JP2601006Y2 - piston - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston body having a crown portion and a skirt portion, and a piston having an outer ring member fitted to the skirt portion with a buffer member interposed therebetween.

[0002]

2. Description of the Related Art One of the noises generated by driving an internal combustion engine is a slap sound. The slap noise is generated when the skirt of the piston collides with the cylinder liner when the piston reciprocates in the cylinder. That is, while a gap is formed between the piston and the cylinder liner wall so that the piston can reciprocate in the cylinder, a piston ring formed on the piston is formed to prevent blowdown from the combustion chamber. Since the piston ring is fitted in the groove, when the piston reciprocates in the cylinder, the piston collides with the cylinder liner wall surface in the direction perpendicular to the piston pin axis, that is, in the thrust direction, and slap noise is generated.

Conventionally, various pistons have been developed in order to reduce the slap noise. For example, as shown in FIGS. 3, 4 and 5, a piston (Japanese Patent Application No. 137,009). This piston will be described with reference to the drawings. 3 is an exploded view of the piston, FIG. 4 is an assembled front view of the piston of FIG. 3, and FIG. 5 is a sectional view taken along line CC of FIG.

The piston body 1 has a crown 2 having a piston ring groove 12 and a skirt 3 having a boss 13 having a pin hole 4 through which a piston pin 22 is inserted. , And skirt part 3
And a pair of semicircular outer ring members 7 fitted with a buffer member 6 interposed therebetween. A plurality of recesses 5 into which the cushioning members 6 are fitted are formed symmetrically with respect to the pin holes 4 in the arcuate surface portion of the skirt portion 3. The outer ring support member 10 that supports the outer ring member 7 is provided so as to be rotatable around the axis of the piston pin 22. Further, the outer ring supporting member 10 regulates the relative movement of the outer ring
Has locking portions 20 and 21 that allow relative movement in the thrust direction.

[0005] The outer ring member 7 is constituted by a semi-circular surface member 7b divided into two parts with respect to the axis of the piston pin 22. Arm portions 18 extending in the circumferential direction are respectively provided on both circumferential sides of each semi-circular surface member 7b. The arm 18 is provided with the outer ring support member 1.
It is slidably engaged with a groove 19 formed by the locking portions 20 and 21 of the "0".

The outer ring supporting member 10 is a columnar body having an arc-shaped cross section, and has a flat surface 14 formed on the skirt portion 3 of the piston body 1, that is, a boss portion 13 having the pin hole 4 formed therein, and the outer ring member 7 Are arranged in a space formed between the inner surface of the base and the inner surface of the base. The groove 19 is defined by engaging portions 20 and 21 which are formed on the upper and lower portions of the outer ring supporting member 10 in a convex shape, respectively. Since the width W of the groove 19 and the width AW of the arm 18 are substantially equal, the arm 18 can slidably engage the groove 19.

The diameter PD of the piston pin 22 is substantially equal to the inner diameter D of the pin hole 4 of the piston body 1, and the piston pin 22 is fitted and fixed in the pin hole 4 of the piston body 1. The piston pin 22 has a center hole 28, and the sub piston pin 23 is attached to the center hole 28. The sub-piston pin 23 includes a pin portion 26 including a small-diameter portion 24 and a large-diameter portion 25, and a cap portion 27 formed at an end of the large-diameter portion 25. The diameter Sd _{1 of the} small diameter portion 24 is formed to be equal to the inner diameter d ₁ of the center hole 28 of the piston pin 22.
Can be press-fitted. The diameter Ld ₂ of the large diameter portion 25 is formed slightly smaller than the inner diameter d _{2 of the} hole 29 formed in the groove 19 of the outer ring support member 10.

The assembly of the piston is performed as follows. First, the piston pin 22 is inserted and fixed in the pin hole 4 of the piston body 1, and then the outer ring support member 10 is applied to the boss portion 13 of the piston body 1 so as to sandwich the piston pin 22 from both sides. The small diameter portion 24 at the tip of 23 is press-fitted into the center hole 28 of the piston pin 22. As a result, the large-diameter portion 25 of the sub piston pin 23 is inserted into the hole 29 of the outer ring support member 10, and in this state, the outer ring support member 10 becomes rotatable with respect to the piston pin 22. . Thereafter, the cushioning member 6 is fitted into the concave portion 5 formed in the skirt portion 3 of the piston main body 1, and then the arm portion 18 is attached to the outer ring supporting member 10 by sandwiching the skirt portion 3 from both sides by the two semi-circular surface members 7b. By inserting the piston into the groove 19, the piston is assembled. Both arms 18 have their tips 17 assembled to the outer ring support member 10 with a predetermined clearance, and the outer ring member 7 is easily disengaged in the state of a single piston. However, if the piston is housed in the cylinder liner, the outer ring member 7 is elastically supported by the cylinder liner by receiving a force from the buffer member 6 in a direction in which the cylinder liner is constantly pushed open. When the piston is housed in the cylinder liner, the arm 18 of the outer ring member 7 engages with the groove 19 even if the cushioning member 6 is detached for some reason. Therefore, an accident that the outer ring member 7 separates from the piston main body 1 does not occur.

The operation of this piston is as follows. The outer ring member 7 is moved by a piston pin 22 by the outer ring support member 10.
Relative movement in the up and down direction is restricted, and relative movement in the thrust direction is allowed. Further, since the outer ring support member 10 is rotatably attached to the piston pin 22, the piston can reciprocate during reciprocation. Even if the outer ring member 7 receives a thrust force or a force rotating around the axis of the piston pin 22, an excessive force is applied to the arms 18 of the outer ring member 7 and the locking portions 20 and 21 of the outer ring support member 10. Without acting, the outer ring member 7 can smoothly move relative to the outer ring support member 10 in the thrust direction. Further, with the reciprocating motion of the piston, the piston main body 1 swings around the axis of the piston pin 22, and the skirt member 3 gives an impact to the cylinder liner wall surface via the buffer member 6 and the outer ring member 7. However, since the outer ring member 7 is configured to be relatively movable in the thrust direction and rotatable around the axis of the piston pin 22 without moving relative to the piston body 1 in the vertical direction, the piston body 1 Is rocked by the buffer member 6 and transmitted to the outer ring member 7, and the impact force is reduced, so that the slap noise is reduced.

[0010]

In the above-mentioned piston, the outer ring member 7 is supported by the outer ring support member 10 by the arm portion 18 being engaged with the locking portions 20 and 21. However, the relationship between the outer ring member 7, the outer ring support member 10, and the cylinder liner wall surface 8 will be examined in more detail with reference to FIG. As shown in FIG. 6, the radius of curvature of the outer surface 9 of the outer ring member 7 is formed to be equal to the radius of curvature of the cylinder liner wall surface 8. The locking portions 20 and 21 of the outer ring support member 10 are formed in an arc-shaped cross section.
It is not preferable that the side surface 11 of the outer ring 0, 21 slides on the cylinder liner wall surface 8 from the viewpoints of wear, seizure, deformation, and the like. An appropriate gap a is provided between the side surfaces 11 of the locking portions 20 and 21 and the cylinder liner wall surface 8 so that the cylinder liner wall surface 8 does not contact the cylinder liner wall surface 8.

However, when the gap a is provided, the contact area between the outer ring member 7 and the outer ring support member 10, ie, the arm 18
Since the contact area between the upper surface 15 and the lower surface 16 and the upper and lower locking portions 20 and 21 is reduced, the contact pressure on the contact surface is increased, and the wear is increased, which is not preferable. In the worst case, the outer ring member 7 may be detached from the outer ring support member 10. Further, as another problem, there is a concern that abrasion may increase or seizure may occur due to a so-called edge contact of the tip 17 of the arm 18 of the outer ring member 7 with the cylinder liner wall 8. Therefore, in the conventional piston, while the gap a is secured,
The problem was how to sufficiently secure the contact area and prevent the tip of the arm 18 from hitting the edge.

It is an object of the present invention to solve the above-mentioned problems, and even if an appropriate gap is provided between the cylinder liner wall surface and the outer ring support member, the upper and lower arms of the outer ring member can be provided. To provide a piston that ensures a sufficient contact area between the arm and the engaging portion of the outer ring support member and does not cause edge contact at the distal end of the arm.

[0013]

The present invention has the following configuration to achieve the above object. That is, the present invention is directed to a piston body including a crown portion and a skirt portion to which a piston pin is attached, a pair of semicircular outer ring members fitted to the skirt portion via a buffer member, and a vertical direction of the outer ring member. A piston having an outer ring supporting member provided with a locking portion for restricting relative movement of the piston and enabling relative movement in the thrust direction and rotatably provided around the axis of the piston pin. A first portion opposed to the cushioning member, a second portion engaged with the locking portion, and a third portion between the first portion and the second portion, wherein a radius of curvature of the first portion is a cylinder liner wall surface. Wherein the radius of curvature of the second portion is smaller than the radius of curvature of the first portion.

Further, in this piston, the skirt portion has a boss portion formed on a flat outer surface with which the piston pin fits, and the outer ring member has a half provided with arms on both circumferential sides. The outer ring support member is disposed in a space formed between the flat surface of the boss portion and the inner surface of the outer ring member, and the locking portion of the outer ring support member is The outer ring member engages with the arm portion of the outer ring member to guide the outer ring member so as to be relatively movable in the thrust direction and to regulate the relative movement in the vertical direction.

Further, in this piston, the center of the radius of curvature of the second portion is offset from the center of the radius of curvature of the first portion in a position farther in the axial direction of the piston pin.

In the piston, the radius of curvature of the third portion is smaller than the radius of curvature of the second portion.

[0017]

Since the piston according to the present invention is constructed as described above, it operates as follows. That is, in this piston, since the outer ring member is formed so that the radius of curvature of the first portion is equal to the radius of curvature of the cylinder liner wall, the piston body swings around the axis of the piston pin with the reciprocating motion of the piston. Although the outer ring member is in contact with the cylinder liner wall surface, the skirt portion presses the cylinder liner wall surface via the cushioning member and the outer ring member in the state in which the outer ring member is in surface contact with the cylinder liner wall surface. Can be obtained.

The second portion is formed such that the radius of curvature is smaller than the radius of curvature of the first portion, and the center of the radius of curvature of the second portion is larger than the center of the radius of curvature of the first portion. By offsetting the arm in the direction, the gap between the side surface of the arm and the wall surface of the cylinder liner increases as the arm approaches the tip of the arm of the outer ring member. Therefore, edge contact at the tip of the arm can be completely avoided. The radius of curvature of the third portion is smaller than the radius of curvature of the second portion, so that the first portion and the second portion are connected smoothly. Furthermore, while the gap between the side surface of the locking portion and the cylinder liner wall surface is constant, the gap between the side surface of the arm portion and the cylinder liner wall surface becomes larger toward the tip of the arm portion. The contact area between the upper and lower surfaces of the arm and the locking portion is considerably larger than that of the conventional one.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a piston according to the present invention will be described below with reference to the drawings. 1 and 2 show an embodiment of the piston according to the present invention. FIG. 1 is an exploded sectional view showing a piston body and an outer ring member.
FIG. 6 is a cross-sectional view showing a relationship among an outer ring member, an outer ring support member, and a cylinder liner wall surface.

The piston according to the present invention is shown in FIGS.
And the conventional piston shown in FIG. 5, the external structure of the piston body 1, the cushioning member 6, the outer ring member 7, the outer ring support member 10, the piston pin 22, and the sub piston pin 23 is the same as that of the conventional piston. It is almost the same as the piston.
The main difference between the two is that the curvature of the outer surface 9 of the outer ring member 7 differs depending on the portion, or the curvature of the outer surface 9 is constant everywhere. Therefore, the piston according to the present invention is the same as the above-described conventional piston except for the outer ring member 7, and therefore, the same parts are denoted by the same reference numerals and the duplicate description will be omitted.

Hereinafter, the outer ring member 7 will be described. FIG.
As shown in the figure, the outer ring member 7 is composed of a pair of semi-circular surface members 7b, and each semi-circular surface member 7b has arms 18 on both sides in the circumferential direction. The semi-circular surface member 7b has a first portion 30 and a second portion 3 depending on the difference in curvature of the outer surface 9.
The first and third portions 32 are roughly divided into three regions.

The first portion 30 is a portion facing the cushioning member 6 arranged on the skirt portion 3. That is, the angle α of the first portion 30 is substantially equal to the angle α of the arc-shaped surface portion of the skirt portion 3 in which the concave portion 5 for fitting the buffer member 6 is formed.
The first portion 30 is formed such that the radius of curvature R ₁ is equal to the radius of curvature of the cylinder liner wall surface 8. The center P of the radius of curvature R ₁ is on the center line XX of the piston body 1.

The second portion 31 is a portion to be engaged with the locking portions 20 and 21 of the outer ring support member 10, and includes the arm portion 18 and the base portion thereof. The radius of curvature R ₂ of the second portion 31 is smaller than the radius of curvature R ₁ of the first portion 30. Center Q of the radius of curvature R ₂ of the second portion 31 are offset at a position away in the axial Y-Y direction by a distance L of the first portion 30 of the radius of curvature R ₁ of the center P piston pin 22 than. Note that this offset is not always necessary.

The third part 32 includes the first part 30 and the second part 3
1 is a connection part. The radius of curvature R ₃ of the third portion 32 is smaller than the radius of curvature R ₂ of the second portion 31. The first portion 30 and the second portion 31 are smoothly connected by the third portion 32.

As described above, the respective radii of curvature of the outer ring member 7 of the piston have a relationship of R ₁ > R ₂ > R ₃ . As described above, the outer ring member 7 of the piston according to the present invention is characterized in that it has a larger curvature on both sides in the circumferential direction, instead of an arc having a constant curvature unlike the conventional outer ring member.

Next, the relationship between the outer ring member 7 and the outer ring support member 10 will be described with reference to FIG. Outer ring member 7
Since the radius of curvature R ₁ of the first portion 30 is formed equal to the radius of curvature of the cylinder liner wall 8, the piston body 1 is swung around the axis of the piston pin 22 with the reciprocating motion of the piston, the outer ring When the member 7 is in surface contact with the cylinder liner wall surface 8, the skirt member 3 gives an impact to the cylinder liner wall surface 8 via the buffer member 6 and the outer ring member 7. Therefore, the slap sound can be effectively reduced.

The radius of curvature R ₂ of the second portion 31 is formed to be smaller than the radius of curvature R ₁ of the first portion 30.
The gap between the side surface 9 and the cylinder liner wall surface 8 increases. Therefore, it is possible to avoid the edge contact at the tip portion 17 of the arm portion 18. Further, even if the piston is subjected to force in the axial direction of the piston pin 22, the radius of curvature R ₂ of the second portion 31 is smaller than the radius of curvature of the cylinder liner wall 8, never strikes the edge occurs.

The gap a between the side surfaces 11 of the locking portions 20 and 21 and the cylinder liner wall surface 8 is formed to be constant, whereas the gap a between the side surface 9 of the arm portion 18 and the cylinder liner wall surface 8 is formed. Since the gap is larger at the tip of the arm 18, the contact area between the upper surface 15 and the lower surface 16 of the arm 18 and the corresponding upper and lower locking portions 20, 21 is sufficient compared with the conventional one. Can be bigger. The shape of the groove 19 of the outer ring support member 10 is preferably formed in accordance with the curvature of the second portion 31 so that the outer ring member 7 slides smoothly in the thrust direction with respect to the outer ring support member 10. . Further, in FIG. 2, the depth of the groove 19 is smaller than the thickness of the arm 18, but the depth of the groove 19 may be increased.

[0029]

[Effects of the Invention] The present invention is configured as described above and has the following effects. Since the outer ring member of this piston is formed so as to have a large curvature on both sides in the circumferential direction instead of an arc having a constant curvature, a gap a is provided between the side surface of the locking portion and the cylinder liner wall surface. Even in this case, a sufficient contact area between the arm portion of the outer ring member and the locking portion of the outer ring support member is ensured. For this reason, the surface pressure on the contact surface between the arm portion and the locking portion is reduced, and the problem of wear on the contact surface can be avoided. In addition, since the contact area increases, the problem that the outer ring member detaches from the outer ring support member and drops off can also be avoided.

The outer ring member of the piston is formed not to be a circular arc having a constant curvature but to have a large curvature on both sides in the circumferential direction. Therefore, the edge of the tip of the outer ring member with respect to the wall surface of the cylinder liner is formed. The hit can be prevented. For this reason, problems such as wear and seizure of the distal end portion of the outer ring member or the cylinder liner wall surface can be avoided.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a piston according to the present invention, which is an exploded sectional view showing a piston body and an outer ring member.

FIG. 2 is a cross-sectional view of the piston according to the present invention, showing a relationship among an outer ring member, an outer ring support member, and a cylinder liner wall surface.

FIG. 3 is an exploded view of a piston according to the present invention, and also an exploded view of a conventional piston.

FIG. 4 is an assembled front view of the piston of FIG. 3;

FIG. 5 is a sectional view taken along line CC in FIG. 4;

FIG. 6 is a cross-sectional view of a conventional piston, showing a relationship among an outer ring member, an outer ring support member, and a cylinder liner wall surface.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Piston main body 2 Crown part 3 Skirt part 6 Buffer member 7 Outer ring member 7b Semicircular surface member 8 Cylinder liner wall surface 10 Outer ring support member 13 Boss part 18 Arm part 20 Locking part 21 Locking part 22 Piston pin 30 First part 31 second portion 32 third portion R ₁ radius of curvature of first portion R ₂ radius of curvature of second portion R ₃ radius of curvature of third portion P center of radius of curvature of first portion Q center of radius of curvature of second portion

Claims (4)

(57) [Scope of request for utility model registration] 1. A piston body comprising a crown portion and a skirt portion to which a piston pin is attached, a pair of semicircular outer ring members fitted to the skirt portion via a buffer member, and a vertical direction of the outer ring member. A piston having an outer ring support member provided with a locking portion that regulates relative movement and enables relative movement in the thrust direction and is rotatably provided around the axis of the piston pin; A first portion opposed to the cushioning member, a second portion engaged with the locking portion and a third portion between the first portion and the second portion, the radius of curvature of the first portion is the wall surface of the cylinder liner. A piston substantially equal to a radius of curvature, wherein the radius of curvature of the second portion is smaller than the radius of curvature of the first portion. 2. The skirt portion has a boss portion formed on a flat outer surface with which the piston pin fits, and the outer ring member is formed of a semi-circular surface member having arms on both sides in the circumferential direction. The outer ring supporting member is disposed in a space formed between the flat surface of the boss portion and the inner surface of the outer ring member, and the locking portion of the outer ring supporting member is 2. The piston according to claim 1, wherein the piston engages with the arm portion to guide the outer ring member so as to be relatively movable in a thrust direction and regulates the relative movement in a vertical direction. 3. 3. The center of the radius of curvature of the second portion is offset to a position further away from the center of the radius of curvature of the first portion in the axial direction of the piston pin. Piston. 4. The apparatus according to claim 1, wherein a radius of curvature of said third portion is smaller than a radius of curvature of said second portion.
The piston according to any one of the above items.