A fixed frame car-lifting machine height counter sensor fault detection method

Abstract

The application discloses a fixed car lifter height counter sensor fault detection method, and relates to the technical field of fault detection, aiming at solving the problem that the traditional car lifter cannot detect the proximity switch fault. The car lifter comprises a main proximity switch and an auxiliary proximity switch, a main counter and an auxiliary counter are arranged in a PLC and are used for recording the tooth numbers of the main proximity switch and the auxiliary proximity switch, and the detection method comprises the following steps: the PLC receives the main switch tooth number recorded by the main counter and the auxiliary switch tooth number recorded by the auxiliary counter in real time, and converts the main switch tooth number and the auxiliary switch tooth number into a main switch height value and an auxiliary switch height value; the main switch height value and the auxiliary switch height value are subjected to difference operation, the absolute value of the difference is obtained, the absolute value of the difference is compared with a pre-stored warning threshold value, and when the absolute value of the difference is higher than the warning threshold value, a warning is given. The double proximity switches and the double counters adopted in the detection method can detect the proximity switch fault, and the reliability of the system is improved.

Description

Technical Field

[0001] This invention relates to the field of fault detection technology, and in particular to a fault detection method for a fixed vehicle jack height counting sensor. Background Technology

[0002] Existing fixed car-lifting machine height counting systems typically use a combination of proximity switches and a counting gear to collect the car-lifting height data. Specifically, the counting gear is fixedly connected to a rotating lead screw, and the proximity switch is installed near the counting gear. When the car-lifting machine is raised or lowered, the counting gear rotates with the lead screw, and the proximity switch records the change in car-lifting height by detecting the number of passes of the gear teeth. Simultaneously, the PLC determines the direction of increase or decrease in the car-lifting machine height by combining the signals from the proximity switch and the status of the contactors (such as the on / off state of the raising or lowering contactors). This design offers advantages such as simple installation, low cost, and can basically meet the functional requirements of car-lifting machine height adjustment.

[0003] However, while the combination of proximity switches and counting gears demonstrates a certain level of reliability in practical applications, it also has significant limitations. Firstly, existing systems using a single proximity switch are susceptible to malfunctions. When the proximity switch fails (e.g., due to mechanical wear, environmental interference, or intermittent triggering problems), the PLC cannot detect the fault. Since the PLC control system relies solely on the signal from this single proximity switch for height counting, intermittent triggering issues prevent the PLC from determining the accuracy of the counting signal, leading to a discrepancy between the recorded height and the actual height. This discrepancy accumulates over time, eventually causing errors in the height adjustment of the vehicle jack.

[0004] More seriously, if height counting deviations are not detected and corrected in time, the vehicle jacking machine may make incorrect height adjustments to the vehicle during the lifting and lowering process. For example, if one side of the jacking machine stops rising or falling due to counting deviation, while the other side continues to operate normally, the vehicle will tilt. This tilt will not only affect the safety and stability of the vehicle, but may also cause additional stress on the mechanical structure of the jacking machine, and may even lead to equipment damage or safety accidents. Summary of the Invention

[0005] To address the aforementioned technical problems, the present invention aims to provide a method for fault detection of a fixed vehicle jack height counting sensor.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A method for fault detection of a fixed vehicle jack height counting sensor is provided, characterized by including a main proximity switch and an auxiliary proximity switch, and a PLC equipped with a main counter and an auxiliary counter for recording the number of teeth passed by the main proximity switch and the auxiliary proximity switch, respectively. The detection method includes the following steps: Working value conversion: The PLC receives the number of main switch teeth recorded by the main counter and the number of auxiliary switch teeth recorded by the auxiliary counter in real time, and converts the number of main switch teeth and the number of auxiliary switch teeth into the main switch height value and the auxiliary switch height value; Numerical processing and comparison: The height value of the main switch and the height value of the auxiliary switch are subtracted, and the absolute value of the difference is taken. The absolute value of the difference is compared with the pre-stored warning threshold. When the absolute value of the difference is higher than the warning threshold, an early warning is issued.

[0007] Compared with the prior art, the fault detection method for the fixed vehicle jack height counting sensor provided by the present invention has the following technical advantages: The detection method in this application employs a combination of two proximity switches and a main counter and an auxiliary counter. The installation position of the two proximity switches relative to the counting gear disc has no special requirements. The main counter and the auxiliary counter count the associated proximity switches respectively. The PLC converts the switch tooth counts recorded by the main counter and the auxiliary counter into switch height values. The difference between the two switch height values ​​is calculated, and the absolute value is compared with a warning threshold. When the threshold is exceeded, the PLC issues an alarm signal, prompting the operator to troubleshoot and maintain the system. The use of dual proximity switches and dual counters improves the reliability of the system. Attached Figure Description

[0008] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic flowchart of the fault detection method for the height counting sensor of the fixed vehicle jack in an embodiment of the present invention; Figure 2 This is a schematic diagram of the installation of the proximity switch in an embodiment of the present invention.

[0009] Figure label: 1-Counting gear, 2-Main proximity switch, 3-Rotating lead screw, 4-Auxiliary proximity switch, 5-Bearing housing, 6-Base, 7-Lead screw protective sleeve, 8-Switch protective sleeve. Detailed Implementation

[0010] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0011] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0012] like Figure 1 As shown in the embodiment of the present invention, the fault detection method for the fixed vehicle jack height counting sensor includes a main proximity switch and an auxiliary proximity switch. A main counter and an auxiliary counter are respectively set in the PLC to record the number of teeth passed by the main proximity switch and the auxiliary proximity switch. The detection method includes the following steps: Working value conversion: The PLC receives the number of main switch teeth recorded by the main counter and the number of auxiliary switch teeth recorded by the auxiliary counter in real time, and converts the number of main switch teeth and auxiliary switch teeth into the main switch height value and auxiliary switch height value; Numerical processing and comparison: The height values ​​of the main switch and the auxiliary switch are subtracted, and the absolute value of the difference is taken. The absolute value of the difference is compared with the pre-stored warning threshold. If the absolute value of the difference is higher than the warning threshold, an early warning is issued.

[0013] In practice: The technical solution uses a combination of a main proximity switch, an auxiliary proximity switch, a main counter, and an auxiliary counter. The counting gear is precisely installed at one end of the rotating screw. When the drive motor starts, the rotating screw begins to rotate, driving the counting gear to rotate synchronously. The main proximity switch and the auxiliary proximity switch are respectively connected to the main counter and the auxiliary counter of the PLC. The main counter and the auxiliary counter count the number of teeth on the counting gear detected by the main proximity switch and the auxiliary proximity switch when the car lifter is raised and lowered. The PLC converts the number of teeth recorded by the main counter and the auxiliary counter into the height of the car lifter.

[0014] like Figure 2 As shown, the main proximity switch 2 and the auxiliary proximity switch 4 are mounted on the base 6 through the mounting sleeve 8. The counting gear 1 is fixedly connected to the rotating screw 3. The upper and lower sides of the counting gear 1 are the bearing seat 5 and the screw sleeve 7, respectively. The rotating screw 3 drives the counting gear 1 to rotate.

[0015] During operation, each time a tooth of the counting trolley passes the main and auxiliary proximity switches, the main and auxiliary counters are triggered to start counting. These two counters transmit the captured signals to the programmable logic controller (PLC) in real time. The algorithm internal to the PLC converts the received two counting signals into the lifting heights of the main and auxiliary proximity switches, and then compares and analyzes these lifting heights. Under normal circumstances, due to the continuous rotation of the counting trolley, the counting results of the main and auxiliary counters should theoretically differ by only one data point. This minute difference is due to the slight offset in the physical position of the two proximity switches.

[0016] However, if during operation, the PLC detects that the difference in counts between the two counters exceeds a preset threshold (e.g., greater than 1mm), the system will automatically determine that one of the proximity switches may be faulty. At this time, the PLC will issue an alarm signal, prompting the operator to troubleshoot and perform maintenance. This dual-counter design not only improves the system's reliability.

[0017] In this embodiment, the rotating lead screw and the counting gear are rigidly connected to ensure that their rotation angles are strictly synchronized. The lead screw has a lead of 12mm (meaning that for every revolution of the lead screw, the car-lifting machine moves vertically by 12mm); the counting gear has 12 teeth (uniformly distributed). Signal acquisition logic: When the lead screw rotates one revolution (12mm), the counting gear rotates synchronously one revolution, triggering the proximity switch 12 times (once per tooth). Therefore, each pulse signal corresponds to a 1mm height change of the car-lifting machine, achieving a linear mapping between height and pulse.

[0018] After the initial installation, it is also necessary to set the lower limit of the car jack, the correspondence between pulse count and height, etc.

[0019] Lower limit reference setting: After the initial installation, lower the lifting column of the fixed vehicle jack to its lower limit position. The lower limit is an electrical limit device used to ensure the lifting column stops accurately at its lowest position. Use this lower limit as a reference point, setting the height at this point to 0mm. This reference value provides a clear origin for subsequent height counting, ensuring the accuracy and consistency of height data.

[0020] Correspondence between pulse count and height: Height counting is achieved by combining a proximity switch (pulse proximity switch) with a counting gear. Each time the counting gear rotates and passes the proximity switch, the proximity switch will send back a pulse signal, and the PLC can directly calculate the current height of the lifting column through pulse counting.

[0021] To ensure the long-term stability and high-precision counting of the system, an automatic synchronization mechanism is introduced for periodic calibration between the main counter and the auxiliary counter. Specifically, when the car-mounting machine reaches its lower limit, the system automatically triggers the synchronization process of the two counters. This aims to eliminate accumulated errors that may occur due to long-term operation, thereby ensuring the accuracy and consistency of the counting data.

[0022] During synchronization, the PLC receives a signal that the car-lifting machine has reached its lower limit and immediately initiates the synchronization program. At this time, the current count values ​​of the main counter and the auxiliary counter are read and compared. Since the car-lifting machine is at its lower limit, theoretically, the values ​​of the two counters should be exactly the same. If a difference is found, the PLC automatically adjusts the value of the auxiliary counter to match that of the main counter, thus achieving synchronization. This synchronization mechanism not only effectively prevents the accumulation of errors but also ensures the counting accuracy of the system in each working cycle.

[0023] Furthermore, this automatic synchronization mechanism offers significant alarm optimization. Because synchronization occurs automatically at the end of each cycle, any counting deviations caused by proximity switch malfunctions or external interference are detected and corrected within a single cycle. This means that alarm signal triggering is concentrated within a single cycle, avoiding complex troubleshooting caused by error propagation across cycles. This design not only improves system reliability but also simplifies maintenance procedures and reduces downtime caused by false alarms or missed alarms.

[0024] Lower limit setting: When the lifting column of the vehicle jacking machine descends to the lower limit, the PLC sets the height at this point to 0mm. It's important to note that the PLC will not automatically reset the main counter value to zero unless manually reset by the operator. This design prevents the loss of the reference point due to misoperation or system malfunction.

[0025] Height change process: During the ascent of the car lifter, the value of the main counter gradually increases from 0 until it reaches the target height (e.g., 1000mm). During the descent, the value of the main counter gradually decreases from the target height, and the height of the car lifter gradually decreases until it returns to the lower limit of 0mm. This continuous and linear height change process provides the PLC with a clear basis for status judgment.

[0026] The value recorded by the main counter here is the number of teeth passed by the main proximity switch, which is also the height value of the lifting mechanism. Since the height corresponding to one tooth in this embodiment is 1mm, the number of teeth read can be directly used as the lifting height value without conversion. The main counter and auxiliary counter used are not physical devices, but two independent stored variables inside the PLC (Programmable Logic Controller). The output signal of the proximity switch is directly connected to the input module of the PLC. The PLC performs real-time addition and subtraction operations on the values ​​of these two counters according to the trigger signal of the proximity switch, and realizes height counting and fault detection through logical comparison.

[0027] Proximity switch signal input: The counting gear rotates with the lead screw. Each time a tooth on the gear passes a proximity switch, the proximity switch outputs a pulse signal (high or low level). This signal is acquired by the PLC's input module (such as the DI module) and used as the basis for counting.

[0028] PLC internal counting logic: Master counter (e.g., VW100): The PLC is triggered by the rising (or falling) edge of the proximity switch to perform an increment or decrement operation (depending on the lifting direction of the car jack).

[0029] Auxiliary counters (such as VW200): use the same counting logic, but are stored in different PLC registers to form a redundant backup.

[0030] The trigger stroke of the lower limit is relatively short, typically 2-3 mm. This design ensures that the jacking machine can quickly and accurately trigger the signal when approaching the lower limit.

[0031] Master counter fault detection: If the master counter malfunctions (such as due to damage to the master proximity switch, signal loss, or counting errors), the PLC will detect and trigger an alarm through the following mechanisms: Detection after leaving the lower limit: When the car lifter starts to rise from the lower limit, the PLC will monitor the value change of the main counter in real time. If the main counter fails to count normally after leaving the lower limit (e.g., the value does not increase or increases abnormally), the PLC will immediately determine that the main counter may be faulty.

[0032] Alarm triggering conditions: In the event of a main counter failure, the car lifter only needs to rise 2mm (i.e., move out of the short stroke range of the lower limit) for the PLC to detect the counting abnormality and trigger an alarm. At this time, the car lifter has not yet made contact with the vehicle, so it will not cause any impact on the vehicle or equipment.

[0033] Safety protection mechanism: Once an alarm is triggered, the PLC will immediately stop the lifting machine's ascending operation and lock the ascending function, allowing only descending operation. This design ensures that the lifting machine will not continue to operate in the event of a fault, thereby avoiding potential safety risks.

[0034] The detection method in this application employs a combination of two proximity switches and a main counter and an auxiliary counter. The installation position of the two proximity switches relative to the counting gear disc has no special requirements. The main counter and the auxiliary counter count the associated proximity switches respectively. The PLC converts the switch tooth counts recorded by the main counter and the auxiliary counter into switch height values. The difference between the two switch height values ​​is calculated, and the absolute value is compared with a warning threshold. When the threshold is exceeded, the PLC issues an alarm signal, prompting the operator to troubleshoot and maintain the system. The use of dual proximity switches and dual counters improves the reliability of the system.

[0035] As one possible implementation, the following steps are included before the working value conversion: Mark the lower limit: Set the lowest position of the fixed car frame machine as the lower limit, and set the initial main switch height value and initial auxiliary switch height value of the tooth count conversion recorded by the main counter and auxiliary counter to 0; Calculate the height value corresponding to each tooth of the counting gear based on the lead screw and the number of teeth of the counting gear.

[0036] By calculating the height value corresponding to each tooth of the counting tooth disk, the lifting height of the fixed frame machine can be determined based on the number of teeth read from the counting tooth disk.

[0037] As one possible implementation method, the warning threshold is 1 mm.

[0038] Setting the warning threshold to 1mm ensures the safety of multiple lifting columns of the fixed frame car machine during lifting, and avoids damage to the train caused by inappropriate threshold setting and asynchronous lifting columns.

[0039] As one possible implementation, the main proximity switch and the auxiliary proximity switch are mounted on the central axis of the vertically rotating lead screw.

[0040] The main proximity switch and the auxiliary proximity switch are mounted vertically along the central axis of the rotating screw. This allows for better acquisition of the number of teeth passing through the main proximity switch and the auxiliary proximity switch when the counting gear rotates. There are no requirements for the installation angle between the main proximity switch and the auxiliary proximity switch.

[0041] As one possible implementation method, the detection method further includes the following steps: Periodic counting synchronization: When the car-mounting machine moves to the lower limit, the PLC obtains the number of teeth of the main switch and the number of teeth of the auxiliary switch recorded by the main counter and the auxiliary counter respectively. When the number of teeth of the auxiliary switch is different from the number of teeth of the main switch, the number of teeth of the auxiliary switch is synchronized with the number of teeth of the main switch.

[0042] By synchronizing the main counter and the auxiliary counter at the lower limit of the same cycle, the accumulation of errors is effectively prevented, and the counting accuracy of the system in each working cycle is also ensured.

[0043] As one possible implementation method, the detection method further includes the following steps: Record the signal trigger distance of the lower limit. When the fixed frame vehicle rises from the lower limit to the distance from the signal trigger distance, convert the number of teeth of the main switch into the height value of the main switch. Compare the height value of the main switch with the signal trigger distance. If the height value of the main switch and the signal trigger distance are different, issue an early warning of a main proximity switch failure.

[0044] By comparing the signal trigger distance when the car lifter rises to the point of disengagement from the lower limit signal with the height of the main proximity switch after tooth count conversion recorded by the main counter, an early warning can be given before the car lifter contacts the vehicle, without causing any impact on the vehicle or equipment.

[0045] In the description of the above embodiments, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0046] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for fault detection of a fixed vehicle jack height counting sensor, characterized in that, The system includes a main proximity switch and an auxiliary proximity switch. The PLC is equipped with a main counter and an auxiliary counter, respectively, for recording the number of teeth passed by the main and auxiliary proximity switches. The detection method includes the following steps: Working value conversion: The PLC receives the number of main switch teeth recorded by the main counter and the number of auxiliary switch teeth recorded by the auxiliary counter in real time, and converts the number of main switch teeth and the number of auxiliary switch teeth into the main switch height value and the auxiliary switch height value; Numerical processing and comparison: The height value of the main switch and the height value of the auxiliary switch are subtracted, and the absolute value of the difference is taken. The absolute value of the difference is compared with the pre-stored warning threshold. When the absolute value of the difference is higher than the warning threshold, an early warning is issued.

2. The method for fault detection of the fixed vehicle jack height counting sensor according to claim 1, characterized in that, Before converting working values, the following steps are also included: Mark the lower limit: Set the lowest position of the fixed car frame machine as the lower limit, and set the initial main switch height value and initial auxiliary switch height value of the tooth count conversion recorded by the main counter and auxiliary counter to 0; Calculate the height value corresponding to each tooth of the counting gear based on the lead screw and the number of teeth of the counting gear.

3. The method for fault detection of the fixed vehicle jack height counting sensor according to claim 1, characterized in that, The warning threshold is 1 mm.

4. The method for fault detection of the fixed vehicle jack height counting sensor according to claim 1, characterized in that, The main proximity switch and the auxiliary proximity switch are mounted on the central axis of the vertical rotating screw.

5. The method for fault detection of the fixed vehicle jack height counting sensor according to claim 1, characterized in that, The detection method further includes the following steps: Periodic counting synchronization: When the car-mounting machine moves to the lower limit, the PLC obtains the number of main switch teeth and the number of auxiliary switch teeth recorded by the main counter and the auxiliary counter, respectively. When the number of auxiliary switch teeth is different from the number of main switch teeth, the number of auxiliary switch teeth is synchronized with the number of main switch teeth.

6. The method for fault detection of the fixed vehicle jack height counting sensor according to claim 1, characterized in that, The detection method further includes the following steps: Record the signal trigger distance of the lower limit. When the fixed frame vehicle rises from the lower limit to the distance away from the signal trigger distance, convert the number of teeth of the main switch into the height value of the main switch. Compare the height value of the main switch with the signal trigger distance. If the height value of the main switch and the signal trigger distance are different, issue an early warning of a main proximity switch failure.

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