Disclosure of Invention
The invention discloses a potential energy recovery system of a split type electro-hydraulic drive forklift and the split type electro-hydraulic drive forklift, which have the advantages of simple structure and convenience in operation and aim to solve the problems.
The invention adopts the following scheme: a potential energy recovery system of a split type electro-hydraulic drive forklift comprises a lifting oil way, an inclined oil way, a hydraulic drive and energy recovery assembly and an electric drive and energy recovery assembly; wherein,
the lifting oil way comprises a first hydraulic oil cylinder and a second hydraulic oil cylinder, and the first hydraulic oil cylinder and the second hydraulic oil cylinder are suitable for being connected with a fork piece of a forklift and driving the fork piece to move up and down;
the electric driving and energy recovery assembly is connected with the hydraulic oil tank, the lifting oil way and the inclined oil way and is used for inputting and recovering hydraulic oil to the lifting oil way and the inclined oil way;
the hydraulic driving and energy recovery assembly and the electric driving and energy recovery assembly are arranged in parallel, are also connected to the lifting oil way and the inclined oil way, and are used for inputting and recovering hydraulic oil to the lifting oil way and the inclined oil way;
the inclined oil way comprises an inclined hydraulic oil cylinder which is suitable for being connected with the fork piece, and the inclined oil way is configured to be matched with the first hydraulic oil cylinder and the second hydraulic oil cylinder of the lifting oil way to control the movement of the fork piece together.
Further, the electric driving and energy recovering assembly comprises an electric motor-generator, a hydraulic pump-motor, a motor controller and a power supply system; wherein the electric motor-generator and the hydraulic pump-motor are coaxially arranged, the generator and the motor constitute an electrical energy recovery assembly, and the electric motor and the hydraulic pump constitute an electrical driving assembly; the motor-generator is electrically connected with the motor controller, and the motor controller is in communication connection with the power supply system through a CAN.
Further, the power supply system comprises a pre-charging controller, a BMS battery management system and a high-voltage lithium ion battery which are connected in series.
Furthermore, the lifting oil way also comprises a speed limiting valve, a first two-position two-way electromagnetic valve, a first one-way valve and a hydraulic oil tank; the oil outlet of the hydraulic oil tank is communicated with the first one-way valve inlet, the first one-way valve outlet is communicated with the inlet of the hydraulic pump-motor, the hydraulic pump-motor outlet is communicated with the first two-position two-way electromagnetic valve inlet, the first two-position two-way electromagnetic valve outlet is communicated with the speed limiting valve inlet, the speed limiting valve outlet is communicated with rodless cavities of the first hydraulic oil cylinder and the second hydraulic oil cylinder, and rod cavities of the first hydraulic oil cylinder and the second hydraulic oil cylinder are communicated with the oil return port of the hydraulic oil tank.
Furthermore, the speed limiting valve comprises a second one-way valve, a pressure reducing valve and a throttle valve, and the second one-way valve is connected with the pressure reducing valve in parallel through a pipeline; the speed limiting valve is configured as follows: when the lifting oil way is descended, the hydraulic oil is transmitted to the first two-position two-way electromagnetic valve through the pressure reducing valve and the throttle valve.
Furthermore, the inclined oil way comprises a second two-position two-way electromagnetic valve, a three-position four-way valve, an inclined hydraulic oil cylinder and a hydraulic oil tank; the inlet of the second two-position two-way solenoid valve is communicated with a first bypass port led out by a pipeline between the outlet of the hydraulic pump and the motor and the inlet of the first two-position two-way solenoid valve, the outlet of the second two-position two-way solenoid valve is communicated with a first port of the three-position four-way valve, a second port of the three-position four-way valve is communicated with a rod cavity of the inclined hydraulic oil cylinder, a rodless cavity of the inclined hydraulic oil cylinder is communicated with a third port of the three-position four-way valve, and a fourth port of the three-position four-way valve is communicated with an oil return port of the hydraulic oil tank.
Furthermore, the hydraulic driving and energy recovery assembly comprises a third one-way valve, a third two-position two-way electromagnetic valve, a hydraulic accumulator and a fourth two-position two-way electromagnetic valve; the inlet of the third check valve is communicated with a second bypass interface led out by a pipeline between the outlet of the second two-position two-way electromagnetic valve and a first interface of the three-position four-way valve, the outlet of the third check valve is communicated with the inlet of the third two-position two-way electromagnetic valve, the outlet of the third two-position two-way electromagnetic valve is communicated with the hydraulic accumulator, the inlet of the fourth two-position two-way electromagnetic valve is communicated with a third bypass interface led out by a pipeline between the outlet of the third check valve and the inlet of the third two-position two-way electromagnetic valve, and the outlet of the fourth two-position two-way electromagnetic valve is communicated with a fourth bypass interface led out by a pipeline between the outlet of the first check valve and the inlet of the hydraulic pump-motor.
Furthermore, a first overflow valve is arranged in the lifting oil way, an inlet of the first overflow valve is communicated with a fifth bypass interface led out by a pipeline between an outlet of the hydraulic pump and the motor and the first bypass interface, and an outlet of the first overflow valve is communicated with an oil return port of the hydraulic oil tank; and a second overflow valve is arranged in the hydraulic driving and recovering assembly, the inlet of the second overflow valve is communicated with a sixth bypass interface led out by a pipeline between the outlet of the third two-position two-way electromagnetic valve and the inlet of the hydraulic accumulator, and the outlet of the second overflow valve is communicated with an oil return port of the hydraulic oil tank.
Further, the lifting oil way and the inclined oil way are arranged in parallel.
The invention also provides a compound type electro-hydraulic driving forklift, which comprises a fork piece and any one of the compound type electro-hydraulic driving forklift potential energy recovery systems, wherein a first hydraulic rod oil cylinder, a second hydraulic oil cylinder and a push rod of an inclined hydraulic oil cylinder of the compound type electro-hydraulic driving forklift potential energy recovery system are connected with the fork piece and are configured to drive the fork piece to move up and down and rotate obliquely.
By adopting the technical scheme, the invention can obtain the following technical effects: on the basis of realizing an electric driving and potential energy recovery integrated energy-saving system by combining an electric motor-generator and a hydraulic pump-motor, a hydraulic energy accumulator is introduced to realize an energy-saving technology of hydraulic driving and energy recovery, and the energy recovery capability of the hydraulic system of the electric forklift is further improved; the oil circuit under each working condition is separated by the two-position two-way electromagnetic valve, so that the hydraulic oil is definitely conveyed to the corresponding execution part, and the loss of the oil energy on the oil circuit is reduced. Meanwhile, the hydraulic accumulator supplies oil to enable the inclined system to have enough hydraulic oil supply when the lifting system recovers potential energy, and composite action is realized; electro-hydraulic combined driving and energy recovery overcome the defects of large oil energy loss, high temperature rise and the like of a hydraulic system of a traditional electric forklift, solve the problem that a tilting system cannot operate in the electric energy recovery process, improve the controllability of the electric forklift and the stability of the hydraulic system, further realize the electromotion and intellectualization of the traditional forklift and meet the requirements of energy conservation and emission reduction of the country more.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings of the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations and positional relationships based on those shown in the drawings, and are used only for convenience of description and simplicity of description, and do not indicate or imply that the equipment or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be considered as limiting the present invention.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.
In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.
Examples
With reference to fig. 1, the embodiment provides a split type electro-hydraulic forklift, which includes a fork member and a split type electro-hydraulic forklift potential energy recovery system, wherein push rods of a first hydraulic cylinder 10, a second hydraulic cylinder 11 and an inclined hydraulic cylinder 14 of the split type electro-hydraulic forklift potential energy recovery system are connected to the fork member and configured to drive the fork member to move up and down and rotate in an inclined manner. The potential energy recovery system of the split type electro-hydraulic drive forklift comprises a lifting oil way E, an inclined oil way F, a hydraulic drive and energy recovery assembly C and an electric drive and energy recovery assembly D; the lifting oil way E comprises a first hydraulic oil cylinder 10 and a second hydraulic oil cylinder 11, and the first hydraulic oil cylinder 10 and the second hydraulic oil cylinder 11 are suitable for being connected with a fork piece of a forklift and drive the fork piece to move up and down; the electric driving and energy recovery assembly D is connected with the hydraulic oil tank 1, the lifting oil way E and the inclined oil way F, and is used for conveying hydraulic oil in the hydraulic oil tank 1 to the lifting oil way E, driving the hydraulic oil cylinder to move and recovering the hydraulic oil; the hydraulic driving and energy recovery assembly C is connected with the lifting oil way E and the inclined oil way F and is used for driving the lifting oil way E and the inclined oil way F and recovering hydraulic oil; the inclined oil path F comprises an inclined hydraulic oil cylinder 14 suitable for being connected with the fork piece, and the inclined oil path F is configured to be matched with the lifting oil path E and control the movement of the fork piece.
In this embodiment, the hydraulic cylinder includes a rod cavity and a rodless cavity, and when hydraulic oil is input into the rodless cavity, the hydraulic cylinder can push a push rod of the hydraulic cylinder to move upward. The lifting oil circuit E and the inclined oil circuit F are arranged in parallel, so that the lifting oil circuit E and the inclined oil circuit F can simultaneously control the inclined lifting of the fork member and can also independently and respectively control the lifting or the inclined movement.
In the present embodiment, the electric drive and energy recovery assembly D includes an electric motor-generator 5, a hydraulic pump-motor 6, a motor controller 4, and a power supply system 3; wherein the motor controller 4 (M/GCU), the electric motor-generator 5 and the hydraulic pump-motor 6 are coaxially arranged, the generator and the motor constitute an electric energy recovery assembly, and the electric motor and the hydraulic pump constitute an electric drive assembly; the motor-generator 5 is electrically connected with the motor controller, and the motor controller 4 is in communication connection with a power supply system through a CAN. And the power supply system 3 comprises a pre-charging controller, a BMS battery management system and a high-voltage lithium ion battery which are connected in series. Here, the motor-generator 5 and the hydraulic pump-motor 6 are coupled together, respectively.
The lifting oil circuit E also comprises a speed limiting valve 9, a first two-position two-way electromagnetic valve 8, a first one-way valve 2 and a hydraulic oil tank 1; the oil outlet of the hydraulic oil tank 1 is communicated with the inlet of the first check valve 2, the outlet of the first check valve 2 is communicated with the inlet of the hydraulic pump-motor 6, the outlet of the hydraulic pump-motor 6 is communicated with the inlet of the first two-position two-way electromagnetic valve 8, the outlet of the first two-position two-way electromagnetic valve 8 is communicated with the inlet of the speed limiting valve 9, the outlet of the speed limiting valve 9 is communicated with the rodless cavities of the first hydraulic oil cylinder 10 and the second hydraulic oil cylinder 11, and the rod cavities of the first hydraulic oil cylinder 10 and the second hydraulic oil cylinder 11 are communicated with the oil return port of the hydraulic oil tank 1.
The speed limiting valve 9 comprises a second one-way valve, a pressure reducing valve and a throttle valve, and the second one-way valve is connected with the pressure reducing valve in parallel through a pipeline; the speed limiting valve 9 is configured as follows: when the lifting oil way E rises, hydraulic oil is transmitted to the rodless cavities of the first hydraulic oil cylinder 10 and the second lifting hydraulic oil cylinder through the second one-way valve, and when the lifting oil way E falls, hydraulic oil is transmitted to the first two-position two-way electromagnetic valve 8 through the pressure reducing valve and the throttle valve. The speed limiting valve is used for controlling the speed of hydraulic oil, so that the speed of the fork piece can be controlled.
The inclined oil way F comprises a second two-position two-way electromagnetic valve 12, a three-position four-way valve 13, an inclined hydraulic oil cylinder 14 and a hydraulic oil tank 1; the inlet of the second two-position two-way solenoid valve 12 is communicated with a first bypass port led out by a pipeline between the outlet of the hydraulic pump-motor 6 and the inlet of the first two-position two-way solenoid valve 8, the outlet of the second two-position two-way solenoid valve 12 is communicated with a first port P of the three-position four-way valve 13, a second port A of the three-position four-way valve 13 is communicated with a rod cavity of the inclined hydraulic oil cylinder 14, a rodless cavity of the inclined hydraulic oil cylinder 14 is communicated with a third port B of the three-position four-way valve 13, and a fourth port T of the three-position four-way valve 13 is communicated with an oil return port of the hydraulic oil tank 1.
The hydraulic driving and energy recovering component C comprises a third one-way valve 15, a third two-position two-way electromagnetic valve 16, a hydraulic energy accumulator 18 and a fourth two-position two-way electromagnetic valve 19; the inlet of the third check valve 15 is communicated with a second bypass port led out by a pipeline between the outlet of the second two-position two-way solenoid valve 12 and a first port of the three-position four-way valve 13, the outlet of the third check valve 15 is communicated with the inlet of the third two-position two-way solenoid valve 16, the outlet of the third two-position two-way solenoid valve 16 is communicated with the hydraulic accumulator 18, the inlet of the fourth two-position two-way solenoid valve 19 is communicated with a third bypass port led out by a pipeline between the outlet of the third check valve 15 and the inlet of the third two-position two-way solenoid valve 16, and the outlet of the fourth two-position two-way solenoid valve 19 is communicated with a fourth bypass port led out by a pipeline between the outlet of the first check valve 2 and the inlet of the hydraulic pump-motor 6.
A first overflow valve 7 is arranged in the lifting oil way E, an inlet of the first overflow valve 7 is communicated with a fifth bypass interface led out by a pipeline between an outlet of the hydraulic pump-motor 6 and the first bypass interface, and an outlet of the first overflow valve 7 is communicated with an oil return port of the hydraulic oil tank 1; and a second overflow valve 17 is arranged in the hydraulic driving and recovering assembly, the inlet of the second overflow valve 17 is communicated with a sixth bypass interface led out by a pipeline between the outlet of the third two-position two-way electromagnetic valve 16 and the inlet of the hydraulic energy accumulator 18, and the outlet of the second overflow valve 17 is communicated with an oil return port of the hydraulic oil tank 1.
The working principle of the invention is as follows:
firstly, when the electric forklift is lifted independently:
1. when the load of the lifting system rises:
(1) the hydraulic accumulator 18 is in a non-pressure state, no matter no load, light load or heavy load, at this time, the hydraulic driving and energy recovery component C cannot supply oil, and is driven by the electric driving and energy recovery component D alone. The first two-position two-way solenoid valve 8 is in a right-position conducting state. Hydraulic oil is transmitted to a first hydraulic oil cylinder 10 and a second hydraulic oil cylinder 11 rodless cavity from a hydraulic oil tank 1 through a first one-way valve 2, a hydraulic pump-motor 6, a first two-position two-way electromagnetic valve 8 and a speed limiting valve 9 to complete lifting.
(2) The hydraulic accumulator 18 is under pressure whether empty, lightly loaded or heavily loaded.
a. The lifting speed meets the requirement, and the lifting is driven by the hydraulic driving and energy recovery component C independently. The first two-position two-way solenoid valve 8 is in a right-position conducting state, the third two-position two-way solenoid valve 16 is in a right-position conducting state, and the fourth two-position two-way solenoid valve 19 is in an upper-position conducting state. The hydraulic oil is transmitted to the first hydraulic oil cylinder 10 and the second hydraulic oil cylinder 11 from the hydraulic accumulator 18 through the third two-position two-way electromagnetic valve 16, the fourth two-position two-way electromagnetic valve 19, the hydraulic pump-motor 6, the first two-position two-way electromagnetic valve 8 and the speed limiting valve 9 to complete the lifting action.
b. The lifting speed does not meet the requirement, and the electric driving and energy recovery D and the hydraulic driving and energy recovery component C are driven in a combined mode. The first two-position two-way solenoid valve 8 is in a right-position conducting state, the third two-position two-way solenoid valve 16 is in a right-position conducting state, and the fourth two-position two-way solenoid valve 19 is in an upper-position conducting state. The hydraulic oil is transmitted to the first hydraulic oil cylinder 10 and the second hydraulic oil cylinder 11 from the hydraulic accumulator 18 through the third two-position two-way electromagnetic valve 16, the fourth two-position two-way electromagnetic valve 19, the hydraulic pump-motor 6, the first two-position two-way electromagnetic valve 8 and the speed limiting valve 9 to complete the lifting action. At this time, the motor-generator 5 compensates along with the change of the lifting speed, drives the hydraulic pump-motor 6 to realize the regulation and control of the lifting speed, and simultaneously supplements oil supply.
2. When the load of the lifting system is lowered:
(1) the hydraulic accumulator 18 is in a non-pressure state, no matter no load, light load or heavy load, and the hydraulic driving and energy recovery component C is used for recovering energy independently. The first two-position two-way solenoid valve 8 is in a right-position conducting state, the third two-position two-way solenoid valve 16 is in a right-position conducting state, and the fourth two-position two-way solenoid valve 19 is in an upper-position conducting state. The hydraulic oil in the rodless cavities of the first hydraulic oil cylinder 10 and the second hydraulic oil cylinder 11 is transmitted to a hydraulic accumulator 18 for recycling through a speed limiting valve 9, a first two-position two-way electromagnetic valve 8, a hydraulic pump-motor 6, a fourth two-position two-way electromagnetic valve 19 and a third two-position two-way electromagnetic valve 16.
(2) The hydraulic accumulator 18 is under pressure.
a. When the load is heavy, the electric driving and energy recovery D and the hydraulic driving and energy recovery component C are combined to recover energy. The first two-position two-way solenoid valve 8 is in a right-position conducting state, the third two-position two-way solenoid valve 16 is in a right-position conducting state, and the fourth two-position two-way solenoid valve 19 is in an upper-position conducting state. The hydraulic oil in the rodless cavities of the first hydraulic oil cylinder 10 and the second hydraulic oil cylinder 11 is transmitted to a hydraulic energy accumulator 18 for recycling through a speed limiting valve 9, a first two-position two-way electromagnetic valve 8, a hydraulic pump-motor 6, a fourth two-position two-way electromagnetic valve 19 and a third two-position two-way electromagnetic valve 16. At this time, the hydraulic pump-motor 6 drives the motor-generator 5 to rotate reversely to recover partial potential energy.
b. When the vehicle is in no-load or light-load, the hydraulic driving and energy recovery component C is used for recovering energy independently. The first two-position two-way solenoid valve 8 is in a right-position conducting state, the third two-position two-way solenoid valve 16 is in a right-position conducting state, and the fourth two-position two-way solenoid valve 19 is in an upper-position conducting state. The hydraulic oil in the rodless cavities of the first hydraulic oil cylinder 10 and the second hydraulic oil cylinder 11 is transmitted to a hydraulic accumulator 18 for recycling through a speed limiting valve 9, a first two-position two-way electromagnetic valve 8, a hydraulic pump-motor 6, a fourth two-position two-way electromagnetic valve 19 and a third two-position two-way electromagnetic valve 16. The control of the lowering speed is now effected by the motor-generator 5.
Secondly, when the electric forklift independently inclines:
1. the hydraulic accumulator 18 is in a non-pressure state, no matter no load, light load or heavy load, at this time, the hydraulic driving and energy recovery assembly C cannot supply oil, and is driven by the electric driving and energy recovery assembly D alone. The second two-position two-way electromagnetic valve 12 is in an upper conduction state. The hydraulic oil is transmitted to the tilting hydraulic oil cylinder 14 from the hydraulic oil tank 1 through the first check valve 2, the hydraulic pump-motor 6, the second two-position two-way electromagnetic valve 12 and the three-position four-way valve 13 to complete the tilting action. When the three-position four-way valve 13 is in the right position when the hydraulic oil tank tilts forwards, a port P of the three-position four-way valve is connected with a port B to transmit oil to a rodless cavity of the inclined hydraulic oil cylinder 14, and a port T of the three-position four-way valve is connected with a port A to transmit the oil in a rod cavity of the inclined hydraulic oil cylinder 14 to the hydraulic oil tank 1; when the hydraulic cylinder tilts backwards, the port P is connected with the port A to transmit oil to a rod cavity of the inclined hydraulic cylinder 14, and the port T is connected with the port B to transmit the oil in a rodless cavity of the inclined hydraulic cylinder 14 to the hydraulic oil tank 1.
2. The hydraulic accumulator 18 is under pressure, no matter no load, light load or heavy load, and is driven by the hydraulic driving and energy recovering assembly C alone.
a. When the pressure at the inlet end of the third check valve 15 is greater than the pressure at the outlet end, the second two-position two-way solenoid valve 12 is in an upper conduction state, the third two-position two-way solenoid valve 16 is in a right conduction state, and the fourth two-position two-way solenoid valve 19 is in an upper conduction state. The hydraulic oil is transmitted from the energy accumulator 18 to the tilting hydraulic cylinder 14 through the third two-position two-way solenoid valve 12, the fourth two-position two-way solenoid valve 19, the hydraulic pump-motor 6, the second two-position two-way solenoid valve 12 and the three-position four-way valve 13 to complete the tilting action. The forward tilting or backward tilting is controlled by switching the position of a three-position four-way valve 13.
b. When the pressure at the inlet end of the third check valve 15 is lower than the pressure at the outlet end, the third two-position two-way electromagnetic valve 16 is in a right-position conducting state. The hydraulic oil is transmitted from the energy accumulator 18 to the tilting hydraulic cylinder 14 through the third two-position two-way solenoid valve 16, the third check valve 15 and the three-position four-way valve 13 to complete the tilting action. The forward tilting or backward tilting is controlled by switching the position of a three-position four-way valve 13.
Thirdly, when the electric forklift is lifted and inclined to operate in a combined mode:
1. when the load of the lifting system rises:
(1) the hydraulic accumulator 18 is in a non-pressure state, no matter no load, light load or heavy load, at this time, the hydraulic driving and energy recovery assembly C cannot supply oil, and is driven by the electric driving and energy recovery assembly D alone. The first two-position two-way solenoid valve 8 is in a right-position conducting state, and the second two-position two-way solenoid valve 12 is in an upper-position conducting state. Hydraulic oil is transmitted to a rodless cavity of a first hydraulic oil cylinder 10 and a second hydraulic oil cylinder 11 from a hydraulic oil tank 1 through a first one-way valve 2, a hydraulic pump-motor 6, a first two-position two-way electromagnetic valve 8 and a speed limiting valve 9 to complete lifting action; the signal is transmitted to a tilting hydraulic oil cylinder 14 through a bypass via a second two-position two-way electromagnetic valve 12 and a three-position four-way valve 13 to complete the tilting action. The forward tilting or backward tilting is controlled by switching the position of a three-position four-way valve 13.
(2) The hydraulic accumulator 18 is under pressure whether empty, lightly loaded or heavily loaded.
a. When the pressure at the inlet end of the third check valve 15 is greater than the pressure at the outlet end, the electric driving and energy recovery assembly D and the hydraulic driving and energy recovery assembly C are driven in a combined manner. The first two-position two-way solenoid valve 8 is in a right-position conducting state, the second two-position two-way solenoid valve 12 is in an upper-position conducting state, the third two-position two-way solenoid valve 16 is in a right-position conducting state, and the fourth two-position two-way solenoid valve 19 is in an upper-position conducting state. The hydraulic oil is transmitted to the first hydraulic oil cylinder 10 and the second hydraulic oil cylinder 11 from the hydraulic accumulator 18 through the third two-position two-way electromagnetic valve 16, the fourth two-position two-way electromagnetic valve 19, the hydraulic pump-motor 6, the first two-position two-way electromagnetic valve 8 and the speed limiting valve 9 to complete the lifting action. The signal is transmitted to a tilting hydraulic oil cylinder 14 through a bypass via a second two-position two-way electromagnetic valve 12 and a three-position four-way valve 13 to complete the tilting action. The forward tilting or backward tilting is regulated by switching the position of the three-position four-way valve 13, and the motor-generator 5 realizes the regulation of the composite action speed and supplements oil supply at the same time.
b. When the pressure at the inlet end of the third check valve 15 is smaller than the pressure at the outlet end, the hydraulic driving and energy recovery assembly C is used for driving the third check valve alone. The first two-position two-way solenoid valve 8 is in a right-position conducting state, the third two-position two-way solenoid valve 16 is in a right-position conducting state, and the fourth two-position two-way solenoid valve 19 is in an upper-position conducting state. The hydraulic oil is transmitted to the tilting hydraulic oil cylinder 14 from the hydraulic accumulator 18 through the third two-position two-way solenoid valve 16, the third check valve 15 and the three-position four-way valve 13 to complete the tilting action. The forward tilting or backward tilting is controlled by switching the position of a three-position four-way valve 13. The hydraulic oil is transmitted to the first hydraulic oil cylinder 10 and the second hydraulic oil cylinder 11 from the hydraulic accumulator 18 through the third two-position two-way electromagnetic valve 16, the fourth two-position two-way electromagnetic valve 19, the hydraulic pump-motor 6, the first two-position two-way electromagnetic valve 8 and the speed limiting valve 9 to complete the lifting action.
2. When the load of the lifting system is lowered:
(1) the hydraulic accumulator 18 is in a non-pressurized state, no matter no load, light load or heavy load, and energy is recovered by the hydraulic driving and energy recovering assembly C alone. The first two-position two-way solenoid valve 8 is in a right-position conducting state, the third two-position two-way solenoid valve 16 is in a right-position conducting state, and the fourth two-position two-way solenoid valve 19 is in an upper-position conducting state. The hydraulic oil in the rodless cavities of the first hydraulic oil cylinder 10 and the second hydraulic oil cylinder 11 is transmitted to the inclined hydraulic oil cylinder through the speed limiting valve 9, the first two-position two-way electromagnetic valve 8, the second two-position two-way electromagnetic valve 12 and the three-position four-way valve 13 to finish the inclination action. The forward tilting or backward tilting is controlled by switching the position of a three-position four-way valve 13. The redundant hydraulic oil is transmitted to the hydraulic accumulator 18 for recycling through the hydraulic pump-motor 6, the fourth two-position two-way electromagnetic valve 19 and the third two-position two-way electromagnetic valve 16.
(2) The hydraulic accumulator 18 is under pressure whether empty, lightly loaded or heavily loaded.
a. When the pressure at the inlet end of the third check valve 15 is higher than the pressure at the outlet end, the hydraulic driving and energy recovery assembly C is used for energy recovery alone. The first two-position two-way solenoid valve 8 is in a right-position conducting state, the second two-position two-way solenoid valve 12 is in an upper-position conducting state, the third two-position two-way solenoid valve 16 is in a right-position conducting state, and the fourth two-position two-way solenoid valve 19 is in an upper-position conducting state. The hydraulic oil in the rodless cavities of the first hydraulic oil cylinder 10 and the second hydraulic oil cylinder 11 is transmitted to the inclined hydraulic oil cylinder through the speed limiting valve 9, the first two-position two-way electromagnetic valve 8, the second two-position two-way electromagnetic valve 12 and the three-position four-way valve 13 to finish the inclination action. The forward tilting or backward tilting is controlled by switching the position of a three-position four-way valve 13. The redundant hydraulic oil is transmitted to the hydraulic accumulator 18 for recycling through the hydraulic pump-motor 6, the fourth two-position two-way electromagnetic valve 19 and the third two-position two-way electromagnetic valve 16.
b. When the pressure at the inlet end of the third check valve 15 is smaller than the pressure at the outlet end, the hydraulic driving and energy recovery assembly C recovers energy independently. The first two-position two-way solenoid valve 8 is in a right-position conducting state, the third two-position two-way solenoid valve 16 is in a right-position conducting state, and the fourth two-position two-way solenoid valve 19 is in an upper-position conducting state. The hydraulic oil in the rodless cavities of the first hydraulic oil cylinder 10 and the second hydraulic oil cylinder 11 is transmitted to the inclined hydraulic oil cylinder through a speed-limiting valve 9, a first two-position two-way electromagnetic valve 8, a hydraulic pump-motor 6, a fourth two-position two-way electromagnetic valve 19, a third one-way valve 15 and a three-position four-way valve 13 to finish the inclination action. The forward tilting or backward tilting is controlled by switching the position of a three-position four-way valve 13. The redundant hydraulic oil is transmitted to the hydraulic accumulator 18 for recycling through the third two-position two-way electromagnetic valve 16.
On the basis that the electric driving and potential energy recovery integrated energy-saving system is realized by the motor-generator 5 and the hydraulic pump-motor 6 together, the hydraulic energy accumulator 18 is introduced to realize the energy-saving technology of hydraulic driving and energy recovery, so that the energy recovery capability of the hydraulic system of the electric forklift is further improved; the oil circuit under each working condition is separated by the two-position two-way electromagnetic valve, so that the hydraulic oil is definitely conveyed to the corresponding execution part, and the loss of the oil energy on the oil circuit is reduced. Meanwhile, the hydraulic accumulator 18 supplies oil to enable the inclined system to have enough hydraulic oil supply when the lifting system recovers potential energy, and composite action is realized; electro-hydraulic combined driving and energy recovery overcome the defects of large oil energy loss, high temperature rise and the like of a hydraulic system of a traditional electric forklift, solve the problem that a tilting system cannot operate in the electric energy recovery process, improve the controllability of the electric forklift and the stability of the hydraulic system, further realize the electromotion and intellectualization of the traditional forklift and meet the requirements of energy conservation and emission reduction of the country more.
The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above-mentioned embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention.