The present invention relates to a linear dual actuator for articles of lying and sitting furniture with two sections adjustable around a rotary shaft each, said dual actuator comprises a housing with a recess at either end for each of the rotary shafts on the article of furniture, and where either end of the housing is furnished with an electrical drive for adjusting the respective sections. The invention further relates to an article of lying or sitting furniture. Electrically driven linear dual actuators for home beds, where the back rest and leg rest section of the bed can be adjusted, were invented in the late 1980s, cf. for instance DE 38 42 078 C2 Dietmar Koch and EP 0 372 032 B2 Eckhart Dewert. In the bed there is a transverse shaft for the back rest and the leg rest section respectively, said shafts are equipped with an arm, which is actuated by the dual actuator to adjust the sections, typically back rest and leg rest section. The introduction of this type of actuator for the private bed market resulted in a significant interest in electrically adjustable beds, as it concurrently therewith was followed by a simultaneous development of the product in order to bring the furniture into a price range, which made this more commonly accessible. A decisive difference in favour of the dual actuator was that it unlike the known constructions as a complete unit, without the use of tools, can be mounted on the bed. The dual actuator is simply mounted by opening a cover over the recesses and lifting it up under the bed onto the rotary shafts and when the covers are closed it will be suspended on the rotary shafts ready for operation. The electronics necessary for driving and controlling the dual actuator is also contained in the housing cf. e.g. also

WO2004/032687 Al to Dewert Verwaltungs GmbH and EP 2 001 339 B l to Linak A/S. The only exception is that the power supply in some cases is placed outside of the housing. Previously, the power supply was typically a transformer-based low- voltage DC power supply, while it nowadays can also be a switch mode or mains voltage. The electronics typically consist of a controller and possibly also parts of the power supply mounted on a printed circuit board, e.g. rectifiers (H-bridges), just as there can be various extra electrical equipment, such as e.g. an orientation light (under bed light), sender/receiver for connection with a smart phone or a tablet with various apps. Connected to the controller are end stop switches and/or encoders or potentiometers for indicating the position of the back rest and leg rest section. In that connection the controller can also be equipped with a processor, which allows the user to preprogram different desired positions for the back rest and leg rest section.

As for linear actuators including dual actuators for use in articles of furniture a duty cycle e.g. 10% (i.e. the actuator can run for 2 minutes and should idle afterwards for 18 minutes) is established as a rule to ensure that these are not overloaded. Even though the electronics comply with the common quality and standard requirements, the possibility of unintended errors in the electronics can however not be ruled out, not even despite that fact that various measures has been taken in regard to the electrical system in order to counter unintended errors in the electronics, e.g. in the form of fuses, monitoring of the power consumption e.g. as stated in WO 02/091539 to Linak A/S or by means of duty cycle guard. Another example is WO 2013/163353 Al to Linak A/S, which concerns a monitoring built into the printed circuit board. In order to counter fire risks from short-circuit or superheating in the electronics due to an unintended error in this, the housing of the dual actuator is typically made from a plastic material with flame-retardant. Thus, the housing will constitute a considerable portion of the manufacturing costs of the dual actuator.

The purpose of the invention is to reduce manufacturing costs for a dual actuator without compromising on the safety.

This is achieved according to the invention by designing the dual actuator as stated in claim 1, i.e. in that the printed circuit board is completely or partly surrounded by a heat shield of metal or a similarly hear-resistant material. Thus, it becomes possible to manufacture the housing of the dual actuator from a plastic material without flame-retardant, at which the manufacturing costs of the dual actuator are considerably reduced. As example of a material with similarly heat-resistant properties as metal can e.g. be mentioned ceramic materials. The heat shield will prevent direct thermal radiation towards the housing in case of a defect in the printed circuit board and/or its electronic components. In a preferred embodiment the heat shield is made from iron, such as the tin plated sheet metal, where the heat shield can be manufactured by a simple punching and bending. A heat shield of metal further has the advantage of being heat conducting and thus distributes heat, e.g. heat from hotspots of the electronics, evenly over the entire heat shield, which also eases cooling. In addition such a heat shield would during normal operation be contributing to distributing the heat and lowering the temperature for the printed circuit board, which in general will increase the service life of this.

Expediently, the printed circuit board is only or in all essentials only equipped with electronics components on one side, and the heat shield is designed and mounted such that it extends downwards along this side and over the upper edge of the printed circuit board. When the heat shield extends over the upper edge of the printed circuit board it is in order to prevent possible sparking from moving upwards.

In a further embodiment the heat shield is moreover correspondingly extended under the lower edge of the printed circuit board. In this embodiment the part of the heat shield, which is extended under den the lower edge of the printed circuit board, is expediently terminated in an edge (low wall), which reaches a distance up on the other side of the printed circuit board, such that a groove appears under the printed circuit board. The groove thus functions as a collector in case an unintended error causes a component or peelings from the printed circuit board itself to fall off.

In an embodiment the heat shield is expediently designed such that it follows the inner contour of the housing. In an embodiment where the housing is designed with a recess over the printed circuit board the heat shield has four runs - where the first run extends downwards along the side of the printed circuit board, which is equipped with the electric components, the second run, which is a perpendicular bending on the first run, extends over the upper edge of the printed circuit board, the third run, which likewise is a perpendicular bending, extends towards the upper side of the housing, and the fourth run is a further perpendicular bending, which extends below the upper side of the housing. The heat shield thus follows the contour of the housing and protects this. As to the retention of the heat shield this can be achieved in various ways. The heat shield can thus be retained with the edges in one or more grooves in the housing. Alternatively, the heat shield can be retained by means of one or more spring legs in the housing cooperating with one or more recesses in the heat shield. In both cases the mounting of the heat shield is carried out without the use of tools.

The invention further relates to an article of lying or sitting furniture with at least one section, which with one end is rotatably embedded around an axis in the article of furniture, and where the section can be adjusted with a rotary shaft coupled directly or indirectly to the section, and where the rotary shaft is fitted with an arm, by means of which the rotary shaft can be brought to rotate and thus adjust the section, and a linear dual actuator according to one or more of the claims 1-8 mounted on the rotary shafts, such that the arm on the rotary shaft is or can be brought into engagement with the sliding element of the dual actuator.

In an embodiment the article of lying and/or sitting furniture comprises two adjustable sections, where each section with one end is rotatably embedded around a shaft in the article of furniture, and where each section can be adjusted by means of the respective rotary shafts coupled directly or indirectly to the section, and where each of the rotary shaft is fitted with an arm with which the rotary shafts can be brought to rotate and thus adjust the respective sections.

An example of a slatted frame and dual actuator will be described more fully below under reference to the accompanying drawing. The drawing shows:

Fig. 1, a slatted frame shown with elevated back rest and leg rest section, fig. 2, a dual actuator seen directly from the side,

fig. 3, the dual actuator in fig. 2, where one part of the cabinet has been removed,

fig. 4, an enlargement of the end of the dual actuator in fig. 3, which operates the leg rest section, fig. 5, the dual actuator, where one part of the housing as well as cover, rotary shaft and arm at that end of the dual actuator which operates the leg rest section of the bed has been removed, and

fig. 6, a cross section down the middle of the dual actuator.

The slatted bed shown in fig. 1 comprises a frame 1, in which a back rest section 2 and an articulated leg rest section 3 is rotatably embedded around an axis. In the frame a transverse shaft 4 is embedded for the back rest section 2, which shaft is furnished with an arm 5. At each end of the shaft 4 a rod 4a is mounted, which with its free end is rotatably connected to the back rest section. Correspondingly, there is a transverse shaft 6 with an arm 7 for the leg rest section 3. The ends of the shaft 6 are in a corresponding manner furnished with a rod 6a rotatably connected to the leg rest section 3. The adjustment of the back rest and leg rest section 2,3 is brought about by means of a dual actuator, which comprises a housing 8 with a drive and an opening cover 9 at each end. The housing 8 is designed as two half-shells with the parting line running down the middle in the longitudinal direction of the housing. In the shown embodiment the two half-shells are assembled by means of screws, cf. the screw towers located along the edge in fig. 5. Alternatively, the two half-shells can be welded or glued together. With reference to the end of the dual actuator which operates the leg rest section, the cover 9 provides access to a recess 10 in the sidewalls of the housing for the transverse shaft 6 for the leg rest section 3. In connection with the recess 10 there is, as mentioned, a drive comprising an electric motor 11. Through a transmission 12 this electric motor 11 drives a spindle unit 13, comprising a spindle 13a and a spindle nut 13b. The transmission 12 comprises a first worm gear 15 where the worm 15a is designed in continuation of the motor shaft. The worm 15a is guided with its front end in a recess designed as a journal bearing located in a transverse wall 8a in the housing 8. The worm 15a is in engagement with a worm wheel 15b located next to the worm 15a. This worm wheel

15b is mounted on a vertical shaft 16 embedded in the housing. The transmission 12 further comprises a second worm gear 17 where the worm 17a is mounted on the opposite end of the shaft 16 than the worm wheel 15b. The worm 17a is in engagement with a worm wheel 17b. The worm wheel 15b and the worm 17a is with an intermediate pipe piece 16a cast as a unit with the shaft 16 as a through-going steel shaft, which provides strength to the unit. The spindle nut 13b is arranged in the worm wheel 17b and this worm wheel 17b is with a ball bearing 18 embedded in the housing 8, as the worm wheel 17b on its side is furnished with a bushing for the bearing 18. A sliding element 19 is secured to the end of the spindle 13a which faces towards the arm 7 on the rotary shaft 4 of the leg rest section 3. When the spindle nut 13c is brought to rotate the spindle 13a will, together with the sliding element 19, be displaced axially in one or the other direction depending on the direction of rotation of the spindle nut 13c. It is noted that the sliding element 19, which has a rectangular cross-section is guided in a guideway 20 in the housing 8 and is thus secured against rotation. The front end 19a of the sliding element 19 is designed as a contact surface for the arm 7 on the shaft 4 of the leg rest section 3. With its end 7a the arm 7 rests loosely against the end 19a of the sliding element 19. When the sliding element 19 is set in motion towards the end of the housing, it presses with its front end 19a against the arm 7 on the shaft 6, causing the shaft to rotate such that the leg rest section 3 is raised. Correspondingly, when the sliding element 19 is brought to move towards the center of the housing the leg rest section 3 will be lowered as the load of the leg rest section 3 will press the end of the arm 7a against the front end 19a of the sliding element 19.

The drive and the end of the housing at the other end of the dual actuator are constructed in a similar manner and operate the back rest section 2. In the figures the same reference numerals are used for the same elements. I fig. 3 the drive unit and thus the sliding element 19 is shown in a position, where the leg rest section 3 is in its lowered position. The drive unit and its sliding element which operates the back rest section 2 is on the other hand shown in its fully extended position corresponding to the back rest section 2 being raised to its maximum upright position.

The actuator is mounted in the slatted frame in that the covers 9 are pulled outwards and removed and the actuator is lifted up, until the shafts 4,6 rest in the recesses 10 and the arms 5,7 on the shafts reach down in front of the sliding elements 19. The covers 9 are reattached and closed, at which the actuator is suspended on the shafts 4,6. It is noted that the covers are designed as sliding covers 9 which from the side are pushed over the recesses 10. This construction contributes to the strength of the housing as the covers assist in fastening the end of the housing, i.e. the part located from the recess 10 and outwards, to the part of the housing which is located within the recess 10, i.e. towards the center of the housing.

For the electric functions associated with the actuator this comprises a printed circuit board 20, which among others comprises the controller, said printed circuit board 20 is arranged in a chamber 21 located between the two electric motors 11. The various electric components and plugs are located on one side of the printed circuit board 20, while the solderings are located on the opposite side. The printed circuit board can also, as it appears from fig. 5 be fitted with an orientation light 22, called "under bed light", specifically a number of light emitting diodes and a glass, located in a recess in the underside of the housing. The orientation light illuminates the area under and around the bed. A hand control, which can either be wireless or cable-connected, is connected to the printed circuit board 20. The orientation light 22 can be operated with a key on the hand control or by means of a sensor in the bed arranged such that the orientation light 22 is switched on and stays on for a given period of time, when the person leaves the bed.

In case a defect in the printed circuit board 20 generates abnormally much heat, which could constitute a risk of ignition the housing 8, a heat shield 23 of metal, e.g. preferably sheet metal, is arranged in the housing 8. The actual design of the heat shield is adapted to the cross-section of the housing, which in the relevant position, where the printed circuit board is located is designed with a recess 8c. In the recess 8c there is a plug 24 for connecting the dual actuator to a power supply. The plug 24 is as it appears connected to the printed circuit board. The heat shield 23 has four runs. The first run 23a of the heat shield extends downwards along the side of the printed circuit board 20, which is equipped with the electric components. The second run 23b of the heat shield, which is a perpendicular bending on the first run 23 a, extends over the upper edge 20c of the printed circuit board 20. The third run 23c, which likewise is a perpendicular bending, extends towards the upper side of the housing. The fourth run 23d is a further perpendicular bending, which extends below the upper side of the housing. The heat shield is retained for one thing by means of the plug 24, which protrudes through a recess in the housing and through a corresponding recess in the heat shield and is thus retained on the plug 24. In the heat shield there is a further recess 23e with which this reaches over a spring leg 8d on the inner side of the housing. In case a defect in one of the electric components results in development of abnormally much heat, the heat shield 23 will prevent direct thermal radiation towards the housing, just as the heat will distribute itself in the heat shield and thus evens out the temperature, i.e. prevent a high localised temperature or energy concentration. In addition the heat shield 23 would during normal operation be contributing to distributing the heat and lowering the temperature for the printed circuit board 20 in general, which overall will increase the service life of this

The invention thus discloses a dual actuator, for which it is possible to manufacture the housing from an inexpensive plastic material without flame-retardant, and where a great extent of safety against unintended fire due to an error in the printed circuit board is still achieved. It should, however, be understood that the invention is also appropriate in cases where the housing is made from a plastic material with flame- retardant. In such cases a further safety against fire due to an arisen error the printed circuit board is achieved.