CN1146528A

CN1146528A - Two-stroke engine with scavenging

Info

Publication number: CN1146528A
Application number: CN94113828A
Authority: CN
Inventors: 何学新
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-11-09
Filing date: 1994-11-09
Publication date: 1997-04-02

Abstract

The present invention relates to a two-stroke engine with all advantages of simple structure, low cost, large specific power and less maintenance work of the existent two-stroke engine. It has a scavenge pipe, and its volume is about equal to cylinder displacement and the size of its length is much greater than that of its diameter, so that in each cycle the inlet air only can be gone into and out from the scavenge pipe, and is less in exchange with the gas in the crankcase, therefore it can use four-stroke engine mode to make lubrication, and said inlet air does not contain lubricant, and the spark plug is replaced with oil nozzle, and the carburetor is removed, so that it is made into a two-stroke diesel engine. Besides, it has no need of high-accuracy Root's blower.

Description

Scavenging two-stoke cycle engine

The present invention relates to a kind of two stroke engine.

The two stroke engine specific power is big, and is simple in structure, with low cost, owing to there is not the cam valve mechanism of four stroke engine, except regular servicing, do not need to adjust when therefore working simultaneously, and its advantage is very tangible.

What best embody the two stroke engine advantage is exactly Shi Nule scavenging two-stoke cycle petrol engine.This design proposal adopts airtight crankcase to make air pump, makes that the cost of complete machine is very low.But its lubricating system is that lubricant oil is mixed in the gasoline, utilizes the infiltration of mist of oil to be lubricated.The lubricant oil that does not have burning that is blended in the fuel oil together is discharged in the atmosphere in company with waste gas.A shortcoming of this lubricating system is that lubricating oil consumption is bigger, and the lubricant oil of incomplete combustion forms the life-span that carbon distribution is unfavorable for motor simultaneously, and another shortcoming is a befouling environment.Especially in today that environmental protection comes into one's own day by day, this motor has been subjected to serious challenge even has flayed.According to the data introduction, some developed countries have give stricted orders this kind of forbidding motor.But because its advantage is so outstanding, so that people are also striving to find the whole bag of tricks, in the hope of maximize favourable factors and minimize unfavourable ones (1994 the 1st phases of " motorcycle technology " magazine have article to introduce the situation of this respect in detail).But these methods are not to fail to solve exhaust oil-containing problem, make motor become too complicated exactly, so that two stroke engine is simple in structure, advantage with low cost has been submerged.

As for two stroke diesel engine, because its fuel is not to resemble together to enter cylinder in company with air the petrol engine, so can not lubricate with Shi Nule scavenging mode, the high load of its bent axle does not allow it with such lubricating system yet.So it must be equipped with special scavenging pump (being generally Roots pump).Scavenging pump that requirement on machining accuracy is very high and the structure that becomes complicated have reduced the advantage of two stroke diesel engine equally.

We need a kind ofly to resemble the Shi Nule scavenging simple in structurely, but adopt the two stroke engine of four-stroke machine lubricating system.Like this, two stroke engine has just overcome original deficiency, has had tangible advantage.

The motor of structure shown in Figure 1 just can be realized this point preferably.

1 is spark plug among the figure, the 2nd, and cylinder, the 3rd, relief opening, the 4th, piston, the 5th, crank, the 6th, crankcase, the 7th, scavenging air pipe, the 8th, air-strainer, the 9th, Carburetor, the 10th, leaf valve, the 11st, scavenging port.

Different with traditional approach is to have set up scavenging air pipe 7.Scavenging air pipe 7 is answered inner wall smooth, and its length should be much larger than its radial dimension, and its volume should approximate cylinder displacement.When piston stroking upward, produce the certain vacuum degree in the crankcase, valve 10 is opened, and mixed steam is drawn in the scavenging air pipe, when descent of piston, pressure in the crankcase raises, valve 10 cuts out, and the mixed steam in the scavenging air pipe also is compressed simultaneously, when scavenging port is opened, mixed steam in the scavenging air pipe is sprayed onto in the cylinder, finishes scavenging.Scavenging air pipe is such length, to such an extent as to mixed steam wherein can be ignored with the quantity that contains the mist of oil air mixing.Even it is when swept volume seldom, like this too.Because it is the crankcase that suction port splashes apart from mist of oil is too far away after all, very low in the concentration of the suction port one side mist of oil of scavenging air pipe.Can see that, crankcase does not store mixed steam here, it just is used for producing air inlet and the necessary pressure of scavenging, and mixed steam is stored by scavenging air pipe.So (lubricating system of splash lubrication---four stroke engine is not sent mist of oil within the cylinder to, because a scavenging air pipe has been arranged, has isolated crankcase and mixed steam although mist of oil splashes in the crankcase.Because scavenging air pipe has increased the real space of crankcase, so intake vacuum and scavenging pressure all will decrease, and power per liter will descend to some extent, especially under the rotating speed condition with higher, so should reduce the space in the crankcase, in other words, should increase the volume of crank and connecting rod as far as possible as far as possible.What the advantage of this mode was is that it has only increased a scavenging air pipe, just solved the problem of exhaust oil-containing, even so its specific power is reduced to the level of four-stroke machine, it still has superiority than four stroke engine---simple structure, low cost of production and few maintenance workload.

In Fig. 1, we are as long as change spark plug 1 into oil injecting nozzle, and remove Carburetor 9, we just obtained one simple in structure, no longer need the two stroke diesel engine of highi degree of accuracy Roots pump.Should be noted that because the diesel engine intake resistance is little, rotating speed is lower, do not descend so power per liter does not have because of scavenging pressure reduces obviously to some extent.Therefore, its simple structure, low production cost and big specific power can make four-stroke machine prove definitely inferior.

The volume of scavenging air pipe is general desirable to be equated with cylinder displacement.But be crankcase ventilation usefulness, can make its volume be slightly less than cylinder displacement, like this, the gas in each air inlet cycle crankcase case all has the part exchange with new gas.That is realized the purpose of ventilating.

Structure shown in Figure 2 designs for reducing the distinctive scavenging loss of two-stroke gasoline engine.Each sequence number 1 to 6 is identical with Fig. 1 implication among the figure, and the 9th, air-strainer, the 10th, Carburetor.It has been divided into two scavenging

air pipes

7 and 8 with the scavenging air pipe among Fig. 17, there are 11, two valves of valve 12 and closure (throttle) should keep identical cracking pressure, the closure synchronization motion separately respectively, like this, when crankcase is negative pressure, air and mixed gas with certain proportion be stored in respectively air sweep the pipe 8 and mixed steam sweep the pipe 7 in, be timing at crankcase pressure, piston is opened the air scavenging mouth earlier, air is swept pipe 8 by air and is sprayed onto in the cylinder, drive away waste gas, and back piston is opened the mixed steam scavenging port.Mixed steam charges into cylinder, is pure air owing to what be introduced into cylinder, does not contain fuel oil, has therefore reduced fuel loss in the scavenging process.

The design of another kind of minimizing scavenging loss can be referred to as the rearmounted scheme of Carburetor as shown in Figure 3.This mode still needs the closure 11 of two synchronization motions, its cylinder point is the environment that needs Carburetor is placed variation in pressure, and this just needs sealing and special oil supplying device (oil pump), and this has increased complexity, its advantage is the problem that does not have valve synchronous, because it has only a valve.

Adopt the fuel oil inner cylinder direct injection to make this motor seem very simple.As shown in Figure 4.The implication of sequence number 1 to 8 and Fig. 1's is identical among the figure, the 9th, valve, the 10th, fuel injector, when scavenging process finishes soon, sparger with fuel injection to cylinder.Though be sparger, owing to defeat work down, therefore require not resemble diesel engine strictness (High Temperature High Pressure) low, its cost is also lower.Fuel also can mix with a spot of high-pressure air and sprays into, and can certainly resemble to spray into from the cylinder top the diesel engine.The common advantage of this several method is the fuel loss that does not have in the scavenging process.

Adopt the lubrication system the same simple certainly, but thisly have the mode of " oil sump " that the height of motor has been increased, also increased the volume of crankcase simultaneously, and this is unfavorable for the raising of power per liter with traditional four stroke engine.Adopt method as shown in Figure 5 to address this problem.Be processed with several trough on the crank of circle among the figure, they have constituted a centrifugal pump with the opening that crankcase reaches in the crankcase tangent direction.Lubricant oil in the crankcase is constantly pumped crankcase, along the transport pipe flow at high speed.When flowing to filter cleaner 1, flow to change rapidly, and flow velocity reduces, the impurity particle that contains in the oil is because action of inertia, break through filter screen 2 and be precipitated to cleaner bottom secction, pure lubricant oil is delivered to oil storage 3 along oil pipe through voltage limiter 5, is sent from the direction of arrow by oil storage 3 then.4 is oil storage lids among the figure, refuels and from then on carries out, and it keeps the sealing of oil storage.

The lubricant oil that flows out from oil storage can directly inject the middle friction pairs such as bent axle, connecting rod and wrist pin that are provided with oil duct.Under the less situation of crank diameter, centrifugal pump is less at the pressure that low velocity zone can provide, and in the time of can not satisfying the demand, can be forced into available degree with a gear pump or rotor pump again before lubricant oil is sent into said mechanism by oil storage.

Another kind of lubricating system is " spraying lubricated ".It is similar to " oil mist lubrication ".But owing to be the bigger machine oil of viscosity in the crankcase, there is not " oil mist lubrication " good sprayability like that, for increasing lubrication effect, can add some oil injecting nozzles by the suitable position in crankcase, make lubricant oil come out to need to strengthen lubricated position after oil injecting nozzle sprays to from oil storage 3 with atomization.

For further strengthening in scavenging air pipe, to increase by one " free valve ", as shown in Figure 6 every effect.1 and 7 is springs among the figure, the 2nd, and towards the port of crankcase, the 3rd, scavenging air pipe, the 4th, " free valve ", and the 5th, slide bar, " free valve " can be free to slide on bar.The 6th, another port of scavenging air pipe.An effect of spring be for free valve provide may be necessary buffering, another effect is the position of restraint of liberty valve, avoids free valve to go to limit position and ineffective.In fact, this " free valve " can not only further strengthen isolation effect, and it also has the effect of inertia supercharging.Suppose that it is to be formed from aluminium, because the density of aluminium is more than 2000 times of air, therefore " free valve " its effect of inertia of 0.5 millimeters thick just is equivalent to 1 meter air column how long.In other words, used after " free valve ", the pressurized effect that needs significant volume to realize when only needing very little volume just can realize valveless, its advantage is conspicuous.

More than the just principle schematic that provides among each figure, do not represent actual process structure.Scavenging fully can be identical with traditional two stroke engine with formula.But adopt directed symmetrical scavenging simple in structure and effect is better, as shown in Figure 7.1 is commutator lug among the figure, the 2nd, and cylinder block, the 3rd, relief opening, the 4th, a port of scavenging air pipe, the 5th, scavenging port.So-called directed scavenging is exactly to increase by one group of commutator lug in scavenging air belt, they are divided into several less scavenging air belts with scavenging air belt, make the direction of air-flow be controlled preferably (, in application number is 94221803 patent specification, more detailed explanation being arranged) about directed scavenging and effect thereof.Can certainly adopt the straight formula scavenging of cam control exhaust.

The air intake valve that provides among each figure is leaf valve.In fact, the valve of rotary valve or cam control etc. can be used, as long as it is opened and closed according to correct phase place.Just leaf valve is that wherein structure is the simplest a kind of, and its low-speed performance is better, and shortcoming is that certain pressure loss is arranged.

More than among each figure scavenging air pipe be schematic representation with connecting of crankcase.In fact, scavenging air pipe preferably is connected on crank and revolves on the vertical direction in plane, to reduce the influence of mist of oil as far as possible.Scavenging air pipe is not necessarily straight, and it can be crooked, for example is circular-arc, helical, or straight tube folding or the like, but it should have an angle with level, enough flows back to crankcase when airborne lubricant oil condenses so that be mixed on tube wall.

When multi-cylinder was used, the preposition scheme of Carburetor had its advantage: it only needs a Carburetor.Certainly scavenging air pipe respectively naturally independently comprises valve.Scheme shown in Figure 8 makes the rearmounted mode of carburetion also can be only with a Carburetor.1 is the scavenging air pipe of two cylinders among the figure, and it no longer directly leads to scavenging air belt, but converges to together by a leaf valve 6 respectively, and then closure 2, air passageways 3 and the Carburetor passage 4 by synchronization motion leads to separately scavenging port respectively.5 is that the Carburetor arrow is represented airflow direction among the figure, and wherein single arrow is represented air flow, and broad arrow represents that mixed steam flows to.The effect of leaf valve is to guarantee that air can only enter scavenging air pipe from the suction port of scavenging air pipe, can not cause the phase mutual interference between each cylinder.Can certainly be with the valve of other form, but with leaf valve for the simplest.Obviously, this method also is same being suitable for to multi-cylinder.If we change Carburetor among the figure 5 into fuel injection apparatus, and suitably control its time for spraying, we do not need special air scavenging road can realize " layered scavenging " too.When even scavenging port has just been opened, not oil spout of sparger behind certain hour, just begins to spray, and closes preceding end at scavenging port.Is the most suitable in kind of method to the twin-tub machine.When the cylinder number increases again, can increase the quantity of sparger again and air is divided into several, the sparger in every road is responsible for two cylinders.

When multi-cylinder was used, lubrication system also can partial common or all public.Lubricant oil all can be pumped into a public oil storage, send into each lubricant housings (can pressurize) then respectively.In this mode,, therefore will make air inflow to some extent with low because each crankcase has been connected in together by transport pipe.If we can make the pressure of outlet pressure in the crankcase of each " centrifugal pump ", or with its flow restriction in an acceptable scope, this influence will be very little.Especially after public oil storage through once more the pressurization situation under.Therefore, in multi-cylinder, we have just used compression pump in order to reduce the interference between each cylinder sometimes.

Claims

1, a kind of two stroke engine is characterized in that, its each cylinder has a scavenging air pipe 7 at least, and an end of scavenging air pipe communicates with crankcase 6, and the other end communicates with scavenging port 11, and communicates with suction port 10 by valve.Valve is opened during for negative pressure in crankcase, closes during for malleation.

2, a kind of motor as claimed in claim 1 is characterized in that: the total measurement (volume) of scavenging air pipe is 0.5-5 a times of cylinder displacement, and length is 2-20 times of its diameter.

3, a kind of motor as claim 1 and 2 is characterized in that: at the scavenging port place fuel injector 10 is housed.

4, a kind of motor as claim 1 and 2 is characterized in that: free valve is housed in scavenging air pipe.

5, a kind of motor as claim 1 and 2, it is characterized in that: the part of scavenging air pipe 7 between scavenging port and valve is divided into two scavenging air pipes, in these two scavenging air pipes, the closure 11 of two synchronization motions is housed, and in a scavenging air pipe Carburetor 10 is housed therein.

6, a kind of motor as claim 1 and 2 is characterized in that: it has two scavenging air pipes 7 and 8, in these two scavenging air pipes, the valve 12 and the closure 11 of synchronization motion is housed, and is arranged in following scavenging air pipe therein Carburetor 10 is housed.

7, a kind of motor as claim 1 and 2, it is characterized in that: its crank is circular, and has several trough at its end face, and the tangent line of circle is to having outlet in its crankcase, constituted a centrifugal pump, this pump can constantly pump the machine oil in the crankcase.

8, a kind of motor as claimed in claim 7 is characterized in that: it also has organic oil filter cleaner 1 voltage limiter 5 and oil storage 3.

9, a kind of motor as claim 7 and 8, it is held to levy and is: oil storage is airtight, machine oil wherein has among the crankshaft-link rod of oil duct in the middle of oil outlet is directly delivered to.

10, a kind of motor as claim 8 and 9, it is characterized in that: the machine oil in the oil storage is in oil injecting nozzle sprays into crankcase.