JPH0672526B2 - Lubricating structure of reciprocating piston engine - Google Patents

Abstract

PURPOSE:To improve distributing performance of lubricating oil and supplying performance at the time of starting by distributing lubricating oil to the parts of an engine via an oil sump chamber provided above the engine. CONSTITUTION:A lubricating oil tank separated from an engine body 1 is pro vided. A lubricating oil supply passage 37 is provided with a oneway valve 39 which permits lubricating oil to flow only to a crankcase and a valve mecha nism chamber 41 from the lubricating oil tank 28 and an oil sump chamber 40 provided at the downstream side of the oneway valve 39. Hereupon, the supply passage 37 is extended above a cylinder block 2 in parallel with a cylin der axis and is branched to the crankcase 3 and the valve mechanism chamber 41 via the oil sump chamber 41. Thus, the oil sump chamber 40 is provided above the engine body 1 so that oiling delay right after starting is improved. And the lubricating oil is distributed via the oil sump chamber 40 to each part so that the uniform oiling to each part becomes possible.

Description

The present invention relates to a lubrication structure for a reciprocating piston engine, and more particularly to a lubrication structure for an overhead valve engine in which a cylinder shaft is horizontally arranged.

<Prior Art> For example, a general-purpose engine with a vertically arranged crankshaft, such as an engine for a lawn mower, is as compact as possible.
It is desirable to reduce the weight. However, in the case of a four-cycle engine, it is indispensable to supply lubricating oil for lubricating the valve mechanism and the sliding surface of the cylinder. Especially in an engine in which the cylinder shaft is arranged horizontally, the crank web and piston are Since it is not preferable to submerge it in the lubricating oil, a tank for storing the lubricating oil is required at the bottom of the engine. Therefore, the structure tends to be complicated, and the height dimension of the engine tends to increase.

As a measure to eliminate such an inconvenience, the negative pressure in the crankcase accompanying the ascending of the piston is used to suck the lubricating oil into the crankcase, and the positive pressure in the crankcase accompanying the descending of the piston is used. Japanese Patent Laid-Open No. 61-175209 proposes a structure in which the lubricating oil is pushed back to the tank via the valve mechanism chamber.

<Problems to be Solved by the Invention> However, according to the dry sump type lubrication structure utilizing the pumping action of the piston as in the above conventional type, it is difficult to make the distribution of the lubricating oil to each part uniform,
In addition, it was inevitable that a time lag would occur in the supply of lubricating oil to the required parts at the start.

The present invention has been made to solve such inconvenience, and its main object is to provide a lubricating structure for a reciprocating piston engine capable of improving the distribution of lubricating oil and the supply at the time of starting. Especially.

[Structure of the Invention] <Means for Solving the Problem> According to the present invention, such a purpose has a valve mechanism chamber on one side of a cylinder block in which a cylinder shaft is horizontally arranged,
A lubricating structure for a reciprocating piston engine having a crankcase on the other side, the lubricating oil tank being provided separately from the engine body, and from the lubricating oil tank to the crankcase and the valve mechanism chamber. Supply oil passage including a one-way valve that allows only the flow of the lubricating oil and an oil reservoir provided downstream of the one-way valve, and the lubricating oil tank from the crankcase and the valve mechanism chamber. A return oil passage provided with a one-way valve that allows only the flow of lubricating oil toward the oil supply path, the supply oil passage being provided in an upper portion of the cylinder block and extending parallel to the cylinder axis. This is achieved by providing a lubricating structure for a reciprocating piston engine, which is characterized in that it branches into the crankcase and the valve mechanism chamber via a reservoir chamber.

<Operation> When the oil sump chamber is provided in the upper portion of the engine as described above, the delay in refueling immediately after the start is improved. Moreover, if the lubricating oil is distributed to each part through the oil reservoir, it is possible to uniformly supply each part. Particularly, if the lubricating oil tank is made of a translucent resin material, the state of the lubricating oil can be visually confirmed from the outside, and the boss having the inflow passage is provided inside. If the boss is provided so as to project downward at the bottom of the lubricating oil tank and the boss is fitted into the opening formed in the crankcase of the engine, it can contribute to the improvement of the assembling property.

<Embodiment> Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a vertical crankshaft type, forced air cooling type, single cylinder engine constructed according to the present invention. A crank case 3 is integrally abutted and coupled to an opening on the right side of a cylinder block 2 which constitutes the engine body 1, and a pair of ball bearings provided at a joint between the cylinder block 2 and the crank case 3 The crankshaft 5 is supported by 4a and 4b along the vertical direction. A piston 8 slidably fitted in a cylinder bore 7 provided in the cylinder block 2 is connected to a crank pin 6 formed at a substantially central portion of the crank shaft 5 via a connecting rod 9.

A balancer shaft 10 is pivotally supported at the joint between the cylinder block 2 and the crankcase 3 in parallel with the crankshaft 5. The balancer shaft 10 is for canceling the primary vibration force generated by the eccentricity of the crank pin 6, and is connected to the crank shaft 5 through the gear means 11 to be connected to the crank shaft 5. It is driven to rotate at the same speed and in the opposite direction.

A head cover 12 is integrally abuttingly connected to the opening on the left side of the cylinder block 2. A pair of upper and lower journals 13a and 13b is formed at the joint between the cylinder block 2 and the head cover 12. The journals 13a and 13b form a camshaft 14 extending parallel to the crankshaft 5. It is supported by its both ends. This camshaft
Reference numeral 14 denotes a timing belt 17 wound between a large timing pulley 15 integrally formed on the lower end side thereof and a small timing pulley 16 fixedly attached to the crankshaft 5 so that 1 / of the crankshaft 5 Driven at a rotational speed of 2.

An intake valve 19 and an exhaust valve 20 which are elastically urged in a valve closing direction by valve springs 18a and 18b are provided on the left side of the cylinder block 2. Both of these valves 19
The 20 are arranged side by side at an appropriate interval in a plane parallel to the crankshaft 5 and via the direct lifters 22a and 22b to the pair of cams 21a and 21b formed on the camshaft 14. They are engaged with each other, and are opened / closed at appropriate timing according to the rotation of the crankshaft 5.

A flywheel 23 is fixed to the upper end of the crankshaft 5. A blade 24 acting as a cooling fan is integrally formed on the outer peripheral portion of the axial end surface of the furan wheel 23. Further, a permanent magnet 25 is fixed to a part of the outer periphery of the permanent magnet 25 so that a required ignition spark is generated at a predetermined timing in cooperation with the ignition device 26 fixed to the cylinder block side. . Further, a recoil starter 27 is connected to the shaft end of the crankshaft 5.

A lubricating oil tank 28 is arranged on the right side of the crankcase 3. This lubricating oil tank 28 is made of a translucent resin material, and its bottom walls 29a and 29b are provided in two stages, and the shallow bottom portion 29a.
A boss portion 30 projecting downward is fitted into a through hole 31 formed in the crankcase 3. Continuing with the boss portion 30, a ridge 32 is extended along the inner surface of one side wall of the lubricating oil tank 28 until it reaches the upper wall. The ridge 32 is formed on the lower wall of the crankcase 3. Opposite openings and reed valve
A passage 34 is internally provided as a return oil passage that opens to the upper space of the lubricating oil tank 28 via 33. The passage 34 allows the lubricating oil to flow only from the bottom of the crankcase 3 to the upper portion of the lubricating oil tank 28.

On the inner surface of the other side wall of the lubricating oil tank 28, a second passage opening into the deep bottom portion 29b and communicating with the outside of the upper wall of the lubricating oil tank 28.
35 have been extended. The second passage 35 has a hose port 36 fitted in an opening in an upper wall thereof, and is connected to a lubricating oil supply passage 37 provided in the cylinder block 2 via a flexible tube 38. A one-way valve 39 that allows only the inflow of the lubricating oil from the lubricating oil tank 28 is interposed at the most upstream end of the lubricating oil supply passage 37.

The lubricating oil supply passage 37 extends along the cylinder axis in the upper wall of the cylinder block 2, and a cam journal portion located on the upper side through an oil reservoir 40 formed in the middle portion thereof.
Similarly to 13a, the crank bearing portion 4a located on the upper side is branched to supply the lubricating oil.

The upper surface of the engine body 1 configured as described above is covered with a cover C that also serves as a fan shroud over almost the entire surface.

Next, the lubricating action of the engine having the above configuration will be described.

A predetermined amount of lubricating oil OL has been previously injected into the lubricating oil tank 28. Here, when the engine is started and the piston 8 moves upward, the internal pressure of the crankcase 3 including the valve mechanism chamber 41 defined in the head cover 12 becomes negative, and the lubricating oil OL in the lubricating oil tank 28 becomes Through the second passage 35, the one-way valve 39 and the oil sump chamber 40, the oil flows into the valve mechanism chamber 41 via the lubricating oil supply passage 37, and at the same time, flows into the crankcase 3 via the upper crank bearing 4a. At this time, since some lubricating oil OL is stored in the oil reservoir 40, the lubricating oil is immediately stored in the required portion.
OL is supplied.

On the other hand, when the piston 8 descends and the internal pressure of the crankcase 3 becomes a positive pressure, the one-way valve 39 is closed and the lubricating oil OL in the crankcase 3 pushes the reed valve 33 through the passage 34 to push it away. Pushed back into 28.

[Effects of the Invention] As described above, according to the present invention, the lubricating oil circulates with the crankcase internal pressure that repeats positive and negative pressure fluctuations with the reciprocating movement of the piston, so that the oil pump is not required. Therefore, the structure is simplified and the number of parts is reduced,
Manufacturing costs can be reduced. In addition, since the lubricating oil tank is provided separately, the amount of lubricating oil to be stored in the engine body can be reduced, so that the crankcase volume can be reduced and the engine can be made smaller and lighter. At the same time, since the cooling property of the lubricating oil is improved and it is less likely to deteriorate, it is possible to confirm the amount of the lubricating oil or the pollution situation from the outside by making the lubricating oil tank semi-transparent, and maintainability is improved. Is improved. Further, since the lubricating oil is always stored in the oil reservoir, the lubricating oil is supplied immediately after the start, so that the oil film is not broken and the distributability of the lubricating oil to each part is improved.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of an engine constructed according to the present invention. 1 ... Engine main body, 2 ... Cylinder block 3 ... Crank case, 4a ・ 4b ... Ball bearing 5 ... Crank shaft, 6 ... Crank pin, 7 ... Cylinder bore, 8 ... Piston 9 ... Connecting rod, 10 …… Balancer shaft 11 …… Gear means, 12 …… Head cover 13a ・ 13b …… Journal part 14 …… Cam shaft, 15 …… Timing large pulley 16 …… Timing small pulley 17 …… Timing belt 18a ・ 18b …… Valve spring 19 …… Intake valve, 20 …… Exhaust valve 21a ・ 21b …… Cam 22a ・ 22b …… Direct lifter 23 …… Flywheel, 24 …… Blade 25 …… Permanent magnet, 26 …… Ignition device 27 …… Recoil starter 28 …… Lubricating oil tank, 29a ・ 29b …… Bottom wall 30 …… Boss part, 31 …… Through hole 32 …… Projection, 33 …… Reed valve 34 …… Passage, 35 …… Second passage 36 ...... Hose port, 37 ...... Lubricant oil supply path 38 ...... Flexible Cube 39 ...... one-way valve, 40 ...... the oil reservoir chamber 41 ...... valve operating mechanism chamber

Claims (3)

[Claims] 1. A lubrication structure for a reciprocating piston engine, comprising a valve mechanism chamber on one side of a cylinder block in which a cylinder shaft is horizontally arranged, and a crankcase on the other side, which is separate from the engine body. And a one-way valve that allows only the flow of the lubricating oil from the lubricating oil tank to the crankcase and the valve mechanism chamber, and an oil provided on the downstream side of the one-way valve. And a return oil passage having a one-way valve that allows only the flow of the lubricating oil from the crankcase and the valve mechanism chamber to the lubricating oil tank. The reciprocating piston is characterized in that the supply oil passage extends in an upper portion of the cylinder block in parallel with a cylinder axis and branches into the crankcase and the valve mechanism chamber via the oil reservoir chamber. engine Lubrication structure. 2. The lubricating structure for a reciprocating piston engine according to claim 1, wherein the lubricating oil tank is made of a translucent resin material. 3. The lubricating oil tank has a boss which is provided with an inflow passage therein and which projects downward, and the boss is fitted into an opening formed in a crankcase of the engine. The reciprocating piston engine lubrication structure according to claim 1 or 2.