JPH0623529B2 - Overhead valve type engine lubricator - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to an overhead valve engine without an oil pump, and more particularly to a lubricating device for lubricating around a valve mechanism located on the piston head side of the engine.

[Technical background of the invention and its problems]

Conventionally, as a lubricating device for this type of engine, a splasher that rotates with the crankshaft stirs and splashes the lubricating oil that has accumulated in the bottom of the crank chamber. It is known to use blow-by gas that blows into the crank chamber from the gap to guide it into the valve operating chamber inside the cylinder head to lubricate the rocker arm and rocker shaft in this valve operating chamber, that is, the valve operating mechanism. .

By the way, recent engines have taken measures to enhance the sealing function of the pistons, not to mention exhaust gas measures, but to improve fuel efficiency and suppress deterioration of oil. However, if such measures are taken, the blow-by gas blown into the crank chamber is drastically reduced. As a result, the amount of oil introduced around the valve mechanism also decreases, and the oil supply becomes unstable.

For this reason, recently, the cylinder was laid almost horizontally, and the opening of the return passage connecting the crank chamber and the valve operating chamber was made to face the position where the splasher splashes the lubricating oil. An engine designed to directly hit the valve train is being considered.

However, in such an engine, the arrangement of the cylinders may be greatly restricted due to the relationship of the direction in which the lubricating oil is spattered, and the engine structure and design freedom may be lost.

[Object of the Invention]

The present invention has been made based on such a situation, and it is possible to stably supply the lubricating oil to the valve operating mechanism. Further, the arrangement of the cylinders is not restricted, and the degree of freedom in structure and design is increased. It is an object of the present invention to provide a lubricating device for an overhead valve type engine that can increase intake air and can sufficiently suck the outside air into the crank chamber when the piston moves up without the operability of the check valve being hindered by the lubricating oil.

[Outline of Invention]

In order to achieve the above object, according to the present invention, an intake valve, an exhaust valve, and a valve mechanism for opening and closing both valves are arranged on the side of the piston facing the piston head, and the valve mechanism is housed. The valve operating chamber and the crank chamber in which the cylinder containing the piston is connected are communicated with each other through a return path, and the crank chamber rotates in conjunction with the crankshaft, so that the bottom portion of the crank chamber A splasher that stirs and splashes the lubricating oil that has accumulated in the valve is housed. It is premised on an overhead valve type engine which is designed to perform lubrication around the valve mechanism.

Then, the valve operating chamber is communicated with the outside air through the breather port, and the valve operating chamber and the crank chamber are communicated with each other through a communication passage and an outside air introducing passage different from the return passage, The opening of the communication passage to the crank chamber is provided at a portion where the lubricating oil is splashed by the splasher, and the opening of the communication passage to the valve operating chamber is provided in the vicinity of the lubricated portion of the valve operating mechanism. Further, the opening to the valve operating chamber of the outside air introducing passage is provided in the upper wall of the valve operating chamber, and in the middle of the outside air introducing passage, a check valve that allows only the flow from the valve operating chamber toward the crank chamber is provided. The feature is that it is provided.

Example of Invention

The present invention will be described below based on an embodiment shown in the drawings.

3 and 4 show a small vehicle such as a golf car equipped with the engine according to the present invention, in which 1 is a body frame. Left and right front wheels 2 and 2 on the front of the body frame 1.
Is supported, and a swing arm 3 extending rearward is swingably supported on the body frame 1. The swing arm 3 is suspended from the vehicle body frame 1 via springs 4 and 4 and a hydraulic shock absorber 5, and the swing arm 3 supports left and right rear wheels 7 and 7 via rear wheels 6. And the rear wheels 7,7
A drive system 8 for traveling for driving the vehicle is attached. The body frame 1 is covered with a body 9, and a traveling drive system 8 is housed in a space below the seat 10 provided on the body 9.

By the way, the drive system 8 for traveling mainly comprises an overhead valve engine 11 according to the present invention and a power transmission mechanism 13 for transmitting the power of the engine 11 to the final reduction gear 12 on the rear wheels 6. About the details of 11 First
A description will be given with reference to FIG. 2 and FIG.

That is, reference numeral 14 in FIG. 1 is a crankcase, and a cylinder block 15 is erected on the upper surface of the crankcase in a slightly inclined state. Crank chamber 16 in cylinder block 15
Cylinder 17 connected to the cylinder 17 is formed.
A piston 18 that reciprocates inside and a crankshaft 19 housed in the crank chamber 16 are connected by a connecting rod 20. And, the crankshaft in the crank chamber 16
Balancer shaft 51 that is driven to rotate by power transmission from 19
The cam shaft 22 is housed and supported. On the lower surface of the connecting rod 20, a splasher 21 extending downward is provided.
Is fixed, and this splatter 21
The lubricating oil stored in the bottom portion of the crank chamber 16 is agitated with the rotation of the crank chamber 16 and is splashed toward the inner surface of the upper portion of the crank chamber 16 as indicated by the arrow in FIG. In addition, L in FIG. 1 indicates the oil level of the lubricating oil.

A cylinder head 23 is fitted on the upper surface of the cylinder block 15. This cylinder head 23 and piston 1
A combustion chamber 24 is formed between the No. 8 piston head 18a and an intake port 25 and an exhaust port (not shown) are opened in the combustion chamber 24. An intake pipe 37 is connected to the intake port 25 as shown in FIGS. 3 and 4, and the intake pipe 37 is guided toward the front of the engine 11 and an air cleaner 38 via a carburetor 38.
It is connected to 39. Further, an exhaust pipe 40 extending rearward of the engine 11 is connected to the exhaust port, and a rear end of the exhaust pipe 40 is connected to a silencer 41. The intake port 25 and the exhaust port are opened and closed by an intake valve 26 and an exhaust valve (not shown), respectively. The intake valve 26 and the exhaust valve are the piston head.
18a and its valve stem 26a
Are led out into a valve operating chamber 28 provided between the cylinder head 23 and the head cover 27. A rocker shaft 29 is supported in the valve operating chamber 28, and this rocker shaft 29 has:
A rocker arm 30 that operates the intake valve 26 and the exhaust valve is swingably attached. The rocker arm 30 is connected to the cam shaft via the push rod 31 and the tappet 32.
The push rod 31 of this embodiment is interlocked with 22 and is inserted through a return passage 33 formed in the cylinder block 15 and the cylinder head 23. The return path 33 connects the crank chamber 16 and the valve operating chamber 28, and is opened at the bottom of the valve operating chamber 28. The rocker arm 30 and the rocker shaft are
It serves as both a return passage for oil that lubricates 29 and a flow passage for blow-by gas blown into the crank chamber 16.
Therefore, in the case of the engine 11 of this embodiment, the rocker shaft 29, the rocker arm 30, and the bush rod 31 form the valve mechanism 34.

The circumference of the cylinder block 15, the cylinder head 23, and the head cover 27 is covered with an air shroud 35. Outside air is sent into the air shroud 35 by a blower fan (not shown), and this outside air is forced around the cylinder. After air cooling, the air is discharged from an exhaust hole 36 formed in the rear surface of the air shroud 35.

On the other hand, in such an engine 11, the crank chamber
Between the valve 16 and the valve operating chamber 28, a communication passage 42 different from the return passage 33 is provided.
And it is connected via the outside air introduction path 43. The open end 42a of the communication passage 42 to the crank chamber 16 is located on the upper surface of the crank chamber 16 to which the lubricating oil splashed by the splasher 21 is introduced, and
An open end 42b of the communication passage 42 to the valve operating chamber 28 is located close to a lubricated portion of the valve operating mechanism 34, that is, a contact portion between the rocker arm 30 and the valve stem 26a to be lubricated with lubricating oil. .

Further, the open end 43 of the outside air introduction passage 43 to the crank chamber 16
a is adjacent to the opening end 42a of the communication passage 42, and the opening end 43 of the outside air introducing passage 43 to the valve operating chamber 28 is provided.
b is located on the upper surface of the head cover 27 which is the upper wall of the valve operating chamber 28. A breather port 44 is opened on the upper surface of the head cover 27 at a position adjacent to the open end 43b of the outside air introduction passage 43. Breather mouth 44
Is communicated with the air cleaner 39 via a breather hose 44a. Therefore, one end of the outside air introduction passage 43 is
It communicates with the outside air via the valve operating chamber 28 and the air cleaner 39.

A check valve 46 that allows only the flow from the valve operating chamber 28 toward the crank chamber 16 is provided in the middle of the outside air introduction path 43.

In the check valve 46 of this embodiment, as shown in FIG. 2, a partition member 49 having, for example, four small holes 48 ... A flexible valve body 50 that opens and closes the small holes 48 is attached to the downstream end face of the outside air. By changing the hole diameter of the small holes 48 ... The flow rate can be adjusted.

Next, the operation of the above configuration will be described.

When the crankshaft 19 is rotated along with the up-and-down movement of the piston 18, the splatter 21 stirs the lubricating oil in the crank chamber 16 and splashes it, and the splashed lubricating oil accommodates it in the crank chamber 16. Lubrication around the shafts 51, 21, 22, the cylinder 17 and the piston 18 is performed.

On the other hand, in the exhaust or compression process, as the piston 18 rises, the inside of the crank chamber 16 becomes a negative pressure. Therefore, as indicated by the broken line arrow in FIG. The outside air in the air cleaner 39 is sucked into the crank chamber 16 through 33. When the piston 18 starts descending after reaching the top dead center, the outside air sucked into the crank chamber 16 and the piston 18 and the cylinder 1
The blow-by gas blown into the crank chamber 16 through the gap between the crank chamber 16 and 7 is compressed, and the internal pressure of the crank chamber 16 rises.

The compressed outside air and probe gas are pushed up through the return passage 33 and the communication passage 42 and fed into the valve operating chamber 28, as shown by the solid line arrow in FIG.

At this time, the crank chamber 16 is filled with the lubricating oil agitated by the splasher 21 in the form of a mist, and in particular, the opening end 42a of the communication passage 42 to the crank chamber 16 is splashed by the splasher 21. Since it is located on the upper surface of the crank chamber 16 through which the lubricated oil is guided, the lubricating oil directly enters the opening end 42a. Therefore, the lubricating oil flows into the return passage 33 and the communication passage 42 by being multiplied by the flow of the outside air or blow-by gas compressed as described above, and is guided to the valve operating chamber 28 through the return passage 33 and the communication passage 42. Since the open end 42b of the communication passage 42 to the valve operating chamber 28 is close to the contact portion between the rocker arm 30 and the valve stem 26a, the lubricating oil is directly supplied to the contact portion requiring this lubrication, Lubrication of the entire valve mechanism 34 including this contact portion is performed. It should be noted that when the interior of the crank chamber 16 is compressed by the lowering of the piston 18, the outside air or blow-by gas in the crank chamber 16 may flow back in the outside air introduction passage 43, and the pressure increase in the crank chamber 16 may be hindered. Although conceivable, since the check valve 46 is provided in the middle of the outside air introduction path 43, the outside air and blow-by gas do not flow backward, and the pressure in the crank chamber 16 is efficiently increased.

Further, the lubricating oil after lubricating the valve operating mechanism 34 in the valve operating chamber 28 is returned to the crank chamber 16 via the return passage 33, and the blow-by gas introduced into the valve operating chamber 28 is the first As indicated by the solid line arrow in the figure, it is recirculated to the air cleaner 39 or the crank chamber 16.

According to such an embodiment of the present invention, due to the pressure fluctuation in the crank chamber 16 caused by the up-and-down movement of the piston 18, the outside air is sucked into the crank chamber 16 and the sucked outside air is compressed together with the blow-by gas. The valve chamber 16 is supplied to the valve chamber 28 during operation of the engine 11.
Lubricating oil in the form of mist is always supplied to the inside by the outside air. Therefore, it is not necessary to rely on the blow-by gas for the supply of the lubricating oil as in the past, so that the oil can be stably supplied to the valve mechanism 34 even if the blow-by gas decreases.

Moreover, the lubricating oil component is forcibly sent into the valve operating chamber 28 by the pumping action of the crank chamber 16, so that the cylinder arrangement is not restricted, and therefore the degree of freedom in the structure and design of the engine 11 is increased. There are advantages.

Further, since the outside air introduction passage 43 of the present embodiment sucks the outside air filtered in the air cleaner 39, there is no fear that fine dust in the air will be mixed into the crank chamber 16, and the wear inside the engine 11 Can be prevented.

In addition, according to the above configuration, the valve operating chamber 2 of the outside air introduction passage 43
Since the opening end 43b to 8 is opened in the upper surface wall of the valve operating chamber 28, the lubricating oil component guided to the valve operating chamber 28 is less likely to flow into the outside air introduction passage 43.

That is, since the lubricating oil component is heavier than gases such as blow-by gas and the outside air, when it is introduced into the valve operating chamber 28, it is separated from the blow-by gas and the outside air based on the decrease in the flow velocity and adheres to the valve operating mechanism 34. Except for this, most of it tries to accumulate on the bottom of the valve operating chamber 28 along the peripheral surface of the valve operating chamber 28. Then, this lubricating oil is returned to the crank chamber 16 mainly through the return passage 33 and the communication passage 42.

From this, the lubricating oil flows back and forth between the crank chamber 16 and the valve operating chamber 28 through the return passage 33 and the communication passage 42, so that most of the lubricating oil flowing through the outside air introduction passage 43 becomes outside air, and the lubricating oil It becomes difficult for oil to adhere to the check valve 46. If the lubricating oil component adheres to the check valve 46, the small hole 48 of the check valve 46 may be blocked, especially when the oil temperature is low and the viscosity of the oil is high, such as immediately after starting, and the crank chamber may be blocked. Even when the pressure in the cylinder 16 becomes negative, the introduction of outside air into the crank chamber 16 is hindered.

However, as in the above configuration, the amount of lubricating oil is reduced by the check valve 4
If it becomes difficult to adhere to 6, the small holes 48 will not be blocked, and the circulation of the outside air toward the crank chamber 16 can be maintained smoothly.

Therefore, when the piston 18 rises, a sufficient amount of outside air is sucked into the crank chamber 16, and when the piston 18 descends, the internal pressure of the crank chamber 16 rapidly rises and is supplied to the valve mechanism 34. A sufficient amount of oil can be secured, and the reliability of lubrication is improved.

The engine of the above-described embodiment is an OHV engine in which the cam shaft is provided in the crank chamber and the rocker arm is operated from there through the tappet and the push rod.
The present invention is not limited to this, and the OH in which the camshaft is also provided in the valve operating chamber
It may be a C engine.

Further, the outside air introducing passage may be opened directly into the outside air without communicating with the air cleaner, and the structure of the check valve is not limited to the above embodiment.

〔The invention's effect〕

According to the present invention described in detail above, due to the pressure fluctuation in the crank chamber due to the up-and-down movement of the piston, the outside air is sucked into the crank chamber, and the sucked outside air is compressed together with the probe-by gas and sent into the valve operating chamber. Therefore, during operation of the engine, the valve operating chamber is always supplied with mist-like lubricating oil by the outside air. Therefore, it is not necessary to rely on the blow-by gas for the supply of the lubricating oil as in the past, so that the oil can be stably supplied to the valve mechanism even if the blow-by gas is reduced.

Further, the lubricating oil component is forcibly sent into the valve operating chamber by the pumping action of the crank chamber, so that the cylinder arrangement is not restricted and the degree of freedom in the structure and design of the engine is increased.

Moreover, according to the above configuration, the lubricating oil component introduced to the valve operating chamber is heavier than the blow-by gas or the outside air, so that when the lubricating oil is introduced into the valve operating chamber, the lubricating oil is separated from the blow-by gas or the outside air due to the decrease in flow velocity. Except for the amount separated and adhered to the valve operating mechanism, most of it will travel along the peripheral surface of the valve operating chamber toward the bottom of the valve operating chamber, and the outside air introduction path that opens to the upper wall of this valve operating chamber It becomes difficult to flow into the open end. For this reason, the lubricating oil mainly flows back and forth between the crank chamber and the valve operating chamber through the return passage and the communication passage, and most of the lubricating oil flows through the outside air introduction passage to the outside air, so that the lubricating oil component Difficult to attach to the check valve. Therefore, even when the oil temperature is low and the viscosity of the oil is high, such as immediately after starting, the operability of the check valve is not hindered, and the circulation of outside air toward the crank chamber can be smoothly maintained. . Therefore, when the piston rises, a sufficient amount of outside air is drawn into the crank chamber,
When the piston descends, the internal pressure of the crank chamber rapidly rises, so that there is an advantage that the amount of oil supplied to the valve operating mechanism can be sufficiently secured and the lubrication reliability is improved.

[Brief description of drawings]

The drawings show one embodiment of the present invention. Fig. 1 is a sectional view of an engine, Fig. 2 is a sectional view of a check valve, Fig. 3 is a side view of a golf car, and Fig. 4 is a plan view of the same. is there. 16 …… Crank chamber, 17 …… Cylinder, 18 …… Piston,
18a ... Piston head, 19 ... Crankshaft, 21 ...
... Splasher, 26 ... Intake valve, 28 ... Valve chamber, 33 ... Reflux passage, 34 ... Valve mechanism, 42 ... Communication passage, 42a, 42b ... Opening, 43 ... Outside air introduction passage, 4
3a, 43b ... Opening, 44 ... Breather opening, 46 ...
Check valve.

Claims (1)

[Claims] 1. An intake valve, an exhaust valve, and a valve operating mechanism for opening and closing these valves on the side of the piston facing the piston head, and a valve operating chamber accommodating the valve operating mechanism; Lubricating oil accumulated at the bottom of the crank chamber is made to communicate with the crank chamber in which the cylinder containing the piston is connected via a return path, and the crank chamber rotates in conjunction with the crankshaft. A splasher that stirs and splashes the oil. In an overhead valve engine designed to perform lubrication around the mechanism, the valve operating chamber is connected via the freezer port. The valve chamber and the crank chamber are communicated with each other through a communication passage separate from the return passage and an outside air introduction passage, and the opening of the communication passage to the crank chamber is The opening of the communication passage to the valve operating chamber is provided near the lubricated portion of the lubricated portion of the valve mechanism, and the movement of the outside air introduction passage is provided while the lubricating oil is splashed by the splasher. An overhead is characterized in that an opening to the valve chamber is provided in the upper wall of the valve operating chamber, and a check valve that allows only the flow from the valve operating chamber to the crank chamber is provided in the middle of the outside air introducing passage. Lubricator for valve type engine.