Carrying vehicle and tray in-out mechanism thereof

Abstract

The front portion of a pallet fork is divided into a fork tip and a fork plate transition part, the fork tip is located at the foremost end of the pallet fork, the bottom face of the fork tip is higher than the bottom face of the fork plate transition part, and a guide wheel assembly is arranged at the connecting position of the fork tip and the fork plate transition part; the bottom of the fork plate transition part is of a flat straight line structure and used for guiding the bottom of the pallet fork to make contact with a tray. The load wheel in a suspended state is positioned at the front part of the fork plate transition part, and the bottom of the load wheel is downwards exposed out of the fork plate transition part; a roller assembly is arranged in the middle of the fork plate transition part, and the bottom of the roller assembly protrudes out of the bottom of the fork plate transition part. By means of the structure, friction between the pallet fork and a tray can be reduced, and therefore the pallet fork can enter and exit from the tray smoothly.

Description

Technical Field

[0001] The present invention relates to an AGV vehicle, and particularly to a forklift truck and its pallet entry and exit mechanism. Background Art

[0002] In recent years, handling robots have been widely used in the logistics and warehousing fields. However, there are significant deficiencies in their adaptability to pallets with crossbeams at the bottom (such as American standard pallets, cross-shaped pallets, etc.). Taking the American standard pallet as an example, due to its mature technology and low cost, the American standard pallet dominates the global market. However, existing handling robots maintain a constant and low-speed movement characteristic when entering and exiting the pallet, making it impossible for them to smoothly enter and exit the American standard pallet. Especially for an empty American standard pallet, since the empty pallet is light in weight and the bottom of the American standard pallet has multiple upward protruding structures, it is very easy for the forklift forks to get stuck in the pallet and drive the pallet to move together when entering and exiting the pallet, and it is impossible to stably enter and exit the American standard pallet, resulting in users being forced to use non-standard pallets or customized solutions, greatly increasing the usage cost.

[0003] In the prior art, there are also solutions proposed for American standard pallets. Generally, an independent power source needs to be set up to raise the forklift forks when entering and exiting the pallet to enable them to smoothly enter and exit the pallet. For example, the industrial handling vehicle disclosed in CN118479396A realizes double-sided pallet fork picking by tilting the vehicle body through a jacking mechanism. However, it relies on a hydraulic or electric power source, with a complex structure and high energy consumption. Summary of the Invention

[0004] The present invention provides a forklift truck and its pallet entry and exit mechanism, which does not require setting an additional power source. Using a pure mechanical structure can enable the forklift forks to smoothly enter and exit pallets with crossbeams such as American standard pallets, solve the problem that the forklift robot is prone to jamming when entering and exiting the pallet under the characteristics of constant and low-speed movement, and has a low cost.

[0005] A pallet entry and exit mechanism of a forklift truck includes:

[0006] A forklift fork mechanism, including a forklift fork frame and forklift forks installed on the forklift fork frame;

[0007] A load wheel assembly, including a first wheel frame and load wheels installed on the first wheel frame. The load wheel assembly is driven by a linkage mechanism to switch between a load-bearing state and a suspended state;

[0008] The front part of the forklift fork is divided into a fork tip and a fork plate transition part. The fork tip is located at the front end of the forklift fork, and its bottom surface is higher than the bottom surface of the fork plate transition part. A guide wheel assembly is provided at the connection between the fork tip and the fork plate transition part; the bottom of the fork plate transition part is a straight line structure for guiding the contact between the bottom of the forklift fork and the pallet; the load wheels in the suspended state are located in front of the fork plate transition part, and their bottoms protrude downward from the fork plate transition part; a roller assembly is provided in the middle of the fork plate transition part, and the bottom of the roller assembly protrudes from the bottom of the fork plate transition part;

[0009] A link locking mechanism is also included for locking the load wheel assembly in a suspended state when the fork enters or exits the pallet.

[0010] In the above scheme, the stepped design of the transition part between the fork tip and the fork plate is combined with the guide wheel assembly to avoid the collision between the front end of the fork and the lower crossbeam of the pallet. The guide wheel assembly can smoothly guide the fork to be lifted into the pallet; the bottom of the fork plate transition part is a straight line, which occupies the relatively long end of the front of the pallet, serving as the transition line for the fork plate to enter and exit the pallet, preventing it from colliding with the concave and convex parts inside the pallet; the suspended load wheel and the protruding roller convert static friction into rolling friction to reduce the resistance to entry and exit. The roller only slightly protrudes from the fork plate transition part, which can avoid jamming during entry and exit; the connecting rod locking mechanism ensures that the load wheel is stably suspended. The pallet entry and exit mechanism of the above scheme is a scheme without an independent power source. It is based on a pure mechanical structure and the coordinated action of the fork plate transition part, the lifting guide wheel assembly and the roller assembly to achieve low-speed and uniform speed entry and exit of a pallet with a crossbeam, such as an American standard pallet. Compared with the scheme of setting an additional power source, the control is simpler.

[0011] Preferably, the connecting rod mechanism includes a rocker rod and a long connecting rod, the rocker rod is connected to the fork frame, one end of the rocker rod is connected to one end of the long connecting rod, and the other end of the long connecting rod is connected to the first wheel frame of the load wheel assembly; the lifting of the fork mechanism drives the rocker rod and the long connecting rod to drive the load wheel assembly to switch between the load-bearing state and the suspended state. The lifting of the fork automatically drives the connecting rod to switch the load wheel state without an independent power source; the pure mechanical structure reduces energy consumption and maintenance costs and improves reliability.

[0012] Preferably, the connecting rod locking mechanism includes a limiter and a limiter seat; the limiter is fixed on the swing arm, and one end of the limiter extends into the first space of the limiter seat; the limiter moves with the swing arm in the first space of the limiter seat; when the load wheel is suspended, the limiter abuts against the first side of the first space, and the limiter has a tendency to continue to move toward the first side. The abutment design of the limiter and the limiter seat forms a mechanical self-locking to prevent the load wheel from accidentally falling when entering and exiting the pallet; when the load wheel is suspended, the limiter has a tendency to continue to move toward the first side to prevent the load wheel from falling under its own weight, and the locking structure is simple and reliable.

[0013] Preferably, the first wheel frame of the load wheel is connected to the fork at a first hinge point, the first wheel frame is hinged to the second hinge point of the connecting rod mechanism, and the roller assembly is arranged at the second hinge point. The roller assembly is directly arranged at the stress-bearing hinge point, and no additional installation structure of the roller assembly is required, so the structure is simple.

[0014] Preferably, the guide wheel assembly includes a plurality of lifting guide wheels, which are arranged along the stepped inclined plane for guiding. The stepped guide wheel layout matches the height change of the lower cross beam of the American standard pallet, gradually lifting the front end of the fork; the arrangement of multiple guide wheels realizes the contour passability and stable lifting and guiding.

[0015] Preferably, the guide wheel assembly includes a second wheel carrier, and a plurality of lifting guide wheels are installed on the fork through the same second wheel carrier. The installation through the second wheel carrier reduces the installation complexity.

[0016] Preferably, the plurality of lifting guide wheels are divided into two groups, and the two groups of lifting guide wheels are respectively installed on both sides of the second wheel carrier and are staggered. The staggered guide wheel groups expand the contact coverage range with the pallet, adapting to different sizes of cross beams; avoiding the failure of the single-side guide wheels when the fork is tilted and improving the fault tolerance.

[0017] A handling vehicle includes a pallet access mechanism of a handling vehicle as described in any one of the above.

[0018] The handling vehicle is an AGV vehicle. With the above-mentioned pallet access structure, the friction force between the vehicle and the pallet during pallet access is small, which is suitable for the characteristics of the low-speed and uniform-speed access of the AGV vehicle to the pallet. Description of the Drawings

[0019] Figure 1 It is a schematic structural diagram of an American standard pallet at an angle;

[0020] Figure 2 For Figure 1 A schematic structural diagram at another angle;

[0021] Figure 3 It is a schematic structural diagram of the present application;

[0022] Figure 4 It is a schematic structural diagram (bottom) of the handling vehicle carrying an American standard pallet;

[0023] Figure 5 For Figure 4 A cross-sectional view of;

[0024] Figure 6 It is one of the schematic diagrams of the process of the fork entering the American standard pallet;

[0025] Figure 7 It is the second of the schematic diagrams of the process of the fork entering the American standard pallet.

[0026] Reference Signs:

[0027] Pallet 10, cross beam 11, longitudinal beam 12,

[0028] Fork mechanism 20, fork carriage 21, forks 22, fork tips 221, fork plate transition part 222, roller assembly 23, guide wheel assembly 24, second wheel carrier 241, lifting guide wheel 242,

[0029] Load wheel assembly 30, first wheel carrier 31, arc-shaped avoidance part 311, load wheel 32,

[0030] Linkage mechanism 40, swing rod 41, long link 42,

[0031] Link locking mechanism 50, limit piece 51, limit seat 52, first space 521. Specific embodiments

[0032] The present application will be further specifically described below through specific embodiments in conjunction with the accompanying drawings of the specification.

[0033] American Standard pallet

[0034] The American Standard pallet 10 is a standardized pallet 10 widely used in the North American region, mainly used for logistics, warehousing and cargo transportation. As Figure 1-2 shown, both the upper and lower surfaces of the American Standard pallet 10 are load-bearing surfaces, supported by longitudinal beams 12 and cross beams 11 in the middle, and 3 longitudinal beams 12 are provided at the bottom to form two rows of fork holes for the forklift of the handling vehicle to enter.

[0035] Pallet entry and exit mechanism

[0036] As Figure 3 shown, the pallet entry and exit mechanism includes a fork mechanism 20, a linkage mechanism 40, a load wheel assembly 30, and a link locking mechanism 50. The fork mechanism 20 includes a fork carriage 21 and forks 22 installed on the fork carriage 21. The fork carriage 21 is installed on the vehicle frame and has a stroke of moving up and down relative to the vehicle frame, and is driven by a lifting mechanism to lift along the vehicle frame. In the embodiment, the lifting mechanism can be a lifting oil cylinder or an electric cylinder. In this embodiment, the fork carriage 21 refers to the mechanism on the vehicle frame that installs the forks and drives them to lift. For example, in a specific embodiment, the vehicle frame of the handling vehicle is divided into a front vehicle frame and a rear vehicle frame. The forks are welded and fixed to the front vehicle frame. The front vehicle frame and the rear vehicle frame are matched through rollers and chutes, and the front vehicle frame can be driven by a lifting structure to lift along the rear vehicle frame. In this embodiment, the front vehicle frame is the fork carriage described here.

[0037] In this embodiment, the front part of the fork 22 is divided into a fork tip 221 and a fork plate transition part 222. The fork tip 221 is located at the very front end of the fork 22, and the width of the fork tip 221 is relatively narrow so as to easily enter the pallet 10. The bottom surface of the fork tip is higher than the bottom surface of the fork plate transition part 222. Thus, the connection between the fork tip 221 and the fork plate transition part 222 is transitioned through an inclined surface. The inclined surface transition is beneficial for the fork 22 to cooperate with the bottom step of the pallet 10 during the process of entering the pallet 10 for climbing guidance. In a preferred embodiment, a guide wheel assembly 24 is provided at the connection between the fork tip 221 and the fork plate transition part 222 to reduce the frictional force between the fork 22 and the pallet 10 through rolling friction. As Figure 3 shown, the bottom of the fork plate transition part 222 is a long straight line to assist the fork 22 in avoiding jamming due to the unevenness of the bottom of the fork plate during the process of entering and exiting the pallet 10. Moreover, the fork plate transition part 222 is the thickest part of the fork 22, and a transition inclined surface is also formed at the connection between the fork plate transition part 222 and the fork plate behind it. When the fork 22 passes through the step during entering and exiting the pallet 10, it can also play a guiding role through the inclined surface.

[0038] See Figure 4 , for the American standard pallet, several gaps are formed between adjacent crossbeams at the bottom of the pallet. The length of the fork plate transition part 222 is greater than the width of the widest gap among them to avoid the fork getting stuck at the crossbeam gap during the process of entering and exiting.

[0039] The link mechanism 40 includes a swing rod 41 and a long link 42. The swing rod 41 has three hinged ends, and the relative positions of the three hinged ends on the swing rod 41 always remain fixed; the first hinged end of the swing rod 41 is hinged to the vehicle frame, the second hinged end of the swing rod 41 is hinged to the fork carrier 21, the third hinged end of the swing rod 41 is hinged to one end of the long link 42. While the fork mechanism 20 moves up and down, the second hinged end rotates in a circular motion around the first hinged end, driving the third hinged end to drive the long link 42 to move horizontally, so as to drive the first wheel carrier 31 connected to the front end of the long link 42 to move.

[0040] In a specific embodiment, the specific structure of the link mechanism 40 and the connection method with the fork mechanism 20 can adopt those disclosed in, for example, the patent with publication number CN117658023A or CN118723873A.

[0041] The load wheel assembly 30 includes a first wheel carrier 31 and load wheels 32 installed on the first wheel carrier 31. The load wheel assembly 30 is driven by the link mechanism 40 to switch between a load-bearing state and a suspended state. In the load-bearing state, the load wheels 32 extend from below the fork 22 to contact the ground, as Figure 5 shown; in the suspended state, the load wheels 32 retract into the fork 22 to avoid the load wheel assembly 30 hindering the entry and exit of the pallet 10. The position of the load wheels 32 in the suspended state is as Figure 3, 6 as shown in FIG. -7.

[0042] On one side of the first wheel carrier 31 close to the long connecting rod 42, there are a first hinge point and a second hinge point. The first wheel carrier 31 is hinged to the forklift fork 22 at the first hinge point or the second hinge point, and one end of the long connecting rod 42 is connected at the other hinge point, so that the linkage mechanism 40 can drive the load wheel assembly 30 to switch between the bearing state and the suspended state.

[0043] It should be further noted that, referring to Figure 3 and Figure 5 , the inner side of the first wheel carrier is defined as the side located below in the suspended state. There is an upward protrusion relief portion 311 on the inner side of the first wheel carrier, and the relief portion is arranged close to the long connecting rod. Thus, after switching to the suspended state, the lower tray is avoided through this relief portion. Specifically, referring to Figure 5 , after the forklift fork enters the tray in place, the load wheel assembly 30 is located at the first gap on the tray, so that the load wheel can move downward through this first gap to contact the ground. In this embodiment, by setting the relief portion, the distance between the first wheel carrier and the edge of the first gap is increased, so as to avoid interference between the first wheel carrier and the bottom of the tray during the switching between the bearing state and the suspended state. On this basis, in the bearing state, the first wheel carrier tilts forward from back to increase the distance from the edge of the first gap.

[0044] As Figure 4-5 shown, the link locking mechanism 50 is used to lock the load wheel assembly 30 in the suspended state when the forklift fork 22 enters or exits the tray 10. Through the link locking mechanism 50, it is ensured that the load wheels 32 are suspended during the process of the forklift fork 22 entering and exiting the tray 10, and it will not hinder the load wheel assembly 30 from switching to the bearing state after the forklift fork 22 enters and exits the tray 10 in place. For the action relationship of the cooperation of the load wheel assembly 30, the linkage mechanism 40 and the forklift fork mechanism 20 in this embodiment, reference can be made to, for example, those disclosed in the publication number CN117658023A or CN118723873A.

[0045] The link locking mechanism 50 includes a limiting member 51 and a limiting seat 52; the limiting member 51 is fixed on the swing rod 41, and one end of the limiting member 51 extends into the first space 521 of the limiting seat 52; the limiting member 51 moves in the first space 521 of the limiting seat 52 along with the swing rod 41; when the load wheel 32 is in a suspended state, the limiting member 51 abuts against the first side of the first space 521, and the limiting member 51 has a tendency to continue moving towards the first side. The abutting design between the limiting member 51 and the limiting seat 52 forms mechanical self-locking to prevent the load wheel 32 from accidentally falling when entering or exiting the tray 10; when the load wheel 32 is in a suspended state, the limiting member 51 has a tendency to continue moving towards the first side, preventing the load wheel 32 from falling under its own weight, and the locking structure is simple and reliable. In a specific embodiment, an extension of the rotating shaft of the swing rod 41 is directly used as the limiting member 51, and the limiting seat 52 includes an upper pressing plate and a lower pressing plate, and the space between the upper pressing plate and the lower pressing plate is the first space 521. When the load wheel assembly 30 is in a suspended state, the limiting member 51 abuts against the upper pressing plate from below and has a tendency to continue moving upward, thereby enabling mechanical self-locking and realizing the state locking of the load wheel assembly 30. In other specific embodiments, a limiting hole is formed on the limiting seat 52, and the shape of the limiting hole matches the moving path of the limiting member 51 therein, so that the corresponding function can be realized by the cooperation of the limiting hole and the limiting member 51.

[0046] The matching structure between the tray entry and exit mechanism and the tray 10

[0047] The guide wheel assembly 24 includes a plurality of lifting guide wheels 242, and the plurality of lifting guide wheels 242 are arranged along the stepped inclined plane for guiding. In a preferred embodiment, the guide wheel assembly 24 includes a second wheel frame 241, and the plurality of lifting guide wheels 242 are installed on the forklift fork 22 through the same second wheel frame 241. Through the installation of the second wheel frame 241, the installation complexity is reduced. The plurality of lifting guide wheels 242 are divided into two groups, and the two groups of lifting guide wheels 242 are respectively installed on both sides of the second wheel frame 241 and are arranged staggeredly. The staggered guide wheel group expands the contact coverage with the tray 10, adapts to different sizes of cross beams 11; avoids the failure of the single-side guide wheel when the forklift fork 22 is tilted, and improves the fault tolerance.

[0048] The load wheel 32 in a suspended state is located in front of the fork plate transition part 222, and its bottom exposes downward from the fork plate transition part 222. The fork plate transition part 222 is provided with a roller assembly 23, and the bottom of the roller assembly 23 protrudes from the bottom of the fork plate transition part 222. The roller assembly 23 is arranged slightly protruding below the bottom of the fork plate transition part 222 and will not be stuck by the bottom cross beam 11 of the pallet. Preferably, the roller assembly 23 is located in the middle or rear part of the fork plate transition part 222, so as to be able to cooperate with the load wheel 32 to support the front part of the forklift fork 22. Through the cooperation of the guide wheel assembly 24, the load wheel 32 and the roller assembly 23, the static friction during the process of the forklift fork 22 entering and exiting the tray 10 is converted into rolling friction, enabling it to smoothly enter and exit the tray 10 at a low speed.

[0049] Taking the process of entering the tray 10 as an example, as Figure 6-7 shown, during the process of the forklift forks 22 entering, when passing through the bottom steps of the tray 10, the guide wheel assembly 24 guides and cooperates to lift the forklift forks 22. During the entering process, the guide wheel assembly 24 first enters the tray 10, then the load wheels 32 take over and enter, followed by the roller assembly 23, so as to ensure that the forklift forks 22 always contact the bottom of the tray 10 with a relatively small frictional force (rolling friction). It should be emphasized that the key points of this solution are the shapes of the guide wheel assembly 24 and the fork plate transition part 222, the load wheels 32, and the mutual cooperation of the guide wheel assembly 24 to reduce the frictional force between the forklift forks 22 and the tray 10 when the forklift forks enter and exit the tray 10, so as to achieve no independent power source through the cooperation of a pure mechanical structure and adapt to the movement characteristics of AGV and other handling vehicles entering and exiting the tray 10 at a uniform and low speed.

[0050] According to the above settings, when the tray entry and exit mechanism enters and exits the tray, the friction between it and the tray is rolling friction, which is less than the static friction between the tray and the ground. Therefore, during the process of the forklift forks entering and exiting the tray, the tray can remain in place, and the situation where the forklift forks drive the tray to move will not occur, ensuring accurate position judgment of the AGV vehicle during the process of controlling the forklift forks to enter and exit the tray.

[0051] The roller assembly 23 in this embodiment is a wear-resistant roller, preferably including a pair of symmetrically arranged wear-resistant rollers. The roller assembly 23 in this embodiment is directly installed at the hinge point between the first wheel frame 31 and the link mechanism 40. The roller assembly 23 is directly arranged at the force-bearing hinge point, and there is no need to additionally set the installation structure of the roller assembly 23, and the structure is simple.

[0052] It should be noted that the tray entry and exit mechanism of this embodiment is also applicable to other trays with crossbeams at the bottom, such as a four-way pallet, and is not limited to the American standard pallet.

[0053] Handling robot

[0054] The handling robot includes a vehicle frame, and a forklift mechanism 20 is slidably lifted on the vehicle frame. The forklift mechanism 20 is driven to lift by a lifting drive device. The handling robot in this embodiment is an AGV forklift, which can automatically control the movement of the vehicle and the lifting of the forklift forks 22 without manual control. When it moves near the tray 10, it controls the forklift forks 22 to enter and exit the tray 10 at a uniform and low speed, and there is a need to handle an empty tray 10. The handling robot of this embodiment includes the above-mentioned tray entry and exit mechanism and is applicable to the American standard tray 10. Since the above-mentioned tray entry and exit mechanism can enable the forklift forks 22 to smoothly enter and exit the American standard tray 10 by using a pure mechanical structure, when used for an AGV forklift, there is no need to improve its control method, and the transformation of the existing vehicle is simple.

Claims

1. A pallet in and out mechanism for a transport vehicle, comprising: A fork mechanism, comprising a fork frame and a fork mounted on the fork frame; The load wheel assembly comprises a first wheel frame and a load wheel mounted on the first wheel frame, and the load wheel assembly is driven by a connecting rod mechanism to switch between a load-bearing state and a suspended state; It is characterized in that The front part of the fork is divided into a fork tip and a fork plate transition part. The fork tip is located at the front end of the fork, and its bottom surface is higher than the bottom surface of the fork plate transition part. A guide wheel assembly is provided at the connection between the fork tip and the fork plate transition part; the bottom of the fork plate transition part is a flat straight line structure, which is used to guide the contact between the bottom of the fork and the pallet; the load wheel in the suspended state is located in the front part of the fork plate transition part, and its bottom is exposed downward from the fork plate transition part; a roller assembly is provided in the middle of the fork plate transition part, and the bottom of the roller assembly protrudes from the bottom of the fork plate transition part; A link locking mechanism is also included for locking the load wheel assembly in a suspended state when the fork enters or exits the pallet.

2. The pallet inlet and outlet mechanism of a carrier vehicle according to claim 1, characterized in that, The connecting rod mechanism includes a rocker rod and a long connecting rod. The rocker rod is connected to the fork frame. One end of the rocker rod is connected to one end of the long connecting rod. The other end of the long connecting rod is connected to the first wheel frame of the load wheel assembly. The lifting of the fork mechanism drives the rocker rod and the long connecting rod to work in conjunction, driving the load wheel assembly to switch between a load-bearing state and a suspended state.

3. The tray access mechanism of a forklift according to claim 2, characterized in that, The connecting rod locking mechanism includes a limit member and a limit seat; the limit member is fixed on the rocker arm, and one end of the limit member extends into the first space of the limit seat; the limit member moves with the rocker arm in the first space of the limit seat; when the load wheel is suspended, the limit member abuts against the first side of the first space, and the limit member has a tendency to continue moving toward the first side.

4. The tray entry and exit mechanism of a carrier truck according to claim 1, characterized in that, The first wheel frame of the load wheel is connected to the fork at a first hinge point, the first wheel frame is hinged to the second hinge point of the connecting rod mechanism, and the roller assembly is arranged at the second hinge point.

5. The pallet entry and exit mechanism of a transporter according to claim 1, characterized in that, The guide wheel assembly includes a plurality of lifting guide wheels, and the plurality of lifting guide wheels are arranged along the step slope for guiding.

6. The tray access mechanism of a forklift according to claim 5, characterized in that, The guide wheel assembly comprises a second wheel frame, and a plurality of lifting guide wheels are mounted on the fork through the same second wheel frame.

7. The tray access mechanism of a handling vehicle according to claim 6, characterized in that, The plurality of lifting guide wheels are divided into two groups, and the two groups of lifting guide wheels are respectively installed on both sides of the second wheel frame and are staggered.

8. A carrier vehicle, characterized in that, The invention comprises a pallet entry and exit mechanism of a transport vehicle as claimed in any one of claims 1 to 7.

9. The forklift according to claim 8, characterized in that, The transport vehicle is an AGV vehicle.

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