JP2009235926A - Engine cooling device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine cooling device for a vehicle which rationally integrates a water temperature sensor by suppressing the dispersion of cooling water temperature when an engine is cold and by simplifying a cooling water passage. <P>SOLUTION: The engine cooling device forces cooling water to flow into the upstream side tank 31a on the upstream side of the radiator core (a heat exchange part) 31c of a radiator 31 through the medium of a radiator introduction hose 46 extending from a main outflow part 45 in a thermostat 41 when the engine is hot, and blocks the main outflow part 45 and forces cooling water to flow into the downstream side tank 31b on the downstream side of the radiator core 31c of the radiator 31 through the medium of a bypass hose 52 extending from a sub-outflow part 51 in a thermostat 41 when the engine is cold. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a water-cooled engine cooling device suitable for a saddle-ride type vehicle such as a motorcycle.

Conventionally, a discharge portion of a water pump interlocked with an engine is connected to an inflow portion of the water jacket of the engine, and an outflow portion of the water jacket is connected to an upstream tank of the radiator via a thermostat, and a downstream tank of the radiator In a vehicle engine cooling device connected to the suction portion of the water pump, the thermostat stops the flow of cooling water when the engine is cold (see, for example, Patent Document 1).
Japanese Patent Publication No. 5-81729

However, in the conventional configuration, when the engine is cold, temperature variation occurs due to the retention of the cooling water in the cooling water channel, and it is difficult to accurately manage the cooling water temperature as the engine temperature.
On the other hand, in recent water-cooled engines, when the engine is warm, the coolant flows into the upstream tank of the radiator through a main outflow passage extending from the main outflow portion of the thermostat, while the main outflow portion is closed when the engine is cold. There is also a type in which cooling water is allowed to flow to the suction portion of the water pump through a sub-outflow passage extending from the sub-outflow portion of the thermostat. In this case, the outflow passage from the downstream tank of the radiator and the sub outflow passage are connected in parallel to the suction portion of the water pump, and the cooling water passage is complicated due to the overlap of the respective outflow passages.
Some of the above-mentioned water-cooled engines are provided with a water temperature sensor corresponding to the control of a water temperature gauge or the like in the thermostat, while a water temperature sensor corresponding to the control of the radiator fan is separately provided in the tank on the downstream side of the radiator. Integration of multiple water temperature sensors has been desired.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to suppress variation in cooling water temperature when the engine is cold, simplify a cooling water channel, and rationally integrate a water temperature sensor in a vehicle engine cooling device.

As means for solving the above problems, the invention described in claim 1
The discharge portion (for example, the discharge portion 35 of the embodiment) of the water pump (for example, the water pump 34 of the embodiment) interlocked with the engine (for example, the engine 21 of the embodiment) is the water jacket of the engine (for example, the water jacket W of the embodiment). Of the water jacket (for example, the outflow portion 38 of the embodiment) is connected to a radiator (for example, the thermostat 41 of the embodiment) via a thermostat (for example, the thermostat 41 of the embodiment). A radiator 31) is connected to an upstream tank (for example, the upstream tank 31a of the embodiment) that is upstream of a heat exchange section (for example, the radiator core 31c of the embodiment), and is downstream of the heat exchanger of the radiator. A side tank (for example, the downstream tank 31b in the embodiment) is a suction portion (for example, the suction portion in the embodiment) of the water pump. In the vehicle engine cooling device connected to 0), when the engine is warm, via the main outflow passage (for example, the radiator introduction hose 46 of the embodiment) extending from the main outflow portion (for example, the main outflow portion 45 of the embodiment) of the thermostat. While flowing cooling water to the upstream tank of the radiator, when the engine is cold, the main outflow portion is closed and the sub outflow passage (for example, the sub outflow portion 51 of the embodiment) extends from the sub outflow portion of the thermostat (for example, the sub outflow portion of the embodiment). Cooling water is allowed to flow to the downstream tank of the radiator via a bypass hose 52).

  According to a second aspect of the present invention, the thermostat is provided with a water temperature sensor (for example, the water temperature sensor 54 of the embodiment) for detecting the cooling water temperature on the inflow portion (for example, the inflow portion 44 of the embodiment) side from the water jacket, A radiator fan (for example, the radiator fan 31d in the embodiment) is driven based on the detection result of the water temperature sensor.

  The invention described in claim 3 is characterized in that the thermostat is arranged closer to the downstream tank of the radiator than to the water pump.

According to the first aspect of the present invention, the thermostat does not stop the flow of the cooling water even when the engine is cold, and the cooling water that has passed through the water jacket of the engine is circulated without passing through the heat exchanging portion. It is possible to promptly shift to a favorable operating state by promoting warm-up of the engine.
Further, the cooling water temperature as the engine temperature can be managed more accurately by eliminating the retention of the cooling water in the cooling water passage when the engine is cold and eliminating the temperature variation of the cooling water.
Further, by connecting a sub-outflow passage extending from the sub-outflow portion of the thermostat to the downstream tank of the radiator, the outflow passage from the downstream tank of the radiator and the sub-outflow passage around the suction portion of the water pump is eliminated. The cooling water channel can be simplified.

According to the invention described in claim 2, heat is radiated by the radiator immediately after passing through the water jacket of the engine by a single water temperature sensor provided in the thermostat in both cases of the cold engine and the warm engine. The previous cooling water temperature can be detected, and the cost can be reduced by reducing the number of parts compared to the case where the water temperature sensors are provided in both the downstream tank and the thermostat of the radiator as in the prior art.
In addition, it becomes possible to eliminate the water temperature sensor for driving the radiator fan that has been provided in the downstream tank of the radiator, and the opening for attaching the water temperature sensor provided in the downstream tank of the existing radiator is connected to the sub outflow passage. The existing radiator can be used with less processing, and the cost can be reduced.

  According to the third aspect of the present invention, the length of the sub-outflow passage can be shortened compared to the case where the sub-outflow passage extending from the sub-outflow portion of the thermostat is connected to the suction portion of the water pump as in the prior art, and The piping can be simplified.

  Embodiments of the present invention will be described below with reference to the drawings. Note that the directions such as front, rear, left and right in the following description are the same as those in the vehicle unless otherwise specified. In the figure, the arrow FR indicates the front of the vehicle, the arrow LH indicates the left side of the vehicle, and the arrow UP indicates the upper side of the vehicle.

  As shown in FIG. 1, the upper portions of the left and right front forks 3 that pivotally support the front wheels 2 of a motorcycle (saddle-type vehicle) 1 can be steered to a head pipe 6 at the front end of a vehicle body frame 5 via a steering stem 4. It is supported by. A steering bar handle 4 a is attached to the steering stem 4. A left and right main frame 7 extends behind the head pipe 6 so as to branch left and right.

  The left and right main frames 7 are formed by integrally welding an upper pipe 7a and a lower pipe 7b extending obliquely downward and rearward from the top and bottom of the head pipe 6 and a plurality of connecting pipes 7c provided between the two pipes in a truss shape. Left and right joint plates 8 press-molded into a predetermined shape are integrally welded to the rear ends of the left and right main frames 7, respectively.

  The upper ends of the left and right pivot plates 9 are bolted to the lower ends of the left and right joint plates 8, and the front end of the swing arm 11 is swingable up and down via a pivot shaft 11a at the upper and lower intermediate portions of the left and right pivot plates 9. It is pivoted. A rear wheel 12 is pivotally supported at the rear end portion of the swing arm 11, and a rear cushion 13 is interposed between the front portion of the swing arm 11 and the upper end portions of the left and right joint plates 8. Front end portions of the left and right seat frames 15 that support the occupant seat 14 are bolted to the upper rear side of the left and right joint plates 8. A fuel tank 16 is disposed in front of the seat 14.

  Referring also to FIG. 2, an engine (internal combustion engine) 21 that is a prime mover of the motorcycle 1 is disposed substantially at the center of the vehicle body. The engine 21 is a V-type two-cylinder engine having a crankshaft 22a along the vehicle body width direction (left-right direction). A forward tilt cylinder 23 and a rear tilt cylinder 24 (hereinafter simply referred to as front and rear cylinders) are disposed on the crankcase 22. ) Are established. Pistons are fitted in the front and rear cylinders 23 and 24 so as to be able to reciprocate, and the reciprocation of the pistons is converted into rotational movement of the crankshaft 22a via connecting rods (both not shown). In FIG. 2, reference numerals C <b> 1 and C <b> 2 indicate cylinder center axes along the standing direction of the front and rear cylinders 23 and 24, respectively.

  Above the banks of the front and rear cylinders 23 and 24, a pair of throttle bodies 25a and 25b corresponding to the front and rear cylinders are arranged side by side (see FIG. 2), and lower ends (downstream) of the throttle bodies 25a and 25b. Side end) is connected to the rear part of the cylinder head 23a of the front cylinder 23 and the front part of the cylinder head 24a of the rear cylinder 24, respectively. Base ends of front and rear exhaust pipes 26a and 26b corresponding to the respective cylinders are connected to the front part of the cylinder head 23a of the front cylinder 23 and the rear part of the cylinder head 24a of the rear cylinder 24, respectively.

  Here, the motorcycle 1 is provided with an electronically controlled fuel injection device in the intake system (fuel supply system) of the engine 21, and based on various vehicle information such as the throttle opening, the engine speed, and the vehicle speed, The illustrated electronic control unit operates injectors provided in the throttle bodies 25a and 25b to control the fuel injection amount and the injection timing.

Referring to FIG. 2, the front exhaust pipe 26 a is curved immediately after extending from the front portion of the cylinder head 23 a of the front cylinder 23 obliquely forward and downward, and extends downward and obliquely downward, below the crankcase 22 and the crankcase. After passing through the side of the oil pan 22b attached to the bottom 22, the oil pan 22 is further bent and becomes substantially horizontal and extends rearward.
On the other hand, the rear exhaust pipe 26b extends obliquely rearward and downward from the rear portion of the cylinder head 24a of the rear cylinder 24, and then curves and extends downwardly behind the pivot shaft 11a of the swing arm 11, and the lower end portion of the left and right pivot plates 9 After being curved in the vicinity (near the rear end portion (extended tip portion) of the front exhaust pipe 26a) and becoming substantially horizontal and extending forward, it is further bent and extended so as to be folded back.

  The leading ends of the front and rear exhaust pipes 26a and 26b join together to form a single collecting pipe 27. The collecting pipe 27 extends obliquely upward and rearward, and the front end of a silencer 28 disposed on the right side of the rear wheel 12. Connected to. In the collecting pipe 27 and in the front part of the silencer 28, exhaust gas purifying catalytic converters 27a and 28a are respectively incorporated. An exhaust gas sensor (oxygen concentration sensor) 29 is provided in the collecting pipe 27 immediately upstream of the catalytic converter 27a. Each of the catalytic converters 27a, 28a and the exhaust gas sensor 29 performs its function by heating a catalyst such as platinum to a predetermined reaction temperature.

  Here, the rear exhaust pipe 26b is a single pipe, whereas the front exhaust pipe 26a is a double pipe so that the exhaust gas from the front cylinder 23 is hardly cooled by the traveling wind. As a result, the temperature rise of the catalytic converters 27a, 28a and the exhaust gas sensor 29 due to the exhaust gas from the front and rear cylinders 23, 24 is promoted, and the detection accuracy of the exhaust gas sensor 29 is quickly increased, and the catalytic converters 27a, 28a are quickly activated. It can be activated to obtain a good exhaust gas purification performance.

The rear part of the front cylinder 23 is supported by the lower part of the left and right main frames 7, the rear upper part of the crankcase 22 is supported by the lower end part of the left and right joint plate 8 and the upper end part of the left and right pivot plate 9, and the lower rear part of the crankcase 22 is It is supported at the lower end of the left and right pivot plate 9.
A clutch mechanism and a transmission (not shown) are accommodated in the rear part of the crankcase 22, and the rotational power of the crankshaft 22a is output to the left side of the rear part of the crankcase 22 through the clutch mechanism and the transmission. It is transmitted to the rear wheel 12 through a chain drive type transmission mechanism.

  Referring to FIGS. 2 and 4, a radiator 31 for cooling the engine 21 is disposed in front of the head cover 23 b of the front cylinder 23. The radiator 31 has a horizontally long rectangular shape, and is disposed in a standing posture that is slightly inclined in a side view so that the upper portion is positioned forward. An upper support bracket 32 is fixed to the upper portion of the radiator 31, and the upper support bracket 32 is formed on a gusset 6 a that extends to the lower side of the front end of the left and right main frames 7 and to the rear side of the lower end of the head pipe 6. Is elastically supported. On the other hand, a lower support bracket 33 is fixed to the lower portion of the radiator 31, and the lower support bracket 33 is elastically supported by a support pin 33a projecting from a fixing bolt of the head cover 23b of the front cylinder 23.

Hereinafter, the overall configuration of the engine cooling device of the motorcycle 1 will be described with reference to FIG.
A water pump 34 that circulates engine coolant (coolant) is attached to the lower left side of the crankcase 22. The water pump 34 is a spiral pump in which an impeller is accommodated in a housing 34a. The water pump 34 is driven to rotate as the engine 21 operates (rotation of the crankshaft 22a), and sucks and discharges cooling water to circulate it.

  A discharge part 35 is provided in the upper part of the housing 34 a of the water pump 34, and one end side of a cooling water introduction pipe 36 is connected to the discharge part 35. The cooling water introduction pipe 36 extends upward and then bends obliquely upward and forward, and further bent inwardly to the left and right so as to enter between the front and rear cylinders 23 and 24, and then an inflow portion provided between the front and rear cylinders 23 and 24. 37 is connected to the other end. The inflow portion 37 communicates with a water jacket W (see FIG. 3) appropriately formed in the front and rear cylinders 23 and 24, and the cooling water pumped from the water pump 34 through the inflow portion 37 enters the front and rear water jacket W. It flows in and absorbs heat generated by the front and rear cylinders 23 and 24.

  The front and rear outflow portions 38 for cooling water from the front and rear water jackets W are respectively provided on the rear side of the front cylinder 23 and the front side of the rear cylinder 24, and one end side of the front and rear cooling water outlet hose 39 is connected to the front and rear outflow portion 38. Each is connected. The front / rear cooling water outlet hose 39 extends to the vicinity of the upper end of the head cover 23b along the rear side of the front cylinder 23, and connects the other end side to a thermostat 41 disposed immediately above the head cover 23b.

  The thermostat 41 accommodates the thermostat main body 43 in the hollow casing 42 (refer FIG. 3). In the rear part of the casing 42 of the thermostat 41, left and right inflow portions 44 are provided to protrude rearward, and the other end sides of the front and rear cooling water outlet hoses 39 are connected to the inflow portions 44, respectively. A main outflow portion 45 protrudes forward from the upper portion of the casing 42 of the thermostat 41, and one end side of a radiator introduction hose 46 is connected to the main outflow portion 45. The radiator introduction hose 46 bends and extends upward in front of the thermostat 41, then extends downward so as to be folded back to the right side thereof, and is bent appropriately, and then connected to the upstream tank 31a on the right side of the radiator 31. The thermostat 41 is positioned between the front portions of the left and right main frames 7 (near the head pipe 6), and is supported via a bracket B on the connection pipe 7c closest to the head pipe 6 in the main frame 7 (see FIG. 2).

  The radiator 31 is provided integrally with a vertically long upstream tank 31a along the right side of the radiator core 31c, which is a heat exchanging part constituting the center thereof, and is also provided on the left side of the radiator core 31c. A vertically long downstream tank 31b is integrally provided so as to extend from the upstream tank 31a (right side) upstream of the radiator core 31c toward the downstream tank 31b (left side) downstream of the radiator core 31c. Thus, when the cooling water is flowed, the so-called cross flow type (transverse flow type) is used in which heat is radiated by the radiator core 31c. A radiator fan 31d is attached to the rear side (back side) of the radiator core 31c.

An upstream inflow portion 47 is provided on the upper rear surface side of the upstream side tank 31 a, and the other end side of the radiator introduction hose 46 is connected to the upstream inflow portion 47.
A reservoir pipe joint 46a is interposed in the folded portion of the radiator introduction hose 46 after extending upward from the thermostat 41 (see FIG. 4). The reservoir pipe joint 46a is connected to a reservoir tank (not shown) disposed between the front portions of the left and right main frames 7, and when the cooling water in the cooling water passage increases, this is returned to the reservoir tank, and the cooling water is supplied. When is decreased, it can be replenished from the reservoir tank.

  A downstream outflow portion 48 is provided on the lower rear surface side of the downstream side tank 31 b, and one end side of the radiator outlet hose 49 is connected to the downstream outflow portion 48. The radiator outlet hose 49 extends obliquely downward and rearward along the left side of the front cylinder 23, then curves downward, and further curves backward to connect the other end side to the water pump 34. A suction part 50 is projected forward from the front part of the housing 34 a of the water pump 34, and the other end side of the radiator outlet hose 49 is connected to the suction part 50.

  A sub outflow portion 51 protrudes downward from the lower portion of the casing 42 of the thermostat 41, and one end side of a bypass hose 52 is connected to the sub outflow portion 51. The bypass hose 52 is bent to the left and right outside below the thermostat 41 and then bent forward, and the other end is connected to the downstream tank 31 b of the radiator 31. In the downstream tank 31 b, a downstream inflow portion 53 is provided immediately above the downstream outflow portion 48, and the other end side of the bypass hose 52 is connected to the downstream inflow portion 53.

The thermostat 41 uses the inside of the casing 42 as a part of the cooling water channel and switches the flow path of the cooling water by the operation of the thermostat main body 43.
Referring to FIG. 3, the thermostat body 43 incorporates a thermal expansion body that thermally expands or contracts due to a temperature change of the cooling water, and the main valve body 43 a and the sub valve body 43 b are integrally formed by a volume change of the thermal expansion body. It is a temperature sensing type automatic valve that opens and closes the main outflow part 45 and the sub outflow part 51 by reciprocating.

  When the engine 21 is cold, such as when the engine 21 is started (when the cooling water temperature (engine temperature) is equal to the outside air), the thermostat main body 43 closes the main outflow portion 45 and closes the main outflow portion 45. The valve body 43b opens the sub-outflow part 51 (see FIG. 3A), and the engine warms up after the engine 21 is warmed up (cooling water temperature (engine temperature) rises to a temperature suitable for the operation of the engine 21. The main valve body 43a opens the main outflow portion 45, and the sub valve body 43b closes the sub outflow portion 51 (see FIG. 3B).

That is, in the thermostat 41, when the engine is cold, the communication between the inflow portion 44 (water jacket W of the engine 21) and the main outflow portion 45 (upstream tank 31a of the radiator 31) is blocked, and the inflow portion 44 and the auxiliary outflow The part 51 (downstream tank 31b of the radiator 31) communicates. Further, when the engine is warm, the inflow portion 44 and the main outflow portion 45 communicate with each other, and the communication between the inflow portion 44 and the sub outflow portion 51 is blocked.
As a result, the cooling water flowing into the casing 42 of the thermostat 41 flows out from the sub-outflow portion 51 toward the downstream tank 31b when the engine is cold, and toward the upstream tank 31a from the main outflow portion 45 when the engine is warm. Leaked.

Next, the operation of the engine cooling device will be described.
First, when the water pump 34 is activated and the cooling water is discharged in accordance with the operation of the engine 21, the cooling water is introduced into the water jacket W of the front and rear cylinders 23 and 24 through the cooling water introduction pipe 36. , 24 is absorbed into the casing 42 of the thermostat 41 through the front and rear cooling water outlet hoses 39.

  At this time, if the engine 21 is in a cold state, as shown in FIG. 3A, the main outflow portion 45 is closed and the sub outflow portion 51 is opened in the thermostat 41, and the cooling introduced into the casing 42 is performed. Water is introduced into the downstream tank 31b of the radiator 31 via the bypass hose 52, and returned to the water pump 34 via the radiator outlet hose 49 without passing through the radiator core 31c. By circulating through such a path, although the cooling water absorbs the heat of the front and rear cylinders 23 and 24, the radiator 31 quickly raises the temperature without radiating heat and promotes warming up of the engine 21.

On the other hand, when the engine 21 shifts from the cold state to the warm state, as shown in FIG. 3 (b), the thermostat main body 43 is operated to open the main outflow portion 45 and the sub outflow portion 51 is closed. The cooling water introduced into 42 is introduced into the upstream tank 31a of the radiator 31 via the radiator introduction hose 46, and after radiating heat while passing through the radiator core 31c, reaches the downstream tank 31b of the radiator 31. It is returned to the water pump 34 via the radiator outlet hose 49. By circulating through such a path, the cooling water absorbs the heat of the front and rear cylinders 23 and 24 and dissipates heat by the radiator 31, so that the engine 21 is maintained at a temperature suitable for a good operating state.
When the cooling water temperature exceeds a predetermined upper limit due to a long stoppage or the like, the radiator fan 31d is operated to forcibly introduce the outside air into the radiator core 31c, thereby accelerating the heat dissipation of the cooling water and Prevent overheating.

  Here, as shown in FIGS. 2 and 4, the thermostat 41 positioned immediately above the head cover 23 b of the front cylinder 23 and the downstream tank 31 b of the radiator 31 positioned immediately in front of the head cover 23 b of the front cylinder 23 are: They are arranged relatively close to each other. On the other hand, the thermostat 41 and the water pump 34 disposed on the lower left side of the crankcase 22 are disposed relatively apart from each other. Furthermore, the sub-outflow part 51 of the thermostat 41 is arranged closer to the downstream inflow part 53 of the downstream tank 31 b of the radiator 31 than to the suction part 50 of the water pump 34.

  As a result, the bypass hose 52 is compared with the case where the sub outflow path is extended from the sub outflow section 51 of the thermostat 41 to the suction section 50 of the water pump 34 (the sub outflow path in this case is indicated by reference numeral 52 ′ in FIG. 4). And the overlap between the bypass hose 52 and the radiator outlet hose 49 in the vicinity of the water pump 34 is eliminated.

  Further, in the radiator 31, the water temperature sensor conventionally provided in the downstream tank 31b is eliminated, and the downstream outflow portion 48 is provided using the opening for attaching the water temperature sensor. That is, the bypass hose 52 can be connected, for example, by installing a nozzle in the opening, and the cooling water from the bypass hose 52 can flow into the downstream tank 31b.

  In the motorcycle 1, a water temperature sensor that detects the coolant temperature as the engine temperature is provided only in the casing 42 of the thermostat 41 (indicated by reference numeral 54 in FIG. 3). The inside of the casing 42 of the thermostat 41 constitutes a part of the cooling water passage, and a detection portion of the water temperature sensor 54 is provided in a space (inside the engine side water passage) communicating with the inflow portion 44 inside the casing 42. I'm here. In other words, the water temperature sensor 54 can detect the cooling water temperature before the radiator 31 radiates heat immediately after passing through the water jacket W of the engine 21 when the engine is cold or warm.

  The thermostat 41 causes the cooling water that has flowed into the casing 42 to flow out from the sub-outflow portion 51 when the engine is cold, and causes the cooling water that has flowed into the casing 42 to flow out from the main outflow portion 45 when the engine is warm. That is, the cooling water does not stay near the thermostat 41 when the engine is cold, the temperature variation of the cooling water is suppressed, and the detection accuracy of the cooling water temperature (engine temperature) by the water temperature sensor 54 is increased. Information detected by the water temperature sensor 54 is used to control a plurality of devices such as a water temperature gauge, a radiator fan 31d, and a fuel injection device.

  As described above, in the engine cooling device for a vehicle in the above embodiment, the discharge portion 35 of the water pump 34 interlocked with the engine 21 is connected to the inflow portion 37 of the water jacket W of the engine 21, The outflow part 38 is connected to the upstream tank 31a which is upstream of the radiator core (heat exchange part) 31c of the radiator 31 through the thermostat 41, and the downstream tank 31b of the radiator 31 is connected to the suction part 50 of the water pump 34. In the case where the engine is warm, the cooling water is supplied to the upstream tank 31a of the radiator 31 via the main outflow passage (radiator introduction hose 46) extending from the main outflow portion 45 of the thermostat 41, while the engine is cold Sometimes the main outlet 45 is closed and the thermostat 41 Sub outflow path extending from the sub-outlet unit 51 via the (bypass hose 52) on the downstream side tank 31b is the downstream side of the radiator core 31c of the radiator 31 in which the cooling water flows.

According to this configuration, the thermostat 41 does not stop the flow of the cooling water even when the engine is cold, and the cooling water that has passed through the water jacket W of the engine 21 is circulated without passing through the radiator core 31c. The warm-up can be promoted to quickly shift to a good operating state.
Further, the cooling water temperature as the engine temperature can be managed more accurately by eliminating the retention of the cooling water in the cooling water passage when the engine is cold and eliminating the temperature variation of the cooling water.
Further, by connecting a sub outflow passage (bypass hose 52) extending from the sub outflow portion 51 of the thermostat 41 to the downstream tank 31 b of the radiator 31, from the downstream tank 31 b of the radiator 31 around the suction portion 50 of the water pump 34. It is possible to eliminate the overlap between the outflow passage and the auxiliary outflow passage, thereby simplifying the cooling water passage.

The engine cooling device is provided with a water temperature sensor 54 for detecting a cooling water temperature on the inflow portion 44 side from the water jacket W in the thermostat 41, and drives the radiator fan 31d based on the detection result of the water temperature sensor 54. Thus, a single water temperature sensor 54 provided on the thermostat 41 allows the cooling water temperature to be radiated by the radiator 31 immediately after passing through the water jacket W of the engine 21 when the engine is cold or warm. As compared with the conventional case where the water temperature sensors are provided in both the downstream tank 31b and the thermostat 41 of the radiator 31, the cost can be reduced by reducing the number of parts.
Further, it is possible to eliminate the water temperature sensor for driving the radiator fan 31d that has been provided in the downstream tank 31b of the radiator 31 conventionally, and the opening for attaching the water temperature sensor provided in the downstream tank 31b of the existing radiator 31 has the above-described opening. It can be used as a connecting portion of the sub outflow passage, and the existing radiator 31 can be used with less processing, and the cost can be reduced.

  Further, the engine cooling device is arranged such that the thermostat 41 is disposed closer to the downstream tank 31b of the radiator 31 than the water pump 34, so that the sub-outflow portion of the thermostat 41 is conventionally provided. Compared with the case where the sub outflow passage extending from 51 is connected to the suction portion 50 of the water pump 34, the length of the sub outflow passage can be shortened and the piping thereof can be simplified.

The present invention is not limited to the above-described embodiment. For example, the radiator 31 may be a downflow type (longitudinal flow type, vertical flow type), and the sub-outflow portion 51 even when the thermostat 41 is warm in the engine. It may be a thing which cannot be closed.
Further, the present invention may be applied to various types of engines such as a V-type multi-cylinder engine having more than two cylinders, a parallel multiple cylinder engine, a single cylinder engine, and a vertically placed engine having a crankshaft along the vehicle longitudinal direction.
And the structure in the said Example is an example of this invention, and it cannot be overemphasized that a various change is possible in the range which does not deviate from the summary of the said invention not to mention that it can apply also to a three-wheel or four-wheel vehicle. .

1 is a left side view of a motorcycle according to an embodiment of the present invention. It is a principal part enlarged view of FIG. It is a block diagram of the engine cooling device of the said motorcycle, (a) shows when the engine is cold, and (b) shows when the engine is warm. It is a perspective view of a partial structure of the engine cooling device.

Explanation of symbols

1 Motorcycle (vehicle)
21 Engine 31 Radiator 31a Upstream tank 31b Downstream tank 31c Radiator core (heat exchanger)
31d Radiator fan 34 Water pump 35 Discharge section 37 Inflow section 38 Outflow section 41 Thermostat 44 Inflow section 45 Main outflow section 46 Radiator introduction hose (main outflow path)
50 Inhalation part 51 Sub outflow part 52 Bypass hose (sub outflow path)
54 Water temperature sensor W Water jacket

Claims (3)

The discharge part of the water pump interlocked with the engine is connected to the inflow part of the water jacket of the engine, and the outflow part of the water jacket is connected to the upstream tank that is upstream of the heat exchange part of the radiator via the thermostat, In a vehicle engine cooling apparatus in which a downstream tank, which is a downstream side of a heat exchange part of the radiator, is connected to a suction part of the water pump,
While the engine is warm, cooling water flows to the upstream tank of the radiator via a main outflow passage extending from the main outflow portion of the thermostat, while the main outflow portion is closed and extended from the suboutflow portion of the thermostat when the engine is cold. An engine cooling apparatus for a vehicle, characterized in that cooling water is allowed to flow to a downstream tank of the radiator via an outflow path.   2. The engine cooling of a vehicle according to claim 1, wherein a water temperature sensor that detects a cooling water temperature on an inflow portion from the water jacket is provided in the thermostat, and a radiator fan is driven based on a detection result of the water temperature sensor. apparatus. The vehicle engine cooling device according to claim 1 or 2, wherein the thermostat is arranged closer to a downstream tank of the radiator than to the water pump.

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