A natural gas engine anti-surge system

Abstract

The present invention discloses a natural gas engine anti-surge system, comprising an exhaust manifold, an ERG cooler, an intercooler, a compressor, and a throttle. The system is characterized in that it includes a first anti-surge passage connecting the intercooler, the ERG cooler, and the exhaust manifold, wherein a first solenoid valve is provided on the first anti-surge passage. When the throttle opening decreases, the first solenoid valve is opened, thereby opening the first anti-surge passage and directing compressed gas between the compressor and the throttle to the exhaust manifold. The present invention prevents surge by directing compressed air between the compressor and the throttle, while effectively utilizing the energy of the directed compressed air and improving the efficiency of the turbocharger. The present invention can function within the full operating range of the engine. The present invention reduces the exhaust manifold temperature while avoiding surge.

Description

Technical Field

[0001] The present invention belongs to the technical field of engines, and in particular relates to an anti-surge system for a natural gas engine. Background Art

[0002] When the vehicle decelerates, the throttle opening of the natural gas engine decreases, and the gas pressure before the throttle becomes higher than the gas pressure at the compressor outlet. The gas after the compressor flows back, causing the turbocharger to surge.

[0003] The Chinese patent "Turbocharger Anti-Surge System," publication number CN104832221B, published on April 27, 2016, discloses a turbocharger anti-surge system comprising: a turbocharger having a turbine and a compressor interconnected; a first intake pipe, one end of which is connected to the exhaust port of an internal combustion engine; a flow mixing device, connected to the other end of the first intake pipe and connected to the turbine of the turbocharger; a first outlet pipe, one end of which is connected to the compressor of the turbocharger and the other end of which is connected to the intake port of the internal combustion engine; a second outlet pipe, one end of which is connected to the compressor of the turbocharger; a heat exchange device for exchanging heat with the internal combustion engine; a diverter valve having an inlet and an outlet, the inlet of which is connected to the other end of the second outlet pipe and the outlet of which is connected to the heat exchange device; and a second intake pipe, one end of which is connected to the heat exchange device and the other end of which is connected to the flow mixing device. This patent directs compressed gas between the compressor and the throttle valve into the exhaust manifold, thereby preventing surge, but the system does not function under the full operating range of the engine. It can play a role in the working condition where the compressed gas pressure between the compressor and the throttle is higher than the exhaust manifold pressure, but it cannot play a role in the working condition where the compressed gas pressure between the compressor and the throttle is lower than the exhaust manifold pressure.

[0004] Chinese patent application "An Engine Turbocharged Air Intake System," publication number CN204783371U, published on November 18, 2015, discloses an engine turbocharged air intake system comprising an air filter outlet steel pipe joint connected to the inlet side of a supercharger, and an intercooler outlet steel pipe joint connected to the exhaust side of the supercharger. The system also includes an anti-surge line, the anti-surge line comprising an anti-surge valve. The anti-surge valve is a three-way valve. A first passage of the anti-surge valve is connected to the intercooler outlet steel pipe joint, a second passage of the anti-surge valve is connected to the air filter outlet steel pipe joint, and a third passage of the anti-surge valve is connected to the engine's intake cylinder. Airflow enters the anti-surge valve from the first passage and flows through the second passage into the air filter outlet steel pipe joint and the third passage into the intake cylinder. Using this technical solution, when the vehicle decelerates, the large pressure difference between the inlet and exhaust sides of the supercharger can be dissipated, thereby avoiding wear and fatigue of the supercharger and extending its service life. This patent avoids turbocharger surge by routing compressed gas between the compressor and the throttle valve. However, its main disadvantage is reduced turbocharger efficiency. While routing compressed gas between the compressor and the throttle valve avoids turbocharger surge, the compressed gas's energy remains unutilized. Summary of the Invention

[0005] In view of the problems existing in the background technology, the purpose of the present invention is to provide a natural gas engine anti-surge system that can avoid turbocharger surge, utilize the energy of compressed gas between the compressor and the throttle, and function under all working conditions.

[0006] To achieve the above-mentioned objectives, the natural gas engine anti-surge system designed in the present invention includes an exhaust manifold, an ERG cooler, an intercooler, a compressor, and a throttle valve. The system is characterized in that it includes a first anti-surge passage connecting the intercooler, the ERG cooler, and the exhaust manifold, and a first solenoid valve is provided on the first anti-surge passage. When the throttle valve opening decreases, the first solenoid valve is opened, the first anti-surge passage is opened, and the compressed gas between the compressor and the throttle valve is discharged to the exhaust manifold.

[0007] Preferably, the first anti-asthma passage and the portion passing through the ERG cooler are independent passages.

[0008] Preferably, a first pipeline is provided between the intercooler and the ERG cooler, and a second pipeline is provided between the ERG cooler and the exhaust manifold.

[0009] Further preferably, the first solenoid valve is located on the first pipeline.

[0010] In order to further suppress surge, as a preferred solution, it also includes: a second anti-surge passage connecting the ERG cooler, the intercooler and the compressor; a second solenoid valve is provided on the second anti-surge passage; the first solenoid valve and the second solenoid valve are opened at the same time; the exhaust gas is guided through the ERG cooler and the intercooler to the front of the compressor by the second anti-surge passage.

[0011] Preferably, the second anti-surge passage and the portion passing through the intercooler are independent pipelines.

[0012] Preferably, a third pipeline is provided between the intercooler and the compressor, and a fourth pipeline is provided between the intercooler and the ERG cooler.

[0013] Further preferably, the second solenoid valve is located on the third pipeline.

[0014] The beneficial effects of the present invention are: the present invention prevents surge by guiding the compressed air between the compressor and the throttle valve, effectively utilizes the energy of the guided compressed air, and improves the efficiency of the turbocharger; the present invention can function within the full operating range of the engine; the present invention reduces the exhaust manifold temperature while avoiding surge. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a structural schematic diagram of the present invention, wherein: the thick solid line with an arrow is the high-temperature gas pipeline, the thin solid line with an arrow is the low-temperature gas pipeline, the dotted line with an arrow is the anti-surge pipeline, and the arrow indicates the flow direction of the gas.

[0016] In the figure: 1 first solenoid valve, 2 second solenoid valve, 3 EGR cooler, 4 intercooler, 5 turbine, 6 compressor, 7 EGR valve, 8 throttle valve, 9 mixer, 10 exhaust manifold, first pipeline 11, second pipeline 12, third pipeline 13, fourth pipeline 14. DETAILED DESCRIPTION

[0017] Below through Figure 1 The technical solutions of the present invention (including preferred technical solutions) are further described in detail by listing some optional embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0018] The exhaust gas from the natural gas engine is divided into two paths from the exhaust manifold 10. One path flows into the turbine 5 to perform work, and the other path is cooled by the EGR cooler 3, passes through the EGR valve 7, and enters the mixer 9. Air from the atmosphere enters the compressor 6 through the air filter (not shown) and is supercharged. It is then cooled by the intercooler 4 and passes through the throttle 8 to enter the mixer 9. After the fresh air and recirculated exhaust gas are mixed in the mixer 9, they enter the engine through the intake manifold (not shown). This part is prior art and will not be described in detail here. When the vehicle decelerates, the opening of the throttle 8 of the natural gas engine decreases, and the gas pressure at the inlet of the throttle 8 becomes higher than the gas pressure at the outlet of the compressor 6. If the engine operates in an area with limited surge margin, such as a low-speed and high-load area, the phenomenon of the gas pressure at the inlet of the throttle 8 being higher than the gas pressure at the outlet of the compressor 6 will induce compressor 6 surge.

[0019] like Figure 1 As shown, the natural gas engine anti-surge system designed by the present invention has a first pipeline 11 provided between the intercooler 4 and the ERG cooler 3, a second pipeline 12 provided between the ERG cooler 3 and the exhaust manifold 10, and a first solenoid valve 1 disposed on the first pipeline 1; a third pipeline 13 provided between the intercooler 4 and the compressor 6, and a fourth pipeline 14 provided between the intercooler 4 and the ERG cooler 3;

[0020] The first pipe 11 and the second pipe 12 are both connected to the ERG cooler 3 to form a first anti-surge passage, and they are independent of the previous high-temperature gas passage flowing into the ERG cooler 3. In other words, the ERG cooler 3 has two independent passages. The third pipe 13 and the fourth pipe 14 are both connected to the intercooler 3 to form a second anti-surge passage, and they are independent of the pressurized air passage entering the intercooler 4. In other words, the intercooler 4 has two independent passages. The first anti-surge passage and the second anti-surge passage are also independent of each other.

[0021] When the opening degree of the throttle valve 8 of the natural gas engine decreases, the first solenoid valve 1 and the second solenoid valve 2 will be opened at the same time.

[0022] After the first solenoid valve 1 opens, the gas between the compressor 6 and the throttle valve 8 first passes through the first solenoid valve 1, then enters the EGR cooler 3 for heating, and finally enters the exhaust manifold 10. (Natural gas engine anti-surge systems typically function in the low-speed, high-load region where surge margin is limited. During this period, the pressure of the gas between the compressor 6 and the throttle valve 8 is generally higher than the pressure in the exhaust manifold 10.) The gas between the compressor 6 and the throttle valve 8 is directed to the exhaust manifold 10, preventing compressor surge and reducing the temperature of the exhaust manifold 10.

[0023] After the second solenoid valve 2 opens, exhaust gas from exhaust manifold 10, cooled by EGR cooler 3, partially passes through EGR valve 7 and enters mixer 9. The remaining portion, after being cooled by intercooler 4, passes through solenoid valve 2 and enters the inlet of compressor 6. Exhaust gas from exhaust manifold 10 is directed to the inlet of compressor 6. This firstly reduces the pressure ratio between the outlet and inlet gas of compressor 6, preventing surge. Secondly, it lowers the exhaust pressure of exhaust manifold 10, facilitating the flow of gas between compressor 6 and throttle valve 8 to exhaust manifold 10. Finally, it reduces the exhaust energy of exhaust manifold 10, which, on the one hand, reduces turbocharger power. As turbocharger power decreases, the pressure ratio between the outlet and inlet gas of compressor 6 also decreases, and, on the other hand, reduces the temperature of exhaust manifold 10.

[0024] The purpose of diverting the compressed gas between the compressor 6 and the throttle valve 8 is to prevent surge. The primary purpose of diverting the exhaust gas is to reduce the pressure in the exhaust manifold 10, facilitating the entry of the compressed gas between the compressor 6 and the throttle valve 8 into the exhaust manifold. A secondary purpose is to suppress surge by increasing the inlet pressure of the compressor 6 and reducing the compressor 6 pressure ratio. Furthermore, it also serves to reduce the temperature of the exhaust manifold 10. Diverting the compressed gas between the compressor 6 and the throttle valve 8 into the exhaust manifold 10 compensates for the energy loss caused by diverting the exhaust gas and simultaneously reduces the exhaust manifold temperature.

[0025] It will be easily understood by those skilled in the art that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, combinations, replacements, improvements, etc. made within the spirit and principles of the present invention are included in the scope of protection of the present invention.

Claims

1. A natural gas engine anti-surge system, comprising an exhaust manifold, an ERG cooler, an intercooler, a compressor, and a throttle, characterized in that: It also includes a first anti-surge passage connecting the intercooler, ERG cooler and exhaust manifold, and a first solenoid valve is provided on the first anti-surge passage; a second anti-surge passage connecting the ERG cooler, intercooler and compressor; a second solenoid valve is provided on the second anti-surge passage; when the throttle opening decreases, the first solenoid valve is opened, the first anti-surge passage is opened, and part of the compressed gas between the compressor and the throttle is discharged through the ERG cooler to the exhaust manifold; and at the same time, the second solenoid valve is opened, and the exhaust gas passing through the ERG cooler and intercooler is discharged to the front of the compressor through the second anti-surge passage.

2. The natural gas engine anti-surge system according to claim 1, characterized in that: The first anti-stomach passage and the portion passing through the ERG cooler are independent passages.

3. The natural gas engine anti-surge system according to claim 1 or 2, characterized in that: A first pipeline is provided between the intercooler and the ERG cooler, and a second pipeline is provided between the ERG cooler and the exhaust manifold.

4. The natural gas engine anti-surge system according to claim 3, characterized in that: The first solenoid valve is located on the first pipeline.

5. The natural gas engine anti-surge system according to claim 1, characterized in that: The second anti-surge passage and the portion passing through the intercooler are independent pipelines.

6. The natural gas engine anti-surge system according to claim 1 or 5, characterized in that: A third pipeline is provided between the intercooler and the compressor, and a fourth pipeline is provided between the intercooler and the ERG cooler.

7. The natural gas engine anti-surge system according to claim 6, characterized in that: The second solenoid valve is located on the third pipeline.

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