阅读说明：本技术 一种智慧城市用无人机 (Unmanned aerial vehicle is used in wisdom city ) 是由 庄艺松 于 2020-12-24 设计创作，主要内容包括：本发明公开了一种智慧城市用无人机,其结构包括：无人机体、扇叶、推动脚架、稳降装置,稳降装置设在无人机体的底部,推动脚架卡合在无人机体底部和稳降装置上,无人机体内设有卡合槽和滑动电阻,稳降装置由滑块、顶块、弹簧、限位块,滑块和顶块分设在卡合槽内的两侧,顶块与滑动电阻相卡合,本发明通过将无人机的推动脚架与稳降装置相配合,并使稳降装置与无人机体内的滑动电阻相连接,从而使得无人机体下降时,通过推动脚架接触到底面来带动稳降装置工作,将滑动电阻向内推动,从而使无人机体电路阻值随着无人机体的下降而增大,从而随着无人机体的下降而降低无人机体扇叶的转速直至停止,防止断电下落时造成无人机体碰撞损坏。(The invention discloses an unmanned aerial vehicle for a smart city, which structurally comprises: the invention relates to an unmanned aerial vehicle, which comprises an unmanned aerial vehicle body, fan blades, a pushing foot rest and a stable descending device, wherein the stable descending device is arranged at the bottom of the unmanned aerial vehicle body, the pushing foot rest is clamped on the bottom of the unmanned aerial vehicle body and the stable descending device, a clamping groove and a sliding resistor are arranged in the unmanned aerial vehicle body, the stable descending device comprises a sliding block, a top block, a spring and a limiting block, the sliding block and the top block are respectively arranged at two sides in the clamping groove, and the top block is clamped with the sliding resistor, so that when the unmanned aerial vehicle descends, the stable descending device is driven to work by pushing the foot rest to contact the bottom surface, the sliding resistor is pushed inwards, thereby make unmanned aerial vehicle body circuit resistance increase along with the decline of unmanned aerial vehicle body to reduce the rotational speed of unmanned aerial vehicle body flabellum until stopping along with the decline of unmanned aerial vehicle body, cause unmanned aerial vehicle body collision damage when preventing to cut off the power supply whereabouts.)

1. The utility model provides an unmanned aerial vehicle is used in wisdom city, its structure includes: unmanned aerial vehicle body (1), flabellum (2), promotion foot rest (3), steady decline device (4), its characterized in that:

the unmanned aerial vehicle is characterized in that a power supply and a main control board are arranged in the unmanned aerial vehicle body (1), fan blades (2) are arranged on a motor arranged at an octagonal position of the unmanned aerial vehicle body (1), the stabilizing and descending device (4) is arranged at the bottom of the unmanned aerial vehicle body (1), the pushing foot rest (3) is clamped at the bottom of the unmanned aerial vehicle body (1) and the stabilizing and descending device (4), a clamping groove (11) and a sliding resistor (12) are arranged in the unmanned aerial vehicle body (1), the clamping groove (11) is arranged at four corners of the unmanned aerial vehicle body (1), and the sliding resistor (12) is arranged on the right side inside the clamping groove (11);

steadily fall device (4) by slider (41), kicking block (42), spring (43), stopper (44), slider (41) and kicking block (42) are divided and are established the both sides in block groove (11), kicking block (42) and sliding resistance (12) looks block, spring (43) support between block groove (11) inner wall and kicking block (42), stopper (44) are established in block groove (11).

2. The unmanned aerial vehicle for smart city according to claim 1, wherein: slider (41) inboard is equipped with driving pin (411), kicking block (42) are equipped with trapezoidal round pin (421), push away spring (422), chuck (423), trapezoidal round pin (421) block is in kicking block (42), push away spring (422) and support between terminal and kicking block (42) inner wall, chuck (423) and sliding resistance (12) block mutually, trapezoidal round pin (421) outside working face is inclined plane and the directional stopper (44) of inclined plane, driving pin (411) offsets with the back of trapezoidal round pin (421) working face.

3. The unmanned aerial vehicle for smart city according to claim 1, wherein: the push foot rest (3) is composed of a fixing frame (31), a sliding sleeve (32), a frame rod (33), a bottom frame (34) and an elastic sleeve (35), the fixing frame (31) is fixed at the bottom of the unmanned aerial vehicle body (1), the sliding sleeve (32) is rotatably embedded at the tail end of the fixing frame (31), the frame rod (33) is cylindrical, the upper section of the frame rod (33) is thin, the lower section of the frame rod is thick, the upper section of the frame rod (33) is embedded on the sliding sleeve (32), the top end of the frame rod (33) is connected to a sliding block (41), the lower end of the frame rod (33) is fixed with the bottom frame (34), and the elastic sleeve (35) is embedded between the lower section of the frame.

4. The unmanned aerial vehicle for smart city according to claim 3, wherein: the fixing frame (31), the sliding sleeve (32) and the frame rod (33) are four and are respectively arranged at four corners of the bottom of the unmanned aerial vehicle body (1), the elastic sleeve (35) is composed of a compression bar (351) and a lantern ring (352), the lantern rings (352) are fixed at two ends of the compression bar (351), the compression bar (351) is provided with eight bars and is arranged on the lantern ring (352) in a surrounding mode, and the static state of the compression bar (351) is vertical and is arched towards the outside when being pressed.

5. The unmanned aerial vehicle for smart city according to claim 2, wherein: the top of the limiting block (44) is in an inclined shape matched with the trapezoidal pin (421), a pressing plate (441), a compression pad (442) and a button switch (443) are arranged on the inclined surface of the limiting block (44), the button switch (443) is arranged in the middle of the inclined surface of the limiting block (44), the compression pad (442) is arranged on the inclined surface of the limiting block (44), and the pressing plate (441) is arranged on the compression pad (442) and keeps the same inclination as the inclined surface of the limiting block (44).

6. The unmanned aerial vehicle for smart city according to claim 5, wherein: the unmanned aerial vehicle is characterized in that the stable-descending device (4) is provided with four parts which are respectively arranged at four corners of the bottom of the unmanned aerial vehicle body (1), the sliding resistor (12) of the stable-descending device (4) is connected with a power supply in the unmanned aerial vehicle body (1) in series, the resistance value of the sliding resistor (12) is zero when the sliding resistor (12) is not operated, and the resistance value of the sliding resistor (12) is increased when the switch of the sliding resistor (12) moves towards the direction of the limiting block (44).

7. The unmanned aerial vehicle for smart city according to claim 5, wherein: the button switch (443) is connected with a main control panel in the unmanned aerial vehicle body (1), and the unmanned aerial vehicle body (1) stops running when the button switch (443) at the four corners of the unmanned aerial vehicle body (1) is triggered.

Technical Field

The invention relates to the field of unmanned aerial vehicles, in particular to an unmanned aerial vehicle for a smart city.

Background

The unmanned aerial vehicle is often adopted in the city to take a photo by plane, the urban scenery is shot, collected and spread, and the urban spiritual civilization construction is increased.

Unmanned aerial vehicle's rising and falling generally puts rethread controller control on the plane and takes off, but the flabellum rotation has the cutting danger when descending, unmanned aerial vehicle's descending is generally not directly accepted to the people's hand, the bathroom just lets unmanned aerial vehicle descend subaerially, this flabellum that makes unmanned aerial vehicle when descending will reduce to zero from the minimum power that drives unmanned aerial vehicle flight suddenly, make unmanned aerial vehicle's descending be one kind and fall the form that is close to ground, for a long time, this kind of striking causes the damage to unmanned aerial vehicle's main control board and the equipment of the part of making a video recording easily, cause economic loss and take place unnecessary trouble.

Disclosure of Invention

Aiming at the problems, the invention provides an unmanned aerial vehicle for a smart city.

In order to achieve the purpose, the invention is realized by the following technical scheme: the utility model provides an unmanned aerial vehicle is used in wisdom city, its structure includes: unmanned aerial vehicle body, flabellum, promotion foot rest, steady device that falls, the internal power and main control board that are equipped with of unmanned aerial vehicle, the flabellum is established on the motor that unmanned aerial vehicle body octagon was equipped with, steady device that falls is established in the bottom of unmanned aerial vehicle body, promote the foot rest block on unmanned aerial vehicle body bottom and steady device that falls, the internal block groove and the sliding resistance of being equipped with of unmanned aerial vehicle, the block groove is established in unmanned aerial vehicle body four corners department, sliding resistance establishes on the inside right side of block inslot portion, steady device that falls is by slider, kicking block, spring, stopper, the both sides at the block inslot are established to slider and kicking block branch, kicking block and sliding resistance looks block, the spring supports between block inslot wall and kicking block, the stopper is established at the block inslot.

Preferably, the driving pin is arranged on the inner side of the sliding block, the ejector block is provided with a trapezoidal pin, a push spring and a chuck, the trapezoidal pin is clamped in the ejector block, the push spring is abutted between the tail end and the inner wall of the ejector block, the chuck is clamped with the sliding resistor, the outer working surface of the trapezoidal pin is an inclined surface, the inclined surface points to the limiting block, and the driving pin is abutted against the back of the working surface of the trapezoidal pin.

Preferably, the pushing foot rest comprises a fixed frame, a sliding sleeve, a frame rod, a bottom frame and an elastic sleeve, wherein the fixed frame is fixed at the bottom of the unmanned aerial vehicle body, the sliding sleeve is rotatably embedded at the tail end of the fixed frame, the frame rod is cylindrical, the upper section of the frame rod is thin, the lower section of the frame rod is thick, the upper section of the frame rod is embedded on the sliding sleeve, the top end of the frame rod is connected to the sliding block, the lower end of the frame rod is fixed with the bottom frame, and the elastic sleeve is embedded between the lower section of the frame.

Preferably, the fixing frame, the sliding sleeve and the frame rod are four and are respectively arranged at four corners of the bottom of the unmanned aerial vehicle body, the elastic sleeve is composed of compression strips and lantern rings, the lantern rings are fixed at two ends of each compression strip, eight compression strips are arranged on the lantern rings in a surrounding mode, the compression strips are in a vertical state and arch outwards when being pressed, and therefore the elastic sleeve provides stretched elastic force to stretch the space between the frame rod and the sliding sleeve.

Preferably, the top of the limiting block is in an inclined shape matched with the trapezoidal pin, the inclined surface of the limiting block is provided with a pressing plate, a compression pad and a button switch, the button switch is arranged in the middle of the inclined surface of the limiting block, the compression pad is arranged on the inclined surface of the limiting block, the pressing plate is arranged on the compression pad and keeps the same inclination as the inclined surface of the limiting block, and the trapezoidal pin slides through the clamping of the trapezoidal pin and the limiting block when being driven by the driving pin through the inclined heads of the limiting block and the pressing plate, so that the top block is retracted into the top block under the driving of a spring to rebound, and the sliding resistance is converted from a large resistance value to a zero resistance value for the next use.

Preferably, the four stable descending devices are respectively arranged at four corners of the bottom of the unmanned aerial vehicle body, sliding resistors of the stable descending devices are connected in series with a power supply in the unmanned aerial vehicle body, the resistance value of the sliding resistors is zero when the sliding resistors are not operated, and the resistance value of the sliding resistors is increased when switches of the sliding resistors move towards the direction of the limiting blocks, so that when the unmanned aerial vehicle body descends, the foot rests are pushed to drive the stable descending devices to operate, the sliding resistors are pushed inwards, the resistance value of a circuit of the unmanned aerial vehicle body is increased, the rotating speed of blades driven by a motor of the unmanned aerial vehicle body is reduced, the unmanned aerial vehicle body can descend slowly, and collision and damage of the unmanned aerial vehicle body when the unmanned aerial vehicle body falls in a.

Preferably, the button switches are connected with a main control board in the unmanned aerial vehicle body, the unmanned aerial vehicle body stops running when the button switches at the four corners of the unmanned aerial vehicle body are triggered, the button switches are arranged at the tail end of the stroke of the sliding resistor, and when the sliding resistor circuit resistance value is increased to drive the unmanned aerial vehicle body to stably land, the button switches are triggered to stop running of the unmanned aerial vehicle body, so that power failure after landing is prevented, and the fan blades can hurt a user when the unmanned aerial vehicle body is taken up.

Preferably, the elastic sleeve is made of elastic metal, and provides elastic force through the elastic sleeve so as to stretch the frame rod and the sliding sleeve, and further drive the sliding block to abut against the outer side of the clamping groove to wait for triggering.

Preferably, the stroke length of the sliding resistor switch is greater than the displacement length of the top block, so that the switch of the sliding resistor is prevented from being over-traveled when the top block moves, and damage to the sliding resistor is avoided.

Advantageous effects

Compared with the prior art, the invention has the following beneficial effects:

1. according to the unmanned aerial vehicle, the pushing foot rest of the unmanned aerial vehicle is matched with the additionally arranged stable descending device, and the stable descending device is connected with the sliding resistor in the unmanned aerial vehicle body, so that when the unmanned aerial vehicle body descends, the foot rest is pushed to contact the bottom surface to drive the stable descending device to work, the sliding resistor is pushed inwards, the circuit resistance value of the unmanned aerial vehicle body is increased along with the descending of the unmanned aerial vehicle body, the rotating speed of fan blades of the unmanned aerial vehicle body is reduced along with the descending of the unmanned aerial vehicle body until the fan blades stop, and the unmanned aerial vehicle body is prevented from being damaged by collision when falling in a power failure.

2. According to the invention, through the inclined head parts of the limiting block and the pressing plate, when the trapezoidal pin is driven by the driving pin, the trapezoidal pin can slide through the clamping of the trapezoidal pin and the limiting block and can be contracted into the top block, so that the top block is driven by the spring to rebound, and meanwhile, the sliding resistor is converted from a large resistance value to a zero resistance value, so that the sliding resistor does not need to be independently adjusted when being used next time.

3. According to the unmanned aerial vehicle, the button switch is arranged at the tail end of the stroke of the sliding resistor, the resistance value of the sliding resistor circuit is increased to drive the unmanned aerial vehicle to stably land, when the unmanned aerial vehicle lands until the trapezoidal pin is clamped with the limiting block to slide, the trapezoidal pin triggers the button switch on the limiting block to stop the unmanned aerial vehicle from running, the unmanned aerial vehicle is prevented from being powered off in time after landing, and the fan blades can hurt a user when the unmanned aerial vehicle is taken up.

Drawings

FIG. 1 is a schematic three-dimensional structure of the present invention.

Fig. 2 is a schematic front view of the push foot stand of the present invention.

Fig. 3 is a side view of the pushing foot stool part of the invention.

Fig. 4 is a front structural diagram of the elastic sleeve of the invention.

Fig. 5 is a schematic view of a top-down cut-away structure of the stabilizing device of the present invention.

Fig. 6 is a top sectional view of the top block of the present invention.

Fig. 7 is a schematic side view of the limiting block of the present invention.

In the figure: the device comprises an unmanned aerial vehicle body-1, fan blades-2, a pushing foot stand-3, a steady-falling device-4, a clamping groove-11, a sliding resistor-12, a sliding block-41, a top block-42, a spring-43, a limiting block-44, a driving pin-411, a trapezoidal pin-421, a pushing spring-422, a chuck-423, a fixed frame-31, a sliding sleeve-32, a frame rod-33, a bottom frame-34, an elastic sleeve-35, a compression strip-351, a lantern ring-352, a pressing plate-441, a compression pad-442 and a button switch-443.

Detailed Description

In order to make the technical means, the original characteristics, the achieved purposes and the effects of the invention easy to understand, the following description and the accompanying drawings further illustrate the preferred embodiments of the invention.

Example one

As shown in fig. 1 to 6, the present invention provides an unmanned aerial vehicle for smart city, which comprises: unmanned aerial vehicle body 1, flabellum 2, promotion foot rest 3, steady device 4 that falls, be equipped with power and main control board in the unmanned aerial vehicle body 1, flabellum 2 is established on the motor that unmanned aerial vehicle body 1 eight corners department was equipped with, steady device 4 is established in the bottom of unmanned aerial vehicle body 1, promote the 3 blocks of foot rest on unmanned aerial vehicle body 1 bottom and steady device 4 that falls, be equipped with block groove 11 and sliding resistance 12 in the unmanned aerial vehicle body 1, block groove 11 is established in unmanned aerial vehicle body 1 four corners department, sliding resistance 12 is established on the inside right side in block groove 11, steady device 4 is by slider 41, kicking block 42, spring 43, stopper 44, slider 41 and kicking block 42 divide the both sides of establishing in block groove 11, kicking block 42 and sliding resistance 12 looks block, spring 43 supports between block groove 11 inner wall and kicking block 42, stopper 44 is established in block groove 11.

As shown in fig. 5, a driving pin 411 is provided inside the slider 41, the top block 42 is provided with a trapezoidal pin 421, a push spring 422, and a collet 423, the trapezoidal pin 421 is engaged with the inside of the top block 42, the push spring 422 abuts between the end and the inner wall of the top block 42, the collet 423 is engaged with the sliding resistor 12, the outer working surface of the trapezoidal pin 421 is an inclined surface, the inclined surface points to the stopper 44, and the driving pin 411 abuts against the back of the working surface of the trapezoidal pin 421.

As shown in fig. 2, the push foot rest 3 is composed of a fixed frame 31, a sliding sleeve 32, a frame rod 33, a bottom frame 34, and an elastic sleeve 35, wherein the fixed frame 31 is fixed at the bottom of the unmanned aerial vehicle body 1, the sliding sleeve 32 is rotatably embedded at the tail end of the fixed frame 31, the frame rod 33 is cylindrical, the upper section is thin, the lower section is thick, the upper section of the frame rod 33 is embedded on the sliding sleeve 32, the top end of the frame rod 33 is connected to the sliding block 41, the lower end of the frame rod 33 is fixed to the bottom frame 34, and the elastic sleeve 35 is embedded between the lower section of the frame.

The fixing frame 31, the sliding sleeve 32 and the frame rod 33 are four and are respectively arranged at four corners of the bottom of the unmanned aerial vehicle body 1, the elastic sleeve 35 is composed of a compression bar 351 and a lantern ring 352, the lantern rings 352 are fixed at two ends of the compression bar 351, eight compression bars 351 are arranged on the lantern ring 352 in a surrounding mode, the compression bar 351 is in a vertical state in a static state and is arched outwards when being pressed, and therefore the elastic sleeve 35 provides a straightening elastic force to stretch the frame rod 33 and the sliding sleeve 32.

The elastic sleeve 35 is made of elastic metal, and provides elastic force through the elastic sleeve 35 to expand the space between the frame rod 33 and the sliding sleeve 32, so as to drive the sliding block 41 to abut against the outer side of the clamping groove 11 to wait for triggering.

The stroke length of the switch of the sliding resistor 12 is greater than the displacement length of the top block 42, so that the switch of the sliding resistor 12 cannot be overtravel when the top block 42 moves, and the sliding resistor 12 is prevented from being damaged.

The working principle of the present invention is explained as follows:

the user operates through the controller unmanned aerial vehicle body 1, the motor rotation through unmanned aerial vehicle body 1 four corners department drives flabellum 2 to rotate and operate, thereby drive unmanned aerial vehicle body 1 to rise, when unmanned aerial vehicle body 1 descends, promote the chassis 34 of foot rest 3 to contact ground, rise through hack lever 33, promote the slider 41 in the steady lowering device 4 to move towards the unmanned aerial vehicle body 1, through driving round pin 411 on the slider 41 and propping up with trapezoidal round pin 421, drive kicking block 42 to the motion of unmanned aerial vehicle body 1 internal direction, thereby make chuck 423 drive sliding resistance 12 and promote inwards, thereby make unmanned aerial vehicle body 1 circuit resistance increase, make the motor of unmanned aerial vehicle body 1 drive the rotational speed decline of flabellum 2, make unmanned aerial vehicle body 1 can descend gently through contacting ground, cause collision damage of unmanned aerial vehicle body 1 when preventing the outage to fall;

example two

As shown in fig. 1 and 5, the present invention provides an unmanned aerial vehicle for smart city, which comprises: unmanned aerial vehicle body 1, flabellum 2, promotion foot rest 3, steady device 4 that falls, be equipped with power and main control board in the unmanned aerial vehicle body 1, flabellum 2 is established on the motor that unmanned aerial vehicle body 1 eight corners department was equipped with, steady device 4 is established in the bottom of unmanned aerial vehicle body 1, promote the 3 blocks of foot rest on unmanned aerial vehicle body 1 bottom and steady device 4 that falls, be equipped with block groove 11 and sliding resistance 12 in the unmanned aerial vehicle body 1, block groove 11 is established in unmanned aerial vehicle body 1 four corners department, sliding resistance 12 is established on the inside right side in block groove 11, steady device 4 is by slider 41, kicking block 42, spring 43, stopper 44, slider 41 and kicking block 42 divide the both sides of establishing in block groove 11, kicking block 42 and sliding resistance 12 looks block, spring 43 supports between block groove 11 inner wall and kicking block 42, stopper 44 is established in block groove 11.

As shown in fig. 5, a driving pin 411 is provided inside the slider 41, the top block 42 is provided with a trapezoidal pin 421, a push spring 422, and a collet 423, the trapezoidal pin 421 is engaged with the inside of the top block 42, the push spring 422 abuts between the end and the inner wall of the top block 42, the collet 423 is engaged with the sliding resistor 12, the outer working surface of the trapezoidal pin 421 is an inclined surface, the inclined surface points to the stopper 44, and the driving pin 411 abuts against the back of the working surface of the trapezoidal pin 421.

As shown in fig. 7, the top of the stopper 44 is in an inclined shape matching with the trapezoidal pin 421, a pressing plate 441, a compression pad 442, and a button switch 443 are disposed on the inclined surface of the stopper 44, the button switch 443 is disposed in the middle of the inclined surface of the stopper 44, the compression pad 442 is disposed on the inclined surface of the stopper 44, the pressing plate 441 is disposed on the compression pad 442 and maintains the same inclination as the inclined surface of the stopper 44, and the trapezoidal pin 421 can slide by the engagement of the trapezoidal pin 421 and the stopper 44 when being driven by the driving pin 411 through the inclined heads of the stopper 44 and the pressing plate 441 and can be retracted into the top block 42, so that the top block 42 is driven by the spring 43 to rebound, and the sliding resistor 12 is converted from a large resistance value to a zero resistance value for the next use.

Steadily decreasing device 4 is equipped with four and sets up the four corners department in unmanned aerial vehicle body 1 bottom separately, the sliding resistance 12 of steadily decreasing device 4 is series connection with the power in unmanned aerial vehicle body 1, the resistance is zero when sliding resistance 12 does not work, sliding resistance 12's resistance increase when the switch moves to stopper 44 direction to when making unmanned aerial vehicle body 1 descend, drive steadily decreasing device 4 work through promoting foot rest 3, inwards promote sliding resistance 12, thereby make unmanned aerial vehicle body 1 circuit resistance increase, make unmanned aerial vehicle body 1's motor drive the rotational speed decline of flabellum 2, make unmanned aerial vehicle body 1 can descend gently, cause unmanned aerial vehicle body 1 collision damage when preventing the outage whereabouts.

Button switch 443 is connected with the main control board in the unmanned aerial vehicle body 1, unmanned aerial vehicle body 1 stall when button switch 443 at the four corners of unmanned aerial vehicle body 1 triggers, through establishing button switch 443 at the end that sliding resistor 12 formed, when sliding resistor 12 circuit resistance increases and drive unmanned aerial vehicle body 1 steady descending, trigger button switch 443 makes unmanned aerial vehicle body 1 stall, prevents to drop and not cut off the power supply in time, and flabellum 2 function can cause the injury to the user when picking up unmanned aerial vehicle body 1.

The working principle of the present invention is explained as follows:

when the trapezoid pin 421 is driven by the driving pin 411 to move towards the limiting block 44, the trapezoid pin 421 and the limiting block 44 are engaged with each other to slide through the inclined surface, so that the linear motion of the trapezoid pin 421 towards the limiting block 44 is converted into the motion of the trapezoid pin 421 in the vertical direction, the trapezoid pin 421 is contracted into the top block 42, the top block 42 is disengaged from the engagement of the driving pin 411 to be driven by the spring 43 to rebound, and meanwhile, the sliding resistor 12 is converted from a large resistance value to a zero resistance value, so that the sliding resistor 12 does not need to be adjusted independently when being used next time;

establish button switch 442 at the end of sliding resistor 12 stroke simultaneously, when trapezoidal round pin 421 and stopper 44's block slided, trapezoidal round pin 421 extrudes clamp plate 441, triggers button switch 442 on the stopper 44, makes unmanned aerial vehicle body 1 stop operation, prevents that unmanned aerial vehicle body 1 from falling and not cutting off the power supply in time, and flabellum 2 function can cause the injury to the user when picking up unmanned aerial vehicle body 1.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.