Lifting mechanism overcoming contact impact of two connecting rods and control method

Abstract

This invention discloses a lifting mechanism and control method for overcoming the impact of two-link contact. The lifting mechanism includes an upper cover plate, a push block, two links, a base, and a scissor lift device. The lower end of the scissor lift device is connected to the base, and the upper end is connected to the upper cover plate. The two links consist of a first link, a second link, and a shock absorber. One end of the first link is connected to the push block, and the other end is hinged to one end of the second link. The other end of the second link is hinged to the scissor lift device. The shock absorber is fixedly installed on the first link. The push block is installed on a ball screw, which is driven by a motor. The control method includes the following steps: 1) Calculate the motor's initial limit speed v0 based on the shock absorber deformation S; 2) The motor runs at the initial speed. After detecting contact between the first and second links, the motor speed decreases to half of the initial speed; 3) When the motor current drops below the threshold current, the controller issues a command to increase the motor speed back to the initial speed v. The invention has a simple structure, and the shock absorber effectively reduces the additional impact from the flexible impact point. Combined with the control method, it can achieve greater lifting capacity without replacing the high-power motor.

Description

Technical Field

[0001] This invention relates to a lifting mechanism, specifically a lifting mechanism for an AGV (Automated Guided Vehicle), and more particularly, to a lifting mechanism that overcomes the impact of two-bar linkage contact. Background Technology

[0002] Currently, many production activities involve the handling of heavy goods, making AGV (Automated Guided Vehicle) forklifts particularly important in both production and daily life. Among these, the lifting capacity of an AGV forklift is a crucial technical indicator.

[0003] AGV forklifts mostly use scissor lift mechanisms, which require linkages to provide lifting power to the forks. Other related patents indicate that a two-bar linkage can provide greater lifting capacity to the forks. However, this two-bar linkage mechanism creates a flexible impact point at the moment of contact between link one and link two, which can cause the motor to overload at a certain instant, making it unable to lift the goods.

[0004] To address the aforementioned problems, this invention proposes a lifting structure and control method to overcome the contact impact of the two-linkage linkage. Summary of the Invention

[0005] The purpose of this invention is to solve the problem that the motor cannot lift goods due to the presence of flexible impact points in the existing two-bar linkage mechanism during the lifting process, and to propose a lifting mechanism and control method that overcomes the contact impact of the two-bar linkage.

[0006] The present invention achieves the above objectives through the following technical solutions:

[0007] A lifting mechanism for overcoming the impact of two-bar contact includes an upper cover plate, a push block, two connecting rods, a base, and a scissor lift device. The lower end of the scissor lift device is connected to the base, and the upper end is connected to the upper cover plate. The two connecting rods consist of a first connecting rod, a second connecting rod, and a shock absorber. One end of the first connecting rod is connected to the push block, and the other end is hinged to one end of the second connecting rod. The other end of the second connecting rod is hinged to the scissor lift device. The shock absorber is fixedly mounted on the first connecting rod. During the movement of the two connecting rods, the first connecting rod and the second connecting rod first rotate relative to each other. After the first connecting rod and the second connecting rod contact through the shock absorber, the two connecting rods act as a single unit, driving the scissor lift device to move and thus lift the upper cover plate. The push block is mounted on a ball screw, which is driven by a motor.

[0008] The scissor lift device consists of a first movable bracket and a second movable bracket, which are hinged together in the middle. The bottom of the first movable bracket is fixedly hinged to the chassis, and the top is in sliding contact with the upper cover plate. The bottom of the second movable bracket is in sliding contact with the base, and the top is fixedly hinged to the upper cover plate.

[0009] Specifically, it includes the following steps:

[0010] 1) Calculate the motor's limit initial operating speed v0 from the deformation amount S of the shock absorber

[0011]

[0012] Where L2 is the effective length of link two, L1 is the distance from the contact point of link two to the hinge point of link one and link two, and θ1 is the angle between link two and link one when link one and link two just come into contact;

[0013] 2) After detecting the contact of link one and link two, the motor reduces its speed to half of the initial speed:

[0014] The motor operates at the initial speed v (v < v0), monitors the motor current. When the current exceeds the threshold current, it is the contact moment of link one and link two. At this time, the controller issues an order for the motor to reduce its speed to After a time T, the motor responds to the order, and at this time the torque of the motor increases;

[0015] 3) When the motor current drops below the threshold current, the controller issues an order for the motor to increase its speed to the initial speed v.

[0016] The working principle of the present invention is: According to the structural simulation, the flexible impact point of the cover plate acceleration occurs when link one and link two are completely in contact. To smoothly pass through the flexible impact point, a shock absorber is added

[0017] to enable the AGV cart to smoothly lift and lower under the same load. By reducing the running speed of the push block at the moment of contact, the acceleration caused by the contact can be effectively reduced, thereby achieving the purpose of smooth lifting and lowering.

[0018] The beneficial effects of the present invention are as follows:

[0019] 1. The shock absorber can effectively reduce the additional load brought by the flexible impact point.

[0020] 2. Installing a high-strength shock absorber can increase the time from the start of contact to full contact between link one and link two. Through the increased time, the motor can be controlled in time and the speed can be reduced and the torque can be increased to pass through this flexible impact point.

[0021] 3. By using the relationship between the motor speed and torque and combining with an algorithm to control the motor, a greater bearing capacity can be obtained without replacing a high-power motor. Description of the Drawings

[0022] Figure 1 is a scissor lift device with two links adopted by the present invention.

[0023] Figure 2 This is the two-bar linkage structure of the present invention.

[0024] Figure 3 This is the physical model of the two-bar linkage structure of the present invention.

[0025] Figure 4 It is a control method and process for lifting mechanisms that overcomes the contact impact of the two linkages.

[0026] In the diagram, 1-upper cover plate, 2-push block, 3-connecting rod one, 4-connecting rod two, 5-base, 6-shock absorber Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings:

[0028] like Figures 1-2 As shown, a lifting mechanism for overcoming the impact of two-bar contact includes an upper cover plate 1, a push block 2, two connecting rods, a base 5, and a scissor lift device. The lower end of the scissor lift device is connected to the base 5, and the upper end is connected to the upper cover plate 1. The two connecting rods consist of a first connecting rod 3, a second connecting rod 4, and a shock absorber 6. One end of the first connecting rod 3 is connected to the push block 2, and the other end is hinged to one end of the second connecting rod 4. The other end of the second connecting rod 4 is hinged to the scissor lift device. The shock absorber 6 is fixedly installed on the first connecting rod 3. During the movement of the two connecting rods, the first connecting rod 3 and the second connecting rod 4 first rotate relative to each other. After the first connecting rod 3 and the second connecting rod 4 come into contact through the shock absorber 6, the two connecting rods become a single unit, driving the scissor lift device to move and thus lift the upper cover plate 1.

[0029] The push block 2 is mounted on the ball screw, which is driven by a motor;

[0030] The scissor lift device consists of a first movable bracket and a second movable bracket. The first movable bracket and the second movable bracket are hinged in the middle. The bottom of the first movable bracket is fixedly hinged to the chassis, and the top is in sliding contact with the upper cover plate 1. The bottom of the second movable bracket is in sliding contact with the base 5, and the top is fixedly hinged to the upper cover plate 1.

[0031] like Figure 3 The diagram shows the motion model of a two-bar linkage. Since the motor has a response time T, the deformation S of the damper 6 is completely consumed within this time T under extreme conditions. Because time T is very short, it is assumed that the angular velocity ω at the contact point of link 2 is constant. Therefore:

[0032] ………………(1)

[0033] ………………… (2)

[0034] ……………… (3)

[0035] … (4)

[0036] …… (5)

[0037] …… … (6)

[0038] Where L1 is the distance from the contact point of link 2 4 to the hinge point of link 1 3 and link 2 4, θ is the angle between link 1 3 and link 2 4 when they are in full contact, θ1 is the angle between link 1 3 and link 2 4 when they just make contact, X is the distance link 1 3 travels in time T, X2 is the equivalent length of link 2 4 when link 1 3 and link 2 4 just make contact, and X3 is the equivalent length of link 2 4 when link 1 3 and link 2 4 are in full contact.

[0039] By solving the simultaneous equations, we can obtain the maximum initial operating speed v0 of the motor.

[0040]

[0041] A lifting mechanism and control method for overcoming the contact impact of a two-linkage linkage specifically includes the following steps:

[0042] 1) Calculate the initial running speed v0 of the motor from the deformation S of the shock absorber 6.

[0043]

[0044] Where L2 is the effective length of link 2 4, L1 is the distance from the contact point of link 2 4 to the hinge point of link 1 3 and link 2 4, and θ1 is the angle between link 2 4 and link 1 3 when link 1 3 and link 2 4 just come into contact.

[0045] 2) After contact is detected between link 1 (3) and link 2 (4), the motor speed decreases to half of its initial speed:

[0046] The motor runs at an initial speed v0, and the motor current is monitored. When the current exceeds the threshold current, it is the moment of contact between link 3 and link 4. At this time, the controller issues a deceleration signal to reduce the motor speed. The motor responds to the command after a time T, at which point the motor torque increases.

[0047] 3) When the motor current drops below the threshold current, the controller issues a command to increase the motor speed to the initial speed v0.

[0048] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the technical solutions of the present invention. Any technical solution that can be implemented based on the above embodiments without creative effort should be considered to fall within the scope of protection of the patent of the present invention.

Claims

1. A lifting mechanism control method for overcoming the contact impact of a two-bar linkage, comprising a lifting mechanism for overcoming the contact impact of a two-bar linkage, characterized in that: The device includes an upper cover plate (1), a push block (2), a two-link system, a base (5), and a scissor lift device. The lower end of the scissor lift device is connected to the base (5), and the upper end is connected to the upper cover plate (1). The two-link system consists of a first link (3), a second link (4), and a shock absorber (6). One end of the first link (3) is connected to the push block (2), and the other end is hinged to one end of the second link (4). The other end of the second link (4) is hinged to the scissor lift device. The shock absorber (6) is fixedly installed on the first link (3). During the movement of the two-link system, the first link (3) and the second link (4) first rotate relative to each other. After the first link (3) and the second link (4) come into contact through the shock absorber (6), the two-link system becomes a whole, driving the scissor lift device to move and thus lift the upper cover plate (1). It includes the following steps: 1) Calculate the initial running speed v0 of the motor from the deformation S of the shock absorber (6). Where L2 is the effective length of link 2 (4), L1 is the distance from the contact point of link 2 (4) to the hinge point of link 1 (3) and link 2 (4), θ1 is the angle between link 2 (4) and link 1 (3) when link 1 (3) and link 2 (4) just come into contact, and T is the motor response time; 2) After contact is detected between link one (3) and link two (4), the motor speed is reduced to half of its initial speed: The motor runs at an initial speed v (v < v0), monitors the motor current, and when the current exceeds the threshold current, it is the contact moment of the first connecting rod (3) and the second connecting rod (4). At this time, the controller issues a command to reduce the speed of the motor to After a time T, the motor responds to the command, and at this time the torque of the motor increases; 3) When the motor current drops below the threshold current, the controller issues a command to increase the motor speed to the initial speed v.

2. The lifting mechanism control method for overcoming contact impact of two linkages according to claim 1, characterized in that: The push block (2) is mounted on the ball screw, which is driven by a motor.

3. The lifting mechanism control method for overcoming contact impact of a two-linkage linkage according to claim 1, characterized in that: The scissor lift device consists of a first movable bracket and a second movable bracket. The first movable bracket and the second movable bracket are hinged in the middle. The bottom of the first movable bracket is fixedly hinged to the chassis, and the top is in sliding contact with the upper cover plate (1). The bottom of the second movable bracket is in sliding contact with the base (5), and the top is fixedly hinged to the upper cover plate (1).

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