JP2015151877A - Piston structure for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piston structure for an engine in which a piston, a piston pin, and a small end of a connecting rod are restrained from integrally resonating with a large end of the connecting rod in a combustion stroke, noise is restrained from increasing in other strokes, resonance of a crankshaft and a cylinder block is restrained from being increased relatively, and both of resonance of the piston and the connecting rod and resonance of the crankshaft or the cylinder block can be suppressed.SOLUTION: Two of dynamic vibration reducers 20X and 20Y are provided, and the one dynamic vibration reducer 20X is set so as to suppress vibration in resonance frequencies of a piston and a connecting rod, and the other dynamic vibration reducer 20Y is set so as to suppress vibration in a resonance frequency of one of a crankshaft and a cylinder block.

Description

  The present invention connects a piston that reciprocates in a cylinder, a connecting rod having a small end connected to the piston and a large end connected to a crankshaft, and the piston and the small end of the connecting rod. The present invention relates to a piston structure of an engine provided with a piston pin having a hollow cross section and a dynamic vibration absorber provided inside the piston pin.

Generally, in an engine mounted on a vehicle such as an automobile, a piston and a small end portion of a connecting rod are connected by a piston pin. Specifically, the piston pin is inserted through a pin insertion hole formed at the small end portion of the connecting rod, and the small end portion of the connecting rod is positioned at the central portion in the central axis direction of the piston pin. Two bosses are formed at both ends of the piston pin central axis direction on the back surface of the piston (the surface opposite to the top surface, that is, the surface on the anti-combustion chamber side) so as to sandwich the small end portion of the connecting rod. The two boss portions are respectively formed with pin support holes for inserting the both end portions of the piston pin in the central axis direction and supporting the both end portions (see, for example, Patent Document 1).

  In the above engine, it is known that combustion noise is generated by resonance determined by the basic structure of the engine (for example, see Non-Patent Document 1). In Non-Patent Document 1, the engine sound has three peaks of 1.7 kHz, 3.3 kHz, and 6 kHz, and one of those peaks (3.3 kHz) is due to the expansion and contraction resonance of the connecting rod, and the amplitude of the resonance It is said that there is almost no room for reduction.

JP 2004-353500 A

Masaya Otsuka, “Diesel Combustion Noise Reduction Method in Engine Structure”, Automobile Engineering Society Academic Lecture Preprints No. 36-05, Society of Automotive Engineers of Japan, May 2005, p7-10

The inventors of the present invention have intensively studied the spring mass model of the piston and the connecting rod, and as a result, have found the following.

In the spring mass model of the piston and connecting rod, the small end of the piston, piston pin, and connecting rod as a whole corresponds to the mass point (mass is defined as M (unit kg)), and the small end and large end of the connecting rod The connecting portion connecting the two corresponds to a spring (the spring constant is K (unit N / m)) that supports the mass point with respect to the large end portion. As a result, assuming that the piston, piston pin, and small end of the connecting rod are integrated, the resonance frequency is (1 / 2π) · (K / M) ^1/2 Hz with respect to the large end of the connecting rod. Resonance occurs (for example, 3 kHz to 4 kHz). This resonance corresponds to the expansion / contraction resonance of the connecting rod described in Non-Patent Document 1.

By the way, a lubricating oil film is formed between the piston pin and the pin insertion hole of the connecting rod. This lubricating oil film corresponds to a spring that connects the piston pin and the small end of the connecting rod. In addition, when a full-float assembly method that allows the piston pin to rotate with respect to both the boss and the small end of the connecting rod is adopted, it is added between the piston pin and the pin insertion hole of the connecting rod. Thus, a lubricating oil film is also formed between the piston pin and the pin support hole of the boss portion of the piston. This lubricating oil film corresponds to a spring that connects the piston pin and the piston.

If there is a lubricating oil film between the piston pin and the pin insertion hole of the connecting rod (in the full float type, the lubricating oil film and the lubricating oil film between the piston pin and the pin support hole of the boss portion of the piston), the piston The small end portion of the connecting rod is supported via a spring, and the piston, piston pin, and small end portion of the connecting rod are not integrally resonated with respect to the large end portion of the connecting rod. Except for the combustion stroke (expansion stroke), the piston is not pressed with a large force, so that the lubricating oil film exists, and thus the resonance does not occur.

On the other hand, in the combustion stroke, since the piston is pressed with a large force, the lubricating oil film disappears, and as a result, the piston, piston pin, and the small end of the connecting rod are united to resonate with the large end of the connecting rod. It will be.

From the above viewpoint, since the piston, piston pin, and connecting rod small end are integrated in the combustion stroke, it is considered to use a dynamic vibration absorber to suppress the resonance (reduce the vibration at the resonance frequency). It is done. However, by simply providing a dynamic vibration absorber, even though the noise due to the resonance can be reduced in the combustion stroke, the vibration, due to the vibration of the dynamic vibration absorber, in other strokes where the piston, piston pin and connecting rod small ends are not integrated. Noise will increase.
Therefore, it is conceivable to provide a dynamic vibration absorber inside the piston pin to suppress vibration at the resonance frequency of the piston and connecting rod in the entire stroke.

  However, when a dynamic vibration absorber that suppresses vibration at the resonance frequency of the piston and the connecting rod is provided inside the piston pin, there is an advantage that the target resonance can be suppressed, but the resonance of the crankshaft and the cylinder block does not occur. There is a problem that it becomes relatively large.

  The present invention has been made to solve the above-described problems. In the combustion stroke, the piston, piston pin, and the small end portion of the connecting rod are prevented from integrally resonating with respect to the large end portion of the connecting rod. In this process, the increase in noise can be suppressed, and the resonance of the crankshaft and cylinder block can be prevented from becoming relatively large, the resonance of the piston and connecting rod can be suppressed, and the crankshaft and cylinder block can be suppressed. It aims at providing the piston structure of the engine which can aim at coexistence with resonance suppression of this.

  The piston structure of the engine according to the present invention includes a piston that reciprocates in a cylinder, a connecting rod having a small end connected to the piston and a large end connected to a crankshaft, and a small end of the piston and the connecting rod. A piston structure of an engine provided with a piston pin having a hollow cross section for connecting parts and a dynamic vibration absorber provided inside the piston pin, wherein two dynamic vibration absorbers are provided, and one dynamic vibration absorber is provided. Is set to suppress vibration at the resonance frequency of the piston and connecting rod, and the other dynamic vibration absorber is set to suppress vibration at the resonance frequency of at least one of the crankshaft and the cylinder block. is there.

  According to the above configuration, in the combustion stroke, the lubricating oil film between the piston pin and the connecting rod (in the full float type, the lubricating oil film and the lubricating oil film between the piston pin and the piston) is lost, and the piston, the piston pin, and When the small ends of the connecting rods are integrated, the dynamic vibration absorber can prevent them from resonating together. In addition, since the dynamic vibration absorber is provided inside the piston pin, when there is a lubricating oil film between the piston pin and the connecting rod, that is, in the intake stroke, the compression stroke, and the exhaust stroke, the lubricating oil film (spring) The vibration of the vibration absorber is not transmitted to the connecting rod, and noise does not increase due to the vibration. Further, by providing a dynamic vibration absorber inside the piston pin, the space can be used effectively and the piston does not need to be large.

  Moreover, the vibration at the resonance frequency of the piston and the connecting rod is suppressed by one dynamic vibration absorber, and the vibration at the resonance frequency of at least one of the crankshaft and the cylinder block is suppressed by the other dynamic vibration absorber. Therefore, the resonance of the cylinder block can be suppressed from becoming relatively large, and the resonance suppression of the piston and the connecting rod and the resonance suppression of the crankshaft and the cylinder block can be both achieved.

  In one embodiment of the present invention, the two dynamic vibration absorbers are configured to obtain the desired resonance frequency by making the masses of the two dynamic vibration absorbers different from each other, and the moments of the two dynamic vibration absorbers are set to be approximately equal. Is.

According to the above configuration, since the moments of the two dynamic vibration absorbers are set to be approximately the same, it is possible to suppress the force in the piston pin axial direction from acting on each dynamic vibration absorber, and to the left and right of the two dynamic vibration absorbers. Can balance.
If there is a difference in moment between the two dynamic vibration absorbers, the force to move the dynamic vibration absorber outward in the piston pin axial direction with respect to the dynamic vibration absorber with the larger moment. However, in this embodiment, it is possible to suppress such a force from acting.

  In one embodiment of the present invention, the dynamic vibration absorber is fixed to the piston pin, a movable part extending in the axial direction of the piston pin, and the movable part is supported to be swingable with respect to the fixed part. And a supporting portion.

  According to the said structure, a dynamic vibration absorber can be comprised integrally.

  In one embodiment of the present invention, one of the two dynamic vibration absorbers includes a fixed portion fixed to the piston pin, and an axial direction of the piston pin via a support portion on the fixed portion. An extending shaft portion and a cap portion fixed to the outer periphery of the shaft portion, and the shaft portion and the cap portion constitute a movable portion, and the support portion is configured such that the movable portion is fixed to the fixed portion. It is supported so that it can swing.

  According to the above configuration, the frequency tuning (adjustment) can be easily performed by the cap portion fixed to the outer periphery of the shaft portion.

  In one embodiment of the present invention, the two dynamic vibration absorbers include a fixed portion fixed to the piston pin, a shaft portion extending in the axial direction of the piston pin via the support portion on the fixed portion, and the shaft A cap portion fixed to the outer periphery of the portion, and the shaft portion and the cap portion constitute a movable portion, and the support portion supports the movable portion so as to be swingable with respect to the fixed portion. Is.

  According to the above configuration, each of the two dynamic vibration absorbers includes the shaft portion and the cap portion fixed to the outer periphery of the shaft portion. Therefore, the frequency of each of the two dynamic vibration absorbers can be easily tuned. Can do.

  In one embodiment of the present invention, the dynamic vibration absorber has a fixed portion fixed to the piston pin, and the fixed portion is fixed at an offset position shifted from the axial center of the piston pin.

  According to the said structure, a dynamic vibration absorber can be arrange | positioned inside a piston pin in consideration of the length of the movable part which forms a fixed part and mass (mass, mass).

  According to the present invention, the piston, the piston pin, and the small end of the connecting rod are prevented from resonating with the large end of the connecting rod in the combustion stroke, and noise is prevented from increasing in other strokes. In addition, the resonance of the crankshaft and the cylinder block can be suppressed from becoming relatively large, and the resonance suppression of the piston and the connecting rod and the resonance suppression of the crankshaft and the cylinder block can both be achieved. effective.

The figure which shows the piston and connecting rod of the engine by which the piston structure of this invention was employ | adopted. 1 is a cross-sectional view taken along line AA in FIG. BB sectional view taken on line in FIG. 2 is an enlarged cross-sectional view of the main part Diagram showing spring mass model of piston and connecting rod Characteristic chart showing vibration of crankshaft and cylinder block and vibration of piston and connecting rod The principal part expanded sectional view which shows the other Example of the piston structure of an engine The principal part expanded sectional view which shows the further another Example of the piston structure of an engine The principal part expanded sectional view which shows the further another Example of the piston structure of an engine The principal part expanded sectional view which shows the further another Example of the piston structure of an engine The principal part expanded sectional view which shows the further another Example of the piston structure of an engine The principal part expanded sectional view which shows the further another Example of the piston structure of an engine

  In the combustion stroke, the piston, piston pin, and the small end of the connecting rod can be prevented from resonating integrally with the large end of the connecting rod, and noise can be suppressed from increasing in other strokes, The purpose of reciprocating the cylinder and cylinder block is to reduce resonance of the crankshaft and cylinder block, and to reduce resonance of the piston and connecting rod and resonance of the crankshaft and cylinder block. A connecting rod having a small end connected to the piston and a large end connected to the crankshaft, a piston pin having a hollow cross section connecting the piston and the small end of the connecting rod, and the piston pin A piston structure for an engine comprising a dynamic vibration absorber provided in the interior of the engine. Two dynamic vibration absorbers are provided, one dynamic vibration absorber is set to suppress vibration at the resonance frequency of the piston and connecting rod, and the other dynamic vibration absorber is at least at the resonance frequency of either the crankshaft or the cylinder block. This is realized by a configuration that is set so as to suppress vibration.

An embodiment of the present invention will be described in detail with reference to the drawings.
The drawing shows a piston structure of a diesel engine, FIG. 1 is a view showing a piston and a connecting rod of the engine, FIG. 3 is a cross-sectional view taken along the line B-B in FIG. 1, and FIG. .

  1 to 3, the piston 1 repeats a cylinder cycle (intake stroke, compression stroke, combustion stroke (expansion stroke), and exhaust stroke), thereby causing a cylinder axis direction (FIG. 1, FIG. 1) in the cylinder (cylinder). 2 up and down).

The piston 1 is connected via a piston pin 2 to a small end portion 10 a (so-called small end) that is one end portion of a connecting rod 10. A large end 10b (so-called large end), which is the other end of the connecting rod 10, is connected to a crankshaft (not shown). The small end portion 10a and the large end portion 10b of the connecting rod 10 are connected by a connecting portion 10c. The reciprocating motion of the piston 1 is transmitted to the crankshaft through the connecting rod 10 to rotate the crankshaft. The central axial direction of the piston pin 2 (the horizontal direction in FIG. 2) coincides with the axial direction of the crankshaft.

The small end portion 10a of the connecting rod 10 is formed with a pin insertion hole 10d through which the piston pin 2 is inserted, and the large end portion 10b of the connecting rod 10 is formed with a shaft insertion hole 10e through which the crankshaft is inserted. Yes. Although not shown in FIG. 1, the large end portion 10b of the connecting rod 10 is divided into two at the center of the shaft insertion hole 10e in the longitudinal direction of the connecting portion 10c.

As shown in FIGS. 2 and 3, the piston pin 2 is inserted into the pin insertion hole 10 d in the small end portion 10 a of the connecting rod 10, and the small end portion 10 a of the connecting rod 10 is the center in the central axis direction of the piston pin 2. Located in the department. Further, the small end portion 10 a of the connecting rod 10 is located at the center of the piston 1 in the central axis direction of the piston pin 2.

The piston pin 2 is rotatably inserted into the pin insertion hole 10 d of the connecting rod 10. A bush 11 is fixed to the inner peripheral surface of the pin insertion hole 10d of the connecting rod 10, and strictly speaking, the piston pin 2 is rotatably inserted into the bush 11.

  A lubricating oil film is formed between the piston pin 2 and the pin insertion hole 10d (specifically, the bush 11) of the connecting rod 10 by supplying lubricating oil circulated in the engine. With the bush 11, the piston pin 2 rotates smoothly with respect to the pin insertion hole 10 d of the connecting rod 10.

As shown in FIG. 2, a cavity 1 a is formed on the top surface (piston head) of the piston 1, and a top ring groove 1 b, a second ring groove 1 c, and an oil ring groove 1 d are formed on the land portion of the piston 1. At the same time, a cooling channel 1 e is formed in the piston 1.
As shown in FIG. 1, a top ring 12, a second ring 13, and an oil ring 14 are mounted in the ring grooves 1b, 1c, and 1d, respectively.

Two boss portions 1f sandwich the small end portion 10a of the connecting rod 10 from both sides at both ends in the central axis direction of the piston pin 2 on the back surface of the piston 1 (the surface opposite to the top surface, that is, the anti-combustion chamber side). As described above, the bulge is formed on the crankshaft side. These two boss portions 1 f are respectively formed with pin support holes 1 g extending in the central axis direction of the piston pin 2. Both end portions in the central axis direction of the piston pin 2 are inserted into and supported by the pin support holes 1g of the two boss portions 1f.

In this embodiment, a full float type is adopted as an assembly method of the piston pin 2. That is, the piston pin 2 can be rotated with respect to the pin insertion hole 10 d of the connecting rod 10, and can also be rotated with respect to the pin support hole 1 g of the boss portion 1 f of the piston 1.

A lubricating oil film is also formed between the piston pin 2 and the pin support hole 1g of the boss portion 1f of the piston 1 in the same manner as between the piston pin 2 and the pin insertion hole 10d of the connecting rod 10. The pin 2 rotates smoothly with respect to the pin support hole 1g of the boss 1f of the piston 1.

A circlip 15 is inserted and fixed to each end of the pin 1 in the pin support hole 1g of the two boss portions 1f on the outer peripheral surface side of the piston 1, and the two circlips 15 are both fixed in the direction of the central axis of the piston pin 2. Positioned so as to be in contact with the outer end surfaces, respectively, the movement of the piston pin 2 in the central axis direction is restricted.

The piston pin 2 is hollow in cross section, and a through-hole 2 a extending in the central axis direction of the piston pin 2 is formed at the radial center of the piston pin 2. A press-fitting in which a fixed portion 20a of dynamic vibration absorbers 20X and 20Y, which will be described later, is press-fitted into the central portion of the inner peripheral surface of the through hole 2a in the central axis direction of the piston pin 2 (that is, the central portion in the longitudinal direction of the piston pin 2). A portion 2b is provided. The inner diameter of the through hole 2a in the press-fit portion 2b is set smaller than the inner diameter of the through hole 2a in the other part.

Specifically, the through-hole 2a is located in the central portion of the piston pin 2 in the central axis direction, is connected to the press-fit portion 2b formed in a small diameter cylindrical shape, and both sides of the press-fit portion 2b, and the central axis of the piston pin 2 It has the accommodating part 2c formed in the cylindrical shape of a large diameter located in the both ends of a direction.

A stepped surface 2d facing the central axis direction of the piston pin 2 is formed by a step between the press-fitting portion 2b and the accommodating portion 2c. By making the press-fitting portion 2b have a small diameter, the rigidity of the piston pin 2 can be improved.

  In the inside of the piston pin 2 (in the through hole 2a), the piston 1, the piston pin 2, and the small end portion 10a of the connecting rod 10 are integrally prevented from resonating with the large end portion 10b of the connecting rod 10 in the combustion stroke. Two dynamic vibration absorbers 20X and 20Y (which are so-called dynamic dampers, hereinafter simply abbreviated as dampers) are disposed. As shown in FIG. 4, these two dampers 20X and 20Y pass through the center of the piston pin 2 in the central axis direction, and are positioned on both sides of the plane perpendicular to the central axis of the piston pin 2. doing.

Here, the spring mass model of the piston 1 and the connecting rod 10 is as shown in FIG. That is, the piston 1, the piston pin 2, and the small end portion 10a of the connecting rod 10 as a whole correspond to a mass point (mass is defined as M (unit kg)), and the connecting portion 10c of the connecting rod 10 determines the mass point of the connecting rod 10 This corresponds to a spring (the spring constant is K (unit N / m)) supported with respect to the large end portion 10b.

The lubricating oil film between the piston pin 2 and the pin insertion hole 10d of the connecting rod 10 corresponds to a spring that connects the piston pin 2 and the small end portion 10a of the connecting rod 10, and the piston pin 2 and the boss portion 1f of the piston 1 The lubricating oil film between the pin support hole 1g corresponds to a spring connecting the piston pin 2 and the piston 1 (boss portion 1f).

In the combustion stroke, since the piston 1 is pressed with a large force, a lubricating oil film between the piston pin 2 and the pin insertion hole 10d of the connecting rod 10 (a spring connecting the piston pin 2 and the small end portion 10a of the connecting rod 10). , And the lubricating oil film (spring connecting the piston pin 2 and the piston 1) between the piston pin 2 and the pin support hole 1g of the boss 1f of the piston 1 is lost. As a result, the piston 1 and the piston pin 2 And the small end part 10a of the connecting rod 10 is united. As a result, the piston 1, the piston pin 2, and the small end portion 10a of the connecting rod 10 are integrated with the large end portion 10b of the connecting rod 10 at a resonance frequency of (1 / 2π) · (K / M) ^1/2 Hz. It will resonate. In order to suppress this resonance and resonance of at least one of the crankshaft and the cylinder block (reducing vibration at the resonance frequency), the two dampers 20X and 20Y are disposed inside the piston pin 2 (in the through hole 2a). ).

  As shown in FIGS. 2 to 4, each of the dampers 20 </ b> X and 20 </ b> Y includes a fixed portion 20 a that is fixed to a press-fit portion 2 b provided on the inner peripheral surface of the through hole 2 a of the piston pin 2, and an inside of the piston pin 2. A movable portion 20b extending in the central axis direction of the piston pin 2 and a support portion 20c that supports the movable portion 20b so as to vibrate in the radial direction of the piston pin 2 with respect to the fixed portion 20a.

In this embodiment, two dampers 20X and 20Y are integrally formed from the viewpoint of reducing the number of parts. In the left damper 20X shown in the figure, a fixed part 20a, a movable part 20b, and a support part 20c are integrally formed (integrated damper), and the right damper 20Y is formed by assembling a plurality of members. It is an assembly type damper (assembly type damper).

The damper 20X and the damper 20Y are integrally connected by respective fixing portions 20a. The integrated fixing part 20a is press-fitted and fixed in the press-fitting part 2b. Thereby, the movable part 20b of the damper 20X on the left side in the figure is accommodated in one accommodating part 2c, and the movable part 20b in the damper 20Y on the right side in the figure is accommodated in the other accommodating part 2c.

The movable portion 20b is formed in a substantially cylindrical shape, and the outer diameter thereof is smaller than the inner diameter of the housing portion 2c so that it does not contact the inner peripheral surface of the housing portion 2c even when the movable portion 20b vibrates. The dimensions are designed. Thus, the movable portion 20b is disposed inside the accommodating portion 2c so that the outer peripheral surface of the movable portion 20b is opposed to the inner peripheral surface of the accommodating portion 2c with a slight gap therebetween.
Further, each of the above-described dampers 20 and 20 is provided with a regulating means for mechanically regulating the axial movement thereof.

  That is, the damper 20X on the left side in FIG. 4 has a larger outer diameter D5 on the support portion 20c side of the movable portion 20b than the inner diameter D4 of the minimum diameter portion of the step surface 2d of the piston pin 2 (D5> D4). In this way, the restricting means 30 is configured to prevent the damper 20X from being removed.

In FIG. 4, a damper 20Y on the right side of the figure is integrally formed with a support portion 20c with a shaft portion 20d extending from the support portion 20c in the piston pin axial direction, and a cap portion 40 as a mass adjusting member is fixed to the outer periphery of the shaft portion 20d. The shaft portion 20d and the cap portion 40 described above form a movable portion 20b.
Further, the shaft portion 20d described above is directed from the support portion 20c side toward the outer end side, the first shaft portion 21 having an outer diameter D3, the second shaft portion 22 having an outer diameter D1, and the second shaft portion 22 having an outer diameter D2. The three shaft portions 23 and the fourth shaft portion 24 having an outer diameter of DO are integrally formed in this order, and the outer diameter dimensions of the shaft portions 21 to 24 are set so that the relational expression of DO <D1 <D2 <D3 is satisfied. It is set.

A step surface 25 is formed at the end of the fourth shaft portion 24 on the support portion 20 c side, and the inner side is large between the radially outer end of the step surface 25 and the third shaft portion 23. A tapered portion 26 having a small diameter on the outside is formed.
The cap portion 40 is formed in a two-stage cylindrical shape in which a press-fit portion 41 located on the front end side in the press-fit direction and a neck portion 42 loosely fitted on the outer periphery of the fourth shaft portion 24 are integrally formed. A stopper portion 44 is formed between the cylindrical portion 43 having the same inner and outer diameter as the inner and outer diameters of the portion 41 and the neck portion 42, and the stopper portion 44 comes into contact with the step surface 25 when the cap portion 40 is press-fitted. , Configured to complete the press-fitting.

Further, a clearance in units of microns is formed between the inner diameter portion of the cylindrical portion 43 of the cap portion 40 and the outer diameter portion of the third shaft portion 23 in the shaft portion 20d.
Thus, the outer diameter D6 of the cap portion 40 (outer diameter of the movable portion 20b) is made larger than the inner diameter D4 of the minimum diameter portion of the stepped surface 2d of the piston pin 2 (D6> D4), thereby restricting. The means 31 is configured to prevent the damper 20Y from being removed.

  By the way, the support part 20c is formed in a substantially columnar shape, and is interposed between the movable part 20b and the fixed part 20a. The outer diameter of the support portion 20c is smaller than the outer diameter of the movable portion 20b and the inner diameter of the press-fit portion 2b, and can be inserted into the press-fit portion 2b.

Thus, the support portion 20c is disposed inside the press-fit portion 2b so that the outer peripheral surface of the support portion 20c faces the inner peripheral surface of the press-fit portion 2b with a sufficient gap. Thereby, the support part 20c supports the movable part 20b so that it can vibrate in the radial direction of the piston pin 2 with respect to the fixed part 20a.

The fixed portion 20a is also formed in a columnar shape. The outer diameter of the fixed portion 20a is smaller than the outer diameter of the movable portion 20b, but is slightly larger than the inner diameter of the press-fit portion 2b. Thereby, the fixing part 20a can be press-fitted into the press-fitting part 2b. The fixed portion 20a, the movable portion 20b, and the support portion 20c are connected in series in a state where the central axes are matched.

The central axis of the damper 20X and the central axis of the damper 20Y are arranged so as to coincide with the central axis of the piston pin 2. The center of gravity of the movable portion 20b of the two dampers 20X and 20Y is located on the central axis of the piston pin 2 and passes through the center in the direction of the central axis of the piston pin 2 (through the center and the piston (Planes perpendicular to the central axis of the pin 2) are located symmetrically to each other.

  In FIG. 6, the horizontal axis represents frequency, the vertical axis represents sound pressure, vibrations of at least one of the crankshaft and the cylinder block (resonance frequencies are f1 and f2), the piston 1 and the connecting rod 10 FIG. 5 is a characteristic diagram showing vibration (resonance frequency is f3), where the frequency f3 at which the piston 1 and the connecting rod 10 vibrate is relatively high, and the frequencies f1, f2 at which the crankshaft and cylinder block vibrate are relatively high. It turns out that it is low.

  Therefore, in this embodiment, one damper 20X is set so as to suppress vibration at the resonance frequency f3 of the piston 1 and the connecting rod 10, and the other damper 20Y is set to at least the resonance frequency of either the crankshaft or the cylinder block. It is set to suppress vibrations at f1 and f2.

  Since the resonance frequency is inversely proportional to the mass of the movable part 20b, the mass of the damper 20X may be set relatively small with respect to the mass of the damper 20Y. In other words, the mass of the damper 20Y may be set relatively large with respect to the mass of the damper 20X.

  For example, carbon steel (although there is a difference depending on the carbon content, the specific gravity of the material of the member in which the fixed portion 20a, the support portion 20c, and the shaft portion 20d of the one damper 20X and the other damper 20Y are integrally formed may be selected. Is approximately 7.812 to 7.85), and the material of the cap portion 40 is a material having a specific gravity greater than that of carbon steel (for example, lead having a specific gravity of 11.4 or a copper alloy having a specific gravity of about 8.9), The two dampers 20X and 20Y are configured so as to obtain the desired resonance frequencies f1, f2, and f3 by making the masses of the two dampers 20X and 20Y different from each other.

The support portion 20c of each damper 20X, 20Y corresponds to a spring that supports the movable portion 20b (the mass of the movable portion 20b is m (unit kg)), and its spring constant is k (unit N / m). In order to suppress the resonance, basically, the value of k / m may be configured to be substantially the same as K / M. The length and diameter of the movable portion 20b and the length and diameter of the support portion 20c are set so that such a value of k / m can be obtained. Strictly speaking, it is necessary to consider the mass of the support portion 20c, but the mass of the support portion 20c can be ignored because the mass of the support portion 20c is considerably smaller than the mass of the movable portion 20b.
As described above, in the combustion stroke, the lubricating oil film (the spring connecting the piston pin 2 and the small end portion 10a of the connecting rod 10) between the piston pin 2 and the pin insertion hole 10d of the connecting rod 10, and the piston pin 2 And the lubricating oil film (spring connecting the piston pin 2 and the piston 1) between the pin supporting hole 1g of the boss portion 1f of the piston 1 is lost, and as a result, the piston 1, the piston pin 2 and the connecting rod 10 are small. The end portion 10d is united to resonate with the large end portion 10b. However, in this embodiment, the resonance is suppressed by the damper 20X provided on the piston pin 2, and noise due to the resonance can be reduced.

  On the other hand, in the intake stroke, the compression stroke, and the exhaust stroke, respectively, between the piston pin 2 and the pin insertion hole 10d of the connecting rod 10, and between the piston pin 2 and the pin support hole 1g of the boss portion 1f of the piston 1, respectively. Lubricating oil film exists. As a result, resonance that occurs in the combustion stroke does not occur. If the damper is provided at the small end of the connecting rod, the above-described resonance can be suppressed in the combustion stroke, but the damper vibrates also in the intake stroke, the compression stroke, and the exhaust stroke where no resonance occurs. For this reason, in the intake stroke, the compression stroke, and the exhaust stroke, noise is increased due to the vibration of the damper. However, in this embodiment, since the damper 20X is provided on the piston pin 2, a lubricating oil film (piston pin) between the piston pin 2 and the pin insertion hole 10d of the connecting rod 10 in the intake stroke, the compression stroke, and the exhaust stroke. 2) and the small end 10a of the connecting rod 10), the vibration of the damper 20X is not transmitted to the connecting rod 10, and the noise does not increase. Further, by providing the damper 20X and the damper 20Y inside the piston pin 2, the space can be used effectively, and the piston 1 does not have to be enlarged.

  As described above, the piston structure of the engine of the first embodiment shown in FIGS. 1 to 5 includes the piston 1 that reciprocates in the cylinder, the small end portion 10a connected to the piston 1, and the large end portion 10b. A connecting rod 10 connected to the crankshaft, a piston pin 2 having a hollow cross section connecting the piston 1 and the small end 10a of the connecting rod 10, and dampers 20X and 20Y provided inside the piston pin 2, The two pistons 20X and 20Y are provided, and one damper 20X is set so as to suppress vibration at the resonance frequency f3 of the piston 1 and the connecting rod 10, and the other damper is provided. 20Y is set so as to suppress vibration at least at the resonance frequencies f1 and f2 of either the crankshaft or the cylinder block. Than is (1, 2, see Fig. 4).

  According to this configuration, the lubricating oil film between the piston pin 2 and the connecting rod 10 (in the full float type, the lubricating oil film and the lubricating oil film between the piston pin 2 and the piston 1) disappears in the combustion stroke. When the piston 1, the piston pin 2, and the small end portion 10a of the connecting rod 10 are integrated, the damper 20X can prevent them from resonating together. Further, since the damper 20X is provided inside the piston pin, when a lubricating oil film exists between the piston pin 2 and the connecting rod 10, that is, in the intake stroke, the compression stroke, and the exhaust stroke, the lubricating oil film (spring) The vibration of the damper 20X is not transmitted to the connecting rod 10, and the noise does not increase due to the vibration. Further, by providing the dampers 20X and 20Y inside the piston pin 2, space can be used effectively, and the piston 1 does not need to be large.

  Moreover, the vibration at the resonance frequency f3 of the piston 1 and the connecting rod 10 is suppressed by one damper 20X, and the vibration at at least one of the resonance frequencies f1 and f2 of the crankshaft and the cylinder block is suppressed by the other damper 20Y. Therefore, it can suppress that the resonance of a crankshaft and a cylinder block becomes comparatively large, and can aim at coexistence with resonance suppression of the piston 1 and the connecting rod 10, and resonance suppression of a crankshaft and a cylinder block.

  In one embodiment of the present invention, the damper 20X is fixed to the piston pin 2, a fixed portion 20a, a movable portion 20b extending in the axial direction of the piston pin 2, and the movable portion 20b with respect to the fixed portion 20a. And a support portion 20c that is swingably supported (see FIG. 4).

  According to this configuration, the damper 20X can be configured integrally.

  In one embodiment of the present invention, one of the two dampers 20X and 20Y includes a fixed part 20a fixed to the piston pin 2, and a piston pin connected to the fixed part 20a via a support part 20c. 2, a shaft portion 20 d extending in the axial direction, and a cap portion 40 fixed to the outer periphery of the shaft portion 20 d, and the shaft portion 20 d and the cap portion 40 constitute a movable portion 20 b, and the support portion 20c supports the movable part 20b so as to be swingable with respect to the fixed part 20a (see FIG. 4).

  According to this configuration, the frequency tuning (adjustment) can be easily performed by the cap portion 40 fixed to the outer periphery of the shaft portion 20d.

FIG. 7 is an enlarged cross-sectional view of an essential part showing another embodiment of the piston structure of the engine, in which one damper 20X is set so as to suppress vibration at the resonance frequency f3 of the piston 1 and the connecting rod 10, and the other When the damper 20Y is set so as to suppress vibrations at least at the resonance frequencies f1 and f2 of either the crankshaft or the cylinder block, the outer diameter of the movable portion 20b of the damper 20X on the left side of the figure is set to the damper 20Y on the right side of the figure. The outer diameter D3 is set equal to or smaller than the outer diameter D3.
In the second embodiment, the material of the cap portion 40 in each of the dampers 20X and 20Y and the damper 20Y on the right side of the figure is set to be the same (for example, carbon steel having a specific gravity of approximately 7.812 to 7.85). Yes.

  Even if comprised in this way, it is possible to achieve both the suppression of the resonance of the piston 1 and the connecting rod 10 and the suppression of the resonance of the crankshaft and the cylinder block as in the first embodiment.

  In the second embodiment shown in FIG. 7 as well, the other configurations, operations, and effects are almost the same as those of the previous embodiment. Therefore, in FIG. Detailed description thereof will be omitted.

FIG. 8 is an enlarged cross-sectional view of a main part showing still another embodiment of the piston structure of the engine.
In the third embodiment, the press-fitting portion 2b of the piston pin 2 is formed at a position shifted to the right side in the drawing, and the fixing portion 20a of the two dampers 20X and 20Y is moved from the axial center CL1 of the piston pin 2 to the right side in the drawing. The offset position is fixed.
That is, when the axial center of the fixed portion 20a is CL2, the axial center CL2 is shifted from the axial center CL1 of the piston pin 2 by the offset amount OS to the right in the figure. The fixed portion 20 a is press-fitted and fixed to the press-fit portion 2 b of the piston pin 2.

  In addition, one damper 20X is set so as to suppress vibration at the resonance frequency f3 of the piston 1 and the connecting rod 10, and the other damper 20Y is set at at least one of the resonance frequencies f1 and f2 of the crankshaft and the cylinder block. In the case of setting so as to suppress vibration, in this third embodiment, the respective masses of the two dampers 20X and 20Y, more specifically, the masses of the cylindrical movable parts 20b and 20b are made different from each other, and the intended resonance frequency f1. , F2 and f3.

Here, the diameters (outer diameters) of the movable portions 20b and 20b of the damper 20X and the damper 20Y are set to be the same or substantially the same, and the axial length WX of the movable portion 20b of the damper 20X is set to the value of the damper 20Y. The axial length WY of the movable portion 20b is set shorter (WX <WY), and the mass mX of the movable portion 20b of the damper 20X is set smaller than the mass mY of the movable portion 20b of the damper 20Y (mX <mY). )doing.
Furthermore, the moments of the two dampers 20X and 20Y are set to be approximately equal.

  That is, the center of gravity of the movable part 20b of the damper 20X is set to GX, the center of gravity of the movable part 20b of the damper 20Y is set to GY, and the distances from the center CL2 in the axial direction of the fixed part 20a to the respective centers of gravity GX and GY are L2, L1. When setting, the separation distance L2 on the damper 20X side is set to be longer than the separation distance L1 on the damper 20Y side (L2> L1), and the product (mX) of the mass mX that is the moment on the damper 20X side and the separation distance L2 L2) is configured such that the product (mY · L1) of the mass mY, which is the moment on the damper 20Y side, and the separation distance L1 is substantially equal.

Further, the outer diameter Dx of the cylindrical support portion 20c on the damper 20X side is set larger than the outer diameter Dy of the cylindrical support portion 20c on the damper 20Y side (Dx> Dy), and the spring constant on the damper 20X side is set. k is set larger than the spring constant k on the damper 20Y side. The vibration at the resonance frequency f3 of the piston 1 and the connecting rod 10 is suppressed by the damper 20X by the frequency indicated by (1 / 2π) · (K / M) ^1/2 [Hz], and at least the crankshaft is at the damper 20Y. Further, it is configured to suppress vibrations at either one of the resonance frequencies f1 and f2 of the cylinder block.

  As described above, in the third embodiment shown in FIG. 8, the two dampers 20X and 20Y have different masses mX and mY to obtain the desired resonance frequency, and the two dampers. The moments 20X and 20Y are set substantially equal (mX · L2≈mY · L1) (see FIG. 8).

According to this configuration, since the moments of the two dampers 20X and 20Y are set to be substantially the same, the force in the piston pin axial direction is prevented from acting on the dampers 20X and 20Y, and the two dampers 20X and 20Y 20Y can be balanced on the left and right.
If there is a moment difference between the two dampers, the force that moves the damper outward in the piston pin axial direction acts on the damper with the larger moment. In Example 3, it can suppress that such force acts.

  The dampers 20X and 20Y have a fixing portion 20a fixed to the piston pin 2, and the fixing portion 20a is fixed at an offset position (refer to CL2) that is shifted from the axial center CL1 of the piston pin 2. (See FIG. 8).

  According to this configuration, the dampers 20X and 20Y are disposed inside the piston pin 2 in consideration of the fixed portion 20a and the length (see L1 and L2) of the movable portion 20b that forms a mass. be able to.

  Also in the third embodiment shown in FIG. 8, the other configurations, operations, and effects are almost the same as those of the previous embodiment. Therefore, in FIG. Detailed description thereof will be omitted.

FIG. 9 is an enlarged sectional view of an essential part showing still another embodiment of the piston structure of the engine.
In the fourth embodiment shown in FIG. 9, two dampers 20X and 20Y are provided, and a shaft portion 20d extending in the piston pin axial direction from the support portion 20c is formed integrally with the support portion 20c of the damper 20Y on the right side in the figure. The cap portion 40 is fixed to the outer periphery of the shaft portion 20d, the movable portion 20b is formed by the shaft portion 20d and the cap portion 40, and the regulating means 30 and 35 are provided with a small diameter portion of the piston pin 2 for fixing the fixing portion 20a. And the large-diameter portion of the movable portion 20b (the outer-diameter portion of the cap portion 40 on the right side).

The cap portion 40 is formed in a cylindrical shape having press-fit portions 44 and 45 at the front end side and the rear end side in the press-fit direction, and the shaft portion 20d between the press-fit portions 44 and 45 is the cap portion 40. A gap 46 is formed between the portion formed in this small diameter and the inner peripheral surface of the cap portion 40 between the press-fit portions 44 and 45.
Further, the outer end of the cap portion 40 in the axial direction is fixed and secured by a locking ring 36 such as a C-shaped clip attached to the corresponding position of the shaft portion 20d.

  Then, the dampers 20X and 20Y are formed by both the stepped surface 2d in the small-diameter portion of the piston pin 2 and the large-diameter portion of the movable portion 20b (that is, the outer-diameter portion of the cap portion 40 on the right side) (that is, the regulating means 30, 35). The cap part 40 is configured to facilitate the mass adjustment while achieving the retaining.

  Moreover, also in the fourth embodiment, one damper 20X is set so as to suppress vibration at the resonance frequency f3 of the piston 1 and the connecting rod 10, and the other damper 20Y is at least one of the crankshaft and the cylinder block. The vibration is set to be suppressed at the resonance frequencies f1 and f2.

  In the fourth embodiment, the fixed portion 20a, the support portion 20c, and the shaft portion 20d of the one damper 20X and the other damper 20Y are formed of carbon steel having a specific gravity of approximately 7.812 to 7.85, and the cap portion 40 Is made of a material having a specific gravity greater than that of carbon steel (for example, lead having a specific gravity of 11.4 or a copper alloy having a specific gravity of about 8.9), and the masses of the two dampers 20X and 20Y are made different from each other. The frequencies f1, f2, and f3 are obtained.

  In the fourth embodiment, both the resonance suppression of the piston 1 and the connecting rod 10 and the resonance suppression of the crankshaft and the cylinder block can be achieved. In the fourth embodiment shown in FIG. 9 as well, the other configurations, operations, and effects are almost the same as those of the previous embodiment. Therefore, in FIG. Detailed description thereof will be omitted.

FIG. 10 is an enlarged cross-sectional view of a main part showing still another embodiment of the piston structure of the engine.
In the fourth embodiment shown in FIG. 9, the right side in the figure with the fixing part 20a separated is the assembled damper 20Y, and the left side in the figure with the fixing part 20a separated is the integrated damper 20X. In the fifth embodiment, the left and right sides shown in the drawing with the fixing portion 20a separated from each other are assembled dampers 20X and 20Y equivalent to the configuration on the right side in FIG.

  That is, in the fifth embodiment shown in FIG. 10, two dampers 20X and 20Y are provided, and the support portions 20c of the two dampers 20X and 20Y have shaft portions extending from the support portions 20c in the axial direction of the piston pin 2. 20d is provided, and the cap portion 40 is fixed to the outer periphery of the shaft portion 20d, and the movable portion 20b is formed by the shaft portion 20d and the cap portion 40, and the restricting means 35 is fixed to the fixing portion 20a. It consists of a small-diameter portion (see step surface 2d) of the piston pin 2 to be fixed and a large-diameter portion of the movable portion 20b (see the outer diameter portion of the cap portion 40).

  Moreover, also in the fifth embodiment, one damper 20X is set so as to suppress vibration at the resonance frequency f3 of the piston 1 and the connecting rod 10, and the other damper 20Y is set to at least one of the crankshaft and the cylinder block. The vibration is set to be suppressed at the resonance frequencies f1 and f2.

  In this embodiment, the cap portion 40 on one damper 20X side is made of carbon steel having a specific gravity of approximately 7.812 to 7.85, and the cap portion 40 on the other damper 20Y side has a specific gravity larger than that of carbon steel. The material (for example, lead having a specific gravity of 11.4 or a copper alloy having a specific gravity of about 8.9), and the fixed portions 20a, support portions 20c, and shaft portions 20d of the dampers 20X and 20Y other than the cap portions 40 and 40 are used. Are integrally formed of the same material so that the respective masses of the two dampers 20X and 20Y are made different to obtain the desired resonance frequencies f1, f2, and f3.

  In the fifth embodiment, both the resonance suppression of the piston 1 and the connecting rod 10 and the resonance suppression of the crankshaft and the cylinder block can be achieved.

  Further, in the fifth embodiment, the two dampers 20X and 20Y extend in the axial direction of the piston pin 2 through the fixing portion 20a fixed to the piston pin 2 and the fixing portion 20a via the support portion 20c. A shaft portion 20d and a cap portion 40 fixed to the outer periphery of the shaft portion 20d. The shaft portion 20d and the cap portion 40 constitute a movable portion 20b, and the support portion 20c includes the movable portion. 20b is supported so as to be swingable with respect to the fixed portion 20a (see FIG. 10).

  According to this configuration, each of the two dampers 20X and 20Y includes the shaft portion 20d and the cap portion 40 fixed to the outer periphery of the shaft portion 20d. Therefore, frequency tuning for each of the two dampers 20X and 20Y is performed. Can be easily performed.

  In the fifth embodiment shown in FIG. 10 as well, the other configurations, operations, and effects are almost the same as those of the previous embodiment. Therefore, in FIG. Detailed description thereof will be omitted.

FIG. 11 is an enlarged cross-sectional view of a main part showing still another embodiment of the piston structure of the engine.
In FIG. 11, the damper 20X on the left side of the figure is an integrated type, and the damper 20X has an outer diameter D11 on the support portion 20c side of the movable portion 20b with respect to the inner diameter D9 of the smallest diameter portion of the stepped surface 2d of the piston pin 2. Is largely formed (D11> D9), and thereby the restricting means 30 is configured.

In FIG. 11, the damper 20Y on the right side of the figure is an assembly type, and the damper 20Y is integrally formed with a support portion 20c and a shaft portion 20d extending in the piston pin axial direction from the support portion 20c. The cap part 40 as an adjusting member is fixed, and the movable part 20b is formed by the shaft part 20d and the cap part 40 described above.
Further, the above-described shaft portion 20d integrally forms a first shaft portion 27 having an outer diameter D8 and a second shaft portion 28 having an outer diameter D7 in this order from the support portion 20c side toward the outer end side. The outer diameter dimensions of the shaft portions 27 and 28 are set so that the relational expression D8> D7 is satisfied.

A step surface 25 is formed at the end of the second shaft portion 28 on the support portion 20 c side, and the inner side is large between the radially outer end of the step surface 25 and the first shaft portion 27. A tapered portion 26 having a small diameter on the outside is formed.
The cap portion 40 described above is formed in a two-stage cylindrical shape in which a press-fit portion 41 that extends over substantially the entire axial length of the first shaft portion 27 and a neck portion 42 that is loosely fitted to the outer periphery of the second shaft portion 28 are integrally formed. A stopper portion 44 is formed between the cylindrical portion 43 having the same inner and outer diameters as the inner and outer diameters of the press-fit portion 41 and the neck portion 42. When the cap portion 40 is press-fitted, the stopper portion 44 becomes the stepped surface 25. Is configured to complete the press-fitting.

Thus, the outer diameter D10 of the cap portion 40 (outer diameter of the movable portion 20b) is formed larger than the inner diameter D9 of the minimum diameter portion of the step surface 2d of the piston pin 2 (D10> D9), thereby restricting. Means 31 are configured.
Then, the restricting means 30 and 31 restrict the release of the dampers 20X and 20Y inside the piston pin 2 from coming off and secure the function of preventing the dampers 20X and 20Y.

  Moreover, also in the sixth embodiment, one damper 20X is set so as to suppress the vibration at the resonance frequency f3 of the piston 1 and the connecting rod 10, and the other damper 20Y is at least one of the crankshaft and the cylinder block. The vibration is set to be suppressed at the resonance frequencies f1 and f2.

  In the sixth embodiment, the fixed portion 20a, the support portion 20c, and the shaft portion 20d of one damper 20X and the other damper 20Y are formed of carbon steel having a specific gravity of approximately 7.812 to 7.85, and the cap portion 40 Is made of a material having a specific gravity greater than that of carbon steel (for example, lead having a specific gravity of 11.4 or a copper alloy having a specific gravity of about 8.9), and the masses of the two dampers 20X and 20Y are made different from each other. The frequencies f1, f2, and f3 are obtained.

  Also in the sixth embodiment, it is possible to achieve both suppression of the resonance of the piston 1 and the connecting rod 10 and suppression of the resonance of the crankshaft and the cylinder block. In the sixth embodiment shown in FIG. 11 as well, the other configurations, operations, and effects are almost the same as those of the previous embodiment. Therefore, in FIG. Detailed description thereof will be omitted.

  FIG. 12 is an enlarged cross-sectional view of a main part showing still another embodiment of the piston structure of the engine.

  In the sixth embodiment shown in FIG. 11, the right side in the drawing with the fixing portion 20a separated is the assembled damper 20Y, and the left side in the drawing with the fixing portion 20a separated is the integrated damper 20X. In the seventh embodiment, the left and right sides shown in the drawing with the fixing portion 20a separated from each other are assembled dampers 20X and 20Y equivalent to the configuration on the right side in FIG. Therefore, the dampers 20X and 20Y in the piston pin 2 are prevented from being fixed and removed, and the retaining function of the dampers 20X and 20Y is secured.

  Moreover, also in the seventh embodiment, one damper 20X is set so as to suppress vibration at the resonance frequency f3 of the piston 1 and the connecting rod 10, and the other damper 20Y is at least one of the crankshaft and the cylinder block. The vibration is set to be suppressed at the resonance frequencies f1 and f2.

  In this embodiment, the cap portion 40 on one damper 20X side is made of carbon steel having a specific gravity of approximately 7.812 to 7.85, and the cap portion 40 on the other damper 20Y side is made of a material having a large specific gravity (for example, Lead having a specific gravity of 11.4 or a copper alloy having a specific gravity of about 8.9), and the fixed portions 20a, support portions 20c, and shaft portions 20d of the dampers 20X and 20Y other than the cap portions 40 and 40 are made of the same material. Are formed integrally with each other so that the masses of the two dampers 20X and 20Y are different from each other to obtain the desired resonance frequencies f1, f2, and f3.

  Also in the seventh embodiment, it is possible to achieve both the suppression of the resonance of the piston 1 and the connecting rod 10 and the suppression of the resonance of the crankshaft and the cylinder block.

  Also in the embodiment 7 shown in FIG. 12, the other configurations, operations, and effects are almost the same as those in the previous embodiment. Therefore, in FIG. Detailed description thereof will be omitted.

In the correspondence between the configuration of the present invention and the above-described embodiment,
The dynamic vibration absorber of the present invention corresponds to the dampers 20X and 20Y of the embodiment,
The present invention is not limited to the configuration of the above-described embodiment.

For example, in each of the above-described embodiments, the full float type is adopted as the assembly method of the piston pin 2. However, the present invention is not limited to this, and the piston pin 2 rotates with respect to the pin insertion hole 10d of the connecting rod 10. A semi-float type that is movable and fixed to the pin support hole 1g of the boss 1f of the piston 1 may be used.
Further, in the illustrated embodiment, the piston 1 for a diesel engine is illustrated, but the present invention can also be applied to a piston for a gasoline engine.

  As described above, the present invention includes a piston that reciprocates in a cylinder, a connecting rod having a small end connected to the piston and a large end connected to a crankshaft, and a small size of the piston and the connecting rod. It is useful for a piston structure of an engine provided with a piston pin having a hollow cross section for connecting the end portion and a dynamic vibration absorber provided inside the piston pin.

DESCRIPTION OF SYMBOLS 1 ... Piston 2 ... Piston pin 10 ... Connecting rod 10a ... Small end part 10b ... Large end part 20X, 20Y ... Damper (dynamic vibration absorber)
20a ... fixed part 20b ... movable part 20c ... support part 20d ... shaft part 40 ... cap part

Claims (6)

A piston that reciprocates in the cylinder;
A connecting rod having a small end connected to the piston and a large end connected to the crankshaft;
A hollow piston pin that connects the piston and the small end of the connecting rod;
A piston structure of an engine provided with a dynamic vibration absorber provided inside the piston pin,
Two dynamic vibration absorbers are provided,
Set one dynamic vibration absorber to suppress vibration at the resonance frequency of the piston and connecting rod,
An engine piston structure in which the other dynamic vibration absorber is set so as to suppress vibration at a resonance frequency of at least one of a crankshaft and a cylinder block. The two dynamic vibration absorbers are configured to obtain the desired resonance frequency by making the masses of the two different from each other,
2. The piston structure of an engine according to claim 1, wherein the moments of the two dynamic vibration absorbers are set to be substantially equal. A fixed portion where the dynamic vibration absorber is fixed to the piston pin;
A movable part extending in the axial direction of the piston pin;
The piston structure for an engine according to claim 1, further comprising a support portion that supports the movable portion so as to be swingable with respect to the fixed portion. One of the two dynamic vibration absorbers is a fixed portion fixed to the piston pin, and a shaft portion extending in the axial direction of the piston pin via a support portion on the fixed portion,
A cap portion fixed to the outer periphery of the shaft portion,
The shaft part and the cap part constitute a movable part,
The engine piston structure according to claim 1, wherein the support portion supports the movable portion so as to be swingable with respect to the fixed portion. The two dynamic vibration absorbers are fixed to the piston pin;
A shaft portion extending in the axial direction of the piston pin via a support portion on the fixed portion;
A cap portion fixed to the outer periphery of the shaft portion,
The shaft part and the cap part constitute a movable part,
The engine piston structure according to claim 1, wherein the support portion supports the movable portion so as to be swingable with respect to the fixed portion. The dynamic vibration absorber has a fixed portion fixed to the piston pin,
The piston structure for an engine according to any one of claims 1 to 5, wherein the fixing portion is fixed at an offset position shifted from an axial center of the piston pin.

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