JP6274190B2 - Internal combustion engine and piston pin - Google Patents

Description

  The present invention relates to an internal combustion engine and a piston pin, and more particularly to an internal combustion engine and a piston pin that include a dynamic vibration absorber for suppressing the generation of noise associated with combustion.

  Conventionally, it is known that a large vibration phenomenon (resonance) occurs and noise is generated when the frequency of the external force matches the natural frequency of a vibrating body that vibrates due to the external force. In an internal combustion engine, resonance occurs when the frequency of the vibration force such as a piston, a connecting rod, and a crankshaft that vibrates due to the vibration generated by combustion coincides with the natural frequency, and noise (combustion noise) is generated. .

  Non-Patent Document 1 discloses that combustion noise has three peaks of 1.7 kHz, 3.3 kHz, and 6 kHz, each of which is caused by a secondary longitudinal bending resonance in which a crankshaft and a cylinder block are integrated, and a connecting rod. It is disclosed that they are expansion resonance and combustion chamber resonance. Non-Patent Document 1 also discloses that these frequencies are determined by the basic structure of the internal combustion engine.

  In Patent Documents 1 to 3, focusing on the fact that the expansion and contraction resonance of the connecting rod as referred to in Non-Patent Document 1 occurs integrally with the piston, piston pin and the small end of the connecting rod, in order to suppress this expansion and contraction resonance A technique for providing a dynamic vibration absorber in an internal combustion engine is disclosed. In Patent Documents 1 and 2, specifically, a dynamic vibration absorber is provided inside a tubular piston pin that connects a piston and a connecting rod. This dynamic vibration absorber is equivalent to a mass body that is fixed to the inner peripheral surface of the piston pin, a support portion that is supported by the fixed portion and corresponds to an elastic body, and that is connected to the fixed portion via the support portion. And a movable part. On the other hand, in Patent Document 3, a dynamic vibration absorber is provided on the back surface of the piston (that is, the surface opposite to the top surface of the piston). This dynamic vibration absorber includes a fixed portion fixed to the back surface of the piston, and a beam portion supported by the fixed portion and corresponding to a mass body and an elastic body.

Japanese Patent Laying-Open No. 2015-083826 International Publication No. 2014/034034 JP 2014-095297 A

Masaya Otsuka "Diesel Combustion Noise Reduction Method in Engine Structure", Automobile Engineering Society Academic Lecture Preprint, 2005

In the dynamic vibration absorbers of Patent Documents 1 and 2, the square root (= (k / m) ^1/2 ) of the value of the spring constant k of the support part with respect to the mass m of the movable part is adjusted to a predetermined value. Resonance is suppressed. Further, in the dynamic vibration absorber of Patent Document 3, the square root (= (k / m) ^1/2 ) of the value of the spring constant k of the beam portion with respect to the mass m of the beam portion is adjusted to a predetermined value. Resonance is suppressed. That is, in the dynamic vibration absorbers of Patent Documents 1 to 3, the expansion and contraction resonance of the connecting rod is suppressed by adjusting the square root of the spring constant k of the elastic body to the mass m of the mass body to a predetermined value. In other words, the fixing portions of Patent Documents 1 to 3 do not contribute to the suppression of expansion and contraction resonance of the connecting rod that is suppressed by the dynamic vibration absorber including the mass body and the elastic body, and the inner peripheral surface of the piston pin and the piston. It exists only to attach a mass or elastic body to the back.

  Since weight reduction of the internal combustion engine leads to improvement in fuel consumption, it is desirable to exclude as much as possible elements that may lead to an increase in the weight of the internal combustion engine. In this respect, in Patent Documents 1 to 3, since the fixing portion is considered to correspond to this element, further improvement is required.

  The present invention has been made in view of the above-described problems. That is, in the case of providing a dynamic vibration absorber for suppressing expansion and contraction resonance of the connecting rod, an object is to reduce the weight of the internal combustion engine and the piston pin to be installed.

An internal combustion engine according to the present invention includes a piston pin that connects a piston and a connecting rod. The piston pin includes a tubular pin body and a dynamic vibration absorber for suppressing expansion and contraction resonance of the connecting rod accompanying combustion. The dynamic vibration absorber is fixed to the pipe end of the pin body. The fixed position of the dynamic vibration absorber is a side surface of the tube end portion in the central axis direction of the pin main body.

  In the internal combustion engine according to the present invention, the dynamic vibration absorber may include a spring portion corresponding to an elastic body and having a tubular spring portion having an outer diameter smaller than the outer diameter of the tube end portion. In this case, the outer peripheral surface of the spring part may be opposed to the outer peripheral surface of the inner peripheral surface which is formed on the pin boss and may oppose the inner peripheral surface of the pin hole into which the pin body is inserted. An annular groove may be formed on the surface along the outer peripheral surface. Further, in this case, a snap ring having an inner diameter that is larger than the outer diameter of the spring portion and smaller than the outer diameter of the tube end portion is fitted into the groove portion when fitted into the groove portion. Also good.

  In the internal combustion engine according to the present invention, the dynamic vibration absorber is a tubular mass portion corresponding to a mass body and a spring portion corresponding to an elastic body, and connects the mass portion and the pipe end portion, and A tubular spring portion having an outer diameter smaller than the outer diameter of the tube end portion. In this case, the outer peripheral surface of the spring part may be opposed to the inner peripheral surface of the pin hole formed in the pin boss and into which the pin body is inserted, and the spring is formed on the inner peripheral surface facing the outer peripheral surface. An annular groove for providing a snap ring having an inner diameter larger than the outer diameter of the tube portion and smaller than the outer diameter of the tube end portion may be formed along the outer diameter of the spring portion. Further, in this case, the mass portion may include a notch portion that extends from the end surface on the spring portion side to the opposite surface to expose the end surface on the mass portion side of the spring portion.

  In the internal combustion engine according to the present invention, the dynamic vibration absorber may include a mass portion corresponding to a mass body and a spring portion corresponding to an elastic body and connecting the mass portion and the pipe end portion. Good. In this case, the mass portion may be a separate member from the pin body. Furthermore, the spring part may be a separate member from the pin body. In this case, a groove part for fitting the spring part may be formed in the pipe end part.

  In the internal combustion engine according to the present invention, the dynamic vibration absorber may have a one-piece structure integrated with the pipe end portion.

  In the internal combustion engine according to the present invention, the tube end portion is inserted into a pin hole formed in a pin boss, and the dynamic vibration absorber has a mass portion whose end surface located outside the pin hole is opposed to the inner wall surface of the cylinder. When provided, the curvature radius of the end surface of the mass portion facing the inner wall surface may be equal to the curvature radius of the inner wall surface.

  In the internal combustion engine according to the present invention, the dynamic vibration absorber may be configured to vibrate at a frequency at which the expansion / contraction resonance occurs and to vibrate at a frequency different from the frequency at which the expansion / contraction resonance occurs.

A piston pin according to the present invention is a piston pin that connects a piston and a connecting rod of an internal combustion engine, and includes a tubular pin body and a dynamic vibration absorber for suppressing expansion and contraction resonance of the connecting rod accompanying combustion. The dynamic vibration absorber is fixed to the tube end of the pin body. The fixed position of the dynamic vibration absorber is a side surface of the tube end portion in the central axis direction of the pin main body.

  In the piston pin according to the present invention, the dynamic vibration absorber is a tubular mass portion corresponding to a mass body and a spring portion corresponding to an elastic body, and connects the mass portion and the tube end portion and A tubular spring portion having an outer diameter smaller than the outer diameter of the tube end portion, the mass portion extends from the end surface on the spring portion side to the opposite surface, and the mass portion of the spring portion You may provide the notch which exposes the end surface of the side.

  In the piston pin according to the present invention, when the dynamic vibration absorber includes a mass portion corresponding to a mass body and a spring portion corresponding to an elastic body and connecting the mass portion and the pipe end portion, The part may be a separate member from the pin body. Furthermore, when the spring part is a separate member from the pin main body, a groove part for fitting the spring part into the pipe end part may be formed.

  In the piston pin according to the present invention, the dynamic vibration absorber may have a one-piece structure integrated with the pipe end portion.

  In the piston pin according to the present invention, the dynamic vibration absorber may be configured to vibrate at a frequency at which the expansion / contraction resonance occurs and to vibrate at a frequency different from the frequency at which the expansion / contraction resonance occurs.

  According to the present invention, the dynamic vibration absorber for suppressing the expansion and contraction resonance of the connecting rod is fixed to the tube end portion of the pin main body, and the member only for fixing the dynamic vibration absorber is omitted. Therefore, it is possible to reduce the weight of the internal combustion engine or the piston pin that is the installation target of the dynamic vibration absorber.

1 is a schematic view of an internal combustion engine according to Embodiment 1 of the present invention. It is a cross-sectional schematic diagram when the internal combustion engine shown in FIG. 1 is cut | disconnected by the AA line. It is a cross-sectional schematic diagram of the edge part periphery of a piston pin when the internal combustion engine shown in FIG. 1 is cut | disconnected by the BB line. It is a figure for demonstrating the modification of the internal combustion engine which concerns on Embodiment 1 of this invention. It is a cross-sectional schematic diagram of the periphery of the end of the piston pin in the internal combustion engine according to Embodiment 2 of the present invention. It is a figure for demonstrating the modification of the internal combustion engine which concerns on Embodiment 2 of this invention. It is a figure for demonstrating the modification of the internal combustion engine which concerns on Embodiment 2 of this invention. It is a figure for demonstrating the modification of the internal combustion engine which concerns on Embodiment 2 of this invention. It is a cross-sectional schematic diagram of the periphery of the end of the piston pin in the internal combustion engine according to Embodiment 3 of the present invention. FIG. 10 is an enlarged schematic view around the spring portion 20 of FIG. 9. It is a cross-sectional schematic diagram of the edge part periphery of the piston pin in the internal combustion engine which concerns on Embodiment 4 of this invention. It is a figure for demonstrating the modification of the internal combustion engine which concerns on Embodiment 4 of this invention. It is a schematic diagram of the periphery of the end of the piston pin in the internal combustion engine according to the fifth embodiment of the present invention. It is a figure for demonstrating the attachment method of the snap ring 10c.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the following embodiments.

Embodiment 1 FIG.
First, Embodiment 1 of the present invention will be described with reference to FIGS.
FIG. 1 is a schematic diagram of an internal combustion engine according to Embodiment 1 of the present invention. 2 is a schematic cross-sectional view of the internal combustion engine shown in FIG. 1 taken along line AA. FIG. 3 is a schematic cross-sectional view around the end of the piston pin when the internal combustion engine shown in FIG. 1 is cut along the line BB. There is no limitation on the type of internal combustion engine to which the present invention can be applied. For example, the present invention can be applied to internal combustion engines such as gasoline engines, diesel engines, naturally aspirated engines, and supercharged engines.

  As shown in FIG. 1, the internal combustion engine according to the present embodiment includes a piston 10, a piston pin 12, and a connecting rod 14. Two pin bosses 10 a are formed on the side surface of the piston 10. Each pin boss 10a is formed with an annular pin hole 10b. Both ends of the piston pin 12 are inserted into the pin holes 10b. An annular groove 10d (see FIG. 3) is formed on the inner peripheral surface of the pin hole 10b along the inner peripheral surface. The snap ring 10c is a C-shaped retaining ring fitted into the groove 10d. The snap ring 10c restricts the movement of the piston pin 12 in the central axis direction. Details of the regulation of the snap ring 10c and the movement of the piston pin 12 thereby will be described later.

  The piston 10 is connected to a small end portion 14 a that is one end portion of a connecting rod 14 through a piston pin 12. A large end portion 14b which is the other end portion of the connecting rod 14 is connected to a crankshaft (not shown). The small end portion 14a and the large end portion 14b are connected by a columnar column portion 14c. An annular through hole 14d into which the piston pin 12 is inserted is formed in the small end portion 14a. On the other hand, an annular through hole 14e into which the crankshaft is inserted is formed in the large end portion 14b.

  The piston pin 12 shown in FIG. 1 is rotatably inserted into the through hole 14d. As shown in FIG. 2, an annular bush 16 is fixed to the inner peripheral surface of the through hole 14d. Strictly speaking, the piston pin 12 is rotatably inserted into the bush 16. A lubricating oil film is formed between the piston pin 12 and the bush 16 by supplying lubricating oil (not shown) circulated in the internal combustion engine. With this lubricating oil film and the bush 16, the piston pin 12 rotates smoothly with respect to the bush 16. The lubricating oil is also supplied between the pin hole 10b and the piston pin 12 to form a lubricating oil film.

  As shown in FIGS. 2 to 3, the piston pin 12 includes a pin body 12a, a spring portion 12b, and a mass portion 12c. The pin body 12a, the spring portion 12b, and the mass portion 12c are formed of a tube having a circular cross section, and form a one-piece structure that shares the through hole 12d. Since the piston pin 12 is inserted into both the pin hole 10 b and the bush 16, the outer diameters of the pin main body 12 a, the spring part 12 b and the mass part 12 c are smaller than the inner diameters of the pin hole 10 b and the bush 16. However, in order to increase the flexibility of the spring portion 12b, the outer diameter of the spring portion 12b is made smaller and at least smaller than the outer diameter of the pin body 12a. On the other hand, the outer diameter of the mass portion 12c only needs to be large enough to avoid contact of the outer peripheral surface of the mass portion 12c with the inner peripheral surface of the pin hole 10b, and may be equal to the outer diameter of the pin body 12a. It may be equal to the outer diameter of the spring part 12b, or may be smaller than the outer diameter of the spring part 12b.

  As shown in FIG. 3, the spring part 12b is accommodated in the pin hole 10b, and the outer peripheral surface of the spring part 12b faces the snap ring 10c. A part of the mass portion 12c is also accommodated in the pin hole 10b, but most of the remaining mass portion 12c is located outside the pin hole 10b. The spring portion 12b and the mass portion 12c are formed at the end of the pin body 12a. For example, the spring portion 12b and the mass portion 12c can be formed at the end portion of the pin body 12a by grinding the end portion of one piston pin having the through hole 12d. In addition, if both the spring part 12b and the mass part 12c are tubular, a cross-sectional shape will not be specifically limited, The cross section of the spring part 12b and the mass part 12c may be a polygon. Further, the entire mass portion 12c may be accommodated in the pin hole 10b together with the spring portion 12b, or may be located outside the pin hole 10b.

  The spring portion 12b corresponds to an elastic body of a dynamic vibration absorber for suppressing expansion and contraction resonance of the connecting rod that is caused by the piston 10, the piston pin 12, and the small end portion 14a being integrated. On the other hand, the mass portion 12c corresponds to a mass body of the dynamic vibration absorber. When the outer diameter of the mass portion 12c is equal to the outer diameter of the spring portion 12b, the entire mass including the mass portion 12c and the spring portion 12b is the elastic body and mass of the dynamic vibration absorber for suppressing the expansion and contraction resonance of the connecting rod. Corresponds to the body.

Here, the expansion and contraction resonance of the connecting rod will be described. The frequency at which the expansion and contraction resonance of the connecting rod occurs is specified by the spring mass model of the piston and the connecting rod. In this spring mass model, the small end portion of the piston, piston pin and connecting rod corresponds to the mass point (mass is M (unit kg)) as a whole, and the column portion connecting the small end portion and the large end portion of the connecting rod. Corresponds to an elastic body (the spring constant is K (unit N / m)) that supports the mass point with respect to the large end. Assuming that the piston, piston pin and the small end of the connecting rod are integrated, the expansion and contraction resonance of the connecting rod occurs at a natural frequency of (1 / 2π) · (K / M) ^1/2 Hz. Details of this spring mass model are disclosed in Patent Documents 1 to 3.

  In the combustion stroke of the internal combustion engine, the piston 10 is pushed down by the combustion pressure. At this time, the lubricating oil film between the piston pin 12 and the bush 16 and the lubricating oil film between the piston pin 12 and the pin hole 10b are partially extremely thin. Then, the piston pin 12 comes into direct contact with both the bush 16 and the pin hole 10b, and the piston 10, the piston pin 12, and the small end portion 14a are integrated, and the above-described precondition of the spring mass model is satisfied. Become. Therefore, by acquiring the total mass M of the piston 10, the piston pin 12, and the small end portion 14a and the spring constant K of the column portion 14c, and substituting them into the above-described spring mass model equation, the expansion and contraction resonance of the connecting rod is achieved. The frequency that occurs is identified.

  The principle of suppressing the expansion and contraction resonance of the connecting rod by the dynamic vibration absorber is as follows. That is, the vibration of the mass body in which the piston 10, the piston pin 12, and the small end portion 14a are integrated is made to vibrate by using the dynamic vibration absorber as a shoulder, thereby suppressing the vibration of the mass body at the natural frequency. Therefore, the sound pressure level at the natural frequency can be lowered. That is, the expansion / contraction resonance of the connecting rod can be suppressed.

Based on the principle described above, in the present embodiment, the square root (k / m) ^1/2 of the value of the spring constant k (unit N / m) of the spring portion 12b with respect to the mass m (unit kg) of the mass portion 12c is Value (K / M) It is adjusted to a value approximately equal to ^1/2 . Here, if the size of the spring portion 12b is changed, the spring constant of the spring portion 12b changes, so the size of the mass portion 12c is fixed (that is, the mass m of the mass portion 12c is fixed), and the size of the spring portion 12b is changed. By changing it, the value (k / m) ^1/2 can be adjusted. However, in the present embodiment, the spring portion 12b and the mass portion 12c are formed at the end of the pin body 12a. Therefore, from the viewpoint of simplifying the adjustment of the value (k / m) ^1/2 , the size of the spring portion 12b is fixed (that is, the spring constant k of the spring portion 12b is fixed) and the mass portion 12c is fixed. It is preferable to change the size. Of course, it is also possible to adjust the value (k / m) ^1/2 by simultaneously changing the sizes of the spring portion 12b and the mass portion 12c.

  Returning to FIG. 2 to FIG. 3, the effect of this embodiment will be described. As described above, the spring portion 12b and the mass portion 12c are formed at the end of the pin body 12a. That is, in the present embodiment, the function of the dynamic vibration absorber is given to the end of the pin body 12a. If the viewpoint is changed, it can be considered that the dynamic vibration absorber is fixed by the pin body 12a. Therefore, according to the present embodiment, a member for the purpose of fixing only the dynamic vibration absorber, which is essential in Patent Documents 1 to 3, can be omitted, and the internal combustion engine and the piston pin to be installed with the dynamic vibration absorber can be reduced in weight. Can be achieved.

  Further, as described above, the outer diameter of the spring portion 12b is smaller than the outer diameter of the pin body 12a. Further, in the present embodiment, as shown in FIGS. 2 to 3, a snap ring 10c is disposed to face the outer peripheral surface of the spring portion 12b. That is, the snap ring 10c is disposed in a space formed outside the spring portion 12b having a small outer diameter. Therefore, according to the present embodiment, the space formed outside the outer peripheral surface of the spring portion 12b is effectively utilized. In addition, since the snap ring 10c restricts the movement of the piston pin 12 in a state where the snap ring 10c is fitted in the groove portion 10d, the inner diameter of the snap ring 10c is the pin main body 12a in a state where the snap ring 10c is fitted in the groove portion 10d. It is adjusted so as to be smaller than the outer diameter. Further, the outer diameter of the snap ring 10c is adjusted to be larger than the outer diameter of the pin body 12a when the snap ring 10c is fitted into the groove 10d.

  Further, in the present embodiment, as shown in FIGS. 2 to 3, the groove portion 10d is provided at a location away from the small end portion 14a on the inner peripheral surface of the pin hole 10b, that is, at a location close to the side surface of the piston 10. Is formed. When the groove portion 10d is formed at a location close to the small end portion 14a, the area of the outer peripheral surface of the pin main body 12a facing the inner peripheral surface is reduced, and the support of the pin main body 12a by the pin boss 10a is likely to be unstable. In this regard, according to the present embodiment, it is possible to secure the area of the outer peripheral surface of the pin main body 12a facing the inner peripheral surface of the pin hole 10b and to ensure the support of the piston pin 12 by the pin boss 10a. it can.

  By the way, in this Embodiment, the snap ring 10c was arrange | positioned facing the outer peripheral surface of the spring part 12b. However, the location of the snap ring 10c is not particularly limited as long as the piston pin 12 can be prevented from falling off the piston 10. For example, a groove corresponding to the groove 10d may be provided along the opening of the pin boss 10a, and the snap ring 10c may be disposed in this groove. In this case, the entire mass portion 12c is located outside the pin hole 10b. Note that this modification can be similarly applied to Embodiments 2 to 4 described later.

Further, in the present embodiment, the end face EF ₁ of the mass portion 12c facing the inner wall surface of the cylinder 30 and the plane. However, as shown in FIG. 4, the curvature radius of the end face EF ₁ of the mass portion 12c facing the inner wall surface of the cylinder 30 may be equal to the radius of curvature of the inner wall surface. By making the curvature radius of the end face EF ₁ equal to the curvature radius of the inner wall surface, the size of the mass portion 12c is maximized within an allowable range, and the adjustment of the value (k / m) ^1/2 is facilitated. Can do. Further, it is possible to satisfactorily prevent the end surface EF ₁ from coming into contact with the inner wall surface of the cylinder 30 and to reliably suppress the expansion and contraction resonance of the connecting rod by the dynamic vibration absorber. The present modification can be similarly applied to the mass portions (the mass portion 18 and the mass portion 182) of Embodiments 2 to 4 described later.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIGS.
FIG. 5 is a schematic cross-sectional view around the end of the piston pin in the internal combustion engine according to Embodiment 2 of the present invention. As shown in FIG. 5, the piston pin 12 includes a pin body 12a, a spring portion 12b, and a mass portion 12c. The point that the pin body 12a, the spring part 12b, and the mass part 12c share the through-hole 12d, and the magnitude relationship of the outer diameters of the pin body 12a, the spring part 12b, and the mass part 12c are the same as in the first embodiment. . Further, the point that the snap ring 10c is arranged facing the outer peripheral surface of the spring portion 12b is the same as that of the first embodiment.

  Unlike Embodiment 1, in this Embodiment, the capacity | capacitance of the mass part 12c is made small. A mass portion 18 is provided so as to cover the mass portion 12c. The mass portion 18 is a member (separate member) different from the mass portion 12c (that is, the piston pin 12). The mass portion 18 is formed from a tube having a circular cross section (the cross-sectional shape of the mass portion 18 is not particularly limited), and has a through hole 18a that communicates with the through hole 12d and allows the lubricating oil to flow inside and outside the piston pin 12. Have. However, the inner diameter of the through hole 18a is made smaller than the inner diameter of the through hole 12d. Further, the outer diameter of the mass portion 18 is enlarged at the end portion on the mass portion 12c side. In addition, a groove portion 18b having a shape corresponding to the shape of the mass portion 12c is formed on the end surface of the mass portion 18 facing the end surface of the mass portion 12c, and the mass portion 12c is pressed into the groove portion 18b. 12c (that is, piston pin 12) and mass portion 18 are connected.

  The effect by this Embodiment is demonstrated. In the present embodiment, the expansion and contraction resonance of the connecting rod is suppressed by the dynamic vibration absorber provided with the spring portion 12b and the mass portions 12c and 18, and members for the purpose of fixing the dynamic vibration absorber are omitted. . Therefore, it is possible to reduce the weight of the internal combustion engine and the piston pin that are to be fixed. In the present embodiment, the spring portion 12b corresponds to an elastic body of a dynamic vibration absorber for suppressing expansion and contraction resonance of the connecting rod, and the mass portions 12c and 18 correspond to a mass body of the dynamic vibration absorber. Further, according to the present embodiment, as in the first embodiment, the space formed outside the outer peripheral surface of the spring portion 12b can be effectively utilized, and the piston boss 10a is reliably supported by the pin boss 10a. It can also be.

By the way, in Embodiment 1, since the spring part 12b and the mass part 12c are formed in the edge part of the pin main body 12a, while there exists an advantage that the structure of a dynamic vibration absorber can be simplified, value (k / m) ¹ There is a drawback that the adjustment of ^{/ 2} tends to be complicated. In this regard, according to the present embodiment, since the mass portion 18 is a separate member, the design freedom of the mass portion 18 can be increased, and the adjustment of the value (k / m) ^1/2 can be facilitated. (However, mass m = m _12c + m _18, where m _12c is the mass of the mass portion 12 c and m ₁₈ is the mass of the mass portion 18). For example, by forming the mass portion 18 from a high specific gravity material such as tungsten or copper, the value (k / m) ^1/2 can be adjusted while reducing the size of the mass portion 18. Further, the shape of the mass portion 18 can be changed according to the space on the back surface of the piston 10 and outside the pin boss 10a, and the value (k / m) ^1/2 can be adjusted.

  In the present embodiment, the total mass M of the piston 10, the piston pin 12, the mass portion 18 and the small end portion 14a and the spring constant K of the column portion 14c are acquired, and the above-described formula of the spring mass model is obtained. By substituting, the frequency at which the expansion and contraction resonance of the connecting rod occurs is specified.

  Further, as described above, the mass portion 18 has the through hole 18a communicating with the through hole 12d. If both ends of the piston pin 12 are closed by the mass portion 18, the lubricating oil rarely flows into the through hole 12d. However, if the lubricating oil once enters the through hole 12d for some reason, it cannot be discharged to the outside of the piston pin 12, affecting the function as a dynamic vibration absorber, and further affecting the movement of the piston 10. There is a possibility of effect. In this regard, according to the present embodiment, since the through hole 18a is formed, while allowing the lubricating oil to flow into the through hole 12d via the through hole 18a, the piston pin 12 is exposed to the outside. Since the discharge can be performed, the occurrence of the above-described problems can be prevented in advance.

  6 to 8 are views for explaining modifications of the internal combustion engine according to Embodiment 2 of the present invention. Each of these modified examples is a modified example related to the connection between the piston pin 12 and the mass portion 18. In the example shown in FIG. 6, the end portion of the mass portion 18 facing the end portion of the mass portion 12c has a shape corresponding to the shape of the through-hole 12d, and the end portion is press-fitted into the through-hole 12d. The portion 12c (that is, the piston pin 12) and the mass portion 18 are connected. In this example, as in the second embodiment, the mass portion 12c and the mass portion 18 correspond to a mass body of a dynamic vibration absorber for suppressing expansion and contraction resonance of the connecting rod, and the spring portion 12b serves as an elastic body of the dynamic vibration absorber. Equivalent to. In this example, as in the second embodiment, the mass portion 18 has a through hole 18a communicating with the through hole 12d. Therefore, in the example shown in FIG. 6 as well, a member only for fixing the dynamic vibration absorber can be omitted, and the lubricating oil can be discharged to the outside of the piston pin 12 through the through hole 18a.

  In the example illustrated in FIGS. 7 to 8, the spring portion 12 b fixes the mass portion 18. In the example shown in FIG. 7, the radial thickness of the spring portion 12b is reduced. Further, a groove portion 18c having a shape corresponding to the shape of the spring portion 12b is formed on the end surface of the mass portion 18 facing the end surface of the spring portion 12b, and the spring portion 12b is press-fitted into the groove portion 18c. The portion 12b (that is, the piston pin 12) and the mass portion 18 are connected. In this example, the portion of the spring portion 12b that is press-fitted into the groove portion 18c and the mass portion 18 correspond to a mass body of a dynamic vibration absorber for suppressing expansion and contraction resonance of the connecting rod. The exposed portion of the spring portion 12b corresponds to the elastic body of this dynamic vibration absorber. The exposed portion has a through hole 12e having a larger inner diameter than the through hole 12d, and a through hole 12f that connects the through hole 12e and the pin hole 10b. Therefore, in this example, the through hole 12d communicates with the outside of the piston pin 12 through the through holes 12e and 12f. Therefore, also in the example shown in FIG. 7, a member only for fixing the dynamic vibration absorber can be omitted, and the lubricating oil can be discharged to the outside of the piston pin 12 through the through holes 12e and 12f.

  In the example shown in FIG. 8, the radial thickness of the spring portion 12 b is reduced in two stages, and a thinner spring portion 12 b (hereinafter referred to as “spring portion 121 b” for convenience of description) penetrates the mass portion 18. doing. Furthermore, the protruding part from the end surface of the mass part 18 of the spring part 121b is crimped. Thereby, the spring part 12b (namely, piston pin 12) and the mass part 18 are connected. In this example, the spring portion 121b and the mass portion 18 correspond to a mass body of a dynamic vibration absorber for suppressing expansion and contraction resonance of the connecting rod. A portion of the spring portion 12b excluding the spring portion 121b (hereinafter referred to as “spring portion 122b” for convenience of explanation) corresponds to an elastic body of the dynamic vibration absorber. The spring portion 122b has a through hole 12e and a through hole 12f. Therefore, in this example, similarly to the example shown in FIG. 7, the through hole 12 d communicates with the outside of the piston pin 12 through the through holes 12 e and 12 f. Therefore, in the example shown in FIG. 8 as well, a member only for fixing the dynamic vibration absorber can be omitted, and the lubricating oil can be discharged to the outside of the piston pin 12 through the through holes 12e and 12f.

Embodiment 3 FIG.
Next, a third embodiment of the present invention will be described with reference to FIGS.
FIG. 9 is a schematic cross-sectional view around the end of the piston pin in the internal combustion engine according to Embodiment 3 of the present invention. As shown in FIG. 9, the piston pin 12 includes a pin body 12a. The point that the pin body 12a has the through hole 12d is the same as that of the first embodiment. The point that the snap ring 10c is arranged on the inner peripheral surface of the pin hole 10b is the same as that of the first embodiment.

  Unlike Embodiment 1, in this Embodiment, the mass part 18 and the spring part 20 which are connected with the pin main body 12a are integral one-piece structures, and are different members (separate members) from the pin main body 12a. The mass portion 18 is formed of a tube having a circular cross section (the cross-sectional shape of the mass portion 18 is not particularly limited), and has a through hole 18a. The spring portion 20 is formed from a tube having a circular cross section (the cross sectional shape of the spring portion 20 is not particularly limited), and has a through hole 20a communicating with the through hole 12d. A groove portion 12g having a shape corresponding to the shape of the spring portion 20 is formed in the pin body 12a, and the pin body 12a (that is, the piston pin 12) and the spring portion 20 are pressed into the groove portion 12g. Are connected. Further, a snap ring 10 c is disposed so as to face the outer peripheral surface of the spring portion 20.

  The effect by this Embodiment is demonstrated. In the present embodiment, the expansion and contraction resonance of the connecting rod is suppressed by the dynamic vibration absorber provided with the spring portion 20 and the mass portion 18, and a member only for fixing the dynamic vibration absorber is omitted. Therefore, it is possible to reduce the weight of the internal combustion engine and the piston pin that are to be fixed. In the present embodiment, the exposed portion of the spring portion 20 corresponds to an elastic body of a dynamic vibration absorber for suppressing expansion and contraction resonance of the connecting rod, and the mass portion 18 corresponds to a mass body of the dynamic vibration absorber. . FIG. 10 is an enlarged schematic view of the periphery of the spring portion 20 of FIG. As shown in FIG. 10, the opening of the groove 12g is chamfered. The exposed portion of the spring portion 20 corresponds to a portion (spring portion in the figure) located on the mass portion 18 side with respect to the chamfered portion 12h. A portion of the spring portion 20 that is located closer to the pin main body 12a than the chamfered portion 12h (a connecting portion in the figure) is integrated with the pin main body 12a and hardly functions as an elastic body. Further, according to the present embodiment, as in the first embodiment, the space formed outside the outer peripheral surface of the spring portion 12b can be effectively utilized, and the piston boss 10a is reliably supported by the pin boss 10a. It can also be.

  In the present embodiment, the total mass M of the piston 10, the pin main body 12a, the mass portion 18, the spring portion 20, and the small end portion 14a and the spring constant K of the column portion 14c are acquired, and the above-described spring mass is obtained. By substituting into the model equation, the frequency at which the expansion and contraction resonance of the connecting rod occurs is specified.

  Further, as described above, the spring portion 20 has the through hole 20a that communicates with the through hole 12d. The through hole 20 a communicates with the mass portion 18. Therefore, according to the present embodiment, it is possible to discharge the piston pin 12 to the outside while allowing the lubricating oil to flow into the through hole 12d via the through holes 18a and 20a. Occurrence of problems due to the lubricating oil flowing into the can be prevented.

  As shown in FIG. 9, in the present embodiment, the outer diameter of the spring portion 20 is made smaller than the outer diameter of the pin body 12a, and the snap ring 10c is arranged facing the outer peripheral surface of the spring portion 20. Has been. Therefore, according to the present embodiment, it is possible to effectively use the space formed outside the outer peripheral surface of the spring portion 20. Further, according to the present embodiment, as in the first embodiment, the support of the piston pin 12 by the pin boss 10a can be ensured.

Embodiment 4 FIG.
Next, a fourth embodiment of the present invention will be described with reference to FIGS.
FIG. 11 is a schematic cross-sectional view of the periphery of an end portion of a piston pin in an internal combustion engine according to Embodiment 4 of the present invention. As shown in FIG. 11, the piston pin 12 includes a pin body 12a, a spring portion 12b, and a mass portion 12c. The point that the pin body 12a, the spring part 12b, and the mass part 12c share the through-hole 12d, and the magnitude relationship of the outer diameters of the pin body 12a, the spring part 12b, and the mass part 12c are the same as in the first embodiment. . Further, the point that the snap ring 10c is arranged facing the outer peripheral surface of the spring portion 12b is the same as that of the first embodiment.

  Unlike Embodiment 1, in this Embodiment, the capacity | capacitance of the mass part 12c is made small. A mass portion 181 is provided as a separate body so as to cover the mass portion 12c. The mass portion 181 is formed of a tube having a circular cross section (the cross sectional shape of the mass portion 181 is not particularly limited), and has a through hole 24 communicating with the through hole 12d. The inner diameter of the through hole 24 is smaller than the inner diameter of the through hole 12d. A groove portion 18b having a shape corresponding to the shape of the mass portion 12c is formed on the end surface of the mass portion 181 opposed to the end surface of the mass portion 12c, and the mass portion 12c ( That is, the piston pin 12) and the mass portion 181 are connected. That is, the basic configuration of the mass portion 181 is the same as that of the mass portion 18 described in the second embodiment.

  Unlike Embodiment 2, in this Embodiment, the spring part 22 and the mass part 182 are provided in the outer side of the mass part 181 further. The spring portion 22 and the mass portion 182 are formed from a tube having a circular cross section (the cross-sectional shapes of the spring portion 22 and the mass portion 182 are not particularly limited), and the through hole 24 is shared with the mass portion 181. Further, the spring portion 22 and the mass portion 182 have a one-piece structure integrated with the mass portion 181.

  The spring portions 12b and 22 and the mass portions 12c, 181, and 182 constitute one dynamic vibration absorber as a whole. This dynamic vibration absorber is configured not only to vibrate at a frequency at which expansion and contraction resonance of the connecting rod occurs, but also to vibrate at a frequency different from this frequency. For example, a frequency in the vicinity of the frequency at which the expansion and contraction resonance of the connecting rod occurs is set as the different frequency. By setting to such a frequency, the sound pressure level can be lowered in a certain frequency range including the frequency at which expansion and contraction resonance of the connecting rod occurs.

In the present embodiment, the first spring portion (spring constant k ₂ ) and the second mass body are added to the first dynamic vibration absorber including the first spring portion (spring constant k ₁ ) and the first mass body (mass m ₁ ). A dynamic vibration absorber is expressed by a model to which a second dynamic vibration absorber made of (mass m ₂ ) is attached. This model is based on a two-degree-of-freedom system without attenuation, and the first and second mass bodies are both mass points. Further, the weight of the first and second spring portions is not taken into consideration.

式（１），（２）において、ｋ_１１＝ｋ_１＋ｋ_２であり、ｋ_２２＝ｋ_２であり、ｋ_１２＝ｋ_２１＝−ｋ_２である。 In this model, if the displacements of the first mass body and the second mass body (movement amounts from the positions where the two spring portions are balanced together) are x ₁ and x ₂ , respectively, the equations (1) and (2) The equation of motion holds.

In the equations (1) and (2), k ₁₁ = k ₁ + k ₂ , k ₂₂ = k ₂ , and k ₁₂ = k ₂₁ = −k ₂ .

Assuming that the first and second dynamic vibration absorbers are in periodic motion, the solutions x ₁ and x ₂ of equations (1) and (2) can be placed as in equation (3).

By substituting equation (3) into equations (1) and (2), equations (4) and (5) are derived.

Since the coefficient matrix of the simultaneous linear equations of Equations (4) and (5) is 0, Equation (6) is established.

Solving Equation (6) leads to Equation (7) representing the natural frequencies ω ₁ and ω ₂ as a whole of the two-degree-of-freedom system.

The spring constant k ₁ shown in Expression (7) corresponds to the spring constant of the spring portion 12 b, and the spring constant k ₂ corresponds to the spring constant of the spring portion 22. Further, the mass m ₁ shown in the formula (7) corresponds to the total mass including the mass portion 12 c and the mass portion 181, and the mass m ₂ corresponds to the mass of the mass portion 182. In the present embodiment, _{one of} the natural frequencies ω ₁ and ω ₂ shown in the equation (7) is made equal to the frequency at which the expansion / contraction resonance of the connecting rod occurs, and the other is made equal to the target frequency different from this frequency. In this way, the spring constants of the spring portions 12b and 22 and the masses of the mass portions 12c, 181, and 182 are adjusted.

  In the present embodiment, the total mass M of the piston 10, the piston pin 12, the mass portions 181, 182, the spring portion 22, and the small end portion 14a and the spring constant K of the column portion 14c are acquired and described above. By substituting into the equation of the spring mass model, the frequency at which the expansion and contraction resonance of the connecting rod occurs is specified.

  The effect by this Embodiment is demonstrated. In the present embodiment, the expansion and contraction resonance of the connecting rod is suppressed by the dynamic vibration absorber provided with the spring portions 12b and 22 and the mass portions 12c, 181 and 182, and a member intended only for fixing the dynamic vibration absorber is provided. It is omitted. Therefore, it is possible to reduce the weight of the internal combustion engine and the piston pin that are to be fixed. In this embodiment, not only the frequency at which expansion / contraction resonance of the connecting rod occurs, but also the sound pressure level at a frequency different from this frequency can be lowered. Further, according to the present embodiment, as in the first embodiment, the space formed outside the outer peripheral surface of the spring portion 12b can be effectively utilized, and the piston boss 10a is reliably supported by the pin boss 10a. It can also be.

  In the present embodiment, the spring portion 22 and the mass portion 182 are provided outside the mass portion 181. However, the mass portion 181 may have a hollow structure, and the spring portion 22 and the mass portion 182 may be accommodated in the mass portion 181. FIG. 12 is a view for explaining a modification of the internal combustion engine according to the fourth embodiment of the present invention. As shown in FIG. 12, in this modification, the mass portion 181 and the spring portion 20 connected to the pin main body 12a have an integral one-piece structure, and are different members (separate members) from the pin main body 12a. Yes. A groove portion 12g having a shape corresponding to the shape of the spring portion 20 is formed in the pin main body 12a, and the pin main body 12a and the spring portion 20 are connected by press-fitting the spring portion 20 into the groove portion 12g. Further, a snap ring 10 c is disposed so as to face the outer peripheral surface of the spring portion 20. The mass portion 181 includes a hollow portion 181a and a groove portion 181b, and the mass portion 181 and the spring portion 20 are connected by press-fitting the spring portion 22 into the groove portion 181b.

In this modification, the spring parts 20 and 22 and the mass parts 181 and 182 constitute one dynamic vibration absorber as a whole. Further, this dynamic vibration absorber is configured not only to vibrate at a frequency at which expansion and contraction resonance of the connecting rod occurs, but also to vibrate at a frequency different from this frequency. Therefore, according to this modification, not only the frequency at which the expansion / contraction resonance of the connecting rod occurs, but also the sound pressure level at a frequency different from this frequency can be lowered. In this modification, _{one of} the natural frequencies ω ₁ and ω ₂ shown in equation (7) is equal to the frequency at which the expansion and contraction resonance of the connecting rod occurs, and the other is a target frequency different from this frequency. The spring constants of the spring portions 20 and 22 and the masses of the mass portions 181 and 182 are adjusted so as to be equal. The portion of the spring portion 20 that is press-fitted into the groove portion 12g corresponds to a connecting portion between the pin main body 12a and the spring portion 20, and hardly functions as an elastic body. Further, a portion of the spring portion 22 that is press-fitted into the groove portion 181b corresponds to a connecting portion between the groove portion 181b and the spring portion 22, and hardly functions as an elastic body.

Embodiment 5. FIG.
Next, a fifth embodiment of the present invention will be described with reference to FIGS.
FIG. 13 is a schematic view around the end of the piston pin in the internal combustion engine according to the fifth embodiment of the present invention. As shown in FIG. 13, the piston pin 12 includes a pin main body 12a, a spring portion 12b, and a mass portion 12c. The point that the pin body 12a, the spring part 12b, and the mass part 12c share the through-hole 12d, and the magnitude relationship of the outer diameters of the pin body 12a, the spring part 12b, and the mass part 12c are the same as in the first embodiment. .

Unlike the first embodiment, the mass portion 12c in the present embodiment has a notched portion 12i extends to the opposite end face from the end face EF ₂ of the spring portion 12b side (i.e. the end face EF _1). The notches 12i are those formed by notching the mass portion 12c from the end face EF ₂ to the end face EF ₁ arcuately. As shown in FIG. 13, the end face EF ₃ of the mass portion 12c-side of the spring portion 12b by having a mass portion 12c is notched part 12i is partially exposed.

  The effect by this Embodiment is demonstrated with reference to FIG. FIG. 14 is a view for explaining a method of attaching the snap ring 10c. As indicated by arrows in FIG. 14, the snap ring 10c is attached simultaneously with the insertion of the piston pin 12 into the pin hole 10b. Specifically, the piston pin 12 is inserted into the pin hole 10b while the outer diameter of the snap ring 10c hung on the spring portion 12b is reduced by a jig. Thereafter, by removing the jig from the snap ring 10c at the position of the groove 10d (see FIG. 3), the snap ring 10c expands its diameter by its own elastic recovery and is introduced into the groove 10d.

Since the groove portion 10d is formed on the inner peripheral surface of the pin hole 10b, the attachment of the snap ring 10c to the groove portion 10d requires insertion of a jig up to the position of the groove portion 10d. This jig insertion is not so problematic when the outer diameter of the mass portion 12c is smaller than the inner diameter of the pin hole 10b, but it becomes more difficult when the outer diameter of the mass portion 12c is increased. In this respect, according to the present embodiment in which the mass portion 12c has the cutout portion 12i, the end face EF ₃ C is partially exposed, so that the jig can be easily inserted. Therefore, the attachment work of the snap ring 10c can be made efficient.

  By the way, in this Embodiment, the notch part 12i was formed in the mass part 12c. However, a notch portion similar to the notch portion 12i can be formed in the mass portion 18 described in the second to third embodiments and the mass portions 181 and 182 described in the fourth embodiment.

In the present embodiment, the shape of the notch 12i is an arc. However, the shape is not particularly limited as long as the notch capable of exposing the end face EF ₃ of the spring portion 12b partly by extending from the end face EF ₂ of the mass portion 12c to the end face EF _1, for example, straight It may be V-shaped, rectangular or trapezoidal.

10 piston 10a pin boss 10b pin hole 10c snap ring 10d, 12g, 18b, 18c, 181b groove 12 piston pin 12a pin body 12b, 20, 22, 121b, 122b spring 12c, 18, 181, 182 mass 12d, 12e, 12f, 14d, 14e, 18a, 20a, 24 Through hole 12h Chamfered portion 12i Notch portion 14 Connecting rod 14a Small end portion 14b Large end portion 14c Column portion 16 Bush 181a Hollow portion 30 Cylinder

Claims (14)

An internal combustion engine comprising a piston pin for connecting a piston and a connecting rod,
The piston pin includes a tubular pin body, and a dynamic vibration absorber for suppressing expansion and contraction resonance of the connecting rod accompanying combustion.
The dynamic vibration absorber is fixed to the pipe end of the pin body ,
The dynamic vibration absorber of the fixed position, the internal combustion engine, wherein a side der Rukoto of the tube end in the central axis direction of the pin body. The dynamic vibration absorber is a spring portion corresponding to an elastic body, and includes a tubular spring portion having an outer diameter smaller than the outer diameter of the tube end portion,
The outer peripheral surface of the spring portion is opposed to the inner peripheral surface of the pin hole formed in the pin boss and into which the pin body is inserted.
An annular groove portion is formed along the outer peripheral surface on the outer peripheral surface of the inner peripheral surface,
The groove portion is fitted with a snap ring having an inner diameter that is larger than the outer diameter of the spring portion and smaller than the outer diameter of the tube end portion in a state of being fitted into the groove portion. The internal combustion engine according to claim 1. The dynamic vibration absorber is a tubular mass portion corresponding to a mass body and a spring portion corresponding to an elastic body, and connects the mass portion and the tube end portion and is larger than an outer diameter of the tube end portion. A tubular spring portion having a small outer diameter,
The outer peripheral surface of the spring portion is opposed to the inner peripheral surface of the pin hole formed in the pin boss and into which the pin body is inserted.
An annular groove for providing a snap ring having an inner diameter that is larger than the outer diameter of the spring portion and smaller than the outer diameter of the tube end portion is formed on the inner peripheral surface facing the outer peripheral surface. Formed along the outer diameter of the part,
The said mass part is provided with the notch part extended from the end surface by the side of the said spring part to the surface on the other side, and exposing the end surface by the side of the said mass part of the said spring part. Internal combustion engine. The dynamic vibration absorber includes a mass portion corresponding to a mass body and a spring portion corresponding to an elastic body and connecting the mass portion and the pipe end portion,
The internal combustion engine according to any one of claims 1 to 3, wherein the mass portion is a separate member from the pin body. The spring part is a separate member from the pin body;
The internal combustion engine according to claim 4, wherein a groove portion for fitting the spring portion is formed at the pipe end portion.   The internal combustion engine according to any one of claims 1 to 3, wherein the dynamic vibration absorber has a one-piece structure integrated with the pipe end portion. The tube end is inserted into a pin hole formed in a pin boss,
The dynamic vibration absorber includes a mass portion whose end face located outside the pin hole faces the inner wall surface of the cylinder,
The internal combustion engine according to any one of claims 1 to 6, wherein a radius of curvature of an end surface of the mass portion facing the inner wall surface is equal to a radius of curvature of the inner wall surface.   8. The dynamic vibration absorber is configured to vibrate at a frequency at which the expansion / contraction resonance occurs and to vibrate at a frequency different from the frequency at which the expansion / contraction resonance occurs. The internal combustion engine described in 1. A piston pin connecting a piston and a connecting rod of an internal combustion engine,
A tubular pin body;
A dynamic vibration absorber for suppressing expansion and contraction resonance of the connecting rod accompanying combustion,
The dynamic vibration absorber is fixed to a pipe end of the pin body ;
The fixed position of the dynamic vibration reducer is, piston pin, wherein the sides der Rukoto of the tube end in the central axis direction of the pin body. The dynamic vibration absorber is a tubular mass portion corresponding to a mass body and a spring portion corresponding to an elastic body, and connects the mass portion and the tube end portion and is larger than an outer diameter of the tube end portion. A tubular spring portion having a small outer diameter,
10. The piston according to claim 9, wherein the mass portion includes a notch portion extending from an end surface on the spring portion side to a surface on the opposite side to expose the end surface on the mass portion side of the spring portion. pin. The dynamic vibration absorber includes a mass portion corresponding to a mass body and a spring portion corresponding to an elastic body and connecting the mass portion and the pipe end portion,
The piston pin according to claim 9 or 10, wherein the mass portion is a separate member from the pin body. The spring part is a separate member from the pin body;
The piston pin according to claim 11, wherein a groove portion for fitting the spring portion is formed in the pipe end portion.   The piston pin according to claim 9 or 10, wherein the dynamic vibration absorber has a one-piece structure integrated with the pipe end.   14. The dynamic vibration absorber is configured to vibrate at a frequency at which the expansion / contraction resonance occurs and to vibrate at a frequency different from the frequency at which the expansion / contraction resonance occurs. Piston pin as described in.

Images