JPH04342811A - Engine lubricating structure for outboard motor - Google Patents

Abstract

PURPOSE:To provide an engine lubricating mechanism of an outboard motor, which can rapidly return lubricant oil fed in a crank chamber, into an oil pan. CONSTITUTION:A crank chamber leading out part 61 of an engine easing communication passage 57 which is led from a crank chamber 20 and is communicated to a cam chamber 26 is laid in the outermost peripheral section of the crank chamber 20 which has a height the same as that of the center line C of a cylinder 31, and its leading-out direction is set in the rotating direction of a crank wheel 35, along the outer periphery of the crank wheel 35.

Description

[Detailed description of the invention]

[Object of the invention]

0002

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine lubrication structure for an outboard motor, and more particularly to an engine lubrication structure for an outboard motor in which lubricating oil supplied into a crank chamber is quickly returned to an oil pan.

0003

2. Description of the Related Art A typical outboard motor has an engine mounted vertically, and a drive shaft extending downward is connected to the lower end of an upright crankshaft. The lower end of this drive shaft is transmitted via a bevel gear or the like to a horizontally supported propeller shaft, and the propeller at the rear of the propeller shaft rotates underwater to obtain propulsive force.

[0004] When the engine of such an outboard motor is a four-cycle engine, the oil pump is usually located at the bottom of a vertically mounted crankshaft or camshaft, and is driven by either shaft. Lubricating oil is pumped up from the oil pan directly below and pumped to each part of the engine. Since the rotational speed of the camshaft is 1/2 slower than that of the crankshaft, the crankshaft is often used to drive the oil pump when increasing the discharge amount of the oil pump.

[0005] The lubricating oil discharged from the oil pump is applied to the engine case, crankshaft, camshaft,
The oil is supplied to the cam chamber and crank chamber through an oil supply path formed in a shaft such as a rocker shaft.

[0006] The lubricating oil supplied to the cam chamber lubricates the camshaft, valve mechanism, etc., and then flows down the cam chamber along the camshaft, and the oil flows through the cam chamber oil return hole provided at the bottom of the cam chamber. Back to bread.

The lubricating oil supplied to the crank chamber lubricates each journal bearing of the crankshaft, the large and small end bearings of the connecting rod, and the piston sliding surface of the cylinder, and then flows inside the crank chamber along the crankshaft. It flows down and returns to the oil pan through the crank chamber oil return hole provided at the bottom of the crank chamber.

[0008]

[Problem to be solved by the invention] However, when the oil pump is driven by the crankshaft as described above,
Since the oil pump and the above-mentioned crank chamber oil return hole are in almost the same position, there are restrictions on the position and size of the crank chamber oil return hole, and the shape makes it difficult for the lubricating oil in the crank chamber to return to the oil pan. I have no choice but to do so.

For this reason, especially in an in-line multi-cylinder outboard engine, the lubricating oil supplied to each lubricating part in the crank chamber tends to accumulate at the bottom of the crank chamber, and the bottom crank wheel is immersed in the lubricating oil. In some cases, this caused rotational resistance to the crankshaft. Therefore, the amount of lubricating oil supplied to the crank chamber cannot be increased very much, and the lubricating oil supplied to each lubricating section within the crank chamber tends to be insufficient.

Furthermore, since the crankshaft is upright, the lubricating oil flowing down from above the crank chamber hits the crank wheel rotating below and scatters, generating a mist of lubricating oil. This mist is difficult to condense because it continues to mix with the airflow in the crank chamber due to the high-speed rotating crank wheel, causing a delay in the return of oil to the oil pan.

[0011] In order to solve this problem, it is necessary to increase the distance between the inner wall of the crank chamber and the crank wheel so that the lubricating oil flowing down inside the crank chamber does not hit the crank wheel. This resulted in a disadvantage in terms of space for the outboard motor.

The present invention has been made in consideration of the above problems, and it is an object of the present invention to provide an engine lubrication structure for an outboard motor that can quickly return lubricating oil supplied into the crank chamber to the oil pan. purpose. [Structure of the invention]

[0013]

[Means for Solving the Problems] In order to achieve the above object, an outboard motor engine lubrication structure according to the present invention provides an outboard motor equipped with a four-stroke multi-cylinder engine with the crankshaft upright. In the engine lubrication structure, an engine case communication passage led out from the engine crank chamber and communicating with the cam chamber is provided, and the crank chamber outlet part of the engine case communication passage is connected to the crank chamber end at the same height as the cylinder centerline. It is installed on the outer periphery and its leading direction is along the tangent to the outer periphery of the crank wheel and in the direction of rotation of the crank wheel.

[0014]

[Operation] The lubricating oil flowing down along the crankshaft in the crank chamber hits the rotating crank wheel and is scattered in the tangential direction of the crank wheel due to the centrifugal force, and is applied to the inner wall of the crank chamber. Most of the lubricating oil applied to the inner wall of the crank chamber is pushed by the swirling air current generated within the crank chamber due to the rotation of the crankshaft, flows around the crank chamber wall surface, and flows into the engine case communication passage along with the air flow. The lubricating oil then enters the cam chamber, flows down along the camshaft, and quickly returns to the oil pan through the cam chamber oil return hole. Therefore, the amount of lubricating oil flowing downward within the crank chamber is reduced.

[0015] Furthermore, the lubricating oil that falls onto the rotating crank wheel and becomes a mist and mixes with the airflow in the crank chamber flows into the engine case communication passage along with the airflow.
It quickly condenses without being stirred by the crank wheel and returns to the oil pan.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the right side of an outboard motor equipped with an outboard motor engine lubrication structure according to the present invention.

The outboard motor 1 is made up of an engine 2, a drive shaft housing 3, and a propeller shaft housing 4. The engine 2 is fixed onto the drive shaft housing 3 via a substantially flat engine holder 5. ing. Further, a lower engine cover 6 is attached to the upper part of the drive shaft housing 3, and the lower engine cover 6 and the upper engine cover 7 cover the engine 2 from the outside.

The engine 2 is mounted vertically with a crankshaft 8 standing upright, and a drive shaft 9 extending downward is connected to the lower end of the crankshaft 8 by serrations or the like. The drive shaft 9 passes through the drive shaft housing 3 and reaches into the propeller shaft housing 4.

A propeller shaft 10 is horizontally supported in the propeller shaft housing 4, and the rear end of the propeller shaft 10 is connected to the propeller shaft housing 4.
The propeller 11 is attached to this protruding portion so as to rotate integrally therewith.

The drive shaft 9 and propeller shaft 10 are configured to rotate in conjunction with each other via a clutch mechanism 12 composed of, for example, a plurality of bevel gears.

This clutch mechanism 12 can switch the rotation of the drive shaft 9 using a clutch, and can maintain the propeller shaft 10 in normal rotation, reverse rotation, or in a stopped state.

A clamp bracket 13 is pivotally attached to the front edge of the drive shaft housing 3 so as to be rotatable left and right, and the clamp bracket 13 is hooked and fixed to a transom 14 (stern section) of the hull. The boat is steered by rotating the outboard motor 1 left and right.

FIG. 2 is a longitudinal sectional view of the outboard motor 2, and FIG. 3 is a sectional view taken along line A--A in FIG.

The engine 2 is a water-cooled, four-cycle gasoline engine with four cylinders arranged in-line, and is, for example, an SOHC four-valve type with two intake and two exhaust valves per cylinder.

The outer shell of the engine 2 is the cylinder block 1
5, a cylinder block 1 formed by a crankcase 16, a cylinder head 17, and a head cover 18;
5 and the cylinder head 17 are fixed to the engine holder 5 described above, and an oil pan 1 is provided at the bottom of the engine holder 5 so as to fit into the drive shaft housing 3.
9 has been installed.

Cylinder block 15 and crankcase 1
The space defined by 6 is four crank chambers 20, and a crankshaft 8 is rotatably supported by a crank bearing 21 formed at the joint surface between the cylinder block 15 and the crank case 16. . Each crank chamber 20 communicates with each other along the crankshaft 8 through communication holes 22, 23, and 24, and the lowermost crank chamber 20
A crank chamber oil return hole 25 communicating with the inside of the oil pan 19 is provided at the lower part of the engine.

Furthermore, the cylinder head 17 and the head cover 1
8 defines a cam chamber 26, and a cam shaft 29 is rotatably supported by a cam bearing 28 formed at the mating surface of the cylinder head 17 and the cam holder 27 (see FIG. 8). A cam chamber oil return hole 30 communicating with the oil pan 19 is provided at the lowest part of the cam chamber 26 .

The cylinder block 15 has a crank chamber 20.
Four cylinders 31 are formed which communicate with each other, into which a piston 32 is inserted reciprocably. A piston pin 33 is inserted into the piston 32, and this piston pin 33 is connected to the crank pin 3 eccentrically interposed between the crank wheel 35 of the crankshaft 8 by a connecting rod 34.
It is connected to 6.

Therefore, the reciprocating motion of the piston 32 is converted into a rotational motion of the crankshaft 8 by the connecting rod 34. The crankshaft 8 rotates the camshaft 29 at 1/2 rotation speed via the belt 37 and the like.

The combustion chamber 38 of the cylinder head 17 is provided with an intake port 40 opened by an intake valve 39 and an exhaust port 42 opened by an exhaust valve 41, and a spark plug 43 is arranged therein. has been done.

The camshaft 29 includes an intake cam 44.
and an exhaust cam 45 are integrally formed to rotate, and the intake cam 44 and the exhaust cam 45 are connected to an intake rocker arm 48 which is swingably supported by two rocker shafts 46, 47 supported by a cam holder 27, and an exhaust cam 45. rocker arm 49
the intake valve 39 and the exhaust valve 41 via,
A valve is opened in a combustion chamber 38 at a predetermined timing in a four-cycle engine. Then, as the piston 32 descends, the mixture of gasoline and air flows into the cylinder 31 from the intake port 40.
The exhaust gas that is supplied into the exhaust gas after the combustion of the air-fuel mixture is discharged from the exhaust port 42 as the piston 32 rises.

The piston 32 is pressed by the explosive force during combustion of the air-fuel mixture, and this force becomes the rotational force of the crankshaft 8.

An intake manifold 50 also shown in FIG. 4 is connected to the outside of the intake port 40. The bases of the four intake manifolds 50 are assembled into a surge tank 51.
A throttle body 53 having a butterfly type throttle valve 52 is connected to the surge tank 51. The amount of air supplied to the intake manifold 50 is adjusted by the opening degree of the throttle valve 52. Further, a fuel injection device 54 is installed at a portion of the intake manifold 50 closest to the engine 2, and injects gasoline into the air supplied from the intake manifold 50 to generate an air-fuel mixture.

[0035] The exhaust port 42 is connected to the cylinder block 15.
The exhaust passage 5 is connected to an exhaust passage 55 formed on one side of the exhaust passage 5.
5 extends downward and is connected to an exhaust tube (not shown) disposed within the drive shaft housing 3. The exhaust gases are then discharged through these passages, for example into water.

A water jacket 56 is formed around the exhaust passage 55 and the cylinder 31 and above the combustion chamber 38, through which water taken in from the outside of the outboard motor 1 flows. and combustion chamber 3
8 is water cooled.

3 and 4 show an engine case communication passage 57 which is an embodiment of the present invention. This engine case communication passage 57 is arranged so as to lead out from the crank chamber 20 and communicate with the cam chamber 26.

The engine case communication passage 57 is formed by connecting unions 58 and 59 protruding from the outer walls of the crank chamber 20 and the cam chamber 26 with a hose 60 made of heat-resistant and oil-resistant rubber, and the hose 60 is connected to the intake manifold. It passes between 50 and 50.

The union 58 corresponding to the crank chamber outlet portion 61 of the engine case communication passage 57 is connected to the cylinder 3.
It is installed at the outermost periphery of the crank chamber 20 immediately beside the center line C of the crankshaft 1, and its leading direction is along a tangent to the outer periphery of the crank wheel 35 and is oriented in the rotation direction R of the crank wheel 35.

A breather chamber 63 partitioned by a partition plate 62 is formed within the head cover 18 . A breather pipe 64 extends from the upper part of the breather chamber 63 and is connected to the surge tank 51, for example.

Note that 65 in FIG. 3 is an oil filter.

An oil pump 66 is installed at a portion where the crankshaft 8 protrudes from the crank chamber 20 and is connected to the drive shaft 9. The oil pump 66 is, for example, a general trochoid pump, and is attached to the joint surface between the cylinder block 15 and the crankcase 16, through which the crankshaft 8 passes.

The casing 67 of the oil pump 66 includes:
An oil strainer 69 fixed so as to be submerged in lubricating oil 68 stored in the oil pan 19 is connected by an oil pipe 70.

The structure of the oil pump 66 is shown in FIGS. 5 and 6.
(A sectional view taken along the line B-B in FIG. 5). Inside the casing 67 is an external gear-shaped inner rotor 71 that rotates integrally with the crankshaft 8, and which meshes with the inner rotor 71.
An internal gear-shaped outer rotor 72 that rotates in the same direction as the inner rotor 71 is arranged. Regarding the number of teeth of each rotor 71, 72, the inner rotor 71 has one fewer tooth than the outer rotor 72, for example, the inner rotor 71 has four teeth and the outer rotor 72 has five teeth. Therefore, a gap serving as an oil carrying chamber 73 is formed between the inner rotor 71 and the outer rotor 72.

The oil pipe 70 is installed in the casing 67.
A suction passage 75 extending from a suction hole 74 connected to the upper part and a discharge passage 77 connected to a discharge hole 76 provided at the upper part are formed, and the suction passage 75 and the discharge passage 77 are connected to the inner rotor 71 and the outer rotor A fan-shaped suction port 78 and a fan-shaped discharge port 79 are formed in the lower part of the crankshaft 8 so as to surround each half of the circumference of the crankshaft 8 . These suction passage 75, discharge passage 77, suction port 78, and discharge port 79 are filled with lubricating oil.

The inner rotor 11 and the outer rotor 72 are driven by the crankshaft 8 and rotate (
6), the volume of the oil carrier chamber 73 expands at the position of the suction port 78 and decreases at the position of the discharge port 79. Therefore, the lubricating oil in the suction port 78 is sucked into the oil carrier chamber 73, conveyed to the discharge port 29, and discharged. In this way, the lubricating oil continuously enters the suction hole 74 and is discharged from the discharge hole 76.

Note that a hole 80 formed in the middle of the discharge path 77
is a relief oil flow path connected to a relief valve (not shown) that limits the discharge pressure of the oil pump 66 to a constant value. Further, reference numerals 81 and 82 are oil pump through holes for returning lubricating oil from the crank chamber 20 to the oil pan 19.

7 and 8 show the lubricating oil supply system within the engine 2.

An oil supply passage 8 is provided in the cylinder block 15 at a position where the discharge hole 76 of the oil pump 66 coincides with the oil supply passage 8.
3 is formed. The oil supply path 83 is connected to a main gallery 84 parallel to the crankshaft 8, and an oil filter 65 is interposed therebetween.

A crank lubricating oil passage 85 communicating with the crank bearing 21 and a cam lubricating oil passage 86 communicating with the cam chamber 26 are branched from the main gallery 84 .

The cam lubricating oil flow path 86 enters the aforementioned cam holder 27 and communicates with the rocker shaft 47, the cam bearing 28, and the rocker shaft 46 in this order, for example. The rocker shafts 46 and 47 have a hollow pipe shape, and the hollow portions thereof serve as rocker shaft lubricating oil passages 87 and 88, and are located at positions lined up with the suction and exhaust cams 44 and 45 of the camshaft 29, and the suction and exhaust rocker arms 48. , 49 are provided with lubricating oil ejection holes 89 and 90.

The lubricating oil discharged from the discharge hole of the oil pump 66 flows into the oil supply path 83, passes through the oil filter 65, is purified by the filter element 91, and then flows into the main gallery 84, where it flows into the crank lubricating oil flow path. 85 and a cam lubricating oil flow path 86 .

The lubricating oil that has flowed into the crank lubricating oil flow path 85 is supplied to the crank bearing 21 to lubricate the crankshaft 8, and also enters the crank pin lubricating oil flow path 92 formed inside the crank wheel 35 to supply the crankshaft 8. After lubricating between the pin 36 and the connecting rod 34, it is scattered into the cylinder 31 by the centrifugal force of the rotating crank wheel 35, and lubricates between the cylinder 31 and the piston 32 and between the connecting rod 34 and the piston pin 33. conduct.

On the other hand, the lubricating oil that has flowed into the cam lubricating oil passage 86 flows into the rocker shaft lubricating oil passages 87 and 8.
8 and the cam bearing 28, and lubricates the camshaft 29, as well as being ejected from the lubricating oil injection holes 89, 90, and is supplied to the suction and exhaust cams 44 and 45, and the suction and exhaust rocker arms 48.
, 49 and between the rocker shafts 46, 47 and the suction and exhaust rocker arms 48, 49.

FIG. 9 shows the route through which lubricating oil supplied to each part of the engine 2 returns to the oil pan 19.

First, the lubricating oil supplied to the cam chamber 26 falls along the camshaft 29 and returns to the oil pan 19 through the cam chamber oil return hole 30 at the bottom of the cam chamber 26 .

Furthermore, the lubricating oil supplied to the cylinder 31 and the crank chamber 20 falls along the crankshaft 8 through the communication hole 24, etc., and hits the rotating crank wheel 35 on the way, as shown in FIG. It scatters in the tangential direction of the crank wheel 35.

By the way, at the outermost periphery of the crank chamber 20, which is at the same height as the center line C of the cylinder 31, the crank chamber lead-out portion 61 of the engine case communication passage 57 is located along a tangent to the outer periphery of the crank wheel 35, and
Since the crank chamber 2 is installed facing the rotation direction R of the crank wheel 35, the crank chamber 2 turns along the rotation direction R of the crank wheel 35.
The airflow in the engine 0 constantly flows into the crank chamber outlet portion 61 at a high speed.

Therefore, as described above, most of the lubricating oil that has been scattered and adhered to the inner wall of the crank chamber 20 is pushed by the airflow and advances toward the crank chamber outlet portion 61, and flows into the crank chamber outlet portion 61 along with the air flow. The oil then flows through the engine case communication passage 57 to the cam chamber 26, drops downward, and returns to the oil pan 19 through the cam chamber oil return hole 30.

As shown in FIG. 4, the engine case communication passage 5
Since the union 59 of No. 7 is installed at a lower location than the union 58, the engine case communication passage 57 is connected to the union 58.
The shape is such that the lubricating oil passing through the interior quickly flows to the cam chamber 26.

A part of the lubricating oil supplied to the crank chamber 20 falls to the lowest part of the crank chamber 20 through the communication hole 24 and the like, and collects in the crank chamber oil return hole 25. In this embodiment, since the oil pump 66 is driven by the crankshaft 8, the crank chamber oil return hole 2
5 is located directly above the oil pump 66, and there are restrictions on its position and shape, and the lubricating oil that has passed through the crank chamber oil return hole 25 is a small oil provided in the oil pump 66. Pump through holes 81, 8
2 and return to the oil pan 19, this is by no means an efficient flow path for returning to the oil pan 19, but most of the lubricating oil supplied to the crank chamber 20 flows through the engine case communication path mentioned above. Cam room 2 via 57
6, the lubricating oil that falls to the lowest part of the crank chamber 20 is very small and does not accumulate in the crank chamber 20.

For this reason, there is no risk that the lowest crank wheel 35 will be immersed in a pool of lubricating oil, creating rotational resistance for the crankshaft 8, or slowing down the return of lubricating oil to the oil pan 19.

Therefore, there is no need to limit the amount of lubricating oil supplied to each lubricating section within the crank chamber 20, and a good lubrication state can be obtained.

Further, some of the lubricating oil that has changed into mist by falling onto the rotating crank wheel 35 is carried by the airflow in the crank chamber 20 and sent to the engine case communication passage 57, The inside of the engine case communication passage 57 and the cam chamber 2 are protected from being rotated.
6, and can quickly condense in the breather chamber 63 and return to the oil pan 19.

[0065] Because of this effect, the crank chamber 2
It is not necessary to provide a large distance between the inner wall surface of the crank chamber 20 and the crank wheel 35 so that the lubricating oil flowing down inside the engine does not fall onto the crank wheel 35, and the crank chamber 20 can be narrowed to create a compact engine. can.

In this embodiment, the engine case communication passage 57 corresponding to the cylinder 31 and the crank wheel 35 at the bottom of the engine 2 is not provided. This is because the lowermost cylinder 31 and crank wheel 35 are close to the crank chamber oil return hole 25.

As described above, the cylinders in which the engine case communication passages are installed and the number of cylinders installed may be arbitrarily selected depending on the lubrication condition of the engine.

Furthermore, the present invention is applicable not only to outboard engines but also to four-stroke engines in other fields in which the crankshaft is arranged upright. Furthermore, it may be applied to an engine having a V-shaped or horizontally opposed cylinder arrangement.

[0069]

As explained above, the engine lubrication structure for an outboard motor according to the present invention includes an engine case communication passage led out from the crank chamber and communicating with the cam chamber. The crank chamber lead-out part is installed at the outermost periphery of the crank chamber at the same height as the center line of the cylinder, and the direction of the lead-out part is along the tangent to the outer circumference of the crank wheel and in the direction of rotation of the crank wheel. The lubricating oil that falls onto the rotating crank wheel and is scattered on the surrounding crank chamber wall surface due to centrifugal force is carried to the engine case communication passage by the air flow inside the crank chamber rotating in the same direction as the crank wheel, and is carried to the engine case communication passage along with the air flow. It flows into the case communication passage, passes through the cam chamber, and returns to the oil pan. For this reason, in engines where the oil pump is interposed between the crank chamber and the oil pan, such as outboard engines equipped with a crankshaft-driven oil pump, the lubricating oil in the crank chamber is difficult to return to the oil pan. The lubricating oil in the crank chamber can also be quickly returned to the oil pan. Therefore, there is no need to limit the amount of lubricating oil supplied to each lubricating section in the crank chamber, and a good lubrication state can be obtained.

Furthermore, the lubricating oil drifting in the form of mist within the crank chamber flows into the engine case communication passage along with the airflow within the crankcase, where it can quickly solidify and return to the oil pan.

[Brief explanation of drawings]

FIG. 1 is a right side view of an outboard motor equipped with an outboard motor engine lubrication structure according to the present invention.

FIG. 2 is a longitudinal sectional view of the engine.

FIG. 3 is a sectional view taken along line A-A in FIG. 2, showing one embodiment of the present invention.

FIG. 4 is a side view showing one embodiment of the present invention.

FIG. 5 is a longitudinal sectional view showing the structure of the oil pump.

FIG. 6 is a sectional view taken along line BB in FIG. 5;

FIG. 7 is a side view showing a lubricating oil supply system within the engine.

8 is a view taken along arrow D in FIG. 7. FIG.

FIG. 9 is a diagram showing a route of lubricating oil returning to the oil pan.

[Explanation of symbols]

2 Engine 8 Crankshaft 20 Crank chamber 26 Cam room 29 Camshaft 31 Cylinder 35 Crank wheel 57 Engine case communication passage 61　Crank chamber lead-out part

Claims (1)

[Claims] Claims: 1. An engine lubrication structure for an outboard motor equipped with a four-stroke multi-cylinder engine with a crankshaft standing upright, including an engine case communication passage led out from a crank chamber of the engine and communicating with a cam chamber. The crank chamber lead-out portion of this engine case communication passage is installed at the outermost periphery of the crank chamber at the same height as the cylinder center line, and its lead-out direction is along the tangent to the outer circumference of the crank wheel, and the direction of the lead-out part is set along the tangent to the outer circumference of the crank wheel. An outboard motor engine lubrication structure characterized by being oriented in the direction.