WO2004109139A1

WO2004109139A1 - Clutch actuation system with a synchronised electrical generator

Info

Publication number: WO2004109139A1
Application number: PCT/PT2003/000008
Authority: WO
Inventors: José Manuel Braga Gomes ALBUQUERQUE
Original assignee: Albuquerque Jose Manuel Braga
Priority date: 2003-06-06
Filing date: 2003-06-06
Publication date: 2004-12-16
Also published as: WO2004109140A1; AU2003234374A1

Abstract

This invention describes an automated clutch actuation system, with short response time, based on the principles of rotary electric motor and generator machines, intended to be used in all motor vehicle’s in general. The required electromagnetic power for clutch actuation is provided by the invention itself, via a special electric generator (1, 2, 3), and only a small external electric (4) exciting current is required to control the whole system. The generator described by this invention is aimed to work at constant power “P” and constant torque “T”, regardless the highly variable “ωm” vehicle’s engine rotation speeds: P=T(ωm-ωe)=constant. The generator excitation field is created by external (4) AC three-phase current with variable frequency, creating “ωe”. The generator operation causes the central rotor (2) to have a small angular displacement, that is converted into linear displacement, by means of two large pitch screw threads (5, 6, 7) to actuate clutch spring.

Description

CLUTCH ACTUATION SYSTEM BY MEANS OF A SYNCHRONISED ELECTRICAL GENERATOR

DESCRIPTION

This invention describes a clutch actuation system. It relates to automated clutch actuation systems, based on the principles of the rotary electric motor and generator machines. It is intended to be used on small automobiles, heavy-trucks, racing and all motor vehicle's in general, specially whenever speed gear changes are to be fully automated via automatic clutch operation, with short time response. The aim of the present invention is to virtually eliminate the conventional vehicle's driver clutch pedal, in such a way that it can automatically perform the force, the displacement and the same function of a conventional clutch pedal. By means of the present invention, the vehicle's conventional clutch pedal, used to disconnect the engine rotation power from vehicle's transmission, is actuated by electromagnetic induction and fully controlled by means of the associated electricity.

^' The required power is provided by this invention itself, via an electric generator. According to this invention the mechanical power of vehicles engine is directly converted into electricity, by means of a generator (1, 2, 3), and only a small external electric (4) exciting power is required to control the whole system. In order to produce electricity this invention is based on alternating current (AC) three-phase synchronous generator operation. All the electricity produced by the generator (1, 2, 3) is short-circuited on heavy-loads (16, 17, 18) and wasted producing heat. According to this invention, only the electromagnetic torque created in the generator air-gap (3) is useful for the clutch actuation system.

According to the present invention, the AC synchronous generator is turned upside down. The part of the generator that usually rotates is stopped and the generator's usual static part is coupled with the engine main shaft (13) and permanently rotates. Therefore, according to this invention, the so-called stator (1) of a conventional generator is herein called the rotating stator (1). On the other hand, the rotating part of a conventional generator is herein described as the central rotor (2) and it will be regarded as being stopped. This invention fully describes an electromechanical system, invented to apply force onto the powerful spring (11) of a conventional clutch. Clutch spring (11) force depends on the vehicles engine torque and clutch design, but it is always a huge force. According to this invention, that force will be produced by the vehicle engine torque, wasting fuel at the moment the clutch spring (11) is actuated and whenever it stays actuated. The mechanical rotation of vehicles engine is converted onto a magnetic field that produces electromagnetic torque. That torque is then mechanically converted into linear force and displacement (15), in order to properly actuate the clutch spring (11).

According to this invention, the clutch spring (11) force is fully controlled by means of the induced electromagnetic fields, created within the generator air-gap (3). The linear spring displacement (15), required to actuate the clutch, is converted from angular displacement (14). That angular displacement (14) is the angular displacement of the central rotor (2) of the generator, upon a concentric system (5, 6, 7) that converts angular to linear displacement. That system is based on two large pitch screw threads (5, 6, 7).

The rotating stator (1) of the generator is permanently driven by vehicle's engine main shaft (13), which is the crankshaft in the case of combustion engines, like shown in Fig.2. The rotating stator (1) is herein defined as the part of the generator where the mechanical energy is converted and electricity is generated. The rotating stator (1) electric output is short- circuited (16, 17, 18). Therefore, the electricity produced by the generator is not usable. All the electricity generated must be totally dissipated on convenient loads (16, 17, 18), to produce heat. The most important roll of the generator itself concerns the magnetic forces induced by the energy conversion, within the air-gap (3), not the electricity it self. It is the electromagnetic developed torque that is used to actuate the clutch spring (11), not the electricity generated.

According to the present invention, the central rotor (2) of the generator is considered a stopped part. The central rotor (2) is concentric with clutch axis, face on to the clutch spring (11), as shown in Fig.2. The central rotor (2) is mounted upon two large pitch concentric screw threads (5, 6, 7). This screw system, shown in Fig.4, is intended to convert a small angular displacement (14) of the central rotor (2) onto an even smaller linear displacement (15) of the clutch spring (11). Two screw threads (5, 6, 7) are used in order to cut by half the displacement (15), hence doubling the force acting on the spring (11), due to mechanical energy conservation Law.

In order to turn on, and off, the generator, the central rotor (2) must be magnetised and demagnetised. According to the present invention, the central rotor (2) cannot be a permanent magnet and must be a coil type electromagnet (8), similar to those used in a conventional AC synchronous generator, but with some major differences. The central rotor (2) must have the triple of electromagnetic salient poles (8), coils (8), then a conventional generator does. The reason for the triple number of poles (8) is the fact that the generator excitation current must not be direct current (DC), but AC three-phase current (4). The AC three-phase current produces a very useful rotating electromagnetic excitation field, like if it was a motor excitation field. This is a very important feature of this invention, in order to cost-efficiently deal with vehicle's highly variable engine rotation speeds. This special rotating feature of the central rotor (2) will be explained later, on the detailed description.

When an external source (4) of electricity is supplied to the central rotor (2), an electromagnetic exciting field is created and the vehicle's engine mechanical rotation will induce a force between the central rotor (2) and the rotating stator (1), via the air-gap (3). That electromagnetic induced force causes a counter-electromagnetic torque into the central rotor (2). That counter-electromagnetic torque will then create a small angular displacement (14) of the central rotor (2), which will be used to actuate the clutch spring (11).

Due to its proven great efficiency, this invention uses all the basic principles of the AC three-phase synchronous generators and motors. Nevertheless, because the whole system is an isolated system, it is always possible to use less efficient mono-phase circuits, or even more expensive and complicated four-phase, five-phase or n-phase circuits. Special type of generators can be used, regarding they have the basic working mechanism explained on this patent, without being innovative.

Due to the fact that the induced electromagnetic torque changes with the engine/generator mechanical rotation speed, and because we need to have a controllable force upon the clutch spring (11), an external electronic auxiliary system is need to accurately control the required power of the generator. That electronic auxiliary system is wire (4) connected to the central rotor (2) and must produce a variable rotating excitation magnetic field. At the same time, it must control the central rotor (2) magnetic field strength, by means of applying more or less electric tension and current. With a rotating magnetic field excitation, conveniently adjusted to the vehicle's engine rotation, the strength and the frequency of the induced magnetic field can be accurately controlled to match the needed clutch spring (11) force, at any driving situation.

Like is the case of conventional AC synchronous generators, the external electrical (4) energy, required to control the magnetic excitation field strength of the central rotor (2), will be a very small part of the total energy required to actuate the clutch spring (11). The most of the energy required to produce the working magnetic field is supplied by the short- circuited rotating stator (1) and, therefore, mainly supplied by the vehicle's engine mechanical energy, via the engine's output shaft (13), by mechanical energy conversion.

When the generator is turned off, by means of no current supplied to the central rotor (2), the position recover of all the clutch actuation system is based on the clutch spring (11) elastic energy. Nevertheless, the electronic system can also control the recovery time.

By means of present invention, manual speed gear systems can be converted into automated transmission systems. For instance, actuated by a push button onto drivers steer wheel. By a programmable logic control (PLC), etc.

Due to its basic working mechanism, this invention has a major problem. Whenever the vehicle's engine stops the clutch actuation system cannot work, because it missies mechanical power. Without vehicle's engine mechanical power the basic mechanism of this invention doesn't work. Therefore, in complement to the basic working mechanism herein described, an auxiliary system is needed. This patent of invention also provide solutions for those occasional situations, when the vehicles engine is stopped and the clutch system must be actuated by means of an auxiliary system. DETAILED DESCRIPTION OF THE INVENTION

The great majority of vehicles clutch actuation system, produced World-wide, they work by means of compressing and releasing a spring (11). That spring, usually a diaphragm spring (11), is actuated by an axial force applied around the axis of the clutch disk, by means of an axial bearing (26) as shown in Fig.1-2. It is known that the force, any clutch actuation system must produce, is about 800 N (80 kg) for the smallest automobiles, about 1500 N (150 kg) for normal passenger cars, 2500 N (250 kg) for high performance vehicles and about 4000 N (400 kg) for heavy-trucks, or even more.

The present invention concerns an innovative way to produce huge forces, required to actuate vehicles engine clutches produced World-wide. According to the present invention, that force is directly supplied by vehicle's engine mechanical rotation power, which translates into vehicle's engine torque and mechanical angular velocity, with instantaneous fuel consumption, whenever the clutch system is actuated. The mechanical torque produced by vehicles engine is directly converted into an electromagnetic induced torque, by means of an electrical generator. According to this invention all the power is supplied by vehicles engine, in real time. Therefore, in normal conditions, the vehicle's engine must be running. Otherwise, if vehicle's engine rotation fall's and stops, the basic principle of this invention cannot work, because there is no generation phenomenon.

The electricity produced by the generator (1, 2, 3) is to be wasted on heavy-loads electrical impedance (16, 17, 18), producing heat. Only the electromagnetic torque, induced in the generator air-gap (3), is useful for the clutch actuation mechanism. The electrical generator herein described, like all rotary electrical generators, is used to convert mechanical energy into electricity, according to the Faraday's and Lenz's Physical Laws. These Laws are the Laws that describe the electromagnetic induction and the basic working mechanism of all rotating electrical motors and all rotating electrical generators.

This invention comprises two major systems, being one mechanical and another electromagnetic. Fig.1-4 shows and describes the mechanical system. The mechanical system is basically composed by a set of two large pitch screw threads (5, 6, 7), used to convert angular displacement (14) into linear displacement (15). Fig.5-9 shows and describes the working mechanism and the basic wire connection of this special type of generator, presented by this invention.

Fig. l shows the basic elements of this invention and Fig.l is fully integrated into Fig.2.

Fig.2 shows a more complete description of the innovative clutch actuation system, integrated into the conventional clutch housing, where it is aimed to be placed, substituting the existing conventional system.

Fig.3 shows another view of Fig.l. In general, all Figures herein presented (Fig.1-9) describe one and the same machine, nevertheless highlighting different aspects in order to help on the description. All Figures Fig.1-9 presented in this patent of invention are based on conventional AC three-phase synchronous generator, with two conceptual permanent pairs of magnetic poles build on the central rotor (2).

Shown in Fig.1-3, Fig.5 and Fig.8-9, the rotating stator (1) is a laminated iron piece, wire wound, composed by several coils (9), or electromagnets (9). The rotating stator (1) is permanently coupled to vehicle's engine main shaft (13), via the engine fly-wheel (24) and the clutch disk housing (25). Therefore, the rotating stator (1) is always rotating, whenever vehicle's engine is running. Shown in Fig.1-3 and Fig.5-7, the central rotor (2) also is a laminated iron piece, wire wound, composed by several electromagnets (8). Between the rotating stator (1) and the central rotor (2) there is an air-gap (3), where the energy conversion takes place. These above three parts are the so called generator (1, 2, 3).

According to this invention the central rotor (2) is assumed to be stopped, but in fact it does have some angular displacement (14) that, in general, must be a fraction of one complete revolution. Central rotor (2) angular displacement (14) will be something between 90 degrees and 360 degrees or so, back and forward, depending on the particular design. More angular displacement (14) will result in a poorer time response of the clutch actuation system, but it will benefits in much less power rated, that could be very useful when very high clutch actuation forces are required. When the central rotor (2) is energised the generator is turned on. Then the rotating stator (1) will create a counter-electromagnetic torque against the central rotor (2), via the small air-gap (3) between them. The counter-electromagnetic torque causes the central rotor (2) to rotate in the same direction of the rotating stator (1) and, if bigger enough to surpass the clutch spring (11) force, it will cause the central rotor to accelerate and have the predefined angular displacement (14). That predefined angular displacement (14) is aimed to actuate the mechanical system of the clutch, producing force and compressing the clutch spring (11).

The mechanical system is composed by a set of two large pitch screw threads (5, 6, 7), or double screw threads (5, 6, 7), used to convert rotation into linear displacement (15).

Fig.4 shows a perspective of the two large pitch screw threads (5, 6, 7). Basically it is composed by three parts, being one the innermost part (5), that will be the fulcrum, normally attached to the gearbox housing. That fulcrum (5) comprises the first large screw thread, drawn in its exterior diameter, and it could be left, or right handed, depending on vehicle's engine sense of rotation. The outermost part (7) is rigidly attached to the central rotor (2), by means of thermal expansion or any other means. That outermost part (7) comprises the second large screw thread, drawn in its interior diameter. This outermost part (7) is the one that will receive the torque and the angular displacement (14) from the central rotor (2), when the generator (1, 2, 3) is energised.

The double screw thread central part (6), of the double large pitch screw thread system, is positioned between the two above mentioned ones. Therefore, both counterparts of the two large screw threads must be drawn in both sides of this central part (6), exterior and interior diameter, respectively. It will be this double screw central part (6) that will perform the linear displacement (15) in order to actuate the clutch spring (11) and, therefore, it must have a conventional axial bearing (26) assembled on the side facing the clutch spring (11), as shown in Fig.1 and Fig.2. According to this invention, the two large screw threads drawn in the central part (6) must be opposite, which means that when one is a left screw thread the other must be a right screw thread, and vice-versa, depending on vehicle's engine sense of rotation.

Fig.1-4 assumes that vehicle's engine rotates clockwise, when seen from fly-wheel (24) side. Therefore, the screw thread drawn in the fulcrum (5) must be right handed, as shown in Fig.4, because the outermost part (7), attached to the central rotor (2), will rotate clockwise when the generator is energised. Because both screw threads must be opposite, as stated previously, the screw thread drawn in the outermost part (7) must be left handed, as shown in Fig.4.

When the generator is turned on, the central rotor (2) will accelerate and will trend to follow the rotating stator (1), producing the desired angular displacement (14), up to the point where it must be stopped, by means of any kind of limit device, not shown. That limit device could be positioned in the housing, or it could be provided by the clutch course limit itself. When the angular displacement (14) occurs, the central rotor (2) and the outermost part (7) of the double screw thread system will exerts a force to the right, as seen in Fig. l and Fig.2, against the fulcrum housing, by means of the axial bearing (23).

At the same time, the central rotor (2) attached to the outermost part (7) they will exert an equal force, with opposite direction, onto the double screw central part (6) of the thread system, against the clutch spring (11). Therefore, according to Fig.1-2 and Fig.4, when the central rotor (2) has an angular displacement (14) clockwise, the double screw central part (6) of the double screw thread system will be linearly displaced (15) to the left, in order to compress and actuate the clutch spring (11). When the generator is turned off, the clutch spring (11) elastic energy will provide the position recover of all the actuation system.

In order to convert angular (14) to linear displacement (15), two screw threads will work better then only one screw thread, because two screw threads allows that the central rotor (2) doesn't have to be displaced linearly. Independently of screw threads pitch angle, only the double screw central part (6) suffers linear displacement (15) and, therefore, the central rotor (2) will be permanently aligned with the rotating stator (1), which is very important for generator correct work. Because there always be a reaction force against any displacement, the reaction force against clutch spring (11) must be sustained by an axial bearing (23), positioned between the fulcrum (5) and the outmost part (7), as shown in Fig. l and Fig.2. Another important benefit of the double screw threads system (5, 6, 7) is that, if both threads have equal pitch, it cut by half the displacement (15). Hence, it doubles the force acting on the spring (11), due to mechanical energy conservation Law.

For instance, it the clutch actuation system must produce a linear displacement (15) of about 0,015 metre, onto the clutch spring (11), and if the angular displacement (14) of the central rotor (2) is defined to be about 150 degrees, assuming equal pitch threads for both screw threads and a medium diameter of 0,05 metres for the double screw central part (6), then the pitch angle thread of each screw threads must be of about 25 degrees. If only one screw thread is used, instead of the double screw thread system shown in Fig.4, then the pitch angle of the single screw thread system must be about 13 degrees. Therefore, when the generator is turned off, the larger angle of 25 degrees will have faster recovery response, based on clutch spring (11) elastic energy recover, then a smaller pitch angle has. Double screw thread system improves recovery time response.

According to the present invention, the electrical generator design is based on class AC three-phase synchronous generators, used in power plants World- wide, to supply National grids at the synchronous frequency of 50 Hz, in Europe, and 60 Hz in the U.S.A. Those conventional generators are based on a low consumption DC magnetic excitation field, which, by means of mechanical rotation, induces a magnetic field onto a set of adjacent coils, separated by the air-gap, and placed on the stator of the machine, where electricity is generated, by means of the Physical conversion of mechanical energy into electric energy. The stator of those conventional generators have a three-phase winding set of coils, wire wound around a laminated ferromagnetic material. The stator is the static part of a conventional generator and that's the part of the machine where the electricity is generated, at high voltage and high current intensity. The rotor of conventional generators is the rotating part of the machine, directly coupled to the driving engine, which provides the needed mechanical power to be Physically converted into high-tension electricity. In its basic design, the rotor of conventional generators can have one, up to several, pairs of magnetic poles. A pair of magnetic poles means one pole North and one pole South, both displaced 180 degrees electrically. Depending on the number of pairs of poles, build in the rotor of the generator, the National power grid generators always work at constant speed. For a 50 Hz grid in Europe, a generator with one pair of poles in the rotor must rotate at 3000 RPM (50 cycles per second); two pairs of poles must rotate at 1500 RPM; three pairs at 1000 RPM; four pairs 750 RPM, etc. Those pairs of poles are created by electromagnets, that once energised provide the electromagnetic excitation field, required to induce an even stronger electromagnetic field on the stator, whenever the magnetic lines of force are cut in the air-gap, by means of mechanical rotation.

This invention is fully based on those conventional generators, but there are three noticeable and very important differences, claimed by this invention, between a conventional AC three-phase synchronous generator and the innovative AC three-phase synchronised generator presented by this patent of invention.

The first difference is that conventional electrical generators, supplying National electrical grids World-wide, they work at constant rotation speed and variable power and torque. The generator claimed by this invention is aimed to work at constant power and constant torque. Hence it also must have constant "apparent" speed, because Physically the total power (in Watts) produced and wasted by any generator is calculated as torque in N-m (Newton- metre) times angular velocity in rad/s (radian per second).

The second difference is that the usual static part of the generator, herein called rotating stator (1), is rotating and permanently coupled to the vehicle's engine shaft (13). According to this invention, the rotating stator (1) of the generator is where the high-tension electricity is generated, by means of electromagnetic induction. The rotating stator (1) is wired and its coils are wire wound like the stator of a conventional AC three-phase synchronous generator, as shown in Fig.8 and Fig.9. The rotating stator (1) is constructed and designed based on the number of excitation magnetic poles of the central rotor (2).

The rotating stator (1) of this invention is similar to the stator of a conventional AC three- phase generator. The basic difference is that all the electricity generated by the rotating stator (1) is short-circuited to the ground (19), on heavy loads (16, 17, 18), and converted into heat. Therefore, according to this invention no wire connection are need outside the rotating stator (1) of the generator. The only Physical connection of the rotating stator (1) is done by means of electromagnetic induction, which translates into magnetic induced fields and counter-electromotive force.

Like in a conventional AC synchronous generator, this generator can be turned on and off, by means of energising the electromagnetic excitation field existent in the central rotor (2) of the generator. The central rotor (2) is a cylindrical wire wound laminated iron piece, composed by one, two, or more pair of electromagnetic poles (namely one pair is one North and one South magnetic poles). The excitation magnetic field of the central rotor (2) controls the electricity and the electromagnetic torque delivered by the generator, like in the case of any conventional AC synchronous generator.

The generator herein described is turned upside down, compared to the layout of a conventional generator. The conventional rotating part is stopped and the stopped part is rotating. The reason of that inversion is concerned with conventional clutch design, to avoid the necessity of electric rotating contacts, in order to eliminate tear and wear. The electromagnetic induction phenomenon is related by what is seen by the air-gap (3), between the two different parts of the generator. If the air-gap (3) sees a rotating magnetic field, then an induced voltage is generated, according to Faraday's Law and Lenz's Law of induction. It doesn't matter who is rotating and who is stopped.

The third main difference, between this invention and conventional AC synchronous generators, follows from the first one above-mentioned, that is: The generator described by this invention is aimed to work at constant power and constant torque. But in reality it must work with highly variable vehicle's engine rotation speeds, because the generator herein described must be directly coupled to vehicle's engine main shaft (13), and vehicles engines are highly variable speed machines. Then this particular generator must work at many different mechanical angular velocities and that will be very difficult without the following inventive step. If it were used a conventional generator it will produce variable power, because the power produce by any generator is calculated as torque times angular speed. Therefore, for a given rated nominal power, the torque generated would be changing accordingly to rotation speed. Therefore, at vehicle's engine high rotation speeds, the electrical power generated would be very high and a large generator is required, in order to be able to generate the torque required by the clutch actuation system. This behaviour of conventional AC synchronous generator would cause this invention to be much less competitive, because of the resultant size of the required generator.

According to this invention, the excitation magnetic field of the central rotor (2) cannot be permanently supplied by direct current (DC), to the electromagnets (8), like is the case of conventional AC synchronous generators. In order to achieve constant power and constant torque, the central rotor (2) must be supplied (4) by alternating current (AC), to have electromagnetic rotation. The nature of that electromagnetic rotation, of the central rotor (2) exciter field (not seen by Human eyes), is of the same nature as the excitation field of conventional AC motors. The angular magnetic velocity produced and seen by the air-gap (3) is given by the frequency of the alternating current supplied to the central rotor (2), based on the number of real magnetic instantaneous poles of the central rotor (2), as shown in Fig.5-7.

According to this invention, the electromagnetic rotating field, seen by the air-gap (3), is composed by the sum of two different angular velocities. The first angular velocity is the mechanical angular velocity of vehicle's engine, herein symbolically denoted by ω_m, relative to the central rotor (2) that is assumed to be stopped. The second angular velocity is the result of the magnetic frequency caused by the AC current supplied to the central rotor (2). The central rotor (2) is wire wound like any conventional electrical AC three-phase motor, as shown in Fig. 6 e Fig.7. The frequency of the supplied AC three-phase current defines in the generator air-gap (3) an electromagnetic angular velocity, of the same kind used to turn an electrical AC three-phase motor. That electromagnetic angular velocity is herein symbolically denoted by coe. Notice that this alternating behaviour of the central rotor (2) also solves the problem concerned to remnant magnetisation of the ferromagnetic core, allowing for a total generator shutdown, which is very important for this kind of applications.

According to this invention, the theoretically constant power P (in Watts), that the generator must deliver, is equal to the constant rated torque T (in N-m) times the differential angular velocity (ωm - ωe) expressed in rad/s, between vehicles engine mechanical rotation ωm and the generator excitation angular velocity ωe. Therefore, the differential angular velocity (ω_m - ωe), that will be seen by the air-gap (3), is aimed to be constant. On this theoretical conditions, the equation defining the theoretical working mechanism of this innovative generator is the following: P = T (ω_m - ωe) = constant.

In order to create a rotating exciting field, supplied by three-phase current, the central rotor (2) of this invention must have three times more magnetic poles then a conventional generator does. Three times more poles are needed to create the fictitious and apparent electromagnetic rotation ω_e, not existing in a conventional generator excitation field. In order to achieve that electromagnetic rotating field ωe, the electromagnets (8) creating the magnetic poles in the central rotor (2) must be wired like in the case of conventional delta, or star, three-phase electrical connection, as shown in Fig.6 and Fig.7.

According to the present invention the electromagnets (8), of the central rotor (2), must be wire wound like any conventional three-phase delta, or star, connection used for the excitation field of an AC three-phase electrical motor. Therefore we can say that the central rotor (2) also acts like a motor excitation field, when supplied (4) by an AC three-phase current. Therefore only three power wires (20, 21, 22) for a delta connection, or three power wires (20, 21, 22) plus ground (19) (or neutral (19)) for a star connection, are needed to create the exciter field rotation speed ωe of this particular invention. Those three (20, 21, 22) or four (19, 20, 21, 22) electrical wires (4) resume all the external connections needed in order to actuate this invention and provide full control over the clutch actuation force. No rotating electrical contacts are need

Fig.6 shows a central rotor (2) three-phase (20, 21, 22) coil wired in delta connection. Fig.7 shows the same central rotor (2) of Fig.6 wired in star connection.

Both Fig.6 and Fig.7 show a central rotor (2), designed according to this invention, that are wire wound and connected like any three-phase excitation field of any conventional three- phase electrical motor. Also, according to this invention, the current supplied to the central rotor (2) must be AC three-phase electrical current with variable frequency, from zero up to any desired frequency.

In order to design an automatic clutch actuation system, based on this invention, the first and most important value to be established is the value of the nominal and constant differential angular velocity (ωm - ωe), seen by the air-gap (3), between the vehicles engine real angular velocity ωm and the apparent exciter field angular velocity ωe. According to this invention, vehicles engine angular velocity com must be always bigger then the apparent exciter field angular velocity ω_e and both must rotate physically in the same direction. It will be that constant and positive value (ωm - ωe) that will define the power of the generator.

Because both angular velocities ωm and ωe must have the same direction of rotation and vehicles engine angular velocity ω_m must be always bigger then the apparent exciter electromagnetic angular velocity ω_e, then the electrical machine (1, 2, 3) herein described will work as a generator, according to the basic working mechanism of this invention, not as a motor. But if the apparent exciter field angular velocity ωe physically rotates contrary to the sense of rotation of vehicle's engine ωm, then this electrical machine (1, 2, 3) will work partially like a motor, trying to reverse the mechanical sense of rotation ωm of vehicle's engine. The clutch actuation system still works, based on the same working mechanism presented by this invention, but it will work much stronger then previously. On the other hand, if the apparent exciter electromagnetic angular velocity ωe is bigger then ω_m, then this electrical machine (1, 2, 3) will work like a pure motor, trying to speed up vehicle's engine ω_m and not actuating the clutch system anymore, because it missies the basic working mechanism of this invention.

Fig.5 shows a generator according to this invention, that in fact only has two pairs of magnetic poles in the central rotor (2). According to conventional AC three-phase synchronous generator construction rules, if the central rotor (2) has two pairs of magnetic poles, the rotating stator (1) must have six pairs of magnetic poles, or twelve magnetic poles total to be three-phase. The polygonal lines filled with different tonalities, shown in Fig.5, represents an artistic conceptual vision of what could be the so-called magnetic poles. If we assume that darker filled shapes represents a North pole and lighter filled shapes represents a South pole, then we realise that the central rotor (2) has always two North poles and two South poles, spaced 180 degrees electrically. Because the central rotor (2) has two pairs of poles, when the rotating stator (1) physically rotates 360 degrees, each pole (9) (or each coil (9)) of the rotating stator (1) will see a North pole passing twice, plus a South pole passing twice, hence a double frequency, or 720 degrees, or two revolutions.

Nevertheless, as shown in Fig.3 and Fig.5-7, the central rotor (2) has twelve independent poles (8), which are the triple of those first established (two pairs of poles equals four poles total). The reason is that instead of using DC current to create two pairs of magnetic poles in the central rotor (2), this invention must use AC three-phase current. This result in a rotating magnetic field, that conceptually will have always the same constant shape, shown in Fig.5, and that will be rotating as if it was a solid body. Therefore, the current in each electromagnet (8) (or each coil (8)) of the central rotor (2) will be changing synchronised with the AC three-phase frequency that is being supplied. Basically this is exactly the behaviour of any excitation field of an AC three-phase motor.

Because there are two pairs of magnetic poles build in the central rotor (2), the generator excitation field is rotating with half the nominal frequency of the conventional AC three- phase current, that is being externally supplied to turn the generator on. Therefore, the frequency of the supplied AC three-phase current must be doubled to attain a required ωe value. When the frequency of the AC current supplied is set to be zero, the magnetic poles don't rotate electrically and the excitation magnetic field stands still, being physically stopped, as shown in Fig.5. When the frequency of the AC current supplied has any value, the exciter magnetic field virtually rotates with half of that frequency. If there were only one pair of poles the exciter magnetic field will be rotating with the same frequency of the AC current supplied. If there were three pair of poles the exciter magnetic field will rotate at one third of the AC frequency, etc. , like in the case of any conventional electrical motor. According to this invention the two pairs of magnetic poles, conceptually shown in the central rotor (2) of Fig.5, will create six pairs of magnetic poles on the rotating stator (1), which are the triple of the excitation poles. Hence, the electricity produced by this generator within the rotating stator (1) will be three-phase current. If the central rotor (2) has only one pair of poles, the rotating stator (1) must have three pairs of poles. If the central rotor (2) has three pairs of poles, the rotating stator (1) must have nine pairs of poles, etc.

Fig.8 shows a rotating stator (1), according to this invention, whose output is wired in three-phase delta connection (the most efficient). Each phase line of the three output lines is short-circuited to the ground (19), or neutral (19), by means of small convenient electrical impedance (16, 17, 18), respectively. Because the rotating stator (1) is wire wound like any conventional three-phase generator output, the rotating stator (1) output will be conventional three-phase current.

Fig.9 shows the same rotating stator (1) shown in Fig.8, the difference is that the output is wired in three-phase star connection, according to this invention.

Any of the two possible output connections, conventional delta or star, must dissipate all the power generated to the ground (19), or to a neutral (19) point. Normally, the ground (19) must be vehicle's chassis ground, by means of an electrical connection to the iron laminated piece of the rotating stator (1), or the clutch housing (25). But, because the open circuit voltage generated could be in the order of thousands of Volts, instead of vehicle's chassis ground, a neutral (19) point, made of conductive material, could be used and made electrically isolated from vehicle's ground. That neutral (19) point rotates along with the rotating stator (1) and the heavy-loads (16, 17, 18) attached.

According to this invention, nominal rated power (in Watts), nominal rated torque (in N m) and nominal differential angular velocity (ω_m - ωe) (in rad/s) of the generator, they must be defined and determined in conditions of a null apparent excitation field angular velocity, which means ω_e=0. Therefore, at nominal conditions, the generator must have a non- electrically rotating electromagnetic excitation field, like in the case of a conventional generator. Therefore, at nominal conditions, the central rotor (2) of the generator must be supplied by direct current (DC), which in fact equals to an AC three-phase current whose frequency is zero. A null apparent exciting electromagnetic angular velocity

corresponds to a zero frequency three-phase electrical current supplied to the central rotor (2), which means that the three sinusoid curves, spaced 120 degrees in the time line, and describing the conventional three-phase current, must be frozen in a convenient point of the time line, providing different voltage and current value phase lines (20, 21, 22), being one of the current phase lines (20, 21, 22) inversely polarised relative to the others. This is normal three-phase current behaviour. Therefore, phase lines (20, 21, 22) sequence will determine the sense of rotation, clockwise, or counter-clockwise, of ωe.

According to this invention, the AC three-phase current can have any frequency, from zero up to hundreds of Hertz, including "negative values" that translates into a phase sequence change, that consists in the change of any two of the three lines (20, 21, 22) supplying (4) the central rotor (2). This kind of AC variable frequency three-phase current is actually used World-wide in commercial modules, called variable speed drives, used in order to change mechanical rotation speed of AC three-phase electrical motors.

The best point to define nominal power of the generator will depend on the particular application. For instance, if vehicle's engine operation speed is between 800 RPM and 8000 RPM and if we want the nominal power of the generator to be around 1500 RPM, we must regard the following procedures. For vehicle's engine speeds lower then 1500 RPM, the strength of generator excitation field must increase by means of increasing the voltage supplied to the central rotor (2), keeping it at zero frequency. For vehicle's engine speed above 1500 RPM, theoretically, only the frequency of the AC three-phase current supplied must increase, proportionally to vehicle's engine speed increase, seeking the point (com-coe) constant. Only minor compensation adjustments on the voltage supplied must be required. This procedures will limit the electric power produced by the generator rotating stator (1) to a constant value. Hence, also constant torque, because the differential velocity (ωm - ωe) has been assumed to be constant. If we chose nominal power of the generator to be around the vehicle's engine idle rotation, about 800-900 RPM, theoretically only a control over the frequency of the excitation field is necessary to achieve constant power and constant torque, over the full range of vehicle's engine speed. Choosing vehicle's engine idle rotation to define the nominal generator rated power will result in minimum power required for the external excitation field, rendering the efficiency of this invention higher. In general, it must be done adjustments of the voltage and frequency of the current supplied to the generator excitation field, to control vehicle's start, normal running condition and smooth drive. Smooth start of the vehicle can be achieved by means of increasing the frequency of the current supplied to the central rotor (2), or simply accelerating vehicle's engine and therefore increasing com. Torque will be reduced proportionally.

Because of the well-known impedance nature of coils (electromagnets), translated into inductance, reactance, power factor, phase shift, etc. All the system must be regulated on the usual basic electrical parameters, voltage, current, frequency, power factor, sinusoids shape, etc., via the excitation field placed on the central rotor (2), using auxiliary electronic systems, software, etc.

According to this invention, it was pointed very clear that all the power required to actuate the clutch spring (11) results from a very well known phenomenon, that is the Physical conversion of pure mechanical energy into electricity, according to Faraday's and Lenz's Laws, translated by Maxwell equations. On the other hand, notice that vehicles engine is a very powerful machine. Therefore, by nature the generator will try to take all the mechanical power he can get. Normally, the power generated is to be limited and controlled by the magnetic excitation field of the central rotor (2). Also notice that when a rotating excitation magnetic field (ωe) is created, in the central rotor (2), the aim of that rotating magnetic field (ω_e) is to reduce the power produced by the generator, allowing the use of a small machine. Therefore, for safety reasons, it is highly recommended that the rotating stator (1) has build in it some kind of voltage and current limiting device. That voltage/current limiting device could be any kind of electronic device; electromechanical device; thermal effect device, etc. If a voltage/current limiting device doesn't exist in the rotating stator (1) and there is a failure on the excitation magnetic field control of the central rotor (2), the power delivered by the generator can be uncontrollably high, up to the total destruction, because the generator always will try to extract all the mechanical power available. According to this invention, the voltage/current limiting device is to be incorporated within the so-called heavy-loads (16, 17, 18), that are small impedance used to short-circuit the generator electric output and also aimed to correct the power factor of the generator.

Due to the transitory nature of clutch actuation systems, the generator will be turned on when the clutch spring (11) is to be actuated. Therefore, most of vehicle's running time the generator will be turned off, by means of a null current supplied to the central rotor (2). When the vehicle's clutch is to be actuated, first an auxiliary electronic system measures the vehicles engine speed (ω_m) and then provide the required excitation Voltage to the central rotor (2), of AC three-phase current, whose frequency (ωe) must be the frequency needed to have (ω_m - ωe) = constant = nominal differential angular velocity. Therefore, the electromagnetic torque in the air gap (3) will be theoretically constant and equal to the nominal value needed to actuate the clutch spring (11).

Based on general Physical Law's, the required energy (in Joules) to mechanically actuate the clutch spring (11), will be calculated as clutch spring (11) force (in N) times the clutch needed displacement (15) (in metre). On the other hand, the energy required to completely displace the central rotor (2), a given angular displacement (14), will be mechanically calculated as the electromagnetic torque (N-m) times the angular displacement (rad) of the central rotor (2). Energy conservation Law states that in an ideal system, without friction losses onto the double screw threads (5, 6, 7), both energies must be equal. Based on this Law we can calculate the electromagnetic torque required to actuate the clutch spring (11). For instance, if the nominal clutch spring (11) force is 1500 N (150 kg) and the required displacement (15) 0,015m, the energy involved will be 22,5 Joules, plus friction losses. Assuming 10% friction losses, the total energy can be around 25 Joules. On the other hand, if we assume the central rotor (2) angular displacement (14) to be 5π/6 rad (150 degrees), then the electromagnetic torque required will be 9,55 N-m. Therefore, the generator must produce the torque of 9,55 N-m at the nominal design differential angular velocity (ωm - ωe). If the nominal differential angular velocity (ωm - ωe) of the generator is designed to be 900 RPM (94,25 rad/s), then the mechanical power developed must be 9,55 N-m x 94,25 rad/s = 900 Watts. Increasing the nominal rotation speed the power required will increase. For a nominal rotation speed design of 1500 RPM (157,1 rad/s) the mechanical power will be 1500 Watts. Assuming a horse power factor of 0,8 for the generator rotating stator (1), the total mechanical power consumed by the generator, from vehicle's engine, will be calculated as 900 Watts / 0,8 = 1125 Watts (or 1,53 HP) and 1500 Watts / 0,8 = 1875 Watts (or 2,55 HP).

The theoretical time response for the clutch actuation will be calculated as Energy /Power, therefore 25 Joules / 900 Watts = 0,028 seconds in the first case, and 25 Joules / 1500 Watts = 0,017 seconds in the second case. But in real engineering conditions, we also have to account for central rotor (2) kinetic energy and relative angular velocity variation, between the rotating stator (1) and the central rotor (2) (acceleration), rendering engineering calculations much more complex. Nevertheless, the real time response could be much better then 0,1 seconds for the above mentioned examples. Notice that, when the central rotor (2) starts to accelerate the differential angular velocity (ω_m - ωe) will be reduced and, therefore, the electromagnetic torque must be increased to generate constant power for the clutch actuation effort. Increasing central rotor (2) angular displacement (14) will proportionally reduce the total power required for clutch spring (11) actuation, but it will increase time response of the whole system.

Notice that, hypothetically, if we use a conventional generator for this task, when vehicle's engine rotate at maximum rotation speed, for instance 6000 RPM (628 rad/s), in order for the generator to develop the torque of 9,55 N-m required to actuate clutch spring (11), in the same time response, the generator must develop a power of (9,55 N-m x 628 rad/s) / / 0,8 = 7497 Watts (10,2 HP) and, therefore, we need to use a large and heavy machine. By means of the innovative excitation field, presented by this patent of invention, it allows the use of much less power rated generators, with fast time response to be competitive with the actual state of the art. But, the basic working mechanism of this invention doesn't work without mechanical energy, supplied by vehicle's engine rotation. Whenever vehicle's engine stops the clutch spring (11) cannot be actuated, without an auxiliary system.

By means of the present invention, the clutch actuation is so quickly that, if a good electronic AC three-phase current system is used, to control the generator excitation field, the kinetic energy of vehicle's engine fly-wheel (24) will be enough to never allow the engine rotation fall, and stop, without first the clutch spring (11) being actuated and vehicle's gearbox released.

Nevertheless, a failure can occur and then a common driver's clutch pedal, associated with a mechanical system, can be used. One of the best solutions will be the use of a steel cable (10), as shown in Fig.1-3, connected to a common driver's clutch pedal. If the angular displacement (14) of the central rotor (2) doesn't exceed a value of about 150 degrees, the use of a steel cable (10) will be a very good cost-effective solution.

Another good solution uses the fact that this same generator (1, 2, 3) can be used as a motor, by means of reversing any two of the three phase lines (20, 21, 22) of the three- phase current supplied to central rotor (2). Physically, this corresponds to reverse the sense of rotation of the electromagnetic excitation field ω_e created in the central rotor (2). This electrical solution is much more elegant, but also more expensive, because a powerful electric power supply will be needed.

Contrary to the generator mode of operation, the excitation field required to turn the generator as a motor will need to deliver the full rated power, for the same clutch time response. Therefore, the auxiliary power supply must deliver values like 1772 Watts and 2945 Watts, for the examples herein given. Also, in order to attain the value of the rated power, by means of vehicle's main battery, if vehicle's battery is rated 12 Volts DC the total consumption will be about 140 Amperes and 230 Amperes DC, respectively. But increasing time response will reduce proportionally these values and this solution can be easily implemented.

Claims

1. Clutch actuation system, comprising two major systems, being one electromagnetic and another mechanical: a) The electromagnetic system comprises a special generator, aimed to work at constant power and constant torque, composed by a rotating stator (1), that is a laminated iron piece, wire wound, composed by several coils (9) (electromagnets (9)). The rotating stator (1) is permanently coupled to vehicle's engine main shaft (13), via the engine fly-wheel (24) and the clutch disk housing (25). Therefore, the rotating stator (1) is always rotating, whenever the engine is running. The central rotor (2) of the generator also is a laminated iron piece, wire wound, composed by several coils (8). Between the rotating stator (1) and the central rotor (2) there is an air-gap (3), where the energy conversion takes place. These above three parts are the so called generator (1, 2, 3). According to this invention the central rotor (2) is assumed to be stopped, but in fact it does have some angular displacement (14) that, in general, must be a fraction of one complete revolution. The central rotor (2) has the triple of the conventional required number of permanent DC magnetic poles, because the central rotor (2) must be supplied by AC three-phase current, with variable frequency from zero up to any desired value, in order to create a synchronised rotating magnetic excitation field, used to turn on and off the generator and produce the clutch spring (11) actuation. b) The mechanical system is composed by a set of two large pitch screw threads (5, 6, 7), used to convert angular displacement (14) into linear displacement (15). It is composed by three parts, being one the innermost part (5), which must be the fulcrum, normally attached to the gearbox housing. That fulcrum (5) comprises the first large screw thread, drawn in its exterior diameter, and it could be left or right handed, depending on vehicle's engine sense of rotation. The outermost part (7) is rigidly attached to the central rotor (2), by means of thermal expansion or any other means. That outermost part (7) comprises the second large screw thread, drawn in its interior diameter. This outermost part (7) is the one that will receive the torque and the angular displacement (14) from the central rotor (2), when the generator is turned on. This outermost part (7) will have a reaction force against the fulcrum housing, by means of a conventional axial bearing (23). The double screw thread central part (6), of the screw thread system, is positioned between the two above mentioned ones (5, 7). Therefore, both counterparts of the two large screw threads must be drawn in both sides of this central part (6), exterior and interior diameter, respectively. It will be this double screw central part (6) that will perform the linear displacement (15) in order to actuate the clutch spring (11) and, therefore, it must have a conventional axial bearing (26), assembled on the side facing the clutch spring (11). According to this invention, the two large screw threads drawn in the central part (6) must be opposite, which means that when one is a left screw thread the other must be a right screw thread, and vice-versa, depending on vehicle's engine sense of rotation.

2. Clutch actuation system according to Claim 1, characterised in that the power required to actuate the clutch spring (11) is supplied, in real time, by vehicle's engine mechanical angular velocity and torque, by means of mechanical energy conversion performed by the synchronised electrical generator (1, 2, 3), creating counter-electromotive force when it's turned on. The basic working mechanism of this clutch actuation system cannot work if the vehicle's engine is not running, or if it stops suddenly, because it missies the required mechanical power for the energy conversion.

3. Clutch actuation system according to Claim 1-2, characterised in that the synchronised electrical generator (1, 2, 3) is aimed to work at constant power, constant torque and constant "apparent" angular electromechanical combined velocity, regardless of vehicle's engine highly variable mechanical rotation speed, ωm. The equation defining the theoretical working mechanism of this innovative generator is the following: P=T(ωm- ωe) = constant. Being P the power in Watts, T the torque in Newton-metre and (ω_m - ωe) the differential angular velocity, in radians per second, seen by the air-gap (3), between the rotating stator (1) angular velocity, ωm, and the comparable electromagnetic angular velocity, ωe, of the electromagnetic excitation field. That differential angular velocity (ωm - ωe) will be the synchronisation speed, established by design, in order to have constant power and torque, based on Physical Laws. The electromagnetic angular velocity, ωe, is created by means of wire wound the central rotor (2) as any AC three-phase excitation field, like an AC three- phase motor. The central rotor (2) must be supplied by conventional three-phase current, with the required frequency to have a comparable electromagnetic angular velocity, ωe. Providing that mechanical angular velocity, ωm, is bigger then the electromagnetic angular velocity, ω_e, this electrical machine will work like a generator, inducing clutch operation.

4. Clutch actuation system according to Claim 1, characterised in that the said synchronised electrical generator (1, 2, 3) does not produce any usable electricity, because all the high- voltage electricity it produces is to be short-circuited onto heavy-loads (16, 17, 18), assembled locally, and all power dissipated as heat. Those heavy-loads (16, 17, 18) must be small convenient impedance loads, aimed to correct the power factor and produce load, also incorporating a voltage/current limiting device to avoid generation overload, for safety reasons. No electrical wire connections or any other material connection exists outside the rotating stator (1) of the synchronised generator, because the heavy-loads (16, 17,18) and the ground neutral (19) point, they rotate along with the rotating stator (1), that is considered to be an electrical isolated system. The only Physical connection between the rotating stator (1) and the central rotor (2) is done by means of electromagnetic induction, which translates to magnetic induced fields and electromagnetic developed torque, used to produce the clutch spring (11) actuation.

5. Clutch actuation system according to Claim 1, characterised in that, by means of the double large pitch screw thread system (5, 6, 7), the central rotor (2) doesn't have any linear displacement (15) and therefore it will be permanently aligned with the rotating stator (1), which is very important for generator correct work. Also, if both screw thread pitch angle are equal, the required electromagnetic torque the central rotor (2) must deliver, to actuate the clutch spring (11), will be half the value for any given angular displacement (14) of the central rotor (2), compared to the case that only one screw thread is used to convert angular (14) to linear (15) displacement.

6. Clutch actuation system according to Claim 1-5, characterised in that, if vehicle's engine is not running, then an external powerful auxiliary system is required to actuate the clutch spring (11). If the angular displacement (14) of the central rotor (2) doesn't exceed a value of about 150 degrees, the use of a steel cable (10) will be a very good cost-effective solution. Another good solution uses the fact that this same generator (1, 2, 3) can be used as a motor, by means of reversing any two of the three phase lines (20, 21, 22) of the AC three-phase current supplied to central rotor (2). Physically, this corresponds to reverse the sense of rotation of the electromagnetic excitation field ωe, created in the central rotor (2). Contrary to the generator mode of operation, the excitation field required to turn the generator as a motor will need to deliver the full rated power, for the same clutch time response. Longer time response will need less power.