Electric control and valve control combined type forklift potential energy recovery system

Abstract

A hybrid electronically controlled and valve-controlled forklift potential energy recovery system is disclosed. The cooling circulation module includes a motor controller, a permanent magnet synchronous motor-generator, and a cooling circulation pump. The power module coaxially connects a four-quadrant hydraulic pump-motor to the permanent magnet synchronous motor-generator via a torque sensor, and a power simulator is connected to the motor controller. A lifting hydraulic circuit drives the forks to lift; a tilting hydraulic circuit drives the forks to tilt; an accumulator energy storage module recovers the potential energy from the load's descent and supplies power to the four-quadrant hydraulic pump-motor; a motor-controlled potential energy module completes the hydraulic oil input and potential energy recovery; a proportional flow valve controls the combined control of the potential energy recovery module and the motor-controlled potential energy module to control the load descent speed. This system effectively improves the potential energy recovery efficiency under complex working conditions, ensures the stability of the hydraulic system by releasing the recovered energy through the accumulator, and facilitates lifting and tilting actions, thereby extending the service life of the hydraulic system.

Description

Technical Field

[0001] This invention relates to a forklift potential energy recovery system, and more particularly to an electronically controlled and valve-controlled composite forklift potential energy recovery system, belonging to the field of forklift system research and development technology. Background Technology

[0002] In recent years, with the rapid economic development, the logistics industry has become my country's largest industry, and forklifts, as commonly used tools for handling and palletizing in the logistics industry, have also developed rapidly. Traditional electric forklifts frequently lift and lower during operation. When the load is lowered, the potential energy of the load is consumed in the hydraulic system, resulting in a large amount of energy loss. This energy loss can also cause hydraulic component failures and reduce the service life of hydraulic components, so it is necessary to recover the potential energy.

[0003] Existing electric forklift potential energy recovery systems often use throttle valves or variable hydraulic pumps to control the load descent speed. This results in low hydraulic system operating efficiency and significant energy loss. Furthermore, the potential energy recovery efficiency is unstable under different loads or heights. Summary of the Invention

[0004] To address the shortcomings of the prior art, this invention provides a hybrid electronic and valve-controlled forklift potential energy recovery system. This system can effectively improve the potential energy recovery efficiency under complex working conditions with different loads and heights. By releasing the recovered energy through an accumulator, the system can ensure the stability of the hydraulic system and also assist in lifting and tilting actions, thereby helping to extend the service life of the hydraulic system.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: an electronically controlled and valve-controlled composite forklift potential energy recovery system, comprising an oil tank, a control module, a tilting oil circuit, an accumulator energy storage module, a motor-controlled potential energy module, a proportional flow valve-controlled potential energy recovery module, a lifting oil circuit, a cooling circulation module, and a power module;

[0006] The cooling circulation module includes a motor controller electrically connected to a permanent magnet synchronous motor-generator and a cooling circulation pump for water cooling of both.

[0007] The power module, in addition to the cooling circulation module, also includes a power simulator, a torque sensor, and a four-quadrant hydraulic pump-motor. The four-quadrant hydraulic pump-motor is coaxially connected to the permanent magnet synchronous motor-generator via the torque sensor. The power simulator is connected to the motor controller.

[0008] The oil tank is supplied with oil by a four-quadrant hydraulic pump-motor. The control module, power simulator, motor controller, permanent magnet synchronous motor-generator, and torque sensor are connected via CAN communication.

[0009] The lifting oil circuit supplies oil to the rodless chambers of the first hydraulic cylinder and the second hydraulic cylinder through the oil outlet of the four-quadrant hydraulic pump-motor in sequence via the first check valve, the first two-position two-way solenoid valve and the third check valve, thereby driving the lifting motion of the forks.

[0010] The tilting oil circuit and the lifting oil circuit are configured in parallel. The oil outlet of the four-quadrant hydraulic pump-motor passes through the fifth check valve and the three-position four-way directional valve to supply oil to the rodless chamber of the third tilting cylinder and the fourth tilting cylinder. The hydraulic oil can be returned to the oil tank by the three-position four-way directional valve, thereby driving the fork to tilt.

[0011] The accumulator energy storage module includes an accumulator and a third two-position two-way solenoid valve located at the opening. It is located between the lifting oil circuit and the tilting oil circuit to recover the potential energy of the load drop and can work with the four-quadrant hydraulic pump-motor to supply energy to the lifting oil circuit and the tilting oil circuit.

[0012] The motor control potential energy module is connected in parallel with the lifting oil circuit and the tilting oil circuit. The rodless chambers of the first hydraulic cylinder and the second hydraulic cylinder are connected to the four-quadrant hydraulic pump-motor through the second throttle valve and the second two-position two-way solenoid valve in sequence. The hydraulic oil input and potential energy recovery of the lifting oil circuit and the tilting oil circuit are completed by the input signal of the motor controller.

[0013] The proportional flow valve control potential energy recovery module is connected in parallel with the motor control potential energy module, and the proportional flow valve control potential energy recovery module is connected in series with the power module. The rodless chambers of the first hydraulic cylinder and the second hydraulic cylinder are connected to the four-quadrant hydraulic pump-motor in sequence through the proportional flow valve and the fourth check valve, which can control the load descent speed in a composite manner.

[0014] Compared with the prior art, the beneficial effects of this invention are as follows: Based on the potential energy recovery of the permanent magnet synchronous motor-generator and the four-quadrant hydraulic pump-motor, this invention adds a control module and a proportional flow valve control module for potential energy recovery. This enables the permanent magnet synchronous motor-generator braking torque and the proportional flow valve opening to jointly adjust the descent speed under different loads and heights, ensuring the stability of potential energy recovery, improving the potential energy recovery efficiency of the hydraulic system under complex working conditions, and helping to extend the service life of the hydraulic system. The lifting oil circuit can complete unloading by manually adjusting the first throttle valve in case of forklift failure, achieving a safer working environment. The accumulator can not only ensure the stability of the hydraulic system, but also work with the permanent magnet synchronous motor-generator to provide energy to the tilting oil circuit and the lifting oil circuit, achieving energy saving and potential energy recovery and reuse functions. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the electronically controlled and valve-controlled composite forklift potential energy recovery system of the present invention. Detailed Implementation

[0016] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0017] like Figure 1 As shown, an electronically controlled and valve-controlled composite forklift potential energy recovery system includes an oil tank 1, a control module 2, a tilting oil circuit C, an accumulator energy storage module D, a motor-controlled potential energy module E, a proportional flow valve-controlled potential energy recovery module F, a lifting oil circuit G, a cooling circulation module H, and a power module I.

[0018] The cooling circulation module H includes a motor controller 4 and a permanent magnet synchronous motor-generator 6 connected by electrical connection, and a cooling circulation pump 5 for water cooling of both.

[0019] The power module I, in addition to the cooling circulation module H, also includes a power simulator 3, a torque sensor 7, and a four-quadrant hydraulic pump-motor 8. The four-quadrant hydraulic pump-motor 8 is coaxially connected to the permanent magnet synchronous motor-generator 6 through the torque sensor 7. The power simulator 3 is connected to the motor controller 4.

[0020] The oil tank 1 supplies oil to the four-quadrant hydraulic pump-motor 8. The control module 2, power simulator 3, motor controller 4, permanent magnet synchronous motor-generator 6 and torque sensor 7 are connected via CAN communication.

[0021] The lifting oil circuit G supplies oil to the rodless chambers of the first hydraulic cylinder 15 and the second hydraulic cylinder 16 through the oil outlet of the four-quadrant hydraulic pump-motor 8 via the first check valve 12, the first two-position two-way solenoid valve 13 and the third check valve 14, thereby driving the lifting motion of the forks.

[0022] The tilting oil circuit C and the lifting oil circuit G are configured in parallel. The oil outlet of the four-quadrant hydraulic pump-motor 8 passes through the fifth check valve 21 and the three-position four-way directional valve 29 to supply oil to the rodless chamber of the third tilting cylinder 27 and the fourth tilting cylinder 28. The hydraulic oil can be returned to the oil tank 1 by switching through the three-position four-way directional valve 29, thereby driving the forks to tilt.

[0023] The accumulator energy storage module D includes an accumulator 24 and a third two-position two-way solenoid valve 25 disposed in the opening. It is disposed between the lifting oil circuit G and the tilting oil circuit C, and is used to recover the potential energy of the load drop and can work with the four-quadrant hydraulic pump-motor 8 to supply energy to the lifting oil circuit G and the tilting oil circuit C.

[0024] The motor control potential energy module E is connected in parallel with the lifting oil circuit G and the tilting oil circuit C. The rodless chambers of the first hydraulic cylinder 15 and the second hydraulic cylinder 16 are connected to the four-quadrant hydraulic pump-motor 8 through the second throttle valve 22 and the second two-position two-way solenoid valve 23 in sequence. The hydraulic oil input and potential energy recovery of the lifting oil circuit G and the tilting oil circuit C are completed by inputting signals through the motor controller 4.

[0025] The proportional flow valve control potential energy recovery module F is connected in parallel with the motor control potential energy module E, and the proportional flow valve control potential energy recovery module F is connected in series with the power module I. The rodless chambers of the first hydraulic cylinder 15 and the second hydraulic cylinder 16 are connected to the four-quadrant hydraulic pump-motor 8 through the proportional flow valve 19 and the fourth check valve 20 in sequence, which can control the load descent speed in a composite manner.

[0026] Furthermore, a filter 30 is provided at the front end of the return port of the oil tank 1 to filter the returned hydraulic oil.

[0027] Furthermore, an overflow valve 9 is provided between the first check valve 12 and the filter 30. When the pressure in the lifting oil circuit G and the tilting oil circuit C is greater than the pressure that the overflow valve 9 can withstand, the excess hydraulic oil is returned to the oil tank 1.

[0028] Furthermore, the lifting oil circuit G is also equipped with a first throttle valve 17 in parallel, and the rodless chambers of the first hydraulic cylinder 15 and the second hydraulic cylinder 16 are returned to the oil tank 1 via the first throttle valve 17.

[0029] Furthermore, the accumulator 24 is equipped with a third throttle valve 26 in addition to the third two-position two-way solenoid valve 25, which throttles the hydraulic oil flowing into the accumulator 24 when recovering the potential energy of the load decrease.

[0030] Furthermore, the proportional flow valve control potential energy recovery module F, the motor control potential energy module E, and the accumulator energy storage module D are all connected to the four-quadrant hydraulic pump-motor 8 after passing through the second check valve 10.

[0031] Furthermore, the control module 2 is also equipped with a second pressure sensor 11 and a first pressure sensor 18. The first pressure sensor 18 detects the oil outlet pressure of the lifting oil circuit G and the tilting oil circuit C, and the second pressure sensor 11 detects the oil inlet pressure of the lifting oil circuit G and the tilting oil circuit C.

[0032] The working principle of this electronically controlled and valve-controlled combined forklift potential energy recovery system is as follows:

[0033] When the forklift forks are being lifted, there are two working conditions:

[0034] 1) When the accumulator 24 is depressurized, the accumulator 24 in the hydraulic system cannot supply oil. Oil is supplied only through the power module I. First, the control module 2 controls the first two-position two-way solenoid valve 13 to be energized. Second, the motor controller 4 gives the speed of the permanent magnet synchronous motor-generator 6, drives the intermediate torque sensor 7, and then drives the four-quadrant hydraulic pump-motor 8, so that the hydraulic oil is input from the oil tank 1 to the lifting oil circuit G, and enters the first hydraulic cylinder 15 and the second hydraulic cylinder 16 to realize the lifting of the forks.

[0035] To increase the lifting speed of the forks, the speed of the permanent magnet synchronous motor-generator 6 can be adjusted by controlling the speed of the permanent magnet synchronous motor-generator 6 through the control module 2. The speed threshold of the permanent magnet synchronous motor-generator 6 is set in advance to 2500 revolutions per minute.

[0036] 2) When the accumulator 24 is pressurized, the accumulator 24 in the hydraulic system can work together with the power module I. The control module 2 controls the first two-position two-way solenoid valve 13 and the third two-position two-way solenoid valve 25 to be energized. The pressure of the accumulator 24 supplies energy to the lifting oil circuit G. At the same time, the motor controller 4 gives the speed of the permanent magnet synchronous motor-generator 6 to jointly realize the lifting of the forks and play an energy-saving role.

[0037] When the forklift forks are lowered, there are three working conditions:

[0038] 1) Motor-controlled potential energy recovery

[0039] When the forks descend from the high position, the control module 2 first controls the second two-position two-way solenoid valve 23 and the third two-position two-way solenoid valve 25 to be energized, and reduces the braking torque of the permanent magnet synchronous motor-generator 6. The potential energy is recovered simultaneously through the accumulator 24 and the permanent magnet synchronous motor-generator 6.

[0040] When the forks descend from the low position, if the rotational speed read by the torque sensor 7 cannot be changed significantly by the braking torque of the permanent magnet synchronous motor-generator 6, the third two-position two-way solenoid valve 25 is closed. At the same time, the control module 2 controls the motor controller 4 to give the braking torque of the permanent magnet synchronous motor-generator 6, which is adjusted according to the rotational speed read by the torque sensor 7. When the rotational speed read by the torque sensor 7 is large, the braking torque of the permanent magnet synchronous motor-generator 6 can be appropriately increased, and vice versa, to ensure the stability of the retraction time of the power module I.

[0041] 2) Proportional valve control for potential energy recovery

[0042] When the forks descend from the high position, the control module 2 first controls the second two-position two-way solenoid valve 23 and the third two-position two-way solenoid valve 25 to be energized, and then controls the opening size of the proportional flow valve 19 to keep the power module I and the accumulator 24 recovering potential energy and maintaining a stable state.

[0043] When the forks descend from the low position, if the rotational speed read by the torque sensor 7 cannot be changed within a wide range by changing the opening size of the proportional flow valve 19, the control module 2 controls the third two-position two-way solenoid valve 25 to open, and recovers the remaining potential energy through the power module I.

[0044] 3) Combined potential energy recovery system using motor control and proportional valve control

[0045] When the forks descend from the high position, the control module 2 first controls the second two-position two-way solenoid valve 23 and the third two-position two-way solenoid valve 25 to be energized. Then, the braking torque of the permanent magnet synchronous motor-generator 6 can be increased and the opening of the proportional flow valve 19 can be reduced to generate greater potential energy. The potential energy is then recovered simultaneously through the permanent magnet synchronous motor-generator 6 and the accumulator 24.

[0046] When the forks descend from the low position, the corresponding torque sensor 7 reads a very small rotational speed, closes the third two-position two-way solenoid valve 25, and at the same time, the control module 2 reduces the braking torque of the permanent magnet synchronous motor-generator 6 and increases the opening of the proportional flow valve 19, so that the oil pressure converted from the descending potential energy increases, and the potential energy is recovered through the power module I.

[0047] When the forklift forks tilt:

[0048] First, control module 2 energizes the three-position four-way directional valve 29, connecting port P to port A and port T to port B. Motor controller 4 sets the speed of permanent magnet synchronous motor-generator 6, driving the intermediate torque sensor 7, which in turn drives the four-quadrant hydraulic pump-motor 8. This causes hydraulic oil to flow from tank 1 into tilting circuit C. The hydraulic oil flows through PA channel into the rodless chamber of the third tilting cylinder 27 and the fourth tilting cylinder 28, while the hydraulic oil in the rod chamber of the third tilting cylinder 27 and the fourth tilting cylinder 28 flows back to tank 1 through BT channel and filter 30, achieving forward tilting of the forks. Conversely, control module 2 energizes the three-position four-way directional valve 29, connecting port P to port B and port T to port A. The hydraulic oil flows through PB channel into the rod chamber of the third tilting cylinder 27 and the fourth tilting cylinder 28, while the hydraulic oil in the rodless chamber of the third tilting cylinder 27 and the fourth tilting cylinder 28 flows back to tank 1 through AT channel and filter 30, achieving backward tilting of the forks.

[0049] In summary, this electronically controlled and valve-controlled composite forklift potential energy recovery system, based on the potential energy recovery of the permanent magnet synchronous motor-generator 6 and the four-quadrant hydraulic pump-motor 8, adds a control module 2 and a proportional flow valve-controlled potential energy recovery module F. The control module 2 controls the second pressure sensor 11, the first two-position two-way solenoid valve 13, the first pressure sensor 18, the proportional flow valve 19, the second two-position two-way solenoid valve 23, the third two-position two-way solenoid valve 25, and the three-position four-way directional valve 29. Through the combined action of the proportional flow valve-controlled potential energy recovery module F and the motor-controlled potential energy module E, potential energy is recovered. Through the combined action of the accumulator energy storage module D and the motor-controlled potential energy module E, potential energy is recovered and reused. This achieves a composite adjustment of the braking torque of the permanent magnet synchronous motor-generator 6 and the opening of the proportional flow valve 19 to adjust the descent speed under different loads and heights, ensuring the stability of potential energy recovery and improving the potential energy recovery efficiency of the hydraulic system under complex working conditions. In the event of a forklift power failure, the lifting hydraulic circuit G can be manually adjusted via the first throttle valve 17 to slowly lower the load, thus unloading the hydraulic system and creating a safer working environment. The accumulator 24 ensures the stability of the hydraulic system and, together with the permanent magnet synchronous motor-generator 6, provides energy to the tilting hydraulic circuit C and the lifting hydraulic circuit G, achieving energy saving and potential energy recovery and reuse.

[0050] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of the equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0051] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A combined electronically controlled and valve-controlled forklift potential energy recovery system, characterized in that: It includes an oil tank (1), a control module (2), an inclined oil circuit (C), an accumulator energy storage module (D), a motor control potential energy module (E), a proportional flow valve control potential energy recovery module (F), a lifting oil circuit (G), a cooling circulation module (H), and a power module (I). The cooling circulation module (H) includes a motor controller (4) electrically connected to a permanent magnet synchronous motor-generator (6) and a cooling circulation pump (5) for water cooling of both. The power module (I) further includes a power simulator (3), a torque sensor (7) and a four-quadrant hydraulic pump-motor (8) in addition to the cooling circulation module (H). The four-quadrant hydraulic pump-motor (8) is coaxially connected to the permanent magnet synchronous motor-generator (6) through the torque sensor (7). The power simulator (3) is connected to the motor controller (4). The oil tank (1) supplies oil to the four-quadrant hydraulic pump-motor (8), and the control module (2), power simulator (3), motor controller (4), permanent magnet synchronous motor-generator (6) and torque sensor (7) are connected via CAN communication; The lifting oil circuit (G) supplies oil to the rodless chambers of the first hydraulic cylinder (15) and the second hydraulic cylinder (16) through the oil outlet of the four-quadrant hydraulic pump-motor (8) via the first check valve (12), the first two-position two-way solenoid valve (13) and the third check valve (14), thereby driving the lifting motion of the forks. The tilting oil circuit (C) and the lifting oil circuit (G) are configured in parallel. The oil outlet of the four-quadrant hydraulic pump-motor (8) passes through the fifth check valve (21) and the three-position four-way directional valve (29) to supply oil to the rodless chamber of the third tilting cylinder (27) and the fourth tilting cylinder (28). The hydraulic oil can be returned to the oil tank (1) by switching through the three-position four-way directional valve (29), thereby driving the forks to tilt. The accumulator energy storage module (D) includes an accumulator (24) and a third two-position two-way solenoid valve (25) located in the opening. It is located between the lifting oil circuit (G) and the tilting oil circuit (C) to recover the potential energy of the load drop and can work with the four-quadrant hydraulic pump-motor (8) to supply energy to the lifting oil circuit (G) and the tilting oil circuit (C). The motor control potential energy module (E) is connected in parallel with the lifting oil circuit (G) and the tilting oil circuit (C). The rodless chambers of the first hydraulic cylinder (15) and the second hydraulic cylinder (16) are connected to the four-quadrant hydraulic pump-motor (8) through the second throttle valve (22) and the second two-position two-way solenoid valve (23). The hydraulic oil input and potential energy recovery of the lifting oil circuit (G) and the tilting oil circuit (C) are completed by inputting signals through the motor controller (4). The proportional flow valve controlled potential energy recovery module (F) is connected in parallel with the motor controlled potential energy module (E), and the proportional flow valve controlled potential energy recovery module (F) is connected in series with the power module (I). The rodless chambers of the first hydraulic cylinder (15) and the second hydraulic cylinder (16) are connected to the four-quadrant hydraulic pump-motor (8) through the proportional flow valve (19) and the fourth check valve (20) in sequence, which can combine the control of the load descent speed. The control module (2) adjusts the braking torque of the permanent magnet synchronous motor-generator (6) and the opening size of the proportional flow valve (19) in coordination with the speed and load height detected by the torque sensor (7) to achieve composite control of the load descent speed: when the forks descend to a high position, the braking torque of the permanent magnet synchronous motor-generator (6) is increased and the opening size of the proportional flow valve (19) is decreased; when the forks descend to a low position, the braking torque of the permanent magnet synchronous motor-generator (6) is decreased and the opening size of the proportional flow valve (19) is increased.

2. The electronically controlled and valve-controlled composite forklift potential energy recovery system according to claim 1, characterized in that: A filter (30) is installed at the front end of the return port of the oil tank (1) to filter the hydraulic oil returning.

3. The electronically controlled and valve-controlled composite forklift potential energy recovery system according to claim 2, characterized in that: An overflow valve (9) is provided between the first check valve (12) and the filter (30). When the pressure in the lifting oil circuit (G) and the tilting oil circuit (C) is greater than the pressure that the overflow valve (9) can withstand, the excess hydraulic oil is returned to the oil tank (1).

4. A combined electronically controlled and valve-controlled forklift potential energy recovery system according to claim 1, 2, or 3, characterized in that: The lifting oil circuit (G) is also connected in parallel with a first throttle valve (17), and the rodless chambers of the first hydraulic cylinder (15) and the second hydraulic cylinder (16) are connected back to the oil tank (1) via the first throttle valve (17).

5. The electronically controlled and valve-controlled composite forklift potential energy recovery system according to claim 1, characterized in that: The accumulator (24) is equipped with a third throttle valve (26) in addition to the third two-position two-way solenoid valve (25) to throttle the hydraulic oil flowing into the accumulator (24) when recovering the potential energy of the load decrease.

6. The electronically controlled and valve-controlled composite forklift potential energy recovery system according to claim 1, characterized in that: The proportional flow valve controlled potential energy recovery module (F), the motor controlled potential energy module (E), and the accumulator energy storage module (D) are all connected to the four-quadrant hydraulic pump-motor (8) after passing through the second check valve (10).

7. The electronically controlled and valve-controlled composite forklift potential energy recovery system according to claim 1, characterized in that: The control module (2) is also equipped with a second pressure sensor (11) and a first pressure sensor (18). The first pressure sensor (18) detects the outlet pressure of the lifting oil passage (G) and the tilting oil passage (C), and the second pressure sensor (11) detects the inlet pressure of the lifting oil passage (G) and the tilting oil passage (C).

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