A CUSHION CONSISTING OF A WATER-FILLED COVER

Abstract: A cushion for support of a sitting or lying person such as a seat cushion or mattress, consists of a water-filled cover of soft flexible foil material such as weldable plastic foil. The inner water-filled cavity contains devices for damping of liquid flows and can be connected to one or more equalizing vessels. The interior of the cover is divided into cells which are defined by bottom and side walls (2) and an expandable diaphragm (1) so that together the diaphragms (1) form the supporting or lying surface of the cushion, and every cell is connected to a channel (3) which can be common to all cells or a group of cells, partly via a check valve (5) which when open and at an increasing pressure in the cell allows a quick flow of water from the cell to the channel, and when closed prevents flow in the opposite direction, and partly via throttling devices (6) which allow a slow flow of water from the common channel (3) to the cell. The check valve may appropriately be a bistable check valve.

Description: A cushion consisting of a water-filled cover The present invention relates to a cushion consisting of a water-filled cover and of the kind specified in the introduction to the claim. When a person sits or lies down on such a cushion, the local load on the cover will because of the person's weight have the effect that water is displaced to other parts of the interior of the cover and/or to the equalizing vessel. Hence waving or lapping motions will occur in the cover which may be very irritating to the person concerned. To damp these liquid flows it is known to insert partitions in the interior of the cover or sectionalize the cushion in some other way so that the water flow is forced through different channels and/or valves. A complete prevention of backflowing volumes of water cannot, however, be obtained in such a cushion by the use of known designs. The object of the invention is, therefore, to specify a cushion of the said nature, but without the above disadvantage. This is done according to the invention by designing the cushion as specified in the claim. In the neutral condition all the cells are filled completely and equally much with water. When a person - or some other load - is placed on the cushion, water from the loaded cells will, via the check valves which are opened, flow quickly to the corresponding channel and possibly to the equalizing vessel. Water cannot pass the check valves in the opposite direction, but will flow slowly through the throttling devices back to the unfilled cells. In what follows, the invention w.ill be described in detail in connection with the drawing where Fig. 1 shows a section through part of a first embodiment of a cushion according to the invention, and Fig. 2 a section through part of another embodiment of a cushion according to the invention. In the embodiment shown in Fig. 1 every cell is connected to a common channel 3 via a check valve 5 which allows water to flow from the cell to the channel, but not vice versa. The connection is sized in such a way that the volume of water which is displaced from the cell when diaphragm 1 is loaded, can pass very quickly through the open check valve 5 and flow through channel 3 to an equalizing vessel 7. In order to produce a certain counter-pressure in this vessel, an elastic diaphragm 8 may be placed in the equalizing vessel, as shown in Fig. 1. Every cell is also connected to the common channel 3 and hence to equalizing vessel 7 via throttling channels 6 with throttling openings and/or a relatively small cross section. When the load on a diaphragm ends, water from equalizing vessel 7 will thus be able to flow relatively slowly back to the cell in question. In the embodiment shown water can thus flow quickly away from loaded areas (cells) of the cushion, but the backflow in the normal way known from already existing cushions is avoided. Instead of the normal check valve illustrated in Fig. 1, a so-called bistable check valve can be used. This valve is arranged *) so that from neutral position it opens to flow in an arbitrary direction in accordance with a pressure increase, but closes to backflow in the opposite direction until pressure equalization has taken place. This bistable check valve for a cell which is loaded will thus open to flow from the cell to the channel, but prevent backflow from the channel to the cell. When the pressure thus increases in the channel, the check valves to other cells connected to the same channel whose diaphram is not loaded will open to flow from the channel to the cells, but prevent backflow from these cells to the channel. When a pressure equilibrium has been created again via the throttling devices, all the. bistable check valves will go back to neutral position. *) See application /85 filed with this application. Fig. 2 shows an embodiment where every cell is connected to channel 3 via two inlets 9 and 10. Iri one inlet 9 a check valve 11 is fitted which allows influx into the cell, but prevents backflow from the cell. The other inlet 10 can be closed and opened by means of a body 12 which changes position or shape when the distance between the top point of diaphragm 1 and the cell bottom is changed; for example,, by body 12 being connected to the diaphragm by means of a piston rod 13 and resting on a spring unit 14. The space defined by the bottom of body 12 is connected to the surroundings via an air duct 15.

Claims: C l a i m s 1. A cushion for support of a sitting or lying person such as a seat cushion or mattress and of the kind which consists of a water-filled cover of a soft flexible foil material such as weldable plastic foil, the . inner water-filled spaces of which cover contain devices for damping of liquid flows and can be connected to one or more equalizing vessels, characterized in that the interior of the cover is divided into cells which are defined by bottom and side walls (2) and an expandable diaphragm (1) whereby diaphragms (1) jointly constitute the supporting or lying surface, and that every cell is connected to a channel (3) which can be common to all cells or a group of cells, partly via a check valve (5) which in the open state allows a quick flow of water between the cell and the corresponding channel which may be . connected to an equalizing vessel, and in the closed state prevents flow in the opposite direction, and partly via throttling devices (6) which allow a slow flow of water between the channel (3) and the cell. 2. A cushion as claimed in claim 1, characterized in that the check valve is a bistable check valve.

Inventors: GULDAGER HANS, GULDAGER, HANS
Applicants: GULDAGER HANS, GULDAGER, HANS
Application year: 1986
Main classification: A47C7
IPC codes: A47C4, A47C27