AGV pallet truck and hydraulic system

Abstract

The AGV pallet truck comprises a truck body and a pallet fork frame assembly arranged on the truck body, the pallet fork frame assembly comprises a pallet fork body slidably connected with the truck body and a pallet fork body extending to the outside of the truck body, and a middle supporting wheel assembly is arranged at the lower end of the pallet fork body; a bearing wheel assembly is arranged at one end, far away from the truck body, of the pallet fork body, and the bearing wheel assembly is rotationally connected with the pallet fork body through a wheel carrier; a main lifting part and an auxiliary lifting part are arranged between the fork arm carrier assembly and the vehicle body, and a driving transmission assembly is arranged between the main lifting part and the wheel carrier and between the auxiliary lifting part and the wheel carrier. When a tray shaped like a Chinese character'tian 'or goods with bottom stop levers are carried, the weighing wheel at the front end of the vehicle needs to be folded on the inner side of the pallet fork, then the goods are forked, and then the weighing wheel is put down and touches the ground, so that different pallet and goods fork hole styles can be adapted, and the universality is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of pallet trucks, in particular to an AGV pallet truck and a hydraulic system. Background Art

[0002] AGV pallet truck is a kind of forklift handling robot. The existing AGV pallet truck mainly works by inserting the fork into the bottom hole of the pallet, lifting the goods, and then transporting the pallet and the goods, thereby realizing automatic forking and transporting of the pallet and the goods.

[0003] Existing AGV pallet transporters can generally only transport Sichuan-shaped pallets, iron pallets or goods with fork holes, and are not suitable for transporting Tian-shaped pallets or goods with bottom bars. If you forcibly fork a Tian-shaped pallet truck or goods with a bottom bar, the vehicle's load-bearing wheels will interfere with the bottom edge of the Tian-shaped pallet or the bottom bar of the goods when rolling forward, and you need to rely on the load-bearing wheels to roll over the bottom edge of the Tian-shaped pallet or the bottom bar of the goods. When the load-bearing wheels roll over the bottom edge of the Tian-shaped pallet or the bottom bar of the goods, a large impact force is generated, which not only causes damage to the pallet, but also greatly reduces the service life of the pallet; and because the load-bearing wheels are usually made of polyurethane materials, they are prone to cracking and damage after being subjected to a large impact force, affecting the normal use of the vehicle; more importantly, for AGV vehicles, when the load-bearing wheels roll over the bottom edge of the Tian-shaped pallet or the bottom bar of the goods, a large impact force will suddenly be generated, causing the vehicle posture to shift, resulting in uncontrollable changes in the vehicle positioning and navigation, thereby affecting the AGV vehicle's automatic forking and transport of goods. Summary of the invention

[0004] The object of the present invention is to provide an AGV pallet truck and a hydraulic system to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] An AGV pallet transporter comprises a vehicle body and a fork frame assembly arranged on the vehicle body, wherein the fork frame assembly comprises a fork main body slidably connected to the vehicle body and a fork body extending outside the vehicle body, an intermediate supporting wheel assembly is arranged at the lower end of the fork main body, a load-bearing wheel assembly is arranged at one end of the fork body away from the vehicle body, and the load-bearing wheel assembly is rotatably connected to the fork body through a wheel frame;

[0007] A main lifting part for driving the wheel frame to rotate in a direction away from the fork body and a secondary lifting part for driving the wheel frame to rotate in a direction close to the fork body are provided between the fork frame assembly and the vehicle body.

[0008] A driving transmission assembly is provided between the main lifting part, the auxiliary lifting part and the wheel frame.

[0009] As a further solution of the present invention: one end of the wheel frame is rotatably connected to a load-bearing wheel assembly, the other end of the wheel frame is rotatably connected to the fork body through a pin shaft, and the drive connection assembly is rotatably connected to the middle part of the wheel frame to drive the wheel frame to rotate around the pin shaft.

[0010] As a further solution of the present invention: the drive transmission assembly includes a push-pull rod assembly rotatably connected to the middle part of the wheel frame, the end of the push-pull rod assembly away from the wheel frame is rotatably connected to a small swing arm assembly, the middle part of the small swing arm assembly is rotatably connected to the bottom of the fork frame assembly, and the end of the small swing arm assembly away from the push-pull rod assembly is movably connected to a small roller limiting bracket.

[0011] As a further solution of the present invention: a waist-shaped hole is provided at the lower part of the small roller limit bracket, a rotating shaft is provided on the small rotating arm assembly, the rotating shaft is movably connected in the waist-shaped hole, an auxiliary lifting slide assembly is slidably connected up and down on the vehicle body, and the small roller limit bracket is fixedly connected to the lower end of the auxiliary lifting slide assembly.

[0012] As a further solution of the present invention: the main lifting part includes a main lifting cylinder, one end of the main lifting cylinder is connected to the fork frame assembly and the other end is connected to the vehicle body, and both sides of the fork frame assembly are connected to the vehicle body channel steel in an up and down sliding manner through a channel steel roller assembly.

[0013] As a further solution of the present invention: the auxiliary lifting part includes an auxiliary lifting cylinder, the upper end of the auxiliary lifting cylinder is connected to the vehicle body, the lower end of the auxiliary lifting cylinder is connected to the auxiliary lifting slide assembly, and the two sides of the auxiliary lifting slide assembly are connected to the vehicle body channel steel through auxiliary channel steel rollers for upward and downward sliding.

[0014] As a further solution of the present invention: the auxiliary lifting cylinder is fixedly connected to the vehicle body through an upper fixing seat of the cylinder, and the upper fixing seat of the cylinder is adjustably connected to the vehicle body through an upper adjusting bolt and a lower adjusting bolt, the lower end of the auxiliary lifting cylinder is connected to the auxiliary lifting slide assembly through a cylinder fixed shaft, a fixed shaft locking plate is provided on the cylinder fixed shaft, a proximity sensor is provided at a position of the auxiliary lifting slide assembly close to the vehicle body channel steel, the proximity sensor is fixedly connected to the auxiliary lifting slide assembly through a proximity sensor fixing bent plate, and an induction bent plate cooperating with the proximity sensor is provided on the vehicle body channel steel.

[0015] A hydraulic system for an AGV pallet truck is characterized in that it comprises an oil supply unit, wherein the oil supply unit is connected to a main oil supply system and an auxiliary oil supply system, wherein the main oil supply system is connected to the main lifting cylinder, and the auxiliary oil supply system is connected to the auxiliary lifting cylinder.

[0016] As a further solution of the present invention: The oil supply part includes a gear pump and a fuel tank communicated with the oil inlet of the gear pump. A filter is arranged at the oil inlet of the gear pump. The power end of the gear pump is connected with an oil pump motor. The output end of the gear pump is connected with an oil supply pipe through a check valve, and the output end of the gear pump is connected with a relief valve.

[0017] As a further solution of the present invention: The main oil supply system includes a two-way check valve connected with the oil supply pipe of the oil supply part. The oil outlet end of the two-way check valve is communicated with the main hoisting cylinder. The main hoisting cylinder is connected in parallel with a driving increasing cylinder. The main hoisting cylinder is connected with an oil return pipeline, and a descending proportional solenoid valve and a pressure compensation valve are arranged on the oil return pipeline;

[0018] The auxiliary oil supply system includes two auxiliary hoisting cylinders and a balance valve connected with the two auxiliary hoisting cylinders. The balance valve is connected with a reversing valve, and the reversing valve is communicated with the oil supply pipe of the oil supply part.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] 1. When the present application transports a Sichuan-shaped pallet or goods with a fork hole channel, it can directly insert the fork; when transporting a Tian-shaped pallet or goods with a bottom baffle rod, it is necessary to first retract the weighing wheels at the front end of the vehicle inside the fork, then fork the goods, and then put the weighing wheels down to the ground. It can cope with different pallet and goods fork hole styles, improving the general performance.

[0021] 2. By arranging high-strength support rollers in the middle position in the present application, when the weighing wheels at the front end of the fork are retracted inside the fork, the support rollers and the drive wheels support the stability of the whole vehicle.

[0022] 3. The whole vehicle hydraulic system of the present application is divided into two subsystems, namely the main hoisting and the auxiliary hoisting. In this way, there is no need to separately design many independent hydraulic systems for different requirements of the main hoisting and the auxiliary hoisting, or for different types of pallets. It not only occupies a large amount of space in the vehicle body, but also causes waste of costs. In addition, a large number of independent hydraulic systems will cause logical crossover of the vehicle and it is difficult to ensure continuous actions. Brief Description of the Drawings

[0023] Figure 1 、 Figure 2 is a schematic structural diagram of the main hoisting mechanism of this embodiment;

[0024] Figure 3 is a schematic structural diagram of the auxiliary hoisting mechanism of this embodiment;

[0025] Figure 4 is a schematic diagram of the state where the load-bearing wheels are retracted in this embodiment;

[0026] Figure 5 This is a schematic diagram of the load-bearing wheel on the ground state of this embodiment;

[0027] Figure 6 , Figure 7 This is a schematic diagram of the fork entry status of the field-shaped pallet;

[0028] Figure 8 This is a schematic diagram of the hydraulic system principle of the whole vehicle in this embodiment.

[0029] In the figure: 03-Tianzi pallet, 11-load-bearing wheel assembly, 12-wheel frame, 13-push-pull rod assembly, 14-small rotating arm assembly, 15-main lifting cylinder, 16-fork frame assembly, 17-channel steel roller assembly, 18-pin shaft, 19-small roller limit bracket, 20-middle support wheel assembly, 21-secondary channel steel roller, 22-cylinder fixed shaft, 23-fixed shaft lock plate, 24-secondary lifting slide assembly, 25-proximity sensor, 26 -Sensor fixing bent plate, 27-induction bent plate, 28-auxiliary lifting cylinder, 29-lower adjusting bolt, 30-cylinder upper fixing seat, 31-upper adjusting bolt, 32-descending proportional solenoid valve, 33-two-way check valve, 34-pressure compensation valve, 35-one-way valve, 36-mailbox, 37-oil pump motor, 38-gear pump, 39-filter, 40-overflow valve, 41-reversing valve, 42-balancing valve, 43-drive additional cylinder. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] See also Figure 1-7 In an embodiment of the present invention, an AGV pallet transporter includes a vehicle body and a fork frame assembly 16 arranged on the vehicle body, the fork frame assembly 16 includes a fork body slidably connected to the vehicle body and a fork body extending outside the vehicle body, an intermediate supporting wheel assembly 20 is provided at the lower end of the fork body, a load-bearing wheel assembly 11 is provided at one end of the fork body away from the vehicle body, the load-bearing wheel assembly 11 is rotatably connected to the fork body through a wheel frame 12, one end of the wheel frame 12 is rotatably connected to the load-bearing wheel assembly 11, the other end of the wheel frame 12 is rotatably connected to the fork body through a pin shaft 18, and the drive connection assembly is rotatably connected to the middle part of the wheel frame 12 for driving the wheel frame 12 to rotate around the pin shaft 18;

[0032] A main lifting part for driving the wheel frame 12 to rotate away from the fork body and a secondary lifting part for driving the wheel frame 12 to rotate toward the fork body are provided between the fork frame assembly 16 and the vehicle body.

[0033] A driving transmission assembly is provided between the main lifting part, the auxiliary lifting part and the wheel frame 12. The driving transmission assembly includes a push-pull rod assembly 13 rotatably connected to the middle part of the wheel frame 12, and the end of the push-pull rod assembly 13 away from the wheel frame 12 is rotatably connected to a small rotating arm assembly 14, and the middle part of the small rotating arm assembly 14 is rotatably connected to the bottom of the fork frame assembly 16, and the end of the small rotating arm assembly 14 away from the push-pull rod assembly 13 is movably connected to a small roller limiting bracket 19, and a waist-shaped hole is provided at the lower part of the small roller limiting bracket 19, and a rotating shaft is provided on the small rotating arm assembly 14, and the rotating shaft is movably connected in the waist-shaped hole, and an auxiliary lifting slide assembly 24 is slidably connected to the vehicle body up and down, and the small roller limiting bracket 19 is fixedly connected to the lower end of the auxiliary lifting slide assembly 24.

[0034] The main lifting part is an eight-link mechanism and includes a main lifting cylinder 15, one end of which is connected to the fork frame assembly 16 and the other end is connected to the vehicle body. Both sides of the fork frame assembly 16 are connected to the vehicle body channel steel through the channel steel roller assembly 17 for vertical sliding connection.

[0035] When installing the main lifting part, first install the load-bearing wheel assembly 11 and the lower hinge hole of the wheel frame 12. Then use the pin 18 to assemble the upper hinge hole of the wheel frame 12 and the mounting hole at one end of the push-pull rod assembly 13. Then use the pin 18 to assemble the mounting hole at the other end of the push-pull rod assembly 13 and the middle hinge hole of the small rotating arm assembly 14. Then put the roller of the small rotating arm assembly 14 in the waist-shaped slot hole of the small roller limiting bracket 19, and then use the pin 18 to assemble the roller end of the small rotating arm assembly 14 and the small roller limiting bracket 19 together to form a prefabricated component of the push-pull rod assembly.

[0036] Then, the push-pull rod assembly prefabricated components are assembled with the fork frame assembly 16. First, the hinge hole in the middle of the wheel frame 12 is connected to the front end fixing hole of the fork frame assembly 16 with the pin 18; the upper hinge hole of the small rotating arm assembly 14 is connected to the rear end fixing hole of the fork frame assembly 16 with the pin 18.

[0037] Finally, fix the channel steel roller assembly 17 to the fork frame assembly 16, fix the intermediate support wheel assembly 20 to the side of the fork frame assembly 16 with bolts, and fix the upper end of the main lifting cylinder 15 to the upper end plate of the fork frame assembly 16 to complete the assembly process of the main lifting part.

[0038] When the main lifting part is working, the cylinder rod of the main lifting cylinder 15 extends. Since the upper end of the main lifting cylinder 15 is fixed to the upper end plate of the fork frame assembly 16, the cylinder rod of the main lifting cylinder 15 pushes the fork frame assembly 16 to move. Since the channel steel roller assemblies 17 installed on both sides of the fork frame assembly 16 are constrained to move in the frame channel steel, the channel steel roller assembly 17 can only roll up and down along the frame channel steel, so that the fork frame assembly 16 moves upward. The small rotating arm assembly 14 hingedly installed with the fork frame assembly 16 rotates. The roller of the small rotating arm assembly 14 rolls horizontally forward along the upper edge of the waist-shaped groove of the small roller limit bracket 19. At the same time, the push-pull rod assembly 13 hingedly mounted with the small rotating arm assembly 14 pushes the wheel frame 12 forward to rotate in the counterclockwise direction, and because the load-bearing wheel assembly 11 hingedly mounted with the wheel frame 12 is always tangentially fitted with the ground, the downward movement trend of the load-bearing wheel assembly 11 is restricted, so that the load-bearing wheels of the load-bearing wheel assembly 11 can only roll horizontally backward along the ground, and finally complete the lifting process of the main lifting mechanism. Otherwise, the main lifting mechanism will descend.

[0039] During the main lifting process, the load-bearing wheel assembly 11 is always tangent to the ground, and together with the driving wheel, it supports the weight of the vehicle, the pallet, and the cargo. The intermediate support wheel assembly 20 will complete the lifting and lowering action together with the fork frame assembly 16. When the fork frame assembly 16 is lowered to the lowest position, the rollers of the intermediate support wheel assembly 20 will touch the ground. When encountering a "C"-shaped pallet or cargo with a fork hole channel, the fork is directly inserted into the fork opening, and then only the main lifting mechanism needs to be lifted to complete the pallet and cargo lifting process.

[0040] The auxiliary lifting part includes an auxiliary lifting cylinder 28, the upper end of which is connected to the vehicle body, the lower end of which is connected to the auxiliary lifting slide assembly 24, and the two sides of the auxiliary lifting slide assembly 24 are slidably connected to the vehicle body channel steel through auxiliary channel steel rollers 21. The auxiliary lifting cylinder 28 is fixedly connected to the vehicle body through an upper cylinder fixing seat 30, and the upper cylinder fixing seat 30 is adjustably connected to the vehicle body through an upper adjusting bolt 31 and a lower adjusting bolt 29. The lower end of the auxiliary lifting cylinder 28 is connected to the auxiliary lifting slide assembly through a cylinder fixed shaft 22, and a fixed shaft locking plate 23 is provided on the cylinder fixed shaft 22. A proximity sensor 25 is provided at a position of the auxiliary lifting slide assembly 24 near the vehicle body channel steel, and the proximity sensor 25 is fixedly connected to the auxiliary lifting slide assembly 24 through a proximity sensor fixed bent plate 26, and an induction bent plate 27 cooperating with the proximity sensor 25 is provided on the vehicle body channel steel.

[0041] When the auxiliary lifting part belongs to the seven-link mechanism, when installing, fix the auxiliary channel steel roller 21 on both sides of the auxiliary lifting carriage assembly 24, and then assemble them between the channel steels on the left and right sides respectively. Connect the small roller limit bracket 19 to the auxiliary lifting carriage assembly 24 with bolts. Then use the cylinder fixed shaft 22 and the fixed shaft locking plate 23 to hinge the lower end of the auxiliary lifting cylinder 28 with the auxiliary lifting carriage assembly 24. Fix the upper fixing seat 30 of the cylinder to the vehicle body with bolts, and then use the cylinder fixed shaft 22 and the fixed shaft locking plate 23 to hinge the upper end of the auxiliary lifting cylinder 28 with the upper fixing seat 30 of the cylinder. Use screws to fix the sensor fixed bent plate 26 and the induction bent plate 27 to the auxiliary lifting carriage assembly 24 and the vehicle body channel steel respectively, install the proximity sensor 25 on the sensor fixed bent plate 26, and adjust the sensing distance. Finally, the lower adjusting bolt 29 and the upper adjusting bolt 31 are used to adjust the upper and lower heights of the fixing seat 30 on the oil cylinder, thereby ensuring that the rollers of the load-bearing wheel assembly 11 are in contact with the ground, thus completing the assembly process of the auxiliary lifting part.

[0042] When the auxiliary lifting part is working, after the oil enters the lower oil port of the auxiliary lifting cylinder 28, the cylinder rod retracts. Since the lower end of the auxiliary lifting cylinder 28 is fixed to the auxiliary lifting slide assembly 24, the cylinder rod of the auxiliary lifting cylinder 28 pulls the auxiliary lifting slide assembly 24. In addition, since the auxiliary channel steel roller 21 installed on the auxiliary lifting slide assembly 24 is constrained to move in the channel steel of the frame, the auxiliary channel steel roller 21 can only roll up and down vertically along the channel steel. As a result, the auxiliary lifting slide assembly 24 moves upward. The small roller limit bracket 19 fixed to the auxiliary lifting slide assembly 24 also moves upward. Since the roller of the small swing arm assembly 14 is installed in the waist-shaped hole of the small roller limit bracket 19, it will roll forward horizontally along the lower edge of the waist-shaped hole while moving vertically upward along with the roller limit bracket 19. The small rotating arm assembly 14 is driven to rotate counterclockwise around the fixed axis, and the push-pull rod assembly 13 hingedly mounted to the small rotating arm assembly 14 will be pulled backward. The wheel frame 12 hingedly mounted to the other end of the push-pull rod assembly 13 is pulled to rotate clockwise around the fixed axis. The load-bearing wheel assembly 11 hingedly mounted to the wheel frame 12 will be lifted until the proximity sensor 25 on the upper side senses the sensing bend plate 27 on the upper side, and the pump station motor stops running. At this time, the upper end surface of the load-bearing wheel assembly 11 fits exactly with the fork surface, so that the load-bearing wheel is retracted to the inner side of the fork, completing the entire lifting process of the auxiliary lifting part. The specific status is shown in FIG. Figure 4 shown.

[0043] After oil is supplied to the oil port of the auxiliary lifting cylinder 28, the cylinder rod extends. The cylinder rod of the auxiliary lifting cylinder 28 pushes the auxiliary lifting slide assembly 24 and the small roller limit bracket 19 to move downward. The roller of the small rotating arm assembly 14 will roll horizontally backward along the upper edge of the waist-shaped hole of the small roller limit bracket 19, and move vertically downward along with the roller limit bracket 19. The small rotating arm assembly 14 is driven to rotate clockwise around the fixed axis, and the push-pull rod assembly 13 hingedly mounted to the small rotating arm assembly 14 will be pushed forward. Pull the wheel frame 12 hingedly mounted to the other end of the push-pull rod assembly 13 to rotate counterclockwise around the fixed axis. The load-bearing wheel assembly 11 hingedly mounted on the wheel frame 12 will fall down until the proximity sensor 25 on the lower side senses the sensing bent plate 27 at the lower end, and the pump station motor stops running. At this time, the roller of the load-bearing wheel assembly 11 just fits the ground, completing the entire process of the auxiliary lifting part descending. The specific status is shown in Figure 5 shown.

[0044] After the cylinder rod of the auxiliary lifting cylinder 28 is retracted, the side rollers of the auxiliary lifting carriage assembly 24 are confined to the inner side of the special channel steel and move vertically. The rollers of the small swivel arm assembly 14 are confined in the closed waist-shaped hole. Since they can roll horizontally along the upper and lower edges of the waist-shaped hole, they can also move vertically with the auxiliary lifting carriage assembly 24. In this way, the mechanism can allow the small swivel arm assembly 14 to rotate to a larger angle to the maximum extent in a small space. Moreover, such an invention can also eliminate the problem that the final roller and the limit plate cannot be effectively fitted due to production errors. During the movement process, the push-pull rod assembly 13 generates a pulling force or a thrust on the wheel frame 12, causing the wheel frame 12 to rotate. Although the wheel frame 12 is a laborious lever, it can enable the load-bearing wheel assembly 11 to obtain a larger range of motion when the wheel frame 12 has a smaller activity space and a smaller rotation angle. The load-bearing wheel assembly 11 can be completely retracted inside the fork, and the minimum fork height of the fork can be reduced, ensuring that the entire vehicle can better adapt to pallets or goods of different heights.

[0045] The conditions for the load-bearing wheel assembly 11 to be retracted into place are triggered. First, when the proximity sensor 25 on the upper side senses the induction bend plate 27 at the upper end, the pump station motor stops rotating, and the pump station will immediately stop supplying oil to the auxiliary lifting cylinder 28, so that the cylinder rod of the auxiliary lifting cylinder 28 will stop retracting. Second, mechanical limit support plates are designed at both ends of the wheel frame clamps on both sides of the load-bearing wheel assembly 11 in the length direction, so that the length of the wheel frame clamp will be greater than the length of the opening at the front end of the fork. When the load-bearing wheel assembly 11 is retracted into place, the upper ends of the wheel frame clamps on both sides of the load-bearing wheel assembly 11 fit with the fork surface and prevent the load-bearing wheel assembly 11 from exceeding the upper surface of the fork. Moreover, the upper ends of the wheel frame clamps on both sides of the load-bearing wheel assembly 11 are designed with inclined surfaces of the same angle as the fork head of the cargo fork, so that the front and rear rollers of the load-bearing wheel assembly 11 are tightly attached to the lower surface of the cargo fork, and the front and rear rollers will not rotate around the axis due to their own weight, thereby affecting the minimum gap between the cargo fork frame assembly 16 and the ground, and affecting the avoidance gap required for the vehicle to fork the pallet in the later stage. When the load-bearing wheel assembly 11 is retracted to the inner side of the cargo fork, the vehicle itself is mainly supported by the middle support wheel assembly 20 and the driving wheel, and an effective gap is formed between the lower end surface of the cargo fork and the ground, so that when forking a field-shaped pallet or cargo with a bottom stop bar, the interference of the pallet bottom plate or the bottom stop bar can be avoided.

[0046] When the fork is in place, the arrival signal is triggered, the cylinder rod of the auxiliary lifting cylinder 28 extends, the auxiliary lifting mechanism is lowered, and finally the load-bearing wheel assembly 11 touches the ground. At this time, the weight of the vehicle is supported by the load-bearing wheel assembly 11 and the driving wheel. For a field-shaped pallet or cargo, the load-bearing wheel assembly 11 directly exceeds the other end of the pallet and touches the ground, or the load-bearing wheel assembly 11 touches the ground just at the hole of the pallet bottom plate.

[0047] During the lifting and lowering process of the auxiliary lifting part, the rollers of the intermediate support wheel assembly 20 are always on the ground. After the cylinder rod of the auxiliary lifting oil cylinder 28 is retracted or extended, the components of the connecting rod mechanism complete the movement logic between the components in the form of a rotating pair and a moving pair, and finally the load-bearing wheel assembly 11 is retracted or lowered to the ground, so that the vehicle can reach the conditions for forking and carrying forked pallet trucks or goods with bottom gear bars.

[0048] When the forklift truck in this embodiment forks a cross-shaped pallet or goods with a bottom bar, first, the weighing wheels at the front end of the forklift forks are retracted inside the forklift forks. In this way, there is a large clearance between the lower section of the forklift forks and the ground, which can completely avoid the bottom plate of the cross-shaped pallet and can also completely avoid the bottom bar of the goods. Instead of the existing general pallet AGV vehicles, which rely on increasing the diameter of the weighing wheels and翻越 the bottom plate of the cross-shaped pallet or the bottom bar of the goods by means of the rollers to fork the forklift forks into the pallet or the goods. Therefore, there will be no sudden impact between the rollers and the bottom plate of the pallet or the lower bar of the goods, nor will it cause problems such as pallet damage and roller cracking, nor will there be problems such as the unstable attitude of the whole vehicle affecting the navigation and positioning accuracy. Moreover, with the structure of the present invention, after the forklift forks are inserted, the load-bearing wheels at the front end of the forklift forks can be lowered to the ground again. It is still possible to use the vehicle load-bearing wheels and drive wheels to support the weight of the whole vehicle and the goods. With such an invention of the function, it will not reduce the vehicle's load-carrying capacity, maintain the original excellent performance characteristics of the vehicle, and can be compatible with the handling of different types of pallets or goods.

[0049] And a high-strength support roller is arranged at the middle position. When the weighing wheels at the front end of the forklift forks are retracted inside the forklift forks, the support roller and the drive wheel support the stability of the whole vehicle. So that the vehicle can still walk smoothly when there is no support of the load-bearing wheels, the vehicle does not nod when forking, the vehicle attitude does not tilt, and the vehicle can fork smoothly. When the forklift forks are lifted, the support roller also rises. In this way, when the vehicle is lifted and transported, it does not affect the ground clearance and does not affect the vehicle's ability to cross pits and climb slopes.

[0050] Please refer to Figure 8 , a hydraulic system of an AGV pallet forklift truck, which is characterized in that it includes an oil supply part, the oil supply part is connected with a main oil supply system and a secondary oil supply system, the main oil supply system is communicated with the main lifting cylinder 15, and the secondary oil supply system is communicated with the secondary lifting cylinder 28.

[0051] The oil supply part includes a gear pump 38 and a fuel tank 36 communicated with the oil inlet of the gear pump 38. A filter 39 is arranged at the oil inlet of the gear pump 38. The power end of the gear pump 38 is connected with an oil pump motor 37. The output end of the gear pump 38 is connected with an oil supply pipe through a check valve 35, and the output end of the gear pump 38 is connected with a relief valve 40.

[0052] The main oil supply system includes a two-way check valve 33 connected with the oil supply pipe of the oil supply part. The oil outlet end of the two-way check valve 33 is communicated with the main lifting cylinder 15. The main lifting cylinder 15 is connected in parallel with a drive increase cylinder 43. The main lifting cylinder 15 is connected with an oil return pipeline, and a descending proportional solenoid valve 32 and a pressure compensation valve 34 are arranged on the oil return pipeline;

[0053] The auxiliary oil supply system includes two auxiliary lifting cylinders 28 and a balance valve 42 connected to the two auxiliary lifting cylinders. The balance valve 42 is connected to a reversing valve 41, and the reversing valve 41 is communicated with the oil supply pipe of the oil supply part.

[0054] According to different pallet usage scenarios, the hydraulic system of this embodiment automatically sends a demand signal to the main controller, and the main controller sends different control signals to the hydraulic control components to control the start and stop of the pump control motor and the action response of different sequence valve blocks, thereby controlling the main lifting part and the auxiliary lifting part.

[0055] Main lifting system:

[0056] When it is recognized that a tray of the channel type or a cargo with a fork hole channel is to be picked up, after a pick-up instruction is issued, the main controller will automatically determine that only the main lifting action is required to meet the requirement of lifting the cargo, providing conditions for subsequent handling. In the process of the AGV vehicle of the present invention picking up a tray of the channel type or a cargo with a fork hole channel, actually, first, the hydraulic system - the main lifting controls the extension or contraction of the cylinder rod of the main lifting cylinder 15, and then through the working mechanism of the main lifting part, the fork is lifted and lowered to complete the lifting and lowering of the tray or cargo on the fork. The structural characteristics and working mechanism of the main lifting part have been clearly explained above and will not be described here again. Now, a specific analysis of the hydraulic system - the main lifting is as follows.

[0057] When the AGV vehicle sends a lifting request for the main lifting mechanism, the controller will first send a signal to energize the electromagnetic coil m4, so that the right position of the two-way check valve 33 is connected to the pipeline. At the same time, power is supplied to the receiver of the oil pump motor 37, so that the oil pump motor 37 starts to rotate, driving the fixed-displacement gear pump 38 to work and draw the hydraulic oil from the fuel tank 36. The hydraulic oil in the fuel tank is first filtered by the filter 39, and then pressurized by the fixed-displacement gear pump 38. After the pressurized hydraulic oil pushes open the valve core of the one-way valve 35, it passes through the two-way check valve 33 with the right position already connected. Part of the hydraulic oil enters the cylinder barrel of the main lifting cylinder 15, pushing the extension of the cylinder rod. The extended cylinder rod realizes the lifting of the cargo through the working mechanism of the main lifting part. Another part of the hydraulic oil enters the cylinder barrel of the driving boost cylinder 43, pushing the extension of the cylinder rod, squeezing the compression spring at the top of the cylinder rod, generating an additional elastic force, increasing the positive pressure of the driving wheel, and increasing the frictional resistance between the driving wheel and the ground to prevent the driving wheel from slipping on the ground.

[0058] On the contrary, after the AGV vehicle issues a request for lowering the main lifting unit, the controller will first send a signal to stop supplying power to the receiver of the oil pump motor 37, causing the oil pump motor 37 to stop rotating. At the same time, power supply to the electromagnetic coil m4 is stopped, causing the two-way check valve 33 to be connected to the pipeline in the left position under the action of the left spring; also at the same time, power is supplied to the electromagnetic coil m5, causing the lowering proportional solenoid valve 32 to be in the upper position and connected to the pipeline. The hydraulic oil in the main lifting cylinder 15 and the driving increasing cylinder 43 passes through the upper position of the lowering proportional solenoid valve 32 and then through the component pressure compensation valve 34 and returns to the fuel tank 36. Finally, the cylinder rod of the main lifting cylinder 15 contracts, and the contracted cylinder rod realizes the lowering of the goods through the working mechanism of the main lifting unit.

[0059] Auxiliary lifting system:

[0060] When the AGV vehicle recognizes that it is picking up a square pallet or goods with a bottom railing and issues a picking-up instruction, after the main controller automatically judges that it is necessary to first perform auxiliary lifting - fork insertion - auxiliary lowering, and then perform main lifting to meet the requirement of the goods lifting action and provide conditions for subsequent handling. The process of the AGV vehicle of the present invention picking up a square pallet or goods with a bottom railing is actually first through the contraction or elongation of the cylinder rod in the auxiliary lifting cylinder 28 of the hydraulic system - auxiliary lifting, and then through the working mechanism of the auxiliary lifting unit to realize the retraction and landing of the component load-bearing wheel assembly 11 to provide conditions for the fork to enter the fork. Then, the hydraulic system - main lifting is used to control the lifting and lowering of the pallet or goods. The structural characteristics, working mechanism of the auxiliary lifting unit, and the principle of the sub-hydraulic system - main lifting have been clearly explained above. Now, the principle of the hydraulic system - auxiliary lifting will be specifically analyzed as follows.

[0061] When the AGV vehicle issues a request for lifting the auxiliary lifting unit, the controller will first send a signal to energize the electromagnetic coil m2, causing the three-position four-way electromagnetic reversing valve 41 to be connected to the pipeline in the right position. At the same time, power is supplied to the receiver of the oil pump motor 37, causing the oil pump motor 37 to start rotating and drive the fixed-displacement gear pump 38 to work, sucking the hydraulic oil from the fuel tank 36. The hydraulic oil in the fuel tank is first filtered by the filter 39, then pressurized by the fixed-displacement gear pump 38. After the pressurized hydraulic oil pushes open the valve core of the check valve 35, it passes through the right position of the three-position four-way electromagnetic reversing valve 41, then flows into the balance valve 42, and finally enters the upper chamber of the cylinder barrel of the auxiliary lifting cylinder 28, pushing the cylinder rod to retract. The retracted cylinder rod realizes the retraction of the load-bearing wheel assembly 11 towards the inner side of the fork through the working mechanism of the auxiliary lifting unit, providing conditions for the fork to enter the fork.

[0062] After the forklift forks into the pallet, the AGV vehicle sends a request for the lowering of the secondary lifting unit. The controller will first send a signal to energize the electromagnetic coil m1, causing the left position of the three-position four-way electromagnetic reversing valve 41 to be connected to the pipeline. The pressurized hydraulic oil that pushes open the spool of the check valve 35 flows through the left position of the three-position four-way electromagnetic reversing valve 41, then into the balance valve 42, and finally into the lower chamber of the cylinder barrel of the secondary lifting cylinder 28, pushing the cylinder rod to extend. The extended cylinder rod, through the working mechanism of the secondary lifting unit, causes the load-bearing wheel assembly 11 to move away from the forklift and approach the ground until the rollers of the load-bearing wheel assembly 11 are tangent to the ground, thus completing the entire action of the vehicle's fork insertion.

[0063] After the entire action of the vehicle's fork insertion is completed, when the AGV vehicle sends a lifting requirement for a cross-shaped pallet or a goods with a bottom railing, it actually uses the hydraulic system - main lifting to control the main lifting unit to achieve the lifting and lowering of the forklift, and complete the lifting and lowering of the cross-shaped pallet or the goods with a bottom railing on the forklift.

[0064] Regardless of whether it forks a channel pallet or a cross-shaped pallet, the load-carrying lifting uses the hydraulic system - main lifting to control the extension or contraction of the cylinder rod of the main lifting cylinder 15, and then through the working mechanism of the main lifting unit, to achieve the lifting and lowering of the forklift, and complete the lifting and lowering of the pallet or goods on the forklift. However, for a channel pallet and goods with fork holes, it can directly fork in; for a cross-shaped pallet or goods with a bottom railing, it is necessary to first use the hydraulic system - secondary lifting to control the contraction or extension of the cylinder rod of the secondary lifting cylinder 28, and then through the working mechanism of the secondary lifting unit, to achieve the retraction or landing of the load-bearing wheel assembly 11, thus providing conditions for whether the vehicle can fork into the pallet.

[0065] The vehicle's hydraulic system in this embodiment is divided into two subsystems: main lifting and secondary lifting. Although these two sub-hydraulic systems share hydraulic fittings such as a pump motor, gear pump, check valve, relief valve, and filter. However, a two-way check valve, a three-position four-way electromagnetic reversing valve with an O-shaped neutral position, and the oil inlet M of the three-position four-way electromagnetic reversing valve are designed to be located between the check valve and the two-way check valve. In this way, the main lifting and secondary lifting work separately and do not affect each other, thus controlling the operation of the main lifting unit and the secondary lifting unit respectively. It is also possible to select different action logic sequences according to functional requirements to complete the lifting of the pallet or goods. In this way, there is no need to design many independent hydraulic systems respectively for different requirements of the main lifting and secondary lifting, or for different types of pallets. This not only occupies a large amount of space in the vehicle body but also causes waste of costs. In addition, numerous independent hydraulic systems will cause logical crossover of the vehicle and it is difficult to ensure continuous actions.

[0066] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0067] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. An AGV pallet truck, comprising a vehicle body and a fork frame assembly (16) arranged on the vehicle body, characterized in that: The fork frame assembly (16) comprises a fork body slidably connected to the vehicle body and a fork body extending outside the vehicle body, an intermediate support wheel assembly (20) is provided at the lower end of the fork body, and a load-bearing wheel assembly (11) is provided at one end of the fork body away from the vehicle body, and the load-bearing wheel assembly (11) is rotatably connected to the fork body via a wheel frame (12); A main lifting part for driving the wheel frame (12) to rotate in a direction away from the fork body and a secondary lifting part for driving the wheel frame (12) to rotate in a direction close to the fork body are provided between the fork frame assembly (16) and the vehicle body; A driving transmission assembly is provided between the main lifting part, the auxiliary lifting part and the wheel frame (12).

2. The AGV pallet truck according to claim 1, characterized in that: One end of the wheel frame (12) is rotatably connected to a load-bearing wheel assembly (11), and the other end of the wheel frame (12) is rotatably connected to the fork body via a pin shaft (18). The drive connection assembly is rotatably connected to the middle part of the wheel frame (12) for driving the wheel frame (12) to rotate around the pin shaft (18).

3. The AGV pallet truck according to claim 1, characterized in that: The driving transmission assembly comprises a push-pull rod assembly (13) rotatably connected to the middle part of the wheel frame (12); one end of the push-pull rod assembly (13) away from the wheel frame (12) is rotatably connected to a small rotating arm assembly (14); the middle part of the small rotating arm assembly (14) is rotatably connected to the bottom of the fork frame assembly (16); and one end of the small rotating arm assembly (14) away from the push-pull rod assembly (13) is movably connected to a small roller limiting bracket (19).

4. The AGV pallet truck according to claim 3, characterized in that: A waist-shaped hole is provided at the lower part of the small roller limiting bracket (19); a rotating shaft is provided on the small rotating arm assembly (14); the rotating shaft is movably connected to the waist-shaped hole; an auxiliary lifting carriage assembly (24) is slidably connected to the vehicle body up and down; and the small roller limiting bracket (19) is fixedly connected to the lower end of the auxiliary lifting carriage assembly (24).

5. The AGV pallet truck according to claim 1, characterized in that: The main lifting part comprises a main lifting cylinder (15), one end of the main lifting cylinder (15) is connected to the fork frame assembly (16) and the other end is connected to the vehicle body, and both sides of the fork frame assembly (16) are connected to the vehicle body channel steel in an upward and downward sliding manner through a channel steel roller assembly (17).

6. The AGV pallet truck according to claim 4, characterized in that: The auxiliary lifting part comprises an auxiliary lifting cylinder (28), the upper end of the auxiliary lifting cylinder (28) is connected to the vehicle body, the lower end of the auxiliary lifting cylinder (28) is connected to the auxiliary lifting slide assembly (24), and the two sides of the auxiliary lifting slide assembly (24) are connected to the vehicle body channel steel in an up and down sliding manner through auxiliary channel steel rollers (21).

7. The AGV pallet truck according to claim 6, characterized in that: The auxiliary lifting cylinder (28) is fixedly connected to the vehicle body through an upper cylinder fixing seat (30), and the upper cylinder fixing seat (30) is adjustably connected to the vehicle body through an upper adjusting bolt (31) and a lower adjusting bolt (29). The lower end of the auxiliary lifting cylinder (28) is connected to the auxiliary lifting slide assembly through a cylinder fixing shaft (22), and a fixing shaft locking plate (23) is provided on the cylinder fixing shaft (22). A proximity sensor (25) is provided at a position of the auxiliary lifting slide assembly (24) close to the vehicle body channel steel. The proximity sensor (25) is fixedly connected to the auxiliary lifting slide assembly (24) through a proximity sensor fixing bent plate (26), and an induction bent plate (27) cooperating with the proximity sensor (25) is provided on the vehicle body channel steel.

8. An AGV pallet truck hydraulic system for an AGV pallet truck according to any one of claims 1 to 7, characterized in that: It comprises an oil supply part, the oil supply part is connected to a main oil supply system and an auxiliary oil supply system, the main oil supply system is in communication with the main lifting cylinder (15), and the auxiliary oil supply system is in communication with the auxiliary lifting cylinder (28).

9. The hydraulic system of an AGV pallet truck according to claim 8, characterized in that: The oil supply unit comprises a gear pump (38) and an oil tank (36) connected to an oil inlet of the gear pump (38); the oil inlet of the gear pump (38) is provided with a filter (39); the power end of the gear pump (38) is connected to an oil pump motor (37); the output end of the gear pump (38) is connected to an oil supply pipe via a one-way valve (35); and the output end of the gear pump (38) is connected to an overflow valve (40).

10. The hydraulic system of an AGV pallet truck according to claim 8, characterized in that: The main oil supply system comprises a two-way check valve (33) connected to the oil supply pipe of the oil supply part, the oil outlet end of the two-way check valve (33) is in communication with the main lifting oil cylinder (15), the main lifting oil cylinder (15) is connected in parallel with the driving increase oil cylinder (43), the main lifting oil cylinder (15) is connected with an oil return pipeline, and the oil return pipeline is provided with a descending proportional solenoid valve (32) and a pressure compensation valve (34); The auxiliary oil supply system comprises two auxiliary lifting oil cylinders (28) and a balance valve (42) connected to the two auxiliary lifting oil cylinders. The balance valve (42) is connected to a reversing valve (41), and the reversing valve (41) is in communication with an oil supply pipe of an oil supply unit.

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