JP2013011316A - Radial needle bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make flows of lubricating oil smooth through a gap between an outer-ring track and the outer peripheral surfaces of rim portions 12a, 12a by means of a retainer 7b made of a synthetic resin, and to keep rotational resistance of the retainer 7b low.SOLUTION: Central guide portions 18, 18 protruding outward in the radial direction are provided on the central-external surface of each of pillars 10a, 10a. The central guide portions 18, 18 are each closely opposed to the outer-ring track so that the retainer 7b is properly positioned with respect to the radial direction. Flows of the lubricating oil can be made smooth through the gap between the outer-ring track and the outer peripheral surfaces of both the rim portions 12a, 12a resulting in improved lubricant properties. In addition, the area of a portion wherein the lubricating oil exists between each of the central guide portions 18, 18 and the outer-ring track is decreased so that the rotational resistance of the retainer 7b can be kept low.

Description

  The present invention relates to an improvement in a radial needle bearing incorporated in a rotary machine device such as a manual transmission for an automobile (including a so-called SMT automated based on a manual transmission). Specifically, by devising the shape of the cage, even when an outer ring guide structure is used that makes it easy to stabilize the posture of the cage, the lubricating oil can be smoothly distributed in the radial needle bearing. In addition, by reducing the rotational resistance of the cage, it is possible to improve the performance of various rotary machine devices such as an automobile manual transmission.

  Conventionally, a manual transmission for an automobile has a structure as shown in FIG. 8 as described in, for example, Patent Documents 1 and 2, and a gear 1 for transmission is placed around a power transmission shaft 2 by a radial needle bearing 3. The rotation relative to the power transmission shaft 2 and the rotation synchronized with the power transmission shaft 2 are supported. The radial needle bearing 3 includes a cylindrical outer ring raceway 4 provided on the inner peripheral surface of the transmission gear 1 that is an outer ring equivalent member, and a cylindrical shape provided on the outer peripheral surface of the power transmission shaft 2 that is an inner ring equivalent member. A plurality of needles 6 are provided between the inner ring raceway 5 and the inner ring raceway 5 so as to be able to roll while being held by a cylindrical cage 7. The inner ring raceway 5 may be provided directly on the outer peripheral surface of the power transmission shaft 2 or may be provided on the outer peripheral surface of a separately provided cylindrical inner ring. Further, on the side of the transmission gear 1, there are provided engaging teeth 8 for constituting a synchro mechanism. Since the synchro mechanism and the engaging teeth 8 are not related to the gist of the present invention, the description thereof is omitted.

  Patent Documents 3 to 4 describe a cage 7a having a structure shown in FIGS. 9 to 10 as a cage that constitutes a radial needle bearing incorporated in the rotation support portion as described above. This retainer 7a is provided with each column portion that guides the rolling surface of each needle 6 and 6 in the circumferential direction among the inner surfaces of pockets 9 and 9 formed at equal intervals in a plurality of locations in the circumferential direction. Oil passage recesses 11 and 11 are formed in the axially central portions of the guide surfaces 10 and 10 in a state where the inner and outer peripheral surfaces of the cage 7a are communicated with each other. In the case of a radial needle bearing incorporating such a cage 7a, since the lubricating oil flows while passing through the oil-passing recesses 11, 11, the durability of the radial needle bearing is improved. Therefore, it is possible to improve the performance of various rotary machine devices such as automobile transmissions incorporating this radial needle bearing.

However, in the case of the conventional structure shown in FIGS. 9 to 10, the attitude of the cage, specifically, the positioning in the radial direction (the neutral position is concentric with the outer ring raceway 4 and the inner ring raceway 5. In order to prevent the deviation from the state), the outer ring guide and the outer ring raceway are in close proximity to each other, so-called outer ring guide structure is adopted. From the standpoint of further optimization, it is desirable to improve the following points (1) and (2).
(1) The gap between the outer ring raceway and the outer peripheral surface of the rim portion of the cage is increased, and the flow of lubricating oil through this gap is made smoother.
(2) The friction area between the outer ring raceway and the outer peripheral surface of the cage is made narrower, and the rotational resistance of the cage is kept lower.

First, (1) of these will be described. When the structure of the outer ring guide is adopted in the conventional structure shown in FIGS. 8 to 10 described above, the outer peripheral surfaces of the annular rim parts 12 and 12a existing at both axial ends of the cages 7 and 7a are the outer rings. It is close to the track 4. On the other hand, the lubricating oil for lubricating the radial needle bearing 3 is fed into the radial needle bearing 3 through an oil supply hole 13 provided in the power transmission shaft 2 and opened in the intermediate portion in the axial direction of the inner ring raceway 5. Then, after the lubricating oil is pressed against the outer ring raceway 4 based on the centrifugal force, the gaps 14 and 14 between the outer ring raceway 4 and the outer peripheral surfaces of the rim portions 12 and 12 (12a and 12a). Is discharged to the surroundings. In the case of the conventional structure, since the radial thickness t of both the gaps 14 and 14 is small, the lubricating oil is not necessarily discharged smoothly, and it is difficult to secure the amount of the lubricating oil flowing through the radial needle bearing 3. This is disadvantageous from the viewpoint of improving the performance of the various rotary machine devices.
Also, if positioning of the cages 7 and 7a in the radial direction is achieved by rolling element guidance based on the engagement between the rolling surfaces of the needles 6 and 6 and the inner surfaces of the pockets 9 and 9 However, there is a possibility that the problems as described above may occur. That is, even when the rolling element guide structure is adopted, the radial positions of the cages 7 and 7a vary to some extent. A part of the outer peripheral surface of the cages 7 and 7a in the circumferential direction is close to the outer ring raceway 4, and the above-described problem may occur in the part.

  Next, the above (2) will be described. As described above, when the outer peripheral surfaces of the pair of rim portions 12, 12 (12 a, 12 a) existing at both axial ends of the cage 7 (7 a) are brought close to and opposed to the outer ring raceway 4, these rim portions 12 , 12 (12a, 12a) and the outer ring raceway 4 are formed with an oil film. A shearing force is applied to the oil film with the rotation of the cage 7 (7a), and this shearing force becomes a resistance against the rotation of the cage 7 (7a), and the dynamic torque of the radial needle bearing 3 is increased. (Rotational resistance) increases. The oil film exists around the rim portions 12 and 12 (12a and 12a) almost over the entire circumference and width. For this reason, in order to ensure the strength of the retainer 7 (7a), if the width dimension in the axial direction of both the rim portions 12, 12 (12a, 12a) is ensured, the area of the oil film becomes considerably large, Dynamic torque also increases.

  In Patent Documents 5 to 6, in a metal press cage formed by bending a metal plate, the outer diameter of the central portion in the axial direction is larger than the outer diameter of a pair of rim portions provided at both end portions in the axial direction. The structure is described. However, the structures described in Patent Documents 5 to 6 not only increase the manufacturing cost and weight but also the points (1) and (2) as compared with the synthetic resin cage that is the subject of the present invention. Not intended to improve. Specifically, since the width in the axial direction of the portion where the outer diameter of the cage central portion is large is wide, the flow of the lubricating oil supplied to the axial central portion is not necessarily good {the above (1) Can't improve the point enough}. Similarly, since the width of the portion where the outer diameter is increased is wide, the area of the oil film that generates shear resistance cannot always be reduced, and when the outer ring guide structure is adopted, the rotational resistance of the cage is not always sufficient. Cannot be lowered {cannot improve point (2)}. Even when the rolling element guide structure is adopted, if the positional deviation in the radial direction of the cage increases, the rotational resistance of the cage increases.

JP 2008-286232 A JP 2009-85001 A JP 2009-68669 A Japanese Unexamined Patent Publication No. 2009-92008 JP-A-6-280864 JP 2005-172036 A

  In view of the circumstances as described above, the present invention, on the premise of using a synthetic resin cage, can smoothly flow the lubricating oil through the gap between the outer ring raceway and the outer peripheral surface of the rim portion of the cage, And it invented in order to implement | achieve the structure which can hold down the rotational resistance of this holder | retainer low.

The radial needle bearing of the present invention includes an outer ring-equivalent member, an inner ring-equivalent member, a plurality of needles, and a cage, similarly to the previously known radial needle bearing. In addition, this retainer holds a space surrounded by a plurality of pillar portions spanned between a pair of rim portions and the four rim portions so that each needle can roll. As a pocket.
In particular, in the radial needle bearing of the present invention, the cage is integrally formed by injection molding a synthetic resin, and at least three or more of the pillar portions that do not exist on the semicircular side are provided. The thickness dimension in the radial direction is the center in the axial direction with respect to the column parts (preferably three or more that are equally spaced with respect to the circumferential direction, and further all as in the invention described in claim 7). The part is also larger than both ends. In addition, the diameter of the circumscribed circle related to the central part of the three or more column parts, the diameter of the circumscribed circle related to both ends of all the column parts including these three or more column parts, and the outer diameter of the both rim parts Is bigger than.

When implementing the radial needle bearing of the present invention as described above, preferably, the positioning of the cage in the radial direction is related to the axial direction of the three or more column portions as in the invention described in claim 2. This is achieved by outer ring guidance in which the outer peripheral surface of the central portion and the outer ring raceway provided on the inner peripheral surface of the outer ring equivalent member are closely opposed to each other.
Preferably, as in the invention described in claim 3, when the outer surface in the radial direction of the cage is the outer peripheral side surface among the surfaces of the column portions, the three or more column portions are used. A central guide portion in which the diameter of the circumscribed circle is constant with respect to the axial direction is provided at the axially central portion of the outer peripheral side surface of the outer peripheral surface of the outer peripheral side surface. And the width dimension regarding the axial direction of this center guide part is made smaller than the sum of the width dimension regarding the axial direction of the outer peripheral surface of both said rim | limb parts.
When the invention described in claim 3 is carried out, it is more preferable that the center guide portion related to the three or more column portions is arranged in the center in the width direction in the circumferential direction as in the invention described in claim 4. Similarly, it is a convex curved surface with a partial cylindrical surface that is curved in a direction in which the portion protrudes in comparison with both end portions.

When carrying out the invention described in claim 3 or claim 4, specifically, as in the invention described in claim 5, the three or more column portions are arranged at the central portion in the axial direction. Similarly to the thick wall portion, the thin wall portion near the both ends is assumed to have a stepped shape in which a step portion existing on the outer peripheral side surface is continued.
Alternatively, as in the invention described in claim 6, the thickness in the radial direction of the three or more column parts gradually decreases from the thick part at the axially central part toward both the rim parts.
In any case, the central guide portion is the outer peripheral side surface of the thick-walled portion, and the inner diameter of the cage is constant over the entire width in the axial direction except for the chamfered portions at both end edges in the axial direction.

According to the radial needle bearing of the present invention configured as described above, through a gap between the outer ring raceway and the outer peripheral surface of the rim portion of the cage, using a synthetic resin cage that is low-cost and lightweight. The flow of the lubricating oil can be made smooth, and the rotational resistance of the cage can be kept low.
First, the smooth flow of the lubricating oil means that the radial displacement of the cage is suppressed (for example, positioning in the radial direction is achieved by an outer ring guide), and the axially central portion of three or more column portions. This can be realized only by the central guide portion provided in For example, since a pair of rim portions provided at both ends in the axial direction of the cage are not used for guiding the outer ring of the cage, the gap between the outer peripheral surface of these rim portions and the outer ring raceway can be increased. . Therefore, even if a pump with a large discharge capacity (high discharge pressure) is not used as a pump for supplying lubricating oil, the lubrication fed into the radial needle bearing from the axial intermediate portion of the radial needle bearing Oil can be smoothly discharged to the outside through both the gap portions. For this reason, the lubrication conditions of the radial needle bearing can be improved.

  Next, it is possible to suppress the rotational resistance of the cage to be low by, for example, reducing the area of the portion where the outer peripheral surface of the cage and the outer ring raceway are closely opposed to each other for guiding the outer ring. That is, only the central guide portions provided on the three or more pillar portions are brought close to and opposed to the outer ring raceway. Unlike the rim portion, each of these column portions originally exists intermittently in the circumferential direction, and therefore, by making the diameter of the circumscribed circle larger than the other portions, the area is sufficiently narrowed. it can. In particular, as in the invention described in claim 3, if the width dimension of each central guide portion is narrowed, the area can be more sufficiently narrowed. As a result, by adopting the structure of the outer ring guide, the area of the portion where the oil film exists between the outer peripheral surface of the cage and the outer ring raceway can be reduced, and the rotation of the cage can be reduced. Resistance, and hence dynamic torque of the radial needle bearing can be kept low. Furthermore, if the structure of the invention described in claim 4 is adopted, each central guide portion will not scrape off the lubricant adhering to the outer ring raceway. Rather, the center guide portion and the outer ring raceway A firm oil film can be easily formed between them, and it can contribute to reduction of rotational resistance and stabilization of the attitude of the cage. As a result, it is easy to improve the performance of various rotary machine devices.

The perspective view which shows the 1st example of embodiment of this invention in the state which took out only the holder | retainer. AA sectional drawing of FIG. FIG. 3 is a cross-sectional view taken along the line BB in FIG. The perspective view shown in the state which assembled | attached the needle in each pocket, respectively. The perspective view which shows the 2nd example of embodiment of this invention in the state which took out only the holder | retainer. CC sectional drawing of FIG. DD sectional drawing of FIG. 6 which shows two examples of the cross-sectional shape of each pillar part, respectively. The fragmentary sectional view of the rotation support part of the manual transmission for motor vehicles incorporating the radial needle bearing. The figure similar to FIG. 4 which shows an example of a conventional structure. The partial expanded view seen from the radial direction outer side of FIG.

[First example of embodiment]
1-4 show a first example of an embodiment of the present invention corresponding to claims 1 to 5 and 7. The feature of the present invention, including this example, is a synthetic resin cage whose radial position is regulated by the outer ring guide, for example, in order to improve the flow of lubricating oil and reduce rotational resistance. It is in the point which devised the shape and dimension of a pair of rim | limb part and a some pillar part. Since the structure and operation of other parts including the basic structure of the cage are the same as those of the conventional structure described above, the illustration and description of the equivalent parts are omitted or simplified. And it demonstrates centering on the part which was not demonstrated previously.

  The cage 7b constituting the radial needle bearing of the present example is integrally formed by injection molding a synthetic resin, and includes a pair of rim portions 12b and 12b and a plurality of column portions 10a and 10a. . Of these, the two rim portions 12b, 12b have the same diameter, and are concentrically provided in a state of being separated from each other in the axial direction. The column portions 10a and 10a are arranged in parallel with each other at an equal pitch in the circumferential direction, and are spanned between the rim portions 12b and 12b. And in order to hold | maintain the needle | hook 6 and 6 so that rolling is possible, respectively, the part enclosed by each of these rim | limb parts 12b and 12b and said each pillar part 10a and 10a adjacent to the circumferential direction at each four circumferences. Pockets 9a and 9a are provided.

In the case of this example, each of the pillar portions 10a and 10a has a step portion 17 existing on the outer peripheral side surface, as well as a thick portion 15 and 15 at the both ends as well as a thick portion 15 and 15 at the axial center portion. 17 is a stepped shape made continuous. If the Considering circumscribed circle of the axial respective sections of the column sections 10a, 10a, the diameter D ₁₅ of the circumscribed circle of each thick portion 15, 15 parts of the axial central portion, the two rim portions 12b, 12b of the larger than the outer diameter D _12. On the other hand, the diameter D ₁₆ of the circumscribed circle of the thin-walled portions 16, ₁₆ is smaller than the outer diameter D ₁₂ of the rim portions 12b, 12b (D ₁₅ > D ₁₂ > D ₁₆ ). In short, of the outer peripheral surface of the cage 7b, the outer peripheral side surfaces of the thick portions 15 and 15 existing at the axial center portions of the column portions 10a and 10a are projected most outward in the radial direction, The central guide portions 18 and 18 are located close to and opposite to the track 4 (see FIG. 8). The width dimension W in the axial direction of each of the central guide portions 18 and 18 is smaller than the sum (2w) of the width dimensions w in the axial direction of the outer peripheral surfaces of the rim portions 12b and 12b (W <2w). The cross-sectional shape of each central guide portion 18 with respect to a virtual plane orthogonal to the central axis of the cage 7b may be a flat surface as shown in FIG. A convex curved surface having a partial cylindrical surface as shown in B) is used. The radius of curvature of the convex curved surface is made sufficiently smaller than the radius of curvature of the outer peripheral surfaces of the rim portions 12b and 12b. However, in any case, the diameter of the circumscribed circle related to each of the central guide portions 18 and 18 is constant over the entire width in the axial direction of each of the central guide portions 18 and 18.

  When the radial needle bearing is configured by the cage 7b as described above, for example, the central guide portions 18 and 18 are close to and opposed to the outer ring raceway 4 to position the cage 7b in the radial direction. Therefore, during operation of the radial needle bearing, the cage 7b is not displaced in the radial direction more than necessary for stable rolling of the needles 6 and 6, so-called cage noise is generated. Can be suppressed. Even in this state, an annular gap having a sufficiently large radial thickness exists between the outer peripheral surfaces of the rim portions 12b, 12b and the outer ring raceway 4, so that the axial intermediate portion of the radial needle bearing is provided. The lubricating oil fed from can be smoothly discharged to the outside through the both annular gap portions. For this reason, the lubrication conditions of the radial needle bearing can be improved.

  In addition, even in the state where the positioning of the cage 7b in the radial direction is achieved as described above, the area of the portion where the central guide portions 18 and 18 and the outer ring raceway 4 are closely opposed can be reduced. For this reason, the area of the oil film formed between each of the central guide portions 18 and 18 and the outer ring raceway 4 can be reduced, the rotational resistance of the cage 7b, and the dynamic torque of the radial needle bearing. Can be kept low. In particular, if the shape of each of the central guide portions 18 and 18 is a convex curved surface as shown in FIG. 3 (B), the central guide portions 18 and 18 and the outer ring raceway 4 are firmly fixed. An oil film can be easily formed, and a reduction in rotational resistance and stabilization of the attitude of the cage can be achieved at a higher level, thereby making it easier to improve the performance of various rotary machine devices.

  Moreover, even if positioning in the radial direction of the cage 7b is achieved by rolling element guidance based on the engagement between the rolling surfaces of the needles 6 and 6 and the inner surfaces of the pockets 9a and 9a, To some extent, the above-described actions and effects can be obtained. That is, even when the positioning of the cage 7b in the radial direction is achieved by the rolling element guide, the radial position of the cage 7b varies to some extent. There is a possibility that a part of the outer circumferential surface of the cage 7b in the circumferential direction tends to be close to the outer ring raceway 4. Even in such a case, if the cage 7b of this example is used, the radial thickness of the annular gap between the outer peripheral surfaces of the rim portions 12b and 12b and the outer ring raceway 4 can be sufficiently increased. The actions and effects described above can be obtained.

[Second Example of Embodiment]
FIGS. 5-7 has shown the 2nd example of embodiment of this invention corresponding to Claims 1-4,6,7. In the cage 7c constituting the radial needle bearing of the present example, the shape of the outer peripheral side surface of each column portion 10b, 10b is different from that of the first example of the above-described embodiment. Specifically, in the case of this example, each of the column portions 10b and 10b is changed from a thick wall portion 15a and 15a provided at the axial center portion to a pair of rim portions 12b provided at both axial ends. The thickness in the radial direction gradually decreases toward 12b. For this purpose, the central guide portions 18a and 18a, which are the outer peripheral side surfaces of the thick portions 15a and 15a, and the outer peripheral surfaces of the rim portions 12b and 12b are made continuous by the inclined surface portions 19 and 19, respectively. Also in this example, the cross-sectional shape of the central guide portions 18a, 18a is a flat surface as shown in FIG. 7A or a convex curved surface as shown in FIG. Since the configuration and operation of the other parts are the same as those in the first example of the above-described embodiment, redundant description is omitted.

  When carrying out the present invention as described above, as shown in FIGS. 9 to 10, as a cage, the width dimension in the circumferential direction of the central portion in the axial direction of the pocket is set to the circumference of both end portions in the axial direction. What is larger than the width dimension in the direction (that is, the width dimension in the circumferential direction of the central portion in the axial direction of the column portion is smaller than the width dimension in the circumferential direction at both end portions in the axial direction) may be used. According to such a cage, the flow rate of the lubricating oil can be further increased.

DESCRIPTION OF SYMBOLS 1 Gear for speed change 2 Power transmission shaft 3 Radial needle bearing 4 Outer ring raceway 5 Inner ring raceway 6 Needle 7, 7a, 7b, 7c Cage 8 Engagement tooth 9, 9a Pocket 10, 10a, 10b Pillar part 11 Oil recess 12 , 12a, 12b Rim part 13 Oil supply hole 14 Gap 15, 15a Thick part 16 Thin part 17 Step part 18, 18a Central guide part 19 Inclined surface part

Claims (7)

  An outer ring equivalent member having a cylindrical outer ring raceway provided on the inner peripheral surface, an inner ring equivalent member having a cylindrical inner ring raceway provided on the outer peripheral surface, and a rollable portion provided between the outer ring raceway and the inner ring raceway. A plurality of needles and a holder for holding each needle are provided, and the holder is disposed between a pair of rim portions arranged concentrically with each other in an axially spaced state. A plurality of pillar portions arranged at intervals in the circumferential direction are spanned, and the respective needles can roll in a space surrounded by the circumference by the pillar portions adjacent to each other in the circumferential direction and the rim portions. In the radial needle bearing, which is a pocket for holding, the cage is integrally formed by injection molding of synthetic resin and exists on at least a semicircular side of each of the pillars. For three or more pillars that do not The thickness dimension is also larger in the central portion than in the central portion with respect to the axial direction, and the diameter of the circumscribed circle with respect to the central portion of the three or more column portions is a total including these three or more column portions. A radial needle bearing characterized in that a diameter of a circumscribed circle related to a portion near both ends of each column portion and an outer diameter of both the rim portions are larger.   2. The cage according to claim 1, wherein the retainer is positioned with respect to a radial direction by an outer ring guide that makes an outer peripheral surface of the central portion in the axial direction of the three or more pillar portions and the outer ring raceway face each other. Radial needle bearing.   When the outer surface in the radial direction of the cage is the outer peripheral side surface among the surfaces of the column portions, the circumscribed circle is formed at the axial central portion of the outer peripheral side surfaces of the three or more column portions. A central guide portion having a constant diameter with respect to the axial direction is provided, and a width dimension in the axial direction of the central guide portion is smaller than a sum of width dimensions in the axial direction of the outer peripheral surfaces of the two rim portions. The radial needle bearing described in any one of 1-2.   The central guide portion related to the three or more column portions is a partially cylindrical convex curved surface that is curved in a direction in which the central portion in the width direction in the circumferential direction protrudes in comparison with both end portions. Radial needle bearing.   The three or more pillars have a stepped shape in which a thick part at the center in the axial direction and a thin part at a portion near both ends are continuously provided by a step part existing on the outer peripheral side surface. The radial needle bearing according to claim 3 or 4, wherein the portion is an outer peripheral side surface of the thick-walled portion, and the inner diameter of the cage is constant over the entire width in the axial direction.   The three or more column parts gradually decrease in thickness in the radial direction from the thick part at the axially central part toward the two rim parts, and the central guide part is an outer peripheral side surface of the thick part. The radial needle bearing according to claim 3 or 4, wherein an inner diameter of the cage is constant over the entire width in the axial direction.   With respect to all the column parts, the thickness dimension in the radial direction in each central part is also larger than the both end parts, and the diameter of the circumscribed circle in each central part is the diameter of the circumscribed circle in the part near both ends and the both rim parts. The radial needle bearing according to claim 1, wherein the radial needle bearing is larger than an outer diameter of the radial needle bearing.

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