooler is connected to the EGR output port via a pipeline, allowing exhaust-side EGR to be input to the intake side; the external air inlet inputs air into the cylinder; the exhaust gas outlet discharges exhaust gas from the cylinder; a main combustion chamber injector and a pre-combustion chamber are disposed between the external air inlet and the EGR output port. In this application, the EGR input port is disposed radially of the cylinder, and the external air inlet is disposed tangentially to the cylinder inner wall, forming a stratified scavenging structure with EGR along the cylinder axis and ambient air, allowing EGR to be discharged instead of fresh air, thereby achieving control of the oxygen concentration in the exhaust gas.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal engines, in particular to an opposed-piston two-stroke engine. Background Art

[0002] The cylinder of an opposed-piston two-stroke engine is enclosed by two opposing pistons, offering advantages such as low specific mass, simple structure, high power, and high torque. Furthermore, the lack of a cylinder head reduces heat and friction losses, giving opposed-piston two-stroke engines high thermal efficiency. Furthermore, the opposed piston layout results in relatively low vibration. Compared to compression-ignition engines, spark-ignition engines offer lower mass, lower cost, and gentler operation, making them particularly suitable for land transportation and other applications.

[0003] To achieve optimal ventilation, two-stroke engines typically use an excess of fresh air for scavenging, resulting in a significant amount of unused oxygen in the exhaust. However, the most efficient and universal aftertreatment method for spark-ignition engines is the use of a three-way catalyst for the catalytic oxidation and reduction of unburned hydrocarbons, carbon monoxide, and nitrogen oxides. However, efficient reduction of nitrogen oxides requires extremely low oxygen levels, creating an irreconcilable conflict with the scavenging and combustion processes of a two-stroke engine. Summary of the Invention

[0004] In order to address the deficiencies in the prior art, the present invention designs an opposed-piston two-stroke engine. By optimizing the structure of the scavenging duct, a stratified scavenging structure of cylinder axis EGR and peripheral air is formed, and EGR is discharged instead of air, thereby achieving control of the oxygen concentration in the exhaust gas.

[0005] An opposed piston two-stroke engine comprises a cylinder,

[0006] an intake-side piston and an exhaust-side piston respectively disposed in the cylinder;

[0007] An EGR input port, an external air inlet, an EGR output port, and an exhaust gas outlet are sequentially arranged along a circumferential direction on the cylinder from the intake side to the exhaust side; the EGR output port and the EGR input port are connected to an intercooler via a pipeline to input the exhaust side EGR into the intake side; the external air inlet inputs air into the cylinder; and the exhaust gas outlet discharges the exhaust gas out of the cylinder;

[0008] A main combustion chamber injector and a pre-combustion chamber are arranged between the external air inlet and the EGR output port.

[0009] Furthermore, a scavenging passage I is arranged around the cylinder in the circumferential direction, and a plurality of scavenging ports I are arranged circumferentially between the scavenging passage I and the cylinder. The scavenging ports I are EGR input ports, and the EGR input ports are arranged along the radial direction of the cylinder.

[0010] Furthermore, an exhaust passage I is provided around the cylinder in a circumferential direction, and a plurality of exhaust ports I are provided circumferentially between the exhaust passage I and the cylinder, wherein the exhaust ports I are EGR output ports.

[0011] Furthermore, the scavenging passage I is connected to the intercooler through a cooling EGR conduit, and the exhaust passage I is connected to the intercooler through an intercooler inlet conduit.

[0012] Furthermore, a scavenging duct II is arranged around the circumference of the cylinder, and a plurality of scavenging ports II are arranged circumferentially between the scavenging duct II and the cylinder; the scavenging ports II are external air inlets; and the scavenging ports II are arranged tangentially along the inner wall of the cylinder.

[0013] Furthermore, the scavenging port II is connected to the supercharger to input air into the cylinder. Furthermore, an exhaust duct II is arranged around the cylinder, and a plurality of exhaust ports II 11 are arranged circumferentially between the exhaust duct II and the cylinder; the exhaust ports II are exhaust gas outlets.

[0014] Furthermore, the exhaust port II is connected to an exhaust gas treatment device.

[0015] Furthermore, the pre-combustion chamber includes a spark plug and a pre-combustion chamber injector, and the spark plug and the pre-combustion chamber injector are arranged toward the pre-combustion chamber inner cavity of the pre-combustion chamber.

[0016] Furthermore, the main combustion chamber injector and the pre-combustion chamber are arranged opposite to each other along the radial direction of the cylinder.

[0017] Beneficial effects

[0018] (1) The present invention forms a stratified scavenging structure of cylinder axis EGR and peripheral air by regulating scavenging in layers, and exhausts EGR instead of fresh air, thereby achieving control of the oxygen concentration in the exhaust gas, thereby achieving efficient conversion conditions for NOx by the three-way catalyst and significantly reducing NOx emissions.

[0019] (2) The present invention realizes the introduction of EGR without affecting the scavenging process of the opposed-piston two-stroke engine, thereby reducing the combustion temperature in the cylinder and reducing the amount of NOx generated from the source.

[0020] (3) The present invention adopts a pre-combustion chamber jet ignition method in an opposed piston two-stroke engine, thereby improving the combustion stability of the engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the implementation cases and technical solutions of the present invention, the following briefly introduces and explains the drawings required for the implementation plans.

[0022] Figure 1 This is a cylinder structure diagram of the spark-ignition two-stroke engine described in the present invention.

[0023] Figure 2 The figure is a schematic diagram of the axial gas flow during the scavenging process of the spark-ignition two-stroke engine according to the present invention.

[0024] Figure 3 Schematic diagram of gas flow and distribution in radial cross-section at four positions: EGR inlet, air inlet, cylinder center, and exhaust hole during the scavenging process of the spark-ignition two-stroke engine according to the present invention.

[0025] Figure 4 This is the internal structure diagram of the pre-combustion chamber of the spark-ignition two-stroke engine of the present invention

[0026] Description of reference numerals:

[0027] 1-Intake side piston; 2-Exhaust side piston; 3-Exhaust side crankcase; 4-Intake side crankcase; 5-Scavenging port I; 6-Scavenging port II; 7-Main combustion chamber injector; 8-Exhaust channel I; 9-Exhaust channel II; 10-Exhaust port I; 11-Exhaust port II; 12-Scavenging channel I; 13-Scavenging channel II; 14-Precombustion chamber; 15-Intercooler inlet duct; 16-Intercooler; 17-Cooling EGR duct; 18-External air; 19-Exhaust gas; 20-Hot exhaust gas in the cylinder; 21-Air in the cylinder; 22-Cooling EGR; 23-Spark plug; 24-Precombustion chamber injector; 25-Precombustion chamber inner cavity; 26-Precombustion chamber jet hole. DETAILED DESCRIPTION

[0028] The technical solution of the present invention is described below with reference to the implementation examples in the accompanying drawings. This implementation example is only a partial implementation example of the present invention and does not represent all feasible solutions. Based on this implementation example, other implementation examples obtained by ordinary technicians in this field without further innovative work are all within the scope of protection of the present invention.

[0029] This case provides an opposed-piston two-stroke engine, including a cylinder, with an intake-side crankcase 4 and an exhaust-side crankcase 3 at the left and right ends of the cylinder respectively; an intake-side piston 1 is arranged in the intake-side crankcase 4, and an exhaust-side piston 2 is arranged in the exhaust-side crankcase 3.

[0030] From the intake side to the exhaust side, the scavenging duct I 12, the scavenging duct II 13, the exhaust duct I 8 and the exhaust duct II 9 are sequentially installed on the outside of the cylinder; among them, the scavenging duct I 12 is connected to the intercooler 16 through the cooling EGR conduit 17, and the exhaust duct I 8 is connected to the intercooler 16 through the intercooler inlet conduit 15. The hot exhaust gas 20 in the cylinder on the exhaust side can be input into the intercooler 16 for cooling and then input to the intake side.

[0031] More specifically, five scavenging ports I5 are circumferentially arranged between the scavenging passage I12 and the cylinder. The scavenging ports I5 are EGR input ports. The EGR input ports are arranged radially along the cylinder. The hot exhaust gas 20 in the cylinder treated by the intercooler 16 enters the cylinder radially from the scavenging ports I5 and moves along the axis toward the exhaust side in the cylinder. Figure 3 shown.

[0032] More specifically, a scavenging duct II 13 is arranged around the circumference of the cylinder, and five scavenging ports II 6 are arranged circumferentially between the scavenging duct II 13 and the cylinder. The scavenging duct II 13 is connected to the supercharger, which inputs air into the scavenging duct II 13. The air in the scavenging duct II 13 enters the cylinder through the scavenging ports II 6. All scavenging ports II 6 are arranged tangentially along the inner wall of the cylinder and face the same direction. Therefore, the air entering the cylinder through the scavenging ports II 6 forms a radial rotating flow. Under the action of centrifugal force, it rotates along the wall and slowly moves toward the exhaust side. Figure 3 shown.

[0033] More specifically, an exhaust duct I8 is provided around the cylinder circumference, and five exhaust ports I10 are provided circumferentially between the exhaust duct I8 and the cylinder. The exhaust ports I10 are EGR outlets. The exhaust ports I10 are provided along the radial direction of the cylinder and guide the hot exhaust gas 20 in the cylinder from the intercooler inlet duct 15 to the intercooler 16. Figure 3 shown.

[0034] More specifically, an exhaust passage II 9 is provided around the cylinder circumference, and five exhaust ports II 11 are provided circumferentially between the exhaust passage II 9 and the cylinder; the exhaust ports II 11 are exhaust gas outlets, such as Figure 3 shown.

[0035] More specifically, the main combustion chamber injector 7 and the pre-combustion chamber 14 are arranged between the scavenging passage II 13 and the exhaust passage I 8, and the main combustion chamber injector 7 and the pre-combustion chamber 14 are arranged opposite to each other along the radial direction of the cylinder; Figure 4 As shown, the pre-combustion chamber 14 includes a spark plug 23 and a pre-combustion chamber injector 24 , which are arranged toward a pre-combustion chamber inner cavity 25 of the pre-combustion chamber 14 .

[0036] The following describes in detail the working process of the cylinder of an opposed piston two-stroke engine of the present invention. Figure 1 and Figure 2 As shown, when the intake side piston 1 and the exhaust side piston 2 run in opposite directions to the late stage of the power stroke, the exhaust port I10 is connected to the cylinder, and the hot exhaust gas 20 in the cylinder enters the intercooler 16 through the exhaust passage I8 and the intercooler inlet duct 15 for cooling.

[0037] At the same time, or later, the scavenging port II6 is connected to the outside through the scavenging passage II13, and the external fresh air 18 is pressed into the cylinder by the supercharger. Figure 3As shown, the radial cross-section of the scavenging port II6 is spiral, so that a radial rotating airflow is formed in the cylinder. The cylinder air 21 entering the cylinder rotates along the wall under the action of centrifugal force and slowly moves toward the exhaust side.

[0038] When the intake side piston 1 and the exhaust side piston 2 continue to move to the sides, the exhaust port II 11 is connected to the cylinder, and the hot exhaust gas 20 in the cylinder enters the exhaust gas treatment device through the exhaust port II 11 and the exhaust passage II 9.

[0039] At the same time, or later, the scavenging port I5 is connected to the intercooler 16 through the scavenging passage I12, and the cooled EGR22 in the intercooler 16 enters the cylinder through the scavenging port I5. Figure 3 As shown, the radial cross-section of the scavenging port I5 is a straight cylinder, so that the cooling EGR22 entering the cylinder converges at the center and moves toward the exhaust side along the cylinder axis.

[0040] Due to the flow direction and the external supercharger, the axial movement speed of the cooling EGR 22 is greater than the axial movement speed of the in-cylinder air 21 , and the cooling EGR 22 reaches the exhaust side before the in-cylinder air 21 .

[0041] Finally, the bottom dead center is formed. Figure 2 and Figure 3 The airflow structure shown in the figure. In the cylinder main body area, the cylinder air 21 surrounds the cooled EGR 22, and there is no fresh air or less fresh air on the exhaust side. Compared with conventional two-stroke engines, the cooled EGR 22 replaces the cylinder air 21 and is discharged out of the cylinder, achieving controllable exhaust oxygen concentration.

[0042] During the compression process, the fresh air 21 in the cylinder is pressed into the pre-combustion chamber 14 and forms a mixed gas with a low EGR rate.

[0043] Then, the main combustion chamber injector 7 injects fuel into the main combustion chamber, forming a uniform mixture of fresh air, cooled EGR and fuel in the cylinder.

[0044] When compression is nearing the end, the pre-combustion chamber injector 24 in the pre-combustion chamber 14 sprays fuel into the inner cavity of the pre-combustion chamber 25, and is ignited by the spark plug 23. The combustion flame is sprayed into the main combustion chamber through the pre-combustion chamber jet hole 26, igniting the mixture in the main combustion chamber.

[0045] It should be noted that the present invention is not limited to the exemplary case details described above. Without violating the basic characteristics of the present invention and the effects produced in its field of application, the present invention may be expressed in a variety of forms and may be implemented in other specific solutions and forms. Therefore, all variations within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention.

[0046] This specification uses specific examples to illustrate the present invention, and the above examples are only used to understand the technical core of the present invention. The content of this specification should not be understood as limiting the present invention.

Claims

1. An opposed-piston two-stroke engine, characterized in that: Including cylinder, An intake side piston (1) and an exhaust side piston (2) are respectively arranged in the cylinder; From the intake side to the exhaust side, a scavenging passage I (12), a scavenging passage II (13), an exhaust passage I (8) and an exhaust passage II (9) are sequentially provided in a circumferential direction on the cylinder; A plurality of scavenging ports I (5) are provided along the circumferential direction between the scavenging passage I (12) and the cylinder, wherein the scavenging ports I (5) are EGR input ports, and the EGR input ports are provided along the radial direction of the cylinder; A plurality of scavenging ports II (6) are provided along the circumferential direction between the scavenging passage II (13) and the cylinder, and the radial cross section of the scavenging ports II (6) is spiral; the scavenging ports II (6) are external air inlets for inputting air into the cylinder; the scavenging ports II (6) are provided along the tangential direction of the inner wall of the cylinder; A plurality of exhaust ports I (10) are provided circumferentially between the exhaust duct I (8) and the cylinder, wherein the exhaust ports I (10) are EGR output ports; the exhaust duct I (8) is connected to the intercooler (16) via an intercooler inlet conduit (15); the intercooler (16) is connected to the scavenging duct I (12) via a cooling EGR conduit (17); The axial movement speed of the cooling EGR (22) is greater than the axial movement speed of the in-cylinder air (21), and the cooling EGR (22) reaches the exhaust side before the in-cylinder air (21); Exhaust duct II (9) discharges exhaust gas out of the cylinder; A main combustion chamber injector (7) and a pre-combustion chamber (14) are arranged between the external air inlet and the EGR output port.

2. An opposed-piston two-stroke engine according to claim 1, characterized in that: The scavenging port II (6) is connected to the supercharger to input air into the cylinder.

3. An opposed-piston two-stroke engine according to claim 1, characterized in that: An exhaust duct II (9) is arranged around the cylinder in the circumferential direction, and a plurality of exhaust ports II (11) are arranged between the exhaust duct II (9) and the cylinder in the circumferential direction; the exhaust ports II (11) are exhaust gas outlets.

4. An opposed-piston two-stroke engine according to claim 3, characterized in that: The exhaust port II (11) is connected to an exhaust gas treatment device.

5. An opposed-piston two-stroke engine according to claim 1, characterized in that: The pre-combustion chamber (14) comprises a spark plug (23) and a pre-combustion chamber injector (24), and the spark plug (23) and the pre-combustion chamber injector (24) are arranged toward the pre-combustion chamber inner cavity (25) of the pre-combustion chamber (14).

6. An opposed-piston two-stroke engine according to claim 5, characterized in that: The main combustion chamber injector (7) and the pre-combustion chamber (14) are arranged opposite to each other along the radial direction of the cylinder.

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