Emergency direct current power supply system of grab and engineering vehicle

Abstract

The utility model relates to the technical field of material grabbing machine power supply, provide a material grabbing machine emergency direct current power supply system and engineering vehicle, including main power supply loop and the standby power supply loop of access main power supply loop, emergency drive loop and material grabbing drive loop, and with the emergency starting loop of standby power supply loop connection, in main power supply loop access standby power supply loop, when the AC input end interruption input, by standby power supply loop output power supply to emergency drive loop to drive material grabbing drive loop, effectively solve the problem that the power grid sudden failure power failure leads to material falling, guarantee equipment use safety, reduce the security risk that the sudden power failure caused, simultaneously by standby power supply loop output power supply to emergency starting loop and carry out emergency starting, provide walking power source, support equipment mobile scene, guarantee the normal execution of production work.

Description

Technical Field

[0001] This utility model relates to the field of power supply technology for material handling machines, and in particular to an emergency DC power supply system for material handling machines and an engineering vehicle. Background Technology

[0002] Existing power control systems for electric trolley construction machinery typically do not install generators or power batteries. Instead, they are connected to the mains power supply and equipped with a switching power supply to convert the 220V AC mains power into 24V DC low-voltage electricity to supply the low-voltage electrical appliances or power control circuits on the equipment.

[0003] High-power electrical appliances on tethered construction machinery (such as work motors, air conditioners, and other appliances compatible with mains voltage) are controlled by a low-voltage DC power supply control circuit. Tethered construction machinery also contains various controllers, work lights, solenoid valves, GPS devices, and other low-voltage electrical appliances. These low-voltage appliances are typically powered by a 24V DC power supply, and the total current of the entire DC power system is often quite large.

[0004] For material handling machines that use switching power supplies as the low-voltage DC power supply for the control system, existing technical solutions can meet the power supply requirements of the material handling operation control system; however, in harsh power grid environments, existing technical solutions have the following shortcomings: (1) When the material grabber is in a power grid environment with unstable voltage and frequent fluctuations, the electronic components in the switching power supply will be quickly damaged or aged. The switching power supply will often be damaged in a short time, and therefore cannot provide stable low-voltage DC power.

[0005] (2) When the material grabber is picking up material and it is suspended in the air, if the power grid suddenly fails and the power supply fails, the material grabber will immediately lose its power and control power, thus stopping the machine. This will cause the electromagnet to demagnetize, the material to fall, and create a safety hazard. In addition, the inability to move and relocate due to the loss of power will hinder on-site construction. Utility Model Content

[0006] This utility model provides an emergency DC power supply system and engineering vehicle for a material grabber, which solves the technical problems that the existing material grabber power supply system cannot provide a stable voltage source, cannot effectively deal with sudden failures, lacks emergency functions, and poses a safety hazard of material falling.

[0007] To solve the above technical problems, this utility model provides an emergency DC power supply system for a material handling machine, including a main power circuit, a controller, a backup power circuit, an emergency drive circuit, and a material handling drive circuit connected to the main power circuit, as well as an emergency start circuit connected to the backup power circuit; the input end of the backup power circuit is connected to the input end of the main power circuit, and the output end is connected to the output circuit of the main power circuit and connected to the emergency start circuit and the controller. When the AC input terminal is interrupted, the backup power supply circuit outputs power to the emergency drive circuit / emergency start circuit to drive the material grabbing drive circuit / perform an emergency start.

[0008] This basic solution integrates a backup power circuit into the main power circuit. When the AC input is interrupted, the backup power circuit outputs power to the emergency drive circuit to drive the material grabbing drive circuit. This effectively solves the problem of material falling due to sudden power outages, ensuring equipment safety and reducing safety hazards caused by sudden power outages. At the same time, the backup power circuit outputs power to the emergency start circuit for emergency start-up, providing a power source for movement, supporting equipment relocation, and ensuring the normal execution of production.

[0009] In a further embodiment, the main power supply circuit includes a molded case circuit breaker QF1, a rectifier circuit, a controller, and a control branch; the input terminal of the rectifier circuit is connected to the AC input terminal through the molded case circuit breaker QF1, and the output terminal is connected to the controller and the control branch as a power output terminal; the material gripping drive circuit is connected to the AC input terminal through the molded case circuit breaker QF1; the controller is connected to at least one solenoid valve.

[0010] In this solution, the molded case circuit breaker QF1 serves as the main power supply access point, ensuring circuit safety through safety isolation; it is connected to the rectifier circuit for power conversion and voltage stabilization control, providing stable low-voltage DC power to ensure the normal operation of the equipment, thereby improving the stability and safety of the operating system of the trolley-mounted material handling machine.

[0011] In a further embodiment, the control branch includes a first switch S1, a normally closed contact of contactor KM1, and contactor KM. The first switch S1, the normally closed contact of contactor KM1, and the coil of contactor KM are connected in sequence. The main contact of contactor KM is connected in series in the main circuit of the material gripping drive circuit to perform the switching control of the material gripping drive circuit.

[0012] This scheme sets up a system that sequentially connects the first switch S1, the normally closed contact of contactor KM1, and the coil of contactor KM. By using the series connection of the normally closed contact of contactor KM1 and the coil of contactor KM, the control branch and the emergency drive circuit are interlocked, thereby avoiding drive control chaos, realizing emergency switching control between the main power supply and the backup power supply, ensuring the normal operation of the equipment, and thus improving the stability, safety, convenience, and economy of the material handling machine.

[0013] In a further embodiment, the material handling drive circuit includes an excitation cabinet and an electromagnet. The excitation cabinet is connected to the AC input terminal through a molded case circuit breaker QF1 and connected to the electromagnet through the main contacts of a contactor KM. The main contacts of the contactor KM are normally open contacts.

[0014] This solution uses the main contacts of contactor KM between the excitation cabinet and the electromagnet to control whether contactor KM is energized, thereby controlling the power supply of the material handling drive circuit (indirectly controlling the on / off state of the electromagnet by controlling the energization and de-energization of KM), and achieves remote monitoring and fault diagnosis through integrated control.

[0015] In a further embodiment, the backup power circuit includes a charger, a second switch S2, a third switch S3, a molded case circuit breaker QF2, an energy storage battery, and a current sensing switch C1. The coil of the current sensing switch C1 is connected to the AC input terminal, and the two pairs of linkage contacts of the current sensing switch C1 are respectively connected to the emergency drive circuit and the emergency start circuit; the output terminal of the charger is connected to the energy storage battery through the second switch S2, and the input terminal is connected to the input terminal of the main power circuit; the first output terminal of the energy storage battery is connected to the power output terminal of the main power circuit through the third switch S3, and is also connected to the emergency drive circuit and the emergency start circuit through the molded case circuit breaker QF2; The linkage contact of the current sensing switch C1 is a normally closed contact.

[0016] This solution connects the charger directly to the AC input terminal, controls the charging of the energy storage battery through the second switch S2, and controls the power supply output of the energy storage battery through the third switch S3. Based on the real-time detection of the AC input status by the current sensing switch C1, the power supply is automatically switched, resulting in a high degree of automation and good emergency feedback performance.

[0017] In a further embodiment, the backup power circuit also includes the main contacts of contactor KM1 and contactor KM2 connected to the molded case circuit breaker QF2, the second output terminal of the energy storage battery connected to the molded case circuit breaker QF2, the main contacts of contactor KM1 connected to the molded case circuit breaker QF2 and the material handling drive circuit, and the main contacts of contactor KM2 connected to the molded case circuit breaker QF2 and the emergency start circuit.

[0018] This solution sets up the main contacts of contactor KM1 connected in series with the material handling drive circuit and the main contacts of contactor KM2 connected in series with the emergency start circuit. Remote control of the equipment is achieved through the inductive control of the main contacts and the coil. The emergency power input of the equipment is triggered by the energization of the coil. The solution is easy to operate and low in cost.

[0019] In a further embodiment, the emergency drive circuit includes the coil of contactor KM1, the normally closed contact of contactor KM2, and a warning light. A pair of linkage contacts of the current sensing switch C1 are connected to one end of the normally closed contact of contactor KM2, and the other end of the normally closed contact of contactor KM2 is connected to the coil of contactor KM1. The warning light is connected to a pair of linkage contacts of the current sensing switch C1. When the AC input is interrupted, the coil of the current sensing switch C1 is de-energized, its linkage contact closes, the coil of the contactor KM1 is energized, and the power supply circuit between the backup power circuit and the material handling drive circuit is connected; and the warning light is energized to provide emergency indication. This solution achieves automatic power detection and switching by connecting a pair of linked contacts of the current sensing switch C1 in series in the emergency drive circuit, effectively solving the problem of electrical device failure caused by power grid faults.

[0020] In a further embodiment, the emergency start circuit includes a start branch connected to the first output terminal of the backup power circuit. The start branch includes a fourth switch S4, a normally closed contact of contactor KM1, and a coil of contactor KM2. The other pair of linkage contacts of the current sensing switch C1, the fourth switch S4, the normally closed contact of contactor KM1, and the coil of contactor KM2 are connected in sequence. When the AC input terminal is interrupted, the coil of the current sensing switch C1 is de-energized, its linkage contact closes, the fourth switch S4 closes, the coil of the contactor KM2 is energized, and the power supply circuit between the backup power circuit and the emergency start circuit is connected. The normally closed contacts of contactor KM1 and the coil of contactor KM2, which are connected in series, form an interlocking mechanism.

[0021] In a further embodiment, the emergency start circuit also includes an emergency power station connected to the second output terminal of the backup power circuit. The emergency power station includes a hydraulic pump and a DC motor. The DC motor is connected to the main contact of the contactor KM2 to drive the hydraulic pump to provide emergency power.

[0022] This solution features a DC emergency power station and corresponding emergency start circuit, which prevents the equipment from having a short-term operating and moving power source after a power grid failure, thus preventing it from becoming immobilized and hindering production. Simultaneously, an interlocking mechanism is formed using the normally closed contacts of contactor KM1 and the coil of contactor KM2, connected in series, to provide directional power output control. This avoids insufficient power or drive malfunctions, ensuring the independent execution of the material handling machine's picking and moving functions in emergency situations. Furthermore, the use of a DC motor instead of a conventional AC motor eliminates the need for an inverter, reducing costs.

[0023] This utility model also provides an engineering vehicle, including an emergency DC power supply system for a material handling machine as described above. Attached Figure Description

[0024] Figure 1 This is a system framework diagram of an emergency DC power supply system for a material handling machine provided in an embodiment of this utility model; Figure 2 This is provided by the embodiment of the present utility model. Figure 1 PLC control circuit diagram; The circuit consists of: main power supply circuit 1, rectifier circuit 11, control branch circuit 12; backup power supply circuit 2, charger 21, energy storage battery 22; emergency drive circuit 3, material grabbing drive circuit 4, excitation cabinet 41, electromagnet 42; emergency start circuit 5 (not marked in the figure), start branch circuit 51, emergency power station 52; controller E1; hydraulic pump P, DC motor M, warning light H1. Detailed Implementation

[0025] The embodiments of this utility model are described in detail below with reference to the accompanying drawings. The embodiments are given for illustrative purposes only and should not be construed as limiting the utility model. The accompanying drawings are for reference and illustration only and do not constitute a limitation on the scope of patent protection of this utility model, because many changes can be made to this utility model without departing from the spirit and scope of this utility model.

[0026] Example 1 This utility model provides an emergency DC power supply system for a material handling machine, such as... Figure 1 , Figure 2 As shown, in this embodiment, it includes a main power circuit 1, a controller E1, a backup power circuit 2, an emergency drive circuit 3, and a material grabbing drive circuit 4 connected to the main power circuit 1, as well as an emergency start circuit 5 connected to the backup power circuit 2; the input terminal of the backup power circuit 2 is connected to the input terminal of the main power circuit 1, and the output terminal is connected to the output circuit of the main power circuit 1 and connected to the emergency start circuit 5 and the controller E1. When the AC input terminal (such as 220V AC mains input) is interrupted, the backup power supply circuit 2 outputs power to the emergency drive circuit 3 / emergency start circuit 5 to drive the material grabbing drive circuit 4 / perform an emergency start.

[0027] In a further embodiment, the main power supply circuit 1 includes a molded case circuit breaker QF1, a rectifier circuit 11, and a control branch 12; the input terminal of the rectifier circuit 11 is connected to the AC input terminal through the molded case circuit breaker QF1, and the output terminal is connected to the controller E1 and the control branch 12 as a power output terminal; the material gripping drive circuit 4 is connected to the AC input terminal through the molded case circuit breaker QF1; the controller E1 is connected to at least one solenoid valve.

[0028] Among them, at least one solenoid valve (as shown in the attached document) Figure 2 The functions performed by A1, A2, A3, A4, A5, A6, A7, and A8 in the code include, but are not limited to, left track forward, right track forward, left track backward, right track backward, boom lowering, boom raising, stick retraction, and stick extension.

[0029] The rectifier circuit 11 used in this embodiment is a conventional circuit in the art, and will not be described in detail here.

[0030] In this solution, the molded case circuit breaker QF1 serves as the main power supply access point, ensuring circuit safety through safety isolation; it is connected to the rectifier circuit 11 for power conversion and voltage stabilization control, providing stable low-voltage DC power to ensure the normal operation of the equipment, thereby improving the stability and safety of the operating system of the trolley-type material grabber.

[0031] In a further embodiment, the control branch 12 includes a first switch S1, a normally closed contact of contactor KM1, and contactor KM. The first switch S1, the normally closed contact of contactor KM1, and the coil of contactor KM are connected in sequence. The main contact of contactor KM is connected in series in the main circuit of the material gripping drive circuit 4 to perform the switching control of the material gripping drive circuit 4.

[0032] This scheme sets up a system that sequentially connects the first switch S1, the normally closed contact of contactor KM1, and the coil of contactor KM. By using the series connection of the normally closed contact of contactor KM1 and the coil of contactor KM, the control branch 12 and the emergency drive circuit 3 are interlocked, thereby avoiding drive control chaos, realizing emergency switching control between the main power supply and the backup power supply, ensuring the normal operation of the equipment, and thus improving the stability, safety, convenience, and economy of the material handling machine.

[0033] In a further embodiment, the material handling drive circuit 4 includes an excitation cabinet 41 and an electromagnet 42. The excitation cabinet 41 is connected to the AC input terminal through a molded case circuit breaker QF1 and is connected to the electromagnet 42 through the main contacts of a contactor KM. The main contacts of the contactor KM are normally open contacts.

[0034] This solution uses the main contacts of contactor KM between the excitation cabinet and the electromagnet to control whether contactor KM is energized, thereby controlling the energization of the material handling drive circuit 4 (indirectly controlling the on / off state of the electromagnet by controlling the energization and de-energization of KM), and achieves remote monitoring and fault diagnosis through integrated control.

[0035] In a further embodiment, the backup power circuit 2 includes a charger 21, a second switch S2, a third switch S3, a molded case circuit breaker QF2, an energy storage battery 22, and a current sensing switch C1. The coil of the current sensing switch C1 is connected to the AC input terminal, and the two pairs of linkage contacts of the current sensing switch C1 are respectively connected to the emergency drive circuit 3 and the emergency start circuit 5; the output terminal of the charger 21 is connected to the energy storage battery 22 through the second switch S2, and the input terminal is connected to the input terminal of the main power circuit 1; the first output terminal of the energy storage battery 22 is connected to the power output terminal of the main power circuit 1 through the third switch S3, and is also connected to the emergency drive circuit 3 and the emergency start circuit 5 through the molded case circuit breaker QF2; The linkage contact of the current sensing switch C1 is a normally closed contact.

[0036] The first output terminal of the energy storage battery 22 outputs a 24V DC power supply.

[0037] This solution directly connects to the charger 21 at the AC input terminal, controls the charging of the energy storage battery 22 through the second switch S2, and controls the power supply output of the energy storage battery 22 through the third switch S3. Based on the current sensing switch C1, the AC input status is detected in real time and the power supply is automatically switched, which has a high degree of automation and good emergency feedback performance.

[0038] In a further embodiment, the backup power circuit 2 also includes the main contacts of contactor KM1 and contactor KM2 connected to the molded case circuit breaker QF2. The second output terminal of the energy storage battery 22 is connected to the molded case circuit breaker QF2. The main contacts of contactor KM1 are connected to the molded case circuit breaker QF2 and the material handling drive circuit 4. The main contacts of contactor KM2 are connected to the molded case circuit breaker QF2 and the emergency start circuit 5.

[0039] The second output terminal of the energy storage battery 22 outputs a 220V DC power supply.

[0040] That is, the energy storage battery 22 is electrically connected to the electromagnet through the main contacts of the molded case circuit breaker QF2 and the contactor KM1 in sequence, and the electrical protection of the backup power supply is performed by the molded case circuit breaker QF2.

[0041] This solution sets the main contacts of contactor KM1 connected in series with the material handling drive circuit 4 and the main contacts of contactor KM2 connected in series with the emergency start circuit 5. Remote control of the equipment is achieved through the induction control of the main contacts and the coil. The emergency power input of the equipment is triggered by the coil being energized. The solution is easy to operate and low in cost.

[0042] In a further embodiment, the emergency drive circuit 3 includes the coil of contactor KM1, the normally closed contact of contactor KM2, and the warning light H1. A pair of linkage contacts of the current sensing switch C1 are connected to one end of the normally closed contact of contactor KM2, and the other end of the normally closed contact of contactor KM2 is connected to the coil of contactor KM1. The warning light H1 is connected to a pair of linkage contacts of the current sensing switch C1. When the AC input is interrupted, the coil of the current sensing switch C1 is de-energized, its linkage contact closes, the coil of the contactor KM1 is energized, and the power supply circuit between the backup power circuit 2 and the material grabbing drive circuit 4 is connected; and the warning light H1 is energized to provide emergency indication. The specific emergency drive principle (i.e., electromagnet demagnetization prevention) is as follows: When the equipment is activated, close the molded case circuit breaker QF1, the second switch S2, and the third switch S3.

[0043] When the first control switch S1 is closed, and the AC input terminal is normally input, the current sensing switch C1 is energized, and its linkage contact is in the open state. Contactors KM1 and KM2 are not energized (emergency drive circuit 3 and emergency start circuit 5 do not work). At this time, the coil of contactor KM is energized, and its main contact closes, so the power supply is input from the excitation cabinet to the electromagnet for normal operation.

[0044] When the AC input is interrupted (three-phase power failure), the current sensing switch C1 is de-energized, and its linkage contact is in the closed state (normally closed contact closes when de-energized, opens when energized). The coil of contactor KM1 and the warning light H1 are energized. The coil of contactor KM is de-energized (normally closed contact of contactor KM1 opens), and the main contact of contactor KM opens. The main contact of contactor KM1 is attracted, and the electromagnet is supplied with DC220V power from the second output terminal of the energy storage battery 22.

[0045] At this time, since the coil of contactor KM1 is energized, its normally closed contact opens, and the emergency start circuit 5 is not connected.

[0046] This solution achieves automatic power detection and switching by connecting a pair of linked contacts of the current sensing switch C1 in series in the emergency drive circuit 3, effectively solving the problem of electrical device failure caused by power grid faults.

[0047] In a further embodiment, the emergency start circuit 5 includes a start branch 51 connected to the first output terminal of the backup power circuit 2. The start branch 51 includes a fourth switch S4, a normally closed contact of contactor KM1, and a coil of contactor KM2. The other pair of linkage contacts of the current sensing switch C1, the fourth switch S4, the normally closed contact of contactor KM1, and the coil of contactor KM2 are connected in sequence. When the AC input is interrupted, the coil of the current sensing switch C1 is de-energized, its linkage contact closes, the fourth switch S4 closes, the coil of the contactor KM2 is energized, and the power supply circuit between the backup power circuit 2 and the emergency start circuit 5 is connected. The normally closed contacts of contactor KM1 and the coil of contactor KM2, which are connected in series, form an interlocking mechanism.

[0048] In a further embodiment, the emergency start circuit 5 further includes an emergency power station 52 connected to the second output terminal of the backup power circuit 2. The emergency power station 52 includes a hydraulic pump P and a DC motor M. The DC motor M is connected to the main contact of the contactor KM2 to drive the hydraulic pump P to provide emergency power.

[0049] The specific emergency power start-up principle is as follows: When the equipment is activated, close the molded case circuit breaker QF1, the second switch S2, and the third switch S3.

[0050] When the first control switch S1 is closed, and the AC input terminal is normally input, the current sensing switch C1 is energized, and its linkage contact is in the open state. Contactors KM1 and KM2 are not energized, and the emergency drive circuit 3 and emergency start circuit 5 do not work. At this time, the coil of contactor KM is energized, and its main contact closes, so the emergency power station 52 does not work.

[0051] When the AC input is interrupted (three-phase power failure), the current sensing switch C1 is de-energized and its linkage contact is closed. At this time, the first switch S1 is opened and the fourth switch S4 is closed. The coil of contactor KM1 is not energized, the coil of contactor KM is de-energized, and contactor KM2 is energized (the normally closed contacts of contactor KM1 and contactor KM2 are interlocked). Its main contacts are attracted, and the second output terminal of the energy storage battery 22 outputs DC220V power to the DC motor to drive the hydraulic pump and provide emergency hydraulic power for the grabber. The operator controls the solenoid valves (A1, A2, A3, A4, A5, A6, A7, A8) through the controller E1 to complete the corresponding actions of the grabber's movement, boom and stick.

[0052] This solution configures a DC emergency power station 52, corresponding to the emergency start circuit 5, which can prevent the equipment from having a short-term operating and moving power source after a power grid failure, thus preventing it from being paralyzed and hindering production. At the same time, an interlocking mechanism is formed by the normally closed contacts of contactor KM1 and the coil of contactor KM2 in series, to perform directional control of power output, avoid insufficient power or drive confusion, and ensure the independent execution function of the material grabber's picking and moving actions in emergency situations. Furthermore, the use of a DC motor instead of a conventional AC motor eliminates the need for an inverter, reducing costs.

[0053] In this embodiment, the first switch S1, the second switch S2, and the third switch S3 can be selected as electrically operated switches (e.g., contactors), manually operated switches (e.g., circuit breakers such as push-button switches), or electronically controlled switches (e.g., soft starters) as needed. This embodiment does not impose any restrictions.

[0054] Example 2 This utility model embodiment also provides an engineering vehicle, including an emergency DC power supply system for a material handling machine as described in Embodiment 1 above.

[0055] In this embodiment of the invention, a backup power circuit 2 is connected to the main power circuit 1. When the AC input is interrupted, the backup power circuit 2 outputs power to the emergency drive circuit 3 to drive the material grabbing drive circuit 4, effectively solving the problem of material falling due to sudden power outages caused by grid failures, ensuring the safety of equipment use, and reducing the safety hazards caused by sudden power outages. At the same time, the backup power circuit 2 outputs power to the emergency start circuit 5 for emergency start-up, providing a power source for movement, supporting equipment relocation, and ensuring the normal execution of production work.

[0056] The above embodiments are preferred embodiments of the present utility model, but the embodiments of the present utility model are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present utility model shall be considered equivalent substitutions and shall be included within the protection scope of the present utility model.

Claims

1. An emergency DC power supply system for a material handling machine, characterized in that: It includes a main power circuit, a controller, a backup power circuit, an emergency drive circuit, and a material grabbing drive circuit connected to the main power circuit, as well as an emergency start circuit connected to the backup power circuit; the input end of the backup power circuit is connected to the input end of the main power circuit, and the output end is connected to the output circuit of the main power circuit and connected to the emergency start circuit and the controller. When the AC input terminal is interrupted, the backup power supply circuit outputs power to the emergency drive circuit / emergency start circuit to drive the material grabbing drive circuit / perform an emergency start.

2. The emergency DC power supply system for a material handling machine as described in claim 1, characterized in that: The main power supply circuit includes a molded case circuit breaker QF1, a rectifier circuit, a controller, and a control branch; the input terminal of the rectifier circuit is connected to the AC input terminal through the molded case circuit breaker QF1, and the output terminal is connected to the controller and the control branch as the power output terminal; the material gripping drive circuit is connected to the AC input terminal through the molded case circuit breaker QF1; the controller is connected to at least one solenoid valve.

3. The emergency DC power supply system for a material handling machine as described in claim 2, characterized in that: The control branch includes a first switch S1, a normally closed contact of contactor KM1, and contactor KM. The first switch S1, the normally closed contact of contactor KM1, and the coil of contactor KM are connected in sequence. The main contact of contactor KM is connected in series in the main circuit of the material gripping drive circuit to perform the switching control of the material gripping drive circuit.

4. The emergency DC power supply system for a material handling machine as described in claim 3, characterized in that: The material handling drive circuit includes an excitation cabinet and an electromagnet. The excitation cabinet is connected to the AC input terminal through a molded case circuit breaker QF1 and to the electromagnet through the main contacts of a contactor KM. The main contacts of the contactor KM are normally open contacts.

5. The emergency DC power supply system for a material handling machine as described in claim 4, characterized in that: The backup power circuit includes a charger, a second switch S2, a third switch S3, a molded case circuit breaker QF2, an energy storage battery, and a current sensing switch C1. The coil of the current sensing switch C1 is connected to the AC input terminal, and the two pairs of linkage contacts of the current sensing switch C1 are respectively connected to the emergency drive circuit and the emergency start circuit; the output terminal of the charger is connected to the energy storage battery through the second switch S2, and the input terminal is connected to the input terminal of the main power circuit; the first output terminal of the energy storage battery is connected to the power output terminal of the main power circuit through the third switch S3, and is also connected to the emergency drive circuit and the emergency start circuit through the molded case circuit breaker QF2; The linkage contact of the current sensing switch C1 is a normally closed contact.

6. The emergency DC power supply system for a material handling machine as described in claim 5, characterized in that: The backup power circuit also includes the main contacts of contactor KM1 and contactor KM2 connected to the molded case circuit breaker QF2. The second output terminal of the energy storage battery is connected to the molded case circuit breaker QF2. The main contacts of contactor KM1 are connected to the molded case circuit breaker QF2 and the material handling drive circuit. The main contacts of contactor KM2 are connected to the molded case circuit breaker QF2 and the emergency start circuit.

7. The emergency DC power supply system for a material handling machine as described in claim 6, characterized in that: The emergency drive circuit includes the coil of contactor KM1, the normally closed contact of contactor KM2, and a warning light. A pair of linkage contacts of the current sensing switch C1 are connected to one end of the normally closed contact of contactor KM2, and the other end of the normally closed contact of contactor KM2 is connected to the coil of contactor KM1. The warning light is connected to a pair of linkage contacts of the current sensing switch C1. When the AC input is interrupted, the coil of the current sensing switch C1 is de-energized, its linkage contact closes, the coil of the contactor KM1 is energized, and the power supply circuit between the backup power circuit and the material handling drive circuit is connected; and the warning light is energized to provide emergency indication.

8. The emergency DC power supply system for a material handling machine as described in claim 7, characterized in that: The emergency start circuit includes a start branch connected to the first output terminal of the backup power circuit. The start branch includes a fourth switch S4, a normally closed contact of contactor KM1, and a coil of contactor KM2. The other pair of linkage contacts of the current sensing switch C1, the fourth switch S4, the normally closed contact of contactor KM1, and the coil of contactor KM2 are connected in sequence. When the AC input terminal is interrupted, the coil of the current sensing switch C1 is de-energized, its linkage contact closes, the fourth switch S4 closes, the coil of the contactor KM2 is energized, and the power supply circuit between the backup power circuit and the emergency start circuit is connected. The normally closed contacts of contactor KM1 and the coil of contactor KM2, which are connected in series, form an interlocking mechanism.

9. The emergency DC power supply system for a material handling machine as described in claim 8, characterized in that: The emergency start circuit also includes an emergency power station connected to the second output terminal of the backup power circuit. The emergency power station includes a hydraulic pump and a DC motor. The DC motor is connected to the main contact of the contactor KM2 to drive the hydraulic pump to provide emergency power.

10. An engineering vehicle, characterized in that: Includes an emergency DC power supply system for a material handling machine as described in any one of claims 1 to 9.

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