CN102278201B

CN102278201B - Method of operating reciprocating piston type engine and piston applied in reciprocating piston type engine

Info

Publication number: CN102278201B
Application number: CN201110123189.XA
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: 2015-07-15
Anticipated expiration: 2031-05-13
Also published as: KR20110126052A; CN102278201A; JP2011241982A; DE102010020491B4; DE102010020491A1; JP5851718B2; KR101855215B1

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

Method for operating stroke piston formula motor and the piston for it

Technical field

The present invention relates to a kind of for the method for operating stroke piston formula motor and the piston for this conventional engine, especially for the piston of two stroke type large-scale diesel engines, this piston is arranged in corresponding cylinder liner as the boundary of active chamber, gap wherein between piston and cylinder liner is covered by a Piston volume tube, described Piston volume tube has the piston ring in corresponding piston ring groove that multiple tandem is arranged, that be separately positioned on piston, and these piston rings can by the gas-loaded from active chamber.

Background technique

In such device common in practice, all piston rings all arrange Leakage Gas.For this reason, usually use the piston ring cracked, the end of described piston ring is spaced apart from each other, thus forms continuous print gap from the top down, and described gap forms the flow path being used for gas leakage.But the cross section in described gap constantly increases along with the expansion gradually of associated piston ring, that is become large along with the increase of wearing and tearing.

By the piston of the described type of the known beginning of EP 0,742 875 B1, wherein at least uppermost piston ring is configured to airtight piston ring, and this piston ring is provided with the groove of the circumference for realizing controlled leakage.The document also proposes, and multiple or all piston rings of Piston volume tube can be designed to the airtight piston ring of the groove of the circumference had for realizing controlled leakage.Therefore, under any circumstance can realize leaking on each piston ring of Piston volume tube, thus there will be the leakage flow do not waited from the intensity of active chamber escaping gas, and occur the power loss that causes thus thus.Rule of thumb, in the device of type noted earlier, also there will be, the different piston rings of Piston volume tube have very different working life, this means high maintenance cost.

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

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

Summary of the invention

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

In conjunction with the piston of the above-mentioned type, described object is realized like this according to the present invention, only have and be configured to the possible airtight piston ring of No leakage apart from active chamber piston ring farthest, for each in addition, the piston ring of closer active chamber location is equipped with the structure of the controlled leak for realizing the gas from active chamber, at least one expansion chamber is provided with between the piston ring that at least two tandem of Piston volume tube are arranged, additional expansion is there is for making occurred gas leakage, the volume of the annular space that the piston ring that the volume of expansion chamber does not have additional allowance for expansion ground tandem to arrange more than two for this reason defines.

This measure is utilized to reliably avoid the shortcoming of known arrangement.Expansion chamber arranged according to the present invention achieves the expansion exceeding conventional degree of occurred gas leakage, that is degree possible in known layout is exceeded, equally also expand in each annular space defined by two piston rings respectively in known layout, therefore described expansion chamber advantageously plays buffering and delay unit, is cushioned by described buffering and delay unit and is postponed the actuating pressure load to airtight piston ring in each expansion stroke of piston.Can advantageously achieve the firing pressure that born by Piston volume tube thus to all piston rings and distribution best in longer stroke range, this is favourable for the working life realizing all piston ring equilibriums and achieves the good utilization to operational energy.Measure according to the present invention additionally provides a kind of favourable possibility: the quantity reducing the piston ring of Piston volume tube relative to known layout, the reduction of this loss that not only causes friction, and cause the reduction of dynamic force, and cause obvious power gain relative to known device thus.Another advantage according to measure of the present invention is, piston according to the present invention also can easily identify due to expansion chamber, and the expansion chamber being arranged on piston side such as can easily check in the region of the scavenging port of cylinder liner, this facilitate that maintenance.

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

Another favourable measure is, is provided with the breach of at least one piston side as expansion chamber.Now advantageously the volume size of expansion chamber determine in obtain large structural degrees of freedom.In addition, set out thus, the volume being configured to the expansion chamber of piston side breach keeps substantial constant at run duration.Therefore, at this without the need to worrying that caused by the gap width between piston and cylinder liner and that the distortion that is in operation by cylinder liner causes restriction.

The piston side breach playing expansion chamber effect can be configured to aptly flute profile around.This not only achieves simple manufacture, but also advantageously achieves in the stepless action circumferentially of whole piston.

In another expansion scheme of above-mentioned measure, it is contemplated that, the volume being arranged on each expansion chamber between two piston rings be at least equivalent to, preferably slightly exceed the volume of a piston ring groove.Because described measure advantageously can use the Piston volume tube that piston ring is fewer than piston ring groove, and a piston ring groove can be made simply to occupy without piston ring.This groove does not need the armouring (Panzerung) usually arranged in piston ring groove certainly, therefore can also be slightly different from cross section.In addition to the previous mentioned advantages, layout is closely also achieved.As mentioned above, reduce piston ring realize the reduction of friction and thus achieve the reduction of the power loss caused thus.Above-mentioned dead slot also advantageously causes the larger spacing of each piston ring be adjacent, and this is conducive to the volume expanding expansion chamber.

Other favourable configuration and the rational expansion scheme of described upper measure can draw in detail by referring to the explanation of accompanying drawing to embodiment.

Accompanying drawing explanation

In accompanying drawing described below:

Fig. 1 illustrates the vertical sectional view of the 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 piston ring sectional view in the mounted state of the type that Fig. 3 relates to, and wherein, in order to simplify view, all side channels of shown piston ring are drawn with vertically extending.

Embodiment

Main application fields of the present invention is the conventional engine being configured to big-block engine, is particularly such as applied in two stroke type 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 in the current situation to describe in detail again.

Cylinder-piston assembly involved by Fig. 1 belongs to one or two stroke type large-scale diesel engine.The piston 2 that shown cylinder-piston assembly comprises cylinder 1 and holds in the cylinder.Cylinder 1 comprise around cylinder liner 3 and the cylinder head 4 that is received in this cylinder liner.In cylinder 1, be provided with active chamber 5, the lower boundary of this active chamber passes through piston 2 that guide in cylinder liner 3, that can move up and down and is formed.Be in operation by be not shown specifically at this, air inlet gap in the lower area that is arranged on cylinder liner 3 load inflation primarily of air composition to active chamber 5 and be not shown specifically equally by one, injection apparatus in the region that is usually arranged on cylinder head 4 loads fuel to active chamber 5.In the big-block engine of this type, piston 2 is connected with a crosshead at this piston rod be not shown specifically by one, and this crosshead passes through the bent axle acting in conjunction of a connecting rod and motor.

For realizing the normal operation of motor, that is in order to avoid combustion gas escape into the scavenging air box be arranged on below piston 2 strongly from active chamber 5, be provided with receiving on the piston 2, in cylinder liner 3 scraping, the piston ring 6,7,8 that arranges along the moving direction tandem of piston.These piston rings form so-called Piston volume tube 9 jointly, and this Piston volume tube comprises the piston ring 6,7,8 that three moving direction tandem along piston 2 are arranged in the example shown.Also can imagine and adopt more piston ring, or less to the piston ring of two.Each piston ring 6,7,8 is received within the piston ring groove 10,11,12 matched of piston 2.Be provided with in the example shown three arrange to three piston rings 6,7,8, around piston ring groove 10,11,12.

Each piston ring of Piston volume tube 9 covers the gap 13 between the periphery of piston 2 and the inner circumferential of cylinder liner 3 with the circumferential area of its radially outer, and realizes downward pressurization working lumen 5 thus.

Piston ring 6,7,8 is in order to install on the piston 2 and in order to realize reliably reclining and must expand in radial directions in cylinder liner 3.For this reason, around piston ring there is relatively movable end.End described here can be configured to make them define a gap through from the top down, and the leakage from the gas of active chamber 5 occurs through this gap.Fig. 2 illustrate another kind of type around that close, seamless mode of structure.The piston ring of Fig. 2 institute foundation has the end regions rabbeted each other by tenon and flute profile formula.Here, on the left of Fig. 2, an end regions is provided with to radial outside and downward breach 14 that open wide, chamber shape.On the right side of Fig. 2, region, the other end is provided with along the circumferential direction outstanding finger 15, and the cross section of described finger and the cross section of breach 14 match and be scarfed in breach.Here, the size of breach 14 and finger 15 interlocking length is each other defined as, and makes the interlocking can not eliminated due to wearing and tearing completely when piston ring is expanded each other.

Piston volume tube 9 according to Fig. 1 is configured to, and makes nethermost, that is apart from active chamber 5 piston ring 8 closing gap 13 airtightly farthest.Therefore the structural principle of this nethermost piston ring 8 according to Fig. 2 is designed to airtight piston ring.On the contrary, the piston ring 6,7 be arranged on above to two is equipped with the structure for realizing the controlled leakage from active chamber 5 gas.This structure can be the gap of the above-mentioned type, or also can be other structure, as made, piston ring groove 10,11,12 is connected to each other, be arranged on piston side, the fluxus formae passage such as hole, or the breach of piston ring side or similar structure.Piston ring 7,8 after the piston ring 6 of under any circumstance all obtain such flow path, make to be arranged on first via this flow path, that is locating closest to active chamber 5 can by the gas-loaded from active chamber 5.Piston ring 6,7,8 is aptly a little less than corresponding piston ring groove 10,11,12, thus obtain the flow path in the region of the radially inner side leading to piston ring groove 10,11,12 from gap 13, correspondingly piston ring 6,7,8 in the region of its radial inner circumferential for realize expansion and by the gas-loaded from active chamber 5.

In the example shown, the piston ring 6,7 that two tops of Leakage Gas should occur is formed according to the form 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 multiple circumference.In the example shown, as shown in Figure 3, piston ring 6,7 should have multiple, at these four grooves 16 at the circumference circumferentially distributed.These grooves are arranged obliquely relative to plane of a loop aptly, and this is conducive to the rotational motion of the piston ring matched.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, being in operation of groove 16 is effectively equivalent to by cross section that piston 2 is unlapped, the groove region of the periphery that protrudes from piston 2 in other words, thus obtain a flow cross section, the area of this cross section by gap width b and groove 16 in figure 3 as parallel groove side distance shown in the product of width c draw.Because the degree of depth t of groove 16 is greater than gap width b, even if so described cross section also can not change when relevant piston ring 6 or 7 weares and teares.Degree of depth t is greater than the wear-thickness sum that gap width b and associated piston ring allow in the working life that can imagine aptly, makes describedly all to be existed in whole working life by cross section.The groove 16 of circumference achieves piston ring 6, and lower level is accurately determined in the controlled leakage on 7.

The gas leakage flowing through the flow path formed by groove 16 arrives the annular space defined by two piston rings respectively, and step-down/expansion (Entspannung) occurs there.But because the width in gap 13 is smaller, so this step-down is also very little when not having addition thereto.Therefore, in order to give airtight lower piston ring 8 off-load, an expansion chamber 17 is set in the region on this piston ring 8 top, the free space of that is expansion compared with the situation of the free space or volume that there is not expansion or volume.With two conventional that arrange, that is according to the kind of arrangements of piston ring 6,7 piston ring between annular space or the piston ring arranged of layout known as stated in the beginning define, with compared with the step-down achieved by the annular space of 18 types represented, the step-down possibility that expansion chamber 17 is additional for gas leakage provides, the step-down possibility that is expanded.

In the embodiment in accordance with fig. 1, expansion chamber 17 is directly arranged in before airtight piston ring 8, thus formation directly acts on connection.The step-down of the gas occurred realized in expansion chamber 17 makes the gas pressure acted on the piston ring 8 of bottom reduce and this loading is postponed, and therefore and to after loading interval one time lag of the piston ring 7 be arranged in above described loading just realizes.This achieve and can utilize operational energy well in longer piston stroke scope.Set out thus in addition, when in appearance on the airtight piston ring 8 of bottom during maximum load, with the contact area of cylinder liner 3 in establish lubricating film.

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

In the embodiment according to Fig. 1, expansion chamber 17 is formed by the breach of a piston side.Described breach can be such as radial hole etc.But desirably, in as directed example, be provided with for the formation of expansion chamber 17 around groove.As indicated by the solid line in Fig. 1, it can have the configuration being similar to piston ring groove.But also it is contemplated that other cross section, as represented by dashed line in Fig. 1.

Damage for the bearing capacity making the supporting of piston 2 be positioned at the region of the piston ring 7 above expansion chamber 17 is not inflated room 17, arrange to the piston ring groove 12 of the piston ring 8 of the bottom be arranged on before expansion chamber 17 with adjacent, to arrange to the piston ring groove 11 of the second piston ring 7 between distance with arrange to the piston ring groove 10 of first piston ring 6 and the normal slot pitch between arranging to the piston ring groove 11 of the second adjacent piston ring 7 from compared be expand.Also achieve the expansion of the annular space defined by piston ring 7,8 thus, this causes the expansion of free space and causes the expansion of expansion chamber 17 thus.The annular space expanded so in some cases may just be enough to form the expansion chamber for after-expansion, thus can abandon the piston side breach that adds.But the additional expansion desired by usually can not realizing with the degree of hope when not having piston side breach.

The volume of necessity of expansion chamber 17 be arranged on piston ring above, be that the leakage expected in the region of piston ring 7 is coordinated mutually here.For leaking very weak situation, the volume of expansion chamber 17 can be one times of conventional piston ring groove volume to twice.For leaking very strong situation, can imagine is the larger volume of two to three times of piston ring groove volume.Shown example is based on leaking very weak situation.Therefore, expansion chamber 17 can be formed by the form of piston ring groove.Combination for piston and Piston volume tube is suitable for here, and the piston ring for quantification should set the piston ring groove of the larger quantity of many grooves.So, in the example shown, the piston 2 with four piston ring grooves is used for the Piston volume tube 9 only with three piston rings (an airtight piston ring 8 and two have the piston ring 6,7 of controlled leakage), one of them piston ring groove, namely be empty from several 3rd piston ring groove keeps above, piston ring is not set.Therefore, these piston ring grooves do not need conventional armouring etc. yet.The piston ring of other quantity can certainly be imagined.In a simple case, the Piston volume tube 9 only with two piston rings also can be set, these two piston rings be below, airtightly closing gap 13 piston ring and above, allow the piston ring of controlled leakage and be arranged on the expansion chamber 17 between these two piston rings.

As mentioned above, cause the obvious off-load of the airtight piston ring 8 of bottom in the additional expansion being arranged on gas that realize in the expansion chamber 17 before airtight piston ring 8, that occur, this produces favourable effect for its working life.Be arranged on piston ring 6,7 off-load due to that allow at this, controlled leakage above.These piston rings can be designed to, and make the working life of all piston rings 6,7,8 of Piston volume tube 9 roughly the same.For this reason, the quantity of the groove 16 that can such as arrange by correspondingly determining flow path as controlled leakage and/or width, that determine the permission on piston ring 6,7 individually, controlled leakage.Therefore, the whole cross section of the groove 16 of upper piston ring 6,7 is as can be different, such as make to form so downward classification, that is, roughly make first piston ring 6 be greater than for the flow cross section of controlled leak the second piston ring 7 be arranged on before airtight piston ring 8.Also can imagine, in the region between the piston ring 6,7 with controlled leakage, improve the possibility of the expansion that the gas that occurs adds equally.

Explanation is above interpreted as, and the invention is not restricted to shown embodiment.

Claims

1. for the piston of conventional engine, described piston is arranged in the cylinder liner (3) of arranging as the border of active chamber (5), gap (13) wherein between piston (2) and cylinder liner (3) is covered by a Piston volume tube (9), described Piston volume tube has the setting of multiple tandem, be arranged in the piston ring groove (10 of the arranging of piston (2), 11, 12) piston ring (6 in, 7, 8), described piston ring can by the gas-loaded from active chamber (5), it is characterized in that, only have and be configured to the possible airtight piston ring of No leakage apart from active chamber (5) piston ring farthest (8), for each in addition, the piston ring (6 that closer active chamber (5) is located, 7) structure for realizing from the controlled leakage of the gas of active chamber (5) is arranged, at least one expansion chamber (17) is provided with between the piston ring that at least two tandem of Piston volume tube (9) are arranged, for the additional expansion of occurred gas leakage.

2. piston according to claim 1, it is characterized in that, the volume of the annular space (18) that the piston ring (6,7) that the volume of expansion chamber (17) exceedes the allowance for expansion ground tandem setting added by two nothings defines.

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

4. piston according to claim 1 and 2, 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 belonging to expansion chamber (17) is formed according to the form of the piston ring groove do not occupied by piston ring.

7. piston according to claim 1 and 2, is characterized in that, each volume being arranged on expansion chamber (17) between two piston rings at least equals the volume of a piston ring groove (10,11,12).

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

9. piston according to claim 1 and 2, it is characterized in that, described Piston volume tube (9) at least has a described airtight piston ring (8) and at least one other piston ring (7), and described other piston ring limits expansion chamber (17) and has controlled leakage together with airtight piston ring (8).

10. piston according to claim 1 and 2, it is characterized in that, be provided with three piston ring grooves (10,11,12) being suitable for holding respectively a piston ring (6,7,8) and an other groove, described other groove is used as expansion chamber (17) and is positioned between last and penultimate piston ring groove (11,12).

11. pistons according to claim 1 and 2, is characterized in that, the distance between the piston ring groove (11,12) being positioned at expansion chamber (17) both sides is greater than the distance between remaining piston ring groove (10,11).

12. pistons according to claim 1 and 2, is characterized in that, described airtight piston ring (8) has the end of rabbeting each other hermetically by the form of tenon and groove.

13. pistons according to claim 12, it is characterized in that, each piston ring (6,7) be arranged on before airtight piston ring (8) has the end of rabbeting each other hermetically by the form of tenon and groove equally, and is additionally provided with the breach for controlled leakage.

14. pistons according to claim 13, it is characterized in that, each piston ring (6,7) be arranged on before airtight piston ring (8) has the groove (16) of circumference, and the degree of depth (t) of the groove of these circumferences is greater than the width (b) in the gap (13) between piston (2) and cylinder liner (3) and the wear-thickness sum of the piston ring allowed on service life.

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

16. pistons according to claim 1 and 2, is characterized in that, determine the size of effectively leaking cross section individually, make all piston rings all have identical working life for each piston ring (6,7) for controlled leakage setting.

17. pistons according to claim 1, is characterized in that, described conventional engine is two stroke type large-scale diesel engines.

18. for the method for operating stroke piston formula motor, wherein define active chamber (5) by the piston (2) be arranged in cylinder liner (3), gap (13) between piston (2) and cylinder liner (3) is covered by a Piston volume tube (9), described Piston volume tube has the setting of multiple tandem, be separately positioned on the piston ring groove (10 of the arranging of piston (2), 11, 12) piston ring (6 in, 7, 8), described piston ring can by the gas-loaded from active chamber (5), it is characterized in that, gap (13) between piston (2) and cylinder liner (3) is by closing airtightly downwards apart from active chamber (5) piston ring farthest (8), be arranged on apart from the piston ring (6 before active chamber (5) piston ring farthest (8) each, 7) leakage that upper permission is controlled, the pressure of gas leakage passed through the expansion in the expansion chamber (17) arranged for expanding at least one and reduces before arriving distance active chamber (5) piston ring farthest (8).

19. methods according to claim 18, is characterized in that, described conventional engine is two stroke type large-scale diesel engines.