Patent Description:
The present invention relates to an electric actuator apparatus provided with a position detection system and a road vehicle thereof comprising such an apparatus.

In particular, the present invention is advantageously, but not exclusively, embodied in one or more electric actuators for highly performing vehicles, to which the following description will make explicit reference without thereby losing its generality.

As well-known, in the field of vehicles (but also in general terms) the use of electric actuations is now widely widespread, both in terms of propulsion and comfort. In particular, all these actuators are usually governed by special control units, which operate by means of a control in position or in speed of the aforementioned actuators.

To carry out feedback controls, often necessary for safety reasons in relation to at least the electric motor of the propulsion system, angular position transducers are used, i.e., electromechanical devices that provide instant by instant the absolute or relative position of the rotor of the electric motor to be controlled, allowing de. Among these, digital devices are known, usually called encoders, which convert the angular position of a rotating axis (integral with the rotor of the electric motor to be controlled) into short electrical pulses that need to be processed by a signal analysis circuit in the form of digital numerical signals.

The document <CIT> describes an electric valve actuator comprising an electric motor and an optical angle encoder with optical sensor elements.

Furthermore, analogue devices are known, usually called resolver, in which they consist of an electromechanical device for the measurement of angular displacements allowing to detect the variation of magnetic induction flux, concatenated with a solenoid, as a function of the position of the solenoid itself (which is integral with the rotor of the electric motor to be controlled).

Of the aforementioned devices, over the years, several types have been developed.

In any case, encoders are usually used in applications requiring the prior search for a reference, in that they provide a relative position, that is, they encode the position (and its derivatives over time) of the motor rotor to be controlled in signals proportional to the displacement.

On the other hand, resolvers are able to provide a coding of the rotor position in absolute terms, but they usually have significant costs and dimensions, especially since they require at least the presence of a copper circuit (solenoid or track printed) concatenated with the variation of the magnetic induction flux of the machine (i.e., of the electric motor to be controlled) and of relative sensors.

Moreover, prior art devices are electromechanical and require careful and gentle assembly, usually by experienced personnel.

In addition, the prior art devices require dedicated circuitry at the transducer and within the road vehicle control unit.

In any case, both the above solutions, although functional, are susceptible to improvement according to the Applicant.

In general, the need is felt for further weight reduction, simplified assembly, and improved safety performance, as well as optimized cost management.

Finally, the devices of prior art are also expensive in terms of energy, especially in fully electric vehicles, in which the energy saving of non-propulsive components becomes increasingly relevant, so as to increase the vehicular autonomy.

An object of the present invention is to provide an electric actuator apparatus as defined in claim <NUM>, provided with a position detection system and a road vehicle thereof comprising such apparatus which are at least partially free from the drawbacks described above and, at the same time, are of simple and cheap realization.

According to the present invention, an electric actuator apparatus provided with a position detection system and a road vehicle thereof comprising such apparatus according to what is claimed in the following independent claims and, preferably, in any of the directly or indirectly dependent claims from the independent claims, are provided.

In the following, some embodiments of the invention will be described for a better understanding thereof by way of non-limiting example and with reference to the accompanying drawings in which:.

In <FIG> generally indicates, as a whole, a road vehicle provided with two front wheels <NUM> and two rear wheels <NUM>, of which at least one pair (or all) receive the driving torque from a motor propulsion system <NUM>. The motor propulsion system <NUM> can be exclusively thermal (i.e., it comprises only an internal combustion engine), hybrid (i.e., it comprises an internal combustion engine and at least one electric motor), or electric (i.e., it comprises only one or more electric motors).

Preferably, the road vehicle <NUM> is provided with a passenger compartment <NUM> which is adapted to accommodate at least one driver and preferably one or more passengers.

The same reference numbers and letters in the Figg. identify the same elements or components with the same function.

In the context of this description, the term "second" component does not imply the presence of a "first" component. These terms are in fact used as labels to improve clarity and are not to be understood in a limiting way.

The elements and features illustrated in the various preferred embodiments, including the drawings, can be combined or isolated from each other without however departing from the scope of protection of the present application as described below.

The road vehicle <NUM> comprises at least one electric actuator apparatus <NUM>, which is provided with an electric motor <NUM>.

The electric motor <NUM> comprises a stator <NUM> and a rotor <NUM>, which is configured to rotate about a rotation axis A according to the (electric) power transmitted by the stator in known and therefore not further detailed manner. In particular, the electric motor <NUM> can be any type of electric machine (e.g., brushless, permanent magnet, inductance, synchronous, asynchronous, etc.).

The road vehicle <NUM> comprises an electronic control unit ("ECU") <NUM> which, among other things, is configured to control the electric motor <NUM> in feedback (i.e., closed loop, by means of known control algorithms and therefore not further elaborated). Physically, the control unit <NUM> can be composed of a single device or of several devices separated from each other and communicating through the local network (can, Ethernet, etc.) of the road vehicle <NUM>.

To carry out the aforementioned feedback control, the apparatus <NUM> comprises a position detection system <NUM> configured to provide the control unit <NUM> with an angular position of the rotor <NUM> (and therefore of a motor shaft <NUM> connected thereto according to known techniques).

Advantageously, the apparatus <NUM> comprises a reading portion <NUM>, which is integral to the rotor <NUM> and provided with an encoded (non-perforated) surface <NUM> on which a plurality of codes <NUM> that can be associated with the angular position of the rotor <NUM> are fixed (in particular, printed).

The apparatus <NUM> further comprises a sensor, optical or laser element <NUM>, which is arranged integral to the stator <NUM> and so as to point toward the encoded surface <NUM>.

Advantageously but not in a limiting way, codes <NUM> extend radially to the rotor <NUM> and are separated from each other. In other words, codes <NUM> are rows arranged in rugged pattern.

Advantageously but not in a limiting way, codes <NUM> are not circular sectors.

Preferably but not in a limiting way, the codes <NUM> determine an absolute reference on the position of the rotor <NUM>; in particular, they are all different from each other.

Preferably, the encoded surface <NUM> is a seamless surface, i.e., without through holes. Thus, SPAD/CMOS chips can be used as described below. In addition, this avoids compromising the inertia of rotor <NUM> with holes that would alter its density.

The sensor element <NUM> is a photodetector <NUM> (i.e., a device capable of detecting an electromagnetic radiation, outputting a signal having a current intensity or a potential difference proportional to the intensity of the detected radiation).

According to the claimed invention, the sensor element <NUM> comprises one or more single-photon photodetector diodes <NUM> (known by the acronym SPAD). Preferably, the sensor element <NUM> is in the form of a SPAD/CMOS chip. By doing so, the sensor element <NUM> is able to read at extremely high speed the information contained in the encoded surface <NUM>, even in dark conditions within the apparatus <NUM>. This avoids adding weight to the road vehicle. In addition, this technology, nowadays unused in vehicular applications, would allow laser printing of encodings on the rotor without impacting its mechanical performance and ensuring sufficient durability of the encodings <NUM>.

In other non-limiting and non-illustrated cases, the sensor element <NUM> is a miniaturized camera, which is configured to sequentially detect images of the encoded surface <NUM>.

Advantageously but not in a limiting way, the encodings <NUM> are arranged radially, in particular equidistant from each other to the rotation axis A of the rotor <NUM>.

Preferably, the codes <NUM> are realized by laser printing.

According to some preferred non-limiting embodiments, the reading portion <NUM> is made of metal.

In particular, the reading portion <NUM> is made in one piece with the rotor <NUM> of the electric motor <NUM> or with the motor shaft <NUM>. More precisely, the reading portion is a pre-existing part of the rotor <NUM> or a pre-existing part of the shaft <NUM>. Thereby, assembly can be simplified as much as possible, which will be limited to fixing the sensor element <NUM> in the correct seat.

In some non-limiting cases, such as that illustrated in <FIG> and <FIG>, the reading portion <NUM> comprises (is) an end <NUM> of the shaft <NUM> integral with the rotor <NUM> of the electric motor <NUM>. Thereby, the mounting of the sensor element <NUM> would be simplified in that the end <NUM> comes out of the rotor <NUM> (i.e., from one of the bases of the cylindrical volume defined by the rotor <NUM>).

Alternatively, or in addition, as even more sensor elements <NUM> could in general be combined to increase the accuracy, the reading portion <NUM> comprises (is) a base disc <NUM> of the rotor <NUM> of the electric motor <NUM>. In so doing, the coded surface would be larger and allow for a greater number of rows <NUM>.

In some non-limiting cases, as in the embodiment of <FIG> and <FIG>, the encoded surface <NUM> is parallel to the axis A of rotation of the rotor <NUM>.

In other non-limiting cases, as in the embodiment of <FIG> and <FIG>, the encoded surface <NUM> is transverse, in particular perpendicular, to the rotation axis A of the rotor <NUM>.

Regardless of the orientation of the encoded surface <NUM>, the sensor member <NUM> is mounted so as to be viewed perpendicularly to the encoded surface <NUM>, so as to optimize reading of the encoding <NUM>.

According to some preferred non-limiting embodiments, each code <NUM> comprises a binary-coded line <NUM>. In particular, the term "binary" means any coding providing for two different conditions. For example, an encoding <NUM> would be binary in the case of peaks and valleys in row <NUM>, or if values of zero and one were printed, or different figures.

According to further non-limiting and non-illustrated embodiments, the coding <NUM> comprises a bar-coded or alphanumeric-coded line <NUM>.

Advantageously but not necessarily, and as visible from <FIG> and <FIG>, each coding line <NUM> corresponds to a specific angular position of the rotor <NUM> of the electric motor <NUM>.

In particular, the reading portion <NUM> has at least one line for each degree of a turn angle. In other words, the reading portion <NUM> comprises at least <NUM> rows, preferably at least <NUM> rows. Obviously, increasing the number of rows increases the resolution of the position detection system.

According to some preferred non-limiting embodiments, the actuator apparatus <NUM> is part of the propulsion system <NUM>. In other words, the electric motor <NUM> is configured to deliver driving torque to at least one or both of the front wheels <NUM> and/or to one or both of the rear wheels <NUM>.

Alternatively, or in addition, but not limited to, the actuator apparatus <NUM> is configured to operate an accessory device, which is not essential for the driving of the road vehicle <NUM>, for example windows, doors, seats, and any actuator controlled in feedback.

In particular, the actuator apparatus <NUM> may also be successfully used to actuate an active suspension, for example of the type described in Applicant's application <NUM>.

In use, the sensor element <NUM>, the control unit <NUM> processes, preferably in real time, the exact angular position of the rotor <NUM> by decoding the signals detected by the sensor element <NUM>, thus, for example, the photons perceived by the photodetector <NUM> of the SPAD type. Upon detection, the unit <NUM> is able to centrally control the mode of the electric motor <NUM> by implementing known control algorithms (e.g., PID, feedforward, etc.).

Although the invention described above makes particular reference to a very precise example of embodiment, it is not to be considered limited to this example of embodiment, as all those variants, modifications or simplifications covered by the attached claims fall within its scope, such as for example a different type of road vehicle (for example with hybrid traction), a different form of the coded surface, a different position of the lines, etc..

The actuator apparatus and vehicle described above have numerous advantages.

First of all, they allow to lighten the structure of the road vehicle, removing encoder/resolver and the circuitry connected to them, thus allowing to increase the performance at the same expressed power.

In addition, they allow to simplify the assembly of the actuator apparatus, since the angular position detection system is directly integrated into the engine and does not require special precautions on the part of experienced personnel.

A further advantage of the present invention lies in the fact that, thanks to the presence of specific coding lines for certain angular positions, the absolute position of the electric motor to be controlled is detected in a mechanically simpler and more reliable way. In this way, it is possible to avoid any error in reading the position when the road vehicle is switched on, ensuring that the vehicle always moves in accordance with the driver's wishes, thus protecting the safety of the driver himself, the vehicle, and any individuals around the vehicle.

Furthermore, the present invention allows to control in an economical, simple, and safe way any type of electric motor, vehicular and not.

Claim 1:
An electric actuator apparatus (<NUM>) comprising:
- an electric motor (<NUM>), comprising in turn a stator (<NUM>) and a rotor (<NUM>), which is configured to rotate about an axis (A) according to the power transmitted by the stator (<NUM>);
- a control unit (<NUM>) configured to control the electric motor (<NUM>) via a feedback control;
- a position detection system (<NUM>) configured to provide the control unit (<NUM>) with an angular position of the rotor (<NUM>);
the electric actuator apparatus (<NUM>) further comprising:
- a reading portion (<NUM>), which is integral to the rotor (<NUM>) and provided with an encoded surface (<NUM>) on which a plurality of codes (<NUM>) that can be associated with the angular position of the rotor (<NUM>) are fixed;
- an optical or laser sensor element (<NUM>), which is arranged integral to the stator (<NUM>) and so as to point toward the encoded surface (<NUM>), characterized in that
the sensor element (<NUM>) comprises one or more single-photon, SPAD photodetector (<NUM>) diodes.