JP6845100B2 - Lubrication structure of piston support - Google Patents

Description

The present invention relates to a lubrication structure for a piston support portion.

As shown in FIG. 3, in a general reciprocating engine used in an automobile or the like, a piston 2 housed in a cylinder 1 is swingably supported by a small end portion 4a of a connecting rod 4 via a piston pin 3. The large end portion 4b of the connecting rod 4 is connected to the crankshaft 6 via the crank pin 5.

Further, the crank pin 5 is supported by the crank arm 6a at a position deviated from the center of the crankshaft 6, and the crank pin 5 moves in a circular trajectory around the center of the crankshaft 6. The piston 2 moves up and down in the cylinder 1 while the connecting rod 4 swings around the piston pin 3.

Here, both ends of the piston pin 3 are rotatably supported by a pair of pin boss portions 7 formed on the back surface of the piston 2, and the small end portions 4a of the connecting rod 4 are the pin boss portions. The central portion of the piston pin 3 sandwiched between the 7's is rotatably supported by the shaft.

For lubrication of the support portion of the piston 2, the lubricating oil is forcibly supplied through the oil passage 8 inside the connecting rod 4, or the lubricating oil is applied to the back surface of the piston 2 from an oil injection nozzle (not shown) provided in the lower part of the cylinder 1. It is performed by injecting upward toward the crankshaft 6 or by utilizing the splashing of the lubricating oil of the crankshaft 6.

The following patent documents 1, 2 and the like are available as prior art document information related to the lubrication structure of this type of piston support portion.

Japanese Unexamined Patent Publication No. 2006-258194 Japanese Unexamined Patent Publication No. 2011-149444

In recent years, it has been widely practiced to reduce friction by lowering the rotation speed in order to reduce fuel consumption of the engine, and to combine high supercharging to compensate for the decrease in power due to the lower rotation speed. In such a case, the in-cylinder pressure in the engine increases significantly in the entire stroke, and the piston 2 is always maintained in a depressed state, while the inertial force acting on the piston 2 near the exhaust top dead center decreases, and as a result, the sliding rod There is a concern that the lubricating oil will not spread well to the moving parts and the risk of seizure between the piston 2, the piston pin 3 and the connecting rod 4 will increase.

That is, conventionally, no matter how much the in-cylinder pressure exerts a force to push down the piston 2, the force to lift the piston 2 by the inertial force is superior in the vicinity of the exhaust top dead center, and the small end portion 4a of the connecting rod 4 and the piston The sliding portion of the piston pin 3 pressed against each pin boss portion 7 of 2 (the lower portion of the central portion of the piston pin 3 with respect to the small end portion 4a of the connecting rod 4, and each pin boss portion 7 of the piston 2). However, there was a gap in the upper part of both ends of the piston pin 3), and lubricating oil entered the gap to perform lubrication and cooling. If the feeding is compatible, it becomes difficult for the lubricating oil to enter the sliding portion even near the top dead center of the exhaust.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a lubrication structure for a piston support portion capable of suppressing seizure between a piston, a piston pin, and a connecting rod.

The present invention has a lubrication structure for a piston support portion in which the piston is swingably supported by a small end portion of a connecting rod via a piston pin whose both ends are rotatably supported by a pin boss portion formed on the back surface of the piston. The piston pin is formed of a circular tube and the penetrating portion is used as an accommodation space, and the inner pin forming a columnar diameter smaller than the inner diameter of the accommodation space is accommodated in the accommodation space, and both ends of the accommodation space are accommodated. The opening is sealed with a lid, and an oil hole that radially communicates the inside and outside of the accommodation space is formed in a shaft support region formed by the pin boss portion of the piston pin and the small end portion of the connecting rod, and the inner pin is formed. Is characterized in that it can roll while being pressed against the inner peripheral surface of the piston pin by an inertial force near the top dead center and the bottom dead center.

Thus, in this way, the inner pin rolls in the accommodation space of the piston pin due to the vertical movement of the piston and the swing of the connecting rod, and the inner pin is particularly near the top dead point and the bottom dead point. Will roll while being pressed against the inner peripheral surface of the piston pin by the inertial force, but an oil pool having a crescent-shaped cross section is formed between the inner peripheral surface of the piston pin and the inner pin. On the side where the inner pin rolls relative to the piston pin and advances, the oil pool is crushed and reduced by the inner pin, and the lubricating oil is remarkably pressurized by the wedge effect to pass through the oil hole. It is extruded to the outer peripheral surface of the piston pin, and forced lubrication is performed on the sliding part where the piston pin is pressed against the small end of the connecting rod and each pin boss of the piston to achieve good lubrication and cooling.

On the other hand, on the side where the inner pin rolls relative to the piston pin and passes by, the oil pool is expanded at once and the lubricating oil is significantly depressurized, resulting in a negative pressure state, and the piston passes through the oil hole. Since the lubricating oil is sucked from the outer peripheral surface of the pin, it is possible to replenish the lubricating oil to the accommodation space only by arranging at least a part of the oil holes so that the oil can be supplied from the existing lubricating system.

That is, when the inner pin rolls while being pressed against the inner peripheral surface of the piston pin by inertial force near the top dead center and the bottom dead center, the lubricating oil is pushed out at each oil hole of the inner pin. The suction will be repeated alternately.

Further, in carrying out the present invention more specifically, an oil supply passage for guiding lubricating oil from the cooling gallery on the upper part of the piston toward the oil hole formed in the shaft support region by the pin boss portion of the piston pin is provided. Lubricating oil may be replenished to the accommodating space of the piston pin through the piston pin.

According to the lubrication structure of the piston support portion of the present invention described above, the inner pin is rolled while being pressed against the inner peripheral surface of the piston pin by an inertial force near the top dead center and the bottom dead center, thereby causing oil from the accommodation space. Since the lubricating oil can be remarkably pressurized through the holes and pushed out to the outer peripheral surface of the piston pin, forced lubrication is applied to the small end of the connecting rod and the sliding part where the piston pin is pressed against each pin boss of the piston. As a result, good lubrication and cooling of the sliding portion can be achieved, and seizure between the piston, the piston pin, and the connecting rod can be effectively suppressed, which is an excellent effect.

It is a side sectional view which shows an example of embodiment of this invention. It is a front sectional view of the piston pin and the inner pin of FIG. It is a front sectional view which shows the conventional example.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

As shown in FIGS. 1 and 2, in this embodiment, a piston whose both ends are rotatably supported by a pin boss portion 7 formed on the back surface of the piston 2 is substantially similar to the case of FIG. 3 described above. The piston 2 is swingably supported by the small end portion 4a of the connecting rod 4 via the pin 3, but the piston pin 3 is formed of a circular tube and the penetrating portion is used as the accommodating space 9, and the accommodating space 9 is provided. The inner pin 10 forming a columnar diameter smaller than the inner diameter of the piston pin 3 is accommodated in the accommodation space 9, and the openings at both ends of the accommodation space 9 are sealed by plugs 11 and 12 (lid), and the piston pin 3 is described. An oil hole 13 that radially communicates the inside and outside of the accommodation space 9 is bored in the axial support region formed by the pin boss portion 7 and the small end portion 4a of the connecting rod 4, and the inner pin 10 is near top dead center and underneath. It is configured so that it can roll while being pressed against the inner peripheral surface of the piston pin 3 by an inertial force near the point.

Further, in the example shown here, the cooling gallery 14 is annularly bored inside the upper side of the piston 2, and the oil hole bored in the shaft support region by the pin boss portion 7 of the piston pin 3. A refueling passage 15 for guiding the lubricating oil from the cooling gallery 14 is bored toward 13, and the lubricating oil is replenished to the accommodating space 9 of the piston pin 3 through the refueling passage 15.

That is, the cooling gallery 14 has an oil inlet (opening at a phase not shown in FIG. 1) that opens downward at an appropriate position in the circumferential direction, and upwards from an oil injection nozzle (not shown) provided in the lower part of the cylinder 1. The injected lubricating oil is mainly injected into the cooling gallery 14 from the oil inlet when the piston 2 is lowered, and shaken by the inertial force due to the vertical movement of the piston 2 to efficiently exchange heat. Lubricating oil that has been heated by removing heat from the piston 2 by this heat exchange flows down from an oil outlet (opened in a phase not shown in FIG. 1) that is opened downward at an appropriate position in the circumferential direction of the cooling gallery 14 to recover Therefore, a part of the lubricating oil is divided into the oil supply passage 15 to replenish the accommodation space 9.

Here, at a position where the oil supply passage 15 abuts on the outer peripheral surface of the piston pin 3, an oil groove 16 is formed over the entire circumference of the piston pin 3, and all the oil holes arranged in the circumferential direction at this position. Lubricating oil can be supplied to 13.

The oil passage 8 inside the connecting rod 4 is left as before in this embodiment, but there is room for abolishing the oil passage 8 due to the new construction of the oil passage 15 for guiding the lubricating oil from the cooling gallery 14. I would like to add that.

Further, a part of the oil hole 13 formed in the shaft support region by the small end portion 4a of the connecting rod 4 of the piston pin 3 can communicate with the oil passage 8 inside the connecting rod 4 without newly constructing the oil supply passage 15. In this way, it is possible to replenish the accommodation space 9 with lubricating oil.

Thus, in this case, the inner pin 10 rolls in the accommodation space 9 of the piston pin 3 due to the vertical movement of the piston 2 and the swing of the conrod 4, and particularly near the top dead point and the bottom dead point. The inner pin 10 rolls while being pressed against the inner peripheral surface of the piston pin 3 by an inertial force, but there is a crescent moon between the inner peripheral surface of the piston pin 3 and the inner pin 10. An oil pool having a shape cross section (see FIG. 2) is formed, and the inner pin 10 rolls relative to the piston pin 3 and advances (the side indicated by A in FIG. 2). The oil pool is crushed and shrunk by 10, and the lubricating oil is remarkably pressurized by the wedge effect and pushed out to the outer peripheral surface of the piston pin 3 through the oil hole 13, and the small end portion 4a of the conrod 4 and the piston 2 Forced lubrication is performed on the sliding portion where the piston pin 3 is pressed against each pin boss portion 7, and good lubrication and cooling are achieved.

On the other hand, on the side where the inner pin 10 rolls relative to the piston pin 3 and passes by (the side indicated by B in FIG. 2), the oil pool is expanded at once and the lubricating oil is significantly depressurized. In a negative pressure state, lubricating oil is sucked from the outer peripheral surface of the piston pin 3 through the oil holes 13, so that at least some of the oil holes 13 need only be arranged so that oil can be supplied from the existing lubricating system. Lubricating oil can be replenished to the accommodation space 9.

That is, the inner pin 10 rolls while being pressed against the inner peripheral surface of the piston pin 3 by inertial force near the top dead center and the bottom dead center, thereby lubricating each oil hole 13 of the inner pin 10. Oil extrusion and suction will be repeated alternately.

Therefore, according to the above embodiment, the inner pin 10 is rolled while being pressed against the inner peripheral surface of the piston pin 3 by an inertial force near the top dead center and the bottom dead center, so that the oil hole 13 is formed from the accommodation space 9. Since the lubricating oil can be remarkably pressurized through the piston pin 3 and pushed out to the outer peripheral surface of the piston pin 3, the sliding portion where the piston pin 3 is pressed against the small end portion 4a of the connecting rod 4 and each pin boss portion 7 of the piston 2. Forcible lubrication can be performed to ensure good lubrication and cooling of the sliding portion, and seizure between the piston 2 and the piston pin 3 and the connecting rod 4 can be effectively suppressed.

The lubrication structure of the piston support portion of the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

2 Piston 3 Piston pin 4 Connecting rod 4a Small end 7 Pin boss 9 Storage space 10 Inner pin 11 Plug (lid)
12 plug (lid body)
13 Oil hole 14 Cooling gallery 15 Oil supply passage 16 Oil ditch

Claims (2)

It is a lubrication structure of a piston support portion in which the piston is swingably supported by a small end portion of a conrod via a piston pin whose both ends are rotatably supported by a pin boss portion formed on the back surface of the piston. The piston pin is formed of a circular tube, the penetrating portion is used as a storage space, the inner pin forming a columnar diameter smaller than the inner diameter of the storage space is housed in the storage space, and the openings at both ends of the storage space are covered. In the shaft support region formed by the pin boss portion of the piston pin and the small end portion of the conrod, an oil hole that radially communicates the inside and outside of the accommodation space is formed in the piston pin, and the inner pin reaches the top dead center. A lubrication structure for a piston support portion, which is configured so that it can roll while being pressed against the inner peripheral surface of the piston pin by an inertial force in the vicinity and near the bottom dead center. The lubrication structure for a piston support according to claim 1, wherein a lubrication path for guiding lubricating oil from a cooling gallery on the upper part of the piston is provided toward an oil hole formed in a shaft support region by a pin boss portion of the piston pin. ..

Images