A control circuit for driving an oil pump of a forklift

Abstract

The utility model relates to electric fork truck system technical field, concretely provides a fork truck lifting oil pump drive control circuit, and the control circuit includes MCU, pump oil voltage control unit, unloading voltage control unit, first control voltage and second control voltage, the pump oil voltage control unit includes MOS pipe V1, triode Q6, triode Q4, triode Q5, and unloading voltage control unit includes MOS pipe V4, triode Q25, triode Q20, triode Q24, the pump oil and unloading control unit independent design in the scheme, respectively correspond to the lifting action, improve control accuracy and system responsiveness, the utility model discloses a double voltage time -sharing control strategy, effectively solved the contradiction problem of the attraction deficiency and coil heating in electric fork truck oil pump drive, improved system reliability, efficiency and life, has higher industrial application value.

Description

Technical Field

[0001] This utility model relates to the technical field of electric forklift systems, specifically to a hydraulic pump drive control circuit for forklift lifting. Background Technology

[0002] Electric forklifts are common industrial handling vehicles. Their core function is to lift and lower goods by using a hydraulic system to drive the forks. A Chinese patent application (application number 202511561043.1) proposes an integrated forklift drive assembly, including, from left to right, an oil pump drive assembly, a motor drive assembly, and a gear drive assembly. The oil pump drive assembly includes an oil pump drive spindle; the motor drive assembly includes a stator and rotor for drive engagement; and the gear drive assembly includes a gear transmission shaft. It also includes a coil, a brake sleeve, a splined shaft, a magnetic sleeve for the transmission shaft, and a return spring. One end of the splined shaft is detachably splined with the oil pump drive spindle, and the other end is detachably splined with the gear transmission shaft. This design discloses a method of controlling the detachable transmission connection between the drive motor and the gear drive assembly by energizing the coil.

[0003] In practical applications, based on the working principle of the above solution, operators will configure the forklift oil pump drive control method to control the drive motor and oil pump drive assembly through a separable transmission connection by energizing the coil. Specifically, energizing the coil causes the drive motor shaft to engage with the oil pump drive assembly's main shaft for pumping and unloading oil, thus enabling higher-frequency lifting drive control for electric forklifts. However, in practical applications, there are challenges regarding how to apply voltage to the coil. Specifically: if a low voltage is used to drive the coil, the initial voltage is too low, resulting in insufficient engagement capacity and potentially unsuccessful engagement, affecting oil pump start-up efficiency. Conversely, if a high voltage is used, continuous application of high voltage to the coil can cause severe overheating, affecting system stability and lifespan. Utility Model Content

[0004] In view of the shortcomings of the prior art described above, the purpose of this utility model is to provide a hydraulic pump drive control circuit for forklift lifting, which solves the problem in the prior art of how to ensure that the coil has sufficient initial attraction force to reliably drive the hydraulic pump while avoiding overheating of the coil due to continuous application of high voltage.

[0005] To achieve the above and other related objectives, this utility model provides a hydraulic pump drive control circuit for forklift lifting, the control circuit including an MCU, a pump voltage control unit, an unloading voltage control unit, a first control voltage, and a second control voltage; The pump oil voltage control unit includes a MOSFET V1, a transistor Q6, a transistor Q4, and a transistor Q5. The drain of the MOSFET V1 is used to receive the coil pull-in signal. The source of the MOSFET V1 is grounded, and the gate is connected to the emitter of the transistor Q6. The base of the transistor Q6 is connected to the collector of the transistor Q4, and the collector of the transistor Q6 is grounded. The base of the transistor Q4 is connected to the collector of the transistor Q5, and the emitter of the transistor Q5 is connected to the MCU. The unloading voltage control unit includes a MOSFET V4, a transistor Q25, a transistor Q20, and a transistor Q24. The drain of the MOSFET V4 is used to receive the magnetic braking signal. The source of the MOSFET V1 is grounded, and its gate is connected to the emitter of the transistor Q25. The base of the transistor Q25 is connected to the collector of the transistor Q20, and the collector of the transistor Q25 is grounded. The base of the transistor Q20 is connected to the collector of the transistor Q24, and the emitter of the transistor Q24 is connected to the MCU.

[0006] In one embodiment of this utility model, the first control voltage is connected to the emitter of the PNP transistor Q4, and the second control voltage is connected to the base of the transistor Q5; the first control voltage is output to the pull-in coil through the transistor Q4 to pull out the motor shaft driving the oil pump, and the second control voltage of 5V is output to the pull-in coil through the transistor Q5 to maintain the pull-in state between the pull-in coil and the motor shaft of the oil pump.

[0007] In one embodiment of the present invention, the first control voltage is connected to the emitter of transistor Q20, and the second control voltage is connected to the base of transistor Q24; the first control voltage is output to the pull-in coil through transistor Q20 to pull out the motor shaft driving the oil pump, and the second control voltage is output to the pull-in coil through transistor Q24 to maintain the pull-in state between the pull-in coil and the motor shaft of the oil pump.

[0008] In one embodiment of this utility model, the first control voltage is 15V and the second control voltage is 5V.

[0009] In one embodiment of this utility model, the MCU is connected to the drain of the MOS transistor V4 via the SDA interface for detecting magnetic braking signals.

[0010] In one embodiment of this utility model, transistors Q6, Q4, Q20, and Q25 are PNP transistors, while transistors Q5 and Q24 are NPN transistors.

[0011] As described above, the oil pump drive control circuit for forklift lifting of this utility model has the following beneficial effects: This invention employs a dual-voltage control strategy by setting up an oil pump voltage control unit and an oil unloading voltage control unit. In the initial stage, a first control voltage (high voltage) is applied to the pull-in coil to achieve rapid pull-in of the motor shaft and oil pump shaft, providing sufficient pull-in force to ensure rapid and reliable pull-in between the motor shaft and oil pump shaft. This avoids insufficient pull-in capacity due to low initial voltage, improving the pull-in efficiency and effect between the motor shaft and oil pump shaft. After the motor shaft and oil pump shaft are pulled in, a second control voltage (low voltage) is applied to the pull-in coil to maintain the pull-in state, ensuring the pumping and unloading of oil by the oil pump drive assembly. This avoids continuous high-voltage operation of the coil, reducing heat generation and extending system lifespan. In this design, the oil pump and oil unloading control units are independently designed, each corresponding to the lifting action, improving control accuracy and system responsiveness. Attached Figure Description

[0012] Figure 1 The diagram shown is a schematic diagram of the oil pump drive control circuit for forklift lifting disclosed in this utility model.

[0013] Figure 2 The image shown is an enlarged view of the oil pump voltage control unit in the oil pump drive control circuit for forklift lifting disclosed in this utility model.

[0014] Figure 3 The image shown is an enlarged view of the oil unloading voltage control unit in the oil pump drive control circuit for forklift lifting disclosed in this utility model. Detailed Implementation

[0015] The following specific embodiments illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification.

[0016] Please see Figures 1 to 3 It should be noted that the structures, proportions, sizes, etc., illustrated in the accompanying drawings are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the implementation conditions of this utility model. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportional relationships, or adjustments to the size, without affecting the effects and purposes that this utility model can produce, should fall within the scope of the technical content disclosed in this utility model.

[0017] Please see Figure 1This utility model provides a hydraulic pump drive control circuit for forklift lifting. The control circuit includes an MCU, a pumping voltage control unit 1, an unloading voltage control unit 2, a first control voltage 3, and a second control voltage 4. In this embodiment, the first control voltage 3 is 15V and the second control voltage 4 is 5V. The MCU is used to control the hydraulic pump drive assembly to pump and unload oil according to the coil activation signal and the magnetic braking signal.

[0018] Please see Figure 1 , Figure 2 The pump oil voltage control unit 1 includes a MOSFET V1, a transistor Q6, a transistor Q4, and a transistor Q5. The drain of MOSFET V1 is connected to the upper-level signal circuit to receive the coil pull-in signal. The source of MOSFET V1 is grounded, and its gate is connected to the emitter of transistor Q6. The base of transistor Q6 is connected to the collector of transistor Q4, and the collector of transistor Q6 is grounded. The base of transistor Q4 is connected to the collector of transistor Q5, and the emitter of transistor Q5 is connected to the MCU. The first control voltage 3 is connected to the emitter of PNP transistor Q4. The second control voltage 4 is connected to the base of transistor Q5; transistors Q6 and Q4 are PNP type transistors, and transistor Q5 is an NPN type transistor. The MCU controls the oil pump voltage control unit 1 to output a 15V first control voltage 3 to the pull-in coil through transistor Q4 to pull out the motor shaft driving the oil pump. The MCU controls the oil pump voltage control unit 1 to output a 5V second control voltage 4 to the pull-in coil through transistor Q5 to maintain the pull-in state between the pull-in coil and the motor shaft of the oil pump. The MCU controls the oil pump drive assembly to pump oil according to the coil pull-in signal.

[0019] Please see Figure 1 , Figure 3The unloading voltage control unit 2 includes a MOSFET V4, a transistor Q25, a transistor Q20, and a transistor Q24. The drain of MOSFET V4 is connected to the upper-level signal circuit to receive the magnetic braking signal. The source of MOSFET V4 is grounded, and its gate is connected to the emitter of transistor Q25. The base of transistor Q25 is connected to the collector of transistor Q20, and the collector of transistor Q25 is grounded. The base of transistor Q20 is connected to the collector of transistor Q24, and the emitter of transistor Q24 is connected to the MCU. The first control circuit... Voltage 3 is connected to the emitter of transistor Q20, and the second control voltage 4 is connected to the base of transistor Q24. Transistors Q20 and Q25 are PNP type transistors, while transistor Q24 is an NPN type transistor. The MCU controls the unloading voltage control unit 2 to output the first control voltage 3 to the pull-in coil through transistor Q20 to pull out the motor shaft driving the oil pump. The MCU controls the unloading voltage control unit 2 to output the second control voltage 4 (5V) to the pull-in coil through transistor Q24 to maintain the pull-in state between the pull-in coil and the motor shaft of the oil pump. The MCU is connected to the drain of MOSFET V4 through the SDA interface to detect the magnetic braking signal. The MCU controls the oil pump drive assembly to unload oil based on the magnetic braking signal.

[0020] This invention employs a dual-voltage control strategy by setting up an oil pump voltage control unit 1 and an oil unloading voltage control unit 2. In the initial stage, a first control voltage 3 (high voltage) is applied to the engagement coil to achieve rapid engagement of the motor shaft and oil pump shaft, providing sufficient engagement force to ensure rapid and reliable engagement between the motor shaft and oil pump shaft. This avoids insufficient engagement capacity due to low initial voltage, improving the engagement efficiency and effect between the motor shaft and oil pump shaft. After engagement, a second control voltage 4 (low voltage) is applied to the engagement coil to maintain the engagement state, ensuring the pumping and unloading of oil by the oil pump drive assembly. This avoids continuous high voltage operation of the coil, reducing heat generation and extending system lifespan. In this design, the oil pump and oil unloading control units are independently designed, corresponding to lifting and lowering actions respectively, improving control accuracy and system responsiveness.

[0021] The control flow of this solution is as follows: 1) Lifting action: Press the lift button, the MCU controls the oil pump voltage control unit 1 to output 15V voltage to engage the motor shaft and the oil pump shaft. After engagement, switch to 5V voltage to maintain the engagement state of the motor shaft and the oil pump shaft, drive the motor to rotate forward to drive the oil pump drive component to pump oil until the oil cylinder reaches the top and stops automatically. Then release the button to reset.

[0022] 2) Lowering Action: Press the lowering button. The MCU controls the unloading voltage control unit 2 to output 15V voltage to engage the motor shaft and the oil pump shaft. After engagement, the voltage switches to 5V to maintain the engagement state between the motor shaft and the oil pump shaft. The drive motor reverses to drive the oil pump drive assembly to discharge oil until the oil cylinder reaches the bottom and automatically stops. Then release the button to reset. In summary, this solution features independently designed oil pump and unloading control units, each corresponding to the lifting action, thus improving control accuracy and system responsiveness. Furthermore, this invention effectively resolves the contradiction between insufficient suction force and coil overheating in the electric forklift oil pump drive through a dual-voltage time-sharing control strategy, enhancing system reliability, efficiency, and lifespan, and possessing high industrial application value. Therefore, this invention effectively overcomes the various shortcomings of existing technologies and has significant industrial applicability.

[0023] The above embodiments are merely illustrative of the principles and effects of this utility model and are not intended to limit the scope of this utility model. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this utility model. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this utility model should still be covered by the claims of this utility model.

Claims

1. A hydraulic pump drive control circuit for forklift lifting, characterized in that: The control circuit includes an MCU, a pump oil voltage control unit, an unloading oil voltage control unit, a first control voltage, and a second control voltage; The pump oil voltage control unit includes a MOSFET V1, a transistor Q6, a transistor Q4, and a transistor Q5. The drain of the MOSFET V1 is used to receive the coil pull-in signal. The source of the MOSFET V1 is grounded, and the gate is connected to the emitter of the transistor Q6. The base of the transistor Q6 is connected to the collector of the transistor Q4, and the collector of the transistor Q6 is grounded. The base of the transistor Q4 is connected to the collector of the transistor Q5, and the emitter of the transistor Q5 is connected to the MCU. The unloading voltage control unit includes a MOSFET V4, a transistor Q25, a transistor Q20, and a transistor Q24. The drain of the MOSFET V4 is used to receive the magnetic braking signal. The source of the MOSFET V1 is grounded, and its gate is connected to the emitter of the transistor Q25. The base of the transistor Q25 is connected to the collector of the transistor Q20, and the collector of the transistor Q25 is grounded. The base of the transistor Q20 is connected to the collector of the transistor Q24, and the emitter of the transistor Q24 is connected to the MCU.

2. The oil pump drive control circuit for forklift lifting according to claim 1, characterized in that: The first control voltage is connected to the emitter of PNP transistor Q4, and the second control voltage is connected to the base of transistor Q5. The first control voltage is output to the pull-in coil through transistor Q4 to pull out the motor shaft driving the oil pump, and the second control voltage of 5V is output to the pull-in coil through transistor Q5 to maintain the pull-in state between the pull-in coil and the motor shaft of the oil pump.

3. The forklift lifting oil pump drive control circuit according to claim 1, characterized in that: The first control voltage is connected to the emitter of transistor Q20, and the second control voltage is connected to the base of transistor Q24. The first control voltage is output to the pull-in coil through transistor Q20 to pull out the motor shaft driving the oil pump, and the second control voltage is output to the pull-in coil through transistor Q24 to maintain the pull-in state between the pull-in coil and the motor shaft of the oil pump.

4. The oil pump drive control circuit for forklift lifting according to claim 1, characterized in that: The first control voltage is 15V, and the second control voltage is 5V.

5. The oil pump drive control circuit for forklift lifting according to claim 1, characterized in that: The MCU is connected to the drain of MOS transistor V4 via the SDA interface for detecting magnetic braking signals.

6. The oil pump drive control circuit for forklift lifting according to claim 1, characterized in that: Transistors Q6, Q4, Q20, and Q25 are PNP type transistors, while transistors Q5 and Q24 are NPN type transistors.

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