JPH0667839U - piston - Google Patents

Abstract

(57) [Summary] [Purpose] The flatness of the upper and lower surfaces of the oil ring groove can be obtained, the sealing with the upper surface of the oil ring is improved, and the oil passage resistance is reduced to scrape the oil ring. (EN) Provided is a piston in which the oil is smoothly discharged into the piston and, moreover, an oil escape hole can be easily obtained without drilling. [Structure] In a piston having an oil ring groove into which a thin oil ring is formed, which has only one contact surface with the cylinder, a piston is provided inward from the bottom of the piston on the rear surface of the bottom of the oil ring groove. An oil relief hole with a vertically continuous open end is provided, and the width of the communicating portion at the bottom of the oil ring groove is made uniform from the upper surface to the lower surface of the oil ring groove, and the oil relief hole is formed from inside the piston to the oil ring groove. A piston characterized by being provided so as to communicate with each other at a height larger than the entire width of the bottom.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a piston of an internal combustion engine, and more particularly to an oil relief structure in an oil ring groove of the piston.

[0002]

[Prior art]

 Conventionally, as an oil escape structure in an oil ring groove of a piston of an internal combustion engine, there is one disclosed in Japanese Utility Model Publication No. 58-150666. This will be described with reference to FIG. 7A. 1 is a piston, 2 is an oil ring groove in which an oil ring 3 is fitted, and the lower surface 2a of the oil ring groove 2 is an oil communicating with the inside of the piston 1. A relief hole 4 is provided.

In such an oil relief structure in the oil ring groove, the lower surface 3 a of the oil ring 3 is located on the lower surface 2 a side of the oil ring groove 2 as shown in FIG. Yes, oil escapes from the land portion 5 from the upper surface 3b side of the oil ring 3 to the oil escape hole 4 on the rear surface of the oil ring 3, and as shown in (a) of FIG. The upper surface 3b is located on the upper surface 2b side of the oil ring groove 2, and oil from the outside of the piston skirt 6 escapes from the lower surface 3a side of the oil ring 3 to the oil escape hole 4.

By the way, since the oil escape hole 4 is provided up to the lower surface 2a of the oil ring groove 2, the tool escapes during the machining of the oil ring groove 2 and the upper surface of the thin oil ring groove 2 is removed. 2b becomes a rough surface, and flatness of both upper and lower surfaces cannot be obtained. Therefore, even if the upper surface 3b of the oil ring 3 comes into contact with the upper surface 2b of the oil ring groove 2 in the downward stroke of the piston 1, a clearance 7 is generated as shown in FIG. The seal between 3b and the upper surface 2b of the oil ring groove 2 became defective, leading to an increase in blowby gas and an increase in oil consumption.

Further, since the lower surface 2a of the oil ring groove 2 is interrupted by the oil escape hole 4 at a plurality of circumferential positions to form a semicircular recess 9, the oil ring 3 is lifted during the upward stroke of the piston 1. When the lower surface 3a of the oil contacts the lower surface 2a of the oil ring groove 2, the oil ring 3 partially falls into the semicircular recess 9 as shown in FIG. , Oil is hard to miss. Moreover, the behavior of the oil ring 3 becomes unstable, the oil ring 3 bends in the circumferential direction, and the conformability with the lower surface 2a of the oil ring groove 2 deteriorates.

Therefore, it is possible to form the oil escape hole 4 only on the bottom surface of the oil ring groove 2 by drilling, but it is difficult because the groove width is extremely small.

In addition to the above, as a piston for an internal combustion engine provided with an oil escape hole, as shown in Japanese Utility Model Laid-Open No. 53-85409, a thin portion other than the piston pin boss portion is formed in the oil ring groove forming portion. Has an oil relief hole through which the oil ring groove directly communicates with the hollow part inside the piston, and through the pin hole from the lower part of the piston pin boss part to the oil ring groove and the bottom part of the pressure ring groove adjacent to the oil ring groove. There is a piston for an internal combustion engine, which is characterized by having an oil relief hole communicating therewith.

However, in this piston for an internal combustion engine, the oil relief hole that directly communicates with the hollow portion inside the piston is a horizontal slit, and the slit is formed in the middle height of the bottom of the groove into which the thick oil ring is fitted. The oil ring has a groove width provided, and the oil ring has an annular groove with a V-shaped cross section on the outer peripheral surface to make two contact surfaces, and a small hole penetrating the inner peripheral surface is provided at the bottom of the annular groove The oil scraped by the oil ring is hard to escape because it is provided at the end. In addition, the oil escape hole communicating from the bottom of the piston pin boss through the pin hole to the bottom of the oil ring groove and the pressure ring groove adjacent to the oil ring groove has no open end inside the piston, and the oil escape hole Since the hole is a small circular hole and the end of the piston pin is located on the way, the oil scraped by the oil ring cannot be smoothly discharged from the ring groove to the inside of the piston through the oil escape hole. Further, the above-mentioned thin hole escape holes and small circular hole escape holes are extremely difficult to process.

[0009]

[Problems to be solved by the device]

 Therefore, the present invention was developed to solve the above-mentioned problems of the prior art. It is possible to obtain the flatness of the upper and lower surfaces of the oil ring groove, and to improve the sealing with the upper surface of the oil ring, and to provide the oil passage. Attempt to provide a piston that reduces resistance and allows oil scraped by an oil ring to be smoothly discharged inside the piston, and moreover, an oil escape hole can be easily obtained without drilling. It is a thing.

[0010]

[Means for Solving the Problems]

 The piston of the present invention for solving the above-mentioned problems is a piston having an oil ring groove into which a thin oil ring formed with only one contact surface with the cylinder is fitted. An oil relief hole with a vertically continuous open end is provided on the back of the piston from the bottom to the inside of the piston, and the width of the communication part at the bottom of the oil ring groove is made uniform from the top surface to the bottom surface of the oil ring groove. It is characterized in that the escape hole is provided so as to communicate with the inside of the piston at a height larger than the entire width of the bottom of the oil ring groove.

[0011]

[Action]

 As described above, in the piston of the present invention, the oil escape hole that communicates with the inside of the piston at a height larger than the entire width of the oil ring groove is formed vertically from the bottom of the piston to the inside of the piston. The oil scraped by the oil ring is smoothly discharged into the piston through the oil relief hole from the oil groove. In addition, during machining of the oil ring groove, the tool does not escape, the upper and lower surfaces of the oil ring groove are well finished, and high flatness is obtained. Therefore, the upper surface of the oil ring and the upper surface of the oil ring groove are brought into close contact with each other during the piston descending stroke to complete the seal, and the blow bath gas and oil consumption can be reduced.

[0012]

【Example】

 An embodiment of the piston of the present invention will be described. First, an embodiment of the piston of the present invention will be described with reference to FIG. 1. Reference numeral 1 is a piston, 2 is a thin oil ring groove into which an oil ring 3 is fitted, and a bottom portion 2c of the oil ring groove 2 has a bottom portion 2c. A plurality of vertical oil escape holes 10 communicating with the inside of the piston at a height larger than the entire width of 2c are provided at equal intervals in the circumferential direction, in this example, eight holes are provided. The oil escape hole 10 is formed by a punching die arranged inside the piston 1 during casting, and the thick wall portion 1b on the inner peripheral surface upper side of the piston skirt 1a is vertically formed into a slit shape. It was done.

Next, another embodiment of the piston of the present invention will be described with reference to FIG. 2. The piston of this embodiment is inclined outward at the lower portion of the inlet of the oil ring groove 2 in the piston of the embodiment of FIG. A cutout portion 11 is provided, and an oil escape passage 12 communicating with the inside of the piston is provided in the cutout portion 11 in an inclined manner. The oil escape passage 12 is provided between the oil escape holes 10 in the circumferential direction. It is distributed.

In a further embodiment of the piston of the present invention, a vertical cutout 13 is provided at the lower part of the inlet of the oil ring groove 2 as shown in FIG. 3, and the cutout 13 communicates with the oil escape passage 12 inside the piston. The oil escape passage 12 is arranged between the oil escape holes 10 in the circumferential direction.

In the pistons of the respective embodiments configured as described above, the oil escape hole 10 in the oil ring groove 2 has a height larger than the entire width of the oil ring groove 2 only at the bottom of the oil ring groove 2. Since it is provided vertically from the bottom of the piston to the inside of the piston, the machining of the oil ring groove 2 is not affected by the oil escape hole 10, the tool does not escape, and the upper and lower parts of the oil ring groove 2 are not removed. Both sides have good finish and high flatness. Therefore, in the piston in which the oil ring 3 is fitted in the oil ring groove 2, when the upper surface 3b of the oil ring 3 comes into contact with the upper surface 2b of the oil ring groove 2 in the descending stroke as shown in FIGS. , The both sides are in close contact and the seal is complete, and blow-by gas and oil consumption can be reduced. Then, the oil from the outside of the piston skirt 1a smoothly escapes into the piston through the oil escape hole 10 through the gap formed between the lower surface 3a of the oil ring 3 and the lower surface 2a of the oil ring groove 2.

On the other hand, when the lower surface 3a of the oil ring 3 comes into contact with the lower surface 2a of the oil ring groove 2 as shown by the alternate long and short dash line in FIGS. It is complete and the oil ring 3 does not bend in the circumferential direction. Then, the oil from the land portion 5 smoothly escapes from the oil escape hole 10 to the inside of the piston through the gap formed between the upper surface 3b of the oil ring 3 and the upper surface 2b of the oil ring groove 2.

Further, in the piston of the embodiment shown in FIGS. 2 and 3, notches 11 and 13 are further provided in the lower portion of the inlet of the oil ring groove 2, and the oil escape passage 12 communicating with the inside of the piston is provided in the notches 11 and 13. Since a large amount of oil scraped off by the lower surface 3a of the piston ring 3 is formed by the cylinder inner wall 14 and the notches 11 and 13 during the piston descending stroke as shown in FIGS. It is returned from the oil reservoirs 15 and 16 directly into the piston through the oil escape passage 12. At this time, the passage resistance is small, so the oil is very easy to escape.

[0018]

[Effect of device]

 As can be seen from the above description, in the piston of the present invention, the oil escape hole, which communicates with the inside of the piston at a height larger than the entire width of the oil ring groove, extends continuously from below the piston to the inside of the piston. Since it is installed vertically, the oil scraped by the oil ring is smoothly discharged into the piston from the oil groove through the oil relief hole. In addition, during machining of the oil ring groove, the tool does not escape, the upper and lower surfaces of the oil ring groove are well finished, and high flatness is obtained. Therefore, in the downward stroke of the piston, the upper surface of the oil ring and the upper surface of the oil ring groove are brought into close contact with each other to complete the seal, so that the blow bath gas and oil consumption can be reduced. Furthermore, since the oil escape hole is formed by a punching die placed inside during piston casting, there is no need to drill the oil escape hole, resulting in excellent productivity.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of an essential part of an embodiment of a piston according to the present invention.

FIG. 2 is a longitudinal sectional view of a main part of another embodiment of the piston according to the present invention.

FIG. 3 is a longitudinal sectional view of a main part of a piston according to another embodiment of the present invention.

FIG. 4 is a cross-sectional view of essential parts showing a usage state of the piston of FIG. 1.

FIG. 5 is a cross-sectional view of essential parts showing a usage state of the piston of FIG.

FIG. 6 is a cross-sectional view of essential parts showing a usage state of the piston of FIG.

FIG. 7 is a view showing a usage state of a conventional piston,
(A) is a sectional view of an essential part during a piston descending stroke, and (b) is a sectional view of an essential part during a piston ascending stroke.

8A is a sectional view taken along line AA of FIG. 7A, and FIG.
FIG. 8 is a sectional view taken along line BB in FIG.

[Explanation of symbols]

 1 Piston 2 Oil ring groove 2c Bottom of oil ring groove 3 Oil ring 10 Oil escape hole

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[Procedure amendment]

[Submission date] July 1, 1993

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Fig. 2]

[Figure 3]

[Figure 5]

[Figure 1]

[Figure 4]

[Figure 6]

[Figure 7]

[Figure 8]

Claims (1)

[Scope of utility model registration request] 1. A piston provided with an oil ring groove into which a thin oil ring formed with only one contact surface with a cylinder is fitted, the piston having a bottom surface of the oil ring groove,
An oil escape hole having a vertically continuous open end is provided from below to the inside of the piston, and the width of the communicating portion at the bottom of the oil ring groove is made uniform from the upper surface to the lower surface of the oil ring groove, and the oil escape hole is formed in the piston. A piston, which is provided so as to communicate with the inside at a height larger than the entire width of the bottom of the oil ring groove.