JP3330019B2 - Engine exhaust purification device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine for a motorcycle or the like, in which secondary air is supplied to an exhaust system of the engine to promote combustion of unburned harmful components in exhaust gas flowing therethrough. The present invention relates to an exhaust gas purifying apparatus.

[0002]

2. Description of the Related Art Generally, a secondary air supply system is connected to an exhaust system as an exhaust gas purifying device of an engine for a motorcycle or the like, and a reed valve is interposed in the secondary air supply system. It is well known that the reed valve is opened in response to the exhaust pulsation pressure generated in the exhaust system by operation to supply secondary air for exhaust purification to the exhaust system ( See Japanese Utility Model Publication No. 55-53693.

[0003]

In the exhaust gas purifying apparatus, a secondary air passage downstream of the reed valve of the secondary air supply system is provided with a secondary air distribution passage for introducing secondary air into the exhaust system. In addition to this, the exhaust pulsating pressure in the exhaust system is transmitted to the reed valve and is also an exhaust introduction passage for opening the reed valve. Backflow into the secondary air passage reaches the reed valve, which heats the reed valve and exposes the reed valve body, its seat rubber, and other components to high temperatures. There is a problem in durability,
There is also a problem that foreign matter such as carbon may be deposited on the open / close end of the reed valve.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a novel engine exhaust gas purifying apparatus which solves all of the above problems and has excellent reliability and durability. is there.

[0005]

According to the first aspect of the present invention, a reed valve chamber having a reed valve is provided in a cylinder head of an engine body, and the reed valve chamber is provided upstream of the reed valve chamber. The chamber communicates with a secondary air introduction passage communicating with the atmosphere, and the downstream chamber communicates with an exhaust port of the engine via a secondary air distribution passage, and the reed valve is driven by exhaust pulsation pressure generated by operation of the engine. In the exhaust gas purifying apparatus for an engine in which secondary air is introduced into an exhaust port by opening a valve, a ventilating heat shielding means is provided in a downstream chamber of the reed valve chamber, and the exhaust gas is heated by heating the heat shielding means.
The exhaust gas is provided so as to conduct heat to the cylinder head, and the exhaust gas flowing backward from the exhaust port to the downstream chamber of the reed valve chamber is
After passing through the thermal barrier means of the breathable downstream chamber is characterized in that as Charles electrically to the lead valve.

[0006] According to the second aspect of the invention, claim
In addition to one of the feature, the closing open ends of the reed valve body before Symbol reed valve, is characterized in that so as to open in a direction to follow the flow of the exhaust gas flowing back to the reed valve chamber from the exhaust port.

According to the third aspect of the present invention,
In addition to the above features, the heat shielding means may be made of an Al plate.
It is characterized by that.

[0008] According to the invention of claim 4, according to the invention,
In addition to one of the feature, the shield Netsute stage, a large number of vent holes
It is characterized by including a punch plate with an opening
You.

According to the fifth aspect of the present invention,
In addition to the above features, the heat shielding means may include a number of ventilation holes.
A rectangular substrate consisting of a punch plate with a hole
Upright at substantially right angles from both sides of the board in the width direction.
Left and right gap holding pieces and one edge of the board in the longitudinal direction
It is formed integrally with the engaging tongue that stands up at a substantially right angle.
It is characterized by being.

[0010] According to the invention of claim 6, according to the invention,
In addition to the above features, the upper part of the cylinder head
On the upper surface of the upper wall of the cylinder head cover
A bottom wall of the valve chamber is formed, and the upper surface of the bottom wall faces upward.
A seat is protruded integrally, and the heat shielding means is mounted on the seat.
It is characterized by being placed and supported.

According to the seventh aspect of the present invention,
In addition to the above features, the heat shielding means may include the reed valve.
Of the reed valve engaged with the downstream wall of the chamber.
It is characterized in that the surface is covered from below.

[0012]

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

First, an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a longitudinal sectional view of the head of the engine, and FIG.
Is an enlarged view of a main part of FIG. 1, FIG. 3 is a longitudinal sectional view taken along line 3-3 in FIG. 2, FIG. 4 is a transverse sectional view taken along line 4-4 in FIG. 2, and FIG. 6. Partially broken cross-sectional view along line 5-5 of FIG.
FIG. 3 is a perspective view of a heat shield plate.

In FIGS. 1 and 2, a DOHC for a motorcycle is shown.
An engine body E of a four-stroke cycle engine includes a cylinder block 1 and a cylinder head 2 integrally connected to a deck surface of the engine by a gasket 3. An intake port 6 communicating with the combustion chamber 5 is provided on the other side.
Is formed in a uniflow type. The intake port 6 has a carburetor (not shown),
An intake system In such as an air cleaner is connected thereto, and an exhaust system Ex such as an exhaust pipe and a muffler (not shown) is connected to the exhaust port 7. The cylinder head 2 is provided with intake and exhaust valves 8 and 9 for opening and closing the intake and exhaust ports 6 and 7 at the opening ends on the combustion chamber 5 side in the usual manner. 11, a valve train 12,
The opening / closing operation is performed in cooperation with the control unit 13. In this embodiment it Thus, since DOHC Shikidoben mechanism is employed, intake, exhaust valves 8 and 9, intake camshaft 14, 15 thereon, it is directly driven by the exhaust cam 14 _1, 15 ₁ You.

A packing 16 is provided above the cylinder head 2.
, The cylinder head cover 17 is integrally connected. Above the exhaust camshaft 15, a reed valve cover 18
Are fixed by two bolts 19, and a reed valve chamber C is formed by the cylinder head cover 17 and the reed valve cover 18, and an exhaust pulsation pressure responsive reed valve described in detail later in the reed valve chamber C. R is housed and held. A secondary air inlet 20 is opened in the upper wall of the reed valve cover 18, and a secondary air introduction passage 21 is connected to the inlet 20, and the secondary air introduction passage 21 is connected via an air control valve 22. To the intake system In. The air control valve 22 is conventionally known and is normally closed.
During operation of the engine, the valve is opened in response to the intake negative pressure in the intake system In.

In the cylinder head 2 and the cylinder head cover 17, a secondary air distribution passage 24 extending substantially vertically extends across the cylinder head 2 and the cylinder head cover 17 and communicates with the base of the exhaust port 7 and the reed valve chamber C. Are formed. The secondary air distribution passage 24 includes a downstream passage 24d formed in the cylinder head 2 and an upstream passage 24u formed in the cylinder head cover 17, and these passages 24d,
24u is the cylinder head 2 and the cylinder head cover 1
7 are connected by a hollow cylindrical knock pin 25 provided over the connecting surface with the connecting member 7. Then, the clean secondary air passing through the reed valve R is introduced into the exhaust port 7 through the secondary air distribution passage 24, and a part of the exhaust gas in the exhaust port 7 is removed from the secondary air distribution passage 24. Through the reed valve chamber C, and the reed valve R is opened by the pulsating pressure of the exhaust gas.

In the reed valve chamber C, a pair of left and right reed valves R, which partition the inside of the chamber C into an upstream chamber Cu above the chamber C and a downstream chamber Cd below the chamber C, are provided side by side. The valve seat 26 of the reed valve R is formed in a rectangular shape by an Al plate or the like, and its outer peripheral edge is surrounded by a heat-resistant seal rubber 27 having a U-shaped cross section. The seat 26 is the cylinder head cover 1
7 and the reed valve cover 18 are clamped and fixed. At the center of each valve seat 26 is a square valve port 2
The upstream chamber Cu and the downstream chamber Cd communicate with each other through the valve port 28. Each valve seat 26
On the lower surface facing the downstream chamber Cd, a lead seat surface 29 made of heat-resistant rubber is superimposed, and the lead seat surface 29 has a flexible lead capable of opening and closing each valve port 28. The valve body 30 is superimposed, and a curved reed stopper 31 for limiting the opening of the reed valve body 30 is further superimposed thereon. The base ends of the reed valve body 30 and the reed stopper 31 are connected to a valve seat. The valve seat 26 is fixedly fastened to the valve seat 26 by a set screw 32 screwed to the same.

By the way, as clearly shown in FIG. 2, the free end or closing open end 30 ₁ that lead valve body 30 of the pair of reed valve R, the opening of the upstream passage 24u of the secondary air distribution passage 24 On the side away from the end, it is opened in a direction to follow the flow of exhaust gas flowing backward through the secondary air distribution passage 24 from the exhaust port 7 and flowing through the reed valve chamber C. Foreign matter, such as carbon, contained therein is difficult to bite.

In the downstream chamber Cd of the reed valve chamber C, there is provided a heat shielding means P for relieving the reed valve R from being overheated by being exposed to high-temperature exhaust gas flowing backward. ing.

In the following, the structure of the heat shield means P will be described. The heat shield plate 34 constituting the main part is made of an Al plate as shown clearly in FIG. Substrate 34 made of punched plate
_1, the width direction both side edges each of which is substantially perpendicular to the upright formed from left and right space maintaining piece 34 _2, and Kakarigoshitahen 34 ₃ which is substantially perpendicular upright from its longitudinal end edges and more, together are formed, the lateral spacing holding pieces 34 _2, its upper edge is formed on the inclined surface s so gradually lowered from one to the other. 2 and 5, a cylinder head cover 1 forming a bottom wall of the reed valve chamber C is formed.
On the upper surface of the upper wall of the 7, an underside of each reed valve R, at one end on the side away from the secondary air distribution passage 24, one receiving seat 35 having an oval cross section is integrally formed to protrude upward. On the side adjacent to the secondary air distribution passage 24, another boss-shaped receiving seat 36 is integrally provided so as to protrude upward and integrally with these receiving seats 3.
On 5,36, the heating plate 34 shield is placed on the right and left distance holding pieces 34 ₂ and Kakarigoshitahen 34 ₃ facing up, and is supported. And the right and left distance holding pieces 34 _2, the heat shield plate 34, the inclined surface s, s of the space is formed, also on those edges for circulating the secondary air between the reed valve R is
The lower surface of the valve seat 26 is abutted. As a result, as shown in FIG.
The reed valve R can have a sufficient valve opening stroke, and the rising end of the heat shield plate 34 can be connected to the head of the set screw 32. , So that even if the set screw 32 is loosened, it will not fall off. The engagement Goshitahen 34 ₃ also engages the inner wall of the lead valve chamber C, and to regulate the longitudinal position.

In the drawings, reference numerals 38 and 39 denote bearing caps for supporting the intake and exhaust camshafts 14 and 15 rotatably of the cylinder head 2, respectively, and reference numerals 40 and 41.
Is a camshaft guide cover formed integrally with the bearing caps 38, 39.

Next, the operation of the embodiment of the present invention configured as described above will be described.

Now, when the engine is operated, exhaust pulsation pressure is generated in the exhaust port 7, and this exhaust pulsation pressure passes through the secondary air distribution passage 24 and the reed valve chamber C to reach the pair of reed valves R. By opening these valves and further opening the air control valve 22 by operating the engine, clean air from the intake system In is led to the upstream chamber Cu of the reed valve chamber C through the secondary air introduction passage 21 and further to a pair. Reed valve R valve port 28
And flows into the downstream chamber Cd, from which it is introduced into the exhaust port 7 through the secondary air distribution passage 24. The secondary air introduced into the exhaust port 7 enters the exhaust gas in the exhaust system Ex including the exhaust port 7, and oxidizes and purifies unburned harmful components such as HC and CO mixed in the exhaust gas.

The reed valve R is opened and closed by positive and negative pressures due to exhaust pulsation in the exhaust port 7.
At a moment, the high-temperature exhaust gas in the exhaust port 7 flows backward through the secondary air distribution passage 24 to reach the reed valve R as shown by the dotted arrow in FIG. If the conventional one (for example, the above-mentioned Japanese Utility Model Publication No. 55-53693)
In the case where the reed valve is not provided with any heat-insulating means, such as the one described in Japanese Patent Application Laid-Open No. H11-157, the components of the reed valve, especially the heat-sensitive seal rubber and the reed seat surface, are deteriorated, and their functions such as deterioration of the sealing performance are reduced. In addition to causing a decrease in the life of the reed valve itself, there is a possibility that the life of the reed valve itself is shortened. However, in this embodiment, the reed valve is connected to the downstream chamber Cd of the reed valve chamber C which communicates with the secondary air distribution passage 24. By providing a heat-insulating plate 34 having air permeability, the heated exhaust gas can be supplied to the heat-insulating plate 3.
When the gas passes through the reed valve R, the heat is removed, and as a result, the temperature of the exhaust gas reaching the reed valve R can be effectively lowered, and the deterioration of the components of the reed valve R due to heating can be reduced. Its durability can be increased. Further, the exhaust heat that has heated the heat shield plate 34 is quickly transmitted to the cylinder head 2 and does not overheat the heat shield plate 34.

[0025] As shown in FIG. 2, since the opening and closing open end 30 ₁ of the reed valve body 30 of the reed valve R is opened in a direction to follow the flow direction of the backflow exhaust gas flowing through the reed valve chamber C, reed valve R This makes it difficult for foreign substances such as carbon contained in the exhaust to be caught in the opening of the reed valve, ensures the correct opening and closing operation of the reed valve, and ensures a smooth flow of the secondary air.

FIG. 7A is a plan view of a first modified example of the heat shield plate constituting the main part of the heat shield means. Hot plate 134 shielding the variant 1, the are formed in a substantially same shape as the heat shield plate 34 of the embodiment, the breathable substrate 134 ₁ is formed by metal wire mesh such as steel.

FIG. 7B is a plan view of a second modification of the heat shield plate constituting the main part of the heat shield means. Hot plate 234 shielding the variation 2, the are formed in a substantially same shape as the heat shield plate 34 of the embodiment, the breathable substrate 234 ₁ are formed by the steel wool.

Thus, any of the heat shield plates 13 of the first and second modified examples
4, 234 also has a function equivalent to that of the heat shield plate of the above-described embodiment, and can effectively remove the heat of the exhaust gas passing therethrough, thereby lowering the temperature of the exhaust gas reaching the reed valve R.

FIG. 8A shows a modified example 1 of a knock pin for connecting the upstream passage and the downstream passage of the secondary air distribution passage.
Is a partially cutaway perspective view of FIG. The knock pin 125 of the first modification is made of a metal material such as stainless steel.
25 ₁ and is formed in a cylindrical shape.
5 ₁ has a plurality of vents 125 ₂ passing secondary air or exhaust is bored.

FIG. 8B shows a modified example 2 of a knock pin connecting the upstream passage and the downstream passage of the secondary air distribution passage.
Is shown in perspective view. Dowel pin 225 of Modified Example 2
It is a metal material such as stainless steel, formed in a cylindrical shape having a honeycomb structure 225 ₁ therein, the honeycomb structure 225 in _one secondary air or exhaust passes.

Thus, any one of the modified examples 1 and 2
25 and 225 have the same function as the knock pin 25 of the first embodiment, and further, they receive the heat of the exhaust gas passing therethrough and contribute to the temperature drop.

Although the embodiments of the present invention have been described above, the present invention is not limited to those embodiments, and various embodiments are possible within the scope of the present invention. For example, in the above-described embodiment, the case where the present invention is applied to a motorcycle running engine has been described. However, it is needless to say that the present invention can be applied to other engines. May be used.

[0033]

As described above, according to the first aspect of the present invention,
Lead with a reed valve on the cylinder head of the engine body
A second valve chamber is provided, and secondary air is introduced into the upstream chamber of the reed valve chamber.
Air into the passage and the downstream chamber through the secondary air distribution passage.
In the exhaust gas purification device for an engine, the reed valve is opened and secondary air is introduced into the exhaust port by the exhaust pulsation pressure generated by the operation of the engine. The room is provided with air-permeable heat shielding means, and the heat of the exhaust gas that has heated the heat shielding means is transferred to a cylinder.
Provided so as to be conducted to the head, the exhaust flow back from the exhaust port to the downstream chamber of the reed valve chamber, the vent in the downstream chamber
Since there was I <br/> Unishi Charles guiding the reed valve after passing through the heat shield means for a gender, downstream chamber of the reed valve chamber, the effect of the temperature of the hot exhaust before reaching the reed valve by said thermal barrier means Lowering of the components of the reed valve due to heat, reducing the reliability,
Durability can be increased. Also heats the above heat shielding means
The heat of the exhaust gas is conducted to the cylinder head,
The stage does not overheat.

[0034] According particularly to the second aspect of the present invention, the opening and closing the open end of the reed valve bodies rie de valve, since so as to open in a direction to follow the flow of the exhaust gas flowing back to the reed valve chamber from the exhaust port In addition, foreign substances such as carbon mixed in the exhaust gas are less likely to be caught in the opening of the reed valve, so that accurate opening and closing operation of the reed valve can be ensured and its reliability can be improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an engine head.

FIG. 2 is an enlarged view of a main part of FIG. 1;

FIG. 3 is a longitudinal sectional view taken along line 3-3 in FIG. 2;

FIG. 4 is a cross-sectional view taken along line 4-4 in FIG. 2;

FIG. 5 is a partially broken cross-sectional view taken along line 5-5 of FIG. 2;

FIG. 6 is a perspective view of a heat shield plate.

7A is a plan view of a heat shield plate (Modified Example 1), and FIG.
Is a plan view of a heat shield plate (Modification 2)

FIG. 8A is a partially cutaway perspective view of a knock pin (Modified Example 1), and FIG. 8B is a perspective view of a knock pin (Modified Example 2).

[Explanation of symbols]

2 ... Cylinder head 7 ... Exhaust port 17 ... Cylinder head cover 21 ... Secondary air introduction passage 24 ... Secondary air distribution passage 30 closing the open end 34 ----- heat shield plate 34 ₁ ... substrate 34 ₂ .... left ... reed valve body 30 ₁ ... reed valve, the right spacing holding pieces 34 ₃ - ··· Engaging tongues 35 and 36 ··· Receptacle 37 ········ Vent hole C ·····························································・ Downstream chamber (lead valve chamber) E ・ ・ ・ ・ ・ ・ Engine P ・ ・ ・ ・ ・ ・ Heat shielding means R ・ ・ ・ ・ ・ ・ Reed valve

──────────────────────────────────────────────────の Continuing from the front page Examiner Takashi Kameda (56) References JP-A-57-93617 (JP, A) JP-A-58-10108 (JP, A) JP-A-58-44424 (JP, U) Open Sho 60-131770 (JP, U) Actual open Sho 59-117827 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F01N 3/08-3/36 F02F 7/00 F02F 1/24

Claims (7)

(57) [Claims] A reed valve chamber (C) provided with a reed valve (R) is provided in a cylinder head (2) of an engine body (E), and an upstream chamber (Cu) of the reed valve chamber (C) is provided with an atmosphere. And a downstream chamber (Cd) thereof is communicated with an exhaust port (7) of the engine via a secondary air distribution passage (24), and is generated by operation of the engine. Due to the exhaust pulsation pressure, the reed valve (R)
Was to be introduced into the exhaust port of the secondary air by opening (7), in the exhaust purification apparatus for an engine, breathable said reed valve chamber downstream chamber (C) in (Cd) Oh
The heat shielding means (P) and the exhaust gas heated by the heat shielding means (P).
Is provided so that the heat of the cylinder is conducted to the cylinder head (2) .
The exhaust flow back into the downstream chamber (Cd) of the exhaust port (7) from the lead valve chamber (C) is said in the downstream chamber (Cd)
Characterized in that after passing through the heat shield means (P) with a breathable and to Charles electrically to the lead valve (R), an exhaust purification device of an engine. 2. A pre-Symbol reed valve reed valve body (R) (3
Closing the open end of the 0) (30 _1), characterized in that so as to open in a direction to follow the flow of the exhaust gas flowing back from the exhaust port (7) reed valve chamber (C), the claim 1 exhaust purification system of the <br/> engine. (3) The heat shielding means (P) is made of an Al plate
The exhaust gas purification of an engine according to claim 1, characterized in that:
Device. (4) The heat shielding means (P) includes a number of ventilation holes.
(37) characterized by including a punch plate with an opening
The exhaust gas purifying apparatus for an engine according to claim 1, wherein (5) The heat shielding means (P) includes a number of ventilation holes.
(37) A square base consisting of a punch plate with an opening
Board (34 ₁ ) And its substrate (34) ₁ ) Both sides in the width direction
Left and right spacing holding pieces that are respectively formed at approximately right angles
(34 _Two ) And its substrate (34) ₁ ) One longitudinal edge
The engagement tongues (34) that are erected at a substantially right angle _Three ) And more
The d-shaped body according to claim 1, which is formed on a body.
Engine exhaust purification system. 6. Connected to the upper part of the cylinder head (2)
On the upper surface of the upper wall of the cylinder head cover (17)
A bottom wall of the reed valve chamber (C) is formed, and an upper surface of the bottom wall is formed.
The receiving seats (35, 36) are integrally projected upward and
The heat shielding means (P) is placed on a support (35, 36),
The engine according to claim 1, wherein the engine is carried.
Exhaust purification device. 7. The heat shielding means (P) is provided in the reed valve chamber.
(C) is engaged with the inner wall surface of the downstream chamber (Cd).
It covers almost the entire surface of the valve valve (R) from below.
The exhaust gas purifying apparatus for an engine according to claim 1, wherein