64results about How to "Improve low-speed performance" patented technology

A hinged panel operation system is provided having a mechanical linkage assembly coupled between a fixed structure and a trailing edge device. The mechanical linkage assembly has a first link operatively coupled to the trailing edge device, a second link pivotably connected at a first end to the first link and pivotably connected at a second end to a third link, and an eccentric attachment connecting the second link to the third link. The hinged panel operation system further has a hinged panel positioned forward of the trailing edge device and being operatively coupled to the mechanical linkage assembly. The hinged panel is movable by the mechanical linkage assembly between a stowed position and a drooped position. The mechanical linkage assembly provides a load path to the hinged panel.

The invention discloses a vector control device for an induction motor and relates to a vector control device without speed sensor for the induction motor. The invention solves the problem of the vector control method of the conventional induction motor that a system is unstable in a low-speed power generation state and has a bigger rotating speed observation error under a low-speed condition because a rotating speed adaptive rate cannot guarantee the stability of an algorithm. In the invention, the speed of the motor can be observed by adding the exciting current error between the actual value and observed value of an exciting current and the product of a q axis stator magnetic chain observed value and a variable gain (M) into the general product of the observed current bias and the observed rotor magnetic chain and through a PI regulator; and thus, the speed of the motor can be controlled. The device reduces the low-speed performance of the system considerably and solves the unstable problem of the system in a power regeneration state effectively. The device is used for controlling the rotating speed of the induction motor.

The invention discloses a complex turbine device with a variable section, comprising a double flow channel turbine volute, wherein the double flow channel turbine volute is provided with two air flow passageways; the double flow channel turbine volute is provided with a volute air outlet and a volute air inlet which are communicated with the air flow passageways; a complex turbine impeller is arranged in the double flow channel turbine volute; and the complex turbine impeller is formed by compounding two turbine impellers which correspond to the two air flow passageways one by one. In the invention, the variable section function can be achieved by design and development of the turbine of a turbocharger and by using the complex turbine device, thereby effectively solving the defects of poor reliability and high cost of a vane type turbocharger with the variable section, effectively improving the efficiency of the turbine of an engine in low speed and increasing the torque output of the turbine.

The invention provides a thrust bearing, a rotor system and a control method of the thrust bearing. The thrust bearing comprises a thrust disc, a first stator and a second stator, wherein the thrust disc is fixed on a rotating shaft, and a first magnetic part is arranged on the thrust disc; the first stator and the second stator are arranged on the rotating shaft in a penetrating mode, and the first stator and the second stator are arranged on the two opposite sides of the thrust disc respectively; each stator comprises a magnetic bearing, a plurality of second magnetic parts are arranged on the magnetic bearing in the circumferential direction, bearing gaps are formed between the magnetic bearings and the thrust disc, and the thrust disc can move in the axial direction of the rotating shaft under the action of the magnetic force between the first magnetic part and the plurality of the second magnetic parts; and dynamic pressure generating grooves are formed in the thrust disc or the first stator and the second stator. According to the thrust bearing, the rotor system and the control method of the thrust bearing, bearing clearances and magnetic bearings are arranged in the thrust bearing, so that the thrust bearing forms gas and magnetic hybrid thrust bearings, the gas bearings and the magnetic bearings can work cooperatively, so that the dynamic performance and the stability of the thrust bearing under a high-speed running state can be improved.

The invention discloses a hydraulic control type device capable of eliminating pumping loss and improving the low-speed performance of a hydraulic retarder. The hydraulic control type device comprises a planetary gear train, a multi-piece brake, a multi-piece clutch, a case and a hydraulic control system which is used for controlling the multi-piece brake and the multi-piece clutch to be connected or separated. The planetary gear train comprises a planet carrier, a sun wheel, a gear ring and a plurality of planet gears, wherein the plurality of planet gears are evenly distributed between the sun wheel and the gear ring, meshed with the sun wheel and the gear ring respectively and installed on the planet carrier, the planet carrier is fixedly connected to an output shaft of a driven gear of a transmission, the sun wheel is fixedly connected to an input shaft of the hydraulic retarder, the multi-piece brake is disposed between the gear ring and the case, and the multi-piece clutch is arranged between the gear ring and the input shaft of the hydraulic retarder. The hydraulic control type device is capable of eliminating the pumping loss of the hydraulic retarder and improving the low-speed performance of the hydraulic retarder, has a little modification on existing hydraulic retarders and is simple in structure, convenient to use and reliable in work.

The invention provides a rotor system and a control method of the rotor system as well as a gas turbine generator set and a control method of the gas turbine generator set. The rotor system comprisesa rotating shaft, a generator, a gas compressor and a turbine as well as a thrust bearing and at least two radical bearings, wherein a shaft body of the rotating shaft is of an integrated structure and is horizontally arranged, the generator, the gas compressor and the turbine are sequentially arranged on the rotating shaft, the thrust bearing and the radial bearings are arranged on the rotating shaft, the thrust bearing and the radial bearings are non-contact bearings, and the thrust bearing is arranged at the position where the gravity center of the rotor system can be located between two radial bearings which are spaced by the largest distance. According to the rotator system, the shaft body of the rotating shaft in the rotor system is arranged into the integrated structure, so that theproblem that the installation position of a gas-magnetic hybrid thrust bearing is limited due to the fact that a coupling is used for connection in an existing gas turbine generator set is solved; and the arrangement position of the thrust bearing is adjusted, so that the gravity center of the whole rotator system is located between the two radial bearings which are arranged at the farthest distance, and the structure can be kept stable when the whole rotor system rotates at a high speed.

This refrigerating compressor comprises a sealed chamber delimiting a suction volume and a compression volume arranged respectively either side of a body contained in the chamber, and an oil injection circuit arranged to inject oil into the compression volume. The oil injection circuit comprises a moving blocking piece, operated by a centrifugal force, between a first position enabling oil injection into the compression volume and a second position preventing or limiting oil injection into the compression volume, the blocking piece being arranged to be displaced into its second position when the speed of the compressor exceeds a predetermined value.

The invention provides a subdivided signal error compensation method of a photoelectric encoder of a tracking control platform. The subdivided signal error compensation method is suitable for the tracking control platform which is formed by a main processor module, a storage module, a display module, a power module, an execution module, a controlled module, an photoelectric encoder measurement module, a communication interface module and a human-computer interaction module. The compensation is performed on the subdivided signal error of the encoder measurement module through the controlled object position of the tracking control platform. The practicability and the field adaptability are high and accordingly an expensive error detection device is not required and a large time delay of complex algorithm does not need to be brought to the platform. Meanwhile, only the shaft system position information needs to be obtained, the tracking control platform, an encoder angle measuring module and a lower layer of software and hardware structure of the platform do not need to be known, and accordingly the portable capability and the operational capability are high, the time and the labor are saved, and a good solution is provided for the encoder subdivided signal error problem which is common in the field of photoelectric tracking control platforms.

The invention discloses an air inlet duct suitable for a small jet unmanned aerial vehicle with a flying wing configuration. The air inlet duct is in a Y shape and is divided into air inlet shaping sections, diffusion sections, mergence sections and a shrinking rectifying section. Two air inlets are formed in the upper surface of a flying wing, and the lower edges of the air inlets and the front edge of the flying wing are overlapped. The air inlet shaping sections each are in a bell shape, and the outlet area is 90% smaller than the inlet area of each air inlet shaping section. The diffusionsections on the two sides are merged through the mergence sections after complete diffusion and subjected to shrinking rectifying through the shrinking rectifying section. Internal structure arrangement is facilitated. The double-side air inlet layout is adopted on the small unmanned aerial vehicle, electronic equipment can be easily arranged on a nose, and meanwhile vehicle trim is facilitated.

The invention discloses a sensorless controller of a bearingless synchronous reluctance motor and a method for controlling the sensorless controller. The sensorless controller consists of a current sampling and conversion unit, a least square support vector machine prediction model, a linear closed-loop controller, and two expanded current hysteresis pulse width modulation (PWM) inverters which are connected in parallel, wherein the current sampling and conversion unit acquires an output current and generates an input current of the least square support vector machine prediction model; the least square support vector machine prediction model respectively compares prediction radial displacement and a rotary speed, which are output, with given reference values to obtain difference values which serve as input signals of the linear closed-loop controller; and control current components of a suspension force winding and a torque winding which are generated by the linear closed-loop controller are input into the two current hysteresis PWM inverters to respectively generate the input currents of a system. By the invention, the bearingless synchronous reluctance motor can be steadily suspended in a sensorless mode in a full-speed range, and high anti-interference performance and high robustness are realized.

The invention provides a rotor system and a control method of the rotor system as well as a gas turbine generator set and a control method of the gas turbine generator set. The rotor system comprisesa rotating shaft, a motor, a gas compressor and a turbine as well as a thrust bearing and at least two radical bearings, wherein a shaft body of the rotating shaft is of an integrated structure, the rotating shaft is vertically arranged, the motor, the gas compressor and the turbine are sequentially arranged on the rotating shaft, the thrust bearing and the radial bearings are arranged on the rotating shaft, the thrust bearing and the radial bearings are non-contact bearings, the thrust bearing is arranged at a preset position of one side, close to the gas compressor, of the turbine, and the preset position is the position where the center of gravity of the rotator system can be located between the two radial bearings which are spaced by the largest distance. According to the rotator system, the non-contact type bearings are adopted so that the rotor system can be vertically arranged; and in this way, the gravity center of the rotator system is located at the axis, static deflection cannot be generated, moreover, the torque generated by the gravity on the axis is zero, therefore, the influence of the gravity on the rotation of the rotator system can be eliminated, and then the stability of the rotator system can be improved.

The invention provides an electromagnetically enabled active hydrodynamic gas-lubricated bearing. The electromagnetically enabled active hydrodynamic gas-lubricated bearing comprises an electromagnetic bearing (1) and an elastic foil bearing (3) nested between the electromagnetic bearing (1) and a rotor shaft (2), and is characterized in that the elastic foil bearing (3) comprises elastic top foil (31) and elastic bottom foil (32), the elastic top foil (31) is a non-magnetic material, and a plurality of mutually independent magnetic material areas are distributed on the surface of the elastic top foil (31). The electromagnetically enabled active hydrodynamic gas-lubricated bearing is simple in structure, has low requirement for precision, adopts a gas-magnetism mixed bearing structure, is provided with the adjustable magnetic flat foil and low-cost pressure sensors, and solves the problem that lubrication airflow leaks and is difficult to control due to low low-speed bearing capacity and bearing disturbance eccentricity during work of the conventional hydrodynamic gas-lubricated bearing.

A device and methods for low speed performance improvement of a lifting surface assembly (300) are disclosed. At least one vortex generator (308) is coupled to the lifting surface assembly, and the vortex generator is extended through the lifting surface assembly by drooping a hinged leading edge device (302) coupled to the lifting surface assembly to increase lift. The vortex generator is retracted inside the lifting surface assembly to decrease drag.

The invention discloses a multi-nozzle type variable flow rate supercharging device which comprises a volute casing, wherein the volute casing is internally provided with an air inlet and a volute air inlet passageway which is communicated with the air inlet, and the volute air inlet passageway is internally provided at least one intermediate baffle plate. The multi-nozzle type variable flow rate supercharging device provided by the invention has a simple air inlet regulating and controlling mechanism, the control mode is easy to realize, the reliability is high, and the problems of the existing vane type variable turbocharger in the aspects of reliability and efficiency and too low efficiency of a tongue shape baffle plate variable cross section charger are solved effectively.

The invention belongs to an air path control technology, and particularly relates to a fast pneumatic valve applied to air path control. The fast pneumatic valve comprises a valve body, a cone valve, electromagnetic valves, a separation plate and a gun barrel, wherein the cone valve and the separation plate are arranged in the valve body, a first air chamber is separated by a piston of the cone valve and the valve body, a valve head of the cone valve passes through the separation plate and can be matched with an opening of the gun barrel, a space among the cone valve, the separation plate and the valve body is a second air chamber, a third air chamber is formed between the separation plate and the valve body, in addition, the first air chamber is communicated with external atmosphere, and the third air chamber is communicated with a main air chamber used for emitting the gun barrel. Meanwhile, each air chamber is respectively provided with the electromagnetic valves used for controlling the air path closing. The fast pneumatic valve has the advantages that the cone valve movement is irrelevant to the work pressure, so the repeatability of the fast pneumatic valve is better, the speed precision of an air cannon device can be effectively improved, the piston lifting movement is smoother, the clamping cannot easily occur, and the low-speed capability of the air cannon device can be effectively improved.

An aircraft avian radar is implemented using multiple axial beam antennas mounted on an aircraft. Target range is determined by radar range. Target azimuth and elevation position is determined by triangulation. An end-fire array antenna composed of a series of monopole antenna elements enclosed inside a long thin protective cover fashioned in the form of a stall fence is mounted on the wings, tail, or fuselage to produce a low drag axial beam antenna pattern directed ahead of the aircraft. Other axial beam antenna choices include helical, pyramidal horn, and conical horn antennas mounted on or inside various forward facing surfaces of the aircraft.

The invention provides radial bearings, a rotor system and a control method of the radial bearings. Each radial bearing comprises a magnetic bearing, wherein the magnetic bearing is arranged on a rotating shaft in a sleeved mode, and a plurality of magnetic parts are arranged on the magnetic bearing in the circumferential direction; the magnetic bearing faces the side wall of the rotating shaft, and the rotating shaft is provided with a dynamic pressure generating groove facing the circumferential surface of the magnetic bearing; and a bearing gap is formed between the magnetic bearing and therotating shaft, and the rotating shaft can move in the radial direction of the rotating shaft under the magnetic action of the magnetic parts. According to the radial bearings, the rotor system and the control method of the radial bearings, bearing clearances and magnetic bearings are arranged in the radial bearings, so that the radial bearings form gas and magnetic hybrid radial bearings, the gas bearings and the magnetic bearings can work cooperatively, so that the dynamic performance and the stability of the radial bearings under a high-speed running state can be improved.

The invention provides a rotor system and a control method thereof and a gas turbine generator set and a control method thereof. The rotor system comprises a rotating shaft, a generator, a gas compressor, a turbine, a thrust bearing, two radial bearings, a first casing and a second casing; the shaft body of the rotating shaft is of an integrated structure, and the rotating shaft is horizontally arranged or vertically arranged; the generator, the gas compressor, the turbine, the thrust bearing and the two radial bearings are arranged on the rotating shaft, and the thrust bearing and the two radial bearings are non-contact bearings; the first casing is connected to the second casing; the generator, the thrust bearing and the two radial bearings are arranged in the first casing, and the gas compressor and the turbine are arranged in the second casing; and the impeller of the gas compressor is arranged close to the impeller of the turbine in the second casing. According to the system and the control method, the machining precision and assembly precision of the gas turbine generator set are reduced, the cost is reduced, and the gas turbine generator set is suitable for engineering batchproduction.

The invention discloses an electromagnetic control type air loss energy consumption removing and low-speed performance improving device for a hydrodynamic retarder. The device is connected between a transmission and the hydrodynamic retarder. The device comprises a planetary gear train, a magnetic powder type electromagnetic brake, a magnetic powder type electromagnetic clutch and a casing. The planetary gear train comprises a planet carrier, a sun gear, a gear ring and a plurality of planetary gears. The planetary gears are distributed between the sun gear and the gear ring evenly, meshed with the sun gear and the gear ring respectively and arranged on the planet carrier. The planet carrier is fixedly connected on a driven gear output shaft of the transmission, the sun gear is fixedly connected on a hydrodynamic retarder input shaft, the magnetic powder type electromagnetic brake is arranged between the gear ring and the casing, and the magnetic powder type electromagnetic clutch is arranged between the gear ring and the hydrodynamic retarder input shaft. The device can remove the air loss energy consumption of the hydrodynamic retarder and improve the low-speed performance of the hydrodynamic retarder and is simple in structure, convenient to use, low in cost, reliable in work and excellent in performance.

A fixed plane wave rider design method based on an osculating cone theory includes the following steps that (1), the relational expression shown in the patent among a wave rider front edge sweep backangle lambada, ICC and FCT is established; and (2), according to the relational expression obtained through the first step, the front edge of a wave rider is designated to be a straight line with thefixed chamber of lambada, one of ICC and FCT is given, in other words, delta1 or delta2 is known, distribution of delta1 or delta2 is obtained, and then the outline of the wave rider is generated through a traditional osculating cone method.

The invention discloses a turbine device with variable flows. The turbine device provided by the invention comprises a volute, wherein the volute is provided with an air inflow path; the air inflow path is internally provided with a separation wall and a mobile baffle with an arc-shaped cross section; the mobile baffle can axially move along the volute in the air inflow path; one end of the mobile baffle extends out from one side of the volute and is connected with a control device of the mobile baffle in a transmission mode; when the other end of the mobile baffle moves to the other side of the volute, the mobile baffle is used for dividing the volute into an internal volute flow path and an external volute flow path which are not communicated mutually; and the control device of the mobile baffle drives the mobile baffle to move upwards in the spanwise direction of the volute so as to change the flow allocation proportion of the internal volute flow path and the external volute flow path. The volute is simple in structure, good in inheritance, low in cost and easy to quickly realize engineering, and can be used for solving the problems in reliability and efficiency of the existing variable geometry turbine-compressor with a vaned nozzle and the problem of lower efficiency of a variable geometry compressor without a vaneless volute.

The invention discloses an improvement method for the low-speed performance of a permanent magnet synchronous motor, belonging to the field of high-performance servo control. The improvement method comprises the following steps: carrying out filtering pre-processing on the output of a speed calculation module by virtue of an improved Butterworth low-pass filter; establishing a composite PMSM mathematical model, and designing a general speed equation by the composite PMSM mathematical model; establishing a standard speed equation by the general speed equation; designing a disturbance observer with regard to the standard speed equation; adjusting the gain matrix L of the disturbance observer, correcting a lumped disturbance estimated value and compensating a speed PI adjustor through forward feedback to obtain final output. High-frequency noise components in the output of the calculation module are effectively filtered by the improved Butterworth low-pass filter, thus avoiding influence on the low-speed performance of the motor; the lumped disturbance is estimated through the disturbance observer and is subjected to forward feedback processing, so that not only can the influence of external disturbance be eliminated, but also the load torque item, the friction torque item and the inertia perturbation of the permanent magnet synchronous motor can be effectively processed, and the low-speed performance of the permanent magnet synchronous motor can be improved.

An apparatus forming an aircraft which is designed for flight by movement through the air, the aircraft has a front and rear portions and a center of mass, with left and right sides when divided by a central plane of reference. The aircraft has inboard portions closer to said central plane of reference and outboard portions farther from said central plane of reference. Further, the aircraft contains at least one positive lifting aerodynamic surface configured to affect the flow of air near said at least one positive lifting aerodynamic surface when said aircraft is appropriately moving forward, and at least one elevon structure configured to create negative aerodynamic force when said aircraft is appropriately moving forward. The elevon structure is constructed so as to have outboard portions thereof positioned outward of said central plane of reference to a distance at least three-fourths of the distance from said central plane of reference to a tip end of said at least one wing.

The invention relates to an indirect type matrix control system for an electricity-oil hybrid energy conversion electric driving ship. A three-phase alternating current diesel generating set is connected with an input end AC / DC converter of an indirect type matrix converter, a three-phase alternating current propulsion motor is connected with an output end DC / AC converter of the indirect type matrix converter, a virtual direct current link clamping circuit of the indirect type matrix converter is connected with a both-way PWM switch, the both-way PWM switch is connected with a power storage battery pack, a switch commutation controller is connected with switch control circuits of the input end AC / DC converter and the output end DC / AC converter of the indirect type matrix converter, a direct torque control frequency converter is connected with the switch commutation controller, the three-phase alternating current diesel generating set, the three-phase alternating current propulsion motor and a speed sensor, and a charger is connected with the power storage battery pack. By means of the indirect type matrix control system, efficient connection and parallel operation of alternating currents and direct currents can be achieved, and efficient and energy-saving frequency-conversion stepless speed-regulation control over the propulsion motor can be achieved.

The invention provides a tesla turbine and a control method. The tesla turbine comprises a rotating shaft, a shell, a plurality of discs, a thrust bearing and at least two radial bearings; the shell is arranged on the rotating shaft, and a medium inlet and a medium outlet are formed in the shell; the plurality of discs are arranged in the shell, the plurality of discs are fixedly connected to therotating shaft, a gap is formed between every two adjacent disks of the plurality of disks, and at least one exhaust hole is formed in each of the plurality of disks; and the thrust bearing and at least two radial bearings are arranged on the rotating shaft, and the thrust bearing and the at least two radial bearings are non-contact bearings. According to the tesla turbine, non-contact thrust bearings of the thrust bearing and the radial bearings are adopted, the power loss of the tesla turbine on the bearings is reduced, so that the efficiency of the tesla turbine is improved.

The invention belongs to the surface treatment technology for machine tool guide rails, and particularly relates to a micro-nano composite texture guide rail and a preparation method thereof. The micro-nano composite texture guide rail comprises a fixed guide rail and a sliding guide rail, the fixed guide rail is located below the sliding guide rail, and the sliding guide rail can do reciprocatingmotion relative to the fixed guide rail. Multiple micro-texture grooves perpendicular to the sliding direction are formed in the surface, in contact with the sliding guide rail, of the fixed guide rail, and the micro-texture grooves are arranged evenly in a staggered manner. Correspondingly, multiple nano-texture grooves perpendicular to the sliding direction are formed in the surface, in contactwith the fixed guide rail, of the sliding guide rail, and the nano-texture grooves penetrate through the surface of the sliding guide rail. According to the micro-nano composite texture guide rail, the micro-texture grooves perpendicular to the sliding direction are formed in the fixed guide rail of the guide rail, lubricating oil can be stored, and grinding scraps can be collected; and the nano-texture grooves perpendicular to the sliding direction are formed in the sliding guide rail, forming of a lubricating oil film is facilitated, and therefore the functions of enhancing lubricating, reducing friction and improving the performance of the guide rail are achieved.

A wide speed range electrical excitation doubly salient wind turbine generator belongs to a two-phase outer rotor doubly salient wind turbine generator which consists of an outer rotor (1), an inner stator (2), eight armature windings (A1, A2, A3, A4, B1, B2, B3, B4) which are wound on the stator, an excitation winding (L), and a winding diverter switch S. The four armature windings A1, A2, A3, and A4 in a stator slot are serially connected into an A phase, and the four armature windings B1, B2, B3, and B4 are serially connected into a B phase. The two-phase outer rotor doubly salient wind turbine generator can change the phase number of a motor through the diverter switch S to improve an adaptive speed range. The invention is applicable to a direct-drive wind turbine generating system of wide speed variations of a wind turbine.

A hinged panel operation system is provided having a mechanical linkage assembly coupled between a fixed structure and a trailing edge device. The mechanical linkage assembly has a first link operatively coupled to the trailing edge device, a second link pivotably connected at a first end to the first link and pivotably connected at a second end to a third link, and an eccentric attachment connecting the second link to the third link. The hinged panel operation system further has a hinged panel positioned forward of the trailing edge device and being operatively coupled to the mechanical linkage assembly. The hinged panel is movable by the mechanical linkage assembly between a stowed position and a drooped position. The mechanical linkage assembly provides a load path to the hinged panel.

The invention discloses a radial power rotor engine which has a structure that a compressed air surge chamber (2), a combustion chamber (3) and a rotor chamber (4) are formed in an engine shell (1), wherein an air compressor (13) is communicated with the combustion chamber (3) through the compressed air surge chamber (2) and a one-way valve (5), the combustion chamber (3) is connected with a fuel-injection apparatus (6) and a timing ignition device (7), and a puff port (8) of the combustion chamber (3) is communicated with the rotor chamber (4); the rotor chamber (4) is internally provided with a rotor (9) which consists of a rotor shaft (10) and rotor vanes (11), the rotor vanes (11) are homocentrically and circularly distributed on the rotor shaft (10) which is arranged on the engine shell (1), and the rotor shaft (10) is provided with the air compressor (13). The invention has the advantages of simple structure, few parts, easy manufacture, stable property and simple maintenance and can use various fuels.

The invention discloses an exhaust manifold and an exhaust system employing the same. The exhaust manifold comprises a plurality of exhaust branches, a first front end chamber, a second front end chamber, a precatalyst carrier, a first rear end chamber, a second rear end chamber and an exhaust front pipe, wherein the first rear end chamber is communicated with the first front end chamber, and the second rear end chamber is communicated with the second front end chamber. Airflow of the first front end chamber and the airflow of the second front end chamber pass through the precatalyst carrier, and then pass through the corresponding first rear end chamber and second rear end chamber respectively to reach the exhaust front pipe. In the invention, one part of waste gas exhausted by each of cylinders passes through the first front end chamber and the other part of waste gas passes through the second front end chamber and then the waste gas directly enters the precatalyst carrier, so a distance that the waste gas enters the precatalyst carrier is shortened; and then the waste gas passes through the first rear end chamber and the second rear end chamber respectively and then reaches the exhaust front pipe respectively, namely, a mode of 4-2-2-1 similarly. Therefore, the length of exhausting independently in the exhaust manifold is extended, mutual interference degree of the airflow among the cylinders is reduced obviously, and the low speed performance of an engine is improved.