Rear frame structure of electric loader

Abstract

The utility model discloses a rear frame structure of an electric loader. The rear frame structure comprises a tail box body, a mounting groove is formed in the upper surface of the tail box body and is used for mounting a battery box bracket in a sinking manner; a reinforcing plate is arranged in the symmetric center of the left-right direction of the mounting groove, and the front and rear ends of the reinforcing plate are integrally connected with the front and rear walls of the mounting groove. Through the mounting groove sinking in the upper surface of the tail box body, a battery box bracket of the electric loader can be mounted in a sinking manner, so that the arrangement space of a battery is enlarged, the arrangement height of the battery box bracket is reduced, the tail height of the loader is further reduced, and the problem that the rear view of a driver is seriously insufficient is solved; the operation safety and the operation efficiency of the machine are improved, the probability that the tail of the machine is damaged due to collision is reduced, more batteries can be configured, the continuous operation time of the machine is prolonged, and the application range and the competitiveness of the product are improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to engineering machinery technical field, especially point to a kind of rear frame structure of electric loader. BACKGROUND

[0002] In existing engineering machinery, the height of rear frame tail frame is about 200mm, its itself and lower space cannot be utilized, power battery can only be arranged on the upper of tail frame, increase the tail height of machine, seriously affect the rear view of driver, and further affect the operation safety and operation efficiency of machine, increase the security risk of collision between tail of machine and obstacle.

[0003] Meanwhile, due to the fact that tail frame itself and lower space cannot be utilized, the number of battery that machine can arrange is limited, the continuous operation time of machine cannot be improved, the use range of product is limited, and the competitiveness of product is reduced.

[0004] In addition, the wiring end of battery is all towards the front end of machine, and the distance between battery and other systems of machine is small, which increases the difficulty of wiring, pipe connecting operation and daily maintenance of battery. INVENTION CONTENTS

[0005] The utility model aims at providing a kind of rear frame structure of electric loader, solve the problems in prior art, increase the arrangement space of power battery, reduce the tail height of machine.

[0006] In order to achieve the above-mentioned purpose, the solution of the utility model is as follows:

[0007] A kind of rear frame structure of electric loader, including tail box;The upper surface of the tail box is provided with mounting groove, for sinking type installation battery box support;The center of symmetry of the mounting groove left and right direction is provided with reinforcing plate, the front and rear ends of the reinforcing plate are integrally connected with the front and rear walls of the mounting groove.

[0008] The front wall of the mounting groove is provided with protruding part, and the front end of the reinforcing plate is integrally connected to the inner wall of the protruding part.

[0009] The mounting groove is provided with the support part of upper and lower layer battery support, and the support part of upper and lower layer battery support is staggered in horizontal projection plane;The interval of front side support part in the support part of each layer battery support is less than the interval of rear side support part.

[0010] The left and right walls of the mounting groove are each provided with an installation and maintenance opening, and the installation and maintenance opening is provided with openable and closable movable cover.

[0011] The rear wall top of the mounting groove is provided with rear beam, and the both ends of the rear beam are integrally connected to the left and right walls of the mounting groove, and a traction pin is arranged in the rear beam.

[0012] The rear frame structure of the electric loader further comprises a battery box support; the battery box support is divided into upper and lower layers, the lower layer comprises two groups of first and second supports arranged symmetrically left and right, the upper layer comprises a third support arranged above the first support and a fourth support arranged above the third support; the first and second supports are arranged in the mounting groove of the tail box, and one battery is arranged in each of the first and second supports; two batteries are arranged in each of the third and fourth supports in parallel; the direction of the batteries arranged in the upper layer is perpendicular to the direction of the batteries arranged in the lower layer.

[0013] Preferably, the batteries in the first and second supports are arranged along the transverse direction of the rear frame, and the batteries in the third and fourth supports are arranged along the longitudinal direction of the rear frame.

[0014] Preferably, the battery connection ends in the first and second supports are arranged on the left and right sides of the machine, and the battery connection ends and connection pipes in the third and fourth supports are arranged on the rear side of the machine.

[0015] Preferably, a pair of first locking feet are arranged on the front and rear surfaces of the first support, a pair of second locking feet are arranged on the front surface of the third support, and a third locking foot is arranged on each of the left and right surfaces of the third support; the first, second and third locking feet are staggered on the horizontal projection plane of the rear frame, and are locked to the tail box.

[0016] Preferably, the distance between the pair of first locking feet on the front surface of the first support is smaller than the distance between the pair of first locking feet on the rear surface of the first support, and the distance between the second locking feet of the third support is smaller than the distance between the third locking feet of the third support.

[0017] Preferably, a rear beam is arranged on the top of the rear wall of the mounting groove, two rear upper support portions are arranged on the front side of the rear beam, a front beam is arranged on the top of the front wall of the mounting groove, two front upper support portions and four front lower support portions are arranged on the front beam, a support beam is arranged above the rear part of the mounting groove, and four rear lower support portions are arranged on the support beam; the first locking feet on the front and rear surfaces of the first support are locked to the front and rear lower support portions by threaded connectors; the second locking feet of the third support are locked to the front upper support portions by threaded connectors, and the third locking feet are locked to the rear upper support portions by threaded connectors; the second support is locked below the first support by a threaded connector, and the fourth support is locked above the third support by a threaded connector.

[0018] Preferably, a shock-absorbing pad is arranged between each of the first, second and third locking feet and the corresponding support portion.

[0019] The utility model discloses the following technical effects are obtained after the above technical scheme is adopted:

[0020] (1) through the installation groove sinking in the tail box upper surface, can realize sinking type installation electric loader's battery box support, utilize the counterweight of the rear frame and the space of the girder in the prior art, the arrangement space of battery is increased significantly, to this increases the arrangement space of battery, reduces the arrangement height of battery box support, further reduces the tail height of machine, solves the problem that the driver rear view is seriously insufficient, improves machine operation efficiency and safety, also reduces the probability of damage of machine tail due to collision, and because the battery is arranged centrally in the tail of machine, need only smaller and lighter counterweight to realize smaller overall weight under the condition of equivalent performance, saves manufacturing cost and operating cost, because more batteries (increase from 8 to 10) can be arranged, the utility model can greatly prolong the continuous operation time of machine, expand the application range of machine, improve product competitiveness;

[0021] (2) through the reinforcing plate arranged in the installation groove, the strength of the tail box can be strengthened, so that the tail box can not only bear the weight of the battery and the support, but also bear greater traction force, the tail box is only the rear half of the rear frame, can be machined separately with the front structure of the rear frame and then welded into the rear frame assembly, will not produce larger deformation, need not machining after welding, this structure does not need large machining equipment, and the front and rear two parts are separated and machined simultaneously, which can also speed up the production rhythm. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is the rear frame perspective drawing of the utility model specific embodiment;

[0023] Figure 2 It is the tail box perspective drawing of the utility model specific embodiment;

[0024] Figure 3 It is the tail box and battery box support perspective drawing of the utility model specific embodiment;

[0025] Figure 4 It is the battery box support overall perspective drawing of the utility model specific embodiment;

[0026] Figure 5 It is the first support perspective drawing of the utility model specific embodiment;

[0027] Figure 6 It is the second support perspective drawing of the utility model specific embodiment;

[0028] Figure 7 It is the third support perspective drawing of the utility model specific embodiment;

[0029] Figure 8 is a fourth support stereogram of the embodiment of the utility model;

[0030] Figure 9 is a fifth support stereogram of the embodiment of the utility model;

[0031] Explanation of reference numerals:

[0032] 1 - tail box; 11 - installation groove; 12 - reinforcing plate; 13 - protruding part; 14 - installation maintenance opening; 15 - movable cover; 16 - rear beam; 161 - rear upper support part; 17 - traction pin; 18 - front beam; 181 - front upper support part; 182 - front lower support part; 19 - support beam; 191 - rear lower support part;

[0033] 2 - battery box support; 21 - first support; 211 - first locking leg; 212 - weight reduction hole; 213 - maintenance window; 22 - second support; 221 - weight reduction hole; 222 - maintenance window; 23 - third support; 231 - second locking leg; 232 - third locking leg; 233 - first connecting plate; 234 - first steel pipe; 235 - weight reduction hole; 236 - maintenance window; 24 - fourth support; 241 - second connecting plate; 242 - weight reduction hole; 243 - maintenance window; 25 - fifth support; 251 - third connecting plate; 252 - weight reduction hole;

[0034] 3 - shock pad;

[0035] 4 - front structure;

[0036] a - battery. DETAILED DESCRIPTION

[0037] In order to further explain the technical scheme of the utility model, the utility model will be described in detail through specific embodiments.

[0038] Reference Figures 1-2 As shown in the figure, the utility model discloses a rear frame structure of electric loader, including tail box 1 and front structure 4;

[0039] Tail box 1 is the tail of rear frame, and the front structure 4 of rear frame is two relatively independent parts, and the front part and the tail part all have enough strength stiffness, can be respectively machined and then welded into rear frame assembly without needing to machine again (of course, in some cases, the two can also be welded into an integral after machining, have more processing flexibility);

[0040] The upper surface of tail box 1 is provided with installation groove 11, for sinking type installation battery box support 2;

[0041] The center of symmetry of the mounting groove 11 in the left-right direction is provided with a reinforcing plate 12, and the front and rear ends of the reinforcing plate 12 are integrally connected to the front and rear walls of the mounting groove 11.

[0042] By the above scheme, by sinking the mounting groove 11 on the upper surface of the tail box 1, the battery box support 2 of the electric loader can be realized, the space of the counterweight and the beam of the rear frame in the prior art is utilized, and the arrangement space of the battery is significantly increased, so as to increase the arrangement space of the battery, reduce the arrangement height of the battery box support 2, and further reduce the tail height of the machine, solve the serious problem of insufficient rear view of the driver, improve the machine operation efficiency and safety, and reduce the probability of damage of the machine tail due to collision, and since the batteries are arranged in the tail of the machine, a counterweight does not need to be increased or only a smaller and lighter counterweight is needed to realize a smaller overall weight under the condition of equivalent performance, thereby saving the manufacturing cost and operation cost; since more batteries (increased from 8 to 10) can be arranged, the continuous operation time of the machine can be greatly prolonged, the application range of the machine is expanded, and the product competitiveness is improved; by the reinforcing plate arranged in the mounting groove 11, the strength of the tail box 1 can be strengthened, so that the tail box 1 can not only bear the weight of the battery a and the support, but also bear a larger traction force; the tail box 1 is only the rear half of the rear frame, can be machined separately with the front structure 4 of the rear frame and then welded into a rear frame assembly, does not produce large deformation, does not need post-weld machining, and such a structure does not need large machining equipment, and the production rhythm can also be accelerated by machining the front and rear parts separately.

[0043] The specific embodiments of the utility model are shown below.

[0044] The front structure 4 integrates the mounting structure of the electrical system, the transmission system, the hydraulic system, the brake system, the cab and other systems of the electric loader.

[0045] The front wall of the mounting groove 11 is provided with a protruding part 13, the front of the tail box 1 is extended forward to form a protruding structure integrally formed with the tail box 1, so that the tail box 1 can be arranged integrally forward, more close to the rear axle tire, reduce the rear suspension length of the machine and the length of the rear frame, also reduce the overall length size of the product, at the same time, the tail departure angle of the product can be increased and the rear view of the driver can be further improved; the front end of the reinforcing plate 12 is integrally connected to the inner wall of the protruding part 13; in addition, when the tail box 1 and the front structure 4 are welded into one body, the strength and rigidity between the tail box 1 and the front structure 4 can be ensured through the protruding part 13, and at the same time, the tail box 1 can bear the required traction force.

[0046] The mounting groove 11 is provided with a plurality of support portions of the upper and lower battery supports, and the support portions of the upper and lower battery supports are staggered with each other in a horizontal projection plane.

[0047] The left and right walls of the mounting groove 11 are each provided with an installation and maintenance opening 14, which facilitates installation and maintenance of the battery pipeline.

[0048] The rear wall of the mounting groove 11 is provided with a rear beam 16, the two ends of the rear beam 16 are integrally connected to the left and right walls of the mounting groove 11, and a traction pin 17 is arranged in the rear beam 16.

[0049] The utility model also includes a battery box support 2, and the battery box support 2 is divided into upper and lower two layers. Figures 3-9 The first support 21 and the second support 22 are arranged in the mounting groove 11 of the tail box body 1, and one battery a is arranged in each of the first support 21 and the second support 22. The third support 23 and the fourth support 24 are arranged above the first support 21, and two batteries a are arranged in each of the third support 23 and the fourth support 24. The arrangement scheme can greatly prolong the continuous operation time of the machine, increase the use range of the machine, and improve the competitiveness of the product.

[0050] In some embodiments of the battery box support 2, the batteries a in the first support 21 and the second support 22 are arranged along the transverse direction of the rear frame, and the batteries a in the third support 23 and the fourth support 24 are arranged along the longitudinal direction of the rear frame.

[0051] In some embodiments of the battery box support 2, the battery connection terminals in the first support 21 and the second support 22 of the lower layer of the battery box support are arranged on the left and right sides (the outer sides) of the machine, and the battery connection terminals and the pipe connection terminals in the third support 23, the fourth support 24 and the fifth support 25 (see below) of the upper layer of the battery box support are arranged on the rear side of the machine, which facilitates the installation and maintenance of the batteries.

[0052] In some embodiments of the battery box support 2, the front and rear faces of the first support 21 are each provided with a pair of first locking feet 211; the front face of the third support 23 is provided with a pair of second locking feet 231, and the left and right faces are each provided with a third locking foot 232; the first locking feet 211, the second locking feet 231 and the third locking feet 232 are staggered with each other in the horizontal projection plane of the rear frame, and are locked on the tail box 1, facilitating installation. In this embodiment, the distance between the pair of first locking feet 211 on the front face of the first support 21 is smaller than the distance between the pair of first locking feet 211 on the rear face; the distance between the second locking feet 231 of the third support 23 is smaller than the distance between the third locking feet 232. In this embodiment, the first locking feet 211, the second locking feet 231 and the third locking feet 232 are all plate members with a U-shaped cross section, which are integrally formed on the side faces of the corresponding supports by welding, thereby ensuring the strength and rigidity of the locking feet.

[0053] Further, the rear wall of the mounting groove 11 is provided with a rear beam 16, the front side of the rear beam 16 is provided with two rear upper support portions 161, the front wall of the mounting groove 11 is provided with a front beam 18, the front beam 18 is provided with two front upper support portions 181 and four front lower support portions 182, the upper part of the rear part of the mounting groove 11 is provided with a support beam 19, the support beam 19 is provided with four rear lower support portions 191; the first locking feet 211 on the front and rear faces of the first support 21 are locked on the front lower support portions 182 and the rear lower support portions 191 respectively by threaded connections; the second locking feet 231 of the third support 23 are locked on the front upper support portions 181 by threaded connections, and the third locking feet 232 are locked on the rear upper support portions 161 by threaded connections; the second support 22 is locked below the first support 21 by a threaded connection; the fourth support 24 is locked above the third support 23 by a threaded connection.

[0054] Secondly, the first locking feet 211, the second locking feet 231 and the third locking feet 232 are each provided with a shock-absorbing pad 3 between the corresponding support portions, for buffering the vibration generated during machine operation.

[0055] At the same time, the front and rear walls inside the third support 23 are connected by a first connecting plate 233, which divides the third support 23 into two groove-shaped structures for mounting the batteries a, and the first steel pipe 234 is connected between the third locking feet 232, which is integrally connected with the first connecting plate 233, achieving reinforcement of the third support 23 and meeting the installation requirements of the batteries a; similarly, the front and rear walls inside the fourth support 24 are connected by a second connecting plate 241, which divides the fourth support 24 into two groove-shaped structures for mounting the batteries a.

[0056] In addition, the battery box support 2 further comprises a fifth support 25 stacked above the fourth support 24, the height of the fifth support 25 is lower than that of the fourth support 24, and a third connecting plate 251 is connected between the front and rear walls inside the fifth support 25, the third connecting plate 251 divides the fifth support 25 into two slot-shaped structures for mounting batteries a to achieve parallel mounting of two batteries a. The height of the fifth support 25 is relatively low, which can avoid increasing the tail height of the bonnet as much as possible while increasing the number of batteries a of the machine, greatly improving the situation that the rear view is blocked; after adding the fifth support 25, the machine can arrange more batteries (from 8 to 10), which can greatly prolong the continuous operation time of the machine, expand the application range of the machine, and improve the product competitiveness; in addition, when the number of batteries to be configured is small (such as only 8), the fourth support 24 can also not be arranged, and the fifth support 25 is directly locked on the third support 23, that is, the fifth support 25 with a lower height is used to further reduce the height of the tail of the machine.

[0057] Finally, the bottom walls inside the first support 21, the second support 22, the third support 23, the fourth support 24 and the fifth support 25 are respectively provided with a plurality of weight reduction holes 212, 221, 235, 242 and 252, which can reduce the weight of each support; the side walls of each support are respectively provided with a plurality of maintenance windows 213, 222, 236 and 243 except the fifth support 25, which can be used for battery installation and maintenance.

[0058] In the embodiment, the shapes and structures of the supports are as follows:

[0059] (1) The first support 21 mainly comprises a bottom plate, two U-shaped plates, an outer side reinforcing plate, a bottom plate reinforcing rib and four support structures (i.e. four first locking feet 211), etc., and can accommodate one battery. The bottom plate and the two U-shaped plates have bending structures, such a welding structure has sufficient strength and rigidity, can meet the installation requirements of the battery, and has fewer welds, which can reduce the processing cost and welding deformation. The outer side reinforcing plate has a larger space on one side for the layout of the power battery circuit and pipeline. The bottom plate has two larger weight reduction holes to reduce the weight of the support, and the two side U-shaped plates each have three holes for mounting bolts and maintenance.

[0060] (2) The second support 22 mainly comprises a bottom plate, two L-shaped plates, an outer side reinforcing plate and a bottom plate reinforcing rib, etc., and can accommodate one battery. The bottom plate and the two L-shaped plates have bending structures, such a welding structure has sufficient strength and rigidity, can meet the installation requirements of the battery, and has fewer welds, which can reduce the processing cost and welding deformation. The outer side reinforcing plate has a larger space on one side for the layout of the power battery circuit and pipeline. The bottom plate has two larger weight reduction holes to reduce the weight of the support, and the two L-shaped plates each have three holes for mounting bolts and maintenance.

[0061] (3) The third bracket 23 is mainly composed of a bottom plate, two side U-shaped plates, a first connecting plate 233, a steel pipe, a bottom plate reinforcing rib and four support structures (i.e. second locking feet 231 and 232). The bottom plate and the side U-shaped plates each have two bends, the first connecting plate 233 separates the third bracket into two parts for mounting two batteries, the steel pipe connects the two second locking feet 232 together and connects with the first connecting plate 233. Such a welding structure has sufficient strength and rigidity, can meet the installation requirements of the batteries, and has fewer welds, which can reduce processing costs and welding deformation. The rear side of the third bracket 23 leaves a relatively large space for the layout of the battery lines and pipelines. The bottom plate has four larger weight-reducing holes to reduce the weight of the bracket, and each of the two side U-shaped plates has three holes for mounting bolts and maintenance and repair.

[0062] (4) The fourth bracket 24 is mainly composed of a bottom plate, two side U-shaped plates, a second connecting plate 241, a rear U-shaped plate and a bottom plate reinforcing rib. The bottom plate, the side U-shaped plates and the rear U-shaped plate each have two bends, the second connecting plate 241 separates the fourth bracket 24 into two parts for mounting two batteries, and the rear U-shaped plate connects the side U-shaped plates together and connects with the second connecting plate 241. Such a welding structure has sufficient strength and rigidity, can meet the installation requirements of the batteries, and has fewer welds, which can reduce processing costs and welding deformation. The rear side of the fourth bracket 24 leaves a relatively large space for the layout of the battery lines and pipelines. The bottom plate has four larger weight-reducing holes to reduce the weight of the bracket, and the two U-shaped plates and the rear U-shaped plate have holes for mounting bolts and maintenance and repair.

[0063] (5) The fifth bracket 25 is mainly composed of a bottom plate, two side U-shaped plates, an intermediate reinforcing plate, a steel pipe and a bottom plate reinforcing rib. The bottom plate and the side U-shaped plates each have two bends, the intermediate reinforcing plate separates the bracket into two parts for mounting two batteries, and the steel pipe connects the side U-shaped plates together and connects with the intermediate reinforcing plate. Such a welding structure has sufficient strength and rigidity, can meet the installation requirements of the batteries, and has fewer welds, which can reduce processing costs and welding deformation. The rear side of the bracket leaves a relatively large space for the layout of the battery lines and pipelines. The bottom plate has four larger weight-reducing holes to reduce the weight of the bracket, and the two side U-shaped plates have holes for mounting bolts and maintenance and repair. In addition, the fifth bracket 25 has a smaller height, which is beneficial to further reduce the height of the machine tail and improve the rear view.

[0064] The above embodiments and drawings do not limit the product form and style of the utility model, and any appropriate changes or modifications made by ordinary technical personnel in the technical field shall be considered as not departing from the patent scope of the utility model.

Claims

1. A rear frame structure of an electric loader, characterized by: Including the tail box; The upper surface of the tail box is provided with a mounting groove for sunken installation of the battery box bracket; A reinforcing plate is provided at the symmetrical center of the installation slot in the left and right directions, and the front and rear ends of the reinforcing plate are integrally connected to the front and rear walls of the installation slot; A protrusion is provided on the front wall of the installation groove, and the front end of the reinforcement plate is integrally connected to the inner wall of the protrusion.

2. The rear frame structure of the electric loader according to claim 1, characterized in that: The mounting groove is provided with several support parts of the upper and lower battery brackets, and the support parts of the upper and lower battery brackets are staggered with each other on the horizontal projection plane; among the support parts of each layer of battery brackets, the spacing between the front support parts is smaller than the spacing between the rear support parts.

3. The rear frame structure of the electric loader according to claim 1, characterized in that: The left and right walls of the installation groove are each provided with an installation inspection port, and the installation inspection port is provided with a movable cover that can be opened and closed.

4. The rear frame structure of the electric loader according to claim 1, characterized in that: A rear beam is provided on the top of the rear wall of the installation groove, and both ends of the rear beam are integrally connected to the left and right walls of the installation groove, and a traction pin is provided therein.

5. The rear frame structure of the electric loader according to claim 1, characterized in that: It also includes a battery box bracket; the battery box bracket is divided into two layers, the lower layer includes two groups of first and second brackets stacked up and down, which are symmetrically arranged on the left and right; the upper layer includes a third bracket arranged above the first bracket and a fourth bracket stacked above the third bracket; the first bracket and the second bracket are both located in the mounting groove of the tail box body, and a battery is installed in each of the first bracket and the second bracket; two batteries are installed in parallel in each of the third bracket and the fourth bracket; the direction of the batteries installed on the upper layer is perpendicular to the direction of the batteries installed on the lower layer.

6. The rear frame structure of the electric loader according to claim 5, characterized in that: The batteries in the first bracket and the second bracket are both arranged along the transverse direction of the rear frame, and the batteries in the third bracket and the fourth bracket are both arranged along the longitudinal direction of the rear frame.

7. The rear frame structure of the electric loader according to claim 5, characterized in that: The battery terminals in the first bracket and the second bracket are both located on the left and right sides of the machine; the battery terminals and the pipe terminals in the third bracket and the fourth bracket are both located on the rear side of the machine.

8. The rear frame structure of the electric loader according to claim 5, characterized in that: A pair of first locking feet are provided on the front and rear sides of the first bracket; a pair of second locking feet are provided on the front side of the third bracket, and a third locking foot is provided on each of the left and right sides; the first locking feet, the second locking feet and the third locking feet are staggered with each other on the horizontal projection plane of the rear frame, and are all locked to the tail box; the spacing between the pair of first locking feet in the front side of the first bracket is smaller than the spacing between the pair of first locking feet in the rear side; the spacing between the second locking feet of the third bracket is smaller than the spacing between the third locking feet.

9. The rear frame structure of the electric loader according to claim 8, characterized in that: A rear beam is provided at the top of the rear wall of the mounting slot, two rear upper support parts are provided on the front side of the rear beam, a front beam is provided at the top of the front wall of the mounting slot, two front upper support parts and four front lower support parts are provided on the front beam, a support beam is provided above the rear part of the mounting slot, and four rear lower support parts are provided on the support beam; the first locking feet at the front and back sides of the first bracket are respectively locked to the front lower support part and the rear lower support part through threaded connectors; the second locking feet of the third bracket are locked to the front upper support part through a threaded connector, and the third locking feet are locked to the rear upper support part through a threaded connector; the second bracket is locked to the bottom of the first bracket through a threaded connector; the fourth bracket is locked to the top of the third bracket through a threaded connector; shock-absorbing pads are provided between the first locking foot, the second locking foot and the third locking foot and the corresponding support parts.

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