JP2001032715A - Installation structure of thermostat in water-cooled internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve assemblability and reduce cost by simplifying the installation structure of a thermostat, and also improve cooling responsiveness and cooling stability of cooling water by a radiator in the installation structure of a cooling water temperature detecting thermostat in a water-cooled internal combustion engine in which the radiator is installed on the upper part of the internal combustion engine. SOLUTION: In this installation structure of a cooling water temperature detecting thermostat 82 in a water-cooled internal combustion engine 30 in which a radiator 41 is installed on the upper part of the internal combustion engine 30, the thermostat 82 is arranged in a cooling water circulating route and is arranged to be placed in the tank (storage chamber 41a) of the radiator 41. The thermostat 82 is installed by being held between the cooling water outlet 43 of the internal combustion engine 30 and the cooling water inlet 130 of the radiator 41.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermostat mounting structure for a water-cooled internal combustion engine, and more particularly to a thermostat mounting structure for a water-cooled internal combustion engine in which a radiator is mounted on an upper portion of an internal combustion engine. The present invention relates to a mounting structure of a thermostat in a water-cooled internal combustion engine which has improved assemblability and reduced costs.

[0002]

2. Description of the Related Art Conventionally, in a water-cooled internal combustion engine in which a radiator is mounted on an upper portion of an internal combustion engine, when a thermostat is provided in a circulation path of cooling water, a radiator cooling fan is provided between the internal combustion engine and the radiator. The thermostat is sandwiched between the cooling water outlet opening of the internal combustion engine and the end of the thermostat cover conduit, and the other end of this conduit is connected to the cooling water inlet of the radiator via a hose. (See Japanese Patent Publication No. 5-78642).

[0003]

However, in such a conventional thermostat mounting structure, a dedicated cover conduit for holding and covering the thermostat is required, and the cover conduit is connected to a radiator. Is necessary, the number of parts is increased, and this is a factor of cost increase. In addition, there were operations such as attaching a thermostat cover conduit to an internal combustion engine and inserting a hose, and it was hard to say that the assembly was excellent.

[0004] The present invention solves the above-mentioned problems of the conventional thermostat mounting structure in a water-cooled internal combustion engine, simplifies the mounting structure, improves the assemblability, and reduces the cost. At the same time, the radiator improved the cooling response and cooling stability of the cooling water.
It is an object to provide a thermostat mounting structure for a water-cooled internal combustion engine.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a thermostat mounting structure for a water-cooled internal combustion engine which solves the above-mentioned problems. In a thermostat mounting structure in a water-cooled internal combustion engine having a radiator mounted on an upper portion, the thermostat is provided in a circulation path of cooling water so as to face a tank of the radiator. 1 is a mounting structure of a thermostat in an internal combustion engine.

The invention described in claim 1 is constructed as described above, and the thermostat is conventionally required because it is provided in the circulation path of the cooling water so as to face the inside of the radiator tank. This eliminates the need for a dedicated cover conduit for holding and covering the thermostat and a hose for connecting the cover conduit to a radiator, thereby reducing the number of parts and reducing costs. . In addition, the work of attaching and inserting such conventionally required parts is not required, and the assembling property can be improved.

Further, since a thermostat cover conduit and a hose are not required, the cooling water inlet and outlet of the internal combustion engine and the cooling water inlet and outlet of the radiator can be connected and connected without connecting pipes. Is located at the closest position, the temperature of the cooling water cooled by the radiator (when the thermostat is provided at the cooling water inlet of the internal combustion engine) or the cooling water heated by the internal combustion engine The temperature of the engine (when a thermostat is provided at the outlet of the cooling water of the internal combustion engine) to quickly detect the effect of the cooling water circulation and improve the responsiveness of cooling of the cooling water by the radiator. Can be.

Further, since the thermostat is less affected by the outside air temperature, it is possible to accurately control the temperature of the cooling water whose temperature has risen by cooling the internal combustion engine and appropriately control the cooling water circulation. The stability of cooling of the cooling water by the radiator can be improved.

According to the second aspect of the present invention, the thermostat is mounted so as to be sandwiched between the cooling water port of the internal combustion engine and the cooling water port of the radiator.

As a result, the thermostat can be fixed in the circulation path of the cooling water by extremely simple means, and the thermostat can be provided so as to face the inside of the tank of the radiator.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the invention described in claims 1 and 2 of the present application shown in FIGS. 1 to 8 will be described below. FIG. 1 is a left side view of a motorcycle equipped with a water-cooled internal combustion engine to which the thermostat mounting structure according to the present embodiment is applied, and FIG.
2 is a cross-sectional view taken along line II-II of FIG. 2, and is a schematic cross-sectional view of a power unit including a water-cooled internal combustion engine cut along a plane orthogonal to a crankshaft and including a cylinder axis; FIG.
FIG. 4 is a cross-sectional view taken along line IV-IV of FIG. 2, and FIG. 4 is a side view of the radiator portion, and FIG. 5 is a cross-sectional view taken along line VV of FIG. 2. FIG. 6 is a sectional view of FIG.
FIG. 7 is a plan view of a radiator, and FIG.
It is a front view of a shroud.

In the following, “front, rear, left and right” means
When viewed in the traveling direction of the vehicle, it indicates the front, rear, left and right of the vehicle body. Further, "the center of the vehicle body" means a vertical plane passing through the center in the left-right width direction of the wheel mounted on the motorcycle. Further, “near the center of the vehicle body” means within the range of the width of the wheels mounted on the motorcycle in the left-right width direction.

As shown in FIG. 1, a motorcycle 1 to which a radiator mounting structure to a power unit 7 according to the present embodiment is applied has a front frame 3 and a rear frame 4 connected to each other by bolts 2. Having a main frame consisting of

At the front of the front frame 3, a front suspension mechanism for suspending the front wheels 5 and a steering mechanism for steering the front wheels 5 are provided. Behind the rear of the rear frame 4, a power unit 7 for driving rear wheels is provided. A rear suspension mechanism for suspending the rear wheel 6 is provided at a rear part of the rear frame 4, and a seat 8 is provided at an upper front part of the rear frame 4.

Further, a front fender 9, a front cover 10, a floor step 11, a frame body cover 12, and a rear fender 13 are attached to the motorcycle 1 in order from the front to the rear.
A pair of side covers 14 are provided. Inside the frame body cover 12 below the seat 8, a storage box 15 for storing a helmet or the like is provided.

The front suspension mechanism is a swing arm 16 located on the right side of the front wheel 5 and supported on a support shaft at the front lower end of the front frame 3 so as to be vertically swingable.
And a shock absorber 17 having one end pivotally attached to the swing arm 16 and the other end pivotally attached to the front frame 3. An axle holder 19 is attached to the front end of the swing arm 16 via a king pin 18 so as to be swingable in the left-right direction.
The front wheel 5 is rotatably supported.

The steering mechanism includes a front frame 3
A handle post 22 rotatably supported by a head pipe 21 attached to the front upper end of the handle post;
A steering arm 23 pivotally supported on the support shaft at the lower end of the steering arm 23 in a vertical direction; a link 24 pivotally connected at one end to the steering arm 23 and at the other end to an arm 19a of the axle holder 19. And

As described above, the steering mechanism and the front suspension mechanism are configured to be independent from each other, thereby improving the maneuverability.

Although not shown in detail, a front portion of the power unit 7 has a hanger hole 26 of a bracket 25 attached to each of the pair of left and right rear frames 4, and a front end portion of a lower crankcase 42l of the internal combustion engine 30, which will be described later. And bushings provided at the front end of the cylinder head 43, respectively.
46 (see FIGS. 2 and 3), and is supported by the rear frame 4 so as to be swingable by a pair of hanger bolts respectively inserted.

On the other hand, the rear part of the power unit 7 is attached to the rear part of the left rear frame 4 via a shock absorber 27. This allows the power unit 7 to swing up and down in accordance with the ups and downs of the road surface during traveling.

The axis of both bushings 46 is an internal combustion engine.
The crankshaft 30 is located slightly above a horizontal plane including the axis C1 of the crankshaft 31. And both axes are located below the upper surface position of the step floor 11,
The power unit 7 is arranged at a position where the upper end surface of the power unit 7 excluding the radiator 41 is substantially equal in height to the upper surface of the step floor 11, so that the center of gravity of the vehicle body is reduced.

The power unit 7 includes an internal combustion engine 30 and a power transmission device 90 having a transmission 91 and a final reduction gear 110. The internal combustion engine 30 is a spark-ignition, 4-cycle, single-cylinder, water-cooled internal combustion engine.
A flexible air introduction pipe 33 extending from an air cleaner 32 disposed below the air cleaner 32 is connected to an upstream end of a throttle body 34 disposed on the right side of the vehicle body. Throttle body
An intake pipe 35 connected to an intake port of a cylinder head 43 is connected to a downstream end of the cylinder 34, and a fuel injection valve 36 is attached to the intake pipe 35. Fuel is supplied to the fuel injection valve 36 from a fuel tank 37 arranged below the step floor 11.

On the right side of the vehicle body, a cylinder head 43 is provided.
An exhaust muffler 39 connected to an exhaust pipe 38 connected to the exhaust port is disposed. Further, a radiator 41 to which cooling air from a cooling fan 58 disposed in front of the internal combustion engine 30 is applied is disposed above the internal combustion engine 30.

The power transmission device 90 has a planetary gear type transmission 91 whose output is the drive shaft 111 of the final reduction device 110.
Is transmitted to the axle of the rear wheel 6 so that the rear wheel 6 is driven.

Next, the power unit 7 will be described in more detail. As illustrated in FIGS. 2 and 3,
The internal combustion engine 30 is configured such that a crankcase 42, a cylinder head 43, and a cylinder head cover 44 are sequentially stacked and assembled.

The crankcase 42 is divided into upper and lower crankcases 42u and 42l by a split plane A that includes the axis of the crankshaft 31 and is inclined with respect to the horizontal plane. It is directed to the upper left of the vehicle. A cylinder 45 having an axis inclined upward and to the right with respect to the center of the vehicle body is formed integrally with the upper part of the upper crankcase 42u.
A cylinder head 43 is mounted on a mounting surface B facing the upper right of the vehicle body.

The mounting surface B is inclined with respect to the horizontal plane and the split surface A, and the plane including the split surface A and the plane including the mounting surface B correspond to the lower right of the upper and lower crankcases 42u and 42l (see FIG. 2 at the lower left). The upper and lower crankcases 42u and 42l also serve as a part of a transmission case 92 that covers the front part of the transmission, which is a component of the power transmission device 90 that transmits the power of the crankshaft 31 to the rear wheel 6.

A tube bush 46 through which a hanger bolt for supporting the power unit 7 is inserted into the bracket 25 of the rear frame 4 is provided on the outer surface of the front left end of the lower crankcase 42l. The tube bush 46 includes a cylindrical portion 46a integrally formed with the lower crankcase 42l, an elastic tube 46b made of a cylindrical rubber or the like whose outer peripheral surface is fixed to the inner peripheral surface of the cylindrical portion 46a, and an outer peripheral surface thereof. Is fixed to the inner peripheral surface of the elastic tube 46b and a metal insertion tube 46c through which a hanger bolt is inserted. A tube bush 46 having the same structure is also provided on the outer surface of the front lower right end of the cylinder head 43.

The crankcase 42 has a so-called vertically disposed crankshaft 31 oriented in the front-rear direction of the vehicle body.
Are rotatably supported via a pair of main bearings 49 and 50. Each of the main bearings 49 and 50 includes upper and lower crankcases 42u,
42l are held in semi-cylindrical concave grooves formed on the split surface A, respectively, so that the axis C1 of the crankshaft 31 is positioned on the split surface A.

A connecting rod 48 having a small end pivotally attached to a piston pin of a piston 47 slidably fitted in a cylinder bore of the cylinder 45 and a large end pivotally attached to a crankpin of the crankshaft 31 is provided. The crankshaft 31 is driven to rotate by the reciprocating piston 47. Also, the crankshaft
31 has a balance weight 31a on the opposite side of the piston pin.
Is provided to suppress the generation of vibration due to the reciprocating motion of the piston 47 and the connecting rod 48.

Here, the relationship between the split surface A, the mounting surface B, and the axis of the cylinder 45 will be described in more detail. The axis C of the cylinder 45 is orthogonal to the axis C1 of the crankshaft 31.
2, the angle α formed by the line of intersection between the split plane A and the reference plane and the reference vertical line, which is a vertical half line extending upward from the axis C1 of the crankshaft 31, is an acute angle. . The angle β between the axis of the cylinder 45 and the reference vertical line is also acute, and the angles α and β are substantially equal.

The angle γ, which is the angle between the extension line of the line of intersection of the mounting surface B and the reference plane and the reference vertical line and is the isotopic angle of the angle α, is smaller than the angle α. Accordingly, in the reference plane, the angles formed by the split surface A, the mounting surface B, and the axis of the cylinder 45 with the center C0 of the vehicle body are also the angles α, β, and γ, respectively. The values of these angles α, β, and γ are appropriately set in consideration of the size of the bank angle to be set and the like.

The cylinder head 43 has an intake port to which the intake pipe 35 is connected, an exhaust port to which the exhaust pipe 38 is connected, and a supercharge port to which a discharge air conduit connected to the supercharger 52 is connected. And communicates with a combustion chamber formed on the lower surface of the cylinder head 43.

The combustion chamber is supplied with a mixture of fuel and air injected from a fuel injection valve 36 attached to an intake pipe 35 toward an intake port. Then, a spark plug 51 for igniting the air-fuel mixture faces the combustion chamber,
Attached to 43. A supercharging cylinder 52a forming a housing of the supercharger 52 is fitted in a hole formed in the rear end surface of the cylinder head 43.

The cylinder head 43 is further provided with a camshaft 53 disposed so as to point in the front-rear direction of the vehicle body.
It is rotatably supported via 4, 55. Each bearing 54, 5
5 is held in semi-cylindrical concave grooves formed on the mounting surface B of the upper crankcase 42u and the cylinder head 43, respectively, so that the axis C3 of the cam shaft 53 is located on the mounting surface B. ing. With such an arrangement of the cam shaft 53, the height of the cylinder 45 in the axial direction can be reduced as compared with an internal combustion engine in which the cam shaft 53 is supported only by the cylinder head 43.

As shown in FIG. 3, an AC generator 56 is provided at a front end portion of the crankshaft 31 which is located forward of a main bearing 49 on the front side, and a rotor 56a of the generator 56 is provided.
Is fixed to the crankshaft 31 by being penetrated by a bolt screw portion on the front end face of the crankshaft 31 and fastened by a nut 57. A cooling fan 58 that sends cooling air to the radiator 41 is bolted to the rotor 56a of the generator 56.
They are attached together by 59. The periphery of the cooling fan 58 is covered by a shroud (fan cover) 40. An air intake 40a is formed at the front of the shroud 40.

On the other hand, behind the main bearing 50 on the rear side of the crankshaft 31, a first drive gear 60 and a second drive gear 61 are mounted in order toward the rear so as to rotate integrally with the crankshaft 31. Have been. Further, a fitting hole coaxial with the axis C1 of the crankshaft 31 is formed in the rear end face of the crankshaft 31, and a hollow oil pump drive shaft 62a is fitted in the fitting hole, and is integrated with the crankshaft 31. It is designed to rotate.

The oil pump 62 is of a troicoid type, and the rotor 62b is provided with an oil in the internal space of the casing formed by using the joint surfaces of the upper and lower crankcases 42u and 42l and the transmission case 92. Pump drive shaft 62a
Is driven to rotate.

The oil stored in the bottom of the lower crankcase 42l is transmitted by the oil pump 62 to the transmission case 92l.
The oil that is sucked and discharged through the suction passage 63 formed in the camshaft 53, the center shaft 93 of the transmission, and the bearings passes through oil passages and oil pipes provided in the crankcase 42 and the transmission case 92. The parts are supplied respectively. The oil pump drive shaft 62a is provided on both main bearings 49 and 50 of the crankshaft 31 and the sliding portion between the crankpin and the large end of the connecting rod 48.
Oil is supplied through the inside of the.

The first drive gear 60 meshes with a large gear 65 mounted so as to rotate integrally with the idler shaft 64. Since the idler shaft 64 also serves as a balancer shaft as described later, the number of teeth of the large gear 65 is set equal to the number of teeth of the first drive gear 60 so that the idler shaft 64 rotates at the same rotation speed as the crankshaft 31. I have.

In order to rotate the cam shaft 53, a small gear 66 meshing with a cam gear 67 provided so as to rotate integrally with the cam shaft 53 is provided integrally with the large gear 65. Then, the camshaft 53 rotates once every two rotations of the crankshaft 31 by the series of gear trains. A rotating plate is attached to the front end of the cam shaft 53, and a rotation position sensor is provided.
By detecting the rotational position of the rotary plate, the engine stroke state necessary for fuel injection timing control is detected.

The cam gear 67 is a double-acting piston type supercharger.
Supercharging crankshaft 52 for reciprocating 52 supercharging piston 52b
Spline joined to c. The camshaft 53 is formed with a hollow portion serving as an oil passage for supplying oil to a sliding portion between each cam and each rocker arm, which will be described later, and at the end of the hollow portion on the supercharger side, The extension of the supercharging crankshaft 52c is press-fitted. Thus, the cam shaft 53 rotates integrally with the supercharged crank shaft 52c.

The camshaft 53 is provided with an intake cam, an exhaust cam (not shown), and an intake cam, an exhaust cam and a supercharge cam for driving the supercharging valve 69 to open. Among them, the intake valve 68 is driven to open by a second rocker arm 71 which is oscillated by a rod 72 which is lowered by a first rocker arm 70 which is oscillated in contact with the intake cam. Although not shown, the exhaust valve is also driven to open at a different timing by a similar mechanism. On the other hand, supercharging valve
69 is the first rocker arm that swings by contacting the supercharging cam
The valve is driven to open by a second rocker arm 74 which is swung by a rod 75 pushed up by 73.

The idler shaft 64 is disposed so as to point in the front-rear direction of the vehicle body, is formed in a stepped cylindrical shape, and has a large cylindrical portion.
64a and a small cylindrical portion 64b. The large cylindrical portion 64a and the small cylindrical portion 64b are rotatably supported by bearings 77 and 78 held by upper and lower crankcases 42u and 42l, respectively.

Each of these bearings 77 and 78, like the main bearings 49 and 50 of the crankshaft 31, includes both upper and lower crankcases 42u and 42u.
1 are held in semi-cylindrical concave grooves formed on the split surface A, respectively, so that the axis of the idler shaft 64 is positioned on the split surface A. Also, the split surface A is the center of the vehicle C
0, the axis C4 of the idler shaft 64 is located below the axis C1 of the crankshaft 31 and on the right side (left side in FIG. 2) with respect to the center C0 of the vehicle body. I have.

Inside the large cylindrical portion 64a of the idler shaft 64,
A cooling water pump 79 housing (magnetic cooling water pump) is provided with a radial gap from the inner peripheral surface of the large cylindrical portion 64a.
79 partition walls) 79a are accommodated. This housing 79a
A cover 79b of a cooling water pump 79 is attached in a liquid-tight manner, and a pipe (water guide pipe) 80 from a tank on the outlet side of the radiator 41 is connected to the cover 79b.

Although not shown in detail, the upper crankcase 42u communicates with a discharge portion of a cooling water pump 79, and a cooling water jacket formed around the cylinder bore.
An ejection hole 81 communicating with 84 is formed (see FIGS. 2 and 5). FIG. 5 shows an enclosure surrounding the periphery of the alternator 56.
Part of 128 is externally viewed. The surrounding wall 128 is formed so as to protrude from a front outer surface of the upper crankcase 42u.

In the pump chamber formed by the housing 79a and the cover 79b, the pump chamber extends in the axial direction in the pump chamber, and has one end on the top of the cover 79b and the other end on the housing 79a.
A rotating shaft 79c, which is rotatably supported, is provided at the bottom of the shaft. The cooling water pump 79 has three blades, and has an impeller 79d integrally attached to a rotating shaft 79c, and a permanent magnet 79e is attached to the shaft of the impeller 79d in the circumferential direction.

In the gap between the inner peripheral surface of the large cylindrical portion 64a of the idler shaft 64 and the housing 79a, a small gap is provided between the inner peripheral surface of the large cylindrical portion 64a and the housing 79a. A permanent magnet 79f is attached in the circumferential direction,
A magnetic coupling is formed between the impeller 79d and the permanent magnet 79e on the shaft.

Therefore, when the idler shaft 64 rotates,
The impeller 79d rotates through this magnetic coupling,
The cooling water that has flowed into the pump chamber through the water pipe 80 is pressurized by the cooling water pump 79, passes through the discharge section of the cooling water pump 79, and passes through the discharge hole 81 of the upper crankcase 42 u.
It is pumped to 84.

As shown in FIG. 2, the radiator 41 is disposed so as to be bridged between a V-shape formed by the upper crankcase 42u and the cylinder head 43, and has both left and right ends. The upper crankcase 42u is fixed to the left end of the upper surface of the upper crankcase 42u and the right end of the upper surface of the cylinder head 43 by bolts 121 via stays (mounting plates) 120.

The cooling water which has finished cooling the high temperature portions of the cylinder 45 and the cylinder head 43 is, as shown in FIG.
The coolant flows from the cooling water outlet of the cylinder head 43 into the inlet-side tank 122 (see FIG. 7) of the radiator 41 via the thermostat 82.

The cooling water outlet of the cylinder head 43 is formed in a protruding cylindrical shape as shown in FIGS. 2 and 6, and the protruding cylindrical portion 43a is connected to the inlet tank 12 of the radiator 41.
2 is inserted into the housing chamber 41a by penetrating the chamber wall of the housing chamber 41a formed integrally with the side of the cooling water outlet of the cylinder head 43 and the inlet-side tank 122 of the radiator 41. Fluid communication is provided. Thermostat 82
The protruding cylindrical portion 43a is arranged and attached in the cooling water circulation path at a portion penetrating the chamber wall of the storage chamber 41a.

The accommodation room 41a is provided with the radiator as described above.
It is formed integrally with the side of the inlet-side tank 122 of 41 and forms a part of the inlet-side tank 122. And the radiator
It is provided so as to be in contact with substantially the latter half of the right end of the 41 core portion.

Here, the mounting structure of the thermostat 82 will be described in more detail with reference to FIGS. 2, 6 and 7. In the portion where the protruding cylindrical portion 43a penetrates the chamber wall of the storage chamber 41a, the protruding cylindrical portion 43a is formed on the chamber wall (bottom wall) of the storage chamber 41a.
A recessed cylindrical portion 130 for receiving a is formed so as to be recessed, and the first half of the protruding tubular portion 43a is fitted to the recessed cylindrical portion 130. The inner end of the concave cylindrical portion 130 is reduced in diameter, and an annular step portion 130a is formed there. The concave cylindrical portion 130 forms a cooling water inlet of the radiator 41.

An annular flange 82a protruding from the outer peripheral surface of the body of the thermostat 82 is sandwiched between the end surface of the protruding cylindrical portion 43a and the inner surface of the step portion 130a of the concave cylindrical portion 130 via a sealing means. In this way, the thermostat 82 is sandwiched and mounted between the cooling water outlet of the cylinder head 43 corresponding to the cooling water outlet of the internal combustion engine 30 and the cooling water inlet of the radiator 41. The valve body portion 82b of the thermostat 82 has penetrated considerably deeply into the accommodation room 41a, and the thermostat 82 is mounted so as to face deeply into the accommodation room 41a. The wax part 131 of the thermostat 82 is arranged on the cooling water outlet side of the cylinder head 43.

The fitting of the projecting cylindrical portion 43a to the concave cylindrical portion 130 and the clamping of the end surface of the projecting cylindrical portion 43a of the thermostat 82 and the inner surface of the step portion 130a of the concave cylindrical portion 130 are performed by the radiator 41 described above. In this way, it is performed at the same time as being arranged and fixed so as to span the V-shape formed by the upper crankcase 42u and the cylinder head 43.

As described above, the radiator 41 is disposed here by utilizing the V-shaped space formed by the upper crankcase 42u and the cylinder head 43, so that the space for the radiator mounting structure can be reduced. As a result, the power unit 7 can be made more compact. In addition, this makes it possible to widen the storage space below the seat 8.

Further, there is no need to connect the cooling water outlet of the cylinder head 43 to the inlet-side tank 122 of the radiator 41 via a pipe such as a hose, and a dedicated thermostat is not required. Also becomes unnecessary, and the degree of freedom in arranging peripheral components can be increased. In addition, the communication connection of the cooling water passage is facilitated, and the cooling water passage between the cylinder head 43 and the radiator 41 is minimized with the thermostat 82 interposed therebetween, so that the cooling performance can be further stabilized.

The structure of the radiator 41 will be described in more detail. As shown in FIGS. 2, 4 and 7, the radiator 41 includes a cooling water inlet-side tank 122 and an outlet-side tank 123, and these two tanks 122, 12
3 are connected by a number of finned heat transfer tubes 124.

The overall shape of the radiator 41 is an elongated shape in which the central portion in the longitudinal direction in the front view is slightly larger upward and slightly swelled downward (see FIG. 2).
41, this slender direction (length direction), upper crankcase
It is arranged and fixed in the same direction as that of bridging the V-shaped valley formed by 42u and the cylinder head 43.

The overall shape of the radiator 41 is substantially rectangular in plan view, and one of the inlet-side tanks 122 for receiving the cooling water flowing out of the housing chamber 41a into which the projecting cylindrical portion 43a of the cylinder head 43 fits. Only the end portion has a shape protruding in the length direction (see FIG. 7). The size and shape of the radiator 41 are appropriately determined in consideration of a required cooling capacity, a layout of peripheral components, and the like.

The cooling water flows from the inlet-side tank 122 into the many finned heat transfer tubes 124, where the cooling fan
It is cooled by the cooling air discharged from 58. The cooling water cooled in the finned heat transfer pipe 124 then flows into the outlet side tank 123, and from a cooling water outlet 125 provided at one end of the tank 123 via a pipe (water pipe) 80. It is led to the suction part of the cooling water pump 79.

After the cooling air is discharged from the cooling fan 58, a part of the peripheral wall of the shroud 40 bulges in the radial direction and extends in the axial direction. 8), although not shown in detail, a U-shaped air guide wall 12 protruding from the upper surface of the upper crankcase 42u.
6 (see FIGS. 2 and 4), while flowing through the air guide passage D, the upper crankcase 42u and the cylinder head
Radiator 41 from the bottom of the V-shaped space formed by
Flows into the core portion.

The cooling air that has flowed into the core of the radiator 41 flows while diffusing upward and to the left and right in the core, and flows out of the core. During this time, the heat transfer pipes 124 are uniformly contacted with a large number of finned heat transfer tubes 124 to perform effective indirect heat exchange with the cooling water flowing inside.

A cooling water replenishing section 127 is provided above the inlet-side tank 122 of the radiator 41. Although not shown in detail, the cooling water replenishing unit 127 is integrally provided with a relief mechanism.

A cylindrical weight 83 having an opening at a part thereof is attached to the outer peripheral surface of the large cylindrical portion 64a of the idler shaft 64, and is generated by rotation of the crankshaft 31 having the balance weight 31a. A balancer for suppressing the vibration and the vibration generated by the reciprocation of the piston 47 and the connecting rod 48 is formed.

Therefore, the idler shaft 64 is a drive shaft for driving the cooling water pump 79 and also serves as a balancer shaft. As described above, the idler shaft 64 provided in the drive mechanism that drives the cam shaft 53 functions as a drive shaft of the cooling water pump 79 and also functions as a balancer shaft, so that the compact size of the internal combustion engine 30 is achieved. As a result, a plurality of rotating shafts can be compactly arranged even in a narrow space.

The cam shaft 53 and the idler shaft 64 are
With respect to the 45 axes, the plane including the split surface A and the plane including the mounting surface B intersect, that is, the two planes are arranged on the side approaching each other. With such an arrangement of the cam shaft 53 and the idler shaft 64, the idler shaft 64 supported on the split surface A and the cam shaft 53 supported on the mounting surface B can be arranged close to each other. The two can be directly connected by the small gear 66 and the cam gear 67 without interposing another idle shaft between the cam shaft 53 and the cam shaft 53. Thus, the height of the cylinder 45 in the axial direction can be suppressed low, and the number of components can be reduced.

Further, due to such an arrangement of the cam shaft 53 and the idler shaft 64, as a result, the plane including the split surface A and the plane including the mounting surface B are sandwiched between these two sides on the side approaching each other. Since the narrow space is effectively used, a wide space can be formed on the side surface of the cylinder 45 opposite to the cylinder 45, and the radiator 41, which is one of the peripheral parts, is formed in the space as described above. Can be arranged.

The planetary gear type transmission 91, which is a component of the power transmission device 90 of the power unit 7, includes a center shaft 93, an input gear 94, a starting clutch 95, and second-, third-, and fourth-speed transmission clutches. 96 to 98, and an output shaft 99.

A center shaft 93 oriented in the front-rear direction of the vehicle body is the center shaft of the transmission 91. The front end of the center shaft 93 is located on the split surface A of the upper and lower crankcases 42u and 42l. Cases 42u and 42l are fitted into bottomed semi-cylindrical concave grooves formed on the inner surfaces of the front ends of the front ends of the case 42u and 42l, respectively. The gear case 114 is inserted and supported in a support hole.

The shaft is mounted on the final reduction gear case 114 and covers the shaft end so as to be non-rotatably supported. The axis C5 of the center shaft 93 is located on the split plane A between the upper and lower crankcases 42u and 42l.

The front end of the center shaft 93 is, as described above,
It is supported by the front ends of the two crankcases 42u and 42l, and is located in front of the vehicle with respect to the rear end of the crankshaft 31, so that the crankshaft 31 and the center shaft 93 overlap in the front-rear direction. The power unit 7 can be disposed, and the length of the power unit 7 in the front-rear direction can be reduced, so that the power unit 7 can be made compact.

The second drive gear 61 of the crankshaft 31 is provided with a transmission
A boss 101 with a flange rotatably fitted to the center shaft 93 of the 91 is engaged with an input gear 94 attached to a flange provided at a central portion in the axial direction of the boss 101. Boss with flange
The rear part of 101 is coupled to rotate integrally with the clutch inner 95a of the starting clutch 95.
Small idler shaft gear 10 constituting the reduction mechanism of the starting motor
4 is engaged with the starting driven gear 105
Mounted via 6. Reference numeral 102 denotes a drive gear directly connected to the rotation shaft of the starting motor, and reference numeral 103 denotes a large idler shaft gear that meshes with the drive gear 102.

The starting clutch 95 includes a clutch inner 95a,
The clutch inner 95a and the clutch outer 95b are connected by the operation of the centrifugal weight 95c when the clutch inner 95a exceeds a predetermined rotation speed, having the clutch outer 95b and the centrifugal weight 95c. Thus, the starting clutch 95 is completely connected. Each of the speed change clutches 96 to 98 has a planetary gear mechanism and a clutch mechanism.

An output gear 107 is mounted on the output shaft 99 of the planetary gear type transmission 91 so as to rotate integrally therewith. The output gear 107 is connected to the gear 112 fixed to the drive shaft 11 of the final reduction gear 110. Are engaged. A bevel gear (not shown) is formed at the rear end of the drive shaft 111 disposed in the front-rear direction of the vehicle body. The bevel gear meshes with a driven bevel gear mounted on the axle of the rear wheel 6. In this way, the rotation of the output shaft 111 is reduced and transmitted to the rear wheel 6, and the rear wheel 6 is driven. Reference numeral 113 denotes a rotation speed sensor.

Since the mounting structure of the radiator 41 to the power unit 7 of the present embodiment is configured as described above, the following effects can be obtained. When the radiator 41 is mounted on the upper part of the power unit 7, the crankshaft 31 of the power unit 7 is disposed vertically in the front-rear direction of the vehicle body, and the axis of the cylinder 45 of the power unit 7 is disposed obliquely upward in the right direction of the vehicle body. The power transmission system is arranged to be inclined upward in the left direction of the vehicle body, and the radiator 41 is arranged so as to bridge between the V-shaped upper portions of the power unit 7 formed by these two inclinations.

As a result, the radiator 41 is arranged and mounted so as to extend over the V-shaped valley above the power unit 7 formed by the two inclinations which tend to be dead space. And the space required for mounting the radiator 41 can be reduced. Thereby, a storage space above the radiator 41 and below the seat 8 can be widened.

The upper part of the power unit 7
The radiator 41 can be mounted on the upper part of the power unit 7 above the axis of the cylinder 45 which is disposed obliquely upward in the right side of the vehicle when viewed in the front-rear direction of the vehicle body. This position can be set to the power unit 7
Becomes closer to the pivot portion which pivotally supports the power unit 7 by means of the hanger bolt, so that when the power unit 7 swings, the swing of the radiator 41 is reduced, and the upper portion of the radiator 41 (such as a cap provided in the cooling water supply unit 127) Becomes small, and it becomes unnecessary to fix the radiator 41 to the power unit 7 so strongly against the swing displacement. As a result, the mounting strength of the radiator 41 is reduced, and the mounting structure of the radiator 41 on the upper part of the power unit 7 is correspondingly simplified.

A cooling fan is provided at one end of the crankshaft 31.
The cooling fan 58 is attached, and the cooling fan 58 is covered with the shroud 40 so that the cooling air discharged from the cooling fan 58 is guided to the radiator 41. The cooling performance of the radiator 41 can be improved. Further, the shroud 40 can be downsized.

In the present embodiment, the radiator 41 is arranged so as to be bridged between the V-shaped upper portions of the power unit 7. However, depending on the structure of the water-cooled internal combustion engine 30 or the power unit 7, such a V-shaped radiator 41 is provided. There may be times when you can't expect it. In such a case, the bottom of the radiator 41 is recessed by an appropriate amount to form a space corresponding to the space between the V-shapes. Can be installed.

Further, since the mounting structure of the thermostat 82 of the present embodiment is configured as described above, the following effects can be obtained. Thermostat 82
Is provided in the cooling water circulation path so as to face the storage chamber 41a which forms a part of the inlet-side tank 122 of the radiator 41, and holds and covers the thermostat 82, which has been conventionally required. A dedicated conduit for the cover,
A hose for connecting the cover conduit to the radiator 41 is not required, so that the number of parts can be reduced and the cost can be reduced. In addition, since operations such as attachment and insertion of these conventionally required parts are not required, assemblability of the radiator 41 and the thermostat 82 can be improved.

Further, since the thermostat cover conduit and the hose are not required, the cooling water outlet of the internal combustion engine 30 and the cooling water inlet of the radiator 41 are connected and connected without connecting pipes. Since the radiator 41 and the radiator 41 are arranged at the closest positions, the thermostat 82 can quickly sense the effect of the temperature of the cooling water heated by the internal combustion engine 30 and appropriately control the cooling water circulation, The responsiveness of cooling the cooling water by the radiator 41 can be improved.

Since the thermostat 82 is less affected by the outside air temperature, it is necessary to cool the internal combustion engine 30 and accurately sense the temperature of the increased cooling water to appropriately control the cooling water circulation. Therefore, the stability of cooling of the cooling water by the radiator 41 can be improved.

Further, the thermostat 82 is
Projecting cylindrical portion 43a of the cylinder head 43 forming the cooling water outlet
And between the recessed cylindrical portion 130 of the storage chamber 41a forming the cooling water inlet of the radiator 41,
By very simple means, the thermostat 82 can be fixed in the circulation path of the cooling water, and the thermostat 82 can be provided so as to face the tank (the accommodation chamber 41a) of the radiator 41.

In the present embodiment, the projecting cylindrical portion 43a of the cylinder head 43 serves as a cooling water outlet of the internal combustion engine 30, and a housing chamber 41a formed integrally with the side of the inlet-side tank 122 of the radiator 41 has a radiator 41. However, the present invention is not limited to this. The direction of circulation of the cooling water is reversed, and the accommodating chamber 41a is used as the cooling water outlet of the radiator 41.
The part a may be a cooling water inlet of the internal combustion engine 30, and even in this case, the thermostat 82 can quickly detect the effect of the temperature of the cooling water cooled by the radiator 41 and appropriately control the cooling water circulation. Therefore, the responsiveness of cooling the cooling water by the radiator 41 can be improved. Further, since the thermostat 82 is less affected by the outside air temperature, the stability of cooling the cooling water by the radiator 41 can be improved. In this case, it is desirable that the direction of the thermostat 82 be reversed so that the wax portion 131 of the thermostat 82 is disposed on the accommodation room 41a side.

Further, the connection point between the cooling water outlet of the internal combustion engine 30 and the cooling water inlet of the radiator 41 without a hose can be moved to the cylinder 45 side. In this case, a protruding cylindrical portion (corresponding to the protruding cylindrical portion 43a of the cylinder head 43) is formed in the cylinder 45 so as to communicate with the cooling water jacket 84, and the dimensions of the radiator 41 are appropriately reduced. Is fitted to the recessed cylindrical portion 130 of the storage chamber 41a of the radiator 41. Then, the thermostat 82 is arranged in the fitting portion between the projecting tube portion and the concave tube portion 130. Further, the projecting cylindrical portion 43a of the cylinder head 43 is used as a cooling water inlet, and this is communicated with the discharge portion of the cooling water pump 79. Even in this case, the same effect as described above can be obtained. It should be noted that, even with such a pipe connection configuration between the internal combustion engine 30, the radiator 41, and the cooling water pump 79, the cooling water can be used with the circulation direction reversed.

In this embodiment, the water-cooled internal combustion engine 30
Is integrated with the power transmission device 90, and the power unit 7
, But is not limited to this.
Even a water-cooled internal combustion engine that is not unitized with the power transmission device 90 may be a single-cylinder or multiple-cylinder water-cooled internal combustion engine that is arranged so that a radiator is mounted on the top thereof. For institutions,
The mounting structure of the thermostat 82 of the present embodiment can be suitably implemented.

[Brief description of the drawings]

FIG. 1 is a left side view of a motorcycle equipped with a water-cooled internal combustion engine to which a thermostat mounting structure according to an embodiment of the invention described in claims 1 and 2 of the present application is applied.

FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1, and is a schematic cross-sectional view of a power unit including a water-cooled internal combustion engine cut along a plane orthogonal to a crankshaft and including a cylinder axis.

FIG. 3 is a sectional view taken along line III-III of FIG. 2;

FIG. 4 is a cross-sectional view taken along line IV-IV of FIG. 2, showing a radiator portion in a side view.

FIG. 5 is a sectional view taken along line VV of FIG. 2;

FIG. 6 is an enlarged view of a main part of FIG. 2;

FIG. 7 is a plan view of a radiator.

FIG. 8 is a front view of the shroud.

[Explanation of symbols]

1 ... motorcycle, 2 ... bolt, 3 ... front frame,
4: Rear frame, 5: Front wheel, 6: Rear wheel, 7: Power unit, 8: Seat, 9: Front fender, 10: Front cover, 11: Floor step, 12: Frame body cover, 13: Rear fender, 14: Side cover , 15… storage box, 16… swing arm, 17… shock absorber, 18…
King pin, 19 ... axle holder, 19a ... arm, 20 ... axle, 21 ... head pipe, 22 ... handle post, 23 ... steering arm, 24 ... link, 25 ... bracket, 26 ... hanger hole, 27 ... shock absorber, 30 ... Internal combustion engine, 31 ... Crankshaft, 31a ... Balance weight, 32 ... Air cleaner, 33 ...
Air inlet pipe, 34 ... throttle body, 35 ... intake pipe, 36 ...
Fuel injection valve, 37 ... Fuel tank, 38 ... Exhaust pipe, 39 ... Exhaust muffler, 40 ... Shroud (fan cover), 40a ... Air intake, 40b ... Slender air guide, 41 ... Radiator, 41a ... Housing chamber, 42 ... Crankcase, 42u, 42l ... Upper and lower crankcase, 43 ... Cylinder head, 43a ... Projecting cylinder, 44 ... Cylinder head cover, 45 ... Cylinder, 46 ... Pipe bush,
46a ... cylindrical part, 46b ... elastic pipe, 46c ... insertion pipe, 47 ... piston, 48 ... connecting rod, 49, 50 ... main bearing, 51 ... spark plug,
52: Piston type supercharger, 52a: Supercharged cylinder, 52b: Supercharged piston, 52c: Supercharged crankshaft, 53: Camshaft, 54,
55 ... bearing, 56 ... alternator, 56a ... rotor, 57 ... nut, 58 ... cooling fan, 59 ... bolt, 60 ... first drive gear,
61 ... second drive gear, 62 ... oil pump, 62a ... oil pump drive shaft, 62b ... rotor, 63 ... suction passage, 64 ... idler shaft, 64a ... large cylindrical part, 64b ... small cylindrical part, 65 ... large gear,
66… Small gear, 67… Cam gear, 68… Intake valve, 69… Supercharging valve,
70 ... first rocker arm, 71 ... second rocker arm, 72 ... rod, 73 ... first rocker arm, 74 ... second rocker arm
75… Rod, 76… Rotation position sensor, 77, 78… Bearing, 79…
Cooling water pump, 79a ... housing, 79b ... cover, 79c
... Rotary shaft, 79d ... Impeller, 79e, 79f ... Permanent magnet, 80
… Pipe (water pipe), 81… discharge hole, 82… thermostat,
82a: annular flange, 82b: valve body, 83: weight,
84 ... cooling water jacket, 90 ... power transmission device, 91 ... planetary gear type transmission, 92 ... transmission case, 93 ... center shaft, 94 ... input gear, 95 ... starting clutch, 95a ... clutch inner, 95
b… Clutch outer, 95c… Centrifugal weight, 96-98… 2
Speed-to-fourth-speed transmission clutch, 99: output shaft, 100: detent member, 101: flanged boss, 102: starting drive gear, 103: large gear, 104: small gear, 105: starting driven gear, 106: One-way clutch, 107 ... output gear, 110 ...
Final reduction gear, 111… drive shaft, 112… gear, 113…
Rotational speed sensor, 114 ... gear case, 120 ... stay (mounting plate), 121 ... bolt, 122 ... inlet side tank, 123 ... outlet side tank, 124 ... finned heat transfer tube, 125 ... cooling water outlet, 126 ... wind guide wall , 127 ... cooling water supply section, 128 ... wall,
130 ... recessed cylindrical part, 130a ... annular step part, 131 ... wax part,
A: split surface, B: mounting surface, C0: center of vehicle body, C1 to C
5 ... axis, D ... wind guideway.

Claims (2)

[Claims] 1. A mounting structure of a thermostat in a water-cooled internal combustion engine in which a radiator is mounted on an upper portion of an internal combustion engine, wherein the thermostat is located in a cooling water circulation path,
A mounting structure for a thermostat in a water-cooled internal combustion engine, wherein the mounting structure is provided so as to face a tank of the radiator. 2. A thermostat for a water-cooled internal combustion engine according to claim 1, wherein said thermostat is mounted between said cooling water inlet and outlet of said internal combustion engine and said cooling water inlet and outlet of said radiator. Mounting structure.