CN107986196A - A kind of electri forklift potential energy regenerating unit - Google Patents

Abstract

The invention discloses a kind of electri forklift potential energy regenerating unit, including motor load system, Buck conversion circuit, main control module, constant-current control module and power module；The constant-current control module and power module are electrically connected, and the motor load system, Buck conversion circuit, power module and main control module are electrically connected, and are controlled by it；The present invention proposes that load, which is greatly reduced, falls fever after rise, and realizes a kind of electri forklift potential energy regenerating unit that energy regeneration utilizes.

Description

A potential energy regeneration device for an electric forklift

technical field

The invention relates to the field of electric vehicles, in particular to an energy-saving device for electric forklifts based on storage batteries and supercapacitors.

Background technique

In recent years, the scale of my country's logistics industry has continued to grow rapidly. In 2015, the total amount of social logistics in the country reached 219.2 trillion yuan, an increase of 3.68 times compared with 2006, with an average annual growth rate of 15.58%. The total cost of social logistics accounted for 16% of the national GDP. Among them, forklifts are the core handling equipment in the logistics industry. China's forklift industry has grown at an average annual rate of 30% for more than ten consecutive years, and has become the world's largest forklift production base. However, global warming and energy issues are becoming increasingly prominent, and high fuel prices have prompted the forklift industry to solve the current problem of large fuel consumption. In addition, since the lifting system is driven by hydraulic pressure, most of the lost potential energy is transferred to the throttling loss of the hydraulic system, which not only causes energy waste and reduces the continuous working time of the forklift, but also causes the hydraulic oil to heat up, damages the life of the parts, and reduces the system efficiency. Therefore, it is of great significance to recover the gravitational potential energy when the forklift cargo falls.

In addition, due to its working characteristics, the lifting system of the forklift requires frequent reciprocating motions. The moment when the cargo is lifted and the lifting is accelerated, a large current output of the energy source is required. In electric forklifts, the instantaneous high current output has a great impact on the battery, which seriously damages the life of the battery. Therefore, in the energy management scheme, it is necessary to reasonably match the energy output at the moment of lifting the cargo and when the lifting is accelerating, so as to prolong the service life of the battery.

For the potential energy recovery of electric forklifts, the existing technologies are as follows:

Taking Chinese patent 200610042603.3 as an example, by controlling the working mode of the motor to regulate the working state of the forklift lifting system and recover energy, it is necessary to achieve high-precision matching and response between the control system and the motor. The principle of the control system is complex and the realizability requirements higher.

Taking Chinese patent 201620398878.X as an example, through three different forklift fork lowering speed adjustment methods, partial potential energy recovery is realized. Potential energy can be recovered when there is variable speed and volumetric speed regulation, so the potential energy during throttling speed regulation cannot be effectively recovered. Potential energy recovery efficiency is not high.

Taking Chinese patent 201510772125.0 as an example, the potential energy of the forklift lifting system is recovered by connecting the accumulator and the recovery oil circuit in the hydraulic system, so it is necessary to greatly change the oil circuit model of the overall hydraulic system in the forklift lifting system, and the forklift lifting system The changes are large, the operation is complicated, and the replaceability is small.

Taking Chinese patent 201620398878.X as an example, by using a newly designed reversing valve during the descent of the lifting system and using the battery to supply power to the motor, part of the potential energy is recovered by reversing the oil pump to drive the motor to generate electricity during the descent. The implementation conditions of this method Strict, it is necessary to purchase a special reversing valve made by the inventor/enterprise, which has no versatility.

Contents of the invention

In view of the above technical problems, the present invention proposes a potential energy regeneration device for an electric forklift.

In order to solve the above technical defects, the technical solution of the present invention is as follows:

A potential energy regeneration device for an electric forklift, comprising a motor load system, a step-down conversion circuit, a main control module, a constant current control module and a power supply module; the constant current control module is electrically connected to the power supply module, and the motor load system , The step-down conversion circuit, the power supply module are electrically connected with the main control module and are controlled by it;

The motor load system includes a double-acting motor-generator, a double-acting oil pump-hydraulic motor, an oil cylinder, a third relay and auxiliary equipment, and the double-acting motor-generator is connected with a double-acting oil pump-hydraulic motor and the third relay, Double-acting oil pump-hydraulic motor is connected with oil cylinder and auxiliary equipment;

The step-down conversion circuit includes an inductor, a second diode and a second MOS tube, the drain of the second MOS tube is connected to the motor load system, and the source of the second MOS tube is connected to the inductor, the second diode tube connection, the gate of the second MOS tube is connected to the main control module;

The main control module includes a controller, a first relay, a second relay, a first voltage detection module, and a second voltage detection module; the first relay, the second relay, the first voltage detection module, and the second voltage detection module It is electrically connected with the controller and controlled by it; the controller receives the main switch signal, the lifting signal, and the lowering signal;

The power module includes a storage battery, a first diode, a first MOS tube, and a supercapacitor; the gate of the first MOS tube is connected to the constant current control module, and the source of the first MOS tube is connected to the first diode connection, the drain of the first MOS tube is connected to the positive pole of the battery, the negative pole of the battery is connected to the other end of the first diode, and the supercapacitor motor load system is connected.

Further, one end of the first relay is connected to the source of the second MOS tube, the other end is connected to the positive pole of the storage battery, one end of the second relay is connected to the motor load system and the drain of the second MOS tube, and the other end is connected to the positive electrode of the storage battery. One end is connected to a supercapacitor.

Further, a first voltage detection module is connected between one end of the first relay and the storage battery, and a second voltage detection module is connected between the second relay and the supercapacitor.

Further, the controller of the main control module controls the first control relay and the second relay through the feedback voltage signals of the first voltage detection module and the second voltage detection module, the forklift lifting signal, the lowering signal, and the main switch signal. On-off with the second MOS tube of the step-down circuit.

Further, the constant current control module can control the on-off of the first MOS tube when the first relay is off and the second relay is on, so that the battery charges the supercapacitor and controls the charging current.

Further, the third relay is controlled by a controller.

Further, when the controller of the motor load system receives the lifting signal, the third relay is closed, and the double-acting motor-generator is used as a motor to drive the double-acting oil pump-hydraulic motor to rotate forward to realize load lifting; When the down signal is reached, the third relay is closed, and the load drops to drive the double-acting oil pump-hydraulic motor to reverse to become a hydraulic motor, which drives the double-acting motor-generator to reverse to generate electricity.

The present invention has the following advantages due to the adoption of the above technical scheme:

1. The potential energy of the traditional electric forklift load falling back is dissipated and wasted in the form of heat energy, which not only increases the operating load of key parts of the oil circuit, but also greatly increases the heat dissipation demand of the forklift cooling device and reduces the service life of the equipment. This device can recover and utilize most of the potential energy of the load, greatly reduce the heat generated by the load drop, and realize energy regeneration and utilization. It is suitable for most of the medium and high-end forklift products. It has broad market prospects and remarkable energy-saving benefits.

2. By detecting the voltage signal of dual energy sources and receiving the lifting and lowering signals, the on-off of the relay is controlled, so as to complete the energy source management when the forklift is working. The operation method is simple, the control program is simple, and no excessive hardware equipment is required. The circuit design technology is mature, so the circuit has strong operability, is easy to manufacture as an integrated module, has a small volume and space, and is easy to place on a forklift; and the control program has low requirements on the response speed of the hardware, overload voltage, and current, and the circuit cost is low. Has good economic value.

3. The battery-supercapacitor energy storage solution is adopted. The supercapacitor is used as the first storage device for recovering potential energy. When the battery is fully charged, the battery is used as the second energy storage device for recovering potential energy. Supercapacitors have high power density and are suitable for high-current discharge, and batteries have high energy density and are suitable for long-term discharge. Therefore, comprehensively matching the energy output of the supercapacitor and the battery can maximize the energy utilization rate and improve the working efficiency of the forklift. In addition, the supercapacitor is used as the energy source when the forklift is lifted and accelerated, which avoids the instantaneous high current output of the battery and prolongs the service life of the battery.

Description of drawings

Fig. 1 is the overall circuit block diagram of the present invention;

Fig. 2 is a schematic diagram of the motor load system of the present invention.

Marks in the figure: battery 1, first voltage detection module 2, constant current control module 3, first relay 4, first MOS tube 5, first diode 6, inductor 7, second diode 8, second MOS tube 9, second voltage detection module 10, supercapacitor 11, second relay 12, motor load system 13, controller 14, double-acting motor-generator B1, double-acting oil pump-hydraulic motor B2, oil cylinder B3, third Relay B4.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

As shown in FIG. 1 , a potential energy regeneration device for an electric forklift includes a motor load system 13 , a step-down conversion circuit, a main control module, a constant current control module 3 and a power supply module. The constant current control module 3 is electrically connected to the power module, and the motor load system 13, step-down conversion circuit, and power module are electrically connected to and controlled by the main control module.

The motor load system 13 includes a double-acting motor-generator B1, a double-acting oil pump-hydraulic motor B2, an oil cylinder B3, a third relay B4 and auxiliary equipment. As shown in Figure 2, the double-acting motor-generator B1 is connected to the double-acting oil pump-hydraulic motor B2 and the third relay B4, and the double-acting oil pump-hydraulic motor B2 is connected to the oil cylinder B3 and auxiliary equipment.

The step-down conversion circuit includes an inductor 7, a second diode 8 and a second MOS transistor 9, the drain of the second MOS transistor 9 is connected to the motor load system 13, and the source of the second MOS transistor 9 is connected to the The inductor 7 is connected to the second diode 8, and the gate of the second MOS transistor 9 is connected to the main control module. The third relay B4 is controlled by the main control module, that is, the controller 14 of the main control module. The controller 14 receives the master switch signal, the lifting signal, and the lowering signal. Then, when the controller 14 of the motor load system 13 receives the lifting signal, the third relay B4 is closed, and the double-acting motor-generator B1 is used as a motor to drive the double-acting oil pump-hydraulic motor B2 to rotate forward to realize load lifting; When the controller 14 receives the down signal, the third relay B4 is closed, and the load drop drives the double-acting oil pump-hydraulic motor B2 to reverse to become a hydraulic motor, and drives the double-acting motor-generator B1 to reversely generate power. The third relay B4 is controlled by the controller 14, and is turned on when the lifting/lowering signal is received, and is turned off when the standby signal is received.

The main control module includes a controller 14, a first relay 4, a second relay 12, a first voltage detection module 2, a second voltage detection module 10; the first relay 4, the second relay 12, the first voltage detection The module 2 and the second voltage detection module 10 are electrically connected to and controlled by the controller 14; the controller 14 receives the main switch signal, the lifting signal, and the lowering signal. One end of the first relay 4 is connected to the source of the second MOS tube 9, the other end is connected to the positive pole of the storage battery 1, and one end of the second relay 12 is connected to the motor load system 13 and the drain of the second MOS tube 9 connected, and the other end is connected with supercapacitor 11. A first voltage detection module 2 is connected between one end of the first relay 4 and the battery 1 , and a second voltage detection module 10 is connected between the second relay 12 and the supercapacitor 11 .

The controller 14 of the main control module controls the first control relay and the second relay through the feedback voltage signal of the first voltage detection module 2 and the second voltage detection module 10 and the forklift lifting signal, lowering signal and master switch signal. 12 and the second MOS transistor 9 of the step-down circuit.

The power module includes a storage battery 1, a first diode 6, a first MOS transistor 5, and a supercapacitor 11; the gate of the first MOS transistor 5 is connected to the constant current control module 3, and the source of the first MOS transistor 5 pole is connected with the first diode 6, the drain of the first MOS tube 5 is connected with the positive pole of the battery 1, the negative pole of the battery 1 is connected with the other end of the first diode 6, and the supercapacitor 11 is connected with the motor load system 13. The constant current control module 3, when the first relay 4 is off and the second relay 12 is on, can control the on-off of the first MOS transistor 5, enable the battery 1 to charge the supercapacitor 11, and control the charging current.

To sum up, specifically when the controller 14 receives a lifting signal, that is, a lifting start or acceleration signal, according to the voltage signal fed back by the first voltage detection module 2 and the second voltage detection module 10, and when the supercapacitor 11 When the voltage at both ends is not less than 24V, the controller 14 sends a signal to control the first relay 4 to be disconnected and the second relay 12 to be turned on, so that the supercapacitor 11 is in a power supply state, and supplies power until the voltage of the supercapacitor 11 is lower than 20V . If the voltage across the supercapacitor 11 is less than 24V, the battery 1 will still provide power.

When the controller 14 does not receive a lifting signal or a lowering signal, the lifting system of the forklift is in a standby state, and the controller 14 controls both the first relay 4 and the second relay 12 to be turned off.

When the controller 14 received the drop signal, according to the voltage signal fed back by the first voltage detection module 2 and the second voltage detection module 10, and when the voltage across the supercapacitor 11 was not greater than 28V, the controller 14 sent a signal to control The first relay 4 is turned off, and the second relay 12 is turned on, so that the motor load system 13 charges the supercapacitor 11 . If the voltage across the supercapacitor 11 is greater than 28V, the controller 14 controls the first relay 4 to be disconnected and the second relay 12 to be disconnected, and outputs a PWM signal to the second MOS transistor 9, that is, outputs a pulse width modulation for The on-off control of the second MOS transistor 9 of the semiconductor device enables the motor load system 13 to charge the storage battery 1 . And according to the feedback signal of the first voltage detection module 2, the duty cycle of the PWM signal is adjusted, so that the charging voltage is stabilized at 28.5V, and constant voltage charging is realized.

When it is detected that the voltage of the supercapacitor 11 is greater than 28V under the falling signal for 5 consecutive times, when the lifting system of the forklift is in the standby state, the controller 14 controls the first relay 4 to be disconnected, the second relay 12 to be turned on, and output The PWM signal is sent to the second MOS tube 9, and the battery 1 is charged by the supercapacitor 11, and the duty ratio of the PWM signal is adjusted according to the feedback signal of the first voltage detection module 2, so as to realize constant voltage charging until the voltage of the supercapacitor 11 is no longer Greater than 24V or receive lift signal or drop signal.

When it is detected that the voltage of the supercapacitor 11 is lower than 24V when the lifting signal is started or accelerated for five consecutive times, when the lifting system of the forklift is in a standby state, the controller 14 controls the first relay 4 to be disconnected and the second relay 4 to be disconnected. The relay 12 is turned on, and the battery 1 charges the supercapacitor 1111 with a constant current of 5A through the constant current charging module.

The constant current control module 3, when the first relay 4 and the second relay 12 are both closed, judges the charging current by judging the voltage drop of the internal sampling resistor, thereby controlling the on-off of the first MOS tube 5, and completing the storage of the battery. 1. Charge the supercapacitor 11, and control the charging current at about 5A.

The above is only a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present invention, some improvements and modifications can also be made, and these improvements and modifications should also be considered Within the protection scope of the present invention.

Claims (7)

1. A kind of 1. electri forklift potential energy regenerating unit, it is characterised in that including motor load system, Buck conversion circuit, Main control module, constant-current control module and power module；The constant-current control module and power module are electrically connected, the motor Load system, Buck conversion circuit, power module and main control module are electrically connected, and are controlled by it；

   The motor load system includes double acting motor generator, double acting oil pump-hydraulic motor, oil cylinder, the 3rd relay Device and auxiliary device, the double acting motor generator are connected with double acting oil pump-hydraulic motor, the 3rd relay, double cropping It is connected with oil pump-hydraulic motor with oil cylinder, auxiliary device；

   The Buck conversion circuit includes inductance, the second diode and the second metal-oxide-semiconductor, drain electrode and the electricity of second metal-oxide-semiconductor Machine load system connects, and the source electrode of the second metal-oxide-semiconductor is connected with inductance, the second diode, grid and the master control molding of the second metal-oxide-semiconductor Block connects；

   The main control module includes controller, the first relay, the second relay, first voltage detection module, second voltage Detection module；First relay, the second relay, first voltage detection module, second voltage detection module and controller It is electrically connected, and is controlled by it；The controller receives master switch signal, lifting signal, dropping signal；

   The power module includes storage battery, the first diode, the first metal-oxide-semiconductor, super capacitor；The grid of first metal-oxide-semiconductor It is connected with constant-current control module, the source electrode of the first metal-oxide-semiconductor is connected with the first diode, the drain electrode of the first metal-oxide-semiconductor and storage battery Cathode connects, and the anode of storage battery is connected with the other end of the first diode, the connection of super capacitor motor load system.
2. A kind of 2. electri forklift potential energy regenerating unit according to claim 1, it is characterised in that first relay One end be connected with the source electrode of the second metal-oxide-semiconductor, the connection of the cathode of the other end and storage battery, one end and the electricity of second relay The drain electrode connection of machine load system, the second metal-oxide-semiconductor, the other end are connected with super capacitor.
3. A kind of 3. electri forklift potential energy regenerating unit according to claim 2, it is characterised in that first relay One end and storage battery between connect first voltage detection module, between second relay and super capacitor connect second electricity Press detection module.
4. A kind of 4. electri forklift potential energy regenerating unit according to claim 1, it is characterised in that the main control module Controller by first voltage detection module, the feedback voltage signal of second voltage detection module and forklift lifting signal, under Signal, master switch signal drop, to control the break-make of the second metal-oxide-semiconductor of the first control relay, the second relay and reduction voltage circuit.
5. A kind of 5. electri forklift potential energy regenerating unit according to claim 1, it is characterised in that the current constant control mould Block, when the first relay disconnects, the second relay closes, can control the break-make of the first metal-oxide-semiconductor, and cause storage battery to super The charging of capacitance, and control charging current.
6. A kind of 6. electri forklift potential energy regenerating unit according to claim 1, it is characterised in that the 3rd relay It is controlled by the controller.
7. A kind of 7. electri forklift potential energy regenerating unit according to claim 6, it is characterised in that the motor load system For system when controller receives lifting signal, the 3rd relay closure, double acting motor generator drives double cropping as motor Rotated forward with oil pump-hydraulic motor, realize load lifting；When controller receives dropping signal, the 3rd relay closure, under load Drop drives double acting oil pump-hydraulic motor reversion to become hydraulic motor, drives the reversion power generation of double acting motor generator.