Controllable air diffuser

Abstract

 Air diffuser for rooms and similar spaces, the diffuser being intended for mounting at the end of an air duct ending on the surface of a wall, ceiling or similar structure, and the air diffuser being comprised of an arcuate brace (1) or a similar member with a flow control disc (4) and diffuser body (3) mounted thereon, the flow control disc (4) having an actuator connected thereto for moving the flow control disc (4) between two limit positions called the minimum-opening position and the maximum-opening position, the actuator being equipped with spring elements (7, 11) of which at least one first spring is adapted to serve for moving the flow control disc (4) toward the maximum-opening position while at least one second spring serves for moving the flow control disc toward the minimum-opening position. The invention is implemented so that at least one of said spring elements is a thermally actuated memory metal spring (11) whose spring constant is capable of changing with temperature in a preprogrammed manner.

Description

[0001] The present invention relates to an air diffuser for rooms and similar spaces, the diffuser being intended for mounting at the end of an air duct ending on the surface of a wall, ceiling or similar structure, and the air diffuser being comprised of an arcuate brace or a similar member with a flow control disc and diffuser body mounted thereon, the flow control disc having an actuator connected thereto for moving the flow control disc between two limit positions called the minimum-opening position and the maximum-opening position, the actuator being equipped with spring elements of which at least one first spring is adapted to serve for moving the flow control disc toward the maximum-opening position while at least one second spring serves for moving the flow control disc toward the minimum-opening position.

[0002] These kind of controllable air diffusers are also known as dampers. Their function is either in preset manner or controlled by the environmental parameters or in some other fashion to perform controlledly or manually the adjustment of the flow control disc position in an inlet or outlet diffuser. Resultingly, the volumetric air flow passing via the diffuser is varied as a function of the flow control disc position.

[0003] Today, a plurality of controllable air diffusers are known in the art with various kinds of implementations. In the simplest diffuser constructions, the flow control disc is rotated by fingers into a desired position or a string or the like member may be attached thereto so that the flow control disc position can be adjusted by pulling therefrom. As to controllable air diffusers equipped with an externally powered actuator, a typical diffuser construction may use an electric motor as the prime mover. This kind of controllable diffuser generally provides reliable function combined with a large amplitude and accurate control of the flow control disc position adjustment. Air diffusers actuated by an electric motor are, however, costly to manufacture. Furthermore, in the art are known air diffusers equipped with a thermal actuator based on the large thermal expansion of beeswax, for instance. Unless link levers or other similar mechanisms are employed, however, the amplitude of flow control disc position adjustment in diffusers controlled by a wax thermostat remains marginal indeed. Moreover, these thermal actuators tend to fail in an unexpectedly short time. A still further category of controllable air diffusers is formed by those driven by a solenoid. However, these actuators require a high drive current and are noisy in operation.

[0004] It is an object of the present invention to provide an air diffuser free from the disadvantages of prior-art controllable air diffuser constructions. The air diffuser according to the invention is characterized in that at least one of its spring elements is a thermally-controllable memory metal spring, whose spring constant changes with temperature in a predetermined fashion. The spring constant of the memory metal spring can be designed to change with temperature so that the force exerted by the memory metal spring becomes sufficiently large to overcome the force of the flow control disc return spring. Then, the flow control disc is actuated to move toward its maximum-opening position. Obviously, the memory metal spring may also be given the task to act as the flow control disc return spring, whereby the roles of the springs are changed so that the second spring serves to actuate the flow control disc toward its open position and the activation of the memory metal spring causes the mechanism to overcome the force of the first spring so that the flow control disc is forced toward its minimum-opening position, either fully closed or at least closer to this position from that preceding the heating of the memory metal spring.

[0005] A first preferred embodiment of the invention is characterized in that the flow control disc actuator is equipped with a heater means for heating the memory metal spring. The heater means may comprise a heater body with a heater wire or element mounted thereto for controlled heating of the memory metal spring.

[0006] A second preferred embodiment of the invention is characterized in that the heat imposed on the memory metal spring becomes from the environment in the form of, e.g., ambient heat in sauna applications. Then, the diffuser may operate so that, e.g., when the temperature in the sauna rises to a predetermined level, the temperature activates the memory metal spring that subsequently actuates the flow control disc so as to enhance the conditioning of the sauna atmosphere.

[0007] The benefits of the invention may be appreciated in its simplicity of the air diffuser construction, reliable function and longevity of the memory metal element. Additionally, the memory metal spring facilitates as large amplitudes of position movements of the flow control disc as may be desired. The long life of the actuator mechanism is also a major advantage.

[0008] In the following, the invention is described in more detail with reference to the appended drawings in which

FIG. 1 shows an air diffuser according to the invention in an oblique front view;

FIG. 2 shows a cross-sectional view of the air diffuser according to the invention in its closed position (minimum-opening position); and

FIG. 3 shows a cross-sectional view of the air diffuser according to the invention in its open position (maximum-opening position);

[0009] Now referring to FIG. 1, therein is shown an air diffuser according to the invention. As shown in the diagram, the construction comprises an arcuate brace 1, an actuator means 2 connected to the brace, an air diffuser body 3 and a flow control disc 4 with a position control. This kind of air diffuser may be used as, e.g., an inlet or an outlet diffuser. It may be installed in the spaces of a house or an industrial/commercial building or any similar premise as the outlet diffuser of an air duct, e.g., on the surface of a wall or ceiling.

[0010] Detailed construction of the air diffuser can be seen in FIG. 2, wherein an air diffuser according to the invention is shown in a closed position or a predetermined limit position called a minimum-opening position. According to the invention, it is advantageously possible to predetermine or preset the desired span of flow control disc movement. Hereby, the closed or at least substantially most closed position of the diffuser is called the minimum-closing position. Respectively, the other limit position is called the maximum-closing position.

[0011] As is evident from FIG. 1, reference numeral 1 denotes an arcuate brace conventionally used in air diffusers of the kind concerned herein. To the arcuate brace is fixed a body 2 of the actuator moving the flow control disc. The diffuser body is respectively denoted by reference numeral 3. As is conventional in diffusers of this type, the flow control disc 4 as well as the diffuser body 3 are shaped slightly conical on their exterior side thus forcing the air flow to take place via an annular passageway 5 formed therebetween. The cross section of this passageway is determined by the position of the flow control disc. In the position shown in FIG. 2, the flow control disc 4 is actuated into a position wherein the cross section of the passageway 5 is relatively small. Respectively, in the situation shown in FIG. 3, the passageway 5 is actuated into a substantially more open state, whereby a larger volumetric air flow is facilitated via the diffuser.

[0012] The body 2 of the actuator is hollow and cylindrical. The actuator body extends from the arcuate brace, whereto it is connected, toward the flow control disc 4, whereto it is not connected. To the end of the actuator body 2 situated closer to the flow control disc 4, there is made a inner collar 2' that extends radially inwardly toward the longitudinal center axis of the cylindrical body of the actuator. The inner diameter of the center bore in the inner collar 2' is made essentially equal to the external diameter of a cylindrical, hollow sliding shaft 6 that is adapted into the interior space of the actuator and in turn is connected to the flow control disc 4. The sliding shaft 6 extends from the flow control disc toward the arcuate brace and has at its distal end formed thereto a outer collar 6' extending radially outwardly from the longitudinal center axis and having an outer diameter essentially equal to the inner diameter of the actuator body 2. Into the space between the actuator body 2 and the sliding shaft 6 is adapted a return spring 7 that has its one end resting against the inner collar 2' of the actuator body 2 and the other end against the outer collar 6' of the sliding shaft 6. In the embodiment described herein, the function of the return spring 7 is to push the outer collar 6' of the sliding shaft 6 against the arcuate brace and thus to urge the flow control disc toward its minimum-opening position.

[0013] To the arcuate brace 1 and/or the actuator body 2 is attached the fixed body 8 of a heater element having formed therein an elongated peg member 8' that, with a diameter smaller than that of the interior bore of the sliding shaft and having a heater wire 9 wound thereabout, extends into the interior of the sliding shaft. To make the free length of the interior bore of the sliding shaft shorter, a bushing 10 or similar member serving for the same purpose is inserted into the bore at its end facing the flow control disc. Between the bushing 10 and the heater body 8 is adapted a thermally actuated memory metal spring 11 that does not in its normal state exhibit any substantial spring constant force. In this situation, the force exerted by the return spring 7 can clearly overcome the force exerted by the memory metal spring, thus causing the flow control disc to stay in its minimum-opening position.

[0014] The function of the air diffuser implemented according to the embodiment shown in the diagrams is as follows: the initial position herein is assumed to be the minimum-opening position that is illustrated in FIG. 2 and is preset to the position shown. Herein, the air diffuser may be preset fully closed or into a slightly open position as desired. To open the air diffuser, the heater wire or element 9 is heated by electric current, for instance. Resultingly, the memory metal spring 11 is heated therefrom by thermal radiation or conduction, for instance. In the illustrated embodiment, the heater wire or element 9 is wound about the peg member 8' of the heater body 8. When heated, the memory metal spring acts in the manner "programmed" thereto during its manufacture. This means that the spring expands or bends in the same predictable manner at all times. By giving the memory metal element a coiled form, it is possible to achieve a very long stroke thereof if so desired. Accordingly, the spring constant force exerted by the memory metal spring 11 changes, whereby the memory metal spring can overcome the counter force exerted by the return spring 7 thus causing the flow control disc to move to the right in the view of FIG. 2, i.e., toward the maximum-opening position of the flow control disc that also has a preset limit. In this manner it is possible to control the degree of air diffuser opening either in steps by introducing a given amount of additional heat to the memory metal spring or even steplessly if so desired. The simplest possibility is to omit any intermediate position by allowing the flow control disc to move directly between its minimum-opening position and its maximum-opening position.

[0015] The maximum-opening position of the air diffuser is shown in FIG. 3. Herein, the memory metal spring 11 that has been activated by the applied heat exerts its force on the bushing 10 that has moved the sliding shaft to the right in the view of the diagram, whereby the flow control disc has moved into its maximum-opening position wherein the cross section of the air flow channel 5 is maximally open. The air diffuser stays in this maximum position as long as the memory metal spring 11 is maintained heated. When heating is removed, the memory metal spring 11 loses its spring constant force and the return spring 7 can push the flow control disc back into its minimum-opening position.

[0016] As the control of the opening/closing movements of the air diffuser may be readily implemented today in an automatic and preprogrammed using any suitable control technology, such details may be omitted as irrelevant to the present invention.

[0017] The invention may also be applied to, e.g., sauna spaces so that the air diffuser has no heater elements, but rather, the memory metal is "programmed" to operate in a desired manner with variations in the ambient temperature. In practice, the memory metal spring is designed to become active at a given elevated temperature of the sauna atmosphere thus actuating the air diffuser into its open position.

[0018] Furthermore, it is possible to use the memory metal spring as the return spring. Herein, a "conventional" spring is adapted to actuate the air diffuser into its open (or maximum-opening) position, while the activation of the memory metal spring by heat causes the same to close the air diffuser. This feature can be utilized, e.g., in smoke vent applications wherein the air-conditioning diffusers shall not uncontrolledly open in fire. This safety measure may readily be complemented with such a function that forces the flow control disc in a closing air diffuser to lock into this closed position, wherefrom it cannot be reopened but by pushing a reset button or the like.

[0019] The above-described exemplifying embodiment was elucidated by way of assuming the heating of the memory metal spring to take place indirectly, e.g., from heater wires or the like means. Obviously, the electric current may as well be applied to the memory metal spring thus causing the heating of the same.

[0020] To a person skilled in the art it is obvious that the invention is not limited by the above-described exemplifying embodiment, but rather may be varied within the inventive spirit and scope of the appended claims. As the art of memory metals is known from plural publications and intensive research into the matter has already been conducted over decades, it is unnecessary to discuss the details of memory metal compositions and the behavior thereof herein. Accordingly, a person skilled in the art has no difficulty in selecting a suitable memory metal material in the implementation of the present invention and then performing the necessary "programming" thereof.

Claims

1. Air diffuser for rooms and similar spaces, the diffuser being intended for mounting at the end of an air duct ending on the surface of a wall, ceiling or similar structure, and the air diffuser being comprised of an arcuate brace (1) or a similar member with a flow control disc (4) and diffuser body (3) mounted thereon, the flow control disc (4) having an actuator connected thereto for moving the flow control disc (4) between two limit positions called the minimum-opening position and the maximum-opening position, the actuator being equipped with spring elements (7, 11) of which at least one first spring is adapted to serve for moving the flow control disc (4) toward the maximum-opening position while at least one second spring serves for moving the flow control disc toward the minimum-opening position, characterized in that at least one of said spring elements is a thermally actuated memory metal spring (11) whose spring constant is capable of changing with temperature in a preprogrammed manner.

2. Air diffuser according to claim 1, characterized in that said actuator is equipped with a heater for heating said memory metal spring (11).

3. Air diffuser according to claim 2, characterized in that said heater comprises a heater body (8, 8') with a heater wire or element (9) adapted thereto for controlled heating of said memory metal spring (11).

4. Air diffuser according to claim 1, characterized in that the heat applied to said memory metal spring (11) is ambient heat, e.g., in sauna applications.

5. Air diffuser according to claim 1, characterized in that the heating of said memory metal spring (11) is implemented by direct application of electric current to said spring (11).

6. Air diffuser according to any one of foregoing claims, characterized in that said actuator for moving said flow control disc comprises a hollow, cylindrical, stationary body (2, 2') with a movably into the center bore thereof mounted and similarly hollow, cylindrical sliding shaft (6, 6') connected to said flow control disc (4), operative between said actuator body (2, 2') and said sliding shaft (6, 6') a return spring (7) acting so as to push said flow control disc (4) toward its minimum-closing position, connected to said arcuate brace (1) and/or to said actuator body (2, 2') a heater body (8) including an elongated peg member (8') extending toward said flow control disc and having a heater wire or element (9) adapted thereabout, and a memory metal spring (11) that has its one end resting against the stationary heater body (8) and the other end resting either directly or indirectly via a bushing (10) against said flow control disc (4) and said memory metal spring (11) being adapted under activation by heat to push said flow control disc (4) toward its maximum-opening position with a force that overcomes the counter force exerted by said return spring (7).

Drawing