Abstract:
Actuator system comprising at least one actuator, a control unit, a power supply and an operations panel, where the actuator in a transmission between an activation element ( 4 ) and a reversible electric motor is inserted a quick release unit ( 13 ) for release of the activation element ( 4 ) from the electric motor and the part of the transmission between the motor and the quick release. The actuator comprises at least one electrical switch ( 30 ), activated with the quick release. The signal from the electrical switch(es) ( 30 ) may be used for various purposes, such as triggering a power supply from sleep mode, activating one or more actuators, or activating an external function such as an alarm etc.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to an actuator assembly which has a quick release ability. 
     2. The Prior Art 
     A quick release in an actuator is used for temporary release of the activation element for manual setting without the drive unit. Examples of the potential use of a quick release are in hospital beds, patient hoists, fire doors and other constructions where it is important, if not essential, to be able to spontaneously set the activation element. 
     Actuators with quick release function are well known, for example, EP 685 662 B1, WO 03/033946 A1 and WO 2006/039931 A1 and EP 577 541 B1 all in the name of Linak A/S. The first three documents relate to a quick release construction based on a releasable clutch spring around two cylinder parts. The last document EP 577 541 relates to a quick release construction where a gear can be displaced from engagement. 
     In some situations it is desirable or essential to activate another function as a result of the quick release. Generally, this may be activation of a power supply and/or controls for the actuator and/or activation of one or more actuators simultaneously with the release of the quick release. 
     The object of the invention is to provide a solution to the problem described. 
     SUMMARY OF THE INVENTION 
     This is achieved in the invention by designing an actuator assembly which includes at least one electrical switch which is activated when the quick release is released. The signal from the electrical switch(es) may be used for various purposes, such as activating a power supply and/or control from sleep mode, activating one or more actuators, or activating an external function such as an alarm, etc. The circuit, of which the switch is part, will typically be designed for the switch to close a circuit, but the circuit may also be designed for the switch to break the circuit. The electrical contact is appropriately mounted in the actuator so that it is activated by one or more of the moveable construction elements in the quick release. Most suitably, it is the construction elements in the release mechanism itself, but it may however also be construction elements in the coupling parts of the quick release, such as the gear in the quick release as defined in EP 577 541 or a spring end or cylinder part in the constructions with coupling springs. 
     An actual implementation of the actuator system, which relates to a bed equipped with an actuator assembly, where the actuator for the back rest section comprises a quick release with an electrical switch activated by the release of the quick release. The bed is further equipped with position determination in a suitable manner. 
     A linear actuator according to the invention will be described below with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1 , shows a hospital bed with four actuators; 
         FIG. 2  shows an exploded view of an actuator with a quick release unit; 
         FIG. 3  shows a detailed view of the quick release unit; 
         FIG. 4  is a longitudinal section through another actuator; 
         FIG. 5  is a side view of the actuator of  FIG. 4 , and 
         FIG. 6  is an exploded view of the quick release unit of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  shows a hospital bed equipped with an actuator assembly comprising four actuators  101 - 104 , a control box  105  containing a power supply and a control; and a hand operation  106  and an operations panel (ACP)  107  at the end of the bed. The power supply consists of a low voltage unit, typically transformer-based, and a rechargeable battery pack. Two of the actuators  101 ,  102  are for adjustment (profiling) of the base  108  carrying the mattress, while the other two  103 ,  104  are for height adjustment of the upper frame  109  on which the base is mounted. The two last mentioned actuators also allow for tilting of the base frame over a transverse axis (Trendelenburg/Anti-Trendelenburg position). 
       FIG. 2  shows an actuator with a quick release construction of the type mentioned in WO 2006/039931, more exactly FIGS. 1-7. The main elements of the actuator are a cabinet in two parts  1   a ,  1   b  with a reversible electric motor, which through a worm gear drives a spindle  2  with a spindle nut  3 , on which an activation rod  4  (inner tube) is surrounded by a protective tube  5  (outer tube) is attached. Note that the motor is not shown in the drawing, but it is located in the perpendicular section  1   c  of the cabinet. The motor shaft extends into a worm engaging a worm wheel  6 . The spindle  2  is seated in the cabinet with a ball bearing  7 . 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  shows a hospital bed equipped with an actuator assembly comprising four actuators  101 - 104 , a control box  105  containing a power supply  105   a  and a control  105   b ; and a hand operation  106  and an operations panel (ACP)  107  at the end of the bed (operation unit). The power supply consists of a low voltage unit, typically transformer-based, and a rechargeable battery pack. Two of the actuators  101 ,  102  are for adjustment (profiling) of the base  108  carrying the mattress, while the other two  103 ,  104  are for height adjustment of the upper frame  109  on which the base is mounted. The two last mentioned actuators also allow for tilting of the base frame over a transverse axis (Trendelenburg/Anti-Trendelenburg position). 
     The quick release construction, consisting of an inner and an outer coupling part  8 , 9 , where the inner coupling part  8  is mounted at the end of the spindle  2 , while the outer coupling part  9  is mounted in the worm wheel  6 . This worm wheel is on the side facing the front end of the actuator, designed with a hollow cylindrical part that accommodates the outer coupling part  9  for torque transfer with a spline connection. 
     In the back of the worm wheel is a circular disc with three legs protruding through the openings in the worm wheel into the hollow cylindrical part and guided there. In the upper part  1   b  of the cabinet is a release mechanism  13  in a housing  14  with an entry for a cable (not shown) leading to an operating handle (not shown either). The release mechanism comprises an axle unit  15 , led down behind the circular disc  11 . At the end of the axle unit there is a cam  16  which is brought into contact with the disc  11  by turning the axle unit and the disc presses this forward towards the worm wheel. The axle unit is spring loaded with a spring  17 , to an inactive position, i.e., a position where the cam  16  is not in contact with the disc  11 . A ring  18  is attached at the upper end of the axle, to which the end of the cable leading to the operating handle is attached. 
     The outer coupling part  9 , connected to the worm wheel, has an internal torque transfer spline connection  21   a  in the front. On the outer side of the coupling part  9  at the front end, in front of the spline connection to the worm wheel, there is a flange  22 . 
     The inner coupling part  8  has a narrow part  23  in the front to enable it to pass through the opening in the part of the spline connection  21   a  placed in the outer coupling part  9 . The other part of the spline connection is part of the step between the narrow end  23  and the outer side of the coupling part. In the narrow part  23  there is a groove for a disc  24 , creating a flange. 
     The quick release is activated by operating the release mechanism, which turns the cam  16  on the axle unit  15  into contact with the disc  11 , which is then pushed forward. The spline connection  21   a ,  21   b  between the outer coupling part  9  and the inner coupling part  8  will thus be interrupted and the spline will rotate freely, independent from motor and transmission. The activation rod  4  of the actuator and therefore the element attached to it, will then be manually adjustable. 
     An electrical contact in the form of a micro switch is placed next to the turning axle  15 , and a cam opposite to cam  16  activates the micro switch at the same time as the quick release is activated. This sends an electrical signal through the cable connection to the control unit, which is brought from sleep mode, more precisely the power supply for the control is activated, that is, the part of the power supply comprising the rechargeable battery pack. By keeping the battery pack switched off until it is required, i.e. use ‘on demand’, means a substantial saving in the battery pack power. When the bed is connected to mains power, the low voltage unit is active. Placing the switch in the actuator itself has the advantage that further cabling is avoided and only a cable for the actuator is required. 
     When the bed is without mains power and the back rest section  110 , must be moved rapidly to the horizontal position, such as in the case of a patient with cardiac arrest, this is achieved by activating the quick release. Simultaneously the control is brought from sleep mode and the bed becomes fully operational. The leg section  111  may be moved to horizontal position and, if required, may be brought into Trendelenburg position. 
     In  FIGS. 4-5 , the actuator shown is the same type as specified in WO 2006/039931 Linak A/S, specifically in  FIGS. 8-15 , and this is referred to as part of the present application. In  FIG. 4  to elements labeled  2 ′,  6 ′,  8 ′,  9 ′ and  14 ′ correspond to elements  2 ,  6 ,  8 ,  9  and  14  in the  FIGS. 2-3  embodiment. The quick release construction itself is shown in  FIG. 6 . The release mechanism consists of a tilting element  27 , that takes an inclined resting position. An axially sliding element  28  with a hook at the end grabs the tilting element and is connected to the operating handle by a cable. By operating the handle, the element  28  is pulled upwards and brings the tilting element  27  to a vertical position, releasing the quick release as previously described. 
     The inner coupling part  8  is equipped with a magnetic ring  31  with four poles used to determine the position of the activation rod  4 . Two Hall-elements, or sensors,  33   a ,  33   b  are mounted on a small printed circuit board  32  in conjunction with this. The Hall-elements are activated when a pole passes these on rotation of the magnetic ring, thereby sending a signal to the control unit which, by means of a microprocessor, computes the position of the activation rod  4  based on the rotation, its direction and the thread pitch of the spindle. Because the two Hall-elements are angularly displaced in relation to the magnetic ring  31 , the rotation direction of the spindle can be detected (quadrature detection) and determines if signals must be added or subtracted depending on the extension or retraction of the activation rod  4 . As the magnetic ring  31  is mounted to the inner coupling part  8 , the ring  31  always rotates with the spindle, i.e., also in the situation where the spindle is released from the motor/transmission. In this way the position of the activation rod is known at all times, also after activation of the quick release. 
     The actuator illustrated in  FIG. 2  may be similarly equipped with a magnetic ring on the inner coupling part and Hall-elements, hence the position of the activation rod is also known in this case, regardless of whether the quick release has been activated or not.