Potential energy recovery system and method of controlling the same

Abstract

This invention relates to the field of equipment technology with potential energy recovery function, and particularly to a potential energy recovery system and its control method. The potential energy recovery system includes an oil tank, a first power source, a first motor, a lifting cylinder, and a controller. The first power source is a battery. The first motor can switch between motor mode and generator mode. The lifting cylinder is used to drive the lifting components to move up and down. The battery is electrically connected to the first motor, and the first motor is connected to the lifting cylinder. The first interface of the motor is connected to the lifting cylinder through a valve assembly, and the second interface of the motor is connected to the oil tank. A first pressure sensor is installed between the valve assembly and the lifting cylinder, and a second pressure sensor is installed between the motor and the valve assembly. The first pressure sensor, the second pressure sensor, the valve assembly, and the first motor are all electrically connected to the controller. The control method is applied to the above-mentioned potential energy recovery system. The potential energy recovery system and its control method provided by this invention have high energy conversion efficiency.

Description

Technical Field

[0001] This invention relates to the field of equipment technology with potential energy recovery function, and in particular to a potential energy recovery system and its control method. Background Technology

[0002] Many devices with potential energy recovery functions (such as forklifts) use hydraulic systems to drive their lifting components (such as the lifting components of a forklift) to rise and fall, and use the hydraulic system to recover the gravitational potential energy of the lifting components and convert it into other forms of energy (such as electrical energy) for storage.

[0003] Existing devices with potential energy recovery functions add a balance valve to the hydraulic system to prevent the lifting components from stalling. However, the balance valve has a large pressure loss, resulting in low energy recovery efficiency.

[0004] In summary, overcoming the aforementioned deficiencies in the hydraulic systems of existing devices with potential energy recovery capabilities is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide a potential energy recovery system and its control method to alleviate the technical problem of low energy recovery efficiency in hydraulic systems of existing devices with potential energy recovery functions.

[0006] The potential energy recovery system provided by the present invention includes an oil tank, a first power source, a first motor, a motor, a lifting cylinder, and a controller. The first power source is a storage battery, the first motor can switch between motor mode and generator mode, and the lifting cylinder is used to drive the lifting components to lift.

[0007] The battery is electrically connected to the first motor, the first motor is connected to the motor, the motor has a first interface and a second interface, the first interface is connected to the lifting cylinder through a valve assembly, and the second interface is connected to the oil tank.

[0008] A first pressure sensor is installed between the valve assembly and the lifting cylinder, and a second pressure sensor is installed between the motor and the valve assembly. The first pressure sensor, the second pressure sensor, the valve assembly, and the first motor are all electrically connected to the controller.

[0009] Preferably, as one possible implementation, the potential energy recovery system further includes a second power supply, a second motor, and a pump; the second power supply is electrically connected to the second motor, the second motor is connected to the pump, the pump has an inlet and an outlet, the inlet is connected to the oil tank, and the outlet is connected to the first interface of the motor through a one-way valve.

[0010] Preferably, as one possible implementation, the second motor is electrically connected to the controller; or, the pump's displacement is smaller than the motor's displacement.

[0011] Preferably, as one possible implementation, the valve assembly includes a logic valve and a solenoid directional valve. The pipe connection port A of the logic valve is connected to the first interface, the pipe connection port B of the logic valve is connected to the lifting cylinder, the control port C of the logic valve is connected to the oil tank through the solenoid directional valve, and the solenoid directional valve is electrically connected to the controller.

[0012] Preferably, as one possible implementation, the valve assembly further includes an overflow valve located between the lifting cylinder and the oil tank; and / or, the potential energy recovery system further includes a speed limiting valve located between the lifting cylinder and the valve assembly.

[0013] Preferably, as one possible implementation, the first motor has an operating handle, which can adjust the speed of the first motor when the first motor is in motor mode, and can also adjust the torque of the first motor when the first motor is in generator mode.

[0014] Accordingly, the present invention provides a control method for a potential energy recovery system, comprising the following steps:

[0015] When the lifting component needs to rise, the valve assembly opens, and at the same time, the first motor switches to electric motor mode. The drive motor delivers oil from the tank to the lifting cylinder through the valve assembly, causing the lifting cylinder to extend. The extended lifting cylinder then lifts the lifting component. When the lifting component reaches the predetermined position, the valve assembly closes, and the first motor stops operating, leaving the lifting component at its current position.

[0016] When the lifting component needs to descend, the first motor in electric motor mode drives the motor to deliver oil from the tank to the valve assembly, and the pressure at the second pressure sensor gradually increases. When the pressure value sensed by the second pressure sensor reaches the pressure value sensed by the first pressure sensor, the valve assembly opens, and at the same time, the first motor switches to generator mode. The oil in the lifting cylinder flows back to the tank through the valve assembly and the motor in sequence. When the oil passes through the motor, it drives the motor to run. The running motor drives the first motor to generate electricity, and the first motor stores the electrical energy in the battery.

[0017] Preferably, as one possible implementation, the step of the first motor driving the motor in electric motor mode conveying oil from the oil tank to the valve assembly is replaced by the following steps:

[0018] The second motor drives the pump to deliver oil from the tank to the valve assembly.

[0019] Preferably, as one possible implementation, between the step of converting the first motor to electric motor mode and the step of the first motor driving the motor to deliver oil from the oil tank to the lifting cylinder via the valve assembly, the control method further includes the following steps:

[0020] The second motor drives the pump to deliver oil from the tank to the lifting cylinder via a valve assembly. The pump's displacement is smaller than that of the motor.

[0021] Preferably, as one possible implementation, the step of the first motor driving the motor to deliver oil from the oil tank to the lifting cylinder via the valve assembly specifically includes the following steps:

[0022] When the second motor reaches its maximum speed, the first motor drives the oil tank to deliver the oil to the lifting cylinder via the valve assembly.

[0023] Compared with the prior art, the advantages of the present invention are as follows:

[0024] The potential energy recovery system and control method provided by this invention, when the lifting component needs to rise, opens the valve assembly and switches the first motor to electric motor mode. At this time, the battery can supply power to the first motor in electric motor mode, and the first motor in electric motor mode drives the motor to run. The running motor can transport oil in the oil tank to the lifting cylinder through the valve assembly, so that the lifting cylinder extends. After the lifting cylinder extends, it will drive the lifting component to rise. When the lifting component rises to the predetermined position, the valve assembly is closed, so that the lifting cylinder maintains the current state, and then the lifting component stops at the current position. At the same time, the first motor stops running, completing the lifting action of the lifting component.

[0025] When the lifting component needs to descend, the first motor in electric motor mode drives the motor to operate. The operating motor can transport oil from the oil tank towards the valve assembly. Since the valve assembly is in the closed state at this time, the oil between the motor and the valve assembly will have a certain pressure. The second pressure sensor can sense this pressure value. At the same time, the first pressure sensor can sense the pressure value between the lifting cylinder and the valve assembly. When the pressure value sensed by the second pressure sensor reaches the pressure value sensed by the first pressure sensor, the valve assembly is opened and the first motor is switched to generator mode. At this time, the oil in the lifting cylinder will flow back to the oil tank through the valve assembly and the motor under its own oil pressure. When the oil passes through the motor, it will drive the motor to operate. The operating motor can drive the first motor in generator mode to generate electricity. The electricity generated by the first motor can be stored in the battery to achieve the purpose of energy recovery.

[0026] The pressure values ​​sensed by the first and second pressure sensors can both be transmitted to the controller and used as reference signals for the controller to control the valve assembly and the first motor. The opening and closing actions of the valve assembly, as well as the mode switching and start / stop actions of the first motor, can all be performed by the controller, especially when the pressure value sensed by the second pressure sensor reaches the pressure value sensed by the first pressure sensor, the valve assembly opens and the first motor switches to generator mode.

[0027] It should be noted that the presence of the first and second pressure sensors ensures that the oil pressure on both sides of the valve assembly is equal or nearly equal. Only when the valve assembly is open in this state will the oil in the lifting cylinder flow back to the oil tank via the motor. This prevents the lifting component from stalling due to a large difference in oil pressure on both sides of the valve assembly, eliminating the need for a balance valve. Consequently, the loss of hydraulic pressure is minimal and the energy conversion efficiency is high during the descent of the lifting component. Attached Figure Description

[0028] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0029] Figure 1 A schematic diagram of a potential energy recovery system provided in an embodiment of the present invention.

[0030] Icons: 1 - Oil tank; 2 - First power supply; 3 - First motor; 4 - Motor; 5 - Lifting cylinder; 6 - First pressure sensor; 7 - Second pressure sensor; 8 - Second power supply; 9 - Second motor; 10 - Pump; 11 - Logic valve; 12 - Solenoid directional valve; 13 - Relief valve; 14 - Speed ​​limiter valve. Detailed Implementation

[0031] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] In the description of this invention, it should be noted that the terms "upper," "lower," and "inner," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0033] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0034] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings.

[0035] See Figure 1 This embodiment provides a potential energy recovery system, which mainly consists of an oil tank 1, a first power supply 2, a first motor 3, a motor 4, a lifting cylinder 5, and a controller. The first power supply 2 is a battery that can be charged and discharged. The first motor 3 can switch between motor mode and generator mode. When the lifting cylinder 5 extends and retracts, it can drive the lifting components to rise and fall.

[0036] The battery is electrically connected to the first motor 3 to charge the first motor 3 or store the electricity generated by the first motor 3. The first motor 3 is connected to the motor 4. The motor 4 has a first interface and a second interface. The first interface is connected to the lifting cylinder 5 through a valve assembly, and the second interface is connected to the oil tank 1. Thus, the lifting cylinder 5 can be indirectly connected to the oil tank 1 under the action of the valve assembly and the motor 4 to obtain the oil in the oil tank 1 and to drain the oil back to the oil tank 1.

[0037] A first pressure sensor 6 is installed between the motor 4 and the valve assembly to sense the oil pressure between the motor 4 and the valve assembly. A second pressure sensor 7 is installed between the valve assembly and the lifting cylinder 5 to sense the oil pressure between the valve assembly and the lifting cylinder 5. The first pressure sensor 6, the second pressure sensor 7, the valve assembly, and the first motor 3 are all electrically connected to the controller so that the controller can obtain the pressure values ​​sensed by the first pressure sensor 6 and the second pressure sensor 7, and can control the opening and closing of the valve assembly, as well as the mode switching and start / stop of the first motor 3, based on the obtained pressure value signals.

[0038] This embodiment also provides a control method for the above-mentioned potential energy recovery system. When the lifting component needs to rise, the valve assembly is opened and the first motor 3 is switched to motor mode. At this time, the battery can supply power to the first motor 3 in motor mode. The first motor 3 in motor mode drives the motor 4 to run. The running motor 4 can transport the oil in the oil tank 1 to the lifting cylinder 5 through the valve assembly, so that the lifting cylinder 5 extends. After the lifting cylinder 5 extends, it will drive the lifting component to rise. When the lifting component rises to the predetermined position, the valve assembly is closed, so that the lifting cylinder 5 maintains the current state, and then the lifting component stops at the current position. At the same time, the first motor 3 stops running, completing the lifting action of the lifting component.

[0039] When the lifting component needs to descend, the first motor 3, in electric motor mode, drives the motor 4 to operate. The operating motor 4 can transport the oil in the oil tank 1 towards the valve assembly. Since the valve assembly is in a closed state at this time, the oil between the motor 4 and the valve assembly will have a certain pressure. The second pressure sensor 7 can sense the pressure value. At the same time, the first pressure sensor 6 can sense the pressure value between the lifting cylinder 5 and the valve assembly. When the pressure value sensed by the second pressure sensor 7 reaches the pressure value sensed by the first pressure sensor 6, the valve assembly is opened and the first motor 3 is switched to generator mode. At this time, the oil in the lifting cylinder 5 will flow back to the oil tank 1 through the valve assembly and the motor 4 under its own oil pressure. When the oil passes through the motor 4, it will drive the motor 4 to operate. The operating motor 4 can drive the first motor 3 in generator mode to generate electricity. The electricity generated by the first motor 3 can be stored in the battery to achieve the purpose of energy recovery.

[0040] The pressure values ​​sensed by the first pressure sensor 6 and the second pressure sensor 7 can both be transmitted to the controller and used as reference signals for the controller to control the valve assembly and the first motor 3. The opening and closing actions of the valve assembly, as well as the mode switching and start / stop actions of the first motor 3, can all be completed by the controller, especially when the pressure value sensed by the second pressure sensor 7 reaches the pressure value sensed by the first pressure sensor 6, the valve assembly opens and the first motor 3 switches to generator mode.

[0041] It should be noted that the presence of the first pressure sensor 6 and the second pressure sensor 7 allows the oil pressure on both sides of the valve assembly to reach an equal or nearly equal state. After the valve assembly opens in this state, the oil in the lifting cylinder 5 will flow back to the oil tank 1 via the motor 4. In this way, the stalling phenomenon of the lifting component caused by the large difference in oil pressure on both sides of the valve assembly can be prevented. There is no need to add a balance valve. As a result, the loss of hydraulic pressure is small and the energy conversion efficiency is high during the descent of the lifting component.

[0042] The potential energy recovery system provided in this embodiment can also be equipped with a second power supply 8, a second motor 9, and a pump 10. The second power supply 8 is electrically connected to the second motor 9, and the second motor 9 is connected to the pump 10. The pump 10 has an inlet and an outlet. The inlet is connected to the oil tank 1, and the outlet is connected to the first interface of the motor 4 through a one-way valve. Since the first interface of the motor 4 is connected to the lifting cylinder 5 through a valve assembly, the second motor 9 can drive the pump 10 to pump the oil in the oil tank 1 into the lifting cylinder 5.

[0043] Based on the above structure, the step "the first motor 3 in electric motor mode drives the motor 4 to deliver oil from the oil tank 1 to the valve assembly" in the control method of the potential energy recovery system can be replaced by the following step: the second motor 9 drives the pump 10 to deliver oil from the oil tank 1 to the valve assembly. In this way, there is no need to consider the time required for the first motor 3 to switch from electric motor mode to generator mode. When the pressure at the second pressure sensor 7 rises to equal the pressure value sensed by the first pressure sensor 6, the first motor 3 can quickly acquire the gravitational potential energy generated by the descent of the lifting component, thereby further improving the energy conversion efficiency.

[0044] Specifically, the second motor 9 can be electrically connected to the controller so that the controller can control the operation of the second motor 9. For example, when the lifting component needs to descend, the controller can send a start signal to the second motor 9 to start the second motor 9. When the controller obtains a signal that the pressure sensed by the second pressure sensor 7 is equal to the pressure value sensed by the first pressure sensor 6, the controller can control the second motor 9 to stop in time to save the power consumed by the second motor 9. In this way, the degree of automation can be further improved and manpower can be saved.

[0045] Furthermore, the displacement of pump 10 can be set to be less than that of motor 4. Based on this, the control method of the potential energy recovery system includes the following steps between the above-mentioned steps "the first motor 3 switches to electric motor mode" and "the first motor 3 drives motor 4 to deliver the oil in tank 1 to lifting cylinder 5 via valve assembly" during the lifting process of the lifting component: the second motor 9 drives pump 10 to deliver the oil in tank 1 to lifting cylinder 5 via valve assembly. That is, the small displacement pump 10 is used to pump the oil to achieve the micro-movement of the lifting component, and then the large displacement motor 4 is used to deliver the oil to achieve the rapid lifting of the lifting component. Thus, the micro-movement performance of the lifting component at the beginning of the lifting can be optimized, and the lifting speed of the lifting component after a period of time can be guaranteed.

[0046] Specifically, during the lifting process, the first motor 3 can be started when the second motor 9 reaches its maximum speed. The controller can monitor the speed of the second motor 9 in real time. When the controller detects that the speed of the second motor 9 has reached its maximum, the controller controls the first motor 3 to start, which can give full play to the role of the second motor 9 and improve the automation level of the potential energy recovery system.

[0047] Specifically, motor 4 can be a fixed displacement piston motor, and pump 10 can be a gear pump.

[0048] The specific structure of the valve assembly includes a logic valve 11 and a solenoid directional valve 12. The A port of the logic valve 11 is connected to the first interface, the B port of the logic valve 11 is connected to the lifting cylinder 5, and the control port C of the logic valve 11 is connected to the oil tank 1 through the solenoid directional valve 12. The solenoid directional valve 12 is electrically connected to the controller. Thus, the controller can control the operation of the solenoid directional valve 12 to open and close the logic valve 11. In this way, the stability of the potential energy recovery system can be ensured by utilizing the characteristic of the logic valve 11 being suitable for high pressure and high flow environment.

[0049] Furthermore, an overflow valve 13 can be added to the valve assembly and placed between the lifting cylinder 5 and the oil tank 1. Thus, the overflow valve 13 can be used to perform constant pressure overflow, pressure stabilization, system unloading, and safety protection for the potential energy recovery system.

[0050] A speed limiting valve 14 can also be added to the potential energy recovery system and set between the lifting cylinder 5 and the valve assembly. This allows for speed limiting of the oil between the lifting cylinder 5 and the valve assembly, providing an emergency function in case of leakage in the pipeline on the side of the limit valve away from the lifting cylinder 5, and preventing the lifting components from descending uncontrollably.

[0051] Specifically, an operating handle can be installed on the first motor 3. When the first motor 3 is in motor mode, the operating handle can adjust the speed of the first motor 3 so as to adjust the rising speed of the lifting component. The operating handle can also adjust the torque of the first motor 3 when the first motor 3 is in generator mode so as to adjust the falling speed of the lifting component and realize the micro-movement falling of the lifting component.

[0052] In summary, this invention discloses a potential energy recovery system and its control method, which overcomes many technical defects in the hydraulic systems of traditional devices with potential energy recovery functions. The potential energy recovery system and its control method provided in this embodiment can prevent the stalling of the lifting components caused by a large difference in oil pressure on both sides of the valve assembly, and has high energy conversion efficiency.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A potential energy recovery system, characterized in that, It includes an oil tank (1), a first power supply (2), a first motor (3), a motor (4), a lifting cylinder (5), and a controller. The first power supply (2) is a storage battery. The first motor (3) can switch between motor mode and generator mode. The lifting cylinder (5) is used to drive the lifting components to lift. The battery is electrically connected to the first motor (3), the first motor (3) is connected to the motor (4), the motor (4) has a first interface and a second interface, the first interface is connected to the lifting cylinder (5) through a valve assembly, and the second interface is connected to the oil tank (1); A first pressure sensor (6) is installed between the valve assembly and the lifting cylinder (5), and a second pressure sensor (7) is installed between the motor (4) and the valve assembly. The first pressure sensor (6), the second pressure sensor (7), the valve assembly, and the first motor (3) are all electrically connected to the controller. The controller is configured such that when the lifting component needs to be lowered, the first motor (3) in motor mode drives the motor (4) to transport the oil in the oil tank (1) to the valve assembly. At this time, the valve assembly is in the closed state, and the oil between the motor (4) and the valve assembly has a certain pressure. The pressure at the second pressure sensor (7) gradually increases. When the pressure value sensed by the second pressure sensor (7) reaches the pressure value sensed by the first pressure sensor (6), the valve assembly opens. At the same time, the first motor (3) switches to generator mode. The oil in the lifting cylinder (5) flows back to the oil tank (1) through the valve assembly and the motor (4) in sequence. When the oil passes through the motor (4), it drives the motor (4) to run. The running motor (4) drives the first motor (3) to generate electricity. The first motor (3) stores the electrical energy in the battery.

2. The potential energy recovery system according to claim 1, characterized in that, The potential energy recovery system also includes a second power supply (8), a second motor (9), and a pump (10); the second power supply (8) is electrically connected to the second motor (9), the second motor (9) is connected to the pump (10), the pump (10) has an inlet and an outlet, the inlet is connected to the oil tank (1), and the outlet is connected to the first interface of the motor (4) through a one-way valve.

3. The potential energy recovery system according to claim 2, characterized in that, The second motor (9) is electrically connected to the controller; Alternatively, the displacement of the pump (10) is smaller than that of the motor (4).

4. The potential energy recovery system according to claim 1, characterized in that, The valve assembly includes a logic valve (11) and a solenoid directional valve (12). The pipe connection port A of the logic valve (11) is connected to the first interface, the pipe connection port B of the logic valve (11) is connected to the lifting cylinder (5), the control port C of the logic valve (11) is connected to the oil tank (1) through the solenoid directional valve (12), and the solenoid directional valve (12) is electrically connected to the controller.

5. The potential energy recovery system according to claim 4, characterized in that, The valve assembly also includes an overflow valve (13) located between the lifting cylinder (5) and the oil tank (1); And / or, the potential energy recovery system further includes a speed limiting valve (14) located between the lifting cylinder (5) and the valve assembly.

6. The potential energy recovery system according to any one of claims 1-5, characterized in that, The first motor (3) has an operating handle, which can adjust the speed of the first motor (3) when the first motor (3) is in motor mode, and can also adjust the torque of the first motor (3) when the first motor (3) is in generator mode.

7. The potential energy recovery system according to claim 1, characterized in that, The controller is also configured such that when the lifting component needs to rise, the valve assembly opens, and at the same time, the first motor (3) switches to electric motor mode, driving the motor (4) to transport the oil in the oil tank (1) to the lifting cylinder (5) through the valve assembly, so that the lifting cylinder (5) extends, and the extended lifting cylinder (5) drives the lifting component to rise; when the lifting component rises to the predetermined position, the valve assembly closes, and at the same time, the first motor (3) stops running, and the lifting component stops at the current position.

8. The potential energy recovery system according to claim 2, characterized in that, The controller controls the first motor (3) in electric motor mode to drive the motor (4) to deliver the oil in the oil tank (1) to the valve assembly. Alternatively, the controller controls the second motor (9) to drive the pump (10) to deliver the oil in the oil tank (1) to the valve assembly.

9. The potential energy recovery system according to claim 2, characterized in that, The controller is also configured such that when the lifting component needs to rise, the valve assembly opens, and at the same time, the first motor (3) switches to electric motor mode and drives the motor (4) to transport the oil in the oil tank (1) to the lifting cylinder (5) via the valve assembly. The controller is further configured to: between the first motor (3) switching to motor mode and the drive motor (4) delivering oil from the oil tank (1) to the lifting cylinder (5) via the valve assembly, control the second motor (9) to drive the pump (10) to deliver oil from the oil tank (1) to the lifting cylinder (5) via the valve assembly, wherein the displacement of the pump (10) is smaller than that of the motor (4).

10. The potential energy recovery system according to claim 9, characterized in that, The controller controls the first motor (3) to drive the motor (4) to deliver the oil in the oil tank (1) to the lifting cylinder (5) via the valve assembly. Specifically: When the second motor (9) reaches its maximum speed, the controller controls the first motor (3) to drive the motor (4) to deliver the oil in the oil tank (1) to the lifting cylinder (5) via the valve assembly.

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