EP3491211A1

EP3491211A1 - A rocker arm braking device for doors and sliding furniture doors

Info

Publication number: EP3491211A1
Application number: EP17767992.5A
Authority: EP
Inventors: Giovanni Terno
Original assignee: Terno Scorrevoli SpA
Current assignee: Terno Scorrevoli SpA
Priority date: 2016-07-27
Filing date: 2017-07-25
Publication date: 2019-06-05
Anticipated expiration: 2037-07-25
Also published as: IT201600078974A1; WO2018019415A1; EP3491211B1; PL3491211T1; BR112019000577B1; BR112019000577A2; ES2720206T3; ES2720206T1; DE17767992T1; PL3491211T3

Abstract

A rocker arm braking device (10) for doors and sliding furniture doors comprises a carriage (26', 86), sliding on wheels (26', 90) along a guide (72, 116) and fixed to the top edge of a sliding door (80) or to the top of the inner side of a sliding door (94) of a cabinet or wardrobe (96); said device further comprises a shaped support (62), having a substantially rectangular cross-section, constrained by dowel screws (82) to said guide (72, 116), which has a housing and stabilization seat on one side (64) of a cushioning means (66) laterally to which there is a cam (70) on the same shaped support (62). The device is provided with a pair of matching shaped arms (44), basically "C" shaped in which the central convex part is facing downwards, with a hole (46') at the opposite ends for inserting connection pins (46) which simultaneously stabilize between said arms two needle rollers (48, 48') to form a pivoting rocker arm (14). Said needle rollers (48, 48') are guided by the cam (70) during the movement of the carriage (26, 86) along the guide (72, 116).

Description

"A rocker arm braking device for doors and sliding furniture doors"

Description The present invention relates to a rocker arm braking device for doors and sliding furniture doors .

More in particular, the present invention relates to a device suitable to slow down and brake during closing sliding doors separating rooms or adjoining rooms and the sliding doors of cabinets or wardrobes to prevent uncontrolled and overly rapid strokes with possible kickbacks at the end stop.

It is known that in buildings intended for private homes or used for other purposes, such as offices or premises open to the public, some environments are separated from each other and made independent using sliding doors, which replace the traditional swing doors. In the manufacture of cabinets and wardrobes too, sliding doors are currently widely used, especially give the reduced occupation of space when opened. Both for doors and cabinet and wardrobe doors, sliding is achieved by means of carriages with wheels which slide along specially designed and sized guides, typically attached to the top of the opening containing the door or on the top side of the wardrobe. The carriages are combined with specific devices facilitating the closure of the door or furniture door, creating a pulling effect to accompany them to the end-stop, which is reached gradually and smoothly. It is important in fact that during closing the stroke of the door or wardrobe door is gradual and even braked in the case that it has unintentionally been subjected to an excessive push. In the absence of an accompaniment to the end stop, which slows down the sHding and cushions the abutment with the stop element, said door or furniture door would impact said end stop violendy, rebounding off it, with the consequence of creating not just a loud noise, but also the danger of damaging parts of the sliding carriage or related components and requiring subsequent manual intervention to achieve effective closing.

Devices designed to cushion the stroke when closing doors are known of for example from WO00/55460, where a bumper comprises a body suitable to be mounted in a guide, a cushioning and restraint element and a spring with one end shaped to hold a sliding mechanism; the latter may disengage from the holding spring under high impact. In this case, the solution is not suitable for doors and furniture doors of significant size and weight, which can rebound and disengage if pushed with considerable force.

EP 0877138 discloses a guide and stop mechanism of a sliding door, especially a side door of a car, which comprises a carriage with wheels cooperating with an element that defines an articulated ramp, superposing an elastomer body. When the door is opened, the rotation of the ramp and compression of the elastomer body slows down the stroke of the carriage attached to the sliding door. This solution too does not guarantee a secure attachment if the door is opened brusquely, there being no dampers to gradually accompany the carriage to the end stop.

A further solution is known from the European Patent No EP 1 640 537 by the same applicant, which refers specifically to a device for the cushioned stopping and stabili2ation of sliding doors and furniture doors. Such device comprises a carriage which slides in a section and abuts a cam; the latter can partially rotate to couple said carriage, which at the same time abuts a cushioning device, in the form of an oil, silicone or air piston. This solution, though able to ensure effective cushioning of the stroke, even violent, of sliding doors and furniture doors, has drawbacks both as regards noise, especially at the time of engaging and disengaging with the cam, and as regards movement; in the opening phase in fact the resistance of the contrast spring which extends to subsequently recall the carriage when closing the door or wardrobe door, must be overcome.

The purpose of the present invention is to overcome the drawbacks complained of above.

More specifically, the purpose of the present invention is to provide a rocker arm braking device for doors and sliding doors of cabinets and wardrobes which gradually accompanies the closing of the door or furniture door, braking the excessive speed without however causing noise.

A further aim of the invention is to provide a braking device as defined above that permits the user to close the door or the sliding furniture door smoothly without any effort or difficulty in relation to the initial thrust to be exercised.

A further aim of the invention is to make available to users a rocker arm braking device for doors and sliding furniture doors suitable to ensure a high level of resistance and reliability over time, and also such as to be easily and inexpensively made.

These and yet other purposes are achieved by the rocker arm braking device for doors and sliding furniture doors of the present invention, according to the main claim.

The construction and functional characteristics of the rocker arm braking device of the present invention will be more clearly comprehensible from the detailed description below in which reference is made to the appended drawings which show a preferred and non-limiting embodiment and wherein:

Figure 1 represents schematically axonometric views of the rocker arm braking device of the present invention, integrated in a guide rail, combined with a piston cushioning means and attached to a sliding door;

Figure 2 represents schematically a further axonometric view of the same rocker arm braking device in figure 1 ;

Figure 3 represents schematically an axonometric view of the rocker arm braking device and of the carriage used with it;

Figure 4 represents schematically, in an exploded view , said rocker arm braking device; Figure 5 represents schematically, in an exploded view, a part of the rocker arm braking device of the invention;

Figure 6 represents schematically an axonometric view of the activation support of the rocker arm braking device of the invention;

Figure 7 represents schematically, in an exploded view, the same support as figure 6 and the cushioning element used with it;

figures 8, 9 and 10 represent schematically as many views in longitudinal cross-section of the rocker arm braking device and relative carriage in three different positions corresponding to the stages of movement of the door;

Figure 11 represents schematically an axonometric view of the rocker arm braking device of the present invention, combined with a piston cushioning device and attached to a sliding door of a cabinet or wardrobe in the open condition;

Figure 12 represents schematically a side view of the same device attached to a sliding door of a cabinet or wardrobe;

Figure 13 represents schematically an axonometric view of the rocker arm braking device of the present invention, wherein the sliding door is in the intermediate condition, prior to total closure; Figure 14 represents schematically a side view of the same device in the condition of figure 13;

Figure 15 represents schematically an axonometric view of the rocker arm braking device of the present invention, wherein the sliding door is in the closed condition; Figure 16 represents schematically a side view of the same device in the condition of figure 15, which shows it upon reaching the end stop.

With initial reference to figures 1 and 2, the rocker arm braking device for doors and sliding furniture doors of the present invention, globally denoted by reference numeral 10 in figure 3, comprises a containment unit 12, in metal, plastic or other suitable material, in which a pivoting rocker arm is placed; the latter globally denoted by reference numeral 14 in figures 3 and 4. The containment unit 12 consists of two opposite and complementary half-shells 16 and 18, each of which substantially defines an "L" section; the half-shells 16 and 18 are connected transversely by means of a pin 20. At one end the half-shells 16, 18 define an extension consisting of a wing 22 with holes 24 , suitable to form the attachment seat of a carriage 26, in itself known, shown in detail in figure 3 and provided with pairs of wheels 26'. Said carriage comprises a head 28 on which holes 30 are made. Using two pins 32 or equivalent means, inserted in the holes 24 of the wings 22 and in the holes 30 holes of the head 28, the known carriage 26 is connected to said end of the rocker arm braking device 10 as shown in particular in figure 3. Said rocker arm braking device, at the end opposite the one connected to the aforementioned carriage 26, bears an integral appendage 34, extending from half-shells 16, 18 and forming the attachment seat for an opposite pair of wheels 36, similar to the wheels 26' of the carriage 26; the wheels 36 are paired with a bearing 36 ' and are rotatably coupled to the braking device 10 by means of the same pin 20 that transversely connects the half-shells 16 and 8.

The latter are further connected transversally by a rivet 56 inserted in the appendages 34; a pin 38, extending transversely near the same appendages 34, constitutes the coupling element of one end of a coil spring 40.

In the area between said pin 38 and the wings 22, the half-shells 16, 18 interconnected transversely define, in the containment unit 12, a cavity 42, which the pivoting rocker arm 14 is placed in . Said rocker arm, shown in detail in figure 5, consists of a pair of matched shaped arms 44, basically "C" shaped, wherein the convex part is facing downwards; the two shaped arms 44 are provided at opposite ends with a hole 46' for inserting the connection pins 46. Said pins simultaneously connect two needle rollers 48, 48' placed between said arms. Each of the needle rollers 48, 48 ' placed at one end of said arms, has a circumferential notching in which an O-ring 50 is housed which forms the rolling surface of said needle rollers. From one of the shaped arms 44 a pin 52 protrudes outwards, matched with a spacer 54 placed between said arms; the pin 52 constitutes the coupling element of one end of the coil spring 40, which at the other end is connected to the pin 38. The assembly formed of the shaped arms 44 and needle rollers 48, 48 ' with CD- ring 50 form the pivoting rocker arm 14, intended to be placed in the cavity 42 of the containment unit 12 in order to present said amis facing upward at an angle, with the needle rollers 48 and 48 ' suitable to project in part and alternately from the containment unit 12 according to the pivoting. Said shaped arms 44 have, at their central convex zone,facing down, a hole 58 suitable to accommodate a pin 60 making the longitudinal oscillation of the rocker arm 14 in the cavity of the containment unit 12 possible; said pin 60 visible in particular in figure 4, is supported by the half- shells 16 and 18 between which it extends.

The rocker arm braking device for doors and sliding furniture doors of the present invention further comprises a shaped support 62, illustrated in detail in figures 6 and 7, defined by a plate-shaped body with a substantially rectangular cross section which on one side has a housing and stabilization seat 64 of the cylindrical body of a cushioning means, typically of a known cushioning means 66 , in itself known, of the gas, air or silicone type. Laterally to said seat 64, from which the stem 68 of the cushioning device 66 protrudes at least in part, the shaped support 62 extends on one side in the shape of an appendage with an inverted "U" shape cross-section, in which the vertical branch adjacent to the seat 64 defines a triangular profile forming a cam 70; the latter comprises a descending portion 71 and an adjoining portion with the opposite inclination 73, at the end of which an arched fold 75 is formed. The cam 70 is facing downwards, in the direction of the needle rollers 48 and 48 ', being intended to cooperate with them and with the pivoting rocker arm 14 as a whole, as further described below in connection with the operation of the braking device of the invention.

Figures 1 and 2 clearly indicate the arrangement of the pivoting rocker arm and of the shaped support with the cam 70 and with the seat for the cushioning means 66, together with the positioning of the known carriage 26. All the components referred to are housed in a sliding guide of the known type, indicated by reference numeral 72 and formed of a basically rectangular section aluminium profile in which the lower base has a longitudinally extending central opening which defines a slot 74; protruding outwards from the latter is the conventional pin 76 of the carriage 26 connected in the known manner to the plate 78 which is fixed, with screws or other appropriate means of restraint, to the upper edge of the sliding door, schematically shown as number 80 in figures 1 and 2. The head 28 of the carriage 26, as specified above, is connected to the wings 22 of the containment unit 12, while the shaped support 62 is stabilized in the guide 72 by means of two or more dowel screws 82 (figures 6 and 7) which protrude upwards from the rear side, opposite the stem 68 of said shaped support. The guide 72 is instead fixed in a known manner to the ceiling or to a counter- ceiling (not shown) arranged at the opening housing the sliding door 80.

The rocker arm braking device of the invention intervenes when the door 80 is pushed by the user in the direction suitable to achieve closure; in this phase in fact the door needs to be slowed down, since if not properly braked, it could impact the end stop and rebound violentiy, partly opening. The reference is to figures 8 to 10, which depict the phases of such slowing down, thanks to both the pivoting rocker arm 14 in cooperation with the cam 70 and to the cushioning means 66.

Figure 8 illustrates the condition in which the needle roller 48 is in a position next to the appendage 34 of the half-shells 16, 18, and approaching the cam 70 and about to abut with it travelling along the first inclined portion, in descent; the door 80 hanging from the carriage 26 is about to start slowing down. The stem 68, which at the free end is fitted with a rubber bumper 84, is in fact about to abut with the appendage 34, which will push it, causing the initial braking phase. The spring 40, which acts as a traction member of the pivoting rocker arm 14, keeps said rocker arm in a basically lowered position and such as to facilitate the abutment between the needle roller 48' and the descending portion of the cam 70.

Figure 9 illustrates the next condition in which the pivoting rocker arm 14 is almost horizontal, given that the needle roller 48 has covered the entire descent portion of the cam 70 and has already begun to travel along the adjacent upward portion, while the needle roller 48 ' has begun to travel along said descent portion. The stem 68 of the cushioning means 66 is compressed, starting from the rubber bumper 84, by the appendage 34 and realizes the progressive braking of the sliding door 80 connected to the carriage 26. Figure 10 illustrates the condition in which the needle roller 48 has reached the end of its stroke by the pulling effect of the spring 40; the sliding door 80 is now in the fully closed position. The end stop of the needle roller 48 is defined by the folded arch 75, made adjacent to the upward portion of the cam 70. The spring 40 is calibrated so as to exert sufficient force to pull the door, bringing it into the closed position, as later described in relation to figures 12, 14 and 16, and to fully compress the stem 68 of the cushioning device 66.

During the sliding of the needle rollers 48 and 48 ' along the portions 71 and 73 of the cam 70, the O-ring 50 applied to said needle rollers prevents appreciable noise phenomena.

Figures 11 to 16 relate to the application of the rocker arm braking device of the present invention to the sliding doors of cabinets and wardrobes, i.e. furniture components, rather than sliding doors in rooms.

In the following description the same references as the previous solution will be used, referred to the sliding door, to identify common components or parts.

Figure 11 illustrates the rocker arm device paired with a carriage 86 of a known type which comprises a support plate 88 from the front side of which a bearing 90 with a grooved profile and plastic- coating protrudes. Said carriage 86 is constrained, through the support plate 88 to the top of the rear side of a door 94 of a cabinet or wardrobe 96, part of the hori2ontal panel forming the top shelf constituting the top 98 is schematically shown. The pivoting rocker arm 14 formed of the shaped arms 44 and of the needle, rollers 48, 48 ' is rotatably connected with a screw or pin 100 (figures 12, 14 and 16) or equivalent means to the hub of the bearing 90 of the carriage 86 projecting from said plate 88. The connection of said device to the plate 88 is made starting from the holes 58 which the shaped arms 44 forming said rocker arm device 14 have at their central convex zone. The pin or screw 100 allows the longitudinal oscillation of said pivoting rocker arm which, compared to the solution described above, has shaped arms 44 oriented at a downward angle. Laterally to each of the needle rollers 48, 48' of the rocker arm device opposite blocks 102, 104 are provided attached to the plate 88 and bearing cantilevered, respective appendages 106, 108 which constitute abutments suitable to limit the stroke of the needle rollers 48 and 48'; from the block 104, which is placed next to the needle roller 48', a pin 110 protrudes which is hooked to one end of the coil spring 40, the opposite end of said spring is hooked to a pin 112 (figures 12, 13 and 14) coming out of the shaped arms 44 of the rocker arm device. Below the appendage 108 of the block 104 an integral protruding element 114 is made, suitable to abut with the rubber 84 placed at the free end of the stem 68 of the cushioning means 66 to brake the door 88. The blocks 102, 104 can be made in one piece.

The cushioning means 66 are placed in this case too in the seat 64 made in the shaped support 62, which is housed in a linear guide 116, fixed at the front edge of the upper shelf or top 98 of the cabinet or wardrobe 96; the guide 116 is of the known type and comprise a rail 118 with a substantially semi-circular profile, complementary to that of the bearing 90 which slides on it . The shaped support 62 is constrained with the dowel nuts 82 to said top shelf or top 98 so as to present the cam 70 of said support oriented upwards, contrary to the solution described above and referring to the sliding door where the cam is facing downwards.

Figures 11, 13 and 15 show that the guide 116 comprises two paired seats extending longitudinally, only one of which is occupied by the shaped support 66. The second seat is advantageously used to accommodate a second support 66 in the case of a cabinet or wardrobe with double doors, i.e. also provided with an outer door. In this hypothesis too,referring to the doors of cabinets and wardrobes, the rocker arm braking device of the invention is activated when the door 94 is pushed by the user; in this phase in fact the door needs to be slowed down, since if not properly braked, it could violendy impact the end stop and rebound, pardy opening.

Figures 11 and 12 show that the carriage 86 fixed to the door 94 is next to the cam 70; the needle roller 48 ' is about to travel along the portion 71 of said cam which in this case extends upwards, given the inverted position of the shaped support, 62; the needle roller 48 is in the forward most position, overlooks said portion 71 and abuts from the bottom the appendage 106 which prevents any further upward movement. As may be seen in particular in figure 12, the "X" axis of the spring 40 is placed above the centre of rotation of the pivoting rocker arm 14, which consequently moves clockwise (as indicated by the arrow) so that the spring tends to pull the needle roller 48' upwards, determining the movement along the upward portion of the cam 70. Figures 13 and 14 show the next moment where, leaving out some intermediate stages, the needle roller 48 of the rocker arm braking device starts to travel along the portion now descending 73 of the cam 70, while the needle roller 48' is located about half-way along the upward portion 71 of said cam. In this phase, the spring 40 has already started to pull the door 94 closed, towards the end stop, defined by the arched fold 75 of the shaped support 62, and the element 114 protruding from the appendage 108 has abutted and begun to compress, starting from the rubber bumper 84, the stem 68 of the cushioning element 66, causing the start of deceleration of the carriage 86 and thus of the door 94 attached to it. In figure 14, in particular, it may be seen how the "X" axis of the spring 40 is aligned with the centre of rotation of the pivoting rocker arm 14, so that said spring finds itself in a neutral or stall condition with respect to the pivoting rocker arm 14.

Figures 15 and 16, lastly, illustrate the situation in which the needle roller 48 of the pivoting rocker arm has covered the entire descending portion 73 and abutted with the limit stop defined by the arched fold 75 of the shaped support 62, pulling the door 94 and bringing it into the closed position as a result of the action of the spring 40; the other needle roller 48 ' is near the top of the cam 70 and cannot in any case go any higher since it would abut the appendage 108 of the block 104 from below. During this phase, which brings the needle roller 48 to the end stop, the stem 68 of the cushioning means 66 has moved back completely under the thrust of the element 114 protruding from the appendage 108, causing the completion of the gradual braking of the door 94 of the cabinet or wardrobe 96. As may be seen in particular from figure 16, the "X" axis of the spring 40 is placed below the centre of rotation of the pivoting rocker arm 14, which consequently moves anti-clockwise (as indicated by the arrow) so that the spring tends to pull the needle roller 48' downwards, determining the movement along the downward portion of the cam 70 as far as the end stop 75 and the complete closure of the door or furniture door.

As may be seen from the above, the advantages which the invention achieves are evident.

The rocker arm braking device of the present invention makes it possible to bring into the closed position both sliding doors and the sliding doors of cabinets and wardrobes gradually, effortlessly and appropriately slowing down the door or furniture door if pushed too hard initially, at the same time avoiding unwanted noise given the use of O-rings on the needle rollers 48, 48' of the pivoting rocker arm 14. Depending on the inclination of the portions 71 and 73 of the cam 70 and the force exerted by the spring 40, it is possible to calibrate the closing of the sliding door 80 or sliding furniture door 94 considering the variable weight.

Despite the invention having been described above with particular reference to a possible and an alternative embodiment, made solely by way of a non-limiting example, numerous modifications and variants will appear evident to a person skilled in the art in the light of the above description. In particular, the rocker arm braking device can be used in groups of two units on each door 80 or furniture door 94, with one of the devices placed mirror-wise to the other, at or near the opposite ends of said doors or furniture doors. The present invention therefore sets out to embrace all the modifications and variants which fall within the sphere and scope of the following claims.

Claims

1) A rocker arm braking device (10) for doors and sliding doors of furniture comprising a carriage (26, 86), sliding on wheels or bearings (26', 90) along a guide (72, 116) and fixed to the top edge of a sliding door (80) or to the top of the inner side of a sliding door (94) of a cabinet or wardrobe (96); a shaped support (62), having a substantially rectangular cross-section, constrained by dowel screws (82) to said guide (72, 116), which has a housing and stabilization seat (64) of a cushioning means (66) on one side laterally to which a cam (70) is made on the same shaped support (62), characterised in that it comprises a pair of matching shaped arms (44), basically "C" shaped in which the central convex part is facing downwards, provided with a hole (46 ') at the opposite ends for inserting connection pins (46) which simultaneously stabilize between said arms two needle rollers (48, 48') to form a pivoting rocker arm (14), said needle rollers (48, 48') being guided by the cam (70) during the movement of the carriage (26, 86) along the guide (72, 116).

2) The braking device according to claim 1, characterized in that the pivoting rocker arm (14), formed by the pair of matching shaped arms (44) and by the needle rollers (48, 48') is placed in the cavity (42) of a containment unit (12) consisting of two opposite and complementary half-shells (16, 18) substantially having an L-shaped section, connected in a transverse direction by means of a pin (20), at one end said half-shells (16, 18) being provided with an extension consisting of a wing (22) with holes (24) constituting the attachment seat of the carriage(26). 3) The braking device according to claim 2, characterised in that the shaped arms (44) of said pivoting rocker arm (14) have, at their central convex zone,facing down, a hole (58) suitable to accommodate a pin (60) making the longitudinal oscillation of said rocker arm in the cavity of the containment unit (12) possible, said pin being supported by the half-shells (16 , 18) between which it extends.

4) The braking device according to claim 3, characterised in that the ends of the half-shells (16, 18) opposite the wing (22) bear an integral appendage (34), suitable to abut with a rubber bumper (84), placed at the free end of the stem (68) of the cushioning means (66), and forming at the same time, the seat for the attachment of a pair of opposite wheels (36), paired with a bearing (36 ') and coupled to said braking device by means of the pin (20) which transversely connects the half-shells (16, 18), a rivet (56) being placed in the appendages (34) for the further connection to each other of said half-shells (16, 18).

5) The braking device according to claim 1, characterised in that the cam (70) made on the shaped support (62) is facing downwards, in the direction of the needle rollers (48, 48 ') and defines a triangular profile comprising a descending portion (71) and an adjoining portion with the opposite inclination (73), at the end of which an arched fold (75) is formed, said needle rollers (48, 48') being provided with a circumferential notching in which an O-ring (50) is housed which forms the rolling surface of said needle rollers.

6) The braking device according to claim 4, characterised in that the pivoting rocker arm (14), formed by the pair of matching shaped arms (44) and by the needle rollers (48, 48^ is associated with a coil spring (40) the ends of which are respectively coupled to a pin (38), extending transversely next to said appendages (34) of the half-shells (16, 18), and to a pin (52) combined with a spacer (54) and protruding outwards from one of the shaped arms (44).

7) The braking device according to claim 1, characterised in that the pivoting device (14) is connected, starting from the hole (58) which the shaped arms (44) are provided with, by means of a pin or screw (100) to the hub of the bearing with plastic coating (90) of the carriage (86) that protrudes from said plate (88) and which is attached to the top of the inner side of a sliding door (94) of a cabinet or wardrobe (96).

8) The braking device according to claim 1, characterised in that at the front edge of the top shelf forming the top (98) of said cabinet or wardrobe (96) a guide (116) is fixed to which the shaped support (62) with the cam (70) made on said support and the cushioning means are constrained (66), said cam being facing upwards in the direction of the needle rollers (48, 48 ') of the pivoting rocker arm (14) connected to said bearing (90) projecting from the plate (88) of the carriage (86).

9) The braking device according to claim 8, characterised in that laterally to each of the needle rollers (48, 48') opposite blocks (102, 104) are provided, fixed to the plate (88) and bearing cantilevered respective appendages (106, 108) which constitute abutments suitable to limit the stroke of said needle rollers (48 and 48'), a pin (110) projecting from the block (104) to which one end of the coil spring (40) is attached, the opposite end of which is fastened to a pin (112) coming out of the shaped amis (44) of the pivoting rocker arm (14).

10) The braking device according to claim 9, characterised in that below the appendage (108) of the block (104) an integral protruding element (114) is made, suitable to abut a rubber (84) placed at the free end of the stem (68) of the cushioning means (66), said latter being pardy inserted in a seat (64) of said shaped support (62).

11) The braking device according to claim 9, characterised in that the blocks (102, 104) are made in one piece.