JP6916082B2 - Piston support structure - Google Patents

Description

The present invention relates to a piston support structure.

In a reciprocating engine, a piston that moves up and down in a cylinder is connected to a small end of a connecting rod by a piston pin. The piston pin is inserted into a pair of pin support holes formed in the piston and a pin insertion hole formed in the small end of the connecting rod, and the piston is formed on the outer peripheral surface of the piston pin and the inner peripheral surface of the pin insertion hole. It moves up and down in the cylinder while sliding and. Therefore, for example, as in Patent Document 1, seizure between the connecting rod and the piston pin is suppressed by supplying oil to the sliding portion where the outer peripheral surface of the piston pin and the inner peripheral surface of the pin insertion hole slide. ..

By the way, an in-cylinder pressure load based on the pressure in the cylinder and an inertial force due to the vertical movement of the piston act on the piston. The in-cylinder pressure load acts as a pressing force that pushes the piston downward. On the other hand, the inertial force acts as a pressing force when the piston is located on the bottom dead center side of the center of the stroke, and moves the piston upward when the piston is located on the top dead center side of the center of the stroke. It acts as a pushing force that pushes up in the direction. Then, near the exhaust top dead center, the pushing force based on the inertial force becomes larger than the pushing force based on the in-cylinder pressure load, and the piston pin is displaced in the pin insertion hole toward the upward movement direction of the piston. As a result, new oil is supplied to the lower sliding portion, which is the sliding portion on the downward moving direction side of the piston, so that seizure in the lower sliding portion is suppressed.

Japanese Unexamined Patent Publication No. 2014-202216

On the other hand, in recent years, the pressure in the cylinder tends to increase in the entire process due to engine downsizing and the like. Therefore, as the in-cylinder pressure load increases, it becomes difficult to supply oil to the lower sliding portion, and there is a risk that the piston pin and the connecting rod may seize at the lower sliding portion.

An object of the present invention is to provide a piston support structure that suppresses seizure between a piston pin and a connecting rod.

The piston support structure for solving the above problems includes a piston having a pair of pin support holes facing each other, a conrod having a pin insertion hole located between the pair of pin support holes, the pair of pin support holes, and the pair of pin support holes. A piston pin that is inserted through the pin insertion hole to connect the piston and the conrod, and oil is supplied to a gap between the inner peripheral surface of the pin insertion hole, and the piston pin with respect to the conrod. It is provided with an urging portion having a spring member for urging the piston in the upward movement direction, and the spring member is arranged on the outside of the piston and is connected to the conrod and the piston pin. It is rotatably connected to.

According to the above configuration, the pushing force of the piston can be increased by the amount that the piston pin is urged in the upward movement direction of the piston by the spring member. As a result, new oil can be easily supplied to the lower sliding portion, which is the sliding portion on the downward moving direction side of the piston. As a result, seizure between the piston pin and the connecting rod can be suppressed. Moreover, since the spring member is arranged on the outside of the piston, the spring member can be assembled after the piston and the connecting rod are connected.

In the piston support structure having the above configuration, the urging portion has a pair of the spring members, and the pair of spring members are arranged on both sides of the connecting rod in the extending direction of the piston pin. preferable.

According to the above configuration, the spring constant required for one spring member in order to obtain a predetermined urging force can be reduced. As a result, the assembly work of the spring member can be performed more easily. Further, since the piston pin receives the urging force in the upward moving direction at both ends, new oil can be more easily supplied to the lower sliding portion.

In the piston support structure having the above configuration, the piston pin has a cylindrical shape in which a shaft hole extending in the axial direction of the piston pin is formed, and the shaft holes are located at both ends of the piston pin. It has a pair of large-diameter portions and a small-diameter portion that communicates the pair of large-diameter portions, and the urging portion includes an inner shaft that is inserted into the shaft hole and projects from both ends of the piston pin, and the large-diameter portion. Each of the diameter portions has a ball bearing that rotatably supports the inner shaft with respect to the piston pin, and the spring member is a portion of the inner shaft that protrudes from the piston pin. It is preferable that the piston pin is rotatably connected to the piston pin by being connected to the piston pin.

According to the above configuration, since the ball bearing is interposed between the spring member and the piston pin, it is possible to reduce the friction generated when the spring member rotates with respect to the piston pin.

In the piston support structure having the above configuration, it is preferable that the spring member is non-rotatably connected to the connecting rod.
According to the above configuration, it is possible to reduce the rotational movement that occurs in the urging portion.

In the piston support structure having the above configuration, it is preferable that the spring member and the connecting rod are fastened by a plurality of fastening members.
According to the above configuration, the spring member and the connecting rod can be non-rotatably connected while facilitating the connection work between the spring member and the connecting rod. In addition, loosening of the fastening member can be suppressed more reliably.

It is a schematic block diagram which shows the schematic structure of one Embodiment of the piston support structure, and is the figure which shows the state which the piston is located at the top dead center. (A) A front view showing the front structure of the spring member in the free state, and (b) a side view showing the side structure of the spring member in the free state. The graph which shows an example of the relationship between a crank angle and a force acting on a piston. (A) A graph showing an example of dimensional conditions of a spring member that generates a predetermined urging force, and (b) a graph showing an example of the relationship between the dimensional conditions of a spring member and a pressure ratio.

An embodiment of the piston support structure will be described with reference to FIGS. 1 to 4.
As shown in FIG. 1, the cylinder 12 formed in the cylinder block 11 accommodates a piston 13 that can move up and down between the top dead center and the bottom dead center along the extending direction of the cylinder 12. .. The piston 13 is manufactured by subjecting a steel base material containing iron as a main component, such as cast iron, to various machining processes.

The piston 13 has a ring belt portion 13A on which various piston rings 14 are mounted, and a pin connecting portion 13B having an outer diameter smaller than that of the ring belt portion 13A on the downward moving direction side of the piston 13 with respect to the ring belt portion 13A. ing. The piston 13 has a step space 15 which is a space formed by a step based on the diameter difference between the ring belt portion 13A and the pin connecting portion 13B. The piston 13 has a back surface 13C having a shape recessed in the upward movement direction of the piston 13, and also has a pair of pin support holes 17 that are open to the back surface 13C and the outer surface of the pin connecting portion 13B and face each other. is doing. In the piston 13, the piston pin 23 is inserted into the pair of pin support holes 17 and the pin insertion hole 24 of the small end portion 21 in a state where the small end portion 21 of the connecting rod 20 is arranged in the recess formed by the back surface 13C. Is connected to the connecting rod 20.

The piston pin 23 is manufactured by subjecting a steel base material containing iron as a main component, for example, chrome steel (Cr steel), to various machining processes, and a shaft hole 25 extending in the axial direction is formed. It has a cylindrical shape. The movement of the piston pin 23 in the axial direction is restricted by a snap ring (not shown) attached to the pin connecting portion 13B in the pin support hole 17. The shaft hole 25 has a pair of large diameter portions 26 located at both ends of the piston pin 23 and a small diameter portion 27 communicating with the pair of large diameter portions 26. The piston pin 23 has an opening at a position facing the oil outlet 36 formed in the connecting rod 20, which will be described later, and an oil introduction path 38 configured to allow oil to be introduced is formed in the shaft hole 25. There is.

The connecting rod 20 is manufactured by subjecting a steel base material containing iron as a main component, such as carbon steel, to various types of machining, and connects the piston 13 and a crankshaft (not shown). The connecting rod 20 swings around the piston pin 23 while sliding the inner peripheral surface of the pin insertion hole 24 with the outer peripheral surface of the piston pin 23 as the piston 13 moves up and down. Of the sliding portions where the inner peripheral surface of the pin insertion hole 24 and the outer peripheral surface of the piston pin 23 slide, the portion on the downward moving direction side of the piston 13 is the lower sliding portion 30 and the upward movement of the piston 13. The portion on the directional side is referred to as an upper sliding portion 31.

Further, the connecting rod 20 has an oil passage 35 that communicates with an oil supply passage formed inside the crankshaft. The oil passage 35 extends along the extending direction of the connecting rod 20 and has an oil outlet 36 which is an opening to the inner peripheral surface of the pin insertion hole 24. An oil having a predetermined pressure, for example, pumped by an oil pump powered by an engine, is introduced into the oil passage 35 through an oil supply passage formed in a crankshaft. The oil introduced into the oil passage 35 is led out from the oil outlet 36 to the lower sliding portion 30, lubricates between the piston pin 23 and the connecting rod 20, and cools the piston pin 23 and the connecting rod 20. .. The piston pin 23 is urged by the urging portion 40 in the upward direction of the piston 13 with respect to the connecting rod 20 so that the oil can be easily supplied to the lower sliding portion 30.

The urging portion 40 has a pair of ball bearings 41, an inner shaft 44, and a pair of spring members 45.
The ball bearing 41 is arranged in the large diameter portion 26 which is a part of the shaft hole 25 of the piston pin 23, and is connected to the large diameter portion 26 by the snap ring 42 mounted on the piston pin 23 in the large diameter portion 26. It is prevented from falling off. Each ball bearing 41 has an inner diameter smaller than that of the small diameter portion 27 of the shaft hole 25 of the piston pin 23.

The inner shaft 44 has a cylindrical shape having a diameter slightly smaller than the inner diameter of the ball bearing 41, and various machining can be performed on a steel base material containing iron as a main component, for example, carbon steel or stainless steel. It is produced by being applied. The inner shaft 44 is inserted through each ball bearing 41 and is rotatably supported with respect to the piston pin 23 via a pair of ball bearings 41. In the inner shaft 44, the length of the inner shaft 44 is larger than the width of the pin connecting portion 13B of the piston 13 and smaller than the diameter of the ring belt portion 13A of the piston 13. The inner shaft 44 is arranged in a region inside the ring belt portion 13A of the piston 13 in the radial direction of the cylinder 12, and both ends thereof protrude from the pin connecting portion 13B of the piston 13. Further, a gap 44A is formed between the inner shaft 44 and the piston pin 23 in the shaft hole 25 of the piston pin 23.

The spring member 45 urges the piston pin 23 against the connecting rod 20 in the upward direction of the piston 13. The spring member 45 is arranged so as to pass through the space outside the piston 13 on both sides of the connecting rod 20 in the extending direction of the piston pin 23. The space outside the piston 13 is the space between the cylinder 12 and the piston 13 in the radial direction of the cylinder 12, and the space on the downward movement direction side of the piston 13 with respect to the piston 13 in the axial direction of the cylinder 12. .. The spring member 45 is preferably made of, for example, a member conforming to the spring steel material specified in JIS G4801, and is made of a material having a high yield stress so that the elastic deformation region with respect to the load becomes large. The spring member 45 has a bent shape that is bent like a crank, and is connected to the piston pin 23 via the first connecting portion 47 that is connected to the connecting rod 20 by the fastening member 46, the inner shaft 44, and the ball bearing 41. It has a second connecting portion 48 that is rotatably connected. Further, the spring member 45 has an offset portion 49 that offsets the second connecting portion 48 toward the vicinity of the end portion of the piston pin 23 with respect to the first connecting portion 47. The first connecting portion 47 is arranged along the extending direction of the connecting rod 20, and the second connecting portion 48 provides a step space 15 based on the diameter difference between the ring belt portion 13A and the pin connecting portion 13B of the piston 13. It is arranged along the pin connecting portion 13B. Further, the offset portion 49 offsets the second connecting portion 48 with respect to the first connecting portion 47 through the space on the downward movement direction side with respect to the piston 13.

As shown in FIGS. 2A and 2B, the spring member 45 is manufactured by bending a plate-shaped base material having a width b and a thickness h by press working or the like.
The first connecting portion 47 has a plurality of fastening holes 51 arranged along the extending direction of the connecting rod 20. The first connecting portion 47 is fixed to the connecting rod 20 by fastening the fastening member 46 to the connecting rod 20 through these fastening holes 51, and connects the spring member 45 and the connecting rod 20 in a non-rotatable manner.

The second connecting portion 48 is a portion extending substantially parallel to the first connecting portion 47, and has a shaft insertion hole 52 into which the inner shaft 44 is inserted at the tip end portion thereof. The second connecting portion 48 attaches the spring member 45 to the inner shaft 44 by mounting the snap ring 55 (see FIG. 1) on the inner shaft 44 with the end portion of the inner shaft 44 inserted into the shaft insertion hole 52. Connect to. As a result, the spring member 45 is rotatably connected to the piston pin 23 via the inner shaft 44 and the ball bearing 41. The spring member 45 may be rotatably connected to the inner shaft 44, or may be non-rotatably connected to the inner shaft 44.

The offset portion 49 is integrally connected to the first connecting portion 47 and the second connecting portion 48 via an R portion having a predetermined dimension. The offset portion 49 extends obliquely with respect to the first and second connecting portions 47 and 48 when the spring member 45 is in the free state. As a result, the offset portion 49 arranges the first connecting portion 47 and the second connecting portion 48 at positions shifted by the setup amount x along the extending direction of the first connecting portion 47. As shown in FIG. 1, the spring member 45 is in a state of being elastically deformed so as to be orthogonal to the first connecting portion 47 and the second connecting portion 48 when assembled to the connecting rod 20 and the piston pin 23. In the following, the width b, the thickness h, and the setup amount x of the spring member 45 are referred to as dimensional conditions of the spring member 45.

In the piston support structure described above, the connecting rod 20 and the piston 13 are connected by the piston pin 23, and then the urging portion 40 is assembled in the following order.
First, the ball bearing 41 is attached to the piston pin 23. The ball bearing 41 is arranged on the large diameter portion 26 of the piston pin 23, and then is attached to the piston pin 23 by attaching the snap ring 42 to the large diameter portion 26. Subsequently, the inner shaft 44 is inserted through the ball bearing 41. At this time, both ends of the inner shaft 44 are held in a state of protruding from the pin connecting portion 13B of the piston 13. Next, after the first connecting portion 47 of the spring member 45 is connected to the connecting rod 20, the inner shaft 44 is inserted into the shaft insertion hole 52 of the second connecting portion 48 in a state where the spring member 45 is elastically deformed. Then, the snap ring 55 is attached to the portion of the inner shaft 44 that protrudes from the shaft insertion hole 52. The spring member 45 is mounted on one end side of the piston pin 23 and on the other end side of the piston pin 23. In the urging portion 40 assembled in this way, the elastic force of the spring member 45 having the connecting rod 20 as a fulcrum acts on both ends of the piston pin 23 via the inner shaft 44 and the ball bearing 41. As a result, the piston pin 23 is urged against the connecting rod 20 in the upward direction of the piston 13.

By the way, a pushing force in the downward moving direction side and a pushing force in the upward moving direction side act on the piston 13. The in-cylinder pressure load based on the product of the in-cylinder pressure, which is the pressure in the cylinder 12, and the bore area of the cylinder 12 acts on the piston 13 as one of the pressing forces. This in-cylinder pressure load becomes small in a low load state of an engine in which the in-cylinder pressure is low, and becomes large in a high load state of an engine in which the in-cylinder pressure is high. Further, an inertial force based on the total weight of the piston 13 and the piston pin 23 and the acceleration of the piston 13 acts on the piston 13. This inertial force acts as one of the pushing forces when the piston 13 is located closer to the top dead center than the center of the stroke, and when the piston 13 is located closer to the bottom dead center than the center of the stroke. It acts as one of the pressing forces. The inertial force increases as the engine speed increases, and decreases as the engine speed decreases. Further, the sum of the urging forces based on the spring constant of each spring member 45 and the set-up amount x of the spring member 45 acts on the piston 13 as one of the pushing forces.

FIG. 3 is a graph showing an example of the result of a simulation performed for setting characteristics such as dimensional conditions and materials of the spring member 45. In this simulation, the operating state of the engine was set to a low speed and high load state, and the relationship between the crank angle and the force acting on the piston 13 was simulated.

In FIG. 3, the crank angle when the piston 13 is at the compression top dead center is displayed as 0 ° CA, and the in-cylinder pressure load PS, the inertial force Wa, and the inertial force act as the forces acting on the piston 13. The resultant force F + Wa of Wa and the urging force F by the urging unit 40 is shown. Further, the in-cylinder pressure load PS acts as a pressing force in the positive region on the vertical axis. On the other hand, the inertial force Wa and the resultant force F + Wa act as a pushing force in the positive region on the vertical axis and as a pushing force in the negative region on the vertical axis.

As shown in FIG. 3, in this simulation, the inertial force Wa does not exceed the in-cylinder pressure load PS. Therefore, the spring member 45 so that the resultant force F + Wa exceeds the in-cylinder pressure load PS near the crank angle of 360 ° CA where the pushing force based on the in-cylinder pressure load PS is the smallest and the pushing force based on the inertial force Wa is the largest. Set the characteristics of. That is, the characteristics of the spring member 45 are set so that an urging force F larger than the minimum value of the difference between the pushing force based on the in-cylinder pressure load PS and the pushing force based on the inertial force Wa is generated. By setting the characteristics of the spring member 45 in this way, it is possible to form a period A in which the pushing force exceeds the pushing force. Further, by setting the characteristics of the spring member 45 with reference to the low speed and high load state, the period A is likely to be formed even in other operating states. During the period A in which the pushing force is larger than the pushing force, the piston pin 23 is displaced toward the upward movement direction side of the piston 13 in the pin insertion hole 24. At this time, new oil is supplied to the lower sliding portion 30 from the oil outlet 36.

The result of the simulation performed on the dimensional condition of the spring member 45 will be described with reference to FIG.
In this simulation, the dimensional conditions (thickness h, width b, and setup amount x) of the spring member 45 are calculated under the condition that the urging portion 40 applies a predetermined urging force to the piston 13, and the dimensional conditions (thickness h, width b, and setup amount x) are calculated. The estimated seizure cylinder pressure under the dimensional conditions was calculated. The estimated seizure in-cylinder pressure is the in-cylinder pressure at which the piston 13 and the piston pin 23 are seized at the lower sliding portion 30. Then, the pressure ratio R (= P1 / P2), which is the ratio between the estimated seizure cylinder pressure P1 when the urging portion 40 is present and the estimated seizure cylinder pressure P2 when the urging portion 40 is not present, was calculated. That is, the result is that the seizure is less likely to occur as the pressure ratio R is larger than 1. The material of the spring member 45 was SUP7 (JISG4801).

FIG. 4A is a graph showing an example of dimensional conditions of the spring member 45 when the urging portion 40 applies a predetermined urging force to the piston 13. FIG. 4B is a graph showing an example of the relationship between each dimensional condition and the pressure ratio R.

As shown in FIG. 4A, it was found that the set-up amount x was smaller in applying a predetermined urging force to the piston 13 when the thickness h was larger even if the cross-sectional area was the same. Further, it was found that the larger the thickness h, the smaller the increase amount of the setup amount x with respect to the decrease amount of the width b. That is, it was confirmed that the larger the thickness h, the smaller the change in the setup amount x with respect to the change in the width b.

As shown in FIG. 4B, it was found that the larger the thickness h, the larger the pressure ratio R, even if the cross-sectional areas were the same. Further, it was confirmed that the larger the thickness h, the larger the increase in the pressure ratio R with respect to the increase in the width b.

From these facts, it is preferable that the dimensional condition of the spring member 45 has a large thickness h and a large width b when a predetermined urging force is applied in order to effectively increase the estimated seizure cylinder pressure. Further, as for the dimensional condition of the spring member 45, if the cross-sectional area is the same, it is preferable that the thickness h is large.

According to the piston support structure of the above embodiment, the effects listed below can be obtained.
(1) The pushing force can be increased by the amount of the urging force applied to the piston 13 by the urging portion 40 having the spring member 45. As a result, new oil is easily supplied to the lower sliding portion 30, so that seizure between the piston pin 23 and the connecting rod 20 can be suppressed.

(2) As the urging portion for urging the connecting rod 20 in the upward movement direction of the piston 13, for example, a method of disposing a spring member between the small end portion 21 of the connecting rod 20 and the back surface 13C of the piston 13. , A method of disposing the spring member inside the piston 13 or inside the connecting rod 20 can be considered. However, in such a method, it is necessary to simultaneously perform the work of assembling the piston 13 and the connecting rod 20 with the piston pin 23 and the work of assembling the urging portion. Moreover, the spring constant required for the spring member to obtain the desired urging force becomes excessively large, the assembly work process becomes excessively complicated, and the jig required for the assembly work requires a great deal of cost. It is expected that it will take.

In this respect, the spring member 45 is arranged so as to pass through the space outside the piston 13. According to such a configuration, the connecting rod 20 and the piston 13 are assembled by the piston pin 23, and then the urging portion 40 is assembled, that is, the assembling work of the connecting rod 20 and the piston 13 and the assembling work of the urging portion 40. Can be performed as a separate process. As a result, the assembling work of the urging unit 40 can be facilitated.

(3) The urging portion 40 has a pair of spring members 45, and these pair of spring members 45 are arranged on both sides of the connecting rod 20 in the extending direction of the piston pin 23. Specifically, one of the pair of spring members 45 is arranged in a region on the one end side of the piston pin 23 with respect to the connecting rod 20 and is rotatably connected to one end of the piston pin 23. Further, the other end of the pair of spring members 45 is arranged in the region on the other end side of the piston pin 23 with respect to the connecting rod 20 and is rotatably connected to the other end portion of the piston pin 23.

According to such a configuration, the spring constant required for one spring member 45 can be reduced in order to obtain a predetermined urging force. As a result, the assembly work of the spring member 45 can be performed more easily. Further, the piston pin 23 can displace the entire piston pin 23 in the upward movement direction by receiving an urging force in the upward movement direction at both ends thereof. As a result, a gap is likely to be formed in the lower sliding portion 30, and new oil is more likely to be supplied to the lower sliding portion 30.

(4) The spring member 45 is rotatably connected to the piston pin 23 via the inner shaft 44 and the ball bearing 41. According to such a configuration, the inner shaft 44 rotates with respect to the ball bearing 41, so that the spring member 45 rotates with respect to the piston pin 23. This makes it possible to reduce the friction generated when the spring member 45 rotates with respect to the piston pin 23.
(5) Further, since the gap 44A is formed between the inner shaft 44 and the piston pin 23, the effect described in (4) above becomes more remarkable.

(6) Since the spring member 45 is non-rotatably connected to the connecting rod 20, the spring member 45 does not rotate with respect to the connecting rod 20. As a result, the only rotational movement required for the urging portion 40 in the vertical movement of the piston 13 is the rotational movement of the spring member 45 with respect to the piston pin 23. By reducing the number of places where the rotation operation is required in this way, mechanical troubles caused by the rotation operation are less likely to occur in the urging portion 40.

Further, in the configuration in which the spring member 45 is rotatably connected to the piston pin 23 via the inner shaft 44 and the ball bearing 41, the rotation of the spring member 45 with respect to the piston pin 23 is intensively performed in the ball bearing 41. .. As a result, the friction generated by the rotation of the spring member 45 with respect to the piston pin 23 can be effectively reduced. Such an effect becomes remarkable when the spring member 45 is non-rotatably connected to the inner shaft 44.

(7) The spring member 45 and the connecting rod 20 are fastened by a plurality of fastening members 46. Since the spring member 45 is non-rotatably connected to the connecting rod 20 by fastening with the fastening member 46 in this way, the connecting work becomes easier as compared with the case where they are connected by metal joining such as welding. At the same time, changes in the mechanical properties of the connecting rod 20 and the spring member 45 at the connecting portion can be suppressed. Further, since there are a plurality of fastening positions by the fastening member 46, it is possible to prevent the spring member 45 from rotating with respect to the connecting rod 20 and to suppress loosening of the fastening member 46. Further, since the fastening positions of the fastening members 46 are aligned along the extending direction of the connecting rod 20, the durability of the fastening member 46 with respect to the load in the direction along the extending direction of the connecting rod 20 can be enhanced.

(8) The piston pin 23 is formed with an oil introduction path 38 configured so that oil can be introduced into the shaft hole 25. As a result, oil can be supplied to the support portion of the inner shaft 44 by the ball bearing 41, the rolling portion of the ball bearing 41, and the like. As a result, the spring member 45 can be smoothly rotated with respect to the piston pin 23, and the ball bearing 41 and the inner shaft 44 can be cooled.

The above embodiment can be modified as appropriate and implemented as follows.
-The spring member 45 and the connecting rod 20 may be connected by fastening with one fastening member, or may be connected by metal joining such as welding.

The spring member 45 is rotatably connected to the piston pin 23 via the inner shaft 44 and the ball bearing 41. Not limited to this, the spring member 45 may be rotatably connected to the piston pin 23. For example, the ball bearing 41 is omitted, and the spring member 45 is connected to the piston pin 23 only via the inner shaft 44. It may be configured to be rotatably connected to the bearing. Further, for example, even if the ball bearing 41 and the inner shaft 44 are omitted, the end portion of the piston pin 23 is projected from the pin connecting portion 13B, and the protruding portion is inserted into the shaft insertion hole 52 of the spring member 45. good.

The urging portion 40 may have a configuration in which only one of the pair of spring members 45 is provided.
The spring member 45 may be rotatably connected to the connecting rod 20. For example, the spring member 45 and the connecting rod 20 are connected by inserting an insertion pin having a circular cross section formed in the spring member 45 into an insertion hole having a circular cross section formed in the connecting rod 20. You may.

The spring member 45 may have a rib at the connecting portion to the connecting rod 20 or the piston pin 23, for example. According to such a configuration, the mechanical strength at the connecting portion can be increased.

The spring member 45 is not limited to a configuration formed by processing a plate-shaped base material having a width b and a thickness h. For example, the spring member 45 may have a plate-like shape at the first connecting portion 47 and the second connecting portion 48, and may have a linear shape at the offset portion 49. In such a configuration, the offset portion 49 may have a crank-like shape.

The method of supplying oil to the sliding portion between the inner peripheral surface of the pin insertion hole 24 and the outer peripheral surface of the piston pin 23 is not limited to the method using the oil passage 35 formed in the connecting rod 20, for example, the piston 13. It may be an oil jet that injects oil toward the back surface 13C.

11 ... Cylinder block, 12 ... Cylinder, 13 ... Piston, 13A ... Ring belt part, 13B ... Pin connection part, 13C ... Back side, 14 ... Piston ring, 15 ... Step part, 17 ... Pin support hole, 20 ... Connecting rod, 21 ... Small end, 23 ... Piston pin, 24 ... Pin insertion hole, 25 ... Shaft hole, 26 ... Large diameter, 27 ... Small diameter, 30 ... Lower sliding part 30 ... Upper sliding part, 35 ... Oil passage , 36 ... oil outlet, 38 ... oil inlet, 40 ... urging part, 41 ... ball bearing, 42 ... snap ring, 44 ... inner shaft, 44A ... gap, 45 ... spring member, 46 ... fastening member, 47 ... 1st connecting part, 48 ... 2nd connecting part, 49 ... offset part, 51 ... fastening hole, 52 ... shaft insertion hole, 55 ... snap ring.

Claims (5)

A piston with a pair of pin support holes facing each other,
A connecting rod having a pin insertion hole located between the pair of pin support holes,
A piston pin that is inserted through the pair of pin support holes and the pin insertion hole to connect the piston and the connecting rod, and oil is supplied to a gap between the inner peripheral surface of the pin insertion hole.
The connecting rod is provided with an urging portion having a spring member for urging the piston pin in the upward movement direction of the piston.
A piston support structure in which the spring member is arranged on the outside of the piston and is connected to the connecting rod and rotatably connected to the piston pin. The urging portion has a pair of the spring members.
The piston support structure according to claim 1, wherein the pair of spring members are arranged on both sides of the connecting rod in the extending direction of the piston pin. The piston pin has a cylindrical shape in which a shaft hole extending in the axial direction of the piston pin is formed.
The shaft hole has a pair of large diameter portions located at both ends of the piston pin and a small diameter portion communicating with the pair of large diameter portions.
The urging portion includes an inner shaft that is inserted into the shaft hole and protrudes from both ends of the piston pin, and the inner shaft that is arranged in each of the large diameter portions and is rotatable with respect to the piston pin. With ball bearings to support
The piston support structure according to claim 2, wherein the spring member is rotatably connected to the piston pin by being connected to a portion of the inner shaft that protrudes from the piston pin. The piston pin support structure according to any one of claims 1 to 3, wherein the spring member is non-rotatably connected to the connecting rod. The piston support structure according to claim 4, wherein the spring member and the connecting rod are fastened by a plurality of fastening members.

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