JP4820860B2 - Radiator structure of unit swing type internal combustion engine - Google Patents

Description

  The present invention relates to a radiator provided in a unit swing type internal combustion engine mounted on a small vehicle.

  In the case of a unit swing type internal combustion engine, a pivot support portion protruding from a crankcase is connected to a vehicle body frame via a support link member, so that the unit swing type internal combustion engine is swingably supported.

  There is an example in which a radiator is provided on the side of the crankcase of such a unit swing type internal combustion engine, but if the radiator covers the pivot support part from the side, it becomes difficult to assemble the pivot support part. There is an example in which a pivot support part is protruded largely forward from the lower part of the crankcase and is connected to a vehicle body frame where a radiator is avoided (see, for example, Patent Document 1).

JP 2007-126988 A

The unit swing type internal combustion engine disclosed in Patent Document 1 is mounted on a scooter type vehicle, and a cylinder tilted forward from the crankcase to a level is projected from the crankcase and protrudes forward from the lower part of the crankcase. The pivot support portion is located below the cylinder and is connected to the lower portion of the vehicle body main frame via a link member.
Therefore, the radiator disposed on the side of the crankcase does not cover the pivot support portion.

In this way, in the case of having the pivot support part at the lower part of the crankcase, the connecting part connected to the vehicle body main frame via the link member is formed below the forwardly inclined cylinder, so that there is a space below the crankcase and the cylinder. And the center of gravity of the internal combustion engine is increased, making it difficult to lower the center of gravity.
Therefore, if the pivot support part is provided at the upper part of the crankcase, there is a high possibility that the radiator disposed on the side of the crankcase, in particular, the upper tank part covers the side of the pivot support part. Is troublesome.

  The present invention has been made in view of this point, and the object of the present invention is to reduce the center of gravity of the internal combustion engine by preventing the radiator from covering the side of the pivot support portion provided at the upper part of the crankcase. And a radiator structure of a unit swing type internal combustion engine that simplifies the assembly work of the pivot support portion.

In order to achieve the above object, according to the present invention, a unit swing type internal combustion engine is provided with a pivot support portion (18) projecting from an upper portion of a crankcase (31) via a support link member (16). It is connected to the vehicle body frame (4) and is supported so as to be swingable.The upper radiator tank portion (52) is arranged vertically on both sides of the crankcase (31) with a rectangular heat dissipating core portion (51) in side view. In a radiator structure of a unit swing type internal combustion engine in which a radiator (50) including a lower radiator tank portion (53) is disposed, the radiator (50) is inclined forward and the heat radiating core portion (51 the upper radiator tank through which cooling water is supplied to the) (52) also inclined forward, the upper radiator tank (52), the low-side tank portion (52L that is formed on the portion that becomes the lower side when viewed from the side ) And the upper wall ( 52L) of the low side tank portion (52L) formed on the high side portion f) constitutes a high-side tank portion (52U) that bulges upward from and into which cooling water is introduced, and the upper wall (52r) of the high-side tank portion (52U) has a top wall (52uc) and the top wall A front side wall (52uf) formed to be inclined forward from the wall (52uc) and continued to the upper wall (52f) of the low side tank portion (52L), and formed to be inclined rearward from the top wall (55uc). The pivot support portion (18) is positioned in a side view in a space (52S) in front of the high-side tank portion (52U) above the low-side tank portion (52L). The upper radiator tank portion (52) is arranged in the manner described above , and the cooling water introduction connecting pipe (52J) is forwarded from the upper side of the front side wall (52uf) of the high side tank portion (52U) to the lower side. Protruding substantially parallel to the upper wall (52f) of the tank part (52L), the pivot support part (18) is located between the low tank part (52L) and the introduction connecting pipe (52J) in a side view. The tank cover (55) Covering the upper radiator tank part (52) from the side along its outline while avoiding the support part (18) in side view, and the tank cover (55) along the introduction connecting pipe (52J) The radiator structure of the unit swing type internal combustion engine is provided with a connecting pipe cover portion (55j) that covers at least the side of the extended connecting pipe (52J).

According to a second aspect of the present invention, in the radiator structure of the unit swing type internal combustion engine according to the first aspect , the upper wall (52f) of the low-side tank portion (52L) extends forward of the heat radiating core portion (51). It is characterized by being inclined parallel to the inclination .

  According to a third aspect of the present invention, in the radiator structure of the unit swing type internal combustion engine according to the first or second aspect, a pinion step (43) is disposed on a side of the introduction connecting pipe (52J). Features.

  According to the radiator structure of the unit swing type internal combustion engine according to claim 1, in the space above the low side tank portion of the upper radiator tank portion inclined forward and backward and in front of the high side tank portion bulging upward, The upper radiator tank is arranged so that the pivot support projecting from the top of the crankcase is located in side view, and the tank cover avoids the pivot support in side view and the upper radiator tank is defined as its contour. Therefore, the side of the pivot support portion is not covered with the radiator and the tank cover and is opened, thereby facilitating the assembly work of the pivot support portion.

The cooling water bulging upward and introduced into the high-capacity high-side tank portion flows into the low-capacity low-side tank portion and is distributed to the heat-radiating core portion without deviation from the inclined lower side of the upper radiator tank portion. Therefore, it is possible to efficiently utilize the entire heat radiating core portion and cool it efficiently.
The pivot support part projects from the upper part of the crankcase and the connection part connected to the vehicle body frame is located above the crankcase, so that the center of gravity of the internal combustion engine can be easily lowered.

The cooling water introduction and connection pipe protrudes from the upper part of the side wall of the lower tank part side of the upper wall (52r) of the higher side tank part that protrudes substantially parallel to the upper side of the lower side tank part. the top wall (52r) vigorously introduced cooling water from the inlet connecting pipe of the side wall of the lower side tank portion side hits the other side wall inner surface of the high-side tank portion of the bulged top wall (52r), the direction Since it is guided to the low-side tank part instead, the cooling water can be sufficiently supplied to the low-side tank part having a small capacity.
Since the pivot support part is located between the low side tank part and the introduction connecting pipe in a side view, the high side tank part projecting the introduction connecting pipe above the pivot support part greatly bulges upward to increase the volume. This increases the capacity of the upper radiator tank section.

In the tank cover, the connecting pipe cover part (55j) extending along the introduction connecting pipe covers at least the side of the introducing connection pipe, so that the connecting pipe cover part (55j) integral with the tank cover has a small diameter. The introduction connecting pipe can be protected.

According to the radiator structure of the unit swing type internal combustion engine according to claim 2, the upper wall (52f) of the low side tank portion (52L) is inclined in parallel with the forward inclination of the heat radiating core portion (51). because there, while ensuring the tank capacity, by suppressing the variation due to fluctuation of the cooling water of the low-side tank portion, the cooling water can be stably supplied to the heat core portion.

  According to the radiator structure of the unit swing type internal combustion engine according to the third aspect, since the pinion step is disposed on the side of the introduction connecting pipe, the pinion step can reliably protect the introduction connecting pipe.

Hereinafter, an embodiment according to the present invention will be described with reference to FIGS.
FIG. 1 shows a scooter type motorcycle 1 equipped with a unit swing type internal combustion engine according to the present embodiment.
In the present embodiment, the front, rear, left and right are determined based on the state in which the vehicle is directed forward.

  The vehicle body front portion 1f and the vehicle body rear portion 1r are connected via a low floor portion 1c, and the vehicle body frame forming the skeleton of the vehicle body is generally composed of the down tube 3 and the main pipe 4.

  That is, the down tube 3 extends downward from the head pipe 2 at the front part 1f of the vehicle body, the down tube 3 is bent horizontally at the lower end and extends rearward under the floor 1c, and a pair of left and right main pipes 4 at the rear end. The main pipe 4 is bent at the upper part of the rising part 4a that suddenly rises from the connecting part to form an inclined part 4b extending obliquely rearward, and the upper part of the inclined part 4b is further bent and substantially rearward. A horizontal portion 4c extending horizontally is formed.

A fuel tank 5 and the like are supported by a rear horizontal portion 4 c of the main pipe 4, and a seat 6 is disposed above the main pipe 4 so as to cover the fuel tank 5.
On the other hand, at the vehicle body front portion 1f, a handle 11 is provided above and supported by the head pipe 2, a front fork 12 extends downward, and a front wheel 13 is supported at the lower end thereof.

A bracket 15 protrudes from the vicinity of the front side of the inclined portion 4 b of the main pipe 4, and a power unit 20 is swingably connected to the bracket 15 via a link member 16.
The power unit 20 has a single-cylinder, four-stroke, water-cooled internal combustion engine 30 in front of the cylinder block 32, the cylinder head 33, and the cylinder head cover 34, which are stacked one after the other from the crankcase 31. An end portion of the pivot support bracket 18 that is configured in an inclined posture and protrudes upward from the upper portion of the crankcase 31 is connected to the link member 16 via a pivot shaft 19 (see FIG. 2).

  As described above, the pivot support bracket 18 protrudes from the upper portion of the crankcase 31 and the connecting portion connected to the main pipe 4 is located above the crankcase 31 so that the center of gravity of the internal combustion engine 30 can be easily lowered.

The power unit 20 includes a belt-type continuously variable transmission 37 extending rearward from the internal combustion engine 30, and a rear wheel 21 is provided on a rear axle 21a that is pivotally supported by a speed reduction mechanism 38 provided at a rear portion thereof.
A rear cushion 22 is interposed between the upper end of the speed reduction mechanism 38 and the upper bent portion of the main pipe 4.

  An upper part of the power unit 20 is provided with a throttle body 25 connected to an intake pipe 23 extending from an upper part of a cylinder head 33 that is largely inclined forward of the internal combustion engine 30, and an air cleaner 26 connected to the throttle body 25. Yes.

On the other hand, the exhaust pipe 27 extending from the lower part of the cylinder head 33 extends downward while being biased to the right side, curves backward, and extends rearward below a radiator 50 described later provided on the right side of the crankcase 31. It is linked to 28.
The muffler 28 is suspended from the crankcase 31 by a bracket 29 and is located on the right side of the rear wheel 21.

  Brackets 40a and 40b are provided on the inclined portion 4b of the main pipe 4 before and after the bracket 15 for supporting the power unit 20, and stays 41 bent in a U-shape are connected to the brackets 40a and 40b at both ends. Each is fixed and extends obliquely downward and projects sideways.

A step support portion 42 is fixed to a bent portion that protrudes to the outermost side of the stay 41 that is bent in this square shape, and a base end portion of the pinion step 43 is pivotally supported on the step support portion 42.
The pinion step 43 is provided at a symmetrical position of the vehicle body, and is used as a footrest for a passenger by swinging horizontally from a lying state along the vehicle body to a standing state protruding outward.

  The pinion step 43 on the right side of the vehicle body is positioned on the right side of the upper portion of the radiator 50 together with the step support portion 42 because the stay 41 extends obliquely downward from the main pipe 4 above the radiator 50.

  The front part 1f of the vehicle body is covered from the front and back by the front cover 9a and the leg shield 9b from the left and right sides by the front lower cover 9c, and the center part of the handle 11 is covered by the handle cover 9d.

The floor portion 1c is covered with a side cover 9e, and the vehicle body rear portion 1r is covered with a body cover 10 from the left and right sides.
The step support portion 42 faces the opening of the body cover 10 and the pinion step 43 protrudes outside the body cover 10.

The radiator 50 arranged on the right side of the crankcase 31 has a structure in which a rectangular heat radiating core 51 is sandwiched between an upper radiator tank 52 and a lower radiator tank 53, and is inclined forward. It is attached to the crankcase 31 (see FIG. 2).
The upper radiator tank portion 52 and the lower radiator tank portion 53 are made of a synthetic resin and are reduced in weight.

  As shown in FIGS. 3 to 5, the upper radiator tank portion 52 has an upper side 52f that opposes the lower third side (about the front third) of the lower side 52a that is inclined in a side view. The lower side 52a is formed in parallel with a certain interval to form a low side tank portion 52L, and is formed in a portion of about 2/3 of the inclined lower side 52u on the high side (about 2/3 of the rear side). The opposing upper side 52r bulges upward from the upper side 52f of the low-side tank portion 52L to constitute the high-side tank portion 52U.

The bulging upper side 52r of the high-side tank portion 52U is formed with a front side wall 52uf that is steeply inclined toward the front side (the low-side tank portion 52L side) of the top wall 52uc and a rear side wall 52ur that is steeply inclined toward the rear side.
A cooling water supply cylinder 52p is formed to extend upward in the latter half of the top wall 52uc, and the filler cap 54 is closed at the opening.

An introduction connecting pipe 52J for introducing cooling water is formed to project forward from the upper part of the front side wall 52uf facing the front of the high-side tank portion 52U.
The introduction connecting pipe 52J protrudes substantially parallel to the upper side 52f of the low-side tank portion 52L.
Mounting brackets 52b and 52b are provided with mounting holes at the front portion of the low-side tank portion 52L and the lower portion of the rear side wall 52ur of the high-side tank portion 52U.

Therefore, a space 52S is formed between the low side tank portion 52L and the introduction connecting pipe 52J above the lower side tank portion 52L in front of the front side wall 52uf of the high side tank portion 52U. (See FIG. 3).
A mounting bracket 52b is erected in front of the space 52S.

On the other hand, the lower radiator tank portion 53 is provided with a drain cock 53a at substantially the center, and a cooling water outlet connecting pipe 53J projects forward at the front end.
Mounting brackets 53b and 53b are formed with mounting holes on the front and rear of the lower part, respectively.

As shown in FIGS. 4 and 5, the upper radiator tank portion 52 is covered with a metal tank cover 55 from the side.
Referring to FIGS. 3, 4, and 5, tank cover 55 is generally composed of outer wall 55 s and upper wall 55 u having substantially the same outer shape as upper radiator tank portion 52, and bulges above upper wall 55 u. An arcuate defect 55p into which the supply cylinder 52p fits is formed in a part of the rear portion.

A semi-cylindrical connecting tube cover portion 55j extends from the upper portion of the front side wall 55uf of the rear portion bulging above the upper wall 55u along the introduction connecting tube 52J of the upper radiator tank portion 52.
Accordingly, a space 55S is formed between the connecting pipe cover portion 55j and the front portion of the upper wall 55u.
Note that mounting brackets 55b and 55b are provided with mounting holes in front and rear of the upper wall 55u.

When the upper radiator tank 52 is covered with the tank cover 55 from the side, the supply cylinder 52p is fitted into the missing portion 55p of the tank cover 55 and protrudes upward, and the introduction connecting pipe 52J is formed into a semi-cylindrical connecting pipe cover 55j. Then, the connecting pipe cover portion 55j covers from the side and the upper and lower sides from the base of the introducing connecting pipe 52J to the vicinity of the tip.
The upper radiator tank 52 and the tank cover 55 are connected to the crankcase 31 through bolts 56 and 56 through the mounting holes of the mounting brackets 52b and 52b of the upper radiator tank 52 and the mounting brackets 55b and 55b of the tank cover 55. It is tightened together.

Thus, the upper radiator tank portion 52 made of synthetic resin is covered and protected by the metal tank cover 55 from the side.
At the same time, the small-diameter introduction connecting pipe 52J is also reliably protected by the connecting pipe cover portion 55j which is an extension portion integrated with the tank cover 55.
The space 52S of the upper radiator tank 52 is overlapped with the space 55S of the tank cover 55 to secure a space.

As shown in FIG. 2, the radiator 50 is attached to the right side of the crankcase 31 with the upper radiator tank portion 52 covered with the tank cover 55 so as to be inclined forward.
Then, in a side view of FIG. 2, the pivot support bracket that protrudes from the upper part of the crankcase 31 into the space 52S (the space 55S of the tank cover 55) between the low-side tank portion 52L and the introduction connecting pipe 52J thereabove. 18 pivot shaft 19 portions are located.

Therefore, with the radiator 50 attached to the right side of the crankcase 31, the pivot shaft 19 portion of the pivot support bracket 18 is connected to the lower tank portion 52L of the upper radiator tank portion 52 and the introduction connecting pipe in a side view as shown in FIG. Since it can be seen in the space 52S (the space 55S of the tank cover 55) between 52J, the assembly work of the pivot support portion can be facilitated.
The pivot shaft 19 of the pivot support bracket 18 protrudes from the upper part of the crankcase 31 and the link member 16 connected to the vehicle body frame is above the crankcase 31 so that the center of gravity of the internal combustion engine can be easily lowered.

  Since the pivot shaft 19 of the pivot support bracket 18 is positioned between the low-side tank portion 52L and the introduction connection pipe 52J in a side view, the high-side tank portion in which the introduction connection pipe 52J protrudes above the pivot support bracket 18 52U bulges upward to increase the volume and secure the capacity of the upper radiator tank 52.

  In the upper radiator tank portion 52, the cooling water swelled upward and introduced into the high-side tank portion 52U having a large capacity flows into the low-side tank portion 52L having a small capacity, and the inclined lower side of the upper radiator tank portion 52 Since water is distributed to the heat radiating core 51 from the 52a without any deviation, the entire heat radiating core 51 can be effectively utilized and efficiently cooled.

  Further, the upper radiator tank section 52 is configured such that the introduction connecting pipe 52J is substantially connected to the upper side 52f of the low side tank part 52L from the upper part of the front side wall 52uf on the low side tank part 52L side of the bulging upper side 52r of the high side tank part 52U. Since it is projecting in parallel, the cooling water that is vigorously introduced rearward from the introduction connecting pipe 52J of the front side wall 52uf hits the inner surface of the rear side wall 52ur of the high side tank portion and changes its direction downward and forward to the low side tank. Since it is guided by the portion 52L, the cooling water can be sufficiently supplied to the low-side tank portion 52L having a small capacity, and the cooling water can be efficiently cooled by flowing the cooling water through the entire heat radiating core portion 51.

The lower tank portion 52L of the upper radiator tank portion 52 is formed so that the upper side 52f is substantially parallel to the inclined lower side 52a with a substantially constant interval. The fluctuation due to the shaking of the 52 L cooling water can be suppressed, and the cooling water can be stably supplied to the heat radiating core 51.

  The tank cover 55 has a connecting pipe cover portion 55j extending along the inlet connecting pipe 52J, and the connecting pipe cover portion 55j covers the side and upper and lower sides of the inlet connecting pipe 52J. The small diameter introduction connecting pipe can be protected from an external force or the like by the portion 55j.

  Further, as described above, the pinion step 43 on the right side of the vehicle body, together with the step support portion 42, is located on the right side of the upper portion of the radiator 50 (the upper radiator tank portion 52 and the introduction connecting pipe 52J), that is, the tank cover 55 and the connecting pipe cover portion 55j. Since it is located on the right side, the pinion step 43 can reliably protect the introduction connecting pipe 52J.

A cooling water circulation system through which the cooling water cooled by the radiator 50 circulates will be described with reference to FIGS.
A water pump 60 is attached to the right side surface of the cylinder head 33.

  In the water pump 60, a water pump body 61 that supports the pump drive shaft 63 is fitted and fixed to the right side wall of the cylinder head 33, and an impeller 64 fitted to the pump drive shaft 63 is accommodated in the water pump 60. A pump cover 62 is covered.

The water pump cover 62 has a water suction tube portion 62b extending from the suction port portion 62a bulging rightward of the water pump drive shaft 63 along the right side surface of the cylinder head 33 in the direction of the radiator 50, and an impeller 64. A discharge port portion 62c extends obliquely rearward and downward from a lower portion of the outer periphery of the tube, and a discharge connection pipe 67 projects from the discharge port portion 62c (see FIG. 2).
An air vent 62d is formed in the upper part of the outer periphery of the impeller 64, and an air vent connecting pipe 68 projects upward from the air vent 62d.

A connecting portion 62bb is formed at the upstream end (rear end) of the water suction cylindrical portion 62b, and the thermostat 70 is connected to the connecting portion 62bb.
In the thermostat 70, the bypass connection pipe 71 extends obliquely upward from the upper part, and the inflow connection pipe 72 extends obliquely downward to the right from the lower part.

Further, a branch connection pipe 75 is provided on the upper part of the right side surface of the cylinder head 33 so as to protrude rightward.
The branch connecting pipe 75 is fitted in a watertight manner in a circular opening in which the upstream base pipe 75b directly communicates with the uppermost portion of the water jacket 33w on the right side surface of the cylinder head 33 (see FIG. 6), and extends upward and downward. , 75f are fixed to the right side surface of the cylinder head 33 by bolts 79 (see FIG. 2).

  As shown in FIGS. 2 and 6, the branch connection pipe 75 is bent obliquely rearward from the upstream base pipe 75b and a main pipe 75a protrudes, and from the middle of the main pipe 75a protruding obliquely rearward to the rear. The bypass branch pipe 76 branches and protrudes slightly upward, and a small-diameter air vent branch pipe 77 branches and protrudes slightly downward from the middle of the main pipe 75a.

  Referring to FIG. 2, the main pipe 75a of the branch connection pipe 75 is connected to the bypass connecting pipe 52J projecting forward from the high-side tank portion 52U of the upper radiator tank section 52 of the radiator 50 by the radiator inflow hose 80, and is bypassed. The branch pipe 76 is connected by a bypass connection pipe 71 of the thermostat 70 and a bypass hose 81, and the air vent branch pipe 77 is connected by an air vent connection pipe 68 of the water pump 60 and an air vent connection hose 82.

  A lead-out connecting pipe 53J projecting forward from the lower radiator tank section 53 of the radiator 50 and an inflow connecting pipe 72 of the thermostat 70 are connected by a radiator outlet hose 73, and a discharge connecting pipe 67 of the water pump 60 is connected to the cylinder block 32. The inflow connection pipe 78 communicated with the water jacket and the connection hose 84 are connected.

The cooling water cooled by the radiator 80 is guided from the lower radiator tank 83 to the thermostat 70 through the radiator outlet hose 83.
The cooling water guided to the thermostat 70 is sucked into the water pump 60 from the thermostat 70 through the water suction cylinder 62b, and is supplied from the discharge port 62c of the water pump 60 to the water jacket of the cylinder block 32 through the connecting hose 84. Is done.

  The water jacket of the cylinder block 32 communicates with the water jacket 33w of the cylinder head 33, and the cooling water that flows through each water jacket and cools the cylinder block 32 and the cylinder head 33 projects into the upper portion of the right side surface of the cylinder head 33. A water path is formed from the branch connection pipe 75 provided to return to the upper tank portion 52 of the radiator 50 via the radiator inflow hose 80.

  In addition, there is a water path in which the cooling water that has flowed through the water jacket of the cylinder block 32 and the cylinder head 33 bypasses the radiator 50 from the bypass branch pipe 76 branched from the branch connection pipe 75 to the thermostat 70 via the bypass hose 81. Is formed.

  During the warm-up operation in which the internal combustion engine 30 does not warm up, the thermostat 70 closes the water path flowing in from the radiator 50, opens the water path bypassed from the cylinder head 33, accelerates the warm-up in the water path that does not pass through the radiator 50, and warms up. After the operation is completed, the thermostat 70 closes the water path bypassed from the cylinder head 33 and opens the water path flowing in from the radiator 50, and the cooling water cooled by the radiator 50 is supplied from the cylinder block 32 to the cylinder head 33. And the cylinder block 32 and the cylinder head 33 are cooled.

  The air in the water pump 60 exits from the air vent 62d at the upper part of the water pump cover 62 to the upper branch connecting pipe 75 via the air vent connecting hose 82, and the radiator inflow hose is inclined slightly upward as it goes rearward. It is possible to reach the upper part of the high side tank portion 52U of the upper radiator tank portion 52 through 80, reach the filler cap 54, and remove air from the water path.

1 is an overall side view of a scooter type motorcycle equipped with a unit swing type internal combustion engine according to an embodiment of the present invention. 1 is a right side view of a unit swing type internal combustion engine to which a radiator is attached. It is a disassembled side view of a radiator and a tank cover. It is an exploded top view of a radiator and a tank cover. It is a disassembled front view of a radiator and a tank cover. It is a top view of a cylinder head, a cylinder head cover, and its vicinity.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Scooter type motorcycle, 4 ... Main pipe, 15 ... Bracket, 16 ... Link member, 17 ..., 18 ... Pivot support bracket, 19 ... Pivot shaft,
20 ... Power unit, 30 ... Internal combustion engine, 31 ... Crank case, 32 ... Cylinder block, 33 ... Cylinder head, 34 ... Cylinder head cover, 41 ... Stay, 42 ... Step support, 43 ... Pinion step,
50 ... Radiator, 51 ... Radiation core, 52 ... Upper radiator tank, 52a ... Lower side, 52U ... High side tank, 52r ... Upper side, 52uc ... Top wall, 52uf ... Front side wall, 52ur ... Rear side wall, 52p ... Supply Tube, 52J ... Inlet connection pipe, 52L ... Low side tank portion, 52f ... Upper side, 52S ... Space, 53 ... Lower radiator tank section, 53J ... Lead connection pipe, 54 ... Filler cap,
55 ... Tank cover, 55uc ... Top wall, 55s ... Outer wall, 55u ... Upper wall, 55uf ... Front side wall, 55j ... Connection pipe cover, 55p ... Defect, 55b ... Bracket, 55S ... Space, 56 ... Bolt,
60 ... Water pump, 70 ... Thermostat, 75 ... Branch connection pipe.

Claims (5)

A unit swing type internal combustion engine is pivotally supported by connecting a pivot support portion (18) protruding from the upper part of the crankcase (31) to the vehicle body frame (4) via a support link member (16),
A radiator (50) having an upper radiator tank portion (52) and a lower radiator tank portion (53) above and below sandwiching a rectangular heat dissipating core portion (51) in side view on the side of the crankcase (31). In the radiator structure of the unit swing type internal combustion engine disposed,
The radiator (50) as a whole is inclined forward, and the upper radiator tank part (52) to which cooling water is supplied to the heat radiating core part (51) is also inclined forward .
The upper radiator tank portion (52) includes a side view at a lower side and become part formed that lower side tank portions (52L), a high is formed on the portion serving side the upper wall of the lower side tank portions (52L) ( 52f) constitutes a high-side tank part (52U) that bulges upward from which cooling water is introduced,
The upper wall (52r) of the high-side tank portion (52U) is formed to be inclined forward from the top wall (52uc) and the top wall (52uc), and the upper wall (52f) of the low-side tank portion (52L). ) And a rear side wall (52ur) formed to be inclined rearward from the top wall (55uc),
The upper radiator tank section (52) is positioned above the low tank section (52L) and in the space (52S) in front of the high tank section (52U) in the side view. Arrange
Wherein said front wall (52uf) introducing connecting pipe from the upper part of the cooling water toward the front of the high-side tank portion (52U) (52J) substantially parallel to the upper wall of the lower side tank portions (52L) (52f) Project
The pivot support (18) is located between the low-side tank portion (52L) and the introduction connecting pipe (52J) in a side view;
The tank cover (55) avoids the pivot support part (18) in a side view and covers the upper radiator tank part (52) from the side along its contour,
The tank cover (55) includes a connection pipe cover portion (55j) extending along the introduction connection pipe (52J) and covering at least a side of the introduction connection pipe (52J). Structure of the internal combustion engine. The unit swing type internal combustion engine according to claim 1 , wherein the upper wall (52f) of the low-side tank portion (52L) is inclined in parallel to the forward inclination of the heat radiating core portion (51). Radiator structure.   The radiator structure of the unit swing type internal combustion engine according to claim 1 or 2, wherein a pinion step (43) is disposed on a side of the introduction connecting pipe (52J). A branch connection pipe (75) communicating with the water jacket (33w) is provided at the upper part of the right side surface of the cylinder head (33), and the main pipe (75a) of the branch connection pipe (75) is the pivot support portion in a side view. Located above (18),
  The radiator of a unit swing type internal combustion engine according to any one of claims 1 to 3, wherein the main pipe (75a) and the introduction connecting pipe (52J) are connected by a hose (80). Construction. The lead-out connecting pipe (53J) protrudes from the lower radiator tank section (53) toward the front substantially parallel to the introduction connecting pipe (52J). A radiator structure of the unit swing type internal combustion engine according to the item.

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