Patent Abstract:
Disclosed is a lifting column for lifting a load, such as a vehicle, which includes a frame with a movable carrier and a drive which acts on the carrier; control means for control of the drive; a carrying part attached to the carrier for carrying the load; weight measuring means attached to the carrying part for measuring the weight of the load; and communication means for communicating a measurement signal of the weight measuring means indicative of the weight of the load to the control means.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Patent Application No. 61/735,102 and The Netherlands Patent Application No. 2009949, both filed Dec. 10, 2012, the disclosures of which are hereby incorporated by reference in their entirety 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a lifting column for lifting a load, such as a vehicle. Such lifting columns are in particular used for lifting motor vehicles including buses and trucks and may relate to lifting columns of the two-post lift type with pivoting support arms, the four-post lift type with runways, the mobile type etc. 
     2. Description of Related Art 
     A lifting column known from practice comprises a frame with a carrier that is connected to a drive for moving the carrier upwards and downwards. In the ascent mode hydraulic oil is pumped to a cylinder for lifting the carrier, and thereby the vehicle. In the descent mode the carrier with the vehicle is lowered and hydraulic oil returns to the reservoir. Lifting columns are designed for a maximum load. Lifting a load with a weight above this maximum leads to unsafe operation of the lifting columns possibly causing accidents with the risk of operators getting injured and vehicles and equipment getting damaged. 
     The present invention has for its object to provide a lifting column obviating or at least reducing the aforementioned problems. 
     SUMMARY OF THE INVENTION 
     This objective is achieved with a lifting column for lifting a load, such as a vehicle, according to the present invention, the lifting column comprising:
         a frame with a movable carrier and a drive which acts on the carrier;   control means for control of the drive;   a carrying part attached to the carrier for carrying the load;   weight measuring means attached to the carrying part for measuring the weight of the load; and   communication means for communicating a measurement signal of the weight measuring means indicative of the weight of the load to the control means.       

     By providing the carrying part of the lifting column with weight measuring means, the weight of a load can be measured. More specifically, the weight of a vehicle that is lifted by the lifting column is measured. The communication means communicate a measurement signal that is determined by the weight measurement means and is indicative for the weight of the load that is lifted to the control means. Preferably, the central controller is part of these control means. 
     The lifting column according to the invention may relate to lifting columns of the two-post lift type with pivoting support arms, the four-post lift type with runways, the mobile type etc. 
     By providing the controller with weight information of the load the (central) controller knows that a vehicle is present on the carrying part of the carrier. For example, in case of a mobile lifting column the controller may prevent moving the lifting column and/or selecting the lifting column for another group. Furthermore, the controller may perform a check to see whether the weight of the vehicle is below the allowed maximum weight for the specific lifting column, thereby preventing an overload situation. In addition, this check may establish a safety check whether the vehicle is placed correctly relative to the lifting column. 
     In a presently preferred embodiment the control means that are configured for control of the drive directly or indirectly receive information from the weight measuring means, such as a load sensor. This information is indicative for an authorization to proceed with the lifting operation and/or a command to abort the lifting operation, for example due to a detection of an overload or misalignment of the vehicle on the lifting column. The information from the weight measuring means is preferably received and treated by a central controller. The central controller provides an individual lifting column of a set of lifting columns with the relevant commands, for example for the drive thereof, optionally through the use of an individual controller of a lifting column. 
     Weight measuring means convert a force caused by the weight of the vehicle that is lifted into an electrical signal. A possible embodiment of the weight measuring means comprises a so-called Wheatstone bridge configuration. For heavier loads an embodiment using a cylinder may be used. Such embodiment enables measuring the deformation as the effective electrical resistance is changed due to the load. Alternative embodiments include the use of piezo-electric load cells and capacitive load cells using a change of the capacitance of the capacitor as indication of the weight of the load. In a presently preferred embodiment the weight measuring means comprise a rubber pad filled with a fluid or gel. The pressure inside the pad is measured with a pressure sensor and represents a measure for the weight. This embodiment can be applied to a lifting column of the two-post lift type. In an alternative embodiment that can be applied to a lifting column of the four-post lift type the pad is positioned under the runways, preferably at or close to one of both outer ends thereof. 
     The communication means may involve the use of cables connecting the lifting column to a central controller enabling exchange of data representing the measurement signal of the weight measuring means and/or operating instructions, for example. 
     Preferably, the communication means comprise a transmitter and receiver for wireless communication between the weight measuring means and the control means. The use of wireless communication means may involve the use of Bluetooth, Wi-Fi and/or Ultra Wide Band, for example. Wireless communication prevents the use of cables across the workshop. This improves safety and flexibility for the users of the system. In case the lifting column is a mobile lifting column a battery can be provided to improve the flexibility of the overall lifting system even further. This is especially beneficial for the two-post lifting system with moveable arms. 
     In a presently preferred embodiment according to the present invention the weight measuring means comprise an energy supply. 
     By providing an energy supply the weight measuring means can collect measurement data and transfer the measurement signal to the (central) controller without requiring a separate energy supply. The use of a specific energy supply for the measurement means enables performing the measurement and communicating the data autonomously. By providing the energy supply together with the measuring means to the carrier, and more specifically to the carrying part thereof, energy supply cables can be omitted from the lifting system. 
     Preferably, the energy for the weight measuring means is provided by the vehicle to be lifted. More specifically, the energy is delivered by gravity when lifting the vehicle. This prevents any requirements for external equipment to provide energy. 
     In a presently preferred embodiment according to the present invention the weight measuring means comprise a piezo-element for generating energy for the energy supply. When a vehicle is positioned on the carrying part, the piezo-element generates a small amount of energy that can be used for the energy supply to the weight measuring means for performing a measurement and communicating a measurement signal to the controller via the communication means. Energy is provided by the vehicle to be lifted, more specifically by gravity when lifting the vehicle. Therefore, no cables and/or external energy sources are required. 
     In a presently preferred embodiment the energy supply comprises an energy collector for storing the generated energy. This enables storage of energy to be used at the appropriate moment, for example to transfer data via the communication means to the control means. In a presently preferred embodiment the energy collector comprises a capacitor to (temporarily) store energy for use by the weight measuring means and/or the communication means associated therewith. 
     In a further preferred embodiment according to the present invention the energy supply comprises electromagnetic means for wireless transfer of energy to the weight measuring means. 
     By providing electromagnetic means an electromagnetic field can be achieved. Preferably, the field is operated by the (central) controller. This enables providing the weight measuring means with energy for performing the weight measurement including transferring data with the communication means to the control means. This enables a standalone weight measurement that in a presently preferred embodiment is integrated in the central controller. 
     Preferably, the control means comprise operating means for controlling the electromagnetic means. This enables the control means to activate the measurement when required, for example when starting a lifting movement. This results in an energy efficient system. 
     Preferably, the control means are configured for control of a lifting column or components thereof. In a presently preferred embodiment the control means involve a controller of a first lifting columns acting as master or central controller, and controllers of further lifting columns belonging to the same set of lifting columns acting as slave or local controllers. It will be understood that other configurations of the control means according to the invention are possible. The control means are preferably configure to activate the measurement, receive and treat the measurement data, and send commands to the lifting column(s) and/or components thereof. Next to sending commands and controlling the lifting operation the control means may provide an indication of the load or weight that is measured to the user, operator, driver, or other person. This indication may involve a visual indication that is provided on a display, such as a touch screen, of the control means. Other indication including sound signal may also be applied, for example when an overload is detected. 
     The invention further relates to a lifting system comprising one or more lifting columns as described above. 
     Such a lifting system provides the same effects and advantages as those stated with reference to the lifting column. The lifting system preferably uses two, four, six, or even more lifting columns, operating in pairs. Preferably, the control means comprise safety means that are activated when the measurement signal indicates an overweight. This provides additional safety to the lifting system. 
     The invention furthermore relates to a load sensor for measuring a load on a lifting column and/or lifting system. 
     Such load sensor provides the same effects and advantages as those stated with reference to the lifting column and/or lifting system. Preferably, the sensor can be used in a lifting system and/or lifting column described above. In a preferred embodiment the load sensor according to the invention comprises an energy generator and/or an energy collector to provide a stand-alone sensor. Preferably the sensor shares its findings with a controller or control system to provide additional safety checks, for example checking an overload.
         The invention furthermore also relates to a method for measuring a load on a lifting column, the method comprising:   providing a lifting system with a number of lifting columns as described above; and   measuring the load.       

     Such method provides the same effects and advantages as those stated with reference to the lifting column and/or lifting system. Preferably, the method uses the load sensor according to the invention as described earlier. Preferably, the measurement data is provided to the control means, such as the central controller, for example. This enables checking the position of a vehicle relative to a lifting column preventing damage to the columns by an overload and/or providing additional safety to a lifting operation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further advantages, features and details of the invention are elucidated on the basis of preferred embodiments thereof, wherein reference is made to the accompanying drawings, in which: 
         FIG. 1  shows a schematic overview of a vehicle lifted by lifting columns according to the invention; 
         FIG. 2  shows a lifting column according to the invention; 
         FIG. 3  shows an alternative embodiment of a lifting column according to the invention; 
         FIG. 4  A-B shows a load sensor according to the invention; and 
         FIGS. 5-7  show alternative embodiments of lifting columns according to the invention. 
     
    
    
     DESCRIPTION OF THE INVENTION 
     A system  2  for efficient lifting and lowering a load ( FIG. 1 ) comprises four mobile lifting columns  4  in the illustrated embodiment. Lifting columns  4  lift a passenger car  6  from the ground  8 . Lifting columns  4  are connected to each other and/or a control system by wireless communication means or alternatively by cables. Lifting columns  4  comprise a foot  10  which can travel on running wheels  12  over ground surface  8  of for instance a floor of a garage or workshop. In the forks of foot  10  is provided an additional running wheel (not shown). Lifting column  4  furthermore comprises a mast  14 . A carrier  16  is moveable upward and downward along mast  14 . Carrier  16  is driven by a motor  18  that is provided in a housing of lifting column  4 . Motor  18  is supplied with power from the electrical grid or by a battery that is provided on lifting column  4  in the same housing as motor  18 , or alternatively on foot  10  (not shown). Control panel  20  is provided to allow the user of system  2  to control the system, for example by setting the speed for the carrier  16 . 
     A column  22  ( FIG. 2 ) of a lifting system  24  is a mobile lifting column that communicates by transmitter-receiver  26  to a transmitter-receiver  28  of a central controller  30 . A connection  32  to the electrical grid is provided on a side wall  33  in the neighbourhood of controller  30 . Sensor  34  is capable of measuring a load of vehicle  6  carried by carrying part  36 . The resulting measurement signal is communicated via transmitter  38  to transmitter-receiver  28  of controller  30  directly or indirectly through transmitter-receiver  26 . Controller  30  may send data to lifting column  22  such as an activation signal for sensor  34  using transmitter-receiver  28  and receiver  40 . It will be understood that transmitters and/or receivers  26 ,  38 ,  40  can be combined or separated. In the illustrated embodiments sensor  34  is a piezo-electric sensor. 
     In an alternative embodiment a lifting column  42  of lifting system  44  ( FIG. 3 ) comprises load sensor  46 . Energy supply system  48  comprises a piezo-element  50  that generates energy when a load is positioned over carrying part  36 . The energy is stored in capacitor  52  that is used to transmit data to controller  30 . 
     A sensor  54  ( FIG. 4  A-B) comprises pressure plate  56 . Below plate  56  an illustrated gel-pad  58  is provided that rests on a stationary plate  60 . In the illustrated embodiment plate  60  is connected by weld  62  to housing  64 . Channel  66  brings the gel of pad  58  into contact with pressure sensor  68 . Processing module  70  determines the measurement signal  72 . Transmitter  74  sends signal  76  representing the load acting on sensor  54 . In the illustrated embodiment channel  78  brings gel of pad  58  into contact with power generator  80 . The generated energy can be stored in power buffer  82  and used by transmitter  76 . 
     In a presently preferred embodiment pressure sensor  68  comprises a thin film and/or semiconductor, power generator  80  comprises a piezo-element, and buffer  82  comprises a capacitor and/or a rechargeable battery. 
     When measuring a load of vehicle  6 , carrying part  36  that is lifted by carrier  16  of lifting columns  4 ,  22 ,  42  receives an activation signal from controller  30  using transmitter/receivers  26 ,  28 ,  38 ,  40  for activating sensor  34 ,  46 . Sensor  34 ,  46  performs the measurement and transfers the measurement data to controller  30  using the same or similar transmitter/receivers. The energy required for sensor  46  is in one of the illustrated embodiments of lifting column  42  provided by piezo-element  50  and capacitor  52 . This obviates the need to provide additional cables for the measuring system. In another embodiment the energy required for sensor  46  is provided by electromagnetic means  54  that are preferably activated by controller  30 . 
     In addition, controller  30  may perform additional tasks using the measurement signal including a check to prevent overweight. In case an overweight is established, controller  30  may prevent operation and more specific load lifting by lifting column  4 ,  22 ,  42 . For example, when lowering a vehicle a load sensor may detect a small overload of column  4 ,  22 ,  42  such that controller  30  may stop the operation. Furthermore, controller  30  may check the correct positioning of vehicle  6  over a pair of lifting columns  4 ,  22 ,  42  of lifting system  24 ,  44 . Also, controller  30  may provide an operator with a clearance signal if necessary and/or a warning signal in case of a problem. 
     The present invention can be applied to the (wireless) lifting columns illustrated in  FIGS. 1-3 . Alternatively the invention can also be applied to other types of lifting columns and lifting systems. 
     For example, a four-post lifting system  102  ( FIG. 5 ) comprises four columns  106  carrying runways  106 . Columns  104  comprise a sensor  108 , preferably each column  104  has one sensor  108 . In the illustrated embodiment an indicator  110  with a green light  112  and a red light  114  is provided. Light  110  signals to the driver when vehicle  6  is positioned correctly relative to columns  104  and the vehicle  6  can be lifted. In case each column  104  is provided with sensor  108  the position of vehicle  6  on carriage way/carrier  106  can be checked. In addition, the individual load for a specific lifting column  104  can be checked. This contributes to the overall safety of the lifting operation. Furthermore, by preventing overloads to occur in practice columns  104  can be designed effectively thereby reducing costs. 
     As a further example, lifting system  202  ( FIG. 6 ) comprises a so-called sky-lift configuration with four posts  204  carrying runways  206 . In the illustrated embodiment a sensor  208  is provided for every post  204 . This enables the check on positioning of vehicle  6  and/or the individual loads acting on a post  204  as described earlier. A light  210  with green  212  and red  214  lights can be provided on wall  216  to indicate to the driver of vehicle  6  that the vehicle is positioned correctly or needs to be repositioned. 
     As an even further example, lifting system  302  ( FIG. 7 ) comprises a so-called two-post configuration with two posts  304  that are provided with carrier arms  306 . In the illustrated embodiment carrier arms  306  are provided with sensor  308 . This enables the check on positioning of vehicle  6  and/or the individual loads acting on a post  304  as described earlier. A light  310  with green  312  and red  314  lights can be provided to indicate to the driver of vehicle  6  that the vehicle is positioned correctly or needs to be repositioned. 
     It will be understood that the invention can be applied to a range of lifting systems, including but not limited to four-post and two-post lifting columns, skylift, and mobile columns. Also, it will be understood that additional embodiments of the invention can be envisaged combining and/or switching features from the described and/or illustrated embodiments. For example, instead of light  110 ,  210 , or in addition thereto, sound signals, indications on a control system etc. can be applied. 
     Providing signals, such as warning signals of an overload or misalignment of the vehicle, can be provided in numerous ways. This may involve the use of lights, sounds, visual indications on a display, such as a touch screen, of a lifting column, etc. 
     The present invention is by no means limited to the above described preferred embodiments. The rights sought are defined by the following claims within the scope of which many modifications can be envisaged. The present invention is described using a lifting column and more specifically a mobile lifting column and/or a lifting column of the two-post and/or four-post lift type. The invention can also be applied to other type of lifting columns such as so-called boom-lifts, scissor-lifts and loading platforms. Such lifting equipment can be provided with the measures illustrated above according to the invention.

Technology Classification (CPC): 7