Safety control method for working condition of forklift in field

Abstract

The application discloses a kind of field fork truck operating condition safety control methods, belong to fork truck safety control technical field.The scheme includes: the running speed signal of fork truck is acquired in real time by speed sensor;The lifting height state of portal frame is detected by proximity switch arranged on portal frame, and high level signal is output when the lifting height of portal frame is below set threshold, and when the lifting height of portal frame reaches or exceeds set threshold, output suspended signal;Speed signal and portal height state signal are received and judged simultaneously;When vehicle speed is greater than first speed threshold and portal height state signal is suspended signal, speed limit message is sent to engine control unit, and engine control unit limits the maximum running speed of vehicle to second speed threshold in response to the speed limit message;When portal height state signal recovers to high level signal, stop sending speed limit message, and cancel vehicle speed limit.The application realizes the linkage safety control of fork truck running speed and portal frame lifting height, effectively reduces the risk of overturning of fork truck in high portal frame state.

Description

Technical Field

[0001] This invention relates to the field of forklift safety control technology, specifically to a method for controlling the safety of forklift operation conditions in a factory, particularly applicable to, but not limited to, the safe control of the operating speed of internal combustion forklifts under 7 tons in high-lift conditions. Background Technology

[0002] Forklifts are widely used in warehousing, logistics, and manufacturing for loading, unloading, stacking, and short-distance transportation. As forklift applications continue to expand and operational requirements become increasingly stringent, forklift operation safety is receiving more and more attention.

[0003] Currently, forklifts lack identification systems and corresponding control methods when operating at high speeds and lifting masts, resulting in higher safety risks for forklifts in this state: when a forklift is traveling at high speed while the cargo is being lifted, the center of gravity of the entire vehicle increases and stability decreases, which can lead to dangerous situations such as tipping over, front and rear tipping over, and cargo being thrown out if the speed is too high.

[0004] The industry has also proposed several speed limiting solutions for forklift lifting height. For example, one forklift forklift lifting speed limiting device uses a limit switch fixed on the mast and a switch lever on the fork carriage. When the fork carriage rises to a certain height, the limit switch is activated, and the vector controller controls the motor speed based on the level signal. Another example is a high-lift mast speed limiting system, which uses multiple position sensors installed vertically on the mast. The fork carriage height signal is obtained through the cooperation of the sensing element and the position sensors, and the travel controller outputs a speed limiting signal to the travel motor.

[0005] However, after verification and analysis, the existing solutions still have the following shortcomings:

[0006] Firstly, mechanical contact detection methods, such as position sensors or limit switches, are often used. After long-term use, these methods are prone to wear and poor contact, which affects the reliability of detection and the accuracy of control.

[0007] Secondly, speed detection and gantry height detection are mostly independent systems, lacking a mechanism for coordinated judgment and dynamic linkage control of the two signals, making it difficult to achieve refined safety control based on real-time operating conditions.

[0008] Third, it lacks a mechanism for resetting the status and continuously monitoring after the speed limit is lifted, making it unable to effectively cope with flexible switching when the operating conditions change after the speed limit is triggered.

[0009] Fourth, the structural differences between fully free masts and non-fully free masts have not been fully considered in relation to the speed limit height threshold setting, making it difficult to adapt to the application needs of different types of forklifts.

[0010] To address the aforementioned issues, the industry urgently needs a reliable solution that can achieve intelligent and safe control of forklift operating speed and mast lifting height. Summary of the Invention

[0011] In view of the above, the present invention aims to provide a safety control method for forklift operation conditions in the field, so as to solve the technical problem that there is no effective safety control means when the forklift is running at high speed and the mast is in a high lifting state in the prior art.

[0012] The technical solution adopted in this invention is as follows:

[0013] This invention provides a method for safety control of forklift operation conditions within a factory, comprising the following steps:

[0014] S1. The forklift's operating speed signal is acquired in real time through a speed sensor, and the speed signal is transmitted to the instrument module.

[0015] In at least one of the possible implementations, the speed sensor is a vehicle speed sensor, installed at the output end of the forklift gearbox or at the drive wheel, to detect the vehicle's running speed in real time. The speed signal is transmitted to the instrument module via a hardwire or CAN bus, and the vehicle speed is displayed on the instrument in real time.

[0016] S2. The lifting height status of the gantry is detected by a proximity switch installed on the gantry. The proximity switch is a PNP type normally open switch. When the lifting height of the gantry is lower than a set threshold, the proximity switch outputs a high-level signal (such as 12V+). When the lifting height of the gantry reaches or exceeds the set threshold, the proximity switch is disconnected and outputs a floating signal. The height status signal output by the proximity switch is transmitted to the instrument module.

[0017] In at least one possible implementation, the proximity switch is powered by 12V+, and its output is connected to the signal input of the instrument module. The proximity switch is mounted on the outer mast of the forklift mast, with its sensing surface facing the lower mast moving parts, such as the inner mast or fork carriage. When the mast is in a lower position, the mast moving parts are within the sensing area of ​​the proximity switch, the switch is activated, and a 12V+ high-level signal is output. When the mast is raised to a certain height, the mast moving parts move out of the sensing area of ​​the proximity switch, the switch is deactivated, and the output is left suspended.

[0018] Therefore, the set threshold is determined according to the forklift mast type: if the forklift is equipped with a fully free mast, the set threshold is the lifting height after the fully free lifting cylinder has extended its full stroke; if the forklift is equipped with a non-fully free mast, the set threshold is 800mm.

[0019] S3. The instrument module simultaneously receives and judges the speed signal and the gantry height status signal.

[0020] The instrument module integrates a microprocessor and has signal acquisition, logic judgment and CAN communication functions. The instrument module acquires the frequency signal or pulse signal of the speed sensor in real time and converts it into the vehicle speed value. At the same time, it acquires the level signal of the proximity switch and judges its status, such as high level or floating.

[0021] S4. When the operating speed is less than or equal to the first speed threshold, the instrument module does not perform speed limit control. Preferably, the first speed threshold is 6.0 km / h. When the vehicle speed does not exceed 6.0 km / h, speed limit control is not triggered regardless of the mast's height, to ensure the forklift's normal operating efficiency under low-speed conditions.

[0022] S5. When the operating speed is greater than the first speed threshold and the gantry height status signal is a suspended signal, the instrument module sends a speed limit message to the engine control unit (ECU) via the CAN bus. The engine control unit responds to the speed limit message and limits the maximum operating speed of the vehicle to a second speed threshold, wherein the second speed threshold is less than the first speed threshold.

[0023] In at least one of the possible implementations, the second speed threshold is 5.0 km / h; when the vehicle speed exceeds 6.0 km / h and the gantry lifting height reaches or exceeds the set threshold (i.e., the proximity switch is suspended), the instrument module sends a speed limit command message to the ECU via the CAN bus. After receiving the message, the ECU responds and limits the maximum operating speed of the vehicle to 5.0 km / h.

[0024] In at least one of the possible implementations, the engine control unit limits the vehicle’s maximum operating speed to a second speed threshold while simultaneously limiting the forklift’s lifting speed to no more than 30% of the rated maximum lifting speed under full load.

[0025] S6. When the vehicle is in a speed-limited state, the instrument module continuously monitors the gantry height status signal. If the gantry height status signal remains suspended, the instrument module continuously sends the speed limit message to keep the vehicle in a speed-limited state. If the gantry height status signal switches to a high-level signal, the instrument module stops sending the speed limit message, cancels the vehicle speed limit, and resets the gantry height status judgment.

[0026] In other words, under speed-limited conditions, the instrument module monitors the signal changes of the proximity switch in real time. If the mast remains in the high-lift state (proximity switch suspended), the instrument module continuously sends speed-limiting messages to ensure the vehicle always maintains the speed limit. If the mast descends below the set threshold (proximity switch returns to high-level output), the instrument module stops sending speed-limiting messages, the ECU cancels the speed limit, and the vehicle returns to normal operating speed. Simultaneously, the instrument module resets the internal judgment flag for the mast height status, preparing for the next speed-limiting judgment.

[0027] In at least one possible implementation, the method further includes a power-on self-test step: after the forklift is started and powered on, the instrument module first executes a self-test program to check whether the signals of the speed sensor and the proximity switch are normal. If any sensor signal is detected to be abnormal, the instrument module issues a fault alarm signal and prohibits the vehicle from entering normal operating mode.

[0028] In at least one of the possible implementations, when the instrument module sends a speed limit message to the engine control unit via the CAN bus in step S5, the speed limit message includes a speed limit command identifier and a speed limit target value. After receiving the speed limit message, the engine control unit returns an acknowledgment message to the instrument module. If the instrument module does not receive the acknowledgment message within a preset time, it repeatedly sends the speed limit message until it receives an acknowledgment message or reaches the preset maximum number of retransmissions.

[0029] In at least one possible implementation, the method further includes an anomaly handling step: when the instrument module detects that the proximity switch has a signal switching frequency exceeding a preset threshold during vehicle operation, it determines that the proximity switch has malfunctioned, the instrument module issues a fault alarm signal and limits the maximum operating speed of the vehicle to the second speed threshold until the fault is cleared.

[0030] In at least one possible implementation, in step S6, after the gantry height status signal switches to a high-level signal, the instrument module, while stopping sending speed limit messages, records the occurrence time, duration, and vehicle operating parameters of this speed limit event, and provides a prompt through the instrument display unit.

[0031] Compared with existing technologies, the main design concept of this invention lies in achieving linkage control between forklift operating speed and mast lifting height through the coordinated detection of a speed sensor and a normally open proximity switch. At high speeds and with a high mast, a speed limit is automatically triggered, simultaneously limiting both operating and lifting speeds to improve overall vehicle stability. The instrument module continuously monitors the mast status, automatically maintaining or removing the speed limit without manual intervention. Different thresholds are set for fully free and non-fully free masts, offering strong adaptability. CAN bus communication is preferably used, providing fast response and an acknowledgment mechanism to ensure reliable command execution. Furthermore, through power-on self-testing and signal anomaly detection, timely alarms and safety measures are implemented in case of sensor failure, effectively preventing the removal of the speed limit device. If removed, the vehicle can only operate within safe limits, thus comprehensively improving safety and reliability. Attached Figure Description

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described below with reference to the accompanying drawings, wherein:

[0033] Figure 1 This is a flowchart illustrating the on-site forklift operation safety control method provided in an embodiment of the present invention. Detailed Implementation

[0034] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0035] This invention proposes a safety control method for forklift operation conditions within a factory, particularly applicable to internal combustion counterbalance forklifts under 7 tons, but not universally applicable. The control method described below can rely on a safety control system, specifically comprising the following hardware components:

[0036] (1) Speed ​​sensor, installed at the output end of the forklift gearbox or at the drive wheel of the drive axle, is used to detect the vehicle's running speed in real time. The speed sensor is preferably a Hall effect speed sensor or a magnetoelectric speed sensor, whose output is a frequency signal or a pulse signal, the frequency of which is proportional to the vehicle speed. The signal line of the speed sensor is connected to the vehicle speed signal input terminal of the instrument controller.

[0037] (2) A proximity switch, preferably a PNP type normally open inductive proximity switch, is installed on the outer mast of the forklift mast. The power supply voltage of the proximity switch can be selected as 12V+. Its output terminal is connected to the mast height signal input terminal of the instrument controller, and the sensing surface of the proximity switch faces the mast moving parts (such as the inner mast or fork carriage) below. When the mast is in a low position, the mast moving parts are in the sensing area of ​​the proximity switch, the proximity switch is turned on, and the output terminal outputs a 12V+ high-level signal; when the mast is raised to a certain height, the mast moving parts are removed from the sensing area of ​​the proximity switch, the proximity switch is turned off, the output terminal is suspended, that is, there is no output.

[0038] It can also be pointed out that the installation position of the proximity switch can be determined according to the speed limit height threshold: for a fully free gantry, the proximity switch is installed at the position of the inner gantry relative to the outer gantry after the fully free lifting cylinder has extended its full stroke, that is, the speed limit height is the lifting height after the fully free lifting cylinder has extended its full stroke; for a non-fully free gantry, the proximity switch is installed at the position of the inner gantry relative to the outer gantry when the gantry lifting height reaches 800mm, that is, the speed limit height is 800mm.

[0039] (3) The instrument module, also known as the instrument controller, refers to the combination instrument of the forklift. It integrates a microprocessor (MCU) and has multiple analog and digital signal acquisition interfaces, a CAN communication interface, and a display driver interface. The instrument controller receives the frequency signal from the speed sensor and the level signal from the proximity switch via hard wiring, and communicates with the engine control unit (ECU) via the CAN bus. The instrument controller is also connected to a display unit for real-time display of information such as vehicle speed, mast height status, and speed limit status.

[0040] And (4) the engine control unit mentioned above, which is the main controller of the forklift engine system, communicates with the instrument controller via the CAN bus, receives the speed limit message sent by the instrument controller and executes speed limit control. The ECU limits the maximum operating speed of the vehicle by controlling the amount of fuel injected by the engine or the speed governor.

[0041] Therefore, as Figure 1 As shown, the present invention provides an embodiment of a safety control method for in-plant forklift operation conditions. Corresponding to the aforementioned invention content, steps S1 and S2 are implemented through signal acquisition in step S103 below; step S3 is implemented through logical determination in steps S104 and S106; and steps S4, S5 and S6 are implemented through specific control logic in steps S105, S107~S108 and S109~S110 respectively.

[0042] The detailed steps are as follows:

[0043] Step S101: After the forklift is started and powered on, the instrument controller first performs system initialization, including: microprocessor register initialization, I / O port initialization, CAN communication initialization, display unit initialization, etc. After initialization is completed, the instrument controller enters the working state.

[0044] Step S102: The instrument controller executes the power-on self-test program, checking the following items in sequence:

[0045] (a) Speed ​​sensor signal detection: The instrument controller reads the signal input of the speed sensor and determines whether there is a valid frequency signal input; if no speed signal is detected within a preset time (e.g., 2 seconds) or the signal is obviously abnormal, such as the frequency is zero but the vehicle is actually in a drivable state, then the speed sensor is determined to be faulty.

[0046] (b) Proximity switch signal detection: The instrument controller reads the level signal input of the proximity switch and judges whether the signal state is normal. Understandably, a high level or a floating state are normal states, but short circuit or open circuit faults must be ruled out. If the signal is detected to be in an uncertain state or does not conform to the preset logic, the proximity switch is judged to be faulty.

[0047] (c) CAN communication detection: The instrument controller sends a diagnostic request message to the ECU via the CAN bus to detect whether the CAN communication link is normal; if no response message is received from the ECU within a preset time, the CAN communication is determined to be faulty.

[0048] If any abnormality is detected during the self-test, the instrument controller will issue a fault alarm signal through the display unit, such as, but not limited to, fault code display and audible and visual alarms, and will prohibit the vehicle from entering normal operating mode until the fault is resolved; if the self-test passes all tests, the instrument controller may display a prompt such as "system normal" and allow the vehicle to enter normal operating mode.

[0049] Step S103: During normal vehicle operation, the instrument controller collects the following signals in real time to achieve the functions of speed signal acquisition and gantry height signal acquisition:

[0050] (a) Speed ​​signal: The instrument controller reads the frequency signal or pulse signal from the speed sensor at a fixed sampling period (e.g., 10ms), and converts the frequency value into the real-time vehicle speed value V (unit: km / h) according to the pre-stored vehicle speed conversion coefficient; the conversion formula is: V = f × K, where f is the sensor output frequency (Hz) and K is the vehicle speed conversion coefficient (km·h). -1 / Hz), this coefficient is pre-calibrated based on parameters such as the forklift's tire radius and main reduction ratio and stored in the non-volatile memory of the instrument controller.

[0051] (b) Gantry height status signal: The instrument controller reads the level signal of the proximity switch at a fixed sampling period to determine its status. If the input terminal is 12V+ high level, it is determined that the gantry is in a low lifting state, that is, when the height is lower than the set threshold, and the status flag H=0; if the input terminal is in a floating state, specifically implemented by detecting a low level through an internal pull-up resistor, it is determined that the gantry is in a high lifting state, that is, when the height reaches or exceeds the set threshold, and the status flag H=1.

[0052] The instrument controller displays the real-time vehicle speed value V in the vehicle speed display area of ​​the instrument, and displays the mast height status in the indicator area of ​​the instrument in the form of icons or text.

[0053] Step S104: The instrument controller compares the real-time vehicle speed value V with the first speed threshold V1 for judgment. This is an important component for simultaneously receiving and judging the data. In this embodiment, V1 = 6.0 km / h.

[0054] If V ≤ V1, then proceed to step S105; if V > V1, then proceed to step S106.

[0055] Step S105: When the vehicle speed does not exceed 6.0 km / h, the instrument controller will not perform speed limit control regardless of the height of the gantry, and will continue to execute step S103 to continuously collect and monitor signals.

[0056] It should be noted that "no speed limit" here means that the active speed limit based on gantry height is not triggered, but the vehicle's original maximum design speed limit remains in effect.

[0057] Step S106: When the vehicle speed V > 6.0 km / h, the instrument controller further determines the value of the mast height status indicator H:

[0058] If H=0 (the gantry is in a low lifting state and the proximity switch outputs a high level), then step S105 is executed, and speed limit control is not performed;

[0059] If H=1 (the gantry is in a high-lift state and the proximity switch is suspended), then proceed to step S107.

[0060] Step S107: The instrument controller sends a speed limit message to the ECU via the CAN bus, initiating the speed limit control process mentioned above. The data frame format of the speed limit message can be referenced as follows: Message ID: Preset speed limit command identifier (e.g., 0x18FFXXXX); Data field: Contains the speed limit command code (e.g., 0x01 indicates speed limit execution) and the speed limit target value (e.g., 0x32 indicates 5.0 km / h).

[0061] After the instrument cluster controller sends a speed limit message, a timer starts to wait for a confirmation message from the ECU. Upon receiving the speed limit message, the ECU sends a confirmation message back to the instrument cluster controller, containing the same message ID and confirmation code. If the instrument cluster controller receives the confirmation message within a preset time (e.g., 100ms), it confirms that the speed limit command has been successfully received by the ECU. If no confirmation message is received within the timeout period, the instrument cluster controller resends the speed limit message, up to three times. If no confirmation message is received after three resends, the instrument cluster controller determines that CAN communication is abnormal and issues a communication fault alarm.

[0062] Step S108: After receiving and parsing the speed limit message, the ECU executes the following speed limit control to limit the vehicle's maximum operating speed to the second speed threshold:

[0063] (a) Operating speed limit: The ECU limits the vehicle's maximum operating speed to a second speed threshold V2 by controlling the engine's fuel injection quantity or adjusting the governor setting. In this embodiment, V2 = 5.0 km / h. That is, no matter how the driver operates the accelerator pedal, the vehicle's maximum operating speed will not exceed 5.0 km / h.

[0064] (b) Lifting speed limit: The ECU or hydraulic system controller simultaneously limits the lifting speed of the forklift to no more than 30% of the rated maximum lifting speed under full load. For example, if the rated maximum lifting speed of the forklift under full load is 400 mm / s, the lifting speed after speed limit shall not exceed 120 mm / s. This limit is achieved by controlling the oil supply flow of the lifting hydraulic system.

[0065] Step S109: When the vehicle is in a speed-limited state (i.e., V is limited to V2), the instrument controller continuously monitors the signal status of the proximity switch at a fixed sampling period to determine the value of the gantry height status flag H, thereby achieving continuous monitoring.

[0066] If H=1, it indicates that the gantry is still in the high-lift state and the proximity switch remains suspended. The instrument controller will continuously send speed limit messages at a fixed period (e.g., 500ms) to ensure that the vehicle maintains the speed limit state. This is because in actual applications, there may be situations such as CAN bus message loss or ECU state reset. Continuously sending speed limit messages can ensure the reliability of speed limit control.

[0067] If H=0, it indicates that the gantry has descended to the low lifting state, the proximity switch resumes output high level, and then step S110 is executed.

[0068] Step S110: When the instrument controller detects that the gantry height status signal changes from floating to high level (i.e., H changes from 1 to 0), perform the following operations to stop sending speed limit messages, cancel the vehicle speed limit, and reset the gantry height status judgment:

[0069] (a) Stop sending speed limit messages: The instrument controller stops sending speed limit messages to the ECU.

[0070] (b) Sending a speed limit cancellation message: Optionally, the instrument controller may send a speed limit cancellation command message to the ECU to explicitly notify the ECU to lift the speed limit status.

[0071] (c) ECU cancels speed limit: If the ECU does not receive a new speed limit message or receives a speed limit cancellation message within a preset time, it cancels the restrictions on the operating speed and lifting speed, and the vehicle returns to normal operation.

[0072] (d) Status Reset: The instrument controller resets the internal speed limit status flag and gantry height judgment flag to prepare for the next speed limit judgment.

[0073] (e) Event logging and notification: The instrument controller records relevant information about the speed limit event, including the speed limit trigger time, the duration of the speed limit, the vehicle speed and gantry height status at the time of the speed limit, and notifies the driver through the display unit that the speed limit has been lifted.

[0074] After completing the above operations, the instrument controller returns to step S103 to continue real-time signal acquisition and judgment.

[0075] Regarding special circumstances in forklift application scenarios, the present invention also proposes countermeasures for the following situations.

[0076] (a) If, during vehicle operation, the instrument controller detects that the proximity switch signal changes multiple times in a short period of time (e.g., within 1 second), and the number of times the signal switches between high level and floating exceeds the preset threshold (e.g., 3 times), it is determined that the proximity switch may be faulty, possibly due to a loose sensor, poor wiring contact, or damage to the sensor itself.

[0077] At this time, the instrument controller preferably performs the following operations:

[0078] (1) Issue a fault alarm signal, display the fault code through the display unit, and illuminate the fault indicator light on the instrument;

[0079] (2) Limit the maximum operating speed of the vehicle to the second speed threshold V2 = 5.0 km / h to ensure safety;

[0080] (3) Record fault information for reference in subsequent maintenance and diagnosis;

[0081] (4) Continuously monitor the proximity switch signal. If the signal stabilizes within a preset time (e.g., 10 seconds), the speed limit will be automatically lifted and the fault alarm will be cleared. If the signal remains abnormal, the speed limit will be maintained until the fault is cleared.

[0082] (ii) If the instrument controller detects a loss or obvious abnormality in the speed sensor signal during vehicle operation, such as a sudden drop in signal frequency to zero while the vehicle is still moving, the following operations shall be performed:

[0083] (1) Issue a fault alarm signal and display the fault code through the display unit;

[0084] (2) Since accurate vehicle speed information cannot be obtained, the instrument controller will default to the highest safety level, that is, assuming that the vehicle speed exceeds the first speed threshold and the gantry is in a high lifting state, and send a speed limit message to limit the vehicle speed to V2.

[0085] (3) At the same time, the instrument controller prompts the driver with information such as "vehicle speed sensor malfunction, please drive carefully" through the display unit;

[0086] (4) After the speed sensor signal returns to normal, the instrument controller will automatically resume normal control logic.

[0087] (iii) If the instrument controller does not receive an acknowledgment message from the ECU after sending the speed limit message and the retransmission reaches the maximum number of times, or if the instrument controller detects that the CAN bus is offline, then the CAN communication is deemed to have failed.

[0088] At this time, the instrument controller performs the following operations:

[0089] (1) Issue a communication failure alarm signal;

[0090] (2) Send a speed limit request to the ECU via a backup hardwire signal (if any), or output a speed limit signal via the fault output port of the instrument;

[0091] (3) If there is no available backup communication method, the instrument controller will prompt the driver with information such as "speed limit communication failure, please stop immediately for inspection" through the display unit;

[0092] (4) After the fault is cleared, the system will automatically return to normal operation.

[0093] (iv) When the speed limiting device, such as a proximity switch or its connecting wiring, is removed or malfunctions:

[0094] (1) If the proximity switch is removed, its output terminal is in a floating state. The instrument controller can detect the abnormality during the power-on self-test, and the signal status is inconsistent with the expectation. It will issue a fault alarm and prohibit the vehicle from entering the normal operation mode, thereby preventing illegal operation.

[0095] (2) If the proximity switch circuit is short-circuited to simulate a low gantry state, such as the output always being high level, the instrument controller can detect whether the signal is reasonable during the power-on self-test. For example, if the signal should change during the gantry lifting operation but does not actually change, the abnormality can be identified and a fault alarm can be issued.

[0096] (3) If the speed limiting function fails but the vehicle can still operate, the vehicle can only operate under technical conditions below the safety limits due to the lack of speed limiting control. That is, the operating speed shall not exceed 6.0 km / h, the lifting height of the forklift shall not exceed the speed limit height, or the lifting speed shall be limited to within 30% of the rated full load maximum lifting speed after exceeding the speed limit height.

[0097] Finally, it would be helpful to add the following explanation regarding the application examples of the different gantry types mentioned above:

[0098] (a) Fully free mast forklift: A 7-ton internal combustion counterbalance forklift is equipped with a fully free mast. The lifting height of the fully free lifting cylinder after its full stroke is extended is 1500mm. The proximity switch is installed on the outer mast with the sensing surface facing down. When the lifting height of the inner mast or fork carriage relative to the outer mast reaches 1500mm, the inner mast or fork carriage is removed from the sensing area of ​​the proximity switch, and the proximity switch is disconnected.

[0099] During forklift operation: When the forklift is unloaded or lightly loaded, and the speed is 4.0 km / h (≤6.0 km / h), there is no speed limit regardless of the mast lifting height; when the forklift is loaded, and the speed is 7.0 km / h (>6.0 km / h) and the mast lifting height is 1000 mm (<1500 mm, proximity switch output high level), there is no speed limit to ensure low-position operation efficiency; when the forklift is loaded, and the speed is 7.0 km / h (>6.0 km / h) and the mast lifting height is 1600 mm (≥1500 mm, proximity switch suspended), the speed limit is triggered, and the speed is limited to 5.0 km / h, while the lifting speed is limited to 30% of the rated full-load maximum lifting speed.

[0100] (ii) Non-fully free mast forklift: A 3-ton internal combustion counterbalance forklift is equipped with a non-fully free mast, with a speed limit height set at 800mm; a proximity switch is installed on the outer mast, and the proximity switch is disconnected when the mast lifting height reaches 800mm.

[0101] The control logic of the forklift during operation is the same as that of the fully free mast, but the speed limit height threshold is different: the speed limit is triggered when the mast lifting height reaches or exceeds 800mm and the vehicle speed exceeds 6.0km / h.

[0102] In this invention, when directional terms are mentioned, they are relative concepts based on the embodiments. Furthermore, "at least one" refers to one or more, and "more than one" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent the existence of A alone, A and B simultaneously, or B alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship. "At least one of the following" and similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, and c can represent: a, b, c, a and b, a and c, b and c, or a and b and c, where a, b, and c can be single or multiple.

[0103] The above description of the structure, features, and effects of the present invention is based on the embodiments shown in the figures. However, the above are only preferred embodiments of the present invention. It should be noted that the technical features involved in the above embodiments and their preferred methods can be reasonably combined and matched by those skilled in the art to form a variety of equivalent solutions without departing from or changing the design concept and technical effects of the present invention. Therefore, the present invention is not limited to the scope of implementation shown in the figures. Any changes made in accordance with the concept of the present invention, or modifications to equivalent embodiments, that do not exceed the spirit covered by the specification and figures, should be within the protection scope of the present invention.

Claims

1. A method for safety control of forklift operation conditions within a factory premises, characterized in that, include: S1. The speed signal of the forklift is acquired in real time through the speed sensor and the speed signal is transmitted to the instrument module; S2. The lifting height status of the gantry is detected by a proximity switch installed on the gantry. When the lifting height of the gantry is lower than a set threshold, the proximity switch outputs a high-level signal. When the lifting height of the gantry reaches or exceeds the set threshold, the proximity switch disconnects and outputs a floating signal. The height status signal output by the proximity switch is transmitted to the instrument module. S3. The instrument module simultaneously receives and judges the speed signal and the gantry height status signal; S4. When the operating speed is less than or equal to the first speed threshold, the instrument module does not perform speed limiting control; S5. When the operating speed is greater than the first speed threshold and the gantry height status signal is a suspended signal, the instrument module sends a speed limit message to the engine control unit. The engine control unit responds to the speed limit message and limits the maximum operating speed of the vehicle to a second speed threshold, wherein the second speed threshold is less than the first speed threshold. S6. When the vehicle is in a speed-limited state, the instrument module continuously monitors the gantry height status signal. If the gantry height status signal remains suspended, the instrument module continuously sends the speed limit message to keep the vehicle in a speed-limited state. If the gantry height status signal switches to a high-level signal, the instrument module stops sending the speed limit message, cancels the vehicle speed limit, and resets the gantry height status judgment.

2. The method for safety control of forklift operation conditions in the field according to claim 1, characterized in that, The threshold value set in step S2 is determined based on the forklift mast type: if the forklift is equipped with a fully free mast, the threshold value is the lifting height after the fully free lifting cylinder has extended its full stroke; if the forklift is equipped with a non-fully free mast, the threshold value is a predetermined value.

3. The method for safety control of forklift operation conditions in the field according to claim 1, characterized in that, In step S5, the engine control unit limits the vehicle's maximum operating speed to the second speed threshold, and at the same time limits the forklift lifting speed to a predetermined proportion of the rated maximum lifting speed under full load.

4. The method for safety control of forklift operation conditions in the field according to claim 1, characterized in that, In step S2, the proximity switch is installed on the outer mast of the forklift mast, with the sensing surface of the proximity switch facing the mast moving part below. When the mast lifting height reaches the set threshold, the mast moving part disengages from the sensing area of ​​the proximity switch, and the proximity switch is disconnected.

5. The method for safety control of forklift operation conditions in the field according to claim 1, characterized in that, The instrument module is a forklift combination instrument, which is connected to the speed sensor, the proximity switch and the engine control unit via a CAN bus.

6. The method for safety control of forklift operation conditions in the field according to claim 1, characterized in that, The safety control method also includes a power-on self-test step: after the forklift is started and powered on, the instrument module first executes a self-test program to check whether the signals of the speed sensor and the proximity switch are normal. If any sensor signal is detected to be abnormal, the instrument module issues a fault alarm signal and prohibits the vehicle from entering the normal operation mode.

7. The method for safety control of forklift operation conditions in the field according to claim 5, characterized in that, In step S5, when the instrument module sends a speed limit message to the engine control unit via the CAN bus, the speed limit message includes a speed limit command identifier and a speed limit target value. After receiving the speed limit message, the engine control unit returns an acknowledgment message to the instrument module. If the instrument module does not receive the acknowledgment message within a preset time, it repeatedly sends the speed limit message until it receives an acknowledgment message or reaches the preset maximum number of retransmissions.

8. The method for safety control of forklift operation conditions in the field according to claim 1, characterized in that, The safety control method further includes an anomaly handling step: when the instrument module detects that the proximity switch has a signal switching frequency exceeding a preset threshold during vehicle operation, it determines that the proximity switch has malfunctioned, the instrument module issues a fault alarm signal and limits the maximum operating speed of the vehicle to the second speed threshold until the fault is cleared.

9. The method for safety control of forklift operation conditions in a factory as described in any one of claims 1 to 8, characterized in that, In step S6, when the gantry height status signal switches to a high-level signal, the instrument module stops sending speed limit messages and records the occurrence time, duration, and vehicle operating parameters of this speed limit event, and provides a prompt through the display unit of the instrument module.

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