RU2796710C2 - Exhaust system for engine - Google Patents

Abstract

FIELD: mechanical engineering; snowmobiles.

SUBSTANCE: snowmobile contains a frame, a ski, an engine, an exhaust pipe, a turbocharger. Snowmobile, according to the first variant, where the bypass pipe contains an inlet, hydraulically connected to the outlet pipe. The valve is configured to selectively move between the first and second positions. The snowmobile, according to the second version, includes a bypass pipe hydraulically connected to the outlet of the exhaust pipe. The valve has a bypass position to bypass the turbine. The turbocharger unit for hydraulic connection with the exhaust pipe includes a turbo heater containing a turbine, a housing, a bypass pipe. The bypass branch pipe contains the inlet opening of the branch pipe, the bypass passage, the passage of the turbo-heater. The bypass passage forms a hydraulic connection between the nozzle inlet and the bypass outlet defined by the bypass nozzle. The turbocharger assembly, according to the first variant, in which the nozzle inlet is defined by the bypass pipe and defines the flow axis through the center of the nozzle inlet. The bypass pipe contains a valve made with the possibility of selective movement between open and closed positions. The turbocharger assembly, according to the second embodiment, in which the exhaust pipe contains a turbocharger inlet defined by the turbine. The bypass contains an opening. The turbocharger passage forms a hydraulic connection between the manifold inlet and the turbocharger inlet. The branch pipe for hydraulic connection with the turbocharger housing contains the inlet part of the branch pipe, the inlet opening, the first and second inlet parts of the branch pipe, a flow divider.

EFFECT: increased efficiency of fuel consumption.

22 cl, 36 dwg

Description

cross reference

[001] This application claims priority over U.S. Provisional Application No. 62/678,922, filed May 31, 2018, and U.S. Provisional Application No. 62/783,576, filed December 21, 2018, both of which are fully incorporated herein by reference.

The field of technology to which the invention belongs

[002] The proposed technology relates to engine exhaust systems.

State of the art

[003] For internal combustion engines, such as those used in snowmobiles, the efficiency of the combustion process can be increased by compressing the air entering the engine. This can be done with a turbocharger connected to the snowmobile's air intake and exhaust systems. The compression of air by a turbocharger can be of particular importance when an internal combustion engine is operating in environments with low atmospheric pressure or when the air becomes thinner, such as when the engine is operating at high altitudes.

[004] However, the efficiency and performance of some engines, especially two-stroke engines, can under certain circumstances be reduced by the presence of a turbocharger due to the increased amount of back pressure generated by the turbocharger. Two-stroke engines tend to be especially sensitive to sub-optimal levels of back pressure.

[005] Thus, there is a need for exhaust systems for internal combustion engines that can benefit from the addition of a turbocharger while overcoming some of the previously known disadvantages of incorporating a turbocharger, including, for example, problems associated with back pressure.

Disclosure of the essence of the invention

[006] The purpose of the proposed technology is to eliminate at least some of the shortcomings that exist in the prior art.

[007] According to one aspect of the proposed technology, a snowmobile is provided that includes an exhaust system that includes a turbocharger and a valve that controls the flow of exhaust gas to the turbocharger. Said valve, located in a pipe integrally connected to or attached to the turbocharger housing, directs the exhaust gas to the exhaust gas turbine of the turbocharger and/or allows the exhaust gas to flow through the bypass pipe (bypassing the turbocharger). The backpressure flowing into the turbocharger is generally higher than the intake pressure of the exhaust gas entering the wastegate, so that the exhaust gas will generally flow into the wastegate bypassing the turbocharger when the valve is open. The exhaust pipe hydraulically connected to the engine, the bypass pipe and the exhaust gas manifold hydraulically connected to the muffler are generally aligned so that the exhaust gas, bypassing the exhaust gas turbine, flows generally freely, minimizing back pressure.

[008] The proposed technology also provides ways to control the flow of exhaust gas through the exhaust system to provide the engine with additional air (and power) through the use of a turbocharger in certain scenarios. These methods also strike a balance between rapidly providing additional power and creating a delay in increasing power due to the creation of backpressure. The position of the valve controlling flow to or bypass the turbo is adjustable to supply more or less exhaust gas to the turbo, depending on various parameters, to both increase the amount of air into the engine and limit the detrimental effects of increased back pressure on engine performance. The valve divides the exhaust gas flow into two passages with different levels of restriction (high backpressure in the turbocharger passage; low backpressure in the turbocharger bypass).

Optimal valve position control ensures back pressure is optimized to obtain maximum air injection into the engine for increased power. This condition is usually created only by increasing the time in 2-stroke engines, when the temperature of the exhaust gas heats up the muffler. An improved engine response is then obtained. At the same time, having a portion of the exhaust gas flowing through the turbocharger even when the turbocharger is not in use allows the exhaust gas to quickly move to the turbine inlet when the valve is closed, which in turn causes the turbocharger to spin up quickly, reducing turbine lag. The result of this valve control can improve the response time and power of two-stroke engines, reduce the effect of turbine back pressure, and keep turbine lag to a minimum.

[009] In accordance with one aspect of the proposed technology, a snowmobile is provided, comprising a frame; at least one ski connected to the frame; a frame-mounted engine, the engine comprising an engine air inlet and an engine outlet; an exhaust pipe hydraulically connected to the engine outlet; a turbocharger fluidly connected to the exhaust pipe, the turbocharger comprising: an exhaust gas turbine and a housing housing the exhaust gas turbine; a bypass located downstream of the housing and in fluid communication with the housing, the bypass having an exhaust gas inlet hydraulically connected to the exhaust pipe; a valve located in the bypass pipe for selectively controlling the flow of exhaust gas through the turbocharger, the valve being selectively movable between at least a first position and a second position; and an exhaust manifold hydraulically connected to the turbine housing and a bypass for receiving an exhaust gas flow therefrom, a first exhaust gas flow path defined from the exhaust gas inlet to the exhaust gas manifold, the exhaust gas flowing along the first exhaust gas flow path, passing through the exhaust gas inlet, then through the bypass, and then into the exhaust manifold, a second exhaust gas flow path defined from the exhaust gas inlet to the exhaust manifold, the exhaust gas flowing along the second exhaust gas flow path, passing through the exhaust gas inlet, then through the bypass, then through the exhaust gas turbine, and then into the exhaust manifold, wherein in the first valve position, at least most of the exhaust gas flows along the first exhaust gas flow path, and in at a second position of the valve, at least a large portion of the exhaust gas flows along the second exhaust gas flow path.

[010] In some embodiments, the valve is configured to selectively move to a second position when the engine is operating below a threshold atmospheric pressure.

[011] In some embodiments, the valve is further configured to selectively move to at least one intermediate position between the first and second positions; and at at least one intermediate position, the exhaust gas flows along both the first exhaust gas flow path and the second exhaust gas flow path.

[012] In some embodiments, the implementation of the turbocharger further comprises an air compressor hydraulically connected to the air inlet of the engine; and the snowmobile further comprises an air intake system hydraulically connecting the atmosphere to the engine, the air intake system comprising: an air compressor and an engine air inlet.

[013] In some embodiments, the exhaust manifold comprises a single manifold outlet; and the snowmobile further comprises a muffler fluidly coupled to the manifold outlet, the muffler receiving exhaust gas from both the first exhaust gas flow path and the second exhaust gas flow path through the manifold outlet.

[014] In some embodiments, the exhaust manifold comprises a manifold outlet; and the snowmobile further comprises a muffler hydraulically connected to the manifold outlet, the muffler comprising one muffler inlet to receive exhaust gas from both the first exhaust gas flow path and the second exhaust gas flow path through the manifold outlet.

[015] In some embodiments, the exhaust manifold comprises: at least one inlet for receiving an exhaust gas flow, the at least one inlet comprising: a first portion for receiving exhaust gas flowing along a first exhaust gas flow path; and a second portion for receiving exhaust gas flowing along the second exhaust gas flow path; wherein said first part and said second part are integrally connected.

[016] In some embodiments, the engine comprises: a throttle valve, and a throttle valve position sensor operatively coupled to the throttle valve; and said valve is configured to selectively move based on at least a throttle valve position as determined by the throttle valve position sensor.

[017] In some embodiments, the engine comprises: a throttle valve, and a throttle valve position sensor operatively coupled to the throttle valve; and said valve is configured to selectively move based at least on the rate of change of the throttle valve position, the rate of change being determined by the throttle valve position sensor.

[018] In some embodiments, the bypass includes a passage through which exhaust gas flows while flowing along the first exhaust gas flow path; wherein the exhaust gas turbine comprises a turbine inlet through which exhaust gas flows while flowing along the second exhaust gas flow path; and the cross-sectional area of the passage is larger than the cross-sectional area of the turbocharger turbine inlet.

[019] In some embodiments, the change in direction of the exhaust gas flowing from the exhaust pipe outlet along the second exhaust gas flow path is greater than for the exhaust gas flowing from the exhaust pipe outlet along the first exhaust gas flow path, bypassing the turbine, running on exhaust gases.

[020] In accordance with another aspect of the proposed technology, a method is provided for supplying a fuel-air mixture to a vehicle engine. Said method includes determining a pressure difference between an inlet air pressure for air flowing towards an engine and an exhaust gas pressure for exhaust gas flowing out of the engine; determining, based on at least said pressure difference, an amount of fuel to be injected into the engine; and injecting said amount of fuel into the engine.

[021] In some embodiments, determining the differential pressure includes: determining an intake air pressure; and determination of exhaust gas pressure.

[022] In some embodiments, the implementation of this method further includes determining the speed of the engine; and wherein the amount of fuel to be injected is further determined based on said engine speed.

[023] In some embodiments, the implementation of this method further includes determining the position of the throttle; and wherein the amount of fuel to be injected is further determined based on said throttle position.

[024] In some embodiments, the implementation of this method further includes determining the changed pressure difference; determining, based on at least said changed pressure difference, an updated amount of fuel to be injected into the engine; and injecting said adjusted amount of fuel into the engine.

[025] In some embodiments, the implementation of this method further includes determining that the pressure difference has increased; determining, based on at least the increased pressure difference, a reduced amount of fuel to be injected into the engine; and injecting said reduced amount of fuel into the engine.

[026] In some embodiments, the implementation of this method further includes determining that the pressure difference has decreased; determining, based on at least the reduced pressure difference, a reduced amount of fuel to be injected into the engine; and injecting said reduced amount of fuel into the engine.

[027] In accordance with another aspect of the proposed technology, a snowmobile is provided, comprising a frame, at least one ski connected to the frame; an engine mounted on the frame, the engine comprising an engine outlet; a turbocharger hydraulically connected to the engine outlet; an oil reservoir hydraulically connected to the turbocharger; and an oil pump hydraulically connected between the oil reservoir and the turbocharger, the oil pump supplying oil from the oil reservoir to the turbocharger, the turbocharger hydraulically connected to the engine to supply oil from the turbocharger to the engine.

[028] In some embodiments, the oil pump further supplies oil from the oil reservoir to the engine.

[029] In some embodiments, the oil pump is the first oil pump; and further comprises a second oil pump hydraulically connected between the turbocharger and the engine, the second oil pump supplying oil from the turbocharger to the engine.

[030] In some embodiments, the oil pump further supplies oil from the oil reservoir to the engine.

[031] In some embodiments, the engine includes at least one exhaust valve; wherein the first oil pump supplies oil from the oil reservoir to at least one exhaust valve and to the turbocharger; and wherein the second oil pump supplies oil from the turbocharger to the at least one exhaust valve.

[032] In some embodiments, the engine comprises a crankshaft; and the first oil pump further supplies oil from the oil reservoir to the crankshaft.

[033] In some embodiments, the first oil pump includes four outlets; two of the four exhaust ports supply oil to the crankshaft; one of the four outlet channels supplies oil to at least one outlet valve; and one of the four exhaust ports supplies oil to the turbocharger.

[034] In another aspect of the proposed technology, a snowmobile is provided comprising a frame; at least one ski connected to the frame; a frame-mounted engine, the engine comprising an engine air inlet and an engine outlet; an exhaust pipe hydraulically connected to the engine outlet; a turbocharger hydraulically connected to the exhaust pipe, the turbocharger comprising an exhaust gas turbine; a bypass located downstream of the housing and in fluid communication with the housing, the bypass in fluid communication with the outlet of the exhaust pipe; a valve located in the bypass pipe for selectively controlling the flow of exhaust gas through the turbocharger by selectively closing the bypass passage within the bypass pipe, the valve having at least a bypass position for opening the bypass passage and directing the exhaust gas to bypass the exhaust gas turbine; and an exhaust gas collector hydraulically connected to the bypass pipe to receive an exhaust gas flow from it, wherein at least a part of the inlet of the exhaust gas collector is contained within the protrusion of the exhaust pipe outlet, and the protrusion is made along an axis perpendicular to the outlet of the exhaust pipe.

[035] In accordance with another aspect of the proposed technology, a turbocharger assembly is provided for hydraulic connection with an exhaust pipe. Said assembly comprises a turbocharger comprising: an exhaust gas turbine and a housing housing the exhaust gas turbine; and a bypass pipe located downstream of the housing and hydraulically communicating with the housing, the bypass pipe comprising: an inlet of the nozzle, wherein the exhaust gas flowing into the inlet of the nozzle is generally parallel to said flow axis; a bypass passage defined by the bypass nozzle, the bypass passage forming a fluid connection between the nozzle inlet and the bypass outlet defined by the bypass nozzle; a valve located in the bypass pipe for selectively controlling the flow of exhaust gas through the bypass passage, and the valve is configured to selectively move between at least an open position and a closed position; and a turbocharger passage defined by a bypass pipe, wherein the turbocharger passage forms a hydraulic connection between the nozzle inlet and the exhaust gas turbine, the nozzle inlet and the bypass inlet being at least partially aligned such that at least a portion of the exhaust gas , entering the inlet of the nozzle is parallel to the axis of the flow flowing freely into the bypass passage when the valve is in the open position.

[036] In some embodiments, when the valve is in the closed position, at least a portion of the valve is in contact with exhaust gas entering through the nozzle inlet and flowing parallel to the flow axis.

[037] In some embodiments, when the valve is in a position between the open position and the closed position, at least a portion of the valve is in contact with exhaust gas entering through the nozzle inlet and flowing parallel to the flow axis.

[038] In accordance with another aspect of the proposed technology, a pipe for hydraulic connection with the turbocharger housing is provided. The specified branch pipe contains the inlet part of the pipe for receiving exhaust gas from the exhaust pipe; an inlet defined by an inlet portion of the pipe, wherein the exhaust gas enters the inlet portion of the pipe through said inlet, the inlet defining a central axis perpendicular to the inlet and passing through the center of the inlet; the first outlet part of the nozzle; the second outlet part of the pipe; and a flow divider located between the first outlet part of the pipe and the second outlet part of the pipe, and the flow divider is located between the specified central axis and one of the first outlet part of the pipe and the second outlet part of the pipe.

[039] In some embodiments, the nozzle portion, the first nozzle outlet, and the second nozzle outlet are integrally connected; and the inlet portion of the pipe, the first outlet portion of the pipe, and the second outlet portion of the pipe form a Y-shaped pipe as a whole.

[040] In some embodiments, said inlet is a circle; and said central axis passes through the center of said circle.

[041] In some embodiments, the implementation of the first outlet part of the pipe is hydraulically connected to the turbocharger located inside the turbocharger housing; the exhaust gas leaves the pipe through the second outlet part of the pipe, bypassing the turbocharger; and the flow divider is located between the Central axis and the second outlet part of the nozzle.

[042] In some embodiments, the nozzle further comprises a valve located in the second outlet of the nozzle; and wherein the valve is selectively movable between at least: a first position allowing the exhaust gas to enter the second outlet of the nozzle and a second position blocking the exhaust gas from entering the second outlet of the nozzle.

[043] In accordance with yet another aspect of the proposed technology, a turbocharger assembly is provided for hydraulic connection to an exhaust pipe. Said assembly comprises a turbocharger comprising: an exhaust gas turbine, a turbocharger inlet defined by the exhaust gas turbine, and a housing housing the exhaust gas turbine; and a bypass pipe located downstream of the housing and in fluid communication with the housing, the bypass pipe comprising: an inlet pipe for receiving exhaust gas from the exhaust pipe; a bypass passage forming a hydraulic connection between the nozzle inlet and the bypass outlet defined by the bypass nozzle, the bypass passage comprising an opening; and a turbocharger passage forming a hydraulic connection between the nozzle inlet and the turbocharger inlet, the area of said opening being 0.75 to 1.25 times the area of the turbocharger inlet.

[044] In some embodiments, the area of said hole is greater than the area of the turbocharger inlet.

[045] In some embodiments, the area of the turbocharger inlet is larger than the area of said opening.

[046] In accordance with yet another aspect of the proposed technology, a method is provided for controlling the flow of exhaust gas from an engine. This method includes determining the pressure; and moving, based on at least said pressure, a valve hydraulically connected to the exhaust gas flow path to: a first position such that at least a majority of the exhaust gas flows along the first exhaust gas flow path, bypassing the exhaust gas turbine , turbocharger; a second position such that at least a majority of the exhaust gas flows along the second exhaust gas flow path through the exhaust gas turbine; and at least one intermediate position between said first position and said second position such that the exhaust gas flows partly along the first exhaust gas flow path and partly along the second exhaust gas flow path.

[047] In some embodiments, determining the pressure includes determining a pressure difference; and determining said pressure difference includes: determining a predetermined boost pressure of air flowing into the engine and determining an actual boost pressure of air flowing into the engine.

[048] In some embodiments, determining the actual boost pressure includes determining, by means of the first sensor, an intake air pressure for air flowing into the engine.

[049] In some embodiments, determining a preset boost pressure includes at least one of: determining a throttle lever position; and determining the degree of opening of the throttle valve.

[050] In some embodiments, determining a predetermined boost pressure includes at least one of: determining a throttle lever position; determining the speed of the engine; and determining the degree of opening of the throttle valve.

[051] In some embodiments, said method further comprises determining that the difference between the predetermined boost pressure and the actual boost pressure is less than a threshold difference; based on said difference less than a threshold difference, determining a desired valve position for a valve from a fine adjustment data set related to pressure fine adjustment, the fine adjustment data set providing a desired valve position to reduce the difference between a predetermined boost pressure and the actual boost pressure, wherein the fine adjustment dataset is based on at least one of throttle position and engine speed; and moving the valve towards the desired valve position following the determination of the desired valve position.

[052] In some embodiments, determining the pressure includes determining a pressure difference; and further includes determining that the pressure difference is greater than a threshold difference; determining, based on a pressure difference greater than a threshold difference, a desired valve position for a valve from a coarse adjustment data set relating to coarse pressure adjustment, the coarse adjustment data set providing a desired valve position to reduce the difference between the desired boost pressure and intake pressure, wherein the coarse adjustment dataset is based on at least one of throttle position and engine speed; and moving the valve towards the desired valve position following the determination of the desired valve position.

[053] In some embodiments, determining the pressure includes: determining, using the first sensor, an intake air pressure for air flowing into the engine, and determining, using the second sensor, an exhaust gas pressure for exhaust gas flowing from the engine; and wherein the method further includes: determining a predetermined pressure difference between the exhaust gas pressure and the intake air pressure; and determining that the difference between the pressure difference and the predetermined pressure difference is different from zero; and moving the valve based on at least said pressure, including moving the valve based on at least said difference other than zero, and moving the valve to one of: a second position; and at least one intermediate position.

[054] In some embodiments, a predetermined differential pressure is determined based on throttle position and engine speed.

[055] In accordance with yet another aspect of the proposed technology, a method for controlling the flow of exhaust gas from an engine is provided. This method includes determining, using the throttle position sensor, throttle position; determining, via the engine sensor, an engine speed for the engine; moving, based on at least one of the throttle position and engine speed, a valve hydraulically connected between the turbocharger and the engine to one of: a first position such that at least a large portion of the exhaust gas flows along the first exhaust gas flow path, bypassing exhaust gas turbine, turbocharger; a second position such that at least a majority of the exhaust gas flows along the second exhaust gas flow path through the exhaust gas turbine; and at least one intermediate position between said first position and said second position such that the exhaust gas flows partly along the first exhaust gas flow path and partly along the second exhaust gas flow path.

[056] In some embodiments, valve movement is based on at least one of throttle position, engine speed, and temperature of an exhaust pipe operatively coupled to the engine.

[057] In some embodiments, said method further includes: determining a pressure difference by: determining a predetermined boost pressure of air flowing into the engine, wherein the predetermined boost pressure is determined based on at least one of a throttle position and an engine speed, and determining the actual boost pressure of air flowing into the engine; and wherein the movement of the valve is additionally based on said pressure difference.

[058] In some embodiments, determining the actual boost pressure includes determining, by means of the first sensor, an intake air pressure for air flowing into the engine.

[059] In some embodiments, the implementation of the specified method further includes determining the temperature of the exhaust pipe located downstream of the valve; and wherein the movement of the valve is additionally based on said outlet pipe temperature.

[060] In some embodiments, the implementation of the specified method further includes before moving the valve: determining whether the engine is running at low altitude or at high altitude; extracting, after determining that the engine is operating at low altitude, the desired valve position from the low altitude data set; extracting, after determining that the engine is operating at high altitude, the required valve position from the high altitude data set; and wherein: moving the valve includes moving the valve to said desired position, the desired position being one of a first position, a second position, and at least one intermediate position.

[061] In some embodiments, said method further includes determining whether the engine is operating at low altitude or at high altitude, including determining atmospheric pressure using the first pressure sensor.

[062] In some embodiments, said method further comprises determining, based on at least one of throttle position and engine speed, a threshold engine differential pressure; determination of the actual pressure difference of the engine; determining that the actual pressure difference is greater than the threshold pressure difference; and moving, based at least on an actual pressure difference greater than a threshold pressure difference, of the valve towards the first position if the valve is in one of the second position and at least one intermediate position.

[063] In some embodiments, determining an actual engine differential pressure includes determining, with an exhaust pressure sensor, an exhaust pressure downstream of the engine; determining, by means of an intake air sensor, an intake air pressure downstream of the engine; and determining the pressure difference between the outlet and the intake air pressure.

[064] In accordance with yet another aspect of the proposed technology, a method is provided for controlling the flow of exhaust gas from an engine. Said method includes determining that the pressure of the exhaust gas of air flowing from the engine exceeds the threshold pressure of the exhaust gas, positioning a valve hydraulically connected between the turbocharger and the engine in a first position such that at least a large part of the exhaust gas flows along the first flow path. exhaust gas passing through the exhaust gas turbine of the turbocharger; and moving the valve, based at least on an exhaust gas pressure greater than the exhaust gas threshold pressure, to one of: a second position such that at least a majority of the exhaust gas flows along the second exhaust gas flow path, bypassing the exhaust gas turbine ; and at least one intermediate position between said first position and said second position such that the exhaust gas flows partly along the first exhaust gas flow path and partly along the second exhaust gas flow path.

[065] For the purposes of this application, terms relating to spatial orientation, such as forward, backward, up, down, left, and right, correspond to those normally implied by a snowmobile rider sitting on it in a normal driving position. Terms relating to spatial orientation, when describing or referring to components or subassemblies of a snowmobile separate from the snowmobile, such as, for example, a heat exchanger, should be understood as they will be understood when these components or subassemblies are installed on the snowmobile, unless in this application otherwise indicated.

[066] Each of the embodiments of the proposed technology has at least one of the above objectives and/or aspects, but not necessarily all of them. It should be understood that some aspects of the proposed technology resulting from an attempt to achieve the above goal may not satisfy this goal and/or may satisfy other goals that are not specifically stated in this document. The above explanations in relation to the above terms take precedence over the explanations of these terms, which can be found in any of the documents incorporated herein by reference.

[067] Additional and/or alternative features, aspects, and advantages of implementations of the proposed technology will become apparent from the following description, the accompanying drawings, and the accompanying claims.

Brief description of the drawings

[068] For an improved understanding of the proposed technology, as well as other aspects and features thereof, reference is made to the following description, which should be used in conjunction with the accompanying drawings, in which:

[069] FIG. 1 is a left side elevation view of a snowmobile with part of the drive track;

[070] FIG. 2 is a top, rear, and right perspective view of the engine, air intake system, and exhaust system of the snowmobile of FIG. 1;

[071] FIG. 3 is a front elevation view of the engine, air intake system, and exhaust system of FIG. 2;

[072] FIG. 4 is a cross-sectional view of the engine and some parts of the air intake and exhaust system according to FIG. 2;

[073] FIG. 5 is a top plan view of parts of the air intake system and the exhaust system according to FIG. 2;

[074] FIG. 6 is a schematic representation of the snowmobile lubrication system according to FIG. 1;

[075] FIG. 7 is a schematic representation of the lubricating oil flow of the lubrication system according to FIG. 6;

[076] FIG. 8 is a schematic representation of the exhaust system according to FIG. 2;

[077] FIG. 9 is an enlarged view of parts of the air intake system and exhaust system according to FIG. 5;

[078] FIG. 10 is a right side elevational view of parts of the air intake system and the exhaust system according to FIG. 2;

[079] FIG. 11 is an enlarged view of parts of the air intake system and the exhaust system according to FIG. 10;

[080] FIG. 12 is a front elevation view of the turbocharger, wastegate, and exhaust manifold of the exhaust system of FIG. 2;

[081] FIG. 13 is a perspective view of the bypass according to FIG. 12 shown separately;

[082] FIG. 14 is a cross-sectional view of the bypass according to FIG. 12 taken along line 14-14 in FIG. 13 with the valve in the closed position;

[083] FIG. 15 is a cross-sectional view according to FIG. 14, with the valve in the open position;

[084] FIG. 16 is a cross-sectional view according to FIG. 14, with valve in intermediate position;

[085] FIG. 17 is a perspective view of parts of the turbocharger and the wastegate according to FIG. 12, with part of the top of the bypass and the valve removed;

[086] FIG. 18 is a plan view of the turbocharger and wastegate of FIG. 12;

[087] FIG. 19 is a cross-sectional view of the turbocharger according to FIG. 18 taken along line 19-19 in FIG. 18;

[088] FIG. 20A is a left side elevation view of the exhaust manifold according to FIG. 12 shown separately;

[089] FIG. 20B is a right perspective view of the exhaust manifold according to FIG. 20A;

[090] FIG. 20C is a bottom view of the exhaust manifold according to FIG. 20A;

[091] FIG. 21 is a flowchart illustrating a method for controlling the flow of exhaust gas through the exhaust system according to FIG. 2, corresponding to the proposed technology;

[092] FIG. 22 is a flowchart illustrating another method for controlling the flow of exhaust gas through the exhaust system according to FIG. 2, corresponding to the proposed technology;

[093] FIG. 23 is a flowchart illustrating another method for controlling the flow of exhaust gas through the exhaust system according to FIG. 2, corresponding to the proposed technology;

[094] FIG. 24 is a flowchart illustrating a method for supplying an air-fuel mixture to an engine according to FIG. 2, corresponding to the proposed technology;

[095] FIG. 25 is a cross-sectional view of the bypass according to FIG. 12 taken along line 25-25 in FIG. 13 with the valve in the open position;

[096] FIG. 26 is an elevation view of the inlet side of the valve according to FIG. 14;

[097] FIG. 27 is a vertical view of the outlet side of the valve according to FIG. 26;

[098] FIG. 28 is a cross-sectional view of the valve according to FIG. 26 taken along line 28-28 in FIG. 27;

[099] FIG. 29 is a cross-sectional view of the valve according to FIG. 26 taken along line 29-29 in FIG. 27; And

[0100] FIG. 30 is a graph showing percent orifice mass flow as a function of valve position;

[0101] FIG. 31 is a block diagram depicting an exemplary scenario for controlling the flow of exhaust gas through the exhaust system according to FIG. 2;

[0102] in FIG. 32 illustrates an exemplary dataset for use in the exemplary scenario of FIG. 31;

[0103] in FIG. 33 illustrates additional exemplary data sets for use in the exemplary scenario of FIG. 31;

[0104] in FIG. 34 illustrates an exemplary data set for use in the method of FIG. 24;

[0105] FIG. 35 is a partial sectional view of the air intake of the air intake system according to FIG. 2 with part of the left side of the air intake removed; And

[0106] FIG. 36 is a partial sectional view of the air intake according to FIG. 35 with the rear side of the air intake removed.

[0107] It should be noted that these figures may not be drawn to scale unless otherwise indicated.

Implementation of the invention

[0108] The proposed technology is described herein in relation to a snowmobile 10 containing an internal combustion engine and two skis. However, it is contemplated that some aspects of the proposed technology could be applied to other types of vehicles such as, but not limited to, single ski snowmobiles, on-road vehicles with two, three or four wheels, off-road vehicles, all-terrain vehicles , in-line ATVs and water scooters.

[0109] A snowmobile 10 in accordance with the proposed technology will be described with reference to FIG. 1 and 2. The snowmobile 10 includes a front end 12 and a rear end 14. The snowmobile 10 includes a vehicle body in the form of a frame or chassis 16 which includes a tunnel 18, an engine support 20, a front suspension module 22, and an upper structure 24.

[0110] The internal combustion engine 26 is installed in an engine compartment partially defined by the engine support portion 20 of the frame 16. The fuel tank 28, mounted above the tunnel 18, supplies fuel to the engine 26 for its operation. The engine 26 receives air from the air intake system 100 . Engine 26 and air intake system 100 are described in more detail below.

[0111] An endless drive track 30 is located at the rear end 14 of the snowmobile 10. The drive track 30 is located generally below the tunnel 18 and is operatively connected to the engine 26 via a belt drive and reduction drive system. The endless drive track 30 is driven to rotate around a rear suspension assembly 32 operatively connected to the tunnel 18 to drive the snowmobile 10. The endless drive track 30 includes a plurality of ridges 31 extending from its outer surface to provide traction for the track 30.

[0112] The rear suspension assembly 32 includes drive sprockets 34, idler wheels 36, and a pair of guide rails 38 in sliding contact with the endless drive track 30. Drive sprockets 34 are mounted on axle 35 and define an axle 34a for the sprockets. Bridge 35 is operatively connected to crankshaft 126 (see FIG. 3) of engine 26. Guide rails 38 are attached to tunnel 18 by front and rear suspension arms 40 and shock absorbers 42. It is contemplated that snowmobile 10 may be equipped with another embodiment of assembly 32 rear suspension other than that shown in this document.

[0113] The motorcycle-type seat 60 is located above the fuel tank 28. The fuel filler opening covered by the cap 92 is located on the top surface of the fuel tank 28 in front of the seat 60. It is contemplated that the fuel filler opening may be located elsewhere on the fuel tank 28. The seat 60 is adapted to accommodate the driver of the snowmobile 10. The seat 60 may also be configured to accommodate a passenger. On each side of the snowmobile 10 under the seat 60 is a footrest 64 to accommodate the driver's foot.

[0114] At the front end 12 of the snowmobile 10, fairings 66 surround the engine 26 and the belt drive system, thereby providing an outer shell that not only protects the engine 26 and said transmission system, but can also make the snowmobile 10 more aesthetically pleasing. The fairings 66 comprise a hood 68 and one or more side panels that can be opened to allow access to the engine 26. A windshield 69 connected to the fairings 66 acts as a windshield to reduce the force of air acting on the driver when the snowmobile is moving. 10.

[0115] Two skis 70 located at the front end 12 of the snowmobile 10 are attached to the front suspension module 22 of the frame 16 via the front suspension assembly 72. The front suspension module 22 is connected to the front end of the engine support portion 20 . The front suspension assembly 72 includes ski legs 74, support arms 76, and ball joints (not shown) for operative connection with the corresponding ski leg 74, support arms 76, and steering column 82 (illustrated schematically).

[0116] In General, in front of the seat 60 is the node 80 control containing column 82 steering and steering wheel 84. Column 82 steering connected to the frame 16 with the possibility of free rotation. The lower end of the steering column 82 is connected to the ski legs 74 via tie rods (not shown). The steering wheel 84 is attached to the upper end of the steering column 82. A handlebar 84 is located forward of the seat 60. The handlebar 84 is used to rotate the steering column 82 and hence the skis 70 to steer the snowmobile 10. A throttle control device 86 in the form of a thumb operated throttle lever is mounted on the right side of the handlebar 84. Also provided are other types of throttle control devices such as finger-actuated throttle lever and twist grip. A brake actuator 88 in the form of a handbrake lever is provided on the left side of the handlebar 84 to brake the snowmobile 10 in a known manner. It is envisaged that the windshield 69 can be directly connected to the steering wheel 84.

[0117] At the rear end of the snowmobile 10, a snow flap 94 extends downward from the rear end of the tunnel 18. The snow flap 94 protects against mud and snow that may fly upward from the drive track 30 when the snowmobile 10 is driven by the moving drive track 30. It is contemplated that the snow flap 94 may be omitted.

[0118] The snowmobile 10 includes other components such as a display unit and the like. Since these components are considered to be well known to the person skilled in the art, further explanation and description of these components is not provided in this document.

[0119] Referring further to FIG. 2-6, engine 26 and air intake system 100 will be described in more detail. Atmospheric air flows through side openings 113 defined in the upper portion 25 of the upper structure 24 of the chassis 16. This air then flows into the secondary air intake 110. The secondary air intake 110 is located above the front suspension module 22. In general, a Y-shaped pipe 118 (FIG. 2) hydraulically connects the secondary air intake 110, through the pipe part 117, with the inlet 312 of the air compressor 310 (FIG. 5) located on the right side of the engine 26. The pipe 118 is additionally hydraulically connected to the intake hole 119 of the primary air intake 120 through the part 121 of the pipe. The primary air intake 120 includes a bypass valve 123 (see FIGS. 35 and 36) that controls the flow of air through the inlet 119 into the primary air intake 120. It is contemplated that the secondary air intake 110 can be omitted and that air from the atmosphere can directly enter the inlet 312 and/or the inlet 119 of the primary air intake 120 without passing through the secondary air intake 110.

[0120] Air from the atmosphere, passing through the secondary air intake 110 and into the air compressor 310 through the nozzle 118 and the inlet 312, is compressed by the air compressor 310. The compressed air then flows out of the air compressor 310 through the outlet 314 into the nozzle 316 and into the primary air intake 120. Primary air intake 120 is hydraulically connected to engine 26 via two air outlets 122 of primary air intake 120 (see also FIG. 10). Bypass valve 123 of primary air intake 120 is spring-loaded in the closed position so that air is predominantly taken from air compressor 310 through port 316. air than is available in the primary air intake 120, the valve 123 opens to allow air from the atmosphere, through the secondary air intake 110, to directly enter the primary air intake 120.

[0121] In some situations, this can help achieve optimal engine 26 performance, especially when turbocharger 300 is spinning up and not supplying the required airflow to primary air intake 120 for the air required by engine 26. As shown in FIG. 35, valve 123 includes a spring 125. The spring rate for spring 125 is chosen such that valve 123 will open and close at a predetermined pressure within primary air intake 120. Thus, once opened, bypass valve 123 will automatically close when airflow from turbocharger 300 increases the pressure in the primary air intake 120 to a predetermined pressure, and vice versa. The valve diameter 123 is sized to allow for high flow rates between the secondary and primary air intakes 110, 120. This helps ensure optimum pressure in the primary air intake 120 and thus contributes to optimum overall engine performance in all situations, even if the turbocharger 300 not untwisted. The duct portion 117 and bypass valve 123 also reduce the distance traveled by the air flow between the secondary air intake 110 and the primary air intake 120, when compared to the distance traveled by the air flow through the duct portion 121, the turbocharger 300 and the duct 316. Thus, depending on the air pressure inside the primary air inlet 120, the air flow between the secondary and primary air inlets 110, 120 has either a short air flow path or a long air flow path available. The inclusion of a bypass valve 123 in the primary air intake 120 further allows the engine 26 to operate in either a turbocharged or naturally aspirated mode. The operation of the engine 26 and the corresponding operation of the turbocharger 300 for operation in these two modes will be described in more detail below.

[0122] Engine 26 is an in-line, two-cylinder, two-stroke internal combustion engine. The two cylinders of the engine 26 are oriented so that their cylindrical axes are vertical. It is contemplated that the motor 26 may be configured differently. For example, engine 26 may contain more or less than two cylinders, and the cylinders may be arranged in a V-shape rather than in a row. It is contemplated that, in some embodiments, engine 26 may be a four-stroke internal combustion engine, a carburetor engine, or any other suitable engine capable of driving snowmobile 10.

[0123] As shown in FIG. 1, 2 and 4, the engine 26 receives air from the air intake system 100, in particular from the outlets 122 of the primary air intake 120, through the engine air inlets 27 defined at the rear of each cylinder of the engine 26. Each air inlet 27 is connected to the throttle body 37 air intake systems 100. The throttle body 37 includes a throttle valve 39 that rotates to control the amount of air flowing through the throttle body 37 into the corresponding cylinder of the engine 26. A throttle valve actuator (not shown) is operatively connected to the throttle valve 39 to change the position of the throttle valve 39 and thus adjust the opening of throttle valve 39 via throttle lever 86 on handlebar 84. In the exemplary embodiment, the throttle valve actuator is a mechanical linkage, although this is just one non-limiting embodiment. The position and movement of the throttle valve 39 is monitored by a throttle valve position sensor 588 (shown schematically in FIG. 8) operatively coupled to the throttle valve 39, described in more detail below. It is also contemplated that the throttle valve actuator may be in the form of an electric motor. Said electric motor can change the position of the throttle valve 39 based on inputs received from an electronic control module (not shown), which in turn receives inputs from a position sensor associated with the throttle lever 86 on the steering wheel 84. Further details regarding such throttle systems with electric drive can be found in International Patent Application No. PCT/US 2013/048803, filed June 29, 2013, which is incorporated herein by reference in its entirety.

[0124] Engine 26 receives fuel from fuel tank 28 through Direct Injection (Dl) injectors 41 and Multi Point Fuel Injection (MPFI) injectors 45 (both shown at least in FIG. 4) having openings in cylinders. The air/fuel mixture in each of the left and right cylinders of engine 26 is ignited by an ignition system containing spark plugs 43 (best seen in FIG. 2). Engine power output, engine torque, and engine speed are partly determined by throttle opening and partly by ignition timing, as well as various air/fuel mixture characteristics such as composition, temperature, pressure, and the like. Air-fuel mixture control methods in accordance with some embodiments of the proposed technology will be described in more detail below with reference to FIGS. 24.

[0125] The exhaust gases resulting from combustion in the combustion process are removed from the engine 26 through the exhaust system 600 (FIG. 5). As shown in FIG. 4, an exhaust port 29 is defined at the front of each engine cylinder 26. Each exhaust port 29 includes an exhaust valve 129. The exhaust ports 29 are hydraulically connected to an exhaust manifold 33. The exhaust system 600 includes an exhaust pipe 202 that is connected to the exhaust manifold 33 and extends forward. from it to direct the exhaust gases from the engine 26.

[0126] Turbocharger 300 is operatively coupled to engine 26. Turbocharger 300 compresses air and supplies it to engine 26. As shown in FIG. 6 and 12, the turbocharger 300 includes a housing 302 defining an air compressor 310 and an exhaust gas turbine 350. With additional reference to FIG. 19, the exhaust gas turbine 350 comprises a turbine inlet 355 with an area 354, which is defined in turbochargers in general as the cross-sectional area of the helical flare 352 (measured on the petal) of the exhaust gas turbine 350. The air compressor 310 includes a compressor wheel and is part of the air intake system 100 . The intake air flowing past the rotating compressor wheel is compressed as described above. The rotation of the compressor wheel is from the turbine wheel 351 (FIGS. 19, 25) of the exhaust gas turbine 350, which is part of the exhaust system 600. Turbine wheel 351 is driven by exhaust gases exhausted from engine 26 and directed to flow around the blades of turbine wheel 351. It is contemplated that, in some embodiments, air compressor 310 could be a supercharger in which the compressor wheel would be driven directly from engine 26. System 600 release will be described in more detail below.

[0127] Referring to FIG. 6 and 7, snowmobile 10 further includes a lubrication system for supplying lubricating oil to engine 26 and turbocharger 300. Engine 26 is hydraulically connected to oil reservoir 52, which supplies oil to crankshaft 126 and exhaust valves 129 of engine 26. Oil reservoir 52 also hydraulically connected to the turbocharger 300 to supply oil to it. Turbocharger 300 is also hydraulically coupled to engine 26, as will be further described below.

[0128] The primary oil pump 54 is attached to and hydraulically connected to the oil reservoir 52. It is contemplated that pump 54 and oil reservoir 52 may be connected together in various ways or may be located separately in snowmobile 10. Primary oil pump 54 pumps oil from said reservoir 52 to engine 26 and turbocharger 300. Primary oil pump 54 comprises four outlets for pumping oil out of the oil reservoir 52. Two outlets 53 supply oil to the crankshaft 126. Another outlet 55 supplies oil to one of the exhaust valves 129. A fourth exhaust port 57 supplies oil to the turbocharger 300. Depending on the embodiment, it is contemplated that the primary oil pump 54 may comprise more or less outlet channels depending on the details of the embodiment.

[0129] A secondary oil pump 56 and an oil/steam separation tank 59 are hydraulically connected between the turbocharger 300 and the engine 26. The secondary oil pump 56 receives the oil that has passed through the turbocharger 300 and pumps the oil to another exhaust valve 129. In FIG. . 7 illustrates schematically the directions of oil flow from pumps 54, 56 and through turbocharger 300 to engine 26. It should be further noted that in the proposed embodiment, turbocharger 300 is a ball bearing turbocharger 300 that is designed for low oil flow lubrication to provide an effective response. It is contemplated that different types of turbochargers may be used in various embodiments.

[0130] This configuration uses only one oil reservoir 52 to lubricate both turbocharger 300 and engine 26. It is contemplated that snowmobile 10 could also be configured such that secondary oil pump 56 could be omitted. It is also contemplated that oil may be circulated to crankshaft 126 rather than exhaust valves 129 after passing through turbocharger 300.

[0131] Referring further to FIG. 8-19, the exhaust system 600 will now be described in more detail. Exhaust gas exhausted from engine 26 flows through exhaust ports 29, through exhaust manifold 33, and into exhaust pipe 202 as mentioned above. Exhaust pipe 202, also known as muffler 202, is curved and has a variable diameter along its length. Other types of exhaust pipes 202 are contemplated. As shown in FIG. 5, the outlet pipe 202 includes a pipe inlet 203 fluidly connected to the outlet manifold 33 and a pipe outlet 206 located at the end of the outlet pipe 202. The outlet pipe 202 further comprises a flared portion adjacent to the pipe inlet 203 and a convergent portion adjacent to the pipe outlet 206. The pipe outlet 206 is located downstream of the pipe inlet 203 .

[0132] The exhaust system 600 also includes a bypass pipe 620 for directing the flow of exhaust gas either bypassing the turbocharger 300 or passing through the exhaust gas turbine 350 of the turbocharger 300 to operate the air compressor 310. exhaust pipe 202, hydraulically communicates with the bypass pipe 620. In particular, the bypass pipe 620 defines an inlet 622 for exhaust gases, which is hydraulically connected to the outlet pipe 206 of the pipe. Exhaust gas inlet 622 and pipe outlet 206 are arranged such that exhaust gas passing from pipe outlet 206 to exhaust gas inlet 622 passes through inlet 622 generally normal to inlet 622. Central axis 629 (FIG. 13) of the exhaust inlet 622 illustrates the general direction of the exhaust gas flowing into the bypass pipe 620. In the illustrated embodiment, the central axis 629 coincides with the center of the circular inlet 622, but this may not always be the case.

[0133] The bypass pipe 620 is further hydraulically connected to the housing 302 of the turbocharger 300. More specifically, the bypass pipe 620 is mechanically connected to the turbocharger housing 302 in the present embodiment by means of a clamp 303. It is contemplated that the bypass pipe 620 may be an independent device from the turbocharger 300. It is also contemplated that the bypass pipe 620 may be attached or otherwise mechanically connected to the turbocharger housing 302. It is also further contemplated that the bypass pipe 620 and turbocharger housing 302 can be integrally formed.

[0134] The bypass pipe 620 is generally Y-shaped with an inlet pipe portion 690 extending from the exhaust inlet 622 and branching into two outlet pipe portions 692, 694 (FIG. 14). Thus, and as discussed above, the bypass 620 serves to selectively direct the exhaust gas that enters through the exhaust gas inlet 622 either into the exhaust gas turbine 350 or bypasses the exhaust gas turbine 350. The turbine outlet 692 of the bypass pipe 620 (one Y-shaped branch) is in fluid communication with the turbine inlet 355. The bypass outlet 694 (another Y-shaped branch) allows the exhaust gas to bypass the turbocharger 300 to leave the bypass 620 through the bypass outlet 626. The bypass outlet 694 defines a passage 625 which allows for hydraulic communication between the inlet 622 to exhaust and outlet 626. The outlet 626 and passage 625 can also be seen in FIG. 17. As best seen in FIG. 16, the bypass nozzle 620 further includes a flow divider 628 located between the nozzle portions 692, 694. The flow divider 628 assists in the smooth separation of the exhaust gas stream through the bypass 620 to help avoid splitting or creating vortices in the exhaust gas stream. To this end, the flow divider 628 is typically shaped and positioned to avoid sharp edges.

[0135] The flow of exhaust gas through passage 625 is selectively controlled by valve 630 located in bypass pipe 620 in conjunction with system controller 500, control valve 630. More specifically, valve 630 is a valve for selectively diverting exhaust gas from turbocharger 300. In the present In an embodiment, valve 630 is located in passage 625, and more specifically on its valve seat 623. It is contemplated that valve 630 may be located elsewhere in bypass 620, such as closer to exhaust inlet 622 and upstream of the passage 625, depending on the particular embodiment of valve 630. It is also contemplated that in some embodiments, valve 630 may selectively open or close turbine outlet 692 rather than bypass passage 625.

[0136] Referring to FIG. 26-29, the valve 630 includes a base portion 400 and a working portion 402 extending from the base portion 400. The base portion 400 is configured to pivotally mount the valve 630 within the bypass pipe 620 and thus defines a valve rotation axis 404 around which the valve 630 is rotatable. during application. More specifically, the base portion 400 is generally cylindrical and has an awn 440 including two axial portions 441 extending in opposite directions from the central portion of the base portion 400. Although the axle 440 is integrally manufactured with the valve 630 in this embodiment, it is assumed that in other embodiments, axle 440 may be a separate component (eg, two separate axle parts connected to base part 400).

[0137] The working part 402 is part of the valve 630, which is used to block the passage 625. The working part 402 includes an inlet side 406 and an outlet side 408 opposite the inlet side 406. Inlet side 406 is open during use for hydraulic flow at bypass 620. In other words, inlet side 406 generally faces inlet 622, while outlet side 408 faces overflow outlet 626. Valve 630 operating portion 402 is shaped , facilitating the control of the flow of exhaust gas through the passage 625. In particular, the working part 402 has a generally pointed shape defining a rounded tip 410 at the location of the working part 402, the most distant from the base part 400 in the direction of the length of the valve 630 (generally perpendicular to the axis 404 of rotation valve). Thus, the working part 402 of the valve 630 (ie, the part of the valve 630 used to block the passage 625) can be called generally elongated.

[0138] The outer boundary 412 of the working part 402 generally defines its surface. The outer border 412 includes two opposite longitudinal edges 414 that extend from the base portion 400 in a direction generally parallel to the length direction of the valve 630. The outer border 412 also includes a rounded edge 416 defined by a rounded tip 410 and two converging corner edges 418 extending between the two longitudinal edges 414 and the corresponding edges of the chamfer 416 (ie, the corner edges 418 connect the longitudinal edges 414 to the chamfer 416). The corner edges 418 converge towards each other as the corner edges 418 extend from the two longitudinal edges 414 to the ends of the rounded edge 416. Each of the corner edges 418 is thus at an angle of 6 with respect to the length direction of the valve 630. The corner 9 may be in the range from 10° to 45° inclusive. For example, in this embodiment, angle 6 is approximately 30°.

[0139] As shown in FIG. 26, the working portion 402 of the valve 630 is generally symmetrical with respect to the plane of symmetry PS bisecting the rounded tip 410. The plane of symmetry PS is perpendicular to the axis of rotation 404 of the valve. Each of the longitudinal edges 414 and the corner edges 418 is located on either side of the plane of symmetry PS. Moreover, in this embodiment, the base portion 402 of the valve 630 is also symmetrical with respect to the symmetry plane PS. However, it is contemplated that valve 630 may not be symmetrical about the PS plane.

[0140] The width of the stem 402, measured in a direction parallel to the valve rotation axis 404, varies along the length direction of the valve 630. For example, the width of the stem 402 is largest adjacent to the base portion 400. More specifically, the maximum width W _{max of} the stem 400 402 is measured between two opposite longitudinal edges 414. The width of the lip 402 decreases at the corner edges 418 along the length direction of the valve 630 towards the rounded tip 410. In particular, the width of the vane 402 is narrowest at the rounded tip 410.

[0141] As shown in FIG. 27, the length L _{v of} the valve 630 is measured from the base portion 400 to the rounded tip 410 in the direction of the length of the valve 630. In this embodiment, the length L _v of the valve 630 is greater than or equal to the width W _max of the working portion 402. In particular, the length L _v is greater than the maximum width W _max , such that the ratio L _v /W _max of the valve 630 length L _v to the maximum width W _max of the working portion 402 is greater than 1. For example, the ratio L _v /W _max may be in the range of 1 to 2, inclusive. In particular, the ratio L _v /W _max is in the range from 1.2 to 1.6. In one particular embodiment, the ratio L _v /W _max is about 1.3.

[0142] Moreover, the ratio L _v /W _max of the maximum width W _max of the working portion 402 to the radius R _T of the tip for the rounded tip 410 is greater than 2. For example, the ratio L _v / W _max can be in the range of 2 to 6 exclusively. In this embodiment, the ratio L _v /W _max is about 3.

[0143] As shown in FIG. 26, the working part 402 of the valve 630 includes a rib 420 located on the inlet side 406. In particular, the rib 420 protrudes from the generally flat surface 422 of the inlet side 406. In this embodiment, the height of fin 420, measured from surface 422, is constant. Rib 420 forms a closed shape, which in this embodiment is generally pentagonal. As will be described in more detail below, the outer border 412 defines a portion of the rib 420.

[0144] In this embodiment, the rib 420 includes five edges, including a base edge 424, two outwardly extending edges 426, and two inwardly extending edges 428. The base edge 424 extends generally parallel to the axis of rotation 404 of the valve and is located proximate the base portion 400 of the valve 630 Each outwardly extending edge 426 extends from a respective end of base edge 424 outward to a respective one of the longitudinal edges 414 of outer boundary 412 of working portion 402. Inwardly extending edges 428 are generally parallel to respective corner edges 418 of outer boundary 412 of working portion 402. Each inwardly extending edge 428 extends from the end of the respective one of the outwardly extending edges 426.

[0145] Edges 424, 426, 428 of rib 420 intersect at respective rounded corners 430 ₁ -430 ₅ . In particular, the inwardly extending edges 428 converge on the far rounded top 430 ₅ which, among other tops 430 ₁ -430 ₅ , is the farthest from the base portion 400. The far rounded top 430 ₅ is generally concentric with the rounded edge 416 of the outer border 412 of the working part 402. Specifically, the rounded edge 416 of the outer border 412 defines the rounded top 430 ₅ of the rib 420. Moreover, the corner edges 418 and the longitudinal edges 414 define the inward and outward edges 428, 426, respectively.

[0146] As shown in FIG. 29, the cross-sectional profile of the rib 420, which may be observed, for example, along a plane normal to the length direction of the valve 630, is generally trapezoidal.

[0147] Referring to FIG. 27-29, the valve body 402 of the valve 630 also includes an outer lip 432 protruding from the outlet side 408 of the valve body 402. The outer lip 432 extends from the outer boundary 412 of the valve body 402. The outer lip 432 thus has generally the same shape as defined by the outer lip 432. border 412. The outer lip 432 has a variable height measured from the surface 434 of the outlet side 408 of the working part 402. The height of the outer lip 432 adjacent to the base part 400 exceeds the height of the rib 420.

[0148] The valve 630 as described above is generally shaped to avoid sharp edges to help prevent flow splitting or vortexing in the exhaust gas stream within the bypass pipe 620.

[0149] In this embodiment, the valve 630 is a one-piece component, since the base portion 400 and the working portion 402 are made as a single unit. However, it is contemplated that, in alternative embodiments, base portion 400 and head portion 402 may be fabricated as separate components and coupled together to form valve 630.

[0150] Referring to FIG. 12, actuator 635 is operatively coupled to valve 630 causing valve 630 to rotate about valve rotation axis 404 (shown in FIG. 26). In this embodiment, drive 635 is a servomotor. It is contemplated that other types of actuators may be used in other embodiments. The actuator 635 is connected to the valve 630 via a lever assembly 636. More specifically, in this embodiment, the lever assembly 636 includes three levers 637, 638, 639. The lever 637 is connected to the actuator 635 and is thus pivotable. The lever 638 is connected to the axis 440 of the valve base 400 630. The lever 639 is connected between the levers 637, 638. The rotation of the lever 637 thereby actuates the other two levers 638, 639 and causes the valve 630 to rotate between the open position, the closed position and the intermediate position as will be described below. It is contemplated that, in some embodiments, valve 630 may rotate, translate, or otherwise be moved to control the flow of exhaust gas through passage 625.

[0151] The valve 630 is controlled to regulate the flow of exhaust gas through the turbocharger 300 by selectively blocking or opening the valve hole 627 defined by the valve seat 623 of the passage 625. Thus, the valve hole 627 defined by the valve seat 623 is shaped such that it matches the shape the working portion 402 of the valve 630 (i.e., generally elongated and having a rounded tip). Valve 630 is pivotally mounted on valve seat 623 through valve body 400 630 and is selectively movable between: an open position in which exhaust gas flow through valve opening 627 (and thus passage 625) is substantially unrestricted by valve 630; a closed position in which valve 630 completely closes valve opening 627 so that exhaust gas flow through valve opening 627 is closed valve 630; and any number of intermediate positions between the open and closed positions. In this embodiment, as shown in FIG. 15, in its open position, valve 630 is at an angle of approximately 45° (measured from valve seat 623—ie, 0° corresponds to the closed position of valve 630). Moreover, in the open position, the valve 630 contacts the wall of the bypass 620 on the side opposite the flow divider 628, but this may not be the case in all embodiments.

[0152] A cross section of the bypass pipe 620 is illustrated in FIG. 14-16 to show various positions of the valve 630. In FIG. 14 illustrates the closed position; in fig. 15 illustrates the open position (also illustrated in FIG. 25); and in FIG. 16 illustrates one of many possible intermediate positions for valve 630. As can be seen, valve 630 is oriented in bypass 620 such that rounded tip 410 is downstream of base portion 400. That is, in open, closed, and intermediate positions, rounded tip 410 valve 630 is downstream of base portion 400. Exhaust gas flow through bypass 620 for each of these relative positions of valve 630 will be described in more detail below. As can be seen in FIG. 14, in its closed position, the valve 630 contacts the valve seat 623. More specifically, in the closed position, the rib 420 of the working portion 402 of the valve 630 sits against the valve seat 423.

[0153] With respect to the round valve, the generally elongated shape of the valve 630 as described above establishes a more linear relationship between the exhaust gas mass flow through the orifice 627 and the angle at which the valve 630 is open. In other words, the shape of the valve 630 allows more control the mass flow of the exhaust gas through the opening 627. As a consequence, the back pressure within the exhaust system 600 caused by the opening of the valve 630 can be controlled more accurately by the round valve. This can be seen in the graph of Fig. 30, which illustrates percent orifice mass flow as a function of valve position (percentage - 0% is valve closed; 100% is valve fully open) for the 630 valve of the proposed technology and for the round valve. The percentage mass flow reaches 100% when the valve is in the open position (for a 630 valve, this corresponds to an angle of 45°, but is approximately 90° for a round valve). In particular, performance curve P1 represents the percentage mass flow through port 627 as a function of valve position 630 in accordance with the proposed technology. For comparison, the performance curve PA represents the percentage mass flow through a round orifice as a function of the position of its corresponding round valve. As can be seen, in accordance with the proposed technology, the relationship between the percentage of mass flow through the port 627 and valve position 630 is noticeably more linear than for a round valve, especially at smaller valve angles (for example, below 45% - i.e. below 20 ° for valve 630).

[0154] The exhaust system 600 further comprises a system controller 500 that is operatively coupled to the engine control unit (or ECU) and/or electrical system (not shown) of the snowmobile 10. The engine control unit is in turn operatively coupled to the engine 26 As will be described in more detail below, system controller 500 is also operatively and communicatively coupled to atmospheric pressure sensor 504, also referred to as intake air sensor 504, for sensing atmospheric or ambient air pressure for intake air entering air intake system 100. It should be noted that the atmospheric pressure sensor 504, also referred to as the intake pressure sensor 504, senses the air pressure in the primary air intake 120, and thus measures the intake air pressure for air entering or from the ambient air around the snowmobile 10 and/or air entering into primary air intake 120 from turbocharger 300.

[0155] An actuator 635 for selectively moving valve 630 is communicatively coupled to system controller 500 such that the position of valve 630 is thereby controlled. It is contemplated that the valve 630 may be controlled or moved in various ways, depending on the embodiment.

[0156] As illustrated in the schematic in FIG. 8 and as will be described in more detail below, system controller 500 is also operatively coupled to throttle valve position sensor 588 to determine the position of throttle valve 39, the degree of opening of throttle valve 39, or both. In some modes of operation of exhaust system 600, valve 630 is configured to selectively move based on a determined throttle valve position by throttle valve position sensor 588. In some modes of operation of the exhaust system 600, the valve 630 is configured to selectively move based on the rate of change of the throttle valve position or the degree of opening of the throttle valve 39, as determined by the throttle valve position sensor 588.

[0157] As schematically illustrated in FIG. 8 and as will be described in more detail below, the system controller 500 is further coupled to an exhaust pressure sensor 590 to sense the back pressure of the engine 26. Back pressure, also known as exhaust gas pressure, should be understood as the resistance to flow of exhaust gas between engine 26 and muffler outlet 650. due, at least in part, to the curvatures, bends, obstructions, turns, and sharp edges present in the various components of the exhaust system 600. In the present technology, reducing the back pressure can help optimize the performance of the engine 26, since high back pressure can adversely affect the performance of the engine. Reducing the backpressure value in exhaust system 600 may also have the effect of reducing so-called "turbine lag", which is the delay in response of a turbocharged engine after the throttle lever 86 has been moved to operate the throttle system.

[0158] In the exemplary embodiment, the exhaust pressure sensor 590 is located near the outlet 206 of the exhaust pipe 202. It is contemplated that the exhaust pressure sensor 590 may be placed in various ways, depending on the details of the particular embodiment. In some embodiments, system 600 may further comprise a differential sensor for detecting a pressure difference between intake air pressure entering engine 26 and exhaust pressure for exhaust gas leaving engine 26. It is also contemplated that, in some embodiments, a differential sensor may replace one or both of the intake pressure sensor 504 and the exhaust pressure sensor 590.

[0159] As also illustrated in FIG. 8, the system controller 500 is further connected to several sensors to monitor various components of the exhaust system. System controller 500 is communicatively coupled to exhaust pipe temperature sensor 512 to sense the temperature of exhaust pipe 202. Similarly, system controller 500 is communicable to muffler temperature sensor 550 to sense muffler temperature 650. These sensors 512, 550 can be applied to monitor possible overheating or temperature imbalance, and to provide information to the system controller 500 for use in control methods such as those described herein. To determine the engine speed for engine 26, system controller 500 is further communicatively coupled to engine sensor 586 located in communication with engine 26.

[0160] Exhaust system 600 further comprises an exhaust manifold 640 fluidly coupled to wastegate 620 and turbocharger 300. Exhaust manifold 640, shown alone in FIG. 20A-20C includes an inlet 642 through which the exhaust manifold 640 receives exhaust gas from both the bypass pipe 620 and the exhaust gas turbine 350.

[0161] More specifically, inlet 642 receives exhaust gas that bypasses exhaust gas turbine 350 and exits through outlet 626 of bypass pipe 620. Inlet 642 also receives exhaust gas that has passed through exhaust gas turbine 350. gases, from the outlet 315 of the housing 302 of the turbocharger. The inlet 642 comprises two parts: a lower portion 643 and an upper portion 645. The lower and upper portions 643, 645 are integrally connected to define a peanut-shaped opening in the inlet 642. It is contemplated that, depending on the embodiment, the inlet 642 may be different shape.

[0162] The lower portion 643 is hydraulically connected to the housing 302 for receiving exhaust gas therethrough from the exhaust gas turbine 350 through an exhaust port 315. bypassed the turbine 350, running on exhaust gases. The exhaust manifold 640 also includes an outlet 646 through which the exhaust gas passed into the exhaust manifold 640 exits. It is contemplated that the two inlet portions 643, 645 may be separated in some embodiments such that exhaust manifold 640 may, for example, be generally Y-shaped.

[0163] Exhaust manifold 640 is bolted to housing 302 and bypass 620 using through holes 641 defined in the outer boundary of inlet 642. It is contemplated that exhaust manifold 640 may be coupled to housing 302 in various ways in various embodiments. turbocharger and bypass pipe 640. It is also contemplated that exhaust manifold 640 may be integrally formed with bypass pipe 620 and/or turbocharger housing 302.

[0164] Referring to FIG. 10, exhaust system 600 includes a silencer 650. Silencer 650 includes a single silencer inlet 654 through which exhaust gas from exhaust system 600 is received. Silencer 650 is hydraulically connected to manifold outlet 646 of said exhaust manifold 640. Muffler inlet 654 and manifold outlet 646 are held in place by springs, as can be seen in the figures. It is contemplated that various methods may be used to connect muffler 650 to exhaust manifold 640. As can be seen in the figures, muffler 650 includes only one inlet 654 to receive exhaust gas both bypassing and passing through exhaust gas turbine 350.

[0165] The flow of exhaust gas through exhaust system 600, and more specifically between exhaust pipe 202 and muffler 650, will now be described in more detail below. As described briefly above, the valve 630 in the bypass pipe 620 selectively controls the flow of exhaust gas either entering the exhaust gas turbine 350 or bypassing the exhaust gas turbine 350 by discharging exhaust gas through the outlet portions 692, 694 of the pipe .

[0166] In the present technology, the bypass pipe 620 is designed and located to balance two competing interests: the first is to allow efficient exhaust gas flow while bypassing the turbocharger 300 to drive the engine 26 as a naturally aspirated engine 26, and the second is not to interfere with efficient operation turbocharger 300 when required. In traditional turbocharged engines, all of the exhaust gas could be routed to the turbocharger 300, with an appropriate bypass being used only if there is too much exhaust gas flow to the turbocharger. In the proposed technology, the exhaust gas may be directed either to the turbocharger 300 bypass for naturally aspirated operation or to the turbocharger 300 for supercharged operation. Inclusion of the intake bypass valve 123 further assists in allowing naturally aspirated or supercharged operation of the engine 26. As described above, the intake bypass valve 123 allows atmospheric or ambient air flow to enter the primary air intake 120 when the pressure in the primary air intake 120 falls below a threshold during turbocharger 300 not operating or spinning up and thus not providing enough compressed air to primary air intake 120. By activating both valve 630 and bypass valve 123, each of which operates independently, both intake air and exhaust gas , arranged to enable the operation of the engine 26 naturally aspirated or supercharged.

[0167] As mentioned above, the exhaust gas entering the bypass 620 flows generally parallel to the central axis 629 of the inlet 622. As can be seen in FIG. 13-16, the central axis 629, and thus the center of the exhaust gas flow, is directed towards the turbine outlet portion 692 of the flow divider 628. Since the flow divider 628 is located towards the bypass side with respect to the central axis 629, it should be understood that more than half of the exhaust gas flow is initially directed through it towards the turbine outlet 692.

[0168] On the side of the bypass outlet 694 of the central axis 629 (to the left of the axis 629 in the figures), it can also be seen that some of the exhaust gas flow parallel to the central axis 629 is directed to the opening 627. Since the inlet 622 of the nozzle and the opening 627 of the passage 625 are at least partially aligned along the direction of the central axis 629, then at least part of the exhaust gas entering the inlet 622 of the nozzle is parallel to the axis of the flow flowing freely into the bypass passage 625 when the valve 630 is in the open position. Since the engine 26 is designed to operate naturally under normal operation, at least a portion of the exhaust gas flowing generally directly through the bypass pipe 620 into the exhaust manifold 640 with a minimum number of turns, bends, etc., further contributes to the reduction of back pressure, again to optimize engine performance.

[0169] It should be noted that, as will be described further below, the percentage flow of exhaust gas towards each of the exhaust ports 692, 694 does not necessarily correspond to the percentage exhaust gas that flows through them.

[0170] The two different patterns of exhaust gas flow entering the bypass 620 will now be described in more detail with reference to the flow paths 670, 675 schematically illustrated in FIG. 8. Depending on the position of the valve 630, the exhaust gas may flow along the bypass exhaust gas flow path 670, the exhaust gas turbine path 675, or a combination of the two streams 670, 675.

[0171] The exhaust gas flowing along the bypass path 670 of the flow of exhaust gas is passed through the passage 625, which is not blocked by the valve 630, when the valve 630 is in the open position. The bypass path 670 of the exhaust gas flow is defined from the inlet 622 of the bypass pipe 620 to the collector 640 of the exhaust gases. The exhaust gas flowing along the exhaust gas bypass path 670 is passed through the exhaust gas inlet 622, then through the bypass pipe 620, and then into the exhaust manifold 640. More specifically, the exhaust gas flowing along the exhaust gas bypass path 670 is received at the top 645 of the inlet 642.

[0172] The exhaust gas turbine path 675 is likewise defined from the exhaust gas inlet 622 of the bypass pipe 620 to the exhaust manifold 640. The exhaust gas flowing along the second exhaust gas stream is passed through the exhaust gas inlet 622, then through the turbine outlet 692 of the bypass pipe 620, then through the exhaust gas turbine 350, and then into the exhaust manifold 640. More specifically, the exhaust gas flowing along the turbine exhaust gas flow path 675 is received at the bottom 643 of the inlet 642.

[0173] For each flow path 670, 675, exhaust gas exits manifold outlet 646 and into muffler inlet 654. One silencer inlet 654 of said silencer 650 receives exhaust gas from both the exhaust gas bypass path 670 and the exhaust gas turbine path 675 .

[0174] Although most of the exhaust gas flow is oriented toward the turbine outlet 692, most of the exhaust gas entering the exhaust inlet 622 flows along the bypass exhaust gas flow path 670, through the bypass exhaust 694 when valve 630 is in the open position. The flow path 675 through the exhaust gas turbine 350, designed to turn under the pressure of the exhaust gas flowing through it, is more restrictive and causes more back pressure than the flow path 670 through the bypass passage 625. Most of the exhaust gas is, therefore, directed through the passage 625, even if the initial flow direction is in the direction of the turbine outlet 692. It should be noted that part of the exhaust gas entering the bypass pipe 620 will still flow through the exhaust gas turbine 350, even when the valve 630 is completely open.

[0175] When the valve 630 is in the closed position, most (generally all) of the exhaust gas entering the exhaust gas inlet 622 flows along the turbine path 675 of the exhaust gas flow. As illustrated schematically, exhaust gas flowing along turbine exhaust gas flow path 675 is deflected by valve 630 when valve 630 blocks passage 625 in the closed position. Since some of the exhaust gas entering through the nozzle inlet 622 flows parallel to the central axis 629, at least a portion of the valve 630 contacts and diverts the exhaust gas entering the inlet 622.

[0176] As mentioned above, valve 630 may also be located in an intermediate position, such as illustrated in FIG. 16 (only as one non-limiting example). With the valve 630 in an intermediate position, part of the exhaust gas is allowed to flow through passage 625 to bypass the exhaust gas turbine 350, and part of the exhaust gas is reflected through the turbine outlet 692 towards the exhaust gas turbine 350. In an intermediate position, at least a portion of valve 630 is in contact with exhaust gas entering through nozzle inlet 622 and flowing parallel to axis 629.

[0177] The exhaust gas thus flows along both the bypass exhaust gas flow path 670 and the exhaust gas turbine path 675 when the valve 630 is in one of the intermediate positions. The ratio of the portion of the exhaust gas flowing along the bypass path 670 of the exhaust gas flow to the portion of the exhaust gas flowing along the turbine path 675 of the exhaust gas flow depends on various factors, including at least the angle at which the valve 630 is located. In general, the closer valve 630 is towards the open position, the more exhaust gas will flow along the exhaust gas bypass path 670 and vice versa.

[0178] As will be described in more detail below, the valve 630 is used to organize the flow of exhaust gas through the path 670, 675 flow. For example, in some scenarios, valve 630 is configured to selectively move to a closed position (or toward a closed position) when engine 26 is operating below a threshold atmospheric pressure. In such a scenario, the turbocharger 300 may be used to assist supercharged engine performance as the snowmobile 10 climbs above sea level where the air is thinner and therefore less oxygen is supplied to the engine 26 (detrimental to performance).

[0179] As for the position of the valve 630 in this embodiment, there is no physical barrier blocking the flow of air between the exhaust gas inlet 622 and the turbine inlet 355. As mentioned above, part of the exhaust gas entering through the bypass inlet 622 is passed through the turbine outlet 692 and enters the exhaust gas turbine 350 through the turbine inlet 355 even when the valve 630 is in the open position. The relatively small portion of the exhaust gas entering the exhaust gas turbine 350 contributes to creating a pressure difference between upstream and downstream of the exhaust gas turbine 350 . This pressure difference generally improves the response of the turbocharger 300, generally causing the exhaust gas turbine 350 to spin faster and helping to reduce turbine lag.

[0180] Likewise, there is no physical barrier to closing the turbine outlet 315 when the exhaust gas flows along the bypass path 670 of the exhaust gas flow. Thus, the exhaust gas flow exiting the bypass outlet 626 causes a reduction in air pressure in the turbine outlet 315. This low pressure zone also helps to reduce turbine lag and increase spin-up speed. It should also be noted that there is also no barrier to closing the bypass outlet 626 when the exhaust gas is directed into the turbine exhaust gas flow path 675 and flows out of the turbine outlet 315.

[0181] The exhaust system 600 in accordance with the proposed technology and as described above is generally designed to operate as a naturally aspirated engine system, with the exhaust gas generally bypassing the exhaust gas turbine 350, except in specific scenarios where additional boost from turbocharger 300 is optional. This differs from some standard turbocharged engine layouts where a turbocharger is used in standard operation and a turbocharger bypass is used to prevent compressor overload.

[0182] In the layout and arrangement of the exhaust system 600 according to the proposed technology, unlike conventional turbocharger layouts, most of the exhaust gas flows through the passage 625 when the valve 630 is in the open position (described above). The flow of the exhaust gas, especially to allow the gas to bypass the turbocharger 300 without creating excessive back pressure, is further organized with comparable cross-sections of the two flow paths 670, 675. More specifically, in the proposed technology, the opening area 627 of the passage 625 (for the bypass flow path 670) and the intake area 354 of the exhaust gas turbine 350 (in the turbine flow path 675) are similar dimensions.

[0183] The arrangement of the relative areas of the orifices 627, 355 in the two flow paths 670, 675 allows the exhaust gas to bypass the exhaust gas turbine 350 without creating excessive back pressure (which can be detrimental to the operation of the engine 26), while allowing good flow of exhaust gases through the turbine inlet 355 when a turbine 300 is required. According to the present technology, the area of the hole 627 is generally 0.75 to 1.25 times the area 354 of the turbocharger inlet 355. In the illustrated embodiment, the area 354 of the turbocharger inlet 355 is slightly larger than the area of the bore 627. However, it is contemplated that in some embodiments, the area of the bore 627 may be larger than the area 354 of the turbocharger inlet 355.

[0184] In addition, unlike conventional turbocharger arrangements, the bypass outlet 626 is specifically positioned so that there is no excessive deflection of exhaust flow required to pass flow from the bypass pipe inlet 622 to the bypass outlet 626. Normal to the bypass outlet 626. outlet 626 is at an angle of about 20 degrees to the central axis 629 in the illustrated embodiment (although the exact angle may vary). With this arrangement, a portion of the exhaust gas entering the inlet 622 illustrated between lines 601 and 603 in FIG. 15, both parallel to the central axis 620, will pass directly through the bypass 620, meaning through the passage 625 and opening 627, and leave the bypass outlet 626 without deflection. This is true for a variety of valve 630 positions between the fully open and fully closed positions.

[0185] When the snowmobile 10 is not operating below a threshold atmospheric pressure, the exhaust system 600 will tend to direct the exhaust gas along the exhaust gas bypass path 670, bypassing the exhaust gas turbine 350, and the engine 26 will operate as a naturally aspirated engine 26. When the snowmobile 10 is operating below a threshold intake air pressure, such as at high altitude/low atmospheric pressure, valve 630 will move towards a closed position (either partially or completely) to direct some or all of the exhaust gas to turbine 350 operating on the exhaust gases to provide pressurization to the engine 26. More detailed information regarding the operation of the valve 630 in relation to operating conditions will be provided below.

Exhaust system example

[0186] With reference to FIG. 31 and 32, one non-limiting illustrative scenario for the operation of release system 600 will now be described. Various embodiments of specific methods will be described in more detail with reference to FIGS. 21-23. It should be noted that this is only one non-limiting example to provide a high level understanding of the overall operation of the release system 600, and various embodiments and details will be set forth below.

[0187] In general terms, system controller 500 retrieves preset valve positions 630 from data tables (data sets) based on throttle position (TPS) and engine speed (RPM). Depending on the particular mode of operation (described further below), the exhaust pressure, intake pressure, or difference between the two is simultaneously monitored by comparing their values against similar predetermined pressure data sets. In FIG. 31 is a flowchart 950 generally depicting the steps performed by system controller 500 in controlling valve 630 in the illustrated illustrative scenario.

[0188] First, the controller 500 determines whether the snowmobile 10 is operating near sea level or closer to high altitude. Altitude (high or low) is generally determined by the intake pressure sensor 504 by measuring the pressure of the ambient air entering the air intake system, but in some cases the snowmobile 10 may include an altimeter communicatively connected to the system controller 500 to determine the height above sea level. The system controller 500 may then retrieve a predetermined set of valve position and pressure data corresponding to the operation of the snowmobile 10 at the appropriate altitude range. To avoid inaccurate altitude readings from the intake pressure sensor 504 caused by additional pressure generated by the turbocharger 300, altitude-related pressure readings are taken when the RPM and TPS outputs are below a predetermined level that corresponds to the operating state of the snowmobile 10, which should not be pressurized from the turbocharger 300. It should also be noted that datasets corresponding to different altitudes, other than low and high, may be used. Datasets corresponding to more than two altitudes are also provided.

[0189] Upon determining that the snowmobile 10 is either at high or low altitude, system controller 500 then determines whether valve 630 should be adjusted in accordance with the "coarse" adjustment mode or the "fine" adjustment mode. This determination is made by comparing the actual boost pressure (the current intake air pressure provided by the turbocharger 300) with a predetermined desired target boost pressure based on the TPS vs. RPM comparison data set. The actual boost pressure generated by the turbocharger 300 is determined by the intake pressure sensor 504. The desired target boost pressure for the current TPS and RPM values is determined from a predefined data set, such as the predefined target data set 975 for the desired target boost pressure shown in FIG. 32. When the actual boost from turbocharger 300 is within a predetermined range or threshold of desired boost target (eg, within 5, 10, 15 mbar of desired boost), fine mode will be used. Otherwise, coarse mode will be used. Depending on the particular embodiment, the preset range may be modified depending on factors such as ambient temperature, altitude, and so on. It should be further noted that the predetermined range for switching from the coarse mode to the fine mode may, in some cases, be different from the predetermined range for switching from the fine mode to the coarse mode. This hysteresis is introduced into the coarse/fine determination approach to help limit the rapid switching between these two control modes. If the threshold differences for switching between coarse and fine adjustment modes were the same, for example, each time the pressure difference was slightly below or above the threshold, the method could switch modes in rapid alternation between coarse and fine adjustment modes. This can be overly inefficient, especially when the differential pressure fluctuates around a threshold value.

[0190] When operating in coarse adjustment mode, also known as dynamic mode, backpressure is simultaneously monitored and adjusted according to the pressure data set to ensure that moving valve 630 to increase boost pressure does not cause an undesirable increase in backpressure. An exemplary pair of valve position data set 960 and pressure data set 970 is illustrated in FIG. 33 (values are merely illustrative and are not intended to be limiting). In the case where the pressure data set 970 is used in coarse mode, the output values will represent the maximum value of the difference between the outlet pressure and the inlet pressure, as will be described in more detail below.

[0191] During valve 630 control, if the back pressure rises above a certain value for the current operating conditions (eg, RPM and TPS), engine 26 performance may be adversely affected or at least not optimal. To avoid this, the representation of the maximum backpressure determined in the data set 970 from the current TPS and RPM values is compared with the actual backpressure determined from the exhaust pressure minus the intake pressure obtained from the exhaust pressure sensor 590 and the pressure sensor 504 respectively. inlet. If the actual backpressure exceeds the value in dataset 970, the system controller 500 will apply a valve position correction to dataset 960 to move valve 630 to a position that maintains the backpressure within the allowable range, i.e. the actual pressure difference is lower than that obtained from dataset 970 In some cases, a correction factor may be applied mathematically to the entire 960 dataset; in some embodiments, another predefined set of data 960 may be retrieved.

[0192] In fine tuning mode, fine tuning tables, also called static data sets, are used when there is little difference between the actual boost pressure and the desired boost pressure, as mentioned above. In contrast to the coarse adjustment approach, fine adjustment is performed to approximate and maintain optimum inlet pressure (boost pressure) to engine 26. can be constantly monitored, as in coarse tuning mode. As with coarse mode, fine mode uses a valve position dataset similar to the 960 dataset, which is based on actual TPS and RPM, and a pressure dataset similar to the 970 dataset, also based on actual TPS and RPM. . The pressure data set 970, when in fine mode, contains values that represent intake pressure only and which must be compared with the actual intake pressure measured by the intake pressure sensor 504. The difference between the output from data set 970 in fine mode and the actual inlet pressure will determine the correction factor that will be applied to the valve position from data set 970.

[0193] During operation, the system controller 500 continuously re-evaluates the altitude and coarse/fine determinations, as operation of the snowmobile 10 will cause changes in throttle and RPM positions, which will also change the exhaust and intake pressures when valve 630 is operated to improving the operation of the engine 26; and/or changing the altitude at which the snowmobile 10 operates as it travels through the terrain.

[0194] With reference to FIG. 21-23, various methods for controlling the flow of exhaust gas from engine 26 will be discussed. Each will be described in more detail below. Briefly, methods 700, 750, 800 aim to balance providing optimized boost to engine 26 based on operating conditions (in the form of compressed air supplied by turbocharger 300) against the detrimental increase in back pressure that can be caused when turbocharger 300 spins up. This control is provided by valve 630. As mentioned briefly above, operation of the exhaust system 600 with valve 630 assists in preventing back pressure preventing engine operation when the exhaust gas flows out through the bypass pipe 620. By closing the valve 630, the exhaust gas is directed to the turbine 350 operating on the exhaust gases so that the turbocharger 300 provides additional air to the engine 26, but this exhaust gas flow path 675 also increases backpressures. In some embodiments of the methods, adjustments may be made to position valve 630 to balance the need for additional compressed air against the negative effect on engine performance due to increased back pressure.

Operation based on pressure reading

[0195] The operation of the exhaust system 600 in accordance with the various techniques of the present technology will now be described in more detail below. With reference to FIG. 21, a non-limiting embodiment of control operations in exhaust system 600 is shown in the form of a method 700 for controlling exhaust gas flow from engine 26. Method 700 is performed by system controller 500 in accordance with the present technology. In some embodiments, it is contemplated that an additional or replacement computing system may be implemented to perform method 700.

[0196] Method 700 begins at 705 with at least one engine 26 pressure determined. Based on the one or more pressures sensed for engine 26, method 700 determines how to position valve 630 to optimize or improve engine 26 performance. described in more detail below, valve 630 may be positioned based on, but not limited to, exhaust pressure, intake air pressure, and/or atmospheric pressure, and desired or actual boost pressure.

[0197] Method 700 then continues at 720 with valve 630 moving to a closed position, an open position, or an intermediate position based on at least the pressure determined at 710. Depending on the determined pressure, valve 630 is moved to direct more or less the amount of exhaust gas to the exhaust gas turbine 350. In some cases, the desired position of valve 630 will match the current position of valve 630, and thus valve 630 will not be moved.

[0198] In some embodiments, determining the pressure in step 705 includes determining in sub-step 710 the pressure difference between the actual boost pressure of air flowing into engine 26 and a predetermined boost pressure of air flowing into engine 26.

[0199] In some embodiments, the determination of the differential pressure in sub-step 710 is performed in two sub-steps. The first actual boost pressure is determined in sub-step 712. The actual boost pressure is determined based on readings from the intake pressure sensor 504 to determine the pressure of the intake air coming from the turbocharger 300. However, it is contemplated that another method can be used to determine the actual boost pressure. sensor and/or operating value.

[0200] The preset boost pressure is determined in sub-step 714. The preset boost pressure is the boost pressure calculated or predetermined to match the overall operating conditions of the engine 26 so that the operation of the engine 26 is most optimized. The preset boost pressure is retrieved from a computer accessible storage medium 507 operatively connected to or included in the system controller 500 (shown schematically in FIG. 8). It is contemplated that additional sensors may be included in the exhaust system 600 and applied to the method 700.

[0201] In some embodiments, determining the predetermined boost pressure in sub-step 714 includes at least one of: determining, using engine sensor 586, engine speed for engine 26, determining throttle valve position for throttle valve 39 of engine 26 using sensor 588 throttle valve position, determining throttle position using throttle position sensor 86, and determining throttle valve opening degree for throttle valve 39. In some embodiments, throttle valve opening degree may be determined instead of or in addition to determining throttle valve position. The preset boost pressure is then retrieved from the application-based storage medium 507 based on the preset engine speed, throttle valve position, throttle lever position, and/or throttle valve opening degree.

[0202] It is contemplated that sub-steps 712, 714 may be performed in any order or simultaneously, depending on the particular embodiment and/or operating scenario. In some embodiments, it is contemplated that the snowmobile 10 may include a differential sensor to determine the differential pressure at sub-step 710 in a single measurement.

[0203] In some embodiments or iterations, method 700 may further include determining that the difference between the preset boost pressure and the actual boost pressure, as determined in sub-step 710, does not exceed a threshold difference. Threshold difference generally indicates whether valve movement 630 to more closely match actual boost pressure to predetermined boost pressure should be a coarse adjustment (if the difference is above a threshold) or only a fine adjustment (if the difference is below a threshold).

[0204] Based on the difference not exceeding the threshold difference, the method 700 then continues to determine the desired valve position 630 from the fine adjustment data set. A fine adjustment data set based on at least one of throttle position and engine speed, as defined above, refers to fine or small adjustments to valve position 630 necessary to provide desired pressure to engine 26 by reducing the difference between predetermined boost pressure and actual boost pressure. Method 700 then continues with moving valve 630 to the desired valve position following the determination of the desired valve position.

[0205] Based on the difference above the threshold difference, the method 700 then similarly proceeds to determine the desired valve position 630 from the coarse adjustment data set. A coarse adjustment data set based on at least one of throttle position and engine speed, as defined above, refers to coarse or large adjustments to valve position 630 necessary to maintain the desired pressure in engine 26 by reducing the difference between preset boost pressure and actual boost pressure. Method 700 then continues with moving valve 630 to the desired valve position following the determination of the desired valve position.

[0206] In some embodiments, method 700 can be iteratively performed such that when the difference between the preset boost pressure and the actual boost pressure becomes larger, a coarse adjustment is made to reduce said difference. As soon as the difference between preset and actual boost pressure falls below the specified threshold, fine adjustment will be applied. The use of coarse and fine adjustments is only one non-limiting example of controlling valve position adjustment 630. It is also contemplated that these adjustments may be divided into three or more sets of data. For example, two thresholds may be applied to separate said adjustments into "large coarse adjustments", "small coarse adjustments", and "fine adjustments". It is also contemplated that a single set of data can be used to determine the desired valve position.

[0207] In some embodiments or iterations of the method 700, determining the pressure difference in sub-step 710 includes determining the difference between the inlet air pressure for air flowing into the engine 26 and the exhaust gas pressure flowing from the engine 26, instead of determining the difference between a predetermined and actual boost pressure. In such an embodiment, the method 700 would then include determining the intake air pressure using the intake pressure sensor 504 and determining the exhaust gas pressure using the exhaust pressure sensor 590.

[0208] The method 700 will then further include determining a predetermined pressure difference between the exhaust gas pressure and the intake air pressure. Similar to the predetermined boost pressure, the predetermined pressure difference corresponds to the optimum or preferred difference between the exhaust and intake air pressures that correspond to the best performance of the engine 26 for the current operating conditions. For example, a predetermined differential pressure may be set based on engine parameters, such as engine speed, so that engine 26 as a whole has the amount of air needed to function properly without creating too much back pressure. In some embodiments, a predetermined differential pressure may be determined based on, but not limited to, throttle position and engine speed.

[0209] In such an embodiment, method 700 then continues with determining that the difference between the pressure difference and the predetermined pressure difference is non-zero. A non-zero difference simply indicates that the actual pressure difference is not at the predetermined pressure difference, and thus the engine 26 cannot operate normally. Method 700 thus then continues with movement of valve 630 on a non-zero basis to an open position, a closed position, or one of the intermediate positions. In some embodiments, the position to which valve 630 moves may depend on an actual pressure difference greater than or less than a predetermined pressure difference.

[0210] In some embodiments or iterations of method 700, method 700 includes determining that intake air pressure is below a threshold atmospheric pressure. As in the case of the above steps, determining the intake air pressure includes measuring the pressure using the intake pressure sensor 504. System controller 500 may then determine if the measured air pressure for air entering engine 26 is below some predetermined threshold. For example, said threshold may be set based on engine parameters such that engine 26 as a whole has the amount of air required for proper operation. It is also contemplated that the threshold atmospheric pressure may be a predetermined range of atmospheric pressure. In one non-limiting example, the intake air pressure may drop below a specified threshold as the snowmobile 10 climbs a mountain and the altitude increases.

[0211] Then, based on at least the intake air pressure being below the threshold atmospheric pressure, method 700 can continue with valve 630 moving towards or towards the closed position (if valve 630 is either in the open or in between position) . This will start or increase the operation of the turbocharger 300. Thus, when the engine 26 is not receiving enough air to operate well or adequately, such as when the snowmobile 10 is in operation at high altitude, the turbocharger 300 may be spun to provide compressed air to the engine 26 (as described above).

[0212] In some embodiments or iterations of method 700, method 700 may further include determining that the backpressure is too high and increasing the opening of valve 630 to maintain a balance between the increased inlet air pressure to engine 26 and allowing the backpressure to decrease through the orifice. valve 630.

[0213] Next is movement of the valve 630 in or towards a closed position, the method 700 may further include determining that the exhaust gas pressure is above a threshold exhaust gas pressure. As mentioned above, the exhaust gas pressure is measured by the exhaust pressure sensor 590; wherein the system controller 500 then compares said measurement with a determined backpressure threshold.

[0214] Based on the exhaust gas pressure exceeding the exhaust gas threshold pressure, method 700 then continues with repositioning valve 630 to either an open position or an intermediate position so that exhaust gas flows partially along exhaust gas bypass path 670. By increasing the opening of the valve 630 so that an increased portion of the exhaust gas flows out through the bypass portion 620, the back pressure is reduced. Depending on the specified iteration of method 700, valve 630 may only be moved through a small angle, or in some cases moved to the open position. In some embodiments, the change in position of valve 630 may be proportional to, or directly related to, an increase in exhaust gas pressure after valve 630 has been moved to the closed position.

[0215] In some embodiments or iterations of method 700, valve 630 may be moved back to the open position as soon as snowmobile 10 is operating at atmospheric pressures below the threshold applied above to initiate use of turbocharger 300. In one non-limiting example, valve 630 may be opened back to partially or fully open position when the snowmobile 10 decreases in altitude and the atmosphere surrounding the snowmobile 10 becomes richer.

[0216] In such a scenario, method 700 may further include determining (via intake pressure sensor 504 and system controller 500) that intake air pressure is above a threshold intake air pressure, then moving valve 630 in or toward closed position. Then, based on the intake air pressure exceeding the threshold intake air pressure, method 700 may continue with valve 630 moving such that most or most of the exhaust gas flows along the exhaust gas bypass path 670.

[0217] It is contemplated that method 700 may include additional or different steps, or perform additional functions and/or perform the steps described above. It is also contemplated that the steps described above may be performed in a variety of different sequences, depending on, for example, user preferences, and are not limited to the order set forth in the explanation above.

Operation based on exhaust gas pressure

[0218] With reference to FIG. 22, a non-limiting embodiment of control operations in exhaust system 600 is shown in the form of method 750. Method 750 is performed at least in part by system controller 500 in accordance with the present technology. In some embodiments, it is contemplated that an additional or replacement computing system may be implemented to perform method 750.

[0219] Method 750 begins at 760 by determining that the exhaust gas pressure for air flowing from engine 26 exceeds the exhaust gas threshold pressure where valve 630 is either in the closed position or in an intermediate position where most of the exhaust gas flows along the turbine path 675 of the exhaust gas flow. The exhaust gas pressure is determined by the exhaust pressure sensor 590 and the system controller 500 in the present embodiment, as noted above. In some embodiments, valve 630 may be moved to a closed position based on a decrease in atmospheric pressure surrounding snowmobile 10, similar to the scenario described above with respect to method 700. It is also contemplated that valve 630 may be moved into or toward the closed position in another manner. reason. For one non-limiting example, valve 630 may be moved to a closed position to provide more air to engine 26, via air compressor 310, based on insufficient performance of engine 26.

[0220] Method 750 then continues at 760 with valve 630 moving either to the open position or towards the open position to an intermediate position based on the exhaust gas pressure being greater than the exhaust gas threshold pressure.

[0221] It is contemplated that method 750 may be performed in tandem/in series with method 700, operation of snowmobile 10 may include embodiments of both methods 700, 750.

[0222] It is contemplated that method 750 may include additional or different steps, or perform additional functions and/or perform the steps described above. It is also contemplated that the steps described above may be performed in a variety of different sequences, depending on, for example, user preferences, and are not limited to the order set forth in the explanation above.

Operation based on engine speed and throttle position

[0223] With reference to FIG. 23, another non-limiting embodiment of control operations in exhaust system 600 is presented in the form of a method 800 for controlling exhaust gas flow from engine 26. Method 800 is performed by system controller 500 in accordance with the present technology. In some embodiments, it is contemplated that an additional or replacement computing system may be implemented to perform method 800.

[0224] In addition to controlling the position of valve 630 to adjust intake and exhaust pressures based on ambient conditions (i.e., atmospheric pressure), exhaust system 600 is further operable to control exhaust gas flow for balancing, providing additional boost when limiting back pressure, when the user of the snowmobile 10 requests additional power from the snowmobile 10.

[0225] In one non-limiting scenario, method 800 may be performed in a situation where throttle lever 86 is moved to fulfill a power increase request for engine 26, such as during snowmobile 10 accelerating. As will be described in the steps below, valve 630 moves to a closed position to spin up turbocharger 300 in response to this movement of throttle lever 86. Through the use of turbocharger 300, engine 26 will then benefit from tighter intake air and will have increased power output compared to a similar engine that would be naturally aspirated. As will be further discussed below, requesting too much boost and directing all of the exhaust gas along the turbine exhaust gas flow path 675 may also cause back pressure to rise beyond an optimized level for desired engine operation. In such a situation, method 800 may further move valve 630 back toward the open position to allow some exhaust gas to bypass exhaust gas turbine 350, thereby reducing back pressure.

[0226] Method 800 begins at step 810 with determining, using engine sensor 586, the engine speed for engine 26. Method 800 then continues at step 820, with determining the position of the throttle valve for throttle valve 39 of engine 26. The position of throttle valve 39 is sensed by the sensor 588 throttle valve position as mentioned above.

[0227] In some embodiments, step 820 may include determining a throttle valve opening degree for throttle valve 39 instead of or in addition to determining throttle valve position. In some embodiments, throttle valve position sensor 588, alone or in combination with system controller 500, may also be used to measure throttle valve opening. Depending on the particular embodiment, steps 810, 820 may be performed either in order or simultaneously.

[0228] Method 800 then continues at step 830 with valve 630 moving to an open position, a closed position, or any position in between based on the engine speed and throttle valve position determined at steps 810, 820, as well as the initial position of valve 630. In the method 800 throttle valve position is taken into account to help control the flow of exhaust gas to organize the operation of the engine 26.

[0229] In some embodiments or iterations, method 800 may further include moving valve 630 based on exhaust pipe 202 temperature in addition to engine speed and throttle valve position determined in steps 810, 820. The temperature of exhaust pipe 202 is received by system controller 500 from a sensor 512 temperatures. In some embodiments, the movement of the valve 630 may additionally or alternatively be based on the exhaust gas temperature within the exhaust pipe 202 sensed by the temperature sensor 512.

[0230] In some embodiments, the implementation of the method 800 may further include determining the pressure difference and further move the valve 630 based on the specified pressure difference. In some embodiments, the differential pressure is determined by comparing the preset boost pressure for air flowing into engine 26 with the actual boost pressure for air flowing into engine 26. The preset boost pressure, described in more detail above, is determined based on at least one of throttle position and engine speed as determined in steps 810, 820 and corresponds to how much boost pressure should flow into engine 26 based on throttle position and/or engine speed. The actual boost pressure of the air flowing into the engine 26 is determined by measuring the intake air pressure using the intake pressure sensor 504 and the system controller 500 as described above. In some embodiments, the actual boost pressure may be determined in various ways.

[0231] In some embodiments, method 800 may further include determining whether engine 26 is operating at low altitude or high altitude (i.e., whether snowmobile 10 is operating at low altitude or high altitude). sea) until valve 630 is moved. In some embodiments, determining whether engine 26 is operating at low altitude or high altitude includes determining atmospheric pressure for the air entering the snowmobile using intake pressure sensor 504 . It is also contemplated that the system controller 500 may be included or communicatively coupled to an altimeter or similar altitude measurement device.

[0232] Upon determining that engine 26 is operating at low altitude, method 800 may then continue to extract the desired valve position for valve 630 from the low altitude data set. Upon determining that engine 26 is operating at high altitude, method 800 may then similarly continue to extract the desired valve position for valve 630 from the high altitude dataset. In some embodiments, a low altitude data set and a high altitude data set may be stored on a storage medium 507 communicatively coupled to or part of the system controller 500.

[0233] The desired valve position extracted from the low or high altitude dataset generally corresponds to an optimized or predetermined valve position based on altitude and engine speed and/or throttle position such that airflow to the engine 26 is consistent with the operating conditions of the engine 26. In such an embodiment, having a certain desired position of the valve 630, the movement of the valve 630 at step 830 could be performed by moving the valve 630 to the desired position.

[0234] In some embodiments or iterations, method 800 may further include determining, based at least on the throttle position and engine speed determined in steps 810, 820, a threshold engine differential pressure 26. Method 800 then continues with determining the actual engine differential pressure 26. In some embodiments, determining the actual pressure difference includes determining the exhaust pressure downstream of the engine 26 using the exhaust pressure sensor 590, determining the intake air pressure upstream of the engine 26 using the intake pressure sensor 504, and determining their difference .

[0235] Method 800 then continues with determining that the actual pressure difference is greater than the threshold pressure difference; and moving the valve 630 towards the open position if the valve 630 is either in the closed or intermediate positions. In such a case, an actual pressure difference that is greater than the threshold pressure difference may indicate that there is too much air pressure moving into engine 26. This can be detrimental to the operation of engine 26, and method 800 can thus provide a correction. by allowing more exhaust gas to bypass the exhaust gas turbine 350 by moving valve 630 further towards the open position.

[0236] In some embodiments or iterations, the method 800 may further include determining that the intake pressure, as determined by the intake pressure sensor 504, is above an intake threshold, and determining that the throttle valve position is outside the position threshold. valve. For example, method 800 may determine that there is too much air pressure moving into engine 26 while throttle valve 39 has been opened too far. This combination can be detrimental to the operation of engine 26, and method 800 can provide a correction by allowing more exhaust gas to bypass exhaust gas turbine 350 by further moving valve 630 towards the open position.

[0237] Based on intake pressure and throttle valve position exceeding their respective thresholds, valve 630 may then be moved from a closed position or from an intermediate position towards an open position. This provides an opportunity to reduce the back pressure caused either by too much air intake or by requesting too much thrust.

[0238] In some embodiments or iterations, method 800 may further include moving valve 630 toward a closed position, after moving valve 630 toward an open position, so that a portion of the exhaust gas flowing through exhaust gas turbine 350 is increased, turbocharger 300. In such embodiments, method 800 provides some adjustment of the exhaust gas flow to balance boost from turbocharger 300, while limiting the detrimental effects of increased back pressure, which aids in smoothly increasing engine 26 power.

[0239] In some embodiments or iterations, method 800 may further include determining that the intake pressure is above an intake air pressure threshold, and then moving the valve toward a closed position. Method 800 may then include moving valve 630 toward an open position based on an inlet pressure greater than a specified threshold.

[0240] In some embodiments or iterations, method 800 may further include determining that the inlet pressure is less than an inlet pressure threshold, and then moving the valve toward a closed position. Method 800 may then further include moving valve 630 further toward a closed position to allow additional boost from turbocharger 300.

[0241] In some embodiments, determining intake air pressure may include determining intake pressure at a location downstream of turbocharger 300 using a pressure sensor (not shown). The valve movement may then include selective valve movement based on the intake pressure determined by the downstream pressure sensor from the turbocharger 300.

[0242] In some embodiments, method 800 may further include determining exhaust pressure downstream of engine 26 with exhaust pressure sensor 590 and moving valve 630 towards an open position based on exhaust pressure exceeding a predetermined pressure threshold at release.

[0243] In some embodiments, where a throttle valve opening degree is determined, method 800 may further comprise determining that the throttle valve opening degree is greater than a threshold degree; and moving the valve 630 towards an open position based on at least a throttle valve opening degree greater than a threshold degree. In such an embodiment, valve 630 opens fully, for example, when too much thrust is required too quickly to prevent back pressure from adversely affecting engine operation (especially when the user attempts to increase power from engine 26). In some embodiments, the method 800 may further include determining that the inlet pressure is greater than the threshold inlet pressure and moving the valve 630 based on both the throttle valve opening degree greater than the threshold degree and the inlet pressure greater than the threshold inlet pressure.

[0244] It is contemplated that method 800 may include additional or different steps, or perform additional functions and/or perform the steps described above. It is also contemplated that the steps described above may be performed in a variety of different sequences, depending on, for example, user preferences, and are not limited to the order set forth in the explanation above.

[0245] As described above, various methods of controlling the operation of the turbocharger 300 include monitoring the back pressure affecting the engine 26. Due to the availability of pressure information in the proposed technology, the performance of the snowmobile 10 can be further optimized by making adjustments to the fuel/air mixture in the engine 26.

[0246] Changes in backpressure in engine 26 and exhaust system 600 affect the fuel-to-air ratio present in engine 26. All else being equal, engine 26 receives maximum power when the target backpressure is maintained. If the effective back pressure in engine 26 deviates from this target value, the fuel to air ratio is affected, which in turn reduces engine 26 performance.

[0247] As the back pressure decreases, the total amount of air flowing through the engine 26 decreases. In such circumstances, a constant amount of fuel injected will result in an increase in the fuel to air ratio in the engine 26, and as such, the engine 26 will be supplied with an overly rich air/fuel mixture. Thus, motor 26 may not operate optimally.

[0248] Too much backpressure reduction at high engine speed, other things being equal, would also lead to an increase in the fuel-to-air ratio. When the back pressure is too low, the pressure waves created by the exhaust pipe 202 (which help create a trapping effect to keep the air in the two-stroke engine) can be out of time and the combustion chambers of the engine 26 are emptied of more air than would be optimal. In such a case, engine 26 will again receive a richer air/fuel mixture (getting the same amount of fuel with less air). As in the previous case, the engine 26 may not operate optimally.

Supply of fuel-air mixture

[0249] With reference to FIG. 24 and 33, a method 900 for supplying an air/fuel mixture to the engine 26 of the snowmobile 10 will now be described.

[0250] Method 900 begins at step 910 by determining the pressure difference between the intake air pressure for air flowing to engine 26 and the exhaust gas pressure for exhaust gas flowing from engine 26. This pressure difference, as mentioned above, with respect to dynamic mode, generally correlates with the back pressure in the engine 26. The pressure difference is determined by comparing, using the system controller 500, the measurements from the intake pressure sensor 504 and the exhaust pressure sensor 590. In some embodiments, it is contemplated that the snowmobile 10 may include a differential sensor for detecting pressure differences in one dimension.

[0251] In some embodiments of the method 900, the differential pressure is determined in two steps. More specifically, by determining the intake air pressure using the intake pressure sensor 504 in sub-step 912. The method 900 then continues with determining the exhaust gas pressure using the exhaust pressure sensor 590 in sub-step 914. Depending on the particular embodiment, steps 912, 914 may be performed in any order or at the same time.

[0252] Method 900 continues at 920 to determine the amount of fuel to be injected into engine 26 based on at least the indicated pressure difference (as determined at 910). The system controller 500 calculates the amount of fuel to be injected such that the air/fuel mixture is maintained at an appropriate value based on at least the back pressure in the engine 26. It is contemplated that another computation may be included to organize the determination of the amount of fuel to be injected. the system and not the system controller 500. The amount of base fuel injected is determined using a dataset related to the amount of fuel to be injected corresponding to the current TPS and RPM. An example of a data set 982 for a base injection fuel is shown in FIG. 34, where the base fuel injected is given as a volume, in this example in mm ³ .

[0253] In some embodiments, the amount of base fuel injected may be modified in accordance with the back pressure as indicated below. Target backpressure (exhaust pressure minus inlet pressure) is determined from a dataset for TPS and RPM, such as the example dataset 984. Actual backpressure is derived from exhaust pressure minus inlet pressure using the exhaust pressure sensor 590 and inlet pressure sensor 504, respectively.

[0254] The amount or percentage of fuel trim will then be derived from data set 986 for fuel trim from RPM and the difference between the actual backpressure and the target backpressure (referred to as DDR). The fuel trim from this data set 986 will then be applied to the base fuel injection amount to determine the final injection amount modified according to the measured back pressure.

[0255] Method 900 then ends at 930 with injecting an amount of fuel (as determined at 920) into engine 26. Fuel is injected by fuel injectors 41 as described above.

[0256] It is contemplated that, in some embodiments, method 900 may resume after step 930. In some embodiments, method 900 may continue beyond step 930 with the changed differential pressure determined. Method 900 may then continue to determine the corrected amount of fuel based on the changed differential pressure. This embodiment of method 900 may then end with the adjusted amount of fuel injected into engine 26.

[0257] In some embodiments, method 900 may include determining that the differential pressure has increased, determining a reduced amount of fuel to be injected, and injecting the reduced amount of fuel into engine 26. In some embodiments, method 900 also includes determining that the differential pressure decreased, determining that the pressure difference has decreased; determining the reduced amount of fuel to be injected and injecting the reduced amount of fuel into the engine 26.

[0258] In some embodiments, method 900 is repeated after step 930 at some predetermined time interval to readjust the air-fuel mixture to compensate for changes in backpressure. In some embodiments, method 900 may be periodically performed by system controller 500 while the snowmobile 10 is operating. It is also contemplated that method 900 may be performed only once or only a few times during operation of the snowmobile. It is also further contemplated that method 900 can be performed in response to pressure differences and/or inlet or outlet pressures passing a predetermined threshold.

[0259] In some embodiments, method 900 may further include determining engine speed, and determining the amount of fuel to be injected, also based on engine speed. In some embodiments, the method 900 may further include determining the throttle position of the throttle valve 39, and determining the amount of fuel to be injected further based on the throttle position.

[0260] It is also further contemplated that additional variables may be taken into account when determining or calculating the amount of fuel to be injected, in addition to the pressure difference. This may include, but is not limited to: engine speed (rpm), throttle position, air temperature, ambient barometric pressure, wideband closed loop lambda control, and exhaust gas temperature.

[0261] It is contemplated that method 900 may include additional or different steps, or perform additional functions and/or perform the steps described above. It is also contemplated that these steps may be performed in a variety of sequences, depending on the particular embodiment.

[0262] A person skilled in the art can understand the modifications and changes in the above described embodiments of the proposed technology. The above description is intended by way of example and not as a limitation. Thus, the scope of the present technology should not be limited strictly by the scope of the appended claims.

Claims (105)

1. Snowmobile, comprising: frame; at least one ski connected to the frame; a frame-mounted engine, the engine comprising an engine air inlet and an engine outlet; an exhaust pipe hydraulically connected to the engine outlet; a turbocharger hydraulically connected to the exhaust pipe, the turbocharger comprising: exhaust gas turbine and a housing accommodating an exhaust gas turbine; a bypass located downstream of the housing and in fluid communication with the housing, the bypass having an exhaust gas inlet hydraulically connected to the exhaust pipe; a valve located in the bypass pipe for selectively controlling the flow of exhaust gas through the turbocharger, the valve being selectively movable between at least a first position and a second position; And an exhaust gas collector hydraulically connected to the turbine housing and a bypass pipe for receiving an exhaust gas flow from it, a first exhaust gas flow path defined from the exhaust gas inlet to the exhaust gas manifold, wherein the exhaust gas flows along the first exhaust gas flow path, passing through the exhaust gas inlet, then through the overflow pipe, and then into the exhaust gas manifold, a second exhaust gas flow path defined from the exhaust gas inlet to the exhaust manifold, wherein the exhaust gas flows along the second exhaust gas flow path through the exhaust gas inlet, then through the bypass, then through the exhaust gas turbine , and then to the exhaust manifold, wherein in the first valve position, at least a majority of the exhaust gas flows along the first exhaust gas flow path, and in the second position of the valve, at least most of the exhaust gas flows along the second exhaust gas flow path. 2. Snowmobile according to claim 1, characterized in that the valve is selectively moved to the second position when the engine is operating below a threshold atmospheric pressure. 3. Snowmobile according to claim 1, characterized in that: the valve is further configured to selectively move to at least one intermediate position between the first and second positions; And in at least one intermediate position, the exhaust gas flows along both the first exhaust gas flow path and the second exhaust gas flow path. 4. Snowmobile according to claim 1, characterized in that: the turbocharger further comprises an air compressor hydraulically connected to the engine air inlet; And the snowmobile further comprises an air intake system hydraulically connecting the atmosphere to the engine, the air intake system comprising: air compressor, and engine air inlet. 5. Snowmobile according to claim 1, characterized in that: the exhaust manifold comprises one manifold outlet; And the snowmobile further comprises a muffler fluidly coupled to the manifold outlet, the muffler receiving exhaust gas from both the first exhaust gas flow path and the second exhaust gas flow path through the manifold outlet. 6. Snowmobile according to claim 1, characterized in that: the exhaust manifold comprises a manifold outlet; And the snowmobile further comprises a muffler hydraulically connected to the manifold outlet, the muffler comprising one muffler inlet to receive exhaust gas from both the first exhaust gas flow path and the second exhaust gas flow path through the manifold outlet. 7. Snowmobile according to claim 1, characterized in that the exhaust manifold contains: at least one inlet for receiving an exhaust gas stream, the at least one inlet comprising: a first portion for receiving exhaust gas flowing along the first exhaust gas flow path; And a second part for receiving exhaust gas flowing along the second exhaust gas flow path, wherein said first part and said second part are integrally connected. 8. Snowmobile according to claim 1, characterized in that the engine contains: throttle valve, and a throttle valve position sensor operatively connected to the throttle valve; And said valve is configured to selectively move based at least on the position of the throttle valve as determined by the throttle valve position sensor. 9. Snowmobile according to claim 1, characterized in that the engine contains: throttle valve, and a throttle valve position sensor operatively connected to the throttle valve; And said valve is configured to selectively move based at least on the rate of change of the throttle valve position, the rate of change being determined by the throttle valve position sensor. 10. Snowmobile according to claim 1, characterized in that: the bypass pipe includes a passage through which the exhaust gas flows when flowing along the first flow path of the exhaust gas; the exhaust gas turbine comprises a turbine inlet through which exhaust gas flows while flowing along the second exhaust gas flow path; And the cross-sectional area of the passage is greater than the cross-sectional area of the turbocharger turbine inlet. 11. The snowmobile according to claim. 1, characterized in that the change in the direction of the exhaust gas flowing from the exhaust pipe outlet along the second exhaust gas flow path is greater than for the exhaust gas flowing from the exhaust pipe outlet along the first exhaust gas flow path bypassing the exhaust gas turbine. 12. Snowmobile, comprising: frame; at least one ski connected to the frame; a frame-mounted engine, the engine comprising an engine air inlet and an engine outlet; an exhaust pipe hydraulically connected to the engine outlet; a turbocharger hydraulically connected to the exhaust pipe, the turbocharger comprising: exhaust gas turbine and a housing accommodating an exhaust gas turbine; a bypass located downstream of the housing and in fluid communication with the housing, the bypass in fluid communication with the outlet of the exhaust pipe; a valve located in the bypass pipe for selectively controlling the flow of exhaust gas through the turbocharger by selectively closing the bypass passage within the bypass pipe, the valve having at least a bypass position for opening the bypass passage and directing the exhaust gas to bypass the exhaust gas turbine; And an exhaust gas collector hydraulically connected to the bypass pipe for receiving an exhaust gas flow therefrom, at least a portion of the exhaust manifold inlet is contained within an exhaust pipe outlet protrusion, the protrusion being formed along an axis perpendicular to the exhaust pipe outlet. 13. A turbocharger assembly for hydraulic connection to an exhaust pipe, comprising: turbocharger, containing: exhaust gas turbine and a housing accommodating an exhaust gas turbine; And a bypass pipe located downstream in front of the body and hydraulically communicating with the body, the bypass pipe comprising: a nozzle inlet for receiving exhaust gas from an exhaust pipe, wherein the nozzle inlet is defined by a bypass nozzle, wherein the nozzle inlet defines a flow axis through the center of the nozzle inlet, and the exhaust gas flowing into the nozzle inlet is generally parallel to said flow axis; a bypass passage defined by the bypass nozzle, the bypass passage forming a fluid connection between the nozzle inlet and the bypass outlet defined by the bypass nozzle; a valve located in the bypass pipe for selectively controlling the flow of exhaust gas through the bypass passage, and the valve is configured to selectively move between at least an open position and a closed position; And a turbocharger passage defined by a bypass pipe, wherein the turbocharger passage forms a hydraulic connection between the inlet of the nozzle and the exhaust gas turbine, moreover, the inlet of the nozzle and the inlet of the bypass passage are at least partially aligned in such a way that at least part of the exhaust gas entering the inlet of the nozzle is parallel to the axis of the flow flowing freely into the bypass passage when the valve is in the open position. 14. A turbocharger assembly according to claim 13, wherein when the valve is in the closed position, at least a portion of the valve is in contact with the exhaust gas entering through the inlet of the nozzle and flowing parallel to the flow axis. 15. Turbocharger assembly according to claim 13, characterized in that when the valve is in a position between the open position and the closed position, at least a portion of the valve is in contact with the exhaust gas entering through the inlet of the nozzle and flowing parallel to the flow axis. 16. Pipe for hydraulic connection with the turbocharger housing, containing: an inlet part of the pipe for receiving exhaust gas from the exhaust pipe; an inlet defined by an inlet portion of the pipe, wherein the exhaust gas enters the inlet portion of the pipe through said inlet, the inlet defining a central axis perpendicular to the inlet and passing through the center of the inlet; the first outlet part of the pipe; the second outlet part of the pipe; And a flow divider located between the first outlet of the nozzle and the second outlet of the nozzle, moreover, the flow divider is located between the specified central axis and one of: the first outlet part of the pipe and the second outlet part of the pipe, wherein the first outlet part of the pipe is hydraulically connected to the turbocharger located inside the turbocharger housing; the exhaust gas leaving the pipe through the second outlet part of the pipe bypasses the turbocharger; And the flow divider is located between the central axis and the second outlet part of the nozzle. 17. Branch pipe according to claim 16, characterized in that: the inlet part of the pipe, the first outlet part of the pipe and the second outlet part of the pipe are connected as a whole; And the inlet part of the pipe, the first outlet part of the pipe and the second outlet part of the pipe form a Y-shaped pipe as a whole. 18. Branch pipe according to claim 16, characterized in that: the inlet is a circle; and the central axis passes through the center of the specified circle. 19. The branch pipe according to claim 16, further comprising: a valve located in the second outlet part of the nozzle; And wherein the valve is configured to selectively move between at least: a first position allowing the exhaust gas to enter the second outlet of the nozzle, and the second position, blocking the exhaust gas from entering the second outlet part of the pipe. 20. A turbocharger assembly for hydraulic connection to an exhaust pipe, comprising: turbocharger, containing: exhaust gas turbine a turbocharger inlet defined by the exhaust gas turbine, and a housing accommodating an exhaust gas turbine; And a bypass pipe located downstream in front of the body and hydraulically communicating with the body, the bypass pipe comprising: an inlet of a branch pipe for receiving exhaust gas from an exhaust pipe; a bypass passage forming a hydraulic connection between the inlet of the nozzle and the bypass outlet defined by the bypass nozzle, moreover, the bypass passage contains an opening; And a turbocharger passage forming a hydraulic connection between the nozzle inlet and the turbocharger inlet, moreover, the area of the said hole is from 0.75 to 1.25 times the area of the inlet hole of the turbocharger. 21. The turbocharger assembly according to claim 20, characterized in that the area of said hole is larger than the area of the turbocharger inlet. 22. The turbocharger assembly according to claim 20, characterized in that the area of the turbocharger inlet opening is larger than the area of said opening.

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