Patent Description:
Tyre parameter monitoring systems typically include an inflation valve for introducing or removing air from the tyre and an electronic module which includes a sensor unit or measuring one of more parameters of the tyre. The inflation valve is positioned in a bore or hole in the wheel rim and the electronic module is arranged inside the tyre and is coupled with the inflation valve. Such a system may be used to inform the driver of any abnormal variation in the measured parameter, for example the tyre pressure.

One type of tyre parameter monitoring system or tyre pressure monitoring system (TPMS) is known as the snap-in type, in which the inflation valve positioned on the outside of the wheel rim extends through a bore in the wheel rim and is connected to an electronic unit positioned on the inside of the wheel rim by a snap-in connection. Snap-in valves include an elastically deformable stem. An example of such a snap-in system is disclosed in <CIT>.

Another type of tyre parameter monitoring system is known as the clamp-in type. For the clamp-in type it is generally possible to fasten the electronic module in various angular positions with respect to the wheel rim. This enables the system to be mounted on wheel rims of different designs. An example of such a clamp-in system is disclosed in <CIT>.

<CIT>, <CIT>, <CIT> and <CIT> each disclose a tyre parameter monitoring system.

It is desirable to simplify assembly of the tyre parameter monitoring system to the wheel rim. An object of the present invention is, therefore, to provide a tyre pressure monitoring system that can be more easily mounted onto a wheel rim.

According to the invention defined in claim <NUM>, a tyre parameter monitoring system comprises an electronic module comprising a fitting, a valve stem that is connectable with the electronic module, a washer and a rubber seal. The washer comprises interlocking means with which the washer is detachably attachable to the fitting of the electronic module. The rubber seal is clamped between a flat surface of the valve stem and a flat outer surface of the wheel rim in the mounted condition. The washer and the rubber seal provide an airtight connection between the valve stem and the electronic module. The fitting comprises an adapter which protrudes through the washer and is connected with the valve stem and the valve stem is spaced apart from the electronic module and is coupled with the electronic module by means of the adapter and the washer.

A tyre parameter monitoring system is, therefore, provided, in which the washer can be assembled with and disassembled from the electronic module when desired as the washer is detachably attachable by use of the interlocking means to the fitting of the electronic module. Therefore, the tyre parameter monitoring system can be more simply assembled and disassembled since the washer is mechanically detachably attached by use of the interlocking means to the fitting of the electronic module. The washer is used in conjunction with a one or more seals which are used to provide an airtight connection between the valve stem and the electronic module.

In some embodiments, the interlocking means is integral with an overmoulding of the washer. For example, the washer may include a mouldable material such as a plastic or metal which is shaped to form the interlocking means. In some embodiments, the interlocking means of the washer comprises at least one protrusion and the fitting of the electronic module comprises at least one indentation which corresponds to the protrusion of the washer so as to provide an interlocking mechanism between the washer and the fitting of the electronic module. Alternatively, the interlocking means of the washer may include at least one indentation and the fitting of the electronic module may include at least one protrusion corresponding to the indentation of the washer to provide an interlocking mechanism between the washer and the fitting of the electronic module.

The washer may include a protruding fitting, which may for example be substantially cylindrical and have a diameter that is less than the diameter of the washer. The cylindrical protruding fitting is positioned in a substantially cylindrical opening of the fitting. The protrusions may extend radially from the protruding fitting and be engageable with an indentation in the wall of the opening of the fitting so as to interlock the protrusion with the indentation and detachable attach the washer to the fitting.

In some embodiments, the interlocking action may be a rotational action about the longitudinal axis of the cylindrical protruding fitting and opening. The action may be a bayonet type action. The interlocking mechanism may provide a detachable connection that restricts relative rotational movement between the washer and the electronic module.

In one embodiment, the interlocking means comprises two protrusions that extend radially from the washer, each protrusion interlocking with a corresponding indentation of the fitting to restrict rotational movement of the washer with respect to the electronic module. For example, the washer may include a cylindrical protruding fitting from which two protrusions may extend radially on opposing sides of the cylindrical protruding fitting. However, the number of protrusions as that extend radially from washer is not limited to two and one protrusion or more than two protrusions, for example three or four protrusions may be provided. The protrusions may be distributed uniformly around the circumference of the washer or protruding fitting, if provided.

In some embodiments, the protrusions have the form of a latch or wing that extends radially outwardly from a longitudinal axis of the washer. The protrusions may extend substantially perpendicularly or at an inclined angle to the longitudinal axis.

In some embodiments, the protrusions have the form of a rib having a long direction that extends parallel to the longitudinal axis, a height that extends radially from a longitudinal axis of the washer and a width that extends along the circumference of the protruding fitting.

Typically, the valve stem is attached to the wheel rim using a nut which is placed over the outer surface of the valve stem and which is tightened against the outer surface of the wheel rim. In some embodiments, the valve stem comprises an outer surface that is sized and shaped so as to provide an integral nut. This embodiment has the advantage that the number of components of the system is reduced, thus further simplifying the assembly of the system onto the wheel rim.

The seal is a rubber seal, for example an O-ring. and is clamped between a flat end surface of the valve stem and a flat outer surface of the wheel rim in the mounted condition. This embodiment has the advantage that a groove for accommodating the seal is not required in the outer surface of the wheel rim or the end face of the valve stem. This arrangement further simplifies the construction of the tyre parameter monitoring system and assembly of the tyre parameter monitoring system to the wheel rim.

In some embodiments, a seal is provided that is positioned on an inner surface of the wheel rim. The seal may be at least partially positioned within an indentation of the washer, the indentation being positioned at the opposing side of the washer from the interlocking means.

In some embodiments, a seal is provided on each side of the wheel rim so that a first seal, for example a rubber O ring, is positioned between the valve stem and the outer surface of the wheel rim and a second seal is positioned between the washer and the inner surface of the wheel rim.

In the present invention, the fitting of the electronic module comprises an adapter which protrudes outwardly from the electronic module through the washer and is connected with the valve stem. The valve stem is spaced apart from the electronic module by the adapter and is coupled with the electronic module by means of the adapter, for example by means of a threaded connection between the valve stem and the adapter.

The electronic module may include one or more sensor units or sense circuits for monitoring a parameter of the tyre that are positioned within a housing of the electronic module. In one particular embodiment, the electronic module accommodates a tyre pressure sensor unit.

A method for mounting a tyre parameter monitoring system to a wheel rim is defined in claim <NUM>.

The method comprises positioning an electronic module which comprises a fitting on an inner surface of wheel rim, detachably attaching a washer comprising interlocking means with the fitting, the washer being positioned on the inner surface of the wheel rim, positioning a seal on an outer surface of the wheel rim; positioning a valve stem on the outer surface of the wheel rim such that the seal is positioned between the valve stem and the outer surface of the wheel rim and attaching the valve stem to the outer surface of the wheel by tightening the valve stem against the outer surface of the wheel rim using a nut and securing the seal between the valve stem and the outer surface of the wheel rim, wherein the valve stem comprises an outer surface that is sized and shaped to provide an integral nut. In an embodiment of the method which does not form part of the presently claimed invention, the valve stem is inserting into a hole of the wheel rim and into the washer, and the valve stem tightened against the outer surface of the wheel rim using the integral nut to connect the valve stem with the electronic module. In the present invention, the fitting of the electronic module comprises an adapter and the adapter is inserted through the washer and the hole in the wheel rim and the adapter is connected to the valve stem by a thread to connect the valve stem with the electronic module, and the valve stem is tightened against the outer surface of the wheel rim using the integral nut.

In some embodiments, the interlocking means of the washer comprises one or more protrusions which are connected to one or more corresponding indentations of the fitting to detachably attach the washer to the fitting of the electronic module. In an embodiment, the one or more protrusions extend radially from the washer and are engaged with a corresponding indentation of the fitting by a rotational movement of the washer around its axis to detachably attach the washer to the fitting of the electronic module by a mechanical interlocking action.

In another embodiment, the interlocking means of the washer comprise one or more indentations which are connected to one or more corresponding protrusions of the fitting to detachably attach the washer to the fitting of the electronic module. The indentations may extend in a radial direction such that the washer can be detachably attached to the fitting of the electronic module by a rotational movement of the washer about the longitudinal axis of the washer so as to mechanically engage the indentations of the washer with the protrusion of the fitting.

In some embodiments, one or more seals are provided. The method includes positioning a seal on the outer surface of the wheel rim such that the seal is positioned between the valve stem and the outer surface of the wheel rim and attaching the valve stem to the outer surface of the wheel rim by tightening the valve stem against the outer surface of the wheel rim using a nut and securing the seal between the valve stem and the outer surface.

The method may also include positioning a seal on the inner surface of the wheel rim such that the seal is positioned between the washer and the inner surface of the wheel rim and attaching the washer to the inner surface of the wheel rim by tightening the valve stem against the outer surface of the wheel rim using a nut and securing the seal between the washer and the inner surface.

The valve stem includes an integral nut. The integral nut is provided by the outer surface of the nut that is sized and shaped to provide an integral nut.

In the present invention, the fitting of the electronic module comprises an adapter. The adapter is inserted through the washer and the hole in the wheel rim from the inner surface of the wheel rim. The adapter is connected to the valve stem by a threaded connection to connect the valve stem with the electronic module. The valve stem is tightened against the outer surface of the wheel rim using the integral nut. The valve stem is spaced apart from the electronic module by the adapter in this embodiment. In some embodiments, a seal such as an O-ring is positioned between the valve stem and the adapter.

Embodiments will now be described with reference to the drawings.

<FIG> illustrates a cross-sectional view, <FIG> an exploded perspective view and <FIG> a perspective view of a tyre parameter monitoring system <NUM> according to a first example not forming part of the invention.

The tyre parameter monitoring system <NUM> includes an electronic module <NUM> including a fitting <NUM>, a valve stem <NUM> that is connectable with the electronic module <NUM> and a washer <NUM>. The washer <NUM> includes interlocking means <NUM> with which the washer <NUM> is detachably attachable to the fitting <NUM> of the electronic module <NUM>. The interlocking means <NUM> of the washer <NUM> is positioned within the fitting <NUM> of the electronic module <NUM> and is mechanically engaged with the fitting <NUM> so as to assemble the washer <NUM> and the electronic module <NUM>. The interlocking means can also be disengaged to as to disassemble the washer <NUM> from the electronic module <NUM>.

In the first example, the interlocking means <NUM> comprise two protrusions <NUM> which extend radially from the washer <NUM>. The protrusions <NUM> may extends perpendicularly outwardly from a longitudinal axis <NUM> of the washer <NUM> and form wings or latches. However, the protrusions <NUM> may also extend at an inclined angle to the longitudinal axis <NUM>. The two protrusions <NUM> are positioned uniformly around longitudinal axis <NUM> of the washer <NUM>. In this example, the protrusions <NUM> are integral with an overmoulding <NUM> of the washer <NUM>. The overmoulding <NUM> provides a protruding fitting <NUM> that is substantially cylindrical and that has an outer diameter which is smaller than the outer diameter of the washer body. The protrusions <NUM> each extend radially from the outer surface of the cylindrical protruding fitting <NUM> to form a wing or latch in the first example.

However, the number of protrusions <NUM> is not limited to two. For example one or more than two, for example three or four protrusions may be provided. The protrusion s14 may also extend radially outwardly at an inclines angle to the longitudinal axis <NUM>.

The fitting <NUM> of the electronic module <NUM> includes two indentations, which cannot be seen in the drawings, each corresponding to one of the protrusions <NUM> of washer <NUM> such that the protrusions <NUM> can be inserted into the indentations and interlocked with the indentations and the fitting <NUM> by means of a rotational movement around the axis <NUM> in the direction of the arrows <NUM> to assemble and disassemble the washer <NUM> and the electronic module <NUM>.

The tyre parameter monitoring system <NUM> further includes a seal <NUM> and a rubber seal <NUM>. As is illustrated in the cross-sectional view of the tyre parameter monitoring system <NUM>, when mounted on a wheel rim <NUM>, the seal <NUM>, the washer <NUM> and the electronic module <NUM> are positioned adjacent the inner surface <NUM> of the wheel rim <NUM> and, therefore, within the tyre which is attached the wheel rim <NUM>. The seal <NUM> is positioned at least partially within an indentation <NUM> of the washer <NUM>. The indentation <NUM> is positioned in the opposing face of the washer <NUM> from the protruding fitting <NUM>. The seal <NUM> has a ring-shaped form with an inner diameter that is selected so as to be able to support the outer diameter of the valve stem <NUM>.

The rubber seal <NUM> and the valve stem <NUM> are positioned adjacent the outer surface <NUM> of the wheel rim <NUM> and outside of the tyre. In this example, the end face <NUM> of the valve stem <NUM> has a flat surface and the outer surface <NUM> of the wheel rim also has flat surface. The rubber seal <NUM> is clamped between the two flat surfaces <NUM>, <NUM>. The valve stem <NUM> includes a thread on its outer surface with which the valve stem <NUM> is connected to the fitting <NUM> of the electronic module <NUM>.

In the example illustrated with reference to <FIG>, the valve stem <NUM> includes an outer surface <NUM> which is sized and shaped so as to provide an integral nut <NUM> with which the valve stem <NUM> can be tightened against the outer surface <NUM> of the wheel rim <NUM>. The section of the outer surface <NUM> providing the integral nut <NUM> may have a hexagonal shape or one or more flat surfaces to assist gripping of the outer surface <NUM> and other sections of the valve stem <NUM> may have a different size and/or shape, for example be cylindrical. In the assembled condition illustrated in <FIG>, the valve stem <NUM> extends through the rubber seal <NUM>, through a hole <NUM> in the wheel rim <NUM>, through the seal <NUM> and washer <NUM> so as to be connected to the electronic module <NUM>.

The valve stem <NUM> also includes a cap <NUM> which covers a pin <NUM> positioned within the valve stem <NUM> to form the inflation valve. The pin <NUM> is movable along the longitudinal axis <NUM> of the valve stem <NUM> so as to open the valve in order to introduce air into, or remove air from, the tyre.

<FIG> illustrates an exploded view and <FIG> a perspective view of a tyre parameter monitoring system <NUM>' according to a second example not forming part of the invention. The tyre parameter monitoring system <NUM>' of the second example also includes an electronic module <NUM> comprising a fitting <NUM>, a valve stem <NUM> which is connectable with electronic module <NUM> and a washer <NUM> including interlocking means <NUM> with which the washer <NUM> is detachably attachable to the fitting <NUM> of the electronic module <NUM>. In the second example, the interlocking means <NUM> of the washer <NUM> is provided by four protrusions <NUM> which extend radially from the washer <NUM> and which are uniformly distributed about the axis <NUM>.

In this example, the protrusions <NUM> have the form of ribs <NUM> which are positioned on and may be integrally formed from the outer surface of the cylindrical protruding fitting <NUM> of the washer <NUM>. Each rib <NUM> has a long direction that is substantially parallel to the longitudinal axis <NUM>, a height that extends substantially perpendicularly from the longitudinal axis <NUM> and a width that extends around the circumference of the cylindrical protruding fitting <NUM>.

The fitting <NUM> of the electronic module <NUM> includes four indentations not seen in <FIG>, one for each of the protrusions <NUM> so as to allow the washer <NUM> to be interlocked with the fitting <NUM> by a rotational movement of the washer <NUM> and protrusions <NUM> about the axis <NUM> as indicated by the arrow <NUM> in <FIG>. The washer <NUM> can be assembled to and disassembled from the electronic module <NUM> by means of this rotational action.

<FIG> illustrates a tyre pressure monitoring system <NUM>" according to a third example not forming part of the invention. The tyre parameter monitoring system <NUM>" of the third example differs in the form of the interlocking means <NUM> of the washer <NUM>. In the example illustrated in <FIG>, the interlocking means <NUM> include at least one indentation <NUM> positioned in the outer surface of the washer <NUM>. In this particular example, four indentations <NUM> are provided which are uniformly spaced about the axis <NUM> and which are positioned in an outer surface of the washer <NUM> so as to face radially outwards from the axis <NUM>. In this example, the washer <NUM> includes a substantially cylindrical protruding fitting <NUM> and the indentations <NUM> are positioned in the outer surface of the substantially cylindrical protruding fitting <NUM>.

The fitting <NUM> of the electronic module <NUM> has a substantially cylindrical opening (not shown) and includes four protrusions that extend from the wall of the opening, each protrusion sized, shaped and positioned to correspond to one of the indentations <NUM> so as to provide a mechanical interlocking between the indentation <NUM> of the washer <NUM> and the protrusion of the fitting <NUM> of the electronic module <NUM> so as to allow the washer <NUM> to be detachably attached to the electronic module <NUM>.

In some examples, the interlocking action may be a rotational action about the axis <NUM> as indicated by the arrow <NUM>. However, in a non-illustrated embodiment, an axial snapping action resulting interlocking between the indentations <NUM> and protrusions of the electronic module <NUM> may also be provided.

<FIG> illustrates a tyre parameter monitoring system <NUM>‴ according to the invention.

In this embodiment, the tyre parameter monitoring system <NUM>‴ includes an adapter <NUM> which is attached to the fitting <NUM> of the electronic module <NUM>. The adapter <NUM> protrudes from the fitting <NUM>. In this embodiment, the washer <NUM> includes an interlocking means <NUM> which is provided by the form of the outer surface of the washer <NUM> which interlocks with the fitting <NUM>. In this embodiment, the washer <NUM> includes a protruding fitting <NUM> that is substantially cylindrical and has at least one flat face that is engageable with a corresponding flat face of a substantially cylindrical opening of the fitting <NUM> of the electronic module <NUM>. The washer <NUM> includes an indentation <NUM> in its end face that opposes the protruding fitting <NUM> that accommodates the seal <NUM>.

In this embodiment, the adapter <NUM> protrudes through the washer <NUM>, through the seal <NUM> and through the wheel rim. The adapter <NUM> is connected to the valve stem <NUM> by a threaded connection. The adapter <NUM> may include an external thread which engages with an internal thread of the valve stem <NUM>. A seal such as an O-ring may be positioned between the adapter <NUM> and the valve stem <NUM>.

In this embodiment, the valve stem <NUM> is spaced apart from the electronic module <NUM> whereas in the embodiments illustrated in <FIG>, the valve stem extends into the electronic module <NUM>. The outer surface <NUM> of the valve stem <NUM> of the tyre parameter monitoring system <NUM>‴ of the fourth embodiment may also include an integral nut <NUM> as in the embodiments illustrated in <FIG>.

Claim 1:
A tyre parameter monitoring system (<NUM>‴), comprising:
an electronic module (<NUM>) comprising a fitting (<NUM>);
a valve stem (<NUM>) that is connectable with the electronic module (<NUM>);
a washer (<NUM>);
a rubber seal (<NUM>),
wherein the washer (<NUM>) comprises interlocking means (<NUM>) with which the washer (<NUM>) is detachably attachable to the fitting (<NUM>) of the electronic module (<NUM>),
wherein the rubber seal (<NUM>) is adapted to be clamped between a flat surface (<NUM>) of the valve stem (<NUM>) and a flat outer surface (<NUM>) of a wheel rim (<NUM>) in the mounted condition,
wherein the washer (<NUM>) and the rubber seal (<NUM>) provide an airtight connection between the valve stem (<NUM>) and the electronic module (<NUM>) and
characterised in that the fitting (<NUM>) comprises an adapter (<NUM>) which protrudes through the washer (<NUM>) and is connected with the valve stem (<NUM>) and the valve stem (<NUM>) is spaced apart from the electronic module (<NUM>) and is coupled with the electronic module (<NUM>) by means of the adapter (<NUM>) and the washer (<NUM>).