阅读说明：本技术 一种多自由度转轴转速拾取装置 (Multi-degree-of-freedom rotating shaft rotating speed pickup device ) 是由 纪科 龙俊峰 张俊伟 韩俊峰 马宇 杨木杭 白佳昊 葛萌 于 2021-04-16 设计创作，主要内容包括：本发明公开了一种多自由度转轴转速拾取装置,其包括主轴；连接轴上同轴套设有转动设置的测速盘；测速盘的一侧盘面上沿周向均布设置有若干个伸缩杆,牵引盘的中部同轴穿设卡接有主轴,主轴背向连接轴的端部与球笼同步万向联轴器的一端连接,球笼同步万向联轴器的另一端滑动套设有花键套；安装架上固定有测速元件。优点：本发明通过花键套与球笼同步万向联轴器的匹配,能够抵消转轴的轴向窜动；滑杆沿滑套进行滑动,能够抵消转轴在径向平面内的跳动；由此,实现将转轴的各自由度方向的位移进行抵消,避免传递到测速盘,进而保证测速盘始终保持平稳转动,避免对测速元件造成损坏,保证测速的准确性和可靠性,进而避免系统误动作。(The invention discloses a multi-degree-of-freedom rotating shaft rotating speed pickup device, which comprises a main shaft; a speed measuring disc which is rotatably arranged is coaxially sleeved on the connecting shaft; a plurality of telescopic rods are uniformly distributed on the disc surface on one side of the speed measuring disc along the circumferential direction, a main shaft is coaxially inserted and clamped in the middle of the traction disc in a penetrating manner, the end part of the main shaft, which is back to the connecting shaft, is connected with one end of a ball cage synchronous universal coupling, and the other end of the ball cage synchronous universal coupling is slidably sleeved with a spline sleeve; a speed measuring element is fixed on the mounting rack. The advantages are that: according to the invention, through the matching of the spline sleeve and the ball cage synchronous universal coupling, the axial movement of the rotating shaft can be counteracted; the sliding rod slides along the sliding sleeve, so that the jumping of the rotating shaft in a radial plane can be counteracted; therefore, the rotating shaft is offset by the displacement in the degree direction, the speed measuring disc is prevented from being transmitted, the speed measuring disc is guaranteed to rotate stably all the time, the speed measuring element is prevented from being damaged, the accuracy and the reliability of speed measurement are guaranteed, and the system misoperation is further avoided.)

1. A multi-degree-of-freedom rotating shaft rotating speed pickup device is characterized by comprising a fixed main body, a traction disc and a main shaft; a connecting shaft is fixed on the mounting frame of the fixed main body, and a speed measuring disc which is rotatably arranged is coaxially sleeved on the connecting shaft; a plurality of telescopic rods are uniformly distributed on the disc surface on one side of the speed measuring disc along the circumferential direction, the telescopic rods are vertically arranged relative to the connecting shaft, a sliding sleeve of each telescopic rod is rotatably connected to the speed measuring disc, a sliding rod of each telescopic rod is rotatably connected with the traction disc, and the traction discs are arranged in parallel relative to the speed measuring disc; the main shaft is coaxially inserted and clamped in the middle of the traction disc in a penetrating manner, the end part of the main shaft, which is back to the connecting shaft, is connected with one end of the ball cage synchronous universal coupling, and the other end of the ball cage synchronous universal coupling is slidably sleeved with a spline sleeve; and a speed measuring element is fixed on the mounting rack.

2. The multi-degree-of-freedom rotating shaft rotating speed pickup device as claimed in claim 1, wherein the speed measuring element is a proximity switch; and a plurality of induction blocks corresponding to the speed measuring elements are fixed on the outer edge of the speed measuring disc along the circumferential direction.

3. The multi-degree-of-freedom rotating shaft rotating speed pickup device as claimed in claim 1, wherein a hollow disc body is coaxially fixed on the connecting shaft between the traction disc and the speed measuring disc, an end portion of the main shaft is disposed in the hollow disc body, and a sliding guide disc is coaxially fixed, and a plurality of oil through holes are formed in the sliding guide disc.

4. The multi-degree-of-freedom rotating shaft rotating speed pickup device according to claim 3, wherein the hollow disc body comprises a fixed guide disc, a gasket and a limiting ring plate which are coaxially arranged; the fixed guide disc is coaxially fixed at the end part of the connecting shaft through a screw, and the gasket and the limiting ring plate are sequentially attached and fixed on the disc surface of one side of the fixed guide disc, which is adjacent to the traction disc, through screws; the sliding guide disc is arranged between the fixed guide disc and the limiting ring plate.

5. The multi-degree-of-freedom rotating shaft rotating speed pickup device according to claim 1, wherein the telescopic rod comprises the sliding sleeve and the sliding rod which is slidably inserted into the opening end of the sliding sleeve; the closed end of the sliding sleeve is provided with a damping hole.

6. The multi-degree-of-freedom rotating shaft rotating speed pickup device as claimed in claim 5, wherein a bushing is slidably inserted in the sliding sleeve, the sliding rod is slidably disposed in the bushing, a lock cap screwed at an opening end of the sliding sleeve is sleeved on the sliding rod, and the lock cap abuts against an end of the bushing.

7. The multi-degree-of-freedom rotating shaft rotating speed pickup device according to any one of claims 1 to 6, wherein the fixed body comprises the mounting frame and a box body with openings at two ends; the mounting frame is fixed in the box body; the two ends of the box body are respectively fixed with a front end cover and a rear end cover through screws, the rear end cover is provided with a central hole, and the main shaft penetrates through the central hole and is arranged in the box body.

8. The multi-degree-of-freedom rotating shaft rotating speed pickup device according to claim 7, further comprising a box body fixing frame and a box body connecting frame; the box body connecting frame is rotatably connected with the box body fixing frame through a support rotating shaft, one side of the box body connecting frame is connected with the box body fixing frame through a locking screw, and the other side of the box body connecting frame is connected with the side wall of the box body through a screw.

9. The multi-degree-of-freedom rotating shaft rotating speed pickup device as claimed in claim 7, wherein the speed measuring disc is vertically screwed with a limiting rod on the disc surface corresponding to the two sides of each telescopic rod.

The technical field is as follows:

the invention relates to the technical field of mechanical equipment, in particular to a multi-degree-of-freedom rotating shaft rotating speed pickup device.

Background art:

in mechanical transmission equipment, according to actual production requirements on site, the rotating speed of a rotating shaft of the transmission equipment is generally required to be acquired so as to feed back and control the running state of relevant equipment on site, and the running of the equipment is convenient to match; in the actual operation process of transmission equipment on some occasions, the rotating shaft usually has movement in multiple freedom directions, including axial movement, radial run-out, certain rotation around the end part of the rotating shaft and the like, and in the process, damage of a sensor for acquiring the rotating speed or signal loss caused by too large measurement gap is easily caused, so that the rotating speed acquisition fails, and normal production on the site is seriously influenced.

For example, a pebble coal conveying system of a boiler coal mill is an important system for stably supplying fuel in a thermal power plant; the pebble coal produced by the coal mill system is continuously conveyed into a vertical shaft of a pebble coal bucket elevator through a horizontal conveying chain, and a lifting chain of the bucket elevator drives the elevator bucket to continuously lift the pebble coal falling into the vertical shaft to a conveying device at the upper part; in order to prevent the bucket elevator from being stuck and overloaded, a driven end rotating shaft of the bucket elevator is generally designed to be arranged on two movable side plates, the movable side plates obtain downward traction force through a counterweight to drive the driven end rotating shaft to move downwards and tension a pebble coal lifting chain in a lifting shaft, so that the upward lifting force of the lifting chain acting on a driven shaft and the downward traction force formed by the counterweight can be in dynamic balance; in order to acquire the rotating speed of the driven rotating shaft on line, a speed measuring disc is fixed at the tail end of the rotating shaft, a probe (speed measuring element) support is fixed on a frame of the bucket elevator at a position close to the speed measuring disc, then a probe is fixed on the probe support, and the rotating speed of the rotating shaft is detected in real time through the probe in the process that the speed measuring disc rotates along with the rotating shaft at the driven end.

In the operation process, the rotating shaft at the driven end of the bucket elevator has displacement of a plurality of degrees of freedom, and the movement amount in the direction of each degree of freedom is large, so that the condition that a probe is damaged by a speed measuring disc often occurs, the whole pebble coal system is protected, and the system is stopped; similarly, the moving amount of the rotating shaft is relatively large, so that the distance between the probe and the speed measuring disc is easily caused to exceed the detection range of the probe, and the misoperation of system rotating speed protection is caused; once the pebble coal system is shut down, pebble coal of the coal mill can only be discharged on the ground near the coal mill, so that the environment is polluted, manpower is wasted, the ground is damaged, even the output of the coal mill is limited, and the stable and reliable operation of a boiler fuel supply system is seriously influenced.

The invention content is as follows:

the invention aims to provide a multi-degree-of-freedom rotating shaft rotating speed pickup device which effectively avoids damage to a probe and signal loss caused by overlarge measurement gap, so that the rotating speed detection is stable and accurate, and the system misoperation is further avoided.

The invention is implemented by the following technical scheme: a multi-degree-of-freedom rotating shaft rotating speed pickup device comprises a fixed main body, a traction disc and a main shaft; a connecting shaft is fixed on the mounting frame of the fixed main body, and a speed measuring disc which is rotatably arranged is coaxially sleeved on the connecting shaft; a plurality of telescopic rods are uniformly distributed on the disc surface on one side of the speed measuring disc along the circumferential direction, the telescopic rods are vertically arranged relative to the connecting shaft, a sliding sleeve of each telescopic rod is rotatably connected to the speed measuring disc, a sliding rod of each telescopic rod is rotatably connected with the traction disc, and the traction discs are arranged in parallel relative to the speed measuring disc; the main shaft is coaxially inserted and clamped in the middle of the traction disc in a penetrating manner, the end part of the main shaft, which is back to the connecting shaft, is connected with one end of the ball cage synchronous universal coupling, and the other end of the ball cage synchronous universal coupling is slidably sleeved with a spline sleeve; and a speed measuring element is fixed on the mounting rack.

Further, the speed measuring element is a proximity switch; and a plurality of induction blocks corresponding to the speed measuring elements are fixed on the outer edge of the speed measuring disc along the circumferential direction.

Furthermore, a hollow disc body is coaxially fixed on the connecting shaft between the traction disc and the speed measuring disc, the end part of the main shaft is arranged in the hollow disc body, a sliding guide disc is coaxially fixed on the end part of the main shaft, and a plurality of oil through holes are formed in the sliding guide disc.

Furthermore, the hollow disc body comprises a fixed guide disc, a gasket and a limit ring plate which are coaxially arranged; the fixed guide disc is coaxially fixed at the end part of the connecting shaft through a screw, and the gasket and the limiting ring plate are sequentially attached and fixed on the disc surface of one side of the fixed guide disc, which is adjacent to the traction disc, through screws; the sliding guide disc is arranged between the fixed guide disc and the limiting ring plate.

Further, the telescopic rod comprises the sliding sleeve and the sliding rod which is inserted into the opening end of the sliding sleeve in a sliding mode; the closed end of the sliding sleeve is provided with a damping hole.

Further, slide in the sliding sleeve and wear to be equipped with the bush, the slide bar is in slide in the bush and set up, the cover is equipped with the spiro union on the slide bar and is in the lock cap of the open end of sliding sleeve, the lock cap with the tip butt of bush.

Further, the fixing body comprises the mounting frame and a box body with openings at two ends; the mounting frame is fixed in the box body; the two ends of the box body are respectively fixed with a front end cover and a rear end cover through screws, the rear end cover is provided with a central hole, and the main shaft penetrates through the central hole and is arranged in the box body.

Furthermore, the device also comprises a box body fixing frame and a box body connecting frame; the box body connecting frame is rotatably connected with the box body fixing frame through a support rotating shaft, one side of the box body connecting frame is connected with the box body fixing frame through a locking screw, and the other side of the box body connecting frame is connected with the side wall of the box body through a screw.

Furthermore, the speed measuring disc is vertically screwed with a limiting rod on the disc surface corresponding to two sides of each telescopic rod.

The invention has the advantages that: according to the invention, through the matching of the spline sleeve and the ball cage synchronous universal coupling, the axial movement of the rotating shaft can be counteracted, and the angular movement can be counteracted by the ball cage synchronous universal coupling; the sliding rod slides along the sliding sleeve, so that the jumping of the rotating shaft in a radial plane can be counteracted; therefore, the displacement of the rotating shaft in the multi-degree-of-freedom direction is offset, the speed measuring disc is prevented from being transmitted, the speed measuring disc is guaranteed to rotate stably all the time, the speed measuring element is prevented from being damaged, the accuracy and the reliability of speed measurement are guaranteed, and the system misoperation is avoided.

Description of the drawings:

FIG. 1 is a schematic structural diagram of the present invention.

Fig. 2 is a top view of fig. 1.

Fig. 3 is a sectional view a-a of fig. 1.

Fig. 4 is a view from direction B of fig. 3.

Fig. 5 is a schematic structural view of the present invention with the front end cover removed.

Fig. 6 is a schematic structural view of the case fixed with the mounting bracket according to the present invention.

Fig. 7 is a left side view of fig. 6.

Fig. 8 is a cross-sectional view taken along line C-C of fig. 6.

Fig. 9 is a cross-sectional view taken along line D-D of fig. 6.

Fig. 10 is a schematic structural view of the sliding guide disk according to the present invention.

Fig. 11 is a schematic structural view of the rear end cap of the present invention.

Fig. 12 is a schematic view of the usage state of the present invention.

The parts in the drawings are numbered as follows: the synchronous universal coupling comprises a spline housing 1.1, a ball cage synchronous universal coupling 1.2, a rotating shaft 2, a fixed main body 3, an installation frame 3.1, a box body 3.2, a front end cover 3.3, a rear end cover 3.4, a central hole 3.41, a box body fixing frame 3.5, a box body connecting frame 3.6, a support rotating shaft 3.7, a locking screw 3.8, a main shaft 4, a traction disc 5, a connecting shaft 6, a speed measuring disc 7, an expansion link 8, a sliding sleeve 8.1, a sliding rod 8.2, a damping hole 8.3, a bushing 8.4, a locking cap 8.5, an induction block 9, a speed measuring element 10, a hollow disc body 11, a fixed guide disc 11.1, a gasket 11.2, a limiting ring plate 11.3, a sliding guide disc 12, an oil through hole 12.1, a limiting rod 13, a protective hose 14, a connecting column 15 and a bucket elevator 16.

The specific implementation mode is as follows:

the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As shown in fig. 1 to 12, the present embodiment provides a multi-degree-of-freedom rotating shaft speed pickup apparatus, which includes a fixed body 3, a traction disc 5 and a main shaft 4; a connecting shaft 6 is fixed on an installation frame 3.1 of the fixed main body 3, a speed measuring disc 7 which is rotatably arranged is coaxially sleeved on the connecting shaft 6, and the disc surface of the speed measuring disc 7 is vertically arranged relative to the connecting shaft 6; a plurality of telescopic rods 8 are uniformly and circumferentially arranged on the disc surface on one side of the speed measuring disc 7, in the embodiment, three telescopic rods 8 which are uniformly arranged are arranged, the telescopic rods 8 are vertically arranged relative to the connecting shaft 6, a sliding sleeve 8.1 of each telescopic rod 8 is rotatably connected to the speed measuring disc 7, a sliding rod 8.2 of each telescopic rod 8 is rotatably connected with the traction disc 5, in the embodiment, the traction disc 5 is of a triangular structure, and three corners of the traction disc 5 are respectively connected with the corresponding sliding rods 8.2; the telescopic rod 8 comprises a sliding sleeve 8.1 and a sliding rod 8.2; a bushing 8.4 penetrates through the sliding sleeve 8.1 in a sliding mode, a sliding rod 8.2 is inserted into the bushing 8.4 in a sliding mode, a lock cap 8.5 which is screwed at the opening end of the sliding sleeve 8.1 is sleeved on the sliding rod 8.2, the lock cap 8.5 is abutted to the end portion of the bushing 8.4, the bushing 8.4 is tightly pressed in the sliding sleeve 8.1 through the lock cap 8.5, and the bushing 8.4 is made of wear-resistant copper materials, so that the service life is prolonged; the closed end of the sliding sleeve 8.1 is provided with a damping hole 8.3, and the size of the damping hole 8.3 needs to be actually tested before the product leaves a factory so as to obtain an ideal damping effect; in the test process, damping screws with different pore diameters are manufactured, then the test is carried out in sequence according to the pore diameters from small to large, the damping screw with the proper pore diameter is selected, the damping screw is screwed on the closed end of the sliding sleeve 8.1, and the hole on the damping screw is the damping hole 8.3.

The traction disc 5 drives the sliding rod 8.2 to rotate, and meanwhile, when the sliding rod 8.2 extends out along the sliding sleeve 8.1, negative pressure is formed in a rodless cavity of the sliding sleeve 8.1 due to the existence of the damping hole 8.3, the area of the end face of the closed end of the sliding sleeve 8.1 is larger than that of the end face of the open end, at the moment, the sliding sleeve 8.1 is pushed to move along the rotating direction under the action of atmospheric pressure, and then the speed measuring disc 7 can be driven to rotate, and in the process, air slowly enters from the damping hole 8.3; when the sliding rod 8.2 is contracted along the sliding sleeve 8.1, positive pressure exists in the rodless cavity of the sliding sleeve 8.1, the sliding sleeve 8.1 is continuously pushed to move along the rotating direction of the traction disc 5 under the action of the positive pressure, and the speed measuring disc 7 can be continuously driven to rotate; at the moment, air in the rodless cavity of the sliding sleeve 8.1 is slowly exhausted from the damping hole 8.3, so that an effective damping effect can be achieved on the sliding rod 8.2, strong impact is avoided, and the service life of the sliding sleeve is prolonged; the end part of the sliding rod 8.2 is rotationally connected with the traction disc 5 through a fisheye joint bearing, the end part of the sliding sleeve 8.1 is vertically fixed with a connecting column 15, and the end part of the connecting column 15 is rotationally connected with the speed measuring disc 7 through a bearing; the traction disc 5 is arranged in parallel relative to the speed measuring disc 7, the main shaft 4 is coaxially inserted and clamped in the middle of the traction disc 5, the cross section of the main shaft 4 is of a regular polygon structure, the embodiment is of a regular hexagon structure, a regular hexagon hole matched with the main shaft 4 is formed in the center of the traction disc 5, and the traction disc 5 can be driven to synchronously rotate in the rotating process of the main shaft 4; the end part of the main shaft 4, which is back to the connecting shaft 6, is connected with one end of the ball cage synchronous universal coupling 1.2, one end of a spline shaft of the ball cage synchronous universal coupling 1.2 is inserted into one end of the spline housing 1.1 in a sliding manner, and the other end of the spline housing 1.1 is coaxially screwed on the rotating shaft 2; the invention is connected with the rotating shaft 2 through the spline sleeve 1.1, so that power is convenient to transmit; the spline sleeve 1.1 can axially slide along a spline shaft of the ball cage synchronous universal coupling 1.2, so that the axial movement of the rotating shaft 2 can be counteracted; the ball cage synchronous universal coupling 1.2 has angular compensation capability and can offset the deviation displacement of the rotating shaft 2.

In the process that the rotating shaft 2 drives the main shaft 4 to rotate through the ball cage synchronous universal coupling 1.2, the speed measuring disc 7 rotates under the driving of the traction disc 5; when the rotating shaft 2 jumps radially, the corresponding sliding rod 8.2 slides along the sliding sleeve 8.1, so that the jump of the rotating shaft 2 in a radial plane is counteracted; a plurality of sensing blocks 9 are uniformly distributed and fixed on the outer edge of the speed measuring disk 7 along the circumferential direction, six sensing blocks 9 are arranged in the embodiment, each sensing block 9 is a magnetic conductive metal block, the speed measuring disk 7 is made of a non-magnetic conductive material, and a speed measuring element 10 corresponding to each sensing block 9 is fixed on a mounting rack 3.1 of the fixing main body 3, wherein the speed measuring element 10 is a proximity switch, and the speed measuring element 10 can be conveniently disassembled and assembled after the front end cover 3.3 is disassembled; in the process of rotating the speed measuring disk 7, the speed measuring element 10 is triggered by the induction block 9, so that the rotating speed of the rotating shaft 2 is detected; in the rotating process of the rotating shaft 2, the spline sleeve 1.1 is matched with the ball cage synchronous universal coupling 1.2, so that the axial movement of the rotating shaft 2 can be counteracted, and the ball cage synchronous universal coupling 1.2 can counteract the angular movement, namely the deflection of the rotating shaft 2; the sliding rod 8.2 slides along the sliding sleeve 8.1, so that the jumping of the rotating shaft 2 in a radial plane can be counteracted; therefore, the displacement and deflection in the multi-degree-of-freedom direction of the rotating shaft 2 are offset, the speed measuring disc 7 is prevented from being transmitted, the speed measuring disc 7 is guaranteed to rotate stably all the time, meanwhile, the speed measuring element 10 can be prevented from being damaged, the accuracy and the reliability of speed measurement are guaranteed, and the misoperation of the system is further avoided.

A hollow disc body 11 is fixed on a connecting shaft 6 between the traction disc 5 and the speed measuring disc 7, the end part of the main shaft 4 is arranged in the hollow disc body 11 and is coaxially fixed with a sliding guide disc 12, a plurality of oil through holes 12.1 are formed in the sliding guide disc 12, and when the main shaft 4 drives the sliding guide disc 12 to run in the hollow disc body 11, lubricating oil in the hollow disc body 11 is favorably thrown to each part in a gap between the sliding guide disc 12 and the hollow disc body 11 through the oil through holes 12.1, so that the lubricating oil is distributed more uniformly, and the rotating efficiency of the sliding guide disc 12 in the hollow disc body 11 is ensured under the effective lubricating and cooling action; the hollow disc body 11 comprises a fixed guide disc 11.1, a gasket 11.2 and a limit ring plate 11.3 which are coaxially arranged; the fixed guide disc 11.1 is coaxially fixed at the end part of the connecting shaft 6 through a screw, and a gasket 11.2 and a limit ring plate 11.3 are sequentially attached and fixed on the disc surface of one side, adjacent to the traction disc 5, of the fixed guide disc 11.1 through screws; the sliding guide disc 12 is arranged between the fixed guide disc 11.1 and the limit ring plate 11.3; when the rotating shaft 2 axially moves, the spline sleeve 1.1 slides along the spline shaft on the ball cage synchronous universal coupling 1.2, and simultaneously, under the action of friction force, the ball cage synchronous universal coupling 1.2 is pushed to drive the sliding guide disc 12 to move, the sliding guide disc 12 is effectively limited by the fixed guide disc 11.1 and the limiting ring plate 11.3, and the main shaft 4 is prevented from colliding with the connecting shaft 6; the perpendicular spiro union has gag lever post 13 on the quotation that the dish 7 that tests the speed corresponds every telescopic link 8 both sides, can restrict the turned angle of the telescopic link 8 that corresponds through gag lever post 13, effectively avoids slide bar 8.2 to follow the roll-off of sliding sleeve 8.1, guarantees that the dish 7 that tests the speed can rotate along with traction disc 5 and does not break away from.

The fixed main body 3 comprises a box body fixing frame 3.5, a box body connecting frame 3.6, a mounting frame 3.1 and a box body 3.2 with openings at two ends; the box body fixing frame 3.5 is fixedly connected with the equipment body adjacent to the rotating shaft 2, in the embodiment, the box body fixing frame 3.5 is fixed on the outer wall of the bucket elevator 16, the box body connecting frame 3.6 is rotatably connected with the box body fixing frame 3.5 through a support rotating shaft 3.7, one side of the box body connecting frame 3.6 is connected with the box body fixing frame 3.5 through a locking screw 3.8, and the other side of the box body connecting frame 3.6 is connected with the side wall of the box body 3.2 through a screw; after the locking screw 3.8 is disassembled, the box body connecting frame 3.6 can rotate around the support rotating shaft 3.7, so that the box body 3.2 can be conveniently moved, and the box body 3.2 can be maintained by rotating the box body 3.2 around the support rotating shaft 3.7 by a proper angle without disassembling the box body 3.2 during maintenance, thereby providing great convenience for maintenance and being beneficial to improving the working efficiency; a front end cover 3.3 and a rear end cover 3.4 are respectively fixed at two ends of the box body 3.2 through screws, a central hole 3.41 is formed in the rear end cover 3.4, the main shaft 4 penetrates through the central hole 3.41 and is arranged in the box body 3.2, and the rear end cover 3.4 is provided with two half cover plates, so that the field assembly and disassembly are convenient; the invention is covered by the box body 3.2, thus avoiding the pollution of the parts covered by the box body 3.2 by foreign matters in the external environment, being beneficial to reducing the maintenance frequency and prolonging the service life of the invention; when the maintenance needs to be carried out on the invention, the front end cover 3.3 and the rear end cover 3.4 are opened, the locking screw 3.8 is disassembled, and the box body 3.2 is rotated to a proper position around the bracket rotating shaft 3.7, so that the maintenance is convenient; in addition, the box body 3.2 is used for covering the invention, so that the danger of the safety of workers caused by the exposure of rotating parts is avoided; threaded holes are formed in the bottom of the box body 3.2, the protective hose 14 used for penetrating through a lead of the speed measuring element 10 is installed and connected, the protective hose 14 is arranged at the bottom of the box body 3.2, and rainwater above the box body 3.2 can be prevented from entering the box body 3.2 through the protective hose 14.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.