APPARATUS FOR CLEANING RUGS

Abstract: A carpet cleaning machine is described comprising of a framework and a work table for treating a carpet, and a pulling body comprising a drive roller which is driven by a motor for automatic conveying of a carpet through the machine, characterised in that the machine is equipped with means for the supply of cleaning/washing agent in a first treatment area, and a scrubbing body for mechanical treatment of the surface of the carpet, and that the carpet is mechanically beaten with the aid of a number of pistons in a second area, and is equipped in a third treatment area with means for removal of moisture. A procedure for cleaning of a carpet is also described.

Description: APPARATUS FOR CLEANING RUGS The present invention relates to a carpet cleaning machine comprising a framework, a work table and stand and a roller which is driven by a motor for the automatic conveyance of a carpet through the machine for cleaning of the carpet . To an increasing extent today, loose carpets are used in office and hotel environments. Loose carpets are also used extensively in private homes. With loose carpets it is meant carpets that are not fixed to an underlay/floor. The carpets are found in a number of different varieties, from lounge carpets to long, narrow runners. Normally they are constructed of an underlay material which is often in the form of a vinyl or rubber material. Attached to this underlay are threads/fibres (filaments) . These can have varying lengths from carpet to carpet, but normally range from some millimetres to about 1 centimetre. These fibres are tied or glued closely together to the underlay material. To ensure a close tying of the fibres, a mesh of a fibreglass material is used which is attached to the underlay material. The fibres can be of a synthetic or natural material. The loose carpets, which this cleaning device is aimed at, normally have a width of less than 2.5 metres, but the invention is not limited to such widths. The length can however, be considerable, such as in the case of for example, ' runners which are used in hotel corridors. Because of the close weaving/tying of the carpets, and the only partially penetrable/permeable underlay material, conventional washing techniques cannot be used in the cleaning of the carpets. Ordinary vacuuming has little effect as only a small amount of the solid particles are removed. Vacuuming does not remove stains either. Mechanical beating or hand beating of the carpets ■ is the only way to remove solid particles. The use of washing agents is a great problem because the carpet is then exposed to large amounts of water. Because of the close weaving, it is difficult to get the carpet dried satisfactorily. The use of too much washing agent/detergent also often leads to bleaching of the carpets. It is therefore an object to limit as much as possible, the amount of water used in the cleaning of the carpets. US 3,772,732 describes a carpet cleaning machine in which the carpet is pulled on a roller through the machine. A second roller is equipped with laths which treat the carpet surface while at the same time a roller equipped with ridges beats" the carpet. US 1,986,947 also shows a carpet cleaning machine with rollers which pull the carpet through the machine. This machine also treats the carpet with a set of laths. Additionally, the carpet is beaten by plate pieces which are vertically pushed and pulled towards the carpet. US 3,518,710 describes a carpet cleaning machine in which there is arranged means such as a brush which scrubs the carpet, and means to "beat" the carpet. These patents thus describe machines which carry out a mechanical treatment of the carpets corresponding to that which one can carry out manually by beating the carpets with a carpet beater. Solid particles, such as sand, ash, food remains and the like, are removed. To remove solid particles from a carpet by beating them out of the carpet, as mentioned above, is only one of the problems which one is faced with in cleaning carpets. An equally large problem is often that on the carpet are stains which are irremovable. US 3,518,710 also describes that nozzles are arranged for the supply of cleaning agent and brushes for the mechanical treatment of the carpet. With the present invention it is therefore an aim to provide a carpet cleaning machine which is more effective than those which are described above. The machine according to the invention is principally composed of three different process steps, namely removal of stains with the use of cleaning agents and scrubbing brushes, removal of particles in the carpet with an effective beating arrangement, and also an effective removal of the liquids which have been used during the cleaning process. The present invention thus relates to a carpet cleaning machine comprised of a framework and a work table for the treatment of a carpet, and a pulling device consisting of a drive roller which is driven by a motor for conveying a carpet through the machine automatically, where in a first treatment area the machine is equipped with means for the application of cleaning/washing agent, and is equipped with a scrubbing device for mechanical treatment of the carpet's surface, and in a second treatment area is equipped with means for the removal of moisture in the carpet, and in a third treatment area is equipped with means for the beating of the carpet, characterised in that the means for beating the carpet is comprised of a number of pistons which are arranged in a longitudinal row on the underside of the carpet, arranged such that as the carpet is fed through the carpet cleaning machine with the fibre side down it is beaten by these pistons as they are directed towards the surface of the carpet. More specified embodiments of the carpet cleaning machine according to the invention are described in the claims 2-13. Furthermore, the invention comprises a procedure such as is indicated in claims 14-15. The carpet cleaning machine according to the present invention will be further described in the following description, and the accompanying figures, in which: Fig. 1 shows a section of a side section of a first embodiment of the carpet cleaning machine. For the figure to be clear a number of the technical details are omitted. Figs. 2a and 2b show in side section how a set of pistons treat the surface of the carpet. Fig. 3 shows how a set with pistons is arranged in the longitudinal direction of the carpet cleaning machine. Figs. 4a and 4b show a washing arm for scrubbing of the surface of the carpet, shown in active (fig. 4a) and in inactive (fig. 4b) positions respectively. Fig. 5a shows a longitudinal section of how a set with pistons transmits the press force to a roller. Fig. 5b shows in perspective how the force is transmitted from a piston by way of a square profile and two rollers to one roller. Fig. 6 shows a second embodiment of a carpet cleaning machine according to the invention. Fig. 7 shows an adjustable suction mouthpiece. With the application of a carpet cleaning machine according to the invention, the carpets are cleaned by going through three different steps or phases. Phase I consists of a beating out of solid particles such as sand, ash, food remains etc. In this phase, the carpet is pulled through the machine with the fibre side turned downwards, and the carpet is beaten with a set of pistons which work vertically from below and up against the surface of the carpet (fibre side) . Phase II consists of a mechanical/chemical cleaning of stains which are absorbed onto the surface of the carpet. In this phase the carpet is fed through the machine with the fibre side turned upwards. Cleaning agent (such as soapy water/detergents) are applied, and the surface is treated mechanically with a sideways horizontal scrubbing of the surface of the carpet by a washing profile being moved backwards and forwards in the longitudinal direction of the carpet over the whole width of the carpet. In this phase a removal of loose fibre also takes place, which has a tendency to remain behind in the carpet even after the beating in phase I, by one or more brushes being moved sideways on the surface of the carpet. Phase III is a drying step. The two embodiments of the carpet cleaning machine which are described are, on the whole, different with regard to how the drying process is performed. In the first embodiment of the carpet cleaning machine, which is shown in figures 1-5, the carpet is dried by it being fed in between two rollers, where these two rollers are pressed against each other so that a considerable pressure is established against the carpet such that the washing agents are squeezed out of the carpet. In the second embodiment of the carpet cleaning machine, as shown in figures 6 - 7, a vacuum is used to dry the carpet. In a limited area which stretches over the whole width of the carpet, a reduced pressure is established such that the moisture is sucked out of the carpet, and is led into a waste tank. This second embodiment of the machine is presently the most preferred embodiment . Thus, figs. 1-5 show a first embodiment of a carpet cleaning machine 10 according to the invention. Fig. 1 shows a cross section of a carpet cleaning machine 10 according to the invention. The figure is simplified with regard to technical details to give a clearer picture of the principals on which the machine 10 is founded. The machine 10 is mounted in a framework 12 and is equipped with a work table 13 and an associated stand 14. The carpet 11 is arranged in the stand 14 and is taken across the table 13 and into the machine 10, where the carpet 11 is pulled over a drive roller 15. The drive roller 15 is driven by a motor and associated chain 17. The chain is tightened with a chain tension adjuster (not shown in the figure) . When the carpet has been fed over the upper edge of the drive roller 15, the direction of movement of the carpet 11 is guided by an arch-shaped guiding profile 19, and the carpet 11 is conveyed between the drive roller 15 and a support roller 20. Thereafter, the carpet is conveyed across a guiding surface 31 before it is collected in the frame 14. The frame 14 can be moved from a lower position (which the carpet 11, which has been conveyed through the machine 10, is led down into) and to an upper position (for feeding of the carpet 11 into the machine 10), which is shown in fig. 1. The motor makes the drive roller 15 rotate, and together with associated support roller 20, rollers 21, 21', 23, 23', square profiles 25,26 and pistons 27,28, sufficient pressure/force is put on the carpet 11 so that it is pulled forward with the same speed as the speed of the rotation of the drive roller 15. Whilst being pulled forward, the carpet is also held in place by a brush 24b (see fig. 4a) exerting a pressure against the carpet 11 (explained further below) . When the carpet 11 has been pulled through the machine 10, it can be rolled onto a roll again. This is not shown in the figures. The first time the carpet 11 is taken through the machine 10, the surface of the carpet, i.e. the fibrous side, is facing downwards. A washing arm 32 will, in this operation, be in position B, which is an "inactive" position, as shown in fig. 4b. In this first phase, the carpet is being beaten by a set of quickly upwards and downwards moving pistons 35 to which are fitted hats/caps 36. This beating with a set of many pistons is much more effective than the beating means which are shown in the publications mentioned above. The loose particles which come out of the carpet 11 as a result of the beating are collected in a trough 37. The trough 37 is partially filled with water to prevent foul smells spreading (corresponding to a water seal) . The trough 37 is detachable, and is also fitted with a drainpipe 38 for the removal of liquid and solid particles. How the pistons 35 work is explained further below. After the carpet 11 has been conveyed through phase I it is turned and placed with the surface/fibrous side facing upwards. This is again conveyed across the work table 13, over the drive roller 15, and thereafter between the drive roller 15 and the support roller 20. In this phase, by the conveying of the carpet 11 across the work table 13, different types of cleaning agents are applied. These can be applied automatically with the aid of nozzles which spray on a given amount of liquid, or they can be applied manually. Manual application is often to be preferred as different types of washing agents are used for different types of stains. The different stains can have different solubility in aqueous (polar) or oil-like (non-polar) fluids. Thus, the type of washing agent must therefore be chosen with care from the general rule that "same dissolves same". Smaller or larger amounts of water are also applied in this process. This is not without problems, and it is therefore desirable to use as little water as possible. If the surface is treated mechanically, as it is in the present invention, the amount of water can be reduced. The washing arm 32 is now moved by being rotated to position A (fig. 4a) . In this position, the surface of the carpet can be treated mechanically by a washing profile 33 being pushed sideways backwards and forwards. In addition to this mechanical scrubbing, two sets of brushes will ensure that loose fibres are removed. The first set of brushes 34 are moved together with the washing arm 32, i.e. sideways backwards and forwards, while the other set of brushes 34b are forced against the carpet by means of a set of pistons 34c. These function therefore, both to remove loose fibres from the carpet 11 and also to exert a certain force on the carpet 11 such that this is pulled smoothly by the drive roller 15. Both the washing profile 33 and the brush (es) 34, 34b, extend the whole length of the machine 10, i.e. the whole width of the carpet. The force of the brush (es) against the carpet can be regulated (by means of automatic regulation of the pistons (PLS) ) . How the washing arm 32 functions is explained further below. In the third phase of the process the carpet is dried. This is carried out either by the water being squeezed out of the carpet, or by applying a reduced pressure. In the embodiment of the invention which is explained above, the water is squeezed out of the carpet. Drying with a vacuum will be described below with reference to the second embodiment. As mentioned above, phase 1 is comprised of loose particles being beaten out. This is further described in the figures 2-3, and is common for the two embodiments of the invention. Fig. 2 shown a side section of a piston 35 comprising a piston housing 35a and a piston rod 35b upon which is • fitted a dish-formed cap 36. Fig. 2b shows the piston 35 in extended position as a force is exerted against the carpet 11. In this way, the carpet 22 is beaten with every stroke of the piston. Fig. 3 shows how a number of such pistons are arranged in a row by being fitted to a pipe which extends in the longitudinal direction of the machine 10, i.e. across the longitudinal direction of the carpet. In the specific embodiment which is shown in the figures, 18 such pistons 35 are arranged, but there can of course be more or fewer such pistons 35 used. Each piston 35 is connected by means of a PLS 30 so that each individual piston 35 can be controlled independently of each other, and various beating patterns can be programmed that, for example, all shall beat simultaneously or that, for example, every other shall beat simultaneously, or another pattern. The second step in the process is a cleaning of the surface of the carpet. This step is also common for the two main embodiments of the invention. The washing arm 32 is shown in figs. 4a-4b, and this can be moved from an inactive, primarily vertical position B to a primarily horizontal position A. In the position A, the washing profile 33 and the brush 34 are pushed forwards and backwards across the surface of the carpet 11. The piston 41, which is controlled by means of a PLS, regulates the positioning of the washing arm 32. The piston rod 41b, is secured to an arm 42 by means of a rotating joint. The rotating movements of the arm 42 are transmitted through the framework 12 by means of a pipe 43 to an arm 44. The pipe 43 is connected to the framework 12, so that it can rotate as the pipe 43 is run through the casing 43a. The arm 44 is secured to a longitudinal shaft 45a in a pipe 45b. As the piston rod 41b is retracted, the washing arm will therefore be positioned as shown by position A in fig. 1, i.e. in an active position. If the piston rod 41b is pushed outwards, the position of the washing arm 32 is changed to an inactive position as shown by position B in fig. 1. The piston 46 runs along a body 45 which together with an arm make up a T-shaped body. The arm 49 is connected at its centre to the body 45 at its one end so that it can rotate. On the other side of the body 45, parallel to piston 46, runs a set of rods 47 with associated casings 48. When the piston 46 is moved, the movement is transmitted to a counter movement for the casings 48 which run on the outside of the rods 47. A positioning screw 48a regulates the stroke length of the casing 48, and the piston movement is transmitted further to a gliding casing 48b which surrounds and glides on the pipe 47. The mechanical washing equipment 33,34,34c, and optionally a vacuum mouthpiece 61 are secured to the gliding casings 48b by means of the pistons 50,51. The piston casing 50a is secured to the gliding casing 48, and the piston rod 50b form, by means of a fitting 52, a fastening for the washing profile 33. When the washing arm 32 is in an active position, the piston 46 will ensure an approximately horizontal movement of the washing profile 33, whilst the piston 51 will ensure that the washing profile 33 is pressed against the surface of the carpet with sufficient force. The piston casing 51b is secured to the gliding casing 48b, and the piston rod 51a is secured to a brush 34 by means of a fitting 53. In the same way as for the washing profile, piston 46 provides for a sideways movement and piston 51 provides a vertical force against the surface of the carpet 11. Each of the pistons 50,51 can be regulated with positioning screws 50c, 51c, respectively. Two or more such washing arms 32 are secured in the longitudinal direction of the machine 10. The washing profile 33 and fitting 52, as well as the brush 34 and fitting 53, extend across the whole length of the machine so that the whole width of the carpet 11 is treated simultaneously. A pipe 54a with a shaft 54b is also arranged where the shaft is connected to the arm 49 so that the movement is synchronised in both (all) the washing arms 32. The pistons 46,50,51, which provide for the sideways, horizontal treatment of the surface of the carpet 11, and which also exert a certain pressure against the surface of the carpet 11, are also regulated with the aid of PLS. With this mechanical treatment in phase 2, the amount of washing agent, and thus the amount of liquid, can be considerably reduced. After the carpet 11 has been through the beating out (phase 1) of particles, and mechanical/chemical cleaning (phase 2) of the surface, the clean, but wet carpet must be dried. As described above, this is carried out in a first embodiment of the present invention by the carpet being conveyed between the rollers 15,20. As can be seen in fig. 1, the piston rods 27b and 28b are simultaneously forced forwards so that a considerable pressure is exerted between the rollers 15,20 at the same time as the carpet 11 is pulled by the roller 15 through the slot between the rollers 15,20. How the force is transmitted from the piston 27 to the rollers 20 is illustrated in the figures 5a-c. Two or more pistons 27 are arranged in the longitudinal direction of the machine 10. These are connected to the framework 12 by means of the piston casing 27a. The piston rod 27b is secured, by means of a fitting 27c which is secured to the piston rod 27b by means of bolts 27d, to a square profile 25 which extends in the longitudinal direction of the machine. All movements from the pistons 27 will thus be taken up by the square profile 25 and be evenly distributed over the whole longitudinal direction of the machine 10. The transmission of force between square profile 25 and runner 20, which also extends over the whole of the longitudinal direction of the machine 10, is transmitted by means of several sets of rollers 21,21', which are secured to the square profile 25 by means of fitting 22. In the axial direction of the roller 15, two such rollers 21,21' will simultaneously transmit the force from the piston 27 as is illustrated in the perspective diagram in fig. 5c. Thereby, an even pressure is ensured across the whole length of the roller 15. Corresponding force transmission is exerted from the pistons 28 to the roller 15. In fig. 5, it can be seen that the fluid which is squeezed out of the carpet 11, is collected in a trough 55 which is equipped with a drain pipe 56. Alternatively, or in combination, the carpet can be dried by the establishment of a negative pressure (vacuum) in an area of the carpet. Another embodiment of the machine in which only a vacuum is used to dry the carpet, i.e. the water is not squeezed out of the carpet, is explained below. These two features can also be combined in the first embodiment of the machine by arranging a mouthpiece 61 (shown in fig. 4a) in the longitudinal direction of the machine 10 to delimit an area in which reduced pressure can be established. However, it has been surprisingly found that drying the carpet by vacuum is an especially advantageous way to carry out the drying process, and a particular machine has therefore been developed and adapted for this step. This machine is shown in the figures 6 - 7, and represents in many ways a simplified version of the machine according to the first embodiment. In this connection it shall be mentioned in particular that the arrangement (pistons and rollers) given by the reference numbers 28 and 22 can be removed. In the first embodiment it is these which shall establish sufficient pressure to squeeze the water out of the carpet, and they are now superfluous. Furthermore, the roller 15 can be fabricated in a much simpler construction (solid steel in the first embodiment) as this shall now ensure propulsion of the carpet only. In one embodiment this roller 15' is covered with a layer of rubber or another elastic material to establish sufficient friction between roller 15' and the carpet 11. It can be seen in fig. 6 that the cylinder 41' (which moves the washing arm) is moved. The drying process is now carried out in that an arrangement is made to establish a reduced pressure, or vacuum, in an area of the carpet. In fig. 6, a mouthpiece 61' is shown, in the upper part of which is arranged a connection to a vacuum pump or vacuum suction unit (not shown) such that a negative pressure is established in the gap which arises between the carpet 11' and the inside of the mouthpiece 61' . The suction mouthpiece 61' is shown in greater detail in fig. 7 in which it can be seen that the mouthpiece 61' extends across the whole width of the machine, while it is relatively narrow in the longitudinal direction of the carpet. The mouthpiece can be lowered down towards the carpet 11', and in one embodiment, it is also comprised of sealing means (not shown) in the part of the mouthpiece which is in contact with the carpet, for example in the form of elastic strips made from plastic or rubber. From the mouthpiece a number of openings lead to the vacuum pump by means of communication channels. Furthermore, in one embodiment the mouthpiece 61' is constructed such that its length can be adjusted to fit the width of the carpet, by using adjustable joining pieces 63' which can be fed into and out of the main mouthpiece 61'. This is illustrated in fig. 7 which shows two metal strips 63' that can be pushed into the mouthpiece 61' , so that they cover the opening of the mouthpiece 61', until they adjoin the outer edge of the carpet. This prevents suction of false air, which would have reduced the effectivity of the drying. The most important point is that an adequate vacuum is established so that a sufficient amount of water is removed from the carpet. The vacuum drying can also be combined with other drying processes, as the alternative described above, and standard air drying. Furthermore, a tank 57 for soapy water/detergent is shown in fig. 5a. This feature is common for both of the main embodiments. From this tank 57, liquid is pumped by means of a pump 58 by way of a pipeline 59 to a set of nozzles 60 for the application of soapy water/detergent to the surface of the carpet 11. This is a part of the treatment during phase 2, i.e. the means are applied before the carpet 11 is scrubbed with the washing profile 33 and brush 34. The nozzles can be regulated manually or automatically. Alternatively, the soapy water/detergent can be applied manually. All the different pistons 27, 28, 35, 46, 50, 51, 41 are regulated individually and independently of each other with a PLS 30. The number of each type of piston, and which dimension/capacity each piston shall have, can vary. In the concrete first embodiment which is described in the figures 1-5, there are employed for example, 3 pieces of each of the pistons 27, 28, two pieces of the pistons 46, 50, 51, 41 and 18 pieces of the pistons 35.

Claims: Claims 1. Carpet cleaning machine (10,10') comprising a framework (12) and a work table for treatment of a carpet, and a pulling body comprising of a drive roller (15,15') which is driven by a motor (16) for automatic conveyance of a carpet (11,11') through the machine (10,10'), in which the machine (10,10') in a first treatment area is equipped with means (60) for the supply of cleaning/washing agent, and a scrubbing body (33) for mechanical treatment of the surface of the carpet (11) , and in a second treatment area is equipped with means for removal of moisture in the carpet (11,11'), and in a third treatment area is equipped with means (35) for beating the carpet (11,11'), characterised in that the means (35) for beating the carpet comprise a number of pistons (35) which are arranged in a longitudinal row on the underside of the carpet (11,11') arranged so that when the carpet (11,11') is conveyed through the carpet cleaning machine (10,10') with the fibrous side down it is beaten by these pistons (35) as they are directed against the surface of the carpet. 2. Carpet cleaning machine (10,10') in accordance with claim 1, characterised in that the pistons (35) are regulated by PLSes and that the beating pattern can therefore be regulated. 3. Carpet cleaning machine (10,10') in accordance with claim 2, characterised in that the pistons (35) can work independently of each other. 4. Carpet cleaning machine (10,10') in accordance with claim 1, characterised in that the means for supplying cleaning/washing agent comprise of one or more nozzles (60) mounted in a holder which can be moved in the horizontal plane with respect to the work table (13) . 5. Carpet cleaning machine (10,10') in accordance with claim 1, characterised in that the means for mechanical treatment of the surface of the carpet (11,11') comprise a scrubbing body (33) which is pushed in parallel with respect to the surface of the carpet (11,11'), for example, with the aid of a piston (46) . 6. Carpet cleaning machine (10,10') in accordance with claim 5, characterised in that the vertical position of the scrubbing means (22) is regulated by a force element. 7. Carpet cleaning machine (10,10') in accordance with claims 5 or 6, characterised in that the scrubbing organ (33) is wave-formed on the side facing the carpet. 8. Carpet cleaning machine (10,10') in accordance with claim 1, characterised in that the pulling body functions as a means for removal of moisture from the carpet, and comprises the squeezing elements (15,20) in a press for squeezing water out of the carpet (11) . 9. Carpet cleaning machine (10,10') in accordance with one of the claims 1-8, characterised in that the machine (10,10') is further comprised of a set of brushes (34) which mechanically treat the surface of the carpet (11,11') by the brush(es) (34) being pushed sideways horizontally forwards and backwards by means of the force from the piston (46), and/or second set of brushes (34b) onto which is exerted an adjustable vertical force with the aid of a piston (52) . 10. Carpet cleaning machine (10') in accordance with one of the claims 1-9, characterised in that the machine comprises a mouthpiece 61' for establishing a reduced pressure in an area of the carpet, and that this mouthpiece 61' is connected to a vacuum pump so that the carpet can be dried with the established reduced pressure. 11. Carpet cleaning machine (10') in accordance with claim 10, characterised in that the mouthpiece (61') extends in the whole longitudinal direction of the machine . 12. Carpet cleaning machine (10') in accordance with one of the claims 10-11, characterised in that the mouthpiece (61') in the longitudinal direction of the carpet has an opening (which faces down towards the carpet) in the range 1 - 10 centimetres, preferably 2 - 5 centimetres. 13. Carpet cleaning machine (10') in accordance with one of the claims 10-12, characterised in that the width of the mouthpiece (61') can be adjusted as there is arranged a metal strip (63') on each end of the mouthpiece (61') which can be pushed in towards the carpet so that the opening of the mouthpiece (61') is limited to cover the width of the carpet (11'). 14. Procedure for cleaning of a carpet (11,11'), characterised in that the carpet (11,11') is conveyed through a carpet cleaning machine in which the carpet (11, 11' ) , in a first phase, is supplied with cleaning/washing agent for removal of stains for thereafter to be subjected to a mechanical scrubbing of the carpet, whereupon the carpet is conveyed through the carpet cleaning machine with the surface facing downwards and in which a number of pistons mechanically beat particles out of the carpet, and that the carpet (11,11') is dried in a third phase. 15. Procedure in accordance with claim 14, characterised in that the carpet (11,11') is dried by there being established a reduced pressure (vacuum) in an area of the carpet by means of a mouthpiece (61') .

Inventors: TELLNES OEYSTEIN, TELLNES, OEYSTEIN
Applicants: TELLNES OEYSTEIN, TELLNES, OEYSTEIN
Application year: 2001
Main classification: A47L11
IPC codes: D06G1