JP3052255B2 - Camshaft drive mechanism for 4-cycle outboard motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an outboard motor having an engine mounted above a propulsion unit and arranged in a cowling, and more particularly to a wrapping device for driving a valve train of a four-cycle outboard motor. It relates to a belt tensioner.

[0002]

2. Description of the Related Art In a conventional four-stroke outboard motor, for example, as shown in Japanese Patent Application Laid-Open No. 58-178816, a drive wheel and a cylinder head fixed to a vertical crankshaft supported by a cylinder case of an engine. There is a type in which a wrapping belt is simply stretched between a driven vehicle fixed to a cam shaft supported by a camshaft. The installation of a tensioner on a wrap belt is also generally known in other technical fields.

[0003]

However, in the winding belt disclosed in the above publication, since no tensioner is provided, there is a possibility that the winding belt may become loose and power from the crankshaft may not be reliably transmitted to the camshaft. is there. Therefore, it is conceivable to install a tensioner on the wrapping belt. At this time, it is necessary to determine a position where the tensioner is installed in order to make the cowling compact and how to reduce a thermal influence in the cowling. It becomes a problem.

The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to reduce the protrusion of the tensioner from the cylinder case and to minimize the heat effect. It is an object of the present invention to provide a four-cycle outboard motor which is compact and has few thermal troubles.

[0005]

In order to achieve the above object, a camshaft driving mechanism for a four-stroke outboard motor according to the present invention comprises a crankshaft-side pulley, a camshaft-side pulley, and a tension.
Consists of tio na, a cam shaft supported by the vertical crankshaft and the cylinder head is supported by the cylinder casing of the engine is disposed along a substantially central axis of the cowling, a small diameter of the drive which is fixed to the crankshaft A winding belt is stretched over a wheel and a large-diameter driven wheel fixed to the camshaft, and the tensioner of the winding belt in a plan view is moved on the crankshaft side having a small-diameter driving wheel. , Cylinder body on cylinder side and crankshaft side
And the cylinder shaft arranged on the side of the
An intake passage extending in a straight line in parallel and approximately in the cowling
Is positioned between the mandrel wire, it is characterized in that provided and towards the outside of the wrapping belt inward.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to an embodiment shown in the drawings.

FIG. 1 to FIG. 9 show an embodiment of the present invention, in which an engine 10 for an outboard motor is provided on an exhaust casing 1 on an upper casing 12 of a propulsion unit.
In this embodiment, the exhaust guide 14 is composed of upper and lower exhaust guide plates 14A and 14B.

The upper casing 12 is supported by a swivel bracket 16, and the swivel bracket 16 is rotatable left and right by a steering handle 18 integrated with a pivot shaft 17 and is steered. The swivel bracket 16 is vertically rotatably supported by a clamp bracket 20 via a tilt shaft 19, and the clamp bracket 20 is fixed to a stern plate 21 of the hull.

Reference numeral 22 denotes a lower casing, and a propeller 23
The propeller shaft 24 is provided with a drive shaft 2 depending from the engine 10 via the upper casing 12.
5 through a gear group 26 for shifting. Reference numeral 27 denotes a water intake, which sucks seawater by a cooling water pump 28 driven by a drive shaft 25 and supplies the seawater to the engine 10 as cooling water.

Reference numeral 29 denotes a mount support bolt attached to the steering handle 18, and this mount support bolt 29 is fitted by a mount rubber 30 as shown in FIG. The mount rubber 30 is sandwiched between an exhaust guide plate 14B of the exhaust guide 14 and a fixing bracket 31 fixed to the plate 14B by mounting bolts 32. Thereby, both plates are fixed to each other by the mounting bolts 32.

As a result, the engine 10, the upper case
The weights of the sing 12 and the lower casing 22 are transmitted from the steering handle 18 via the mount supporting bolts 29 to the clamp bracket 20 via the swivel bracket 16 and the pivot shaft 17.

An exhaust guide plate 14A of the exhaust guide 14 has a function of partitioning an oil receiver for storing oil from a crank chamber, which will be described later, and the exhaust guide plate 14B has a mounting support bolt 29. And a function of partitioning a mount structure including the above and an exhaust expansion chamber described later.

Reference numeral 34 denotes an oil tank which is conventionally disposed in the upper casing 12, and is mounted on the engine 10 and stored in the cowling 35 in this embodiment. Therefore, the exhaust from the engine 10 is exhaust
The exhaust pipe 37 extends from the exhaust passage 36 formed in the strike guide 14.
And is expanded in an expansion chamber 38 having a sufficiently large volume because the oil tank 34 does not exist. After being silenced here, it descends in the lower casing 22 and the boss of the propeller 23 It is discharged into water from an exhaust outlet 39 formed in the section.

The exhaust gas passing through the exhaust passage 36 and the exhaust pipe 37 is cooled by a water jacket 40 through which the cooling water after cooling the engine 10 passes, and the exhaust gas passing through the expansion chamber 38 is cooled by the upper casing 12. Inside the muffler 47 which is housed inside and forms an expansion chamber,
The thing 12 is cooled by cooling water passing through a water jacket 41 formed by the weir wall 12A. Reference numeral 42 denotes a small hole of the water jacket 40, and reference numeral 43 denotes a small hole of the water jacket 41.

Exhaust gas when the engine is idling is discharged from an exhaust pipe 37 and an exhaust expansion chamber 38 through an exhaust small hole 44.
Then, the air is introduced into a sub-exhaust passage 45 formed by a muffler 47, expanded and muffled, and then discharged into the air from an idle exhaust outlet 46.

As shown in FIGS. 3 to 5, the engine 1
The oil tank 34 disposed on the port side of the port 0 is provided with an inlet cap 49 at an oil inlet 48, and the lower end of the inlet cap 49 extends below and serves as an oil level gauge. Function. A screen 51 is disposed below the oil tank 34, and has a function of preventing air bubbles in the oil from flowing downward.

Reference numeral 52 denotes an oil outflow pipe, which communicates with an oil pump 53 in which an oil feed pump and a lubrication pump are combined. The pump shaft 54 of the oil pump 53 is shown in FIGS.
As shown in FIG. 5, a driving gear 56 fitted to a vertically disposed crankshaft 55 meshes with a driven gear 57, and the driven gear 57 rotates a driving shaft 58 that drives the pump shaft 54, thereby rotating the crankshaft 55. Is done.

Referring also to FIG. 9 showing a hydraulic circuit of the lubricating oil, lubricating oil from an oil outlet pipe 52 of an oil tank 34 is driven by a pump shaft 54 of an oil pump 53 to be driven by an oil pump. The lubrication pump 59 of the pump 53 is pumped upward to the oil supply gallery 61 via the preset valve 60. The preset valve 60 functions as a check valve for preventing the flow of oil from the oil tank 34 to the engine by the preset load when the engine is stopped horizontally.

The oil is sent from the oil supply gallery 61 to the oil filter 62, where it is filtered again, and then distributed via the distribution gallery 63 to the bearings of the various parts of the engine, such as the bearings of the crankshaft 55 ( See FIG. 8). A relief valve 64 is arranged in the oil supply gallery 61 to keep the pressure of the supply line of the lubricating oil from the lubrication pump 59 constant (see FIGS. 3 and 8).

After lubricating the bearings and the like of the crankshaft 55, the oil flows through the flow passage 65 and the camshaft 66 as shown in FIG.
After lubricating each component in the cylinder head cover 67, the oil is accumulated in an oil receiver 70 provided below the crank chamber 68 via a screen 69. The oil from the oil receiver 70 is returned to the oil pump 53 again.
The oil is returned to the oil tank 34 through an oil return passage 71 via a check valve 73 by an oil feed pump 72 driven by a pump shaft 54 of the pump.

The check valve 73 has a function of preventing oil from flowing backward from the oil tank 34 when the engine 10 is placed horizontally (see FIG. 7). As shown in FIG. 3, the returned oil rises from the oil return passage 71 and is discharged from the discharge port 74 which opens slightly upward from the center in the up-down direction in the oil tank 34, thereby being discharged and circulated. Care is taken to separate the air bubbles inside.

The oil feed pump 72 is provided with an oil receiver 70.
When the amount of accumulated oil in the oil tank is small, the air may be sucked and sent into the oil tank 34, and the ventilation passage 75 for letting the air in the oil tank 34 escape into the cylinder head cover 67. Are arranged (see FIG. 5).

In FIGS. 1 and 3 to 5, the vertical crank shaft 55 supported by the cylinder case 80 of the engine 10 and the cam shaft 66 supported by the cylinder head 78 are substantially aligned with the center axis of the cowling 35. A relatively small-diameter drive wheel 85 is fixed to the crankshaft above a cylinder case 80, and a camshaft 66 supported by the cylinder head 78 is attached to the cylinder head 78. A relatively large-diameter driven wheel 86 is fixed above. The driving vehicle 85 and the driven vehicle 8
A winding belt 87 is stretched between the six. Further, a tensioner 88 for adjusting the tension of the winding belt 87 is provided.
Is a crankshaft 5 having a small diameter drive wheel 85 in plan view.
5 side, the cylinder body on the cylinder side and the crankshaft 55 side
And the cylinder shaft arranged on the side of the
The intake passage 89 extending straight and parallel to the cowling 3
5 , and is provided from the outside to the inside of the winding belt 87 and stands upright from the cylinder head 78.

As described above, the small-diameter drive wheel 8 fixed to the vertical crankshaft 55 supported by the cylinder case 80
5 and a large-diameter driven wheel 86 fixed to a cam shaft 66 supported by a cylinder head 78, a winding belt 87 is stretched,
The tensioner 88 of the winding belt 87 is connected to the small-diameter drive wheel 8.
5 on the side of the crankshaft 55, the cylinder side and the crankshaft.
Around the cylinder body on the shaft 55 side,
Since the tensioner 88 is located between the intake passage 89 extending linearly substantially in parallel with the cylinder axis and the substantially central axis of the cowling 35 , the tensioner 88 is prevented from protruding from the cylinder case 80. Since the projecting side of 88 is the intake passage 89, it is less affected by heat, and the tensioner 88 is located near the small diameter side.
, The overall length of the wrapping belt 87 can be reduced. In addition, the tensioner 88 is a belt
Is provided from the outside to the inside, so that the winding belt 87 is prevented from protruding from the cylinder case 80 and is substantially accommodated in the upper surface area of the cylinder case 80, and the winding belt 87 and surrounding devices are Interference can be avoided. The tensioner 88 is a flywheel mug.
It is located below the net 77.

[0025] Note also, the fuel pump 79, 81 is a piston, 82 is a carburetor located in the intake passage 85 carburetor
82 is the tension as apparent from FIG.
Lower than the screwdriver 88 and may interfere with the tensioner 88.
And not. Further, 83 electric motor for starting, 84 is an oil surface when placing the outboard motor sideways.

[0026]

According to the present invention, the camshaft drive mechanism is
The pulley on the link shaft, the pulley on the camshaft and the tensioner
Made which, placed along the cam shaft supported by the vertical crankshaft and the cylinder head is supported by the cylinder casing in a substantially central axis of the cowling, said a fixed diameter of the drive wheel on the crankshaft camshaft stretched the driven wheel and wound hanging belt fixed large diameter was in the tensioner of the winding hanging belt in plan view, the crank shaft side with a small diameter drive wheel, cylindrical
Over the cylinder body on the
Linearly extend substantially parallel to the cylinder axis located on the side of the
Since it was positioned between the intake passage and substantially central axis of the cowling that can tensioner forms compactly cowling that is suppressed protruding from the cylinder case, also protruding side of the tensioner in the intake passage since there can be reduced even less thermal problems that affected by heat, and further because the position tensioner closer to the small diameter side, corner and shorter overall length of the wrapping belts, moreover, Since the tensioner is provided from the outside to the inside of the winding belt, the winding belt is prevented from protruding from the cylinder case, and interference with surrounding devices can be avoided. It becomes the camshaft drive mechanism of the outboard motor.

[Brief description of the drawings]

FIG. 1 is a side view showing an outboard motor to which the present invention is applied.

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIG. 3 is an enlarged sectional view showing a main part of FIG. 1;

FIG. 4 is a sectional view showing the inside of the engine of FIG. 1;

FIG. 5 is an enlarged plan view showing a part of FIG. 1 with a cutout;

FIG. 6 is a sectional view taken along the line VI-VI in FIG. 3;

FIG. 7 is a sectional view taken along the line VII-VII in FIG. 3;

FIG. 8 is a sectional view taken along the line VIII-VIII in FIG. 3;

FIG. 9 is a circuit diagram of a lubricating oil.

[Explanation of symbols]

 Reference Signs List 10 engine 35 cowling 55 crankshaft 66 camshaft 78 cylinder head 80 cylinder case 85 driving wheel 86 driven wheel 87 wrapping belt 88 tensioner 89 intake passage

Claims (1)

(57) [Claims] 1. A crankshaft for an outboard motor having an engine mounted above a propulsion unit and arranged in a cowling.
Side pulley, camshaft side pulley and tensioner
In a camshaft drive mechanism , a vertically installed crankshaft supported by a cylinder case of the engine and a camshaft supported by a cylinder head are arranged along a substantially central axis of a cowling, and a small diameter fixed to the crankshaft. And a large-diameter driven wheel fixed to the camshaft, and a tension belt of the loop is driven by a small-diameter drive in plan view.
On the crankshaft side with the car , the cylinder side and the crankshaft side
Is located on the side of the cylinder body
The mosquitoes an intake passage extending substantially parallel straight cylinder axis
It is positioned between the substantially central axis of the cowling, and the wrapping belt 4 cycles outboard motor of the cam shaft drive mechanism from the outside, characterized in that provided inward of.