JP3052099B2 - Oil recovery device for two-stroke engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for recovering lubricating oil accumulated at the bottom of a crankcase of a two-cycle engine.

[0002]

2. Description of the Related Art In a two-stroke engine, oil supplied together with an air-fuel mixture or oil supplied to a lubrication unit via an oil supply passage accumulates at the bottom of a crank chamber. It is known to supply the engine again. For example, in the invention of Japanese Utility Model Application Laid-Open No. 2-61108, a reverse opening that opens in the throttle valve direction only when a predetermined pressure difference is established between the bottom of the crank chamber and the engine-side valve sliding surface of the carburetor throttle valve. It communicates via a stop valve, and the accumulated oil is sucked into the intake air for reuse.

[0003] However, if this means is used, oil adhering to the inside of the engine when the engine is stopped collects at the bottom of the crankcase, and a larger amount of oil accumulates than during continuous operation.
If the engine is started in this state, the pressure difference between the throttle valve portion and the crankcase is large at the time of starting and at the time of idling thereafter, so that the accumulated oil is immediately re-supplied to the engine together with the air-fuel mixture. However, since the engine has a low temperature and a small amount of generated heat immediately after the engine is started, the oil may not be completely burned, and may be discharged as white smoke as well as exhaust gas.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to prevent the above-mentioned disadvantages from occurring by simple means.

[0005]

According to a first aspect of the present invention, as described in claim 1, a small volume is provided in a communication passage extending from the bottom of a crank chamber to an intake system. In a two-stroke engine oil recovery apparatus having a check chamber that is disposed downstream of the recovery chamber and that opens to the intake system side, an ascending path is provided downstream of the recovery chamber, and recovery in the ascending path is performed. A check valve is provided at a position higher than the liquid level during normal running of the chamber.

[0006] The second means is as described in claim 2, the collection chamber of a small volume disposed in the middle of the communication path comprising communicating et al intake system from the crank chamber bottom, the air intake system downstream of the recovery chamber in the oil recovery apparatus of a two-stroke engine comprising a check valve that opens to the side, and provided continuously rising path and the descending path downstream of the collection chamber, the connecting portion than the liquid level of the normal running of the collection chamber at elevated road Is also arranged at a higher position. Also the
The means of the third aspect is, as described in the third aspect, the second aspect.
That the volume of the descending path is larger than the volume of the ascending path.
Features .

[0007]

According to the first means, when the engine is started and during irregular combustion, since the negative pressure of the intake system is small, the differential pressure in the communication passage is small, and the oil is discharged from the rising path downstream of the recovery chamber. Sani
Restricted and unable to flow , no resupply of oil. When the engine speed increases, the flow rate of the intake air increases, so that the static pressure of the intake system decreases, and the oil flows into the intake system beyond the check valve and is resupplied, but the heat generated by the engine is large. Therefore, the oil completely burns and no white smoke is generated.

[0008] According to the second means, from the ascending road to the descending road
The spilled oil accumulates in the descending path without backflow,
When the oil level in the recovery chamber drops, it is blown up with the air-fuel mixture. Ma
According to the third means, the oil flowing out of the rising path
Accumulates in the descending path with a large volume, and the oil level in the recovery chamber drops.
Then, it is blown up by the air-fuel mixture and re-supplied to the engine .

[0009]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is a two-stroke engine, 2 is a crankcase,
Reference numeral 3 denotes a cylinder, 4 denotes a scavenging port on the intake pipe side, and 5 denotes an exhaust port.

A reed valve 6 is provided near the scavenging port 4 and faces the crank chamber 2. An intake pipe 7 and a carburetor 8 are connected upstream of the reed valve 6, and a throttle valve 9 is provided at the center of the carburetor 8 in the vertical direction. Are slidably provided and operated by the cable 10.

A crankshaft 11 conceptually illustrated is supported in the crankcase 2, and a connecting rod 12 and a piston 13 are sequentially connected to a crankpin 11 a of the crankshaft 11. Is formed between them.

The rotation of the crankshaft 11 is transmitted to a transmission 15 via a primary reduction gear and a main clutch (not shown) to drive a load.

The bottom portion 16 of the crank chamber 2 has the gap 14 slightly widened so as to easily collect oil, and a scraper 17 very close to the outer peripheral surface of the crank web 12b projects downstream in the rotational direction. The oil attached to the outer periphery of the crank web 12b is scraped off and flows to the bottom portion 16.

A collecting device 20 is used to return the oil collected in the bottom 16 to the intake system.
Comprises a main body 21, a lid 22, and a partition plate 23,
Is provided with a collection chamber 24. The recovery chamber 24 has a volume slightly larger than the amount of oil that accumulates when the engine is left standing for a long time, and is connected to the bottom 16 by an inflow pipe 25.
An exit path 26 is provided on the lower side surface of the collection chamber 24, and an ascending path 27 that stands up between the main body 21 and the lid 22 with the partition plate 23 interposed therebetween.
And a descending passage 28 having a large capacity is formed, and a check valve 29 communicating the upper portions of both passages 27 and 28 is provided in the partition plate 23.
The non-return valve 29 is provided with oil O during normal running in the recovery chamber 24.
2. The small hole 29a, the valve plate 29b, and the four tongue-shaped stoppers 29
c, and no spring for pressurizing the valve plate 29b is provided. Further, a communication path 30 that opens from the lower end of the descending path 28 to the upstream side of the throttle valve 9 of the carburetor 8 is provided.

The engine 1 has hanger bosses 31, 32, 33 from the upper part to the rear part, and is mounted on the motorcycle M shown in FIG. Each hanger boss is provided with the motorcycle M
Of the output sprocket 39 is transmitted to the sprocket 42a of the rear wheel 42 via the chain 40. Then, air is supplied to the carburetor 8 from an air cleaner 44 provided below the seat 43 through an intake pipe 45, and fuel and oil are supplied to the carburetor 8 from a fuel tank and an oil tank 46 (not shown). The recovery device 20 is provided at the lower portion of the engine 1 as described above, and
Is connected to the intake pipe 45 side.

In FIG. 1, the pressure acting on the recovery chamber 24 from the crank chamber 2 due to the lowering of the piston 13 is P ₂ , the pressure acting on the descending chamber 28 from the intake system is P _1, and P ₂ -P
₁ = Oil column with height h is formed by pressure difference of ΔP
When the pressure difference is equal to or less than ΔP, the oil cannot pass through the check valve 29 even if the amount of oil in the recovery chamber 24 is large.

Therefore, oil is prevented from flowing into the carburetor 8 from the communication passage 30 at the time of starting, idling, or irregular combustion when the flow rate of the air passing through the carburetor 8 is low.
When the pressure in the crank chamber 2 is reduced due to the rise of the piston 13, the check valve 29 is closed to prevent the oil from flowing backward. However, when the flow rate of the air passing through the carburetor 8 increases due to the opening of the throttle valve 9 and the static pressure decreases, the pressure difference ΔP increases, and the oil column due to the pressure difference ΔP tries to become more than h. When the oil falls through the check valve 29 into the descending chamber 28 and the oil level L in the collecting chamber 24 is lowered, the air-fuel mixture flows out and blows up the dropped oil to resupply the intake system.

FIG. 4 shows the relationship between the differential pressure ΔP and the recovered oil amount Q. Assuming that the differential pressure at which the oil column having the height h occurs is ΔP ₀ ,
<Oil reservoir to the collection chamber 24 in the area of △ P _0, △ P> line l △ P as a boundary △ resupply of recovered oil in the area of P ₀ is performed. And in which re-supply is carried out at a differential pressure △ P ₀ with drop h, re-supply amount as a line q ₀ by the increase of the differential pressure is changed, it flows out at a differential pressure △ P ₁ at h> h ₁ ones the flow rate Q changes as shown in line q _1, h <those flowing in h ₂ at △ P ₂ changes as the line q _2.

FIG. 5 shows the relationship between the output of the engine and the recovered oil resupply zone. L ₁ indicates the upper limit of the region where the differential pressure of ΔP = P ₂ −P ₁ = h is small, and L ₂ indicates the fully open output. At this time, there is a relationship of ΔP = P ₂ −P ₁ > h. The L ₃ represents a running resistance. A line L ₁ and L ₂ in a region surrounded by A becomes a re-feed zone of the recovered oil in the figure, the height difference between L ₁ and L ₂ are substantially proportional to the re-supply. As is clear from the figure, the resupply amount is small when the engine speed and the output are low, and the resupply amount increases when the engine speed and the output become high.

[0020]

As described above, according to the first means of the present invention, the fact that the differential pressure between the crankcase and the intake system is small when the engine output is low and large when the engine output is high. To resupply the oil that accumulates in the crankcase according to the differential pressure ,
The differential pressure at the start of resupply depends on the height of the rising path following the recovery chamber.
Can be determined when the desired output is generated
Resupply can be started, which prevents incomplete combustion of the oil
Can be stopped.

According to the second means, the water flows out of the rising path.
The oil that has fallen on the downhill
Is discontinuous, preventing siphoning and raising
It has the effect of stabilizing the oil column in the road . This effect is descending
In the third means in which the volume of the road is increased,
More prominent.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an engine embodying the present invention.

FIG. 2 is a longitudinal sectional view of a check valve.

FIG. 3 is a side view of a motorcycle equipped with the engine of the present invention.

FIG. 4 is an explanatory diagram of oil recovery amount

FIG. 5 is an explanatory diagram of an oil recovery area.

[Explanation of symbols]

 2 Crank chamber 8 Vaporizer 20 Recovery device 24 Recovery chamber 27 Ascending path 28 Descending path 29 Check valve 30 Communication path

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F01M 11/00 F01M 3/00

Claims (3)

(57) [Claims] 1. A two-stroke engine having a small-capacity recovery chamber disposed in a communication passage extending from a bottom of a crankcase to an intake system, and having a check valve downstream of the recovery chamber and open to the intake system. A two-stroke engine in which an ascending path is continuously provided downstream of the recovery chamber in the oil recovery device, and a check valve is provided at a position higher than the liquid level of the recovery chamber during normal running in the ascending path . Oil recovery equipment. 2. A two-stroke engine having a small-capacity recovery chamber disposed in a communication passage extending from the bottom of a crankcase to an intake system, and having a check valve downstream of the recovery chamber and open to the intake system. In the oil recovery unit, the rising path and the downstream
Continuously provided the bath, the connecting portion is characterized in that arranged at a position higher than the liquid level of the normal running of the collection chamber at elevated road, oil recovery apparatus of a two-stroke engine. 3. The volume of the descending path according to claim 2,
Characterized by a larger volume than the road
Engine oil recovery device.