JP5541046B2 - Cart wheel - Google Patents

Description

  The present invention relates to a cart wheel used in a racing cart or the like, and more particularly, facilitates the work of attaching and detaching a bead stopper, preventing air leakage from the bead stopper mounting portion, and preventing damage to the rim. It relates to a cart wheel that makes it possible.

  In cart wheels used for racing carts, etc., a hole is formed so as to penetrate the rim at a position adjacent to the bead seat portion of the rim so that the bead portion of the tire does not fall off the rim, and the bead is formed in the hole. A stopper is inserted.

  Such a bead stopper has a shaft portion inserted into the hole of the rim and a head portion wider than the hole, and a male screw portion is machined on the outer peripheral surface of the shaft portion. On the other hand, a female thread portion is machined on the inner peripheral surface of the rim hole. Then, with the ring-shaped packing arranged around the shaft portion of the bead stopper interposed between the head portion of the bead stopper and the rim, the shaft portion of the bead stopper is screwed into the hole of the rim, and the shaft portion Is sufficiently protruded from the outer peripheral surface of the rim so that a bead stopper is attached to the rim (see, for example, Patent Document 1 [Prior Art]).

  However, the above-described bead stopper not only takes a great deal of time for mounting and removal, but if an excessive force is applied when the bead stopper is tightened, the packing may be damaged and air leakage may occur. In addition, when the bead stopper is screwed, the internal thread portion processed in the hole of the rim may be damaged, resulting in an unrepairable state. In this case, there is a problem that the wheel itself becomes unusable.

Japanese Utility Model Publication No. 61-64004

  An object of the present invention is to provide a cart wheel that makes it easy to attach and detach the bead stopper, prevents air leakage from the bead stopper mounting portion, and prevents damage to the rim.

  In order to achieve the above object, a cart wheel according to the present invention is a cart wheel having a rim to which a bead portion of a tire is fitted, and passes through the rim at a position adjacent to the bead seat portion of the rim. A bead stopper having a shaft portion inserted into the hole and a head portion wider than the hole, and a head portion of the bead stopper and the rim disposed around the shaft portion of the bead stopper. And an elastic body ring interposed between them, and a protrusion is provided on the inner surface of the hole, while the protrusion can be accommodated in the shaft portion of the bead stopper and extends in a spiral shape with a length of less than two rounds. A screw groove is provided, one end portion of the screw groove is opened to the tip end side of the shaft portion, and a locking portion for locking the protrusion is provided at the other end portion of the screw groove. Is.

  In the present invention, a protrusion is provided on the inner surface of the hole of the rim, while a screw groove that can be accommodated in the shaft portion of the bead stopper and extends in a spiral shape with a length of less than two rounds is provided. Since the end of the shaft is opened to the tip end side of the shaft and the other end of the screw groove is provided with a locking portion for locking the protrusion, the elastic body is used when the bead stopper is mounted on the rim. With the ring interposed between the head of the bead stopper and the rim, the shaft of the bead stopper is inserted into the hole of the rim while the protrusion is received in the screw groove, and the rotation speed of the bead stopper is less than two revolutions. Just tighten with. Similarly, when removing the bead stopper from the rim, it is only necessary to loosen the bead stopper at a rotational speed of less than two laps. Therefore, the attaching / detaching operation of the bead stopper can be performed more simply than before.

  Also, tightening of the bead stopper only needs to be finished when the protrusion reaches the locking part, and it is difficult to cause damage to the elastic ring due to excessive tightening, so air leakage from the bead stopper mounting part is prevented. Can do. In addition, since the protrusions that are not easily damaged are provided on the inner surface of the rim hole, damage to the rim can be prevented.

  The locking portion formed at the other end of the thread groove has a function of locking the protrusion in a state where the bead stopper is tightened and a repulsive force is generated in the elastic ring. The locking part has a structure in which the other end of the thread groove is extended in a direction perpendicular to the axial direction of the bead stopper, or the other end of the thread groove is directed toward the tip end side of the shaft part. A bent structure is preferable. In particular, when the other end portion of the thread groove is bent toward the distal end side of the shaft portion in the locking portion, it is possible to more reliably prevent the bead stopper from coming off.

  In this case, the thickness B of the elastic ring when the elastic ring is most compressed in the work of mounting the bead stopper to the rim is 50% to 60% of the thickness A in the unloaded state, and The threaded groove is arranged on the shaft so that the thickness C of the elastic ring with the projection locked in the locking portion is 70% to 80% of the thickness A in the unloaded state. It is preferable to do. As a result, the bead stopper can be attached / detached smoothly, the bead stopper can be prevented from coming off more reliably, and air leakage can be prevented more reliably.

  The cross-sectional shape of the elastic ring is preferably circular or elliptical. The elastic ring preferably contains nitrile rubber as a main component and has a JIS-A hardness of 40 to 70. Thereby, favorable air leakage prevention performance can be ensured. Here, JIS-A hardness is durometer hardness measured using an A type durometer in a durometer hardness test specified in JIS K6253.

It is a front view which shows the wheel for carts which consists of embodiment of this invention with the tire assembled | attached to it. It is sectional drawing which expands and shows the rim | limb of the cart wheel of FIG. It is a top view which expands and shows the hole for bead stoppers formed in the rim | limb of the cart wheel of FIG. It is a top view which shows the bead stopper of the wheel for carts of FIG. It is a side view which shows the bead stopper of the wheel for carts of FIG. It is a side view which shows the state which mounted | wore the rim with the bead stopper of the cart wheel of FIG. It is a side view which shows the modification of a bead stopper. It is a side view which shows the modification of the hole for bead stoppers. It is a top view which shows the bead stopper corresponding to the hole of FIG. It is a side view which shows the bead stopper corresponding to the hole of FIG.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. 1 shows a cart wheel according to an embodiment of the present invention, FIG. 2 shows an enlarged rim thereof, FIG. 3 shows an enlarged hole for a bead stopper formed on the rim, and FIGS. FIG. 6 shows the bead stopper.

  As shown in FIG. 1, the cart wheel W is composed of a disc 1 mounted on an axle and a rim 2 to which a bead portion of a pneumatic tire T is fitted. The cart wheel W includes a plurality of bead stoppers 3 attached to the rim 2, and these bead stoppers 3 are arranged at equal intervals on the circumference. Reference numeral 4 denotes an air valve.

  As shown in FIG. 2, a hole 22 is formed at a position adjacent to the bead seat portion 21 of the rim 2 so as to penetrate the rim 2. On the other hand, the bead stopper 3 includes a shaft portion 31 inserted into the hole 22, a head portion 32 wider than the hole 22, and a knob portion 33 attached to the head portion 32. Although the constituent material of the bead stopper 3 is not specifically limited, For example, a metal and a synthetic resin can be used.

  In particular, the tensile strength of the constituent material of the bead stopper 3 is preferably 50 MPa or less. That is, when removing the pneumatic tire T from the rim 2, there is a possibility that the bead portion is dropped from the bead seat portion 21 using the bead breaker without accidentally removing the bead stopper 3. When a material having a tensile strength of 50 MPa or less is used as a constituent material of the bead stopper 3, the bead stopper 3 may be broken when the above-described erroneous operation is performed, thereby preventing the rim 2 from being damaged. it can.

  An elastic ring 5 is disposed around the shaft portion 31 of the bead stopper 3, and the elastic ring 5 is interposed between the head 32 of the bead stopper 3 and the rim 2. The cross-sectional shape of the elastic ring 5 is circular or elliptical. The elastic ring 5 is preferably composed of nitrile rubber as a main component (50% by weight or more of the rubber component is nitrile rubber) and has a JIS-A hardness of 40 to 70. By adopting such a material and hardness, air leakage prevention performance based on the elastic ring 5 can be sufficiently ensured.

  As shown in FIG. 3, a massive protrusion 23 is formed on the inner surface of the hole 22. The protrusion 23 is a part of the circumference of the hole 22 and protrudes from the inner surface toward the center of the hole 22. On the other hand, as shown in FIGS. 4 and 5, the shaft portion 31 of the bead stopper 3 has one screw groove having a cross-sectional shape capable of accommodating the protrusion 23 and extending spirally with a length of less than two rounds. 34 is processed. One end of the screw groove 34 opens to the tip end side of the shaft portion 31, but the other end of the screw groove 34 terminates to form a locking portion 35 for locking the protrusion 23. Yes. More specifically, the locking portion 35 has a structure in which the other end portion of the screw groove 34 is bent toward the distal end side of the shaft portion 31.

  Next, a method for attaching and detaching the bead stopper 3 in the cart wheel W described above will be described. When the bead stopper 3 is mounted on the rim 2, the protrusion 23 is accommodated in the screw groove 34 with the elastic ring 5 interposed between the head 32 of the bead stopper 3 and the rim 2. While inserting the shaft portion 31 of the bead stopper 3 into the hole 22 of the rim 2, the bead stopper 3 is tightened at a rotational speed of less than two rounds. As a result, the bead stopper 3 is attached to the rim 2 in the state shown in FIG. Similarly, when removing the bead stopper 3 from the rim 2, it is only necessary to loosen the bead stopper 3 at a rotational speed of less than two revolutions. Therefore, unlike the conventional case where the rotation speed is 12 to 15 times, the bead stopper 3 can be easily attached and detached.

  Further, the tightening of the bead stopper 3 may be finished when the projection 23 reaches the engaging portion 35 which is the end of the thread groove 34, and the elastic ring 5 is not easily damaged due to excessive tightening. Air leakage from the mounting portion of the stopper 3 can be prevented. In addition, since the inner surface of the hole 22 of the rim 2 is provided with a massive projection instead of a thread, damage to the rim 2 can be prevented.

  In particular, in the above-described embodiment, since the other end of the screw groove 34 is bent toward the distal end side of the shaft portion 31 in the locking portion 35, the bead stopper 3 is effectively removed. Can be prevented. That is, in the process of tightening the bead stopper 3, the elastic ring 5 is most compressed when the projection 23 is located closest to the head portion 32 of the screw groove 34, and the projection 23 is the end of the screw groove 34. When the stop portion 35 is reached, a certain amount of compression of the elastic ring 5 is released, but the compressed state is still maintained. Therefore, in such a state, since the projection 23 is firmly locked to the locking portion 35 based on the restoring force of the elastic ring 5, the bead stopper 3 rotates unexpectedly even if vibration occurs in the wheel W. There is nothing. Further, when the other end portion of the screw groove 34 is bent toward the tip end side of the shaft portion 31 in the locking portion 35, it is confirmed that the protrusion 23 has reached the locking portion 35 that is the terminal end of the screw groove 34. There is also an advantage that it can be easily recognized based on the reaction force inside.

  In the above embodiment, the thickness B of the elastic ring 5 in the state where the elastic ring 5 is most compressed in the mounting operation of the bead stopper 3 to the rim 2 is 50% of the thickness A in the unloaded state. The shaft so that the thickness C of the elastic ring 5 in a state where the projection 23 is locked to the locking portion 35 is 70% to 80% of the thickness A in the unloaded state. A screw groove 34 may be disposed on the portion 31. As a result, the bead stopper 3 can be attached / detached smoothly, the bead stopper 3 can be more reliably prevented from being detached, and air leakage can be more reliably prevented. When the thickness B of the elastic ring 5 is less than 50% of the thickness A, it becomes difficult to attach and detach the bead stopper 3, and conversely, when the thickness B exceeds 60% of the thickness A, the bead stopper 3 is likely to come off. Further, if the thickness C of the elastic ring 5 is less than 70% of the thickness A, the elastic ring 5 is likely to be damaged, and conversely if it exceeds 80% of the thickness A, air leakage is likely to occur.

  FIG. 7 is a side view showing a modified example of the bead stopper. 7, the same components as those in FIG. 6 are denoted by the same reference numerals, and detailed description thereof is omitted. In the present embodiment, the other end of the screw groove 34 terminates to form a locking portion 35A for locking the protrusion 23. The locking portion 35 </ b> A has a structure in which the other end portion of the screw groove 34 is extended in a direction orthogonal to the axial direction of the bead stopper 3.

  In the embodiment described above, when the bead stopper 3 is attached to the rim 2, the elastic ring 5 is interposed between the head 32 of the bead stopper 3 and the rim 2, and the inside of the screw groove 34. The shaft portion 31 of the bead stopper 3 is inserted into the hole 22 of the rim 2 while the protrusion 23 is accommodated, and the bead stopper 3 is tightened at a rotational speed of less than two turns. When the protrusion 23 reaches the locking portion 35A that is the terminal end of the screw groove 34, the elastic ring 5 is in a compressed state, and the other end of the screw groove 34 is connected to the axial direction of the bead stopper 3 in the locking portion 35A. Since the structure extends in the orthogonal direction, the protrusion 23 is locked to the locking portion 35 </ b> A based on the restoring force of the elastic ring 5. As a result, the bead stopper 3 is attached to the rim 2 in the state shown in FIG.

  In this case, the shaft portion 31 is formed such that the thickness C of the elastic ring 5 in a state where the projection 23 is locked to the locking portion 35A is 70% to 80% of the thickness A in the unloaded state. On the other hand, a screw groove 34 is preferably provided. Thereby, an air leak can be prevented more reliably. If the thickness C of the elastic ring 5 is less than 70% of the thickness A, the elastic ring 5 is likely to be damaged, and conversely if it exceeds 80% of the thickness A, air leakage is likely to occur.

  FIG. 8 shows a modified example of the hole for the bead stopper, and FIGS. 9 and 10 show the bead stopper corresponding to the hole of FIG. 8 to 10, the same components as those in FIGS. 3 to 5 are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 8, a pair of protrusions 23 are formed on the inner surface of the hole 22 at opposing positions on the circumference. These protrusions 23 protrude from the inner surface toward the center of the hole 22 at a part of the circumference of the hole 22. On the other hand, in the shaft portion 31 of the bead stopper 3, as shown in FIGS. 9 and 10, there are two screw grooves having a cross-sectional shape capable of accommodating the protrusion 23 and extending in a spiral shape with a length of less than two rounds. 34 are respectively processed at positions corresponding to the two protrusions 23. One end of the screw groove 34 opens to the tip end side of the shaft portion 31, but the other end of the screw groove 34 terminates to form a locking portion 35 for locking the protrusion 23. Yes. That is, the locking portion 35 has a structure in which the other end portion of the screw groove 34 is bent toward the distal end side of the shaft portion 31.

  In this case, since the two screw grooves 34 are provided in the shaft portion 31 of the bead stopper 3 while the pair of protrusions 23 are provided on the inner surface of the hole 22, the behavior when the bead stopper 3 is mounted can be stabilized. In addition, the locking force of the bead stopper 3 can be increased.

  In a cart wheel having a rim to which a bead portion of a tire is fitted, a hole formed so as to penetrate the rim at a position adjacent to the bead seat portion of the rim, a shaft portion inserted into the hole, and A bead stopper having a head wider than the hole; and an elastic ring disposed around the shaft portion of the bead stopper and interposed between the head of the bead stopper and the rim; On the other hand, a screw groove that can be accommodated in the shaft portion of the bead stopper and extends in a spiral shape with a length of less than two rounds is provided, and one end portion of the screw groove is provided at the tip of the shaft portion. Wheels for carts of Example 1 (FIG. 6) and Example 2 (FIG. 7), which were opened to the side and provided with a locking portion for locking the protrusion at the other end of the thread groove, were produced. For comparison, a conventional cart wheel equipped with a screw-in type bead stopper was prepared.

  For these wheels, the following evaluation methods were used to evaluate the mounting work time index, the separation work time index, the air leak trouble frequency index after work, the air leak trouble frequency index during running, and the rim damage frequency index, and the results are shown. It was shown in 1.

Installation time index:
The working time when mounting the bead stopper on the wheel was measured. The evaluation results are shown as an index with the conventional example being 100, using the reciprocal of the measured value. A larger index value means a shorter installation work time.

Detachment time index:
The working time when removing the bead stopper from the wheel was measured. The evaluation results are shown as an index with the conventional example being 100, using the reciprocal of the measured value. A larger index value means a shorter detachment work time.

Air leak trouble frequency index after work:
After attaching a bead stopper to the wheel, the tire was filled with air pressure, and the occurrence frequency of air leakage troubles in a stationary state was measured. The evaluation results are shown as an index with the conventional example being 100, using the reciprocal of the measured value. A larger index value means fewer air leak problems.

Air leak trouble frequency index while driving:
After attaching a bead stopper to the wheel, the tire was filled with air pressure, and the occurrence frequency of air leakage troubles during running was measured. The evaluation results are shown as an index with the conventional example being 100, using the reciprocal of the measured value. A larger index value means fewer air leak problems.

Rim damage frequency index:
The bead stopper was attached to and detached from the wheel, and the frequency of rim damage was measured. The evaluation results are shown as an index with the conventional example being 100, using the reciprocal of the measured value. A larger index value means less rim damage.

  As is clear from Table 1, the wheels of Examples 1 and 2 are compared to the conventional example in the mounting work time index, the separation work time index, the air leak trouble frequency index after work, and the air leak trouble frequency index during traveling. The rim damage frequency index was excellent.

DESCRIPTION OF SYMBOLS 1 Disc 2 Rim 3 Bead stopper 4 Air valve 5 Elastic body ring 21 Bead seat part 22 Hole 23 Protrusion 31 Axle part 32 Head 33 Knob part 34 Screw groove 35 Locking part W Cart wheel T Pneumatic tire

Claims (5)

  In a cart wheel having a rim to which a bead portion of a tire is fitted, a hole formed so as to penetrate the rim at a position adjacent to the bead seat portion of the rim, and a shaft portion inserted into the hole And a bead stopper having a head wider than the hole, and an elastic ring disposed around the shaft portion of the bead stopper and interposed between the head of the bead stopper and the rim, While providing the protrusion on the inner surface, the shaft portion of the bead stopper is provided with a screw groove that can accommodate the protrusion and extends spirally with a length of less than two rounds, and one end of the screw groove is A cart wheel characterized in that an opening is provided on a tip end side of a shaft portion, and a locking portion for locking the protrusion is provided at the other end of the screw groove.   The cart wheel according to claim 1, wherein the other end portion of the screw groove is bent toward the distal end side of the shaft portion in the locking portion.   The thickness B of the elastic ring when the elastic ring is most compressed in the mounting operation of the bead stopper to the rim is 50% to 60% of the thickness A in the unloaded state, and With respect to the shaft portion, the thickness C of the elastic ring in a state where the protrusion is locked to the locking portion is 70% to 80% of the thickness A in an unloaded state. The cart wheel according to claim 2, further comprising a thread groove.   The cart wheel according to any one of claims 1 to 3, wherein a cross-sectional shape of the elastic ring is circular or elliptical.   The cart wheel according to any one of claims 1 to 4, wherein the elastic ring has nitrile rubber as a main component and has a JIS-A hardness of 40 to 70.

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