CN208297131U - A kind of rear axle box assembly for NVH off-line test platform - Google Patents

Abstract

The utility model discloses a kind of rear axle box assembly for NVH off-line test platform, rear axle box assembly includes the cabinet for being equipped with differential mechanism, the installation via hole passed through for axis with coaxial arrangement corresponding with the output end of differential mechanism on cabinet；Also there is the support tube with installation via hole coaxial arrangement on the outside of cabinet；Rear axle box assembly further includes the support base being correspondingly arranged with support tube, and the support tube of cabinet is installed in rotation on support base by bearing；Device for revolving and driving is installed on one of support tube, cabinet is enable to rotate under the action of device for revolving and driving around the axle center of support tube；Support tube passes through device for revolving and driving.The utility model has the advantages that reasonable in design, to assemble, and can be quickly converted the placement status of rear axle reductor convenient for rear axle reductor, advantageously reduce labor intensity, improve detection efficiency.

Description

A kind of rear axle box assembly for NVH off-line test platform

Technical field

The utility model relates to NVH detection technique fields, in particular to a kind of rear axle box for NVH off-line test platform Body component.

Background technique

NVH is the english abbreviation of noise, vibration and sound vibration roughness (Noise, Vibration, Harshness).It is Global question of automobile manufacture quality is measured, it is experienced as most directly and most surface to user vehicle.Vehicle One of the problem of NVH problem is the major vehicle manufacturing enterprise of international automobile industry and parts enterprises concern.There is statistics to show, Vehicle is to have relationship with the NVH problem of vehicle, and there is nearly 20% R & D Cost consumption in each major company there are about 1/3 failure problems On the NVH for solving the problems, such as vehicle.

Rear axle reductor is the main component of automobile, is responsible for the transmission of power, while also bringing noise to vehicle, is being slowed down In the course of work of device, the exception of any one component can all lead to retarder operation irregularity, make an uproar so as to cause retarder generation Sound, for retarder manufacturing enterprise, carrying out NVH off-line test to retarder is necessary.However, each deceleration The rear axle reductor model of device manufacturing enterprise production is various, and the installation dimension of the rear axle reductor of different model is also different, Therefore, the rear axle reductor for how making NVH off-line test platform be suitable for different model becomes urgent problem to be solved.

For this purpose, inventor devises a kind of NVH off-line test platform of rear axle reductor, including with retarder phase to be tested The rear axle box assembly matched, the rear axle box assembly have differential mechanism parameter matched with retarder real vehicle to be tested consistent Differential mechanism, the rear axle box assembly be located at the input terminal of the differential mechanism side be for installing differential mechanism to be tested Side is installed, when being mounted on retarder to be tested on the installation side, the output shaft of retarder to be tested and the differential mechanism Input terminal is coaxially connected；It further include the input terminal for being connected to retarder to be tested and the drive system for simulating real vehicle driving force The loading system for being connected to the output end of the differential mechanism with two and simulating real vehicle loading condition；

However, rear axle reductor on assembly line be in upright state, i.e., input shaft end upward, and carry out NVH detection When, it is desirable that rear axle reductor is in horizontality, i.e. input shaft end is horizontally disposed, if rear axle reductor is removed from assembly line Afterwards, by manually carrying out overturning assembly, it will increase the labor intensity of worker, reduce detection efficiency.

Utility model content

In view of the above shortcomings of the prior art, the technical problem to be solved by the utility model is to how to provide a kind of knot Structure design rationally, assembles, and can be quickly converted the placement status of rear axle reductor convenient for rear axle reductor, advantageously reduces labor Fatigue resistance improves the rear axle box assembly for NVH off-line test platform of detection efficiency.

In order to solve the above-mentioned technical problem, the utility model uses the following technical solution:

A kind of rear axle box assembly for NVH off-line test platform, the rear axle box assembly have and deceleration to be tested The consistent differential mechanism of the matched differential mechanism parameter of device real vehicle, the rear axle box assembly are located at the input terminal of the differential mechanism Side is the installation side for installing differential mechanism to be tested, to be tested when being mounted on retarder to be tested on the installation side The output shaft of retarder and the input terminal of the differential mechanism are coaxially connected；It is characterized in that, the rear axle box assembly includes peace Cabinet equipped with the differential mechanism, on the cabinet with it is corresponding with the output end of the differential mechanism be coaxially disposed being passed through for axis Installation via hole；Also there is the support tube with the installation via hole coaxial arrangement on the outside of the cabinet；The rear axle cabinet Component further includes the support base being correspondingly arranged with the support tube, and the support tube of the cabinet is installed in rotation on by bearing On the support base；Device for revolving and driving is installed on one of them described support tube, enables the cabinet in the revolution It is rotated under the action of driving device around the axle center of the support tube；The support tube passes through the device for revolving and driving.

In this way, cabinet can be rotated to the retarder state adapted on assembly line using device for revolving and driving, convenient for subtracting The installation of fast device.And the retarder after installing can rotate together with horizontality with cabinet, be convenient for retarder and drive system Connection improves the efficiency of assembly and detection in this manner it is possible to reduce the labor intensity of worker.Support tube is filled across revolution driving It sets, convenient for the output end and loading system axis connection of differential mechanism.

Further, the rear axle box assembly further includes the lock plate being mounted on another described support tube, and The outer ledge of the disc brake being mounted on support base, the lock plate is located in the breaker slot of the disc brake.

In this way, can lock cabinet by disc brake locking lock plate, be conducive to improve rear axle cabinet group The rigidity of part reduces the self-excited oscillation of rear axle box assembly in the detection process, improves the accuracy of detection structure.

Further, the disc brake along the lock plate circumferential setting there are three.

In this way, locking power can be made more uniform, locking is more steady.

Further, the device for revolving and driving includes turbine and worm decelerator, and the support tube is mounted on the snail On the output end of worm and gear deceleration mechanism, the input terminal of the turbine and worm decelerator connects servo motor.

Further, the top and bottom of the cabinet are each provided with two hold-down mechanisms, and the hold-down mechanism includes edge The corner oil cylinder of the input axis direction setting of the differential mechanism, the end of the corner oil cylinder have vertically disposed pressing plate, make The pressing plate can compress retarder to be tested when turning to the middle part of the cabinet.

Further, each hold-down mechanism includes two corner oil cylinders,

In conclusion the utility model has reasonable in design, assembles, and can be quickly converted convenient for rear axle reductor The advantages that placement status of rear axle reductor advantageously reduces labor intensity, improves detection efficiency.

Detailed description of the invention

Fig. 1 is a kind of structural schematic diagram of the NVH off-line test platform of rear axle reductor.

Fig. 2 is the structural schematic diagram of rear axle box assembly in Fig. 1.

Fig. 3 is the structural schematic diagram of drive system in Fig. 1.

Fig. 4 is the structural schematic diagram of loading system in Fig. 1.

Fig. 5 is the structural schematic diagram for loading splined shaft.

Fig. 6 is the structural schematic diagram of annular retaining ring.

Specific embodiment

Below with reference to embodiment, the utility model is described in further detail.

When specific implementation: as shown in Fig. 1 ~ Fig. 6, a kind of NVH off-line test platform of rear axle reductor, including subtract with to be tested The rear axle box assembly 1 that fast device matches, the rear axle box assembly 1 have differential mechanism matched with retarder real vehicle to be tested The consistent differential mechanism of parameter, the rear axle box assembly 1 be located at the input terminal of the differential mechanism side be for install to Test differential mechanism installation side, when being mounted on retarder to be tested on the installation side, the output shaft of retarder to be tested and The input terminal of the differential mechanism is coaxially connected；Further include the input terminal for being connected to retarder to be tested and simulates real vehicle driving The drive system 2 of power and two are connected to the output end of the differential mechanism and simulate the loading system 3 of real vehicle loading condition； The drive system 2 includes the driving end stand frame 21 of side where the input terminal of the differential mechanism is arranged in, and along the differential The input terminal of device is axially mounted to the driving assembly 22 on the driving end stand frame 21, and the output end of the driving component 22 can It is coaxially connected with the input terminal of retarder to be tested；The loading system 3 includes being arranged in where the output end of the differential mechanism The loading end rack 31 of side, and the load group on the loading end rack 31 is axially mounted to along the output end of the differential mechanism The output end of part 32, the output end and the differential mechanism of the charging assembly 32 is coaxially connected；The driving end stand frame 21 includes Driving end pedestal 211, lifter plate 212, horizontal slide plate 213 and the driving bottom plate 214 set gradually from bottom to top；The lifter plate 212 are liftably mounted on driving end pedestal 211 by elevating mechanism 215, the lower surface of the horizontal slide plate 213 and It is provided with first straight line sliding equipment 216 between the lifter plate 212, enables the horizontal slide plate 213 along perpendicular to described The input axis direction of differential mechanism is moved horizontally relative to the lifter plate 212；The lower surface of the driving bottom plate 214 and the water It is provided with second straight line sliding equipment 217 between flat runner 213, enables the driving bottom plate 214 along the defeated of the differential mechanism Enter axis direction to move horizontally relative to horizontal slide plate 213；The loading end rack 31 includes the load set gradually from bottom to top Pedestal 311 and load bottom plate 312 are held, is provided between the lower surface and the loading end pedestal 311 of the load bottom plate 312 straight Line mobile mechanism 313 enables the load bottom plate 312 along the output axis direction of the differential mechanism relative to the loading end bottom Seat 311 moves horizontally.

Using the above structure, when detection, retarder to be tested is mounted on rear axle box assembly, is then subtracted to be tested The input terminal of the fast device and output end of driving assembly is coaxially connected to be tested.And for the retarder of different model, only Rear axle box assembly is needed replacing, is adapted its installation dimension with retarder and its differential mechanism parameter and deceleration to be tested The matched differential mechanism parameter of device real vehicle is consistent.For matching the rear axle box assembly of different model retarder, differential mechanism Two output end spacing can change, but due to load bottom plate can be under the action of linear moving mechanism along differential mechanism Output axis direction is moved horizontally with respect to loading end pedestal, enables the charging assembly being mounted on loading end rack with load bottom Plate is moved along the output axis direction of differential mechanism, to adapt to the size of the corresponding rear axle box assembly of different model retarder.And To the change in location of the input terminal of the retarder of different model, elevating mechanism, first straight line sliding equipment and second can be passed through Linear slide mechanism is adjusted respectively, and the output end of driving assembly and the input terminal of retarder to be tested are coaxially connected It connects.In this way, enabling monitor station to be suitable for the various sizes of rear axle speed-reducing of different model by the structure of above-mentioned rational design Device.

When implementation, load bottom plate lockable mechanism is additionally provided between the load bottom plate 312 and the loading end pedestal 311 314, the load bottom plate lockable mechanism 314 includes the load locking plate being vertically mounted on the load bottom plate 312 and installation Disc brake on the loading end pedestal 311, the load locking plate are set along the moving direction of the load bottom plate 312 It sets, and lower end extends in the breaker slot of the butterfly brake.

Using the above structure, so that it may load locking plate be held tightly by disc brake, make to load bottom plate relative to load End pedestal is fixed, and is conducive to the overall stiffness for increasing loading end rack, is avoided in detection process, loading end rack itself generates vibration It is dynamic to influence testing result, be conducive to the accuracy for improving testing result.

When implementation, the linear moving mechanism 313 includes that two parallel and face is arranged on the loading end pedestal 311 The linear movement guide rail on surface, and the linear movement sliding block being slidably fit on the linear movement guide rail, it is described to add Load floor 312 is fixedly mounted on the linear movement sliding block.

When implementation, it is additionally provided with straight line driving mechanism between the load bottom plate 312 and the loading end pedestal 311, institute Stating straight line driving mechanism includes along the linear movement screw rod of the moving direction setting of the load bottom plate 312 and cooperation described Rotationally pacified by bearing spider at the both ends of the linear movement feed screw nut to move linearly on screw rod, the linear movement screw rod Mounted in the loading end pedestal 311, and one end is coaxially connected with linear movement driving motor；The load bottom plate 312 with it is described Linear movement feed screw nut is fixedly connected.

In this way, can use linear movement driving motor drives linear movement screw rod rotation, it, will be straight using feed screw nut pair The rotary motion of the mobile screw rod of line is converted into the linear motion of linear movement feed screw nut, to control the movement of load bottom plate. When due to linear movement screw rod one circle of rotation, the linear movement distance for the feed screw nut that moves linearly is leading for linear movement screw rod Journey, in this manner it is possible to which the moving distance of adjustment load bottom plate, adjustment is more by the rotational angle of control linear movement screw rod It is convenient accurate.

When implementation, there are four the settings of load bottom plate lockable mechanism 314, is located at the four of the load bottom plate 312 At angle.

When implementation, the charging assembly 32 includes the loading motor 321 being mounted on the load bottom plate 312 and loading axis Seat 322 is held, the middle part of the load bearings seat 322 has rotatable load connecting shaft, and the shaft end of the loading motor 321 is logical It crosses shaft coupling and the load connecting shaft is coaxially connected；The other end of the load connecting shaft is by load bindiny mechanism 4 with after The output end of bridge box assembly 1 is connected.

When implementation, the load bindiny mechanism 4 includes the load flower being coaxially mounted on the load connecting shaft other end Key set 41, it is described to load the load splined shaft 42 being fitted on spline housing 41 for connecting rear axle box assembly 1, the load flower One end of key axis 42 has the external splines to match with the internal spline of the load spline housing 41, and the other end has and rear axle cabinet The external splines that the internal spline of the output end of component matches.

When implementation, one end that the load spline housing 41 is connected with load connecting shaft, which all has, extends radially outward shape At ring flange, and be bolted to connection.

When implementation, the load splined shaft 42 includes main shaft 421, and one end of the main shaft 421 has to be added with described The external splines that the internal spline of spline housing 41 matches is carried, the other end is the lesser Step Shaft of diameter, and the end of the Step Shaft has External splines；Slideably be set with spline connecting sleeve 422 on the external splines of the Step Shaft, the spline connecting sleeve 422 it is interior There is the internal spline to match with the external splines of the Step Shaft on hole, have on the outer wall of the spline connecting sleeve 422 with it is rear The external splines that the internal spline of the output end of bridge box assembly matches；Reset spring is further sleeved on the Step Shaft (in figure not Show), the both ends of the reset spring are connected to the step surface and the spline connecting sleeve 422 of the main shaft 421 respectively End, and the reset spring in its natural state when, the outer end of the spline connecting sleeve 422 and the end of the Step Shaft are neat It is flat.

In this way, in the output end of connection load splined shaft and rear axle box assembly, even if the external splines of spline connecting sleeve It is not aligned with the internal spline of the output end of rear axle box assembly, only will cause spline connecting sleeve compression reseting spring, once spline Connector sleeve rotation, so that it may under the thrust of reset spring, spline connecting sleeve be squeezed into rear axle box assembly output end In internal spline, connection is completed.

When implementation, the end of the Step Shaft also has coaxial mounted circular baffle plate, and the diameter of the circular baffle plate is big In the minimum diameter of the spline connecting sleeve 422, and it is less than the minimum diameter of the external splines of the spline connecting sleeve 422.

In this way, can not only prevent spline connecting sleeve from falling off from Step Shaft, but also after spline connecting sleeve can be made smoothly to be inserted into In the internal spline of the output end of bridge box assembly, spline connection transmission is realized.

When implementation, there is the annular groove of coaxial arrangement, the annular groove on the outer end face of the spline connecting sleeve 422 Side radially inward and the inner hole of the spline connecting sleeve 422 connect, the depth of the annular groove and the circle The consistency of thickness of baffle, and diameter is consistent with the diameter of the circular baffle plate.

When implementation, the end of Step Shaft tool has in the circular baffle plate there are two axially disposed threaded hole Two bolts hole being correspondingly arranged with the threaded hole, the circular baffle plate are fixed on institute by passing through the bolt of the bolt hole It states on the threaded hole of Step Shaft.

Since the end of Step Shaft has there are two threaded hole, so that at least one threaded hole can be in the position of disalignment It sets.In this way, in the rotation process of load connecting shaft, so that it may the phenomenon that preventing two bolts from all loosening, be conducive to Improve the reliability of connection.

When implementation, the axial connecting line of two threaded holes intersects with the axis of the Step Shaft, and the two is to described The axis of rank axis is equidistant.

In this way, not only having facilitated manufacture, but also facilitate installation.

When implementation, the one end of the external splines of the spline connecting sleeve 422 outwardly has 45 ° ~ 60 ° of chamfering.

In this way, spline connecting sleeve can be made better centering and to be inserted into internal spline during rotation using chamfering.

When implementation, the main shaft 421 also has the ring of coaxial arrangement on the periphery of one end of the Step Shaft Shape limiting slot, and the external splines at the end extends to the annular spacing groove, the minimum diameter of the annular spacing groove is less than the end The minimum diameter of external splines；It is set with annular retaining ring on the annular spacing groove, has and this on the inner hole of the annular retaining ring The internal spline that the external splines at end matches, so that the internal spline of the annular retaining ring turns to position corresponding with the external splines at the end When setting, the annular retaining ring can be removed from the main shaft 421；The annular retaining ring is bolted on the load On spline housing 41, and in the assembled condition, the internal spline mutual dislocation of the two.

When implementation, the elevating mechanism 215 includes vertically-guided mechanism and lift drive mechanism, the vertically-guided mechanism Guide post including being vertically mounted on 212 lower section of lifter plate, and the linear axis being mounted on the driving end pedestal 211 It holds, the lower end of the guide post is slidably disposed through the linear bearing, and the distance of the linear bearing to ground is greater than described The length of guide post；The lift drive mechanism includes the worm type of reduction gearing being mounted on the driving end pedestal 211, institute The output end for stating worm type of reduction gearing is vertically arranged upward and is connected with elevating screw, and institute is run through in the upper end of the elevating screw Lifter plate 211 is stated, there is the elevating screw nut being equipped on the elevating screw, the elevating screw nut is fixedly mounted On the lifter plate 211；The input terminal of the worm type of reduction gearing is connected with lifting driving motor.

When implementation, the vertically-guided mechanism is provided with two column in the width direction of the lifter plate 212, and each column is arranged There are three；There are two the lift drive mechanism is arranged in the length direction of the lifter plate 212.

When implementation, the vertically-guided mechanism further include be mounted on it is vertical hollow pneumatic on the driving end pedestal 211 Chuck, the vertical hollow air spider are co-axially located at the top of the linear bearing, and the guide post passes through described vertical Hollow air spider.

Be conducive to mention to realize the locking of lifter plate in this way, can use vertical hollow air spider and hold guide post tightly Coupling stiffness between high lifter plate and driving end pedestal, the vibration of lifter plate when reducing detection are conducive to the essence for improving detection True property.

When implementation, the first straight line sliding equipment 216 includes first straight line guiding mechanism and the first sliding drive mechanism, The first straight line guiding mechanism includes that three length directions along the lifter plate 212 are disposed side by side on the lifter plate 212 The first straight line slide rail of upper surface, and it is slidably fit into the first straight line sliding of the first straight line slide rail Sliding block, the horizontal slide plate 213 are fixedly mounted on the first straight line sliding slider；First sliding drive mechanism includes Silk is slided in the first straight line with first straight line slide rail first straight line sliding screw disposed in parallel, and cooperation First straight line sliding screw nut on bar, the both ends of the first straight line slide rail are rotatably mounted by bearing spider On the lifter plate 212, and one end is coaxially connected with the first sliding driving motor；The horizontal slide plate 213 and described first Linear slide feed screw nut is fixedly connected.

When implementation, the second straight line sliding equipment 217 includes second straight line guiding mechanism and the second sliding drive mechanism, The second straight line guiding mechanism includes that two width directions along the lifter plate 212 are disposed side by side on the horizontal slide plate The second straight line slide rail of 213 upper surfaces, and it is slidably fit into the second straight line of the second straight line slide rail Sliding slider, the driving bottom plate 214 are fixedly mounted on the second straight line sliding slider；Second sliding drive mechanism Including sliding in the second straight line with second straight line slide rail second straight line sliding screw disposed in parallel, and cooperation The both ends of second straight line sliding screw nut on dynamic screw rod, the second straight line slide rail pass through bearing spider rotationally It is mounted on the horizontal slide plate 213, and two ends are coaxially connected with the second sliding driving motor；The driving bottom plate 214 and institute Second straight line sliding screw nut is stated to be fixedly connected.

When implementation, the driving component 22 includes driving motor 221, the rotary speed torque sensor 222 for being sequentially connected setting With driving bearing block 223, the middle part of the driving bearing block 223 has rotatable drive connection axis, the driving motor 221 Shaft end it is coaxially connected by one end of shaft coupling and the rotary speed torque sensor 222, the rotary speed torque sensor 222 The other end is coaxially connected by shaft coupling and the drive connection axis.

When implementation, the rotary speed torque sensor 222 is the digital torque sensing that T40B has magnetic pole speed measuring system Device.

When implementation, the rear axle box assembly 1 includes the cabinet 11 for being equipped with the differential mechanism, is had on the cabinet 11 The installation via hole of coaxial arrangement corresponding with the output end of the differential mechanism passed through for axis；Also have on the outside of the cabinet 11 With the support tube of the installation via hole coaxial arrangement；The rear axle box assembly 1 further includes being correspondingly arranged with the support tube The support tube of support base, the cabinet 11 is installed in rotation on the support base by bearing.

When implementation, the rear axle box assembly 1 further includes the revolution driving dress being installed therein on a support tube 12 are set, the support tube passes through the device for revolving and driving 12.

When implementation, the rear axle box assembly 1 further includes the lock plate 13 being mounted on another described support tube, and The disc brake being mounted on support base, the outer ledge of the lock plate 13 are located at the breaker slot of the disc brake It is interior.

When implementation, the disc brake along the lock plate 13 circumferential setting there are three.

In this way, locking power can be made more uniform, locking is more steady.

When implementation, the device for revolving and driving 12 includes turbine and worm decelerator, and the support tube is mounted on the snail On the output end of worm and gear deceleration mechanism, the input terminal of the turbine and worm decelerator connects servo motor.

When implementation, the top and bottom of the cabinet 11 are each provided with two hold-down mechanisms 14, and the hold-down mechanism 14 wraps The corner oil cylinder of the input axis direction setting along the differential mechanism is included, the end of the corner oil cylinder has vertically disposed pressure Plate enables the pressing plate to compress retarder to be tested when turning to the middle part of the cabinet 11.

The above is only the preferred embodiment of the utility model only, is not limitation with the utility model, all at this Made any modifications, equivalent replacements, and improvements etc., should be included in the utility model within the spirit and principle of utility model Protection scope within.

Claims (6)

1. a kind of rear axle box assembly for NVH off-line test platform, the rear axle box assembly has and retarder to be tested The consistent differential mechanism of the matched differential mechanism parameter of real vehicle, the rear axle box assembly are located at the one of the input terminal of the differential mechanism Side is the installation side for installing differential mechanism to be tested, to be tested to subtract when being mounted on retarder to be tested on the installation side The output shaft of fast device and the input terminal of the differential mechanism are coaxially connected；It is characterized in that, the rear axle box assembly includes installation Have a cabinet of the differential mechanism, on the cabinet with it is corresponding with the output end of the differential mechanism be coaxially disposed passed through for axis Via hole is installed；Also there is the support tube with the installation via hole coaxial arrangement on the outside of the cabinet；The rear axle cabinet group Part further includes the support base being correspondingly arranged with the support tube, and the support tube of the cabinet is installed in rotation on institute by bearing It states on support base；Device for revolving and driving is installed on one of them described support tube, the cabinet is enable to drive in the revolution It is rotated under the action of dynamic device around the axle center of the support tube；The support tube passes through the device for revolving and driving.

2. being used for the rear axle box assembly of NVH off-line test platform as described in claim 1, which is characterized in that the rear axle box Body component (1) further includes the lock plate (13) being mounted on another described support tube, and the dish-style being mounted on support base The outer ledge of brake, the lock plate (13) is located in the breaker slot of the disc brake.

3. being used for the rear axle box assembly of NVH off-line test platform as claimed in claim 2, which is characterized in that the dish-style system Dynamic device along the lock plate (13) circumferential setting there are three.

4. being used for the rear axle box assembly of NVH off-line test platform as described in claim 1, which is characterized in that the revolution is driven Dynamic device (12) include turbine and worm decelerator, and the support tube is mounted on the output end of the turbine and worm decelerator On, the input terminal of the turbine and worm decelerator connects servo motor.

5. being used for the rear axle box assembly of NVH off-line test platform as described in claim 1, which is characterized in that the cabinet (11) top and bottom are each provided with two hold-down mechanisms (14), and the hold-down mechanism (14) includes along the defeated of the differential mechanism Enter the corner oil cylinder of axis direction setting, the end of the corner oil cylinder has vertically disposed pressing plate, the pressing plate is made to turn to institute Retarder to be tested can be compressed when stating the middle part of cabinet (11).

6. being used for the rear axle box assembly of NVH off-line test platform as claimed in claim 5, which is characterized in that each pressure Tight mechanism (14) includes two corner oil cylinders.