GB2319429A

GB2319429A - Vibration detector/acoustic generator

Info

Publication number: GB2319429A
Application number: GB9723625A
Authority: GB
Inventors: Enrico Bosco
Original assignee: Bitron SpA
Current assignee: Bitron SpA
Priority date: 1996-11-12
Filing date: 1997-11-07
Publication date: 1998-05-20
Anticipated expiration: 2017-11-07
Also published as: DE29720005U1; FR2755761B3; FR2755761A3; GB9723625D0; ES1038743Y; ES1038743U; ITTO960227U1; GB2319429B; IT239847Y1; ITTO960227V0

Abstract

The device comprises a housing 1 in which an acoustic warning device is mounted. The warning device includes a piezo electric transducer 4 which can generate acoustic signals when it receives electrical activation signals. A chamber 7 is defined in the housing 1 and a ball 8 is disposed with clearance in the chamber. The ball 8 is able to move and so generate a noise by interaction with the walls of the chamber 7. The transducer 4 is reversible and can generate electrical signals correlated with the noise generated by the body 8. The device is particularly useful with washing machines and dishwashers.

Description

2319429 1 A DEVICE FOR DETECTING VIBRATIONS AND FOR GENERATING ACOUSTIC

SIGNALS The present invention relates to a device for detecting vibrations of machines such as washing machines and dishwashers.

The device according to the invention comprises: a housing in which an acoustic warning device is mounted, the warning device including an electroacoustic transducer which can generate acoustic signals when it receives electrical activation signals, a chamber being defined in the housing, and a body being disposed with clearance in the chamber and being able to be moved and to generate a noise by interaction with the walls of the chamber as a result of a vibration of the housing, the transducer being reversible in that it is able to generate electrical signals in response to the noise generated by the body.

The device according to the invention may be fixed, for example, to the suspended portion of a washing machine in order to supply to an electronic unit controlling the operation of the machine signals which can be used, for example, to identify an unbalanced condition of the laundry in the drum, for example, during a spinning stage.

The device according to the invention may be used, in 2 general, for detecting vibrations generated in a washing machine or dishwasher, for example, the vibrations generated in operation as a result of the activation of the motor which drives the drum or of the motor of the draining pump of a washing machine.

As well as enabling operational or anomalous vibrations to be detected during some stages of the working cycle of a washing machine or dishwasher, the device according to the invention enables acoustic signals to be generated during other stages of the working cycle in order to indicate to the user that certain operative conditions have arisen.

Further characteristics and advantages of the invention will become clear from the following detailed description given purely by way of nonlimiting example, with reference to the appended drawings, in which:

Figure 1 is a perspective view of an embodiment of the device according to the invention; Figure 2 is an axial section taken on the line II-II of Figure 1; and Figure 3 is an electrical block diagram of a device according to the invention.

With reference to Figures 1 and 2, a device according to the 3 invention comprises an essentially rigid housing 1 made, for' example, of a plastics material such as ABS. In the embodiment shown, the housing is substantially cup-shaped and an internal tubular element 2 extends from its base wall, a duct 3 being defined in the element 2 and opening outside the housing.

Adjacent the end of the element 2, inside the housing 1, there is an electroacoustic transducer 4 which, in the embodiment illustrated, has a substantially cylindrical body 5.

The transducer 4 is reversible, that is, it can transform acoustic vibrations into an electrical signal, and can generate acoustic vibrations when an electrical activation signal is applied to it.

The transducer 4 is of known type and comprises, for example, a disc of piezoelectric material which is mounted inside the casing 5 and to which two electrical terminals 6, projecting from the casing, are connected.

The face of the casing or body 5 of the transducer 4 facing the wall la of the housing 1 has an aperture Sa through which an acoustic signal is emitted when an electrical activation signal is applied to the terminals 6. This aperture Sa advantageously faces the duct 3 defined in the element 2 of the housing 1.

4 A cylindrical, annular chamber is defined inside the housing' 1 between the end wall la and the body 5 of the transducer 4. In this chamber, there is a body 8 constituted, for example, by a metal ball having a diameter smaller than both the radial width R and the axial length A of the chamber 7.

A circuit board, generally indicated 9, is mounted inside the housing 1 in the vicinity of the open end thereof. This board carries the components of circuits for processing signals generated by the transducer 4.

The board 9 has a peripheral appendage 9a which extends out of the housing 1 through a slot thereof. The appendage carries electrically conductive elements such as printed tracks 11 to external circuits, for connecting the circuits carried by the plate.

The housing 1 has one or more external appendages 12 for enabling it to be f ixed to a member or part of a washing machine or dishwasher. In the embodiment illustrated, the housing 1 has three equiangular ly- spaced appendages 12 having respective holes 13 for the passage of screws or other fixing members.

As shown schematically in Figure 3, the circuits for processing the signals generated by the transducer 4 in operation may comprise, for example, an amplifier 14, followed by a processing circuit 15, such as for example, an integrator circuit. The output of the circuit 15 is connected to a terminal carried by the connection appendage 9a of the printed circuit board 9.

4 The device described above operates in the following manner.

During the stages of the working cycle of a washing machine or dishwasher in which the device is used as a detector, the vibrations transmitted to the housing 1 cause the body 8 to move inside the chamber 7. By interacting with the walls of the chamber, the body 8 generates an acoustic noise with pulsed characteristics and the transducer 4 correspondingly supplies a pulsed electrical signal which, after it has been intensified by the amplifier 14, is transformed into a substantially continuous signal by the integrator circuit 15. The amplitude of the signal is indicative of the intensity of the vibrations detected and can be compared with predetermined threshold levels in external circuitry.

As stated above, the device can be used as a vibration detector, for example, for identifying an unbalanced condition of the laundry in the drum of the washing machine, or for detecting operating conditions (anomalous or not) of the water-draining pump.

In other stages of the operating cycle of the machine, the device may be used as an acoustic warning device. In this case, an activation signal is applied to the terminals 6 of 6 the transducer 4 and the transducer correspondingly generates' an acoustic signal. The signal for activating the transducer may come from an oscillator or other known control circuit which may be outside the device according to the invention or may be carried by the board 9 thereof.

Naturally, the principle of the invention remaining the same, the forms of embodiment and details of construction may be varied widely with respect to those described and illustrated purely by way of non-limiting example, without thereby departing from the scope of the invention as defined in the appended claims.

7

Claims

1. A device f or detecting vibrations of washing machines and dishwashers, comprising: a housing (1) in which an acoustic warning device is mounted, the warning device including an electroacoustic transducer (4) which can generate acoustic signals when it receives electrical activation signals, a chamber (7) being defined in the housing (1), and a body (8) being disposed with clearance in the chamber (7) and being able to be moved and to generate a noise by interaction with the walls of the chamber (7) as a result of a vibration of the housing (1), the transducer (4) being reversible in that it is able to generate electrical signals in respect to the noise generated by the body (8).

2. A device according to claim 1, characterized in that the chamber (7) is annular and the movable body (8) is spherical with a diameter smaller than the radial width (R) of the chamber (7).

3. A device according to claim 2, characterized in that the sphere (8) has a diameter smaller than the axial length (A) of the chamber (7).

4. A detector according to claim 2 or claim 3, characterized in that the housing (1) has an internal tubular element (2) around which the chamber (7) is defined and in which a duct (3) opening outside the housing (1) is defined, 8 the transducer (4) having a body (5) of which a wall facing' the chamber (7) has an aperture (5a) for the emission of the acoustic signal, the aperture (5a) facing the duct (3) defined in the tubular element (2).

5. A device according to any one of claims 2 to 4, characterized in that the housing (1) is substantially cup shaped and the chamber (7) is adjacent its base wall (1a), the transducer (4) being disposed in an intermediate position in the housing (1), and a board (9) carrying components (10) of circuits (14, 15) for processing signals generated by the transducer (4) being mounted adjacent the transducer (4).

6. A device according to claim 5, characterized in that the processing circuits (14, 15) comprise an amplifier (14) and an integrator circuit (15).

7. A device according to claim 5 or claim 6, characterized in that the circuit board (9) has an appendage (9a) projecting from the housing (1) and carrying conductor elements (11) for connecting the circuits (14, 15) and the transducer (4) to external circuits.

8. A device according to any one of the preceding claims, characterized in that the housing (1) has at least one external appendage (12) for enabling it to be fixed to a member of a washing machine or dishwasher.

9 9. A device according to any one of the preceding claims,' characterized in that the transducer (4) is piezoelectric.

10. A device for detecting vibrations of washing machines and dishwashers substantially as herein described by way of example with reference to the accompanying drawings.