A tower crane variable frequency motor encoder anti-electromagnetic interference signal extraction device

Abstract

A tower crane variable frequency motor encoder anti-electromagnetic interference signal lead-out device comprises an encoder installed at the tail of the variable frequency motor, the encoder is connected to the encoder side aviation male plug through a double-layer shielded lead-out line; the encoder side aviation male plug is plug-connected with the inverter side aviation female plug, and the inverter side aviation female plug is connected to the inverter through a double-layer shielded extension line; the encoder side aviation male plug is fixed to the outer surface of the cover shell at the tail of the variable frequency motor through a mounting bracket; after the encoder side aviation male plug is docked with the inverter side aviation female plug, the shielding layer of the double-layer shielded lead-out line, the male plug shell, the female plug shell, and the shielding layer of the double-layer shielded extension line form a closed conductor container, and the conductor container is grounded in turn through the mounting bracket and the shell of the variable frequency motor. The invention has a simple structure and is easy to install, improves the anti-interference ability and signal stability of the variable frequency motor encoder signal, and ensures the stable operation of the three major mechanisms of the inverter and the tower crane.

Description

Technical Field

[0001] The invention relates to the technical field of electromagnetic interference prevention, and in particular to an electromagnetic interference prevention signal extraction device for a tower crane variable frequency motor encoder. Background Art

[0002] The encoders installed on the variable frequency motors of the three major mechanisms of the tower crane, namely the hoisting mechanism, the slewing mechanism, and the luffing mechanism, feed back the motor speed signal to the inverter. The inverter uses the speed signal fed back by the encoder to achieve closed-loop precise control of the motor speed. The existing encoder signal extraction method is to connect the encoder signal line to the motor junction box, and then connect the signal cable in the junction box to lead the encoder signal to the inverter. The disadvantage is that the internal space of the motor junction box is connected to the internal space of the motor housing, resulting in the motor junction box terminals being exposed to the complex and strong electromagnetic field inside the motor, causing the encoder signal to be frequently interfered by the electromagnetic field. The inverter receives the wrong speed signal and falsely reports the encoder fault, causing the inverter to frequently fail and shut down. Summary of the invention

[0003] In order to overcome the above problems, the present invention provides an electromagnetic interference protection signal extraction device for a tower crane variable frequency motor encoder which has a simple structure and is easy to install.

[0004] The technical solution adopted by the present invention is: a tower crane variable frequency motor encoder anti-electromagnetic interference signal lead-out device, comprising an encoder installed at the tail of the variable frequency motor, the encoder is connected to the encoder side aviation male plug through a double-layer shielded lead-out line; the encoder side aviation male plug is plug-connected with the inverter side aviation female plug, the inverter side aviation female plug is connected to the inverter through a double-layer shielded extension line; the encoder side aviation male plug is fixed to the outer surface of the cover shell at the tail of the variable frequency motor through a mounting bracket;

[0005] The double-layer shielded lead wire is composed of a wire and a shielding layer wrapped around the outside of the wire; the encoder side aviation male plug includes a male plug shell, a pin arranged in the male plug shell, and a first cable waterproof connector arranged at the rear end of the male plug shell, the male plug shell is made of metal material, the shielding layer of the double-layer shielded lead wire is electrically short-circuited with the male plug shell, and the wire of the double-layer shielded lead wire is introduced into the pin in the encoder side aviation male plug through the first cable waterproof connector;

[0006] The double-layer shielded extension line is composed of a conductor and a shielding layer wrapped around the outside of the conductor; the inverter-side aircraft mother plug includes a female plug shell, a plug core arranged in the female plug shell, and a second cable waterproof connector arranged at the rear end of the female plug shell, the female plug shell is made of metal material, the shielding layer of the double-layer shielded extension line is electrically short-circuited with the female plug shell, and the conductor of the double-layer shielded extension line is introduced into the plug core of the inverter-side aircraft mother plug through the second cable waterproof connector;

[0007] The mounting bracket is arranged on the outer surface of the cover at the tail of the variable frequency motor. The mounting bracket is a rectangular plate-shaped structure. A through hole adapted to the aviation male plug on the encoder side is opened in the center of the mounting bracket. First screw holes are respectively arranged at the four corners of the mounting bracket; a detachable clamp is sleeved on the outer surface of the aviation male plug on the encoder side. The clamp includes a hoop sheet. Second screw holes are respectively arranged at the four corners of the hoop sheet corresponding to the first screw holes. Bolts are passed through the first screw hole and the second screw hole. The clamp is fixedly connected to the mounting bracket by bolts;

[0008] After the aviation male plug on the encoder side is connected to the aviation female plug on the inverter side, the shielding layer of the double-layer shielded lead-out wire, the male plug shell, the female plug shell, and the shielding layer of the double-layer shielded extension wire form a closed conductor container, which is grounded in turn through the mounting bracket and the shell of the inverter motor.

[0009] Furthermore, it also includes a wire clamp for fixing the double-layer shielded lead-out wire, the wire clamp includes a U-shaped wire clamp body, the wire clamp body includes an arch bridge-shaped wire clamping portion and a mounting portion extending laterally from one side of the arch bridge-shaped wire clamping portion, the bridge-shaped wire clamping portion forms an inwardly concave clamping groove, and the clamping groove is adapted to the double-layer shielded lead-out wire; the mounting portion is provided with a mounting hole for the hexagonal head bolt to pass through, and the wire clamp is screwed to the cover at the rear of the variable frequency motor.

[0010] Furthermore, the hoop has a C-shaped slot, which is compatible with the aviation male plug on the encoder side. The ends of the C-shaped slot are symmetrically provided with connecting ear plates, and the two connecting ear plates are connected by a locking screw.

[0011] Furthermore, a waterproof sealing ring is provided inside the female plug housing, and the inverter-side aviation female plug is sealed and matched with the encoder-side aviation male plug through the waterproof sealing ring.

[0012] Furthermore, the male plug housing and the female plug housing are both made of stainless steel.

[0013] The invention has the following beneficial effects: simple structure, convenient installation and disassembly, simple and quick disconnection and connection of encoder circuit when installing tower crane, and effectively improves the anti-interference ability and signal stability of encoder signal of variable frequency motor, which effectively guarantees the stable operation of three major mechanisms of frequency converter and tower crane. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The utility model is a structural schematic diagram of an existing variable frequency motor encoder signal lead-out junction box.

[0015] Figure 2 It is a structural schematic diagram of the present invention.

[0016] Figure 3 It is a structural schematic diagram of the mounting bracket.

[0017] Figure 4 This is a schematic diagram of the structure of the aviation male plug on the encoder side.

[0018] Figure 5 It is a structural diagram of the aircraft carrier plug on the inverter side.

[0019] Figure 6 This is a schematic diagram of the structure of a line card.

[0020] Explanation of the reference numerals: 1. Frequency conversion motor; 2. Male aviation plug on the encoder side; 21. Male plug housing; 22. Clamp; 23. First cable waterproof connector; 24. Double-layer shielded lead wire; 25. Encoder; 3. Mounting bracket; 4. Female aviation plug on the inverter side; 41. Female plug housing; 42. Second cable waterproof connector; 43. Double-layer shielded extension wire; 5. Wire clip; 51. Wire clip body; 52. Hexagonal head bolt. DETAILED DESCRIPTION

[0021] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] In the description of the present invention, it should be noted that the orientations or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0023] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0024] Referring to the accompanying drawings, a tower crane variable frequency motor encoder anti-electromagnetic interference signal lead-out device includes an encoder 25 installed at the rear end of the rotating shaft of the variable frequency motor 1, and the encoder 25 is concentrically arranged with the rotating shaft of the variable frequency motor 1; the encoder 25 is connected to the encoder side aviation male plug 2 through a double-layer shielded lead-out line 24; the encoder side aviation male plug 2 is connected to the inverter side aviation female plug 4 by plugging, and the inverter side aviation female plug 4 is connected to the inverter through a double-layer shielded extension line 43; the encoder side aviation male plug 2 is fixed to the outer surface of the cover at the rear of the variable frequency motor 1 through a mounting bracket 3;

[0025] The double-layer shielded lead wire 24 is composed of a wire and a shielding layer wrapped around the outside of the wire; the encoder-side aviation male plug 2 includes a male plug housing 21, a pin arranged in the male plug housing 21, and a first cable waterproof connector 23 arranged at the rear end of the male plug housing 21. The male plug housing 21 is made of stainless steel. The shielding layer of the double-layer shielded lead wire 24 is electrically short-circuited with the male plug housing 21. The wire of the double-layer shielded lead wire 24 is introduced into the pin in the encoder-side aviation male plug 2 through the first cable waterproof connector 23.

[0026] The double-layer shielded extension line 43 is composed of a wire and a shielding layer wrapped around the outside of the wire; the inverter side aircraft mother plug 4 includes a female plug shell 41, a plug core arranged in the female plug shell 41, and a second cable waterproof connector 42 arranged at the rear end of the female plug shell 41. The female plug shell 41 is made of stainless steel. The shielding layer of the double-layer shielded extension line 43 is electrically short-circuited with the female plug shell 41, and the wire of the double-layer shielded extension line 43 is introduced into the plug core of the inverter side aircraft mother plug 4 through the second cable waterproof connector 42; a waterproof sealing ring is provided inside the female plug shell 41, and the inverter side aircraft mother plug 4 is sealed with the encoder side aviation male plug 2 through the waterproof sealing ring;

[0027] The mounting bracket 3 is welded to the outer surface of the cover at the tail of the variable frequency motor 1. The mounting bracket 3 is a rectangular plate-like structure. A through hole adapted to the encoder-side aviation male plug 2 is provided at the center of the mounting bracket 3. First screw holes are provided at the four corners of the mounting bracket 3 respectively. A removable clamp 22 is sleeved on the outer surface of the encoder-side aviation male plug 2. The clamp 22 includes a hoop sheet, which has a C-shaped slot, which is adapted to the encoder-side aviation male plug. Connecting ear plates are symmetrically provided at the end of the C-shaped slot, and the two connecting ear plates are connected by locking screws. Second screw holes are provided at the four corners of the hoop sheet corresponding to the first screw holes, and bolts are passed through the first screw holes and the second screw holes. The clamp 22 is fixedly connected to the mounting bracket 3 by bolts.

[0028] The double-layer shielded lead wire 24 is fixed to the outer surface of the cover at the rear of the variable frequency motor 1 through a wire clamp. The wire clamp 5 includes a U-shaped wire clamp body 51. The wire clamp body 51 includes an arch bridge-shaped wire clamping portion and a mounting portion extending laterally from one side of the arch bridge-shaped wire clamping portion. The bridge-shaped wire clamping portion forms an inwardly concave clamping groove, which is adapted to the double-layer shielded lead wire; the mounting portion is provided with a mounting hole for the hexagonal head bolt 52 to pass through, and the wire clamp 5 is screwed to the cover at the rear of the variable frequency motor 1.

[0029] After the aviation male plug 2 on the encoder side is connected to the aviation female plug 4 on the inverter side, the shielding layer of the double-layer shielded lead-out wire 24, the male plug shell 21, the female plug shell 41, and the shielding layer of the double-layer shielded extension wire 43 form a closed conductor container, and the conductor container is grounded in turn through the mounting bracket 3 and the shell of the variable frequency motor 1.

[0030] When in use, the encoder signal at the end of the shaft of the variable frequency motor 1 is transmitted to the frequency converter via the double-shielded signal line and the aviation plug. The closed conductor grounding shell formed by the female aviation plug 4 on the frequency converter side and the male aviation plug 2 on the encoder side can effectively shield the complex and strong electromagnetic field interference from the variable frequency motor 1, ensuring the stable and reliable transmission of the encoder 25 signal, reducing a major unstable factor for the stable operation of the three major mechanisms of the frequency converter and the tower crane.

[0031] The contents described in the embodiments of this specification are merely an enumeration of the implementation forms of the inventive concept. The protection scope of the present invention should not be regarded as limited to the specific forms described in the embodiments. The protection scope of the present invention also extends to equivalent technical means that can be conceived by those skilled in the art based on the inventive concept.

Claims

1. A tower crane variable frequency motor encoder anti-electromagnetic interference signal extraction device, characterized in that: It includes an encoder installed at the tail of the variable frequency motor, the encoder is connected to the encoder side aviation male plug through a double-shielded lead wire; the encoder side aviation male plug is connected to the inverter side aviation female plug through plugging, and the inverter side aviation female plug is connected to the inverter through a double-shielded extension wire; the encoder side aviation male plug is fixed to the outer surface of the cover at the tail of the variable frequency motor through a mounting bracket; The double-layer shielded lead wire is composed of a wire and a shielding layer wrapped around the outside of the wire; the encoder side aviation male plug includes a male plug shell, a pin arranged in the male plug shell, and a first cable waterproof connector arranged at the rear end of the male plug shell, the male plug shell is made of metal material, the shielding layer of the double-layer shielded lead wire is electrically short-circuited with the male plug shell, and the wire of the double-layer shielded lead wire is introduced into the pin of the encoder side aviation male plug through the first cable waterproof connector; The double-layer shielded extension line is composed of a conductor and a shielding layer wrapped around the outside of the conductor; the inverter-side aircraft mother plug includes a female plug shell, a plug core arranged in the female plug shell, and a second cable waterproof connector arranged at the rear end of the female plug shell, the female plug shell is made of metal material, the shielding layer of the double-layer shielded extension line is electrically short-circuited with the female plug shell, and the conductor of the double-layer shielded extension line is introduced into the plug core of the inverter-side aircraft mother plug through the second cable waterproof connector; The mounting bracket is arranged on the outer surface of the cover at the tail of the variable frequency motor. The mounting bracket is a rectangular plate-shaped structure. A through hole adapted to the aviation male plug on the encoder side is opened in the center of the mounting bracket. First screw holes are respectively arranged at the four corners of the mounting bracket; a detachable clamp is sleeved on the outer surface of the aviation male plug on the encoder side. The clamp includes a hoop sheet. Second screw holes are respectively arranged at the four corners of the hoop sheet corresponding to the first screw holes. Bolts are passed through the first screw hole and the second screw hole. The clamp is fixedly connected to the mounting bracket by bolts; After the aviation male plug on the encoder side is connected to the aviation female plug on the inverter side, the shielding layer of the double-layer shielded lead-out wire, the male plug shell, the female plug shell, and the shielding layer of the double-layer shielded extension wire form a closed conductor container, which is grounded in turn through the mounting bracket and the shell of the inverter motor.

2. The tower crane variable frequency motor encoder anti-electromagnetic interference signal extraction device according to claim 1, characterized in that: It also includes a wire clip for fixing the double-layer shielded lead-out wire, the wire clip includes a U-shaped wire clip body, the wire clip body includes an arch bridge-shaped wire clip portion and a mounting portion extending laterally from one side of the arch bridge-shaped wire clip portion, the bridge-shaped wire clip portion forms an inwardly concave slot, and the slot is adapted to the double-layer shielded lead-out wire; the mounting portion is provided with a mounting hole for the hexagonal head bolt to pass through, and the wire clip is screwed to the cover shell at the rear of the variable frequency motor.

3. The tower crane variable frequency motor encoder anti-electromagnetic interference signal extraction device according to claim 1, characterized in that: The hoop piece has a C-shaped slot, which is compatible with the aviation male plug on the encoder side. The end of the C-shaped slot is symmetrically provided with connecting ear plates, and the two connecting ear plates are connected by a locking screw.

4. The tower crane variable frequency motor encoder anti-electromagnetic interference signal extraction device according to claim 1, characterized in that: A waterproof sealing ring is provided inside the female plug housing, and the inverter-side aviation female plug is sealed and matched with the encoder-side aviation male plug through the waterproof sealing ring.

5. The tower crane variable frequency motor encoder anti-electromagnetic interference signal extraction device according to claim 1, characterized in that: The male plug housing and the female plug housing are both made of stainless steel.

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