Autonomous-control energy-saving electric heavy forklift potential energy recovery system

Abstract

The utility model discloses an autonomously-controlled energy-saving electric heavy forklift potential energy recovery system which comprises a hydraulic oil tank, a first oil way and a second oil way, and the first oil way and the second oil way are connected into the hydraulic oil tank and are both connected with a left lifting valve block and a right lifting valve block. The left lifting valve block and the right lifting valve block are connected with the left lifting oil cylinder and the right lifting oil cylinder respectively, and a pressure sensor is arranged at the joint of the first oil way and the second oil way. The device is simple in structure, the cylinder bottom pressure of the left lifting oil cylinder and the right lifting oil cylinder is detected through the pressure sensors, if the pressure is displayed to be in a no-load state, the opening degree of the two-way speed limiting valve is the maximum, the recovery flow falls back into the hydraulic oil tank through the two-way speed limiting valve and the two-way hydraulic pump, and when the pressure is displayed to be in a full-load state, the recovery flow falls back into the hydraulic oil tank through the two-way hydraulic pump. When the two-way speed limiting valve is closed, all flow with potential energy is recycled through the two-way hydraulic pump, some energy can be recycled to the maximum extent, and contribution is made to energy conservation of the whole machine.

Description

Technical Field

[0001] The utility model relates to the technical field of potential energy recovery for heavy-duty forklifts, in particular to an autonomously controlled energy-saving potential energy recovery system for electric heavy-duty forklifts. Background Art

[0002] With the development of the logistics and warehousing industries, heavy-duty forklifts are increasingly used. However, heavy-duty forklifts, particularly due to the frequent use of hydraulic systems, consume a lot of energy during operation, and their limited endurance is a significant drawback. Therefore, improving the energy efficiency of forklifts, particularly through potential energy recovery technologies to extend vehicle operating time, has become a research hotspot within the industry.

[0003] Currently, the most common potential energy recovery systems for heavy-duty forklifts on the market primarily utilize pumps with forward and reverse rotation, or "negative swing angle" capabilities. Specifically, when the forks are raised, the motor rotates forward to drive the pump, directing oil into the lift cylinder to complete the lift. When the forks need to be lowered, a multi-way valve changes the oil flow direction, and the pump switches to reverse rotation, or "negative swing angle" mode. At this point, the pump acts as a generator, driven by the potential energy released during the lowering of the cylinder. This mechanical energy is then converted into electrical energy, stored in the battery for later use.

[0004] However, there are still obvious deficiencies in practical applications. First, due to the limited speed and displacement of the pump, the fork's lowering speed is limited, which in turn affects the time of the entire working cycle and reduces the operating efficiency of the forklift. Secondly, due to the low energy conversion efficiency during the recovery process and the poor stability of the pump when working in reverse or "negative swing angle" state, the overall energy recovery effect is unsatisfactory. In addition, the long wait for energy recovery not only increases the workload of the operator, but also indirectly increases operating costs, affecting the market competitiveness of the forklift. For this reason, an autonomously controlled energy-saving electric heavy-duty forklift potential energy recovery system is proposed. Utility Model Content

[0005] The purpose of the present utility model is to provide an autonomously controlled energy-saving electric heavy-duty forklift potential energy recovery system to solve the problems raised in the above-mentioned background technology.

[0006] To achieve the above object, the utility model provides the following technical scheme: A self -control's energy -conserving electric heavy fork truck potential energy recovery system, including hydraulic oil tank and the first oil way and the second oil way of access hydraulic oil tank, the first oil way and the second oil way are connected with left lifting valve block and right lifting valve block, left lifting valve block and right lifting valve block are connected with left lifting oil cylinder and right lifting oil cylinder respectively, be equipped with pressure sensor in the junction of the first oil way and the second oil way, the first oil way includes the bidirectional hydraulic pump of input end access hydraulic oil tank, the output of bidirectional hydraulic pump is connected with lifting pilot valve, left lifting valve block and right lifting valve block, the first motor is connected with controller.

[0007] As a further scheme of the utility model: The lifting pilot valve is connected with the accumulator, the left lifting valve block, the right lifting valve block and the hydraulic oil tank.

[0008] As a further scheme of the utility model: The second oil way includes the plunger variable displacement pump of access hydraulic oil tank, the plunger variable displacement pump is connected with the second motor, the plunger variable displacement pump is connected with the electric proportional multiway valve, the electric proportional multiway valve is connected with the bidirectional speed limiting valve.

[0009] As a further scheme of the utility model: The electric proportional multiway valve is also connected with the hydraulic oil tank and the pressure reducing valve, and the pressure reducing valve is connected with the lifting pilot valve and the oil tank respectively.

[0010] As a further scheme of the utility model: The left lifting oil cylinder and the right lifting oil cylinder are connected with the hydraulic oil tank.

[0011] As a further scheme of the utility model: The lifting pilot valve is composed of a check valve, a two-position two-way electromagnetic valve, a two-position three-way electromagnetic valve and a relief valve.

[0012] As a further scheme of the utility model: The right lifting valve block is composed of a main valve, an overload valve and a one-way valve, and an electromagnetic valve.

[0013] As a further scheme of the utility model: The left lifting valve block and the right lifting valve block are the same in structure, and the left lifting oil cylinder and the right lifting oil cylinder are the same in structure.

[0014] Compared with the prior art, the utility model has the advantages that:

[0015] The application detects the cylinder bottom pressure of the left lifting oil cylinder and the right lifting oil cylinder through the pressure sensor, when the pressure display is in the empty load state, the bidirectional speed limiting valve has the maximum opening degree, the recovery flow falls to the inside of the hydraulic oil tank through the bidirectional speed limiting valve and the bidirectional hydraulic pump, when the pressure display is in the full load state, the bidirectional speed limiting valve is closed, and all the potential energy flow is recovered through the bidirectional hydraulic pump, so that some energy can be recovered to the maximum extent, and the whole machine is energy-saving.

[0016] In addition, if the pressure sensor detects that the pressure load exceeds the set overflow pressure, the controller can issue a command to stop the first motor from rotating. The controller controls the electric proportional multi-way valve to close port A, and the oil is no longer supplied. As a result, the pressure of the left lifting cylinder and the right lifting cylinder will no longer continue to rise after reaching the set pressure, thereby protecting the entire hydraulic system and preventing overflow losses. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the overall principle of the potential energy recovery system of the utility model;

[0018] Figure 2 This is a partial principle diagram of the potential energy recovery system of the utility model;

[0019] Figure 3 This is a schematic diagram of the principle of the electric proportional multi-way valve of the utility model;

[0020] Figure 4 Schematic diagram of the left and right lifting cylinders of the present invention;

[0021] Figure 5 This is a linear logic diagram of energy recovery of the utility model;

[0022] In the figure: 1. Hydraulic oil tank; 2. Bidirectional hydraulic pump; 3. First motor; 4. Controller; 5. Lifting pilot valve; 51. Check valve; 52. Two-way solenoid valve; 53. Three-way solenoid valve; 54. Overflow valve; 6. Left lifting valve block; 7. Right lifting valve block; 71. Overload valve; 72. Main valve; 73. One-way valve; 74. Solenoid valve; 8. Left lifting cylinder; 9. Right lifting cylinder; 10. Pressure sensor; 11. Pressure reducing valve; 12. Accumulator; 13. Bidirectional speed limiting valve; 14. Electric proportional multi-way valve; 15. Plunger variable pump; 16. Second motor. DETAILED DESCRIPTION

[0023] 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 embodiments described 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 making creative efforts are within the scope of protection of the present invention.

[0024] See also Figure 1-5In the embodiment of the utility model, an autonomously controlled energy-saving electric heavy-duty forklift potential energy recovery system includes a hydraulic oil tank 1 and a first oil circuit and a second oil circuit connected to the hydraulic oil tank 1, the first oil circuit and the second oil circuit are both connected to the left lifting valve block 6 and the right lifting valve block 7, the left lifting valve block 6 and the right lifting valve block 7 are respectively connected to the left lifting cylinder 8 and the right lifting cylinder 9, the port of the left lifting valve block 6 is connected to the left lifting cylinder 8 through the oil port, and the port of the right lifting valve block 7 is also connected to the right lifting cylinder 9 through the oil port, the left lifting cylinder 8 and the right lifting cylinder 9 have the same structure; the left lifting cylinder 8 and the right lifting cylinder 9 are both composed of a cylinder body and a piston rod, and the end of the piston rod divides the interior of the cylinder body into a rod chamber and a rodless chamber, wherein the first oil circuit and The second oil circuit injects oil into the rodless cavity. A pressure sensor 10 is provided at the junction of the first oil circuit and the second oil circuit. The junction of the first oil circuit and the second oil circuit is port M. The first oil circuit includes a two-way hydraulic pump 2 whose input end is connected to the hydraulic oil tank 1. The output end of the two-way hydraulic pump 2 is respectively connected to the lifting pilot valve 5, the left lifting valve block 6 and the right lifting valve block 7. The first motor 3 is connected to the controller 4. The controller 4 is also connected to the pressure sensor 10 and the electric proportional multi-way valve 14. During the lifting process of the gantry, the pressure sensor 10 connected to port M will always measure the pressure of the left lifting cylinder 8 and the right lifting cylinder 9P5 and P4 ports, and transmit the data to the controller 4 in real time. If the pressure load exceeds the set overflow pressure, The controller 4 sends a command to stop the first motor 3 from rotating. The controller 4 closes port A by controlling the electric proportional multi-way valve 14, and the oil is no longer supplied, so that the pressure of the left lifting cylinder 8 and the right lifting cylinder 9 stops rising after reaching the set pressure, thereby protecting the entire hydraulic system and causing no overflow loss; the lifting pilot valve 5 is respectively connected to the accumulator 12, the left lifting valve block 6, the right lifting valve block 7 and the hydraulic oil tank 1; the accumulator 12 can store hydraulic oil, and the lifting pilot valve 5 includes a check valve 51, a two-way solenoid valve 52, a three-way solenoid valve 53 and a relief valve 54, wherein the check valve 51 can maintain the pressure pulsation at the inlet of the lifting pilot valve 5 and improve the response speed; and the relief valve 54 can be opened when the oil pressure is too high. Overflow protection lifting pilot valve 5, the right lifting valve block 7 includes an overload valve 71, a main valve 72 and a one-way valve 73, and a solenoid valve 74. When a system failure causes the motor to stop rotating, the solenoid valve 74 can be opened by touching the switch, thereby urgently lowering the goods lifted into the air to the ground; the left lifting valve block 6 and the right lifting valve block 7 have the same structure, and the second oil circuit includes a plunger variable pump 15 connected to the hydraulic oil tank 1, the plunger variable pump 15 is connected to the second motor 16, the plunger variable pump 15 is connected to the electric proportional multi-way valve 14, the electric proportional multi-way valve 14 is connected to the two-way speed limiting valve 13, the electric proportional multi-way valve 14 is also connected to the hydraulic oil tank 1 and the pressure reducing valve 11, and the pressure reducing valve 11 is respectively connected to the lifting pilot valve 5 and the hydraulic oil tank 1.

[0025] When the heavy electric forklift is working normally, the controller 4 in the first oil path proportionally controls the real-time output speed of the first motor 3 after the electric control handle is operated, the first motor 3 drives the bidirectional hydraulic pump 2 to suck hydraulic oil from the hydraulic oil tank 1, and the pressurized hydraulic oil is sent to the P3 and P2 ports of the left lifting valve block 6 and the right lifting valve block 7. At this time, the two-way electromagnetic valve 52 and the three-way electromagnetic valve 53 in the lifting pilot valve 5 are not working, the main valves in the left lifting valve block 6 and the right lifting valve block 7 are in a one-way opening state, the hydraulic oil reaches the P4 and P5 ports through the P2 and P3 ports respectively, and enters the rodless cavities of the left lifting oil cylinder 8 and the right lifting oil cylinder 9. At this time, the forks are lifted.

[0026] At the same time, the A port of the electric proportional multi-way valve 14A in the second oil path is opened, the second motor 16 drives the plunger variable pump 15 to suck hydraulic oil from the hydraulic oil tank 1, the hydraulic oil is pumped into the electric proportional multi-way valve 14 and enters the C-D port of the bidirectional speed limiting valve 13 through the A port, and enters the P3 and P2 ports of the left lifting valve block 6 and the right lifting valve block 7, and enters the rodless cavities of the left lifting oil cylinder 8 and the right lifting oil cylinder 9.

[0027] The above two high-pressure oils enter the rodless cavities of the left lifting oil cylinder 8 and the right lifting oil cylinder 9 respectively to drive the piston rods in the left lifting oil cylinder 8 and the right lifting oil cylinder 9 to move synchronously, synchronously drive the inner mast and forks of the heavy forklift to move upward at the same time, and reach the specified position for accurate stacking.

[0028] In addition, the hydraulic oil in the rod cavities of the left lifting oil cylinder 8 and the right lifting oil cylinder 9 flows back to the hydraulic oil tank 1 through the T5 and T6 ports on the left lifting oil cylinder 8 and the right lifting oil cylinder 9 respectively, and the pressure of the rodless cavities of the left lifting oil cylinder 8 and the right lifting oil cylinder 9 is controlled by the overload valve 71 in the left lifting valve block 6 and the right lifting valve block 7. If the forks are hit, the instantaneous pressure exceeds the set pressure, and the excess oil will flow back to the hydraulic oil tank 1 through the T2 port on the overload valve 71. Thus, the electric forklift completes the normal mast lifting working condition.

[0029] If the forks need to hover at a certain position, the electric control handle can be directly returned to the home position, the first motor 3 stops rotating, the bidirectional hydraulic pump 2 does not work, and no hydraulic oil enters the main valve 72 in the left lifting valve block 6 and the right lifting valve block 7. Since the main valve is in a one-way opening state, the hydraulic oil in the rodless cavities of the left lifting oil cylinder 8 and the right lifting oil cylinder 9 is prevented from flowing out, and the forks are kept at a certain position; at the same time, the A port of the electric proportional multi-way valve 14 is closed, the plunger variable pump 15 adjusts the displacement, and the pumped hydraulic oil directly returns to the hydraulic oil tank 1; at this time, the left lifting oil cylinder 8 and the right lifting oil cylinder 9 have no oil supply, and the forks will stop with the mast.

[0030] When the gantry is empty or full of goods, the rodless cavity of the left lifting oil cylinder 8 and the right lifting oil cylinder 9 is filled with oil of a certain pressure, and the hydraulic oil in the rodless cavity of the left lifting oil cylinder 8 and the right lifting oil cylinder 9 is extruded downward under the action of the gravity of the gantry system and the goods and enters the P5 and P4 ports on the left lifting valve block 6 and the right lifting valve block 7, at this time, the T6 and T5 ports on the left lifting oil cylinder 8 and the right lifting oil cylinder 9 will suck oil in the hydraulic oil tank 1 in the opposite direction, the purpose of sucking oil here is two-fold, one is to balance the negative pressure in the rod cavity of the left lifting oil cylinder 8 and the right lifting oil cylinder 9, and the other is to lubricate the piston rod inside the left lifting oil cylinder 8 and the right lifting oil cylinder 9 to prevent excessive wear; while the hydraulic oil inside the left lifting oil cylinder 8 and the right lifting oil cylinder 9 is supplied to the left lifting valve block 6 and the right lifting valve block 7, the two-way electromagnetic valve 52 and the three-way electromagnetic valve 53 on the lifting pilot valve 5 are powered on, at this time, the hydraulic oil stored in the accumulator 12 enters the two-way electromagnetic valve 52 through the ACC port on the lifting pilot valve 5, at this time, the three-way electromagnetic valve 53 is powered on, and the hydraulic oil enters the control oil ports G and H of the left lifting valve block 6 and the right lifting valve block 7 from the D port on the lifting pilot valve 5 through the three-way electromagnetic valve 53; taking the right lifting valve block 7 as an example, the hydraulic oil entering the main valve 72 through the control oil port G pushes the valve core of the main valve 72 to move to one side, so that the main valve 72 is in a bidirectional opening state, at this time, the hydraulic oil in the rodless cavity of the right lifting oil cylinder 9 enters the right lifting valve block 7 due to the action of gravity, and since the one-way valve 73 blocks the way, the hydraulic oil can pass through the main valve 72 to reach the P2 port and the M port; similarly, the hydraulic oil in the rodless cavity of the left lifting oil cylinder 8 flows to the M port through the P3 port of the left lifting valve block 6; at the M port, the oil is divided into two paths, one path reaches the bidirectional hydraulic pump 2, so this path of hydraulic oil drives the bidirectional hydraulic pump 2 to operate in the opposite direction, thereby making the first motor 3 operate in the opposite direction to generate electricity and timely charge the super capacitor arranged in the vehicle electrical system for storage, when the forklift fork needs to be lifted, the first motor 3 immediately rotates in the forward direction, the first motor 3 can use the stored electrical energy from the super capacitor to work at this time, the other path of oil directly returns to the hydraulic oil tank 1 through the A port of the electric proportional multi-way valve 14; the two paths of hydraulic oil one reaches the bidirectional hydraulic pump 2 for energy recovery, and the other oil directly reaches the hydraulic oil tank 1, because the potential energy recovery is relatively slow, causing the speed of the fork to drop relatively slowly, and the oil is directly returned to the hydraulic oil tank 1, which can improve the descending speed, but too much oil directly returns to the hydraulic oil tank 1, and the recovered oil is insufficient, which will cause a lot of loss, at this time, the controller 4 controls the opening of the bidirectional speed limiting valve 13 according to the pressure detected by the pressure sensor 10 to determine the amount of potential energy recovered, so as to improve the descending speed and recover sufficient descending potential energy.

[0031] The specific strategy is as follows:

[0032] During the fork lowering process, the pressure sensor 10 has been detecting the bottom pressure of the left lifting cylinder 8 and the right lifting cylinder 9. If the pressure shows that it is in the no-load state, the cylinder bottom pressure is basically 5MPa, and the two-way speed limiting valve 13 is opened to the maximum, and the recovery flow is 150L / min through the two-way speed limiting valve 13; when the pressure shows the full load state, the two-way speed limiting valve 13 is closed, and all the potential energy flow is recovered by the two-way hydraulic pump 2, and the recovery energy is based on linear logic, see the attached Figure 5 .

[0033] Although this specification is described according to implementation methods, not every implementation method contains only one independent technical solution. This narrative method 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 can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0034] Therefore, the above description is only a preferred embodiment of the present application and is not intended to limit the scope of implementation of the present application; that is, all equivalent modifications made according to the scope of the claims of the present application are within the scope of protection of the claims of the present application.

Claims

1. An autonomously controlled energy-saving electric heavy-duty forklift potential energy recovery system, characterized in that: The invention comprises a hydraulic oil tank (1) and a first oil circuit and a second oil circuit connected to the hydraulic oil tank (1); the first oil circuit and the second oil circuit are both connected to a left lifting valve block (6) and a right lifting valve block (7); the left lifting valve block (6) and the right lifting valve block (7) are respectively connected to a left lifting oil cylinder (8) and a right lifting oil cylinder (9); a pressure sensor (10) is provided at the intersection of the first oil circuit and the second oil circuit; the first oil circuit comprises a bidirectional hydraulic pump (2) whose input end is connected to the hydraulic oil tank (1); the output end of the bidirectional hydraulic pump (2) is connected to a lifting pilot valve (5), the left lifting valve block (6) and the right lifting valve block (7); and the first motor (3) is connected to a controller (4).

2. The autonomously controlled energy-saving electric heavy-duty forklift potential energy recovery system according to claim 1 is characterized in that: The lifting pilot valve (5) is connected to the accumulator (12), the left lifting valve block (6), the right lifting valve block (7) and the hydraulic oil tank (1).

3. The autonomously controlled energy-saving electric heavy-duty forklift potential energy recovery system according to claim 1 is characterized in that: The second oil circuit comprises a plunger variable pump (15) connected to the hydraulic oil tank (1), the plunger variable pump (15) being connected to a second motor (16), the plunger variable pump (15) being connected to an electric proportional multi-way valve (14), and the electric proportional multi-way valve (14) being connected to a two-way speed limiting valve (13).

4. The autonomously controlled energy-saving electric heavy-duty forklift potential energy recovery system according to claim 3 is characterized in that: The electric proportional multi-way valve (14) is also connected to the hydraulic oil tank (1) and the pressure reducing valve (11), and the pressure reducing valve (11) is respectively connected to the lifting pilot valve (5) and the oil tank (1).

5. The autonomously controlled energy-saving electric heavy-duty forklift potential energy recovery system according to claim 1 is characterized in that: The left lifting oil cylinder (8) and the right lifting oil cylinder (9) are both connected to the hydraulic oil tank (1).

6. The autonomously controlled energy-saving electric heavy-duty forklift potential energy recovery system according to claim 1 is characterized in that: The lifting pilot valve (5) is composed of a check valve (51), a two-position two-way solenoid valve (52), a two-position three-way solenoid valve (53) and a relief valve (54).

7. The autonomously controlled energy-saving electric heavy-duty forklift potential energy recovery system according to claim 1 is characterized in that: The right lifting valve block (7) is composed of a main valve (71), an overload valve (72), a one-way valve (73), and a solenoid valve (74).

8. The autonomously controlled energy-saving electric heavy-duty forklift potential energy recovery system according to claim 1 is characterized in that: The left lifting valve block (6) and the right lifting valve block (7) have the same structure, and the left lifting oil cylinder (8) and the right lifting oil cylinder (9) have the same structure.

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