CN105736123A - Piston for inner-cylinder injection engine - Google Patents

Piston for inner-cylinder injection engine Download PDF

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Publication number
CN105736123A
CN105736123A CN201510982834.1A CN201510982834A CN105736123A CN 105736123 A CN105736123 A CN 105736123A CN 201510982834 A CN201510982834 A CN 201510982834A CN 105736123 A CN105736123 A CN 105736123A
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CN
China
Prior art keywords
recess
interval
curve
piston
terminal part
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN201510982834.1A
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Chinese (zh)
Inventor
谷口好正
桐村宗孝
上野慎司
金池聪志
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Mitsubishi Motors Corp
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Mitsubishi Motors Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mitsubishi Motors Corp filed Critical Mitsubishi Motors Corp
Publication of CN105736123A publication Critical patent/CN105736123A/en
Pending legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
    • F02F3/00—Pistons 
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B23/00—Other engines characterised by special shape or construction of combustion chambers to improve operation
    • F02B23/08—Other engines characterised by special shape or construction of combustion chambers to improve operation with positive ignition
    • F02B23/10—Other engines characterised by special shape or construction of combustion chambers to improve operation with positive ignition with separate admission of air and fuel into cylinder
    • F02B23/104—Other engines characterised by special shape or construction of combustion chambers to improve operation with positive ignition with separate admission of air and fuel into cylinder the injector being placed on a side position of the cylinder
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
    • F02F3/00—Pistons 
    • F02F3/26—Pistons  having combustion chamber in piston head
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B75/00—Other engines
    • F02B75/12—Other methods of operation
    • F02B2075/125—Direct injection in the combustion chamber for spark ignition engines, i.e. not in pre-combustion chamber
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
    • F02F3/00—Pistons 
    • F02F2003/0007—Monolithic pistons; One piece constructions; Casting of pistons
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Combustion Methods Of Internal-Combustion Engines (AREA)

Abstract

The invention discloses a piston for an inner-cylinder injection engine. A recessed part which is formed at a top part of the piston clamps an axial core of the piston. The axial core is arranged between a recessed part starting end part on one side and a recessed part terminating end part on the other side. At a position of the maximum width part, which has the maximum width in a direction orthogonal to a starting-terminating central line which connects the recessed part starting end part and the recessed part terminating end part and penetrates the axial core, along the starting-terminating central line with respect to the side of the recessed starting end part on which the axial core is arranged, the distance from the maximum width part to the recessed part terminating end part along the starting-terminating central line is set to be shorter than the distance between the axial core and the recessed part starting end part. The recessed part of the piston is provided with a starting end side curve section along an end edge on the side of the recessed part starting end part. The recessed part of the piston is provided with a terminating end side curve section with a curve radius relatively greater than that of the starting end side curve section along an end edge on the side of the recessed part terminating end part.

Description

Direct injection engine piston
Technical field
The present invention relates to the piston of a kind of direct injection engine for directing injection of fuel in cylinder.
Background technology
Possessing in the cylinder injection type petrol engine of the cylinder injection valve of cylinder inner direct fuel, such as, in high load area, the mixing gas of air-fuel ratio of homogenizing is imported to carry out homogeneous combustion in cylinder, and in low-load region, by being divided into the burning mixture layer of fuel rich and lack of fuel in cylinder or almost only having the lean mixture gas layer of air, layering lean burn (stratified combustion) is controlled.
When stratified combustion, utilize the air-flow etc. in the cylinder caused along with the decline of piston, and prevent gasoline and air to be mixed with each other equably, so that the burning mixture layer phase after the compression stroke assembles around spark plug, air-flow is controlled by lean mixture gas layer in the mode assembled near piston-top surface side.
But, in patent documentation 1, disclose on the position being partial to inlet valve side in piston-top surface, form the technology in orbicular recess (peviform) under top view.When piston is positioned near top dead center, the spray axis towards the cylinder injection valve in cylinder points to this recess.
In this piston, when homogeneous combustion, a pair air entry possessed from a cylinder imports fresh air in cylinder, produces to rotate the tumble flow of whirlpool as stronger longitudinal direction.Fuel is injected in cylinder in intake stroke, and this fuel by tumble flow at cylinder internal diffusion, thus the homogenizing of the mixing air realized in cylinder.
In addition, when being layered lean burn, by the control to the air shut-off valve being located in air entry, only from a pair air entry, one air entry imports fresh air in cylinder, while the composition of tumble flow is relatively weakened, and the eddy current of whirlpool in the horizontal direction is enhanced.
Then, in the later half of compression stroke, the fuel sprayed from cylinder injection valve to the recess of top land moves to the spark plug side of top of combustion chamber along with the eddy current in recess, and forms inflammable burning mixture layer around spark plug.
At first technical literature
Patent documentation
Patent documentation 1: Japan JPH11-210551A
Summary of the invention
Such as above-mentioned example, in cylinder injection type petrol engine, it is necessary to successfully guided around spark plug by the fuel sprayed from cylinder injection valve, and around this spark plug, form inflammable mixing gas.
But, the fuel injection region of cylinder injection valve is the fan shape that the direction in the axle center (top view center) from the spout of cylinder injection valve to piston slowly expands, to this, recess is the circular under top view like that if as discussed above, then the jeting area of this fuel will not drop in recess, and occasionally results in the outside extending to the ora terminalis by recess.
In this case, fuel can overflow to the outside diameter by recess, it is impossible to assembles required fuel around spark plug.Thus, owing to pinking or the increase etc. due to carbon distribution can be occurred to cause the reasons such as advanced ignition, therefore it is not preferred.
It addition, the scope unconditionally expanding the recess corresponding with the jeting area of fuel can cause the decline of piston rigidity.Additionally, for the decline making up this rigidity, if by from top bank, namely top bank groove is thickening to the part of piston-top surface, then can cause the increase of piston weight.
Therefore, the problem of the present invention is in that to suppress the rigidity of piston to decline and while weight increase, and the fuel that will spray from cylinder injection valve, is efficiently guided in the recess formed by piston-top surface, and concentrates required fuel around spark plug.
In order to solve above-mentioned problem, the present invention adopts a kind of direct injection engine piston, it is formed in the direct injection engine piston of recess at this at piston-top surface, described recess clips the axle center of piston, it is located between the recess top portion of side and the recess terminal part of opposite side, in described recess, with be connected described recess top portion and described recess terminal part, the Breadth Maximum portion that width is maximum on the direction that the centrage of end all the time in described axle center is orthogonal compares described axle center on the position of side, portion, described recess top along the described centrage of end all the time, along the described centrage of end all the time from described Breadth Maximum portion, distance to described recess terminal part is set as being shorter than the distance from described axle center to described recess top portion.
The described recess of described piston can adopt following structure: it is interval that the ora terminalis along described recess beginning end side possesses side, top curve, and described recess possesses sweep along the ora terminalis of described recess terminal part side, and to be relatively larger than the interval end side curve of side, described top curve interval.
These each structures can adopt following structure: described end side curve interval has the part of the radius longer with 1/2nd of the spacing of described recess terminal part than described recess top portion, and curve interval, side, described top has the part of the radius shorter with 1/2nd of the spacing of described recess terminal part than described recess top portion.
Further, in these each structures, it is possible to adopt following structure: sweep is relatively smaller than the interval curve interval, side of described end side curve and is connected respectively to the two ends that described end side curve is interval.
Now, curve interval, described side can adopt following structure: has the part of the radius shorter than 1/2nd of the distance between described recess top portion and described recess terminal part.
Furthermore it is possible to adopt following structure: along with from described recess initial portion from and interval from the installation that is gradually distance from of centrage of described end all the time, two ends interval with side, described top curve respectively are connected.
Due to the fact that the recess that will be formed in piston head, the axle center clipping piston between the recess top portion being located at side and the recess terminal part of opposite side, and, in described recess, with be connected described recess top portion and described recess terminal part, the Breadth Maximum portion that width is maximum on the direction that the centrage of end all the time in described axle center is orthogonal compares described axle center on the position of side, portion, described recess top along the described centrage of end all the time, along the described centrage of end all the time from described Breadth Maximum portion, distance to described recess terminal part is set as being shorter than the distance from described axle center to described recess top portion, what therefore the scope of the recess of piston head will not become is excessive, recess can become necessity of the fuel for receiving from the injection of cylinder injection valve and sufficient scope.
Thereby, it is possible to while the rigidity suppressing piston declines and weight increases, the fuel that will spray from cylinder injection valve, effectively put in the recess of top land, and around spark plug, collect required fuel.
Accompanying drawing explanation
Fig. 1 illustrates the piston shown in an embodiment of the invention, (a) of Fig. 1 is top view, (b) of Fig. 1 is (c) of section B-B figure, Fig. 1 of Fig. 1 (a) is the C-C sectional view of Fig. 1 (a).
Fig. 2 is the axonometric chart of the piston of this embodiment.
Fig. 3 is the sectional view in the cylinder of the electromotor illustrating the piston accommodating this embodiment.
Fig. 4 is the top view of the piston illustrating this embodiment and observes schematic diagram with the front of the position relationship of cylinder injection valve.
(a) of Fig. 5～(e) is the top view of the process illustrating the shape determining piston-top surface recess.
(a) of Fig. 6～(c) is the top view of the details illustrating piston-top surface recess.
Fig. 7 is the top view of the piston of the embodiment illustrating other and illustrates that schematic diagram is observed in the front of the position relationship with cylinder injection valve.
Fig. 8 is the top view of the piston of the embodiment illustrating other further and observes schematic diagram with the front of the position relationship of cylinder injection valve.
Fig. 9 is the amplification sectional view of the major part of piston.
Detailed description of the invention
Hereinafter, illustrate based on accompanying drawing and to an embodiment of the invention.Present embodiment is the four-stroke gasoline engine of cylinder injection type automobile and for the piston of this electromotor.Fig. 1 and Fig. 2 shows the details of piston, and Fig. 3 shows the major part of the combustor 3 in the cylinder that this electromotor possesses and the structure of electromotor.The component etc. being directly connected to the present invention is only shown in figure 3, and the diagram of other component etc. is omitted.Although additionally, illustrate only a cylinder 1 in figure 3, but electromotor can be single-cylinder, it is also possible to be the multi cylinder possessing multiple cylinder 1.
As it is shown on figure 3, hold piston 2 in the cylinder 1 of electromotor.By the end face etc. of the internal face of cylinder 1 and piston 2, form combustor 3.Additionally, in cylinder 1, possess guide air to enter the air entry 5 of combustor 3, from the air vent 6 of combustor 3 aerofluxus and the spark plug 4 etc. that configures downwardly along the cylinder shaft of the axis of cylinder, i.e. cylinder from cylinder head side.Additionally, the direction of spark plug is not limited to this.
Cylinder 1 possesses the cylinder injection valve 9 to combustor 3 inner direct fuel.Cylinder injection valve 9 is arranged near the opening of the periphery of close top in combustor 3, air entry 5.As it is shown on figure 3, the fuel injection direction of cylinder injection valve 9 be this spraying centrage j0 along with from the periphery of combustor 3 towards central authorities, gradually to the incline direction that piston head (end face of piston 2) is close.By the spraying centrage j0 of this fuel hereinafter referred to as incline direction spraying centrage j0.Fuel is sprayed by this incline direction centered by centrage j0, sprays in the way of fan shape uniformly spreads from the spout of cylinder injection valve 9.
In the present embodiment, a cylinder is equipped with two air entries 5.In each air entry 5, it is provided with the air-breathing door 7 opening and closing the peristome to combustor 3 opening respectively.Additionally, a cylinder is equipped with two air vents 6.In 2 air vents 6, it is provided with the exhaust valve 8 opening and closing the peristome to combustor 3 opening respectively.These air-breathing doors 7 and exhaust valve 8 are by being located at the rotation of the camshaft of cylinder head side, and open or close air-breathing door 5 and exhaust valve 6 with predetermined timing.
Equipment needed for the action of air-breathing door 7, exhaust valve 8, spark plug 4, cylinder injection valve 9 and other electromotor is that the control unit that the electronic control unit (ElectronicControlUnit) possessed by carrying the vehicle of this electromotor possesses controls.
Additionally, in the present embodiment, it is possible to optionally control air-breathing door 5, for instance so that an air-breathing door 5 is the same time from the opening and closing of another air-breathing door 5 timing and makes each other for the different time.Furthermore it is possible to optionally control exhaust valve 6, for instance so that an exhaust valve 6 is the same time from the opening and closing of another exhaust valve 6 timing and makes each other for the different time.
By these controls to valve with to the control during combustion jet, such as, in high load area, the mixing gas of air-fuel ratio of homogenizing can be imported to carry out homogeneous combustion in combustor 3, and in low-load region, by being divided into the burning mixture layer of fuel rich and lack of fuel in combustor 3 or can almost only have the lean mixture gas layer of air, carry out layering lean burn (stratified combustion).
Cylinder injection valve 9 is arranged between two air-breathing doors 7.Cylinder injection valve 9 is at least configured to incline direction spraying centrage j0 and points to the part being slightly closer to cylinder injection valve 9 compared with the axle center O of piston 2 when piston 2 is near top dead center.Symbol P shown in Fig. 3 indicates that when the fuel of cylinder injection valve 9 in one cycle starts to spray, the intersection point of incline direction spraying centrage j0 and piston head.At this, the axle center O of piston 2 is consistent with the cylinder shaft heart of the cylinder 1 that spark plug 4 is positioned at.
As shown in Figures 1 and 2, the piston rostral of piston 2 is formed as cylindric or cylindric, and at side lower, between the piston skirt 2a and piston skirt 2a of a pair, possess piston boss portion 2b.Additionally, possessing cooling duct 2c, cooling duct 2c at periphery is all-round continuous print annulus along the circumferential direction.
Outer peripheral face at piston 2 possesses the groove 2e holding piston ring 2d.In the present embodiment, three groove 2e are formed accordingly with three piston ring 2d.Part near the top surface side of the groove 2e of piston rostral is top bank.
Piston head is formed with recess 10 so that guide the fuel from In-cylinder injector 9 injection.Recess 10 is located at piston-top surface.
Recess 10 clips the axes O of piston 2 and is located between the recess terminal part A1 of the recess top portion A2 of side and cylinder injection valve 9 side and the opposite side of opposite side and cylinder injection valve 9.
As shown in Figure 4, along top, coupling recess portion portion A2 and recess terminal part A1, axes O through piston 2 and orthogonal with this axle center O centrage j2 of end all the time, is arranged to shorter than from the distance L2 axle center O to recess top portion A2 from the distance L1 axle center O to recess terminal part A1.It addition, end centrage j2 is the direction orthogonal under top view of the axis direction relative to piston boss portion 2b all the time.
The position of recess top portion A2 is along the direction from the nozzle exit area J' of cylinder injection valve 9 to axle center O and be positioned at the position directly below J of distance L11 down position for benchmark, to compare this position directly below J only on the position of axle center O lateral extent L3.Recess top portion A2 is set so that in the bottom surface 11 that the jeting area of the fuel of cylinder injection valve 9 drops on recess 10.Additionally, position directly below J is positioned at from the position of the outer rim distance L4 to the inside of piston 2.
The position of recess terminal part A1 is set as that the fuel touching the bottom surface 11 of recess 10 is directed to recess terminal part A1 side, and touch the end wall of this recess terminal part 1 to spark plug 4 side conversion direction, and can be formed around spark plug 4 on the position of dense fuel bed.In the present embodiment, the position of recess terminal part A1 is with the point in the ratio of general about 1:2 point by the intersection point A3 of the axle center O of piston 2 and the ora terminalis of end centrage j2 and piston 2 all the time, and this interior proportion by subtraction rate can according to the injection pressure of the diameter of piston 2 or fuel and other etc. the specification of electromotor suitably determine.
Additionally, the recess 10 of piston 2 possesses curve interval, side, top 12 along the ora terminalis of A2 side, recess top portion, the recess 10 of piston 2 possesses sweep along the ora terminalis of recess terminal part A1 side and is relatively larger than the end side curve interval 13 in curve interval, side, top 12.
End side curve interval 13 has the part of the radius r-1 of 1/2nd of the distance L1+L2 being longer than between recess top portion A2 and recess terminal part A1.Additionally, curve interval, side, top 12 has the part of the radius r-3 shorter than 1/2nd of the distance L1+L2 between recess top portion A2 and recess terminal part A1.
In the present embodiment, side, top curve interval 12 and end side curve interval 13 are the curve interval (R3, R1) being made up of single sweep r-3 and r-1 respectively, but it can also be made to change radius in midway.However, it is preferable that there is no a breakpoint etc. in midway, and there is no a discontinuous part of curvature and curvature can recur change.Now, continuous print, the radius more shorter than 1/2nd of L1+L2 between side, the top curve interval 12 preferred whole districts.Similarly, continuous print, the radius more longer than 1/2nd of L1+L2 between the end side curve interval 13 preferred whole districts.
The two ends in end side curve interval 13 it are connected respectively to as the curve interval, side 19 of the sweep r-2 of the sweep r-1 being relatively smaller than end side curve interval 13.Curve interval, side 19 has the part of the radius r-2 shorter than 1/2nd of distance L1+L2.
In the present embodiment, the sweep r-2 in side curve interval 19 is set as equal with the sweep r-3 in curve interval, side, top 12.If making the sweep r-2 in curve interval, side 19 equal with the sweep r-3 in curve interval, side, top 12, it is possible to the simplification of processing when realizing manufacturing.But it is also possible to this sweep r-2 is set to different from sweep r-3.
It addition, in the present embodiment, curve interval, side 19 is the curve interval (R2) being made up of single sweep r-2, but it can also be made to change radius in midway.However, it is preferable that there is no a breakpoint etc. in midway, and there is no a discontinuous part of curvature and curvature can recur change.Now, continuous print, the radius more shorter than 1/2nd of L1+L2 between the side curve interval 19 preferred whole districts.
It is gradually distance from holds the interval 18 of installing of centrage j2 to be connected with the two ends in curve interval, side, top 12 respectively all the time along with separating from recess top portion A2.In the present embodiment, install interval 18 to be made up of the straight portion (U1) of linearity.Additionally, install interval 18 to be not limited to straight portion (ス ト レ ト portion), it is also possible to be the arcuation (circular arc) being made up of radius big fully.
The end installing interval 18 ends with curve interval, side 19 by connecting curve interval, side, top 12 is constituted.Installing interval 18 parallel with injection border line j1, this injection border line j1 illustrates the outer rim of the fuel injection region of the cylinder injection valve 9 for the jet width direction orthogonal with holding centrage j2 all the time.The fuel injection region of cylinder injection valve 9 is under top view, with the sector region in the injection border line j1 shown in the angle [alpha] in (a) of Fig. 1.
But, the installation portion 18 being made up of this straight portion is not parallel to injection border line j1, it is also possible to be configured to become a small angle mutually.But, install interval 18 preferably more outward than injection border line j1.As long as additionally, install interval 18 along injection border line j1, part or all of installation interval 18 can also be made up of the smooth curve not having breakpoint.Now, interval curve preferably its sweep contained by 18 of installation is the circular arc bigger than curve interval, side, top 12, end side curve interval 13 and curve interval 19, side, so as to successfully guided by fuel to interval 19 sides of side curve.
Such as present embodiment, when end side curve interval 13 is the curve being made up of single sweep r-1, the center O1 of the circular arc in end side curve interval 13 is from (the phase after the compression stroke when spraying fuel than cylinder injection valve 9 during period (サ イ Network Le), such as, compression top center 40CA), compare incline direction spraying centrage j0 and the cross point P of the bottom surface 11 of recess 10 of fuel, be only arranged in A2 side, recess top portion with distance L8.Symbol L5 in figure be between axle center O and center O1 along the distance holding centrage j2 direction all the time.
Additionally, the center O1 of the circular arc in end side curve interval 13 is arranged in the intersection point C midpoint C each other of the ora terminalis than injection border line j1 and recess 100With the distance L8-L9 position closer to A2 side, recess top portion.Here symbol L9 is intersection point P and midpoint C0Between along the distance holding centrage j2 direction all the time.
When curve interval, side, top 12 is the curve being made up of single sweep r-3, the center O3 of the circular arc in curve interval, side, top 12 is arranged in and sprays the centrage j0 cross point P with the bottom surface 11 of recess 10 with the distance L8+L6 side position closer to recess top portion A2 than incline direction.The center O3 of the circular arc in curve interval, side, top 12 is arranged between the intersection point C than injection border line j1 and the ora terminalis of recess 10 the midpoint C of (with reference to distance W3 from holding centrage j2 all the time in figure)0, with the distance L8-L9+L6 position closer to A2 side, recess top portion.Here distance L6 be between center O1 and center O3 along the distance holding centrage j2 direction all the time.
Intersection point C is the intersection point of side curve interval 19 and injection border line j1.Additionally, Breadth Maximum portion WmaxClip through line orthogonal with end centrage j2 all the time for intersection point P, be positioned at the opposition side of the side at intersection point C place.Breadth Maximum portion WmaxIt is positioned at curve interval, side 19, and is for the jet width direction orthogonal with holding centrage j2 all the time, the position that the width of recess 10 is the widest.
Breadth Maximum portion WmaxAlong holding centrage j2 to be positioned at the ratio axle center O position closer to A2 side, recess top portion all the time, and along holding centrage j2 all the time, from Breadth Maximum portion WmaxDistance LW between recess terminal part A1 is set to be shorter than the distance L2 from axle center O to recess top portion A2.
Symbol B1 in figure is the junction point in end side curve interval 13 and curve interval, side 19, and symbol B2 is as Breadth Maximum portion WmaxPlace, symbol B3 is side curve interval 19 and the junction point installing interval 18, symbol B4 be install interval 18 with the junction point in curve interval, side, top 12.The linear wiring direction on mutual junction point each other in the interval, both sides clipping each junction point is consistent, and does not have breakpoint to couple together glossily.
Additionally, intersection point P, midpoint C0And Breadth Maximum portion WmaxPosition can also be consistent mutually along the direction holding centrage j2 all the time.For example, it is possible to consider, among three points, intersection point P and midpoint C0Position along the consistent state in direction holding centrage j2 all the time, Breadth Maximum portion WmaxThe state consistent along the direction holding centrage j2 all the time with the position of intersection point P, Breadth Maximum portion WmaxWith midpoint C0Position along the consistent state in direction holding centrage j2 all the time, or be that the position of three points is all along the state that the direction holding centrage j2 all the time is consistent.But, from effectively catching this viewpoint of injected fuel in the recess 10 of limited area, the position of intersection point P and Breadth Maximum portion WmaxPosition preferably, consistent mutually along the direction holding centrage j2 all the time.
Additionally, as shown in Figures 1 and 2, piston 2 possesses the concave groove 21,23 for preventing around recess 10 interference between suction valve 7,8.Additionally, piston 2 is along the periphery of air-breathing door 7 side, possess side, top circumference 22, and along the periphery of exhaust valve 8 side, possess end side circumference 24.
It addition, the periphery to described jet width direction at piston 2 possesses the side end face 25 of inclination and the side circumference 26 in the direction, face with axis perpendicular.Side circumference 26 is relative with the upper wall surface of cylinder 1, forms the squish area discharged by fuel from the circumference in combustor 3 to central authorities.
Between recess 10 and groove 23, and between recess 10 and side end face 25, possesses the piston-top surface 27 in the face direction vertical with axle center O.Additionally, piston-top surface 27 can also be not provided with according to specification.
As shown in the sectional view of Fig. 9, the ora terminalis of recess 10, in recess terminal part A1 side, possesses chamfered section 14, vertical component effect 15 and end side curved portions 16 successively from piston-top surface 27 to bottom surface 11.Between this structure whole district for end side curve interval 13 and curve interval, side 19.End side curved portions 16 is with central angle alpha 1 (α 1=90 °) and is configured to connect bottom surface 11 and vertical component effect 15 in the scope of height B.As shown in the sectional view of Fig. 9, vertical component effect 15 is formed parallel to axle center O in any cross section parallel with axle center O.
In fig .9, symbol Q1 is the bottom surface 11 junction point with end side curved portions 16 of recess 10.On this junction point Q1, the curved surface of the plane of bottom surface 11 and end side curved portions 16 does not have breakpoint smoothly to link together.Symbol Q2 is the junction point of end side curved portions 16 and vertical component effect 15.On this junction point Q2, the cylindric face of vertical component effect 15 does not have breakpoint smoothly to link together with the curved surface of end side curved portions 16.Symbol Q3 and symbol Q4 is the beginning and end of the chamfered section 14 being made up of lateral dimension C1 and vertical dimension C2.As long as this lateral dimension C1 and vertical dimension C2 can guarantee the height A of vertical component effect 15 fully, it is possible to is freely disposed.
From the fuel of cylinder injection valve 9 injection after touching the bottom surface 11 of recess 10, curve interval, incoming terminal side 13.Or, arrive and interval 18 and side curve interval 19 be installed and move along installation interval 18 and curve interval, side 19, thus reaching end side curve interval 13.At this, fuel rushes to the end side curved portions 16 being smoothly docked to smooth bottom surface 11, and is guided to along vertical component effect 15 direction parallel with axle center O, and guides smoothly to spark plug 4 side.
Here, as it is shown in figure 9, the neutral line f1 of piston 2 connects the upper surface of side, top circumference 22 and the upper surface of end side circumference 24, and with neutral line f1 for boundary, the bottom surface 11 of recess 10 is positioned at downside (crankshaft side), and piston-top surface 27 is positioned at upside (cylinder head side).End side curved portions 16, in the position than neutral line f1 more top, is connected with vertical component effect 15.Neutral line f1 be calculate compression height (center of piston boss portion 2b, namely from the center of piston pin to the shoulder of piston 2 distance) datum level.Owing to end side curved portions 16 and vertical component effect 15 connect on the position than neutral line f1 more top, therefore, it is possible to expand the sweep R1 of end side curved portions 16, enabling fuel is successfully guided to spark plug 4 side.
From neutral line f1 to piston-top surface, the height h2 of 27 is set as that the height h3 of the bottom surface 11 than from neutral line f1 to recess 10 is low.From the bottom surface 11 of recess 10 to the height h1 of piston-top surface 27 be height h2 with height h3 sum.
Owing to the ridge line section between vertical component effect 15 and piston-top surface 27 is not arc, but what the chamfered section 14 being made up of C face was constituted, therefore, it is possible to make the region of vertical component effect 15 become wider along the axle center of piston 2.That be due to, it is assumed that making ridge line section is arc, then cannot substantially ensure that the length (length on axis direction) of vertical component effect 15.Additionally, by making ridge line section be formed as arc, air-flow can flow along the circular arc of this curved portions, but the chamfered section 14 by being made up of C face, air-flow can be peeled off and easily supply near spark plug.
Additionally, by being constituted ridge line section by chamfered section 14, it is possible to make the degree of depth (being equivalent to described height h1) of recess 10 shoal, and can be no longer necessary to as made end face thickening etc., for guaranteeing the various countermeasures of rigidity.If additionally, recess 10 is shallow, it is also possible to substantially ensure that and the interval of cooling duct 2c.
In addition, in A2 side, recess top portion and interval 18 sides of installation, the ora terminalis of recess 10 is constituted by connecting the bottom surface 11 side, the top curved portions 17 with side, top circumference 22 or groove 21, and side, top arc step 17 is located in the scope of central angle alpha 2 (α 2 < 90 °).
In the present embodiment; the sweep R1 of end side curved portions 16 is equal with the sweep R2 of side, top curved portions 17; but from the view point of guarantee the component rigidity of piston, the sweep R2 of side, top curved portions 17 is preferably set as less than the sweep R1 of end side curved portions 16.Additionally, the magnitude relationship of sweep R1 and sweep R2 numerical value is not limited to these embodiments.
In fig .9, symbol Q5 is the bottom surface 11 junction point with side, top curved portions 17 of recess 10.On this junction point Q5, the curved surface of the plane of bottom surface 11 and side, top curved portions 17 does not have breakpoint smoothly to link together.Symbol Q6 is the junction point of side, top curved portions 17 and side, top circumference 22.Side, top curved portions 17 is extended to the postulated point till central angle alpha 2=90 ° by symbol Q7.In the ridge line section of the junction point with side, the top curved portions 17 shown in symbol Q6 and side, top circumference 22, it is also possible to the chamfered section being made up of C face is set.
As long as the position of recess terminal part A1 is making the fuel touching the bottom surface 11 of recess 10 touch the end wall of this recess terminal part A1 and to spark plug 4 side conversion direction and formed on the position of dense fuel bed around spark plug 4, then can freely set.
On the end wall of recess terminal part A1 side, the effect that vertical component effect 15, end side curved portions 16 and chamfered section 14 are set and cause, it is not limited to the flat shape of the recess 10 of above-mentioned embodiment, and at the various end walls needing to utilize recess 10, the fuel sprayed from cylinder injection valve 9 can successfully be guided in the piston 2 in the space near spark plug 4 and play a role.For example, it is also possible to for having the piston 2 of orbicular recess 10 under top view.
As mentioned above, owing to the recess 10 formed at piston head clips the axle center O of piston 2 and is located between the recess top portion A2 of side and the recess terminal part A1 of opposite side, and make more shorter than from axle center O to the distance L2 of recess top portion A2 to the distance L1 of recess terminal part A1 from axle center O, and along the ora terminalis of A2 side, recess top portion, there is curve interval, side, top 12, and along the ora terminalis of recess terminal part A1 side, there is the end side curve interval 13 relatively bigger than the sweep in period side curve interval 12, what therefore the scope of the recess 10 of piston head will not become is excessive, recess 10 can become necessity of the fuel for receiving from cylinder injection valve 9 injection and sufficient scope.This is the radius owing to relatively increasing end side curve interval 13, and relatively reduces the radius in curve interval, side, top 12.
In addition, due to the both sides in end side curve interval 13, possess the side curve less than this end side curve interval 13 relatively sweep interval, therefore near the underface of spark plug 4, it is able to ensure that the scope of recess 10 is bigger, and can effectively catch the fuel from cylinder injection valve 9 injection.
In addition, due to the both sides in curve interval, side, top 12, possesses the installation interval 18 along injection border line j1, and make installation interval 18 be positioned at the outside of injection border line j1, therefore, it is possible to effectively catch from the fuel of cylinder injection valve 9 injection without spilling into recess 10, and by fuel through installing interval 18 and curve interval, side 19, can guide to end side curve interval 13.
Therefore, in necessary Min. and the rigidity of piston 2 can suppressed to decline and while weight increase the scope control of recess 10, the fuel sprayed from cylinder injection valve 9 can be efficiently guided in the recess 10 of piston 2, and around spark plug 4, collect required fuel.
Additionally, due to by the scope control of recess 10 in necessary Min., so there is no the thickness of necessary increase end face.In this respect, it is also possible to suppress the rigidity of piston 2 to decline and weight increases.Further, since the ora terminalis of recess 10 and the outer rim interval of piston 2 can be substantially ensured that, therefore it also is able to the rigidity decline that restraint measure has the part of cooling duct 2c.
Fig. 5 and Fig. 6 is the schematic diagram of design sequence and the action effect illustrating the recess 10 in the present invention.
First, in the top view of the piston head shown in (a) of Fig. 5, the position directly below J of cylinder injection valve 9, and the incline direction spraying centrage j0 and the intersection point P of piston head during fuel injection determined by the specification of electromotor.
As shown in (b) of Fig. 5, recess 10 clips the axes O of piston 2, is located between the recess terminal part A1 of the recess top portion A2 of cylinder injection valve 9 side and the opposition side of cylinder injection valve 9.At this, as shown in (b) of Fig. 5, if making the circular (sweep r-0) being shaped as in the past of recess 10, then this orbicular radius is 1/2nd of the distance between recess top portion A2 and recess terminal part A1.But, if recess 10 is circular, then the region S1 shown in (b) of Fig. 5 has very on a large scale outside recess 10.Additionally, the existence from the injection border line j1 region S2 highlighted laterally is poor efficiency, it is that the area unconditionally expanding recess 10 causes.
Thus, in the present invention, as shown in (c) of Fig. 5, make the sweep (the sweep r-1 in end side curve interval 13) of recess terminal part A1 side more than 1/2nd of the distance between recess top portion A2 and recess terminal part A1.Thus, above-mentioned zone S1 can be reduced into region S1'.
But, according to this sweep r-1, can reduce at the interval T1 of the side of recess 10 and the external end edge of piston 2.Therefore, end side curve interval 13 is provided with the curve interval, side 19 of the sweep r-2 relatively less than end side curve interval 13.Thus, as shown in (d) of Fig. 5, it can be ensured that interval T1 expands as interval T1'.
At this, the junction point B1 in end side curve interval 13 and curve interval, side 19 guarantees that the distance from holding centrage j2 all the time is distance W1, and near the axle center O of piston, it is ensured that the distance from holding centrage j2 all the time is distance W2 (W2 > W0).
Then, as shown in (e) of Fig. 5, make the sweep (the sweep r-3 in curve interval, side, top 12) of A2 side, recess top portion less than 1/2nd of the distance between recess top portion A2 and recess terminal part A1.As a result of which it is, configure, in end side, the end side curve interval 13 that relatively sweep is big, configure the curve interval, side, top 12 that relatively sweep is little in side, top.
Then, by the installation interval 18 of the injection border line j1 of the outer rim along the fuel injection region illustrating cylinder injection valve 9, the end in curve interval, side 19 and the end in curve interval, side, top 12 are connected.
Thus, as shown in (a) of Fig. 6, compared with the situation in the past adopting orbicular recess, on from intersection point P to the side of recess terminal part A1, recess 10 can be expanded with region V1, and on from intersection point P to the side of recess top portion A2, it is possible to reduce recess 10 with region V2.
Additionally, as shown in (b) of Fig. 6, by making fuel start the intersection point P, the Breadth Maximum portion W between bound symbol B2 place of incline direction spraying centrage j0 when spraying and piston headmax, it is possible to effectively fuel is captured in recess 10.
In addition, as shown in (c) of Fig. 6, considering that the intersection point C by injection border line j1 with the ora terminalis of recess 10 interconnects line segment, with when using recess top portion A2 and the recess terminal part A1 line segment being connected as cornerwise tetragon, the interior angle 1 of end side is bigger than the interior angle 2 of top side, and this point also can become the effective ingredient effectively capturing in recess 10 by fuel.
This and consideration are by the Breadth Maximum portion W between bound symbol B2 placemaxLine segment, the same as the situation of cornerwise tetragon with the line segment of top, coupling recess portion portion A2 and recess terminal part A1.
Due to Breadth Maximum portion WmaxAlong holding centrage j2 to be positioned at the ratio axle center O position closer to A2 side, recess top portion all the time, and along holding centrage j2 all the time, from Breadth Maximum portion WmaxDistance between recess terminal part A1 is arranged to more shorter than from the distance axle center O to recess top portion A2, therefore, is considering with the Breadth Maximum portion W between bound symbol B2 placemaxLine segment, with the line segment of top, coupling recess portion portion A2 and recess terminal part A1 as in cornerwise dimetric situation, in the same manner as the example of (c) of Fig. 6, the interior angle 1 of end side can become bigger than side, top interior angle 2.
Other embodiment figure 7 illustrates, and other embodiment figure 8 illustrates further.
In the embodiment of Fig. 7, the sweep r-3 in the curve interval, side, top 12 of A2 side, recess top portion is set to less than the sweep r-2 in curve interval, side 19.At this, although the midpoint C each other of the intersection point C between injection border line j1 and the ora terminalis of recess 100Overlap with intersection point P, but can freely set midpoint C0Whether overlap with intersection point P.
Additionally, in the embodiment of Fig. 8, make the sweep r-3 in the curve interval, side, top 12 of A2 side, recess top portion, somewhat the embodiment than Fig. 7 is bigger, make installation interval 18 towards being configured to for the injection border line j1 direction tilted.Although installing interval 18 and spray border line j1 and non-intersect, but the region that its extended line is outside recess 10 being intersected at a slight angle.By this mode installing interval 18, also fuel can be guided to curve interval, side 19.It is preferable, however, that from recess top portion A2 lateral recess terminal part A1 side, install interval 18 and slowly narrow with injection border line j1.
In these embodiments, the fuel injection manner of cylinder injection valve 9 is around incline direction spraying centrage j0 and uniformly sprays, or, spray centrage j0 at incline direction and hold under the centrage j2 premise overlapped under top view all the time, the shape of the piston 2 of recess 10 will be comprised, clip and hold centrage j2 as object all the time, but the mode of injection fuel can also according to the position of cylinder injection valve 9, consider, by the shape of the piston 2 containing recess 10, to clip and hold centrage j2 as the embodiment of non-object all the time.
Symbol description:
1 cylinder；2 pistons；2a piston skirt；2b piston boss portion；2c cooling duct；3 combustor；4 spark plugs；5 air entries；6 air vents；7 air-breathing doors；8 exhaust valves；9 cylinder injection valves；10 recesses；11 bottom surfaces；12 side, top curves are interval；13 end side curves are interval；14 chamfered section；15 vertical component effects；16 end side curved portions；17 side, top curved portions；Interval (is installed) by 18 straight portions；19 side curves are interval；21,23 groove；22 side, top circumferences；24 end side circumferences；25 side end faces；26 side circumferences；27 piston-top surfaces.

Claims (8)

1. a direct injection engine piston, is formed with recess at piston-top surface, wherein,
Described recess clips the axle center of piston, is located between the recess top portion of side and the recess terminal part of opposite side,
In described recess, in the Breadth Maximum portion maximum with width on that connect described recess top portion and described recess terminal part, orthogonal through the centrage of end all the time in described axle center direction along described axle center compared with the described centrage of end all the time on the position of side, portion, described recess top
Along the described centrage of end all the time from described Breadth Maximum portion, distance to described recess terminal part is set as being shorter than the distance from described axle center to described recess top portion.
2. direct injection engine piston according to claim 1, wherein,
It is interval that the described recess of described piston possesses side, top curve along the ora terminalis of described recess beginning end side, and described recess possesses sweep along the ora terminalis of described recess terminal part side, and to be relatively larger than the interval end side curve of side, described top curve interval.
3. direct injection engine piston according to claim 2, wherein,
Described end side curve interval has the part of the radius longer with 1/2nd of the spacing of described recess terminal part than described recess top portion, and curve interval, side, described top has the part of the radius shorter with 1/2nd of the spacing of described recess terminal part than described recess top portion.
4. direct injection engine piston according to claim 2, wherein,
Sweep is relatively smaller than the interval curve interval, side of described end side curve and is connected respectively to the two ends that described end side curve is interval.
5. direct injection engine piston according to claim 4, wherein,
Curve interval, described side has the part of the radius shorter than 1/2nd of the distance between described recess top portion and described recess terminal part.
6. direct injection engine piston according to claim 3, wherein,
Sweep is relatively smaller than the interval curve interval, side of described end side curve and is connected respectively to the two ends that described end side curve is interval.
7. direct injection engine piston according to claim 6, wherein,
Curve interval, described side has the part of the radius shorter than 1/2nd of the distance between described recess top portion and described recess terminal part.
8. direct injection engine piston according to any one of claim 1 to 7, wherein,
Along with from described recess initial portion from and be connected from the interval two ends interval with side, described top curve respectively of installing that the described centrage of end all the time is gradually distance from.
CN201510982834.1A 2014-12-24 2015-12-24 Piston for inner-cylinder injection engine Pending CN105736123A (en)

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