JP2017089735A - Bearing and connecting rod assembly - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bearing capable of easily supply lubricant to a lower portion of an inner peripheral surface of a bush, and a connecting rod assembly.SOLUTION: A bearing 1, with a direction of a connecting rod 7 passing through a small end part 70 and a large end part 71 as a vertical direction, the small end part 70 side as an upper side and the large end part 71 side as a lower side, includes a cylindrical bush 2 arranged at the small end part 70, supporting a piston pin 92 and having a recess part 201 on an inner peripheral surface 20, and a thermal expansion member 6 having a larger thermal expansion coefficient than the bush 2, arranged in the recess part 201 so as to project from the recess part 201 by thermal expansion and having a support part 60 capable of supporting the piston pin 92. The support part 60 is arranged on a lower side with respect to a gravity center G of the bush 2.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a bearing that is disposed at a small end portion of a connecting rod and supports a piston pin in a relatively swingable manner, and a connecting rod assembly.

  As disclosed in Patent Document 1, the connecting rod transmits an explosive force acting on the piston to the crankshaft. Further, the connecting rod converts the reciprocating motion of the piston into the rotational motion of the crankshaft. The small end of the connecting rod is connected to the piston pin through a bush. Lubricating oil is supplied between the inner peripheral surface of the bush and the outer peripheral surface of the piston pin.

JP-A-63-92818

  With the piston stroke direction being the vertical direction, the top dead center side being the top side, and the bottom dead center side being the bottom side, the engine's explosive force acts downward on the piston, that is, the piston pin. That is, the explosive force acts in the direction in which the piston pin is pressed against the lower portion of the inner peripheral surface of the bush. On the other hand, as the crankshaft rotates, an upward centrifugal force acts on the piston pin in a predetermined crank rotation angle region. In this way, the downward explosion force and the upward centrifugal force act on the piston pin. The piston pin can be floated with respect to the inner peripheral surface of the bush by the centrifugal force. For this reason, lubricating oil can be supplied to the lower part of the inner peripheral surface of the bush.

  However, in recent engines (for example, diesel turbo engines), the compression ratio of the engine is high. For this reason, the explosive power is increasing. On the other hand, since the reduction of sliding resistance is required from the viewpoint of improving fuel efficiency, it is preferable that the engine speed is low. When the rotational speed of the engine becomes slow, the rotational speed of the large end of the connecting rod slows down. Accordingly, the centrifugal force acting on the piston pin is reduced.

  Thus, in recent engines, the explosive force acting downward on the piston pin tends to increase. On the other hand, the centrifugal force acting upward on the piston pin tends to be small. For this reason, the lower part of the outer peripheral surface of the piston pin is pressed against the lower part of the inner peripheral surface of the bush. Therefore, it becomes difficult to supply lubricating oil to the lower part of the inner peripheral surface of the bush. In particular, it is necessary to reliably supply the lubricating oil to the lower portion of the inner peripheral surface of the bush at a high temperature when the temperature around the bush is higher than that during normal operation. Then, an object of this invention is to provide the bearing and connecting rod assembly which can supply lubricating oil to the lower part of the internal peripheral surface of a bush simply.

  In order to solve the above-mentioned problems, the bearing of the present invention is configured so that the direction passing through the small end portion and the large end portion of the connecting rod is the vertical direction, the small end side is the upper side, and the large end side is the lower side. A cylindrical bush that is disposed at the small end, supports the piston pin, and has a recess on the inner peripheral surface, and has a larger coefficient of thermal expansion than the bush, and is disposed in the recess so as to protrude from the recess by thermal expansion. And a thermal expansion member having a support part capable of supporting the piston pin, wherein the support part is disposed on the lower side of the center of gravity of the bush. Moreover, in order to solve the said subject, the connecting rod assembly of this invention is provided with the said bearing and the connecting rod by which the said bearing is arrange | positioned at a small end part.

  The support part is disposed below the center of gravity of the bush. Further, the thermal expansion member can be thermally deformed according to the temperature around the bearing. For this reason, when the thermal expansion member protrudes (thermal expansion) from the concave portion, the support portion can support the piston pin. Therefore, the piston pin can be floated with respect to the inner peripheral surface of the bush. Therefore, lubricating oil can be easily supplied to the lower part of the inner peripheral surface of the bush.

It is an axial sectional view of a cylinder of an engine provided with a connecting rod assembly which is one embodiment of the present invention. It is an axial sectional view of the piston of the engine. FIG. 3 is an enlarged view in a circle III in FIG. 2. It is a fragmentary perspective view of the bearing which is one Embodiment of this invention. It is radial direction sectional drawing at the time of the normal driving | operation of the same bearing. It is radial direction sectional drawing at the time of the high temperature of the bearing.

  Embodiments of the bearing and connecting rod assembly of the present invention will be described below.

[Composition of connecting rod assembly]
First, the structure of the connecting rod assembly of this embodiment is demonstrated. FIG. 1 shows an axial cross-sectional view of a cylinder of an engine provided with a connecting rod assembly of this embodiment. As shown in FIG. 1, the engine 9 includes a cylinder 90, a piston 91, a piston pin 92, a crankshaft 93, and a connecting rod assembly 8. The engine 9 is a diesel turbo engine.

  The piston 91 is accommodated in the cylinder 90. A combustion chamber C is defined in the cylinder 90 by the piston 91. The piston pin 92 has a cylindrical shape. The piston pin 92 penetrates the piston 91 in the diameter direction. The crankshaft 93 includes a main journal 930, a crankpin 931, and a crank arm 932. The crank pin 931 is eccentrically connected to the main journal 930 via a crank arm 932. That is, the center a2 of the large end portion 71 of the connecting rod (connecting rod) 7 described later is eccentric with respect to the center a3 of the main journal 930.

  FIG. 2 shows an axial sectional view of an engine piston. FIG. 3 shows an enlarged view in the circle III of FIG. In FIG. 4, the fragmentary perspective view of the bearing of this embodiment is shown. FIG. 5 shows a radial cross-sectional view of the bearing during normal operation. FIG. 6 is a radial sectional view of the bearing at a high temperature. FIG. 3 corresponds to a radial sectional view of the bearing when the engine is stopped. In FIG. 4, the piston pin 92 is shown through.

  As shown in FIGS. 2 and 4, the connecting rod assembly 8 includes a bearing 1 and a connecting rod 7. As shown in FIGS. 1 and 2, the connecting rod 7 includes a small end portion 70, a large end portion 71, and a rod portion 72. As shown in FIG. 1, the large end 71 has an annular shape. A crank pin 931 is connected to the large end 71 via a connecting rod bearing 710. As shown in FIGS. 2 to 6, the small end portion 70 has an annular shape with a smaller diameter than the large end portion 71. The small end portion 70 includes two oil holes 700. The two oil holes 700 penetrate the small end portion 70 in the radial direction. The rod portion 72 connects the large end portion 71 and the small end portion 70.

  As shown in FIG. 1, when the connecting rod 7 is viewed from the front, the extending direction of the center line A passing through the center a1 of the small end portion 70 and the center a2 of the large end portion 71 is “vertical direction”, and is viewed from the center a2. The center a1 side is defined as “upper side”, and the center a2 side as viewed from the center a1 is defined as “lower side”.

  As shown in FIGS. 2 to 6, the bearing 1 includes a bush 2 and a thermal expansion member 6. The bearing 1 is a sliding bearing. The bush 2 has a short-axis cylindrical shape. The bush 2 is disposed on the radially inner side of the small end portion 70. The bush 2 supports the piston pin 92 from below. A gap (oil clearance) B is secured between the inner peripheral surface 20 of the bush 2 and the outer peripheral surface 920 of the piston pin 92. A recess 201 is provided in the inner peripheral surface 20. As shown in FIGS. 3 to 6, the recess 201 is disposed in a lower portion of the inner peripheral surface 20. The recess 201 is disposed directly below the center of gravity G. The recess 201 is disposed at the center in the axial direction (front-rear direction) of the inner peripheral surface 20. The bush 2 is provided with two oil holes 21. The two oil holes 21 penetrate the bush 2 in the radial direction. The oil hole 21 is continuous with the oil hole 700 of the small end portion 70 in the radial direction. As shown in FIGS. 5 and 6, the lubricating oil O is supplied to the inner peripheral surface 20 through the oil holes 700 and 21 during normal operation and at a high temperature. The lubricating oil O forms an oil film in the gap B.

  The thermal expansion member 6 is disposed in the recess 201. The thermal expansion member 6 includes a support portion 60. The support part 60 is disposed below the center of gravity G of the bush 2. As shown by dotted line hatching in FIG. 4, the support portion 60 can support the outer peripheral surface 920 of the piston pin 92 from below. The thermal expansion member 6 is made of resin. On the other hand, the bush 2 is made of a copper-based alloy. The thermal expansion coefficient of the resin is larger than that of the copper-based alloy.

  Here, the center of gravity G of the bush 2 is a figure center of gravity of a circle formed by the inner peripheral surface 20 when the bush 2 is viewed from the axial direction (the front side of the connecting rod 7). In the present embodiment, the center of gravity G coincides with the center a <b> 1 of the small end portion 70.

  The form in which the support part 60 supports the outer peripheral surface 920 includes a form in which the support part 60 directly supports the outer peripheral face 920 by contacting the outer peripheral face 920. Moreover, the form which the support part 60 supports the outer peripheral surface 920 indirectly through the oil film by the lubricating oil O is included. The same applies to the form in which the inner peripheral surface 20 supports the outer peripheral surface 920.

[Bearing movement]
Next, the movement of the bearing of this embodiment will be described. When the engine shown in FIG. 3 is stopped, the support portion 60 of the thermal expansion member 6 is disposed below the inner peripheral surface 20. The inner peripheral surface 20 supports the outer peripheral surface 920 of the piston pin 92 from below. Lubricating oil O is accumulated on the upper side of the support portion 60 so as to be surrounded by the side surface of the recess 201. The thermal expansion member 6 is in close contact with the recess 201. For this reason, when the temperature around the bearing 1 rises, the thermal expansion member 6 thermally expands upward.

  During normal operation shown in FIG. 5 (after completion of warm-up operation), the temperature around the bearing 1 rises compared to when the engine is stopped shown in FIG. For this reason, the thermal expansion member 6 thermally expands upward until the support portion 60 and the inner peripheral surface 20 are flush with each other. The lubricating oil O that has accumulated on the upper side of the support portion 60 is supplied to the inner peripheral surface 20.

  The support part 60 has a curved surface shape. The curvature of the support part 60 is the same as the curvature of the inner peripheral surface 20. Depending on the load situation around the piston pin 92, the support portion 60 can support the outer peripheral surface 920 of the piston pin 92 together with the inner peripheral surface 20 from below.

  As shown by a dotted line in FIG. 5, at the beginning of the assembly of the bearing 1, the support portion 60 has a planar shape. Further, at the beginning of the assembly of the bearing 1, the support portion 60 protrudes upward from the inner peripheral surface 20 during the normal operation shown in FIG. 5. However, the support portion 60 is gradually worn by sliding with the piston pin 92. For this reason, as shown by a solid line in FIG. 5, the support portion 60 becomes curved as time passes.

  At the time of high temperature shown in FIG. 6, the temperature around the bearing 1 rises as compared with the time of normal operation shown in FIG. For this reason, the thermal expansion member 6 is thermally expanded upward. The support portion 60 protrudes upward from the inner peripheral surface 20. The support unit 60 can support the outer peripheral surface 920 of the piston pin 92 from below according to the load situation around the piston pin 92. When the support part 60 supports the outer peripheral surface 920, the lower part of the inner peripheral surface 20 and the lower part of the outer peripheral surface 920 are separated from each other. For this reason, the lubricating oil O can be supplied to the lower portion of the gap B.

  Thus, the thermal expansion member 6 is thermally deformed according to the temperature condition around the bearing 1. For this reason, the bearing 1 is in the first support state (the piston pin 92 is supported only by the inner peripheral surface 20) shown in FIG. 3, and in the second support state (the piston pin 92 is supported by the inner peripheral surface 20 and the support portion 60) shown in FIG. ) And the lift state shown in FIG. 6 (the piston pin 92 is supported only by the support portion 60).

[Function and effect]
Next, the effect of the bearing and connecting rod assembly of this embodiment will be described. As illustrated in FIGS. 3, 5, and 6, the support portion 60 is disposed below the center of gravity G of the bush 2. Further, the thermal expansion member 6 can be thermally deformed according to the temperature around the bearing 1. For this reason, as shown in FIG. 6, when the thermal expansion member 6 protrudes (thermal expansion) from the recess 201, the support portion 60 can support the piston pin 92. Therefore, the piston pin 92 can be floated with respect to the inner peripheral surface 20 of the bush 2. Therefore, the lubricating oil O can be easily supplied to the lower portion of the inner peripheral surface 20 of the bush 2.

  In addition, as shown in FIGS. 3, 5, and 6, the support portion 60 moves in the vertical direction due to thermal deformation of the thermal expansion member 6. For this reason, the mechanism which moves the support part 60 up and down is simple. Therefore, when shifting from the normal operation shown in FIG. 5 to the high temperature shown in FIG. 6, the bearing 1 can be reliably switched from the second support state to the lift state.

  Also, if the engine shown in FIG. 3 is stopped, a gap (for example, a gap between the circumferential side surface of the thermal expansion member 6 and the circumferential side surface of the recess 201, heat If there is a gap between the axial side surface of the expansion member 6 and the axial side surface of the recess 201, a clearance between the lower surface of the thermal expansion member 6 and the bottom surface of the recess 201, the temperature around the bearing 1 increases. At this time, the thermal expansion member 6 expands in a direction to fill the gap. For this reason, it becomes difficult for the thermal expansion member 6 to expand upward.

  In this regard, according to the bearing 1 of the present embodiment, the thermal expansion member 6 is in close contact with the recess 201 when the engine is stopped as shown in FIG. That is, in the state where the temperature around the bearing 1 is the lowest, the thermal expansion member 6 is in close contact with the recess 201. For this reason, the expansion direction of the thermal expansion member 6 when the temperature around the bearing 1 rises can be oriented upward. Therefore, when shifting from the normal operation shown in FIG. 5 to the high temperature shown in FIG. 6, the bearing 1 can be reliably switched from the second support state to the lift state. Further, when shifting from the time of the engine stop shown in FIG. 3 to the time of the normal operation shown in FIG. 5, the lubricating oil O accumulated on the upper side of the support portion 60 can be supplied to the inner peripheral surface 20.

  Moreover, according to the bearing 1 of this embodiment, the protrusion amount of the support part 60 from the recessed part 201 in the lift state shown in FIG. 6 can be easily adjusted by selecting the material of the thermal expansion member 6. . Similarly, in the first support state shown in FIG. 3, the amount of immersion of the support portion 60 into the recess 201 (the amount of lubricating oil O stored) can be easily adjusted by selecting the material of the thermal expansion member 6. Can do. Further, the thermal expansion member 6 is less likely to be elastically deformed as compared with a spring member (for example, a leaf spring, a coil spring, a disc spring, or the like). For this reason, in the lift state shown in FIG. 6, the protrusion amount of the support part 60 hardly changes. Therefore, the piston pin 92 can be continuously floated with respect to the inner peripheral surface 20 of the bush 2 at a high temperature.

[Others]
The embodiment of the bearing and connecting rod assembly of the present invention has been described above. However, the embodiment is not particularly limited to the above embodiment. Various modifications and improvements that can be made by those skilled in the art are also possible.

  The temperature range in which the bearing 1 is in the lift state, the first support state, and the second support state is not particularly limited. For example, the bearing 1 may be in the second support state when the engine is stopped. Further, the bearing 1 may be in a lift state during normal operation. The material of the thermal expansion member 6 is not particularly limited. For example, it may be a resin such as a polyamideimide (PAI) resin, a polyimide (PI) resin, a phenol (PR) resin, a polyacetal (POM) resin, a polyetheretherketone (PEEK) resin, or a polyphenylene sulfide (PPS) resin. . The thermal expansion member 6 may be a metal. The thermal expansion coefficient of the material forming the thermal expansion member 6 only needs to be larger than the thermal expansion coefficient of the material forming the bush 2.

  Both the side surface of the thermal expansion member 6 and the side surface of the concave portion 201 facing the side surface may be tapered so as to be pointed from the lower side toward the upper side. If it carries out like this, when switching from a 1st support state to a 2nd support state, and when switching from a 2nd support state to a lift state, it is easy to orient the expansion direction of the thermal expansion member 6 to an upper side.

  The cause at the time of the high temperature shown in FIG. 6, that is, the cause of the increase in the temperature around the bearing 1 relative to the normal operation shown in FIG. For example, engine overheating or the like due to a malfunction of a cooling system or a lubricating oil system.

  The number and positions of the oil holes 21 shown in FIG. 3 are not particularly limited. For example, the oil hole 21 may be opened in the lower portion of the inner peripheral surface 20. Further, the oil hole 21 may not be disposed in the bush 2. The same applies to the oil hole 700. The supply path for supplying the lubricating oil O to the inner peripheral surface 20 is not particularly limited. The type of engine 9 is not particularly limited. The bearing and connecting rod assembly of the present invention may be used in a gasoline engine.

  1: bearing, 2: bush, 20: inner peripheral surface, 201: recessed portion, 21: oil hole, 6: thermal expansion member, 60: support portion, 7: connecting rod, 70: small end portion, 700: oil hole, 71 : Large end, 710: connecting rod bearing, 72: rod, 8: connecting rod assembly, 9: engine, 90: cylinder, 91: piston, 92: piston pin, 920: outer peripheral surface, 93: crankshaft, 930: main Journal, 931: Crank pin, 932: Crank arm, A: Center line, B: Gap, C: Combustion chamber, G: Center of gravity, O: Lubricating oil, a1-a3: Center

Claims (4)

The direction passing through the small end and the large end of the connecting rod is the vertical direction, the small end side is the upper side, the large end side is the lower side,
A cylindrical bush arranged at the small end and supporting the piston pin and having a recess on the inner peripheral surface;
A thermal expansion member having a thermal expansion coefficient larger than that of the bush, disposed in the concave portion so as to protrude from the concave portion due to thermal expansion, and having a support portion capable of supporting the piston pin;
With
The said support part is a bearing arrange | positioned in the said lower side rather than the gravity center of the said bush. During normal operation, the support portion of the thermal expansion member is flush with the inner peripheral surface of the bush.
The bearing according to claim 1, wherein the support portion of the thermal expansion member protrudes from the inner peripheral surface of the bush when the temperature is higher than that during the normal operation.   The bearing according to claim 1, wherein the thermal expansion member is in close contact with the recess.   A connecting rod assembly comprising: the bearing according to claim 1; and a connecting rod on which the bearing is disposed at a small end.

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