Forklift electrical switch control circuit integrating delay start and emergency stop functions

Abstract

The utility model relates to the field of forklift electrical control technology, concretely relates to a forklift electrical switch control circuit integrated with delay opening and emergency stop function, including the switch control circuit connected between the battery group and forklift load, and the switch control circuit includes emergency stop circuit, key switch and delay circuit, and the emergency stop circuit includes emergency stop switch S1, detection switch S2, a plurality of detection branch and a control branch, and the emergency stop switch S1, detection switch S2 and key switch are all connected in series in the power supply circuit of battery group, and a plurality of detection branch detects forklift load working condition based on sampling circuit and window comparator, and the control branch is used to or operation of a plurality of detection branch output result and controls the state of detection switch S2, and the delay circuit prolongs the power-on time based on RC circuit. The utility model can avoid forklift load component and device damaged by current impact, and also can cut off the power supply loop manually through emergency stop switch, satisfies the quick power-off demand under the emergency working condition.

Description

Technical Field

[0001] This utility model relates to the field of forklift electrical control technology, specifically to a forklift electrical switch control circuit that integrates delayed start and emergency stop functions. Background Technology

[0002] Forklifts are common industrial handling vehicles. Their electrical switch control circuits are responsible for controlling the connection and disconnection between the battery pack and the vehicle load, which directly determines the safety and reliability of the forklift's operation. To avoid damage to the vehicle's components from the inrush current when the key switch is turned on, and to ensure that the power supply can be quickly cut off in emergency situations, the forklift's switch control circuits usually need to have both delayed start and emergency stop protection functions. The integration and response speed of the related circuits directly affect the overall performance of the forklift.

[0003] Utility model patent CN224571229U discloses a delay circuit and electrical switching device, including a control circuit, an RC delay circuit, and an output circuit. The control circuit generates a control signal and transmits it to the RC delay circuit, enabling the RC delay circuit to acquire the control signal. When a second trigger signal indicates that the delay circuit is operating, the output circuit controls the third transistor in the output circuit to turn off. Thus, the RC delay circuit charges the capacitor in the RC delay circuit using the input voltage according to the control signal until the voltage on the capacitor exceeds a preset voltage, and then transmits a delay signal to the output circuit. The output circuit then controls the turned-off third transistor to turn on according to the delay signal, completing the delay control.

[0004] In this utility model, the delay circuit does not require additional components, simplifying the circuit and reducing the PCB layout area. However, this solution is only optimized for general delay circuits and does not integrate emergency stop control functions to meet the actual usage needs of forklifts. It cannot quickly cut off the power supply circuit of the forklift in emergency scenarios such as abnormal operation by personnel or equipment failure. At the same time, it does not set up an automatic cut-off mechanism linked to the working status of the forklift load. It can only achieve simple delay on / off control and cannot automatically cut off the power supply when the load has abnormal working states such as overcurrent or undercurrent, resulting in insufficient safety protection capabilities. Utility Model Content

[0005] The purpose of this invention is to provide a forklift electrical switch control circuit that integrates delayed start and emergency stop functions to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, this utility model provides the following technical solution: An integrated forklift electrical switch control circuit with delayed start and emergency stop functions includes a switch control circuit connected between a battery pack and the forklift load. The switch control circuit includes an emergency stop circuit, a key switch, and a delay circuit. The emergency stop circuit includes an emergency stop switch S1, a detection switch S2, several detection branches, and a control branch. The emergency stop switch S1, the detection switch S2, and the key switch are all connected in series in the power supply circuit of the battery pack. The several detection branches detect the working state of the forklift load based on a sampling circuit and a window comparator. The control branch is used to perform an OR operation on the output results of the several detection branches and control the state of the detection switch S2. The delay circuit extends the power-on time based on an RC circuit.

[0007] Preferably, the detection branch includes sampling resistor R1, resistor R2, resistor R3, resistor R4, resistor R5, operational amplifier U1, power supply VCC, resistor R6, resistor R7, operational amplifier U2, diode D1, resistor R8, resistor R9, operational amplifier U3, diode D2, inverter U4 and pull-down resistor R15. The sampling resistor R1 is connected in series in the load branch of the forklift load. The first end of the resistor R2 is connected to the first end of the sampling resistor R1, and the second end of the resistor R2 is connected to the inverting input of the operational amplifier U1. The first end of the resistor R3 is connected to the second end of the sampling resistor R1, and the second end of the resistor R3 is connected to the non-inverting input of the operational amplifier U1. The first end of the resistor R4 is connected to the inverting input of the operational amplifier U1, and the second end of the resistor R4 is connected to the output of the operational amplifier U1. The first end of the resistor R5 is connected to the non-inverting input of the operational amplifier U1, and the second end of the resistor R5 is grounded. The first terminal of resistor R6 is connected to the power supply VCC, the second terminal of resistor R6 is connected to the first terminal of resistor R7, the second terminal of resistor R7 is grounded, the inverting input terminal of operational amplifier U2 is connected to the second terminal of resistor R6, the non-inverting input terminal of operational amplifier U2 is connected to the output terminal of operational amplifier U1, and the output terminal of operational amplifier U2 is connected to the positive terminal of diode D1. The first terminal of resistor R8 is connected to the power supply VCC, the second terminal of resistor R8 is connected to the first terminal of resistor R9, the second terminal of resistor R9 is grounded, the non-inverting input terminal of operational amplifier U3 is connected to the second terminal of resistor R8, the inverting input terminal of operational amplifier U3 is connected to the output terminal of operational amplifier U1, and the output terminal of operational amplifier U3 is connected to the positive terminal of diode D2. The voltage at the inverting input of operational amplifier U2 is less than the voltage at the non-inverting input of operational amplifier U3; The negative terminals of diodes D1 and D2 are both connected to the input terminal of inverter U4. The first terminal of pull-down resistor R15 is connected to the input terminal of inverter U4, and the second terminal of pull-down resistor R15 is grounded.

[0008] Preferably, the control branch includes an OR gate U5, a resistor R10, a resistor R11, a transistor Q1, a resistor R12, an indicator light L1, a diode D3, and a relay KA, wherein the transistor Q1 is an NPN transistor. The output terminals of inverters U4 in different detection branches are respectively connected to different input terminals of OR gate U5. The output terminal of OR gate U5 is connected to the first terminal of resistor R10. The second terminal of resistor R10 is connected to the base of transistor Q1. The first terminal of resistor R11 is connected to the base of transistor Q1. The second terminal of resistor R11 is grounded. The first terminal of resistor R12 is connected to power supply VCC. The second terminal of resistor R12 is connected to the first terminal of indicator light L1. The second terminal of indicator light L1 is connected to the collector of transistor Q1. The emitter of transistor Q1 is grounded. The anode of diode D3 is connected to the second terminal of indicator light L1. The cathode of diode D3 is connected to power supply VCC. The first terminal of relay KA is connected to power supply VCC. The second terminal of relay KA is connected to the second terminal of indicator light L1. Relay KA is used to control the detection switch S2 to open.

[0009] These two settings, through the use of a window comparison architecture in the detection branch design, enable both overcurrent and undercurrent abnormal conditions to be accurately captured, resulting in a wider fault identification coverage; through the control branch design with OR operation logic, any abnormal load can quickly trigger the main circuit to cut off power, resulting in a faster automatic protection response speed.

[0010] Preferably, the key switch includes switch S3, the delay circuit includes resistor R14 and capacitor C1, emergency stop switch S1 and detection switch S2 are both normally closed switches, switch S3 is a normally open switch, the first terminal of emergency stop switch S1 is connected to the positive terminal of the battery pack, the second terminal of emergency stop switch S1 is connected to the first terminal of detection switch S2, the second terminal of detection switch S2 is connected to the first terminal of switch S3, the second terminal of switch S3 is connected to the first terminal of resistor R14, the second terminal of resistor R14 is connected to the first terminal of the forklift load, the first terminal of capacitor C1 is connected to the second terminal of resistor R14, the second terminal of capacitor C1 is connected to the negative terminal of the battery pack, and the second terminal of the forklift load is connected to the negative terminal of the battery pack.

[0011] This design features a three-stage series main circuit architecture consisting of an emergency stop switch, a detection switch, and a key switch, providing multiple safety redundancies in the power supply path. The delay circuit design using an RC charging and discharging structure effectively mitigates the inrush current at the moment of power-on, resulting in a simple circuit structure and stronger anti-interference capabilities.

[0012] Preferably, the switch control circuit further includes several indicator branches, each of which corresponds one-to-one with the detection branch; The indicator branch includes a resistor R13 and an indicator light L2. The first end of the indicator light L2 is grounded, the second end of the indicator light L2 is connected to the first end of the resistor R13, and the second end of the resistor R13 is connected to the output terminal of the inverter U4 in the corresponding detection branch.

[0013] This feature, through the design of indicator branches that correspond one-to-one with the detection branches, allows for direct location of the specific abnormal load branch when a fault occurs.

[0014] Compared with the prior art, the beneficial effects of this utility model are: 1. This utility model integrates the delayed power-on function and the emergency stop protection function into the same power supply circuit by setting up a switch control circuit that integrates an emergency stop circuit, a key switch, and a delay circuit. On the one hand, the RC delay circuit extends the power-on time, suppressing the inrush current at the moment the key switch is turned on, and preventing damage to the forklift load components from current surges. On the other hand, the power supply circuit can be manually cut off by the emergency stop switch to meet the need for rapid power-off in emergency situations. Compared with the existing solution, it does not require additional independent functional circuits, has a high degree of integration, simple wiring, and stronger overall reliability.

[0015] 2. This utility model, by setting up a detection branch based on a sampling circuit and a window comparator and a control branch with OR operation logic, can monitor the working status of each forklift load branch in real time. When any load experiences abnormal operation such as overcurrent or undercurrent, the detection switch can be automatically triggered to disconnect the entire power supply circuit, realizing automatic emergency stop protection against load abnormalities. It can quickly cut off the fault power supply without human intervention, further improving the safety protection capability of the forklift electrical system and fully protecting the safety of equipment and operators. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of this utility model; Figure 2 This is one of the schematic diagrams showing the connection between the battery pack, the switch control circuit, and the forklift load in this utility model; Figure 3 This is the second schematic diagram showing the connection between the battery pack, the switch control circuit, and the forklift load in this utility model. Figure 4 This is a circuit diagram of the detection branch in this utility model; Figure 5 This is a circuit diagram of the control branch and the indicator branch in this utility model; In the picture: 100. Battery pack; 200. Switch control circuit; 201. Emergency stop circuit; 2010. Detection branch; 2011. Control branch; 2012. Indicator branch; 202. Key switch; 203. Delay circuit; 300. Forklift load. Detailed Implementation

[0017] The technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0018] Please see Figures 1-5 The present invention provides the following technical solution: An integrated forklift electrical switch control circuit with delayed start and emergency stop functions includes a switch control circuit 200 connected between a battery pack 100 and a forklift load 300. The forklift load 300 includes electrical components such as a travel motor, hydraulic lifting motor, lighting fixtures, and central control instruments distributed throughout various functional parts of the forklift. Heavy loads within the forklift load 300 are preferably controlled using additional time relays and contactors. The battery pack 100 and the switch control circuit 200 are preferably housed in a shielded power supply box. The switch control circuit 200 includes an emergency stop circuit 201, a key switch 202, and a delay circuit 203. The emergency stop circuit 201 includes an emergency stop switch S1, a detection switch S2, several detection branches 2010, and a control branch 2011. The emergency stop switch S1 is preferably configured as a... The forklift is brightly colored, such as red, and has a raised "emergency stop" marking stamped on its surface. It is prominently installed on the edge of the control panel in the cab. The operator can directly cut off the power supply in time via the emergency stop switch S1. The emergency stop switch S1, the detection switch S2, and the key switch 202 are all connected in series in the power supply circuit of the battery pack 100. The key switch 202 is a rotary normally open switch with a mechanical lock core, installed in the standard mounting hole on the right side of the dashboard in the cab. It requires a special key to rotate and switch the on / off state. Several detection branches 2010 detect the working state of the forklift load 300 based on the sampling circuit and the window comparator. The control branch 2011 is used to OR the output results of several detection branches 2010 and control the state of the detection switch S2. The delay circuit 203 extends the power-on time based on the RC circuit.

[0019] In this embodiment, please refer to Figure 3 and Figure 4 The detection branch 2010 includes sampling resistor R1, resistor R2, resistor R3, resistor R4, resistor R5, operational amplifier U1, power supply VCC, resistor R6, resistor R7, operational amplifier U2, diode D1, resistor R8, resistor R9, operational amplifier U3, diode D2, inverter U4 and pull-down resistor R15. The power supply VCC is obtained by stepping down the battery pack 100. The sampling circuit consists of sampling resistor R1, operational amplifier U1, and their peripheral circuits. Sampling resistor R1 is connected in series in the load branch of the forklift load 300, converting the working current of the branch into a voltage difference between the two ends. The first end of resistor R2 is connected to the first end of sampling resistor R1, and the second end of resistor R2 is connected to the inverting input of operational amplifier U1. The first end of resistor R3 is connected to the second end of sampling resistor R1, and the second end of resistor R3 is connected to the non-inverting input of operational amplifier U1. The first end of resistor R4 is connected to the inverting input of operational amplifier U1, and the second end of resistor R4 is connected to the output of operational amplifier U1. The first end of resistor R5 is connected to the non-inverting input of operational amplifier U1, and the second end of resistor R5 is grounded. Operational amplifier U1 and its peripheral circuits form an amplification circuit, which amplifies the voltage difference across sampling resistor R1 and outputs a detection voltage proportional to the load current. The first terminal of resistor R6 is connected to the power supply VCC, the second terminal of resistor R6 is connected to the first terminal of resistor R7, the second terminal of resistor R7 is grounded, the inverting input terminal of operational amplifier U2 is connected to the second terminal of resistor R6, the non-inverting input terminal of operational amplifier U2 is connected to the output terminal of operational amplifier U1, and the output terminal of operational amplifier U2 is connected to the positive terminal of diode D1. The first terminal of resistor R8 is connected to the power supply VCC, the second terminal of resistor R8 is connected to the first terminal of resistor R9, the second terminal of resistor R9 is grounded, the non-inverting input terminal of operational amplifier U3 is connected to the second terminal of resistor R8, the inverting input terminal of operational amplifier U3 is connected to the output terminal of operational amplifier U1, and the output terminal of operational amplifier U3 is connected to the positive terminal of diode D2. The voltage at the inverting input of operational amplifier U2 is less than the voltage at the non-inverting input of operational amplifier U3. The window comparator structure can simultaneously detect both overcurrent and undercurrent abnormal states of the load. This not only prevents overcurrent from burning out load components, but also identifies undercurrent faults such as loose connections and open windings, providing a wider detection range and more comprehensive protection. The negative terminals of diodes D1 and D2 are both connected to the input terminal of inverter U4. The first terminal of pull-down resistor R15 is connected to the input terminal of inverter U4, and the second terminal of pull-down resistor R15 is grounded. When diodes D1 and D2 are off, pull-down resistor R15 pulls the voltage at the input terminal of inverter U4 to a low level.

[0020] Specifically, the control branch 2011 includes an OR gate U5, resistors R10 and R11, transistor Q1, resistor R12, indicator light L1, diode D3 and relay KA, and transistor Q1 is an NPN transistor. In different detection branches 2010, the output of inverter U4 is connected to different inputs of OR gate U5. The output of OR gate U5 is connected to the first terminal of resistor R10. The second terminal of resistor R10 is connected to the base of transistor Q1. The first terminal of resistor R11 is connected to the base of transistor Q1, and the second terminal of resistor R11 is grounded. The first terminal of resistor R12 is connected to power supply VCC, and the second terminal of resistor R12 is connected to the first terminal of indicator light L1. The second terminal of indicator light L1 is connected to the collector of transistor Q1, and the emitter of transistor Q1 is grounded. The anode of diode D3 is connected to the second terminal of indicator light L1, and the cathode of diode D3 is connected to power supply VCC. The first terminal of relay KA is connected to power supply VCC, and the second terminal of relay KA is connected to the second terminal of indicator light L1. Relay KA is used to control the detection switch S2 to open. The output of inverter U4 in all detection branches 2010 is connected to different inputs of OR gate U5. OR gate U5 performs an OR logic operation on all input signals: when all forklift loads 3... When all branches 00 are working normally, all inverters U4 output a low level, and OR gate U5 outputs a low level. This low level is transmitted to the base of transistor Q1 through current-limiting resistor R10. At the same time, the base current-limiting resistor R11 pulls the base voltage down to ground potential, transistor Q1 is in the off state, the power supply circuit of indicator L1 and relay KA is disconnected, indicator L1 is off, relay KA is de-energized, detection switch S2 remains normally closed, and the vehicle power supply is normal. When any detection branch 2010 detects an overcurrent or undercurrent abnormality in the load, the corresponding inverter U4 outputs a high level, OR gate U5 outputs a high level after OR operation, the base of transistor Q1 is energized and conducts, the power supply circuit of indicator L1 and relay KA is connected, indicator L1 lights up to indicate that the vehicle has a fault and needs emergency stop, relay KA is energized and the armature is attracted, driving detection switch S2 to open, cutting off the main power supply circuit of the vehicle, realizing automatic emergency stop protection.

[0021] In this embodiment, please refer to Figure 3 The key switch 202 includes switch S3, and the delay circuit 203 includes resistor R14 and capacitor C1. Emergency stop switch S1 and detection switch S2 are both normally closed switches, and switch S3 is a normally open switch. Emergency stop switch S1, detection switch S2, and switch S3 are connected in series in the positive power supply line of battery pack 100 to form a three-level series power-off protection structure. The power supply to the whole vehicle can be cut off if any one switch is opened. The first terminal of emergency stop switch S1 is connected to the positive terminal of battery pack 100. The second terminal of emergency stop switch S1 is connected to the first terminal of detection switch S2. The second terminal of detection switch S2 is connected to the first terminal of switch S3. The second terminal of switch S3 is connected to the first terminal of resistor R14. The second terminal of resistor R14 is connected to the first terminal of forklift load 300. The first terminal of capacitor C1 is connected to the second terminal of resistor R14. The second terminal of capacitor C1 is connected to the negative terminal of battery pack 100. The second terminal of forklift load 300 is connected to the negative terminal of battery pack 100.

[0022] In this embodiment, please refer to Figure 3 , Figure 4 and Figure 5 The switch control circuit 200 also includes several indicator branches 2012, each of which corresponds to a detection branch 2010. The indicator branch 2012 includes a resistor R13 and an indicator light L2. The first terminal of the indicator light L2 is grounded, and the second terminal of the indicator light L2 is connected to the first terminal of the resistor R13. The second terminal of the resistor R13 is connected to the output terminal of the inverter U4 in the corresponding detection branch 2010, so as to indicate which specific load has a problem.

[0023] Additionally, in the attached diagram, the suffix 'a' represents the first load branch, 'n' represents the nth load branch, and the sampling resistor R1a represents the sampling resistor R1 in the first load branch. The suffix is ​​only used to distinguish the branches.

[0024] In the initial state of use, the emergency stop switch S1 and detection switch S2 of the emergency stop circuit 201 are kept normally closed, the switch S3 of the key switch 202 is kept normally open, and all detection branches 2010, control branches 2011 and delay circuit 203 are not powered.

[0025] After the operator inserts the special key and rotates to close switch S3, the main power supply circuit is turned on, and the current is output from the positive terminal of battery pack 100. It passes through the normally closed emergency stop switch S1, detection switch S2, and closed switch S3 in sequence, and flows into resistor R14 of delay circuit 203. Then, it charges capacitor C1. The voltage across capacitor C1 rises slowly according to the RC charging curve until it reaches the rated operating voltage of forklift load 300, and then it is powered on, realizing soft start and avoiding damage to the sensitive components of forklift load 300 by the inrush current at the moment the switch is closed.

[0026] When the vehicle is powered on, each detection branch 2010 of the emergency stop circuit 201 monitors the working status of the corresponding forklift load branch 300 in real time: the sampling resistor R1 converts the working current of the corresponding load branch into a voltage difference between the two ends, and the voltage difference is amplified to output a detection voltage that is proportional to the load current; resistors R6 and R7 divide the power supply VCC to provide an undercurrent threshold voltage for the inverting input of operational amplifier U2, and resistors R8 and R9 divide the power supply VCC to provide an overcurrent threshold voltage for the non-inverting input of operational amplifier U3; When the load current is in the normal range, the detection voltage is between two thresholds, both operational amplifiers U2 and U3 output high level, diodes D1 and D2 are turned on, the input of inverter U4 is pulled high, the pull-down resistor R15 is clamped, and inverter U4 outputs low level to the input of OR gate U5 of control branch 2011. When all detection branches 2010 output a low level, OR gate U5 outputs a low level, which is transmitted to the base of transistor Q1 through resistor R10. Resistor R11 pulls the base voltage down to ground potential, transistor Q1 is in the cut-off state, the power supply circuit of indicator light L1 and relay KA is disconnected, indicator light L1 goes out, relay KA is de-energized, detection switch S2 remains in the normally closed state, and the power supply of the whole vehicle is normal.

[0027] When any forklift load 300 experiences an overcurrent or undercurrent fault, the detection voltage output by operational amplifier U1 in the corresponding detection branch 2010 is higher than the overcurrent threshold or lower than the undercurrent threshold. Operational amplifiers U2 and U3 both output a low level, diodes D1 and D2 are both cut off, and pull-down resistor R15 pulls the input terminal of inverter U4 to a low level, causing inverter U4 to output a high level. After the high-level input control branch 2011 is connected to the OR gate U5, the OR gate U5 outputs a high level after the OR operation. After being current-limited by resistor R10, it is input to the base of transistor Q1. Transistor Q1 is saturated and conducts. The power supply VCC forms a circuit through resistor R12 and the conducting transistor Q1: the red indicator light L1 is energized and illuminates, indicating that the whole vehicle has entered the fault emergency stop state; the relay KA is energized and engages, which drives the linked detection switch S2 to disconnect the main power supply circuit and cut off the power supply of battery pack 100 to forklift load 300; diode D3 is connected in parallel across the coil of relay KA to absorb the reverse electromotive force at the moment of coil de-energization and avoid damage to components by peak voltage; At the same time, the high level output of the inverter U4 corresponding to the faulty branch flows into the resistor R13 of the corresponding indicator branch 2012, lighting up the corresponding indicator L2 to indicate the specific faulty load branch, facilitating quick troubleshooting.

[0028] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A forklift electrical switch control circuit integrating delayed start and emergency stop functions, comprising a switch control circuit (200) connected between a battery pack (100) and a forklift load (300), characterized in that: The switch control circuit (200) includes an emergency stop circuit (201), a key switch (202), and a delay circuit (203). The emergency stop circuit (201) includes an emergency stop switch S1, a detection switch S2, several detection branches (2010), and a control branch (2011). The emergency stop switch S1, the detection switch S2, and the key switch (202) are all connected in series in the power supply circuit of the battery pack (100). The several detection branches (2010) detect the working state of the forklift load (300) based on the sampling circuit and the window comparator. The control branch (2011) is used to perform an OR operation on the output results of the several detection branches (2010) and control the state of the detection switch S2. The delay circuit (203) extends the power-on time based on the RC circuit.

2. The electric switch control circuit of the integrated time-delay start and emergency stop function for a forklift truck according to claim 1, characterized in that: The detection branch (2010) includes sampling resistor R1, resistor R2, resistor R3, resistor R4, resistor R5, operational amplifier U1, power supply VCC, resistor R6, resistor R7, operational amplifier U2, diode D1, resistor R8, resistor R9, operational amplifier U3, diode D2, inverter U4 and pull-down resistor R15. The sampling resistor R1 is connected in series in the load branch of the forklift load (300). The first end of the resistor R2 is connected to the first end of the sampling resistor R1, and the second end of the resistor R2 is connected to the inverting input of the operational amplifier U1. The first end of the resistor R3 is connected to the second end of the sampling resistor R1, and the second end of the resistor R3 is connected to the non-inverting input of the operational amplifier U1. The first end of the resistor R4 is connected to the inverting input of the operational amplifier U1, and the second end of the resistor R4 is connected to the output of the operational amplifier U1. The first end of the resistor R5 is connected to the non-inverting input of the operational amplifier U1, and the second end of the resistor R5 is grounded. The first terminal of resistor R6 is connected to the power supply VCC, the second terminal of resistor R6 is connected to the first terminal of resistor R7, the second terminal of resistor R7 is grounded, the inverting input terminal of operational amplifier U2 is connected to the second terminal of resistor R6, the non-inverting input terminal of operational amplifier U2 is connected to the output terminal of operational amplifier U1, and the output terminal of operational amplifier U2 is connected to the positive terminal of diode D1. The first terminal of resistor R8 is connected to the power supply VCC, the second terminal of resistor R8 is connected to the first terminal of resistor R9, the second terminal of resistor R9 is grounded, the non-inverting input terminal of operational amplifier U3 is connected to the second terminal of resistor R8, the inverting input terminal of operational amplifier U3 is connected to the output terminal of operational amplifier U1, and the output terminal of operational amplifier U3 is connected to the positive terminal of diode D2. The voltage at the inverting input of operational amplifier U2 is less than the voltage at the non-inverting input of operational amplifier U3; The negative terminals of diodes D1 and D2 are both connected to the input terminal of inverter U4. The first terminal of pull-down resistor R15 is connected to the input terminal of inverter U4, and the second terminal of pull-down resistor R15 is grounded.

3. The electric switch control circuit of the integrated time-delay start and emergency stop function for a forklift truck according to claim 2, characterized in that: The control branch (2011) includes an OR gate U5, resistors R10 and R11, transistor Q1, resistor R12, indicator light L1, diode D3 and relay KA, and transistor Q1 is an NPN transistor. The output terminals of inverter U4 in different detection branches (2010) are respectively connected to different input terminals of OR gate U5. The output terminal of OR gate U5 is connected to the first terminal of resistor R10. The second terminal of resistor R10 is connected to the base of transistor Q1. The first terminal of resistor R11 is connected to the base of transistor Q1. The second terminal of resistor R11 is grounded. The first terminal of resistor R12 is connected to power supply VCC. The second terminal of resistor R12 is connected to the first terminal of indicator light L1. The second terminal of indicator light L1 is connected to the collector of transistor Q1. The emitter of transistor Q1 is grounded. The anode of diode D3 is connected to the second terminal of indicator light L1. The cathode of diode D3 is connected to power supply VCC. The first terminal of relay KA is connected to power supply VCC. The second terminal of relay KA is connected to the second terminal of indicator light L1. Relay KA is used to control the detection switch S2 to open.

4. The forklift electrical switch control circuit with integrated delayed start and emergency stop functions according to claim 1, characterized in that: The key switch (202) includes switch S3, the delay circuit (203) includes resistor R14 and capacitor C1, the emergency stop switch S1 and detection switch S2 are both normally closed switches, and switch S3 is a normally open switch. The first terminal of the emergency stop switch S1 is connected to the positive terminal of the battery pack (100), the second terminal of the emergency stop switch S1 is connected to the first terminal of the detection switch S2, the second terminal of the detection switch S2 is connected to the first terminal of switch S3, the second terminal of switch S3 is connected to the first terminal of resistor R14, the second terminal of resistor R14 is connected to the first terminal of the forklift load (300), the first terminal of capacitor C1 is connected to the second terminal of resistor R14, the second terminal of capacitor C1 is connected to the negative terminal of the battery pack (100), and the second terminal of the forklift load (300) is connected to the negative terminal of the battery pack (100).

5. The integrated delay start and emergency stop function forklift electrical switch control circuit of claim 2, wherein: The switch control circuit (200) further includes several indicator branches (2012), each of which corresponds one-to-one with the detection branch (2010); The indicator branch (2012) includes a resistor R13 and an indicator light L2. The first end of the indicator light L2 is grounded, the second end of the indicator light L2 is connected to the first end of the resistor R13, and the second end of the resistor R13 is connected to the output terminal of the inverter U4 in the corresponding detection branch (2010).

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