Patent Description:
Conventionally, there is a mechanical seal in which a mating ring attached in a sealed state to a rotating shaft and a seal ring attached in a sealed state to a housing slide relative to each other, and seal between the housing and the rotating shaft, the mechanical seal including an annular case which is fixed to the housing and which contains the seal ring, and an O-ring disposed between the seal ring and the annular case (for example, see Patent Document <NUM>).

Moreover, there is a mechanical seal device in which a rotating-side sealing ring attached in a sealed state to a shaft and a stationary-side sealing ring attached to a seal housing slide relative to each other, and seal between the seal housing and the shaft, the mechanical seal device including a cartridge which is fixed to the seal housing and which contains the stationary-side sealing ring, and a rubber bellows disposed between the stationary-side sealing ring and the cartridge (for example, see Patent Document <NUM>).

A generic mechanical seal having the features of the preamble of claim <NUM> is disclosed in Patent Document <NUM>. Further conventional mechanical seals are known from Patent Documents <NUM> to <NUM>.

However, in Patent Document <NUM>, the O-ring which seals between the seal ring and the annular case contacts the seal ring at two points of an inner circumferential surface and an end surface thereof. Therefore, when shaft vibration is increased, the seal ring is restrained by the O-ring due to their contact at two points of the inner circumferential surface and the end surface, and therefore, cannot sufficiently follow the movement of the mating ring, and there is a risk that reliable sealing properties cannot be provided.

Moreover, in Patent Document <NUM>, flexibility is ensured by increasing the axial length of the rubber bellows, so the stationary-side sealing ring can follow the movement of the rotating-side sealing ring even if shaft vibration is increased. However, the axial length of the bellows is increased, so there is a problem that the mechanical seal device is increased in size.

The present invention has been made in view of such problems, and an object thereof is to provide a mechanical seal in which a stationary-side sealing ring can follow the movement of a rotating-side sealing ring to provide reliable sealing properties and by which the entire device can be made compact.

The object is achieved by a mechanical seal having the features of claim <NUM>. Further advantageous developments of the present invention are set out in the dependent claims.

According to the invention, the seal member is regulated by the holding part of the case from moving to the both sides in the axial direction thereof, so the seal member can contact the stationary-side sealing ring at one point and seal it. Thereby, the stationary-side sealing ring is not restrained by the seal member from moving and can follow the movement of the rotating-side sealing ring to provide reliable sealing properties.

Preferably, the holding part further includes an axial gap between the seal member and itself.

Accordingly, even if the seal member deforms and swells in the axial direction, deformation can be absorbed by the axial gap.

Preferably, a depth of the holding part is larger than a gap between the stationary-side sealing ring and the case.

Accordingly, the depth of the annular groove is larger than the gap between the stationary-side sealing ring and the case, so the seal member is reliably held without protruding from the gap between the stationary-side sealing ring and the case.

In an embodiment which is not part of the present invention, a cross-sectional shape of the holding part is a trapezoidal shape which is narrow on an inner diameter side and is wide on an outer diameter side.

Accordingly, the seal member is regulated from moving to the both sides in the axial direction within the trapezoidal groove, and the annular groove is narrow on the inner diameter side and is wide on the outer diameter side, so even if the seal member deforms and swells in the axial direction, deformation can be absorbed by the axial gap on the outer diameter side.

Accordingly, the mechanical seal can be made compact, and an inner circumferential surface of the stationary-side sealing ring is formed into the same diameter along almost the entire axial length, so even if a mold-release material such as SiC is used, molding is facilitated, and stabilization of quality and reduction of cost are possible.

Embodiments of a sliding component according to the present invention will be described in detail referring to the drawings. In addition, a mechanical seal to be described below is an example, the present invention shall not be interpreted as being limited thereto, and a variety of changes, amendments, or improvements could be added based on the knowledge of a person skilled in the art without departing from the scope of the present invention.

A sliding component according to a first embodiment, which is not covered by the subject-matter of the claims but is considered useful for understanding the invention, will be described referring to <FIG>.

<FIG> is a vertical cross-sectional view showing an example of a mechanical seal <NUM>, which is an inside mechanical seal in a form of sealing a fluid to be sealed tending to leak from the outer circumference of a sliding face S toward the inner circumference. The mechanical seal <NUM> consists of a rotating-side cartridge <NUM> provided in a state of being integrally rotatable with a rotating shaft <NUM>, and a stationary-side cartridge <NUM> fixed to a housing <NUM> in a state of being non-rotatable. The rotating-side cartridge <NUM> includes a sleeve <NUM> fixed to the rotating shaft <NUM>, and a rotating-side sealing ring <NUM> provided in a state of being integrally rotatable with the rotating shaft <NUM> via a cup gasket <NUM> within the sleeve <NUM>. On the other hand, the stationary-side cartridge <NUM> includes a case <NUM> fixed to the housing <NUM>, a circular-ring shaped stationary-side sealing ring <NUM> provided in a state of being non-rotatable and axially movable within the case <NUM>, a seal member <NUM> provided between the case <NUM> and the stationary-side sealing ring <NUM>, and a biasing means <NUM> which axially biases the stationary-side sealing ring <NUM>. The rotating-side sealing ring <NUM> and the stationary-side sealing ring <NUM> slide relative to each other on a sliding face S, thereby preventing a fluid to be sealed from flowing out from the outer circumference to a leakage side. In addition, although the materials of the rotating-side sealing ring <NUM> and the stationary-side sealing ring <NUM> are selected from silicon carbide (SiC) excellent in wear resistance, carbon excellent in self-lubricity and the like, for example, both may be SiC or combinations of SiC as one of them and carbon as the other of them are possible. Hereinafter, the configurations of the rotating-side cartridge <NUM> and the stationary-side cartridge <NUM> will be described.

The rotating-side cartridge <NUM> mainly consists of the sleeve <NUM> fixed to the rotating shaft <NUM>, and the cup gasket <NUM> and the rotating-side sealing ring <NUM> which rotate with the sleeve <NUM>.

As shown in <FIG>, the sleeve <NUM> is an annular member having a generally U-shaped cross-section, and consists of an inner cylinder part 12a press-fitted and fixed to the rotating shaft <NUM>, an end wall 12b extended from one end of the inner cylinder part 12a to the radially outside, and an outer cylinder part 12c extended from an outer diameter side end part of the end wall 12b to the axial direction on the inner cylinder part 12a side. An opening 12p of the sleeve <NUM> is fixed to the rotating shaft <NUM> so as to face the stationary-side cartridge <NUM>.

As shown in <FIG>, the rotating-side sealing ring <NUM> is formed by an annular member having a generally rectangular cross-section. On the front surface side of the rotating-side sealing ring <NUM> opposed to the stationary-side sealing ring <NUM>, the sliding face S is provided. In addition, in order to be able to correspond to even the case where the rotation centers of the rotating-side sealing ring <NUM> and the stationary-side sealing ring <NUM> do not exactly match, a sealing portion margin on the outer diameter side and a sealing portion margin on the inner diameter side are formed by increasing the outer diameter of the sliding face S and decreasing the inner diameter thereof, and the sliding face S of the rotating-side sealing ring <NUM> is formed larger than the radial width of the sliding face S of the stationary-side sealing ring <NUM> to be described later. Moreover, in the present embodiment, the radial width of the sliding face S of the rotating-side sealing ring <NUM> is formed larger than the radial width of the sliding face S of the stationary-side sealing ring <NUM>, but the present embodiment is not limited thereto, and of course can be applied to the opposite case. Further, a notch recess 11a is formed in the outer circumferential portion of the rotating-side sealing ring <NUM> symmetrically to the rotating shaft <NUM> as shown in <FIG>, the aforementioned sleeve <NUM> is engaged with the notch recess 11a, and the rotating-side sealing ring <NUM> and the sleeve <NUM> rotate integrally.

Further, as shown in <FIG>, the cup gasket <NUM> is an annular member having an L-shaped cross-section and is made up of an elastic body such as rubber. To the cup gasket <NUM>, an appropriate interference is given between the rotating-side sealing ring <NUM> and the inner cylinder part 12a of the sleeve <NUM>, and sealing performance and a fixed power are ensured.

Then, the rotating-side sealing ring <NUM> is contained in an annular space 10a of the sleeve <NUM> so that the sliding face S faces the opening 12p of the sleeve <NUM>, the back surface side and the inner circumferential side of the rotating-side sealing ring <NUM> are fixed to the sleeve <NUM> via the cup gasket <NUM>, and thereby the rotating-side cartridge <NUM> is constituted.

Next, the stationary-side cartridge <NUM> will be described. The stationary-side cartridge <NUM> mainly consists of the case <NUM> fixed to the housing <NUM>, the stationary-side sealing ring <NUM> contained in the case <NUM>, the seal member <NUM> provided between the case <NUM> and the stationary-side sealing ring <NUM>, and the biasing means <NUM> which biases the stationary-side sealing ring <NUM> toward the rotating-side sealing ring <NUM>.

The stationary-side sealing ring <NUM> is formed by an annular member having a generally rectangular cross-section, and on the surface opposed to the rotating-side sealing ring <NUM>, the sliding face S is formed. The sliding face S of the stationary-side sealing ring <NUM> is formed in an axially protruding annular part. A pressing surface 21b of the stationary-side sealing ring <NUM> is pressed by the biasing means <NUM> from the leakage side toward the rotating-side sealing ring <NUM>, thereby a predetermined surface pressure is applied to the sliding face S.

The case <NUM> which contains the stationary-side sealing ring <NUM> is an annular member having a generally U-shaped cross-section, and is fixed to the housing <NUM> so that the opening 22p of the case <NUM> is opposed to the rotating-side sealing ring <NUM>. The case <NUM> mainly consists of an outer cylinder part 22c press-fitted and fixed to the housing <NUM>, an end wall 22b extended from one end of the outer cylinder part 22c to the radially inside, and an inner cylinder part 22a extended from an inner diameter side end part of the end wall 22b to the axial direction on the outer cylinder part 22c side. Moreover, on an outer circumferential surface of the inner cylinder part 22a, a holding part 22d for containing the seal member <NUM> is formed. The holding part 22d is an annular groove consisting of a bottom wall 22e, and a pair of annular wall parts 22f, <NUM> stood from the bottom wall 22e. Moreover, at least one of the wall parts 22f, <NUM> is opened and inclined toward the radially outside. The width of the holding part 22d for containing the seal member <NUM> is formed larger than the width of the seal member <NUM>, and the depth of the holding part 22d is formed larger than a gap between an inner circumferential surface 21a (an inner circumferential portion) of the stationary-side sealing ring <NUM> and an outer diameter portion of the holding part 22d, that is, outer diameter portions of the wall parts 22f, <NUM>.

The seal member <NUM> held by the holding part 22d is compressively deformed in the radial direction between the inner circumferential surface 21a of the stationary-side sealing ring <NUM> and the case <NUM> and adhered to them, thereby sealing between the stationary-side sealing ring <NUM> and the case <NUM>. Moreover, the seal member <NUM> is regulated at both sides in the axial direction thereof by the wall part 22f and the wall part <NUM> of the holding part 22d from axially moving, so the seal member <NUM> contacts the inner circumferential surface 21a of the stationary-side sealing ring <NUM> only at the outer diameter side thereof. Even if the rotating-side sealing ring <NUM> is largely displaced relative to the case <NUM>, the seal member <NUM> and the inner circumferential surface 21a of the stationary-side sealing ring <NUM> contact with each other at only one point, so the stationary-side sealing ring <NUM> is not restrained by the seal member <NUM> from moving and can follow the movement of the rotating-side sealing ring <NUM> to provide reliable sealing properties. Moreover, the surface formed by radially extending the pressing surface 21b of the stationary-side sealing ring <NUM> is set so as to pass the seal member <NUM>, so the biasing means <NUM> can efficiently correct the posture of the stationary-side sealing ring <NUM> with less biasing force.

Moreover, the width of the holding part 22d for containing the seal member <NUM> is formed larger than the width of the seal member <NUM>, so the seal member <NUM> has an axial gap between the holding part 22d and itself, and can absorb axial swelling due to deformation of the seal member <NUM>. Further, the depth of the holding part 22d is formed larger than the gap between the inner circumferential surface 21a of the stationary-side sealing ring <NUM> and the outer diameter portion of the holding part 22d, that is, the outer diameter portions of the wall parts 22f, <NUM>, so the seal member <NUM> can be prevented from protruding from the holding part 22d.

Further, the inner circumferential surface 21a of the stationary-side sealing ring <NUM> is formed into same diameter along almost the entire axial length, so the mechanical seal can be made compact. Moreover, the inner circumferential surface of the stationary-side sealing ring is formed into the same diameter, so even if a mold-release material such as SiC is used, molding is facilitated, and stabilization of quality and reduction of cost are possible.

The sliding component according to a second embodiment, which is not covered by the subject-matter of the claims but is considered useful for understanding the invention, will be described. <FIG> shows the sliding component according to the second embodiment, and the second embodiment is only different from the first embodiment in that an inner circumferential surface 31a of a stationary-side sealing ring <NUM> is a tapered surface, and other configurations are the same as those in the first embodiment. Hereinafter, the same members as those in the first embodiment are denoted by the same numerals and symbols, and redundant descriptions will be omitted.

As shown in <FIG>, the inner circumferential surface 31a (the inner circumferential portion) of the stationary-side sealing ring <NUM> is a tapered surface. The inner circumferential surface 31a of the stationary-side sealing ring <NUM> is tapered and therefore can be easily fitted to the seal member <NUM> attached to the holding part 22d of the case <NUM>, and it is possible to easily set the stationary-side sealing ring <NUM> in a predetermined position. The seal member <NUM> is compressively deformed in the radial direction between the inner circumferential surface 31a of the stationary-side sealing ring <NUM> and the case <NUM> and adhered to them, thereby sealing between the stationary-side sealing ring <NUM> and the case <NUM>. Moreover, the seal member <NUM> is regulated at both sides in the axial direction thereof by the wall part 22f and the wall part <NUM> of the holding part 22d from axially moving, and contacts the inner circumferential surface 31a of the stationary-side sealing ring <NUM> only at the outer diameter side thereof. Thereby, even if the rotating-side sealing ring <NUM> is largely displaced relative to the case <NUM>, the seal member <NUM> and the inner circumferential surface 31a of the stationary-side sealing ring <NUM> contact with each other at only one point, so the stationary-side sealing ring <NUM> is not restrained by the seal member <NUM> from moving and can follow the movement of the rotating-side sealing ring <NUM> to provide reliable sealing properties.

The sliding component according to a third embodiment which is part of the present invention will be described. <FIG> shows the sliding component according to the third embodiment, and the third embodiment is only different from the first and the second embodiments in the shape of a case <NUM> which contains the stationary-side sealing rings <NUM>, <NUM>, and other configurations are the same as those in the first and the second embodiments. Hereinafter, the same members as those in the first embodiment are denoted by the same numerals and symbols, and redundant descriptions will be omitted.

As shown in <FIG>, the case <NUM> which contains the stationary-side sealing ring <NUM> is an annular member having a generally U-shaped cross-section, and is fixed to the housing <NUM> so that an opening 32p of the case <NUM> is opposed to the rotating-side sealing ring <NUM>. The case <NUM> mainly consists of an outer cylinder part 32c press-fitted and fixed to the housing <NUM>, an end wall 32b extended from one end of the outer cylinder part 32c to the radially inside, and an inner cylinder part 32a extended from an inner diameter side end part of the end wall 32b to the axial direction on the outer cylinder part 32c side. Moreover, in the inner cylinder part 32a, a predetermined number (six in the embodiment of <FIG>) of claw parts 32f are formed at the end part on the opening 32p side.

As shown in <FIG>, after the seal member <NUM> is attached to the outer circumferential surface of the inner cylinder part 32a, the claw parts 32f are bent so as to face the radial direction. Thereby, a holding part 32d consisting of a bottom wall 32e, an annular wall part <NUM> stood from the bottom wall 32e, and the claw part 32f is formed, and the seal member <NUM> is contained in the holding part 32d. The holding part 32d is formed by bending the claw part 32f after the seal member <NUM> is attached to the outer circumferential surface of the inner cylinder part 32a, so it is possible to easily attach the seal member <NUM> to the case <NUM>, and it is possible to prevent damage of the seal member <NUM> when attached to the case <NUM>.

Hereinbefore, although the embodiments of the present invention have been described by the drawings, its specific configuration is not limited to these embodiments, and any changes and additions made without departing from the scope of the present invention are included in the present invention.

For example, the above embodiments show the case where the rotating-side sealing ring <NUM> is disposed in the sleeve <NUM> and sealed by the cup gasket <NUM> as an example, but the present invention is not limited thereto. For example, without using the sleeve <NUM> and the cup gasket <NUM>, the rotating-side sealing ring <NUM> may be sealed by providing a seal member between the rotating-side sealing ring <NUM> and the rotating shaft <NUM>.

In the above embodiments, an O-ring is used as the seal member <NUM>, but the present invention is not limited thereto. For example, as shown in <FIG>, instead of an O-ring, an X-ring <NUM> (<FIG>), a U-ring <NUM> (<FIG>), or a V-ring (not shown) may be used as the seal member <NUM>. The X-ring <NUM>, the U-ring <NUM>, and the V-ring can reduce sliding resistance compared to an O-ring, so even if the rotating-side sealing ring <NUM> and the stationary-side sealing rings <NUM>, <NUM> are relatively displaced to the cases <NUM>, <NUM>, the stationary-side sealing rings <NUM>, <NUM> are not restrained by the seal members <NUM>, <NUM> from moving and can follow the movement of the rotating-side sealing ring <NUM> to provide reliable sealing properties.

Moreover, as shown in <FIG>, as a seal member <NUM>, a combination seal including an O-ring 53a and a cap 53b may be used. The cap 53b is formed of a low friction material such as PTFE, so it is possible to reduce sliding resistance between the stationary-side sealing rings <NUM>, <NUM> and the seal member <NUM>. Thereby, even if the rotating-side sealing ring <NUM> and the stationary-side sealing rings <NUM>, <NUM> are relatively displaced to the cases <NUM>, <NUM>, the stationary-side sealing rings <NUM>, <NUM> are not restrained by the seal member <NUM> from moving and can follow the movement of the rotating-side sealing ring <NUM> to provide reliable sealing properties.

Claim 1:
A mechanical seal (<NUM>) in which a rotating-side sealing ring (<NUM>) suitable to be attached to a shaft (<NUM>) and a stationary-side sealing ring (<NUM>) suitable to be attached to a housing (<NUM>) slide relative to each other and seal, in use, between the housing (<NUM>) and the shaft (<NUM>),
the mechanical seal (<NUM>) includes a case (<NUM>) which is suitable to be attached to the housing (<NUM>) and which contains the stationary-side sealing ring (<NUM>), and a seal member (<NUM>; <NUM>; <NUM>; <NUM>) which is disposed between the case (<NUM>) and the stationary-side sealing ring (<NUM>); and
the case (<NUM>) includes a holding part (32d) which is configured to regulate the seal member (<NUM>; <NUM>; <NUM>; <NUM>) from moving to both sides in an axial direction thereof, wherein the case (<NUM>) has an outer cylinder part (32c) suitable to be fixed to the housing (<NUM>), an end wall (32b) extended from one end of the outer cylinder part (32c) to a radially inside, and an inner cylinder part (32a) extended from an inner diameter side end part of the end wall (32b) to the axial direction on a side of the outer cylinder part (32c), so that in use, an opening (32p) of the case (<NUM>) is opposed to the rotating-side sealing ring (<NUM>),
wherein the holding part (32d) is on an outer circumferential surface of the inner cylinder part (32a), wherein the holding part (32d) consists of a bottom wall (32e), an annular wall part (<NUM>) stood from the bottom wall (32e), and a plurality of claw parts (32f) which are formed at an end part of the inner cylinder part (32a) on a side of the opening (32p),
characterized in that each claw part (32f) is bent so as to face in a radial direction.