JP5564008B2 - Slide bearing structure of shaft member - Google Patents

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.

  And in patent document 1, a recessed part is formed in the bearing member which a rotating shaft contacts, and the bearing part is in the cold state by embedding a contracting member made of a material having a higher thermal expansion coefficient than the bearing member in the recessed part. Occasionally, the recess is an oil reservoir, and when heated, the contracting member expands to form a flush sliding surface to obtain good lubrication characteristics and reduce surface pressure to improve seizure resistance. A structure is disclosed.

JP 2007-285456 A

  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.

  In the bearing structure disclosed in Patent Document 1 described above, a shrinkage member made of a material having a thermal expansion coefficient larger than that of the bearing member is embedded in a recess formed in the bearing member with which the rotating shaft contacts, and the bearing portion is cooled. In this state, the concave portion becomes an oil sump, and is not intended to raise the temperature of the bearing portion early.

  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 bearing member is composed of two halves, each of which is formed with circumferential grooves having a predetermined axial width at both ends in the axial direction on the inner peripheral surface of each halved part. The seal member is arranged at a position corresponding to the circumferential groove, and connects both the circumferential ends of one half part and the circumferential ends of the other half part to each other. A seal member having a connecting portion that is connected to each other, and the seal members shrink so that the inner diameter thereof is smaller than the inner diameter of the bearing member at a low temperature and the bearing member is connected at a high temperature. Same or larger than inner diameter Characterized in that it is formed of a material having a thermal expansion coefficient of sea urchin inflated.

  In this specification, “at low temperature” means that the temperature of the bearing portion is from the above-mentioned extremely low temperature (about −30 ° C.) to room temperature (about 20 to 25 ° C.), and “at high temperature” Similarly, it means a state in which the temperature of the bearing portion is at a high temperature (about 80 to 120 ° C.) during steady operation or high-speed operation after the completion of the warm-up described above.

  According to the sliding bearing structure of the shaft member of this embodiment, the bearing member and the seal member are composed of two halves, so that the shaft member or the bearing member can be easily assembled. In particular, since the seal member is composed of two halved parts, it is not necessary to assemble the bearing member after the seal member is first attached to the shaft member, and the assemblability is improved. Further, it is unnecessary to align the seal member with the circumferential groove of the bearing member, and the bearing member can be prevented from biting the seal member.

  Further, in this embodiment, the seal member disposed at a position corresponding to the circumferential groove having a predetermined axial width formed at both axial end portions on the inner peripheral surface of the bearing member is one half-part. Both ends in the circumferential direction of the sealing member and both ends in the circumferential direction of the sealing member of the other halved part are connected to each other by the connecting portion. The seal members formed of a material having a predetermined coefficient of thermal expansion contract with each other so that the inner diameter becomes smaller than the inner diameter of the bearing member at a low temperature when they are connected to each other. It expands and deforms to be the same as or larger than the inner diameter. Therefore, at a low temperature, the clearance between the seal member and the shaft member becomes smaller than the clearance between the shaft member and the bearing member, and leaks from both ends of the bearing portion of the lubricating oil supplied between the sliding surfaces of the shaft member and the bearing member. Since the amount is limited, the lubricating oil held in the bearing is sheared and heated, and the temperature of the bearing rises early. On the other hand, when the temperature is high, the clearance between the seal member and the shaft member becomes the same as or larger than the clearance between the shaft member and the bearing member, and the amount of lubricating oil leaking from both ends of the bearing portion is not limited. Played.

  Here, in the above aspect, the connecting portion of the seal member includes an axially extending portion extending in the axial direction, and a main body portion having a flat surface in the axial direction and a circular arc surface in the circumferential direction at a predetermined angle in the axis orthogonal direction.鉤 1 extending and having an angled continuous portion continuous with the base end portion of the axially extending portion, and both circumferential ends of the circumferential groove of the bearing member are tapered. May be. According to this configuration, by accommodating the hook-shaped connecting portions of the seal member with respect to the tapered shape portions at both ends in the circumferential direction of the circumferential groove of the bearing member, the positioning of both is facilitated and the assembling property is improved.

  Moreover, it is preferable that the axial direction magnitude | size of the said axial direction extension part of the said hook-shaped connection part is larger than the axial direction width | variety of the said circumferential groove | channel of the said bearing member. According to this configuration, the seal member is prevented from sliding greatly in the circumferential direction in the circumferential groove due to the interference between the axially extending portion and the circumferential groove end portion, so that the handling is easy.

  Further, the distance between the distal end portion of the axially extending portion and the axially flat surface of the main body portion that is far from the distal end portion is greater than half the axial width of the circumferential groove. It is preferable. According to this configuration, after the one axially extending portion and the other axially extending portion of the connecting portion of the seal member are engaged and connected to each other, the half-separated seal members are displaced from each other in the axial direction. Even so, the tip portions of the axially extending portions do not come apart from each other, so that the sealing member is reliably held.

  Further, when the taper angle of the tapered shape at both circumferential ends of the circumferential groove is Θ2, the taper angle Θ2 is preferably larger than the angle Θ1 of the angled continuous portion. According to this embodiment, when the hook-shaped connecting portions at both ends of the seal member are engaged with each other and connected, the tapered continuous ends of the circumferential groove in which the angled continuous portion having the angle Θ1 has the taper angle Θ2 Since it is permitted to move in the axial direction within the part, the assembling property is improved.

  According to the present invention, the sliding resistance at a low temperature can be reduced early, and the cooling action by the lubricating oil at a high temperature is not hindered.

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 the sliding bearing structure of the shaft member of FIG. It is (A) perspective view which shows an example of the seal member used for embodiment of the sliding bearing structure of the shaft member which concerns on this invention, (B) The expanded view of the edge part. (A) A developed view of the end portion of the bearing member used in the embodiment of the sliding bearing structure of the shaft member according to the present invention, (B) a partially developed view when the seal member is assembled to the bearing member, and ( C) It is the partial perspective view similarly. FIG. 5 is a partial development explanatory view showing assembling procedures (A) to (C) in the embodiment of the sliding bearing structure of the shaft member according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a cross-sectional view which shows embodiment of this invention, (A) shows the time of extremely low temperature, (B) shows the time of low temperature of about room temperature, and (C) shows the time of high temperature.

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

  First, an embodiment in which the present invention is applied to a plain bearing structure for an engine crankshaft 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 bearing housing 14 including an upper housing 14U formed in a cylinder block (not shown) and a lower housing 14L formed in a bearing cap fastened thereto, and is fixed by being sandwiched.

  In the present embodiment, the journal bearing 12 includes an upper journal bearing 12U and a lower journal bearing 12L. More specifically, the upper journal bearing 12U and the lower journal bearing 12L are configured by mounting the upper lining 12U2 and the lower lining 12L2 on the upper back metal 12U1 and the lower back metal 12L1, respectively (note that FIG. 2 shows only the lower journal bearing 12L composed of the lower back metal 12L1 and the lower lining 12L2). The main journal 10 and the journal bearing 12 constituted by the upper journal bearing 12U and the lower journal bearing 12L are set so as to have a predetermined clearance over their entire circumference, and the oil passage is provided with respect to this clearance. 15 and the upper journal bearing 12U (or the lower journal bearing 12L may be formed), and lubricating oil is supplied through oil holes.

  Therefore, the journal bearing 12 as the bearing member in the present embodiment has a predetermined axial width b at both axial ends of the inner sliding surfaces of the upper journal bearing 12U and the lower journal bearing 12L. A circumferential groove 16 (consisting of an upper circumferential groove 16U and a lower circumferential groove 16L) is continuously formed (note that only the lower journal bearing 12L and the lower circumferential groove 16L are shown in FIG. 2). It is shown). Then, at positions corresponding to the circumferential grooves 16, the seal member 18 (from the upper seal member 18U and the lower seal member 18L), which is composed of two parts divided separately from the main journal 10 and the journal bearing 12, is provided. Arranged).

  As shown in FIG. 3A, each of the half-upper seal member 18U and the lower seal member 18L has a flat surface on both sides in the axial direction and an arc surface in the circumferential direction, and has a width w and a thickness. The upper body part 18UB and the lower body part 18LB having a substantially rectangular cross section t, and the upper connection part 18UC and the lower connection part 18LC formed at the respective circumferential ends of the respective parts are configured. Each of the upper connecting portion 18UC and the lower connecting portion 18LC includes an upper angled continuous portion 18UC1 extending at a predetermined angle in the direction perpendicular to the axis from the upper body portion 18UB and the lower body portion 18LB, and a lower angled portion. It is formed in a bowl shape having a continuous portion 18LC1, an upper axial extending portion 18UC2 and a lower axial extending portion 18LC2 extending in the axial direction from these end portions. In the present embodiment, the upper angled continuous portion 18UC1 and the lower angled continuous portion 18LC1 extend from the upper body portion 18UB and the lower body portion 18LB with a predetermined angle Θ1 in the axis orthogonal direction, respectively. (See FIG. 3B, but only the lower seal member 18L is shown in FIG. 3B).

  Further, the upper circumferential bearing groove 16U and the lower circumferential groove 16L of the upper journal bearing 12U and the lower journal bearing 12L have respective upper ends of the upper sealing member 18U and the lower sealing member 18L at the circumferential ends. An upper enlarged portion 16UE and a lower enlarged portion 16LE are provided to accommodate the connecting portion 18UC and the lower connecting portion 18LC, respectively. In the present embodiment, the upper enlarged portion 16UE and the lower enlarged portion 16LE are formed in a tapered shape having inclined surfaces 16LEs and 16LEs that are equally inclined to the left and right, as shown in FIG. (Note that only the lower enlarged portion 16LE is shown in FIG. 4A). When this taper angle is Θ2, the taper angle Θ2 is formed larger than the angle Θ1 of the angled continuous portion.

  Here, when the dimension and arrangement relationship between the seal member 18 and the circumferential groove 16 of the bearing member are described, in the present embodiment, as shown in FIGS. Is set. Here, for convenience, only the relationship between the lower circumferential groove 16L of the lower journal bearing 12L and the lower seal member 18L will be typically described with reference to FIGS. 4B and 4C. It should be understood that the upper member can be similarly understood by those skilled in the art by replacing “L” used in reference to the lower member with “U”.

  Therefore, first, the lower axial extending portion 18LC2 of the flange-shaped connecting portion 18LC of the lower seal member 18L protrudes in the circumferential direction from the mating surface 12L1 of the lower journal bearing 12L with the upper journal bearing 12U. Thus, the circumferential dimension of the lower seal member 18L is set. In addition, an inclined surface 18LC3 of approximately 45 degrees with respect to the axis or a direction perpendicular to the axis is formed at the tip of the lower axial extending portion 18LC2. Furthermore, when the axial size (length) of the lower axial extension 18LC2 in the flange-shaped connecting portion 18LC of the lower seal member 18L is a, this length a is equal to the lower circumferential groove 16L. It is formed larger than the axial width b. When the length a is larger than the axial width b in this way, the seal member 18 slides greatly in the circumferential groove 16 in the circumferential direction due to interference between the axially extending portion and the circumferential groove end. Is prevented.

  Further, when the distance between the tip of the inclined surface 18LC3 of the lower axial extension 18LC2 and the flat surface far from the tip of the axial flat surface of the lower body 18LB is c, The distance c is formed larger than half of the axial width b of the lower circumferential groove 16L. According to this configuration, as will be described later, one of the connecting portions of the upper and lower seal members 18U, 18L, for example, the upper axial extension 18UC2 and the other, that is, the lower axial extension 18LC2 is provided. Even if the half upper and lower seal members 18U and 18L are displaced in the axial direction after being engaged with each other and connected, the distal ends of the axially extending portions 18UC2 and 18LC2 are not separated from each other (described later). (See FIG. 5C).

  In the plain bearing structure of the crankshaft of the engine according to the present embodiment configured as described above, for example, assembly is performed by the following procedure. That is, first, as shown in FIG. 5 (A), the upper and lower seal members 18U, 18L are respectively inserted into the circumferential grooves 16U, 16L of the upper and lower journal bearings 12U, 12L. , 18L flange-shaped connecting portions 18UC, 18LC with axially extending portions 18UC2, 18LC2 mounted so as to protrude from the mating surfaces 12U1, 12L1 of the upper and lower journal bearings 12U, 12L, respectively, and the upper and lower journal bearings 12U , 12L, the main journal 10 is interposed.

  Next, the upper and lower journal bearings 12U and 12L are brought close to each other as shown in FIG. 5B with the main journal 10 interposed therebetween. Then, the inclined surfaces 18UC3 and 18LC3 of approximately 45 degrees formed at the tip portions of the axially extending portions 18UC2 and 18LC2 come into contact with each other, and the upper and lower seal members 18U and 18L Due to its elasticity, it is deformed in the direction indicated by the white arrow in FIG. At this time, the angled continuous portions 18UC1 and 18LC1 extending at an angle Θ1 in the bowl-shaped connecting portions 18UC and 18LC are inclined toward the inclined surfaces 16UEs and 16LEs formed at the taper angle Θ2 larger than the angle Θ1. Deformation will be allowed. When the upper and lower journal bearings 12U and 12L are brought into contact with each other until the mating surfaces 12U1 and 12L1 come into contact with each other, the upper and lower seal members 18U and 18L that have been elastically deformed in the process so far are inclined surfaces. After overcoming 18UC3 and 18LC3, they are elastically restored, and as shown in FIG. 5C, the axially extending portions 18UC2 and 18LC2 are axially arranged so as not to be separated from each other in the circumferential direction when contracted as described later. And are connected to each other.

  Thereafter, the slide shaft structure of the crankshaft according to the present embodiment is, for example, after the upper journal bearing 12U assembled as described above is placed on the upper bearing housing 14U formed in a cylinder block (not shown), The bearing cap in which the lower bearing housing 14L is formed on the lower journal bearing 12L is fastened with a bolt or the like, so that the bearing cap 14 is assembled and supported.

  And the seal member 18 connected to each other in an annular shape has an outer diameter portion positioned in the circumferential groove 16 and has an inner diameter portion shown in FIG. 6A at an extremely low temperature of about −30 ° C. In other words, it is smaller than the inner diameter of the journal bearing 12, in other words, almost the same as the outer diameter of the main journal 10, and at room temperature of about 20 to 25 ° C., it is smaller than the inner diameter of the journal bearing 12 as shown in FIG. At a high temperature when the temperature rises, such as steady operation after completion of warm-up at about 80 to 120 ° C. or high speed operation, the inner diameter portion is the same as or larger than the inner diameter of the journal bearing 12 as shown in FIG. In other words, the seal member 18 is formed of a material (for example, polyimide resin) having a coefficient of thermal expansion that is deformed so as to be buried in the circumferential groove 16 by the thickness t. .

  The depth of the circumferential groove 16 is determined so that the inner diameter portion of the seal member 18 expanded at a high temperature is equal to or larger than the inner diameter of the journal bearing 12.

  According to the present embodiment configured as described above, the seal member 18 is in a contracted state at the time of starting at a low temperature when the engine is in a cold state, and the inner diameter portion thereof is shown in FIG. In this manner, the journal bearing 12 contracts smaller than the inner diameter, and the clearance between the seal member 18 and the main journal 10 is smaller than the clearance between the main journal 10 and the journal bearing 12. 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 a contracted state, and the journal bearing 12 This limits the amount of lubricating oil leakage from both ends of the bearing. Accordingly, the lubricating oil held in the bearing portion between the seal members 18 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.

  On the other hand, when the engine is warmed up at room temperature (for example, about 25 ° C.), the inner diameter of the annular seal member 18 is reduced as shown in FIG. It is in a slightly smaller state. Depending on the difference between the inner diameter of the annular seal member 18 and the inner diameter of the journal bearing 12 in this state, in other words, depending on how the amount of protrusion of the seal member 18 into the journal bearing 12 is set, the characteristics of the slide bearing will be described. It can be set. That is, if the amount of protrusion is set large, the warming-up effect of the bearing portion at a low temperature increases, but the cooling action at a high temperature described later decreases. And if the amount of protrusion is set small, it will become the reverse tendency. Therefore, this characteristic can be set so as to adapt to the use environment (destination) of the engine.

  Furthermore, at the time of high temperature after warming up, the annular seal member 18 is in a thermally expanded state, and is deformed so that its inner diameter is the same as or larger than the inner diameter of the journal bearing 12, as shown in FIG. 6 (C), the clearance between the annular seal member 18 and the main journal 10 is the same as or larger than the clearance between the main journal 10 and the journal bearing 12. 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 expanded state, and the amount of lubricating oil leaking from both ends of the bearing portion by the journal bearing 12 is not limited. Therefore, the cooling effect of the bearing portion by the lubricating oil is exhibited.

  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. Even in the case of a direct bearing structure without a journal bearing, the same effect can be obtained by forming the above-described annular groove in the bearing housing that supports the shaft member and disposing the above-described seal member. Can be obtained.

10 Main journal (shaft member)
12 Journal bearing
12U upper journal bearing 12L lower journal bearing 14 bearing housing 14U upper bearing housing 14L lower bearing housing 15 oil passage 16 circumferential groove (of bearing member) 16U upper circumferential groove 16UE upper enlarged portion 16UEs (enlarged portion) inclined surface 16L Lower circumferential groove 16LE Lower enlarged portion 16LEs (Enlarged portion) inclined surface 18 Seal member 18U Upper seal member 18UB Upper body portion 18UC Upper connecting portion 18UC1 Upper angled continuous portion 18UC2 Upper axial extension portion 18UC3 Upper slope Surface 18L Lower seal member 18LB Lower body 18LC Lower connection 18LC1 Lower angled continuous part 18LC2 Lower axial extension 18LC3 Lower inclined surface

Claims (4)

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,
The bearing member, which is composed of two halved parts, in which circumferential grooves having a predetermined axial width are formed at both ends in the axial direction on the inner peripheral surface of each halved part;
The seal member is composed of two halved parts and is disposed at a position corresponding to the circumferential groove, and includes both circumferential ends of one half part and circumferential ends of the other half part. A seal member having a connecting portion that connects to each other,
When the seal members are connected to each other, the inner diameter of the seal member contracts to be smaller than the inner diameter of the bearing member at a low temperature, and the heat expands to be equal to or larger than the inner diameter of the bearing member at a high temperature. Formed of a material having an expansion coefficient,
The connecting portion of the seal member extends from an axially extending portion extending in the axial direction and a main body portion having a flat surface in the axial direction and a circular arc surface in the circumferential direction with a predetermined angle Θ1 in the axial orthogonal direction, An axially extending portion and an angled continuous portion that is continuous with the proximal end portion of the axially extending portion, and both end portions in the circumferential direction of the circumferential groove of the bearing member are tapered . Slide bearing structure. Axial size of the axial extension portion of the hook-like connecting portion, the sliding bearing of the shaft member according to claim 1, wherein greater than the axial width of the circumferential groove of the bearing member Construction. The distance between the distal end portion of the axially extending portion and the flat surface on the side farther from the distal end portion in the axially flat surface of the main body portion is larger than half of the axial width of the circumferential groove. 3. A slide bearing structure for a shaft member according to claim 1 , wherein the shaft member is a plain bearing structure. When the taper angle of the tapered shape of the circumferential ends of the circumferential groove and .theta.2, any one of claims 2, wherein the greater than the angle Θ1 of the taper angle .theta.2 is the angled continuous section 3 A shaft bearing sliding bearing structure as described in 1.

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