JP4089656B2 - Engine secondary air supply device - Google Patents

Description

  The present invention relates to a secondary air supply device for an engine that supplies secondary air to an exhaust passage for purifying exhaust gas.

  As an exhaust gas purifying device for a vehicle engine such as a motorcycle, a passage for supplying secondary air to the exhaust system is formed, and an exhaust gas generated in the exhaust system via a reed valve device in the middle of the secondary air supply passage. There is a type that opens and closes a reed valve device with pulsation pressure (negative pressure) to supply secondary air into the exhaust system.

  In the SOHC type 4-cycle engine, one camshaft is mounted between the cylinder head cover and the cylinder head, and the two rocker shafts that support the rocker arm are mounted in the cylinder head cover. There is little space and it is difficult to provide the secondary air supply device.

For this reason, a pipe for supplying secondary air to the exhaust hole is provided outside, a reed valve chamber is provided above the rocker shaft on the exhaust side of the cylinder head cover, and a through hole leading to the exhaust hole is provided outside the cylinder head cover. (For example, refer to Patent Document 1 and Patent Document 2).
Japanese Utility Model Publication No. 61-9140 Japanese Patent Publication No. 63-2005

  If secondary air is supplied to the exhaust hole by external piping using pipes, the piping becomes complicated, and the more cylinders are, the more complicated and the appearance is not good.

  Further, as shown in Japanese Utility Model Publication No. 61-9140 of Patent Document 1 and Japanese Patent Publication No. 63-2005 of Patent Document 2, when a secondary air passage is formed in the outer portion of the cylinder head cover chamber, Not only does the head cover become large, but also the thickness for hole formation is required and the weight increases.

  The present invention has been made in view of the above-mentioned problems. A reed valve chamber is provided in the upper part of a cylinder head cover, and a secondary air supply passage provided inside the cylinder head cover and the cylinder head is provided in the exhaust passage as a secondary. An object of the present invention is to provide a secondary air supply device for an engine that supplies air and is compact and has good appearance and does not require maintenance.

  In order to achieve the above object, the present invention has the following configuration.

A secondary air supply device for an engine according to the present invention includes a valve operating device driven by a camshaft housed in a valve operating chamber covered with a cylinder head and a cylinder head cover, and a secondary air supplying secondary air to an exhaust passage. A four-cycle engine comprising an air supply passage and a reed valve device interposed in the course of the secondary air supply passage, the bearing housing for supporting the camshaft together with the cylinder head provided in the valve chamber; the reed valve chamber for accommodating the reed valve device, as well as arranged between the bearing housing, is characterized in that provided integrally with said bearing housing and the discrete valve chamber.

  In the secondary air supply device for an engine according to the present invention, the reed valve chamber is disposed above the cylinder as viewed from the crankshaft direction, and is disposed so as to be parallel to the camshaft and to cover the upper portion of the camshaft. Can be a thing.

  In the secondary air supply device for an engine according to the present invention, the secondary air supply passage that communicates the exhaust passage of the cylinder head and the reed valve chamber is located between the adjacent bearing housings and in the vicinity of the exhaust valve near the cylinder center. The cylinder head cover and the cylinder head can be formed so as to pass through the sealed mating surfaces.

  In the secondary air supply device for an engine according to the present invention, the secondary air supply passage corresponds to a narrow-diameter portion that is biased in the axial direction of the camshaft from the intake cam and the exhaust cam of the camshaft in plan view. It can be the one arranged in

  In the engine secondary air supply device according to the present invention, the lid member forming the reed valve chamber can be fastened and fixed around the valve seat of the reed valve device above the thick portion of the bearing housing. .

  According to the secondary air supply device for an engine of the present invention, the reed valve chamber is provided in the upper part of the cylinder head cover, and the secondary air is supplied to the exhaust passage by the secondary air supply passage provided inside the cylinder head cover and the cylinder head. In this way, it is possible to achieve an excellent effect that it is compact and has a good appearance and can be saved from maintenance work.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
The embodiment is a four-cycle engine for a motorcycle equipped with an SOHC type valve gear as shown in the overall view of FIG.

  As shown in FIGS. 1 to 6, the valve gear includes a single camshaft 5 on which an intake cam 3 and an exhaust cam 4 are formed, and a rocker arm 8 for supporting an intake cam and an exhaust cam. 8i, 8e) and a pair of rocker shafts 7 (7i, 7e) for supporting the respective rocker arms 8, and accommodated in a valve operating chamber 25 covered with the cylinder head 2 and the cylinder head cover 1 It is. The cylinder head cover 1 includes a bearing 27 that supports the camshaft 5 together with a bearing 27 that supports the journal of the camshaft 5 that is integrally formed with the cylinder head 2, and a rocker shaft housing 29 that supports the rocker shaft 7. And a reed valve chamber 11 which is located between a pair of rocker shafts 7 and 7 disposed in parallel with the camshaft 5 and accommodates the reed valve device 12 is integrally formed on the upper wall 1a of the cylinder head cover 1. The reed valve chamber 11 is interposed in the secondary air supply passage (through hole) 19 to the engine exhaust passage (exhaust hole) 18.

  Specifically, the cylinder head cover 1 is fastened to the upper surface of the cylinder head 2 by a plurality of fastening bolts 20. A camshaft 5 provided with an intake cam 3 and an exhaust cam 4 on the same axis is rotatably mounted on a mating surface 31 of the cylinder head cover 1 and the cylinder head 2. A sprocket 6 is attached to one end of the camshaft 5 so that the sprocket 6 faces the cam chain chamber 15, and one end of a cam chain (not shown) is wound around the sprocket 6 and accommodated in the cam chain chamber 15. Is wound around a drive sprocket of a crankshaft (crankshaft), and the camshaft 5 is rotated in conjunction with the crankshaft by this cam chain.

  Two rocker shafts 7 are attached to the cylinder head cover 1, and rocker arms 8 pivoted on the rocker shafts 7 are swung by the intake cam 3 and the exhaust cam 4, respectively. Is opened and closed.

  A reed valve chamber 11 is formed on the upper wall 1 a between the two rocker shafts 7 at the center upper portion of the cylinder head cover 1. The reed valve device 12 accommodated in the reed valve chamber 11 has a valve seat 13 provided on the lower surface of the valve seat 13 so that a valve lead 12a (operation restriction by the valve lead guide 12b) opens and closes the opening 13a with a screw or the like It is what.

The reed valve chamber 11 has a recess (reference number omitted) on the upper surface of the upper wall 1a with a lid member 11b having a tubular boss 11a protruding at a right-angle lateral direction with respect to the camshaft 5 and the rocker shaft 7 at the upper end. The other end of the air hose 14, which is closed and connected to the tubular boss 11a, is connected to an air cleaner 33 (see FIG. 7).
In addition, the reed valve chamber 11 has a camshaft chamber 15 side in which the sprocket 6 of the camshaft 5 in which the sprocket 6 is eccentrically provided at one end and the intake cam 3 and the exhaust cam 4 are provided at the other end is lowered. The opening 13a of the reed valve device 12 is opened to the lower side of the reed valve chamber 11.

  The camshaft 5 is provided with a narrow-diameter portion 16 between the sprocket 6 attached to one end and the intake cam 3 and the exhaust cam 4 provided eccentrically on the other end side. The corresponding cylinder head cover 1 is formed with a thick portion 17 that is inflated inward, and the thick portion 17 is formed integrally with the upper wall 1a of the cylinder head cover 1 and accommodates the reed valve device 12. A secondary air supply passage 19 is formed from 11 to the exhaust passage 18 of the cylinder head 2.

  In the vicinity of the secondary air supply passage 19 formed in the thick part 17 of the cylinder head cover 1, fastening bolts 20 for fastening the cylinder head cover 1 to the cylinder head 2 are arranged in the thick part 17. The cylinder head cover 1 is covered with a head cover cap (decorative cover) 21 with a gap at the outer periphery, and is fastened to the cylinder head cover 1 with a bolt 32 via a bush 32a made of an elastic material such as rubber and is supported in a floating manner.

The reed valve chamber 11 is formed so that the side of the cam chain chamber 15 accommodating the sprocket 6 of the camshaft 5 in which the sprocket 6 is eccentrically provided at one end and the intake cam 3 and exhaust cam 4 are provided at the other end is lowered. Since the opening 13a of the reed valve device 12 is opened to the lower side of the reed valve chamber 11, the height of the reed valve chamber 11 can be lowered and the height of the cylinder head cover 1 can be lowered.
Further, the secondary air reed valve chamber 11 can be formed integrally with the upper wall 1a of the cylinder head cover 1 so that the height of the cylinder head cover 1 can be set as low as possible.

The camshaft 5 is provided with a narrow-diameter portion 16 between the sprocket 6 attached to one end and the intake cam 3 and the exhaust cam 4 provided eccentrically on the other end side. A thick-walled portion 17 expanded inward is formed in the cylinder head cover 1 corresponding to the portion 16, and the reed valve device 12 is accommodated in the thick-walled portion 17 integrally formed on the upper wall 1 a of the cylinder head cover 1. Since the secondary air supply passage 19 is formed from the reed valve chamber 11 to the exhaust passage 18 of the cylinder head 2, the secondary air supply passage for sending the secondary air to the exhaust passage 18 without increasing the outer shape of the cylinder head cover 1. 19 can be secured, the secondary air supply passage 19 and the reed valve device 12 main body are not exposed, and are integrated with the cylinder head 2 and the cylinder head cover 1 so that the appearance is good. It can be.
Further, the reed valve device 12 can be easily attached to the exhaust port only by assembling the cylinder head cover 1 to the cylinder head 2 by integrating the cylinder head cover 1 (improvement of maintenance and assembling). There is also an advantage of omitting the piping work.

  Then, close to the secondary air supply passage 19 formed in the thick part 17 of the cylinder head cover 1 (immediately outside the secondary air supply passage 19), and fastening the cylinder head cover 1 to the cylinder head 2 Since the bolt 20 is disposed in the thick portion 17, the mating surface 31 of the cylinder head cover 1 and the cylinder head 2 of the secondary air supply passage 19 can be firmly and securely fastened. Therefore, gaskets, O-rings, spacers, and the like that have been conventionally required can be omitted, and costs can be reduced.

  The secondary air supply device of the embodiment is preferably used for the motorcycle V-type engine shown in FIG. 7, and in this case, each cylinder is provided with a secondary air supply device, and the air The removal of the hose 14 is directed to the inside of the V bank. Thereby, the air hose 14 is gathered between the V banks, the appearance is improved, and the handling of the engine unit is facilitated. In FIG. 7, reference numeral 34 is an engine case, 35 is a cylinder of front and rear cylinders, 36 is an exhaust pipe, and 37 is a muffler. Needless to say, the present invention can be applied to other types of SOHC engines as appropriate.

  The valve operating apparatus according to the above embodiment includes a single camshaft 5, intake and exhaust rocker arms 8 and 8, and a pair of rocker shafts 7 and 7 that support the rocker arms 8 and 8, respectively. And it is accommodated in the valve operating chamber 25 covered with the cylinder head 2 and the cylinder head cover 1. In general, when the support housing of the rocker shafts 7 and 7 is protruded from the cylinder head 2, there is less space, but in the above embodiment, the cylinder head cover 1 is provided with a journal of the camshaft 5 formed integrally with the cylinder head 2. Since the bearing housing 28 that supports the camshaft 5 and the rocker shaft housing 29 that supports the rocker shafts 7 and 7 are provided integrally with the bearing 27 that supports the shaft, not only the bearing of the camshaft 5 but also the rocker It is not necessary to provide the shaft housing 29 so as to protrude from the cylinder head 2 side.

  In addition, a reed valve chamber 11 for housing a reed valve device 12 provided in a secondary air supply passage (through hole) 19 for supplying secondary air to the exhaust passage (exhaust hole) 18 is arranged in parallel with the camshaft 5. Since the cylinder head cover 1 is formed integrally with the upper wall 1a of the cylinder head cover 1 between the pair of rocker shafts 7 and 7, the reed valve chamber 11 can be installed while suppressing the height of the cylinder head cover 1.

  Further, the exhaust gas of the engine is suddenly and intermittently discharged into the exhaust passage 18. While the exhaust gas pulsation pressure becomes negative, the reed valve device 12 is opened, and secondary air is supplied to the exhaust passage (exhaust port, etc.) 18 through the secondary air supply passage 19 to oxidize the exhaust. Promotes and purifies exhaust gas.

  Further, if the secondary air supply passage 19 connecting the reed valve device 12 and the exhaust passage 18 is formed close to and integrally with the rocker shaft housing 29, the cylinder head cover 1 does not become large and can be made compact.

  Further, if the reed valve device 12 is disposed in the upper part of the cylinder head cover 1 in parallel with the cam shaft 5 and the opening of the reed valve device 12 is opened toward the cam chain chamber 15 side, the reed valve chamber 11 is It is possible to install the cylinder head cover 1 while further suppressing the height thereof. The secondary air supply passage is formed inside the cylinder head cover 1 and the cylinder head 2 and is drilled from the lead valve device 12 at the center of the cylinder head cover 1 through the inside of the rocker shafts 7 and 7. 19 so that the piping does not appear to the outside and the appearance is good, and since the cylinder head cover 1 is integrated, conventional external piping (pipe, hose, reed valve device main body, brackets) is unnecessary. Maintenance work is improved, such as simplification of piping work, and it does not take much time.

Further, the cylinder head cover 1 is overlapped on the upper surface of the cylinder head 2 and fastened with a plurality of fastening bolts 20, and the secondary air supply passage 19 passes through the mating face 31 sealed between the cylinder head cover 1 and the cylinder head 2. Since a fastening bolt 20 for fastening the cylinder head cover 1 to the cylinder head 2 is arranged in the vicinity of the seal portion (for example, a fastening bolt is arranged just outside the secondary air supply passage 19 of the cylinder head cover 1), Tightening of the mating surface 31 of the cylinder head cover 1 and the cylinder head 2 in the secondary air supply passage 19 can be tightened, the tightening rigidity is improved, and the seal portion can be reliably sealed.
Therefore, it is possible to eliminate the need for a special gasket or a sealing body such as an O (O) ring, thereby reducing the cost.

It is a vertical side view which shows embodiment of this invention. It is a top view of a cylinder head cover showing an embodiment of the present invention. It is XX arrow sectional drawing of FIG. 2 of the cylinder head cover which shows embodiment of this invention. It is a vertical front view of a cylinder head cover showing an embodiment of the present invention. It is a top view of a cylinder head showing an embodiment of the present invention. It is a bottom view of a cylinder head cover showing an embodiment of the present invention. It is an outside side view of the whole engine which shows an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylinder head cover 1a Upper wall 2 Cylinder head 3 Intake cam 4 Exhaust cam 5 Cam shaft 6 Sprocket 7, 7 Rocker shaft 8, 8 Rocker arm 9 Intake valve 10 Exhaust valve 11 Reed valve chamber 11a Tubular boss 11b Lid member 12a Valve lead 12b Valve lead guide 12 Lead valve device 13 Valve seat 13a Opening 14 Air hose 15 Cam chain chamber 16 Small diameter portion 17 of cam shaft 17 Thick portion 18 Engine exhaust passage 19 Secondary air supply passage 20 Fastening bolt 21 Head cover cap 25 Valve chamber 27 Camshaft bearing 28 Bearing housing 31 Mating surface 32 Bolt 32a Bush 33 Air cleaner

Claims (5)

A valve operating device driven by a camshaft housed in a valve operating chamber covered with a cylinder head and a cylinder head cover, a secondary air supply passage for supplying secondary air to the exhaust passage, and a secondary air supply passage A four-cycle engine with an intervening reed valve device,
A bearing housing that supports the camshaft together with the cylinder head is provided in the valve chamber.
A secondary air supply device for an engine, wherein a reed valve chamber accommodating the reed valve device is disposed between the bearing housings, and the reed valve chamber and the bearing housing are provided integrally.   2. The engine according to claim 1, wherein the reed valve chamber is disposed above the cylinder when viewed from the crankshaft direction, and is disposed so as to be parallel to the camshaft and to cover the upper portion of the camshaft. Secondary air supply device.   A secondary air supply passage that communicates the exhaust passage of the cylinder head and the reed valve chamber passes through a mating surface between the adjacent bearing housings and near the cylinder center of the exhaust valve and sealed between the cylinder head cover and the cylinder head. The secondary air supply device for an engine according to claim 1 or 2, wherein the secondary air supply device is an engine.   4. The secondary air supply passage is disposed at a position corresponding to a narrow-diameter portion that is biased in an axial direction of the camshaft from an intake cam and an exhaust cam of the camshaft in plan view. The secondary air supply device for an engine according to any one of the above.   The lid member forming the reed valve chamber is fastened and fixed around the valve seat of the reed valve device above the thick wall portion of the bearing housing. The secondary air supply device for the engine according to item.

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