Patent Description:
Heretofore, a shock-absorbing stopper <NUM> illustrated in <FIG> is known. The shock-absorbing stopper <NUM> has a cylindrical elastic body <NUM>, in which a fixed-side metal fitting <NUM> is connected to one end portion (upper end portion in the figure) of the elastic body <NUM> and a movable-side metal fitting <NUM> is connected to the other end portion (lower end portion in the figure) thereof. The one end portion (hereinafter sometimes also referred to as a fixed-side end portion <NUM>) to which the fixed-side metal fitting <NUM> is connected is fixed to a housing <NUM> which is a mating component. A shaft (not illustrated) which is an actuating component collides with the other end portion (hereinafter sometimes also referred to as a movable-side end portion <NUM>) to which the movable-side metal fitting <NUM> is connected, so that the other end portion is displaced together with the shaft. Patent Document <NUM> shows a generic shock-absorbing stopper having the features according to the preamble of claim <NUM>.

Patent Document <NUM> shows another conventional shock-absorbing stopper.

Patent Document <NUM>, which is considered the closest prior art, discloses another conventional shock-absorbing stopper.

When the shaft collides with the movable-side end portion <NUM>, so that a load P is applied as illustrated in <FIG>, the movable-side end portion <NUM> is displaced in a direction approaching the fixed-side end portion <NUM>, so that the elastic body <NUM> is compressed. Therefore, the shock absorbing function by the compression and deformation of the elastic body <NUM> is exhibited. An outer peripheral surface 52a of the compressed elastic body <NUM> is radially outward swollen and deformed to contact an inner peripheral surface 61a of the housing <NUM>. The movable-side end portion <NUM> is continuously displaced also after the elastic body <NUM> contacts the housing <NUM>, and therefore the elastic body <NUM> slides in a contact portion with the housing <NUM>. Therefore, wear due to the sliding occurs, so that the performance of the stopper <NUM> decreases.

In order to suppress the sliding wear of the elastic body <NUM>, it is considered to provide an annular hollow <NUM> in the outer peripheral surface of the elastic body <NUM> as illustrated in a reference example of <FIG> to thereby reduce the swollen and deformed amount when compressed to reduce the contact surface pressure to the housing <NUM>.

However, when the hollow <NUM> is provided in the outer peripheral surface of the elastic body <NUM> as described above, the following points need to be taken into consideration.

More specifically, when the hollow <NUM> is provided in the outer peripheral surface of the elastic body <NUM> as described above, the stopper <NUM> is sectioned into three portions of a small diameter portion 51A formed by the hollow <NUM>, a fixed-side large diameter portion 51B located closer to the fixed side relative to the hollow <NUM>, and a movable-side large diameter portion 51C located closer to the movable side relative to the hollow <NUM>.

In this case, when an outer diameter dimension φd<NUM> of the fixed-side large diameter portion 51B and an outer diameter dimension φd<NUM> of the movable-side large diameter portion 51C are equally set φd<NUM> = φd<NUM>) and an axial width w<NUM> of the fixed-side large diameter portion 51B and an axial width w<NUM> of the movable-side large diameter portion 51C are equally set (w<NUM> = w<NUM>) so as to equalize the dimensions, there is a possibility that the following inconvenience may occur.

More specifically, according to the above-described setting (φd<NUM> = φd<NUM> and w<NUM> = w<NUM>), an axial width w<NUM> of the elastic body <NUM> obtained by subtracting an axial width (thickness) w<NUM> of the movable-side metal fitting <NUM> from the axial width w<NUM> of the movable-side large diameter portion 51C is set considerably large.

Therefore, when the shaft collides with the movable-side end portion <NUM>, so that the load P is applied, whereby the movable-side end portion <NUM> is displaced in a direction approaching the fixed-side end portion <NUM>, so that the elastic body <NUM> is compressed, the outer peripheral surface of the elastic body <NUM> is radially outward swollen and deformed in the movable-side large diameter portion 51C to contact the inner peripheral surface 61a of the housing <NUM>. Then, the movable-side end portion <NUM> is continuously displaced also after the elastic body <NUM> contacts the housing <NUM> as described above, and therefore the elastic body <NUM> slides in the movable-side large diameter portion 51C, so that the wear due to the sliding occurs. This phenomenon is likely to occur particularly when the axial displacement amount of the movable-side end portion <NUM> to the fixed-side end portion <NUM> is excessively large (larger than expected).

In view of the above-described points, it is an object of the present invention to provide a shock-absorbing stopper capable of preventing an elastic body from contacting a mating component, such as a housing, to cause sliding wear as much as possible in a structure where a hollow is provided in the outer peripheral surface of the elastic body.

The object is achieved by a shock-absorbing stopper having the features of claim <NUM>. In order to achieve the above-described object, a shock-absorbing stopper of the present invention has a cylindrical elastic body, to one end portion of which a fixed-side metal fitting is connected and to the other end portion of which a movable-side metal fitting is connected and which has an annular hollow in the outer peripheral surface of the cylindrical elastic body, in which the shock-absorbing stopper is sectioned into three portions by the hollow of a small diameter portion formed by the hollow, a fixed-side large diameter portion located closer to the fixed side relative to the hollow, and a movable-side large diameter portion located closer to the movable side relative to the hollow, the outer diameter dimension of the movable-side large diameter portion is set smaller than the outer diameter dimension of the fixed-side large diameter portion, and the axial width of the movable-side large diameter portion is set smaller than the axial width of the fixed-side large diameter portion.

In the structure where the hollow is provided in the outer peripheral surface of the elastic body, a portion where the sliding wear is likely to occur is the outer peripheral surface of the movable-side large diameter portion located closer to the movable side relative to the hollow among the sectioned three portions. Then, the present invention is configured so that the outer diameter dimension of the movable-side large diameter portion is set smaller than the outer diameter dimension of the fixed-side large diameter portion, and thus a relatively large radial gap is set between the movable-side large diameter portion and the mating component, such as a housing. Moreover, the axial width of the movable-side large diameter portion is set smaller than the axial width of the movable-side large diameter portion, and thus, even when the movable-side large diameter portion is swollen and deformed, the swollen and deformed amount is suppressed. Accordingly, the radial gap is set large by the former and the swollen and deformed amount is suppressed by the latter, and therefore the movable-side large diameter portion does not contact the housing even when the movable-side large diameter portion is swollen and deformed or, even when the movable-side large diameter portion contacts the housing, the contact surface pressure or the contact width can be reduced. Therefore, the sliding wear is hard to occur in the movable-side large diameter portion.

The present invention can prevent an elastic body from contacting a mating component, such as a housing, to cause sliding wear as much as possible in a structure where a hollow is provided in the outer peripheral surface of the elastic body.

Next, a comparative example and an embodiment of the present invention are described with reference to the drawings.

As illustrated in <FIG>, a shock-absorbing stopper <NUM> according to this example has a cylindrical elastic body <NUM> containing a predetermined rubber-like elastic body, in which an annular fixed-side metal fitting <NUM> is connected to one axial end portion (upper end portion in the figure) of the cylindrical elastic body <NUM> and an annular movable-side metal fitting <NUM> is connected to the other axial end portion (lower end portion in the figure) thereof. The one end portion (hereinafter sometimes also referred to as a fixed-side end portion <NUM>) to which the fixed-side metal fitting <NUM> is connected is fixed to the housing <NUM> which is a mating component. A shaft (not illustrated) which is an actuating component collides with the other end portion (hereinafter sometimes also referred to as a movable-side end portion <NUM>) to which the movable-side metal fitting <NUM> is connected, so that the other end portion is displaced together with the shaft.

An annular hollow <NUM> is provided in the outer peripheral surface of the elastic body <NUM>. Moreover, due to the fact that the annular hollow <NUM> is provided in the outer peripheral surface of the elastic body <NUM> as described above, the shock-absorbing stopper <NUM> is sectioned into three portions, that is, a small diameter portion 11A formed by the hollow <NUM>, and having an outer peripheral surface of a relatively small diameter, a fixed-side large diameter portion 11B located closer to the fixed side relative to the hollow <NUM> and having an outer peripheral surface of a relatively large diameter, and a movable-side large diameter portion 11C located closer to the movable side relative to the hollow <NUM> and having an outer peripheral surface of a relatively large diameter.

Furthermore, in this example, the outer diameter dimension φd<NUM> of the movable-side large diameter portion 11C is set smaller than the outer diameter dimension φd<NUM> of the fixed-side large diameter portion 11B (φd<NUM> > φd<NUM>) and the axial width w<NUM> of the movable-side large diameter portion 11C is set smaller than the axial width w<NUM> of the fixed-side large diameter portion 11B (w<NUM> > w<NUM>) among the sectioned three portions.

In the shock-absorbing stopper <NUM> of the above-described configuration, when the shaft collides with the movable-side end portion <NUM>, so that the load P is applied, whereby the movable-side end portion <NUM> is displaced in a direction approaching the fixed-side end portion <NUM>, so that the elastic body <NUM> is compressed, the outer peripheral surface of the elastic body <NUM> tends to be radially outward swollen and deformed in the movable-side large diameter portion 11C to contact the inner peripheral surface 61a of the housing <NUM>. However, the outer diameter dimension φd<NUM> of the movable-side large diameter portion 11C is set smaller than the outer diameter dimension φd<NUM> of the fixed-side large diameter portion 11B (φd<NUM> > φd<NUM>) as described above, and therefore a relatively large radial gap c is set between the movable-side large diameter portion 11C and the inner peripheral surface 61a of the housing <NUM>.

Moreover, the axial width w<NUM> of the movable-side large diameter portion 11C is set smaller than the axial width w<NUM> of the fixed-side large diameter portion 11B (w<NUM> > w<NUM>) as described above, and therefore, even when the movable-side large diameter portion 11C is swollen and deformed, the swollen and deformed amount can be suppressed.

Accordingly, the radial gap c is set large due to φd<NUM> > φd<NUM> of the former and the swollen and deformed amount is suppressed due to w<NUM> > w<NUM> of the latter, and therefore the movable-side large diameter portion 11C does not contact the housing <NUM> even when the movable-side large diameter portion 11C is swollen and deformed or, even when the movable-side large diameter portion 11C contacts the housing <NUM>, the contact surface pressure and the contact width can be reduced. Therefore, the sliding wear is hard to occur in the movable-side large diameter portion 11C.

The comparative example described above is configured so that the axial width w<NUM> of the movable-side large diameter portion 11C is the sum of the axial width (thickness) w<NUM> of the movable-side metal fitting <NUM> and the axial width w<NUM> between the hollow <NUM> in the elastic body <NUM> and the movable-side metal fitting <NUM>, and as the axial width w<NUM> of the movable-side large diameter portion 11C becomes small, the axial width w<NUM> between the hollow <NUM> in the elastic body <NUM> and the movable-side metal fitting <NUM> also becomes small in connection therewith. However, the axial width w<NUM> of the movable-side large diameter portion 11C may be set only by the axial width (thickness) w<NUM> of the movable-side metal fitting <NUM>. In this case, the axial width w<NUM> between the hollow <NUM> in the elastic body <NUM> and the movable-side metal fitting <NUM> is set to zero.

In a shock-absorbing stopper <NUM> illustrated in <FIG> as an embodiment, the axial width w<NUM> of the movable-side large diameter portion 11C is set only by the axial width (thickness) w<NUM> of the movable-side metal fitting <NUM> and the axial width between the hollow <NUM> in the elastic body <NUM> and the movable-side metal fitting <NUM> is set to zero from such a viewpoint.

According to this configuration, the position of the hollow <NUM> further shifts to the movable-side as compared with the first embodiment, and therefore the elastic body <NUM> does not contact the housing <NUM> even when the elastic body <NUM> is swollen and deformed or, even when the elastic body <NUM> contacts the housing <NUM>, the contact surface pressure and the contact width can be further reduced. Therefore, the sliding wear is harder to occur in the elastic body <NUM>.

Claim 1:
A shock-absorbing stopper (<NUM>) comprising:
a cylindrical elastic body (<NUM>), to a fixed-side end portion (<NUM>) of which a fixed-side metal fitting (<NUM>) is connected and to a movable-side end portion (<NUM>) of which a movable-side metal fitting (<NUM>) is connected and which has an annular hollow (<NUM>) in an outer peripheral surface of the cylindrical elastic body (<NUM>), wherein
the shock-absorbing stopper (<NUM>) is sectioned into three portions by the hollow (<NUM>) of a small diameter portion (11A) formed by the hollow (<NUM>), a fixed-side large diameter portion (11B) located closer to a fixed side relative to the hollow (<NUM>), and a movable-side large diameter portion (11C) located closer to a movable side relative to the hollow (<NUM>),
an outer diameter dimension (Φd<NUM>) of the movable-side large diameter portion (11C) is set smaller than an outer diameter dimension (Φd<NUM>) of the fixed-side large diameter portion (11B), and
an axial width (w<NUM>) of the movable-side large diameter portion (11C) is set smaller than an axial width (w<NUM>) of the fixed-side large diameter portion (11B), wherein
the outer peripheral surface of the small diameter portion (11A), the fixed-side large diameter portion (11B) and the movable-side large diameter portion (11C) at the elastic body (<NUM>) is configured to be radially outward swollen and deformed when the elastic body (<NUM>) is compressed by a load applied to the movable-side metal fitting (<NUM>), whereby the movable-side end portion (<NUM>) is displaced in a direction approaching the fixed-side end portion (<NUM>),
an outer diameter dimension of the small diameter portion (11A) is set smaller than the outer diameter dimension (Φd<NUM>) of the fixed-side large diameter portion (11B) and the outer diameter dimension (Φd<NUM>) of the movable-side large diameter portion (11C),
the axial width (w<NUM>) of the movable-side large diameter portion (11C) is set only by an axial width (w<NUM>) of the movable-side metal fitting (<NUM>), and
an axial width (w<NUM>) between the hollow (<NUM>) in the elastic body (<NUM>) and the movable-side metal fitting (<NUM>) is set to zero.