IES20010899A2 - Inertial sensor device - Google Patents

Abstract

An inertial sensor device comprises a cylindrical housing (10) (Figure1) containing an inertial sensor and a holder (40) for such housing. The holder (40) comprises a base plate (42) having two pairs of curved convergent arms (44), (46) for resiliently and circumferentially embracing the housing. The housing is slidable into a home position on the holder by inserting one end of the housing between the arms and pushing the housing substantially parallel to its own axis until it engages a detent (52). The detent restrains the housing against both axial and rotational movement relative to the base in the home position. <Figure 3>

Description

Inertial Sensor Device The present invention relates to an inertial sensor device.

According to the present invention there is provided an inertial sensor device comprising a substantially cylindrical housing containing an inertial sensor and a holder for such housing, wherein the holder comprises a base having at least one pair of curved convergent arms for resiliently and circumferentially embracing the housing, and wherein the housing is slidable into a home position on the holder by inserting one end of the housing between the arms and pushing the housing substantially parallel to its own axis until it engages a detent, the detent restraining the housing against both axial and rotational movement relative to the base in the home position.

An embodiment of the invention will now be described,/by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a perspective view of a cylindrical housing containing an inertial sensor; Fig. 2 is a schematic cross-sectional view of the housing of Fig. 1 showing the inertial sensor therein; Fig. 3 is a perspective view of an embodiment of inertial sensor device according to the invention, excluding the sensor housing shown in Figs. 1 and 2; and Figs. 4(a) to (c) are perspective, plan and end views, respectively, of the holder of Fig. 3.

OPEN TO PUBLIC INSPECTION Referring initially to Figs. 1 and 2, a substantially cylindrical housing 10 containing an inertial sensor 12 comprises a hollow cylindrical body 14 with an open end 16 and a hermetically sealed closed end 18. The sensor 12 includes two spaced electrically conductive rods 20 running parallel to each other and to the longitudinal axis of the housing 10. At least one electrically conductive barrel 22 rests on the rods 20 to provide electrical connection between them. The ends (not shown) of the rods project from holes formed in the closed end 18 of the housing to form respective electrical contacts for the sensor, so that associated circuitry can determine the electrical resistance between the rods 20.

A cap 24 is fitted to the open end 16 of the cylindrical body 14 to enclose and hermetically seal the sensor 12. An arrow 26 on the external surface of the cap 24 points in a direction normal to the plane containing the rods 20 to allow a user to position the sensor 12 in its proper orientation for use.

This when the housing 10 is disposed with its axis horizontal and the arrow 26 pointing straight up, so that the barrel (s) rest evenly on the two rods 20.

Finally, the housing 10 has a circumferential groove 28 around the end 16, located behind the periphery of the cap 24, and a plurality of channels 30 evenly spaced around the outside circumference of the body 14 and extending substantially parallel to its axis. (Only a few of the channels 30 are shown in Fig. 2). Each channel 30 continues notionally across the groove 28 into the periphery of the cap 24.

In use the housing 10, containing the sensor 12, is mounted in a holder 40, Figs. 3 and 4. The holder 40 comprises a flat, substantially square base plate 42 having two pairs of curved convergent arms 44, 46 and a detent 52. The lower ends of each pair of arms, i.e. where they join the base plate 42, are connected by a respective web 48 having an arcuate upper edge 50. The pairs of arms 44 and 46 together with their respective webs 48 define two axially aligned circular apertures of a diameter just slightly less than the diameter of the housing 10.

The housing 10 is mounted on the holder 40 by inserting the cap end 16 between the pair of arms 44 and pushing the housing 10 substantially parallel to its own axis, i.e. in the direction of the arrow in Fig. 3, so that it slides between the pairs of arms 44 and 46 to finally engage the detent 52 which defines a home, or fully engaged, position of the housing. During the sliding of the housing 10 towards the detent the arms 44 and 46 are resiliently forced apart to lightly to grip the housing, and projections 54 on the arms 44 and the associated web 48 slidably engage selected channels 30. The projections 54 resist rotation of the housing 10 relative to the holder 40 but do not prevent it, thereby allowing the housing to be rotated to a desired angular orientation, by clicking it round within the arms 44 and 46, just prior to engaging the detent 52.

The detent 52 comprises a shallow flange 56 - best seen in Fig. 4 - which extends transverse to the axis of the housing 10 and which, when the housing reaches its home position, engages the circumferential groove 28 around the end 16 of the housing to restrain the housing 10 against axial movement.

The detent 52 also comprises a rib 58 extending parallel to the axis of the housing 10 for selectively engaging, depending on the angular orientation of the housing, one of the channels to restrain the housing 10 against rotational movement in the home position.

It will be appreciated that the housing 10 is maintained in proper engagement with the detent 52 as aforesaid by the resilient force of the arms 44 and 46 pressing the housing 10 towards the base. However, by lifting the end 16 of the housing away from the detent 52 against the force of the arms, the angular orientation of the housing may be adjusted by rotating the housing within the arms. Then, by releasing the end of the housing the latter is once more brought into positive engagement with the detent by the resilient force of the arms.

The holder 40 is in turn removably mounted in a two-part outer casing of which only the base plate 60 is seen in Fig. 3 (there is also a cover which fits on the base plate in conventional manner to enclose the holder 40 and associated electrical circuitry). The base plate 60 has low walls 62 defining two internal compartments - one compartment 64 for receiving the holder 40 and another compartment 66 for receiving the associated electrical circuitry which may be entirely conventional and will not be further described. In , I use the base plate 60 is fixed to an external surface such as a window frame by screws passing through any one or more screw holes 68.

The compartment 64 has a substantially square floor 7 0 just slightly larger than the base plate 42 of the holder 40. This allows the base plate 42, and hence the holder 40 as a whole, to be snugly inserted in the compartment 64, with the base plate 42 flat against the floor 70, in either one of two mutually orthogonal orientations. The holder is releasably fixed in the selected position by a screw passing through a hole 72. This allows the cylindrical housing 20 carried by the holder 40 to be orientated with its longitudinal axis in either one of two different directions substantially at 90° to one another in a plane parallel to the base plate 60.

This ability to rotate the holder 40 through 90° relative to the outer casing, coupled with the ability to rotate the housing 10 about its own axis within the holder 40, allows the user to position the sensor 12 in its proper orientation of use, i.e. with the housing 10 disposed with its axis horizontal and the arrow 26 pointing straight up, for a wide variety of orientations of the outer casing on horizontal, vertical or inclined surfaces.

When the outer casing of the device is fixed to a surface with the inertial sensor 12 positioned in the proper orientation, any significant vibration of the surface will lift the barrel 22 intermittently away from the rods 20 and create an intermittent electrical open circuit between the rods which can be detected by the associated electrical circuitry. If more than one barrel is used, then the magnitude of the vibration can be determined by the change in resistance between the rods according to whether one or more barrels lift from the rods.

The invention is not limited to the embodiments described herein which may be modified or varied without departing from the scope of the invention.

Claims (6)

Claims

1. An inertial sensor device comprising a substantially cylindrical housing containing an inertial sensor and a holder for such housing, wherein the holder comprises a base having at least one pair of curved convergent arms for resiliently and circumferentially embracing the housing, and wherein the housing is slidable into a heme position on the holder by inserting one end of the housing between the arms and pushing the housing substantially parallel to its own axis until it engages a detent, the detent restraining the housing against both axial and rotational movement relative to the base in the home position.

2. An inertial sensor device as claimed in claim 1, wherein the detent comprises a first projection which engages a circumferential groove around the said one end of the housing to restrain the housing against axial movement, and a second projection for selectively engaging, depending on the angular orientation of the housing, one of a plurality of circumferentially spaced recesses around the said one end of the housing to restrain the housing against rotational movement.

3. An inertial sensor device as claimed in claim 2, wherein the circumferentially spaced recesses are channels extending along the outside of the housing substantially parallel to its axis, and wherein each arm comprises at least one further projection for slidably engaging a selected channel, the further projections resisting but not restraining rotation of the housing between the arms.

4. An inertial sensor device as claimed in claim 1, 2 or 3, further including an outer casing comprising a base plate for fixing to an external surface, the holder being removably mountable in the outer housing so that the cylindrical housing 5. Can be orientated with its axis in either one of two different directions substantially at 90° to one another in a plane parallel to the base plate.

5. An inertial sensor device substantially as described

6. 10 herein with reference to the accompanying drawings.