JP2012127458A - Plain bearing structure of shaft member - Google Patents

Abstract

A sliding bearing structure of a shaft member that can reduce sliding resistance at a low temperature at an early stage and does not hinder a cooling action by lubricating oil at a high temperature is provided.
In a sliding bearing structure of a shaft member and a shaft member in which lubricating oil is supplied between sliding surfaces of a relatively rotatable shaft member and a bearing member 12b, the lubricating oil from between the sliding surfaces is provided on both sides of the bearing member 12b. The seal member 18 is restricted between the sliding surfaces as the lubricating oil temperature between the sliding surfaces rises from the low temperature state (A) to the high temperature state (C). It is formed of a member that is deformed so as to reduce the amount of lubricating oil.
[Selection] Figure 2

Description

  The present invention relates to a sliding bearing structure for a shaft member, and more particularly to a sliding bearing structure for a shaft member used in an internal combustion engine for automobiles.

  Generally, in such a sliding bearing structure of a shaft member, lubricating oil is supplied to the clearance between the sliding surfaces of the shaft member and the bearing member to form a lubricating oil film, and the load is supported by the oil film pressure generated in the lubricating oil film. Thus, the friction loss is reduced, and wear and seizure prevention are brought about.

  Conventionally, in order to keep the lubricating oil in the clearance between the sliding surfaces, a technique has been proposed in which a large number of fine grooves or striations are formed in parallel in the circumferential direction on the inner peripheral surface of the bearing.

  Further, in Patent Document 1, a half cylindrical bearing is used in order to prevent the occurrence of local high oil film pressure by filling the shaft and the bearing metal with lubricating oil to prevent cracking and damage of the bearing metal. Provided with seal devices that prevent leakage of lubricating oil flowing out from the inside of the bearing in the axial direction at both ends in the bearing width direction of the metal, and oil supply holes and bearings for introducing the lubricating oil into the bearing in at least one of the upper and lower bearing metals Disclosed is a plain bearing for large marine diesel engines that has an oil drain hole that discharges deteriorated lubricating oil to the outside, and a throttle device that adjusts the amount of lubricating oil discharged from the oil drain hole. Has been.

Japanese Patent Laid-Open No. 9-203212

  By the way, in an internal combustion engine for automobiles and the like, after completion of the warm-up, a sliding resistance (friction loss) is not so large in the slide bearing structure, but for example, from an extremely low temperature (about −30 ° C.) to room temperature (20 A very large sliding resistance is generated at the time of low temperature starting at about -25 ° C. This is because the viscosity of the lubricating oil depends on the temperature, and the viscosity rapidly increases at such a low temperature.

  Therefore, in order to lower the sliding resistance at such a low temperature, it is desired to increase the temperature of the bearing portion at an early stage. However, at such a low temperature, the temperature of the supplied lubricating oil itself is low and the temperature increase is delayed. Even if the lubricating oil temperature rises due to the heat generated by the resistance, the lubricating oil flows out from the bearing portion immediately, so that there is a problem that it takes time to raise the temperature of the bearing portion.

  On the other hand, at a high temperature (about 80 to 120 ° C.) during steady operation or high-speed operation after the completion of warm-up, if there is not a sufficient amount of lubricating oil, an excessive temperature rise will be caused, and problems such as seizure will occur. There is a need for a plain bearing structure that can exhibit sufficient cooling capacity at high temperatures.

  The slide bearing disclosed in the above-mentioned Patent Document 1 is a slide bearing for supporting a crankshaft of a large marine diesel engine where a large load fluctuation occurs, and a lubricating oil is filled between the shaft and the bearing metal. In order to eliminate the occurrence of local high oil film pressure and prevent cracking and damage to the bearing metal, a seal device is provided to prevent leakage of lubricating oil flowing out from the bearing in the axial direction. It is not intended for the early rise of.

  Therefore, the present invention has been made in view of the above-described conventional situation, and it is possible to reduce sliding resistance at a low temperature at an early stage, and a sliding bearing structure of a shaft member that does not hinder the cooling action by lubricating oil at a high temperature. The purpose is to provide.

  In order to achieve the above object, one aspect of a sliding bearing structure for a shaft member according to the present invention is a sliding of a shaft member that is relatively rotatable and a shaft member that is supplied with lubricating oil between sliding surfaces of the bearing member. In the bearing structure, the seal member is provided on both sides of the bearing member to limit the outflow of the lubricating oil from between the sliding surfaces, and the sealing member has a temperature of the lubricating oil between the sliding surfaces from a low temperature state to a high temperature state. It is formed of a member that is deformed so that the amount of lubricating oil held between the sliding surfaces decreases as it rises.

  In this specification, “low temperature state” means that the temperature of the lubricating oil between the sliding surfaces is from the above-mentioned extremely low temperature (about −30 ° C.) to room temperature (about 20 to 25 ° C.), and “high temperature” The “state” means a state where the temperature of the lubricating oil between the sliding surfaces is at a high temperature (about 80 to 120 ° C.) in the steady operation and the high speed operation after the completion of the warm-up described above.

  According to the sliding bearing structure of the shaft member according to this aspect, the sealing member has an amount of lubricating oil retained between the sliding surfaces as the temperature of the lubricating oil between the sliding surfaces rises from the low temperature state to the high temperature state. Deforms to decrease. Therefore, at low temperatures, the amount of lubricating oil supplied between the sliding surfaces of the shaft member and the bearing member leaks from both ends of the bearing portion, so the lubricating oil held in the bearing portion is sheared and heated. As a result, the temperature of the lubricating oil and the bearing portion rises early. Therefore, the sliding resistance can be reduced early. On the other hand, when the temperature is high, the seal member is deformed so as to reduce the amount of lubricating oil held between the sliding surfaces. Therefore, the amount of lubricating oil leaking from both ends of the bearing portion is not limited, and the outflow is promoted. Therefore, the cooling by the lubricating oil and the seizing prevention effect are exhibited. In this way, with a simple configuration that employs a seal member that deforms according to the temperature, the sliding resistance at low temperatures can be reduced early, and the shaft that does not hinder the cooling action by lubricating oil at high temperatures A sliding bearing structure of the member can be obtained.

  Here, in the above aspect, the seal member may be formed of a material whose hardness decreases as the temperature of the lubricating oil between the sliding surfaces increases from a low temperature state to a high temperature state.

  According to this aspect, when the temperature of the lubricating oil between the sliding surfaces is in a low temperature state, the seal member has a high hardness and is not easily deformed. Therefore, the lubricating oil supplied between the sliding surfaces of the shaft member and the bearing member The amount of leakage from both ends of the bearing portion is limited. On the other hand, since the hardness of the seal member is low and easily deformed when in a high temperature state, the amount of lubricating oil leaking from both ends of the bearing portion is not limited, and the outflow is promoted.

  In the above aspect, the seal member may be formed of a material having a negative coefficient of thermal expansion in a predetermined temperature range from a low temperature state to a high temperature state of the lubricating oil between the sliding surfaces.

  According to this aspect, since the seal member is formed of a material having a negative coefficient of thermal expansion, the seal member expands and deforms in a low temperature state, and the outflow of lubricating oil from between the sliding surfaces is limited. On the other hand, the seal member contracts and deforms in a high temperature state, and the outflow of lubricating oil from between the sliding surfaces is not limited.

  According to the present invention, it is possible to obtain a sliding bearing structure of a shaft member that can reduce sliding resistance at a low temperature at an early stage with a simple configuration and does not hinder a cooling action by lubricating oil at a high temperature.

It is a cross-sectional view showing an embodiment of a sliding bearing structure of a shaft member according to the present invention. It is a longitudinal cross-sectional view which shows the lower half of 1st Embodiment of the sliding bearing structure of the shaft member of FIG. 1, (A) is at low temperature, (B) is on the way from low temperature to high temperature, (C) is high temperature It's time. It is a perspective view which shows the sealing member used for 1st Embodiment of the sliding bearing structure of the shaft member which concerns on this invention. It is the (A) perspective view and (B) partial sectional view which show the more exact relationship between the seal member used for 2nd Embodiment of the sliding bearing structure of the shaft member which concerns on this invention, and a shaft member. It is a longitudinal cross-sectional view which shows the lower half of 2nd Embodiment of the sliding bearing structure of the shaft member which concerns on this invention, (A) is at the time of low temperature, (B) is at the time of high temperature. It is the longitudinal cross-sectional view of the lower half which shows 3rd Embodiment of the attachment of the sealing member in the sliding bearing structure of the shaft member which concerns on this invention, (A) is a right-and-left separate body, (B) is a right-and-left integrated sealing member. It is.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
First, in an embodiment in which the present invention is applied to a plain bearing structure for a crankshaft of an engine, the first embodiment will be described with reference to FIGS. 1 and 2, 10 is a main journal of a crankshaft as a rotating shaft member, and 12 is a journal bearing as a bearing member for rotatably supporting the main journal 10. The journal bearing 12 is accommodated in a housing 14 including an upper housing 14a formed in a cylinder block (not shown) and a lower housing 14b formed in a bearing cap fastened thereto, and is fixed by being sandwiched.

  In this embodiment, the journal bearing 12 includes an upper journal bearing 12a and a lower journal bearing 12b. The upper journal bearing 12a and the lower journal bearing 12b are configured by attaching an upper lining 12a2 and a lower lining 12b2 to the upper back metal 12a1 and the lower back metal 12b1, respectively (see FIG. 2). (Only the lower journal bearing 12b composed of the lower backing metal 12b1 and the lower lining 12b2 is shown). The main journal 10 and the journal bearing 12 composed of the upper journal bearing 12a and the lower journal bearing 12b are set so as to have a predetermined clearance over their entire circumference, and an oil passage is provided for this clearance. 15 and the upper journal bearing 12a are formed, and lubricating oil is supplied through oil holes.

  Therefore, in the first embodiment, the annular grooves 16 are formed in the outer peripheral portion of the main journal 10 as the shaft member at positions corresponding to both end portions of the journal bearing 12 (note that FIG. 2 shows only the lower half of the main journal 10 and the lower journal bearing 12b). A seal member 18 is disposed in the annular grooves 16.

  As shown in FIG. 3, the seal member 18 has an annular shape having a substantially rectangular cross section with a width w and a thickness t, and an abutment 18a is formed so as to be convenient for mounting on the bearing portion. The seal member 18 is positioned such that the inner diameter portion thereof is mounted in the annular groove 16 and the side surfaces of the outer diameter portion are in contact with both end portions of the journal bearing 12 at a low temperature. The seal member 18 is made of a material whose hardness decreases as the temperature of the lubricating oil between the sliding surfaces of the main journal 10 and the journal bearing 12 increases from a low temperature state to a high temperature state. An example of the material having such properties is fluoro rubber, and the seal member 18 is made of fluoro rubber.

  According to the sliding bearing structure of the shaft member according to the first embodiment, the temperature of the lubricating oil between the sliding surfaces of the main journal 10 and the journal bearing 12 increases from the low temperature state to the high temperature state. As a result, the amount of lubricating oil retained between the sliding surfaces is reduced. That is, when the temperature of the lubricating oil between the sliding surfaces is in a low temperature state, the seal member 18 has a high hardness and is not easily deformed. Therefore, the seal member 18 is shown in FIG. Thus, the side surface of the outer diameter portion is maintained so as to substantially contact both end portions of the journal bearing 12. Therefore, the amount of the lubricating oil supplied between the sliding surfaces of the main journal 10 and the journal bearing 12 is limited by the amount of leakage from both ends of the bearing portion, and is held in the bearing portion by the relative rotation of the main journal 10 and the journal bearing 12. The applied lubricating oil is sheared and heated, and the temperature of the lubricating oil and, in turn, the bearing portion rises early.

  On the other hand, as the temperature from the low temperature state to the high temperature state is reached, the hardness of the seal member decreases and the seal member is easily deformed, so that the amount of lubricating oil leaking from both ends of the bearing portion is not limited. That is, when the temperature of the lubricating oil between the sliding surfaces is on the way from the low temperature state to the high temperature state, the seal member 18 has a moderate amount of deformation due to the oil pressure of the lubricating oil, as shown in FIG. On the other hand, in the high temperature state, as shown in FIG. 2C, the amount of deformation of the seal member 18 due to the oil pressure of the lubricating oil increases. Therefore, the gap between the side surface of the outer diameter portion of the seal member 18 and both end portions of the journal bearing 12 is increased, and the amount of lubricating oil leaking from both ends of the bearing portion is not limited and the outflow is promoted. Therefore, the cooling by the lubricating oil and the seizing prevention effect are exhibited.

  Next, a second embodiment of the shaft member slide bearing structure according to the present invention will be described with reference to FIGS. The second embodiment is different from the above-described embodiment in that the seal member has a negative coefficient of thermal expansion in a predetermined temperature range from a low temperature state to a high temperature state of the lubricating oil between the sliding surfaces. Therefore, the same functional parts are denoted by the same reference numerals as those used in the previous embodiment, and redundant explanation is avoided.

  In the second embodiment, as shown in FIGS. 4A and 4B, a seal member 18 ′ having a substantially rectangular cross section having a width w and a thickness t is mounted in the annular groove 16 of the main journal 10. The At this time, the dimensions including the depth of the annular groove 16 and the width w and the thickness t of the seal member 18 are as shown in FIG. 5A at the outer diameter portion of the thermally expanded seal member 18 ′. As shown in FIG. 5 (B), the side surface overlaps with and abuts the end of the journal bearing 12 so that the outer diameter portion of the heat-shrinkable seal member 18 ′ is substantially equal to the outer diameter of the main journal 10. Is set.

For example, zirconium tungstate (ZrW ₂ O ₈ ) may be used as the material having the above negative thermal expansion coefficient.

  According to the present embodiment configured as described above, the seal member 18 'is in an expanded state at a low temperature when the engine is in a cold state, and the side surface of the outer diameter portion is shown in FIG. As shown in the drawing, the state in which the journal bearing 12 is in contact with the end of the journal bearing 12, in other words, the protruding thickness t ′ of the seal member 18 ′ from the outer diameter of the main journal 10 is determined by the clearance between the main journal 10 and the journal bearing 12. Is also in a large state. In this state, the lubricant supplied through the oil passage 15 to the clearance between the sliding surfaces of the main journal 10 and the journal bearing 12 is blocked by the seal member 18 ′ in the expanded state, and the journal bearing 12, the amount of lubricating oil leakage from both ends of the bearing portion is limited. Accordingly, the lubricating oil held in the bearing portion between the seal members 18 ′ on both sides is sheared with the rotation of the main journal 10 to generate heat, and as a result, the temperature of the bearing portion rises early. Become.

  On the other hand, when the engine is warmed up, the seal member 18 ′ is in a heat-shrinkable state, and as shown in FIG. 5B, the outer circumferential portion of the annular groove 16 formed on the outer peripheral surface of the main journal 10. The inner journal is deformed so as to be the same as the outer diameter of the main journal 10. In other words, it contracts and deforms so that the protruding thickness t ′ becomes zero or negative. In this state, the lubricating oil supplied through the oil passage 15 is not prevented from flowing out by the seal member 18 ′ in the contracted state, and the amount of lubricating oil leakage from both ends of the bearing portion by the journal bearing 12 is limited. As a result, the bearing is cooled by the lubricating oil.

  Next, a third embodiment of the sliding bearing structure for a shaft member according to the present invention will be described with reference to FIG. Since the third embodiment is different from the first embodiment described above only in the way the seal member is attached, the same functional parts are denoted by the same reference numerals as those used in the previous embodiment. Avoid.

  That is, in the third embodiment, the annular groove 20 for attaching the seal member is formed in the housing 14 including the upper housing 14a formed in the cylinder block and the lower housing 14b formed in the bearing cap fastened thereto. It is formed. In the third embodiment, a seal member 18 ″ having an attachment piece portion extending in the axial direction on the outer peripheral portion is used, and the attachment piece portion 18 ″ a of the seal member 18 ″ is used as the housing 14. After being mounted in the mounting annular groove 20, the journal bearing 12 is mounted and the seal member 18 "is fixed. As in the first embodiment, the seal member 18 ″ is formed of a material (fluoro rubber) whose hardness decreases as the temperature rises from a low temperature state to a high temperature state. Here, FIG. FIG. 6B shows the case where the left and right separate seal members 18 ″ and FIG. 6B are the left and right integrated seal members 18 ″, respectively, and the above-described annular groove 20 for attaching the seal member is formed. .

  In this third embodiment, in any of the forms shown in FIGS. 6A and 6B, the seal member 18 ″ can be attached to the bearing member side and then attached to the shaft member, so that the assemblability is improved. Since the inner diameter portion of the seal member 18 ″ contacts with the outer peripheral portion of the main journal 10 as the shaft member at low temperatures, the inner diameter portion of the seal member 18 ″ has almost no clearance from the main journal 10. Therefore, when the viscosity of the lubricating oil is high and the temperature is low, the oil pressure of the supplied lubricating oil is also high, but the sealing member 18 ″ is high in hardness and less deformed. Since the clearance with the journal 10 is kept small, the outflow of the lubricating oil from the bearing portion is limited, and the temperature of the bearing portion can be increased. When the engine is stopped, the lubricating oil can be prevented from flowing out of the bearing portion for a long time. Further, at high temperatures, the seal member 18 ″ has a low hardness and a large deformation, and the outflow is promoted. Street.

  In the above description, the embodiment in which the present invention is applied to the bearing portion of the main journal of the crankshaft has been described. However, the slide bearing structure of other parts, for example, the pin portion of the crankshaft, the main journal bearing portion of the camshaft Needless to say, the present invention can be applied to the above.

10 Main journal (shaft member)
12 Journal bearing
12a upper journal bearing 12b lower journal bearing 14 housing 14a upper housing 14b lower housing 16 annular groove 18, 18 ', 18 "seal member 20 annular groove

Claims (3)

In the sliding bearing structure of the shaft member to which lubricating oil is supplied between the sliding surfaces of the shaft member and the bearing member that are relatively rotatable,
A seal member that restricts outflow of lubricating oil from between the sliding surfaces on both sides of the bearing member;
The seal member is formed of a member that is deformed so that the amount of lubricant retained between the sliding surfaces decreases as the temperature of the lubricating oil between the sliding surfaces increases from a low temperature state to a high temperature state. A sliding bearing structure for a shaft member, characterized in that   2. The shaft according to claim 1, wherein the seal member is made of a material whose hardness decreases as the temperature of the lubricating oil between the sliding surfaces increases from a low temperature state to a high temperature state. Sliding bearing structure of members.   The said sealing member is formed with the material which has a negative coefficient of thermal expansion in the predetermined temperature range from the low temperature state of the lubricating oil between the said sliding surfaces to a high temperature state. A plain bearing structure of a shaft member.

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