TECHNICHAL FIELD

The invention relates to a tightening arrangement, comprising a power unit P and a transmission unit T, wherein the transmission unit is arranged to directly or indirectly transfer torque to a tightening shaft for tightening of a chain or a belt/strap, wherein said power unit P includes a linearly movable, reciprocating power rod 11 and said transmission unit T includes a pushing device 2 attached to the outer end of said power rod 11, wherein further said transmission unit T includes a dented wheel 4 mounted on a torque shaft 5 and said pushing device 2 comprising a pushing member 22 having a gripping member 220 arranged to interact with said dented wheel 4 for rotation of said dented wheel 4.

BACKGROUND

In relation to transporting heavy objects, especially timber, it is of utmost importance that the objects are safely and securely tightened to the vehicle such that no accidents may occur due to loss of heavy objects in trafficked surroundings. There are known several tightening arrangements that are fitted onto the frame structure of a vehicle for safe tightening of objects to be transported, e.g. timber. Mostly traditional arrangements use chains but there are also known arrangements using tightening straps/belts.

There is known a tightening arrangement where easy exchange between use of chains and straps/belts may be accomplished. This is achieved by having a shaft that is driven by the tightening arrangement and whereupon different tightening mechanisms may be applied either for chains or for straps/belts. This is a solution that is appreciated due to high flexibility. However, known tightening arrangements do suffer from deficiencies. A common deficiency is that the transmission mechanism may jam.

Accordingly, there is a need for providing a tightening arrangement that better fulfils the need for today’s transportation requirements. SUMMARY OF THE INVENTION

It is an object of the invention to provide a more reliable solution of a tightening arrangement, which is achieved with a tightening arrangement as defined in the claims.

Thanks to this solution it is not merely provided a more reliable solution but also a solution that is cost efficient.

Further beneficial aspects of the invention will become apparent from the detailed description and also in light of the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following the invention will be described in more detail with reference to the appended figures, wherein:

Fig.1 -Fig. 3 show in sequence a schematic side view of essential parts of a power unit and a transmission unit according to the invention,

Fig. 4 shows a view from above of a transmission unit according to the invention,

Fig. 5 shows an embodiment of a preferred tightening arrangement attached within a hollow frame member of a vehicle,

Fig. 6 and Fig. 7 show a preferred embodiment of a power unit according to the invention,

Fig. 8 shows a further embodiment wherein the tightening arrangement is attached underneath the frame structure of a vehicle,

Fig. 9 shows a schematic scheme for control of a pneumatic power unit in accordance with the invention, Fig. 10 shows an alternate embodiment for control of a pneumatic power unit according to the invention, and,

Fig. 11 shows a partly modification of the schematic scheme shown in Fig. 9 for control of a pneumatic power unit in accordance with the invention.

DETAILED DESCRIPTION

In Figs. 1-3 there is shown in sequence the operation of a power unit P and a transmission unit T in accordance with the invention, wherein Fig. 1 shows the power unit P in a retracted position, Fig. 2 in intermediate position and Fig. 3 in an end position wherein the power unit will start making a return stroke.

The power unit comprises of a pneumatic cylinder 1, having a cylinder housing 10 and a power rod 11 with a pressure lid 12 (see Fig. 6). At the end of the power rod 11 there is attached a pushing device 2. The pushing device 2 comprises an attachment member 20 and a pushing member 22, wherein the pushing member is attached to the attachment member 20 by means of a pivot shaft 21. Accordingly, the pushing member 2 can pivot around the pivot shaft 21. Furthermore, it is shown that there is arranged a guiding and camming device 3, which has as its object to guide and steer by camming the movement, at least partly, of the pushing member 22. The guiding and camming device

3 comprises at least one side member 31 that is fixedly attached to the pushing member 22. The side member 31 is arranged with a camming surface 32 that in contact with a cam shaft 33 will provide for a desired movement of the pushing member 22 in a first plane, which during normal use is a vertical plane. The pushing member 22 is arranged with a gripping member 220. The gripping member 220 has a protruding form which is achieved by providing a concave recess 221.

The pushing member 22 may interact with a dented transfer wheel 4. The dented wheel

4 is arranged with a plurality of dents 40 forming valleys 41 in between each pair of dents 40. The at least one side member 31 extends further than the pushing member 22 to 36, that will provide for keeping the pushing member 22 (thereby also the gripping member 220) in line with, i.e. in the same plane as, the dented wheel 4, to safeguard desired interaction between the pushing member 22 and the dented wheel 4. When the pushing device 22 is moved forward from its inner position (see Fig. 1) it will rest with its camming surface 32 on a cam shaft 33 and thereby be guided to have its get gripping member 220 in contact with a valley 41 of the dented wheel 4 (see Fig. 2). Hence, when moved further the gripping member 220 will push into the valley 41 and then urge the dented wheel 4 to rotate 4 in a counter-clockwise direction. When the dented wheel 4 rotates the gripped valley 41 will move upwards and then lift the pushing device 22, such that the pushing member 2/guiding member 3 will pivot around the pivot shaft 21.

Furthermore, it is shown that the dented wheel 4 is fixedly attached to a torque shaft 5 which is intended to transfer the power/movement that is supplied by means of the power unit P, to a tightening shaft (not shown), as known per se. (see also Fig 8) Moreover, there is shown that there is a locking device 6 that has a body 61 attached to a lock pivot shaft 60. The body 61 of the locking device 6 is such that the central mass is positioned at the left-hand side in relation to the lock pivot shaft 60 such that gravity will force the locking body 61 to pivot counter-clockwise, if not affected otherwise. At the bottom side 63 of the locking body 61 there is arranged a contact surface that when pushed upon may pivot the locking body 61 clockwise to enable the dented wheel to rotate clockwise, e.g. to be effected when tension is to be released, which may be achieved by a lever arm (not shown) arranged with a cam surface that may act upon the bottom side 63 to urge the locking device to pivot out of contact with the dented wheel 4.

In Fig. 1 it is shown a position of the power unit P, wherein the pushing member 22 is not in contact with the dented wheel due to the fact that the power rod 11 is positioned in its most inner position. As a consequence, the dented wheel will be fixed in its position by means of the locking device 60 having its front end 62 gripping into a valley 41 of a dented wheel 4. It may be noted that the guiding and steering device 3 in this position has its camming surface 32 in contact with the cam shaft 33. Hence, the whole unit 2, 3, comprising the guiding and steering device 3 and the pushing device 2 rests upon the cam shaft 33 due to gravity acting thereupon and the ability to pivot around the shaft 21. In Fig. 2 it is shown that the power rod 11 has been moved outwardly and that the pushing device 2 by means of its pushing member 220 is in contact with a valley 41 of the dented wheel 4 and has also moved the dented wheel 4 a distant counter-clockwise in relation to Fig. 1 As a consequence the pushing device 2 and the guiding device 3 will be lifted by means of the dented wheel since the rotation thereof will move the pushing member 220 upwardly. Hence, the cam surface 32 of the guiding and steering device 3 will no longer be in contact with the cam shaft 33. Further it is shown that the rotation has caused the locking device 6 to move by means of having a dent 40 pushing on an inner surface 64 of the locking body 61, such that the dented wheel 4 freely may rotate past the locking device 6.

In Fig. 3 it is shown the end position for movement of the power unit P, wherein the pushing device 2 has moved the dented wheel 4 a sufficient distance for the locking device 6 to pivot into another valley 41 of the dented wheel 4. Now the power unit P may safely return to its start position without rotation of the dented wheel 4, since the dented wheel 4 will be secured by the locking device 6 in the position shown in Fig. 3.

I Fig. 4 there is shown a front view of the transmission unit T described in connection with Figs. 1 to 3. It is shown that there is a transmission housing 7 providing a solid structure for mounting of shafts. It is shown that the torque shaft 5 is rotatably (by means of bearings) arranged transversally in the housing 7. On the torque shaft 5 there is arranged the dented wheel 4.

As can be noted in Fig 4, the dented wheel 4 may be positioned off centred in relation to the housing 7, which provides the advantage that there may be arranged other transmission parts, more centrally, next to the dented wheel 4 on the torque shaft 5. In the shown embodiment there is arranged a pair of dented chain wheels 8 intended for pulling chains that in turn may drive another shaft (as will be explained more in detail with reference to Fig. 5. Accordingly, it may be an advantage to have the dented wheel 4 off centred on the torque shaft 5. However, as evident for the skilled person, in many applications the dented wheel 4 may be positioned centred on the torque shaft 5, preferably so in any application not requiring another transmission parts (more centrally) next to the dented wheel 4 on the torque shaft 5, e.g. an application where the torque shaft 5 directly connects to the tightening shaft (not shown), for instance if positioned outside of a support beam or if positioned inside of a support beam and having through holes for a the tightening shaft such that it may be directly connected to the torque shaft 5.

Furthermore, it is shown the pusher device 2 and that the pushing member 22 of the pusher device 2 is arranged between two guide plates 31, 36. These guide plates 31, 36 will safeguard that the pushing member 22 always is positioned in line with the plane of the dented wheel 4 such that safe gripping of pushing member 220 within the dented wheel 4 always occurs. Moreover, it is shown that the cam shaft 33 also is securely attached within the transmission housing 7 such that the camming surface 32 of the steering and guiding member 3 will be in secure contact (when needed) with the outer surface of the cam shaft 33.

In Fig. 5 there is shown a schematic side view of a preferred embodiment according to the invention wherein the power unit P and the transmission unit T are arranged within the hollow space of a hollow support beam B of a vehicle, and a further torque transmitting unit 8 is used.

As can be noted the basic parts of the arrangement are the same as shown in Figs. 1-3, There may be many advantages of mounting the power unit P and the transmission unit T within the support beam B. Firstly it saves space that may be needed for other purposes. Secondly, it will provide for a secure protecting housing for the two units. As also shown, there is a locking device 6 wherein there is shown a release mechanism 64 which includes a plunger 65 that when activated will contact the lower surface 63 of the locking body 61 urging it to pivot around the lock pivot shaft 60 to have its front end 62 moving out of the periphery of the dents 40 of the dented wheel 4. Hereby the dented wheel 4 may be free to rotate also in clockwise direction. A blocking shaft 66 hinders the lock body to rotate too far, i.e. to foresee that gravity will urge counter-clockwise also in the most opened position.

Furthermore, it is shown details of the further torque transmitting unit 8. Attached to the torque shaft 5 there is arranged at least one dented chain wheel 80 for transfer of movement to a chain 81 that in turn will make a second dented chain wheel 82 rotate.

The second dented chain wheel 82 is mounted on a transmission shaft 9 that is hollow for attachment therein of a pulling shaft (known per se, not shown) for pulling either a chain or a strap/belt as is known per se, e.g. in the same manner as described above. Moreover, it is schematically indicated that the cylinder 1 preferably includes two pressure chambers 17, 18 in order to provide for enhanced force of the power unit P.

As shown in Fig. 5 the power unit P and first part of the transmission unit T may be attached onto a plate 70 that in turn is attached to a plate 71 which is fastened within the beam by means of nuts 72, such that there will exist a gap between the lower plates 771 and the inner wall of the beam B, which may be beneficial regarding more easy mounting of the power unit P and first part of the transmission unit T within the beam B.

In Fig. 6 and Fig. 7 there are shown schematic views of a double pneumatic cylinder according to one embodiment of the invention. In Fig. 6 the piston rod 11 is in its most forward position and in Fig. 7 the piston rod 11 is in its most inward position. There will be a front piston plate 12 and a rear piston plate 13. The rear piston plate will be movable in a rear pressure chamber 18 and the front piston rod 12 movable in front pressure chamber 17. There is a front cylinder wall 16, an intermediate cylinder wall 15 and a rear cylinder wall 14. In the rear cylinder wall 14 there is a supply inlet A to supply air for rearward movement of the piston rod 11 and an air supply channel B for forward movement of the piston rod.

The first supply passage A has a connection channel 142 that extends in a longitudinal direction of the cylinder housing 10 along the whole side wall and having one branch connection 142 into the intermediate wall 15 that may provide air from the intermediate wall 15 into the rear pressure chamber 18 and also a branch connection 142B that via the front wall 16 may provide air from the front wall 16 into the front pressure chamber 17. Likewise, the forward supply channel B also has a branch channel 141 that extends in the side wall 10 but merely to the intermediate wall 15 providing a supply of air via the intermediate wall 15 into the front pressure chamber 17. Further there is a pressure channel 140 that opens up from the rear wall 14 into the rear pressure chamber 18.

Moreover, it is shown that there is a through channel C in the side wall 10 which has a controlling function as will be described in more detail below.

In the position shown in Fig. 6 the piston rod 11 has been moved forward (right to left) and reached its forward end position. The power unit P, which preferably is a pneumatic cylinder, has a reciprocating function such that when the tightening arrangement is activated by a control unit (not shown) the piston rod 11 will reciprocate forth and back automatically until a stop signal is initiated and/or force sensing sensor provides a signal to the control system that tensioning is to be interrupted i.e. that sufficient tightening force has been applied to the objects to be transported.

In the position shown in Fig. 6 the piston rod 11 has been moved forward (right to left) and reached its forward end position, which is achieved by supplying pressurized air into the second pressure channel B, i.e. supplying air into the rear pressure chamber 18 and also via channel 140 and simultaneously also to the front pressure chamber 17 via channel 141, such that a pressure will be built up on the right-hand side of the piston plates 12, 13. Accordingly, the piston plates 12, 13 and the piston rod 11 will then move forward, i.e. from the right-hand side to the left-hand side, as shown in Fig. 6.

When the front piston plate 12 reaches its most forward position it will also pass the control channel C such that pressurized air will be supplied through the control channel C to the control arrangement and thereby arrange for switching the supply of air to switch from supplying to the second channel B and instead supply to the first channel A.

When air is supplied to channel A pressure will be applied via channels 142, 142A, 142B to the left-hand side of the two piston plates 12, 13 such that the piston plates 12, 13 together with the piston rod 11 will start moving backwards, i.e. from the left-hand side shown in figure 6 to the right-hand side and finally reach a position as shown in figure 7. Air within the pressure chambers 17, 18, on the non-pressurised side of each plate 12, 13, will be evacuated via the non-activated channel as is evidently understood by the skilled person.

The control signal to change from supplying channel A to channel B, in the position shown in Fig. 7 may easily be detected by the pressure increase that will occur when the piston plates 12, 13 reach their rearward end positions within the cylinder housing 10 since no load will be applied during the rearward stroke and consequently a pressure peak will occur once the end position is reached, which pressure peak may be used to initiate a shift from supply to channel A and instead again supply air to channel B.

In the other direction, when the position is reached as shown in Fig.6 it is not totally reliable to control via the pressure peak because the piston rod 11 will then be loaded with the counter force provided by the dented wheel 4. As is evident this load may vary depending on in which position the tightening device is in at that moment. Hence, the control channel C provides a reliable and cost-effective solution to achieve desired functioning. Accordingly, it is an intelligent solution to instead have a safe position sensor provided by one of the piston plates, e.g. the front piston plate 12, and have a through hole C that will be exposed for the pressure in one of the pressure chambers 17, 18, once a piston plate 12 (or 13) reaches its front position.

In Fig. 8 there is shown an alternative positioning of a tightening arrangement according to the invention wherein a positioning below a beam B is chosen. Accordingly in this embodiment there is no need of a further transmission unit via the torque shaft 5 to transmit the force to a tightening shaft, but instead the torque shaft 5 may itself be used and used to directly have the tightening shaft (not shown) attached thereto, i.e., by means of having the torque shaft 5 hollow and providing a passage 50 for positioning of a tightening shaft. In most aspects, as is evident from the figure the power unit P and the transmission unit T are basically the same as shown above. However, it is shown that the locking device 6 may have an unlocking plunger 65 that is positioned differently compared to what is shown above.

In Fig 9 there is shown an embodiment of a pneumatic circuit with valves for controlling the power unit P in the form the pneumatic cylinder 1 in accordance with what has been described above. However here the schematic view is more simplistic, e.g. using a single pressure chamber 17. It is shown a pressure source G1 that via an on- off valve 00 may connect or disconnect the source G1 to the circuit. It is shown that the second supply channel B is arranged in the rear wall 13 of the cylinder and the first supply channel A is arranged in the front wall 16 of the cylinder 1 such that pressure supply to channel B will produce a forward movement of the piston rod 11 and that pressure supply to channel A will provide a rearward movement of the piston rod 11.

Also, here it is shown that there is a through hole C in the cylinder wall 10 which supplies air to a channel CL once the piston plate 12 passes the position of the outlet hole C and accordingly there may be produced a pressure pulse in the pressure line C.

It is shown a pressure source G1 that via an on-off valve 00 may connect or disconnect the source G1 to the circuit. Pressure line C is connected to a first limit valve VI (e.g. of the 5/2 kind). A spring force will continuously urge the first limit valve VI in a lefthand direction. In the other direction, the right-hand direction, the first limit valve VI will be affected by the outflow air passing via the outlet line A when B is pressurized. As a consequence, this outflow will provide some pressure within line A and an intermediate connected pressure line D via a throttle check valve R1 onto the left-hand side of the first limit valve VI, urging it to be positioned in its right-hand positioning by compressing the spring. Accordingly, when the pressure plate 12 reaches its forward end position, i.e. in the right-hand side of the cylinder 1, no further air will be evacuated through line A and as a consequence the intermediate line D will not provide any pressure onto the first limit valve VI such that the spring moves the valve into a left-hand position whereby the first limit valve VI via line E will supply air to the righthand side of an operation valve V2 and cause it to move in a left-hand direction. As a consequence, this will arrange for a shift of the operation valve V2 to a position as shown in Fig. 9, i.e. a position of the operation valve V2 such that the pressure supply via line F is directed from the pressure channel B to pressure channel A. Hence, the piston will then move leftwards in Fig. 9.

Then once the piston plate 12 has reached its final position moving inwards the pressure exerted by the outflow air in line B, which via line G, including a throttle check valve, is connected to a second limit valve V3 will be ended. Thereby the second limit valve V3 will no longer be pressurized via line G and accordingly the spring of that second limit valve V3 will urge the valve in a right-hand direction such that line H will be pressurized and which then in turn will cause the operation valve V2 to move in a righthand direction and as a consequence the pressure via line F will be switched to instead pressurize line B. Accordingly automatic reciprocating movement is achieved by this pressure circuit of the piston unit 1. In Fig. 10 there is shown an alternate embodiment of achieving the reciprocating movement of the piston rod 11 by means of using an intermediate wall 15A having a slide member 150 off-centrally positioned therein movable between two positions, wherein those two positions are controlled by the piston plates 12, 13, i.e. by pushing the slide 150. Within the wall 15A there are channels corresponding to a 5/2 valve, which are differently activated depending on the position of the slide 150. In a corresponding manner as described above, when in a first position pressure will be supplied via forward channels to a first side of the two piston plates 12, 13 and evacuated via rearward channels. When the piston plates 12, 13 reach their end positions the slide 150 will be pushed into a second position where instead air will be supplied to the rearward channels and evacuated via the forward channels. Accordingly, automatic reciprocating movement may be achieved of the piston unit 1.

In Fig. 11 there is shown a modification of the pressure scheme shown in Fig. 9, wherein there is a arranged a by-pass line K, that continuously connects the operational valve V2 with the pressure source Gl, i.e. without being affected by the on-off valve OO. This provides the advantage that the piston 1 may always be moved into the lefthand position, i.e. without providing any force onto the transmission unit T, which enables easy disconnection of the tightening arrangement, e.g. chain or strap, since the pushing device 22 will then be moved away/be distant from the dented wheel 4, such that it then merely a matter of loosening the locking device 6 to loosen the tension.

Further, there is shown a pivot valve V4, that via line E from the first limit valve VI may move the operational valve V2 to the left-hand position or via line L from the on- off valve OO may move the operational valve V2 to the left hand position, depending on which one of the lines E, L is pressurized (i.e. gives the highest pressure). Hence, pressure via either one of lines E and L will move the operational valve V2 to the lefthand position providing connection of line A. Accordingly, line K may be seen to correspond to line F in Fig. 9, with the difference in the fact that the scheme in Fig. 11 also moves the piston 1 to the left-hand position when the on-off valve is off. A further advantage with the scheme shown in Fig. 11 is that throttle check valves may be disposed of.

As already mentioned the function generally is the same as described in relation to Fig. 9. In brief, when the on-off valve OO is turned on, air will pass through line M via the second limit valve V3 and reset the operational valve V2 into its right-hand position, whereupon the piston 11 makes an outward, tightening stroke. When the piston 11 has reached its end position the hole C will provide pressure via line CL to the first limit valve SI, which due to no pressure in line D is urged by the spring into its left-hand position, and thereby allowing pressure into line E, which resets the operational valve V2 into a let hand position, whereby the piston starts moving inwards. Hence, the reciprocating action is working, which will continue until either the on-off valve 00 is turned off or until a resistance is met that balances the set force of the cylinder 1, e.g. about 30 -50 kN. Preferably, the power supplied from the power source G1 is adjustable, to allow for automatically achieved desired tension. If the on-off valve 00 is then not turned off, the piston 11 will maintain/hold that balance position, with the locking device 6 as a safe guard, which is the recommended manner during freight.

When the on-off valve 00 is turned off, which normally is done when unloading is to be performed, the piston 11 will make an inward movement, allowing merely the locking device 6 to keep the tension. As mentioned above the locking device 6 may be release by a variety if devices. If, in an extreme situation, the locking device 6 would not be easily moved out of its locking position it may be released by aging turning the on-off valve 00 on whereby the piston 11 may assist in diminishing the load on locking device 6 and allow easy released, such that the tension may thereafter be released by again turning the on-off valve 00 off.

As is evident for the skilled person the above-described embodiments include details providing a function that may be achieved in various manners within the ambit of the scope of claims of the invention. For example, it is evident that instead of a pneumatic power device varying mechanisms exist that may provide the same function, e.g. linear actuators powered by means of an electric motor. Further it is evident that the expression “forced by gravity” has to be given a broad interpretation, i.e. not to be seen as circumvented if also a minor force not dependent on gravity is applied.