JPH07654Y2 - Lubricator for horizontal cylinder type overhead valve engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] In this invention, a cylinder is horizontally oriented, and a head opening and a valve cover are provided inside a head cover and a crank chamber. The present invention relates to a lubrication device for a horizontal cylinder type overhead valve engine having a breather passage and an oil return passage.

[Prior Art] In an overhead valve type engine, intake and exhaust valves are arranged in a cylinder head attached to a cylinder.

This intake / exhaust valve is provided, for example, in a camshaft arranged in the crankcase, a tapette and a push rod that move up and down according to the camshaft, and a rocker arm (part of the valve opening / closing mechanism) that can be reciprocally rocked in the rocker arm chamber. It is opened and closed.

In this case, the valve opening / closing mechanism including the locker arm is
In addition to forced lubrication, there is a configuration in which lubrication is performed by an oil mist mixed with a breather from the crank chamber for cost reasons.

In particular, many small general-purpose overhead valve engines use oil mist associated with such a breather for lubrication. For example, it is disclosed in Japanese Utility Model Publication No. 60-6585. There was something that was done.

With such a lubrication system, the locker arm chamber is connected to the air cleaner in the intake passage to keep the pressure almost the same as in the air cleaner (atmospheric pressure or a slight negative pressure), that is, almost atmospheric pressure. The chamber is communicated with a passage, one is a passage for a breather with oil mist, that is, a breather passage, and the other is an oil return passage from the rocker arm chamber to the crank chamber. The oil mist guided along with the breather through the breather passage to the rocker arm chamber maintained at almost atmospheric pressure at the time of positive pressure of L lubricates the valve opening / closing mechanism, and the oil accumulated in the locker arm chamber for lubrication is stored in the crank chamber. At the time of negative pressure, from the rocker arm chamber kept at almost atmospheric pressure to the crank chamber through the oil return passage. While returned, the breather guided to Rotsukaamu chamber, for example, derived into the cleaner through the breather outlet hole.

This is performed by both positive pressure and negative pressure in the crank chamber, which are generated as the piston moves.

When the structure for performing lubrication using two passages is applied to the vertical cylinder type overhead valve engine of the above publication, the positional relationship between the oil in the oil reservoir of the crank chamber and the passage is considered. Even if the engine is tilted, it is unlikely that a large amount of oil will flow into the rocker arm chamber through the passage.

[Problems to be Solved by the Invention] However, when the above structure is adopted in a horizontal cylinder type overhead valve engine in which cylinders are arranged horizontally, a large amount of oil may flow into the rocker arm chamber.

In other words, in the case of the horizontal cylinder type, it is functionally natural to dispose the breather passage on the upper side of the cylinder and the oil return passage on the lower side, but if both passages are disposed in this way, The inlet of the oil return passage on the lower side is likely to be immersed in the oil when the engine is tilted, whereas the oil return passage according to the above publication is an open passage with low flow resistance, so that it is associated with the positive pressure in the crank chamber. A large amount of oil may flow into the locker arm chamber through this oil return passage. Therefore, when introducing the breather to the air cleaner through the breather lead-out hole of the head cover, the oil flows into the air cleaner and further into the carburetor, and when the breather is directly led out of the engine, the oil is discharged to the outside of the engine. There is an inconvenience.

In order to improve this, for example, in Japanese Utility Model Publication No. 58-42569, one end of the oil return pipe is communicated with the rocker arm chamber and the oil separator, and the other end is communicated with the crank chamber, and the oil return pipe is It is disclosed that it is connected to an oil pump to forcibly return excess oil to the crank chamber.

However, according to the above configuration, an oil return pipe separate from the intake system including the air cleaner and the carburetor is provided,
In addition, since the oil pump must be equipped, the engine structure becomes complicated and large.

Therefore, as another conventional example, as disclosed in JP-A-61-98909, a notch (resisting means) is provided at the end of the oil return passage so that a large amount of lubricating oil can be returned. It is known to prevent entry into the locker arm chamber from a passage.

By the way, in this conventional example, the inside of the rocker arm chamber (valve mechanism housing chamber) in the head cover is kept at almost the same pressure as the crank chamber, so that the crank chamber becomes positive pressure and the check valve (check valve). Even if is opened, a large pressure difference does not occur between the crank chamber and the rocker arm chamber.
Therefore, there is a problem that the amount of the breather flowing into the rocker arm chamber is relatively small and the oil mist contained in the breather cannot sufficiently lubricate the rocker arm chamber.

This is because, for example, as disclosed in Japanese Patent Laid-Open No. 58-200019, a check valve (check valve) is provided in the oil return passage, and when the crank chamber has a positive pressure, the check valve is opened. Even with the closed structure, there are almost the same problems.

Further, according to this configuration, since the crank chamber has a double structure, it is necessary to provide two passages for venting the breather and the air from these two chambers, which makes the structure of the engine complicated and large. It cannot be avoided.

This invention was made to solve the above problems,
While simplifying the overall structure of the engine, making it compact and low cost, generate a large pressure difference between the crank chamber and the rocker arm chamber and use the oil mist contained in the breather to sufficiently lubricate the rocker arm chamber. It is an object of the present invention to provide a lubrication device for a horizontal cylinder type overhead valve engine capable of achieving the above.

[Means for Solving the Problems]

In order to achieve the above object, a lubrication device for a horizontal cylinder type overhead valve engine according to the present invention has a cylinder and a cylinder head arranged horizontally and a crankshaft arranged vertically, and an intake valve and an exhaust valve for the cylinder head. Is provided, and the tappet and push rod for operating the intake and exhaust valves are attached substantially in parallel inside the side surfaces of the cylinder and the cylinder head,
In the horizontal cylinder type overhead valve type engine in which a valve opening / closing mechanism for interlocking the intake and exhaust valves is provided in a rocker arm chamber surrounded by a head cover, in the cylinder and cylinder head between the rocker arm chamber and the crank chamber, Two upper and lower passages are formed, of which the upper passage is provided at the upper part of the push rod to serve as a breather passage, and the lower passage is the insertion hole of the push rod on the cylinder head side and the push rod on the cylinder side. The hole formed in the lower part of the is connected stepwise to form an oil return passage, and the end of the breather passage on the cylinder head side or the head side end of the cylinder is
A check valve that is opened by positive pressure and closed by negative pressure in the crank chamber is provided, and the flow resistance in the head cover direction in the oil return passage system is the same as that in the breather passage system including the check valve. A throttle part is formed in the stepwise mating part of the cylinder head and the cylinder of the oil return passage as resistance means for allowing the oil to return and always allowing the oil to return, and preventing the oil from flowing toward the head cover, The rocker arm chamber is provided with a breather lead-out hole communicating with the air cleaner so as to keep the rocker arm chamber at substantially atmospheric pressure, and a crank chamber that becomes positive pressure and negative pressure depending on the operation of the piston, Due to the pressure difference generated between the rocker arm chamber and the rocker arm chamber maintained at atmospheric pressure, the oil mixer is passed through the breather passage. A breather including a pump is sent to the rocker arm chamber, and the breather is separated from the oil mist in the rocker arm chamber to guide the breather to the air cleaner, and only the oil accumulated in the rocker arm chamber is circulated to the oil return passage. Is.

In the lubricating device configured as described above, it is desirable that one end of the oil return passage be opened below the oil level of the oil reservoir of the engine.

[Action]

According to the above configuration, the combination of the check valve provided in the breather passage, the throttle portion provided as the resistance means provided in the oil return passage, and the breather lead-out hole provided in the rocker arm chamber and communicating with the air cleaner causes the rocker arm. Since the chamber is kept at almost atmospheric pressure, the crank chamber becomes positive and negative pressure according to the operation of the piston,
A large pressure difference is generated between the rocker arm chamber maintained at almost atmospheric pressure, and a large amount of breather containing oil mist is sent into the rocker arm chamber through the breather passage to sufficiently lubricate the valve opening / closing mechanism in the rocker arm chamber. It is possible to Here, the breather and the oil containing the oil mist are circulated through the upper and lower two passages formed inside the cylinder and the cylinder head without requiring a forced lubrication device such as an oil pump and an external passage therefor. Therefore, the lubrication performance can be improved without inviting the engine structure to be complicated and upsized. In addition, as a resistance means to prevent oil from flowing into the rocker arm chamber from the oil reservoir on the crank chamber side through the oil return passage when the engine is greatly tilted, a check valve or the like is provided in the oil return passage. No special parts are provided, and the throttle part formed by molding the mold is provided at the stepwise mating part of the cylinder and the cylinder head, so that the reverse flow of oil can be achieved with a small number of parts. Can be surely prevented, and reliability can be improved.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of a small-sized general-purpose type horizontal cylinder type overhead valve type air-cooled engine.

In the figure, 1 is a crankcase, 2 is a cylinder, and both 1 and 2 are formed as an integral block.

The crankcase 1 has an upper side U as shown in FIG.
Is closed and has the bearing portion 3, while the lower side D is opened and the oil reservoir portion 4 is attached.

A bearing portion 5 is also formed in the oil reservoir portion 4, and the crankshaft 6 is supported through the upper and lower bearing portions 3 and 5.

In the present embodiment, the crankshaft 6 is oriented perpendicular to an engine installation surface (not shown), and a vertical shaft type engine is adopted here, and a cooling fan (not shown) is provided at one end of the upper side U thereof. It is installed.

Reference numeral 7 denotes a crank gear, which meshes with a cam gear 8 shown in FIG. 3 to drive a cam shaft 9.

On the other hand, the cylinder 2 has a piston 10 as shown in FIG. 2, and a cylinder 11 is connected to the crankshaft 6.

The cylinder 2 is provided as a horizontal cylinder type whose center is oriented horizontally, and a large number of cooling fins 12 are projected on the outer periphery of the cylinder 2.

Reference numeral 13 is a cylinder head, which is connected to one end of the cylinder 2 in the horizontal direction.
14, 14 are provided in a vertical relationship, and intake and exhaust valves 15, 15 are inserted through the valve guide 14 thereof. Also,
As shown in FIG. 1, an arm shaft bracket 16 is integrally projected in the cylinder head 13 in the horizontal direction. The arm shaft bracket 16 is, as shown in FIG.
Two pairs, one pair as one pair, are arranged vertically.

As shown in FIG. 1, an arm shaft 17 is inserted into these arm shaft brackets 16 so as to face the vertical direction of the engine, and the two arm arms 18, 18 are reciprocally swingable by the arm shaft 17. It is supported.

One end of the locker arm 18 is connected to the intake / exhaust valve 1
5, 15 and the other end abuts one end of the push rod 19, respectively, and encloses a valve opening / closing mechanism 20 constituted by such a locker arm 18, arm shaft 17 and the like with a head cover 21, and inside the head cover 21. The locker arm chamber 22 is formed in the.

Further, the push rod 19 is reciprocally movable in the horizontal direction in accordance with the tapette 23 contacting the camshaft 9.
In this case, as shown in FIG. 3, the cylinder 2 is formed with two taper insertion holes 25 for the tapet 23 at one end on the crank chamber 24 side, and the two taper insertion holes 25 for the tapet 23 are formed above and below each of the tapet insertion holes 25. On the head side, a cylinder-side rod insertion hole 26 is formed in a vertical direction so as to spread in the direction of the cylinder head 13, and the head side rod insertion hole 27 is also formed on the head side. Are formed in a relationship. These head side rod insertion holes 27 are
The arrangement is also shown in FIG.

Further, as shown in FIG. 2, the locker arm chamber 22 itself also serves as a gas-liquid separation chamber, that is, at the end of the cylinder head 13 on the locker arm chamber 22 side, the head projection shown in FIG.
28 is formed, and the locker arm chamber 22 and the air cleaner 32 in the intake passage communicate with each other through the recess 29 formed therein, the breather lead-out hole 30 and the cleaner communication tube 31 shown in FIG. As a result, the inside of the rocker arm chamber 22 is maintained at substantially the same pressure as the inside of the air cleaner 32 (atmospheric pressure or a slight negative pressure), that is, approximately atmospheric pressure. Further, the air cleaner 32 is connected with a carburetor 33.

In such a horizontal cylinder type overhead valve engine, a characteristic feature of this engine is that a check valve 36 is provided in a breather passage 34 and an oil return passage is provided as shown in FIG.
A diaphragm 38 is installed in the middle of 35 and the locker arm chamber
The breather lead-out hole 30 (4th
(Fig.) Is provided so that the locker arm chamber 22 is maintained at substantially the same pressure as in the air cleaner 32 (atmospheric pressure or a slight negative pressure), that is, at approximately atmospheric pressure.

Further, two upper and lower passages 34, 35 that communicate the crank chamber 24 and the interior of the head cover 21 are formed. One of the upper passages is a breather passage 34, and the other lower passage is an oil return passage 35. Placed as above and above the breather passage
A reed valve type check valve 36 is provided at one end on the head cover 21 side of 34, while the flow resistance of the oil return passage 35 toward the head cover 21 is set to be larger than the flow resistance of the breather passage 34 side including the check valve 36. There is a point.

Here, the breather passage 34 is disposed on the uppermost side through the cylinder 2 and the cylinder head 13, and in the embodiment, the cylinder 2 and the cylinder head 13 are formed with a deviating gradient so as to correspond concentrically. Form one passage.

Further, the check valve 36 is the piston 10 (Fig. 1).
Is released when a positive pressure is generated in the crank chamber 24, while the piston 10 (Fig. 1) rises and is released.
It is closed when a negative pressure is generated in 24.

When the valve is opened, the crank chamber 24
A large amount of breather containing mist from inside flows through the breather passage 34 as shown by the arrow X and is guided into the locker arm chamber 22. Among them, the mist lubricates each part of the valve opening / closing mechanism 20, while the breather separates the gas-liquid separation chamber. Double lock arm room
Separated from mist at 22 and air cleaner 32 (Fig. 4)
Be guided inside.

In this embodiment, as shown in FIG. 2, the cylinder head is
As shown in FIG. 5 in the upper part of the concave portion 29 of 13, the labyrinth wall 37 is integrally formed at a position away from the breather passage 34 on one side, and the breather lead-out hole 30 is arranged at the end of the labyrinth wall 37. It has a structure that enhances the separation effect.

On the other hand, the oil return passage 35 of FIG. 3 is formed stepwise by the lower head rod insertion hole 27 and the passage formed under the lower cylinder rod insertion hole 26. Here, a throttle (resistance means) 38 is formed in the middle of the oil return passage 35, that is, at a portion corresponding to the end of the cylinder 2 on the cylinder head 13 side, and the throttle 38 is formed in the rocker arm chamber 22.
To a crank chamber 24 to increase the flow resistance in one direction (the direction opposite to the arrow Y) and to allow the oil to return to the crank chamber 24, and to provide a head cover. It is designed to block the flow of oil in the 21 direction.

In the above structure, as shown in FIG.
Two upper and lower passages 34,3 that connect 24 and the inside of the head cover 21.
5 and one of the upper passages is the breather passage 3
4, the other lower passage is arranged as an oil return passage 35, and the head cover 21 of the breather passage 34 is further arranged.
While the check valve 36 is provided at one end on the side, the flow resistance of the oil return passage 35 toward the head cover 21 is set to be larger than the flow resistance of the breather passage 34 side including the check valve 36, and the rocker arm chamber In this embodiment, for example, the breather lead-out hole 30 communicating with the air cleaner 32 (FIG. 4) is provided in the valve 22, so that the rocker arm chamber 22 is maintained at substantially the same pressure as the intake system (air cleaner 32). .

Therefore, when the check valve 36 is opened because the crank chamber 24 has a positive pressure, the crank chamber 24 that becomes a positive pressure and a negative pressure according to the reciprocating movement of the piston 10 and the rocker arm chamber 22 that is maintained at almost atmospheric pressure. There is a large pressure difference between and.

As a result, a large amount of breather containing oil mist
Flow through the breather passage 34 in the direction indicated by the arrow X,
The inside of the rocker arm chamber 22 is sufficiently lubricated by the large amount of oil mist sucked into the rocker arm chamber 22.

Further, in this embodiment, when the engine is tilted by, for example, about 30 degrees with the head cover 21 side lowered as shown by the two-dot chain line in FIG.
It may correspond to the oil return passage 35 in the figure, but at that time, the inside of the crank chamber 24 becomes a positive pressure and the oil O enters the oil return passage 35 communicating with the rocker arm chamber 22 held at substantially atmospheric pressure. Also, since the resistance on the oil return passage 35 side is larger than that on the breather passage 34 side, the check valve 36 opens and the breather flows in the direction of the arrow X, so that the oil O in the rocker arm chamber 22 passes through the oil return passage 35. Is prevented from flowing.

This is the check valve 36 in the upper breather passage 34,
This is obtained by providing the throttles 38 in the lower oil return passages 35, respectively. For example, breather passage 34
By replacing the check valve 36 of Fig. 3 with a throttle, when the engine tilts from the horizontal direction to the head downward, the breather gas in the crank chamber 24 smoothly flows through the breather passage 34 which has a high flow resistance due to the throttle. Since it is not possible to escape into the locker arm chamber 22, the positive pressure in the crank chamber 24 does not drop sufficiently and acts on the oil return passage 35 as it is, so that a large amount of oil passes through the oil return passage 35. There will be a problem of inflow into the locker arm chamber 22.

When the crank chamber 24 becomes negative pressure, the check valve 36
Is closed, the negative pressure is concentrated in the oil return passage 35,
Therefore, even if the throttle 38 is present, the lubricated oil O in the rocker arm chamber 22 is forcibly returned to the direction of the arrow Y, that is, into the crank chamber 24. This is advantageous in that the oil return function is as reliable as forced lubrication, and this can be obtained with an inexpensive and simple structure in which only a valve is provided.

FIG. 6 shows another embodiment.

In this case, one end (outlet end) of the oil return passage 35 is opened below the oil surface of the oil O as means for preventing the oil O from flowing into the rocker arm chamber through the oil return passage 35 by positive pressure.

Here, even if a positive pressure acts, the head portion H becomes a resistance, and this becomes a kind of flow resistance, and the oil O does not reach the rocker arm chamber. In particular, since it is a type without the throttle 38 (Fig. 3), the oil O returns to the oil reservoir 4 more smoothly through the oil return passage 35.
In this embodiment, the check valve 36 is replaced by the cylinder head.
It is provided not at 13, but at the head end of the cylinder 2.

In each of the above embodiments, the vertical shaft type is used, but the horizontal shaft type can be used.

Furthermore, in the above embodiment, the locker arm 18 drives the intake / exhaust valve 15 to open and close, but other opening / closing drive means may be adopted.

Further, in the above-mentioned embodiment, the reed valve type is adopted as the check valve 36, but other valves can be adopted. In this case, the valve may be arranged at any position on the breather passage 34 as shown in FIG.

[Advantages of the Invention] As described above, according to the present invention, the check valve provided in the breather passage, the throttle portion as the resistance means provided in the oil return passage, and the rocker arm chamber provided in communication with the air cleaner. The rocker arm chamber is maintained at approximately atmospheric pressure by combining it with a breather lead-out hole.Therefore, the crank chamber becomes positive pressure and negative pressure depending on the piston operation, and the rocker arm chamber maintained at approximately atmospheric pressure. Since a large pressure difference is generated between
The structure of the entire engine is simplified without requiring a forced lubrication device such as an oil pump and an external passage therefor, and a large amount of breather containing oil mist is sent into the rocker arm chamber through the breather passage while making it compact and low cost. It is possible to sufficiently lubricate the valve opening / closing mechanism in the rocker arm chamber. Moreover, as a resistance means for preventing oil from flowing into the rocker arm chamber from the oil reservoir on the crank chamber side through the oil return passage when the engine is greatly inclined, a check valve or the like is provided in the oil return passage. The number of parts can be reduced because a stepped part between the cylinder and the cylinder head is provided with a throttle part that can be easily formed by molding a mold without providing any special part. By reducing the number of assembling steps, it is possible to reliably prevent the reverse inflow of oil and improve the reliability while suppressing the increase in cost.

Further, according to the present invention, due to the pressure difference generated between the crank chamber which becomes positive pressure and negative pressure according to the vertical movement of the piston and the rocker arm chamber maintained at substantially atmospheric pressure, the rocker arm chamber and the breather are Since the breather including the oil mist is made to circulate in the passage, the oil return passage, and the intake system, the engine structure can be simplified and downsized without providing an oil pump as in the conventional case.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a horizontal cylinder type overhead valve engine showing an embodiment of the present invention, FIG. 2 is a sectional view taken along line II-II of FIG. 1, and FIG. 3 is III of FIG. -III, a sectional view taken along line IV-IV in Fig. 2, a sectional view taken along line V-V in Fig. 2, and a sectional view taken along line V-V in Fig. 6
The figure is a longitudinal sectional view showing another embodiment of the present invention. 2 ... Cylinder, 6 ... Crank shaft, 13 ... Cylinder head, 15 ... Suction and exhaust valve, 19 ... Push rod, 20 ...
Valve open / close mechanism, 21 ... Head cover, 23 ... Tappet, 24
… Crank chamber, 30… Breather outlet hole, 32… Air cleaner, 34… Breather passage, 35… Oil return passage, 36… Check valve, 38… Throttling part.

Claims (2)

[Scope of utility model registration request] 1. A cylinder and a cylinder head are arranged horizontally and a crankshaft is arranged vertically, and an intake / exhaust valve is provided on the cylinder head, and the inside of the side surface of the cylinder and the cylinder head. In a horizontal cylinder type overhead valve engine in which a tappet and a push rod for operating the intake and exhaust valves are installed substantially in parallel, and a valve opening / closing mechanism that interlocks the intake and exhaust valves is provided in a rocker arm chamber surrounded by a head cover, Two upper and lower passages are formed inside the cylinder and the cylinder head between the rocker arm chamber and the crank chamber,
The upper passage of the push rod is provided at the upper portion of the push rod to form a breather passage, and the lower passage of the push rod has a through hole on the cylinder head side and a hole formed at the lower portion of the push rod on the cylinder side. A check valve that is opened by positive pressure in the crank chamber and closed by negative pressure at the end of the breather passage on the cylinder head side or the end on the head side of the cylinder. The flow resistance in the head cover direction in the oil return passage system is made larger than the flow resistance in the same direction of the breather passage system including the check valve, and the oil return is always allowed, and the oil in the head cover direction is As a resistance means for preventing the flow, the floor of the cylinder head and the cylinder of the oil return passage The rocker arm chamber is provided with a breather lead-out hole communicating with the air cleaner so that the rocker arm chamber is maintained at substantially atmospheric pressure. The breather including the oil mist is sent to the rocker arm chamber through the breather passage due to the pressure difference generated between the crank chamber, which becomes the negative pressure and the negative pressure, and the rocker arm chamber, which is maintained at about atmospheric pressure, and the oil mist is sent in this rocker arm chamber. And a breather are separated from each other to guide the breather to an air cleaner, and only the oil accumulated in the rocker arm chamber is circulated to the oil return passage. A lubrication device for a horizontal cylinder type overhead valve engine. 2. A horizontal cylinder type overhead valve engine according to claim 1, wherein one end of the oil return passage is opened below the oil level of the oil reservoir of the engine. Lubrication device.