Suspension device and running gear

Abstract

The present application provides a kind of to realize the miniaturization of the suspension device using swing arm bogie mechanism technology.A kind of suspension device, with drive wheel (24);First driven wheel (26), relative to drive wheel (24) is arranged in front-rear direction on one side;Second driven wheel (28), relative to drive wheel (24) is arranged in front-rear direction on the other side;Bogie link member (38), support drive wheel (24) and first driven wheel (26) and can be oscillated with first swing axis (44) as center;And swing arm link member (40), support second driven wheel (28) and bogie link member (38) and can be oscillated with second swing axis (50) as center, when observing from left and right direction, first swing axis (44) and the rotation axis (70) of drive wheel (24) are not on the same plumb line, first swing axis is located more than rotation axis in plumb direction and the inner side of the profile of drive wheel.

Description

[0001] This application claims priority based on Japanese Patent Application No. 2021-170365 filed on October 18, 2021. The entire contents of the Japanese application are incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to a suspension device used in a traveling device. BACKGROUND

[0003] Patent Document 1 discloses a suspension device using a swing arm bogie mechanism that has a bogie link member that supports a drive wheel and a first driven wheel, and a swing arm link member that supports a second driven wheel and the bogie link member.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2020-19348

[0005] The present inventors recognized that there is room for improvement in the related art in terms of achieving miniaturization of a suspension device using a swing arm bogie mechanism. SUMMARY

[0006] One object of the present application is to provide a technology that achieves miniaturization of a suspension device using a swing arm bogie mechanism.

[0007] The suspension device of the present application has a drive wheel, a first driven wheel disposed on one side in a front-rear direction with respect to the drive wheel, a second driven wheel disposed on the other side in the front-rear direction with respect to the drive wheel, a bogie link member that supports the drive wheel and the first driven wheel and is swingable about a first swing axis, and a swing arm link member that supports the second driven wheel and the bogie link member and is swingable about a second swing axis, the first swing axis and a rotation axis of the drive wheel not being on the same vertical line when viewed in a left-right direction, the first swing axis being located more upward in the vertical direction than the rotation axis and inside an outline of the drive wheel.

[0008] EFFECT OF THE INVENTION

[0009] According to the present application, it is possible to achieve miniaturization of a suspension device using a swing arm bogie mechanism. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 is a side view of a traveling device of the first embodiment.

[0011] Figure 2 is a perspective view of a suspension device of the first embodiment.

[0012] Figure 3This is a side view of a portion of the suspension device of the first embodiment, viewed from the inside in the left-right direction.

[0013] Figure 4 It is a schematic representation Figure 3 A diagram of the BB section.

[0014] Figure 5 This is a side view of the walking device according to the second embodiment.

[0015] Figure 6 It means Figure 5 A partial cross-sectional side view of a portion of the document.

[0016] Figure 7 It means Figure 5 A partial cross-sectional side view of a portion of the document.

[0017] Figure 8 Diagram (A) is the first explanatory diagram related to the movement of the auxiliary wheel. Figure 8 Figure B is its second explanatory diagram. Figure 8 The middle (C) diagram is its third explanatory diagram.

[0018] In the diagram: 10-Traveling device, 12-Main body of the device, 14-Suspension device, 24-Drive wheel, 26-First driven wheel, 28-Second driven wheel, 38-Bogie linkage assembly, 40-Rocker arm linkage assembly, 44-First swing shaft, 50-Second swing shaft, 56-Traveling surface, 60-Rotating shaft, 62-Rotating support mechanism, 82-Lifting support mechanism, 92-Auxiliary wheel. Detailed Implementation

[0019] The embodiments will now be described. Identical components are labeled with the same symbols, and repeated descriptions are omitted. In the accompanying drawings, components are appropriately omitted, enlarged, or reduced for ease of explanation. Refer to the orientation of the symbols in the drawings.

[0020] (First Embodiment)

[0021] refer to Figure 1 The walking device 10 is an unmanned transport vehicle such as an AGV (Automated Guided Vehicle) or AMR (Autonomous Mobile Robot). The walking device 10 includes a main body 12 and a suspension device 14 mounted on the main body 12. The main body 12 has a loading section 16 for carrying the items to be transported. The main body 12 is equipped with a computer-based control unit (not shown) for controlling the movement of the walking device 10, and a battery (not shown) that supplies power to the control unit and the drive unit 20 (described later).

[0022] refer to Figure 2 , Figure 3 and Figure 4 . Figure 3 Again from Figure 2 Arrow A points in a diagram showing a portion of the suspension assembly 14. In this specification, the positional relationships between the components are described using the front-to-back direction (X), the left-to-right direction (Y), and the vertical direction (Z). The front-to-back direction (X) is a horizontal direction orthogonal to the rotation axis 70 (imaginary axis) that serves as the center of rotation for the drive wheel 24 (described later). The left-to-right direction (Y) is a horizontal direction orthogonal to the front-to-back direction (X). The vertical direction (Z) is the vertical direction.

[0023] The suspension device 14 includes a pair of wheel sets 18 disposed on the left and right sides, a drive device 20 for driving the drive wheels 24 of the wheel sets 18, and wheel seats (wheel set supports) 22 that support the pair of wheel sets 18 respectively.

[0024] The wheel assembly 18 consists of multiple wheels. The multiple wheels constituting the wheel assembly 18 include a drive wheel 24 and a wheel positioned relative to the drive wheel 24 on one side (front side) in the longitudinal direction X. Figure 3 The first driven wheel 26 on the left side and the other side (rear side) of the drive wheel 24 are arranged in the front-rear direction X. Figure 3 The second driven wheel 28 on the right side)

[0025] The drive wheel 24 is able to rotate by power transmitted from the drive unit 20. In this embodiment, the drive wheel 24 is a tire wheel, which includes a wheel 30 that rotates under the drive of the drive unit 20 and a tire 32 mounted on the wheel 30. The type of drive wheel 24 is not particularly limited, and it may also be an integral wheel or the like.

[0026] Power from the drive unit 20 is not transmitted to the driven wheels 26 and 28; the driven wheels 26 and 28 rotate in response to the rotation of the drive wheel 24. In this embodiment, the driven wheels 26 and 28 are integral wheels. The type of driven wheels 26 and 28 is not particularly limited; they can also be tire wheels, etc. In this embodiment, the first driven wheel 26 is the front wheel located at the front, and the second driven wheel 28 is the rear wheel located at the rear.

[0027] The drive device 20 of the present embodiment is a gear motor. The specific example of the drive device 20 is not particularly limited, and can be a motor or an engine, or the like. The drive device 20 has a housing 34 fixed to a bogie link member 38 (described later) by a bolt or the like. The housing 34 penetrates the bogie link member 38 in the left-right direction Y. The drive device 20 is disposed on the inner side in the left-right direction Y of the drive wheel 24. The drive device 20 has an output member 36 fixed to the wheel 30 of the drive wheel 24 by a bolt or the like and capable of outputting a rotational power. The power is directly transmitted from the output member 36 to the drive wheel 24 to rotate.

[0028] A pair of wheel seats 22 are disposed apart in the left-right direction Y. The wheel seat 22 has the bogie link member 38 that supports the drive wheel 24 and the first driven wheel 26, and a rocker link member 40 that supports the second driven wheel 28 and the bogie link member 38. Each of the link members 38, 40 of the wheel seat 22 is made of, for example, a metal such as stainless steel or aluminum.

[0029] The bogie link member 38 is a long member long in the front-rear direction X. One end portion (front end portion) of the bogie link member 38 in the front-rear direction X is connected to the first driven wheel 26, and the other end portion (rear end portion) on the opposite side in the front-rear direction X is connected to the drive wheel 24. As described above, the bogie link member 38 is connected to the drive wheel 24 via the drive device 20.

[0030] The bogie link member 38 is connected to the rocker link member 40 via a first support bearing 42, whereby the bogie link member 38 is capable of relative rotation about a first swing axis 44 to be able to swing. The first swing axis 44 is an imaginary axis that becomes the swing center of the bogie link member 38. The swing here means that, when viewed in the left-right direction Y, the mentioned link member (here, the bogie link member 38) rotates about the mentioned swing axis as the center.

[0031] The first support bearing 42 is, for example, a cross roller bearing. The first support bearing 42 has a first outer ring 42a, a first inner ring 42b, and a plurality of first rolling elements (not shown) that roll on the first outer ring 42a and the first inner ring 42b. The bogie link member 38 has a first accommodation recess 46 recessed in the left-right direction Y at a position on the intermediate portion thereof in the front-rear direction X, which is opposed to the rocker link member 40 in the left-right direction Y. The first support bearing 42 is accommodated in the first accommodation recess 46. The first outer ring 42a of the first support bearing 42 is fixed to the bogie link member 38 by a screw or the like, and the first inner ring 42b is fixed to the rocker link member 40 by a screw or the like. Thus, the first support bearing 42 swingably connects the bogie link member 38 to the rocker link member 40. The first swing axis 44 that becomes the swing center is provided on the axis of the first support bearing 42.

[0032] The rocker arm link member 40 is a long dimension member that is long in the front-rear direction X. One end portion (front end portion) of the rocker arm link member 40 in the front-rear direction X is connected to the bogie link member 38, and the other end portion (rear end portion) thereof on the opposite side in the front-rear direction X is connected to the second driven wheel 28.

[0033] The rocker arm link member 40 is connected to the device main body 12 via the second support bearing 48, whereby the rocker arm link member 40 is relatively rotatable about the second swing axis 50 so as to be swingable. The rocker arm link member 40 of the present embodiment is connected to the device main body 12 via the second support bearing 48 and a mounting member 52 for mounting to the device main body 12. The second swing axis 50 is an imaginary axis that becomes the swing center of the rocker arm link member 40.

[0034] The second support bearing 48 is, for example, a cross roller bearing. The second support bearing 48 has a second outer ring 48a, a second inner ring 48b, and a plurality of second rolling elements 48c that roll on the second outer ring 48a and the second inner ring 48b. The rocker arm link member 40 has a second accommodation recess 54 that is recessed in the left-right direction Y at a position on the middle portion thereof in the front-rear direction X and that opposes the mounting member 52 in the left-right direction Y. The second support bearing 48 is accommodated in the second accommodation recess 54. The second outer ring 48a of the second support bearing 48 is fixed to the rocker arm link member 40 by a screw or the like, and the second inner ring 48b is fixed to the mounting member 52 by a screw or the like. Thus, the second support bearing 48 swingably connects the rocker arm link member 40 to the device main body 12 via the mounting member 52. The second swing axis 50 that becomes the swing center is provided on the axis of the second support bearing 48.

[0035] The bogie link member 38 and the rocker arm link member 40 of the wheel seat 22 constitute a rocker bogie mechanism. The rocker bogie mechanism causes each of the link members 38, 40 to swing about the swing axes 44, 50 so as to follow the shape of the traveling surface 56 when traveling on uneven ground having concavities and convexities, undulations, or the like, thereby being able to maintain a state in which the three wheels (the drive wheel 24 and each of the driven wheels 26, 28) are in contact with the traveling surface 56. Thus, it is possible to prevent a situation in which any one of the three wheels is lifted from the traveling surface 56 from occurring, and high stability when traveling on uneven ground can be obtained. The principle of operation of this rocker bogie mechanism is known per se, and thus detailed description thereof is omitted here.

[0036] The suspension device 14 has a rotation support mechanism 62 that supports the driven wheels 26, 28 so as to be able to rotate about a rotation axis 60 extending in the vertical direction. The rotation axis 60 is an imaginary axis that becomes the center of rotation of the driven wheels 26, 28, and in the present embodiment, is a vertical axis. The suspension device 14 of the present embodiment has separate rotation support mechanisms 62 corresponding to the first driven wheel 26 and the second driven wheel 28. In the present embodiment, the rotation support mechanism 62 corresponding to the first driven wheel 26 and the rotation support mechanism 62 corresponding to the second driven wheel 28 have the same structure, and therefore, the structure of the former will be mainly described, and the description of the latter will be omitted.

[0037] The rotation support mechanism 62 connects the driven wheels 26, 28 to the wheel seat 22, and enables the driven wheels 26, 28 to rotate about the rotation axis 60. The first driven wheel 26 is connected to the bogie link member 38 of the wheel seat 22 via the rotation support mechanism 62. The second driven wheel 28 is connected to the swing arm link member 40 of the wheel seat 22 via the rotation support mechanism 62. In the present embodiment, the rotation support mechanism 62 and the driven wheels 26, 28 function as caster wheels. The rotation support mechanism 62 has a wheel support body 64 that supports the driven wheel 26 so as to be able to rotate about the axis thereof, and a rotation connection mechanism 66 that rotatably connects the wheel support body 64 to the wheel seat 22. The wheel support body 64 is configured using a fork or the like, for example. The rotation connection mechanism 66 of the present embodiment is configured by a swivel joint. The axis 29 of each driven wheel 26, 28 is disposed at a position offset from the rotation axis 60. Thereby, the intersection of the rotation axis 60 and the walking surface 56, and the contact points of the driven wheels 26, 28 and the walking surface 56 are offset, and thus, the caster trail can be ensured. Therefore, when the walking device 10 is running, the advancing direction of the walking device 10 can be easily made to coincide with the orientation of the driven wheels 26, 28, and thus, good advancing stability can be obtained.

[0038] REFERENCE Figure 3The positional relationship between the components when viewed from the left-right direction Y will be described below. The front-rear dimension from the rotation axis 70, which is the center of rotation of the drive wheel 24, to the first swing axis 44 is set as La. The front-rear dimension from the first swing axis 44 to the connection position of the first driven wheel 26 and the bogie link member 38 (in this embodiment, the rotation axis 60 of the first driven wheel 26) is set as Lb. The front-rear dimension from the connection position of the second driven wheel 28 and the rocker link member 40 (in this embodiment, the rotation axis 60 of the second driven wheel 28) to the second swing axis 50 is set as Lc. The front-rear dimension from the second swing axis 50 to the first swing axis 44 is set as Ld. The front-rear dimension from the second swing axis 50 to the connection position of the first driven wheel 26 and the bogie link member 38 is set as Le. In this embodiment, La=Ld, but they can be different. The front-rear dimension here refers to the dimension in the front-rear direction X.

[0039] The upward vertical reaction force acting on each wheel 24, 26, 28 from the traveling surface 56 is set as Fa, Fb1, Fb2. Fa is the vertical reaction force of the drive wheel 24, Fb1 is the vertical reaction force of the first driven wheel 26, and Fb2 is the vertical reaction force of the second driven wheel 28. It is known that, when a rocker bogie mechanism is used, the ratio of each vertical reaction force Fa, Fb1, Fb2 (hereinafter referred to as the reaction force ratio) can be controlled depending on the ratio of La:Lb and Lc:Ld (hereinafter referred to as the length ratio).

[0040] In the balance of the moment around the first swing axis 44 caused by the vertical reaction forces Fa, Fb1 acting on the bogie link member 38, Fa x La = Fb1 x Lb is obtained, which can be rewritten as La:Lb = Fb1:Fa... (A). Also, in the balance of the moment around the second swing axis 50 caused by the vertical reaction forces Fa, Fb1, Fb2 acting on the rocker link member 40, Fb2 x Lc = (Fa + Fb1) x Ld is obtained, which can be rewritten as Lc:Ld = (Fa + Fb1):Fb2... (B). Using the length ratios of La and the like described above and these equations (A) and (B), the reaction force ratio of the vertical reaction forces of each wheel 24, 26, 28 can be obtained.

[0041] For example, in this embodiment, La:Lb is set to 1:2, and Fb1:Fa becomes 1:2. Also, in this embodiment, Lc:Ld (=La) is set to 3:1 (as a result, Lc:Le = 1:1), and Fa + Fb1:Fb2 becomes 3:1. If they are combined, the reaction force ratio of Fa:Fb1:Fb2 = 2:1:1 can be obtained.

[0042] In the present embodiment, the reaction force ratio means that, when the swing arm bogie mechanism is in a balanced state, the vertical reaction forces Fb1, Fb2 acting on the driven wheels 26, 28 are smaller than the vertical reaction force Fa acting on the drive wheel 24. This means that, when the driven wheels 26, 28 in the advancing direction are to pass over a step present on the traveling surface 56, the link members 38, 40 can be caused to swing easily to raise the driven wheels 26, 28, compared with a case where the vertical reaction force Fa and the vertical reaction forces Fb1, Fb2 are the same. Further, the driven wheels 26, 28 can pass over the step present on the traveling surface 56 easily. Furthermore, by making the vertical reaction forces Fb1, Fb2 smaller than the vertical reaction force Fa, the traction of the drive wheel 24, from which power is transmitted from the drive device 20, can be improved, and the raising action of the driven wheels 26, 28, which follow the shape of the traveling surface 56, can be made light. Further, the running performance on uneven ground can be improved. The uneven ground here includes not only a portion having a concave-convex, a step, or the like, but also a portion that is wet and slippery.

[0043] Thus, when the swing arm bogie mechanism is used, La and the like are set to a prescribed length ratio in design, so that the vertical reaction force acts on each wheel 24, 26, 28 at a target reaction force ratio.

[0044] Here, the first swing axis 44 and the rotation axis 70 are not on the same plumb line. This means that the first swing axis 44 is located at a position deviated from the rotation axis 70 in the front-rear direction X. The first swing axis 44 of the present embodiment is located at a position more on the first driven wheel 26 side than the rotation axis 70. This becomes a necessary condition for realizing the length ratio related to La:Lb described above.

[0045] When passing over a step on the traveling surface, a large load is applied to the first support bearing 42, and in order to resist this large load, the first support bearing 42 is required to be large-sized. If the first swing axis 44 is disposed at a position more below the rotation axis 70 in the vertical direction (up-down direction Z), the first swing axis 44 and the first support bearing 42 are too close to the traveling surface 56, and thus the size of the first support bearing 42 can be limited. In order to prevent this, the first swing axis 44 is located at a position more above the rotation axis 70 in the vertical direction (up-down direction Z). Thus, the size of the first support bearing 42 is less likely to be limited by the traveling surface 56, and the size of the first support bearing 42 can be made large. Further, the durability required for the first support bearing 42 in order to resist the large load when passing over a step can be ensured easily.

[0046] The first swing axis 44 is located inside the outer surface of the drive wheel 24. That is, when viewed from the left-right direction Y, the first swing axis 44 is located further radially inward (on the side of the rotation axis 70) than the outer peripheral surface 24a of the drive wheel 24. Therefore, in the front-rear direction X, the first swing axis 44 is located further inward (on the side of the first driven wheel 26) than the end 24b of the drive wheel 24 on the side of the first driven wheel 26. Figure 3 Compared to the case where the position is on the left side of the paper, the distance La from the rotation axis 70 to the first swing axis 44 can be shortened. The shorter this distance La is, the shorter the distance Lb required to maintain the La:Lb length ratio can be. Furthermore, at the same time, by shortening these distances La and Lb, the distance Lc required to maintain the Lc:Ld ratio can also be shortened. Consequently, while maintaining the prescribed length ratio of La, the overall front-rear dimensions of the suspension device 14 can be miniaturized. Being able to maintain the prescribed length ratio of La means that, regarding the manner in which the reaction force acts on each wheel 24, 26, 28, the target reaction force ratio can be maintained.

[0047] Next, the effects of the suspension device 14 described above will be explained.

[0048] (A) In the suspension device 14, the drive wheel 24 and the first swing shaft 44 are positioned in the manner described above. Therefore, in the suspension device 14 using the rocker arm bogie mechanism, the front-to-rear dimensions of the suspension device 14 can be miniaturized. In achieving this, as described above, the specified length ratio of La, etc., can be maintained. Furthermore, as described above, the required durability of the first support bearing 42 when traversing steps can also be ensured.

[0049] (B) The suspension device 14 is equipped with a rotation support mechanism 62 that supports the driven wheels 26 and 28 so that they can rotate about the rotation axis 60. Therefore, when the suspension device 14 wants to change its direction of travel, the driven wheels 26 and 28 can rotate in accordance with the change, and the following performance when changing its direction of travel becomes good.

[0050] The rotating support mechanism 62 is provided separately for the first driven wheel 26 and the second driven wheel 28, respectively. Therefore, if the rotation direction of the left and right drive wheels 24 is reversed, it is possible to turn in place.

[0051] Furthermore, the first support bearing 42 connecting the bogie link assembly 38 and the rocker arm link assembly 40 is located offset relative to the rotation axis 70 in the longitudinal direction X towards the first driven wheel 26. Therefore, a part of the rocker arm link assembly 40 and a part of the bogie link assembly 38 overlap vertically between the first support bearing 42 and the rotation axis 70. Thus, compared to the case where the first support bearing 42 and the rotation axis 70 are located on the same vertical line, the overall longitudinal dimensions of the suspension assembly 14 can be reduced.

[0052] Next, other features of the suspension device 14 of the present embodiment will be described. In the present embodiment, the ratio of the outer diameter of the drive wheel 24 to one of the first driven wheel 26 and the second driven wheel 28 is 2: 1 or more. In the present embodiment, this condition is satisfied between the drive wheel 24 and the first driven wheel 26, and between the drive wheel 24 and the second driven wheel 28. The outer diameter here means the outer diameter in terms of radius. The outer diameter of the drive wheel 24 is denoted as R24, the outer diameter of the first driven wheel 26 is denoted as R26, and the outer diameter of the second driven wheel 28 is denoted as R28. R24:R26 is 2: 1 or more, and R24:R28 is 2: 1 or more.

[0053] The larger the outer diameters R26, R28 of the driven wheels 26, 28, the larger the front-rear dimension of the entire suspension device 14 becomes in order to maintain the prescribed length ratio of La and the like. For example, the larger the outer diameter R26 of the first driven wheel 26, the larger the front-rear dimension of the bogie link member 38 needs to be in order to avoid interference with the drive wheel 24, and the distance Lb needs to be lengthened. Consequently, in order to maintain the La:Lb ratio, the distance La also needs to be lengthened, and furthermore, in order to maintain the Lc:Ld ratio, the distance Lc also needs to be lengthened. As a result, the front-rear dimension of the entire suspension device 14 becomes large.

[0054] Also, the larger the outer diameter R28 of the second driven wheel 28, the larger the front-rear dimension of the swing arm link member 40 needs to be in order to avoid interference with the drive wheel 24, and the distance Lc needs to be lengthened. Consequently, in order to maintain the Lc:Ld ratio or the La:Lb ratio, the distances La (=Ld), Lb also need to be lengthened. As a result, the front-rear dimension of the entire suspension device 14 becomes large.

[0055] In this regard, by satisfying the condition related to the above-described ratio of the outer diameters, the front-rear dimension of the entire suspension device 14 can be made small in a state in which the prescribed length ratio of La and the like is maintained, as compared with a case in which the condition is not satisfied. Note that the upper limit of the ratio of the outer diameters of the driven wheels and the drive wheel 24 is not particularly limited, but can be, for example, 3 to 4: 1 or less.

[0056] (Second Embodiment)

[0057] Reference Figure 5 and Figure 6The traveling device 10 of the present embodiment differs from the first embodiment mainly in the structure around the first driven wheel 26. The structure around the second driven wheel 28 is the same as that of the first embodiment, and thus the description thereof is omitted here. When there is the driven wheel 26 on which the driving force of the driving device 20 is not transmitted on the swing arm bogie mechanism, it is difficult to pass over the step 80 present on the traveling surface 56 based on the driven wheel 26. Hereinafter, the point of ingenuity for making it easy to pass over the step 80 is described.

[0058] With reference to Figure 6 and Figure 7 The suspension device 14 has a lift support mechanism 82 that supports the first driven wheel 26 so as to be liftable. The lift support mechanism 82 connects the first driven wheel 26 to the wheel seat 22 in such a manner that the first driven wheel 26 is liftable with respect to the wheel seat 22. The lift support mechanism 82 has a wheel support body 64 that supports the first driven wheel 26 so as to be rotatable about the shaft center 29 of the first driven wheel 26, and a lift connecting mechanism 84 that connects the wheel support body 64 to the wheel seat 22 so as to be liftable.

[0059] The lift connecting mechanism 84 of the present embodiment has a linear motion bearing 86 that is installed to the wheel seat 22 (the bogie link member 38 in the present embodiment), and a shaft 88 that is installed to the wheel support body 64. The linear motion bearing 86 supports the shaft 88 so as to be linearly movable. The linear motion bearing 86 and the shaft 88 of the present embodiment constitute a ball spline. The shaft 88 that constitutes the ball spline is a spline shaft that has a plurality of splines. The linear motion bearing 86 that constitutes the ball spline has an outer tube 86a that is installed to the wheel seat 22, and a plurality of balls (not shown) that are disposed between the splines of the shaft 88 and the outer tube 86a. In the linear motion bearing 86, the balls that are not shown roll in the outer tube 86a and the shaft 88, thereby supporting the shaft 88 so as to be non-rotatable and linearly movable in the axial direction. With the above-described lift support mechanism 82, it is possible to support the first driven wheel 26 so as to be liftable in conjunction with the movement in the vertical direction Z of the wheel support body 64.

[0060] A shock absorbing member 90 such as a compression spring is disposed between the wheel seat 22 and the wheel support body 64. The load of the device main body 12 and the wheel seat 22 is transmitted to the wheel support body 64 and the first driven wheel 26 via the shock absorbing member 90. In the case where an upward shock load is input to the first driven wheel 26, the shock absorbing member 90 elastically deforms, thereby absorbing the shock load. Furthermore, it is possible to moderate the shock load transmitted to the device main body 12 of the traveling device 10.

[0061] The suspension device 14 is provided with an auxiliary wheel 92 that is positioned apart upward from the flat walking surface 56 when the first driven wheel 26 is in contact with the walking surface 56. The auxiliary wheel 92 is disposed inward in the left and right direction Y of the first driven wheel 26. The outer diameter of the auxiliary wheel 92 of the present embodiment is larger than the outer diameter of the first driven wheel 26. The auxiliary wheel 92 is supported by the wheel support body 64 so as to be rotatable about the shaft center 93 of the auxiliary wheel 92. The first driven wheel 26 and the auxiliary wheel 92 are supported so as to be integrally liftable by the lift support mechanism 82. The auxiliary wheel 92 protrudes toward the opposite side (in this case, the front side) of the front and rear direction X of the first driven wheel 26 from the second driven wheel 28 (also refer to Figure 5 ).

[0062] The rotation support mechanism 62 corresponding to the first driven wheel 26 supports the first driven wheel 26 and the auxiliary wheel 92 so as to be integrally rotatable about the rotation shaft 60. A part of this rotation support mechanism 62 also functions as the structure of the lift support mechanism 82. Specifically, the wheel support body 64 and the shaft 88 of the rotation support mechanism 62 described later also function as the structure of the lift support mechanism 82.

[0063] As explained in the first embodiment, the rotation support mechanism 62 corresponding to the first driven wheel 26 is provided with the wheel support body 64 that supports the first driven wheel 26 so as to be rotatable about the shaft center thereof and the rotation connecting mechanism 66 that rotatably connects the wheel support body 64 to the wheel seat 22.

[0064] The wheel support body 64 is provided with the first wheel support member 104 that supports the first driven wheel 26 and the second wheel support member 106 that supports the auxiliary wheel 92.

[0065] The first wheel support member 104 is provided with the first fork 104a that supports the first driven wheel 26 and the second fork 104b that supports the first fork and is supported to the second wheel support member 106. The first driven wheel 26 of the present embodiment is supported to the first fork 140a of the first wheel support member 104 via the wheel shaft 108.

[0066] The second wheel support member 106 is provided with the plate-shaped second base portion 106a and the plate-shaped second support portion 106b that extends downward from the second base portion 106a. The first wheel support member 104 is fixed to the second base portion 106a of the second wheel support member 106. The second support portion 106b supports the auxiliary wheel 92 via the wheel shaft 110.

[0067] The rotation connecting mechanism 66 of the present embodiment is provided with the shaft 88 that is installed to the wheel seat 22 and the rotation bearing 112 that is disposed between the shaft 88 and the wheel support body 64 and rotatably connects the wheel support body 64 to the shaft 88.

[0068] The rotation bearing 112 has an inner ring 112a, an outer ring 112b, and a plurality of rolling bodies 112c that roll on the inner ring 112a and the outer ring 112b. The shaft 88 of the present embodiment is fixed to the inner ring 112a of the rotation bearing 112 via a bearing retainer 114 that is attached to the lower end portion of the shaft 88. The rotation bearing 112 of the present embodiment is housed in a recessed portion 64a provided on the upper surface portion of the wheel support body 64, and the outer ring 112b thereof is fixed to the inner circumferential portion of the recessed portion 64a.

[0069] The above rotation support mechanism 62 causes the wheel support body 64 to rotate with respect to the wheel seat 22 about the rotation axis 60 that extends vertically through the shaft center of the shaft 88, thereby causing the first driven wheel 26 to rotate. The above rotation support mechanism 62 supports the first driven wheel 26 and the auxiliary wheel 92 so as to be able to rotate integrally about the rotation axis 60.

[0070] In addition, the shaft 88 of the rotation support mechanism 62 of the present embodiment also functions as the structure of the elevation support mechanism 82, and is attached to the wheel seat 22 via the linear motion bearing 86 used in the elevation support mechanism 82. When the shaft 88 of the rotation support mechanism 62 does not function as the structure of the elevation support mechanism 82, it can be attached to the wheel seat 22 in a manner that does not allow linear motion without using the linear motion bearing 86. Also, the shaft 88 of the elevation support mechanism 82 also functions as the structure of the rotation support mechanism 62, and is rotatably attached to the wheel support body 64 via the rotation bearing 112 used in the rotation support mechanism 62. When the shaft 88 of the elevation support mechanism 82 does not function as the structure of the rotation support mechanism 62, it can be non-rotatably attached to the wheel support body 64.

[0071] Next, the relevant operation of the above auxiliary wheel 92 will be described. Referring to FIG. 10(A), the positions of the first driven wheel 26, the auxiliary wheel 92, and the rotation axis 60 are shown only schematically. It is assumed that the traveling device 10 travels with the side opposite to the second driven wheel 28 (in this case, the front side) of the first driven wheel 26 set as the advancing direction. At this time, since the auxiliary wheel 92 protrudes toward the side opposite to the second driven wheel 28 in the front-rear direction X, as shown in FIG. 10(B), the auxiliary wheel 92 is able to ride up the step 80 present on the traveling surface before the first driven wheel 26. At this time, as described above, since the auxiliary wheel 92 is positioned at a location that is separated upward from the flat traveling surface 56, it is able to easily ride up the high step 80 compared to the case of contacting the traveling surface 56. Figure 8 Figure 8 In addition, the shaft 88 of the rotation support mechanism 62 of the present embodiment also functions as the structure of the elevation support mechanism 82, and is attached to the wheel seat 22 via the linear motion bearing 86 used in the elevation support mechanism 82. When the shaft 88 of the rotation support mechanism 62 does not function as the structure of the elevation support mechanism 82, it can be attached to the wheel seat 22 in a manner that does not allow linear motion without using the linear motion bearing 86. Also, the shaft 88 of the elevation support mechanism 82 also functions as the structure of the rotation support mechanism 62, and is rotatably attached to the wheel support body 64 via the rotation bearing 112 used in the rotation support mechanism 62. When the shaft 88 of the elevation support mechanism 82 does not function as the structure of the rotation support mechanism 62, it can be non-rotatably attached to the wheel support body 64. Figure 8 Figure 8 In addition, the shaft 88 of the rotation support mechanism 62 of the present embodiment also functions as the structure of the elevation support mechanism 82, and is attached to the wheel seat 22 via the linear motion bearing 86 used in the elevation support mechanism 82. When the shaft 88 of the rotation support mechanism 62 does not function as the structure of the elevation support mechanism 82, it can be attached to the wheel seat 22 in a manner that does not allow linear motion without using the linear motion bearing 86. Also, the shaft 88 of the elevation support mechanism 82 also functions as the structure of the rotation support mechanism 62, and is rotatably attached to the wheel support body 64 via the rotation bearing 112 used in the rotation support mechanism 62. When the shaft 88 of the elevation support mechanism 82 does not function as the structure of the rotation support mechanism 62, it can be non-rotatably attached to the wheel support body 64.

[0072] After the auxiliary wheel 92 has ridden up the step 80, if the traveling device 10 continues to advance toward the advancing direction,​​Figure 8 As shown in (C), the first driven wheel 26 is able to ride over the step 80. As a result, the auxiliary wheel 92 and the first driven wheel 26 are able to easily pass over the step 80 that is higher than the highest height that can be passed over by the first driven wheel 26 alone.

[0073] Further, when the auxiliary wheel 92 rides over the step 80, the link members 38, 40 of the swing arm bogie mechanism swing about the swing axes 44, 50 in response to the movement thereof. In this way, the driven wheels 24, 28 are in contact with the ground surface 56 during the period in which the auxiliary wheel 92 rides over the step 80, and the auxiliary wheel 92 is in contact with the step 80 present on the ground surface 56 instead of the first driven wheel 26. That is, the three wheels (the auxiliary wheel 92, the driven wheels 24, 28) are able to maintain a state in which they are in contact with the ground surface 56 even when the auxiliary wheel 92 rides over the step 80. Figure 8 In (A) to (C), the change in the inclination direction of the turning shaft 60 is shown, and thus the swinging of the link members 38, 40 is shown. In this way, although not shown, during the period in which the auxiliary wheel 92 rides over the step 80, the driven wheels 24, 28 are in contact with the ground surface 56, and the auxiliary wheel 92 is in contact with the step 80 present on the ground surface 56 instead of the first driven wheel 26. That is, the three wheels (the auxiliary wheel 92, the driven wheels 24, 28) are able to maintain a state in which they are in contact with the ground surface 56 even when the auxiliary wheel 92 rides over the step 80.

[0074] Next, the effects of the above-described suspension device 14 will be described.

[0075] (C) The suspension device 14 is provided with a lift support mechanism 82 that supports the first driven wheel 26 so as to be able to lift and lower. Therefore, the first driven wheel 26 is able to lift and lower in response to the step 80 on the ground surface 56, and thus the highest height of the step 80 that can be passed over by the first driven wheel 26 can be increased.

[0076] (D) The suspension device 14 is provided with the auxiliary wheel 92 that is located at a position apart from the ground surface 56. Therefore, by the combination of the auxiliary wheel 92 and the driven wheel 26, it is possible to pass over a step that is higher than the highest height that can be passed over by the driven wheel 26 alone. If the driven wheel 26 is made large in order to pass over such a high step, the front-rear dimension of the entire suspension device 14 will be made large in order to maintain the prescribed length ratios of La, etc. described above. In this regard, according to the present embodiment, it is not necessary to make the driven wheel 26 large in order to pass over a high step, and furthermore, it is possible to avoid the front-rear dimension of the entire suspension device 14 from being made large.

[0077] (E) The turning support mechanism 62 of the present embodiment supports the first driven wheel 26 and the auxiliary wheel 92 so as to be able to turn integrally. Therefore, when the suspension device 14 is to change the traveling direction, the first driven wheel 26 and the auxiliary wheel 92 are able to turn integrally in a state in which the rudders (directions) thereof are uniform in response to the change. Therefore, regardless of whether the suspension device 14 is traveling straight or turning, it is possible to pass over a step by the auxiliary wheel 92 in a state in which the rudders of the first driven wheel 26 and the auxiliary wheel 92 are uniform, and thus it is possible to maintain smooth movement before and after the step is ridden over.

[0078] (F) The lifting support mechanism 82 of the present embodiment supports the first driven wheel 26 and the auxiliary wheel 92 so as to be integrally liftable. Therefore, the first driven wheel 26 and the auxiliary wheel 92 can be integrally lifted in accordance with the steps of the walking surface 56, and thus the height that the first driven wheel 26 and the auxiliary wheel 92 can pass over can be further increased.

[0079] Next, a modification of each of the above-described components will be described.

[0080] In the embodiment, an example in which the first driven wheel 26 is a front wheel on one side (front side) in the front-rear direction X and the second driven wheel 28 is a rear wheel on the other side (rear side) in the front-rear direction X is described. In addition, the first driven wheel 26 can be a rear wheel on one side (rear side) in the front-rear direction X, and the second driven wheel 28 can be a front wheel on the other side (front side) in the front-rear direction X.

[0081] In the first embodiment, an example in which the length ratios of La and the like are set in such a manner that the vertical reaction forces Fb1, Fb2 are smaller than the vertical reaction force Fa is described. The relationship between the length ratios and the reaction force ratios is not particularly limited. For example, the length ratios of La and the like can be set in such a manner that the vertical reaction forces Fa, Fb1, Fb2 acting on each of the wheels 24, 26, 28 are equal. To achieve this, for example, La:Lb can be set to 1:1, and Lc(=La):Ld can be set to 1:2. Figure 3 In the first embodiment, an example in which the length ratios of La and the like are set in such a manner that the vertical reaction forces Fb1, Fb2 are smaller than the vertical reaction force Fa is described. The relationship between the length ratios and the reaction force ratios is not particularly limited. For example, the length ratios of La and the like can be set in such a manner that the vertical reaction forces Fa, Fb1, Fb2 acting on each of the wheels 24, 26, 28 are equal. To achieve this, for example, La:Lb can be set to 1:1, and Lc(=La):Ld can be set to 1:2.

[0082] Furthermore, when the vertical reaction forces Fb1, Fb2 acting on the driven wheels 26, 28 are made smaller than the vertical reaction force Fa acting on the drive wheel 24, the length ratios of La and the like are not limited to the contents of the embodiment. For example, when the vertical reaction force Fb1 of the first driven wheel 26 is made smaller than the vertical reaction force Fa of the drive wheel 24, La:Lb can be set to 1:X (X is a value larger than 1). In the embodiment, a case in which X is set to 2 is described, but X can be set to any value larger than 1. Thus, according to Equation (A), Fb1:Fa can be set to 1:X, that is, the vertical reaction force Fb1 can be made smaller than the vertical reaction force Fa. At this time, Lc:Ld can also be set to 1+X:1 (as a result, Lc:Le becomes 1:1). Thus, according to Equations (A) and (B), Fa:Fb1:Fb2 can be set to X:1:1. That is, both of the vertical reaction forces Fb1, Fb2 can be made smaller than the vertical reaction force Fa. Here, an example in which both of the vertical reaction forces Fb1, Fb2 are made smaller than the vertical reaction force Fa is described, but the length ratios of La and the like can be set in such a manner that at least one of the vertical reaction forces Fb1, Fb2 is made smaller than the vertical reaction force Fa.

[0083] The rotation support mechanism 62, the lift support mechanism 82, and the auxiliary wheel 92 described in the embodiments are not essential, and the suspension device 14 can not have one or more or all of them.

[0084] The rotation support mechanism 62 only needs to support the driven wheels 26, 28 so as to be rotatable, and a specific example thereof is not particularly limited. Also, in relation to the effects of the above (B), the rotation support mechanism 62 only needs to be provided in correspondence with either one of the first driven wheel 26 and the second driven wheel 28. That is, it can be said that the suspension device 14 only needs to have the rotation support mechanism 62 that supports one of the first driven wheel 26 and the second driven wheel 28 so as to be rotatable.

[0085] The wheel support body 64 only needs to be able to support the driven wheels 26, 28 so as to be rotatable about the shaft centers of the driven wheels 26, 28, and a specific structure thereof is not particularly limited.

[0086] The above describes an example in which the lift support mechanism 82 supports the first driven wheel 26 so as to be liftable. Also, in relation to the effects of the above (C), the lift support mechanism 82 can support the second driven wheel 28 so as to be liftable. That is, the lift support mechanism 82 only needs to support one of the first driven wheel 26 and the second driven wheel 28 so as to be liftable. At this time, the first driven wheel 26 can be replaced with the second driven wheel 28 in the description in the embodiments as a specific description thereof.

[0087] When the lift connection mechanism 84 of the lift support mechanism 82 uses the linear motion bearing 86, a specific example of the linear motion bearing 86 is not particularly limited, and for example, a sliding bushing or the like can be used. Also, the lift connection mechanism 84 of the lift support mechanism 82 can be a guide mechanism such as a linear guide rail in addition to the combination of the linear motion bearing 86 and the shaft 88.

[0088] The above describes an example in which the wheel support body 64 of the lift support mechanism 82 supports the driven wheel 26 and also supports the auxiliary wheel 92, but the auxiliary wheel 92 can not be supported and only the driven wheel 26 can be supported. At this time, the effects of the above (C) can also be obtained. Also, the above describes an example in which the lift support mechanism 82 supports the first driven wheel 26 and the auxiliary wheel 92 so as to be liftable in an integrated manner, but the second driven wheel 28 and the auxiliary wheel 92 can be supported so as to be liftable in an integrated manner.

[0089] In the first embodiment, the case where the auxiliary wheel 92 is provided corresponding to the first driven wheel 26 and the auxiliary wheel 92 protrudes toward the side opposite to the second driven wheel 28 with respect to the first driven wheel 26 in order to obtain the effect of the above (D) is described. The auxiliary wheel 92 can also be provided corresponding to the second driven wheel 28 and protrude toward the side opposite to the first driven wheel 26 with respect to the second driven wheel 28, whereby the same effect can also be obtained. That is, the auxiliary wheel 92 can protrude toward the side opposite to the other one of the first driven wheel 26 and the second driven wheel 28 with respect to one of the first driven wheel 26 and the second driven wheel 28 in the front-rear direction X. At this time, when the traveling device 10 travels with the side opposite to the first driven wheel 26 with respect to the second driven wheel 28 set as the traveling direction, the same effect as the above (D) can be obtained. Further, the auxiliary wheel 92 can also be separately provided corresponding to the first driven wheel 26 and the second driven wheel 28.

[0090] The ratio of the outer diameter of the drive wheel 24 to one of the first driven wheel 26 and the second driven wheel 28 can also be less than 2: 1. Also, the ratio of the outer diameter of the drive wheel 24 to one of the first driven wheel 26 and the second driven wheel 28 can be set to 2: 1 or more, and the ratio of the outer diameter of the drive wheel 24 to the other one of the first driven wheel 26 and the second driven wheel 28 can be set to less than 2: 1.

[0091] The above embodiments and modifications are examples. The idea of the technology that is abstracted from them should not be limited by the contents of the embodiments and modifications. With respect to the contents of the embodiments and modifications, various design changes such as changes, additions, and deletions of constituent elements can be made. In the above embodiments, with respect to the contents to which such design changes can be made, the sentence "embodiment" is emphasized. However, this does not mean that design changes are not allowed with respect to the contents without such a sentence. The hatching lines indicated on the cross sections of the drawings are not used to limit the material of the object to which the hatching lines are indicated. The structures / values mentioned in the embodiments and modifications of course include structures / values that can be considered to be the same if manufacturing errors and the like are taken into consideration.

Claims

1. A suspension device, characterized by, Possessing: a drive wheel; a first driven wheel, which is disposed on one side in the front-rear direction with respect to the drive wheel; a second driven wheel, which is disposed on the other side in the front-rear direction with respect to the drive wheel; and a bogie link member and a swing arm link member that constitute a swing arm bogie mechanism; wherein the bogie link member supports the drive wheel and the first driven wheel and is able to swing about a first swing axis, and the swing arm link member supports the second driven wheel and the bogie link member and is able to swing about a second swing axis; the suspension device further possesses an auxiliary wheel, which is located at a position separate from a traveling surface when one of the first driven wheel and the second driven wheel is in a state of contact with the traveling surface; when viewed in the left-right direction, the first swing axis is located more on the first driven wheel side than a rotation axis of the drive wheel, and is located more above the vertical direction than the rotation axis and on the inside of the outer shape of the drive wheel; the auxiliary wheel protrudes toward the opposite side in the front-rear direction from the other driven wheel with respect to the one driven wheel, when the auxiliary wheel rides up a step, the bogie link member swings about the first swing axis following the action thereof, and the swing arm link member swings about the second swing axis following the action thereof.

2. The suspension device according to claim 1, characterized in that: the bogie link member is connected to the swing arm link member in a manner that is able to swing about the first swing axis via a first support bearing.

3. The suspension device according to claim 1 or 2, characterized in that: a lift support mechanism is possessed that supports the one of the first driven wheel and the second driven wheel in a manner that is able to lift.

4. The suspension device according to claim 1 or 2, characterized in that: an outer diameter of the auxiliary wheel is larger than an outer diameter of the one driven wheel.

5. The suspension device according to claim 4, characterized in that: a rotation support mechanism is possessed that supports the one driven wheel and the auxiliary wheel in a manner that is able to rotate integrally about a rotation axis that extends vertically.

6. The suspension device according to claim 4, characterized in that: a lift support mechanism is possessed that supports the one driven wheel and the auxiliary wheel in a manner that is able to lift integrally.

7. The suspension device according to claim 1 or 2, characterized in that: a ratio of an outer diameter of the drive wheel to an outer diameter of the one of the first driven wheel and the second driven wheel is 2: 1 or more.

8. A walking device characterized by comprising: Possessing: a device main body; and the suspension device according to claim 1 or 2 that is mounted to the device main body.

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