SUCTION DEVICE

The invention relates to a suction device comprising at least one suction unit, preferably three suction units, for adhesion to a surface, in particular a vertical surface, by a vacuum force.

STATE OF THE ART

Suction devices, which allow strong but releasable fixation on surfaces, in particular on vertical walls or even on the lower side of a roof, are widely used in several fields of technology. Especially climbing apparatus for example used for cleaning and maintenance of facades of buildings or large vehicles often use several suction devices to fix the apparatus alternatingly to the surface such that it may move along the surface. The suction devices generally comprise one or more suction cups or similar assemblies, that form a vacuum chamber between the surface and an inner wall of a cupshaped structure. The vacuum chamber can be provided with a vacuum or at least a partial vacuum such that the suction cup is adhered strongly to the surface.

Such devices are for example known from US 5,890,250 or DE 198 35 038 CI which show a robot washing apparatus and a facade climber respectively, using a suction cup mechanism for traveling along a vertical surface. A vacuum assembly comprises bellow vacuum cups, pneumatic cylinders and a series of air vacuum generators. Compressed air for operating the air vacuum generators is provided via an air hose suspended from the vicinity of a carriage or from a pressurized air ejector.

Such devices for generating the required vacuum within the vacuum cups are costly, maintenance intensive and need a lot of energy, which preferably could be used for other tasks.

In WO 2006/083094 an absorption-type robot is shown that uses adhering plates for fixing and moving the robot along a surface. A vacuum between the surface and the adhering plate is generated by a vacuum assembly comprising a cylinder, a piston, a piston gear motor and a coupling tube. The piston is located in the cylinder so as to change inside pressure of the cylinder, when it is driven up and down by the motor. The coupling tube is joined to a lower part of the cylinder at one end and to the adhering plate at the other end, such that a clinging space of the adhering plate communicates with the inside of the cylinder through the coupling tube. When the adhering plate is in contact with the surface and the piston moves upward by the piston gear motor, the air existing in the internal space between the adhering plate and the surface flows into the cylinder through the coupling tube. So, a pressure of the clinging space is reduced and thereby a clinging force is created. Contrary to that, when the piston moves downward, the air in the cylinder flows into the internal space, diminishing a clinging force.

In this absorption-type robot only one adhering plate may be connected to a vacuum generating motor and the vacuum created by the moving piston is not directly applied to the adhering plate, which leads to a loss of efficiency.

OBJECT OF THE INVENTION

It is an object of the invention to provide a suction device which functions reliably over a long period of time without any need of maintenance, which does not require any supply tubes or the like, which is capable to supply several vacuum units with a vacuum at the same time and which shows a cost-saving construction. These objects are solved by a suction device according to claim 1. Preferred embodiments of such suction device are disclosed in the sub claims.

According to the present invention a suction device for adhesion to a surface comprises at least one suction unit with a flexible suction member creating a vacuum chamber between the surface and an inner side of the suction member facing the surface, and a vacuum activator for creating a vacuum in the vacuum chamber, such that the suction device adheres to the surface. The at least one suction unit comprises a moveable rod, which on one end is connected to an outer side of the suction member. Preferably the rod is attached at a middle part of the flexible suction member and extends essentially perpendicular from the flexible suction member. The other end of the rod is connected to the vacuum activator by a screw connection such that a rotational movement of the vacuum activator is transferred to a linear movement of the rod, which then lifts the middle part of the suction member away from the surface for creating a vacuum in the vacuum chamber. The screw connection can include a screw member which engages into a screw counter-member on the rod or coupled to the rod, whereby the vacuum activator is coupled to the screw member for rotation of the screw member relative to the screw counter-member.

For example the suction unit can comprise a housing with a cylindrical upper portion and a cuplike lower portion. The lower portion is open towards the surface and the opening is covered by the flexible suction member. The upper portion contains the screw connection which may comprise the screw member with an external thread and the screw counter- member in form of a nut with an internal thread. The nut is linearly but not rotationally moveable within in the housing. For example a linear guiding is provided on the inner wall of the upper portion comprising e. g. a longitudinal groove in which a pin or a bolt of the nut is slidingly arranged. The screw member is arranged rotationally but axially fixed within the housing. The rod is non-rotationally arranged at the nut or fixed to the nut. The linear guiding may also be realized between the rod and the upper portion of the housing. The upper portion of the housing creates an axis along which the rod may be moved by the vacuum activator and which essentially runs perpendicular to the surface of the flexible suction member. The flexible suction member preferably is made of rubber or an equivalent material. The flexible suction member covers the opening of the lower portion of the housing and basically ends at a rim of housing. The rod is attached to the outer side of the flexible suction member preferably in the center point of the cupshaped lower portion. But it can also be attached at a point some distance away from the center point as long as the middle part of the flexible suction member can be lifted from the surface.

According to the invention the vacuum chamber between the flexible suction member and the surface is a closed chamber without any openings to the external of the chamber, when the lower portion of the housing is pushed on the surface. When the rod is lifted by rotation of the vacuum activator transferred by the screw connection the rod, the middle part of the flexible suction member is lifted away from the surface while the edge of the flexible suction member rests on the surface fixed by the rim of the housing.

Preferably the suction device includes at least two suction units, more preferably three suction units, each coupled to the vacuum activator. In this way the adhering force of the suction device can be enlarged without the need of a further vacuum activator.

The vacuum activator of the suction device comprises a motor for driving a drive shaft of the vacuum activator. The motor may be a conventional electric motor e. g. powered by batteries or solar energy. In one embodiment of a suction device according to the invention the motor is coupled to the screw member by a gear reduction. The motor is for example arranged eccentrically to the drive shaft of the vacuum activator and is coupled to the drive shaft preferably by a meshing engagement, although other couplings may be used. In particular preferred the motor of the vacuum activator is coupled to the screw member or the drive shaft respectively via a drive belt. The drive belt preferably is a toothed drive belt, which engages with a corresponding toothed member of the motor, the screw member and the drive shaft respectively. The toothed belt is for example a polyurethane belt or made of other material with a soft surface. The vacuum activator in this case generally is composed of the motor, the drive shaft, the screw member and the couplings between these parts. The suction device according to the invention establishes the vacuum for adherence to a surface basically by using a simple but highly efficient and reliable mechanical structure. Therefore a vacuum can be established at any time needed without the necessity of a reservoir of air pressure or the like. The mechanical structure can provide an optimum efficiency factor for the used energy. It provides a simple construction to supply several suction units with vacuum.

In one embodiment of a suction device according to the invention the gear between the motor of the vacuum activator and the screw member of the suction unit is realized by circle segments connected to the screw member and/or the drive shaft respectively. The circle segments engage with each other ether directly or via a coupling part e. g. a piece of a toothed driving belt or band. The circle segments have a diameter capable of reducing the rotation speed of the motor to a lower rotation speed of the screw member. Alternatively the screw member and/or the drive shaft themselves may comprise capable diameters for reducing the rotation speed of the screw member.

Preferably the drive shaft of the vacuum activator is orientated essentially parallel to the rod of the suction unit or the axis of the screw member and is arranged eccentrically to the rod, whereby the screw member of the screw connection is coupled to the drive shaft. In this embodiment the rotation is transferred from the motor to the drive shaft and from the drive shaft to screw member. The drive shaft can comprise an extension essentially perpendicular to the drive shaft, which at its end opposite to the drive shaft is provided with a circle segment according a circle around the axis of the drive shaft but with larger diameter than the drive shaft. The circle segment is coupled to the motor, instead of coupling the motor directly to the drive shaft, to reduce the speed of rotation acting on the screw member.

In an especially preferred embodiment an extension of the drive shaft comprises at its end opposite to the drive shaft two brackets extending forklike in different directions. A toothed drive belt is stretched between the brackets and the drive belt is coupled to the motor. Such the action of the motor is transferred by the toothed drive belt to rotate the drive shaft of the vacuum activator by pulling the drive belt along the motor. In this way the motor moves the toothed drive belt by a meshing engagement of the toothed drive belt and for example a pulley driven by a driving crank of the motor.

It is advantageous to transfer the motor action by a drive belt because the alignment and the fine tuning of the coupled parts of the vacuum activator is easy. There is less noise and less vibration within the suction device. Furthermore there is a negligible wear on the parts of the vacuum activator. The belt is easy to replace and the costs for replacement are low. Finally the belt allows a gentle start motion which exerts less stress on the motor than an engagement of metal parts.

In one embodiment the screw member may comprise an arm, which is radially extending toward the drive shaft and comprises a circle segment of a circle around the axis of the screw member, whereby the diameter of the circle segment is larger than the diameter of the screw member. The circle segment is coupled to the drive shaft preferably by a meshing engagement. For example the outer circle line at a front end of the segment engaging with the drive shaft can be covered with a toothed band e. g. a polyurethane band for cushioning the transfer of the rotation of the drive shaft.

To realize the gear reduction between the motor and the screw member the diameter of a driving axle, the driving crank or the pulley of the motor is smaller, preferably a couple of times smaller, than a diameter of the circle segment of the arm of the screw nut and/or the circle segment or the length of the brackets of the extension of the drive shaft. Thus a small motor can be used, which nevertheless produces a high torque. The motion wear and tear reduction on the engaging parts is small and the motor has a long lifetime.

As mentioned above the rotation of the vacuum activator and the parts of the vacuum activator respectively in one direction generates at least a partial vacuum in the vacuum chamber such that the suction device adheres to the surface. A rotation of the vacuum activator in the other direction terminates the at least partial vacuum in the vacuum chamber because the rod of the suction unit is pushed downwards in the direction of the surface so that the volume of the vacuum chamber is reduced and the suction effect is neutralized. That means the movement of the vacuum activator in the other direction is transferred to a counter linear movement of the rod pushing the middle part of the flexible suction member in direction of the surface. Such one rotational direction of the vacuum activator is the fastening direction and the other rotational direction in the counter direction is the releasing direction.

In this way the suction device realizes an active way of terminating the vacuum in the vacuum chamber, so that the suction device can be released from the surface in a controlled manner. Therefore the suction device can be released from a surface reliably in any circumstances. Also the force of the vacuum can be controlled by the vacuum activator according to the invention in that the distance the rod is located from the surface and therefore the flexible suction member is lifted from the surface can be regulated according to adherence force required. The degree of rotation of the vacuum activator in one or the other direction is a measure for the generated adherence force.

In one embodiment of a suction device according to the invention a spring can be arranged between an outer side of the flexible suction member and a housing abutment, whereby the rod lifts the suction member against the force of the spring, when the vacuum activator rotates the screw member. The spring helps to push the rod downwards to terminate the vacuum in the vacuum chamber, when the vacuum activator rotates in the other direction.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention will be described in the accompanying drawings, which may explain the principles of the invention but shall not limit the scope of the invention. The drawings illustrate:

Fig. 1 side view of a suction device according to the invention,

Fig. 2 longitudinal cross-section of the suction device in a released status, Fig. 3 partial longitudinal cross-section of a suction unit of the suction device in a suction status, and

Fig. 4 inside top view of the suction device.

In figure 1 a suction device according to the invention comprising three suction units 1 (only two suction units are visible in figure 1). The suction device comprises a drive motor 2, a drive shaft 3 and a connecting lever 4, which connects the drive shaft 3 with the motor 2. Each suction unit 1 is connected to the drive shaft 3 by a lever arm 5 and such indirectly connected to the motor 2. A suction unit 1 comprises a housing with an upper portion 6 and a cupshaped lower portion 7 with a circular rim. The lower portion 7 has an opening towards a surface (not shown), which is covered by a flexible suction member 8. The flexible suction member 8 ends at the rim of the lower portion 7 of the housing. The three suction units 1 are connected to a center housing 9, which also serves as a bearing for the drive shaft 3.

In figure 2 the inside of the suction unit 1 is shown. The upper portion 6 holds a screw member in form of a suction screw 10 and a screw counter-member in form of a suction nut 1 1. The screw member 10 is held in the upper housing portion within a bearing 12 such that the screw member 10 can rotate within the housing but cannot move along a longitudinal axis of the housing. The suction nut 11 is arranged within a linear guiding such that the suction nut 1 1 can move axially within the upper portion 6 of the housing but is secured against rotational movement. A moveable rod 13 is connected to the suction nut 1 1. Alternatively the rod may be an integral part of the suction nut.

The rod 13 extends along the longitudinal axis of the housing from the upper portion 6 through the lower portion 7 to the flexible suction member 8. The rod 13 is connected to the flexible suction member 8 in a middle part of the flexible suction member, preferably in the center point of the flexible suction member. A spring 14 is arranged between the flexible suction member 8 and an abutment 15 of the housing. The spring 14 is biased to act against the flexible suction member 8 in direction of a surface 17 (see figure 3). The suction unit 1 in figure 2 is in a released status, where the flexible suction member lies flat on the surface 17. In figure 3 the suction unit 1 is in a suction status, where a vacuum chamber 16 is established between an inner side of the flexible suction member 8 and the surface 17. As can be seen, the vacuum chamber 16 does not comprise any openings. To change from the released status to the suction status of the suction unit 1 , the motor turns the drive shaft 3 via the connecting lever 4 and the drive shaft 3 turns the screw member 10 via lever arm 5 within the bearing 12 of the upper portion 6 of the suction unit housing. By rotation of the screw member 10 the suction nut 1 1 is moved upwards in the upper portion 6 of the housing due to the threaded engagement with the screw member 10 and the linear guiding within the housing. When the suction nut 1 1 travels upwards it takes along the rod 13 and the middle part of the flexible suction member, while the edge of the flexible suction member 8 rest on the surface 17. By lifting up the flexible suction member 8 from the surface 17 the vacuum chamber 16 and at least partial vacuum within the chamber 16 is established, that sucks the suction unit 1 to the surface 17. While lifting up the flexible suction member 8 the spring 14 is compressed and stores a spring force.

When the screw member 10 is turned in the counter direction and the suction nut 1 1 is lowered within the upper portion 6 of the suction unit housing. Simultaneously the rod 13 is driven in direction of the surface 17. The lowering movement is supported by the spring force of the spring 14. In this way the vacuum in the vacuum chamber 16 is released and the suction unit and the suction device respectively can be taken off the surface 17. The release of the suction unit can be controlled by the velocity the suction nut 1 1 and the rod 13 respectively are driven in direction of the surface. The velocity of the suction unit can be controlled be the rotational speed of the vacuum activator in one or the other direction.

In figure 4 the suction device according to one embodiment of the invention is shown schematically from a top view. Figure 4 shows the parts of the vacuum activator and their connection schematically. The connecting lever 4 extends basically radially from the drive shaft 3 in general direction of a motor block carrying the motor 2. The connecting lever 4 acts as an extension of the drive shaft 3. It comprises a circular segment 18 and two brackets 19 and 19' extending into opposite direction. A toothed drive belt 20 is stretched between the brackets 19 and 19'. The toothed drive belt 20 engages with a toothed motor pulley 21 (see figure 2) connected to a driving axle of the motor. The motor can pull the toothed drive belt 20 such that the connecting lever 4 passes by and simultaneously rotates the drive shaft 3. The brackets 19 and 19' actually define a section of a circle extending from bracket 19 to the other bracket 19' and the length of the connecting lever defines the diameter of such circle section.

Alternatively the connection lever 4 may engage with the motor pulley 21 with a toothed row on the front side of the circular segment 18 instead of using a drive belt 20. In this case a more precise alignment of the motor block and the drive shaft will be necessary.

The screw member 10 is connected to the lever arm 5, which extends in general radially in the direction of the drive shaft 3. The lever arm 5 comprises a circular segment 22 with a diameter larger than the diameter of the screw member 10 and also larger than the diameter of the upper portion 6 of the suction unit housing. At the front end of the circular segment 22 a piece 23 of a toothed driving belt is fixed for engagement with a toothed center pulley 24 (see figure 2), which is part of the drive shaft 3 or attached to the drive shaft.

When the suction device according to the invention is activated, the motor 2 pulls the toothed drive belt 20 arranged at the connecting lever 4, which results in a rotation of the drive shaft 3. The rotation is transferred to the lever arm 5 by the engagement of the center pulley 24 with the toothed piece 23 on the circular segment 22 of the lever arm 5. Such the lever arm 5 is rotated. The rotation in is transferred to the screw member 10, which causes a linear movement of the suction nut 1 1 and the rod 13, so that a vacuum is created in the vacuum chamber 16 and the suction device is adhered to the surface 17.

The toothed drive belt 20 and the toothed pieces 23 are easily changed because they are simply attached to the brackets 19 and 19' and to the front side of the circular segments 22 of the lever arm 5 or even on the circular segment 18 of the connecting lever 4.

As can be seen in figure 4 all three suction units 1 can be connected to the same motor 2 by the drive shaft 3 and the center pulley 24 respectively. The motor 2, the drive shaft 3 and the axis of the screw member 10 run parallel to each other but are located eccentrically to each other. The distances between the motor 2, the drive shaft 3 and the screw member 10 define the length of the connecting lever 4 and the lever arm 5 or the diameter of the circular segments 18 and 22 respectively. The set up results in a gear reduction for the transmission of the rotation of motor 2 to the screw member 10.

The suction device can advantageously be used in connection with a climbing apparatus for the maintenance of buildings and the like.

LIST OF REFERENCE NUMBERS Suction unit

Motor

Drive shaft

Connecting lever

Lever arm

Housing upper portion

Housing lower portion

Flexible suction member

Center housing

Screw member

Suction nut

Bearing

Rod

Spring

Abutment

Vacuum chamber

Surface

Circular segment

Bracket

Toothed drive belt

Motor pulley

Circular segment

Toothed piece

Center pulley