A cooling system and method for an internal combustion engine

Abstract

A plurality of sensors (602, 607, 608) are used to acquire two-wheeled vehicle operating data. An axial flow fan (404) is mounted on the shroud and is adapted to introduce air axially into an interior portion of the shroud (402) covering the cylinder head (201) and cylinder block (202) assembly. The axial flow fan is driven by a central hub mounted electric motor (406) controlled by a controller unit (601). The controller unit is configured to continuously receive two-wheeled hybrid vehicle operating data from the sensors to determine the thermal state of the internal combustion engine, the speed of the internal combustion engine, and the capacity of a battery for supplying controlled power to the electric motor (406). Thus, the forced cooling system controls the operation of the cooling fan at a target position based on the IC engine cooling requirements.

Description

[0001] This application is a divisional application of the Chinese patent application filed on March 9, 2018, with the invention name “A cooling system and method for an internal combustion engine”, the priority date of March 9, 2017, and the application number 201810196595.0. Technical Field

[0002] The present invention relates generally to two- or three-wheeled saddle-type vehicles. More particularly, the present invention relates to a forced air cooling system employed to cool an internal combustion engine of a saddle-type vehicle. Background Art

[0003] The vehicle uses power from both an internal combustion (IC) engine and an electric motor to drive it. The engine that burns the fuel using an oxidant (air) converts the chemical energy of the fuel into mechanical energy, and a battery powers the electric motor. One type of vehicle is a straddle-type two-wheeled vehicle. During the operation of the IC engine, the combustion of the fuel and the oxidant occurs in the combustion chamber and transfers the mechanical energy to the reciprocating piston. This operation generates a large amount of heat energy in and around the cylinder head and cylinder body. This heat energy will increase the temperature of the IC engine and the atmosphere around it. Therefore, it is necessary to cool the cylinder head, cylinder body, its related components and the surrounding air. The straddle-type two-wheeled vehicle usually adopts a body panel around the IC engine so that the cylinder head and cylinder body are completely enclosed in the scooter body part and vehicle components. Therefore, for this two-wheeled vehicle, it is necessary to adopt an additional forced air cooling system to cool the IC engine. Usually, this forced air cooling system includes a fan operably connected to the crankshaft, and the fan forces air to flow through a shield around the IC engine. The fan can be centrifugal or axial and can be positioned near the crankshaft or close to the cylinder head and cylinder block. Axial fans are advantageous because they work based on local cooling and cool the internal combustion engine more efficiently. Traditionally, axial fans are operably coupled to the IC engine crankshaft so that when the IC engine is operating, the axial fan runs continuously and the rotation speed depends on the speed at the crankshaft. This cooling system has serious drawbacks and affects the styling of the vehicle, including improper cooling, more packaging space, additional number of parts, and difficulty in maintenance. In hybrid vehicles, due to the various modes of operation during a single riding cycle by the driver, additional cooling problems are faced due to changing operating modes. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] The detailed description is described with reference to the accompanying drawings. The same reference numerals are used throughout the drawings to refer to similar features and components.

[0005] Figure 1a A side view of a two-wheeled vehicle incorporating an embodiment of the present invention is shown.

[0006] Figure 1b An isometric view of an internal combustion engine mounted on a frame assembly of a two wheeled vehicle incorporating an embodiment of the present invention is shown.

[0007] Figure 2 A side view of an internal combustion engine incorporating an embodiment of the present invention is shown.

[0008] Figure 3 A cross-sectional view (XX) of an internal combustion engine according to an embodiment of the invention is shown, showing an axial fan and a shroud.

[0009] Figure 4 An exploded view of an axial flow fan and a shroud according to an embodiment of the present invention is shown.

[0010] Figure 5a A cross-sectional view (YY) of a cylinder block of an internal combustion engine and an axial fan and a shroud according to an embodiment of the present invention is shown.

[0011] Figure 5b An enlarged isometric view (Z) of a cylinder block of an internal combustion engine and an axial fan assembly and shroud showing an exhaust system outlet is shown in accordance with an embodiment of the present invention.

[0012] Figure 6 A block diagram of an axial flow fan system according to an embodiment of the present invention is shown.

[0013] Figure 7 A flow chart of a method for determining a thermal state of an axial fan system of an internal combustion engine according to an embodiment of the present invention is shown.

[0014] Figure 7a Determining states for various conditions of engine operating state and ignition switch state are shown. DETAILED DESCRIPTION

[0015] Various features and embodiments of the present invention will become apparent from the further description that follows. According to one embodiment, the internal combustion (IC) engine described herein is operated in four cycles for a hybrid vehicle. Such an IC engine is mounted in a straddle-type two-wheeled vehicle. It is contemplated that the concepts of the present invention may be applied to other types of vehicles within the spirit and scope of the present invention. Moreover, the "front" and "rear" and "left" and "right" mentioned in the subsequent description of the illustrated embodiment refer to the forward and rearward directions and the left and right directions as viewed from the rear of the IC engine and viewed forward.

[0016] The IC engine includes a cylinder head, a reciprocating piston positioned within a cylinder block below the cylinder head, a combustion chamber formed between the cylinder block and the cylinder head, a rotatable crankshaft for transmitting mechanical energy to a drive train, and a connecting rod that transmits energy applied to the reciprocating piston to the rotatable crankshaft. During operation of the IC engine, combustion of an air-fuel mixture occurs within the combustion chamber. This operation generates a large amount of heat energy within and around the cylinder head and cylinder block, which increases their temperature and the temperature of the atmosphere surrounding them. Therefore, a cooling system is required to cool the cylinder head, cylinder block, and their associated components and the surrounding air.

[0017] Although cooling of the cylinder head and cylinder block of an IC engine is necessary, too much cooling is also undesirable because it reduces the thermal efficiency of the IC engine. Therefore, the goal of any cooling system is to keep the engine operating at the most efficient operating temperature. It should be noted that the engine is very inefficient when it is cold, and therefore the cooling system is designed in a way that we need to maintain the actual overall operating temperature of the cylinder block. Therefore, the cooling system should ideally reduce the cooling effect when the IC engine is warming up or operating slowly, and cool it down when it is operating at higher temperatures. Therefore, ideally, the cooling system should maintain the highest efficient operating temperature.

[0018] There are two commonly used air cooling systems. Forced air cooling system and natural air cooling system. In the natural air cooling system, the heat conducted to the outside of the cylinder block is radiated and conducted away by the air flow naturally obtained from the atmosphere during the vehicle's driving. In order to effectively cool by atmospheric air, fins are provided around the cylinder head and cylinder block, which increases the contact area exposed to the atmosphere. In the forced air cooling system, the atmosphere is sucked into the cooling system from the outside atmosphere through an inlet by using a cooling fan. The rotation of the cooling fan is integrated with the rotation of the rotatable crankshaft. The shroud surrounding the cylinder head, cylinder block and IC engine guides the atmospheric air, thereby cooling it. Therefore, the heat generated due to combustion will be conducted to the fins as the air flows over the fins, and the heat will be dissipated to the air flow. The shroud can be composed of multiple parts and usually accommodates the cooling fan and can have multiple deflectors to guide the atmospheric air. The shroud also has vents for the hot air to leave.

[0019] Typically, in a straddle-type vehicle, the IC engine is positioned below the seat, at the lower rear of the vehicle. There are two side cowls surrounding the IC engine on the left and right sides of the vehicle. The IC engine is swingably supported by the rear suspension system and attached to the frame of the vehicle. The cylinder block, cylinder head and other related components of such an internal combustion engine are enclosed and heated during its operation. Due to the lack of proper air circulation around it, such an internal combustion engine is usually cooled using a forced air cooling system.

[0020] Typically, to cool the cylinder block, a forced air cooling system is used in combination with a centrifugal fan that is integral with the rotation of a rotatable crankshaft. However, such centrifugal fan assemblies have many drawbacks, such as having more packaging space, utilizing a greater number of components, and resulting in high costs. In addition, centrifugal forced air cooling systems have shrouds and cooling fans that are exposed to harsh external environments, and therefore may be affected by ingress of dust, water splashes, and stones. The presence of an external shroud that encloses the IC engine and cooling fan also affects vehicle styling and appearance. Therefore, to avoid these drawbacks, an axial flow fan system may be used.

[0021] In an axial fan type forced air cooling system, the axial fan is arranged to face the side of the cylinder head and cylinder block. A shroud surrounds the cylinder head and cylinder block, and the axial fan is mounted on the shroud so that the air flow is axially directed within the shroud. A fan shroud is used that extends in the axial direction of the cylinder block and is fixed to the shroud covering the axial fan. The axial fan is usually operably connected to the rotatable crankshaft by a transmission system, such as a gear train connected to the crankshaft, a flexible belt and a belt drive such as a V-belt drive, or even a drive transmission by means of an axial gear on the axial fan that meshes with a drive gear fixed to a magnetic generator assembly driven by the rotatable crankshaft.

[0022] As emphasized above, an effective cooling system should keep the temperature of the cylinder block at an optimal operating temperature. Too much heat removal will reduce the thermal efficiency of the engine, and ineffective removal will lead to overheating. However, typically in a forced air cooling system, the cooling fan is operably connected to the crankshaft, and therefore increases as the IC engine speed increases regardless of the engine temperature, which increases the suction force of the air flow used for cooling. In many cases, if the cooling fan is coupled to the rotatable crankshaft, it is necessary to control the cooling speed, which is difficult. In traffic conditions where the vehicle is traveling through congested traffic, the IC engine and the traction motor may be continuously switched and started and stopped. Moreover, under cold atmospheric conditions, it is not desirable to circulate cold air at a higher intake rate because the operating temperature may not be maintained. Even under IC engine cold start conditions, the increased amount of cold air will cause a delay in IC engine warm-up. In addition, under these conditions, a larger amount of power is used to drive the cooling fan, and the cooling is also uneven. Therefore, it is desirable to control the operation of the cooling fan based on the IC engine cooling requirements.

[0023] Axial fan type forced air cooling systems are known in the prior art. In an axial fan type forced air cooling system, effective cooling can be achieved and a compact structure can be formed and the defects associated with a centrifugal forced air cooling system can be alleviated. However, such an axial fan type forced air cooling system also faces the defect of not being able to control the cooling fan based on the IC engine cooling requirements. The axial fan type forced air cooling system also has other defects associated with it. There is a transmission mechanism that transmits power to drive the axial fan. Such a transmission system increases complexity and requires frequent maintenance and additional lubrication. Moreover, the transmission system that uses a belt and a pulley to transmit power has defects, including belt slippage and loss of belt tension with frequent use. In order to prevent such slippage, a belt tensioning mechanism can be used, but this only increases the cost and leads to the complexity of the components. In addition, it is difficult to accommodate all the transmission systems in a small and restricted layout (such as a scooter). Moreover, the operation of the axial fan sometimes causes noise, which is undesirable. Moreover, the axial fan type forced air cooling system may have many local parts of the cylinder block that have a higher temperature but are ineffectively cooled.

[0024] The present invention aims to alleviate the above-mentioned disadvantages and proposes a new axial fan type forced air cooling system for a vehicle, which can provide an independent and intermittent local forced air cooling system for the cylinder head and cylinder block of an IC engine. This is achieved by using an axial fan system, which takes advantage of the advantages provided by using an axial fan system and controls its operation based on the thermal state and speed of the IC engine and the operating state of the electric traction motor. The axial fan system is implemented by eliminating any transmission mechanism that operably connects the axial fan system to the rotatable crankshaft. The present invention also aims to improve the cooling system efficiency by enhancing the internal shroud area, deflecting the air towards the key cooling areas in the cylinder head and cylinder block, and aims to improve the hot gas discharge and optimize to reduce pressure losses.

[0025] Through the above-mentioned design changes, the following advantages can be obtained: such as effective cooling of key areas, improved air circulation within the shield, avoidance of the use of mechanical connections and avoidance of lubrication of those mechanical parts, reduced airflow losses within the cooling space, improved heat dissipation, a more compact and durable structure, simple structure, automatic and convenient operation, easy removal of installation and maintenance, and increased aesthetic value by avoiding exposure of the cooling system to the atmosphere to help the vehicle styling.

[0026] The present invention and all accompanying embodiments and further advantages thereof will be described in more detail with reference to the accompanying drawings in the following paragraphs.

[0027] Figure 1aA two-wheeled vehicle according to one embodiment of the present invention is shown. The vehicle includes a frame that is generally a U-shaped frame, which provides a generally open central area to allow a rider to "step" onto the vehicle. Typically, the frame includes a head tube 102, a main tube 107, and a pair of side tubes 109 (only one is shown). One end of the main tube 107 extends downward and rearwardly to form a flat "step-through" section 117 extending toward the rear of the two-wheeled vehicle and connected to a pair of side tubes 109. The step-through section includes two support brackets 120 at both ends (only the rear support bracket is shown). A pair of side tubes (109a and 109b) are attached to the step-through section of the main tube on the support bracket 120, so that the pair of side tubes are arranged at both ends approximately parallel to each other, as viewed from the front of the two-wheeled vehicle. The other end of the main tube 107 has a head tube 102, which is configured to rotatably support a steering tube (not shown). A gusset 116 connects the head tube 102 to the main tube 107. The front suspension system 121 is connected to the lower end of the steering tube (not shown). A handlebar support member (not shown) is connected to the upper end of the steering tube (not shown) and supports the handlebar assembly 106, which can rotate on both sides. The upper part of the upper bracket (not shown) includes a shield assembly 124, which surrounds the handlebar 106, the rearview mirror assembly 105, the front headlight 104 and the instrument cluster (not shown). Two telescopic front suspension systems 121 (only one is shown) are attached to the bracket (not shown) on the lower part of the steering tube (not shown) on which the front wheel 119 is supported. The upper part of the front wheel 119 is covered by the front fender 103 mounted to the lower part of the steering shaft (not shown). When viewed from the front of the two-wheeled vehicle, a pair of side tubes 109 are attached to the main tube 107 at one end and extend rearward in a generally horizontal direction at the other end. A plurality of cross brackets including a bridge-type mounting bracket 114 are secured between a pair of side tubes 109 to support vehicle accessories including a utility box (not shown), seats 108, and a fuel tank assembly (not shown).

[0028] The two-wheeled vehicle further includes a rear wheel 113, a fuel tank (not shown), a rear seat armrest 118 and a seat 108. Left and right rear swing arm brackets (not shown) are pivotally mounted on the U-shaped frame at the rear of the step-over structure 117, and support the swing arm assembly. The swing arm assembly includes left and right swing arms 115 (only one is shown) pivotally mounted to the left and right rear swing arm brackets (not shown), and can swing vertically around the pivot point and is supported by two rear wheel suspensions 111 arranged at the rear of the swing arm assembly. In addition, the swing arm assembly includes a front engine mounting cross tube (not shown) attached between the left and right swing arms 115, and a rear engine mounting cross tube 125. The IC engine 101 is mounted between the front engine mounting cross tube (not shown) and the rear engine mounting cross tube 125, so that the IC engine 101 is swingably supported on the swing arm assembly. The rear wheel 113 is connected to the rear end of the swing arm assembly and is configured to rotate by the driving force of the IC engine 101 transmitted via a belt drive device (not shown) from the IC engine 101. The rear fender 110 covers at least a portion of the rear wheel 113 and is located below the fuel tank (not shown). The electric traction motor 130 (see Figure 6 ) is connected to the rear wheel 113, forming a wheel hub that can drive the rear wheel 113. The electric traction motor 130 draws power from a battery arranged at an appropriate position on the hybrid vehicle. The battery can be charged by the IC engine 101 and can also be charged externally. The two-wheeled vehicle also includes a plurality of electrical and electronic components, including headlights 104, taillights 112, a transistor controlled ignition (TCI) unit (not shown), and a starter motor (not shown).

[0029] Figure 1b An isometric view of an IC engine mounted on a swing arm assembly attached to a U-shaped frame assembly of a vehicle is shown. An axial forced air cooling system according to an embodiment of the present invention is shown, which is arranged to cover a portion of the IC engine 101. A bridge mounting bracket 114 is shown, which is fixed between a pair of side pipes (109a and 109b) to support vehicle accessories, including a utility box (not shown), a seat 108 and a fuel tank assembly (not shown). The bridge mounting bracket 114 is mounted toward the front of the pair of side pipes 109 and is positioned closely to the IC engine 101, and is designed so that it is U-shaped, and the cylinder head and cylinder block assembly 101 of the IC engine 101 generally occupies the space below the curved U-shaped bridge mounting bracket 114. The axial forced air cooling system is mounted above the cylinder head and cylinder block 202 assembly (see Figure 3 , Figure 6); therefore the bridge mounting bracket 114 is mounted above the axial forced air cooling system. In order for the axial forced air cooling system to work effectively, the system should have sufficient air gap available to draw air inside the shield. But the current arrangement prevents sufficient air gap around the system. Therefore, an opening 114a is provided in the bridge mounting bracket 114 to allow the system to access the air gap between the body panel of the vehicle and the pair of side ducts 109. In addition, due to the low pressure generated in the air gap between the body panel and the pair of side ducts 109, the atmosphere from below the vehicle is drawn from the atmosphere and takes its place.

[0030] Figure 2 FIG. 1 shows a side view of an IC engine 101 according to an embodiment of the present invention. The IC engine 101 comprises a cylinder head 201, a cylinder block 202 (see FIG. 1 ). Figure 3 and Figure 6 ) and crankcase 203. An axial type forced air cooling system is installed above cylinder head 201 and cylinder block 202 so that axial flow fan 404 is positioned to align with a high heat area such as spark plug 309 to manage the spark plug temperature. This causes the cooling air to directly impact the spark plug once it is sucked inside by axial flow fan 404. Therefore, effective cooling can be obtained.

[0031] Figure 3 A cross-sectional view taken along line XX of the IC engine 101 is shown, showing the main parts. During operation, combustion of fuel and oxidant occurs in the combustion chamber, and mechanical energy is transferred to the reciprocating piston 306. After combustion, hot exhaust gas is generated that is discharged from the cylinder block 202. The combustion of the air-fuel mixture in the cylinder block 202 generates a large amount of heat energy, which increases the temperature of the cylinder block and the air around the cylinder block 202. The cylinder block 202 has an extended surface that increases the surface area for effective heat dissipation, which is called a fin. The fin increases the heat transfer from the combustion chamber to the outside, which is then removed by forced air circulation. The combustion gases after combustion are also very hot and are discharged from the cylinder block 202 through the exhaust port on the cylinder head 201. An exhaust pipe (not shown) is connected to the cylinder head 201, and the exhaust gas is discharged from the cylinder head 201 through the exhaust pipe (not shown). Therefore, the area around the exhaust pipe connected to the cylinder head 201 is also at an elevated temperature and requires effective cooling.

[0032] Figure 4An exploded view of forced axial fan air cooling according to an embodiment of the present invention is shown. In this embodiment, the system includes an axial fan assembly 400 mounted on an LH shroud 402. The LH shroud 402 is modified to have a circular raised protruding area 402a, and a plurality of protruding portions 402b are arranged around its periphery. The circular raised protruding area 402a forms a space at the inner periphery of the LH shroud 402 to accommodate an axial fan 404. In one embodiment of the present invention, there are three protruding portions 402b, which are equidistantly distributed from each other on the outer periphery of the circular raised protruding area 402a. The protruding portion 402b has a hole with an internal thread at its center. The fan cover 401 is installed to close the opening from the outside. The fan cover 401 is made of a plastic resin material and has a profile with a size similar to the outer periphery size of the circular projected area 402a. The fan cover 401 is suitable for abutting the outer periphery of the circular raised protruding area 402a. The fan cover 401 also has a convex portion 401a protruding axially from the outer peripheral surface of the fan cover. The raised portion 401a also has a hole with an internal thread, and the raised portion is able to perfectly abut against the raised portion 402b of the LH shield 402. The hole on the raised portion 401a and the raised portion 402b match perfectly so that they can be attached by using connection means such as nuts and bolts, fasteners 417, 418, etc. The fan cover 401 also includes a grille 401b that closes the fan cover to protect the axial fan blades from external interference and prevent the ingress of stones and other particles.

[0033] The axial flow fan 404 includes a hub in which the motor 406 is housed. A plurality of twisted guide blades protrude from the hub and radially protrude outside the hub. A plurality of twisted guide blades connect an outer cone. The outer cone is an annular band that surrounds the central hub, wherein the guide blades are located inside the outer cone. The guide blades are twisted so that when the motor 406 rotates, a pressure difference is created between the air behind the fan at a low pressure and the air outside the fan at a high pressure. This pressure difference causes air to be drawn into the interior of the axial flow fan 404. The twisted shape of the guide blades and the shape of the fan cover grille are twisted to guide and draw the air inside, and then guide the air toward the interior portion of the shroud.

[0034] The hub of the axial flow fan includes a bushing portion located downstream. The hub sleeve fits in the protrusion of the fan mounting bracket 407. The fan mounting bracket 407 is a single metal bracket, which includes a central annular portion 407a. The inner circumferential surface of the central annular portion 407a has a protrusion surface suitable for matching with the bushing portion of the axial flow fan hub. The central annular portion 407a has a plurality of arms that protrude radially outward and are positioned equidistantly from each other, and has an upper hole at its end. These arms also have a lower hole with an internal thread, which is positioned close to the base of each arm, close to the central annular portion 407a. The lower hole is used to securely fix the axial flow fan 404 to the fan mounting bracket 407 by connecting means such as bolts, fasteners 411. The upper hole has an internal thread and three arms are equidistantly distributed so that the upper hole just abuts on the inner surface of the protrusion on the inner surface of the LH shield 402. The arm also has a cutout that provides additional strength and rigidity, and is also used as a deflector that deviates from the airflow. The fan mounting bracket 407 is fixed to the LH shroud 402 by fasteners 410, 412 inserted into the upper hole and the protruding portion. The axial fan system including the axial fan 404, the fan shroud 401 and the fan mounting bracket 407 is integrated as a subsystem or assembled as a separate component with the LH shroud 402. The lower hole is also used to mount the spark plug deflector 405 within the inner portion of the LH shroud 402.

[0035] The spark plug deflector 405 is used to divert the cooling air flow 315 to key parts of the cylinder block 202. These key parts include the area around the spark plug 309 and the hot zone area 505 around the portion where the exhaust pipe connects to the cylinder block 202. The system in this embodiment includes the spark plug deflector 405 and the exhaust deflector 503. The spark plug deflector 405 includes a central body with a curved profile, and the angle of curvature is almost vertical. One end of the central body has a curved profile to deflect the cooling air flow 315 toward the center of the cylinder block 202, and the other end has two arms with holes at their ends. The two arms are arranged parallel to each other and have cutouts to provide strength and rigidity. The holes on the arms are matched with the lower holes provided on the engine mounting bracket 407. The exhaust deflector 503 further improves the cooling efficiency by directing the cooling air flow toward the wall of the cylinder block 202.

[0036] Figure 5aA top cross-sectional view of the cylinder block 202 is shown. This figure shows possible paths taken by the cooling air 315 flowing through the interior portion of the shroud. The axial fan 404 draws the cooling air 315 into the shroud and the cooling air enters the interior portion of the shroud. In the interior portion of the shroud, the cooling air is divided into two paths, namely a long path 506 that surrounds the cylinder head and cylinder block assembly, cools both edges of the cylinder head and cylinder block assembly, and a short path 507 that substantially cools the exhaust hot zone 505 of the cylinder head 201. The long path 506 of the cooling air flow is directed out of the shroud through the outlet vent 502. The outlet vent 502 is located in a corner of the lower edge of the RH shroud 403, which surrounds the location 505 where the exhaust pipe connects the cylinder head 201. The short path 507 of the cooling air flow cools the other remaining edge of the connection contained between the exhaust pipe and the cylinder head 201. The short air path 507 cools these areas and exits through the exhaust vent 501. The entire shroud is optimized with respect to the clearance between all sides of the IC engine by having more space on less hot zones near the intake of the LH shroud and less space on more hot zones such as the spark plug 309. More spatial areas are further optimized by creating ridges (402a and 403b) to allow better contact of the air flow with the hot zones by avoiding flow reversals. The shroud (402) includes a hot air outlet formed at one edge of the shroud (402) positioned proximate to the hot zone area (505), the hot air outlet having a first edge and a second edge, the first edge being adapted to protrude outwardly from an outer surface of the shroud (402) such that the width of the first edge is greater than the width of the second edge to form an angled profile when viewed from a side view of the internal combustion engine (101).

[0037] Figure 5bAn enlarged isometric view of the cylinder head 201 and cylinder block 202 of the IC engine 101 and the axial fan 404 and shroud is shown, which shows the exhaust system outlet according to an embodiment of the present invention. The short air path 507 flows through the hot zone 505 near the exhaust system outlet and the hot air leaves the shroud through the exhaust vent 501. However, when the cooling air in the short air path 507 flows through the hot zone area 505 to extract heat, the temperature of the cooling air slowly increases and becomes hot, and a problem occurs at this location. The density of this hot air is lighter, and because the short air path 507 is taken, the speed of the air is significantly reduced and the density of the lighter hot air increases, whereby the hot air accumulates near the location of the hot zone area 505 and cannot leave the exhaust vent 501. To solve this problem, the profile of the shroud is curved below the outlet vent (see 403a), as can be seen from the inner portion of the RH shroud 403. This shape partially directs the cooling air flow from the long path 506 toward the exhaust vent 501. This air flow directed toward the exhaust vent 501 occurs with increased velocity. This is primarily due to the more space provided during the cooling air flow through the long path 506 and due to the ridges 403b provided near the outlet which streamlines the flow, which helps to discharge the hot air accumulated near the exhaust vent 505, thereby helping to avoid air flow deviation and reducing pressure losses. The ridges (402a and 403b) are provided in the inlet and outlet areas for better heat transfer between the air flow and the engine and more streamlined movement of the air flow.

[0038] The outlet vent (502) is further arranged at the bottom corner edge of the cylinder block and cylinder head surface. This provides a desired curved profile (403a) to increase the speed of leaving from the long path 506 and also prevents the hot air from the front of the IC engine from entering the outlet vent (502) and generating backflow. The outlet vent 502 is designed to have an angled opening, protruding and tilted toward the front to avoid the cooling air flow 315 from entering and the hot air from leaving to avoid mixing, flowing back and increasing pressure losses. The design ensures that the hot air outlet is roughly below the two-wheeled vehicle and helps change the direction of the hot air outlet. The outlet vent 502 is also maintained flat to discharge more hot air toward the bottom. This prevents the hot air flow from heating the utility box (not shown) toward the cabin area.

[0039] Figure 6 A system block diagram of a system according to an embodiment of the present invention is shown for determining the thermal state of IC engine 101 and the operating state of electric traction motor 130. The operation of the system includes multiple stages of supplying and regulating power to electric motor 406 to control forced air cooling based on the thermal state of the IC engine and the operating state of electric traction motor 130.

[0040] The main elements of the system include the IC engine 101, the air unit 601, the ignition switch 603 used as a control switch, the electric traction motor 130, and the battery 604. When operating the ignition switch, the rider of the hybrid vehicle selects the operating mode of the hybrid vehicle on the drive mode selector. Based on the selection, the drive mode selector starts the IC engine 101 or the electric traction motor. The IC engine 101 drives the rear wheel 113 of the hybrid vehicle through the end gear 606. The magnetic generator assembly 301 is operably connected to the rotatable crankshaft 305 and is configured to generate a current sent to the battery 604 located at a suitable position in the vehicle to charge it. This power from the battery 604 is used to drive the cooling system controller unit 601, which further drives the electric motor 406 and the electric traction motor 130, and the electric motor 406 forms part of the hub of the axial fan 404. The power from the battery 604 to the electric motor 406 is regulated by the controller unit 601. The battery 604 also drives the electric traction motor 130 and can be charged externally. The controller unit 601 includes a processor and a memory. Among other capabilities, the processor is configured to extract and execute computer-readable instructions stored in the memory to indicate a method of operating the above system. The controller unit 601 is also powered by a battery 604, and the entire system is only turned on and operated when the rider of the two-wheeled vehicle operates the ignition switch 603. The IC engine 101 also includes one or more sensors configured to extract IC engine operating data to detect the thermal state of the IC engine. The magnetic generator assembly 301 includes a speed sensor 607 for detecting the speed of the vehicle. The battery 604 also includes a battery voltage measurement device 608 for measuring the battery capacity. In this embodiment, a temperature sensor 602 is positioned in close proximity to the lubricating oil circulation device located in the cylinder block 202, which can continuously measure the lubricating oil temperature. It should be noted that this embodiment is by no means a limitation or measurement of any parameter with the help of a sensor or sensors located at any position of the IC engine and / or the two-wheeled vehicle, which can achieve the determination of the thermal state of the IC engine without departing from the scope of the present invention.

[0041] The control of the cooling fan motor 406, which forms part of the hub of the axial fan 404, depends on the temperature of the cylinder head 201 and the cylinder block 202, the speed of the vehicle and the battery capacity. The temperature of the cylinder block 202 and the speed of the vehicle in turn depend on the operating conditions of the two-wheeled vehicle and the external atmospheric conditions. These conditions occur, for example, during slow movement in traffic congestion, moving on a gradient surface and under cold start conditions. The operating temperature state is continuously measured by the temperature sensor 602 by measuring the lubricating oil, and the speed is continuously measured by the speed sensor 607. The battery capacity is also continuously monitored when the hybrid vehicle is operated in electric mode. These measurements are continuously transmitted to the controller unit 601. Based on these input signals, the controller unit 601 will disconnect the motor 406 by cutting off the power supply. The axial fan 404 will stop operating and cooling will not occur. This will have a positive effect on the IC engine and help increase the operating temperature when the heat removal stops. The required operating temperature is reached, and the lubricating oil temperature increases, which is monitored by the controller unit 601 through the temperature sensor 602. Once the optimum operating temperature is reached, the controller unit 601 turns on the motor 406, thereby turning on the axial flow fan 404 and starting air cooling. Further, the rotation speed of the axial flow fan 404 can also be controlled and monitored based on inputs from the speed sensor 607 and the battery capacity measuring device 608. Thus, under intermittent operation of the axial flow fan 404, IC engine cooling becomes efficient and performance is improved compared to continuous operation.

[0042] Figure 7 A method for measuring the thermal state of an IC engine with an axial fan forced air cooling system is shown. The method can be described in the general context of computer executable instructions and communications sent to and received by other elements in the system. Typically, computer executable instructions can include routines, methods, programs, objects, components, data structures, processes, modules, functions, etc. that perform specific functions or implement specific abstract data types. The order in which the method is described is not intended to be understood as a limitation, and any number of the described method blocks can be combined in any order to implement the method or an alternative method. In addition, individual blocks can be deleted from the method without departing from the spirit and scope of the present invention described herein. Moreover, the method can be implemented in any suitable hardware, software, firmware, or a combination thereof, as will be explained in another embodiment. Moreover, as best understood by those skilled in the art, although there are a few variations, the method can be implemented in other similar systems.

[0043] Figure 7a The determined status of various conditions of the engine operating state and the ignition switch state are shown. Figure 7a Various conditions under which the axial flow fan is turned on are shown. According to one embodiment of the present invention, the axial flow fan is turned on when the temperature is higher than a predetermined value or the engine is started.

[0044] In method box 701, the ignition switch is actuated by the driver of the two-wheeled vehicle, and the controller unit 601 is powered on to control the operation of the axial fan 404. The method includes two main steps that must be taken, namely, measurement conditions 702, 703 and check conditions 710. The measurement conditions include a plurality of method boxes, wherein in method box 702, the controller unit 601 receives IC engine operation data, such as engine temperature data, engine speed data and battery capacity data from the temperature sensor 602, the speed sensor 607 and the battery measurement device 608. The controller unit 601 then performs the check condition 710. The check condition 710 generally includes a plurality of steps represented as method boxes. In the check condition, the controller unit 601 compares the received temperature data with a first predetermined value, and secondly, the controller unit 601 determines the IC engine mode or the electric mode of the hybrid vehicle, and controls the speed of the axial fan 404 based on the speed data and the battery capacity. Based on the determined state, the controller unit 601 will send an appropriate signal to switch the axial fan to an on state or an off state, and also control its speed. The method represented by these two steps effectively controls the axial flow fan, thereby providing intermittent and independent spot cooling of the cylinder block.

[0045] Check condition 710 includes the following steps. In frame 703, controller unit 603 determines whether the temperature received in frame 702 is greater than a first predetermined value. In one embodiment of the present invention, the first predetermined value is 90 degrees Celsius. It is theoretically known that for a two-wheeled vehicle having a swingably supported single-cylinder engine and a cylinder block enclosed in a side cowl, the temperature generated under standard operation is in the range of 90 degrees Celsius to 120 degrees Celsius. Therefore, if the cooling system is activated under the above temperature range, the IC engine is maintained at an operating working temperature. If the answer to the determination in frame 703 is no, continue to frame 711. In frame 711, controller unit 601 transmits a first signal to disconnect the axial flow fan. In frame 712, axial flow fan 404 receives the first signal and disconnects. Subsequently, leave the check condition and repeat the measurement condition in frame 702. If the answer to the determination in frame 703 is yes, the next step continues to frame 704. In box 703, it should be noted that the conditional loop in box 703 is executed as long as the ignition switch is turned on, regardless of whether the IC engine is turned on or off or running in electric mode. In box 704, the controller unit 601 determines whether the vehicle is in IC engine mode or electric mode by receiving the drive selector signal.

[0046] If it is determined that the vehicle is in electric mode, the condition continues to box 709. Here, the controller unit 601 determines the battery capacity based on the battery capacity sensor. The battery capacity is compared with the second predetermined range. If the battery capacity exceeds the second predetermined range, the controller unit 601 will cause the speed of the axial fan to run at full capacity. In one embodiment, the second predetermined range is between voltages V1 and V2, where V2 is greater than V1, and the maximum capacity of the fan is run at "S" rpm. Therefore, if the battery capacity exceeds V2, the fan will run at full capacity "S" rpm. If the battery capacity is within the second predetermined range, between V1 and V2, the axial fan is driven by the controller unit 601 at less than its maximum capacity "S" "d1" %. Here, the fan speed runs at "S1" rpm. If the battery capacity is below the second predetermined range V1, the axial fan is driven by the controller unit 601 at less than its maximum capacity "S" "d2" %. Here, when the battery capacity is below V1, the fan speed runs at "S2" rpm. In an embodiment of the present invention, the battery voltage can vary from 12.5 V to 48 V. Therefore, at block 708, the controller unit 601 accordingly initiates a second signal to turn on the axial fan 404 and vary the speed of the axial fan 404. In another embodiment, if the temperature is too high (e.g., the temperature exceeds a value "T" degrees Celsius), the temperature input is analyzed, and even if the battery capacity is within a second predetermined range, between V1 and V2, the fan will run at a maximum capacity "S" rpm.

[0047] If it is determined in box 704 that the IC engine mode is selected, then proceed to box 705. Here, the controller unit 601 determines the engine speed based on the engine speed sensor 607. The engine speed is compared with the third predetermined range "U3". If the engine speed exceeds the third predetermined range "U3", the controller unit 601 causes the speed of the axial fan to operate at a minimum capacity (fan speed "S3" RPM). Here, the third predetermined range varies from "U1" rpm to "U2" rpm (U2 is greater than U1). Therefore, if the engine speed exceeds U2rpm, the fan will operate at its minimum capacity S3rpm. If the vehicle speed is within the third predetermined range U3, the axial fan is driven by the controller unit 601 at less than its maximum capacity "S"d3%. If the vehicle speed is lower than the third predetermined range U3, the axial fan is driven by the controller unit 601 at its maximum capacity (fan speed of Srpm). Therefore, in box 706, the controller unit 601 accordingly initiates a third signal to turn on the axial fan 404 and change the speed of the axial fan 404. Subsequently, the check condition is left and the measurement condition is repeated at box 702. It is necessary to mention that the parameters d1, d2 and d3 may vary based on engine size, vehicle layout, and the parameters d1, d2 and d3 may be different to control the fan speed based on battery voltage, engine temperature and engine speed.

[0048] It can be seen from the above method that under all conditions, where the IC engine is in an elevated thermal state, the axial fan can be switched on and off, and its speed can be controlled. The control of the axial fan depends entirely on the engine thermal state and the engine speed / battery capacity. Therefore, during, for example, engine shutdown conditions (where the IC engine is shut down but the temperature is high), or during engine flooding conditions (where the engine is disconnected by operation of the ignition switch (not in the ignition lock state) or the cut-off switch), the thermal state of the cylinder block can exceed the operating temperature and may therefore require cooling. The present invention also envisages operation under these conditions, which is different from the cooling systems proposed in the prior art that depend on the rotation of the crankshaft. Therefore, due to the continuous monitoring of the temperature data of the controller unit 601, intermittent and independent local cooling of the engine cylinder block can be achieved.

[0049] In light of the above disclosure, many modifications and variations of the subject matter are possible. Therefore, within the scope of the subject matter claimed, the present disclosure may be implemented in other ways than those specifically described.

Claims

1. A forced air cooling system for cooling a cylinder head (201) and a cylinder block (202) assembly of an internal combustion (IC) engine (101) of a saddle-type vehicle, the forced air cooling system comprising: A shroud (402) arranged to cover at least a portion of the internal combustion engine (101) including the cylinder head (201) and cylinder block (202) assembly; Features: The shroud (402) has an axial flow fan (404) mounted on the shroud (402), and the axial flow fan (404) is suitable for axially introducing air into an inner portion of the shroud (402) covering the cylinder head (201) and cylinder block (202) assembly; wherein the axial flow fan (404) is mounted above the cylinder head (201) and the cylinder block (202), and the axial flow fan (404) is positioned to align with the spark plug (309), and The shield (402) accommodates a spark plug deflector (405) for deflecting the cooling air flow, the spark plug deflector (405) being mounted on an inner portion of the shield (402), the spark plug deflector (405) having a central body, one end of the central body having a curved profile and the other end having two arms with holes at their ends, the two arms being arranged parallel to each other and having cutouts.

2. The forced air cooling system according to claim 1, wherein: The shroud (402) guides forced air from the axial flow fan (404) toward the spark plug (309) side of the cylinder head.

3. The forced air cooling system of claim 1, wherein: The shield (402) has an integrated fan mounting bracket (407) for mounting the axial flow fan (404), and the fan mounting bracket (407) is fixed to the shield (402) using suitable fasteners (410, 412).

4. The forced air cooling system of claim 1, wherein: The spark plug deflector (405) is installed downstream of the axial flow fan (404), and the spark plug deflector (405) is adapted to change the path of air in the inner portion of the shroud (402).

5. The forced air cooling system of claim 1, wherein: The axial flow fan (404) comprises a hub and a bushing portion, wherein the bushing portion is located downstream of the air flow and the bushing portion is fitted into a boss portion of a fan mounting bracket (407).

6. The forced air cooling system of claim 1, wherein: The axial flow fan (404) including a fan cover (401) and a fan mounting bracket (407) is integrated with a portion of the shield (402) into a subsystem.

7. The forced air cooling system of claim 6, wherein: The fan cover (401) is adapted to abut against the outer periphery of the circular raised protruding area (402a) of the shield (402).

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