Transport vehicle having road surface adaptive suspension

Abstract

The present invention provides a transport vehicle having a road surface adaptive suspension, which can increase stability when driving by using a suspension having a simple configuration, can further improve stability when driving by allowing all wheels to always be in close contact with the ground with a constant load, and can prevent food from being spilled even when transporting the food by eliminating a phenomenon in which the transport vehicle is tilted forward during braking. The transport vehicle of the present invention comprises: a first pivot shaft positioned between a first caster wheel and a driving wheel and installed on a vehicle body frame; a first link arm having one end connected to the first pivot shaft and the other end on which the first caster wheel is installed; a second link arm installed on a rotation center shaft of the driving wheel and having one end connected to the first pivot shaft; a second pivot shaft positioned between a second caster wheel and the driving wheel and installed on the vehicle body frame; a third link arm installed on the second pivot shaft and having one end on which the second caster wheel is installed; and a fourth link arm configured to connect the other ends of the second link arm and the third link arm so that the second link arm and the third link arm can rotate in conjunction with each other in directions opposite to each other.

Description

Transport vehicle equipped with road-adaptive suspension

[0001] The present invention relates to a transport vehicle, and more specifically, to a transport vehicle equipped with a plurality of caster wheels and a drive wheel, and having a road surface adaptive suspension that enables stable driving while minimizing shaking even when driving on a road surface that is uneven or has protruding parts.

[0002] A transport vehicle that combines caster wheels installed on the front and rear left and right sides of the vehicle frame with drive wheels positioned on the middle left and right sides to perform driving and steering together through the difference in rotational speed and direction of rotation of the drive wheels, has no actuator for steering, making it easy to control and offering many advantages in terms of structure and cost. As such, it is widely used recently in autonomous mobile robots (AMR), industrial transport robots (Automated Guided Robots; AGV), and robot vacuum cleaners.

[0003] FIG. 1 shows a conventional transport vehicle. As illustrated, caster wheels (1, 2) for preventing tilting are installed on the left and right sides of the vehicle body frame (3) in the front and rear directions, respectively, and drive wheels (4) are installed on the left and right sides of the middle section, driven by a drive motor installed on the vehicle body frame (3) or an internal drive motor.

[0004] Therefore, driving and steering are performed together by controlling the rotational speed and rotational direction of the left and right drive wheels (4) respectively.

[0005] In addition, the conventional transport vehicle is equipped with tension devices (5, 6, 7) on each caster wheel (1, 2) and drive wheel (4) so ​​as to absorb shock when driving on uneven terrain.

[0006] However, the above tension device (5, 6, 7) is formed by combining several parts including a guide shaft, a slide block, and a coil spring, and is installed independently on the caster wheel (1, 2) and the drive wheel (4), respectively, so the overall configuration of the transport vehicle is very complex. As a result, there are disadvantages such as reduced assembly efficiency during manufacturing due to the increase in the number of parts, increased manufacturing costs, and increased overall weight of the vehicle body.

[0007] Furthermore, since conventional transport vehicles utilize the elastic force of coil springs as tension devices (5, 6, 7), they are sensitive to spring tension and have a limited vertical stroke, which can cause the drive wheel (4) or caster wheel (1, 2) to detach from the ground. In this case, the load acting on the drive wheel (4) and caster wheel (1, 2) changes, causing the vehicle to become unstable or unable to drive.

[0008] In addition, since the tension devices (5, 6, 7) installed on the caster wheels (1, 2) and the drive wheel (4) of the conventional transport vehicle operate independently, a phenomenon may occur where the vehicle tilts to one side depending on the load applied to each tension device (5, 6, 7). Consequently, when the transport vehicle is applied to a serving robot, if the vehicle is driven and then braked, it may tilt forward due to inertia, causing food to spill out.

[0009] The present invention aims to solve the aforementioned conventional problems, and its purpose is to provide a transport vehicle having a road surface adaptive suspension that enables stable driving using a suspension with a simple configuration, reduces the number of parts to decrease overall weight, improves assembly during manufacturing, and reduces manufacturing costs.

[0010] Another objective of the present invention is to provide a transport vehicle having a road-adaptive suspension that can increase horizontal stability and driving stability without load fluctuations even with changes in the road surface, prevent driving instability by ensuring all wheels are always in contact with the ground with a constant load, and prevent spillage when transporting food by eliminating the phenomenon of tilting forward during braking.

[0011] To achieve the above objective, the present invention relates to a transport vehicle comprising a first caster wheel installed on the front left and right sides of a vehicle body frame, a second caster wheel installed on the rear left and right sides of a vehicle body frame, and a drive wheel installed on the middle left and right sides of a vehicle body frame, wherein the transport vehicle comprises: a first pivot shaft located between the first caster wheel and the drive wheel and fixedly installed on the vehicle body frame with the left-right direction as its axis; a first link arm having one end rotatably connected to the first pivot shaft and the first caster wheel installed on the other end; a second link arm rotatably installed on the rotational center axis of the drive wheel and having one end rotatably connected to the first pivot shaft; a second pivot shaft located between the second caster wheel and the drive wheel and fixedly installed on the vehicle body frame with the left-right direction as its axis; and a third link arm rotatably installed on the second pivot shaft and having the second caster wheel installed on one end. The transport vehicle is characterized by including a fourth link arm that rotatably connects the other ends of the second link arm and the third link arm so that the second link arm and the third link arm are linked in opposite rotational directions.

[0012] In addition, the present invention features a transport vehicle configured such that, while the drive wheel and the first and second caster wheels are in contact with a horizontal plane, the rotational center axis of the drive wheel and the first and second pivot axes are located on the same horizontal line, and the vehicle body frame is configured to maintain a horizontal position.

[0013] In addition, the present invention is characterized by a transport vehicle further comprising first and second elastic members that are elastically installed between the ends of the first and third link arms, on which the first and second caster wheels are installed, and the vehicle body frame, and which provide elastic force to the first and second caster wheels in a direction that separates them from the vehicle body frame.

[0014] In addition, the present invention is characterized by a transport vehicle further comprising a third elastic member elastically installed between the end of the third link arm to which the fourth link arm is connected and the vehicle body frame, and providing elastic force to the connecting portion of the third and fourth link arms in a direction separated from the vehicle body frame.

[0015] According to the characteristic configuration of the present invention described above, since the suspension function for stable driving even on uneven roads is achieved by the first to fourth link arms connecting the first and second caster wheels and the drive wheel, the configuration of the transport vehicle can be simplified and the weight and number of parts can be reduced to the maximum extent, thereby improving assembly and productivity during manufacturing and significantly reducing manufacturing costs.

[0016] In addition, the transport vehicle equipped with the road surface adaptive suspension of the present invention has the effect of further improving stability during driving, as the rotational center axis of the drive wheel connected to the first to fourth link arms performing the suspension function and the first and second pivot axes are located on the same horizontal line as the lower part of the vehicle body frame, thereby increasing the load that presses the drive wheel in the middle part against the ground, and as a result, power transmission with the ground is reliably achieved, and the load acting on each wheel does not change even with changes in the road surface, and all wheels can always press against the ground with a constant load.

[0017] In addition, the transport vehicle equipped with the road surface adaptive suspension of the present invention can eliminate the phenomenon of tilting forward during braking through the suspension function consisting of the first to fourth link arms, and as a result, even when the transport vehicle is applied to a serving robot, stable driving is achieved, thereby effectively resolving the problem of food spilling.

[0018] In addition, the transport vehicle equipped with the road surface adaptive suspension of the present invention can be conveniently used in various fields such as autonomous vehicles, logistics loading and transport robots, delivery robots, cleaning robots, serving robots, companion robots, guide robots, and pesticide or fertilizer spraying robots.

[0019] FIG. 1 is a longitudinal section view showing a conventional transport vehicle.

[0020] FIG. 2 is a perspective view showing a transport vehicle according to the present invention.

[0021] FIG. 3 is a perspective view of a transport vehicle with one drive wheel removed from FIG. 2.

[0022] FIG. 4 is a perspective view of the transport vehicle in FIG. 3 seen from below.

[0023] Fig. 5 is a side view of Fig. 3.

[0024] FIGS. 6 to 9 are comparison diagrams of the operating states of the transport vehicle of the present invention and a conventional transport vehicle.

[0025] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0026] FIGS. 2 to 5 illustrate a transport vehicle equipped with a road surface adaptive suspension according to the present invention. As illustrated, the transport vehicle of the present invention has first and second caster wheels (12, 13) installed on the front and rear left and right sides of the vehicle body frame (11), and drive wheels (14) installed on the left and right sides at the midpoint of the vehicle body frame (11). It is preferable that the drive wheels (14) on both sides be of the type with an internal drive motor (not shown), or they may be configured as an external type driven by a drive motor separately provided on the vehicle body frame (11).

[0027] In addition, the first and second caster wheels (12, 13) and the drive wheel (14) are equipped with a suspension that enables stable driving even on uneven road surfaces.

[0028] That is, the suspension of the present invention comprises first and second pivot shafts (21, 22) installed on both the left and right sides of the vehicle body frame (11). The first pivot shaft (21) is located between the first caster wheel (12) and the drive wheel (14) and is fixedly installed on the vehicle body frame (11) with the left and right directions as the axis.

[0029] The second pivot shaft (22) is located between the second caster wheel (13) and the drive wheel (14) and is fixedly installed on the vehicle body frame (11) with the left and right directions as the axis.

[0030] Additionally, the first and second caster wheels (12, 13) are connected to the drive wheel (14) by the first to fourth link arms (31, 32, 33, 34). One end of the first link arm (31) is rotatably connected to the first pivot shaft (21), and the first caster wheel (12) is installed on the other end.

[0031] The second link arm (32) is rotatably installed on the drive wheel (14) and is rotatably connected to the first pivot shaft (21).

[0032] The third link arm (33) is rotatably installed on the second pivot shaft (22), and the second caster wheel (13) is installed at one end.

[0033] The fourth link arm (34) is intended to connect the other ends of the second and third link arms (32, 33), and is rotatably connected to the other ends of the second link arm (32) and the third link arm (33) so that the second link arm (32) and the third link arm (33) move in opposite rotational directions.

[0034] That is, by setting the connection part between the second link arm (32) and the fourth link arm (34) to be located at the lower part of the connection part between the third link arm (33) and the fourth link arm (34), when the second link arm (32) rotates clockwise around the rotational center axis (14a) of the drive wheel (14), the fourth link arm (34) pushes up the third link arm (33) to rotate counterclockwise around the second pivot axis (22), and when the second link arm (32) rotates counterclockwise around the rotational center axis (14a) of the drive wheel (14), the fourth link arm (34) pulls down the third link arm (33) to rotate clockwise around the second pivot axis (22).

[0035] In addition, the present invention is preferably configured such that when the drive wheel (14) and the first and second caster wheels (12, 13) are in contact with a horizontal plane, the rotational center axis (14a) of the drive wheel (14) and the first and second pivot axes (21, 22) are located on the same horizontal line, and the vehicle body frame (11) is maintained horizontally.

[0036] In addition, first and second elastic members (41, 42) are elastically installed between the ends of the first and third link arms (31, 33), on which the first and second caster wheels (12, 13) are installed, and the vehicle body frame (11). The first and second elastic members (41, 42) are composed of compression coil springs and have both ends supported by the first and third link arms (31, 33) and the vehicle body frame (11), respectively, thereby providing elastic force so that the first and second caster wheels (12, 13) are always separated from the vehicle body frame (11).

[0037] In addition, a third elastic member (43) is elastically installed between the end of the third link arm (33), to which the fourth link arm (34) is connected, and the vehicle body frame (11). The third elastic member (43) is also composed of a compression coil spring and has both ends supported by the third link arm (33) and the vehicle body frame (11), respectively, thereby providing elastic force so that the connecting portions of the third and fourth link arms (34) are always separated from the vehicle body frame (11).

[0038] The operation of the transport vehicle equipped with the road surface adaptive suspension of the present invention, configured as described above, is as follows.

[0039] FIGS. 6 to 9 are diagrams showing the operation state of a transport vehicle equipped with a road surface adaptive suspension according to the present invention and a transport vehicle equipped with a conventional tension device. As shown in FIG. 6 (a), the suspension according to the present invention is composed of first to fourth link arms (31, 32, 33, 34) connecting the rotational center axis (14a) of the drive wheel (14) and the first and second pivot axes (21, 22). As shown in FIG. 6 (b), the configuration is greatly simplified compared to a conventional transport vehicle equipped with a tension device (5, 6, 7), thereby reducing weight and reducing the number of parts by more than 60%, which can significantly reduce manufacturing costs.

[0040] In addition, the load acting on the vehicle body frame (11) of the present invention is distributed to both sides centered on the drive wheel (14) by the first and second pivot axes (21, 22), so that 50% is applied to the middle drive wheel (14) and 25% each to the first and second caster wheels (12, 13) on both sides, and as a result, the contact force between the drive wheel (14) and the ground is large, so power transmission is reliably achieved and the vehicle can drive smoothly.

[0041] In contrast, since the drive wheel (4) in the middle and the caster wheels (1, 2) on both sides are each individually installed by their respective tension devices (5, 6, 7), the load acting on the vehicle body frame (1) acts unevenly, ranging from 0 to 100% depending on the position of the load. Consequently, when the load acting on the drive wheel (4) and the ground is low and the contact force is insufficient, smooth driving is not achieved due to slipping, and in severe cases, spinning occurs.

[0042] In addition, when driving on an uneven road surface as shown in FIG. 7 (a) and FIG. 8 (a), the present invention ensures excellent driving stability by ensuring that the intermediate drive wheel (14) and the front and rear first and second caster wheels (12, 13) are always in close contact with the ground through the first to fourth link arms (31, 32, 33, 34). However, in conventional transport vehicles, as shown in FIG. 7 (b), the front and rear caster wheels (1, 2) come into contact with the ground and the intermediate drive wheel (4) deviates from the ground, which can result in unstable or impossible driving. Furthermore, as shown in FIG. 8 (b), if the intermediate drive wheel (4) comes into contact with the ground and the front and rear caster wheels (1, 2) deviate from the ground, the transport vehicle tilts forward and backward, and thus stable driving is not achieved.

[0043] That is, in the present invention, as shown in FIG. 7 (a), when the ground on the front and rear sides of the first and second caster wheels (12, 13) is high and the ground on the middle side of the drive wheel (14) is low, the first and third link arms (31, 33) rotate around the first and second pivot shafts (22) by the height difference, thereby bringing the drive wheel (14) into close contact with the ground, so that the driving force of the drive wheel (14) is maintained and smooth driving can be continued.

[0044] In addition, as shown in FIG. 8 (a), even when the ground on the front and rear sides of the first and second caster wheels (12, 13) is low and the ground on the middle side of the drive wheel (14) is high, the first and third link arms (31, 33) rotate around the first and second pivot axes (21, 22) by the height difference, thereby bringing the front and rear first and second caster wheels (12, 13) into close contact with the ground, so that the transport vehicle can continue stable driving without tilting forward or backward.

[0045] Next, as shown in FIG. 9 (a), the transport vehicle of the present invention is connected to the intermediate drive wheel (14) and the front and rear first and second caster wheels (12, 13) by the first to fourth link arms (31, 32, 33, 44) even when the load shifts forward due to inertia during braking, so all wheels can maintain contact with the ground. However, as shown in FIG. 9 (b), the conventional transport vehicle is supported separately by the drive wheel (4) and the front and rear caster wheels (1, 2) by tension devices (5, 6, 7), so when the load shifts forward due to inertia during braking, a large load is applied to the front caster wheel (1) and it tilts forward. Consequently, when the transport vehicle is applied to a serving robot, food may spill out while driving.

[0046] According to the transport vehicle equipped with the road surface adaptive suspension of the present invention, the first to fourth link arms (31, 32, 33, 34) connecting the first and second caster wheels (12, 13) on the front and rear sides and the intermediate drive wheel (14) allow the drive wheel (14) and the first and second caster wheels (12, 13) to always be in contact with the ground even on uneven road surfaces, enabling stable and smooth driving, and there is no tilting when braking, making it very useful for transporting heavy weights or food.

[0047] In addition, according to the first and third elastic members (41, 42, 43) installed between the body frame (11) and the first and third link arms (31, 33), when the first and third link arms (31, 33) repeatedly rotate forward and reverse at a predetermined angle around the first and second pivot axes (21, 22) while driving on flat and uneven road surfaces as shown in FIGS. 6 to 9, the members elastically contract and expand, thereby mitigating the impact during the operation of the first and third link arms (31, 33) and enabling more stable and unwavering driving.

[0048] In addition, in this embodiment, a road surface adaptive suspension is applied to a transport vehicle in which the drive wheels (14) on both sides are driven by a drive motor not shown, but it is not limited thereto and can also be applied to a transport vehicle in which the drive wheels (14) are not driven by a drive motor.

[0049] Optimal embodiments have been disclosed in the drawings and specification as described above. Specific terms have been used herein, but they are used only for the purpose of describing the invention and are not intended to limit the meaning or the scope of the invention as described in the claims. Therefore, those skilled in the art will understand that various modifications and equivalent alternative embodiments are possible therefrom. Accordingly, the true technical scope of protection of the invention should be determined by the technical spirit of the appended claims.

Claims

1. A transport vehicle comprising a first caster wheel installed on the front left and right sides of a body frame, a second caster wheel installed on the rear left and right sides of a body frame, and a drive wheel installed on the middle left and right sides of a body frame, A first pivot shaft located between the first caster wheel and the drive wheel, and fixedly installed on the body frame with the left-right direction as the axis; A first link arm having one end rotatably connected to the first pivot shaft and the other end having the first caster wheel installed thereon; A second link arm rotatably installed on the rotational center axis of the above-mentioned drive wheel, with one end rotatably connected to the above-mentioned first pivot axis; A second pivot shaft located between the second caster wheel and the drive wheel, and fixedly installed on the vehicle body frame with the left-right direction as the axis; A third link arm rotatably installed on the second pivot shaft and having the second caster wheel installed at one end; and A transport vehicle characterized by including a fourth link arm that rotatably connects the other ends of the second link arm and the third link arm so that the second link arm and the third link arm are coupled in opposite rotational directions.

2. A transport vehicle according to claim 1, characterized in that, while the drive wheel and the first and second caster wheels are in contact with a horizontal plane, the rotational center axis of the drive wheel and the first and second pivot axes are located on the same horizontal line, and the vehicle body frame is set to maintain a horizontal position.

3. A transport vehicle according to claim 2, further comprising first and second elastic members elastically installed between the ends of the first and third link arms on which the first and second caster wheels are installed and the vehicle body frame, and providing elastic force to the first and second caster wheels in a direction separated from the vehicle body frame.

4. A transport vehicle according to claim 3, further comprising a third elastic member elastically installed between the end of the third link arm to which the fourth link arm is connected and the vehicle body frame, and providing elastic force in a direction in which the connecting portion of the third and fourth link arms is separated from the vehicle body frame.

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