A turbocharger

Abstract

The present invention discloses a turbocharger, comprising a compressor and a turbine assembly; the compressor comprises a casing and an impeller; the impeller and the turbine of the compressor are coaxial; the casing comprises a casing and a compressor body, and the casing and the compressor body are configured as a detachable structure; the casing comprises an inner wall and an outer wall; the inner wall surface forms a through intake flow passage, and the outer wall is provided with at least one group of return flow openings that pass through the casing; the casing is partially inserted into the compressor body to form a compressor casing, and part of the outer wall of the casing forms an annular gap with the compressor body, and part of the air that is lifted to a predetermined pressure by the compressor impeller flows into the intake flow passage along the annular gap through the intake bypass port, thereby realizing a separate design of the compressor casing to ensure processing and the effect of improving the surge margin of the compressor.

Description

Technical Field

[0001] The present invention relates to the field of internal combustion engine turbochargers, and in particular to the field of turbochargers used in automobiles. Background Art

[0002] Turbocharging is a technology that uses exhaust gases from an internal combustion engine to drive an air compressor. Turbochargers are commonly installed in automotive engines. Their primary function is to increase the amount of air entering the engine, thereby boosting power and torque, making the vehicle more powerful. A turbocharged engine can increase its maximum power by 40% or more compared to a non-turbocharged engine. This means the same engine can deliver even greater power after being turbocharged.

[0003] In actual use, different flow rates at the same speed correspond to different outlet pressures. The lower the flow rate, the faster the outlet pressure rises, leading to surge and causing the compressor and engine to malfunction. Therefore, improving surge margin plays a vital role in engine operation stability. Casing treatment is a common method for improving surge margin. Conventional casing structures include the following: The casing treatment utilizes a 360° circumferential intake ring groove with circumferential ring groove structural ribs. The ring groove outlet is directly connected to the compressor inlet, and the ring groove inlet is a machined structure.

[0004] A 360° intake ring groove is not easy to manufacture, especially a narrow and long annular groove. Therefore, the injection molding process is mostly used for its molding. The groove molded in this way has structural ribs, which will cause serious throttling or disturbance of the airflow and lead to energy loss. The outlet of the ring groove is directly connected to the open inlet of the compressor assembly, which cannot eliminate the interference with the inlet flow, making the compressor body noisier or causing greater flow loss. The ring groove inlet formed by machining is difficult to manufacture, and it is difficult to adjust the size of the machining hole, and it is difficult to ensure uniform size and quality.

[0005] Therefore, in view of the above technical problems, it is urgent to develop a turbocharger to improve the surge margin and ensure the stable operation of the engine and compressor. Summary of the Invention

[0006] In view of the above-mentioned defects in the prior art, the technical problem to be solved by the present invention is how to ensure that the return flow passage of the compressor is unobstructed and surge does not occur.

[0007] To achieve the above-mentioned objectives, the present invention provides a turbocharger, comprising a compressor and a turbine assembly; the compressor comprises a casing and an impeller; the impeller of the compressor is coaxial with the turbine; the casing comprises a casing and a compressor body, and the casing and the compressor body are configured as a detachable structure; the casing comprises an inner wall and an outer wall; the inner wall surface forms a through intake flow channel, and the outer wall is provided with at least one group of return flow openings passing through the casing; the casing is partially inserted into the compressor body to form a compressor casing, and part of the outer wall of the casing forms an annular gap with the compressor body, and part of the air lifted to a predetermined pressure by the compressor impeller flows into the intake flow channel along the annular gap through the return flow channel.

[0008] Furthermore, the outer wall of the casing includes a protrusion, which is engaged with the assembly portion on the compressor body to form a sealed connection.

[0009] Furthermore, the casing forms an assembly annular gap with the compressor body at the most downstream end along the intake air flow.

[0010] Furthermore, the outer wall of the casing includes the annular return flow channel air outlet guide portion.

[0011] Furthermore, the guide portion is of a gradually expanding or curved type.

[0012] Furthermore, the outer wall of the casing inserted into the compressor body and constituting the annular bypass is formed by rotating a predetermined generatrix around a predetermined axis.

[0013] Furthermore, the turbine drives the impeller of the compressor to rotate via coaxial transmission, belt transmission or gear transmission.

[0014] Furthermore, the compressor body is injection molded, and / or the casing is machined or injection molded into a semi-finished product and then at least part of it is machined into a finished product.

[0015] Furthermore, the casing and the compressor body are connected by threaded connection, riveted connection or pin connection.

[0016] Furthermore, the fitting clearance between the casing and the compressor body is a circumferential clearance.

[0017] In a preferred embodiment of the present invention, the casing and the compressor body are configured as detachable separate structures, the casing and the compressor body are separately processed and formed, connected by plug-in, and the precision and size of the installation fit of each assembly part are ensured by the raised structure.

[0018] In another preferred embodiment of the present invention, the separately processed casing can be designed as a rotary structure, and at least the part inserted into the compressor body can be machined. This part can be composed of a rotating busbar. After assembly is completed, no turbulence effect will be formed inside the bypass ring groove. On the other hand, after assembly, an assembly gap entrance will be formed at the most downstream position in the air flow direction of the air flow channel.

[0019] The technical effect can ensure the processing accuracy. By using the assembly gap as the entrance, the gap size can be easily adjusted to adapt to different vehicle models. Finally, the outlet of the ring groove can be conveniently formed into a guide structure by machining. The air in the ring groove can be guided to the intake flow duct of the casing by the guide part with smaller turbulence loss, thereby compensating for the problem of low surge margin under low intake volume conditions.

[0020] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural diagram of a prior art turbocharger;

[0022] Figure 2 is an assembly structure diagram of a compressor housing in a turbocharger of the present invention;

[0023] Figure 3 This is a disassembled structural diagram of the compressor housing in the turbocharger of the present invention before assembly. DETAILED DESCRIPTION

[0024] The following describes several preferred embodiments of the present invention with reference to the accompanying drawings to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms of embodiments, and the scope of protection of the present invention is not limited to the embodiments mentioned herein.

[0025] In the drawings, components with identical structures are denoted by the same reference numerals, and components with similar structures or functions are denoted by similar reference numerals. The size and thickness of each component shown in the drawings are arbitrary and are not limited by the present invention. For clarity, the thickness of components in some places in the drawings is appropriately exaggerated.

[0026] like Figure 1 As shown in FIG. , it is a structural diagram of a conventional turbocharger, in which the turbine and the impeller are coaxial.

[0027] like Figure 2 and 3The figure shows the assembly diagram of the compressor housing in the turbocharger of the present invention and the disassembled structure diagram before assembly. The turbocharger is applied to automobiles to ensure that the air is inhaled by the action of the compressor during the exhaust process of the vehicle. In this embodiment, the combustion chamber is not shown, the turbine is connected to the exhaust duct of the combustion chamber, and the impeller and the turbine are coaxial. When the flue gas in the combustion chamber rushes towards the turbine at a certain angle, it drives the turbine to rotate, thereby driving the impeller of the compressor to rotate. The compressor also compresses the inhaled air and sends it into the combustion chamber. The turbine rotation speed will be different depending on the amount of flue gas generated by combustion. When the driving force of the flue gas generated by combustion is small, the rotation speed of the compressor is also low. Since the compressor housing in the present invention is composed of a detachable casing 2 and a compressor body 3, and the casing 2 and the compressor body are connected, the turbine housing is connected to the compressor body 3. After the body 3 is assembled, there is an impeller space 8 in the casing for installing the impeller. The position between the top and bottom ends of the impeller includes the annular gap 6 formed by the assembly of the casing 2 and the compressor body 3, so that the inhaled air completes partial pressurization. At this time, the partially pressurized air can be driven by the pressure difference between the intake bypass port 5 of the intake duct 1 of the casing 2 and the assembly gap 7 to flow back to the annular gap 6, and under the action of the guide part 4 in the annular gap 6, it can flow back to the intake duct 1 of the compressor casing 2 through the intake bypass port 5 of the casing 2. The bypass return flow nominally increases the intake volume of the compressor, and the nominally larger intake volume will reduce the surge risk of the compressor. On the other hand, since the boundary layer of the air flow joined by the partial return airflow is also improved, the surge margin of the compressor is enhanced.

[0028] Furthermore, the casing 2 and the compressor body 3 in this embodiment are detachably assembled by plugging together, and the two can be formed by separate processing. Especially for the casing 2 part, the definition of the split design size, etc. will be more precise, thereby ensuring production efficiency and production quality. The casing 2 part is machined or first formed into a semi-finished product by injection molding, and then machined into the finished casing 2. The machined casing 2 includes a protrusion, which is mainly used for positioning. The size of the insertion part of each batch production is guaranteed by machining. When the casing 2 is inserted into the compressor body 3, an assembly gap 7 will be generated due to the reservation during the assembly and processing of the two. The assembly gap 7 is the air inlet of the subsequent annular gap 6. The air inlet is formed by the split assembly gap 7, which can ensure that fine-tuning can be performed according to different vehicle models, thereby making the compressor suitable for a variety of vehicle models. On the other hand, in order to adapt to different requirements, the end of the casing can be formed into different structures or wavy shapes or other types.

[0029] Furthermore, in this embodiment, the portion where the casing 2 and the compressor body 3 are plugged in is at least formed by rotating the same busbar around the core shaft, which ensures the simplicity of machining. In addition, the plug-in portion adopts a busbar rotary structure design to ensure that there are no structural ribs inside the annular gap 6 formed by its cooperation with the compressor body 3. The rotary busbar can be designed as a tapered structure or other different structures. After the casing 2 and the compressor body 3 are inserted and connected, a sealed connection is formed, which can be sealed by a sealing ring or other means. In order to ensure the easy disassembly and connection reliability of the two, the two can be connected by threading, riveting or pinning, etc. Of course, other sealing connection methods are not excluded, such as expansion connection. When the size of the casing 2 is sufficient, a connecting flange can be added to ensure the reliability of the connection. When the size of the casing 2 is small, the casing 2 and the compressor body 3 are fixed by multiple screws, ensuring a universal solution for the compressor casing after assembly.

[0030] Furthermore, the casing 2 in this embodiment is formed with a through-intake bypass port 5, which is optimally a plurality of slots arranged at intervals formed by machine processing. Due to the split design, the return gas flows on part of the outer surface of the casing 2, and the outer surface to the intake bypass port can be easily machined to form a guide portion 4. The guide portion 4 can be a planar structure gradually inclined to the intake bypass port 5, or it can be formed into a streamlined curved surface structure. Due to the presence of the guide structure 4, the airflow can flow back to the intake duct 1 with less loss, which also increases the flow rate of the return gas and can maximize the surge margin of the compressor operation. The intake bypass port 5 cooperates with the guide structure 4 to transport the gas returned from the annular gap 6 to a position near the center of the intake duct 1, and the return airflow is aligned with the air flow direction of the intake duct 1 under the action of the guide portion, reducing the impact dissipation between the return gas and the intake air, which is very good for improving the surge margin of the compressor at a lower flow rate.

[0031] Furthermore, in order to better ensure the guiding effect of the guide part 4 on the return gas, the guide part 4 is machined into a gradual rotating plane structure or a rotating streamlined curved surface structure according to a streamlined design. The design mainly considers the speed of the air flow. Optimally, the guide part 4 obtains the best structure through CFD simulation technology. In order to better achieve the effect of the guide part 4, the annular gap 6 forms a gas collection part at the most downstream position along the flow direction of the return gas. The collection part has a certain chamber volume, and the volume is arranged in the flow direction of the return gas. The volume part is further downstream than the intake bypass port 5. This part of the volume mainly plays the role of adjusting and buffering the return air speed. Using CFD simulation technology, it is found that due to the existence of the buffer part, the return air will cooperate with the guide part 4 to achieve a return effect with less dissipation. This design further optimizes the return air volume and the return air mixing speed of the compressor, thereby achieving the effect of maximizing the compressor surge margin.

[0032] In this embodiment, the turbine and the compressor transmit the rotational energy of the turbine through a common shaft, but in actual use, other transmission methods can also be used, such as a pulley structure, a gear structure, a cam structure, etc. Different transmission structures can adapt to different requirements. For example, through optimization research on the combustion state of an actual automobile, it is found that there is a better relationship between the intake volume and the exhaust volume of the flue gas. The speed ratio of the two can be achieved through structures such as gears without changing the existing turbine and compressor impeller structures, thereby maximizing the cost of the turbocharger.

[0033] In this embodiment, the portion where the casing 2 and the compressor body 3 are plugged in is at least partially a cylindrical rotating surface, and the portion where the compressor body 3 and the casing 2 are plugged in and matched is also a cylindrical rotating surface. The two are plugged in to form a matching annular space, which can ensure the isotropic effect during the flow of the return gas. The intake annular gap 6 formed by the matching of the two is also a circumferential intake gap, which ensures the uniformity and consistency of the return gas intake.

[0034] In this embodiment, a compressor impeller is arranged in a compressor casing formed by plugging and connecting the casing 2 and the compressor body 3. Through surge margin curve analysis, the relationship between the minimum intake volume and the surge margin is analyzed and obtained. In order to improve the influence of the intake volume, the optimal intake pressure and optimal return flow rate of the return gas are calculated. The intake position of the annular gap 6 is obtained based on the flow rate. This design rule also guides the casing size design to ensure the relationship between the assembly gap 7 and the impeller position, thereby ensuring that the surge margin of the compressor is optimally improved.

[0035] For different vehicle models, combustion parameters and combustion conditions, the combustion chamber will affect the design of the turbocharger. In order to ensure the versatility of the structure, the starting point of the present invention is the surge margin curve, and then the size of the casing 2 is determined. The assembled compressor is coaxially connected to the turbine, and the air from the external environment can flow into the impeller through the intake duct of the compressor and be pressurized. Due to the existence of the intake annular gap 6, part of the air accelerated to a predetermined pressure flows back to the intake duct 1. The pressurized air ensures sufficient intake volume. The exhaust port of the compressor is connected to the combustion chamber of the engine. The pressurized air provides a sufficient oxidation environment for fuel combustion in the combustion chamber. The flue gas generated by the combustion flows to the intake port of the turbine, and realizes the propulsion of the turbine in the turbine volute, thereby generating rotational power. The flue gas passing through the outlet of the turbine can be discharged into the atmospheric environment, completing the whole process, and the energy generated by the combustion is used to drive the movement of the car's rotating shaft, thereby realizing the reliable operation of the engine and ensuring the power of the car.

[0036] The preferred embodiments of the present invention have been described in detail above. It should be understood that numerous modifications and variations based on the concepts of the present invention are possible without inventive effort by those skilled in the art. Therefore, any technical solution that can be derived by one skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. A turbocharger, characterized in that: The invention comprises a compressor and a turbine assembly; the compressor comprises a casing and an impeller; the impeller and the turbine of the compressor are coaxial; The housing includes a casing and a compressor body, and the casing and the compressor body are configured as a detachable structure; The casing includes an inner wall and an outer wall, the outer wall of the casing includes a protrusion, the protrusion is engaged with the assembly portion on the compressor body to form a sealed connection, the outer wall of the casing includes a guide portion, and the guide portion is a gradually expanding or curved type; The inner wall surface forms a continuous inlet flow channel, and the outer wall is provided with at least one set of return flow channels that penetrate the casing; The casing is partially inserted into the compressor body to form the compressor housing, and part of the outer wall of the casing forms an annular gap with the compressor body, and part of the air lifted to a predetermined pressure by the compressor impeller flows along the annular gap through the return flow channel into the intake flow channel, and the return flow channel is connected to the intake flow channel through an intake bypass port that penetrates, and a gas collection portion is formed at the most downstream position along the flow direction of the return gas through the annular gap, and the chamber volume of the gas collection portion is arranged with a volume portion downstream of the intake bypass port along the flow direction of the return gas, and the intake bypass port includes a plurality of slots arranged at intervals; the casing forms an assembly gap with the compressor body at the most downstream end along the intake flow; the assembly gap is the air inlet of the annular gap; the assembly gap is adjustable.

2. The turbocharger according to claim 1, wherein: The outer wall of the casing, which is inserted into the compressor body and forms an annular bypass, is formed by rotating a predetermined generatrix around a predetermined axis.

3. The turbocharger according to claim 1, wherein: The turbine drives the impeller of the compressor to rotate through a transmission mode of coaxial, belt or gear transmission.

4. The turbocharger according to claim 1, wherein: The compressor body is injection molded, and / or the casing is machined or injection molded into a semi-finished product and then at least partly machined into a finished product.

5. The turbocharger according to claim 1, wherein: The casing and the compressor body are connected by threaded connection, riveted connection or pinned connection.

6. The turbocharger according to claim 1, wherein: The matching clearance between the casing and the compressor body is a circumferential clearance.

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