EP1291590A2

EP1291590A2 - Air diffuser

Info

Publication number: EP1291590A2
Application number: EP02078023A
Authority: EP
Inventors: Pertti Ojala
Original assignee: Flakt Oy; Flaekt Woods AB
Current assignee: FLAEKT OY
Priority date: 2001-09-06
Filing date: 2002-07-24
Publication date: 2003-03-12
Also published as: NO20023822L; NO20023822D0; FI20011765A0; EP1291590A3

Abstract

An air diffuser is provided 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 comprising a diagonal bridge (1) or a similar member with a hollow-cavity flow control disc (3) affixed thereto, and a diffuser body, whereby the flow control disc has an actuator (4) connected thereto for moving the flow control disc between two limit positions called the minimum-opening position and the maximum-opening position. The invention is implemented by way of using as the actuator a stepper motor (4) mounted in the hollow cavity of the flow control disc (3) and having its shaft equipped with an outer thread which cooperates with a compatible inner thread made in a central hole of the diagonal bridge member (1) of the diffuser.

Description

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 comprising a diagonal bridge or a similar member with a hollow-cavity flow control disc affixed thereto, and a diffuser body, whereby the flow control disc has an actuator connected thereto for moving the flow control disc between two limit positions called the minimum-opening position and the maximum-opening position.
These kinds of controllable air diffusers are also known as supply air flow regulators. Their function is either in a preset manner or controlled by the environmental parameters or in some other fashion automatically or manually adjust the flow control disc position in an inlet or outlet diffuser. As a result, the volumetric air flow passing via the diffuser is varied as a function of the flow control disc position.
Today, a plurality of controllable supply 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, alternatively, 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. However, an external actuator generally occupies a large volume in the diffuser.
Furthermore, in the art are known air diffusers equipped with a thermal actuator based on the large thermal expansion of beeswax, for instance.
Unfortunately, unless link levers or other similar mechanisms are employed, 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.
Still further in the art is known from Fl patent application 20001464 to the applicant an air diffuser equipped with an actuator driven by a memory metal actuator.
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 the actuator is a stepper motor mounted in the hollow cavity of the flow control disc and having its shaft equipped with an outer thread which cooperates with a compatible inner thread made in a central hole of the diagonal bridge member of the diffuser.
A preferred embodiment of the invention is characterized in that the stepper motor body is provided with a sliding bushing that prevents rotation of the flow control disc during its actuation by the stepper motor.
Another preferred embodiment of the invention is characterized in that the sliding bushing, on its side facing the air duct, is provided with a control logic card of the stepper motor adapted to control the operation of the stepper motor as required.
A still another preferred embodiment of the invention is characterized in that the control logic card, together with the sliding bushing and the stepper motor, is secured by screws on the flow control disc, whereby the entity formed by the stepper motor, the sliding bushing and the control logic card is substantially housed in the hollow cavity of the flow control disc.
The benefits of the invention are appreciated in the extremely accurate flow rate control achieved by virtue of the stepper motor and the minimal space requirement thereof accomplished by accommodating the stepper motor in the hollow cavity of the flow control disc thus utilizing this "waste space". A further benefit is achieved by having the stepper motor in the hollow space of the flow control disc concealed from the main flow of air, thereby dampening possible disturbing noise emission generated by the stepper motor.
In the following, the invention is described in more detail with reference to the appended drawings in which
FIG. 1 shows a cross-sectional view of an embodiment of an air diffuser according to the invention having the diffuser driven to its closed position later called the minimum-opening position; and
FIG. 2 shows a cross-sectional view of the air diffuser according to the invention having the diffuser driven to its open position later called the maximum-opening position.
This kind of diffuser or air flow regulator is intended to be mounted at the end of an air duct ending on the surface of a wall, ceiling or similar structure (not shown in the diagrams).
In an air flow regulator, the span range of flow control disc movement is generally made adjustable. Herein, the limit position closest to the maximally closed position of the diffuser is called the minimum-opening or home position of the diffuser. Respectively, the other limit position is called the maximum-opening or boost position.
In the diagrams, reference numeral 1 generally denotes a diagonal bridge member. Substantially at the center thereof, the diagonal bridge member has a hole having on the inner rim thereof fitted an inner thread insert that further has a bushing 2 of a polymer material affixed thereto. To the flow control disc 3 of the diffuser is connected a stepper motor 4 having its shaft with an outer thread fitted into the inner thread insert of the diagonal bridge member. To the body of motor 4 is affixed a sliding bushing 5 serving to prevent the rotation of the flow control disc when it is being actuated by the stepper motor. To the exterior side of the sliding bushing, on its side facing the air duct, is mounted a stepper motor control logic card 6 adapted to control the operation of the stepper motor as required. The control logic card, together with the sliding bushing and the stepper motor, is secured by screws on the flow control disc. In this fashion, the stepper motor, the sliding bushing and the control logic card form an integrated unit having the stepper motor and its control logic card substantially concealed in the hollow cavity of the flow control disc. Soldered thereon, the control logic card is provided with switches permitting a desired predetermined control span (that is, the control span limit points known as the minimum-opening and maximum-opening position) of the flow control disc movement to be selected. If so desired, also a relative-humidity sensor may be placed on the control logic card.
The function of the air diffuser illustrated in the diagrams is as follows. The home position is assumed to be the minimum-opening position of the diffuser shown in FIG. 1 which is preset during the tuning of the diffuser. In this position, the diffuser is in a slightly opened state. When the diffuser must be opened more, a control signal is given to control logic card 6, e.g., by establishing a current loop via diffuser control sensor or switch. The sensor may be an external sensor (operating switch, motion sensor or the like) or a relative-moisture sensor integrated directly on the control logic card. When active, the control signal turns on the operating voltage of the stepper motor, whereby the motor drives the flow control disc toward its maximum-opening position by a predetermined span (preset at the factory or on site). Respectively, the flow control disc is driven back into its minimum-opening position when the stepper motor receives a control signal indicating the end of enhanced ventilation need. This signal may originate from a timer, RH sensor, operating switch or the like. The flow control disc is returned into its minimum-opening position by stepping the motor in a reverse direction by the same number of steps as used for opening the diffuser. Also a mechanical stop 8 is provided to ensure that the disc movement does not exceed the minimum-opening position. Additionally, the zeroing-in on the minimum-opening position may be carried out by performing, e.g., once a day a "training cycle" during which the flow control disc is urged for a short time against stop 8.
To a person skilled in the art it is obvious that the invention is not limited by the above-described exemplary embodiment, but rather may be varied within the inventive spirit and scope of the appended claims.

Claims

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 comprising a diagonal bridge (1) or a similar member with a hollow-cavity flow control disc (3) affixed thereto, and a diffuser body, whereby the flow control disc has an actuator (4) connected thereto for moving the flow control disc between two limit positions called the minimum-opening position and the maximum-opening position, characterized in that said actuator is a stepper motor (4) mounted in the hollow cavity of the flow control disc (3) and having its shaft equipped with an outer thread which cooperates with a compatible inner thread made in a central hole of the diagonal bridge member (1) of the diffuser.
Air diffuser according to claim 1, characterized in that the body of said stepper motor (4) is provided with a sliding bushing (5) that prevents rotation of the flow control disc (3) during its actuation by the stepper motor.
Air diffuser according to claim 1 or 2, characterized in that said sliding bushing (5), on its side facing the air duct, is provided with a control logic card (6) of stepper motor (4) adapted to control the operation of the stepper motor as required.
Air diffuser according to claim 3, characterized in that said control logic card (6), together with said sliding bushing (5) and said stepper motor (4), is secured by screws on the flow control disc (3), whereby the integrated entity formed by the stepper motor, the sliding bushing and the control logic card is substantially housed in the hollow cavity of the flow control disc.
Air diffuser according to claim 3 or 4, characterized in that a relative-humidity sensor (7) is mounted on said control logic card(6).
Air diffuser according to any one of foregoing claims 1-5, characterized in that the flow control disc return movement into its minimum-opening position is secured by a mechanical stop (8).