CN205277615U

CN205277615U - Piston for injection -type engine in jar

Info

Publication number: CN205277615U
Application number: CN201520935849.8U
Authority: CN
Inventors: 谷口好正; 上野慎司
Original assignee: Mitsubishi Motors Corp
Current assignee: Mitsubishi Motors Corp
Priority date: 2014-12-24
Filing date: 2015-11-23
Publication date: 2016-06-01
Anticipated expiration: 2025-11-23
Also published as: JP2016121564A; JP6476841B2

Abstract

The utility model relates to a piston for injection -type engine in jar, it can concentrate on the fuel that comes from the interior injection valve of jar around the spark plug high -efficiently. In the piston -top surface is formed with the piston for injection -type engine in jar of concave part (10), the axle center O of concave part (10) centre gripping piston (2) and setting up terminates between the end (A1) in the concave part initiating terminal (A2) of one side and the concave part of opposite side, the concave part of concave part (10) terminates the end wall of end (A1) one side, by vertical component effect (15) parallel with axle center O on the parallel arbitrary cross section of the axle center O with piston (2), curved surface (16) of connecting bottom surface (11) of vertical component effect (15) and concave part (10), and the chamfer portion (14) of the crest line portion between vertical component effect (15) and concave part (10) piston -top surface on every side that sets up constitutes. The top surface that terminates end (A1) one side piston (2) adjacent with concave part (10) at the concave part is set for to the top surface height than at concave part initiating terminal (A2) one side piston adjacent with concave part (10), and the tie point of vertical component effect (15) and curved surface (16) is located than the top surface height of the piston (2) adjacent with concave part (10) on one side of concave part initiating terminal (A2) high top still.

Description

A kind of direct injection engine piston

Technical field

The utility model relates to a kind of piston for the direct injection engine to cylinder inner direct fuel.

Background technology

Have in the cylinder injection type petrol engine of the cylinder injection valve of cylinder inner direct fuel, such as, there is a kind of petrol engine, it controls as follows, in high load area, in cylinder, import the gas mixture of homogeneous chemically correct fuel and carry out homogeneous burning, and in low load region, the denseer inflammable mixture layer of fuel will be divided in cylinder and fuel is thinner or substantially only has the lean mixture gas-bearing formation of air and carries out the thin burning of layering (stratified combustion).

When stratified combustion, air-flow in the cylinder utilizing the decline with piston and produce, preventing the intimate mixing of gasoline and air, control air-flow makes inflammable mixture layer, and the phase concentrates on around sparking plug after the compression stroke, and lean mixture gas-bearing formation concentrates on from the side close to piston end face.

But, in patent documentation 1, disclose on a kind of position being partial to intake valve side at piston end face, form the technology that orthographic plan is the recess (bowl-type) of circular. When piston is when near top dead center, point to the inside of this recess towards the jet axis of the cylinder injection valve in cylinder.

In this piston, when homogeneous burns, inlet mouth one is imported in cylinder from what a cylinder possessed by fresh air, and what produce a kind of eddy current rotated for stronger longitudinal direction rolls stream. Fuel in the intake stroke injected enter in cylinder, this fuel in the way of rolling stream at cylinder internal diffusion, it is achieved that the homogeneous of gas mixture in cylinder.

In addition, when the thin burning of layering, under the control of the air control valve being arranged in opening, fresh air is only imported in cylinder from an inlet mouth one pair of inlet mouth, the composition rolling stream is weakened relatively, and simultaneously eddy current and eddy flow along horizontal direction is enhanced.

And, in the second half section of pressure stroke, from cylinder injection valve to the fuel of the recess at piston top injection, along with the eddy flow in recess moves to the sparking plug side of top of combustion chamber, around sparking plug, form the inflammable mixture layer being easy to light.

The flat 11-210551 publication of [patent documentation 1] Japanese Patent Laid-Open

Practical novel technical problem to be solved

Such as above-mentioned example, in cylinder injection type petrol engine, it is necessary to the fuel trim ejected from cylinder injection valve be directed into around sparking plug, and around its sparking plug, form the gas mixture being easy to light.

But, in the recess of the dark plate shape (bowl-shape) of such as above-mentioned patent documentation 1, the fuel ejected from cylinder injection valve is trapped in the bottom of recess sometimes. Therefore, exist how by the problem of fuel trim ground around the sparking plug that leads.

Therefore, problem to be solved in the utility model is concentrated on around sparking plug by the fuel-efficient ejected from cylinder injection valve.

Practical novel content

In order to solve the problem, the utility model have employed a kind of direct injection engine piston being formed with recess at piston end face, wherein, the recess of the axle center of described recess clamp piston and the recess initiating terminal and another side that are arranged at side terminates between end, and it is by forming with the curved surface being connected described vertical portion and described recess bottom surface with the vertical portion of described axis parallel with on the arbitrary section of the axis parallel of piston that the described recess of described recess terminates the end wall of end side.

In addition, it is possible to adopt the structure being provided with chamfered section in the ridge line section between the piston end face around described vertical portion and described recess.

Here, terminate end with the described recess initiating terminal and described recess that connect described recess and pass through the maximum width portion that the width on the orthogonal direction of the medullary ray between the initial of described axle center with termination end is the widest, it is positioned at described recess initiating terminal side compared with described axle center along described medullary ray that is initial and that terminate between end, terminate the distance of end along the described initial and medullary ray that terminates between end from described maximum width portion to described recess, it is set as also shorter than the distance from described axle center to described recess initiating terminal.

In addition, described recess terminates the radius of curve of the described curved surface of end side end wall, it is possible to be set as bigger than the radius of curve of the curved surface being arranged at described recess initiating terminal side end wall and hold up from described recess bottom surface.

In addition, the end face of the end side piston adjacent with described recess is terminated at described recess, it is possible to be set as higher than the end face of the piston adjacent with described recess in described recess initiating terminal side.

The tie point of described vertical portion and described curved surface, it is possible to be positioned at also high than the apical side height of the piston adjacent with described recess in described recess initiating terminal side above.

Practical novel effect

The utility model have employed a kind of direct injection engine piston, the recess of the axle center of the recess clamp piston of its piston end face and the recess initiating terminal and another side that are arranged at side terminates between end, the end wall that the described recess of recess terminates end side is by forming with the curved surface being connected vertical portion and recess bottom surface with vertical portion with axis parallel on the arbitrary section of the axis parallel of piston, therefore can be concentrated on around sparking plug by the fuel-efficient that eject from cylinder injection valve.

Accompanying drawing explanation

Fig. 1 (a), Fig. 1 (b), Fig. 1 (c) illustrate the piston of an enforcement mode of the present utility model, wherein, Fig. 1 (a) is orthographic plan, the C-C sectional view of Fig. 1 (b) to be section B-B figure, Fig. 1 (c) be Fig. 1 (a).

Fig. 2 is the oblique drawing of the piston representing identical enforcement mode.

Fig. 3 is the sectional view of the cylinder interior of the engine representing the piston holding identical enforcement mode.

Fig. 4 is the orthographic plan of the piston representing identical enforcement mode and the front schematic view of the position relation with cylinder injection valve.

Fig. 5 (a)��(e) represents the orthographic plan of the order of the recess shapes determining piston end face.

Fig. 6 (a)��(c) is the figure of the detailed configuration of the recess representing piston end face.

Fig. 7 represents other front schematic view implementing the orthographic plan of piston of mode and the position relation with cylinder injection valve.

Fig. 8 represents other front schematic view implementing the orthographic plan of piston of mode and the position relation with cylinder injection valve.

Fig. 9 is the important part enlarged cross section figure of piston.

Nomenclature

1 cylinder

2 pistons

2a skirt of piston

2b piston boss portion

2c cooling channel

3 combustion chambers

4 sparking plug

5 inlet mouths

6 venting ports

7 intake valves

8 vent valves

9 cylinder injection valves

10 recesses

11 bottom surfaces

The curve of 12 initiating terminal sides is interval

The curve of 13 termination end sides is interval

14 chamfered section

15 vertical portions

The fillet portion of 16 termination end sides

The fillet portion of 17 initiating terminal sides

18 line parts (are installed interval)

19 side curves are interval

21,23 grooves

The circumference at 22 side, tops

The circumference of 24 termination end sides

25 side end faces

26 circumference, sides

27 piston end faces

Embodiment

Below, based on accompanying drawing, an enforcement mode of the present utility model is described. Present embodiment is cylinder injection type automobile four-stroke gasoline engine and the piston for this engine. The figure of Fig. 1 and Fig. 2 to be the figure of the detailed configuration representing piston, Fig. 3 the be major parts of combustion chamber 3 and formation of engine in 1 cylinder representing that this engine possesses. In figure 3, only represent the component etc. directly related with the utility model, eliminate the diagram of other components etc. In addition, in figure 3, although merely illustrating a cylinder 1, but engine both can be single cylinder, it is also possible to be the multiple cylinder with multiple cylinder 1.

As shown in Figure 3, in the cylinder 1 of engine, piston 2 is accommodated. Combustion chamber 3 is formed by the end face etc. of the inner-wall surface of cylinder 1 and piston 2. In addition, in cylinder 1, have the inlet mouth 5 of air oriented combustion chamber 3, by come from combustion chamber 3 tail gas discharge venting port 6 and from cylinder cap side along the axis of cylinder, that is, the sparking plug 4 etc. configured downwards along the axis of cylinder. In addition, the direction of sparking plug is not limited in this.

In cylinder 1, there is the cylinder injection valve 9 to combustion chamber 3 inner direct fuel. Cylinder injection valve 9, is configured in combustion chamber 3 near the circumference of top and is positioned near the opening of inlet mouth 5. As shown in Figure 3, the fuel injection direction of cylinder injection valve 9, along with its spray centerline j0 is close to central authorities from the circumference of combustion chamber 3, gradually close to the vergence direction of piston head (end face of piston 2). Below, the spray centerline j0 of this fuel is called the spray centerline j0 of vergence direction. Using the spray centerline j0 of this vergence direction as center, fuel is from the jet orifice ejection of cylinder injection valve 9 and evenly spreads with the shape of sector.

In the present embodiment, a cylinder has two inlet mouths 5. In each inlet mouth 5, it is respectively arranged with the intake valve 7 in the opening portion leading to combustion chamber 3 for opening and closing. In addition, a cylinder has two venting ports 6. In two venting ports 6, it is respectively arranged with the vent valve 8 in the opening portion leading to combustion chamber 3 for opening and closing. These intake valves 7 and vent valve 8, by being arranged at the rotation of the camshaft of cylinder cap side, come opening and closing inlet mouth 5, venting port 6 with specific time.

Equipment required when intake valve 7 and vent valve 8, sparking plug 4, cylinder injection valve 9 and other engine operation, controls by being arranged at the controlling organization of the electronically controlled unit (ElectronicControlUnit) that the vehicle being equipped with this engine possesses.

In addition, in the present embodiment, it is possible to optionally control the opening/closing time of intake valve 5, such as, make an intake valve 5 identical with the opening/closing time of another intake valve 5 or different. Moreover, it is possible to optionally control the opening/closing time of vent valve 6, such as, make a vent valve 6 identical with the opening/closing time of another vent valve 6 or different.

By the control to these valves and fuel injection time point, such as, in high load area, the homogeneous charge of chemically correct fuel can be imported and carry out homogeneous burning in combustion chamber 3, in low load region, can will be divided into the denseer inflammable mixture layer of fuel in combustion chamber 3 and fuel is thinner or substantially only has the lean mixture gas-bearing formation of air, thus carry out the thin burning of layering (stratified combustion).

Cylinder injection valve 9 is configured between two intake valves 7. Cylinder injection valve 9, be configured at least piston 2 be in top dead center pay near state time, the spray centerline j0 of vergence direction is pointed to than the axle center O of piston 2 slightly near the part of cylinder injection valve 9. Symbol P shown in figure 3, represents when being blown into from the fuel of cylinder injection valve 9 injection in 1 stroke, the spray centerline j0 of vergence direction and the intersection point of piston head. Here, the axle center O of piston 2 is consistent with the cylinder axle center of the cylinder 1 at sparking plug 4 place.

As shown in Figure 1 and Figure 2, piston 2, is formed as cylinder shape or cylinder shape in piston head side, and has piston boss portion 2b in bottom, side between pair of pistons skirt section 2a and skirt of piston 2a. In addition, in circumference, at whole space and the cooling channel 2c circumferentially with ring-type circumferentially.

On the periphery of piston 2, possesses the groove 2e accommodating piston ring 2d. In the present embodiment, it is formed with 3 groove 2e corresponding to 3 piston ring 2d. Compared with the groove 2e near piston head side closer to the part of end face side be crest top land.

On piston head, it is formed with the recess 10 that the fuel ejected from cylinder injection valve 9 can be made to point to. Recess 10 is arranged on piston end face.

Recess 10, the axle center O of clamp piston 2 and the recess that is arranged at the recess initiating terminal A2 of side and cylinder injection valve 9 side and the opposite side of another side and cylinder injection valve 9 terminates between end A1.

As shown in Figure 4, the medullary ray j2 between also orthogonal with this axle center O by the axle center O of the piston 2 initial and termination end of end A1 is terminated along coupling recess portion initiating terminal A2 and recess, terminate the distance L1 of end A1 from axle center O to recess, it is set as shorter than from axle center O to the distance L2 of recess initiating terminal A2. In addition, the initial and medullary ray j2 that terminates between end, is positioned on the direction orthogonal with the axis direction of piston boss portion 2b on orthographic plan.

The position of recess initiating terminal A2, using the position J of the only underface of distance L11 downward from the jet orifice position J ' of cylinder injection valve 9 along axle center O as benchmark, is positioned at the side of the axle center O of only distance L3 compared with the position J immediately below this. Recess initiating terminal A2 is set to the jeting area from the fuel of cylinder injection valve 9 is contained in the bottom surface 11 of recess 10. In addition, the position J of underface, is positioned at the inner side of the only distance L4 from the edge of piston 2.

Recess terminates the position of end A1, the fuel being set in the bottom surface 11 touching recess 10 is imported into recess termination end A1 side, the end wall terminating end A1 with this recess contacts and turn to sparking plug 4 side, and can form the position of denseer fuel bed around sparking plug 4. In the present embodiment, recess terminates the intersection point A3 that the position of end A1 is the end edge making the axle center O of piston 2, the initial and medullary ray j2 that terminates between end and piston 2, the point shown greatly in the ratio of 1:2 point, but this interior point of ratio suitably can be determined according to the specification of the spraying pressure of the diameter of piston 2 and fuel, other and engine.

In addition, the recess 10 of piston 2, end edge along recess initiating terminal A2 side has the curve interval 12 of initiating terminal side, and the end edge along recess termination end A1 side has the curve interval 13 of the relatively large termination end side of radius of curve compared with the curve interval 12 of initiating terminal side.

Terminate the curve interval 13 of end side, there is the part of 1/2nd radius r-1 also grown terminating the distance L1+L2 between end A1 than recess initiating terminal A2 and recess. In addition, the curve interval 12 of initiating terminal side, has the part of 1/2nd also short radius r-3 terminating the distance L1+L2 between end A1 than recess initiating terminal A2 and recess.

In the present embodiment, the curve interval 12 of initiating terminal side, the curve interval 13 of termination end side, it is the curve interval (R3, R1) being made up of single radius of curve r-3, r-1 respectively, but the radius in this curve interval can also be made in intermediate change. Just, in the middle of curve, there is not breakpoint etc., and, curvature answers consecutive variations, and it is good for there is not the discontinuous part of curvature. Now, the curve interval 12 of initiating terminal side, in whole interval, 1/the 2 of radius ratio distance L1+L2 are short is good. Equally, terminating the curve interval 13 of end side, in whole interval, 1/the 2 of radius ratio distance L1+L2 are long for good.

At the two ends in the curve interval 13 terminating end side, it is connected to the curve interval, side 19 of radius of curve r-2 relatively little compared with the radius of curve r-1 in the curve interval 13 terminating end side. Curve interval, side 19, has the part of the radius r-2 shorter than 1/the 2 of distance L1+L2.

In the present embodiment, to be set to the radius of curve r-3 in the curve interval 12 with initiating terminal side identical for the radius of curve r-2 in side curve interval 19. If being set as identical by the radius of curve r-3 of the radius of curve r-2 in curve interval, side 19 and the curve interval 12 of initiating terminal side, then it is easy to processing when manufacturing. However, it may also be possible to this radius of curve r-2 and radius of curve r-3 is set as difference.

In addition, in the present embodiment, curve interval, side 19, is the curve interval (R2) being made up of single radius of curve r-2, but the radius in this curve interval can also be made in intermediate change. Just, in the middle of curve, there is not breakpoint etc., and, curvature answers consecutive variations, and it is good for there is not the discontinuous part of curvature. Now, curve interval, side 19, in whole interval, 1/the 2 of radius ratio distance L1+L2 are short is good.

At the two ends in the curve interval 12 of initiating terminal side, be connected to along with away from recess initiating terminal A2 gradually away from the installation interval 18 of medullary ray j2 that is initial and that terminate between end. In the present embodiment, install interval 18 to be made up of linear line part (U1). In addition, install interval 18 and it is not limited to line part, it is also possible to be the arc (circular arc) being made up of enough big radius.

Install interval 18, connect and compose by the end of the end in the curve interval 12 of initiating terminal side and curve interval, side 19. Install interval 18, relative to and the orthogonal jet width direction of medullary ray j2 that is initial and that terminate between end, parallel with the injection edge line j1 at the edge of the jeting area representing the fuel sprayed from cylinder injection valve 9. In plan view, from the jeting area of fuel that cylinder injection valve 9 sprays, it it is the region of the sector in the injection edge line j1 represented with angle [alpha] in Fig. 1 (a).

However, it may also be possible to the installation interval 18 formed by this line part is configured to not parallel with injection edge line j1, form very little angle each other. Just, installation interval 18 is positioned at the outside compared with injection edge line j1 is good. In addition, as long as installing interval 18 along injection edge line j1, part or all of interval 18 is installed, it is also possible to be made up of the level and smooth curve without breakpoint. Now, in order to enable fuel steadily import interval 19 sides of side curve, to be contained in the curve installing interval 18 be its radius of curve compared with the curve of side, top interval 12 or terminate the curve interval 13 of end side, side curve interval 19 big circular shapes be good.

Such as present embodiment, when the curve that the curve interval 13 terminating end side is made up of single radius of curve r-1, terminate the center O1 of the circular arc in the curve interval 13 of end side, it is configured at and (pressure stroke later stage when being blown into from the fuel that cylinder injection valve 9 sprays in 1 stroke, such as, 40CA before compression top center) the spray centerline j0 of vergence direction of fuel compare with the intersection point P of the bottom surface 11 of recess 10, the only recess initiating terminal A2 side of distance L8. Symbol L5 in figure is the distance along the medullary ray j2 direction between the initial and termination end between axle center O and center O1.

In addition, terminate the center O1 of circular arc in the curve interval 13 of end side, the mid point C being configured at and spraying between the intersection point C of the end edge of edge line j1 and recess 10₀Compare, only the recess initiating terminal A2 side of distance L8-L9. Here, distance L9 is along intersection point P and mid point C₀Between the initial and distance in medullary ray j2 direction that terminates between end.

When the curve interval 12 of initiating terminal side is the curve being made up of single radius of curve r-3, the center O3 of the circular arc in the curve interval 12 of initiating terminal side, the intersection point P being configured at the bottom surface 11 of the spray centerline j0 with vergence direction with recess 10 compares, only the recess initiating terminal A2 side of distance L8+L6. The center O3 of the circular arc in the curve interval 12 of initiating terminal side, is configured at and sprays between the intersection point C of edge line j1 and recess 10 end edge the mid point C of (with reference to from initial figure and the distance W3 of medullary ray j2 that terminates between end)₀Compare, only the recess initiating terminal A2 side of distance L8-L9+L6. Here, distance L6 is the distance along the medullary ray j2 direction between the initial and termination end between center O1 and center O3.

Intersection point C is side curve interval 19 and the intersection point of injection edge line j1. In addition, by intersection point P and clamp and straight line that medullary ray j2 that is initial and that terminate between end is orthogonal, there is maximum width portion Wmax in the opposite side in intersection point C side. Maximum width portion Wmax is positioned at curve interval, side 19, for relative to and the orthogonal jet width direction of medullary ray j2 that is initial and that terminate between end, the position that the width of recess 10 is the widest.

Maximum width portion Wmax, it is positioned at compared with the O of axle center near recess initiating terminal A2 side along medullary ray j2 that is initial and that terminate between end, along medullary ray j2 that is initial and that terminate between end, terminate the distance of end A1 from maximum width portion Wmax to recess, it is set as also shorter than from axle center O to the distance of recess initiating terminal A2.

Symbol B1 in figure is the tie point in the curve interval 13 and curve interval, side 19 terminating end side, symbol B2 is the position becoming maximum width portion Wmax, symbol B3 is side curve interval 19 and the tie point installing interval 18, and symbol B4 is the tie point in the curve interval 12 of installation interval 18 and initiating terminal side. Clamping between the line in interval, both sides of each tie point, the tangent line direction on mutual tie point is consistent, smoothly connects without breakpoint.

In addition, intersection point P, mid point C₀With the position of maximum width portion Wmax, it is also possible to consistent mutually along the direction of medullary ray j2 that is initial and that terminate between end. For example, it is contemplated that with under type, in the middle of 3 points, intersection point P and mid point C₀The mode consistent on the direction along medullary ray j2 that is initial and that terminate between end in position, the mode that the position of maximum width portion Wmax and intersection point P is consistent on the direction along medullary ray j2 that is initial and that terminate between end, maximum width portion Wmax and mid point C₀The mode consistent on the direction along medullary ray j2 that is initial and that terminate between end in position, or, the mode that the position of 3 points is all consistent on the direction along medullary ray j2 that is initial and that terminate between end. Just, from the viewpoint of capture in the recess 10 of the area with restriction by the fuel-efficient ejected, the position of intersection point P and the position of maximum width portion Wmax are consistent on the direction of the medullary ray j2 between initial and termination end is good.

In addition, as shown in Figure 1 and Figure 2, piston 2, has the groove 21,23 of the spill of the interference for preventing air inlet and exhaust valve 7,8 around recess 10. In addition, piston 2, the periphery along intake valve 7 side has the circumference 22 of initiating terminal side, and the periphery along vent valve 8 side has the circumference 24 terminating end side.

In addition, at piston 2 towards, on the periphery in described jet width direction, there is the side end face 25 of inclination and the circumference, side 26 in the direction, face with axis perpendicular. Circumference, side 26, relative with the upper wall surface of cylinder 1, it is formed with the Ji Qi district discharging fuel from the circumference in combustion chamber 3 to central authorities.

Between recess 10 and groove 23, between recess 10 and side end face 25, there is the piston end face 27 in the face direction vertical with axle center O. In addition, according to specification, it is also possible to do not arrange piston end face 27.

As shown in the sectional view of Fig. 9, the end edge of recess 10, terminates end A1 side at recess, has the fillet portion 16 of chamfered section 14, vertical portion 15, termination end side successively from piston end face 27 towards bottom surface 11. This structure is employed in whole intervals in the curve interval 13 and curve interval, side 19 terminating end side. Terminate the fillet portion 16 of end side, it is arranged in the scope of central angle alpha 1 (�� 1=90 ��), height B, to connect bottom surface 11 and vertical portion 15. As shown in the sectional view of Fig. 9, vertical portion 15, in the arbitrary section parallel with axle center O, is formed as parallel with axle center O.

In fig .9, symbol Q1 is the bottom surface 11 of recess 10 and the tie point in the fillet portion 16 of termination end side. At this tie point Q1, it is the smooth connection without breakpoint between the tabular surface of bottom surface 11 and the curved surface terminating the fillet portion 16 of end side. Symbol Q2 is the tie point in fillet the portion 16 and vertical portion 15 terminating end side. At this tie point Q2, also it is the smooth connection without breakpoint between the cylinder shape face in vertical portion 15 and the curved surface terminating the fillet portion 16 of end side. Symbol Q3 and symbol Q4 is starting point and the terminating point of the chamfered section 14 being made up of horizontal size C1, longitudinal size C2. This transverse direction size C1, longitudinal size C2, as long as the height A in vertical portion 15 can fully be guaranteed, so that it may freely to set.

From the fuel that cylinder injection valve 9 ejects, after the bottom surface 11 touching recess 10, arrive the curve interval 13 terminating end side. Or, arrive and interval 18 and curve interval, side 19 be installed, and move along this installation interval 18 and side curve interval 19, arrive the curve interval 13 terminating end side. Here, fuel rises along the fillet portion 16 of the termination end side smoothly being connected with smooth bottom surface 11, is directed to the direction parallel with axle center O along vertical portion 15, and steadily is imported sparking plug 4 side.

Here, as shown in Figure 9, the end face of the circumference 22 of initiating terminal side will be connected and terminate the neutral line f1 of the piston 2 of the end face of the circumference 24 of end side for boundary, the bottom surface 11 of recess 10 is positioned at lower section (crank side), and piston end face 27 is positioned at top (cylinder cap side). Terminating the fillet portion 16 of end side, the position above compared with neutral line f1 is connected with vertical portion 15. Neutral line f1 is the reference plane calculated according to compression height (center of piston boss portion 2b, that is, from the center of wrist pin to the distance of the shoulder of piston 2). Owing to being connected in the position above compared with neutral line f1 with vertical portion 15 in the fillet portion 16 terminating end side, therefore the radius of curve R1 that can make the fillet portion 16 of termination end side becomes bigger, it is also possible to steadily guide fuel to sparking plug 4 side.

From neutral line f1 to the height h2 of piston end face 27, it is set as lower to the height h3 of the bottom surface 11 of recess 10 than from neutral line f1. From the height h1 of bottom surface 11 to the piston end face 27 of recess 10 be height h2 and height h3 sum.

Owing to the ridge line section between vertical portion 15 and piston end face 27 not being arranged to arc, the chamfered section 14 being made up of C face constitutes this ridge line section, therefore vertical portion 15 can be formed as wider region along the axle center of piston 2. If this is because ridge line section is set to arc, then can not fully guarantee the length (towards the length of axis direction) in vertical portion 15. In addition, by ridge line section is set to arc, it is possible to make air-flow flow along the circular arc of this curved portions, but by being arranged to the chamfered section 14 being made up of C face, air-flow layering is also easily fed near sparking plug.

In addition, by being formed ridge line section with chamfered section 14, it is possible to make the degree of depth (being equivalent to described height h1) of recess 10 become shallow, it is possible to no longer need to increase crest top land the various countermeasures being used for guaranteeing rigidity such as thick. In addition, if recess 10 is more shallow, then can fully guarantee and the isolation part of cooling channel 2c.

In addition, in recess initiating terminal A2 side and interval 18 sides of installation, the end edge of recess 10, being made up of the fillet portion 17 connecting bottom surface 11 and the circumference 22 of initiating terminal side and the initiating terminal side of groove 21, the fillet portion 17 of initiating terminal side is arranged on the scope of central angle alpha 2 (�� 2 < 90 ��).

In the present embodiment; although the radius of curve R2 of the radius of curve R1 in fillet portion 16 and the fillet portion 17 of initiating terminal side that terminate end side is set as identical; but from the viewpoint of guarantee the rigidity of piston component, the radius of curve R2 in the fillet portion 17 of initiating terminal side is set as less of than the radius of curve R1 in the fillet portion 16 terminating end side good. In addition, the number of radius of curve R1 and radius of curve R2 and magnitude relationship, be not limited to described enforcement mode.

In fig .9, symbol Q5 is the bottom surface 11 of recess 10 and the tie point in the fillet portion 17 of initiating terminal side. At this tie point Q5, the curved surface in the tabular surface of bottom surface 11 and the fillet portion 17 of initiating terminal side is the smooth connection without breakpoint. Symbol Q6 is the fillet portion 17 of initiating terminal side and the tie point of the circumference 22 of initiating terminal side. Symbol Q7 is the virtual point extended in the fillet portion 17 of initiating terminal side to forming central angle alpha 2=90 ��. In the ridge line section of the fillet portion 17 of the initiating terminal side represented by symbol Q6 and the tie point of the circumference 22 of initiating terminal side, it is also possible to the chamfered section being made up of C face is set.

Recess terminates the position of end A1, if the end wall of fuel contact with the bottom surface 11 of recess 10 and this recess termination end A1 contacts and to sparking plug 4 side conversion direction, and can form the position of denseer fuel bed around sparking plug 4, then can freely set.

Terminate on the end wall of end A1 side at recess, vertical portion 15 is set and terminates the fillet portion 16 of end side, the effect of chamfered section 14, it is not limited to the planeform of the recess 10 of described enforcement mode, by the end wall of recess 10, it is possible to need by the fuel trim sprayed from cylinder injection valve 9 lead near sparking plug 4 space various pistons 2 on play a role. Such as, have orthographic plan be circular recess 10 piston 2 on can also adopt.

As mentioned above, owing to the recess 10 being formed at piston head being hold the axle center O of piston 2 and is arranged between the recess initiating terminal A2 of side and the recess termination end A1 of another side, the distance L1 terminating end A1 from axle center O to recess is set as shorter than from axle center O to the distance L2 of recess initiating terminal A2, and, end edge along recess initiating terminal A2 side has the curve interval 12 of initiating terminal side, end edge along recess termination end A1 side has the curve interval 13 of the relatively large termination end side of radius of curve compared with the curve interval 12 of initiating terminal side, therefore recess 10 scope that need not make piston head is excessive, recess 10 can be set in for accepting in the enough scopes needed for the fuel sprayed from cylinder injection valve 9. this is because the radius in the curve interval 13 terminating end side is set to relatively large, and the radius in the curve interval 12 of initiating terminal side is set to relatively little.

In addition, due to the curve interval, side 19 that radius of curve compared with having the curve interval 13 with this termination end side in the both sides in curve interval 13 terminating end side is relatively little, therefore pay closely in the underface of sparking plug 4, can guarantee that the scope of recess 10 is wider, additionally it is possible to catch the fuel from cylinder injection valve 9 efficiently.

In addition, in the both sides in the curve interval 12 of initiating terminal side, there is the installation interval 18 along injection edge line j1, using this installation interval 18 as the outside spraying edge line j1, therefore outside can catching efficiently and not making it spill into recess 10 from the fuel of cylinder injection valve 9, and by fuel through installing interval 18, side curve interval 19 and be fixed to the curve interval 13 terminating end side.

Therefore, it is possible not only to the range limit of recess 10 in required minimum extent, suppress the reduction of piston 2 rigidity and the increase of weight, efficiently the fuel sprayed from cylinder injection valve 9 can also be sent in the recess 10 of piston 2 simultaneously, and around sparking plug 4, concentrate required fuel.

In addition, due to by the range limit of recess 10 in required minimum extent, so there is no need increase crest top land thickness. In this, it is also possible to suppress the rigidity of piston 2 to reduce the increase with weight. In addition, owing to can fully guarantee the isolation part between the end edge of recess 10 and the edge of piston 2, therefore can also restraint measure have cooling channel 2c part rigidity reduce.

Fig. 5 and Fig. 6 is the design procedure of recess 10 and the schematic diagram of action effect representing in the utility model.

First, in the orthographic plan of the piston head shown in Fig. 5 (a), the intersection point P of position, the underface J of cylinder injection the valve 9 and spray centerline j0 and piston head that start vergence direction when being blown at fuel depends on the specification of engine.

As shown in Fig. 5 (b), recess 10, holds the axle center O of piston 2 and is arranged between the recess termination end A1 of the recess initiating terminal A2 of cylinder injection valve 9 side and the opposite side of cylinder injection valve 9. Here, as shown in Fig. 5 (b), if the shape of recess 10 is set to conventional circular (radius of curve r-0), then the radius of this positive round is that recess initiating terminal A2 and recess terminate 1/2nd of the distance between end A1. But, if recess 10 is circular, then the region S1 shown in Fig. 5 (b) is present in outside recess 10 in wider scope. In addition, owing to from the existence spraying the region S2 that edge line j1 stretches out laterally, making the area of recess 10 increase in vain, inefficiency.

Therefore, as shown in Fig. 5 (c), in the utility model, the radius of curve (terminating the radius of curve r-1 in the curve interval 13 of end side) making recess terminate end A1 side is greater than recess initiating terminal A2 and recess terminates 1/2nd of the distance between end A1. Accordingly, it is possible to described region S1 is contracted to region S1 '.

But, according to this radius of curve r-1, in the side of recess 10, and the isolation part T1 between the edge of piston 2 diminishes. Therefore, in the both sides in the curve interval 13 terminating end side, the curve interval, side 19 that compared with being provided with the curve interval 13 with this termination end side, radius of curve r-2 is relatively little. Accordingly, as shown in Fig. 5 (d), it is possible to guarantee that wider isolation part T1 is such as isolation part T1 '.

Here, terminate the curve interval 13 of end side and the tie point B1 in curve interval, side 19, distance W1 can be guaranteed from medullary ray j2 that is initial and that terminate between end, pay closely at piston axes O, it is possible to guarantee distance W2 (W2 > W0) from medullary ray j2 that is initial and that terminate between end.

Then, as shown in Fig. 5 (e), the radius of curve (the radius of curve r-3 in the curve interval 12 of initiating terminal side) of recess initiating terminal A2 side is less than, and recess initiating terminal A2 and recess terminate the distance between end A1 1/2nd. As a result, it is configured with the curve interval 13 of the relatively large termination end side of radius of curve in termination end side, it is configured with the curve interval 12 of the relatively little initiating terminal side of radius of curve in initiating terminal side.

And, by the end of the end in curve interval, side 19 and the curve interval 12 of initiating terminal side, by connecting along the installation interval 18 of the injection edge line j1 at the jeting area edge representing the fuel from cylinder injection valve 9 injection.

Accordingly, as shown in Fig. 6 (a), compared with the situation of the recess in the past adopting circular, terminating end A1 side at recess compared with intersection point P can make recess 10 expand the part being equivalent to region V1, recess 10 can be made to reduce the part being equivalent to region V2 in recess initiating terminal A2 side compared with intersection point P.

In addition, as shown in Fig. 6 (b), by the maximum width portion Wmax making the intersection point P of spray centerline j0 and piston head that fuel starts vergence direction when being blown into be positioned between junction symbol B2 position, it is possible to efficiently fuel is captured in recess 10.

In addition, as shown in Fig. 6 (c), when line segment between the intersection point C considering the end edge to connect injection edge line j1 and recess 10 and the line segment of coupling recess portion initiating terminal A2 and recess termination end A1 are as cornerwise tetragon, the interior angle 1 terminating end side compared with the interior angle 2 of initiating terminal side becomes big this point, be also one by fuel-efficient capture in recess 10 in effective factor.

This is when considering taking the line segment of the line segment of the maximum width portion Wmax between junction symbol B2 position and coupling recess portion initiating terminal A2 and recess termination end A1 as also identical when cornerwise tetragon.

Maximum width portion Wmax, it is positioned at recess initiating terminal A2 side compared with the O of axle center along medullary ray j2 that is initial and that terminate between end, due to along medullary ray j2 that is initial and that terminate between end, the distance of end A1 is terminated from maximum width portion Wmax to recess, shorter with from axle center O to being set as compared with the distance of recess initiating terminal A2, therefore when considering taking the line segment of the line segment of the maximum width portion Wmax between junction symbol B2 position and coupling recess portion initiating terminal A2 and recess termination end A1 as cornerwise tetragon, identical with the example of Fig. 6 (c), the interior angle 1 terminating end side becomes big compared with the interior angle 2 of side, top.

Fig. 7 represents other enforcement modes, and Fig. 8 represents another other enforcement mode.

In the enforcement mode of Fig. 7, the radius of curve r-3 in the curve interval 12 of the initiating terminal side of recess initiating terminal A2 side is set as less than the radius of curve r-2 in curve interval, side 19. Here, although the mid point C between the intersection point C of the end edge of injection edge line j1 and recess 10₀Consistent with intersection point P, but can freely set mid point C₀Whether consistent with intersection point P.

In addition, in the enforcement mode of Fig. 8, compared with the enforcement mode of Fig. 7, slightly increase the radius of curve r-3 in the curve interval 12 of the initiating terminal side of recess initiating terminal A2 side, and by install interval 18 towards the direction being configured to tilt relative to injection edge line j1. Though installing interval 18 not report to the leadship after accomplishing a task with injection edge line j1, but their extended line, report to the leadship after accomplishing a task with less angle in the region beyond recess 10. Even if by such mode installing interval 18, it is also possible to fuel to be fixed to curve interval, side 19. Just, terminate end A1 side from recess initiating terminal A2 side towards recess, make installation interval 18 and injection edge line j1 gradually be narrowed good.

In these embodiments, it is uniformly distributed around the spray centerline j0 of vergence direction from the injection form of the fuel of cylinder injection valve 9 injection, and, under the prerequisite that the spray centerline j0 of vergence direction is consistent on orthographic plan with medullary ray j2 that is initial and that terminate between end, using the object of medullary ray j2 that is initial as clamping for the shape comprising the piston 2 of recess 10 and that terminate between end, but the form according to fuel injection, the position of cylinder injection valve 9, can also consider that the shape of the piston 2 by comprising recess 10 is set to the enforcement mode of the object of medullary ray j2 that non-clamping is initial and terminates between end.

Claims

1. a direct injection engine piston, is formed with recess at piston end face, it is characterised in that,

The recess of the axle center of described recess clamp piston and the recess initiating terminal and another side that are arranged at side terminates between end,

The described recess of described recess terminates the end wall of end side, by forming with the vertical portion of described axis parallel and the curved surface that is connected described vertical portion and described recess bottom surface with on the arbitrary cross section of the axis parallel of piston.

2. direct injection engine piston as claimed in claim 1, it is characterised in that, the ridge line section between piston end face around described vertical portion and described recess is provided with chamfered section.

3. direct injection engine piston as claimed in claim 1, it is characterised in that,

Terminate end with the described recess initiating terminal and described recess that connect described recess and pass through the maximum width portion that the width on the orthogonal direction of the medullary ray between the initial of described axle center with termination end is the widest, it is positioned at described recess initiating terminal side compared with described axle center along the described initial and medullary ray that terminates between end

The distance terminating end from described maximum width portion to described recess along the described initial and medullary ray that terminates between end, is set as shorter than the distance from described axle center to described recess initiating terminal.

4. direct injection engine piston as claimed in claim 3, it is characterized in that, described recess terminates the radius of curve of the described curved surface of end side end wall, is set as bigger than the radius of curve of the curved surface being arranged at the end wall of described recess initiating terminal side and hold up from described recess bottom surface.

5. direct injection engine piston as claimed in claim 1, it is characterised in that, the tie point of described vertical portion and described curved surface, be positioned at also high than the apical side height of the piston adjacent with described recess in described recess initiating terminal side above.

6. direct injection engine piston as described in any one of claim 1 to 5, it is characterized in that, terminate the end face of the end side piston adjacent with described recess at described recess, it is set as also higher than the end face of the piston adjacent with described recess in described recess initiating terminal side.