JP2002021562A - Water-cooled engine cooling system - Google Patents

Abstract

(57) Abstract: In a cooling device for an engine, a thermostat that switches a flow path of cooling water according to a temperature of the cooling water is provided in a middle of an ascending passage through which cooling water can flow. And eliminating the need for parts to avoid an increase in the number of parts, while improving air bleeding from the ascending passage. A wax case (87) having an upper end facing a water chamber (90) formed in a housing (86A) through a bypass passage (81) enables a sliding operation according to expansion and contraction of the wax (89). When the wax 89 contracts, the water chamber 90 is fitted so as to communicate with the upper passage portion 78, and is fitted to the housing 86A.
Inlet hole 10 communicating with lower passage portion 77 of ascending passage 76
2 and an outlet hole 103 communicating with the upper passage portion 78 of the ascending passage 76 is provided so as to be shut off by the wax case 87 when the wax 89 contracts.
The water chamber 90 is communicated with the water chamber 90 via an air vent passage 105.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling device for a water-cooled engine, and more particularly, to a cooling water flow path according to the temperature of the cooling water in a rising passage through which the cooling water can flow upward. The present invention relates to an engine cooling device provided with a switchable thermostat.

[0002]

2. Description of the Related Art Conventionally, such a cooling device is already known, for example, from Japanese Utility Model Application Laid-Open No. 4-75129, in which a cooling device is provided below a housing provided in a thermostat.
An inlet hole communicating with the lower passage portion of the rising passage is provided, an outlet hole communicating with the upper passage portion of the rising passage is provided at an intermediate portion of the housing, and a bypass hole communicating with the bypass passage is provided at an upper portion of the housing. The wax case is slidable between a lower position where the bypass hole communicates with the outlet hole when the wax contracts and an upper position where the inlet hole communicates with the outlet hole when the wax expands. It is stored.

[0003]

When the cooling water is injected into the cooling device, it is necessary to release air from the main circulation circuit and the sub circulation circuit. In the intermediate thermostat, there is a height difference between the inlet hole and the outlet hole, and the passage of the cooling water in the thermostat has a crank shape. For this reason, for example, when the cooling device has to be configured vertically compactly for mounting on a motorcycle, the inclination angle of the ascending passage must be reduced, so that it takes time to release air. In order to avoid this, it is necessary to install an air release bolt or the like in the ascending passage.

The present invention has been made in view of the above circumstances, and has a configuration in which a thermostat is provided in the middle of an ascending passage for raising cooling water upward. It is an object of the present invention to provide a cooling device for a water-cooled engine, in which an increase in the number of points is avoided and air bleeding from a rising passage is improved.

[0005]

In order to achieve the above object, the invention according to claim 1 provides a water jacket, a radiator, and a radiator of an engine body, with a rising passage through which cooling water can flow upward as a partial passage. A main circulation circuit that sequentially connects a water pump and the water jacket, a bypass passage that bypasses the radiator, and a sub circulation circuit that is part of the main circulation circuit; A thermostat provided in the middle of the ascending passage so as to switch a state in which the cooling water is circulated and circulated and a state in which the bypass passage is shut off and the cooling water is circulated and circulated in the main circulation circuit in accordance with the temperature of the cooling water; Wherein the thermostat extends up and down across the middle of the ascending passage. A housing having a moving hole, a wax case which is slidably fitted in the sliding hole and has an upper end facing a water chamber formed in the housing through the bypass passage; Accompanying expansion
A wax built in the wax case so that the wax case can be slid in accordance with shrinkage, and the wax case communicates the water chamber with the upper side passage portion when the wax shrinks. The housing is provided with an inlet hole communicating with the lower passage portion of the rising passage and an outlet hole communicating with the upper passage portion of the rising passage. Sometimes provided at the position blocked by the wax case so as to open to the inner surface of the slide hole, and the inlet hole and the water chamber are communicated via an air vent passage for guiding air in the cooling water. It is characterized by.

According to the first aspect of the present invention, the thermostat housing has an inlet hole and an outlet hole opened on the inner surface of the sliding hole for sliding the wax case. The inlet hole communicates with the lower passage portion of the ascending passage, and the outlet hole communicates with the upper passage portion of the ascending passage. Even if the cooling device must be compactly configured in the vertical direction, the inclination angle of the ascending passage does not need to be reduced as in the related art, and air in the ascending passage is not required. Can be quickly distributed. Moreover, since the inlet hole communicates with the water chamber formed in the upper part of the housing through the bypass passage through the air vent passage, the air in the lower passage portion of the rising passage is quickly discharged to the bypass passage side. As a result, the air bleeding property can be improved.

[0007] The invention according to claim 2 provides the above-described claim 1.
In addition to the configuration of the invention described above, the thermostat is housed in a storage case in which the housing is fitted, and the air vent passage is formed by a groove provided on an inner surface of the storage case and an outer surface of the housing. Characterized in that
According to this configuration, the air bleeding passage is formed around the thermostat, and the air bleeding property can be further improved.

According to a third aspect of the present invention, in addition to the configuration of the first or second aspect, the radiator, the water pump, and the thermostat include:
The cooling device is attached to the engine body at substantially the same height, and according to such a configuration, the cooling device can be compactly assembled in the up-down direction and assembled to the engine body.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on embodiments of the present invention shown in the accompanying drawings.

1 to 9 show a first embodiment of the present invention. FIG. 1 is an overall side view of a scooter type motorcycle.
2 is an enlarged sectional view taken along line 2-2 of FIG. 1, FIG. 3 is an enlarged view of a main part of FIG. 2, FIG. 4 is a view taken along line 4-4 of FIG. 2, and FIG. FIG. 6 is a view as seen from the direction of the arrows, FIG.
7 is a longitudinal sectional view of the thermostat in a low temperature state, FIG. 8 is a longitudinal sectional view of the thermostat in a high temperature state, and FIG. 9 is a sectional view taken along a line 9-9 in FIG.

First, in FIG. 1, a body frame F of a scooter type motorcycle V having a front wheel Wf steered by a steering wheel 11 and a rear wheel Wr driven by a swing type power unit P is a front frame. 1
2, 3 for center frame 13 and rear frame 14
Divided. The front frame 12 includes the head pipe 1
2a, a down tube 12b and a step floor support portion 12c are integrally formed of an aluminum alloy casting. A center frame 13 on which the power unit P is supported so as to be able to swing up and down via a pivot 15 is made of an aluminum alloy casting, and is connected to the rear end of the front frame 12. A rear frame 14 extending rearward and upward from the power unit P is formed of an annular pipe material, and a fuel tank 16 is supported on an upper surface thereof. Center frame 1
Helmet case 17 is supported on the upper surface of 3,
The helmet case 17 and the fuel tank 16 are openably and closably covered by a cover 19 integrally having the seat 18.

The power unit P is a water-cooled, single-cylinder, four-stroke engine E having a cylinder disposed toward the front of the vehicle.
And a belt-type continuously variable transmission T extending rearward from the left side of the engine E to the rear of the vehicle body. The rear upper surface of the belt-type continuously variable transmission T is located behind the center frame 13 via the rear cushion 20. Joined to the end. An air cleaner 21 is supported on an upper surface of the belt-type continuously variable transmission T, a muffler 22 is supported on a right side surface of the belt-type continuously variable transmission T, and a stand-up and fallable main stand 2 is provided on a lower surface of the engine E.
3 is supported.

2 to 4, the engine body 24 of the engine E has first and second engine blocks 27 and 28 divided by a split surface 26 extending vertically along a crankshaft 25. The first engine block 27 forms a cylinder block 27a and a crankcase half 27b, and the second engine block 28
Constitutes the other half of the crankcase. The front end of the first engine block 27 is connected to a cylinder head 29 that constitutes the engine body 24 together with the first and second engine blocks 27 and 28, and the head cover 30 is connected to the front end of the cylinder head 29. First and second
A generator cover 31 is connected to right side surfaces of the engine blocks 27 and 28.

The belt-type continuously variable transmission T includes a right casing 32 and a left casing 33 which are connected to each other. The front right side of the right casing 32 is formed by the first and second engine blocks 27 and 28. Joined to left side. A reduction gear casing 34 is connected to a rear right side surface of the right casing 33.

A piston 36 slidably fitted inside a cylinder 35 provided in the first engine block 27 is connected to a crankshaft 25 via a connecting rod 37.
Connected to. The camshaft 3 is attached to the cylinder head 29.
8 is rotatably supported, and an intake valve and an exhaust valve (not shown) provided on the cylinder head 29 are opened and closed by the camshaft 38. A timing chain 40 is housed in a chain passage 39 provided in the first engine block 27, and the timing chain 40 includes a driving sprocket 41 provided on the crankshaft 25 and a driven sprocket 42 provided on the camshaft 38. Wrapped around. Thus, the camshaft 38 makes one rotation for every two rotations of the crankshaft 25.

A drive pulley 43 is provided at the left end of the crankshaft 25 projecting into the right casing 32 and the left casing 33. The drive pulley 43 includes a fixed pulley half 44 fixed to the crankshaft 25.
And a movable pulley half 45 that can approach and separate from the fixed pulley half 44. The movable pulley half 45 moves radially outward in response to an increase in the number of revolutions of the crankshaft 25. The moving centrifugal weight 46 is urged in a direction approaching the fixed pulley half 44.

A driven pulley 48 provided on an output shaft 47 supported between the rear portion of the right casing 32 and the reduction gear casing 34 is fixed to a fixed pulley half 49 supported on the output shaft 47 so as to be relatively rotatable. And a movable pulley half 50 that can approach and separate from the side pulley half 49. The movable pulley half 50 is urged toward the fixed pulley half 49 by a spring 51. A centrifugal clutch 52 is provided between the fixed pulley half 49 and the output shaft 47, and is brought into a power transmission state as the engine speed exceeds the set speed. Then, an endless V-belt 53 is wound between the driving pulley 43 and the driven pulley 48.

An intermediate shaft 54 and an axle 55 parallel to the output shaft 47 are supported between the right casing 32 and the reduction gear casing 34. A reduction gear train 56 is provided between the output shaft 47, the intermediate shaft 54 and the axle 55. Provided. And an axle 5 that penetrates through the reduction gear casing 34 and protrudes rightward.
A rear wheel Wr, which is a driving wheel, is provided at the right end of 5.

The rotational power of the crankshaft 25 is transmitted to the driving pulley 43, and the driving pulley 43
The power is transmitted to the rear wheel Wr via the belt 53, the driven pulley 48, the centrifugal clutch 52, and the reduction gear train 56.

An alternator 57 provided on the right side of the crankshaft 25 is covered by a generator cover 31, and a radiator 58 is provided on the right side of the generator cover 31. In order to supply cooling air to the radiator 58,
Cooling fan 5 fixed to right end of crankshaft 25
9 is arranged between the alternator 57 and the radiator 58. Thus, the heat radiation capacity of the radiator 58 is always larger than the heat value of the engine E.

The cooling fan 59 and the radiator 58
Synthetic resin cover 60 fastened to generator cover 31
The outside surface of the cover 60 is provided with a louver 61 for introducing air from outside.

A water jacket 62 is provided on the cylinder block 27a of the first engine block 27 and the cylinder head 34. A water pump 63 for supplying cooling water to a lower portion of the water jacket 62 on the cylinder block 27a side is provided. The height position is substantially the same as that of the radiator 58, and the camshaft 38 is connected to the right end.

A storage case 65 is connected to the right side surface of the cylinder head 34. A thermostat 64A is stored in the storage case 65, and the water pump 63 is provided in a space surrounded by the cylinder head 34 and the storage case 65. Is stored. That is, the radiator 58, the water pump 63, and the thermostat 64A are attached to the engine body 24 at substantially the same height.

Referring also to FIG. 5, the cylinder head 34 is connected to the upper portion of the water jacket 62 so as to communicate therewith.
The other end of the cooling water pipe 68 is connected to a filler neck 70 whose upper end opening can be opened and closed by a cap 71, and the filler neck 70 swings with the radiator 58. To the rear fender 66 which is attached to the power unit P and covers the rear wheel Wr from above. The filler neck 70 is connected to a water supply port 58a provided at the rear upper portion of the radiator 58 via a flexible water supply pipe 69 such as a rubber hose.

The filler neck 70 is provided with an overflow pipe 70a for overflowing the cooling water, and the overflow pipe 70a is connected to a reservoir tank (not shown). An outlet port 58b provided at a lower front part of the radiator 58 and the storage case 65 are connected by a cooling water pipe 72, and the cooling water pipe 72 is connected to a suction port of the water pump 63 through a thermostat 64A in the storage case 65. Is done. Further, the storage case 65 and the water jacket 62 in the first engine block 27 are
Connected by

That is, the water jacket 62,
The radiator 58 and the water pump 63 are connected to each other through a cooling water pipe 68, a filler neck 70, a water supply pipe 69, and cooling water pipes 72 and 73 to form a main circulation circuit 75.
In the main circulation circuit 75, the cooling water flows and circulates so that the cooling water discharged from the water pump 63 returns to the water pump 63 via the water jacket 62 and the radiator 58.

In FIG. 6, in the main circulation circuit 75, between the outlet port 58b at the front lower portion of the radiator 58 and the suction port of the water pump 63, the cooling water flows from the lower outlet port 58b to the upper suction port. Are connected to each other by a rising passage 76 through which the cooling water flows to the upper side. The rising passage 76 is formed by a cooling water pipe 72 and a lower passage provided in the storage case 65 and connected to the cooling water pipe 72. A portion 77 and an upper passage passage portion 78 provided in the storage case 65 and communicating with the suction port of the water pump 63, and the thermostat 64 </ b> A is interposed between the two passage portions 77 and 78 so as to be interposed between the storage case 65. Is stored inside.

At a position adjacent to the cooling water pipe 68, one end of a bypass pipe 79 bypassing the radiator 58 is connected to the cylinder head 34 so as to communicate with the upper part of the water jacket 62. The other end of the cover member 8 is fastened to the upper part of the storage case 65.
Connected to 0. The bypass pipe 79 can communicate with the upper side passage portion 78 that communicates with the suction port of the water pump 63 through the thermostat 64 </ b> A in the storage case 64. A sub-circulation circuit 82 is formed by the bypass passage 81 formed between the lid member 80 and the cylinder head 34 including the bypass pipe 74, and between the thermostat 64A and the water pump 63 and between the thermostat 64A and the water pump 63. .

The thermostat 64A shuts off the ascending passage 76 and opens the bypass passage 81 to allow the cooling water to flow and circulate through the sub-circulation circuit 82.
6 is opened and the bypass passage 81 is shut off to switch the state in which the cooling water flows and circulates through the main circulation circuit 75 in accordance with the temperature of the cooling water. The cooling water is provided between the side passage portions 78 to supply the cooling water to the main circulation circuit 75 and the sub-circulation circuit 8.
2 is switched according to the temperature of the cooling water.

Referring to FIGS. 7 and 8, the thermostat 64A is connected to the ascending passage 7 in the main circulation circuit 75.
6 has a bottomed cylindrical housing 86A having a bottomed sliding hole 85 extending vertically across the lower and upper passage portions 77 and 78 and having a closed lower end. Wax case 8 slidably fitted
7, a spring 88 contracted between the housing 86A and the wax case 87, and built in the wax case 87 to slide the wax case 87 in accordance with expansion and contraction due to a change in the temperature of the cooling water. Wax 89
And

The wax case 87 is connected to the bypass passage 81.
Are slidably fitted in the sliding holes 85 such that the upper ends thereof face the water chambers 90 formed in the housing 86A.

The housing 86A is fitted in a bottomed mounting hole 91 provided in the storage case 85, and the mounting hole 9
By closing the open end of the cover member 80 with the cover member 80, the cover member 80 is stored and fixed in the storage case 85 so as to be sandwiched between the closed end of the mounting hole 91 and the cover member 80.

At one end of the housing 86A, a bottomed cylindrical sealing member 92 made of an elastic material is mounted so as to cover one end of the housing 86A. One end of 86A is exposed as a tip reinforcing portion 84. The opened upper end of the housing 86A is in contact with the lid member 80, and a retaining ring 93 is mounted on the inner surface of the upper end side of the housing 80.

The wax case 87 includes a housing 86A.
And a cover 95 coupled to the case main body 94. The peripheral edge of the diaphragm 96 is sandwiched between the case main body 94 and the cover 95. . In addition, case subject 9
4, a cylindrical guide tube 97 slidably fitted in the seal member 92 is integrally connected.

A wax 89 is incorporated in the wax case 87 so as to be filled between the diaphragm 96 and the cover 95, and the diaphragm 96 is deformed in accordance with expansion and contraction of the wax 89 due to a temperature change.
On the other hand, in the guide cylinder 97, the diaphragm 96 is provided.
A rod-shaped piston 98, a disk-shaped plate 99, and a rubber piston 100 are slidably fitted in this order from the opposite side, and the wax case 87 deforms the diaphragm 96 between the rubber piston 100 and the diaphragm 96. A medium 101 for transmitting to the rubber piston 100 is filled.

The wax case 87 and the retaining ring 93
A spring 88 for urging the wax case 87 toward the seal member 92 is provided between the wax cases 87.
When the temperature of the cooling water is low and the wax 89 is in a contracted state, as shown in FIG. When the temperature of the cooling water rises and the wax 89 expands, the diaphragm 96 is deformed so as to bend downward in FIG. 8, and the piston 98 is pushed out of the guide cylinder 97, so that the wax case 87 88
As shown in FIG. 8, the slider slides upward on the side away from the seal member 92, that is, upward.

The housing 86A has an inlet hole 102 communicating with the lower passage portion 77 of the rising passage 76 of the main circulation circuit 75, and an upper passage portion 78 of the rising passage 76.
An outlet hole 103 is provided so as to open on the inner surface of the sliding hole 85 on one diameter line of the sliding hole 85, and a bypass which can communicate the water chamber 90 with the upper side passage portion 78. A hole 104 is provided adjacent to and above the outlet hole 103.

The inlet hole 102 and the outlet hole 103 are
When the wax 89 contracts, the wax 89 is shut off by the wax case 87 as shown in FIG.
8 is provided in the housing 86A so as to open to the inner surface of the sliding hole 85 at a position where the wax case 87 slides as shown in FIG.
In addition, the bypass hole 104 allows the water chamber 90 to communicate with the upper passage portion 78 when the wax 89 contracts,
When the opening between the inlet hole 102 and the outlet hole 103 is opened in accordance with the sliding of the wax case 87 accompanying the expansion of the wax 89, the housing 86A is provided at a position where the wax case 87 is shut off as shown in FIG.

The water chamber 90 and the inlet hole 102 communicate with each other via an air vent passage 105 for guiding air in the cooling water. The air vent passage 105 is formed in the inner surface of the mounting hole 91 in the storage case 65. Groove 10 provided
6 and the outer surface of the housing 87 provided in the thermostat 64A.

Next, the operation of the first embodiment will be described. In the housing 86A of the thermostat 64A, an inlet hole 102 and an outlet hole 103 arranged on one diameter line of a sliding hole 85 for sliding the wax case 87 are provided. Since the inlet hole 102 communicates with the lower passage portion 77 of the ascending passage 76, which is the position of the passage of the main circulation circuit 75, and the outlet hole 103 communicates with the upper passage portion 78 of the ascending passage 76, the thermostat 64A Can be prevented from causing a height difference in the ascending passage 76 at the portion sandwiching.
Therefore, even in the case where the cooling device must be compactly configured in the vertical direction, it is not necessary to reduce the inclination angle of the ascending passage 76 as in the related art, so that the air can flow through the ascending passage 76 quickly. The inclination angle of the rising passage 76 can be set relatively large.

Further, the water chamber 90 which forms a part of the bypass passage 81 and is formed in the upper part in the housing 86A.
In addition, since the inlet hole 102 communicates with the air through the air vent passage 105, the air in the lower passage portion 77 of the rising passage 76 can be quickly discharged to the bypass passage 81 side.

As a result, despite the fact that the thermostat 64A is provided in the middle of the ascending passage 76 through which the cooling water flows upward, air vent bolts and the like are not required, and an increase in the number of parts is avoided, while the increase in the number of parts is prevented. The air bleeding property can be improved.

The housing 8 of the thermostat 64A
6A is fitted into the storage case 65, the groove 106 provided on the inner surface of the storage case 65, and the housing 86A.
And the outer surface of the air vent passage 105 is formed,
The air bleed passage 105 is formed so as to bypass the thermostat 64A, and the air bleeding property can be further improved.

Further, the radiator 58 and the water pump 6
3 and the thermostat 64A are attached to the engine main body 24 at substantially the same height, so that the cooling device can be compactly assembled in the vertical direction and assembled to the engine main body 24. As in this embodiment, the continuously variable transmission The cooling unit is compactly assembled in the up-down direction on the engine body 24 of the engine E, which constitutes a power unit P together with the T and is swingably supported on the body frame F, so that the required swing space is reduced. The size can be reduced, and mounting on the vehicle body frame F can be made advantageous.

FIGS. 10 to 12 show a second embodiment of the present invention. FIG. 10 is a side view corresponding to FIG. 6 of the first embodiment, and FIG. 11 is a longitudinal sectional view of the thermostat in a low temperature state. FIG. 12 is a vertical sectional view of the thermostat in a high temperature state, and portions corresponding to the first embodiment are denoted by the same reference numerals.

The thermostat 64B has a main circulation circuit 75.
Is provided between the lower passage portion 77 and the upper passage portion 78 of the ascending passage 76 which is a partial passage of the cooling water.
Whether to circulate is switched according to the temperature of the cooling water.

The housing 86B of the thermostat 64A
Are formed integrally with the cylinder head 29 of the engine body 24 or fastened to the cylinder head 29. A sliding hole 85 that closes the lower end and extends vertically is provided in the housing 86B. Is closed by a lid member 80 '.

A wax case 87 is slidably fitted in the sliding hole 85, and the lid member 80 and the wax case 87 are fitted.
A spring 88 is contracted between them.

The wax case 87 is connected to the bypass passage 81.
And is slidably fitted in the sliding hole 85 so that the upper end faces a water chamber 90 formed in the housing 86B through the housing 86B. Sliding operation is possible.

The wax case 87 includes a housing 86B
And a cover 95 connected to the case main body 94. The peripheral portion of the diaphragm 96 is sandwiched between the case main body 94 and the cover 95. The wax 89 is filled between the diaphragm 96 and the cover 95. A cylindrical guide cylinder 97 is integrally connected to the case body 94, and a piston 98, a plate 99, and a rubber piston 100 are slidably fitted in the guide cylinder 97, and a rubber piston 100 is provided. And diaphragm 96
The medium 101 is filled in the wax case 87 therebetween.

The housing 86B has an inlet hole 102 'communicating with the lower passage portion 77 of the rising passage 76 of the main circulation circuit 75, and the upper passage portion 7 of the rising passage 76.
An outlet hole 103 ′ communicating with the slide hole 8 is provided on one inner diameter of the slide hole 85 on one diameter line of the slide hole 85.

The entrance hole 102 ′ is formed in a tapered shape having a smaller diameter as it approaches the inner surface of the slide hole 85. The outlet hole 103 'is formed in the housing 86B such that a portion that cannot be blocked by the wax case 87 when the wax 89 contracts remains in the upper portion.
The upper portion of 3 'functions as a bypass hole 104' for connecting the water chamber 90 to the upper passage portion 78 when the temperature of the cooling water is low.

Moreover, the inlet hole 102 'and the water chamber 90
The space is communicated via an air vent passage 107 that guides air in the cooling water.
When the wax 89 is contracted, the inlet passage 102 ′ communicates with the water chamber 90 so that the tapered inlet hole 102 ′ is formed.
It is formed in a groove shape on the upper part of.

According to the second embodiment, the same effect as that of the first embodiment can be obtained. In particular, since the wax case 87 is in direct contact with the passage of the cooling system and the engine body 24, the temperature of the cooling water changes. This prevents the occurrence of hunting and overshoot phenomena, thereby further improving the cooling performance.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various design changes can be made without departing from the present invention described in the appended claims. It is possible.

[0056]

As described above, according to the first aspect of the present invention, even when the cooling device has to be compactly formed in the vertical direction, the inclination angle of the ascending passage is made relatively large so that the air is cooled. Can be quickly circulated, and the air in the lower passage portion of the ascending passage is quickly discharged to the bypass passage side, so that the air bleeding property can be improved while avoiding an increase in the number of parts.

According to the second aspect of the present invention, the air bleeding property can be further improved by forming the air bleeding passage bypassing the thermostat.

According to the third aspect of the present invention, the cooling device can be compactly assembled in the vertical direction and assembled to the engine body.

[Brief description of the drawings]

FIG. 1 is an overall side view of a scooter type motorcycle.

FIG. 2 is an enlarged sectional view taken along line 2-2 of FIG.

FIG. 3 is an enlarged view of a main part of FIG. 2;

FIG. 4 is a view taken in the direction of arrows 4-4 in FIG. 2;

FIG. 5 is a view of the power unit as viewed from the direction of arrows 5-5 in FIG. 1;

FIG. 6 is an enlarged sectional view taken along line 6-6 of FIG. 2;

FIG. 7 is a longitudinal sectional view of the thermostat in a low temperature state.

FIG. 8 is a longitudinal sectional view of the thermostat in a high temperature state.

FIG. 9 is a sectional view taken along line 9-9 of FIG. 7;

FIG. 10 is a side view corresponding to FIG. 6 of the second embodiment.

FIG. 11 is a longitudinal sectional view of the thermostat in a low temperature state.

FIG. 12 is a longitudinal sectional view of the thermostat in a high temperature state.

[Explanation of symbols]

 24 ... Engine body 58 ... Radiator 62 ... Water jacket 63 ... Water pump 64A, 64B ... Thermostat 75 ... Main circulation circuit 76 ... Up passage 77 ... Down passage Part 78: Upper passage part 81: Bypass passage 82: Sub-circulation circuit 85: Sliding hole 86A, 86: Housing 87: Wax case 89: Wax 90 ...・ Water chambers 102, 102 ′ ・ ・ ・ Inlet holes 103, 103 ′ ・ ・ ・ Outlet holes 105, 107 ・ ・ ・ Air vent holes 106 ・ ・ ・ Grooves E ・ ・ ・ Engine

Claims (3)

[Claims] 1. A water jacket (62) of an engine body (24), a radiator (58), and a rising passage (76) through which cooling water can flow upward as a partial passage.
The main circulation circuit (75) sequentially connects the water pump (63) and the water jacket (62), a bypass passage (81) bypassing the radiator (58), and a part of the main circulation circuit (75). A state in which cooling water flows and circulates in the auxiliary circulation circuit (82) by shutting off the ascending passage (76); and a main circulation circuit by shutting off the bypass passage (81). A cooling system for a water-cooled engine including a thermostat (64A, 64B) provided in the middle of the ascending passage (76) so as to switch the state of circulation and circulation of the cooling water in accordance with the temperature of the cooling water. The thermostat (64A, 64B) has a housing (86A) having a sliding hole (85) extending vertically across the middle of the ascending passage (76). Wherein the 86B), along with slidably fitted in said sliding hole (85) the bypass passage (8
Wax case (8) whose upper end faces water chamber (90) formed in housing (86A, 86B) through (1).
7) and a wax (89) incorporated in the wax case (87) so that the wax case (87) can be slid in response to expansion and contraction caused by a change in the temperature of the cooling water. , The wax case (87)
When the wax (89) contracts, the water chamber (90)
Is connected to the sliding hole (85) so as to communicate with the upper passage portion (78), and the housing (86A, 86B) has a lower passage portion of the rising passage (76). Entrance holes (102, 10) leading to (77)
2 ') and outlet holes (103, 103') leading to the upper side passage portion (78) of the ascending passage (76),
At the position where the wax (89) is contracted by the wax case (87) when it shrinks, the wax (89) is provided so as to open to the inner surface of the sliding hole (85), and the entrance hole (102,
102 ') and the water chamber (90) are communicated via air vent passages (105, 107) for guiding air in the cooling water. 2. The storage case (65) in which the thermostat (64A) is fitted with the housing (86A).
The air vent passage (105) is formed by a groove (106) housed inside the housing case (65) and provided on an inner surface of the housing case (65) and an outer surface of the housing (86A). Water-cooled engine cooling system. 3. The radiator (58), the water pump (63) and the thermostat (64A, 6).
The cooling device for a water-cooled engine according to claim 1 or 2, wherein 4B) is attached to the engine body (24) at substantially the same height.