Abstract:
Unit for picking up spare wheels in vehicles that includes a winding assembly with a rotating shaft, the rotating shaft having a gear with a plurality of spaced-apart teeth circumferentially disposed about the rotating shaft. The unit further includes a safety device that includes a spring loaded cam that is pivotable between first and second angular positions. The cam includes an engaging portion that is configured to engage with the spaced-apart teeth on the rotating shaft. In the first angular position the engaging portion of the cam is urged towards the gear of the rotating shaft by action of a spring element so that the engaging portion resides in a space between the spaced-apart teeth to prevent rotation of the rotating shaft. In the second angular position the engaging portion of the cam is positioned away from the gear of the rotating shaft against the action of the spring element so that the engaging portion does not engage with the spaced-apart teeth to permit rotation of the rotation shaft.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application relates to and claims the benefit and priority to Spanish Patent Application No. P201131974, filed Dec. 6, 2011. 
     TECHNICAL FIELD 
     The invention relates to units for picking up spare wheels in vehicles. 
     BACKGROUND 
     There are known units in the prior art for picking up spare wheels designed for their use on vehicles, and more specifically units designed in picking up or releasing a spare wheel which is disposed beneath the chassis (or on the underside) of the vehicle. 
     These units comprise a main shaft connected to the wheel and supporting it, a mechanism with a power shaft, which may be of different types, which allow a cable to be wound or released when the user acts on the power shaft with a tool, the cable being connected at one end to the main shaft and at the other to the mechanism, said mechanism withstanding the tension transmitted by the cable due to the weight of the wheel, and the mechanism being designed so that the power shaft is locked, and its movement therefore being irreversible, and it only being able to rotate again in any direction when the user acts on it with the tool. The units also comprise a safety device that is activated when the tool stops acting on the power shaft. 
     U.S. Pat. No. 6,267,546 discloses a unit of this type. Said unit comprises a main shaft with a support for the wheel, a mechanism connected to the main shaft acted on by the user with a tool, with a cable for raising or lowering said main shaft, and therefore the wheel, between an upper position and another lower position, and a safety device. Said safety device comprises a sliding bolt adapted to support the main shaft, and therefore the wheel, and an actuator adapted to selectively move the bolt between a locking position in which the safety device supports the main shaft, and an unlocking position in which the movement of said shaft is released. The safety device is always in an active position, and the bolt is in the locking position, and therefore supporting the main shaft, when the tool is not acting on the mechanism. 
     SUMMARY OF THE DISCLOSURE 
     According to one implementation a unit for picking up spare wheels is provided for use in vehicles, and more specifically for its use in picking up or releasing spare wheels in vehicles in which the spare wheel is housed on the underside of the vehicle. In one implementation the unit comprises a main shaft connected to the wheel supporting its weight; a mechanism with a power shaft that comprises a plurality of members and transmits a leading power, which allows it to wind or release a cable when the user acts on said power shaft with a tool. The cable is connected at one end to the main shaft and at the other to the mechanism, said mechanism withstanding the tension transmitted by the cable due to the weight of the wheel. The mechanism is designed in such a way that the power shaft of the mechanism may only rotate in any direction when the user acts on it with the tool designed for that purpose, and for as long as this does not happen the power shaft is locked, its movement is, in theory, irreversible and the wheel does not move. The unit also comprises a safety device that is connected to the mechanism, which moves to an active position when the tool stops acting on the power shaft. The safety device, when it is in the active position, cooperates with the mechanism through the power shaft and when the locking of the power shaft fails and it begins to rotate, said safety device acts on the power shaft, locking its rotation. 
     When it is travelling the vehicle is subjected to movements which cause stresses that are transmitted to the unit for picking up spare wheels, and are therefore transmitted to the mechanism. These stresses are impacts and/or vibrations that are accentuated when the user has not totally secured the wheel against the underside of the vehicle, and there is a distance between the upper part of the wheel and the lower part of the vehicle. Known mechanisms with a power shaft are, in theory, irreversible in their rotation, although due to these impacts and vibrations it has been shown that this irreversibility can become reversible and the power shaft may rotate releasing the cable, namely the cable that supports the main shaft and therefore the wheel, while also possibly releasing the safety device that supports the main shaft. When these situations arise the unit, which comprises the safety device—which is in the active position—comes into action, as the mechanism, which in theory is irreversible, may become reversible, locking the rotation of the power shaft when there is a failure in the locking of the power shaft and it has therefore started to rotate, and thereby preventing any movement of the power shaft from the very start. 
     Other advantages deriving from the unit are that this unit is compatible with many mechanisms with an existing power shaft, and capable of use with multiple types of power shafts regardless of whether the unit is disposed or otherwise with an additional safety device to support the main shaft. Furthermore, as it is a unit with few members and simple in design, the cost is reduced and its arrangement in the mechanism simplified. Additionally, another advantage it provides in terms of cost is that the safety device for supporting the main shaft may be removed, if the customer so wishes, as the unit with said safety device is effective and produces irreversibility of the movement of rotation, as the action of the device is caused on the power shaft itself. 
     According to other implementations, an apparatus for storing a spare wheel on a motor vehicle is provided that comprises: a first mechanism attached to the motor vehicle comprising a vertically disposed main shaft that is adapted to support the load of the spare wheel, the main shaft moveable between a first vertical position where the spare wheel is in a stored position and second vertical position lower than the first vertical position where the spare wheel is in an accessible position; a second mechanism comprising a winding assembly having a rotating shaft with a first end adapted to receive a tool, the rotating shaft rotatable upon the application of a rotational force applied by the tool, the rotating shaft comprising a gear with spaced-apart teeth circumferentially disposed about the rotating shaft; the first and second mechanisms coupled by a cable having a first end and a second end, the first end of the cable coupled to the main shaft of the first mechanism, the second end of the cable coupled to the winding assembly of the second mechanism, the cable capable of being wound in the second mechanism upon a rotation of the rotating shaft in a first direction to move the main shaft of the first mechanism towards the first vertical position, the cable capable of being unwound in the second mechanism upon a rotation of the rotating shaft in a second direction opposite the first direction to move the main shaft of the first mechanism towards the second vertical position; the apparatus further comprising a safety device that is capable of assuming an active position and a non-active position, the safety device comprising a cam that is pivotable about an axis between a first angular position that corresponds to the active position and a second angular position that corresponds to the non-active position, in the first angular position an engaging portion of the cam is urged towards the gear of the rotating shaft by action of a spring element so that the engaging portion resides in a space between the spaced-apart teeth to prevent rotation of the rotating shaft in at least the second direction, in the second angular position the engaging portion of the cam is positioned away from the gear of the rotating shaft against the action of the spring element so that the engaging portion does not engage with the spaced-apart teeth to permit rotation of the rotation shaft in at least the second direction. 
     These and other advantages and characteristics will be made evident in the light of the drawings and the detailed description thereof. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a perspective view of one implementation of the unit with the safety device in an active position. 
         FIG. 2  shows a perspective view of the individual parts of the mechanism of the implementation of  FIG. 1 . 
         FIG. 3  shows a perspective view of the individual parts of the safety device of the implementation of  FIG. 1 . 
         FIG. 4  shows a perspective view of the safety device of the implementation of  FIG. 1 , in an active position and fitted on the mechanism without a cover. 
         FIG. 5  shows a perspective view of the pawl mechanism of the safety device of the implementation of  FIG. 1 , in an active position on the drive shaft of the mechanism without a cover. 
         FIG. 6  shows a perspective view of the pawl mechanism of the safety device of the implementation of  FIG. 1 , in a non-active position on the drive shaft of the mechanism without a cover. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a perspective view of an implementation designed to wind or release a spare wheel of a vehicle, which is disposed beneath the chassis (or on the underside) of the vehicle. The unit comprises a main shaft  1  connected to the wheel, said main shaft  1  extending vertically to pass through a central hole of the wheel (not shown in  FIG. 1 ), and said main shaft  1  comprising a support on which the wheel is supported. 
     The unit also comprises a mechanism  2 , and as can be seen in  FIG. 2 , said mechanism  2  comprises a power shaft  50 . A power shaft is understood as any object especially designed to transmit power, and in the mechanisms of units for picking up spare wheels in vehicles it is, in particular, a shaft that transmits a drive force and is subjected to torque requests due to the transmission of a pair of forces: the incoming force due to the weight of the wheel, and the outgoing force on the shaft being acted on by the user with the tool. Power shafts may be of various types, being capable of being of an eccentric cam, a worm gear with helicoidal mesh, a coiled spring in the gear shaft, etc. In the mechanism  2 , in one implementation the power shaft  50  is of the eccentric-cam type, comprises a plurality of members that rotate around an imaginary coaxial shaft, and transmits a drive force, which allows a cable  3  to be wound or released when the user uses a tool  5  to act on said power shaft  50 . The term “cable” should be understood as any type of flexible connection member suitable for performing the function of transmitting the tension due to the weight of the wheel. 
     Said cable  3  is connected at one end to the main shaft  1  and at the other to the mechanism  2 , with the result that said mechanism  2  withstands the tension of the cable  3  due to the weight of the wheel. The power shaft  50  comprises, among other members, an eccentric cam, a drum for winding and releasing the cable  3 , a plurality of meshes with a reducing effect that allows the torque requested at the intake of the power shaft  50  due to the weight of the wheel to become a much smaller torque at the outlet, which allows the user to use the mechanism  2  by means of the tool  5 , and a drive shaft  4  that transmits the torque to the outlet of the power shaft  50 , and on the end of which is housed the tool  5 . The power shaft  50  is designed in such a way that the configuration of the members of which it is comprised make it irreversible, with the result that they ensure that when the cable  3  is wound as a result of it being acted on by the user with the tool  5 , it does not move back due to the tension caused on the cable  3  due to the weight of the wheel, and the mechanism  2  is locked. In this situation the power shaft  50  may only rotate when it is acted on with the tool  5 . 
     In one implementation the unit also comprises a safety device  6  connected to the mechanism  2 . This safety device  6  moves to an active position, and is therefore in a situation in which it may cause an action when the tool  5  stops acting on the power shaft  50 . The safety device  6  of the unit, when it is in an active position and therefore when the tool  5  is not acting on the power shaft  50 , cooperates with the mechanism  2  when the locking of the power shaft  50  fails, for example, due to the vibrations to which the vehicle is subjected and the wheel is not totally in its housing position. The power shaft may then begin to rotate, and it is at this point that the safety device  6  acts on said power shaft  50  and locks its rotation, preventing the wheel from falling on the ground. 
     As shown in  FIG. 2 , the drive shaft  4  of the power shaft  50  comprises an end  23  adapted to house the end of the tool  5 , the safety device  6  acting on said drive shaft  4  in the active position.  FIG. 3  shows how the safety device  6  of the unit comprises in one implementation a pawl mechanism  7  and a drive guide  8  disposed on the cover  40  of the mechanism  2 , with the result that the end  23  of the drive shaft  4  projects out of said cover  40 . The pawl mechanism  7  acts on the drive shaft  4  when the safety device  6  is in the active position. Said pawl mechanism  7  comprises a cam  9 , a spring unit  10  and a shaft  11  that connects the cam  9  and the spring unit  10  to the drive guide  8 . The drive shaft  4  also comprises a crown gear  24  disposed next to and beneath the end  23 , surrounding the drive shaft  4 , being connected to it. The crown gear  24  comprises a plurality of teeth  30  and is disposed beneath the cover  40 , and the cam  9  acts on said crown gear  24  when the safety device is in the active position. 
     The spring unit  10  of the pawl mechanism  7  is a piece that allows the support of the cam  9 , surrounding it, and comprises two differentiated parts, a U-shaped connection member  19  in which there are disposed substantially circular housings  20  and  21  on and extending through each one of the lateral faces of the U-shaped connection member  19 , the connection shaft  11  being housed in said housings  20  and  21 . The spring unit  10  comprises a second part connected tightly to the connection member  19 , which is a spring  22 . Said spring  22  is a piece that in one implementation is a metal strip made of spring steel or a material of similar characteristics, which is connected at one end to the base of the U of the connection member  19  and at the other end is supported on a lateral face  18  of the cam  9 . The spring  22  exerts a force on said cam  9  in the direction of the lateral face  18 , allowing said cam  9  to swing around the shaft  11  that connects the cam  9  to the spring unit  10 . 
     In one implementation the cam  9  is a substantially flat piece with an elongated shape, which comprises a first end  12  next to which there is disposed a substantially circular housing  13  that passes through the cam  9 , in which is housed the shaft  11 . Beside the housing  13  and extending along the cam  9  is comprised an arm  14 , which presents a second end  15  on the opposite end of the first end  12  of the cam  9 , and a projection  16  that is disposed on a lateral face  17 , opposite the lateral face  18  of said arm  14 . In the positioning of the safety device  6  on the cover  40  of the mechanism  2 , the cam  9  is positioned vertically and passes through the cover  40 , the projection  16  being disposed projecting out of the cover  40 , and the second end  15  remaining beneath the cover  40 . The teeth  30  of the crown gear  24  are disposed facing the position of the second end  15  of the cam  9 , beneath the cover  40 . As a result, and due to the force exerted by the spring  22  of the spring unit  10 , when the safety device  6  is in the active position the second end  15  of the cam  9  connects to the crown gear  24 , it being capable of being housed in the gap between two of the teeth  30  of the crown gear  24 . 
     The drive guide  8  of the safety device  6  is a piece that allows the tool  5  to be guided when the user decides to act on the mechanism  2  of the unit by means of the power shaft  50 , and also allows the spring unit  10  to be supported along with the cam  9 . Said drive guide  8  comprises two differentiated parts: a cylindrical guide  25  whose inner body is hollow and which allows the end  23  of the drive shaft  4  to be housed, surrounding it, and two substantially flat supports  26  and  27  that project out of a lateral opening of the cylindrical guide  25  and run along the height of said cylindrical body. Said supports  26  and  27  are disposed with substantially circular housings  28  and  29  on and extending through each of their lateral faces next to the upper part of said lateral faces, with the result that the cam  9  is housed in a vertical position between the two supports  26  and  27 , and the spring unit  10  holds, with the connection member  19 , the two supports  26  and  27 . The housing  13  of the cam  9 , the housings  20  and  21  of the connection member  19 , and the housings  28  and  29  of the supports  26  and  27  coincide when the cam  9  and the spring unit  10  are positioned in the supports  26  and  27 , and the connection shaft  11  of the drive guide  8  is inserted through said housings. The drive guide  8 , as it forms part of the safety device  6 , is disposed on the cover  40  of the mechanism  2 , and is connected in one implementation to the cover  40  by means of a plurality of flaps  31  disposed in the lower area of the cylindrical guide  25  and the supports  26  and  27 . Additionally, and in order to make the connection rigid, in one implementation the cover  40  comprises a plurality of holes  32 , with the result that the connection is performed by inserting the flaps  31  in the holes  32  and folding said flaps  31  on the cover  40  in a process that may be a stamping process. 
       FIG. 4  shows a perspective view of the safety device  6  of the unit, having been eliminated from said view the cover  40  of the mechanism  2  in order to show both the cylindrical guide  25  and the supports  26  and  27  with the flaps  31  folded, and the complete assembly of the safety device  6  with the drive shaft  4  in view. In this situation the end  23  of the drive shaft  4  is free without the tool  5  acting on it, and said end  23  is surrounded by the cylindrical guide  25 . The cam  9  with the second end  15  is housed in the gap between two teeth  30  of the crown gear  24 , as a result of which the safety device  6  is in the active position, cooperating with the mechanism  2  through the drive shaft  4  of the power shaft  50 . As can be seen in  FIG. 4 , between the inner diameter of the cylindrical guide  25 , and the outer diameter of the end  23  of the drive shaft  4  there is a space  33  that allows the end of the tool  5  to be housed, by sliding it.  FIG. 5  shows a perspective view of the pawl mechanism  7  of the safety device  6  of the unit, without the cover  40  and without the drive guide  8 . The tool  5  is not acting on the end  23  of the drive shaft  4 , with the result that due to the elastic action of the spring  22  that exerts a pushing force on the cam  9 , the second end  15  of said cam  9  connects to the crown gear  24 , said second end  15  being disposed pushing against the crown gear  24 , preferably between two consecutive teeth  30 , and the projection  16  being disposed in the space  33  between the cylindrical guide  25  and the end  23  of the drive shaft  4 , as shown in  FIG. 4 . In said situation the safety device  6  is in the active position, but does not act against the rotation of the drive shaft  4  of the power shaft  50 , because in normal situations with the wheel being picked up it locks said rotation, preventing the movement of the cable  3 , and the drive shaft  4  does not move. 
       FIG. 6  shows a perspective view of the pawl mechanism  7  of the safety device  6  of the unit without the cover  40  and without the drive guide  8 . In this case the tool  5  is acting on the end  23  of the drive shaft  4 , with the result that as the end of said tool  5  slides along the space  33  it encounters the projection  16 . The user continues pushing the tool  5  until the end  23  of the drive shaft is completely housed in the end of the tool  5 , and the projection  16 , on being pushed by the tool  5  moves, overcomes the pushing force of the spring  22 , and moves the cam  9  in its entirety. As a result, the second end  15  of the cam  9  moves, disconnecting itself from the crown gear  24 . In said situation the safety device  6  is in a non-active position, releasing the drive shaft  4  of the power shaft  50  from the passive locking in which it found itself in the active position of the safety device  6 , and the user may rotate the tool  5  to wind or release the cable  3 , and with it the wheel. 
     It is known that due to, for example, impacts and vibrations in the movement of the vehicle, above all when the user has not totally picked up the wheel and there is a space between said wheel and the chassis of the vehicle, the irreversibility of the power shaft  50  fails and said shaft becomes reversible, it being capable of rotating and transferring the rotation to the drive shaft  4 , releasing cable and causing the wheel to fall to the ground. In these cases, when the tool  5  is not acting on the drive shaft  4  and therefore the safety device is in the active position and the power shaft  50  is in passive locking, if said power shaft  50  fails and becomes reversible and the drive shaft  4  starts to rotate, the second end  15  of the cam  9 , which is pushing the crown gear  24 , preferably between two consecutive teeth  30 , locks said rotation preventing the movement of the cable  3  and the wheel from falling to the ground. The case may arise in which the second end  15  of the cam  9  pushes the crown gear  24 , not between two consecutive teeth  30 , but in an intermediate position between said teeth  30 . In said case, when the drive shaft  4  tries to rotate, all that happens is that either the locking is maintained because the pushing force of the spring  22  is greater than the rotary force of the crown gear  24 , or the rotary force overcomes the force of the spring  22  and causes a slight movement of the crown gear  24  that positions the second end  15  between two consecutive teeth  30 , it not moving from this position and maintaining the locking of the power shaft  50 . The slight rotation caused either does not affect the falling of the cable or it is imperceptible, due to the reducing effect of the power shaft  50 , which may, for example, be ⅛th, which means to say that the cable may move ⅛th of the corresponding sector in degrees to a tooth (for example, if the crown gear  24  has thirty two teeth  30 , it would correspond to ⅛th of 5°, in other words a virtually insignificant amount). As a result, it may be seen that the safety device  6  locks the power shaft  50  regardless of its position of rotation. 
     In the implementation described above, the operating procedure of the unit for picking up spare wheels can involve two phases:
         A first phase in which the end of the tool  5  is housed in the end  23  of the drive shaft  4 , the safety device  6  moves to a non-active position, and the power shaft  50  may be rotated to wind or release the cable  3  and with it the wheel.   A second phase in which the tool  5  is withdrawn from the drive shaft  4  and the safety device  6  moves to the active position, the second end  15  of the cam  9  being positioned pushing against the crown gear  24 , the power shaft  50  being itself in a passive locking situation for as long as its irreversibility does not fail and it starts to rotate, in which case the safety device  6  locks said rotation. As a result, the safety device  6  moves to the active position automatically when the tool  5  is withdrawn from the drive shaft  4 .       

     In another implementation not shown in the figures, the safety device  6  comprises one more member, such as a lid or another member with the same function, which for example covers the end  23  of the drive shaft  4  and is related to the activation and deactivation of the cam  9  from the crown gear  24  of the drive shaft  4 . In this implementation the phases involved in the operating procedure of the unit for picking up spare wheels may be:
         A first phase in which the user firstly withdraws the lid or the similar member and uncovers the end  23  of the drive shaft  4 , the safety device  6  moving to a non-active position, and may move the power shaft  50  by acting on it with the tool  5 , winding or releasing the cable  3  and with it the wheel.   A second phase in which, the lid being disposed with an automatic restart mechanism such as a spring, when the tool  5  is withdrawn the lid closes to cover the end  23  of the drive shaft  4  once more, and the cam  9  is activated once again through its second end  15  against the crown gear  24 . The power shaft  50  thus is itself in a passive-locking situation for as long as its irreversibility does not fail and it starts to rotate, in which case the safety device  6  locks said rotation. As in the first implementation, the safety device  6  automatically moves to an active position when the tool  5  is withdrawn from the drive shaft  4 , the difference being that the movement to the non-active position in this second implementation is performed on opening the lid or the similar mechanism and not on housing the tool  5  in the drive shaft  4 .       

     An added advantage of the unit is that it may be used with mechanisms that are disposed with a power shaft of any type, with the result that it is very versatile. It also allows customers buying these units to dispense with a safety device for supporting the main shaft with the wheel. If said additional safety device is dispensed with, the spare wheel would fall to the ground should the cable  3  break. However, said risk may be minimised by using a thicker cable  3 , a sufficiently safe and cheaper alternative thereby being obtained.