JPH0771250A - Cooling device for engine - Google Patents

Abstract

PURPOSE:To decrease a temperature of exhaust gas and reduce expansion noises by laterally dislocating a cooling fan from a center axis of a cylinder, passing a part of cooling wind through a lateral space of an engine main body, and blowing it to a front side of an exhaust muffler. CONSTITUTION:A water pump input pulley 16 provided with a cooling fan 2 is arranged on a top portion 57 on a right side of a belt case 14. A turning center of the cooling fan 2 is dislocated rightward from a center axis 3 of a cylinder viewing from a front side of an engine main body 1. An exhaust muffler 7 is arranged in a lateral space 6 of the engine main body 1. A part of a front side of the exhaust muffler 7 is faced to a part of a turning range 5 of the cooling fan 2 from the rear side. A temperature of exhaust gas passing the exhaust muffler 7 is decreased by cooling wind generated by the cooling fan 2. The exhaust gas is discharged from the exhaust muffler 7 with a comparatively low pressure, so that expansion noises are reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine cooling device, and more particularly to a cooling device capable of effectively cooling an exhaust muffler with cooling air blown from a cooling fan.

[0002]

2. Description of the Related Art FIG. 6 shows a conventional art of an engine cooling device.
There is one shown in. Like the present invention, it has the following basic structure. That is, the engine body 101
A cooling fan 102 is disposed on the front side of the cooling fan 102, and cooling air is blown backward from the cooling fan 102 toward the engine body 101.

With such a basic structure, the cooling air blows against the engine body 101 and can be air-cooled.

By the way, in this prior art, the swirl center 104 of the cooling fan 102 is arranged at a position substantially coincident with the cylinder center axis 103 when viewed from the front side of the engine body 101, and substantially the entire swirl region 105 of the cooling fan 102 is arranged. Faces the front side of the engine body 101. Therefore, when viewed from the front side of the engine body 101, the exhaust muffler 1
07 is disposed at a position outside the swirl area 105 of the cooling fan 102.

[0005]

In the above-mentioned conventional technique, the cooling air blown from the cooling fan 102 blows against the front side of the engine body 101, and the cooling air is hardly supplied to the exhaust muffler 107. Therefore, the exhaust muffler 1
The temperature of the exhaust gas passing through the inside of 07 is not sufficiently lowered, and this exhaust gas is emitted from the exhaust muffler 107 with a relatively high pressure, and a large expansion noise is generated.

An object of the present invention is to provide an engine cooling device capable of effectively cooling an exhaust muffler with cooling air blown from a cooling fan.

[0007]

According to the present invention, as illustrated in FIG. 1, a cooling fan 2 is arranged on the front side of an engine body 1, and cooling air is directed rearward from the cooling fan 2 toward the engine body 1. An engine cooling device configured to blow air is characterized by the following.

That is, when viewed from the front side of the engine body 1, the swirl center 4 of the cooling fan 2 is arranged at a position laterally deviated from the cylinder center axis 3 and a part of the swirl region 5 of the cooling fan 2 is arranged. The front side is exposed to the lateral side space 6 of the engine body 1, the exhaust muffler 7 is arranged in the lateral side space 6 of the engine body 1, and a part or all of the front side portion of the exhaust muffler 6 is cooled. It is characterized in that a part of the swirling area 5 of the fan 2 is opposed from the rear side.

[0009]

According to the present invention, as illustrated in FIG. 1, a part of the cooling air blown from the cooling fan 2 passes through the lateral side space 6 of the engine body 1 and is exhausted. The part of the front side of the muffler 7 is sprayed or part of it. Therefore, the temperature of the exhaust gas passing through the exhaust muffler 7 is sufficiently lowered, the exhaust gas is released from the exhaust muffler 7 at a relatively low pressure, and the expansion noise is reduced.

[0010]

Embodiments of the present invention will be described with reference to the drawings.
1 to 4 are views for explaining an overhead cam type water-cooled two-cylinder gasoline engine according to a first embodiment of the present invention. As shown in FIG. 3, the structure of the engine body 1 is as follows. That is, the cylinder head 8 is attached to the upper portion of the cylinder block 11, and the head cover 12 is attached to the upper portion thereof.
Is assembled, and the gear case 13 and the belt case 14 are assembled to the front portion of the cylinder block 11.
As shown in FIG. 1, in the belt case 14, a crank pulley 15, a water pump input pulley 16, a valve operating camshaft input pulley 17, and a tension pulley 18 are arranged, and an interlocking belt 19 is wound around them. .

An air cleaner 20 and an exhaust muffler 7 are separately arranged on the left and right of a cylinder head 8 constituting the engine body 1. As shown in FIG. 2 or 3, an ignition coil 21 and an igniter 22 are attached to the rear portion of the cylinder head 8. A rear end plate 23 is attached to the rear portion of the cylinder block 11, and a flywheel 25 connected to the crankshaft is arranged on the rear side thereof. A ring gear 26 is externally fitted and fixed to the flywheel 25, and as shown in FIG. 2, a starter motor 27 is supported on the right side of the rear end plate 23. Then, the pinion gear 2 of the starter motor 27
8 is meshed with the ring gear 26.

The structure of the intake system of this engine is as follows. That is, as shown in FIG. 4, two intake ports 35 are provided near the center of the cylinder head 8. These are formed in a V-shaped branch structure in which the respective base end portions are joined, and a single intake port inlet 36 is formed in the joint portion 52, and the air-fuel mixture outlet 37 of the carburetor 54 is formed through the insulator 56. Connected. The mixture outlet 37 may be directly connected to the intake port inlet 36. The carburetor inlet 38 communicates with the air cleaner 20. With such a configuration, the air-fuel mixture supplied from the air-fuel mixture outlet 37 of the carburetor 54 is merged with the merging portion 5
Since it is distributed to each intake port 35 via 2, the intake manifold becomes unnecessary with a complicated branch pipe structure.

As shown in FIG. 1, the exhaust system for this engine is provided with two exhaust ports 58, 58 near the front and rear ends of the cylinder head 8, and the exhaust port outlets 59, 59 are provided at the exhaust muffler 7. And is connected to the first expansion chamber 60.

The structure of the exhaust muffler 7 is as follows. That is, the case 39, which is long in the front-rear direction, has a shield plate 40 in the center.
And a perforated plate 41 near the rear end, and in order from the front side,
The first expansion chamber 60, the second expansion chamber 42, and the third expansion chamber 43 are partitioned and formed. Further, the exhaust outlet pipe 4 penetrating from the rear end of the case 39 to both central portions of the perforated plate 41 and the shield plate 40.
4 is inserted, the front end opening 45 faces the first expansion chamber 60, the rear end opening 46 is opened to the atmosphere, and a roll-shaped wire net 47 that suppresses intake of outside air is internally provided at the rear end. ing. A large number of gas permeation holes 48 are formed in the exhaust outlet pipe 44, and these gas permeation holes 48 face the inside of the second expansion chamber 42 and the inside of the third expansion chamber 43. The inside of the exhaust outlet pipe 44 is partitioned by a plug 49 provided at the same position in the front-rear direction as the porous plate 41. In the second expansion chamber 42, a cylindrical wall 51 having a large number of gas permeation holes 50 is internally provided concentrically with the exhaust outlet pipe 44.

In the exhaust device provided with this exhaust muffler 7,
As shown by the arrows in FIG. 4, the high-temperature and high-pressure exhaust gas flowing out from each exhaust port 58 is introduced into the first expansion chamber 60 and sequentially passed through the second expansion chamber 42 and the third expansion chamber 43. The pressure is reduced with and then released into the atmosphere to reduce the expansion noise of the exhaust.

The structure of the water cooling system for this engine is as follows. That is, as shown in FIG. 1, the cooling fan 2 is attached to the water pump input pulley 16, and the radiator 30 is arranged in front of it. Belt case 1
4 is formed in a triangular shape when viewed from the front, and one apex portion 57 on the right side thereof is projected to the lateral side of the cylinder head 8 and the cylinder block 11, and as shown in FIG. A water inlet case 31 is attached and communicates with a cylinder jacket (not shown) in the cylinder block 11. Further, a cooling water outlet case 32 is attached to the cylinder head 8 in the gap between the cylinder head 8 and the belt case 14, and this is the head jacket 3 shown in FIG.
It communicates with 3. The head jacket 33 and the cylinder jacket communicate with each other through a water passage 34.

In this water cooling device, while the engine is operating, the cooling water circulates in the order of the cylinder jacket, the head jacket 33 and the radiator 30 by driving the water pump, and the cooling air passes through the radiator 30 by driving the cooling fan 2. , Cool the engine with water. Further, the cooling air that has passed through the radiator 30 is sent backward from the cooling fan 2,
It hits the front side of the engine body 1.

In this embodiment, the following measures are taken in order to effectively cool the exhaust muffler 7 with the cooling air blown from the cooling fan 2. That is, as shown in FIG. 1, the water pump input pulley 16 provided with the cooling fan 2 is arranged at the one vertex portion 57 on the right side of the belt case 14, and when viewed from the front side of the engine body 1, the cylinder center axis 3 The swivel center 4 of the cooling fan 2 is arranged at a position deviated to the right side from. A part of the swirling area 5 of the cooling fan 2 faces the lateral side space 6 of the engine body 1 from the front side thereof. An exhaust muffler 7 is arranged in the lateral side space 6 of the engine body 1, and a part of the front side of the exhaust muffler 7 faces a part of the swirl region 5 of the cooling fan 2 from the rear side. . The entire front side portion of the exhaust muffler 7 may be opposed to a part of the swirl region 5 of the cooling fan 2.

With such a structure, the cooling air generated by the cooling fan 2 blows against the front side of the exhaust muffler 7 and cools it by air. Therefore, the temperature of the exhaust gas passing through the exhaust muffler 7 is sufficiently lowered, the exhaust gas is discharged from the exhaust muffler 7 at a relatively low pressure, and the expansion noise is reduced.

In this embodiment, in order to make the front side of the exhaust muffler 7 face a part of the rotating region 5 of the cooling fan 2, the following constitution is adopted. That is, as shown in FIG. 4, the exhaust muffler 7 is provided with two exhaust introduction pipes 61, 61 of the same number as the exhaust ports 58, 58, and these two exhaust introduction pipes 61, 61 are the first exhaust muffler 7 of the exhaust muffler 7. It is inserted and fixed in one expansion chamber 60, and the respective exhaust introduction pipe outlets 62, 62 individually face the first expansion chamber 60 of the exhaust muffler 7. Further, the two exhaust introduction pipe inlets 63, 63 are individually connected to the two exhaust port outlets 59, 59.

With such a construction, the exhaust gas flowing out from the two exhaust ports 58, 58 individually passes through the two exhaust introduction pipes 61, 61, and the exhaust muffler 7 has a wide area. Since it joins in the first expansion chamber 60, the exhaust manifold is not required, and the exhaust muffler 7 is connected to the cylinder head 8
1 and the front end of the exhaust muffler 7 can be
It can be opposed to the rotating area 5 of the cooling fan 2 shown in FIG. Further, according to such a configuration, the heat of the exhaust gas is dispersed throughout the first expansion chamber 60, and the heat damage to the exhaust path due to the heat collection of the exhaust gas is reduced.

Next, a second embodiment of the present invention will be described. As shown in FIG. 5, this second embodiment is constructed as follows. That is, in the first embodiment described above, FIG.
As shown in FIG. 5, the swirl center 4 of the cooling fan 2 is arranged at a position deviated to the right side from the center line 29 of the radiator 30 as viewed from the front side of the engine body 1. With this state, especially, the ventilation amount on the left side of the radiator 30 is Considered to be few. For this reason, in the second embodiment, as shown in FIG. 5, a fan shroud 53 having a diameter gradually reduced from the peripheral wall of the radiator 30 toward the cooling fan 2 is provided. For this reason,
The suction force of the cooling fan 2 acts on the entire surface of the radiator 30, the air flow amount on the entire surface of the radiator 30 becomes more uniform, and the cooling efficiency thereof increases. The other structure is configured similarly to the first embodiment.

The contents of the respective embodiments of the present invention are as described above, but the present invention is not limited to the contents of the respective embodiments. For example, although the above-described embodiments have been described with respect to an overhead cam type water-cooled two-cylinder gasoline engine, the present invention can be applied to any engine having a cooling fan. Therefore, it can be applied to liquid-cooled engines and air-cooled engines other than water-cooled engines. Also, not limited to gasoline engines,
It can also be applied to gas engines and diesel engines. Further, it can be applied to a multi-cylinder engine having two or more cylinders or a single-cylinder engine. It can also be applied to an overhead valve engine.

[Brief description of drawings]

FIG. 1 is a front view of an engine according to a first embodiment of the present invention, in which a front portion of a belt case is removed.

2 is a plan view of the engine of FIG. 1. FIG.

3 is a side view of the engine of FIG. 1. FIG.

4 is a cross-sectional plan view of the vicinity of the cylinder head of the engine of FIG.

FIG. 5 is a plan view of an engine according to a second embodiment of the present invention.

FIG. 6 is a front view of an engine according to a conventional technique.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine main body, 2 ... Cooling fan, 3 ... Cylinder center axis line, 4 ... Turning center, 5 ... Turning area, 6 ... Lateral lateral space,
7 ... Exhaust muffler

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Naoki Inoue 64 Ishizukitamachi, Sakai City, Osaka Prefecture Kubota Sakai Co., Ltd.

Claims (1)

[Claims] 1. A cooling fan on the front side of the engine body (1).
(2) is arranged, and from this cooling fan (2) the engine body
In an engine cooling device configured to blow cooling air backward toward (1), when viewed from the front side of the engine body (1), the cylinder center axis line
The swirl center (4) of the cooling fan (2) is arranged at a position laterally deviated from (3), and a part of the swirl region (5) of the cooling fan (2) is placed laterally of the engine body (1). The exhaust space muffler (7) is arranged in the lateral space (6) of the engine body (1) by facing the side space (6) from the front side, and a part of the front side part of the exhaust muffler (6) is arranged. Alternatively, the cooling device for the engine is characterized in that a part of the swirl region (5) of the cooling fan (2) is opposed to the whole from the rear side.