JP5874244B2 - Secondary air supply device for internal combustion engine - Google Patents

Description

  The present invention provides a secondary air supply for supplying secondary air (or secondary air) for purifying exhaust gas in a two-cylinder engine typically mounted on a vehicle such as a motorcycle or an ATV (All Terrain Vehicle). Relates to the device.

  In this type of vehicle engine, a secondary air supply device is provided to purify exhaust gas exhausted after combustion. The suction type uses negative exhaust pulses inside the exhaust pipe (exhaust pipe) to draw air into the vicinity of the exhaust port. A reed valve is installed in the middle of the air supply path, and the air cleaner box Taking in clean air from.

  Until now, when arranging and configuring a secondary air system for purifying exhaust gas, in order to introduce secondary air into the exhaust port, the secondary air unit and the engine have been connected by pipe piping. However, since the cost of the piping and the secondary air unit increases, a method of omitting the heat-resistant piping by incorporating the secondary air reed valve into the engine independently from the secondary air unit has become the mainstream. ing. Note that the secondary air reed valve itself is exposed to a high-temperature exhaust gas atmosphere.

  A conventional secondary air supply device will be schematically described with reference to a specific example of a motorcycle. First, as shown in FIG. 5, a crankcase 11, a cylinder 12, a cylinder head 13, and a cylinder head cover around an engine 10 mounted on a vehicle body frame 101. 14 are joined together so that they sequentially overlap. In this example, the engine 10 is a water-cooled parallel two-cylinder four-cycle gasoline engine. A throttle body 102 that adjusts the amount of air supplied to the engine 10 and an air cleaner 103 that supplies air to the throttle body 102 are continuously connected to the rear upper side of the engine 10.

  Further, as shown in FIG. 6, a piston 15 is accommodated in the cylinder 12 so as to be able to reciprocate, and an intake port 17 and an exhaust port 18 communicate with a combustion chamber 16 formed in the cylinder head 13. The intake port 17 and the exhaust port 18 and the combustion chamber 16 are opened and closed by an intake valve 19 and an exhaust valve 20 via a valve mechanism (not shown). As shown in FIG. 4, a throttle body 102 and an exhaust pipe 104 are connected to the intake port 17 and the exhaust port 18, respectively. Then, as shown in FIG. 6, exhaust gas is discharged from the combustion chamber 16 to the exhaust port 18 as indicated by an arrow G.

  The engine 10 includes a secondary air supply device 1 as shown in FIG. 5, and the secondary air supply device 1 includes a secondary air unit 2. Further, when the secondary air reed valve 3 is arranged in the engine 10, it is installed on the upper part of the cylinder head cover 14 as shown in the figure because of the reed valve installation space. The air cleaner 103 and the reed valve 3 are connected by a tube 4 and the secondary air unit 2 is disposed at an appropriate position on the way. As shown in FIG. 6, the reed valve 3 is disposed inside the cap 5, and the secondary air supplied from the secondary air unit 2 passes through the reed valve 3 in the cap 5 and is In the head cover 14, the air is supplied into the exhaust ports 18 from the secondary air introduction path 6 that branches into two branches.

JP 2010-209765 A

In the conventional secondary air supply device 1, the secondary air introduction path 6 is formed across the cylinder head cover 14 and the cylinder head 13, and a gasket 21 is mounted between the two. Since these members or parts in contact with the secondary air introduction path 6 are exposed to the high temperature of the exhaust, high heat resistance and confidentiality are required. In particular, the gasket 21 is formed of a resin material, and it is not always easy to ensure sufficient heat resistance and confidentiality under such use conditions.
When the reed valve 3 is disposed on the cylinder head cover 14 as in this example, the area around the cylinder head 13 must be bulky.

  As another example, in the internal combustion engine described in Patent Document 1, a reed valve chamber is formed in the cylinder head cover at a portion where a reed valve for controlling the supply of secondary air supplied to the exhaust system is provided. Thus, a bulging portion that bulges toward the camshaft is integrally provided.

  In view of such circumstances, an object of the present invention is to provide a secondary air supply device for an internal combustion engine that can appropriately and effectively supply secondary air while achieving downsizing and the like.

The secondary air supply device for an internal combustion engine according to the present invention is an internal combustion engine in which a timing chain for a valve operating mechanism is disposed between cylinders each having a cylinder and a cylinder head, and an exhaust port connected to each cylinder and an exhaust connected thereto. A reed valve for controlling a quantity of secondary air supplied to an exhaust passage formed by a pipe and a reed valve housing chamber for housing the reed valve, wherein the reed valve The storage chamber is provided in the cylinder head so as to be positioned approximately in the center of the exhaust port of each cylinder, the timing chain is disposed approximately in the center in the width direction of the internal combustion engine, and the reed valve corresponds to the timing chain. Te, is disposed between two of the exhaust pipes extending from the cylinders, the reed valve, the width of the timing chain and the internal combustion engine Characterized in that it is arranged so as to overlap in countercurrent.

  In the secondary air supply device for an internal combustion engine according to the present invention, the reed valve storage chamber is provided in the cylinder head, and a secondary air supply passage from the reed valve storage chamber toward the exhaust pipe is provided in the cylinder head. It is formed inside a cylinder head.

  In the secondary air supply device for an internal combustion engine according to the present invention, the reed valve housing chamber is covered with a lid-like member, and the lid-like member is disposed so as to overlap the flange portion of the exhaust port in a top view. It is characterized by that.

  According to the present invention, by arranging the reed valve so as to overlap the timing chain in the engine width direction, the space widened by the space of the timing chain tunnel is effectively utilized. And by providing a reed valve corresponding to this space, the engine can be substantially made compact. Further, although the interval between two adjacent exhaust pipes is increased, the space can be effectively used even in a space sandwiched between these exhaust pipes, and the reed valve can be effectively arranged in this space.

  In the cylinder head, a reed valve housing chamber and a secondary air supply passage from the reed valve housing chamber to the exhaust pipe are formed. Thus, by forming the reed valve accommodating chamber and the secondary air supply passage inside the cylinder head itself, these components or members can be efficiently and compactly arranged.

1 is a side view of a motorcycle according to an application example of a secondary air supply device for an internal combustion engine according to the present invention. It is a perspective view showing the circumference of the engine as an application example of the secondary air supply device of the internal combustion engine of the present invention. It is sectional drawing which follows the II line of FIG. 2 which shows the engine structure as an application example of the secondary air supply apparatus of the internal combustion engine of this invention. It is a figure which shows the reed valve mounting part periphery which concerns on the secondary air supply apparatus of the internal combustion engine of this invention. It is a side view which shows the engine periphery as an application example of the conventional secondary air supply apparatus. It is a longitudinal cross-sectional view which shows the engine internal structure as an application example of the conventional secondary air supply apparatus.

Hereinafter, preferred embodiments of a secondary air supply device for an internal combustion engine according to the present invention will be described using the same reference numerals for substantially the same or corresponding members based on the drawings.
First, the entire vehicle structure to which the present invention is applied will be described. In this embodiment, a motorcycle 100 as shown in FIG. 1 is used, and an engine mounted on the motorcycle 100 is provided with an oil pump as will be described later. In the drawings used in the following description, the front of the vehicle is indicated by an arrow Fr, the rear of the vehicle is indicated by an arrow Rr, and the lateral right side of the vehicle is indicated by an arrow R, if necessary. Is indicated by an arrow L.

  In the motorcycle 100, a front fork 105 is provided at the front end of a body frame 101 extending along the front-rear direction of the vehicle so as to be turnable in the left-right direction. The front fork 105 supports the front wheel 106. Although not shown in detail, the vehicle body frame 101 includes a main frame that substantially forms the front half of the vehicle and a seat rail that forms the rear half of the vehicle. The engine 10 is attached to the main frame below the main frame. .

  In this example as well, a throttle body 102 that adjusts the amount of air supplied to the engine 10 and an air cleaner 103 that supplies air to the throttle body 102 are continuously connected upward and rearward of the engine 10. It shall be (see FIG. 2). Above the engine 10, a fuel tank 107 is supported by a vehicle body frame 101, and fuel is supplied to the throttle body 102 side via a fuel hose (not shown).

  A headlamp 108 is disposed at the front end of the vehicle, and a front cowl 109 is attached around the front. The front cowl 109 is provided with a pair of left and right direction indicators 110. A side cowl 111 that covers the side surface of the vehicle is connected to the rear of the front cowl 109, and the front cowl 109 and the side cowl 111 are smoothly connected to each other and cover a substantially front half of the vehicle including the engine 10.

  A swing arm 112 is slidably attached to the rear part of the main frame of the vehicle body frame 101, and a rear wheel 113 is supported on the rear end of the swing arm 112, and the power of the engine 10 is transmitted in the same manner as in a known technique. As a result, the rear wheel 113 is driven. A seat rail is connected to the rear upper part of the main frame of the body frame 101, and a seating seat 114 is supported on the seat rail.

  Also in this embodiment, the engine 10 is a water-cooled parallel two-cylinder four-cycle gasoline engine. As shown in FIG. 2, exhaust pipes 104 are respectively connected to the exhaust ports 18 of the cylinder heads 13 of the left and right cylinders. Each exhaust pipe 104 extends rearward so as to wrap around the lower side of the crankcase 11, and the muffler. 115. A catalyst (not shown) is mounted in front of the muffler 115 (upstream of the exhaust), and has a purifying action on the exhaust gas by the catalyst.

  Here, the engine 10 according to the present invention will be described more specifically. FIG. 3 shows a sectional view through the intake port 17 and the exhaust port 18 in the cylinder head 13. In this embodiment, a timing chain tunnel 22 is formed between the left and right cylinders so as to penetrate the cylinder 12 and the cylinder head 13 in parallel with the cylinder axial direction. A timing chain 23 whose front and rear portions are guided by a chain guide 24 is mounted in the timing chain tunnel 22. Although not shown, a crankshaft is pivotally supported on the crankcase 11 in the left-right direction, that is, in the cylinder arrangement direction, while a camshaft constituting a valve mechanism is horizontally mounted on the cylinder head 13 in the left-right direction. The timing chain 23 is wound around sprockets respectively attached to the crankshaft and the camshaft, whereby the rotational driving force of the crankshaft is transmitted to the camshaft via the timing chain 23.

  Now, the engine 10 according to the present embodiment includes a secondary air supply device 50 as shown in FIG. The secondary air supply device 50 includes a secondary air unit 51 and includes a reed valve 52 that controls the amount of secondary air supplied from the secondary air unit 51 to the exhaust passage. The secondary air unit 51 is disposed at an appropriate position in the middle of the tube 53 connecting the air cleaner 103 and the reed valve 52, and can open and close the flow path in the tube 53 using a solenoid valve or the like. Particularly in the present invention, the reed valve 52 is disposed so as to overlap the timing chain 23 in the width direction of the engine 10. The timing chain 23 is disposed substantially in the center of the engine 10 in the width direction. As shown in FIGS. 2 and 3, the reed valve 52 corresponds to the timing chain 23 between the two exhaust pipes 104 extending from each cylinder. Placed in.

  More specifically, as shown in FIG. 3, a pair of left and right reed valve storage chambers 54 are recessed in the cylinder head 13 at the approximate center of the left and right exhaust ports 18. The two reed valve accommodating chambers 54 are isolated from each other by a partition wall 55. Each reed valve storage chamber 54 and the exhaust port 18 are communicated with each other via a secondary air supply passage 56 formed so as to face the corresponding exhaust pipe 104. Each reed valve accommodating chamber 54 accommodates a reed valve 52 configured substantially independently, and both reed valve accommodating chambers 54 are covered with a cap 57 which is a lid-like member.

  In the above case, each reed valve 52 is attached to and supported by a case or frame 58, and is fixed to the front side surface of the cylinder head 13 so as to be integrated into a unit as a whole and closed to the reed valve accommodating chamber 54. Is done. Referring also to FIG. 4, the reed valve 52 is a thin plate having a substantially rectangular or strip shape, and is supported in a cantilever manner by a support portion 59 on the upper end side in this example. Further, as shown in FIG. 3, it has a stopper 60 for restricting the opening degree of the reed valve 52, and the stopper 60 restricts the movement of the reed valve 52 on the free end side.

  The frame 58 of the reed valve 52 is sandwiched between them as shown in FIG. 3 by fixing the cap 57 to the cylinder head 13. As shown in FIG. 4, in this example, the cap 57 is provided with mounting portions 61 projecting in the left and right directions at two diagonal positions, and through holes 62 for fixing bolts (not shown) are formed in the mounting portion 61. It is formed. On the other hand, a flange portion 18a is attached to the open end of the exhaust port 18 as shown in FIG. 3, and the exhaust pipe 104 is connected to the flange portion 18a. As can be seen from FIG. 4, the mounting portion 61 of the cap 57 and the flange portion 18a of the exhaust port 18 are arranged so as to overlap each other when viewed from above, that is, there is a region where both overlap in the left-right direction.

  In the basic operation of the secondary air supply device 50 according to the present invention having the above-described configuration, when the engine 10 is started, the intake valve 19 and the exhaust valve 20 in each cylinder are opened and closed at a predetermined timing, and the exhaust gas after combustion is shown in FIG. As indicated by the arrow G of 3, the exhaust port 18 exhausts the exhaust pipe 104. At this time, a negative exhaust pulse is generated inside the exhaust pipe 104. On the other hand, the secondary air unit 51 is controlled so that the secondary air is introduced into the cap 57 through the tube 53 by the operation of the secondary air unit 51, and the negative exhaust pulse of the exhaust pipe 104 is the secondary air supply passage 56. The reed valve chamber 54 acts on the reed valve chamber 54, thereby opening the reed valve 52, and the secondary air inside the cap 57 passes through the secondary air supply passage 56 as shown by the arrow A in FIG. 18 is supplied. By supplying the secondary air to the exhaust side in this way, for example, when the engine is cold such as during warm-up operation, the effect of reaching the operating temperature of the catalyst as soon as possible is obtained.

  According to the present invention, the secondary air reed valve 52 is arranged in the cylinder head 13. In this case, in the cylinder head 13 of the multi-cylinder engine 10 in this example, the reed valve 52 is arranged directly in the space in front of the timing chain tunnel 22 which has been a dead space in the past.

  By arranging the reed valve 52 directly on the cylinder head 13 in this way, a high-temperature exhaust gas atmosphere does not pass between the cylinder head cover 14 and the cylinder head 13. Thereby, it is not necessary to require high heat resistance for the gasket 21 between them. Further, since the secondary air reed valve chamber is not provided above the cylinder head cover 14, the overall height of the engine can be suppressed, and the vehicle can be made compact and the mass can be concentrated (so-called mass concentration). As a result, substantial cost reduction can be achieved.

Next, the characteristic configuration of the present invention and the operation and effects thereof will be described. First, in the engine 10 including the timing chain 23 disposed in the center of the engine width direction inside the cylinder head 13, the reed valve 52 is It arrange | positions so that it may overlap with the timing chain 23 in an engine width direction.
If the structure in which the timing chain 23 is arranged in the center in the width direction of the engine 10 as in the present embodiment is left as it is, the engine 10 becomes larger in the width direction by the space of the timing chain tunnel 22. In the present invention, such a wide space is effectively utilized, and the reed valve 52 is disposed corresponding to this space, so that the engine 10 can be substantially made compact.

The reed valve 52 is disposed between the two left and right exhaust pipes 104 extending from each cylinder corresponding to the timing chain 23.
The width of the left and right exhaust pipes 104 is increased by the width of the timing chain tunnel 22, and the space between the two adjacent exhaust pipes 104 is expanded. In particular, the reed valve 52 can be arranged.

In addition, the reed valve storage chamber 54 is provided in the cylinder head 13, and secondary air supply passages 56 from the reed valve storage chamber 54 to the exhaust pipe 104 are formed in the cylinder head 13.
Thus, by forming the reed valve accommodating chamber 54 and the secondary air supply passage 56 inside the cylinder head 13 itself, these components or members can be efficiently and compactly arranged.

  In this case, the reed valve 52 is arranged inside the cylinder head 13 so that the high-temperature exhaust gas stays inside the cylinder head 13 even if it flows backward. That is, when the reed valve 3 (see FIG. 6) is disposed on the cylinder head cover 14 as in the prior art, a thermal effect is exerted on components around the cylinder head cover 14 (for example, the gasket 21 of the cylinder head cover 14 in particular) due to the backflow of high-temperature exhaust gas. Will be given. As described above, the gasket 21 is formed of a resin-based material and is easily affected by such heat. By providing the reed valve 52 on the cylinder head 13, the exhaust gas does not flow across the cylinder head 13 and the cylinder head cover 14, i.e., does not contact the gasket 21, so that the thermal influence can be eliminated.

Further, the reed valve chamber 52 is covered with a cap 57 as shown in FIG. 3, and the cap 57 is disposed so as to overlap with the flange portion 18a of the exhaust port 18 in a top view as shown in FIG.
By arranging the cap 57 so as to overlap the flange portion 18a of the exhaust port 18 in this way, a layout that effectively utilizes the space becomes possible.

As mentioned above, although this invention was demonstrated with various embodiment, this invention is not limited only to these embodiment, A change etc. are possible within the scope of the present invention.
Although an example of a two-cylinder engine has been described in the above embodiment, the present invention can also be applied to a four-cylinder engine or the like in the same manner as described above.

10 engine, 11 crankcase, 12 cylinder, 13 cylinder head, 14 cylinder head cover, 17 intake port, 18 exhaust port, 19 intake valve, 20 exhaust valve, 21 gasket, 22 timing chain tunnel, 23 timing chain, 24 chain guide, 50 Secondary air supply device, 51 Secondary air unit, 52 Reed valve, 53 tube, 54 Reed valve storage chamber, 55 Bulkhead, 56 Secondary air supply passage, 57 Cap, 58 Frame, 59 Bearing, 60 Stopper, 61 mounting part, 62 through-hole, 100 motorcycle.

Claims (3)

In an internal combustion engine in which a timing chain for a valve operating mechanism is disposed between cylinders each having a cylinder and a cylinder head, two are supplied to an exhaust passage formed by an exhaust port of each cylinder and an exhaust pipe connected thereto. A secondary air supply device comprising a reed valve for controlling the amount of secondary air and a reed valve housing chamber for housing the reed valve,
The reed valve storage chamber is provided in the cylinder head at a position substantially at the center of the exhaust port of each cylinder.
The timing chain is disposed substantially in the center in the width direction of the internal combustion engine, and the reed valve is disposed between the two exhaust pipes extending from each cylinder corresponding to the timing chain,
The secondary air supply device for an internal combustion engine, wherein the reed valve is arranged to overlap the timing chain in the width direction of the internal combustion engine. 2. The secondary air supply device for an internal combustion engine according to claim 1 , wherein a passage for supplying secondary air from the reed valve housing chamber to each exhaust pipe is formed in the cylinder head. Wherein along with the read valve chamber is covered by a lid-like member, the lid-like member is an internal combustion engine according to claim 1 or 2, characterized in that it is arranged to overlap with the flange portion and the top view of the exhaust port Secondary air supply device.

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