JP2016064680A - Caster for handcart and baby carriage with the same attached thereto - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a caster for a handcart with improved linear runnability.SOLUTION: A caster 3 includes: a fixed body 40 fixed to a leg of a handcart 1; a rotary body 60 which is held by the fixed body 40 so as to rotate around a caster axis La; and wheels which are held by the rotary body 60 so as to rotate around a rotation axis Lb. The fixed body 40 has a caster shaft 51 defining the caster axis La. The rotary body 60 has a cylinder member 71 into which the caster shaft 51 is inserted. A distance r between the caster axis La and the rotation axis Lb may be changed according to an angle of rotation of the rotary body 60 rotating around the caster axis La relative to the fixed body 40.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a caster for a handcart, and more particularly to a caster for a handcart with improved straight traveling performance. The present invention also relates to a baby carriage fitted with casters for the handcart.

  A caster for a handcart represented by a baby carriage is used as a holding mechanism that rotatably holds a wheel about a rotation axis. The caster can also change the direction of the wheel around a caster axis extending in a direction intersecting the rotation axis. For this reason, the caster changes the direction of the wheel in accordance with the direction of the propulsive force applied to the handcart from the operator, thereby realizing the turning of the handcart intended by the operator.

  For example, as disclosed in Patent Document 1, a caster for a handcart has a fixed body that is fixed to a leg of the handcart, a wheel that rotatably holds the wheel, and a fixed body that is centered on the caster axis. And a rotatable rotating body.

JP 2005-014894 A

  If the wheel gets over the unevenness or level difference on the ground contact surface while the wheelbarrow is running, the rotating body that holds the wheel will be affected by the unevenness or level difference on the ground contact surface. If the rotator is affected by unevenness or a step on the ground contact surface, there is a possibility that a wobble phenomenon occurs in which the rotator slightly vibrates with respect to the fixed body and the caster shaft. When the wobble phenomenon occurs in the rotating body, the rotating state of the rotating body with respect to the fixed body becomes unstable, and the straight traveling performance is deteriorated.

  The present invention has been made in view of the above points, and an object thereof is to provide a caster for a handcart with improved straight traveling performance. Another object of the present invention is to provide a baby carriage to which a caster for a handcart with improved straight traveling performance is attached.

A caster for a wheelbarrow according to the present invention includes a fixed body fixed to a leg of the wheelbarrow,
A rotating body rotatably held by the fixed body about a caster axis;
A wheel rotatably held on the rotating body around a rotation axis,
One of the fixed body and the rotating body has a caster shaft that defines the caster axis,
The other of the fixed body and the rotating body has a cylindrical portion into which the caster shaft is inserted,
The distance between the caster axis and the rotation axis when the rotating body is rotated by a certain first angle with respect to the fixed body about the caster axis is such that the rotating body is centered on the caster axis. The distance between the caster axis and the rotation axis when rotated by a second angle different from the first angle with respect to the fixed body is different.

  In the caster for a handcart according to the present invention, the inner surface of the cylindrical portion contacts the outer peripheral surface of the caster shaft when the rotating body rotates about the caster axis by the first angle with respect to the fixed body. A position where the inner surface of the cylindrical portion can come into contact with the outer peripheral surface of the caster shaft when the rotating body is rotated by the second angle with respect to the fixed body around the caster axis. May be different.

  In the caster for a handcart according to the present invention, the shape of the inner surface of the portion of the cylindrical portion into which the caster shaft is inserted in the cross section orthogonal to the caster axis is the outer peripheral surface of the caster shaft in the cross section orthogonal to the caster axis The shape may be different and non-similar.

  In the caster for a handcart according to the present invention, the shape of the outer peripheral surface of the caster shaft in a cross section orthogonal to the caster axis is non-circular, and the caster shaft of the cylindrical portion in the cross section orthogonal to the caster axis is inserted The shape of the inner surface of the portion to be processed may be non-circular.

  In the caster for a handcart according to the present invention, the shape of the outer peripheral surface of the caster shaft in a cross section orthogonal to the caster axis has a shape formed by connecting an odd number of arcs of the same shape, and the curvature of each arc A radius may be equal to the distance to the top part which faces the said circular arc among the top parts where two circular arcs were connected.

  In the caster for a handcart according to the present invention, when the number of the circular arcs is n, a portion of the cylindrical portion that comes into contact with the caster shaft has one virtual positive ( It may include (n + 1) straight line portions located on each side of the (n + 1) square.

  In the caster for a handcart according to the present invention, in the cross section orthogonal to the caster axis, the outer peripheral surface of the caster shaft has a shape formed by connecting three identical arcs, and The portion that comes into contact with the caster axis may include four straight portions located on each side of one virtual square.

  A baby carriage according to the present invention includes a caster for a handcart having any one of the above characteristics, and a baby carriage main body to which the caster for the handcart is attached.

  According to the present invention, it is possible to improve the straight traveling performance of the handcart.

It is a figure for demonstrating one embodiment of this invention, Comprising: The perspective view which shows a baby carriage. The side view which shows the baby carriage of FIG. The perspective view which shows the caster in one Embodiment. The longitudinal cross-sectional view of the caster shown by FIG. The exploded view of the caster shown by FIG. The schematic sectional drawing which shows the cross section of the caster axis | shaft and cylinder member which followed the line VIA-VIA shown in FIG. FIG. 6B is a schematic cross-sectional view showing a state in which the rotating body is rotated with respect to the caster shaft from the state shown in FIG. 6A. FIG. 6B is a schematic cross-sectional view showing a state where the rotating body is further rotated with respect to the caster shaft from the state shown in FIG. 6B. FIG. 6B is a schematic cross-sectional view showing a state where the rotating body is further rotated with respect to the caster shaft from the state shown in FIG. 6B. It is a figure corresponding to Drawing 6A, and is a schematic sectional view for explaining the modification of a caster. FIG. 7B is a schematic cross-sectional view showing a state in which the rotating body is further rotated around the caster shaft from the state shown in FIG. 7A. The schematic sectional drawing which shows the state which the rotary body further rotated centering on the caster axis | shaft from the state shown by FIG. 7B. 7C is a schematic cross-sectional view showing a state in which the rotating body is further rotated around the caster shaft from the state shown in FIG. 7C. FIG. 7D is a schematic cross-sectional view showing a state in which the rotating body is further rotated around the caster shaft from the state shown in FIG. 7D.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIGS. 1-6D is a figure for demonstrating one Embodiment of the baby carriage and caster by this invention. In addition, although the following description demonstrates using the example which applied the caster for handcarts by this invention to the baby carriage, the object to which the caster for handcarts is applied is not limited to the baby carriage. The caster according to the present invention can be widely applied to any vehicle that is pushed and operated by the operator's hand. For example, other examples of the wheelbarrow include a transport cart such as a shopping cart and a pet carry for accommodating and carrying a pet.

  1 and 2 show the overall configuration of the baby carriage 1. A baby carriage 1 shown in FIGS. 1 and 2 includes a baby carriage main body 2 and casters 3 attached to the baby carriage main body 2. Of these, the baby carriage body 2 includes a frame portion 10 having a pair of front legs 11 and a pair of rear legs 12, and a handle 20 that is swingably connected to the frame portion 10.

  A caster 3 which will be described in detail later is attached to the lower ends of the pair of front legs 11. The caster 3 can rotatably hold the wheel 80 about the rotation axis Lb and can rotate the wheel 80 about the caster axis La extending in a direction intersecting the rotation axis Lb. On the other hand, a wheel holder 4 is attached to the lower ends of the pair of rear legs 12. The wheel holding body 4 holds the wheel 80 rotatably while keeping the direction of the wheel 80 constant.

  In the baby carriage 1, the handle 3 is configured to be fixed at a back pushing position indicated by a two-dot chain line in FIG. 2 and a facing pushing position indicated by a solid line in FIG. 2. In the back pushing position, the handle 3 is inclined with respect to the vertical axis so that the upper part of the handle 3 is located rearward in a side view. In this case, the operator (guardian) grips the handle 3 from the rear leg 12 side which is the back of the infant. Then, the operator causes the baby carriage 1 to travel so that the infant faces forward in the traveling direction (the state shown in FIG. 1 and the state indicated by the two-dot chain line in FIG. 2). On the other hand, in the face-to-face pressing position, the handle 3 is inclined with respect to the vertical axis so that the upper portion of the handle 3 is positioned forward in a side view. In this case, the operator grips the handle 3 from the front leg 11 side facing the infant. Then, the operator causes the baby carriage 1 to travel such that the rear leg 12 side of the baby carriage 1 is in front of the traveling direction (state indicated by a solid line in FIG. 2).

  In the baby carriage 1 shown in FIG. 1, the wheel holding body 4 attached to the rear leg 12 may also be configured as a so-called caster so that the direction of the wheel 80 can be changed. In such a stroller 1, with respect to the casters attached to the legs located forward in the movement direction of the front legs 11 and the rear legs 12, it is possible to rotate the wheels and the wheel holders around the caster axis. From the viewpoint of maneuverability of the stroller 1, it is preferable that the casters attached to the legs positioned rearward in the moving direction be restricted from rotation of the wheels and the wheel holding body around the caster axis.

  A configuration in which the handle 20 is swingable with respect to the frame member 20 and a configuration in which the rotation of the wheel and the wheel holding body about the caster axis is automatically restricted according to the position of the handle 20 are known. For example, the configuration disclosed in JP2008-254688A can be adopted. Therefore, further detailed description is omitted in this specification.

  In the present embodiment, the baby carriage 1 is configured to be foldable so as to be widely used. As a configuration that allows the baby carriage 1 to be folded, a known configuration, for example, the configuration disclosed in JP2008-254688A described above can be employed. Therefore, further detailed description is omitted in this specification.

  Next, the caster 3 attached to the front leg 11 of the baby carriage body 2 will be described mainly with reference to FIGS. 3 to 5 are a perspective view, a side view, and an exploded view, respectively, showing a caster 3 according to an embodiment. In addition, casters 3 for front legs are respectively provided at the lower ends of the pair of front legs 11. The two front leg casters 3 are configured identically or symmetrically to each other.

  As shown in FIGS. 3 to 5, the caster 3 includes a fixed body 40 that is fixed to the leg of the baby carriage 1 and a rotating body 60 that can rotate with respect to the fixed body 40. The fixed body 40 has a caster shaft 51 protruding downward. The rotating body 60 is supported so as to be rotatable with respect to the caster shaft 51 around a caster axis La extending in the axial direction of the caster shaft 51. The rotating body 60 rotatably holds the wheel 80 via the axle 85. The wheel 80 rotates with respect to the rotating body 60 around a rotation axis Lb that coincides with the axial direction of the axle 85.

  As shown in FIG. 4, the rotation axis Lb is substantially along the horizontal direction, and the caster axis La is substantially orthogonal to the ground contact surface (road surface) of the baby carriage 1. The rotation axis Lb is spaced apart from the caster axis La in the horizontal direction. For this reason, by adjusting the direction of the propulsive force applied from the operator to the baby carriage 1, the rotating body 60 rotates with respect to the fixed body 40, and the baby carriage 1 can be turned.

  Hereinafter, each component of the caster 3 will be described in detail.

  As described above, the fixed body 40 is fixed to the leg of the baby carriage main body 2 and supports the rotating body 60 in a rotatable manner. In the present embodiment, the fixed body 40 includes a fixed body main body 41 fixed to the leg of the baby carriage 1 and the above-described caster shaft 51 extending downward from the fixed body main body 41. The rotating body 60 includes a rotating holder 61 having a head 61a inserted into the fixed body 41 from below, a cylindrical member 71 that is accommodated in the rotating holder 61 and is slidable with respect to the caster shaft 51, A rotating holder 61 and a wheel holder 62 disposed below the cylindrical member 71.

  As shown in FIG. 5, the fixed body 41 is composed of a shaft-like member extending along a partially curved path, and the legs 11 are inserted into the leg receiving recesses 42 opened upward. Thus, the fixed body main body 41 is held by the legs 11.

  In addition, a rotating body housing recess 43 is formed below the fixed body 41, and a cylindrical head 61 a formed in the rotating holder 61 is inserted into the rotating body housing recess 43. A through hole 61b is formed concentrically on the head 61a, and a cylindrical recess 61c is formed below the through hole 61b and continuously with the through hole 61b. A cylindrical member 71 is accommodated in the cylindrical recess 61c, and the caster shaft 51 is passed through the inner surface 71a and the through hole 61b of the cylindrical member 71 from below in FIG. A pin 45 having an axis extending in a direction perpendicular to the caster axis La passes through the tip end portion (upper end in the figure) of the caster shaft 51 and the fixed body main body 41, and the caster shaft 51 is connected via the pin 45. It is fixed to the fixed body main body 41.

  Here, the diameter of the through hole 61 b provided in the rotary holder 61 is larger than the diameter of the inner surface 71 a of the cylindrical member 71. Therefore, the caster shaft 51 penetrates the head 61 a with a play that does not contact the head 61 a of the rotary holder 61, and can slide on the inner surface 71 a of the cylindrical member 71. When the outer peripheral surface 51a of the caster shaft 51 and the inner surface 71a of the cylindrical member 71 slide with each other, the rotating body 60 can rotate with respect to the fixed body 40 about the caster axis La. In this respect, the cylindrical member 71 is preferably made of, for example, a cylindrical resin part having excellent self-lubricity so that the rotating body 60 can smoothly rotate with respect to the fixed body 40. In the present embodiment, the cylindrical member 71 is configured only from a portion into which the caster shaft 51 is inserted, but a portion into which the caster shaft 51 is not inserted may be provided in the cylindrical member 71.

  On the other hand, the base end portion (lower end portion in FIG. 4) of the caster shaft 51 is formed with a diameter-increased collar 52. The diameter-increased collar 52 has a diameter larger than the diameter of the inner surface 71a. It is held by the fixed body 40.

  Furthermore, a lock member 64 for restricting relative rotation of the rotating body 60 with respect to the fixed body 40 is attached to the rotating holder 61. The lock member 64 is swingably held via a pin 65 at a portion of the rotary holder 61 that protrudes in the horizontal direction from the other portion. The lock member 64 has a convex portion 64a that can be selectively inserted into the concave portion 44 of the fixed body 40 shown in FIG. By operating the lock member 64 to accommodate the convex portion 64 a of the lock member 64 in the concave portion 44 of the fixed body 40, the rotation of the rotating body 60 relative to the fixed body 40 can be restricted.

  A wheel holder 62 is supported on the rotation holder 61 via a pin 63, and a wheel 80 is held on the wheel holder 62 via an axle 85 so as to be rotatable about the rotation axis Lb. In the present embodiment, a hole 62a is formed in the wheel holder 62, and an axle 85 is inserted into the hole 62a.

  In addition, a cushion material 66 is disposed between the rotary holder 61 and the wheel holder 62 that are spaced apart from the pin 63. The cushion material 66 is elastically deformed by relative swinging of the rotating body 60 around the pin 63 with respect to the wheel holder 62, and exhibits a suspension function that absorbs an impact from the ground contact surface. According to the cushion material 66, a comfortable riding comfort can be provided to an infant riding on the baby carriage 1.

  By the way, as described in the background art section, when the rotator 60 is affected by unevenness or a step on the ground surface, there is a possibility that the wobble phenomenon in which the rotator 60 slightly vibrates with respect to the fixed body 40 may occur. . The force transmitted from the unevenness on the ground surface to the wheel 80 is transmitted to the rotating body 60, and then transmitted from the cylindrical member 71 of the rotating body 60 to the caster shaft 51 and received by the caster shaft 51. Therefore, when the rotating body 60 resonates due to the force transmitted to the wheel 80 from the unevenness on the ground surface and the wobble phenomenon occurs, the distance r between the caster axis La and the rotation axis Lb is the resonance wavelength (natural wavelength). It is thought that there is a correlation. Therefore, the present inventor has focused on configuring the caster 3 so as to change the distance r between the caster axis La and the rotation axis Lb in a state where a wobble phenomenon may occur. According to such a form, even if the rotating body 60 resonates in a certain state and the wobble phenomenon occurs, the distance r between the rotation axis Lb and the caster axis La different from the state in which the rotating body 60 resonates. By changing to, the wobble phenomenon can be suppressed.

  Hereinafter, a method for changing the distance r between the caster axis line La and the rotation axis line Lb will be described with reference to FIGS. 6A to 6D. 6A is a schematic cross-sectional view showing an inner surface 71a of the cylindrical member 71 and an outer peripheral surface 51a of the caster shaft 51 in a cross section orthogonal to the caster axis La, and FIGS. 6B to 6D are cross sections orthogonal to the caster axis La. The shape of the inner surface 71a of the cylindrical member 71 and the outer peripheral surface 51a of the caster shaft 51 in each state is shown. In the following description, the cross section orthogonal to the caster axis line La shown in FIGS. 6A to 6D is simply referred to as a main cross section. As shown in FIGS. 6A to 6D, in the present embodiment, the caster 3 includes the caster axis line La according to the angles θ <b> 1 to θ <b> 3 with respect to the fixed body 40 about the caster axis line La. The distance r between the rotation axis Lb can be changed. As described above, when the wobble phenomenon occurs, the rotating state of the rotating body 60 with respect to the fixed body 40 becomes unstable. Therefore, the wobble phenomenon can be effectively suppressed by changing the distance r between the caster axis line La and the rotation axis line Lb according to the rotation angles θ1 to θ3 of the rotating body 60 with respect to the fixed body 40.

  However, generally, a play is provided between the inner surface of the relatively rotating cylinder and the outer surface of the shaft so as to allow relative rotation and assembly. Therefore, “the distance r between the caster axis La and the rotation axis Lb can be changed according to the rotation angles θ1 to θ3 of the rotating body 60 with respect to the fixed body 40” in this specification means that the fixed body 40 of the rotating body 60 is fixed. This means that the range of values that can be taken by the distance r to be changed differs depending on the rotation angles θ1 to θ3 with respect to. In other words, when the rotating body 60 is rotated by a certain angle θ1 to θ3 with respect to the fixed body 40, the rotating body 60 is different from the fixed body 40 in the possible values of the distance r to be changed. It means that there is a value different from the value that the distance r to be changed can take when rotated by the angles θ1 to θ3.

  Specifically, the shape of the inner surface 71a of the cylindrical member 71 and the outer peripheral surface 51a of the caster shaft 51 are changed so that the distance r to be changed changes according to the rotation angles θ1 to θ3 of the rotating body 60 with respect to the fixed body 40. The shape is determined. Conventionally, the shape of the inner surface 71a in the main cross section and the shape of the outer peripheral surface 51a in the main cross section are circular, and therefore have the same or similar shape. On the other hand, in the present embodiment, the shape of the inner surface 71a in the main section and the shape of the outer peripheral surface 51a in the main section are non-circular and different from each other and are not similar. According to such a form, by appropriately designing the shape of the inner surface 71a of the cylindrical member 71 and the shape of the outer peripheral surface 51a of the caster shaft 51, the rotation body 60 can be rotated according to the rotation angles θ1 to θ3 with respect to the fixed body 40. Thus, the distance r to be changed can be changed. For this reason, it is not necessary to provide a separate mechanism or device in the caster 3 in order to change the distance r to be changed according to the rotation angles θ1 to θ3. Therefore, according to such a form, it is possible to effectively suppress the wobble phenomenon while avoiding the complexity of the structure and the increase in weight.

  As a specific shape, the shape of the outer peripheral surface 51a of the caster shaft 51 in the main cross section is a roulau n-gon, and the shape of the inner surface 71a of the cylindrical member 71 in the main cross-section is a positive (n + 1) square with chamfered corners. Consists of. However, n is an odd number. In the illustrated example, the shape of the inner surface 71a of the cylindrical member 71 in the main cross section is a square with chamfered corners, and the shape of the outer peripheral surface 51a of the caster shaft 51 in the main cross section is a Rouleau triangle.

  First, the shape of the inner surface 71a of the cylindrical member 71 will be described. As shown in FIG. 6A, the inner surface 71a of the cylindrical member 71 has four straight portions 74a to 74d located on each side of one virtual square X and two adjacent straight portions 74a to 74a in the main cross section. and corners 75a to 75d extending between d. Each linear part 74a-d comprises the part 73 which comes in contact with the caster axis | shaft 51 among the inner surfaces 71a of the cylindrical member 71, and each corner part 75a-d is the caster axis | shaft 51 among the inner surfaces 71a of the cylindrical member 71. The part which does not touch is constituted.

  In the present embodiment, the inner surface 71a of the cylindrical member 71, particularly the portion 73 that comes into contact with the caster shaft 51, is arranged four times symmetrically about the caster axis La. Therefore, the four linear portions 74a to 74d are configured congruently, and the corners 75a to 75d are also configured congruently. According to such a form, the symmetry of the inner surface 71a of the cylindrical member 71 contributes to changing the distance r between the caster axis La and the rotation axis Lb with good balance. As a result, there is a merit in providing a comfortable ride for the infant riding in the baby carriage 1.

  Each corner part 75a-d of this Embodiment is connected to the edge part of two adjacent linear parts 74a-d, and has a circular arc shape. The corners 75a to 75d may not necessarily be provided on the inner surface 71a of the cylindrical member 71. When the corner portions 75a to 75d are not provided, the straight portions 74a to 74d are overlapped with corresponding sides of one virtual square X, and the portion 73 that comes into contact with the caster shaft 51 of the cylindrical member 71 has a square shape. It has.

  Further, as shown in FIG. 6A, a straight line L1 connecting the midpoints of the two opposing linear portions 74a and 74c and a straight line L2 connecting the midpoints of the two other opposing linear portions 74b and 74d, Let the intersection be c1. This point c1 is the center of the inner surface 71a of the cylindrical member 71. Since the distance between the center c1 of the cylindrical member 71 and the rotation axis Lb is constant, the distance r between the caster axis La and the rotation axis Lb is evaluated by evaluating the change in the relative position between the center c1 and the rotation axis Lb. Can be evaluated.

  In particular, when the shape of the outer peripheral surface 51a of the caster shaft 51 in the main cross section is a Rouleau polygon, in order to prevent the corners 75a to 75d from coming into contact with the caster shaft 51, the center c1 and each corner The distance between 75a to 75d should be longer than the distance between the center c1 and each straight line 74a to 74d.

  Next, the shape of the outer peripheral surface 51a of the caster shaft 51 will be described. As described above, the outer peripheral surface 51a of the caster shaft 51 has a Rouleau polygonal shape in the main cross section. The Reuleaux polygon (n-gon) has a shape formed by connecting an odd number (n) of circular arcs 53a to 53c having the same shape, and apexes 54a to 54c are specified by adjacent circular arcs of the circular arcs 53a to 53c. The In the Rouleau polygon, the radius of curvature R of each arc 53a-c is equal to the distance to the tops 54a-c facing the arcs 53a-c. In the example shown in FIGS. 6A to 6D, the shape of the outer peripheral surface 51 a of the caster shaft 51 in the main cross section is a Rouleau triangle formed by connecting three identical arcs 53 a to 53 c.

  When the shape of the outer peripheral surface 51a of the caster shaft 51 in the main cross section is a Rouleau polygon, the caster axis line La passes through a position that is the center of a circle passing through each of the top portions 54a to 54c. In other words, the caster axis line La passes through a position where the distances from the top portions 54a to 54c are equal.

  Next, the operation of changing the distance r between the caster axis La and the rotation axis Lb according to the rotation angles θ1 to θ3 of the rotating body 60 with respect to the fixed body 40 will be described with reference to FIGS. 6A to 6D. 6A to 6D, the rotation angle of the rotating body 60 with respect to the fixed body 40 is illustrated as being shifted by 20 ° as an example. As a premise, as described above, in the main cross section, the portion 73 that comes into contact with the caster shaft 51 is composed of four straight portions 74a to 74d that are respectively located on each side of one virtual square X. It can be considered that the outer peripheral surface 51a of the caster shaft 51 made of the triangle is accommodated in the inner surface 71a of the cylindrical member 71 made of the virtual square X. Further, in the following description, for the sake of simplification of explanation, it is assumed that the outer peripheral surface 51a of the caster shaft 51 made of a Reuleaux triangle is inscribed in the inner surface 71a of the cylindrical member 71 made of a square in the main cross section. explain. However, even if play is provided between them, it is naturally possible to perform the same function. Further, in the caster 3, the rotary body 60 rotates relative to the fixed body 40. In FIGS. 6A to 6D, for ease of understanding, the position of the rotary body 60 is shown as a reference. Therefore, in FIGS. 6A to 6D, the fixed body 40 rotates relative to the rotating body 60.

  As shown in FIGS. 6A to 6D, when the outer peripheral surface 51 a of the caster shaft 51 made of a Reuleaux triangle rotates relative to the inner surface 71 a of a cylindrical member 71 made of an inscribed square, the center of the caster shaft 51 The position of the caster axis line La that passes through varies according to the angles θ1 to θ3 at which the fixed body 40 rotates relative to the rotating body 60. Therefore, the position of the caster axis line La with respect to the center c1 of the inner surface 71a of the cylindrical member 71 changes continuously according to the rotation angles θ1 to θ3 of the rotating body 60 with respect to the fixed body 40. The distance between the center c1 of the inner surface 71a of the cylindrical member 71 and the rotation axis Lb is constant. Therefore, according to the caster 3, the distance r between the caster axis La and the rotation axis Lb changes continuously according to the rotation angles θ1 to θ3 of the rotating body 60 with respect to the fixed body 40.

  Specifically, in the state shown in FIG. 6A, the first to third apexes 54a-c of the Reuleaux triangle are in contact with the corresponding first, second, fourth linear portions 74a, 74b, 74d on the square, respectively. Yes. In addition, an arc 53a facing the first top portion 54a is in contact with the third linear portion 74c. From the state shown in FIG. 6A, when the rotating body 60 is rotated by the first angle θ1 (20 ° in the illustrated example) with respect to the fixed body 40, the position where the first apex portion 54a contacts the first linear portion 74a is on the paper surface. The position where the third top portion 54c comes into contact with the fourth linear portion 74d is shifted to the upper side in the drawing. Then, the arc 53a that faces the first top portion 54a contacts the third linear portion 74c, and the arc 53c that faces the third top portion 54c contacts the second linear portion 74b. The position of the caster axis line La passing through the center of the caster shaft 51 also changes in accordance with the change in the contact position of the ruler triangle. Accordingly, the distance r between the caster axis La and the rotation axis Lb when the rotary body 60 rotates by the first angle θ1 with respect to the fixed body 40 is the same as the caster axis La before the relative rotation shown in FIG. It is different from the distance r between the axis Lb.

  Further, when the rotating body 60 further rotates with respect to the fixed body 40 from the state shown in FIG. 6B and rotates by a second angle θ2 (40 ° in the illustrated example) in total from the state shown in FIG. 6A, the third top portion 54c. The position in contact with the fourth straight line portion 74d is further shifted upward in the drawing, and the second top portion 54b is in contact with the third straight line portion 74c. Then, the arc 53b that faces the second top portion 54b contacts the first straight portion 74a, and the arc 53c that faces the third top portion 54c contacts the second straight portion 74b. Therefore, the position where the inner surface 71a of the cylindrical member 71 can contact the outer peripheral surface 51a of the caster shaft 51 when the rotating body 60 rotates by the second angle θ2 with respect to the fixed body 40 is the position where the rotating body 60 contacts the fixed body 40. On the other hand, it differs from the position where the inner surface 71a of the cylindrical member 71 can come into contact with the outer peripheral surface 51a of the caster shaft 51 when rotated by the first angle θ1. Further, the position of the caster axis line La passing through the center of the caster shaft 51 further changes in accordance with the change in the contact position of the ruler triangle. Therefore, the distance r between the caster axis La and the rotation axis Lb when the rotating body 60 rotates with respect to the fixed body 40 by the second angle θ2 is the first angle θ1 with respect to the fixed body 40. This is different from the distance r between the caster axis line La and the rotation axis line Lb when rotated only by the distance.

  Furthermore, when the rotating body 60 further rotates with respect to the fixed body 40 from the state shown in FIG. 6C and rotates a total of the third angle θ3 (60 ° in the illustrated example) from the state shown in FIG. The three top portions 54a to 54c are in contact with the second to fourth straight portions 74b to 74d, respectively, and the arc 53b facing the second top portion 54b is in contact with the first straight portion 74a. Therefore, the position where the inner surface 71a of the cylindrical member 71 can contact the outer peripheral surface 51a of the caster shaft 51 when the rotating body 60 rotates by the third angle θ3 with respect to the fixed body 40 is the position where the rotating body 60 contacts the fixed body 40. On the other hand, the position is different from the position where the inner surface 71a of the cylindrical member 71 can contact the outer peripheral surface 51a of the caster shaft 51 when rotated by the first angle θ1 or the second angle θ2. Further, the position of the caster axis line La passing through the center of the caster shaft 51 further changes in accordance with the change in the contact position of the ruler triangle. Therefore, the distance r between the caster axis La and the rotation axis Lb when the rotating body 60 rotates with respect to the fixed body 40 by the third angle θ3 is the first angle θ1 with respect to the fixed body 40. Or, it is different from the distance r between the caster axis line La and the rotation axis line Lb when rotated by the second angle θ2.

  As described above, according to the present embodiment, one of the fixed body 40 and the rotating body 60 has the caster shaft 51 that defines the caster axis La, and the other of the fixed body 40 and the rotating body 60 is the caster shaft. 51 between the caster axis La and the rotation axis Lb when the rotary body 60 is rotated by a certain first angle θ1 with respect to the fixed body 40 about the caster axis La. The distance r is different from the distance r between the caster axis La and the rotation axis Lb when the rotary body 60 rotates about the caster axis La by a certain second angle θ2 with respect to the fixed body 40. That is, even if the rotating body 60 resonates in a certain state and the wobble phenomenon occurs, the position of the caster axis line La changes as the rotating body 60 rotates with respect to the fixed body 40. For this reason, as a result, the distance r between the rotation axis Lb and the caster axis La changes. By changing the distance r, the frequency causing the wobble phenomenon changes, and the wobble phenomenon can be suppressed. As a result, it is possible to suppress a decrease in straight traveling performance due to the wobble phenomenon, and to improve straight traveling performance.

  Further, according to the present embodiment, the inner surface 71a of the cylindrical member 71 is the outer periphery of the caster shaft 51 when the rotating body 60 rotates about the caster axis La by a certain first angle θ1 with respect to the fixed body 40. The position that can contact the surface 51a is that the inner surface 71a of the cylindrical member 71 is caster when the rotating body 60 rotates about the caster axis La by a second angle θ2 different from the first angle θ1 with respect to the fixed body 40. It differs from the position where it can contact the outer peripheral surface 51a of the shaft 51. According to such a form, the position of the outer peripheral surface 51a of the caster shaft 51 with which the inner surface 71a of the cylindrical member 71 contacts can be changed according to the rotation angles θ1 to θ3 of the rotating body 60 with respect to the fixed body 40. Thereby, it can suppress that the outer peripheral surface 51a of the caster axis | shaft 51 wears out unevenly.

  Further, according to the present embodiment, the shape of the outer peripheral surface 51a of the caster shaft 51 in the main cross section is a Rouleux n-gon, and the portion 73 that comes into contact with the caster shaft 51 of the cylindrical member 71 is one virtual (N + 1) linear portions 74a to 74d located on each side of the positive (n + 1) square. In this case, the distance r between the caster axis La and the rotation axis Lb can be continuously and smoothly changed according to the rotation angles θ1 to θ3 of the rotating body 60 with respect to the fixed body 40. As a result, it contributes to providing a comfortable ride for the infant riding in the baby carriage 1. In particular, according to the present embodiment, the shape of the outer peripheral surface 51a of the caster shaft 51 in the main cross section is a Rouleau triangle, and the portion 73 that comes into contact with the caster shaft 51 of the cylindrical member 71 is one imaginary. Four straight portions 74a to 74d located on each side of the square X are included. In this case, the change in the distance r between the caster axis La and the rotation axis Lb according to the rotation angles θ1 to θ3 of the rotating body 60 with respect to the fixed body 40 can be increased. Thereby, the rotating body 60 can be made more difficult to resonate, and the wobble phenomenon can be more effectively suppressed.

≪Modification≫
Note that various modifications can be made to the above-described embodiment. Hereinafter, an example of modification will be described with reference to the drawings. In the following description and the drawings used in the following description, the same reference numerals as those used for the corresponding parts in the above embodiment are used for the parts that can be configured in the same manner as in the above embodiment. A duplicate description is omitted.

  For example, in the above-described embodiment, as shown in FIG. 5, an example in which the cylindrical member 71 that slides with respect to the caster shaft 51 is configured as a separate component from the rotary holder 61 is shown. The configuration example is not limited to such an example. The cylindrical member 71 may be an integral part of the rotary holder 61.

  In the above-described embodiment, as shown in FIG. 4, the fixed body 40 has the caster shaft 51 that defines the caster axis line La, and the rotating body 60 has the cylindrical member 71 into which the caster shaft 51 is inserted. However, the present invention is not limited to such an example. The rotating body 60 may have a caster shaft that defines a caster axis La, and the fixed body 40 may have a cylindrical portion into which the caster shaft is inserted. In this case, the outer peripheral surface of the caster shaft slides with respect to the inner surface of the cylindrical portion of the fixed body, so that the rotating body 60 can rotate relative to the fixed body 40 about the caster axis Lb.

  In the above-described embodiment, as shown in FIGS. 6A to 6D, the shape of the outer peripheral surface 51 a of the caster shaft 51 in the main cross section is an example of a Rouleau triangle. However, the embodiment is limited to such an example. Not. 7A to 7E show other examples of the shape of the outer peripheral surface 51a of the caster shaft 51. FIG. 7A to 7E, the rotation angle of the rotating body 60 with respect to the fixed body 40 is illustrated as being shifted by 18 ° as an example. In the example shown in FIGS. 7A to 7E, the shape of the outer peripheral surface 51 a of the caster shaft 51 in the main cross section is a Roule pentagon, and the portion 73 that comes into contact with the caster shaft 51 of the cylindrical member 71 is one imaginary. Six straight portions 74a to 74f located on each side of the regular hexagon are included.

  In the state shown in FIG. 7A, the first and second top portions 54a, 54b and 54e of the Reuleaux polygons correspond to the corresponding first straight portion 74a, second straight portion 74b and sixth straight portion on a regular hexagon. 74f is in contact with each other. In addition, an arc 53a that faces the first top portion 54a, an arc 53b that faces the second top portion 54b, and an arc 53e that faces the fifth top portion 54e are a fourth straight portion 74d, a fifth straight portion 74e, and a third straight portion. 74c is in contact with each other. When the rotating body 60 rotates from the state shown in FIG. 7A by a first angle θ1 (18 ° in the illustrated example) with respect to the fixed body 40, as shown in FIG. 7B, the first top portion 54a becomes the first straight portion 74a. The position where the fifth top portion 54e contacts the sixth linear portion 74f is shifted to the upper left side in the drawing. The third top portion 54c and the fourth top portion 54d are in contact with the fourth straight portion 74d and the fifth straight portion 74e, respectively, the arc 53d facing the fourth top portion 54d is in contact with the second straight portion 74b, and the fifth top portion An arc 53e facing 54e contacts the third linear portion 74c.

  Further, when the rotating body 60 further rotates with respect to the fixed body 40 from the state shown in FIG. 7B and rotates by a second angle θ2 (36 ° in the illustrated example) in total from the state shown in FIG. As described above, the position at which the third top portion 54c contacts the fourth straight portion 74d is shifted to the right side in the drawing, and the position at which the fourth top portion 54d contacts the fifth straight portion 74e is shifted to the upper right side in the drawing. And the 2nd top part 54b contacts the 3rd straight part 74c, and the circular arc 53b which faces the 2nd top part 54b contacts the 6th straight part 74e. Further, the arc 53c facing the third top portion 54c contacts the first straight portion 74a, and the arc 53d facing the fourth top portion 54d contacts the second straight portion 74b. Therefore, the position where the inner surface 71a of the cylindrical member 71 can contact the outer peripheral surface 51a of the caster shaft 51 when the rotating body 60 rotates by the second angle θ2 with respect to the fixed body 40 is the position where the rotating body 60 contacts the fixed body 40. On the other hand, it differs from the position where the inner surface 71a of the cylindrical member 71 can come into contact with the outer peripheral surface 51a of the caster shaft 51 when rotated by the first angle θ1. Further, as described above, the position of the caster axis line La passing through the center of the caster shaft 51 also changes in accordance with the change in the contact position of the Reuleaux polygon. Therefore, the distance r between the caster axis La and the rotation axis Lb when the rotating body 60 rotates with respect to the fixed body 40 by the second angle θ2 is the first angle θ1 with respect to the fixed body 40. This is different from the distance r between the caster axis line La and the rotation axis line Lb when rotated only by the distance.

  Similarly, when the rotating body 60 further rotates with respect to the fixed body 40 from the state shown in FIG. 7C and rotates by a third angle θ3 (54 ° in the illustrated example) in total from the state shown in FIG. The state shown in FIG. 7D is obtained. The position where the inner surface 71a of the cylindrical member 71 can come into contact with the outer peripheral surface 51a of the caster shaft 51 when the rotating body 60 is rotated by the third angle θ3 with respect to the fixed body 40 is the position where the rotating body 60 is relative to the fixed body 40 This is different from the position where the inner surface 71a of the cylindrical member 71 can contact the outer peripheral surface 51a of the caster shaft 51 when rotated by the first angle θ1 or the second angle θ2. Further, the distance r between the caster axis line La and the rotation axis line Lb when the rotating body 60 rotates by the third angle θ3 with respect to the fixed body 40 is the first angle θ1 with respect to the fixed body 40. Or, it is different from the distance r between the caster axis line La and the rotation axis line Lb when rotated by the second angle θ2.

  Further, when the rotating body 60 further rotates with respect to the fixed body 40 from the state illustrated in FIG. 7D and rotates by a fourth angle θ4 (72 ° in the illustrated example) in total from the state illustrated in FIG. It becomes a state. The position where the inner surface 71a of the cylindrical member 71 can come into contact with the outer peripheral surface 51a of the caster shaft 51 when the rotating body 60 is rotated by the fourth angle θ4 with respect to the fixed body 40 is such that the rotating body 60 is in relation to the fixed body 40. This is different from the position where the inner surface 71a of the cylindrical member 71 can contact the outer peripheral surface 51a of the caster shaft 51 when rotated by the first angle θ1, the second angle θ2, or the third angle θ3. Further, the distance r between the caster axis La and the rotation axis Lb when the rotating body 60 is rotated by the fourth angle θ4 with respect to the fixed body 40 is the first angle θ1 with respect to the fixed body 40. This is different from the distance r between the caster axis La and the rotation axis Lb when rotated by the second angle θ2 or the third angle θ3.

  From the above, even in the configurations shown in FIGS. 7A to 7E, it is possible to suppress a decrease in straight traveling performance due to the wobble phenomenon, and to improve straight traveling performance, as in the above-described embodiments.

DESCRIPTION OF SYMBOLS 1 Stroller 2 Stroller body 3 Caster 11 Front leg 12 Rear leg 40 Fixed body 51 Caster shaft 51a Outer peripheral surface 53a-c Arc 54a-c Top part
60 Rotating body 71 Tube member (tube portion)
71a Inner surface 73 A portion 74 that comes into contact with the caster shaft Linear portion 80 Wheel La Caster axis La
Lb rotation axis r distance X between caster axis and rotation axis X virtual square

Claims (8)

A fixed body fixed to the leg of the wheelbarrow;
A rotating body rotatably held by the fixed body about a caster axis;
A wheel rotatably held by the rotating body around a rotation axis;
With
One of the fixed body and the rotating body has a caster shaft that defines the caster axis,
The other of the fixed body and the rotating body has a cylindrical portion into which the caster shaft is inserted,
The distance between the caster axis and the rotation axis when the rotating body is rotated by a certain first angle with respect to the fixed body about the caster axis is such that the rotating body is centered on the caster axis. A caster for a handcart that is different from a distance between the caster axis and the rotation axis when rotated by a second angle different from the first angle with respect to the fixed body.   The position at which the inner surface of the cylindrical portion can contact the outer peripheral surface of the caster shaft when the rotating body is rotated by the first angle with respect to the fixed body about the caster axis is as follows. 2. The position according to claim 1, which is different from a position at which an inner surface of the cylindrical portion can contact an outer peripheral surface of the caster shaft when rotated by the second angle with respect to the fixed body about a caster axis. Caster for wheelbarrow.   The shape of the inner surface of the portion of the cylindrical portion into which the caster shaft is inserted in the cross section orthogonal to the caster axis is different and non-similar to the shape of the outer peripheral surface of the caster shaft in the cross section orthogonal to the caster axis. A caster for a handcart according to claim 1 or 2. The shape of the outer peripheral surface of the caster shaft in a cross section perpendicular to the caster axis is non-circular,
The caster for a handcart according to any one of claims 1 to 3, wherein a shape of an inner surface of a portion of the cylindrical portion into which the caster shaft is inserted in a cross section perpendicular to the caster axis is non-circular.   The shape of the outer peripheral surface of the caster shaft in a cross section orthogonal to the caster axis line has a shape formed by connecting an odd number of arcs of the same shape, and the curvature radius of each arc is a connection of two arcs. The caster for a handcart according to any one of claims 1 to 5, wherein the caster is equal to a distance to a top portion of the top portion facing the arc. If the number of arcs is n,
The portion of the cylindrical portion that comes into contact with the caster axis includes (n + 1) straight line portions located on each side of one virtual positive (n + 1) square in a cross section orthogonal to the caster axis. A caster for a handcart according to claim 5. In the cross section perpendicular to the caster axis, the shape of the outer peripheral surface of the caster shaft has a shape formed by connecting three identical arcs, and the portion of the cylindrical portion that comes into contact with the caster shaft is Including four straight portions located on each side of one virtual square,
A caster for a handcart according to claim 6. A caster for a handcart according to any one of claims 1 to 7,
A baby carriage comprising: a baby carriage main body to which a wheelbarrow caster is attached.

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