EP0043970B1

EP0043970B1 - Pneumatically controlled delay switch

Info

Publication number: EP0043970B1
Application number: EP19810105018
Authority: EP
Inventors: Giovanni Foggini
Original assignee: Lear SNC di Foggini and C
Current assignee: Lear SNC di Foggini and C
Priority date: 1980-07-10
Filing date: 1981-06-29
Publication date: 1984-11-07
Also published as: DE3167062D1; EP0043970A1

Description

This invention relates to a pneumatically controlled delay switch, particularly for passenger car and motorvehicle courtesy lamps, the term "courtesy lamp(s)" referring herein to lamps which are usually mounted in a vehicle passenger compartment and turned on upon opening at least one door thereof and off upon closing the same.
The invention is essentially directed to providing a delayed action switch, that is one effective to turn the lamps off with a short time delay after the vehicle door has been closed, in order to keep the vehicle interior lighted for a sufficient time duration to insert the ignition key or perform other comparable functions after the door of the vehicle has been closed.
Known in the art are delay switches adapted for turning the courtesy lamps off after the doors have been closed which are based on the utilization of bimetal timers, or of monostable electronic circuits with time constants which can be preset as desired.
However, the use of such known switches has shown to be disadvantageous, on one hand owing to the disproportionate cost to the function they are to perform, and on the other hand on account of the excessively complicated construction of such switches, which makes them liable to failure particularly because they are installed at locations on the vehicle body where they are exposed to weather, dirt, dust, and the like contaminating agents.
Document US-A-3,300,755 discloses a device provided with pneumatic means in order to delay the opening of the electrical contacts of an illuminating system for the interior of a vehicle. The structure of the switch is complicated and it occupies much space, particularly in the longitudinal direction.
It is a primary object of this invention to eliminate all such disadvantages by providing a delay switch as indicated, which has an extremely simple construction, is relatively inexpensive, can be installed with the utmost ease and without involving any alteration of the existing electric circuitry, is reliable in operation, and especially impervious to weather.
According to the invention, these and other objects, such as will be apparent hereinafter, are achieved by a delay switch characterized essentially in that it comprises first and second elastically deformable pneumatic chambers, separated by a partition including a differential valve adapted for allowing a slow transfer from the first into the second chamber of the air contained in the system upon the first chamber being squeezed by the closing movement of a vehicle door and a quick return to the initial rest configuration as said first chamber is relieved of such pressure, the second chamber having a movable electric contact which disengages from a corresponding fixed contact to open the electric circuit with the second chamber in the maximum inflation condition thereof, substantially upon completion of said slow transfer of air from the first into the second chamber.
Advantageously, according to the invention, said differential valve comprises a pair of overlaid membranes having markedly different elastic properties, the stiffer membrane being formed with at least one hole shut off by the more elastic membrane which, with the direction of the transfer airflow occurring from the first into the second chamber is urged to adhere closely against said hole, thus enabling the transfer to occur by leakage or bleeding, and with the transfer airflow occurring in the opposite direction, disengages from said hole to allow a fast return of the air from the second into the first chamber.
Further features and advantages will be more apparent from the following detailed description, with reference to the accompanying drawings, where:

Figure 1 is a perspective view of a passenger car showing the location of a switch according to the invention thereon;
Figure 2 is a schematical longitudinal section of said switch; and
Figure 3 is a detail view of a differential valve advantageously suitable for use in the switch of this invention.

In the drawing figures, reference I designates generally this delay switch as intended for installation on a fixed portion of a passenger car body, such as the upright M of the door P, at such a position as to be engaged by the door when the latter is in its closed condition and disengaged therefrom with the door in the open condition.
The delay switch, which comprises two pneumatic chambers 10-20, respectively calied first chamber and second chamber hereinafter, is installed with the first chamber 10 on the upright exterior and the second chamber 20 on the upright interior, the first chamber being, therefore, the one to be engaged by the door, which squeezes it to a configuration of least volume. The two chambers, which are advantageously formed from an elastomeric material, are preferably made in the form of a bellows and interconnected in airtight sealed and overlapping relationship, as through a preferably metal ring nut 11 which also serves for connecting the switch to the metal sheet portion of the upright M. Between said chambers, and clamped tightly by the action of the ring nut 11, a partition diaphragm 12 is provided incorporating a differential valve schematically indicated at 13 in Figure 2. The function of said valve is of allowing a slow transfer of the pneumatic fluid-contained in the system made up of the two chambers-from the first into the second chamber when said first chamber is engaged and squeezed by the door P, and a fast return of the fluid in the opposite direction, namely from the second into the first chamber, when the latter, being disengaged from the door, tends to recover its original configuration.
A movable contact is attached to the second chamber, comprising an elastically yielding metal reed 14 and being adapted to cooperate with a ground rheostat 15, advantageously formed by a screw arranged on the upright M adjacent the switch I. The arrangement is such that when the chambers 10 and 20 are both in their rest condition, corresponding to an equal pressure of the pneumatic fluid contained therein, the contact 14 will engage the rheostat 15 to close the circuit which turns the courtesy lamps on; said configuration being the one which corresponds to the open condition of the door P. Conversely, when the door is closed, it will deform the first chamber 10 with a squeezing action, thus producing an increase of pressure of the air contained in it and a resulting transfer of air from the first into the second chamber, with a slowed down flow under control by the valve 13. The second chamber 20 is, therefore, slowly deformed until it produces the separation of the reed 14 from the rheostat 15 and consequent breaking of the lamp circuit, thereby the lamps are turned off, the switch off time delay being proportionate to the flow rate through the valve 13 for the air transfer direction from the first into the second chamber.
The above-described operation is advantageously accomplished by utilizing a valve 13 as shown in Figure 3, where it may be noted that said valve comprises first and second membranes 16, respectively 17, in overlapped relationship. The membranes, which are both formed from an elastically yielding material, have markedly different thickness dimensions and, accordingly, elastic properties. The membrane 16, which is the thicker one, has moderate elastic properties and serves for dampening any pressure surges produced in slamming the door shut. The membrane 17, which is much thinner, overlies the former to shut off at least one hole 18 provided in the latter membrane, but such as to allow the air to bleed past it, as indicated by the arrows F, from the chamber 10 (on the left of the membranes in Figure 3) into the chamber 20. This may be accomplished by surrounding the hole 18 with a series of radial grooves, as indicated at 19, of very small cross-sectional area.
It will thus be appreciated that an increase of the pressure within the chamber 10 will tend to urge the membrane 17 against the membrane 16, thereby the air transfer is caused to occur slowly by a bleeding effect, whereas the reverse return flow occurs very rapidly thanks to the raising of the membrane 16, which completely uncovers the opening of the hole 18. To facilitate said fast return flow, it is advantageous that, at least in the chamber 10, a coil spring 21 should be provided which would tend to bring the bellows of said chamber back to its rest or relaxed position.

Claims

1. A pneumatically controlled delay switch, particularly for passenger car courtesy lamps, characterized in that it comprises first (10) and second (20) elastically deformable pneumatic chambers, separated by a partition (12) including a differential valve (13) adapted for allowing a slow transfer from the first (10) into the second (20) chamber of the air contained in the system upon the first chamber (10) being squeezed by the closing movement of a vehicle door (P) and a quick return to the initial rest configuration as said first chamber (10) is relieved of such pressure, the second chamber (20) having a movable electric contact (14) which disengages from a corresponding fixed contact (15) to open the electric circuit with the second chamber (20) in the maximum inflation condition thereof, substantially upon completion of said slow transfer of air from the first (10) into the second (20) chamber.

2. A delay switch according to Claim 1, wherein said first chamber (10) is adapted for engagement by the vehicle door (P), said door (P) squeezing said first chamber (10) to a configuration of least volume thereof.

3. A delay switch according to Claims 1 or 2, wherein said first and second chambers (10, 20) are formed from an elastically yielding material to a bellows-like configuration.

4. A delay switch according to anyone of the preceding claims, wherein said first and second chambers (10, 20) are interconnected in an airtight sealed and overlapping relationship through a ring nut (11), a partition (12) incorporating said differential valve (13) being interposed between said chambers (10, 20) and clamped sealingly by said ring nut (11).

5. A delay switch according to anyone of the preceding claims, wherein said movable contact (14) carried in said second chamber (20) comprises a metal reed (14) and said fixed contact (15) is a ground rheostat (15) in the form of a screw located adjacent said switch.

6. A delay switch according to anyone of the preceding claims, wherein said differential valve (13) comprises a pair of overlapping membranes (16, 17) having markedly different elastic properties, the stiffer membrane (16) being formed with at least one hole (18) adapted to be shut off by the more elastic membrane (17), said more elastic membrane (17), during a transfer direction of the airflow from the first (10) into the second (20) chamber, being urged to adhere against said hole (18), thereby the transfer is caused to occur by a bleeding effect, and during the opposite transfer direction, being disengaged from said hole (18), whereby a quick return of the air is enabled from said second (20) into said first (10) chamber.