JP2008144606A - Secondary air supply device of engine and motorcycle having this device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a secondary air supply device of an engine, and a motorcycle having this device, capable of securing a required quantity of secondary air for purifying exhaust gas, without enlarging an installation space. <P>SOLUTION: This device supplies the secondary air (a) to an exhaust passage 19 of the engine E of a vehicle. At least a part of a supply passage P of the secondary air (a) is formed of an inside space of a constituting part 2 of a main frame 1 of a car body. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an engine secondary air supply device mounted on a vehicle and a motorcycle including the same.

  Conventionally, some engines mounted on motorcycles are provided with a secondary air supply device that supplies secondary air to an exhaust passage and promotes purification of exhaust gas by a downstream catalyst. This secondary air supply device uses, for example, a part of the air from the air cleaner as secondary air, and the distance between the secondary air intake of the air cleaner and the secondary air intake of the engine exhaust passage is 2. Secondary air is supplied to the exhaust passage by a pump connected by a secondary air supply pipe and operated by exhaust pulsation in the intake passage of the engine provided in the secondary air supply pipe (see Patent Document 1).

In this secondary air supply device, the pump is activated by exhaust pulsation in the intake passage of the engine, and clean secondary air taken out from the air cleaner is intermittently supplied to the exhaust passage of the engine, so that CO and HC in the exhaust gas are supplied. The exhaust gas is purified by reburning.
No. 2868468

  However, in the case of the secondary air supply device, since the secondary air supply pipe connecting the secondary air intake port of the air cleaner to the secondary air intake port of the exhaust passage of the engine is long, the secondary air A large passage resistance acts on the secondary air flowing in the supply pipe, and the loss of the secondary air intake suction force makes it difficult to supply the amount of secondary air necessary for sufficient purification of the exhaust gas to the exhaust passage. Thus, for example, a method of increasing the inner diameter of the secondary air supply pipe can be considered, but this is not preferable in terms of installation space in the vehicle body. It is also conceivable that a pump that operates by exhaust pulsation in the intake passage is provided with an air tank in the middle of the secondary air supply pipe that stores a sufficient amount of secondary air to be sucked in at a time during the suction operation. Since the air tank is large with a capacity of 500 cc or more, the installation space is particularly small and difficult to install in a motorcycle.

  Accordingly, the present invention provides a secondary air supply device for an engine that can secure an amount of secondary air necessary for exhaust gas purification without increasing the installation space, and a motorcycle equipped with the same. With the goal.

  In order to achieve the above object, a secondary air supply device for an engine according to the present invention is a device for supplying secondary air to an exhaust passage of an engine of a motorcycle, wherein at least one of the supply passages for the secondary air is provided. The part is formed by the internal space of the constituent part of the main frame of the vehicle body. Here, the constituent parts of the main frame include a main pipe, a down tube, a lower tube, and a rear pipe at the top of the vehicle body.

  According to this configuration, the component part of the main frame that originally becomes the framework of the vehicle body is effectively used as it is as at least a part of the supply passage of the secondary air, so that the installation space is not compressed, and the structure of the apparatus Can be simplified and the number of parts can be reduced. Further, since the main frame usually has a large inner diameter, a sufficient storage amount necessary for supplying the secondary air can be ensured, and an intake silencing effect can be obtained.

  The main frame component is, for example, a main pipe having a head pipe connected to the front end. Since the main pipe has a large capacity of the hollow portion that is the internal space thereof, a sufficient amount of secondary air can be secured, and since the hollow portion has a large inner diameter, the passage resistance of the secondary air is reduced. As a result, the secondary air can be efficiently supplied to the exhaust passage of the engine, and a large intake silencing effect can be obtained.

  In addition, it is preferable that a filter for air purification is disposed at a secondary air intake port in a constituent part of the main frame. In the secondary air taken in from the secondary air intake in the main frame components, that is, the dust and foreign matter contained in the outside air are removed by the air purification filter, so that the engine exhaust as clean secondary air Can be supplied to the passage.

  Furthermore, it is preferable to provide a secondary air pump that is driven by the pulsation pressure of the intake passage of the engine and feeds the secondary air in the supply passage of the secondary air. Since the pulsating pressure in the intake passage of the engine is used, a small and simple valve device combining a diaphragm and a reed valve can be used as a secondary air pump.

  According to the present invention, the constituent part of the main frame that originally becomes the framework of the vehicle body is effectively used as it is as at least a part of the supply passage of the secondary air, so that the installation space is not compressed and the structure of the apparatus is achieved. Can be simplified and the number of parts can be reduced. In addition, since the main frame usually has a large inner diameter, it is possible to secure a storage amount necessary for a sufficient supply of secondary air and to obtain an intake silencing effect.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a side view showing a main part of a motorcycle including a secondary air supply device for a four-cycle single cylinder engine according to an embodiment of the present invention. In the figure, the vehicle body frame FR is a so-called cradle type, and the main frame 1 which is the front half of the vehicle body frame FR has a main pipe 2 made up of one cylindrical substantially straight pipe, and the front end of the main pipe 2. One continuous down tube 3, a pair of left and right rear pipes 4 extending downward from the vicinity of the rear end of the main pipe 2, and a pair of left and right lower tubes 5 connecting the lower ends of the down tube 3 and the rear pipe 4. . A head pipe 7 is connected to the front end portion of the main pipe 2, and an upper bracket 8 and a lower bracket 9 fixed to a steering shaft (not shown) inserted into the head pipe 7 are arranged on the upper and lower sides of the head pipe 7. The front fork 5 is supported by these brackets 8 and 9, and a handle 10 is attached to the upper bracket 8.

  The rear pipe 4 constituting the rear portion of the main frame 1 has a front end portion of a swing arm (not shown) that supports a rear wheel (not shown) supported by a pivot shaft 12 so as to be swingable up and down. Yes. A seat rail 15 is connected to the rear end of the main pipe 2, and a support tube 16 for reinforcing the seat rail 15 is connected to the rear pipe 4, and the vehicle body frame FR is formed by the seat rail 15 and the support tube 16. A rear frame 17 that is the latter half of the second part is configured.

  An engine E is attached to the main frame 1 below the main pipe 2. The intake system of the engine E includes an air cleaner 21 supported by the rear frame 17, a carburetor 23 that is a fuel supply device connected to the air cleaner 21 via a flexible intake duct 22, and a space between the carburetor 23 and the cylinder head 18. It has an intervening throttle body 24. In addition to the carburetor 23, a fuel injection valve may be used as the fuel supply device.

  Secondary air a is supplied to the exhaust passage 19 in the cylinder head 18 of the engine E by the secondary air supply device 30. An upstream portion P1, which is a part of the supply passage P for the secondary air a, is formed using the internal space (hollow portion) of the main pipe 2 of the vehicle body. The rear end 2a of the main pipe 2 is opened to serve as an intake port P2 for the secondary air a, and an air purification filter 32 is loaded in the intake port P2.

  The position at which the filter 32 is disposed is not limited to the intake port P <b> 2, and may be any location in the supply passage P, particularly any location of the main pipe 2. For example, a filter 32 </ b> A can be disposed in the middle portion of the main pipe 2 as indicated by a two-dot chain line. In that case, the inspection and replacement of the filter 32A can be facilitated by making it possible to open and close a part of the peripheral wall of the main pipe 2 that houses the filter 32A. In addition, the inlet P2 for the secondary air a is not limited to the opening at the rear end 2a of the main pipe 2, and a horizontal hole is formed in the middle portion of the main pipe 2 in the longitudinal direction. Also good.

  A mounting hole 35 is provided in the lower part near the front end of the main pipe 2, and one end of a flexible intermediate tube 36 that serves as an intermediate part P 3 of the supply passage P for the secondary air a is connected to the mounting hole 35 via a nipple 37. ing. The front end (upper end) serving as the air inlet of the nipple 37 extends to the vicinity of the central axis of the main pipe 2, so that even if water enters the main pipe 2, this water passes through the nipple 37 and passes through the intermediate tube. 36 does not enter. A secondary air pump 40 is attached to the down tube 3 via a bracket 39, and the other end of the intermediate tube 36 is connected to the inlet of the secondary air pump 40. The secondary air pump 40 is a known pump having a simple structure in which a diaphragm and a reed valve are combined. A downstream tube 41 forming a downstream portion P4 of the supply passage P is connected to an outlet of the secondary air pump 40, and a downstream end portion 41a of the downstream tube 41 is an exhaust valve (not shown) in the exhaust passage 19 of the cylinder head 18. )).

  An intake passage 43 for supplying intake air to the engine E is formed in the air cleaner 21, the intake duct 22, the carburetor 23, and the throttle body 24 constituting the intake system. The intake passage 43 and the secondary air The pump 40 is connected with a negative pressure tube 44, and the negative pressure in the intake passage 43 is introduced into the secondary air pump 40. The negative pressure tube 44 is supported on the main pipe 2 by a support 45 made of a band wound around the outer periphery of the main pipe 2. In this example, one end of the negative pressure tube 44 is connected to the intake passage 43 in the carburetor 23. The secondary air pump 40 sucks the secondary air a through the main pipe 2 and the intermediate tube 36 when the intake passage 43 has a negative pressure, and sends it to the downstream tube 41 when the pressure is positive.

  As shown in FIG. 2 which is a plan view, the rear end 2a of the main frame 2 is opposed to the air cleaner 21 in close proximity, and the outside air is discharged from the gap C between the rear end 2a and the air cleaner 21 as secondary air a. Is smoothly taken into the main frame 2. Further, the downstream tube 41 extending from the secondary air pump 40 meanders above the engine E, and the downstream tube 41 is prevented from being overheated by cooling with the traveling wind.

As shown in FIG. 3, which is a longitudinal sectional view, the air purification filter 32 stores a filter medium (filter element) 52 inside a resin case 51, and the case 51 is inserted inside a rubber damper 53. It is a thing. The rear surface of the case 51 facing the front of the vehicle body is open, and the front wall 51a is provided with an air introduction hole 54 and a handle 55 for making the filter 32 easily put into and out of the rear end 2a of the main pipe 2. ing. The damper 53 has an open front surface facing the rear of the vehicle body, and a lattice-like rib 56 is formed on the rear wall 53a as shown in FIG. 4, and an air outlet hole 57 is formed between the ribs 56 and 56. Yes. A plurality of annular grooves 58 shown in FIG. 3 are formed on the outer periphery of the damper 53, thereby forming a labyrinth seal between the outer peripheral surface of the filter 32 and the inner peripheral surface of the main pipe 2. A screw hole 59 and a screw insertion hole 60 are respectively formed in the case 51 and the damper 53. A screw body (not shown) is inserted into the screw insertion hole 60 from the outside of the main pipe 2 and screwed into the screw hole 59. A filter 32 is attached to the main pipe 2.

  The operation of the secondary air supply device 30 configured as described above will be described. When the engine E of FIG. 1 is in an operating state, the pressure of the intake air pulsation in the intake passage 43 of the engine E is transmitted to the secondary air pump 40 via the negative pressure tube 44, whereby the secondary air pump 40 is driven. Then, outside air is taken in as secondary air a from the intake P2 at the rear end of the main pipe 2. At that time, since dust and foreign matter are filtered out from the outside air by the air purification filter 32, the clean outside air is introduced as the secondary air a into the upstream portion P1 which is the internal space of the main pipe 2. . The clean secondary air a passes through the internal space of the main pipe 2, and then is supplied to the exhaust passage 19 of the engine E through the nipple 37, the intermediate tube 36 and the downstream tube 41. The supplied secondary air a increases the oxygen concentration in the exhaust gas, and the exhaust gas is purified by a catalyst (not shown).

  Moreover, since the inlet P2 of the secondary air a is formed at the rear end 2a of the main pipe 2 and opens rearward, it is difficult for dust and foreign matter to enter from the inlet P2 during traveling. Moreover, since the rear end 2a faces and is close to the air cleaner 21, entry of dust and foreign matter is further suppressed. Furthermore, since the filter 32 is disposed at the intake port P2 at the rear end 2a of the main pipe 2, the filter 32 can be easily inspected and replaced.

  Thus, in the present invention, the main pipe 2 that is a constituent part of the main frame 1 that originally exists as a constituent part of the vehicle body is used as it is as a part of the supply passage P for the secondary air a. The installation space of the supply device 30 is not compressed. In addition, since it is not necessary to newly provide a separate part such as an air tank, the structure can be simplified and the number of parts can be reduced. Further, since the main pipe 2 which is a constituent part of the main frame 1 usually has a large inner diameter, it is possible to secure a storage amount necessary for a sufficient supply of the secondary air a, and a large volume makes it possible to reduce the intake noise. Also grows. In addition, since the inner diameter of the main pipe 2 is large, the passage resistance of the secondary air a is suppressed as much as possible. In this way, a sufficient amount of secondary air a is stored in the main pipe 2 at the upstream side of the secondary air pump 40 and is stored in the main pipe 2 at the time of intermittent suction by the secondary air pump 40, and the passage resistance. Is suppressed, the secondary air a sufficient for exhaust purification can be efficiently supplied to the exhaust passage 19 of the engine E.

  Next, the results of performance comparison experiments between the engine secondary air supply apparatus and the conventional secondary air supply apparatus according to the embodiment will be described. FIG. 5 shows the supply amount of the secondary air a in units of L / min. The inner tube 36 and the downstream tube 41 of FIG. 1 which are the pipes of the conventional apparatus and the apparatus of the present invention both have an inner diameter of 10 mm. As is apparent from FIG. 5, the motorcycle according to the present invention can be operated at any speed of 20 km / h, 30 km / h, 40 km / h, 50 km / h, and 60 km / h from the idling state (ID). The engine secondary air supply device can supply a larger amount of secondary air.

  In the present invention, depending on the arrangement of the engine E and the intake system, as a constituent part of the main frame 1 forming a part of the supply passage P for the secondary air, the down tube 4 or the down tube 4 can be used instead of the main pipe 2. Tube 4 can also be used. Further, depending on the shape of the main frame 1, it is possible to form all of the supply passage P by the constituent parts of the main frame 1. The present invention can also be applied to a tricycle or a four-wheel vehicle for traveling on rough terrain.

  As described above, the preferred embodiments of the present invention have been described with reference to the drawings. However, various additions, modifications, or deletions can be made without departing from the spirit of the present invention. It is included in the range.

1 is a side view showing a main part of a motorcycle including a secondary air supply device for an engine according to an embodiment of the present invention. It is a top view which shows the principal part of the motorcycle provided with the secondary air supply device. It is a longitudinal cross-sectional view of the filter for air purification. It is a rear view of the filter. It is a table | surface which shows the result of the performance comparison experiment of the secondary air supply apparatus of the engine concerning one Embodiment of this invention, and the conventional secondary air supply apparatus.

Explanation of symbols

1 Main frame 2 Main pipe (component)
7 Head pipe 19 Exhaust passage 30 Secondary air supply device 32 Filter 36 Intermediate tube 40 Secondary air pump 43 Intake passage a Secondary air E Engine FR Body frame P Secondary air supply passage

Claims (5)

A device for supplying secondary air to an exhaust passage of a vehicle engine,
A secondary air supply device for an engine, wherein at least a part of the secondary air supply passage is formed by an internal space of a component part of a main frame of a vehicle body.   2. The secondary air supply apparatus for an engine according to claim 1, wherein the constituent part of the main frame is a main pipe having a head pipe connected to a front end portion.   The secondary air supply device for an engine according to claim 1 or 2, wherein a filter for air purification is disposed at a secondary air intake port in a constituent part of the main frame.   4. The secondary air of an engine according to claim 1, wherein the secondary air supply passage is provided with a secondary air pump that is driven by a pulsating pressure of an intake passage of the engine and supplies secondary air to the secondary air supply passage. Feeding device.   A motorcycle comprising the engine secondary air supply device according to any one of claims 1 to 4.

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