Device and method for pneumatically filling and emptying air cushions

Abstract

Device for pneumatically filling and emptying air cushions (LK1, LK2, LK3) in a seat of a means of transport, comprising a valve arrangement (1) through which compressed air from a compressed air supply (K) can be supplied to the air cushions (LK1, LK2, LK3) for filling and compressed air can be released from the air cushions (LK1, LK2, LK3) for emptying, wherein the valve arrangement (1) comprises at least one valve group with several valves (EM; SMA1, SMA2, SMA3), wherein several air cushions (LK1, LK2, LK3) are assigned to the at least one valve group, which can be filled and emptied via the valve group, wherein the at least one valve group is formed with: - a first valve (EM) which in a first switching position allows the supply of compressed air from the compressed air supply (K) to a compressed air channel (VL) and in a second switching position blocks the release of compressed air from the compressed air channel (VL), - a plurality of second valves (SMA1, SMA2, SMA3) coupled to the compressed air channel (VL), wherein each of the air cushions (LK1, LK2, LK3) assigned to the valve group is connected to a different second valve (SMA1, SMA2, SMA3) of the valve group, and wherein each second valve (SMA1, SMA2, SMA3) in a first switching position allows a flow of compressed air from the compressed air channel (VL) to an air cushion (LK1, LK2, LK3) connected to the respective second valve (SMA1, SMA2, SMA3), and in a second switching position allows the deflation of an air cushion (LK1, LK2, LK3) into the environment, and wherein the first valve (EM) is formed with a fast-switching valve and the second valves (SMA1, SMA2, SMA3) are formed with valves that switch more slowly in relation to this.

Description

[0001] The invention relates to a device for pneumatically filling and emptying air cushions in a seat of a means of transport, which has a valve arrangement through which compressed air from a compressed air supply can be supplied to the air cushions for filling and compressed air can be released from the air cushions for emptying, wherein the valve arrangement has at least one valve group with several valves, wherein several air cushions are assigned to the at least one valve group, which can be filled and emptied via the valve group, wherein the at least one valve group is formed with a first valve which in a first switching position allows the supply of compressed air from the compressed air supply to a compressed air channel and in a second switching position allows the release of compressed air from the compressed air channel, and a plurality of second valves which are coupled to the compressed air channel, wherein each of the air cushions assigned to the valve group,is connected to a different second valve of the valve group and wherein each second valve in a first switching position allows a flow of compressed air from the compressed air channel and the air cushions connected to the respective second valve.

[0002] The invention also relates to a method for operating such a device.

[0003] Such a device and method for pneumatically filling and emptying air cushions are known from DE 10 2013 220 563 A1. It is mentioned there that the valves for filling air cushions can be implemented as electromechanical actuators, such as electromagnetic or piezoceramic actuators.

[0004] However, shape memory alloy wires (SMAs) are increasingly being used as actuators for such valves. These wires shorten in length when current flows and they heat up as a result, and lengthen again when they cool down, thus actuating a valve flap. Compared to electromagnetically or piezoelectrically actuated valves, they offer the advantages of low weight and compactness, as well as quiet operation.

[0005] Valves with SMA actuators, however, have a slower response time compared to electromagnetically or piezoelectrically actuated valves, ranging from 0.1 to 0.5 seconds, particularly when switching off. Therefore, highly dynamic functions—such as curve-dependent inflation of side support cushions or rapid massage—can only be implemented to a very limited extent. This affects both the response time and the resulting accuracy in reaching a target pressure. This is particularly relevant in systems with a central pressure supply, where a high pre-pressure is typically applied to the valve continuously.

[0006] For systems with local pressure generation, the flow rate is controlled according to EP 2 361 800 B1 – e.g., slowed down – and, if necessary, stopped as soon as the target pressure is reached. An additional check valve in the pressure generator or in the switching valve prevents air from escaping. This ensures high pressure accuracy even with slow-switching valves.

[0007] DE 10 2005 045 403 A1 discloses a system with a central pressure supply in which electromagnetically or piezoelectrically actuated valves with a short response time are used. However, these are expensive and require more installation space than SMA valves.

[0008] German patent DE 10 2013 220 551 B4 describes a predictive system for extending the time available for filling. This allows for slower filling, and a longer switching time has less of an impact on the target pressure.

[0009] A valve circuit with a pilot valve is generally known from DE 10 2013 220 563 A1. A pilot valve can be used, for example, to throttle the flow rate or to reduce leakage.

[0010] The object of the invention is to provide a device and a method that can utilize SMA valves for actuating highly dynamic functions, possibly in conjunction with a continuously applied pressure supply. The majority of the valves should be able to be actuated by means of SMA actuators.

[0011] The problem is solved by a device for pneumatically filling and emptying air cushions in a seat of a means of transport, which has a valve arrangement through which compressed air from a compressed air supply can be supplied to the air cushions for filling and compressed air can be released from the air cushions for emptying, wherein the valve arrangement has at least one valve group with several valves, wherein several air cushions are assigned to the at least one valve group, which can be filled and emptied via the valve group, wherein the at least one valve group is formed with at least one first valve, which in a first switching position allows the supply of compressed air from the compressed air supply to a compressed air channel, in a second switching position blocks the release of compressed air from the compressed air channel and in a third switching position allows the release of compressed air from the compressed air channel, and a plurality of second valves.which are coupled to the compressed air channel, wherein each of the air cushions assigned to the valve group is connected to a different second valve of the valve group, and wherein each second valve, in an open switching position, allows a flow of compressed air from the compressed air channel to an air cushion connected to the respective second valve, and, in a closed switching position, blocks the flow. According to the invention, the first valve is formed with a fast-switching valve, and the second valves are formed with valves that switch relatively more slowly.

[0012] A fast-acting valve is therefore installed between the pressure supply and the distribution line. Several SMA valves are used to connect air consumers to the common distribution line.

[0013] According to a method in the invention that also solves this problem, it is possible to first actuate the associated second, i.e., slower-acting, valve and then the first, i.e., faster-acting, valve for filling and emptying an air cushion, thereby enabling an overall rapid switching response. This is possible because the slower-acting second valves can be activated, if necessary, even before the actual filling or emptying time, without filling or emptying taking place as long as the first valve is not opened. A filling or emptying operation can then be quickly controlled by means of the first valve.

[0014] In an advantageous embodiment of the device, the first valve is formed with a 2 / 2-NC valve (NC: normally closed) for supplying compressed air to the compressed air channel and for blocking the connection between the compressed air supply and the compressed air channel.

[0015] In a further advantageous embodiment of the device, the second valves are each formed with a 3 / 3 valve for supplying compressed air from the compressed air channel to an associated air cushion in a first switching position, for releasing compressed air from an associated air cushion into the environment in a second switching position, and for locking the valve in a third switching position.

[0016] This means that air can be released directly from an air cushion into the environment via a second valve, without having to operate the first valve.

[0017] In an alternative embodiment of the device, the second valves are each formed with a 3 / 2 valve for supplying compressed air from the compressed air channel to an associated air cushion in a first switching position and for releasing compressed air from an associated air cushion into the environment in a second switching position.

[0018] Here too, the compressed air can be released directly into the environment via the second valves; however, it is not possible to lock the valves, so this design is only intended for applications where this is not important, for example in a massage function where pressure in an air cushion should not be maintained for a longer period of time - as is the case with a lumbar support.

[0019] In a further embodiment of the device, the first valve can be formed with a valve with a magnetic actuator, with a piezo actuator or with an electroactive polymer actuator.

[0020] These technologies enable fast switching times, so that a desired target pressure can be set quickly and precisely.

[0021] In a further development, the second valves can be formed with an actuator using a shape memory alloy wire, making a lightweight design with low switching noise possible.

[0022] In a method according to the invention for operating a device described above, the associated second valve is actuated first, and then the first valve, to fill and empty an air cushion.

[0023] Therefore, in situations where the pressure in an air cushion or pressure line cannot yet change significantly, a second valve is already activated, thus establishing a pressure connection between the pressure line and the air cushion. Afterwards, the desired pressure in the pressure line or air cushion can be set relatively quickly and precisely via the first valve.

[0024] The invention is described in more detail below with reference to exemplary embodiments and the aid of figures. These figures show... Fig. 1 a first embodiment of a device for filling and emptying air cushions and Fig. 2 a second embodiment of a device for filling and emptying air cushions

[0025] The invention is explained below using the example of an inflatable motor vehicle seat, which includes a lumbar support in the seat backrest consisting of three vertically arranged air cushions, the air cushions of which can also be used for a massage function. These air cushions are in Fig. 1 and Fig. 2 is designated LK1, LK2, and LK3, where air cushion LK1 is an upper air cushion, air cushion LK2 is a middle air cushion, and air cushion LK3 is a lower air cushion of the lumbar support. Only three air cushions are shown; however, the vehicle seat may have additional air cushions that can also be controlled by the device shown and described. The air cushions may also be organized into multiple groups.

[0026] According to the embodiment of the Fig. 1. The pneumatic filling and emptying of the air cushions is carried out via a valve arrangement 1, which is connected on one side to the air cushions and on the other side to a compressed air supply K in the form of a pneumatic pump. Instead of a pump, a central compressed air supply with a permanently available pre-pressure can also be used if necessary. The compressed air supply also includes a pressure accumulator DS.

[0027] Valve arrangement 1 of the Fig. 1 comprises a multitude of valves that can be arranged on a common carrier module and are fluidically interconnected on this carrier module. The carrier module simultaneously serves as the valve seat, pressure distributor, and housing of the valve assembly. However, it is also possible to provide several carrier modules or housings, particularly for different valve types, in order to install them, for example, at appropriately suitable locations in a vehicle or vehicle seat due to their differing noise levels.

[0028] The illustrated valve arrangement comprises a valve group, wherein the valve group includes a first valve EM and second valves SMA1, SMA2, and SMA3. Further valve groups may also be provided, each likewise consisting of a first valve and several second valves, to fill and empty additional air cushions. These further valve groups may also be connected to the compressed air supply K.

[0029] In the embodiment of the Fig. 1. All valves are electromechanical control elements or actuators that change their switching position when energized. In Fig. 1 and also in the one described below Fig. Figure 2 shows the valves in their de-energized state, in which the valves are closed. All second valves SMA1, SMA2, SMA3, in a first open position, allow compressed air to flow from a compressed air channel VL to a connected air cushion LK1, LK2, LK3, as indicated by a corresponding arrow. In a second open position, they allow compressed air to flow from a connected air cushion LK1, LK2, LK3 to the compressed air channel VL, as indicated by a corresponding oppositely directed arrow. In a third, closed position, this flow is blocked.

[0030] The first valve EM is in the exemplary embodiment of the Fig. 1 formed with a 2 / 2 valve that allows a flow from the compressed air supply K to the compressed air channel VL and a blocking of this flow.

[0031] The second valves SMA1, SMA2, SMA3 are also connected to the compressed air channel VL and allow the supply of compressed air to an air cushion LK1, LK2, LK3 connected to a respective second valve SMA1, SMA2, SMA3, or to their emptying, as described above.

[0032] The first valve EM is formed with a fast-switching valve, such as an electromagnetically or piezoelectrically actuated valve. The second valves SMA1, SMA2, SMA3 are formed with slower-switching valves, such as, and preferably, valves with an actuator formed from a shape-memory alloy wire.

[0033] This makes it possible to implement a lightweight and quiet switching device that nevertheless enables fast and precise target pressure generation. Since the first valve EM is connected in series with each of the second valves SMA1, SMA2, and SMA3, one or more of the second valves can be actuated while the first valve is still closed, even if no pressure change is yet desired, and the pressure change can then be quickly achieved via the first valve.

[0034] All valves in the valve group are connected to a common compressed air channel K. The first valve allows compressed air to enter the compressed air channel K. The second valves, SMA1, SMA2, and SMA3, in the valve group each control the compressed air supply to an individual air cushion SK1, SK2, and SK3, respectively, or vent it.

[0035] For filling, a second valve SMA1 is first activated for the air cushion LK1, thus pneumatically connecting the compressed air channel K and the air cushion LK1. Subsequently, the first valve EM is actuated, enabling precise timing control of the filling process.

[0036] At the end of the filling process, a rapid shutdown is required, which is not possible with the second valve SMA1 due to the slow cooling of the SMA actuator. Instead, the first valve EM is switched off first to ensure high accuracy of the target pressure, thus stopping the airflow. The second valve SMA1 can now also be switched off and slowly return to its closed state without changing the pressure in the air cushion LK1.

[0037] The advantage of the arrangement shown is that the majority of the air cushion valves can be represented as compact and cost-effective SMA valves, whereas a fast-switching valve, such as a solenoid valve, can be used for precise dynamic control. The [unclear text] Fig. The device shown in 1 is preferably used for static functions with long (or permanent) holding times of the air in the air cushions LK1, LK2, LK3.

[0038] In this example, the number of secondary valves SMA1, SMA2, SMA3 is set to 3; any other number is also possible. Similarly, several secondary valves SMA1, SMA2, SMA3 can be activated simultaneously if the associated air cushions LK1, LK2, LK3 are to be filled or vented synchronously. It is also possible to use multiple valve groups, each with separate pilot valves and distribution lines, to control the groups independently.

[0039] Instead of solenoid valves, other fast-acting valves, such as valves with piezoelectric actuators or electroactive polymer actuators, can also be used. When using a proportional pilot valve, the filling and / or venting speeds are also adjustable.

[0040] According to the Fig. In the embodiment shown in Figure 2, the second valves SMA1, SMA2, SMA3 can also be implemented with a 3 / 2-valve, which is designed to supply compressed air from the compressed air channel VL to an air cushion LK1, LK2, LK3 in a first switching position and to release compressed air from an air cushion LK1, LK2, LK3 into the environment in a second switching position.

[0041] This reduces the control complexity, however, it is not possible to lock the valves, so this variant is only useful for applications where the air pressure in the air cushions does not need to be maintained for long.

[0042] The described devices offer the advantages of short switching times during filling and / or venting when using space-saving and cost-effective SMA valves, as well as extending the use of SMA valves to systems with high dynamic switching time requirements. Furthermore, this expands the use of SMA valves to systems with a central or continuous pressure supply.

Claims

[1] Device for the pneumatic filling and emptying of air cushions (LK1, LK2, LK3) in a seat of a means of transport, which device has a valve arrangement (1) via which compressed air can be supplied from a compressed air supply (K) for filling the air cushions (LK1, LK2, LK3) and compressed air can be released from the air cushions (LK1, LK2, LK3) for emptying, wherein the valve arrangement (1) has at least one valve group with a plurality of valves (EM; SMA1, SMA2, SMA3), wherein the at least one valve group is assigned a plurality of air cushions (LK1, LK2, LK3) which can be filled and emptied via the valve group, wherein the at least one valve group is formed with: - a first valve (EM) which, in a first switching position, enables the supply of compressed air from the compressed air supply (K) to a compressed air duct (VL) and, in a second switching position, blocks the discharge of compressed air from the compressed air duct (VL), - a plurality of second valves (SMA1, SMA2, SMA3) coupled to the compressed air channel (VL), wherein each of the air cushions (LK1, LK2, LK3) assigned to the valve group is connected to a different second valve (SMA1, SMA2, SMA3) of the valve group, and wherein a respective second valve (SMA1, SMA2, SMA3) in a first switching position allows a flow of compressed air from the compressed air channel (VL) to an air cushion (LK1, LK2, LK3) connected to the respective second valve (SMA1, SMA2, SMA3) and in a second switching position allows the emptying of an air cushion (LK1, LK2, LK3) into the environment, and wherein the first valve (EM) is formed with a fast-switching valve and the second valves (SMA1, SMA2, SMA3) are formed with valves that switch more slowly in comparison thereto. [2] Device according to claim 1, wherein the first valve (EM) is formed with a 2 / 2-NC valve for supplying compressed air to the compressed air channel (VL) and for blocking the connection between the compressed air supply (K) and the compressed air channel (VL). [3] Device according to claim 1 or 2, wherein the second valves (SMA1, SMA2, SMA3) are each formed with a 3 / 3 valve for supplying compressed air from the compressed air channel (VL) to an associated air cushion (LK1, LK2, LK3) in a first switching position, for discharging compressed air from an associated air cushion (LK1, LK2, LK3) into the environment in a second switching position and for blocking the valve in a third switching position. [4] Device according to claim 1 or 2, wherein the second valves (SMA1, SMA2, SMA3) are each formed with a 3 / 2 valve for supplying compressed air from the compressed air channel (VL) to an associated air cushion (LK1, LK2, LK3) in a first switching position and for discharging compressed air from an associated air cushion (LK1, LK2, LK3) into the environment in a second switching position. [5] Device according to one of claims 1 to 4, wherein the first valve (EM) is formed with at least one valve with a magnetic actuator, with a piezo actuator or with an electroactive polymer actuator. [6] Device according to one of claims 1 to 5, wherein the second valves (SMA1, SMA2, SMA3) are formed with an actuator with a shape memory alloy wire. [7] Method for operating a device according to one of claims 1 to 6, in which, for filling and emptying an air cushion (LK1, LK2, LK3), first the associated second valve (SMA1, SMA2, SMA3) is actuated and then the first valve (EM).

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