A hoist crane trolley travel limiting system and method

Abstract

The present invention discloses a travel limiting system and method for a hoist crane trolley. A first reflector and a second reflector are respectively provided at both ends of a hoist crane beam. A first distance between the hoist crane trolley and the first reflector is monitored in real time by a first infrared ranging device, and a second distance between the hoist crane trolley and the second reflector is monitored in real time by a second infrared ranging device. When the first distance or the second distance is smaller than a threshold value, the hoist crane trolley can be controlled to stop moving, thereby avoiding a rigid collision between the hoist crane trolley and the two ends of the hoist crane trolley, and preventing the body of the hoist crane trolley from being damaged and derailed.

Description

Technical Field

[0001] The present invention belongs to the field of hoist crane trolleys, and in particular relates to a travel limiting system and method for a hoist crane trolley. Background Art

[0002] Single-girder hoist trolleys are commonly used in factories. They are equipped with anti-collision rubber blocks at both ends of the hoist beam to stop the trolley by mechanical collision when it reaches the end of the beam. However, mechanical collisions can easily damage the rubber blocks, causing them to fall off. This can cause the trolley to collide with the end of the beam during horizontal travel, resulting in damage to the trolley and derailment. Summary of the Invention

[0003] In view of the above-mentioned deficiencies in the prior art, the present invention provides a hoist crane trolley travel limiting system and method to solve the problems in the prior art.

[0004] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is: a hoist crane trolley travel limiting system, including a hoist crane trolley, a hoist crane beam, a first infrared ranging device, a second infrared ranging device, a first reflector, a second reflector, a first limiting device and a second limiting device;

[0005] The hoist crane trolley is arranged on the hoist crane beam, and the first limit device and the second limit device are respectively arranged at both ends of the hoist crane beam; the first reflector is arranged on the hoist crane beam and is located between the first limit device and the hoist crane beam; the second reflector is arranged on the hoist crane beam and is located between the second limit device and the hoist crane beam; the first infrared ranging device and the second infrared ranging device are both arranged on the hoist crane trolley, the measuring direction of the first infrared ranging device is facing the first reflector, and the measuring direction of the second infrared ranging device is facing the second reflector.

[0006] Furthermore, the first reflective plate is connected to a first limiting device, and the second reflective plate is connected to a second limiting device.

[0007] Furthermore, the first infrared ranging device and the second infrared ranging device have the same structure, both including a control module, an infrared sensor module and an analog-to-digital conversion module; the infrared sensor module is electrically connected to the analog-to-digital conversion module, and the analog-to-digital conversion module is electrically connected to the control module.

[0008] Furthermore, the control module includes a processor U1 of model AT89C51.

[0009] Furthermore, the analog-to-digital conversion module includes a digital-to-analog conversion chip U3 of model ADC0804, wherein the DB0 pin of the digital-to-analog conversion chip U3 is connected to the P1.0 pin of the processor U1, the DB1 pin of the digital-to-analog conversion chip U3 is connected to the P1.1 pin of the processor U1, the DB2 pin of the digital-to-analog conversion chip U3 is connected to the P1.2 pin of the processor U1, the DB3 pin of the digital-to-analog conversion chip U3 is connected to the P1.3 pin of the processor U1, the DB4 pin of the digital-to-analog conversion chip U3 is connected to the P1.4 pin of the processor U1, the DB5 pin of the digital-to-analog conversion chip U3 is connected to the P1.5 pin of the processor U1, the DB6 pin of the digital-to-analog conversion chip U3 is connected to the P1.6 pin of the processor U1, the DB7 pin of the digital-to-analog conversion chip U3 is connected to the P1.7 pin of the processor U1, and the The pin is connected to the P3.7 pin of the processor U1, and the digital-to-analog conversion chip U3 The pin is connected to the P3.6 pin of processor U1.

[0010] Furthermore, the infrared sensing module includes an infrared sensor U2 of model GP2D12, and a VO pin of the infrared sensor U2 is connected to a VIN+ pin of a digital-to-analog conversion chip U3.

[0011] Furthermore, the first infrared distance measuring device and the second infrared distance measuring device are both electrically connected to the controller of the hoist trolley.

[0012] Furthermore, the P0.1 pin of the processor U1 in the first infrared ranging device is electrically connected to the controller of the hoist trolley; the P0.1 pin of the processor U1 in the second infrared ranging device is electrically connected to the controller of the hoist trolley.

[0013] A method for using a hoist trolley travel limiting system, comprising:

[0014] The first distance between the hoist trolley and the first reflector is monitored in real time by a first infrared distance measuring device, and the second distance between the hoist trolley and the second reflector is monitored in real time by a second infrared distance measuring device;

[0015] transmitting the first spacing and the second spacing to a controller of the hoist trolley;

[0016] The travel of the hoist trolley is limited according to the first spacing and the second spacing.

[0017] Furthermore, the hoist trolley is limited in travel according to the first spacing and the second spacing, including:

[0018] Determine whether the first distance is within a first threshold range. If so, control the hoist trolley to stop moving. Otherwise, determine the second distance.

[0019] It is determined whether the second distance is within a second threshold range. If so, the hoist trolley is controlled to stop moving, otherwise no operation is performed.

[0020] The beneficial effects of the present invention are:

[0021] (1) The present invention provides a travel limiting system and method for a hoist crane trolley, wherein a first reflector and a second reflector are respectively provided at both ends of the hoist crane beam, and a first infrared ranging device is used to monitor in real time the first distance between the hoist crane trolley and the first reflector, and a second infrared ranging device is used to monitor in real time the second distance between the hoist crane trolley and the second reflector. When the first distance or the second distance is less than a threshold value, the hoist crane trolley can be controlled to stop moving, thereby avoiding a rigid collision between the hoist crane trolley and the two ends of the hoist crane trolley, so that the body of the hoist crane trolley will not be damaged and will not derail and fall.

[0022] (2) The present invention further provides a first limiting device outside the first reflector, and a second limiting device outside the second reflector, thereby forming a double protection mechanism and further ensuring the safety of the hoist trolley.

[0023] (3) The present invention uses the infrared sensor U2 of model GP2D12 as the sensor of the first infrared distance measuring device and the second infrared distance measuring device, which can accurately measure the distance between the hoist trolley and the first reflector and the second reflector. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a structural diagram of a hoist crane trolley travel limiting system provided in an embodiment of the present invention.

[0025] Figure 2 A circuit diagram of a control module provided in an embodiment of the present invention.

[0026] Figure 3 A circuit diagram of an analog-to-digital conversion module provided in an embodiment of the present invention.

[0027] Figure 4 This is a circuit diagram of an infrared sensor module provided by an embodiment of the present invention.

[0028] Figure 5 A circuit diagram of a power supply circuit provided in an embodiment of the present invention.

[0029] Figure 6 The present invention provides a flowchart of a method for limiting the movement of a hoist trolley.

[0030] Among them: 1-hoist crane trolley, 2-hoist crane beam, 3-first infrared ranging device, 4-second infrared ranging device, 5-first reflector, 6-second reflector, 7-first limit device, 8-second limit device.

[0031] The above drawings illustrate specific embodiments of the present application, which will be described in more detail below. These drawings and the textual description are not intended to limit the scope of the present application in any way, but rather to illustrate the concepts of the present application to those skilled in the art by reference to specific embodiments. DETAILED DESCRIPTION

[0032] The specific embodiments of the present invention are described below to facilitate understanding of the present invention by those skilled in the art. However, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the appended claims, these changes are obvious, and all inventions and creations utilizing the concepts of the present invention are protected.

[0033] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0034] like Figure 1 As shown, a hoist crane trolley travel limiting system includes a hoist crane trolley 1, a hoist crane beam 2, a first infrared ranging device 3, a second infrared ranging device 4, a first reflector 5, a second reflector 6, a first limiting device 7 and a second limiting device 8.

[0035] The hoist crane trolley 1 is arranged on the hoist crane beam 2, and the first limit device 7 and the second limit device 8 are respectively arranged at both ends of the hoist crane beam 2; the first reflector 5 is arranged on the hoist crane beam 2, and is located between the first limit device 7 and the hoist crane beam 2; the second reflector 6 is arranged on the hoist crane beam 2, and is located between the second limit device 8 and the hoist crane beam 2; the first infrared ranging device 3 and the second infrared ranging device 4 are both arranged on the hoist crane trolley 1, and the measuring direction of the first infrared ranging device 3 is facing the first reflector 5, and the measuring direction of the second infrared ranging device 4 is facing the second reflector 6.

[0036] In this embodiment, the first limiting device 7 can be set as an anti-collision rubber block, and the second limiting device 8 can be set as an anti-collision rubber block. The first infrared ranging device 3, the second infrared ranging device 4, the first reflector 5 and the second reflector 6 form a first anti-collision structure. The first infrared ranging device 3 measures the first distance between the hoist trolley 1 and the first reflector 5, and the second infrared ranging device 4 measures the second distance between the hoist trolley 1 and the second reflector 6. When the first distance and the second distance are less than the set threshold, the hoist trolley 1 can be controlled to stop moving, thereby protecting the hoist trolley 1 from collision and falling. The first limiting device 7 and the second limiting device 8 form a second anti-collision structure. If the first anti-collision structure fails, the second anti-collision structure can protect the hoist trolley 1 from damage.

[0037] By constructing the first anti-collision structure and the second anti-collision structure, a double protection mechanism is formed, which further ensures the safety of the hoist crane trolley.

[0038] Optionally, the purpose of providing the first reflector 5 and the second reflector 6 in this embodiment is to automatically stop the hoist trolley 1 when it is a certain distance away from the first limit device 7 or the second limit device 8. Therefore, the first reflector 5 and the second reflector 6 can be removed, and the side of the first limit device 7 facing the first infrared distance measuring device 3 can be provided as a reflector, so that the first infrared distance measuring device 3 can measure the first distance between the hoist trolley 1 and the first limit device 7; and the side of the second limit device 8 facing the second infrared distance measuring device 4 can be provided as a reflector, so that the second infrared distance measuring device 4 can measure the second distance between the hoist trolley 1 and the second limit device 8.

[0039] Optionally, the first infrared ranging device 3 and the second infrared ranging device 4 are replaced by ultrasonic ranging devices or other ranging devices, which can also achieve the measurement of the distance between the hoist trolley 1 and the first reflector 5 and the second reflector 6 respectively.

[0040] In a possible implementation, the first reflector 5 is connected to the first limiting device 7 , and the second reflector 6 is connected to the second limiting device 8 .

[0041] Connecting the first reflector 5 to the first limiting device 7 is equivalent to the first infrared distance measuring device 3 measuring the first distance between the hoist trolley 1 and the first limiting device 7. Connecting the second reflector 6 to the second limiting device 8 is equivalent to the second infrared distance measuring device 4 measuring the second distance between the hoist trolley 1 and the second limiting device 8.

[0042] In one possible embodiment, the first infrared ranging device 3 and the second infrared ranging device 4 have the same structure, both including a control module, an infrared sensor module and an analog-to-digital conversion module; the infrared sensor module is electrically connected to the analog-to-digital conversion module, and the analog-to-digital conversion module is electrically connected to the control module.

[0043] like Figure 2 As shown, the control module includes a processor U1 whose model is AT89C51.

[0044] AT89C51 is a low-power, high-performance single-chip microcomputer. Using AT89C51 as the processor of the first infrared ranging device 3 and the second infrared ranging device 4 can realize the control function while running at low power consumption for a long time, saving electricity.

[0045] In this embodiment, the RST pin of the processor U1 is also connected to one end of the resistor R1 and the negative electrode of the polarity capacitor C1 respectively, the positive electrode of the polarity capacitor C1 is connected to the +5V voltage, the other end of the resistor R1 is grounded, the XTAL1 pin of the processor U1 is connected to one end of the crystal oscillator Y1 and one end of the capacitor C3 respectively, the other end of the capacitor C3 is grounded, the XTAL2 pin of the processor U1 is connected to the other end of the crystal oscillator Y1 and one end of the capacitor C2 respectively, the other end of the capacitor C2 is grounded, the GND pin of the processor U1 is grounded, the VCC pin of the processor U1 is connected to the +5V voltage, and the EA pin of the processor U1 is connected to the +5V voltage.

[0046] like Figure 3 As shown, the analog-to-digital conversion module includes a digital-to-analog conversion chip U3 of model ADC0804, the DB0 pin of the digital-to-analog conversion chip U3 is connected to the P1.0 pin of the processor U1, the DB1 pin of the digital-to-analog conversion chip U3 is connected to the P1.1 pin of the processor U1, the DB2 pin of the digital-to-analog conversion chip U3 is connected to the P1.2 pin of the processor U1, the DB3 pin of the digital-to-analog conversion chip U3 is connected to the P1.3 pin of the processor U1, the DB4 pin of the digital-to-analog conversion chip U3 is connected to the P1.4 pin of the processor U1, the DB5 pin of the digital-to-analog conversion chip U3 is connected to the P1.5 pin of the processor U1, the DB6 pin of the digital-to-analog conversion chip U3 is connected to the P1.6 pin of the processor U1, the DB7 pin of the digital-to-analog conversion chip U3 is connected to the P1.7 pin of the processor U1, and the The pin is connected to the P3.7 pin of the processor U1, and the digital-to-analog converter chip U3 The pin is connected to the P3.6 pin of processor U1.

[0047] In this embodiment, the digital-to-analog conversion chip U3 Pin and its Pins are connected, the CLK IN pin of the digital-to-analog conversion chip U3 is connected to one end of the capacitor C4 and one end of the resistor R4, the CLK R pin of the digital-to-analog conversion chip U3 is connected to the other end of the resistor R4, the other end of the capacitor C4 is grounded, the VREF / 2 pin of the digital-to-analog conversion chip U3 is respectively connected to one end of the resistor R2 and one end of the resistor R3, the other end of the resistor R3 is grounded, the other end of the resistor R2 is connected to the +5V voltage, the A GND pin, D GND pin, VIN+ pin and CIN- pin of the digital-to-analog conversion chip U3 are all grounded, and the VCC pin of the digital-to-analog conversion chip U3 is connected to the +5V voltage.

[0048] Optionally, the specific circuit of the analog-to-digital conversion module can be replaced with other analog-to-digital converters or analog-to-digital conversion circuits. The sensing data of the infrared sensor module is converted by the analog-to-digital conversion module to obtain digital sensing data, which is then transmitted to the control module for identification and processing, thereby completing real-time ranging.

[0049] like Figure 4 As shown, the infrared sensor module includes an infrared sensor U2 of model GP2D12, and the VO pin of the infrared sensor U2 is connected to the VIN+ pin of the digital-to-analog conversion chip U3.

[0050] In this embodiment, the VCC pin of the infrared sensor U2 is connected to the +5V voltage, and the GND pin of the infrared sensor U2 is grounded.

[0051] The GP2D12 is an infrared distance sensor widely used in various fields. Its measurement range is 10 cm to 80 cm. It offers high accuracy, minimal fluctuation, and stable data transmission. Using the GP2D12 as the sensor for the first infrared distance measuring device 3 and the second infrared distance measuring device 4 can accurately measure the first distance between the hoist trolley 1 and the first reflector 5, as well as the second distance between the hoist trolley 1 and the second reflector 6.

[0052] In this embodiment, a power supply circuit for a first infrared distance measuring device 3 and a second infrared distance measuring device 4 is provided. Figure 5 As shown, the power supply circuit includes a polarized capacitor C5, a voltage stabilizing chip U4, an inductor L1, a polarized capacitor C6, a diode D1, a light emitting diode D2 and a resistor R5.

[0053] The model of the voltage regulator chip U4 is LM2576S-5. The VIN pin of the voltage regulator chip U4 is connected to the +24V voltage and the positive electrode of the polarity capacitor C5 respectively. The negative electrode of the polarity capacitor C5 is grounded. The pin is grounded, the DGND pin of the voltage regulator chip U4 is grounded, the Feedback pin of the voltage regulator chip U4 is the +5V voltage output end, the Feedback of the voltage regulator chip U4 is respectively connected to one end of the inductor L1, the positive electrode of the polarity capacitor C6 and one end of the resistor R5, the OUT pin of the voltage regulator chip U4 is connected to the other end of the inductor L1 and the negative electrode of the diode D1, the negative electrode of the polarity capacitor C6 is grounded, the positive electrode of the diode D1 is grounded, the other end of the resistor R5 is connected to the positive electrode of the light-emitting diode D2, the negative electrode of the light-emitting diode D2 is grounded, and the model used by the diode D1 is IN5822.

[0054] In a possible implementation, both the first infrared distance measuring device 3 and the second infrared distance measuring device 4 are electrically connected to the controller of the hoist trolley 1 .

[0055] In one possible embodiment, the P0.1 pin of the processor U1 in the first infrared ranging device 3 is electrically connected to the controller of the hoist trolley 1; the P0.1 pin of the processor U1 in the second infrared ranging device 4 is electrically connected to the controller of the hoist trolley 1.

[0056] like Figure 6 As shown, a method for limiting the movement of a hoist trolley includes:

[0057] The first distance between the hoist trolley 1 and the first reflector 5 is monitored in real time by the first infrared distance measuring device 3 , and the second distance between the hoist trolley 1 and the second reflector 6 is monitored in real time by the second infrared distance measuring device 4 .

[0058] The first spacing and the second spacing are transmitted to the controller of the hoist trolley 1.

[0059] The hoist trolley 1 is limited in travel according to the first spacing and the second spacing.

[0060] In this embodiment, when the distance is measured by the first infrared ranging device 3 and the second infrared ranging device 4, the working principles of the circuits in the first infrared ranging device 3 and the second infrared ranging device 4 are: measuring the distance by the infrared sensor U2 to obtain infrared sensing data; performing analog-to-digital conversion on the infrared sensing data through the digital-to-analog conversion chip U3 to obtain conversion data; transmitting the converted data to the processor U1, and transmitting it to the controller of the hoist trolley 1 through the processor U1.

[0061] In a possible implementation, limiting the travel of the hoist trolley 1 according to the first spacing and the second spacing includes:

[0062] Determine whether the first distance is within the first threshold range. If so, control the hoist trolley 1 to stop moving. Otherwise, determine the second distance.

[0063] It is determined whether the second distance is within the second threshold range. If so, the hoist trolley 1 is controlled to stop moving, otherwise no operation is performed.

[0064] In this embodiment, the first threshold range and the second threshold range are both pre-set in the controller of the hoist trolley 1 .

[0065] Optionally, the first distance can be judged in the processor U1 of the first infrared ranging device 3. If the first distance exceeds the first threshold range, a stop signal is sent to the controller of the hoist trolley 1, the stop signal is received by the controller of the hoist trolley 1, and the hoist trolley 1 is controlled to stop running. The second distance can be judged in the processor U1 of the second infrared ranging device 4. If the second distance exceeds the second threshold range, a stop signal is sent to the controller of the hoist trolley 1, the stop signal is received by the controller of the hoist trolley 1, and the hoist trolley 1 is controlled to stop running. Before the first infrared ranging device 3 and the second infrared ranging device 4 respectively judge the first distance and the second distance, the first threshold range and the second threshold range are pre-set in the first infrared ranging device 3 and the second infrared ranging device 4, respectively.

[0066] The present invention provides a travel limiting system and method for a hoist crane trolley. A first reflector and a second reflector are respectively provided at both ends of the hoist crane beam. A first infrared ranging device monitors a first distance between the hoist crane trolley and the first reflector in real time, and a second infrared ranging device monitors a second distance between the hoist crane trolley and the second reflector in real time. When the first distance or the second distance is less than a threshold value, the hoist crane trolley can be controlled to stop moving, thereby preventing the hoist crane trolley from rigidly colliding with the two ends of the hoist crane trolley and preventing the hoist crane trolley from being damaged or derailing. The present invention further provides a first limiting device in addition to the first reflector and a second limiting device in addition to the second reflector, thereby forming a dual protection mechanism and further ensuring the safety of the hoist crane trolley.

[0067] The present invention uses an infrared sensor U2 with a model number of GP2D12 as a sensor of the first infrared ranging device and the second infrared ranging device, which can accurately measure the distance between the hoist trolley and the first reflector and the second reflector.

[0068] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present application that follow the general principles of the present application and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered as exemplary only, and the true scope and spirit of the present application are indicated by the following claims.

[0069] It should be understood that the present application is not limited to the exact structure described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A hoist trolley travel limiting system, characterized in that: It comprises a hoist crane trolley (1), a hoist crane beam (2), a first infrared distance measuring device (3), a second infrared distance measuring device (4), a first reflector (5), a second reflector (6), a first limit device (7) and a second limit device (8); The hoist crane trolley (1) is arranged on the hoist crane beam (2), and the first limiting device (7) and the second limiting device (8) are respectively arranged at both ends of the hoist crane beam (2); the first reflector (5) is arranged on the hoist crane beam (2) and is located between the first limiting device (7) and the hoist crane beam (2); the second reflector (6) is arranged on the hoist crane beam (2) and is located between the second limiting device (8) and the hoist crane beam (2); the first infrared distance measuring device (3) and the second infrared distance measuring device (4) are both arranged on the hoist crane trolley (1), the measuring direction of the first infrared distance measuring device (3) is facing the first reflector (5), and the measuring direction of the second infrared distance measuring device (4) is facing the second reflector (6); The first reflective plate (5) is connected to the first limiting device (7), and the second reflective plate (6) is connected to the second limiting device (8); The first infrared distance measuring device (3) and the second infrared distance measuring device (4) have the same structure, both comprising a control module, an infrared sensor module and an analog-to-digital conversion module; the infrared sensor module is electrically connected to the analog-to-digital conversion module, and the analog-to-digital conversion module is electrically connected to the control module; The control module includes a processor U1 of model AT89C51; The analog-to-digital conversion module includes a digital-to-analog conversion chip U3 of model ADC0804, wherein the DB0 pin of the digital-to-analog conversion chip U3 is connected to the P1.0 pin of the processor U1, the DB1 pin of the digital-to-analog conversion chip U3 is connected to the P1.1 pin of the processor U1, the DB2 pin of the digital-to-analog conversion chip U3 is connected to the P1.2 pin of the processor U1, the DB3 pin of the digital-to-analog conversion chip U3 is connected to the P1.3 pin of the processor U1, the DB4 pin of the digital-to-analog conversion chip U3 is connected to the P1.4 pin of the processor U1, the DB5 pin of the digital-to-analog conversion chip U3 is connected to the P1.5 pin of the processor U1, the DB6 pin of the digital-to-analog conversion chip U3 is connected to the P1.6 pin of the processor U1, the DB7 pin of the digital-to-analog conversion chip U3 is connected to the P1.7 pin of the processor U1, and the The pin is connected to the P3.7 pin of the processor U1, and the digital-to-analog conversion chip U3 The pin is connected to the P3.6 pin of processor U1; The infrared sensor module includes an infrared sensor U2 of model GP2D12, and the VO pin of the infrared sensor U2 is connected to the VIN+ pin of the digital-to-analog conversion chip U3; The first infrared distance measuring device (3) and the second infrared distance measuring device (4) are both electrically connected to the controller of the hoist trolley (1); The P0.1 pin of the processor U1 in the first infrared distance measuring device (3) is electrically connected to the controller of the hoist trolley (1); the P0.1 pin of the processor U1 in the second infrared distance measuring device (4) is electrically connected to the controller of the hoist trolley (1); The method of the hoist crane trolley travel limiting system comprises the following steps: A first distance between the hoist trolley (1) and the first reflective plate (5) is monitored in real time by a first infrared distance measuring device (3), and a second distance between the hoist trolley (1) and the second reflective plate (6) is monitored in real time by a second infrared distance measuring device (4); Transmitting the first spacing and the second spacing to a controller of the hoist trolley (1); According to the first spacing and the second spacing, the hoist trolley (1) is limited in travel; The method of limiting the movement of the hoist trolley (1) according to the first spacing and the second spacing includes: Determine whether the first distance is within a first threshold range, if so, control the hoist trolley (1) to stop moving, otherwise determine the second distance; Determine whether the second distance is within a second threshold range, if so, control the hoist trolley (1) to stop moving, otherwise, do not operate; When the first reflective plate (5) is connected to the first limiting device (7), the first infrared distance measuring device (3) measures the first distance between the hoist trolley (1) and the first limiting device, and / or when the second reflective plate (6) is connected to the second limiting device (8), the second infrared distance measuring device (4) measures the second distance between the hoist trolley (1) and the second limiting device (8).

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