JP5534733B2 - Universal joint boots - Google Patents

Description

  The present invention relates to a universal joint boot mounted on a universal joint. The universal joint boot of the present invention is used as, for example, a universal joint boot for a drive shaft, a universal joint boot for a propeller shaft, and a power transmission universal joint boot in an industrial machine related field.

  Conventionally, as shown in FIG. 7A, an attachment portion 53 for the shaft 21 is provided at one end portion of the bellows-shaped membrane portion 52, and an attachment portion 54 for the outer joint member 22 of the universal joint is provided at the other end portion. There is known a universal joint boot 51 provided with a band mounting groove 55 on the outer peripheral surface of the mounting portions 53, 54. This universal joint boot 51 is connected to the shaft 21 and the outer joint member 22 of the universal joint. The seal is secured by tightening with a band 23 after that, and grease (not shown) is sealed in the boot 51. As shown in an enlarged view in FIG. 7B, a projection-like lip 56 is provided on the inner peripheral surface of the mounting portion 53 in order to improve the sealing performance (see Patent Document 1).

  However, in the structure of FIG. 7 described above, when the tightening force of the tightening band 23 is weak, sufficient sealing performance cannot be ensured, and internal grease may flow out. Therefore, in order to ensure a sufficient sealing performance, a band structure capable of obtaining a strong tightening force is required, which inevitably raises a problem that the manufacturing cost of the band increases. As shown in FIG. 8, the structure of the band 23 is a type in which the lever 24 is fastened by folding it back in the direction of the arrow. As shown in FIG. 9, the engagement holes 26 and the engagement claws are formed at both ends of the band-shaped band body 25. 27 is provided with a hook part 27 and tightened by engaging them (see Patent Document 2), and as shown in FIG. 10, a plastic deformation part (ear part) 28 is provided to plastically deform this part. There are a type (see Patent Document 2) that is tightened with a screw, and a type that is tightened by plastic deformation of an annular member (boot ring) 29 in the inner diameter direction as shown in FIG. 11 (see Patent Document 3).

JP 2004-301202 A JP 2006-283842 A JP 2005-291367 A

  In view of the above points, the present invention provides a universal joint boot that can further enhance the sealing performance of the boot mounting portion and can ensure sufficient sealing performance even when a band having a relatively small tightening force is used. For the purpose.

In order to achieve the above object, a universal joint boot according to claim 1 of the present invention has a mounting portion for a shaft or an outer joint member at an end portion of a bellows-shaped membrane portion, and a band mounting groove on an outer peripheral surface of the mounting portion. In the universal joint boot having a lip, a lip that generates a seal surface pressure against the shaft or the outer joint member is provided on the inner peripheral surface of the mounting portion, and a convex portion is provided on the bottom surface of the band mounting groove. The lip is provided in plural, and a groove is provided between the lips, and the groove is a surface of the inner peripheral surface of the mounting portion where the lip is provided and is in the axial direction of the shaft. while being recessed into the parallel orientation of the cross-section straight radially outward from a surface, the groove cross section linear slope which forms an extension of the boot outer inclined surface of the first lip of the inner boot Characterized in that it has as part of the surface.

The universal joint boot according to claim 2 of the present invention is the universal joint boot according to claim 1 , wherein, in addition to the inclined surface, the groove portion has a flat surface continuous from the inclined surface, and an arc-shaped cross section. And a curved surface connecting the flat surface and the boot inner slope of the second lip on the outer side of the boot .

  A universal joint boot according to claim 3 of the present invention is the universal joint boot according to claim 1 or 2, wherein the lip and the convex portion are provided at corresponding positions in the cross-sectional shape. Features.

  A universal joint boot according to claim 4 of the present invention is the universal joint boot according to any one of claims 1 to 3, wherein the rotational force can be transmitted while allowing axial displacement. It is used for a dynamic type constant velocity universal joint.

  According to a fifth aspect of the present invention, there is provided a universal joint boot according to any one of the first to fourth aspects, wherein the universal joint boot is a component part of a drive shaft for transmitting a driving force of an automobile to a wheel. It is used for a constant velocity universal joint.

  If a protrusion is provided on the bottom surface of the band mounting groove at a position corresponding to the lip in the mounting part of the boot provided with a band mounting groove on the outer peripheral surface and a lip on the inner peripheral surface, the band tightening force is changed from the convex to the lip. Since it is easy to transmit, the seal surface pressure in the lip can be increased. However, since the conventional lip has an equilateral shape (V-shape) symmetrical in the axial direction, the inventors of the present application. According to the FEM analysis result performed by No. 1, the increase ratio of the seal surface pressure at the lip is not so large.

  On the other hand, if the cross-sectional shape of the lip is an unequal side shape, such as a shape that axially displaces the tip (V shape tip) in the equilateral shape (V shape), the case of the equilateral shape (V shape) In comparison, it was found that the peak value of the seal surface pressure at the lip increased by 20% or more. Therefore, in the present invention, a lip is provided on the inner peripheral surface of the mounting portion, a convex portion is provided on the bottom surface of the band mounting groove at a position corresponding to the lip, and the cross-sectional shape of the lip is defined as an unequal side shape.

  When the tip of the equilateral shape (V-shape) is displaced in the axial direction, peak surface pressure is generated in the vicinity of the grease by displacing the tip to the grease side inside the boot instead of the atmosphere side outside the boot. Therefore, it is preferable in terms of the sealing function.

  Moreover, even if the lip has the above-mentioned equilateral shape (V shape), it is not a perfect pointed shape, but the inner diameter of the boot is gradually reduced from the inside slope of the boot (from the inside of the boot, that is, the grease side to the outside of the boot, that is, the atmosphere) 3 surfaces including a flat surface (cylindrical surface having a constant inner diameter) and a boot outer slope (a slope whose inner diameter gradually increases from the boot inner side, that is, the grease side to the boot outer side, that is, the atmosphere side). In the present invention, the lip includes a case where these three surfaces are provided in series, and in this case, the side length and the inclination angle are different between the boot inner slope and the boot outer slope which are paired in the axial direction. As a result, an unequal side shape is obtained.

Therefore, as described above, the unequal side shape, specifically, the side length of the boot inner slope is L ₁ , the tilt angle (the tilt angle with respect to the plane perpendicular to the axis) is θ ₁ , the side length of the boot outer slope is L ₂ , The inclination angle (inclination angle with respect to the plane perpendicular to the axis) is θ ₂ and
L ₁ <L ₂ and θ ₁ <θ ₂
Will be defined.

Further, when a plurality of lips are provided and a groove portion is provided between the lips, the groove portion stores grease, thereby further improving the sealing performance. If a plurality of lips are provided, the space between the lips naturally becomes a relative concave portion, but such a relative concave portion is not included in the groove portion, and the groove portion is deeper than the relative concave portion (as an event, a linear reference surface) A plurality of lips are provided on the reference surface, and the space between the lips is a relative concave portion, but such a relative concave portion is not included in the groove portion. Established).

  In addition, the convex part provided on the bottom surface of the band mounting groove reduces the resistance between the band mounting groove and the band when tightening the band, or the boot mounting part is partially biased on the circumference when tightening the band There is also an effect of controlling.

  The present invention has the following effects.

  That is, by providing a lip on the inner peripheral surface of the boot mounting portion as in the present invention, providing a convex portion on the bottom surface of the band mounting groove at a position corresponding to the lip, and making the cross-sectional shape of the lip an unequal side shape As compared with the case where the cross-sectional shape of the lip is an equilateral shape, the peak value of the seal surface pressure at the lip can be greatly increased. Further, when a plurality of lips are provided and a groove portion is provided between the lips, the groove portion stores grease, thereby further improving the sealing performance. Therefore, according to the intended purpose of the present invention, it is possible to provide a boot for a universal joint that further enhances the sealing performance at the boot mounting portion and ensures sufficient sealing performance.

Sectional drawing which shows the mounting state of the boot for universal joints based on the Example of this invention Expanded sectional view of the main part of the universal joint boot Part A enlarged view in FIG. Table showing data related to "current shape" during comparative tests Table showing data related to "comparative shape" during comparative tests Table showing data related to "Example (Invention shape)" during comparative tests It is a figure which shows the boot for universal joints which concerns on a prior art example, Comprising: (A) is sectional drawing which shows the mounting state, (B) is the principal part expanded sectional view Front view showing the first example of a band It is a figure which shows the 2nd example of a band, Comprising: (A) (B) and (C) are sectional drawings which show the fastening operation | movement in steps, (D) is a perspective view which shows the fastening state It is a figure which shows the 3rd example of a band, (A) is the top view, (B) is the side view, (C) is sectional drawing in the middle of the tightening The perspective view which shows the 4th example of a band

The present invention includes the following embodiments.
(1) In the universal joint boot, the boot is set on the shaft / outer joint member, and then tightened with a band to ensure sealing performance and enclose the grease in the boot. Various types of bands are used, but those with a weak tightening force cannot secure a sufficient sealing performance, and internal grease may flow out.
(2) Therefore, in the present invention, regarding the shape of the band tightening portion on the small diameter side or large diameter side of the rubber boot for a universal joint that is set on the shaft / outer joint member and secures the sealing performance by band tightening, the following (a) to (c) ) To improve sealing performance.
(A) To reduce the resistance between the band mounting groove and the band when tightening the band, and to control that the boot mounting part is partially biased on the circumference when tightening the band, a convex portion was added to the band groove of the boot thing.
(B) The boot inner surface lip has an unequal side shape for the purpose of preventing the outflow of grease against the boot internal pressure rise.
(C) A groove provided between unequal side lips for the purpose of grease fastening.

  Next, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows an overall cross-section of a mounted state of a universal joint boot 1 according to an embodiment of the present invention, and its main part (small diameter side attaching part 3) is shown in FIG. FIG. 3 further shows the portion A of FIG. 2 in an enlarged manner.

  A universal joint boot 1 according to this embodiment is a universal joint boot for a drive shaft or propeller shaft made of a thermoplastic elastomer or a predetermined rubber-like elastic body, and has a bellows-shaped membrane part (bellows part). The small-diameter side attachment portion 3 for the shaft 21 is integrally formed at one end portion in the axial direction 2 and the large-diameter side attachment portion 4 for the outer joint member (joint) 22 is integrally formed at the other end portion in the axial direction. The band 23 is fastened and fixed.

As shown in an enlarged view in FIG. 2, the small-diameter side attachment portion 3 has a cylindrical shape as a whole, and is provided with an annular band mounting groove 5 having a predetermined axial width W ₁ on its outer peripheral surface. An annular lip 6 is provided on the surface, and an annular projection 7 is provided on the bottom surface of the band mounting groove 5 at a position corresponding to the lip 6. Two lips 6 are provided at a predetermined interval, and two protrusions 7 are provided correspondingly.

In addition, on the inner peripheral surface of the small-diameter side mounting portion 3, a positioning annular protrusion 8 having a predetermined axial width W ₂ that engages with a positioning annular groove 24 (see FIG. 1) provided on the peripheral surface of the shaft 21. Therefore, the lip 6 is provided on the inner peripheral surface of the annular projection 8 having a trapezoidal cross section.

  Each of the cross-sectional shapes of the convex portions 7 is a circular arc shape that is symmetrical in the axial direction. On the other hand, the cross-sectional shape of the lip 6 is configured as follows.

  That is, as further enlarged in FIG. 3, if the lip 6 is not provided, the inner peripheral surface of the small-diameter side mounting portion 3 (the inner peripheral surface of the annular protrusion 8) is a straight line from m to n (hereinafter, This straight line is also referred to as a reference plane). Two lips 6 are provided so as to protrude radially inward (downward in the figure) from the reference plane, and the lip 6 has a trapezoidal cross section. In addition, it has an unequal side shape that is asymmetric in the axial direction.

That is, each of the lips 6 has a boot inner slope (a slope whose inner diameter is gradually reduced from the boot inner side, that is, the grease side (left side in the figure) to the boot outer side, that is, the atmospheric side (right side in the figure)) 6a, a flat surface. (Cylinder surface having a constant inner diameter dimension) 6b and a boot outer slope (a slope whose inner diameter dimension gradually increases from the boot inner side, that is, the grease side to the boot outer side, the atmosphere side) 6c is a trapezoidal cross section. The boot inner slope 6a and the boot outer slope 6c, which are paired in the axial direction, have an unequal side shape with different side lengths and inclination angles. Specifically, the side length of the boot inner slope 6a is L ₁ , and the slope is inclined. The angle (inclination angle with respect to the plane perpendicular to the axis) is θ ₁ , the side length of the boot outer slope 6 c is L ₂ , and the inclination angle (inclination angle with respect to the axis perpendicular to the axis) is θ ₂ .
L ₁ <L ₂ and θ ₁ <θ ₂
It is formed to satisfy.

Further, as shown in FIG. 2, each of the lips 6 is disposed at the same position in the axial direction as the convex portion 7 provided on the outer peripheral side thereof, and the axial center line (center line) 6d of the flat surface 6b of the lip 6 is The axial width W ₃ (see FIG. 3) of the whole lip 6 is made to coincide with the axial center line (center line) 7d of the convex portion 7, and the axial width W ₄ (see FIG. 2) of the convex portion 7 is slightly smaller. It is set small.

  As shown in FIG. 3, an annular groove 9 is provided between the two lips 6 so as to be recessed radially outward (upward in the drawing) from the reference surface. Is not particularly limited, but in the figure, the first lip 6 inside the boot extends from the boot outer slope 6c, the slope 9a has a linear cross section, a flat face 9b, and the flat face 9b and the boot have an arcuate cross section. It is formed by a curved surface 9c connecting the boot inner slope 6a of the second outer lip 6.

  Next, since the comparative test regarding the surface pressure peak value of the universal joint boot 1 according to the above embodiment was performed, the contents and results thereof will be described as follows. As a comparative example, there are two “current shape” shown in FIG. 4 and “comparative shape” shown in FIG. 5, and FIG. 6 shows the above “example (invention shape)”.

“Current shape”: No convex part, equilateral lip, no groove between lips
θ ₁ = θ ₂ = 45 degrees

“Comparison shape”: Convex part with arc-shaped cross section, equilateral lip, groove between lips
θ ₁ = θ ₂ = 45 degrees

“Example (Invention shape)”: Convex with arc-shaped cross section, unequal side lip, groove between lips
θ ₁ = 15 degrees, θ ₂ = 60 degrees

  In all the three shapes, the lip height, the axial width of the flat portion, the inner diameter of the reference surface, and the thickness between the reference surface and the bottom surface of the band mounting groove are the same. Further, the height of the projection and the depth of the groove in the comparative shape and the example are the same dimensions.

  The results of the comparative test are as follows. As shown in the “surface pressure distribution” and “surface pressure peak ratio” in each figure “FEM analysis result”, the surface pressure peak value of “current shape” is set to “1.0”, and “comparison shape” The surface pressure peak value of “1.19” and the surface pressure peak value of “Example (invention shape)” are “1.52”, confirming the effectiveness of the “unequal-side lip” according to the present invention. I was able to. In the “Example (Invention shape)”, as shown in the graph of “Surface pressure distribution”, the surface pressure peak is biased toward the grease side (left side in the figure), so that the sealing effect is further enhanced. It is expensive.

DESCRIPTION OF SYMBOLS 1 Boot for universal joints 2 Film | membrane part 3 Small diameter side attaching part 4 Large diameter side attaching part 5 Band mounting groove 6 Lip 6a Boot inner slope 6b, 9b Flat surface 6c Boot outer slope 6d, 7d Axial center line 7 Convex part 8 Annular Projection 9 Groove 9a Slope 9c Curved surface 21 Shaft 22 Outer joint member 23 Band 24 Annular groove

Claims (5)

In the universal joint boot having an attachment portion for the shaft or the outer joint member at the end of the bellows-shaped membrane portion and having a band mounting groove on the outer peripheral surface of the attachment portion,
A lip that generates a seal surface pressure against the shaft or the outer joint member is provided on the inner peripheral surface of the mounting portion, and a convex portion is provided on the bottom surface of the band mounting groove, and the cross-sectional shape of the lip is an unequal side shape,
A plurality of the lips are provided, and a groove is provided between the lips.
The groove portion is a surface provided with the lip in the inner peripheral surface of the mounting portion, and is recessed radially outward from a surface having a straight section in a direction parallel to the axial direction of the shaft. , boot for a universal joint, characterized in that it has a cross-section linear slope which forms an extension of the boot outer inclined surface of the first lip of the inner boot as part of the groove inner surface. In addition to the inclined surface, the groove portion has a flat surface continuous from the inclined surface, and a curved surface connecting the flat surface and the boot inner inclined surface of the second lip outside the boot in a circular arc shape. The boot for a universal joint according to claim 1.   The universal joint boot according to claim 1, wherein the lip and the convex portion are provided at corresponding positions in a cross-sectional shape.   The universal joint boot according to any one of claims 1 to 3, wherein the boot is used for a sliding type constant velocity universal joint capable of transmitting a rotational force while allowing an axial displacement.   The universal joint boot according to any one of claims 1 to 4, which is used for a constant velocity universal joint that is a component part of a drive shaft for transmitting a driving force of an automobile to a wheel.

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