JP3646066B2 - Secondary air supply device for engine exhaust purification - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
According to the present invention, a head cover that defines a valve chamber that accommodates a valve mechanism is joined to a cylinder head, and secondary air for exhaust gas purification is connected to an exhaust port formed in the cylinder head. The present invention relates to an improvement of an engine cylinder head device provided with valve means for supplying gas.
[0002]
[Prior art]
Such a secondary air supply device for purifying exhaust gas of an engine is already known as disclosed in, for example, Japanese Patent Application Laid-Open No. 2000-203483.
[0003]
[Problems to be solved by the invention]
In the conventional secondary air supply device for purifying exhaust gas of the engine, the valve means is attached to the top wall of the head cover. Therefore, the valve means is charged and separated from the cylinder head, and heat damage from the cylinder head is caused. Although it has the advantage that it is difficult to be affected, it slightly increases the length of the engine in the axial direction of the cylinder, which may cause inconvenience in the in-vehicle layout of the engine.
[0004]
The present invention has been made in view of such circumstances, and has a rational configuration in which the valve means does not increase the length of the engine in the axial direction of the engine and is less susceptible to thermal damage from the cylinder head. An object of the present invention is to provide a secondary air supply device for purifying engine exhaust gas.
[0005]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the present invention has a cylinder head joined with a head cover that defines a valve chamber for accommodating a valve mechanism, and an exhaust port formed in the cylinder head. In a secondary air supply device for exhaust gas purification of an engine provided with a valve means for supplying secondary air for exhaust gas purification, an adjacent valve housing is formed on one side of the head cover without contacting the outer surface of the cylinder head. The first feature is that the valve means is provided in series and is accommodated in the valve housing.
[0006]
The valve means corresponds to a one-way valve 75 in an embodiment of the present invention described later.
[0007]
According to this first feature, the valve housing connected to the head cover and disposed adjacent to the outer wall of the cylinder head does not increase the length in the direction along the cylinder axis of the engine, so Can be expanded. Moreover, since the valve housing is not in contact with the outer wall of the cylinder head, it is difficult for high heat of the cylinder head to be transmitted to the valve housing, thus preventing heat damage from the cylinder head to the valve means in the valve housing. It is possible to ensure durability.
[0008]
According to the present invention, in addition to the first feature, the engine is disposed such that the cylinder axis is substantially horizontal and the exhaust port faces downward from the combustion chamber, and the head cover is joined to the cylinder head of the engine. The valve housing is connected to the lower part of the head cover, and a maze is formed between the upper part of the head cover and the cylinder head between the inlet connected to the valve operating chamber and the outlet arranged above the inlet and leading to the outside. A second feature is that a breather chamber that separates the lubricating oil mist from blow-by gas introduced from the valve operating chamber is formed.
[0009]
According to this second feature, the valve housing occupies a position relatively close to the exhaust port, resulting in a shortening of the secondary air passage and, consequently, a reduction in its flow resistance. The secondary air can be accurately supplied to the port, contributing to the improvement of the exhaust gas purification effect.
[0010]
Furthermore, in addition to the first or second feature, the third feature of the present invention is that the valve housing is arranged on the side of the cylinder head on which the spark plug is mounted.
[0011]
According to the third feature, the dead space around the spark plug can be used for the arrangement of the valve housing, and the enlargement of the engine can be avoided.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described based on one embodiment of the present invention shown in the accompanying drawings.
[0013]
1 is an overall side view of a scooter type motorcycle, FIG. 2 is a cross-sectional view taken along line 2-2 of FIG. 1, FIG. 3 is an enlarged view of a main part of FIG. 2, and FIG. 5 is a view taken in the direction of arrow 5 in FIG. 3, FIG. 6 is a top view of the cylinder head, and FIG. 7 is a back view of the head cover.
[0014]
First, in FIG. 1 and FIG. 2, the overall configuration of the scooter type motorcycle will be described.
[0015]
A body frame F of a scooter type motorcycle V having a front wheel Wf steered by a steering handle 11 and a rear wheel Wr driven by a swing type power unit P includes a front frame 12, a center frame 13 and a rear frame. 14 is divided into three. The front frame 12 is composed of an aluminum alloy casting product integrally provided with a head pipe 12a, a down tube 12b, and a step floor 12c. The center frame 13 on which the power unit P is supported so as to be swingable up and down via the pivot shaft 15 is also made of an aluminum alloy casting and is coupled to the rear end of the front frame 12. The rear frame 14 extending upward and rearward of the power unit P is formed of an annular pipe material, and a fuel tank 16 is supported on the rear frame 14 so as to be surrounded by the rear frame 14. A helmet case 17 is supported on the upper surface of the center frame 13, and the helmet case 17 is covered with a lid 19 having a seat 18 integrally.
[0016]
The power unit P includes a water-cooled single-cylinder four-cycle engine E and a belt-type continuously variable transmission T extending from the left side surface of the engine E to the rear of the vehicle body. To the rear end of the center frame 13. An air cleaner 21 is supported on the upper surface of the continuously variable transmission T, a muffler 22 is supported on the right side surface of the continuously variable transmission T, and a main stand 23 that can stand up and down is supported on the lower surface of the engine E.
[0017]
Next, the overall configuration of the power unit P will be described with reference to FIG.
[0018]
The engine body 25 of the engine E includes an engine block 32 and a rear crankcase half body 33b divided by a dividing surface extending in the vertical direction along the axis of the crankshaft 31, and the engine block 32 includes a cylinder bore 41. And a front crankcase half 33a constituting the crankcase 33 together with the rear crankcase half 33b, and a cylinder head 34 is coupled to the front end of the engine block 32. A head cover 35 is coupled to the front end of the head.
[0019]
Such an engine body 25 is arranged on the vehicle body frame F so that the cylinder axis L (see FIG. 1) is substantially horizontal, preferably along the front-rear direction of the vehicle body frame F with the front or the top facing upward as shown in the drawing. Installed.
[0020]
The belt-type continuously variable transmission T includes a right casing 37 and a left casing 38 that are coupled to each other, and the front right side surface of the right casing 37 is the left side of the front and rear crankcase halves 32 and 33. Bonded to the face. Further, a speed reduction casing 39 is coupled to the rear right side surface of the right casing 37.
[0021]
A drive pulley 54 is provided at the left end of the crankshaft 31 protruding into the right casing 37 and the left casing 38. The drive pulley 54 includes a fixed-side pulley half 55 fixed to the crankshaft 31 and a movable-side pulley half 56 that can approach and separate from the fixed-side pulley half 55. The half body 56 is urged in a direction approaching the stationary pulley half body 55 by a centrifugal weight 57 that moves radially outward in accordance with an increase in the rotational speed of the crankshaft 31.
[0022]
A driven pulley 59 provided on an output shaft 58 supported between the rear portion of the right casing 37 and the speed reduction casing 39 includes a fixed pulley half 60 supported on the output shaft 58 so as to be relatively rotatable, and a fixed pulley half. The movable-side pulley half 61 is urged toward the fixed-side pulley half 60 by a spring 62. A starting clutch 63 is provided between the stationary pulley half 60 and the output shaft 58. An endless V-belt 64 is wound around the drive pulley 54 and the driven pulley 59.
[0023]
An intermediate shaft 65 and an axle 66 that are parallel to the output shaft 58 are supported between the right casing 37 and the deceleration casing 39, and a reduction gear train 67 is provided between the output shaft 58, the intermediate shaft 65, and the axle 66. The rear wheel Wr is attached by spline fitting to the right end of the axle 66 that passes through the deceleration casing 39 and protrudes to the right.
[0024]
Thus, the rotational power of the crankshaft 31 is transmitted to the drive pulley 54, and is transmitted from the drive pulley 54 to the rear wheel Wr via the V belt 64, the driven pulley 59, the starting clutch 63 and the reduction gear train 67. .
[0025]
Since the centrifugal force acting on the centrifugal weight 57 of the drive pulley 54 is small when the engine E rotates at a low speed, the groove width between the stationary pulley half 60 and the movable pulley half 61 is reduced by the spring 62 of the driven pulley 59. , The gear ratio is LOW. When the rotational speed of the crankshaft 31 increases from this state, the centrifugal force acting on the centrifugal weight 57 increases, and the groove width between the fixed pulley half 55 and the movable pulley half 56 of the drive pulley 54 decreases, Along with this, the groove width between the stationary pulley half 60 and the movable pulley half 61 of the driven pulley 59 increases, so that the gear ratio changes steplessly from LOW to TOP.
[0026]
The configuration of the engine E will be described in detail with reference to FIGS.
[0027]
A piston 42 slidably fitted in a cylinder bore 41 provided in the engine block 32 is connected to the crankshaft 31 via a connecting rod 43. The cylinder head 34 is formed with a combustion chamber 26 facing the top surface of the piston 42 and intake and exhaust ports 27i and 27e respectively connected to the combustion chamber 26. The intake port 27i extends upward from the combustion chamber 26. However, it is bent backward in a U-shape and opened to the upper back surface of the cylinder head 34, to which the carburetor 24 sucked from the air cleaner 21 (see FIG. 1) is connected. The outer end of the exhaust port 27e extends downward from the combustion chamber 26 and opens to the lower surface of the cylinder head 34, to which the muffler (see FIG. 1) is connected via the exhaust pipe 29. The exhaust pipe 29 or the muffler 22 is provided with a catalytic converter 30 for exhaust purification.
[0028]
In addition, intake and exhaust valves 28i and 28e for opening and closing the intake and exhaust ports 27i and 27e are mounted on the cylinder head 34 so that the valve head side is opened in a V shape, and an electrode is disposed at the center of the combustion chamber 26. A spark plug 48 is screwed.
[0029]
A head cover 35 is joined to the end face of the cylinder head 34, and a valve operating mechanism Vm for opening and closing the intake and exhaust valves 28i and 28e is accommodated in a valve operating chamber 36 defined between the cylinder head 34 and the head cover 35. The The valve operating mechanism Vm is rotatably supported by the cylinder head 34 and is disposed between the intake and exhaust valves 28i and 28e, and is pivotally supported by the cylinder head 34 so as to be swingable. 44, intake and exhaust rocker arms 49i and 49e interlocking between the intake and exhaust valves 28i and 28e, and valve springs 50i and 50e for urging the intake and exhaust valves 28i and 28e in the closing direction, respectively. .
[0030]
As shown in FIGS. 2 and 3, a timing chamber 40 is formed on one side wall of the crankcase 33, the cylinder block 32a, and the cylinder head 34 to connect the inside of the crankcase 33 and the valve operating chamber 36. The chamber 40 accommodates an endless timing chain 45 wound around a drive sprocket 46 provided on the crankshaft 31 and a driven sprocket 47 provided on the camshaft 44. The drive sprocket 46, the driven sprocket 47, and the timing chain 45 constitute a timing transmission device Ti that decelerates the rotation of the crankshaft 31 by half and transmits it to the camshaft 44.
[0031]
The secondary air supply device for exhaust gas purification will now be described with reference to FIGS.
[0032]
A valve housing 74 is connected to the head cover 35 at a lower portion thereof, and a one-way valve 75 is accommodated therein. The valve housing 74 is formed integrally with the lower portion of the head cover 35, and adjacent inner housing half 74a without contacting one side wall of the cylinder head 34 to which the spark plug 48 is mounted, and the inner housing half 74a, The outer housing half 74b is joined to the outer surface parallel to the side wall by a bolt 76.
[0033]
The one-way valve 75 has a valve hole 78a and is sandwiched between the housing halves 74a and 74b. The inside of the valve housing 74 is an inner chamber 79a on the inner housing half 74a side, and an outer housing half 74b side. A valve seat plate 78 partitioned from the outer chamber 79b, an elastic valve plate 80 arranged to open and close the valve hole 78a on the inner chamber 79a side, and a valve seat plate 78 together with one end of the valve plate 80 And a valve plate stopper 88 that restricts the valve opening limit of the valve plate 80, and the elastic valve plate 80 opens and closes according to the pressure difference between the inner and outer chambers 79a and 79b. It has become.
[0034]
The outer housing half 74 b is integrally formed with a connecting pipe 89 connected to the outer chamber 79 b, and is connected to the air cleaner 21 via an air conduit 90. The inner chamber 79a is connected to the exhaust port 27e from the head cover 35 to the cylinder head 34 via a secondary air passage 91 formed in the inner chamber 79a.
[0035]
Thus, during the operation of the engine E, an pulsating wave of exhaust pressure is generated in the exhaust system including the exhaust port 27e due to intermittent exhaust action from the combustion chamber 26 to the exhaust port 27e by opening and closing of the exhaust valve 28e. When the negative pressure component of the pulsating wave is transmitted to the inner chamber 79a of the valve housing 74 via the secondary air passage 91, the valve plate 80 opens the valve hole 78a, so that the air cleaner 21 passes the air conduit 90 to the outer chamber 79b. The sucked secondary air passes through the valve hole 78a, passes through the inner chamber 79a and the secondary air passage 91, and is sucked into the exhaust port 27e. When the positive pressure component of the pulsating wave is transmitted to the inner chamber 79a of the valve housing 74 through the secondary air passage 91, the valve plate 80 closes the valve hole 78a, so that the reverse flow of the secondary air passage 91 toward the air cleaner 21 is performed. Is blocked. The secondary air thus supplied to the exhaust port 27e goes to the catalytic converter 30 while being mixed with the exhaust gas flowing through the exhaust system, where it participates in the oxidation removal of harmful components such as unburned gas in the exhaust gas.
[0036]
By the way, the valve housing 74 connected to the head cover 35 is disposed adjacent to the outer wall of the cylinder head 34, so that the length along the cylinder axis L of the engine E is not increased. , The degree of freedom of the in-vehicle layout of the engine E can be increased. In addition, since the valve housing 74 does not contact the outer wall of the cylinder head 34 and there is a space between them, the high heat of the cylinder head 34 is difficult to transmit to the valve housing 74, and therefore, the cylinder head 34 has no space in the valve housing 74. The one-way valve 75 can be prevented from being damaged by heat, and the durability of the one-way valve 75 can be ensured.
[0037]
Further, since the secondary air passage 91 connecting the inner chamber 79a of the valve housing 74 to the exhaust port 27e is formed in the head cover 35 and the cylinder head 34 itself, piping between them is unnecessary, and the structure can be simplified. . In addition, since the valve housing 74 connected to the lower portion of the head cover 35 occupies a position relatively close to the exhaust port 27e extending downward from the combustion chamber 26, the secondary air passage 91 is shortened and extended. Can reduce the flow resistance, accurately supply the secondary air to the exhaust port 27e, and contribute to the improvement of the exhaust gas purification effect.
[0038]
Further, since the valve housing 74 is arranged on the same side as the side wall of the cylinder head 34 to which the spark plug 48 is screwed, the dead space around the spark plug 48 is used for the arrangement of the valve housing 74. Can be avoided.
[0039]
Next, a breather device that recirculates blow-by gas generated in the crankcase 33 to the suction system including the air cleaner 21 will be described with reference to FIGS.
[0040]
Contrary to the valve housing 74, a breather chamber 95 is provided between the upper portion of the head cover 35 and the cylinder head 34. The breather chamber 95 is defined by upper side walls 34a and 35a of the cylinder head 34 and the head cover 35, and partition walls 34b and 35b that stand from the opposed surfaces of the cylinder head 34 and the head cover 35 and abut against each other. In the lower part of the partition wall 35b, an inlet 98a and an oil return port 98b are arranged in a notch shape so as to communicate the breather chamber 95 with the valve train chamber 36. The inlet 98a and the oil return port 98b It is arranged as far as possible from the chamber 40. Further, an outlet pipe 99 penetrating the inside and outside of the breather chamber 95 is fixed to an upper outer wall of the breather chamber 95, and a breather pipe 100 connected to the air cleaner 21 is connected to the outlet pipe 99.
[0041]
Further, one or a plurality of barriers 34c and 35c for bending the gas flow in the breather chamber 95 are provided on the opposing surfaces of the cylinder head 34 and the head cover 35 so that the breather chamber 95 is formed in a maze shape. The
[0042]
Thus, during operation of the engine E, the blow-by gas leaked from the combustion chamber 26 into the crankcase 33 through the sliding surface of the piston 42 moves to the valve operating chamber 36 through the timing chamber 40 and mainly from the inlet 98a to the breather. It flows into the chamber 95 and moves toward the outlet pipe 99 while the flow is bent by the barriers 34c and 35c. In the meantime, when lubricating oil mist generated in the valve operating chamber 36 due to the operation of the timing transmission device Ti and the valve operating mechanism Vm enters the blow-by gas and enters the breather chamber 95, the blow-by gas is blocked by the barriers 34c and 35c. When the flow is bent, the oil mist in the blow-by gas is separated and liquefied, flows down the bottom surface of the breather chamber 95, and flows out mainly from the lowermost oil return port 98b to the valve operating chamber 36. On the other hand, the blow-by gas from which the oil has been separated passes through the outlet pipe 99 and the breather pipe 100 and is sucked into the air cleaner 21 and purified, and then sucked into the engine E again for combustion processing.
[0043]
By the way, the breather chamber 95 is formed between the upper part of the head cover 35 in which the valve housing 74 is connected to the lower part and the cylinder head 34, so that the breather chamber 95 has a desired shape without being obstructed by the valve housing 74. It can be formed, and the penetration of the lubricating oil into the breather chamber 95 can be minimized. Moreover, the breather chamber 95 is defined by the upper side walls 34a and 35a of the cylinder head 34 and the head cover 35, and partition walls 34b and 35b projecting from the opposing inner walls thereof, so that a special breather chamber forming member needs to be provided. Therefore, it can contribute to the simplification of the structure.
[0044]
The cooling device for the engine E will be described with reference to FIGS.
[0045]
A rotor 69 is fixed to the right end side of the crankshaft 31, and a stator 70 constituting an AC generator 68 in cooperation with the rotor 69 is joined to the side wall of the crankcase 33 so as to be surrounded by the rotor 69. The support plate 73 is bolted. A cooling fan 71 is fixed to the right end portion of the crankshaft 31 outside the AC generator 68, and the radiator 72 is disposed so as to sandwich the cooling fan 71 between the AC generator 68. The radiator 72 is attached to the engine body 25 via a shroud 81 that surrounds the cooling fan 71.
[0046]
On one side of the cylinder head 34, a water pump 110 is provided for circulating the coolant in the coolant circuit including the radiator 72 and the water jacket 82 of the engine 25. The water pump 110 includes a pump housing 111 including an inner housing half 111a protruding toward the valve operating chamber 36 and an outer housing half 111b coupled to one side wall of the cylinder head 34 together with the inner housing half 111a. And a pump chamber 114 is formed in the outer housing half 111b.
[0047]
Both ends of the support shaft 112 are supported by opposing walls of both housing halves 111a and 111b, and a pump impeller 115 accommodated in the pump chamber 114 is supported on a cylindrical pump shaft 113 rotatably supported by the support shaft 112. Is fixed. The outer housing half 111b is formed with a discharge pipe 116 that communicates with the outer periphery of the pump chamber 114, and a thermostat 117 that opens and closes the discharge pipe 116. When the thermostat 117 is opened, the cooling water drawn into the center of the pump chamber 114 from the radiator 72 is pressurized by the rotation of the pump impeller 115 and supplied to the water jacket 82 through the discharge pipe 116 to cool the engine 25. To do. The cooling water that has been cooled returns to the radiator 72.
[0048]
The side cover 118 joined to the outer surface of the outer housing half 111 b has a bypass water channel that returns the discharged cooling water from the pump chamber 114 directly to the water jacket 82 without passing through the radiator 72 when the thermostat 117 is closed. Inlet pipe 119 is provided.
[0049]
A magnetic pump driving device 120 for driving the water pump 110 is configured between the driven sprocket 47 and the water pump 110 as follows.
[0050]
A stepped cylindrical magnet holder 121 is fixed to the outer surface of the center portion of the driven sprocket 47. The magnet holder 121 is formed by press-molding a non-magnetic stainless steel plate, and an annular drive magnet 122 is fixed to the inner peripheral surface of the large diameter portion by press-fitting or bonding.
[0051]
An annular driven magnet 123 fixed to the pump shaft 113 is accommodated in the inner housing half 111a. At that time, the driven magnet 123 is disposed concentrically with the drive magnet 122 with the inner housing half 111a interposed therebetween. Synthetic resin coverings 124 are mode-coupled to both end faces and the outer peripheral face of the driven magnet 123, and the pump impeller 115 is integrally connected to one end of the covering 124.
[0052]
Thus, when the driven sprocket 47 rotates the driving magnet 122 via the magnet holder 121, the driven magnet 123 is rotated in the same direction as the driving magnet 122 by the magnetic force exerted by the driving magnet 122 and the driven magnet 123. The pump impeller 115 can be driven to rotate.
[0053]
As mentioned above, although the Example of this invention was described, this invention is not limited to the said Example, A various design change can be performed in the range which does not deviate from the summary of this invention. For example, the oil return hole 98b can be omitted by making the inlet 98a of the breather chamber 95 also serve as the oil return hole. The present invention can also be applied to various vehicles such as a motor tricycle other than the motorcycle V.
[0054]
【The invention's effect】
As described above, according to the first feature of the present invention, a head cover that defines a valve operating chamber for housing a valve operating mechanism is joined to a cylinder head, and the head cover is formed on the cylinder head. In a secondary air supply device for exhaust gas purification of an engine provided with valve means for supplying secondary air for exhaust gas purification to the exhaust port, adjacent to one side of the head cover without contacting the outer surface of the cylinder head Since the valve housing is connected in series, and the valve means is accommodated in the valve housing, the valve housing does not increase the length in the direction along the cylinder axis of the engine, and the degree of freedom in the on-board layout of the engine is increased. Can be planned. Moreover, since the valve housing is not in contact with the outer wall of the cylinder head, it is difficult for high heat of the cylinder head to be transmitted to the valve housing, thus preventing heat damage from the cylinder head to the valve means in the valve housing. It is possible to ensure durability.
[0055]
According to a second aspect of the present invention, the engine is arranged such that its cylinder axis is substantially horizontal and the exhaust port faces downward from the combustion chamber, and the head cover is joined to the cylinder head of the engine. While the valve housing is connected to the lower part, a labyrinth is formed between the upper part of the head cover and the cylinder head between an inlet connected to the valve operating chamber and an outlet arranged above the inlet and leading to the outside. The breather chamber that separates the lubricating oil mist from the blow-by gas introduced from the valve chamber is formed so that the valve housing occupies a position relatively close to the exhaust port, and the secondary air passage This shortens and leads to a decrease in the flow path resistance, can accurately supply the secondary air to the exhaust port, and contribute to an improvement in the exhaust gas purification effect.
[0056]
Further, according to the third feature of the present invention, since the valve housing is arranged on the side of the cylinder head where the spark plug is mounted, a dead space around the spark plug can be utilized for the arrangement of the valve housing, An increase in size can be avoided.
[Brief description of the drawings]
FIG. 1 is an overall side view of a scooter type motorcycle showing a first embodiment of the present invention.
2 is a sectional view taken along line 2-2 of FIG.
FIG. 3 is an enlarged view of a main part of FIG. 2;
4 is a cross-sectional view taken along line 4-4 of FIG.
FIG. 5 is a view taken along arrow 5 in FIG. 3;
FIG. 6 is a top view of a cylinder head.
FIG. 7 is a rear view of the head cover.
[Explanation of symbols]
E ... Engine L ... Cylinder axis Vm ... Valve mechanism 26 ... Combustion chamber 27e ... Exhaust port 34 ... Cylinder head 35・ ・ ・ ・ ・ Head cover 36 ...... Valve chamber 48 ...... Ignition plug 74 ...... Valve housing 75 ...... Valve means (one-way valve)
95... Breather room 98 a... Entrance of breather room 99... Exit of breather room

Claims (3)

A head cover (35) defining a valve operating chamber (36) for accommodating a valve operating mechanism (Vm) between the cylinder head (34) and a cylinder head (34) is joined to the cylinder head (34). A secondary air supply device for purifying exhaust gas of an engine provided with valve means (75) for supplying secondary air for purifying exhaust gas to an exhaust port (27e) formed in
An adjacent valve housing (74) is connected to one side of the head cover (35) without contacting the outer surface of the cylinder head (34), and the valve means (75) is accommodated in the valve housing (74). A secondary air supply device for exhaust purification of an engine. The secondary air supply device for exhaust purification of an engine according to claim 1,
The engine (E) is arranged so that its cylinder axis (L) is substantially horizontal and the exhaust port (27e) faces downward from the combustion chamber (26), and the cylinder head (34) of this engine (E) The valve housing (74) is connected to the lower part of the head cover (35) joined to the valve head, while the valve cover (36) is connected between the upper part of the head cover (35) and the cylinder head (34). Lubricating oil is introduced from the blow-by gas introduced from the valve chamber (36) by communicating in a labyrinth between the inlet (98a) and the outlet (99) disposed above the inlet (98a) and leading to the outside. A secondary air supply device for purifying engine exhaust, wherein a breather chamber (95) for separating mist is formed. The secondary air supply device for exhaust purification of an engine according to claim 1 or 2,
A secondary air supply device for purifying exhaust gas of an engine, wherein the valve housing (74) is arranged on a side of the cylinder head (34) where the spark plug (48) is mounted.

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