JPH07247838A - Cooling device for internal combustion engine - Google Patents

Abstract

PURPOSE:To improve engine performance by efficiently utilizing exhaust pulse even when external temperature conditions are varied around a cylinder or an exhaust pipe extending from the cylinder. CONSTITUTION:A cooling water jacket 66 is provided on an exhaust pipe 28 extending from a cylinder 24. A discharge side of a cooling water pump 56 is connected to one end of the jacket 66 through a water passage. The other end of the jacket 66 is connected to a suction side of the cooling water pump 56 through the other water passage. Flow rate adjusting means 63, 69 are provided for increasing the flow rate of the cooling water 54 as the temperature of the cooling water 54 flowing through at least one of the water passages.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine for driving a vehicle or the like, and more particularly to a cooling device for this internal combustion engine.

[0002]

2. Description of the Related Art Exhaust gas from a cylinder in an internal combustion engine is usually exhausted to the outside of a vehicle through an exhaust pipe extending from the cylinder. Further, in this case, a preferable equivalent pipe length is required for effectively utilizing the pulsation of exhaust gas passing through the exhaust pipe to improve engine performance, and based on the equivalent pipe length, the cross-sectional area and length of the exhaust pipe are It is set.

[0003]

By the way, in the motorcycle of the vehicles, the exhaust pipe is usually exposed outside the vehicle and is cooled by the running wind.

For this reason, the degree of cooling of the exhaust pipe largely depends on the outside air temperature and the outside temperature conditions such as rainy weather.

Therefore, even if the temperature of the exhaust gas immediately after being discharged from the cylinder is substantially constant, the temperature of the exhaust gas in the exhaust pipe is not constant due to the above external temperature condition.

[0006] Further, for example, in a ship traveling on the sea, a jacket for cooling water is provided in an exhaust pipe, and the exhaust pipe is cooled by flowing seawater through the jacket. Also in this case, the degree of cooling of the exhaust pipe is greatly affected by the external temperature condition such as the temperature of seawater, and the temperature of the exhaust gas in the exhaust pipe is not constant.

As described above, even if the operating state of the internal combustion engine is constant, if the temperature of the exhaust gas is not constant, there are the following problems.

That is, if the temperature of the exhaust gas in the exhaust pipe becomes too lower than the predetermined temperature due to the external temperature condition, the return timing of the reflected wave in the exhaust pulsation is delayed, and the exhaust pulsation cannot be effectively used.

Contrary to the above, if the temperature of the exhaust gas in the exhaust pipe becomes higher than the predetermined temperature, the return timing of the reflected wave in the exhaust pulsation becomes too early, and the pulsation is effectively used in this case as well. Can not be.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and exhaust pulsation is effective even if the external temperature condition around the cylinder and the exhaust pipe extending from the cylinder changes to a low level. The purpose is to be utilized to improve engine performance.

[0011]

A first invention of a cooling device for an internal combustion engine for achieving the above object is to provide a cooling water jacket 66 on an exhaust pipe 28 extending from a cylinder 24,
One end of the jacket 66 is connected to the discharge side of the cooling water pump 56 through a water passage, while the other end of the same jacket 66 is connected to the suction side of the cooling water pump 56 through another water passage. A flow rate adjusting unit 69 is provided to increase the flow rate of the cooling water 54 as the temperature of the cooling water 54 flowing through at least one of the water passages increases.

In the second invention, the cylinder 24 is provided with a first jacket 55 for cooling water, and the first jacket 5 is provided.
5, the discharge side of the cooling water pump 56 is connected to one end side of the cooling water pump 56, and the other end of the first jacket 55 is connected to the suction side of the cooling water pump 56 through another water path.
On the other hand, a second jacket 66 for cooling water is provided on the exhaust pipe 28 extending from the cylinder 24.
Cooling water pump 5
While the discharge side of 6 is connected, the other end of the second jacket 66 is passed through another water passage and the cooling water pump 56
Flow rate adjusting means for increasing the flow rate of the cooling water as the temperature of the cooling water 54 flowing through at least one of the water passages connecting the first jacket 55 and the cooling water pump 56 increases. 63 and 69 are provided.

Further, in the third aspect of the invention, the cylinder 24 is provided with the first jacket 55 for cooling water, and the exhaust pipe 28 extending from the cylinder 24 is provided with the second jacket 6 for cooling water.
6, the first jacket 55 and the second jacket 66 are connected to each other by a water passage,
No. 5 or the second jacket 66 is connected to the discharge side of the cooling water pump 56 through another water passage, and the other jacket is further connected to the suction side of the cooling water pump 56 through another water passage. Flow rate adjusting means 63 and 69 are provided to increase the flow rate of the cooling water connected to each other and increasing the temperature of the cooling water 54 flowing through at least one of the water passages.

[0014]

[Operation] The operation of the above configuration is as follows.

The water passage 6 is controlled by the flow rate adjusting means 63, 69.
The flow rate of the cooling water 54 increases as the temperature of the cooling water 54 flowing in any of 0 to 62, 67, 68 increases.

Therefore, if the temperature around the cylinder 24 and the exhaust pipe 28 extending from the cylinder 24 becomes low (or high), the temperature of the cooling water 54 becomes low (or high) accordingly. Then, since the temperature of the cooling water 54 becomes low (or high), the flow rate adjusting means 63, 69 causes the water passages 60 to 62, 67 ,.
Low (or high) flow of cooling water 54 through 68
To be done.

Therefore, the cooling of the exhaust pipe 28 by the cooling water 54 is suppressed (or promoted), and the supercooling (or insufficient cooling) of the exhaust 50 in the exhaust pipe 28 is suppressed.

As a result of the above, even if the temperature around the cylinder 24 and the exhaust pipe 28 extending from the cylinder 24 changes so as to become low (or high), it is not affected by this change, and the exhaust 50 in the exhaust pipe 28 is not affected. A certain temperature is ensured.

In the exhaust pipe 28, the cooling water 54 flows through the second jacket (jacket) 66 provided in the exhaust pipe 28, so that the exhaust 50 in the exhaust pipe 28 is cooled more than before. Becomes

Therefore, the return timing of the reflected wave of the exhaust pulsation tends to be delayed as a whole, and the corresponding pipe length can be shortened accordingly.

When the cylinder 24 is not sufficiently warmed, such as during warm-up operation, the engine 22 is normally in the low and medium rotation range. In such a case, according to the above configuration, since the exhaust pipe 28 is cooled by the cooling water 54 more than ever, the temperature of the exhaust 50 is lowered, and thus the reflected wave of the exhaust pulsation is reduced. The return tends to be delayed, and this is due to the internal combustion engine 21 in the above low and medium speed regions.
Match the operating conditions of.

Further, as the cooling water 54 flows through the first jacket (jacket) 55, the cooling water 54 is given heat from the exhaust 50, so that the cooling water 54 is supplied to the first jacket (jacket) 55 of the cylinder 24. In the case where the air flow is made to flow, the warm-up time of the cylinder 24 becomes short.

[0023]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIGS. 1 to 3 show a first embodiment.

In FIG. 2, reference numeral 1 in the drawing is an example of a vehicle, which is a motorcycle which is a saddle type vehicle, and is indicated by an arrow Fr in the drawing.
Indicates the front of it.

The vehicle body 2 of the motorcycle 1 has a cradle type vehicle body frame 3. The body frame 3 is provided with a head pipe 4 at its front part, and a main frame 5 extends from above the head pipe 4 toward the rear lower side. A rear arm bracket 6 extends downward from the rear end of the main frame 5. Also, a down tube 7 extends rearward and downward from a lower portion of the head pipe 4, and a rear end of the down tube 7 and a lower end of the rear arm bracket 6 are connected.

A seat rail 9 extends rearward and upward from the connecting portion between the main frame 5 and the rear arm bracket 6,
The seat rail 9 is supported by the rear arm bracket 6 by a back stay 10.

A front fork 12 is rotatably supported on the head pipe 4. A front wheel 13 is supported on the lower end of the front fork 12, and a handle 14 is attached to the upper end of the front fork 12 as above.

A rear arm 16 is pivotally supported on the rear arm bracket 6 by a pivot shaft 17 so as to be vertically swingable.
A rear wheel 18 is supported on the swinging end of the rear arm 16. A shock absorber 19 is installed between the body frame 3 and the rear arm 16.

An internal combustion engine 21, which is a drive source for driving the motorcycle 1 to travel, is provided. This internal combustion engine 2
Reference numeral 1 has a two-cycle engine 22 supported by the vehicle body frame 3. The engine 22 includes a crankcase 23 and a cylinder 24 protruding from the crankcase 23, and the intake pipe 2 is provided on the rear surface of the cylinder 24.
A vaporizer 26 is connected via 5. Further, an exhaust pipe 28 made of sheet metal is provided which extends from the front surface of the cylinder 24 to the front and then extends to the rear.

In FIG. 2 above, the exhaust pipe 28 is constructed as follows.

That is, the exhaust pipe 28 is connected to the cylinder 2
4, an exhaust pipe 29 having a substantially uniform small diameter, which extends forward and then folds back, a divergent cone 30 extending rearward from the rear end of the exhaust pipe 29 with the diameter gradually increasing, and the divergent cone. An expansion chamber 31 extending rearward with a substantially uniform large diameter from the extended end of 30, a convergent cone 32 extending rearward from the rear end of the expansion chamber 31 while gradually reducing the diameter dimension, and the convergent cone 32 The tail pipe 33 extends rearward from the rear end with a substantially uniform small diameter, and a silencer 34 connected to the rear end of the tail pipe 33.

On the main frame 5, the vaporizer 26 is provided.
A fuel tank 36 for supplying fuel is supported, and a seat 37 is mounted on the seat rail 9. The rider straddling the seat 37 can hold the handle 14.

A power transmission device 39 is connected to the engine 22. An output shaft of the power transmission device 39 and the rear wheel 18 are interlocked by a chain winding mechanism 40.

In FIGS. 1 to 3, a crankshaft 42 is supported by the crankcase 23. On the other hand, the cylinder 24 is composed of a cylinder body 43 protruding from the crankcase 23 toward the front upper side, and a cylinder head 44 attached to the upper end of the cylinder body 43. A piston 45 is vertically slidably fitted in the cylinder body 43.
And the crankshaft 42 are connected by a connecting rod.

The space closed by the piston 45 in the cylinder 24 is a combustion chamber 46.
Is attached to the cylinder head 44.

When the engine 22 is driven, the outside air 49 is sucked into the crankcase 23 together with the fuel supplied from the carburetor 26, and after being pre-compressed there,
It is sucked into the combustion chamber 46 and burned by the ignition of the spark plug 47. The hot gas after combustion is exhausted 50
Is discharged to the outside of the vehicle through the exhaust pipe 28.

The power generated by driving the engine 22 is transmitted to the rear wheels 18 via the crankshaft 42, the power transmission device 39, and the chain winding mechanism 40, so that the motorcycle 1 can travel on the road surface 51.

When the engine 22 is driven, the temperature of the cylinder 24 and the exhaust pipe 28 becomes high, so a cooling device for the internal combustion engine 21 is provided to cool them.

A radiator 53 is attached to the upper portion of the down tube 7. On the other hand, a first jacket 55 for cooling water 54 is formed on the cylinder body 43 and the cylinder head 44 which form the cylinder 24. A cooling water pump 56 that sends the cooling water 54 to the first jacket 55 is provided. This cooling water pump 56
Is composed of a pump case 57 integrally formed with the crankcase 23 and a rotor 58 housed and supported in the pump case 57. The rotor 58 is adapted to interlock with the crankshaft 42. .

The discharge side of the cooling water pump 56 is connected to the lower end of the first jacket 55 through a first water passage 60 formed in the crankcase 23. The upper end of the first jacket 55 is connected to the upper end of the radiator 53 through a flexible second water passage 61. Further, the lower end portion of the radiator 53 is connected to the suction side of the cooling water pump 56 through the flexible third water passage 62.

A first flow rate adjusting means 63, which is a thermostat, is provided on the upstream end side of the second water passage 61.

When the engine 22 is driven, the cooling water pump 56 is interlocked with the crankshaft 42 as described above.
The cooling water 5 discharged from the discharge side of the cooling water pump 56
4 is the first jacket 55, the first flow rate adjusting means 63, the second
The cooling water pump 56 is sucked into the cooling water pump 56 through the water passage 61, the radiator 53, and the third water passage 62 in this order.

Then, the cylinder 24 is cooled by the cooling water 54 passing through the first jacket 55, and the cooling water 54 to which heat is applied is cooled by traveling wind in the radiator 53 and returned to the cooling water pump 56. .

In the above case, as the temperature of the cooling water 54 passing through the first flow rate adjusting means 63 decreases (or increases), the flow rate of the cooling water 54 passing through the first flow rate adjusting means 63 decreases (or increases). ) To operate.

Exhaust pipe 29 of the exhaust pipe 28
And the divergent cone 30 has an outer cylinder 65 made of sheet metal.
Is fitted and fixed almost coaxially. As a result, a second jacket 66 having an annular cross section is formed between the exhaust pipe 29 and the divergent cone 30 and the outer cylinder 65, and the cooling water 54 can flow through the second jacket 66. .

An intermediate portion of the first water passage 60 is connected to the one end side 66a of the second jacket 66 located on the upstream end side of the exhaust pipe 28 through the flexible fourth water passage 67. That is, the discharge side of the cooling water pump 56 is connected to the one end side 66 a of the second jacket 66 through the first water passage 60 and the fourth water passage 67.

The other end side 6 of the second jacket 66
6b is connected to the upper end of the radiator 53 through a flexible fifth water passage 68. In this case, the exhaust 50 flowing through the exhaust pipe 28 and the cooling water 54 flowing through the second jacket 66 are in the same direction. ing. The second flow rate adjusting means 6 which is a thermostat is provided on the upstream end side of the fifth water passage 68.
9 is provided.

As described above, when the engine 22 is driven and the cooling water pump 56 is interlocked with the engine 22, a part of the cooling water 54 discharged from the cooling water pump 56 is part of the first water passage 60 and the fourth water passage 60. It is sucked into the suction side of the cooling water pump 56 through the water passage 67, the second jacket 66, the second flow rate adjusting means 69, the fifth water passage 68, the radiator 53, and the third water passage 62 in order.

The cooling water 54 passing through the second jacket 66 cools the exhaust pipe 28 and the exhaust 50 in the exhaust pipe 28. Further, the cooling water 54 to which heat is applied by this is cooled by traveling wind in the radiator 53, returned to the cooling water pump 56, discharged again from here, and the above cooling is repeated.

In the second flow rate adjusting means 69, the lower (or higher) the temperature of the cooling water 54 passing therethrough is, the smaller (or higher) the flow rate of the cooling water 54 passing through the second flow rate adjusting means 69 is. Operate.

According to the above embodiment, the first jacket 55
The second jacket 66 and the second jacket 66 are connected in parallel to the cooling water pump 56. Then, the lower (or higher) the temperature of the cooling water 54 flowing through the second and fifth water passages 61 and 68 is by the first and second flow rate adjusting means 63 and 69,
The flow rate of the cooling water 54 is set to be small (or large).

Therefore, if the temperature around the cylinder 24 and the exhaust pipe 28 extending from the cylinder 24 becomes low (or high), the temperature of the cooling water 54 becomes low (or high) accordingly. Then, as the temperature of the cooling water 54 becomes lower (or higher), the flow rate of the cooling water 54 passing through the second and fifth water passages 61 and 68 is adjusted by the first and second flow rate adjusting means 63 and 69. Be reduced (or increased).

Accordingly, the cooling of the exhaust pipe 28 by the cooling water 54 is suppressed (or accelerated), and the supercooling (or insufficient cooling) of the exhaust 50 in the exhaust pipe 28 is suppressed.

As a result of the above, even if the temperature around the cylinder 24 and the exhaust pipe 28 extending from the cylinder 24 changes so as to become low (or high), it is not affected by this change and the exhaust 50 in the exhaust pipe 28 is not affected. A certain temperature is ensured.

Further, since the cooling water 54 flows through the second jacket 66 provided in the exhaust pipe 28, the exhaust 50 in the exhaust pipe 28 is cooled more than before.

Therefore, the return timing of the reflected wave of the exhaust pulsation tends to be delayed as a whole, so that the corresponding pipe length is shortened by that amount, that is, the pipe length of the exhaust pipe 28 is shortened, and the internal combustion engine 21 is shortened. The configuration is simple.

Further, when the cylinder 24 is not sufficiently warmed up, such as during warm-up operation, the engine 22 is normally in the low and medium rotation range. In such a case, according to the above-described embodiment, since the exhaust pipe 28 is cooled by the cooling water 54 more than before, the temperature of the exhaust 50 is lowered, and thus the reflected wave of the exhaust pulsation is generated. Of the internal combustion engine 2 in the above-mentioned low and medium rotation range tends to be delayed.
In accordance with the operating condition of No. 1, the reflected wave is returned in a timely manner, so that the engine performance is improved.

Further, as the cooling water 54 flows through the first jacket 55, the cooling water 54 is given heat from the exhaust 50, so that the cooling water 54 is supplied to the first jacket 55.
Flowing through the cylinder 24 shortens the warm-up time of the cylinder 24.

Although the above is based on the illustrated example, the first flow rate adjusting means 63 may be omitted. In this case, for example, if the flow rate of the cooling water 54 increases (or decreases) by the second flow rate adjusting unit 69, the flow rate of the cooling water 54 flowing through the first jacket 55 decreases (or increases) accordingly. Become. Therefore, the temperature of the cylinder 24 is raised (or lowered) to some extent, while conversely, the exhaust gas 50 in the exhaust pipe 28 is sufficiently cooled (or the cooling is suppressed) to a predetermined temperature. The Rukoto. Further, since the first flow rate adjusting means 63 is not provided, the structure of the internal combustion engine 21 is simplified.

Further, the outer cylinder 65 may be elongated and the second jacket 66 may be provided so as to extend over almost the entire area from the exhaust pipe 29 of the exhaust pipe 28 to the expansion chamber 31 and the convergent cone 32. With this configuration, the exhaust sound is more effectively attenuated by the cooling water 54 in the second jacket 66. In addition, the exhaust pipe 28 can be reinforced and protected more effectively.

Further, the vehicle may be an automobile or a ship, and the object driven by the internal combustion engine 21 may be an industrial machine or the like. Further, the internal combustion engine 21 may be a 4-cycle engine.

(Example 2)

FIG. 4 shows the second embodiment.

According to this, the second flow rate adjusting means 69 is constructed as follows.

That is, a temperature sensor 71 for detecting the temperature of the cooling water 54 is provided on the upstream end side of the fifth water passage 68. Further, in the vicinity of the downstream side of the temperature sensor 71, a butterfly type on-off valve 7 for opening and closing the fifth water passage 68.
2 is provided, and an electromagnetic actuator 73 that adjusts the opening degree of the opening / closing valve 72 is provided.

The temperature sensor 71 and the actuator 73
Are both electrically connected to an electronic control unit 74. When the temperature of the cooling water 54 is low (or high) based on the detection signal of the temperature sensor 71, the controller 74
If it is determined by the above, the control device 74 operates the actuator 73 to cause the opening / closing valve 72 to close (or open) the fifth water passage 68 to a greater extent, whereby the cooling water 54 is discharged. The flow rate is adjusted.

According to this embodiment, the control device 74 can easily and accurately adjust the set temperature which is the basis of the opening / closing operation of the opening / closing valve 72, and therefore the degree of freedom in adjusting the flow rate of the cooling water 54 can be improved. Is improved, and this adjustment can be performed more accurately.

Further, the control device 74 includes the engine 22.
The rotational speed, the temperature of the cylinder 24, and the throttle opening degree of the carburetor 26 are input, and the opening degree is adjusted by the opening / closing valve 72 via the actuator 73.

In this case, for example, during acceleration,
Although the throttle opening of the carburetor 26 becomes large, the rotation speed of the engine 22 is not so large and the temperature of the exhaust 50 is not so high. Therefore, the opening degree by the opening / closing valve 72 is made smaller by the control device 74, and the cooling water 5
The flow rate of No. 4 is further reduced and the cooling of the exhaust pipe 28 is suppressed. Further, as the rotation of the engine 22 increases, the opening degree of the open / close valve 72 is increased, and the cooling of the exhaust pipe 28 is promoted.

Since other structures and operations are almost the same as those of the first embodiment, the same reference numerals are given to the drawings and the description thereof will be omitted.

(Example 3)

FIG. 5 shows the third embodiment.

According to this, the middle portion of the first water passage 60 passes through the fourth water passage 67 and the other end side 6 of the second jacket 66.
6b, that is, the discharge side of the cooling water pump 56 is connected to the other end side 66b of the second jacket 66 through the first water passage 60 and the fourth water passage 67.

Further, one end side 6 of the second jacket 66
6a is connected to the upper end of the radiator 53 through the fifth water passage 68.

Therefore, the exhaust gas 5 flowing through the exhaust pipe 28
0 and the cooling water 54 flowing through the second jacket 66 are in opposite directions.

According to this embodiment, the internal combustion engine 21 is cooled almost uniformly as a whole, and uneven cooling is prevented.

Since other structures and operations are the same as those of the first embodiment, common reference numerals are given to the drawings, and description thereof will be omitted.

(Example 4)

FIG. 6 shows the fourth embodiment.

According to this, the midway portion of the second water passage 61 passes through the fourth water passage 67 and the one end side 6 of the second jacket 66.
6a, that is, the one end side 66a of the second jacket 66, the fourth water passage 67, the second water passage 61, the first flow rate adjusting means 63, the first jacket 55, and the first water passage 6 are connected.
The discharge side of the cooling water pump 56 is connected through 0.

An electromagnetic valve 75 is provided downstream of the middle portion of the second water passage 61, and the electromagnetic valve 75 is electrically connected to the control device 74.

Further, the first flow rate adjusting means 6 is provided in the middle of the third water passage 62 on the suction side of the cooling water pump 56.
A sixth water passage 76 for connecting the three is provided.

When the temperature of the cylinder 24 is low (or high), the operation of the first flow rate adjusting means 63 causes the cooling water to be short-circuited back to the cooling water pump 56 through the sixth water passage 76. The flow rate of 54 increases (or decreases), the flow rate of the cooling water 54 flowing through the second water passage 61 toward the radiator 53 decreases (or increases), and the cylinder 24 is overcooled (or undercooled). ) Is prevented.

When the temperature of the cylinder 24 becomes sufficiently high as in the normal operation, the operation of the first flow rate adjusting means 63 causes the cooling water pump 56 to short-circuit through the sixth water passage 76. The flow rate of the returned cooling water 54 is substantially zero.

The radiator 53 and the second jacket 66.
The flow rate ratios of the cooling water 54 flowing through and are automatically adjusted by adjusting the opening degree of the solenoid valve 75 based on the control of the control device 74.

For example, when the opening / closing valve 72 is set to a predetermined opening (for example, a middle opening or fully open), the temperature sensor 7
If the temperature (t) detected by _{No. 1} is lower than the minimum temperature (t ₁ ) set by the controller 74, the solenoid valve 7 is controlled by the controller 74 which inputs the temperature detected by the temperature sensor 71.
The opening degree of 5 is increased. Then, the cooling water 54 flows more toward the radiator 53 side, and the second jacket 6
6, the flow rate of the cooling water 54 decreases, and the exhaust pipe 28
Overcooling is prevented. On the other hand, if the detected temperature (t) is higher than the maximum temperature (t ₂ ) set by the control device 74, the control device 74, which inputs the detected temperature of the temperature sensor 71, controls the opening of the solenoid valve 75. Is reduced. Then, more cooling water 5 is supplied to the second jacket 66.
4 flows to prevent insufficient cooling of the exhaust pipe 28.

That is, in addition to the operation of the second flow rate adjusting means 69, t ₁ <t <by adjusting the opening / closing of the solenoid valve 75.
The relationship of t ₂ is always maintained.

Although the above is based on the illustrated example, the second jacket 66 is first connected to the discharge side of the cooling water pump 56,
The first jacket 55 may be connected to the second jacket 66 to cause the cooling water 54 to flow in the opposite direction.

In this way, the cooling of the exhaust pipe 28 becomes more effective.

Further, for example, when the electromagnetic valve 75 is set to a predetermined opening (for example, an intermediate opening or fully open), the control device 74 which inputs the temperature detected by the temperature sensor 71 controls the opening / closing valve 72, The relationship of t ₁ <t <t ₂ may be always maintained.

Further, one of the on-off valve 72 and the electromagnetic valve 75 may be a throttle having a fixed opening.

Since other structures and operations are the same as those in the second embodiment, the same reference numerals are given to the drawings and the description thereof will be omitted.

[0094]

According to the present invention, the flow rate adjusting means increases the flow rate of the cooling water as the temperature of the cooling water flowing through any of the water passages increases.

Therefore, if the temperature around the cylinder and the exhaust pipe extending from this cylinder becomes low (or high), and the temperature of the cooling water becomes low (or high) accordingly, this cooling As the water temperature becomes lower (or higher), the flow rate adjusting means reduces (or increases) the flow rate of the cooling water passing through the water passage.

Therefore, the cooling of the exhaust pipe by the cooling water is suppressed (or accelerated), and the supercooling (or insufficient cooling) of the exhaust gas in the exhaust pipe is suppressed.

As a result of the above, even if the temperature around the cylinder or the exhaust pipe extending from this cylinder changes to be low (or high), it is not affected by this change,
Since a predetermined temperature is secured for the exhaust gas in the exhaust pipe, the reflected wave of the exhaust pulsation returns in good timing so as to match the operating condition of the internal combustion engine at that time, and this exhaust pulsation is effective. Utilized to achieve improved engine performance.

Further, since the cooling water flows through the second jacket (jacket) provided in the exhaust pipe, the exhaust gas in the exhaust pipe is cooled more than the conventional one.

Therefore, the return timing of the reflected wave of the exhaust pulsation tends to be delayed as a whole, so that the equivalent pipe length can be shortened by that much, that is, the pipe length of the exhaust pipe can be shortened and the internal combustion engine The configuration can be simplified.

Further, when the cylinder is not sufficiently warmed up, such as during warm-up operation, the engine is usually in the low and medium speed range. In such a case, according to the above configuration, since the exhaust pipe is cooled by the cooling water more than before, the temperature of the exhaust gas is lowered, and thus the return of the reflected wave of the exhaust pulsation is delayed. This tends to match the operating conditions of the internal combustion engine in the low and medium speed ranges, thus improving the engine performance.

Further, when the cooling water flows through the jacket, the cooling water gives heat from the exhaust gas. Therefore, when the cooling water flows through the jacket of the cylinder, the warm-up time of the cylinder is shortened. Therefore, there is also an advantage that the time from starting to normal driving can be shortened.

[Brief description of drawings]

1 is an enlarged side partial cross-sectional view on the right side of that shown in FIG. 2 in Embodiment 1. FIG.

FIG. 2 is an overall side view of the left side of the motorcycle according to the first embodiment.

FIG. 3 is a simplified diagram of what is shown in FIG. 1 in the first embodiment.

FIG. 4 is a diagram corresponding to a part of FIG. 1 in the second embodiment.

FIG. 5 is a diagram corresponding to FIG. 3 in the third embodiment.

FIG. 6 is a diagram corresponding to FIG. 3 in the fourth embodiment.

[Explanation of symbols]

 21 Internal Combustion Engine 22 Engine 24 Cylinder 26 Vaporizer 28 Exhaust Pipe 50 Exhaust 53 Radiator 54 Cooling Water 55 First Jacket (Jacket) 56 Cooling Water Pump 60 First Water Passage 61 Second Water Passage 62 Third Water Passage 63 First Flow Rate Adjusting means 66 Second jacket (jacket) 67 Fourth water passage 68 Fifth water passage 69 Second flow rate adjusting means

Claims (3)

[Claims] 1. A jacket for cooling water is provided on an exhaust pipe extending from a cylinder, and a water passage is connected to one end of the jacket to connect a discharge side of a cooling water pump to the other end of the same jacket. A cooling device for an internal combustion engine, which is connected to the suction side of a cooling water pump through the above, and which is provided with flow rate adjusting means for increasing the flow rate of the cooling water as the temperature of the cooling water flowing through at least one of the water passages increases. . 2. A first jacket for cooling water is provided on the cylinder, and the discharge side of the cooling water pump is connected to one end side of the first jacket through a water passage, while the other end side of the first jacket is connected to the other side. A cooling water pump is connected to the suction side of the same cooling water pump through a water passage, and a second jacket for cooling water is provided on the exhaust pipe extending from the cylinder. Water passages that connect the discharge side of the pump and the other end of the second jacket to the suction side of the same cooling water pump through another water passage to connect the first jacket and the cooling water pump. A cooling device for an internal combustion engine, which is provided with flow rate adjusting means for increasing the flow rate of the cooling water as the temperature of the cooling water flowing through at least one of the above increases. 3. A first jacket for cooling water is provided on the cylinder, a second jacket for cooling water is provided on an exhaust pipe extending from the cylinder, and the first jacket and the second jacket are connected to each other by a water passage, The discharge side of the cooling water pump is connected to one of the first jacket and the second jacket through another water passage, and the other jacket is further connected to the suction side of the cooling water pump through another water passage. A cooling device for an internal combustion engine, which is provided with flow rate adjusting means for increasing the flow rate of the cooling water connected to each other and increasing the temperature of the cooling water flowing through at least one of the water passages.