Hydraulic solenoid valve coil driving circuit

Abstract

The utility model relates to a hydraulic electromagnetic valve coil driving circuit which comprises a PWM control signal input end, a sampling resistor R7, a first voltage comparator U1, a second voltage comparator U2, an MOSFET G1, an electromagnetic valve coil K1 and a pull-up resistor R3. An MOSFET is adopted as a switching element, driving is efficient, no mechanical contact exists, U1 receives a PWM signal to control on-off of the MOSFET, U2 detects current abnormity and then feeds back the current abnormity to U1, closed-loop control is formed, and short-circuit protection can be achieved.

Description

Technical Field

[0001] This utility model relates to the field of electric forklift technology, and in particular to a hydraulic solenoid valve coil drive circuit. Background Technology

[0002] Generally, the solenoid valve coil of an electric forklift is driven by a transistor or a relay. Transistors have a relatively large driving current, while relays have a short contact life and cannot provide overcurrent and short circuit protection. Summary of the Invention

[0003] To address the aforementioned problems, the purpose of this utility model is to provide a hydraulic solenoid valve coil drive circuit that does not require a relay and can achieve multiple short-circuit protection.

[0004] A hydraulic solenoid valve coil drive circuit includes:

[0005] The components include the PWM control signal input terminal, sampling resistor R7, first voltage comparator U1, second voltage comparator U2, MOSFET G1, solenoid valve coil K1, and pull-up resistor R3.

[0006] The PWM control signal input terminal is connected to one input terminal of the first voltage comparator U1;

[0007] The output of the first voltage comparator U1 is connected to the +VCC power supply through a pull-up resistor R3 and directly connected to the gate of MOSFET G1.

[0008] The drain of the MOSFET G1 is connected to the power supply B+ through the solenoid valve coil K1, and the source is grounded through the sampling resistor R7.

[0009] The voltage signal of the sampling resistor R7 is input to one input terminal of the second voltage comparator U2, the other input terminal of the second voltage comparator U2 is connected to the reference voltage Vref1, and the output terminal of the second voltage comparator U2 is connected to the other input terminal of the first voltage comparator U1.

[0010] When the output of the first voltage comparator U1 is driven by the +VCC power supply through the pull-up resistor R3, the MOSFET G1 is turned on to open the solenoid valve coil K1.

[0011] When the voltage across the sampling resistor R7 exceeds the reference voltage Vref1 of the second voltage comparator U2, the second voltage comparator U2 outputs a low level, forcing the first voltage comparator U1 to output a low level to turn off MOSFET G1, thereby achieving short-circuit protection for the solenoid valve coil K1.

[0012] Preferably, the reference voltage Vref1 of the second voltage comparator U2 is set according to the rated operating current of the solenoid valve coil K1 and is used to determine the short-circuit fault threshold.

[0013] Preferably, resistors R1 and R2 are included. The PWM control signal input terminal is divided by resistors R1 and R2 and sent to one input terminal of the first voltage comparator U1. The other end of resistor R2 is pulled up and connected to the power supply +VDD.

[0014] Preferably, the output of the second voltage comparator U2 is connected to the other input of the first voltage comparator U2 after being divided by resistors R4 and R5. The other end of resistor R4 is connected to the +VCC power supply, and the other end of resistor R5 is grounded.

[0015] Preferably, the sampling resistor R7 is connected to one input terminal of the second voltage comparator U2 via an RC filter circuit consisting of resistor R6 and capacitor C1.

[0016] In the above technical solution, MOSFETs are used as switching elements, which are highly efficient and have no mechanical contacts, thus improving service life. A sampling resistor R7 is set to monitor the current in real time. U1 receives PWM signals to control the switching on and off of the MOSFET. U2 detects abnormal current and feeds back to U1, forming a closed-loop control. When the current exceeds the limit (R7 voltage > Vref1), U2 outputs a low level to force the MOSFET to turn off, thereby achieving short-circuit protection and improving circuit reliability. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of this application. Detailed Implementation

[0018] The embodiments of this utility model are described in detail below.

[0019] like Figure 1 As shown, this embodiment provides a hydraulic solenoid valve coil drive circuit, including: a PWM control signal input terminal, a sampling resistor R7, a first voltage comparator U1, a second voltage comparator U2, a MOSFET G1, a solenoid valve coil K1, and a pull-up resistor R3.

[0020] The PWM control signal input terminal receives an external PWM signal to control the switching of the solenoid valve coil. This input terminal is connected to one input of the first voltage comparator U1. The PWM control signal input terminal is divided by resistors R1 and R2 and connected to one input of the first voltage comparator U1. The other end of resistor R2 is pulled up and connected to the +VDD power supply. Resistors R1 and R2 are used to divide the PWM signal and adapt it to the input range of the voltage comparator U1. The output of the first voltage comparator U1 is connected to the +VCC power supply via a pull-up resistor R3 and directly connected to the gate of MOSFET G1. The high and low levels of the first voltage comparator U1 output control the on / off state of the MOSFET. The pull-up resistor R3 ensures that MOSFET G1 is fully turned on when the comparator U1 outputs a high level. The drain of MOSFET G1 is connected to the B+ power supply via the solenoid valve coil K1, and the on / off state of the MOSFET controls the on / off state of the solenoid valve coil K1.

[0021] The source of MOSFET G1 is grounded through sampling resistor R7. The voltage signal from sampling resistor R7 is input to one input of the second voltage comparator U2, the other input of which is connected to the reference voltage Vref1. The output of the second voltage comparator U2 is connected to the other input of the first voltage comparator U1. The current flowing through the solenoid coil K1 generates a voltage across sampling resistor R7. This voltage is filtered by an RC filter circuit composed of resistor R1 and capacitor C1 to remove noise before being input to the voltage comparator U2. The second voltage comparator U2 compares the voltage across sampling resistor R7 with the reference voltage Vref1 to determine if a short circuit has occurred, and feeds this feedback to the first voltage comparator U1 to make its output low. Figure 1 As shown, the output of the second voltage comparator U2 is connected to the other input of the first voltage comparator U2 after being divided by resistors R4 and R5. The other end of resistor R4 is connected to the +VCC power supply, and the other end of resistor R5 is grounded.

[0022] The working principle of the above circuit is as follows:

[0023] An external PWM control signal is transmitted to one end of the first voltage comparator U1 via a voltage divider connected to resistors R1 and R2. When this signal is greater than the output signal from the connection between resistors R4 and R5 and the second voltage comparator U2, the output of the first voltage comparator U1 outputs a +VCC voltage (high-level signal) through a pull-up resistor R3 connected to the +VCC power supply. This +VCC voltage drives MOSFET G1 to open the solenoid valve coil K1. When MOSFET G1 is in the on state, a short circuit occurs in the solenoid valve coil K1, increasing the voltage across the sampling resistor R7. This voltage is filtered by resistor R6 and capacitor C1 and then input to the second comparator U2. If this voltage is greater than the reference voltage Vref1 of the second voltage comparator U2, the output of the second voltage comparator U2 outputs a low-level signal. If this low-level signal is less than the PWM input signal of the first voltage comparator U1, the first voltage comparator U1 outputs a low-level signal to turn off MOSFET G1, causing the solenoid valve coil K1 to close, thus achieving short-circuit protection.

[0024] Although embodiments of the present invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A hydraulic solenoid valve coil drive circuit characterized by comprising: Comprise: PWM control signal input end, sampling resistance R7, first voltage comparator U1, second voltage comparator U2, MOSFET G1, solenoid coil K1 and pull-up resistor R3; The PWM control signal input end is connected to one input end of the first voltage comparator U1; The output end of the first voltage comparator U1 is connected to the +VCC power supply through the pull-up resistor R3, and is directly connected to the gate of the MOSFET G1; The drain of the MOSFET G1 is connected to the power supply B+ through the solenoid coil K1, and the source is grounded through the sampling resistance R7; The voltage signal of the sampling resistance R7 is input to one input end of the second voltage comparator U2, and the other input end of the second voltage comparator U2 is connected to the reference voltage Vref1, and the output end of the second voltage comparator U2 is connected to the other input end of the first voltage comparator U1; When the output end of the first voltage comparator U1 is driven by the +VCC power supply through the pull-up resistor R3, the MOSFET G1 is turned on to open the solenoid coil K1; When the voltage of the sampling resistance R7 exceeds the reference voltage Vref1 of the second voltage comparator U2, the second voltage comparator U2 outputs low level, forcing the first voltage comparator U1 to output low level to turn off the MOSFET G1, realizing the short circuit protection of the solenoid coil K1.

2. The hydraulic solenoid valve coil drive circuit according to claim 1, wherein The reference voltage Vref1 of the second voltage comparator U2 is set according to the rated working current of the solenoid coil K1, which is used to determine the short circuit fault threshold.

3. The hydraulic solenoid valve coil drive circuit according to claim 1, wherein Comprise resistance R1 and resistance R2, the PWM control signal input end is divided to one input end of the first voltage comparator U1 through resistance R1 and resistance R2, and the other end of resistance R2 is pulled up to connect the power supply +VDD.

4. The hydraulic solenoid valve coil drive circuit according to claim 1, wherein The output end of the second voltage comparator U2 is connected to the other input end of the first voltage comparator U2 after being divided by resistance R4 and resistance R5, the other end of the resistance R4 is connected to the +VCC power supply, and the other end of the resistance R5 is grounded.

5. The hydraulic solenoid valve coil drive circuit according to claim 1, wherein The sampling resistance R7 is connected to one input end of the second voltage comparator U2 through the RC filter circuit composed of resistance R6 and capacitor C1.

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