EP1655460A1

EP1655460A1 - Engine

Info

Publication number: EP1655460A1
Application number: EP04747366A
Authority: EP
Inventors: R. c/o Yamaha Hatsudoki Kabushiki Kaisha Inque; T. c/o Yamaha Hatsudoki Kabushiki Kaisha Masuda; S. c/o Yamaha Hatsudoki Kabushiki Kaisha Tanaka
Original assignee: Yamaha Motor Co Ltd
Current assignee: Yamaha Motor Co Ltd
Priority date: 2003-07-10
Filing date: 2004-07-06
Publication date: 2006-05-10
Anticipated expiration: 2024-07-06
Also published as: JPWO2005005793A1; EP1655460B1; EP1655460A4; ES2402686T3; JP4197522B2; WO2005005793A1

Abstract

It is an obj ect of the invention to provide an engine capable of making a space, in which a decompression device and a breather device are arranged, compact.

In an engine 11 of the invention, a sprocket 32, around which a cam chain 23 is trained, is fixed to a camshaft 22, a breather rotating body 33 of a breather device 18 is fixed to an outside of the sprocket 32, the breather rotating body 33 comprises a cylindrical-shaped annular portion 33a, and a decompression device 19 is arranged inside the annular portion 33a.

Description

TECHNICAL FIELD

This invention relates to an engine, in which a decompression device and a breather device are arranged.

BACKGROUND ART

Conventionally, with engines used for vehicles and the like, a camshaft is provided on a side of a cylinder head to open and close an intake valve and an exhaust valve, a decompression device is provided axially of the camshaft to open the intake valve or the exhaust valve to release pressure in a combustion chamber when compression should be effected in the combustion chamber, thereby removing resistance at the time of compression, and a breather device is provided axially of the camshaft to separate an oil and gases from each other (for example, see JP-A-04-298617 and JP-A-05-156917).
However, such conventional engines involve a problem that a space, in which the decompression device and the breather device are arranged, becomes large on a side of the cylinder head because the decompression device is provided inside of a sprocket provided on the camshaft for a cam chain and the breather device is provided outside of the sprocket.

DISCLOSURE OF THE INVENTION

Hereupon, the invention has been thought of in view of the above and has its object to provide an engine capable of making a space, in which a decompression device and a breather device are arranged, compact.
The invention, which can attain the object, provides an engine characterized in that a rotating member, to which a drive force is transmitted from a crank shaft, is fixed to a camshaft, a breather rotating body constituting a rotating portion of a breather device is fixed outside the rotating member, the breather rotating body has a cylindrical-shaped annular portion, and a decompression device is arranged inside the annular portion.
Also, it is preferred in the engine according to the invention that the decompression device comprise a turning portion and the turning portion is arranged inside the annular portion.
Also, it is preferred in the engine according to the invention that the decompression device have one end of a decompression cam connected to the turning portion and have the other end of the decompression cam extended toward an exhaust cam.
Also, it is preferred in the engine according to the invention that an outermost portion of the decompression device axially of the camshaft be positioned toward the rotating member from a tip end of the annular portion of the breather rotating body axially of the camshaft.
Also, it is preferred in the engine according to the invention that an impeller shaft of a water pump device be detachably fitted into an end of the camshaft toward the breather device and the water pump device be arranged outside and adjacent to the breather device.
Also, it is preferred in the engine according to the invention that the breather device comprise a breather stationary body to constitute a stationary portion arranged in opposition to the breather rotating body, the breather stationary body be fixed to that partition, which partitions off the side of the breather device and the side of the water pump device, and the impeller shaft be fitted into and latched on the partition.
Also, it is preferred in the engine according to the invention that the breather device comprise a breather stationary body to constitute a stationary portion arranged in opposition to the breather rotating body, the breather stationary body be fixed to that partition, which partitions off the side of the breather device and the side of the water pump device, openings be formed on the partition, and gases separated in the breather device go toward an air cleaner through the openings.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic view showing a cross section of a cylinder head of an engine according to an embodiment of the invention.
Fig. 2 is a side view showing a decompression device, a cam chain, etc. of the engine according to the embodiment.
Fig. 3 is a side view showing a turning portion, etc. of the decompression device according to the embodiment.
Fig. 4 is an exploded, perspective view showing the turning portion, etc. of the decompression device according to the embodiment.
Fig. 5 is an exploded, perspective view showing a camshaft, a connection member, etc. according to the embodiment.
Fig. 6 is a perspective view showing motions of a rocker arm, an exhaust valve, etc. which are representative of an operating state of the decompression device according to the embodiment.
Fig. 7 is an illustration representative of motions of a decompression cam according to the embodiment.

In addition, the reference numeral 11 in the drawings denotes an engine, 16 a cylinder head, 18 a breather device, 19 a decompression device, 20 a water pump device, 22 a camshaft, 23 a cam chain, 24 an intake valve, 25 an exhaust valve, 31 a rocker arm, 32 a sprocket (rotating member), 33 a breather rotating body, 42 a turning portion, 43 a base side portion, 44 a tip end side portion, 47 a decompression cam, 47a a pushed pin, 47b a cam body, and 47c a decompression-cam portion.

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of the invention will be described below.
Figs. 1 to 7 show the embodiment of the invention.
First, the constitution is described, and the reference numeral 11 in Fig. 1 denotes a single cylinder, four-cycle, four-valve engine provided on a motorcycle as a saddle type vehicle, the engine 11 comprising a cylinder head 16 fixed to an upper portion of a cylinder block (illustration of which is omitted), the cylinder head 16 mounting thereon a breather device 18, a decompression device 19, and a water pump device 20.
More specifically, a camshaft 22 is rotatably provided on the cylinder head 16, the camshaft 22 being connected to a crank shaft (illustration of which is omitted) through a cam chain 23, which serves as a wrapping transmission belt, and the camshaft 22 being rotated through the cam chain 23 by virtue of rotation of the crank shaft.
The camshaft 22 is rotated whereby respective exhaust and intake valves 24, 25 are opened and closed in a predetermined timing. The camshaft 22 is constructed such that a connection member 27 is fixed to a camshaft body 26 by means of a bolt 28 as shown in Fig. 1 and a latch member 29 is fitted between the camshaft body 26 and the connection member 27 to have the both rotating together.
The camshaft body 26 is formed with an intake cam portion 26a and an exhaust cam portion 26b, and rocker arms 30, 31 are brought into sliding contact with the cam portions 26a, 26b whereby the respective valves 24, 25 are opened and closed through the rocker arms 30, 31.
Also, a sprocket 32 as a rotating member, around which the cam chain 23 is trained, is fixed to the connection member 27 of the camshaft 22, and a breather rotating body 33 of the breather device 18 is fixed to an outside of the sprocket 32 so that the breather rotating body 33 rotates together with rotation of the sprocket 32.
A substantially cylindrical-shaped annular portion 33a is projectingly formed on the breather rotating body 33, a breather stationary body 34 is provided outside the breather rotating body 33, and a tip end of an annular portion 34a of the breather stationary body 34 is inserted inside a tip end of the annular portion 33a of the breather rotating body 33 such that tip ends of the both annular portions 33a, 34a overlap each other to define a gap C between the annular portion 33a and the annular portion 34a.
The breather stationary body 34 is fixed to a partition 36, which partitions off a side of the breather device 18 and a side of the water pump device 20, and onto which a fitting groove 50c of an impeller shaft 50 is fitted and latched. The partition 36 together with the breather stationary body 34 is mounted to a water-pump housing 41 to be sub-assembled to the water pump device 20. Also, the partition 36 is formed with a plurality of openings 36a so that gases separated in the breather device 18 go toward a gas chamber 37 on the side of the water pump device 20 and toward an air cleaner (illustration of which is omitted) through the openings 36a.
Here, an action of the breather device 18 is described.
When pressure in a combustion chamber 48 of the engine 11 is increased in a driving state of the engine 11, a gas-liquid mixture of gases and a liquid (oil) in the combustion chamber 48 leaks into the casing through a gap on a piston ring, so that the gas-liquid mixture escapes toward the breather device 18, which is low in pressure. Since the breather rotating body 33 together with the sprocket 32 rotates within the breather device 18 in the driving state of the engine 11, the gas-liquid mixture passes through the gap C between the breather rotating body 33 in a rotating state and the breather stationary body 34 in a stationary state as indicated by an arrow a to flow into the breather device 18.
The gas-liquid mixture passes through the gap C whereby it expands when flowing into the breather device 18 from the gap C and a liquid of the gas-liquid mixture is separated from gases to adhere to an inner wall surface of the breather rotating body 33 due to centrifugal forces generated by rotation of the breather rotating body 33. The liquid as adhered flows down through the gap C to an outside and then flows downward along an inner wall surface 39 of a chain chamber 38 to be returned to an oil pan (a lower portion of the casing) (illustration of which is omitted).
Further, the gases separated in the breather device 18 go toward the gas chamber 37 on the side of the water pump device 20 through the openings 36a of the partition 36 as indicated by an arrow b. Since the gases further expand in the gas chamber 37 to be subjected to gas-liquid separation therein, the liquid accumulates on a bottom wall to flow downward along the inner wall surface 39 of the chain chamber 38 via a discharge hole 53 to be returned to an oil tank (illustration of which is omitted) as indicated by an arrow c.
On the other hand, the gases separated further in the gas chamber 37 flow toward the air cleaner from inside of the gas chamber 37 as indicated by an arrow d in Fig. 1.
Also, the decompression device 19 is arranged in the breather device 18, which serves for gas-liquid separation.
The decompression device 19 serves to open the exhaust valve 25 a little in a compression stroke to release pressure, and is arranged inside the breather rotating body 33 of the breather device 18.
As shown in Figs. 3 and 4, the decompression device 19 comprises a base side portion 43 constituting a part of a turning portion 42 and pivotally provided on the sprocket 32 through a turning shaft 45, the base side portion being biased clockwise in Fig. 3 by a spring 46. A tip end side portion 44 is fixed to a tip end side of the base side portion 43 to constitute the turning portion 42. A pair of actuation pins 44a are provided on a tip end of the tip end side portion 44 to project therefrom. An outermost portion (the tip end side portion 44) of the decompression device 19 axially of the camshaft is positioned toward the sprocket 32 (inside) from a tip end of the annular portion 33a of the breather rotating body 33 axially of the camshaft.
A pushed pin 47a (one end) of a decompression cam 47 is inserted between and connected to the actuation pins 44a, 44a. The decompression cam 47 comprises, as shown in Fig. 5, a columnar-shaped cam body 47b, the pushed pin 47a projecting from the cam body 47b, and a semi-circular decompression-cam portion 47c formed at a tip end of the cam body 47b.
The cam body 47b of the decompression cam 47 is inserted into a through-hole 27a of the connection member 27 and an insertion hole 26c of the exhaust cam portion 26b of the camshaft body 26. In this state of insertion, the decompression cam 47 is turned a predetermined angle whereby the decompression-cam portion 47c (the other end) having a semi-circular cross sectional shape projects and sinks from a surface of the exhaust cam portion 26b.
In a state, in which the decompression-cam portion 47c projects from the surface of the exhaust cam portion 26b as shown in Figs. 6 and 7(a), and in which one end 31a of the exhaust rocker arm 31 gets on the decompression-cam portion 47c as shown in Fig. 6, a push portion 31b of the exhaust rocker arm 31 pushes the exhaust valve 25 to put the same in a slightly opened state. Timing, in which the exhaust valve 25 is slightly opened, is in a compression stroke, and gases in the combustion chamber 48 are let outside to thereby restrict an increase in pressure within the combustion chamber 48.
That is, since centrifugal forces of the turning portion 42 are not so large when the engine 11 revolves at low speed, the bias of the spring 46 causes the turning portion 42 to turn to a position indicated by a solid line in Fig. 3. In this state, the decompression-cam portion 47c rotates to be put in a state, inwhichits semi-circular shape stands upright and decompression is effected.
On the other hand, since centrifugal forces of the turning portion 42 become large when the engine 11 revolves at high speed, the turning portion 42 turns counterclockwise against the bias of the spring 46 to a position indicated by a two-dot chain line from the position indicated by the solid line in Fig. 3. Thereby, the pair of actuation pins 44a move the pushed pin 47a to turn the decompression cam 47, so that the decompression-cam portion 47c is caused to sink from the surface of the exhaust cam portion 26b. Thereby, there comes a state, in which decompression is released. Further, with the water pump device 20, one end 50a of the impeller shaft 50 is connected to the bolt 28 and an impeller 52 is provided at the other end 50b of the impeller shaft 50 and accommodated in a pump chamber 51. A pump-side cooling water passage extended from the pump chamber 51 is connected directly to a head-side cooling water passage formed in the cylinder head 16.
The impeller 52 revolves to draw a cooling water into the pump chamber 51 from a radiator side to supply the same to the head-side cooling water passage of the cylinder head 16 via the pump-side cooling water passage from the pump chamber 51.
With the above constitution, the turning portion 42 of the decompression device 19 is arranged inside the annular portion 33a of the breather rotating body 33 of the breather device 18 whereby an axial width of the camshaft 22 can be made as short as possible. As a result, a space, in which the decompression device 19 and the breather device 18 are arranged, can be made compact.
Also, since oil is separated in the breather device 18 to adhere to an inner wall of the annular portion 33a, it adheres to the decompression device 19 in the annular portion 33a to enable improving lubrication of the decompression device 19.
Further, since the decompression device 19 having an irregular shape rotates in the breather device 18, it is possible to improve the function of gas-liquid separation.
Moreover, since the decompression device 19 is arranged in the annular portion 33a of the breather rotating body 33, the turning portion 42 of the decompression device 19 abuts against the annular portion 33a prior to the provision of the spring 46 to enable the annular portion 33a to function as a stopper for the turning portion 42.
Besides, since one end (the pushed pin 47a) of the decompression cam 47 is connected to the turning portion 42 and the other end (the decompression-cam portion 47c) of the decompression cam 47 is extended to the exhaust cam portion 26b, the decompression device 19 enables a drive force from the turning portion 42 of the decompression device 19, which is arranged in the breather device 18, to be surely transmitted to the exhaust cam portion 26b via the decompression cam 47.
Also, since the outermost portion (the tip end side portion 44) of the decompression device 19 axially of the camshaft is positioned toward the sprocket 32 (inside) from the tip end of the annular portion 33a of the breather rotating body 33 axially of the camshaft, the decompression device 19 is completely accommodated in the breather rotating body 33, so that specifically in a state prior to mounting of the decompression device 19 to the sprocket 32, it is possible to perform the work of storage, mounting, or the like with the decompression device 19 accommodated in the breather rotating body 33, thus enabling protecting the decompression device 19.
Further, since the impeller shaft 50 of the water pump device 20 is detachably fitted into an end of the camshaft 22 on a side of the breather device 18 and the water pump device 20 is arranged outside and adjacent to the breather device 18, an axial width of the camshaft 22 can be made as short as possible even in a constitution, in which the water pump device 20 is arranged outside the breather device 18.
Moreover, since the breather stationary body 34 of the breather device 18 is fixed to that partition 36, whichpartitions off the side of the breather device 18 and the side of the water pump device 20, and the impeller shaft 50 is fitted into and latched on the partition 36, the partition 36, to which the breather stationary body 34 of the breather device 18 is fixed, can efficiently prevent the impeller shaft 50 from coming off.
In addition, while the embodiment applies the invention to the engine 11 for motorcycles, the invention is of course applicable to engines for other uses. Also, engines are not limited to single cylinder, four-valve ones but may be of other type. Further, while the sprocket 32 is adopted as "rotating member", it is not limitative but it is possible to use a pulley in place of the sprocket 32 and a belt in place of the cam chain 23. Also, it is possible to adopt gears in place of the sprocket 32 so that a drive force from the crank shaft can be transmitted by means of a plurality of gears.
While the invention has been described in detail with reference to the specific embodiment, it is apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.
The present application is based on Japanese Patent Application (Patent Application No. 2003-195210) filed on July 10, 2003 and Japanese Patent Application (Patent Application No. 2004-080057) filed on March 19, 2004, contents of which are incorporate herein for reference.

INDUSTRIAL APPLICABILITY

As described above, according to the invention, the decompression device is arranged inside the annular portion of the breather rotating body of the breather device to thereby enable making an axial width of the camshaft as short as possible, so that a space, in which the decompression device and the breather device are arranged, can be made compact.
Also, since oil is separated in the breather device to adhere to the inner wall of the annular portion, it adheres to the decompression device in the annular portion to enable improving lubrication of the decompression device.
Further, since the decompression device having an irregular shape rotates in the breather device, it is possible to improve the function of gas-liquid separation.
Moreover, since the decompression device is arranged in the annular portion of the breather rotating body, the turning portion of the decompression device abuts against the annular portion to enable the annular portion to function as a stopper for the turning portion.
Besides, since one end of the decompression cam is connected to the turning portion and the other end of the decompression cam is extended to the exhaust cam portion, the decompression device enables a drive force from the turning portion of the decompression device arranged in the breather device to be surely transmitted to the exhaust cam portion via the decompression cam.
Also, since the outermost portion of the decompression device axially of the camshaft is positioned toward the rotating member from the tip end of the annular portion of the breather rotating body axially of the camshaft, the decompression device is completely accommodated in the breather rotating body, so that specifically in a state prior to mounting of the decompression device to the rotating member, it is possible to perform the work of storage, mounting, or the like with the decompression device accommodated in the breather rotatingbody, thus enabling protecting the decompression device.
Also, since the impeller shaft of the water pump device is detachably fitted into the end of the camshaft on the side of the breather device and the water pump device is arranged outside and adjacent to the breather device, an axial width of the camshaft can bemade as short as possible even in a constitution, in which the water pump device is arranged outside the breather device.
Also, since the breather stationary body of the breather device is fixed to that partition, which partitions off the side of the breather device and the side of the water pump device, and the impeller shaft is fitted into and latched on the partition, the partition, to which the breather stationary body of the breather device is fixed, can efficiently prevent the impeller shaft from coming off.

Claims

An engine characterized in that a rotating member, to which a drive force is transmitted from a crank shaft, is fixed to a camshaft, a breather rotating body constituting a rotating portionof abreatherdevice is fixedoutside the rotatingmember, the breather rotating body has a cylindrical-shaped annular portion, and a decompression device is arranged inside the annular portion.
The engine according to claim 1, wherein the decompression device comprises a turning portion and the turning portion is arranged inside the annular portion.
The engine according to claim 2, wherein the decompression device has one end of a decompression cam connected to the turning portion and has the other end of the decompression cam extended toward an exhaust cam portion.
The engine according to any one of claims 1 to 3, wherein an outermost portion of the decompression device axially of the camshaft is positioned toward the rotating member from a tip end of the annular portion of the breather rotating body axially of the camshaft.
The engine according to any one of claims 1 to 3, wherein an impeller shaft of a water pump device is detachably fitted into an end of the camshaft toward the breather device and the water pump device is arranged outside and adj acent to the breather device.
The engine according to claim 5, wherein the breather device comprises a breather stationary body to constitute a stationary portion arranged in opposition to the breather rotating body, the breather stationary body is fixed to that partition, which partitions off the side of the breather device and the side of the water pump device, and the impeller shaft is fitted into and latched on the partition.
The engine according to claim 5, wherein the breather device comprises a breather stationary body to constitute a stationary portion arranged in opposition to the breather rotating body, the breather stationary body is fixed to that partition, which partitions off the side of the breather device and the side of the water pump device, openings are formed on the partition, and gases separated in the breather device go toward an air cleaner through the openings.