Patent Description:
In general, parking brake modules for motor vehicles comprise at least one actuator, typically of the linear type and equipped with a rod, with related kinematic mechanism, capable of placing the gearbox in the 'parking' position and then unlocking it.

The parking configuration must comply with the safety requirements of the vehicle, in particular, it must comply with the on-board diagnostics (OBD) of the vehicle; in other words, the electronics of the vehicle must always be capable of detecting possible malfunctions of the parking function.

The solutions of the prior art involve indirect measurement or estimation of the parking module configuration; in other words, the known solutions involve the use of sensors on the operating kinematic mechanism of the linear actuator, e.g., on a toothed wheel or pinion of such a kinematic mechanism. The on-board electronics can thus only estimate the position of the actuator and detect a possible anomaly by checking the angular position of the kinematic mechanism.

However, this type of indirect check is not entirely reliable and could, in some situations, lead to incorrect or untimely reports of possible malfunctions, for example if the failure occurs downstream of the kinematic mechanism monitored by the sensor.

Moreover, the solutions of the prior art are often mechanically complex and thus result in relatively high production costs.

In brief, the solutions of the prior art are expensive and not always reliable since they do not comply with the on-board diagnostics of the vehicle (OBD-compliant). Solutions according to the preamble of claim <NUM> are disclosed by <CIT>.

The need is therefore felt to solve the drawbacks and limitations mentioned above with reference to the prior art.

Such a need is met by an actuator according to claim <NUM>.

Further features and advantages of the present invention will be more comprehensible from the following description of preferred embodiments thereof, given by way of non-limiting examples, in which:.

Elements or parts of elements common to the embodiments described below will be indicated by the same reference numerals.

With reference to the aforementioned figures, reference numeral <NUM> indicates, as a whole, an actuator for applications on parking brake module on vehicles, according to the present invention.

The actuator <NUM> comprises a body <NUM> containing at least partially a control rod <NUM> operatively connected to motor means <NUM> and to an actuating device <NUM> of a parking brake (not shown).

Preferably, but not exclusively, the actuating device <NUM> is operatively connected to a parking brake of a motor vehicle. However, the aforesaid application is indicative and not exhaustive for the purposes of the present invention.

The body <NUM> delimits a containment volume <NUM> closed by a lid <NUM>. For the purposes of the present invention, the body <NUM> and the lid <NUM> can have any shape and size; moreover, they can be made of several materials, including metal and plastic materials and combinations thereof.

Said motor means <NUM> are configured to move the control rod <NUM> along an operating stroke <NUM> at least from a first position A to a second position B (<FIG>). The motor means <NUM> are preferably electric motors, e.g., DC electric motors.

It is worth noting that, for the purposes of the present invention, the operating stroke <NUM> is not necessarily linear, but can also be curvilinear, can include a broken line, or even an alternation of curvilinear and straight segments.

For example, the control rod <NUM> is operatively connected to the motor means <NUM> by means of kinematic mechanisms which can comprise screw-nut screw type couplings, gears, idlers, and so on.

Typically, said control rod <NUM> is provided with translational or roto-translational movement, the latter obtainable by means of a screw-nut screw type connection, for example.

The actuator <NUM> comprises an antenna <NUM> directly and integrally associated with the control rod <NUM>, said antenna being arranged inside the body <NUM>, i.e., inside the containing volume <NUM>. The antenna <NUM> can thus provide information on the position, i.e., on the operating condition, directly of the control rod <NUM>, not of a component of the kinematic mechanism or the motor means <NUM> themselves configured to move the control rod <NUM>. In other words, it is possible to obtain a direct feedback on the position and thus on the operating condition of the control rod <NUM> which interfaces with the actuating device <NUM>: this feedback unequivocally provides the operating condition of the actuating device <NUM> located downstream of the actuation chain which starts from the motor means <NUM>.

Therefore, it is possible to obtain an absolutely reliable feedback on the operating condition of the actuating device <NUM> but not of an intermediate kinematic mechanism as in the solutions of the prior art. Therefore, it is apparent that the feedback obtainable from this configuration is essential for the operation diagnostics of the apparatus arranged downstream of the actuating device <NUM>.

The actuator <NUM> further comprises a position sensor <NUM> arranged, for example, on a printed circuit or PCB holder <NUM>, housed inside the body <NUM>, i.e., in said containment compartment <NUM>, and facing the control rod <NUM> and the antenna <NUM>. The position sensor <NUM> is of the active type and is powered by power supply means (not shown), typically DC power supply means.

The position sensor <NUM> is configured to detect the presence and position of said antenna <NUM>, which, as seen, is associated directly and integrally with the control rod <NUM>.

According to a possible embodiment, the sensor position <NUM> is arranged on the PCB support <NUM>, e.g., parallel to said control rod <NUM>.

Said position sensor <NUM> is sized and positioned so as to cover and detect the position of the antenna <NUM> along said operating stroke <NUM>, as shown in <FIG>, for example, showing the antenna <NUM> in the first stroke-end position A and in the second stroke-end position B, respectively.

Preferably, the antenna <NUM> is arranged inside the body <NUM>, i.e., inside the containment volume <NUM>, between the motor means <NUM> and the position sensor <NUM>. The antenna <NUM> can thus always and immediately detect not only the position but also the very presence of the antenna <NUM> associated with the respective control rod <NUM>.

Therefore, the system is entirely reliable and is capable of immediately detecting any anomaly downstream of the kinematic mechanism, hence any anomaly which directly affects the actuating device <NUM> the operation and/or operating condition of which must be monitored.

Anomaly means both the detachment of the antenna <NUM> from the respective control rod <NUM>, which event would be immediately detected by position sensor <NUM> which would no longer sense the presence of the antenna <NUM> itself, and an abnormal position of the antenna and hence an unsuitable operating configuration of the actuating device <NUM>.

Preferably, the antenna <NUM> is fixed to an inner end <NUM> of the control rod <NUM>, contained inside the body <NUM>, i.e., in the containment volume <NUM>, said inner end <NUM> being opposite to and integral with an outer end <NUM> which interfaces with said actuating device <NUM>.

According to a possible embodiment, the antenna <NUM> is fixed on the control rod <NUM> by interference (press-fitting) and/or by gluing.

Preferably, the antenna <NUM> is keyed onto a portion of the control rod <NUM> provided with an external thread <NUM>; the thread thus allows adjusting the axial position of the antenna <NUM> with respect to the control rod <NUM> by simply screwing the antenna <NUM> onto the threaded portion.

The external thread <NUM> also forms an axial undercut, i.e., it fixes the axial position of the antenna <NUM> with respect to the control rod <NUM>. For this purpose, it is also possible to use special stops adapted to prevent a relative axial translation between the antenna <NUM> and the control rod, which would lead to an incorrect reading of the position or operating condition of the actuating device <NUM> by the position sensor <NUM>.

As mentioned above, the control rod <NUM> can have any geometric shape and any relative actuation movement.

Preferably, but not exclusively, the control rod <NUM> has a main extension axis X-X and is movable along an axial direction parallel to said main extension axis X-X.

According to a possible embodiment (<FIG>), said antenna <NUM> is axisymmetric with respect to said main extension axis X-X.

According to the invention, the antenna <NUM> is arranged coaxially to the control rod <NUM>. Coaxial arrangement means that at least one portion <NUM> for fixing the antenna <NUM> to the control rod <NUM> is coaxial with the control rod <NUM> itself.

Preferably, said antenna <NUM> is a ring, at least partially made of metal and coaxial with the control rod <NUM>. Preferably, the antenna <NUM> is a single ring, made in one piece, coaxially keyed onto the control rod <NUM>.

Preferably, said antenna <NUM> is a Grifax® ring directly associated with the control rod <NUM>.

Said ring, for example of the Grifax® type, preferably comprises a plurality of radial teeth <NUM> mutually separated by grooves <NUM>, preferably provided with end edges <NUM> in the shape of an arc of a circle; the radial teeth <NUM> thus interface with and are screwed onto the external thread <NUM> of the control rod <NUM>.

As seen, the ring can be axisymmetric with respect to the main extension axis X-X of the control rod <NUM> (<FIG>). In such an axisymmetric configuration, the angular orientation of the ring is irrelevant.

It is also possible to provide an asymmetric ring, as shown in <FIG>, for example, as the antenna <NUM>. In such embodiments, there is a precise angular orientation of the asymmetric ring with respect to the control rod <NUM>. Such an orientation is obtained, for example, by shape coupling between the control rod and the fixing portion <NUM> of the ring. For example, such a shape coupling comprises a flattening <NUM>, made on the control rod <NUM>, which couples to a flat abutment <NUM> obtained on the ring.

According to a possible embodiment, said antenna <NUM> comprises a cylindrical support <NUM> to which a metal portion <NUM> is folded and applied, e.g., by gluing, in the form of a metal foil. Said metal foil <NUM> can also be applied as a metal coating, obtainable in various manners, including by PVD and/or CVD. In general, the metal portion can have any shape and thickness and can be applied to the control rod by bonding, interlocking, undercutting, welding, CVD, PVD, and the like.

In general, said antenna <NUM> preferably has a cylindrical shape about said main extension axis X-X, with a radius R greater than a distance or gap G from the position sensor <NUM>.

The cylindrical shape is particularly useful when the operating stroke <NUM> of the control rod <NUM> and thus of the antenna <NUM> connected thereto is of the roto-translational type. Indeed, by virtue of the axial symmetry of the antenna <NUM>, the risk that the position sensor <NUM> can take unreliable readings based on the actual angle of rotation of the antenna <NUM> during the operating stroke <NUM> is thus averted.

Preferably, the antenna <NUM> has an axial thickness T, parallel to the main extension axis X-X, greater than or equal to the gap G from the position sensor <NUM>. Such a sizing always ensures the correct detection of the antenna <NUM> by the position sensor <NUM>.

As can be appreciated from the description above, the present invention allows overcoming the drawbacks presented in the prior art.

In particular, the linear actuator according to the present invention is particularly reliable since it directly measures the position of the end component which interfaces with the parking mechanism.

Therefore, there is no indirect estimation of the actuator configuration, as in the solutions of the prior art, but rather a direct measurement of the position of the final component of the kinematic mechanism which engages or disengages the parking function.

Moreover, any detachment of the antenna from the related control rod is immediately detected by the position sensor located adjacent to the antenna.

The actuator is also particularly simple and inexpensive to manufacture and assemble.

Indeed, the antenna can be made using a very simple metal 'Grifax' ring, which is cost-effective and readily available in the market.

The assembly step is also particularly easy and cost-effective, because the 'Grifax' ring, or cylindrical antenna in general, can be immediately keyed onto the control rod. The antenna is thus self-supporting because, by virtue of the geometric shape thereof, is automatically supported by the control rod; indeed, being fitted coaxially to the control rod, it forms a radial undercut with respect to the rod itself, which prevents it from detaching. In the case of breakage or detachment, as mentioned above, the antenna separates from the control rod, and its movement away from the control rod is immediately detected by the position sensor.

Therefore, the solution according to the present invention is perfectly 'OBD-compliant', unlike the solutions of the prior art.

Moreover, the use of a ring fitted and screwed directly onto the control rod also allows varying the axial position of the antenna with respect to the control rod and thus with respect to a different position of the position sensor. In other words, it is possible to vary the stroke-end positions by simply changing the axial position of the antenna with respect to the control rod, without requiring an ad hoc component to be manufactured.

Claim 1:
An actuator (<NUM>) comprising:
- a body (<NUM>) at least partially containing a control rod (<NUM>) operatively connected to motor means (<NUM>) and to an actuating device (<NUM>) of a parking brake, said motor means (<NUM>) being configured to move the control rod (<NUM>) along an operating stroke (<NUM>) at least from a first position (A) to a second position (B),
- an antenna (<NUM>) directly and integrally associated with the control rod (<NUM>), said antenna (<NUM>) being arranged inside the body (<NUM>),
- a position sensor (<NUM>) arranged on a printed circuit (<NUM>), housed inside the body (<NUM>) and facing the control rod (<NUM>) and the antenna (<NUM>), the position sensor (<NUM>) being configured to detect the presence and position of said antenna (<NUM>),
characterized in that said antenna (<NUM>) is arranged coaxially to the control rod (<NUM>).