JP6769537B2 - Internal combustion engine cooling structure - Google Patents

Description

The present invention relates to a cooling structure in an internal combustion engine, which is an engine mounted on a vehicle such as a motorcycle.

In a vehicle such as a motorcycle, in a water-cooled engine in which a camshaft is supported between a cylinder head and a cylinder head cover as disclosed in Patent Document 1, for example, the drive shaft of a water pump is provided by a cylinder head and a cylinder head cover. It is held while being sandwiched. In this case, the rotating shaft of the water pump held coaxially with the camshaft is rotationally driven by the camshaft.

Japanese Unexamined Patent Publication No. 2014-70499

However, in the engine disclosed in Patent Document 1, the rotation speed of the water pump is about 1/2 of the rotation speed of the crankshaft (that is, the engine rotation speed), which is lower than the general case. .. If the diameter of the impeller of the water pump is increased in order to increase the flow rate of the cooling water, the pump case is enlarged and the water pump itself is enlarged. On the other hand, if the frame is enlarged in order to avoid increasing the size of the water pump, the vehicle width direction is expanded.

Further, when the water pump is held by the mating surfaces of the cylinder head and the cylinder head cover, the seal structure straddles the cylinder head and the cylinder head cover, so that the structure becomes complicated and the cost increases.

In view of such circumstances, it is an object of the present invention to provide a cooling structure for an internal combustion engine that effectively realizes compactification and improvement of assembling property.

The cooling structure of an internal combustion engine according to the present invention controls a thermostat that controls the supply and stop of the cooling water supplied to the water-cooled engine and the amount of secondary air supplied to the exhaust passage of the water-cooled engine. In a water-cooled engine including a reed valve, the thermostat storage portion and the reed valve storage portion are integrally molded.

According to the present invention, by integrating the breather chamber and the reed valve chamber with the water pump to form a unit, the width of the cylinder head and the height of the engine can be adjusted while effectively realizing the functions of these auxiliary machines. It can be suppressed effectively. Since the thermostat and the reed valve can be assembled to the cylinder head integrally with the water pump, the assembling property thereof can be greatly improved and the number of parts can be reduced.

It is a side view of the motorcycle which concerns on embodiment of this invention. It is a left side view of the engine which is an example of an internal combustion engine in embodiment of this invention. It is a front view of the engine in embodiment of this invention. It is a perspective view of the engine which mounted the water pump unit in embodiment of this invention. It is a perspective view which shows the state which removed the water pump cover of the engine which mounted the water pump unit in embodiment of this invention. It is a front view of the engine which mounted the water pump unit in embodiment of this invention. It is a left side view of the engine which mounted the water pump unit in embodiment of this invention. It is a lower perspective view of the cylinder head of the engine in embodiment of this invention. It is an upper perspective view of the cylinder block of an engine in embodiment of this invention. It is an exploded perspective view which shows the structural example around the water pump in embodiment of this invention. It is a left side view of the cylinder head of the engine in embodiment of this invention. It is a side view which shows the joint surface with the cylinder head of the water pump unit in embodiment of this invention. It is a figure which shows the example of the gasket inserted between the water pump unit, the cylinder head and the joint surface in embodiment of this invention. It is a figure which shows the structural example of the inner side surface of the water pump cover of the water pump unit in embodiment of this invention. It is a figure which shows typically the circulation path of the cooling water in the engine in embodiment of this invention.

Hereinafter, embodiments suitable for the cooling structure of the internal combustion engine in the present invention will be described with reference to the drawings.
FIG. 1 is a side view of a motorcycle 100 as an application example of the present invention. First, the overall configuration of the motorcycle 100 will be described with reference to FIG. In the drawings used in the following description including FIG. 1, the front of the vehicle is indicated by the arrow Fr, the rear of the vehicle is indicated by the arrow Rr, and the right side of the vehicle is indicated by the arrow R, if necessary. The left side of the is indicated by an arrow L.

The motorcycle 100 of FIG. 1 may be for so-called off-road use, for example, and a steering head pipe 101 is arranged in the upper front portion of the vehicle body, and a steering shaft (not shown) rotates in the steering head pipe 101. It is inserted as much as possible. A steering wheel 102 is attached to the upper end of the steering shaft, a front fork 103 is attached to the lower end of the steering shaft, and a front wheel 104, which is a steering wheel, can rotate at the lower end of the front fork 103. It is supported by.

Further, from the steering head pipe 101, a main frame 105 having a pair of left and right configurations extends obliquely downward toward the rear of the vehicle body, and a down tube 106 extends substantially vertically downward. Then, the down tube 106 branches to the left and right as a lower frame 108 near the lower part, and after these pair of lower frames 108 extend downward, they are bent at a substantially right angle toward the rear of the vehicle body, and the rear end portion is a pair of left and right bodies. It is connected to each rear end of the main frame 105 via a frame 107.

A water-cooled engine 10 as an internal combustion engine, which is a power drive source, is mounted in a space surrounded by a pair of left and right main frames 105, a body frame 107, a down tube 106, and a lower frame 108. A fuel tank 109 is arranged above the engine 10, and a seat 110 is arranged behind the fuel tank 109. Further, a radiator 111 is arranged in front of the engine 10.

The front end portion of the swing arm 112 is supported by a pivot shaft 113 so as to be swingable up and down on a pair of left and right body frames 107 provided at a lower portion substantially in the center in the front-rear direction of the vehicle body. A rear wheel 114, which is a driving wheel, is rotatably supported at the rear end of the swing arm 112. The swing arm 112 is suspended from the vehicle body via a link mechanism 115 and a shock absorber 116 (rear wheel suspension device) connected to the link mechanism 115. A drive sprocket 117 is attached to the output end of the engine 10 arranged in front of the swing arm 112, and a driven sprocket 118 is pivotally attached to the axle of the rear wheel 114. The drive sprocket 117 and the driven sprocket 118 are chained 119. Are wound and interconnected.

Next, the engine 10 will be outlined. FIG. 2 is a left side view of the engine 10, and FIG. 3 is a front view thereof. In this embodiment, the engine 10 may be, for example, a 4-cycle single cylinder, typically a DOHC engine. As shown in FIG. 2 and the like, the engine 10 has a cylinder block 12, a cylinder head 13 and a cylinder head cover 14 integrally coupled to the upper part of the crankcase 11, and the cylinder axis is set in front of a predetermined angle as shown in FIG. Tilt. Further, the engine 10 (mainly the crankcase 11) is integrally coupled and supported to the vehicle body frame by being suspended from the vehicle body frame via a plurality of engine mounts, and itself functions as a rigid member of the vehicle body frame.

Although detailed illustrations and the like are omitted as appropriate, the crankshaft 15 is rotatably supported in the crankcase of the crankcase 11, while the piston is fitted in the cylinder bore of the cylinder block 12 so as to be movable in the cylinder axis direction. Cylinder. The crankpin of the crankshaft 15 and the piston pin of the piston are connected to each other via a connecting rod, and the piston reciprocates in the cylinder bore of the cylinder block 12 along the cylinder axis direction to rotationally drive the crankshaft 15. Cylinder.

As shown in FIG. 2, a transmission case 16 is integrally formed at the rear portion of the crankcase 11, and a counter shaft and a drive shaft are arranged behind the crankshaft 15 in parallel with the transmission case 16 in the transmission case 16. .. A plurality of transmission gears are arranged in a row on the counter shaft and the drive shaft. The meshing relationship of these transmission gears is selectively set by the gear shift device, whereby the desired gear ratio of the transmission can be obtained. The power of the engine 10 is finally transmitted from the crankshaft 15 via the transmission to the drive sprocket 117 (FIG. 1) attached to the shaft end of the drive shaft, and the drive sprocket 117 is transmitted via the power transmission chain 119. The driven sprocket 118, and thus the rear wheel 114, is rotationally driven.

Further, the engine 10 has an intake system that supplies an air-fuel mixture (intake) and fuel supplied from an air cleaner and a fuel supply device, respectively, and an exhaust system that exhausts exhaust gas after combustion in a cylinder from the engine 10. A valve train that drives and controls the intake valve and the exhaust valve of the intake system and the exhaust system, a cooling system that cools the engine 10, a lubrication system that lubricates the moving parts of the engine 10, and a control system (ECU; Engine) that controls their operation. Control Unit) is attached.
By controlling the control system, a plurality of functional systems cooperate with the above-mentioned auxiliary machinery and the like, whereby smooth operation of the engine 10 as a whole is performed.

Specifically, in the intake system, an intake port 17 (its approximate position is shown in FIG. 2) is opened at the rear of the cylinder head 13, and the intake port 17 has two intake ports 17A, with reference to FIG. As 17B, it communicates with the combustion chamber 18. The intake ports 17A and 17B are opened and closed by an intake valve. A throttle body is connected to the intake port 17, and combustion air is supplied to the throttle body from an internal space formed between the left and right sides of the vehicle body frame (mainly the body frame 107) or an air cleaner housed and arranged in the space. .. The throttle body is equipped with a throttle valve that opens and closes the intake passage formed inside the throttle body according to the accelerator opening, and the flow rate of air supplied from the air cleaner is controlled by this throttle valve. An injector for fuel injection is mounted on the downstream side of the throttle valve of the throttle body, and the fuel in the fuel tank 109 is supplied to the injector from the fuel pump.

The air purified by the air cleaner is supplied to the throttle body, and the throttle valve is opened and closed at a predetermined timing by the control of the control system described above, and fuel is injected from the injector into the intake passage. As a result, the air-fuel mixture having a predetermined air-fuel ratio is supplied to the intake port 17 of the cylinder head 13. The throttle valve is driven by a valve drive mechanism that mechanically or electrically or electromagnetically drives the throttle valve shaft under the control of a control system.

In the exhaust system, as shown in FIG. 3 or 6, an exhaust port 19 opens at the front of the cylinder head 13, and the exhaust port 19 burns as two exhaust ports 19A, 19B with reference to FIG. Communicate with room 18. These exhaust ports 19A and 19B are opened and closed by an exhaust valve, and in this example, they are so-called four valves having two intake valves and two exhaust valves. An exhaust pipe is connected to the exhaust port 19, and the exhaust pipe extends downward from the exhaust port 19, extends rearward through the side portion of the crankcase 11, and is connected to the muffler 120 (see FIG. 1). Will be done.

In the valve train of an engine, the cylinder head 13 has a camshaft having a cam for driving an intake valve and an exhaust valve, respectively. Although abbreviated in FIG. 4A in this example, the intake side and exhaust side camshafts 20 and 21 (cams) that are rotatably supported by the cylinder head 13 and the cylinder head cover 14 and laid horizontally in the left-right direction. Axis). Sprockets 22 and 23 are attached to the right shaft ends of these camshafts 20 and 21, respectively (abbreviated by dotted lines in FIG. 4A), while drive sprockets (not shown) are attached to the right shaft ends of the crankshaft 15. ) Is attached. As shown in FIG. 5A, a cam chain 24 traveling in the vertical direction is wound and mounted on the sprockets 22, 23 and the drive sprockets, that is, the crankshaft 15 and the cam shafts 20, 21 are connected via the cam chain 24. To. A cam chain chamber 25 is provided on the right side of the engine 10 from the crankcase 11 to the cylinder block 12, the cylinder head 13 and the cylinder head cover 14 with reference to FIGS. 6 and 7, and the cam chain 24 is provided in the cam chain chamber 25. Run.

In this way, the crankshaft 15 and the camshafts 20 and 21 are connected via the cam chain 24, whereby the valve operating mechanism of the valve operating system is driven in synchronization with the rotation of the crankshaft 15. Then, the intake cam and the exhaust cam of the camshafts 20 and 21 open and close the intake valve and the exhaust valve at predetermined timings, respectively.

Further, a lubricating system is configured to supply lubricating oil to the moving parts of the engine 10 to lubricate them. This lubrication system includes a valve gear configured in the crankshaft 15 and the cylinder head 13, a cam chain 24 connecting them, a transmission, and the like. In the present embodiment, a normal oil pump is used for the lubrication system, but the oil pump may be configured to supply the lubricating oil sucked up from the oil pan provided at the lower part of the engine to the lubrication system.

Further, in the cooling system, a water jacket, which will be described later, is configured so as to circulate cooling water around the cylinder including the cylinder block 12 and the cylinder head 13. A water jacket 26 formed so as to surround the combustion chamber 18 in the cylinder head 13 as shown in FIG. 6 and a water jacket 28 formed around the cylinder bore 27 in the cylinder block 12 as shown in FIG. The water jacket 26 and the water jacket 28 are communicated with each other. As schematically shown in FIG. 2, a radiator 111 for cooling the cooling water supplied to the engine 10 including the water jackets 26 and 28 is provided. The radiator 111 dissipates the heat of the cooling water circulating inside by applying a running wind. For example, the radiator 111 has a rectangular shape or the like when viewed from the front (see FIG. 3), and is generally arranged in front of the cylinder head 13. It is supported by the body frame so as to. Further, as shown in FIG. 2 and the like, the cooling system has a water pump 29 for circulating cooling water, and the radiator 111 and the water pump 29 are interconnected by cooling water hoses 30 and 31, but the details thereof. Will be described later.

Next, the cooling structure of the internal combustion engine of the present invention will be described. The water pump 29 is arranged on the side surface (left side in this example) of the cylinder head 13 as shown in FIG. 4A, and has a water pump case 32 and a water pump cover 33 as shown in FIG. In the present embodiment, in addition to the water pump 29, the engine 10 includes a breather chamber for separating air and liquid of blow-by gas and a reed valve chamber for accommodating a reed valve for controlling the amount of secondary air supplied to the exhaust passage. However, these specific configurations will be described later.

As shown in FIG. 8, the water pump case 32 generally has a flat thin box shape, and as shown in FIG. 4B, a plurality of fastenings are performed so as to cover substantially the entire left side surface portion of the cylinder head 13 together with the breather chamber described later. The portion 34 is fixed to the cylinder head 13 by a fastening means such as a bolt. The water pump 29 of this example is a centrifugal pump, and the main parts thereof are an impeller 35, and a rotating shaft 37, in which the impeller 35 is pivotally attached to the shaft end by a bolt 36 as a fixing means, rotates. It includes an oil seal 38 that rotatably supports the shaft 37 and a gear 39 that is pivotally attached to the shaft end of the rotating shaft 37 on the side opposite to the impeller 35. Further, the water pump case 32 has a housing 40 for accommodating the oil seal 38.

In this embodiment, as can be seen from FIG. 4B, the water pump 29 main body is arranged unevenly on the intake side of the engine 10 when viewed from the side of the vehicle. The rotating shaft 37 of the water pump 29 attached to the side surface of the cylinder head 13 extends to the inside of the cylinder head 13. In this case, the rotating shaft 37 is the camshaft 20 on the intake side (see FIG. 4A). Is parallel to, but its axis is offset downward. With reference to FIG. 9 as a drive mechanism of the water pump 29, the rotating shaft 37 is arranged at a distance substantially below the camshaft 20, and the gear 39 at the shaft end thereof is aligned with the gear 41 pivotally attached to the camshaft 20. To mesh. The gear ratio of the gear 39 and the gear 41 is set to be at least 1 or more, preferably larger than 1. The specific gear ratio can be appropriately selected according to the specifications of the engine 10. In either case, the water pump 29 rotates at a rotation speed equal to or higher than the rotation speed of the camshaft 20.

Here, as shown in FIG. 9, a mounting surface 42 for mounting the water pump 29 is formed on the left side surface of the cylinder head 13. The mounting surface 42 is formed as a flat surface having a predetermined pattern as shown in FIG. 9 in order to form a breather chamber or the like as described later. On the other hand, the water pump case 32 has a joint surface 43 formed as a flat surface having a pattern corresponding to the pattern of the mounting surface 42, as shown in FIG. As shown in FIG. 5A, the mounting surface 42 and the joint surface 43 are superposed on each other so as to be substantially parallel (vertical direction) with the cylinder axis Z. In this case, a seal 44 formed so as to have a pattern substantially similar to those patterns is interposed between the mounting surface 42 and the joint surface 43, and the liquidtightness and airtightness of both are interposed. Is secured and maintained.

As shown in FIG. 12, a casing 45 capable of accommodating the impeller 35 is recessed on the inner surface of the water pump cover 33, and the water pump cover 33 is coupled to the water pump case 32 to form the impeller 35 in the casing 45. Is configured to rotate. The water pump cover 33 is cooled after cooling the engine 10 to the radiator 111 and the inlet pipe 46 to which the cooling water hose 30 to which the cooling water cooled by the radiator 111 is supplied is connected, with reference to FIG. 5B and the like. It is provided with an outlet pipe 47 to which a cooling water hose 31 for supplying water is connected. An inlet passage 48 to which the inlet pipe 46 is connected is formed in the water pump cover 33, and the inlet passage 48 communicates with the central portion of the casing 45 as shown in FIG. 5B or the like and extends slightly forward and downward to the front of the vehicle. Will be set up. The inlet passage 48 arranged in this way can shorten the cooling water hose 30.

With reference to FIG. 12, the cooling water discharged from the water pump 29 by the rotation of the impeller 35 is applied to the inner surface of the water pump cover 33 between the water pump case 32 and the water jacket 26A of the cylinder head 13 (see FIG. 13). A supply path 49 for deriving to is formed. The supply passage 49 extends downward in a spiral shape from the rear portion of the casing 45 toward the front, and a delivery port 50 for delivering cooling water to the water jacket 26A corresponding to the lower end position of the supply passage 49 (FIG. 10). (See also) opens toward the cylinder head 13. As shown in FIG. 9, a cooling water inflow port 51 is formed on the mounting surface 42 of the cylinder head 13 to allow cooling water to flow in through the inlet 50, and a cooling water flow from the water pump 29 via the supply passage 49. The cooling water flowing in from the inlet 51 is supplied to the water jacket 26A of the cylinder head 13. As can be seen from FIG. 9 and the like, the cooling water inflow port 51 is biased toward the intake side and is arranged near the lower end of the cylinder head 13. The cooling water flowing through the cylinder head 13 and the cylinder block 12 is then returned to the water pump 29.

As shown in FIG. 9, the mounting surface 42 of the cylinder head 13 also has a cooling water outlet 52 (see FIG. 9) for returning the cooling water after cooling the engine 10 from the water jacket 26 to the water pump 29 side. It is formed. As can be seen from FIG. 9 and the like, the cooling water outlet 52 is provided on the same side surface (left side in this example) of the cooling water inlet 51 and the cylinder head 13, and is located appropriately forward of the cooling water inlet 51 and substantially above it. Is placed. As shown in FIGS. 8 and 10, the water pump case 32 also has a return port 53 that communicates with the cooling water outlet 52 and returns the cooled cooling water to the water pump 29. With reference to FIGS. 8 and 12, the cooling water recirculated to the water pump 29 via the recirculation port 53 is led out to the outlet pipe 47 on the inner surface of the water pump cover 33 with the water pump case 32. The outlet passage 54 is formed. The outlet passage 54 follows a path that is inclined forward and upward around the casing 45, starting from the return port 53 that is located substantially above the delivery port 50, and is an outlet pipe that is arranged above the water pump 29. It will be extended to 47.

The cooling water inlet 51, the cooling water outlet 52, and the rotating shaft 37 of the water pump 29 formed as described above are arranged substantially in a straight line in the vertical direction of the cylinder head 13 as shown in FIG. In this way, the cooling water inlet 51 and the cooling water outlet 52 for transmitting and receiving cooling water between the water pump 29, the water pump 29, and the cylinder head 13 are centrally arranged on the intake side of the cylinder head 13. ..

In the above case, in the water pump cover 33, as shown in FIG. 8, the inlet pipe 46 and the inlet passage 48 are connected via their flange portions. A thermostat 55 is attached to the joint between the inlet pipe 46 and the inlet passage 48. The thermostat 55 controls the supply and stop of the cooling water from the radiator 111 to the water pump 29.

Here, the inlet passage 48 and the outlet passage 54 provided on the water pump cover 33 intersect with each other in a vehicle side view as shown in FIG. 5B or FIG. The inlet passage 48 extends substantially in the front-rear direction on the outside of the water pump cover 33, the outlet passage 54 extends roughly in the vertical direction on the inside of the water pump cover 33, and the water pump cover 33 extends at the intersection of the two. It is partitioned by a part. In this case, as shown in FIG. 12, the water pump cover 33 is provided with a bypass passage 56 which is formed by drilling at the intersection thereof and communicates with the inlet passage 48 and the outlet passage 54. By appropriately communicating the inlet passage 48 and the outlet passage 54, hunting of the temperature of the cooling water flowing through them is prevented from occurring.

Further, as shown in FIG. 12, an air bleeding groove 57 connected to the inlet passage 48 and the outlet passage 54 is provided in the upper part of the water pump cover 33. The air bleeding groove 57 extends from the vicinity of the upper peripheral portion of the casing 45 communicating with the inlet passage 48 to the upper portion of the outlet passage 54 on the inner surface of the water pump cover 33. After injecting the cooling water into the water pump 29, a small amount of air remains in the upper part of the water pump case 32, but the air applied by the water pressure due to the rotation of the impeller 35 is passed through the air bleeding groove 57 to the water pump 29. Can be discharged from.

The cooling structure of the internal combustion engine of the present invention is provided with a breather mechanism and a secondary air supply mechanism. The breather chamber of the breather mechanism and the reed valve chamber of the secondary air supply mechanism are formed in the water pump case 32 and the water pump cover 33, and are provided integrally with the water pump 29 to form a water pump unit. First, in the breather mechanism, the breather chamber 58 is arranged adjacent to the front side of the water pump 29 as shown in FIG. 4A, that is, biased toward the exhaust side of the engine 10 when viewed from the side of the vehicle (see FIG. 5B).

In this case, the breather chamber 58 is formed by the cylinder head 13 and the water pump case 32, and is adjacent to the water pump 29. Specifically, as shown in FIG. 9, it is located on the front side of the water pump 29 on the side surface of the cylinder head 13, is included in a part of the pattern of the mounting surface 42, and its end surface is flush with the mounting surface 42. The shape rib 59 forms the outer shell of the breather chamber 58. The breather chamber half body 58A on the cylinder head 13 side is formed inside the outer shell. Similarly, as shown in FIG. 10, the front portion of the water pump case 32 extends forward, that is, toward the exhaust side, and the outer shell of the breather chamber 58 is formed by the circumferential rib 60 whose end surface is flush with the joint surface 43. It is formed. Inside the outer shell, the breather chamber half body 58B on the water pump case 32 side is configured. The breather chamber half body 58A and the breather chamber half body 58B are polymerized with each other to define the breather chamber 58, which has a pattern substantially similar to the pattern of the mounting surface 42 and the joint surface 43 described above. A seal 44 is interposed.

The breather chamber 58 formed between the cylinder head 13 and the water pump case 32 in this way is arranged adjacent to the front side of the water pump 29. In this case, the water pump case 32 and the breather chamber 58 do not substantially overlap in the vehicle side view, but the inlet pipe 46 of the water pump 29 overlaps the breather chamber 58 in the vehicle side view as shown in FIG. 5B.

Inside the breather chamber 58, a plurality of partition walls or partition walls 61 arranged so as to form a labyrinth structure are provided so as to be butt-assembled between the breather chamber half body 58A and the breather chamber half body 58B. As shown in FIG. 9, a blow-by gas vent 62 is formed on the side surface of the cylinder head 13 so as to be located outside the labyrinth structure and open from the valve chamber side to the breather chamber 58. Further, an oil return hole 63 that opens to the valve chamber side is formed at the bottom of the breather chamber 58 (in this example, the front corner). Further, in the breather chamber half body 58B, an outlet pipe 64 is attached to the upper part of the labyrinth structure in the breather chamber 58 as shown in FIG. A hose for supplying gas-liquid separated blow-by gas to the air cleaner is connected to the outlet pipe 64.

In the breather mechanism, the blow-by gas in the crankcase 11 enters the valve operating chamber through the cam chain chamber 25 and flows into the breather chamber 58 through the ventilation hole 62. In the breather chamber 58, the blow-by gas flows as shown by the dotted arrow in FIG. 9, and gas-liquid is separated while hitting the partition wall 61 having a labyrinth structure. The lubricating oil component separated from the blow-by gas is dropped along the partition wall 61 as shown by the solid arrow in FIG. 9, and is returned to the crankcase 11 side from the oil return hole 63 at the bottom of the breather chamber 58.

Next, in the secondary air supply mechanism, as shown in FIG. 8, the reed valve chamber 65 is substantially formed by the water pump case 32 and the water pump cover 33, and is adjacent to the breather chamber 58 in the vehicle width direction.
In the lower part of the breather chamber 58 integrally formed with the water pump case 32 as shown in FIG. 8, the reed valve chamber 65 is formed on the left outer surface in this example. As shown in FIG. 8, the reed valve chamber 65 is recessed in the outer surface of the breather chamber 58 so as to have a rectangular shape, for example. On the other hand, in the water pump cover 33, as shown in FIG. 12, the secondary air chamber 67 is located near the lower part of the supply path 49 and extends forward, that is, the secondary air chamber 67 is integrally formed with the water pump cover 33. And has an opening 67a that matches the rectangle of the reed valve chamber 65. When the water pump cover 33 is closed to the water pump case 32, the opening 67a overlaps the reed valve chamber 65, that is, the reed valve chamber 65 and the secondary air chamber 67 are coupled.

The reed valve chamber 65 formed below the breather chamber 58 is arranged on the exhaust side opposite to the water pump 29. The water pump 29 is arranged on the intake side on the side surface of the cylinder head 13, whereas the reed valve chamber 65 is substantially arranged on the exhaust side.

As shown in FIG. 8, the reed valve 66 is attached to the joint portion between the reed valve chamber 65 and the secondary air chamber 67 via the retainer 66a. A rubber seal is interposed at the joint between the reed valve chamber 65 and the secondary air chamber 67, for example. The reed valve 66 is opened and operated so as to allow secondary air to flow from the secondary air chamber 67 to the reed valve chamber 65. Further, the reed valve chamber 65 is formed with a communication hole 68 that communicates with the exhaust port 19 of the cylinder head 13 described above. Therefore, as shown in FIG. 9, the cylinder head 13 is formed with a communication hole 68A that communicates with the exhaust port 19 and communicates with the communication hole 68. An inlet pipe 69 extending rearward and upward is attached to the rear upper part of the secondary air chamber 67 as shown in FIG. A hose for supplying secondary air from the air cleaner is connected to the inlet pipe 69.

In the secondary air supply mechanism, the negative pressure of the exhaust port 19 acts on the reed valve 66 through the communication holes 68 and 68A at a predetermined timing. As a result, the reed valve 66 is opened, secondary air is circulated from the secondary air chamber 67 to the reed valve chamber 65, and the secondary air is further supplied to the exhaust port 19. In this way, clean air from the air cleaner can be taken in and supplied to the exhaust system to promote purification of the exhaust gas.

Here, as shown in FIGS. 5A and 5B, the breather chamber 58 has substantially the same length as the water pump 29 along the cylinder axis Z. The water pump 29 and the breather chamber 58 are arranged separately on the intake side and the exhaust side on the side surface of the cylinder head 13, and are set so that the positions and lengths in the height direction, that is, in the vertical direction are substantially the same between the two. To.

Further, as shown in FIG. 5A, the inlet pipe 69 leading to the reed valve chamber 65 is substantially the same position as the inlet pipe 46 of the water pump 29 in the vehicle width direction. The inlet pipe 46 of the water pump 29 overlaps with the breather chamber 58 as shown in FIG. 5B in the side view of the vehicle, but the secondary air chamber 67 is arranged below the inlet pipe 69, and the inlet pipe 69 connected to the secondary air chamber 67 is the water pump 29. It does not overlap with the inlet pipe 46 when viewed from the side of the vehicle.

In the operation of the cooling structure of the internal combustion engine according to the present embodiment, when the engine 10 is started, the rotating shaft 37 rotates via the gear 39 that meshes with the gear 41 of the camshaft 20, and the water pump 29 rotates at a predetermined speed. Rotate by number. The water pump 29 rotates at a high rotation speed of at least the camshaft 20 or higher, and the water pump 29 can be miniaturized by securing the flow rate by increasing the rotation speed in this way.

The cooling water cooled by the radiator 111 is supplied to the water pump 29 via the inlet passage 48 via the cooling water hose 30, and is supplied to the water pump 29 via the supply passage 49 from the outlet 50 via the cooling water inflow port 51 to the cylinder head. It is supplied to 13. In this case, the cooling water supplied from the cooling water inflow port 51 to the cylinder head 13 first flows through the water jacket 26A of the cylinder head 13 and flows into the cylinder block 12 as schematically shown in FIG. This cooling water flows through the water jacket 28 of the cylinder block 12, then returns to the water jacket 26 of the cylinder head 13, and is returned to the water pump 29 from the recirculation port 53 via the cooling water outlet 52. The cooling water that has returned to the water pump 29 is sent from the outlet pipe 47 at the upper part of the water pump 29 through the outlet passage 54 to the radiator 111 via the cooling water hose 31. By distributing the cooling water to the water jacket 26 and the water jacket 28 in this way, the engine 10 can be efficiently cooled.

Next, the main functions and effects in the cooling structure of the internal combustion engine according to the present invention will be described. First, the water pump 29 includes a water pump case 32 and a water pump cover 33. The breather chamber 58 and the reed valve chamber 65 are integrally formed with the water pump 29 in the water pump case 32 and the water pump cover 33, respectively.
By integrating the breather chamber 58 and the reed valve chamber 65 with the water pump 29 and unitizing them in this way, the width of the cylinder head 13 and the height of the engine 10 are realized while effectively realizing the functions of these accessories. Can be suppressed. Further, since the breather chamber 58 and the reed valve chamber 65 can be assembled to the cylinder head 13 integrally with the water pump 29, the assembling property thereof can be significantly improved and the number of parts can be reduced.

In this case, the breather chamber 58 is formed by the cylinder head 13 and the water pump case 32, and is adjacent to the water pump 29.
By having the water pump case 32 and extending a predetermined portion thereof to form the breather chamber 58, the sealing surface with the cylinder head 13 becomes the same height, that is, the water pump case 32 and the breather chamber 58 The joint surface 43 can be made uniform. Since the joint surface 43 is aligned with the mounting surface 42 of the cylinder head 13 and the seal 44 can be integrally molded, the assembling property and airtightness thereof are improved, and the cost can be reduced.

Since the breather chamber 58 is adjacent to the water pump 29, the mounting surface 42 and the joint surface 43, and therefore the seal 44, can be miniaturized to be compact as a whole.
Further, the cooling effect on the blow-by gas flowing in the breather chamber 58 adjacent to the water pump 29 is improved, so that the gas-liquid separation capacity in the breather chamber 58 is also improved. Further, although the reed valve 66 is sealed with a rubber seal, the durability is improved by cooling the seal.

Further, as shown in FIG. 4B and the like, the reed valve chamber 65 is formed by an outer wall of the breather chamber 58, that is, a water pump case 32, and a secondary air chamber 67, that is, a water pump cover 33 that is closed to the outer wall, that is, a water pump cover 33. Adjacent to the outside of the breather chamber 58 in the direction.
By narrowing the width of the reed valve chamber 65 to the breather chamber 58 and adjoining the reed valve chamber 65 in this way, it is possible to make the vehicle width direction particularly compact.

Further, the breather chamber 58 has substantially the same length as the water pump 29 along the cylinder axis Z, as shown in FIG. 5B and the like.
In this way, the breather chamber 58 can be secured without protruding from the water pump 29, that is, the required capacity of the breather chamber 58 can be secured while achieving compactness.

Further, when viewed from the side of the vehicle, the inlet pipe 46 of the water pump 29 overlaps with the breather chamber 58 as shown in FIG. 5B. In this case, the inlet pipe 69 of the reed valve chamber 65 is further connected to the water pump 29 as shown in FIG. 5A. It is substantially the same height as the inlet pipe 46 in the vehicle width direction.
By making the inlet pipe 46 adjacent to the reed valve chamber 65 and making the position in the vehicle width direction the same as that of the inlet pipe 69, the capacity of the secondary air chamber 67 is secured, that is, the flow rate of the secondary air is increased. While ensuring, the width of the cylinder head 13 in the left-right direction can be suppressed.

Further, the water pump 29 is arranged on the intake side and the breather chamber 58 and the reed valve chamber 65 are both arranged on the exhaust side when viewed from the side of the vehicle.
Secondary air passages formed by the communication holes 68 of the reed valve chamber 65 and the communication holes 68A of the cylinder head 13, which are communicated with the exhaust port 19 of the cylinder head 13, are linearly arranged. Therefore, the workability of the communication holes 68 and the communication holes 68A can be improved, and the secondary air can be easily flowed to improve the distribution efficiency.

Although the present invention has been described above with various embodiments, the present invention is not limited to these embodiments and can be modified within the scope of the present invention.
In the above embodiment, an example of a 4-cycle single-cylinder DOHC engine has been described as the engine 10, but a 4-cycle single-cylinder SOHC engine may be used, and in any case, an engine having two or more cylinders other than a single cylinder may be used. It is applicable as well.

10 engine, 11 crankcase, 12 cylinder block, 13 cylinder head, 14 cylinder head cover, 15 crankshaft, 16 transmission case, 17 intake port, 18 combustion chamber, 19 exhaust port, 20,21 camshaft, 22,23 sprocket, 24 cam chain, 25 cam chain chamber, 26, 26A water jacket, 27 cylinder bore, 28 water jacket, 29 water pump, 30, 31 cooling water hose, 32 water pump case, 33 water pump cover, 35 impeller, 37 rotation shaft, 38 oil seal, 39, 41 gear, 42 mounting surface, 43 joint surface, 44 seal, 46 inlet pipe, 47 outlet pipe, 48 inlet passage, 49 supply path, 50 outlet, 51 cooling water inlet, 52 cooling water outlet , 53 Recirculation port, 54 Outlet passage, 55 Thermostat, 56 Bypass passage, 57 Air bleeding groove, 58 Breather chamber, 59,60 Circumferential rib, 62 Vent hole, 63 Oil return hole, 65 Reed valve chamber, 66 Reed valve , 67 Secondary air chamber, 68 communication holes, 69 inlet pipes, 100 motorcycles.

Claims (5)

A water-cooled type equipped with a thermostat that controls the supply and stop of the cooling water supplied to the water-cooled engine and a reed valve that controls the amount of secondary air supplied to the exhaust passage of the water-cooled engine. In the engine
A cooling structure for an internal combustion engine, characterized in that the storage portion of the thermostat and the storage portion of the reed valve are integrally molded. The cooling structure for an internal combustion engine according to claim 1, wherein the storage portion of the reed valve is integrally provided on the side surface of the storage portion of the thermostat. The cooling structure for an internal combustion engine according to claim 1 or 2, wherein the thermostat and the reed valve are arranged adjacent to each other when viewed from the side of the engine. The cooling structure for an internal combustion engine according to any one of claims 1 to 3, wherein the thermostat accommodating portion and the reed valve accommodating portion are attached to a side surface of the cylinder head of the engine. The cooling structure for an internal combustion engine according to claim 4, wherein the storage portion of the thermostat and the storage portion of the reed valve are housed within the front-rear width of the cylinder head when viewed from the side of the engine.

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