JPH10252441A - Ohc(overhead camshaft) engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the number of part items and increase a degree of freedom of layout of accessories by blocking a lower face of a head cover attached to a cylinder head by a breather plate to form a breather chamber and attaching a guide member for suppressing flapping of a drive member at the time of adjustment to a lower face of the breather plate. SOLUTION: A power unit 40 consisting of an engine 10 and a transmission 10a of a motor-bicycle has a cylinder head 45 and a head cover 46 which covers an upper part thereof, and a breather chamber 55 for returning blow by gas into an intake system is provided in the head cover 46. In this case, the breather chamber 55 is formed by blocking an inner face of a projection part 46a provided in the head cover 46 by a breather plate 46b. A guide member 71 for suppressing flapping of a timing chain 68 is attached to a lower face of the breather plate 46b. By making the breather plate 46b also serve as a mounting member of the guide member 71 is this way, the mounting member becomes unnecessary, and assembly man-hour can be reduced due to the decrease of the number of part-items.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an improvement in an OHC engine. The OHC engine is an abbreviation for an overhead camshaft engine.

[0002]

2. Description of the Related Art FIG. 7 is a sectional view of a conventional engine.
The engine 100 includes a crankshaft 102 rotatably provided on a crankcase 101, a timing sprocket 103 provided on the crankshaft, and a crankcase 101.
, An exhaust / intake cam shaft 105, 106 rotatably provided on the cylinder head 104, and an exhaust / intake cam shaft 105,
106, and the timing chain 10 which is extended over the cam sprockets 107, 108 and the timing sprocket 103.
9, a guide member 111 which is close to the timing chain 109 between the cam sprockets 107 and 108 in order to suppress flapping of the timing chain 109, and an attachment member 112 for attaching the guide member 111 to the cylinder head 104. . In addition, 113, 11
4 is a chain guide, 115 is a chain tensioner, 1
Reference numeral 16 denotes a head cover, and 117 denotes a breather chamber.

FIG. 8 is a front view of a cam shaft of a conventional engine.
11 and approach the guide member 111 to the mounting member 11.
2 shows that the mounting member 112 has been mounted to the cylinder head 104 with bolts B. Reference numeral 118 denotes a boss formed on the cylinder head 104, and 119 denotes a breather plate that forms a lower wall of the breather chamber 117.

[0004]

In the above prior art, a mounting member 112 is required to dispose the guide member 111 above the timing chain 109, and a boss is required to mount the mounting member 112 to the cylinder head 104. The part 118 must be formed. Further, by providing the mounting member 112, the timing sprocket 10
It occupies the space around 7, 108, and for example, the breather plate 119 above the mounting member 112 must be disposed further above, and the upper surface position of the head cover 116 is restricted, so that the volume of the breather chamber 117 is secured. There is a disadvantage that it becomes difficult to do. Therefore, an object of the present invention is to provide an OHC engine capable of reducing the number of parts and improving the degree of freedom in layout of accessories for a cylinder head and a head cover.

[0005]

According to a first aspect of the present invention, there is provided a breather chamber for returning blow-by gas to an intake system by closing a lower surface of a head cover attached to a cylinder head with a breather plate. Then, a guide member was attached to the lower surface of the breather plate in the breather chamber. By using the breather plate as a mounting member for the guide member, a member for mounting the guide member to the cylinder head is not required, and the number of parts can be reduced.
This can reduce the number of assembly steps. Further, the degree of freedom in layout of accessories for the cylinder head and the head cover can be improved.

[0006]

Embodiments of the present invention will be described below with reference to the accompanying drawings. The drawings should be viewed in the direction of reference numerals. FIG. 1 is a side view of a motorcycle according to the present invention.
A front fork 4 attached to the head pipe 3 of the body frame 2, a front wheel 5 and a front fender 6 attached to the front fork 4, a handle 7 connected to the front fork 4, and an upper front portion of the body frame 2 A fuel tank 8 mounted so as to straddle the vehicle, a seat 9 (double seat having a driver's seat and a passenger seat) mounted on the rear upper portion of the body frame 2 and a cradle space surrounded by each pipe of the body frame 2 An engine 10 and a transmission 10a disposed therein, an air cleaner 11 disposed behind the cradle space and below the seat 9, a carburetor 12 connected between the air cleaner 11, an intake port of the engine 10, and an engine 10 An exhaust pipe 13, a collecting chamber 14, and a silencer 15 connected to an exhaust port of
A radiator 16 disposed in front of the engine 10, a swing arm 17 attached to a rear portion of the vehicle body frame 2 via a pivot 2a, a rear suspension 18 having a rear end of the swing arm 17 suspended on the vehicle body frame 2,
And a rear wheel 19 attached to the swing arm 17. In the figure, 21 is a step bracket, 22 is a stand, 2
3 is a rear grab rail.

FIG. 2 is a plan view of the motorcycle according to the present invention. The rear side portions of the body frame 2 shown in FIG. 1 are covered with side covers 26, 26 and auxiliary side covers 27, 27, and above the rear wheel 19. A rear fender 28 is put on the rear fender 28 and a rear cowl 29 is put on the rear fender 28. In the figure, 31 is a headlamp, 32 and 32 are front turn signals, 33 and 34 are meters, 35 is a tail lamp,
36, 36 are rear turn signals, and 37, 37 are steps.

FIG. 3 is a side view of a main part of the motorcycle according to the present invention, showing a power unit 40 composed of an engine 10 and a transmission 10a. The power unit 40 includes a crankcase 43 including an upper case 41 and a lower case 42.
A cylinder block 44 attached to the upper front part of the crankcase 43, a cylinder head 45 attached to the upper part of the cylinder block 44, and a head cover 46 covering the upper part of the cylinder head 45. The front engine hanger 41a, the rear upper engine hanger 41b and the rear lower engine hanger 42a are attached to the vehicle body frame 2. 47 is a starter motor, 48 is an AC generator, 51 is a water pump, 52 is an oil filter element, and 53 is an oil pan.

FIG. 4 is a front view of the power unit according to the present invention, in which a head cover 46 is provided with a breather chamber 55 for returning blow-by gas to an intake system.
5 indicate a plurality of exhaust pipes 13 for each cylinder.
The same applies hereinafter. ) Indicates that the oil filter element 52 is mounted in the center of the front part of the crankcase 43.

FIG. 5 is a sectional view taken along line 5-5 of FIG.
The main bearings 41c, 41d, 41e, 41f, 41g, 41h provided on the upper case 41 for rotatably supporting the motor 7.
And the main bearings 42c, 42d, 42e provided in the lower case,
42f, 42g, 42h, connecting rods 58 having one ends rotatably connected to crank pins 57a, 57b, 57c, 57d of the crankshaft 57, and connecting rods 58 ...
Are connected to the other end via piston pins 61 (the other three are omitted).

The crankshaft 57 has a timing sprocket 57e for driving a camshaft described later and an oil pump drive sprocket 57f for driving an oil pump described later in an intermediate portion. Piston 62 ...
Is the cylinder liner 6 fitted to the cylinder block 44.
3 move vertically.

The power unit 40 includes an exhaust cam shaft 65 provided on the cylinder head 45 and a cam shaft 6.
5, the rocker arms 66 ...
An exhaust valve 67 that opens and closes through the camshaft 65
And a timing chain 68 which is a timing drive member which extends from the cam sprocket 65b and the cam sprocket of the intake camshaft shown in FIG. 6 to the timing sprocket 57e of the crankshaft 57. Consists of In addition, 69 is a balance axis. Note that the intake valve is omitted.

The head cover 46 has a projection 46a at the center.
And the inner surface of the convex portion 46a is
A breather chamber 55 is formed by closing the breather chamber b, and a guide member 71 for suppressing flutter of the timing chain 68 is attached to the lower surface of the breather plate 46b of the breather chamber 55. The breather plate 71 is attached to the head cover 46 with bolts B1 (only one is shown).

The guide member 71 is connected to the timing chain 6.
8, the timing chain 68 contacts only when the timing chain 68 rotates and flutters to suppress large fluttering, thereby preventing the timing chain 68 from stretching and generating abnormal noise. The guide member 71 is preferably made of a hard resin or rubber.

The lower case 42 has a protrusion 42j projecting laterally from the main bearing 42f. The protruding portion 42j has its upper end positioned below the timing chain 68 on the timing sprocket 57e of the crankshaft 57, and prevents the timing chain 68 from dropping from the timing sprocket 57e when the power unit 40 is assembled. Things.

Here, the engine 1 of the power unit 40
The procedure for assembling 0 will be described below in order. The cylinder block 44 is mounted on the upper case 41. Main bearings 41c, 41d, 41e, 41 of the upper case 41
The crankshaft 57 is temporarily fixed to f, 41g, and 41h. A connecting rod 58 to which a piston 62 is connected from the upper surface side of the cylinder block 44 is inserted into the inner surface of the cylinder liner 63 from the lower end, and the lower end of the connecting rod 58 is connected to the crankshaft 57.
Connect to

A cylinder head 45 to which an exhaust valve 67 and an intake valve (not shown) have been previously mounted is mounted on the upper part of the cylinder block 44. A timing chain 68 having both ends not connected to a timing sprocket 57e of the crankshaft 57 is hung.
From the outside. The lower case 42 is attached to the upper case 41.

A rocker arm 66 is attached to the cylinder head 45.
And the camshaft 65 is mounted. Both ends of the timing chain 68 are connected while the timing chain 68 is hung on the cam sprocket 65b of the cam shaft 65. The head cover 46 is mounted on the upper part of the cylinder head 45. Thus, the assembly of the engine 10 is completed.

By providing the projection 42j on the main bearing 42f of the present invention, the timing chain 68 does not come off from the timing sprocket 57e of the crankshaft 57 after the assembly of the timing chain 68 described in the above assembly procedure. In this case, the lower case 42 does not need to be attached or detached when it comes off, and the workability is not impaired. In addition, lower case 4
When casting 2 is manufactured by a casting method, compared with the case where a fall prevention member of the timing chain 68 is provided independently between the main bearings 42e and 42f of the crankshaft 57, a portion having a small thickness is not formed in the mold, and As a result, the life of the mold can be extended.

FIG. 6 is a sectional view taken along the line 6-6 in FIG. 4, showing the cam sprocket 65b of the cam shaft 65 for exhaust, the cam sprocket 72b of the cam shaft 72 for intake, and the crank shaft 57 of the cam shaft 57 attached to the cylinder head 45. The timing chain 68 is wrapped around the timing sprocket 57e, and the projection 42j provided on the lower case 42 is attached to the timing sprocket 5e.
7e, the chain guide 73 is brought close to the timing chain 68 between the cam sprocket 65b and the timing sprocket 57e, and the timing chain 68 between the cam sprocket 72b and the timing sprocket 57e.
Shows that the movable chain guide 74 is pressed by the chain tensioner 75 to bring the guide member 71 close to the cam chain 68 between the cam sprockets 65b and 72b.

The crankshaft 57 rotates in the direction of the arrow shown in FIG.
Then, the camshaft 72 for intake is rotated. Crankshaft 57
When the cam sprocket 65b rotates between the cam sprocket 65b and the timing sprocket 57e,
The timing chain 68 between the cam sprockets 72b and the timing sprocket 57e
The timing chain 68 between them is on the loose side.

The chain guide 73 suppresses the flapping of the timing chain 68, and the movable chain guide 74 stretches the timing chain 68 with a constant pressing force by pushing its back surface with a chain tensioner 75. .

Here, reference numeral 81 denotes an oil pump for supplying oil to each part of the engine 10 and the transmission 10a;
Reference numeral 2 denotes an oil pump drive chain that extends between an oil pump drive sprocket 57f (see FIG. 5) and an oil pump driven sprocket (not shown). Is a relief valve that opens when a predetermined pressure is reached, 85 is a main gallery that is a main oil passage extending in the direction of the crankshaft 57, 86 is an oil pass pipe that is an oil passage toward the transmission 10a, and 87 is an oil passage. Upper and lower oil path members 88 and 89 are a main shaft and a drive shaft for shifting the rotation transmitted from the crankshaft 57, and 91 is a fork member for moving a gear during shifting.

As described above, since the guide member 71 is mounted on the lower surface of the breather plate 46b of the head cover 46 shown in FIGS. 5 and 6, the mounting member of the guide member 71 is formed by the breather plate 46b forming the breather chamber 55. Therefore, a member for attaching the guide member 71 to the cylinder head 45 is not required, so that the number of parts can be reduced, and the number of assembling steps associated with this can be reduced. Further, the degree of freedom in layout of accessories for the cylinder head 45 and the head cover 46 can be improved.

The guide member 71 of the present invention shown in FIG.
8 can be reduced to the thickness of the conventional guide member 111 in FIG. 8, so that the amount of protrusion of the breather plate 46b upward from the center can be reduced, and the capacity of the breather chamber 55 can be increased. And the height of the upper surface of the head cover 46 can be suppressed.

[0026]

According to the present invention, the following effects are exhibited by the above configuration. In the OHC engine of the first aspect, a breather chamber for returning blow-by gas to the intake system is formed by closing a lower surface of a head cover attached to the cylinder head with a breather plate, and a guide member is attached to a lower surface of the breather plate in the breather chamber. Therefore, since the breather plate also serves as a mounting member for the guide member, a member for mounting the guide member to the cylinder head is not required, and the number of parts can be reduced, and the number of assembling steps associated with this can be reduced. Further, the degree of freedom in layout of other components in the cylinder head can be improved.

[Brief description of the drawings]

FIG. 1 is a side view of a motorcycle according to the present invention.

FIG. 2 is a plan view of the motorcycle according to the present invention.

FIG. 3 is a side view of a main part of the motorcycle according to the present invention.

FIG. 4 is a front view of a power unit according to the present invention.

FIG. 5 is a sectional view taken along line 5-5 in FIG. 3;

FIG. 6 is a sectional view taken along line 6-6 in FIG. 4;

FIG. 7 is a sectional view of a conventional engine.

FIG. 8 is a front view of a camshaft of a conventional engine.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Engine, 43 ... Crank case, 45 ... Cylinder head, 46 ... Head cover, 46b ... Breather plate, 55 ... Breather chamber, 57 ... Crank shaft, 65, 7
2 cam shaft, 68 timing drive member (timing chain), 71 guide member.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02F 7/00 F02F 7/00 P

Claims (1)

[Claims] 1. A timing drive member such as a timing chain is bridged between a camshaft provided on a cylinder head and a crankshaft provided on a crankcase, and a guide member for suppressing fluttering of the timing drive member is provided on the cylinder head. In the OHC engine, the lower surface of the head cover attached to the cylinder head is closed with a breather plate to form a breather chamber for returning blow-by gas to the intake system, and the guide member is attached to the lower surface of the breather plate in the breather chamber. OHC engine characterized by that.