CN102278201A

CN102278201A - Method of operating reciprocating piston type engine and piston applied in reciprocating piston type engine

Info

Publication number: CN102278201A
Application number: CN201110123189XA
Authority: CN
Inventors: C·L·费尔特
Original assignee: MAN Diesel and Turbo Filial af MAN Diesel and Turbo SE
Current assignee: MAN Energy Solutions Filial af MAN Energy Solutions SE
Priority date: 2010-05-14
Filing date: 2011-05-13
Publication date: 2011-12-14
Anticipated expiration: 2031-05-13
Also published as: KR101855215B1; CN102278201B; KR20110126052A; JP5851718B2; DE102010020491A1; JP2011241982A; DE102010020491B4

Abstract

The invention relates to a piston applied in a reciprocating piston type engine. The piston (2) defines a working chamber (5) and can move inside a cylinder sleeve (3). A piston ring group (9) is applied for covering a gap (13) between the piston and the cylinder sleeve. The piston ring group comprises a plurality of piston rings (6, 7, 8) arranged in a front-back manner and respectively equipped inside a corresponding piston ring groove (10, 11, 12) of the piston (2). The piston rings can be loaded by the air inside the working chamber. In this way, a significant decrease in power loss and a basic balance in the service lifetime of each piston ring are realized. The gap between the piston and the cylinder sleeve is sealed by one piston ring farthest away from the working chamber in an airtight way. Controllable leakage is allowed on piston rings (6, 7) in front of each piston ring arranged farthest away from the working chamber. The pressure of the leaked air is reduced by the expansion of at least one expansion chamber (17) before the air reaches the piston ring arranged farthest away from the working chamber.

Description

The method and the piston that is used for conventional engine that are used for operating stroke piston formula motor

Technical field

The present invention relates to a kind of piston that is used for the method for operating stroke piston formula motor and is used for this conventional engine, piston especially for two stroke formula large-scale diesel engines, this piston is arranged in the corresponding cylinder liner as the boundary of active chamber, wherein the gap between piston and cylinder liner covers by a piston ring group, described piston ring group has the piston ring in the corresponding piston annular groove that be provided with in proper order, that be separately positioned on piston of a plurality of front and back, and these piston rings can be by the gas-loaded from active chamber.

Background technique

In common in practice such device, gas leakage is set all on all piston rings.For this reason, use the piston ring that cracks usually, the end of described piston ring is spaced apart from each other, thereby forms continuous from the top down slit, and described slit is formed for the flow path of gas leakage.But the cross section in described slit constantly increases along with the expansion gradually of associated piston ring, that is to say along with the increase of wearing and tearing to become big.

By the piston of the described type of the known beginning of EP 0742 875B1, wherein uppermost at least piston ring is configured to airtight piston ring, and this piston ring is provided with the groove of the circumference that is used to realize controlled leakage.The document also proposes, and a plurality of or all piston rings of piston ring group can be designed to have the airtight piston ring of the groove of the circumference that is used to realize controlled leakage.Therefore, under any circumstance on each piston ring of piston ring group, can realize leaking, thereby the leakage flow that the intensity of the gas selected from active chamber does not wait can occur, and the power loss that causes thus of appearance thus.Rule of thumb, in the device of described type, also can occur in front, the different piston rings of piston ring group have very different working life, this means high maintenance cost.

JP 2-48 737B2 discloses a kind of piston, wherein all piston rings all are configured to airtight piston ring, wherein set to piston ring groove these piston rings, stacked on top of each other to be connected to each other to realize controlled leakage by being arranged on flow path piston side, structure pore-forming etc.Here leakage flow is particularly stopped on nethermost piston ring.But therefore this nethermost piston ring is loaded in each expansion stroke strongerly, so rule of thumb wear and tear quickly than the piston ring that is positioned at its top.

In these two kinds of known devices, obviously in the piston ring group, need the piston ring of larger amt.But improve along with the quantity of piston ring in the friction of run duration appearance and the power loss that causes thus.Therefore, this known devices also can not realize the method for operation optimized to a great extent.

Summary of the invention

Set out thus, the objective of the invention is, improve the described prior art of beginning like this, make it possible to achieve balanced as far as possible working life of all piston rings and reduce power loss in simple, economic mode.

Piston in conjunction with the above-mentioned type, realize described purpose like this according to the present invention, have only apart from active chamber piston ring farthest and be configured to not have the possible airtight piston ring of leakage, for each is other, be equipped with the structure that is used to realize from the controlled leak of the gas of active chamber near the piston ring of active chamber location, between the piston ring that order is provided with before and after at least two of piston ring group, be provided with at least one expansion chamber, be used to make the gas leakage that occurred that additional expansion takes place, the volume of expansion chamber surpasses two volumes that not have annular space that the piston rings of order setting define before and after the additional allowance for expansion ground for this reason.

Utilize this measure to avoid the shortcoming of known arrangement reliably.Expansion chamber arranged according to the present invention has been realized the expansion that exceeds conventional degree of the gas leakage that occurred, that is to say and exceed degree possible in known layout, in known layout, in each annular space that defines by two piston rings respectively, equally also expand, therefore described expansion chamber advantageously plays buffering and delay unit, cushions in each expansion stroke of piston and postpones actuating pressure load to airtight piston ring by described buffering and delay unit.Can advantageously realize the firing pressure that born by the piston ring group thus to all piston rings and best distribution in long stroke range, this is favourable for the working life of realizing all piston ring equilibriums and has realized good utilization to operational energy.Also provide a kind of favourable possibility according to measure of the present invention: the quantity that reduces the piston ring of piston ring group with respect to known layout, the reduction of this loss that not only causes friction, and cause the reduction of dynamic force, and cause tangible power gain with respect to known devices thus.Another advantage according to measure of the present invention is, because expansion chamber also can easily be discerned, the expansion chamber that is arranged on piston side for example can check easily that in the zone of the scavenging port of cylinder liner this has made things convenient for maintenance according to piston of the present invention.

The favourable mode of execution of described upper measure and reasonably expansion scheme in each dependent claims, provide.

Advantageously set, the front of described at least airtight piston ring directly is provided with at least one expansion chamber.This measure is verified to be rational especially, because buffering and the delay to the load that occurred is particular importance at nethermost airtight piston ring place, because further leakage does not take place here.

Another favourable measure is that the breach that is provided with at least one piston side is as expansion chamber.This moment advantageously the volume size of expansion chamber determine aspect obtain big structural degrees of freedom.In addition, set out thus, the volume that is configured to the expansion chamber of piston side breach keeps substantial constant at run duration.Restriction that therefore, need not to worry to cause and that cause by the distortion that cylinder liner is in operation by the gap width between piston and cylinder liner at this.

The piston side breach that plays the expansion chamber effect can be configured to aptly flute profile around.This has not only realized simple manufacturing, but also has advantageously realized the stepless action on whole piston circumference.

It is contemplated that in another expansion scheme of above-mentioned measure the volume that is arranged on two each expansion chambers between the piston ring is equivalent to, preferably exceeds slightly the volume of a piston ring groove at least.Because the piston ring group that described measure advantageously can use piston ring to lack than piston ring groove, and a piston ring groove is occupied without piston ring.This groove does not need the common armouring (Panzerung) that is provided with certainly in piston ring groove, therefore can also be slightly different with cross section.Except foregoing advantage, also realized very compact layout.As mentioned above, reduce that piston ring is realized the reduction of friction and the reduction of the power loss that realized thus causing thus.Above-mentioned dead slot also advantageously causes the bigger spacing of each piston ring that is adjacent, and this helps enlarging the volume of expansion chamber.

Other favourable configuration of described upper measure and reasonably expansion scheme in remaining dependent claims, provide and can the explanation to embodiment draw in detail with reference to accompanying drawing by following.

Description of drawings

In the accompanying drawing that describes below:

Fig. 1 illustrates the vertical sectional view of upper area of the cylinder piston assembly of reciprocating IC engine,

Fig. 2 illustrates the perspective view of airtight piston ring,

Fig. 3 illustrates the unfolded drawing of the airtight piston ring of the leakage grooves with circumference, and

Fig. 4 illustrates the sectional view of piston ring under installment state of the type that Fig. 3 relates to, wherein, in order to simplify view, shown in all side channels of piston ring vertically draw with extending.

Embodiment

Main application fields of the present invention is the conventional engine that is configured to big-block engine, particularly for example is applied in two stroke formula large-scale diesel engines in the driving on naval vessel.The basic structure of this device and working method itself are known, therefore do not need to describe in detail under present case again.

Related cylinder-the piston assembly of Fig. 1 belongs to one or two stroke formula large-scale diesel engine.Shown cylinder-piston assembly comprises cylinder 1 and the piston 2 that is contained in this cylinder.Cylinder 1 comprise around cylinder liner 3 and be received in cylinder head 4 on this cylinder liner.Be provided with active chamber 5 in cylinder 1, the lower boundary of this active chamber forms by piston 2 guiding, that can move up and down in cylinder liner 3.The inflation of loading mainly for active chamber 5 to be made up of air by the air inlet slit in the lower area that is not shown specifically at this, be arranged on cylinder liner 3 and give active chamber 5 loading fuel by injection apparatus one that be not shown specifically equally, that be arranged in the zone of cylinder head 4 usually is in operation.In the big-block engine of this type, piston 2 is connected with a crosshead at this piston rod that is not shown specifically by one, and this crosshead is by the bent axle acting in conjunction of a connecting rod and motor.

For realizing the normal operation of motor, that is to say that for fear of combustion gas from active chamber 5 escape into the scavenging air box that is arranged on piston 2 belows strongly, be provided be received on the piston 2, on cylinder liner 3

piston ring

6,7,8 scraping, that order is provided with before and after the moving direction of piston.The so-called piston ring group 9 of the common formation of these piston rings, this piston ring group comprise three

piston rings

6,7,8 that are provided with along the moving direction front and back order of piston 2 in the example shown.Also can imagine and adopt more piston ring, perhaps lack piston ring to two.Each

piston ring

6,7,8 is received within the piston ring groove that matches 10,11,12 of piston 2.Be provided with in the example shown three set to three

piston rings

6,7,8, around

piston ring groove

10,11,12.

Each piston ring of piston ring group 9 covers the gap 13 between interior week of the periphery of piston 2 and cylinder liner 3 with the circumferential area of its radially outer, and realizes downward seal operation chamber 5 thus.

Piston

ring

6,7,8 for be installed on the piston 2 and for be implemented on the cylinder liner 3 reliably recline and must be in expansion in the radial direction.For this reason, around piston ring has movable relatively end.End described here can be configured to make them to define a slit that connects from the top down, and the leakage from the gas of active chamber 5 takes place through this slit.Fig. 2 illustrate another kind of type around sealing, seamless mode of structure.The piston ring of Fig. 2 institute foundation has the end regions of rabbeting each other by tenon and flute profile formula.Here, in Fig. 2 left side, an end regions is provided with to radial outside and that open wide, the chamber shape downwards breach 14.On Fig. 2 right side, zone, the other end is provided with along the circumferential direction outstanding finger 15, and the cross section of the cross section of described finger and breach 14 is complementary and rabbets in the breach.Here, breach 14 and finger 15 interlocking length each other is sized to, and making under the situation of piston ring expansion fully not can be owing to each other interlocking is eliminated in wearing and tearing.

Piston ring group 9 according to Fig. 1 is configured to, and makes nethermostly, that is to say apart from active chamber 5 piston ring 8 farthest closing gap 13 airtightly.Therefore this nethermost piston ring 8 is designed to airtight piston ring according to structural principle shown in Figure 2.On the contrary, be equipped with for two piston rings 6,7 that are arranged on the front to be used to the structure that realizes from the controlled leakage of active chamber 5 gases.This structure can be the slit of the above-mentioned type, can be other structure also perhaps, as make

piston ring groove

10,11,12 connected to one another, be arranged on flow channel piston side, form such as hole, or the breach of piston ring side or similar structure.Under any circumstance all obtain such flow path, via this flow path make be arranged on first, that is to say can be by the gas-loaded from active chamber 5 near the piston ring 7,8 of piston ring 6 back of active chamber 5 location.Piston

ring

6,7,8 is aptly a little less than corresponding piston

annular groove

10,11,12, thereby obtain from the gap 13 flow paths in zone that lead to the radially inner side of

piston ring groove

10,11,12, correspondingly

piston ring

6,7,8 is to realize that expansion is by the gas-loaded from active chamber 5 in the zone in week inwardly in its footpath.

In the example shown, the piston ring 6,7 that two tops of gas leakage should take place constitutes according to the forms of gas-tight piston ring equally, but in order to realize controlled leakage, described piston ring be provided with at least one, the groove 16 of preferred a plurality of circumferences.In the example shown, as shown in Figure 3, that piston ring 6,7 should have is a plurality of, at the groove 16 of these four circumferences that on circumference, distribute.These grooves are provided with obliquely with respect to plane of a loop aptly, the rotational motion of the piston ring that this helps matching.Fig. 4 illustrates best, and the degree of depth t of the groove 16 of circumference is greater than the width b in gap 13.Here, groove 16 be in operation effectively by cross section be equivalent to piston 2 unlapped, protrude in the groove zone of the periphery of piston 2 in other words, thereby obtain a mobile cross section, the area of this cross section is drawn with the product as the width c shown in the distance of parallel groove side in Fig. 3 of groove 16 by gap width b.Because the degree of depth t of groove 16 is greater than gap width b, so even described cross section can not change under the situation of relevant piston ring 6 or 7 wearing and tearing yet.The wearing and tearing thickness sum that degree of depth t allows in the working life that can imagine greater than gap width b and associated piston ring aptly makes describedly all to exist in whole working life by cross section.The groove 16 of circumference has been realized the controlled leakage on the piston ring 6,7 accurately is determined to lower level.

The gas leakage that passes the flow path that is formed by groove 16 that flows arrives the annular space that defines by two piston rings respectively, and step-down/expansion (Entspannung) takes place there.But because the width in gap 13 is smaller, thus this step-down do not have under the situation of addition thereto also very little.Therefore,, an expansion chamber 17 is set in the zone on these piston ring 8 tops, that is to say free space or the volume of comparing expansion with the situation of free space that does not have expansion or volume in order to give airtight lower piston ring 8 off-loads.With two conventional that arrange, that is to say that the step-down of defining according to annular space between the piston ring of the kind of arrangements of piston ring 6,7 or the piston ring arranged as layout known as described in starting, can realize with the annular space of the types of 18 expressions compares, expansion chamber 17 that is to say the step-down possibility of expansion for gas leakage provides additional step-down possibility.

In the embodiment according to Fig. 1, expansion chamber 17 directly is arranged in the front of airtight piston ring 8, and effect connects thereby form directly.The step-down of the gas of realizing in expansion chamber 17 that is occurred makes the gas pressure on the piston ring 8 that acts on the bottom reduce and makes this loadings postpone, described loading therefore with to the loading of the piston ring 7 that is arranged in the front just realization after a time lag at interval.This has realized and can utilize operational energy well on long piston stroke scope.Set out thus in addition, on occurring during maximum load to the airtight piston ring 8 of bottom, with the contact area of cylinder liner 3 in set up lubricating film.

As mentioned above, the volume of expansion chamber 17 is greater than between the piston ring 6,7 that is positioned at two tops or the volume of the annular space 18 between the piston ring of known arrangement structure, is not that the additional expansion of the gas that occurred is provided with expansion chamber there.

In according to embodiment shown in Figure 1, expansion chamber 17 forms by the breach of a piston side.Described breach for example can be hole radially etc.But suitable is, in the as directed example like that, be provided be used to form expansion chamber 17 around groove.As representing with solid line among Fig. 1 that it can have the configuration that is similar to piston ring groove.But also it is contemplated that other cross section, as dotting among Fig. 1.

The bearing capacity in zone that is positioned at the piston ring 7 of expansion chamber 17 tops for the supporting that makes piston 2 is not inflated chamber 17 infringements, set to the piston ring groove 12 of the piston ring 8 of the bottom that is arranged on expansion chamber 17 fronts with adjacent, set to the distance between the piston ring groove 11 of second piston ring 7 and enlarge from comparing with setting to the piston ring groove 10 of first piston ring 6 and setting to the normal slot pitch between the piston ring groove 11 of the second adjacent piston ring 7.Also realized the expansion of the annular space that defines by piston ring 7,8 thus, the expansion that this causes the expansion of free space and causes expansion chamber 17 thus.The annular space that enlarges like this may just be enough to be formed for the expansion chamber of after-expansion in some cases, thus the piston side breach that can abandon adding.But under the situation that does not have the piston side breach, can not realize desirable additional expansion usually with the degree of hope.

The volume of necessity of expansion chamber 17 be arranged on the piston ring of front, be that the leakage of expecting in the zone of piston ring 7 is coordinated mutually here.For leaking very weak situation, the volume of expansion chamber 17 can be that a times of conventional piston ring groove volume is to twice.For leaking very strong situation, can imagining is two to three times big volume of piston ring groove volume.Shown example is based on leaking very weak situation.Therefore, expansion chamber 17 can constitute by the form of piston ring groove.For what the combination of piston and piston ring group was suitable for here is to set the piston ring groove of the bigger quantity of many grooves for the piston ring of quantification.So, in the example shown, use piston 2 for the piston ring group 9 that only has three piston rings (an airtight piston ring 8 and two piston rings 6,7) with four piston ring grooves with controlled leakage, one of them piston ring groove, it is empty promptly keeping from top several the 3rd piston ring grooves, and piston ring is not set.Therefore, these piston ring grooves do not need conventional armouring etc. yet.Can certainly imagine the piston ring of other quantity.Under a kind of simple situation, the piston ring group 9 that only has two piston rings also can be set, these two piston rings are piston ring following, closing gap 13 airtightly and top, allow the piston ring of controlled leakage and be arranged on expansion chamber 17 between these two piston rings.

As mentioned above, the additional expansion of gas that realize, that occurred causes the tangible off-load of the airtight piston ring 8 of bottom in the expansion chamber 17 that is arranged on airtight piston ring 8 fronts, and this is for producing favourable effect its working life.The piston ring 6,7 that is arranged on the front is because in this permission, controlled leakage and off-load.These piston rings can be designed to, and make that working life of all

piston rings

6,7,8 of piston ring group 9 is roughly the same.For this reason, the quantity and/or the width of the groove 16 that can be for example be provided with by the flow path of correspondingly determining as controlled leakage are determined leakage permission, controlled on piston ring 6,7 individually.Therefore, the entire cross section of the groove 16 of upper piston ring 6,7 for example can be different, for example make to form so downward classification, that is, roughly make first piston ring 6 be used for the flow cross section of controlled leak greater than second piston ring 7 that is arranged on airtight piston ring 8 fronts.Also can imagine the possibility of the expansion that the gas that same raising is occurred in the zone between the piston ring 6,7 with controlled leakage is additional.

Top explanation is interpreted as the embodiment shown in the invention is not restricted to.

Claims

1. the piston that is used for conventional engine, piston especially for two stroke formula large-scale diesel engines, described piston is arranged in the cylinder liner (3) that sets as the border of active chamber (5), wherein the gap (13) between piston (2) and cylinder liner (3) covers by a piston ring group (9), described piston ring group has that a plurality of front and back are provided with in proper order, be arranged in the piston ring groove that sets (10 of piston (2), 11,12) piston ring (6 in, 7,8), described piston ring can be by the gas-loaded from active chamber (5), it is characterized in that, have only apart from active chamber (5) piston ring (8) farthest and be configured to not have the possible airtight piston ring of leakage, for each is other, the piston ring (6 of close active chamber (5) location, 7) set the structure that is used for realizing from the controlled leakage of the gas of active chamber (5), be provided with at least one expansion chamber (17) between the piston ring that order is provided with before and after at least two of piston ring group (9), be used for the additional expansion of the gas leakage that occurred.

2. piston according to claim 1 is characterized in that, the volume of expansion chamber (17) surpasses the volume that does not have the annular space (18) that order is provided with before and after the additional allowance for expansion ground piston ring (6,7) defines by two.

3. piston according to claim 1 and 2 is characterized in that, in the front of described at least airtight piston ring (8) at least one expansion chamber (17) is set directly.

4. each described piston in requiring according to aforesaid right is characterized in that described expansion chamber (17) comprises the breach of at least one piston side.

5. piston according to claim 4 is characterized in that, the relief configuration that belongs to the piston side of expansion chamber (17) becomes flute profile.

6. piston according to claim 5 is characterized in that, the groove that belongs to expansion chamber (17) constitutes according to the form of the piston ring groove that is not occupied by piston ring.

7. each described piston in requiring according to aforesaid right is characterized in that, each volume that is arranged on two expansion chambers (17) between the piston ring equals the volume of a piston ring groove (10,11,12) at least.

8. piston according to claim 7 is characterized in that, the volume of expansion chamber is in one times to three times scope of the volume of piston ring groove (10,11,12).

9. each described piston in requiring according to aforesaid right, it is characterized in that, described piston ring group (9) has a described airtight piston ring (8) and piston ring (7) that at least one is other at least, and described other piston ring limits expansion chamber (17) and has controlled leakage with airtight piston ring (8).

10. each described piston in requiring according to aforesaid right, it is characterized in that, be provided with three piston ring groove (10,11,12) and other grooves that are suitable for holding respectively a piston ring (6,7,8), described other groove as expansion chamber (17) and be positioned at last and penult piston ring groove (11,12) between.

11. each described piston in requiring according to aforesaid right is characterized in that, in the distance between the piston ring groove that is positioned at expansion chamber (17) both sides (11,12) greater than the distance between remaining piston ring groove (10,11).

12., it is characterized in that described airtight piston ring (8) has the end of rabbeting each other hermetically by the form of tenon and groove according to each described piston in the aforesaid right requirement.

13. according to each described piston in the aforesaid right requirement, it is characterized in that, each piston ring (6,7) that is arranged on airtight piston ring (8) front has the end of rabbeting each other hermetically by the form of tenon and groove equally, and is additionally provided with the breach that is used for controlled leakage.

14. piston according to claim 13, it is characterized in that, each piston ring (6,7) that is arranged on airtight piston ring (8) front all has the groove (16) of circumference, and the degree of depth of the groove of these circumferences (t) is greater than the wearing and tearing sum of width (b) with the piston ring thickness that allows on working life in the gap (13) between piston (2) and cylinder liner (3).

15. piston according to claim 14 is characterized in that, and the effectively total corresponding leakage cross section of flow cross section of groove (16) of circumference of piston ring (6,7) that is provided with the groove of circumference is less than the cross section between the end of the piston ring that cracks.

16., it is characterized in that according to each described piston in the aforesaid right requirement, determine the effectively size of leakage cross section individually for each piston ring (6,7) that is controlled leakage is provided with, make all piston rings all have identical working life.

17. be used for the method for operating stroke piston formula motor, particularly move the method for two stroke formula large-scale diesel engines, wherein define active chamber (5) by the piston (2) that is arranged in the cylinder liner (3), gap (13) between piston (2) and cylinder liner (3) covers by a piston ring group (9), described piston ring group has that a plurality of front and back are provided with in proper order, be separately positioned on the piston ring groove that sets (10 of piston (2), 11,12) piston ring (6 in, 7,8), described piston ring can be by the gas-loaded from active chamber (5), it is characterized in that, gap (13) between piston (2) and cylinder liner (3) is by sealing airtightly downwards apart from active chamber (5) piston ring (8) farthest, be arranged on apart from the piston ring (6 of active chamber (5) piston ring (8) front farthest at each, 7) go up the controlled leakage of permission, the pressure of gas leakage arrives apart from active chamber (5) piston ring (8) farthest before by reducing for the expansion in the expansion chamber (17) that is provided with that expands at least one.