Patent Description:
As background, <CIT> describes a piece of electrical equipment for connecting to an electromechanical brake actuator and to an electromechanical drive actuator; <CIT> describes an electric brake apparatus and electric brake system; <CIT> describes an electro mechanical brake force sensing unit.

An electromechanical brake system typically has an electromechanical actuation device, with which a friction brake lining can be pressed for braking against a brake body that is fixed against relative rotation to a vehicle wheel. The brake body is typically a brake disk or a brake drum. The actuation device typically has an electric motor and a rotation-to-translation conversion gear that converts a rotary driving motion of the electric motor into a translational motion for pressing the friction brake lining against the brake body. Main types of automotive disk brakes, e.g., include a fixed type caliper with pistons on both sides of the brake disk and a floating type caliper with piston(s) on one side of the caliper. Worm gears, such as spindle gears or roller worm drives, are often used as rotation-to-translation conversion gears. It is also possible to convert the rotary motion into a translational motion by means of a pivotable cam, for instance. A series of step-down gears, for instance in the form of planetary gears, is typically placed between the electric motor and the rotation-to-translation conversion gear, to increase the necessary torque. Self-boosting electromechanical brake systems have a self-booster that converts a frictional force, exerted by the rotating brake body against the friction brake lining that is pressed for braking against the brake body, into a contact pressure, which presses the friction brake lining against the brake body in addition to a contact pressure that is exerted by the actuation device. Wedge, ramp, and lever mechanisms can be used for the self-boosting.

There is a need for further simplification and compactification of electromechanical brake systems, e.g. allowing them to be combined and integrated with other systems.

Aspects of the present invention relate to an electromechanical brake system. A brake mechanism is configured to apply braking to a wheel of a vehicle, or release braking of the wheel, depending on a position of the brake mechanism. An electric brake motor is configured to transduce electrical power into mechanical power. A force transmission chain is configured to transmit the mechanical power from the electric brake motor to the brake mechanism for changing the position of the brake mechanism. As described herein the electric brake motor is preferably a high-voltage motor. The inventors find that, by connecting the electro-mechanical brake actuator to a high-voltage energy source, e.g. battery, the mechanical transmission between the electrical machine and the brake disc can be substantially simplified compared to a conventional low voltage brake motor. For example, a higher voltage motor may consume a smaller current, and the motor can provide a higher torque, needing a smaller transmission ratio thus resulting in a simplified transmission. Advantageously, the simplified transmission and/or lower current can lead to improved efficiency. Furthermore, the inventors recognize that this allows further integration of components leading to a more compact design wherein various functions can be combined and/or integrated. For example, the compact brake mechanism allows the system to integrated into the wheel, optionally combined with drive system, e.g. including a traction motor that can also be fitted into the wheel; or otherwise placed in close proximity. Advantageously, the brake and traction motor can both receive power from the same high voltage source. Furthermore, the proximity of these systems allows combining functions such as cooling and/or regenerative braking. Also the length of high power electrical wiring can be decreased.

These and other features, aspects, and advantages of the apparatus, systems and methods of the present invention will become better understood from the following description, appended claims, and accompanying drawing wherein:.

<FIG> illustrates a schematic diagram of an electromechanical brake system <NUM>. Typically, the brake system <NUM> comprises a brake mechanism <NUM>. For example, the brake mechanism <NUM> is configured to apply braking to a wheel <NUM> of a vehicle, or release braking of the wheel <NUM>, depending on a position X of the brake mechanism <NUM>. As illustrated, an electric brake motor <NUM> is configured to transduce electrical power into mechanical power Tm. In some embodiments, the brake system <NUM> comprises a force transmission chain <NUM>. For example, the force transmission chain <NUM> is configured to transmit the mechanical power Tm from the electric brake motor <NUM> to the brake mechanism <NUM>, e.g. Tm→Tt→Fa. This may be used for changing the position X of the brake mechanism <NUM>.

In a preferred embodiment, the electric brake motor <NUM> is a high-voltage motor configured to receive a high voltage "HV". As described herein, the term high voltage "HV" is a voltage of at least two hundred volt, preferably at least four hundred volt, more preferably at least six hundred volt, e.g. up to twelve hundred volt, or more. This may be compared to a traditional brake motor operating typically at twelve volt. Other electronics are typically operated under five volts. The higher the voltage, the less current is drawn, the higher the efficiency and/or the less current is drawn. Preferably, the electric brake motor <NUM> is configured to operate the brake system with an electric current of less than fifty Amperes, preferably less than twenty-five Amperes, or even less than ten Amperes.

Additionally, or alternatively, a relatively high torque is available directly from an output shaft of the motor at reasonable current without overheating. So advantageously, the transmission ratio to the brake mechanism can be relatively low. In a preferred embodiment, the force transmission chain <NUM> between the electric brake motor <NUM> and the brake mechanism <NUM> has a transmission ratio i less than twenty, preferably less than ten, or even less than five.

Typically, the force transmission chain <NUM> comprises a transmission <NUM> configured to increase torque between the motor and the brake mechanism <NUM>, e.g. by a set of rotating gears with different radius. For example, the motor delivers a torque Tm on its output shaft, while the transmission increases this to a torque Tt. The factor (Tt/Tm) by which the torque is increased is typically proportional to the transmission ratio. In some embodiments, a robust and compact solution is provided by including at least one planetary gear set in the transmission <NUM>. Of course also other or further gearsets can be included. At the end of the force transmission chain <NUM>, the rotating motion of the transmission <NUM> can be converted to a linear motion by a mechanism <NUM>. For example, the mechanism <NUM> is configured converts rotational motion into linear motion, e.g. comprising a nut and spindle. Also other mechanism can be envisaged such as a linear actuator. In some embodiments, the electric brake motor <NUM> is directly connected to the mechanism <NUM> which actuates the brake pad <NUM> against the brake disc <NUM>. So the transmission ratio can be one, i.e. the output torque Tm of the motor is applied directly to drive the mechanism <NUM>.

In one embodiment, the brake system comprises a piston-type mechanism, but also other mechanism may be used. Typically, the brake transmission comprises a set of gears which are operationally connected to an output axle of the brake motor <NUM>. In some embodiments, gears in the brake transmission are configured to drive a spindle which is housed in a spindle nut to move a piston. In one embodiment, the piston in turn is guided, e.g. by guide pins to drive the opening and closing movements of a caliper which can be considered part of the brake mechanism <NUM>. For example, the caliper is fitted with two opposing brake pads. The mechanical energy which is transmitted via the brake transmission to the brake mechanism <NUM> is thus ultimately used to drive the two braking pads closer to each other to perform or activate a braking operation, and apart from each other to release of deactivate a braking operation. In some embodiments, the caliper is fixed to a bracket by which the caliper is, e.g., suspended over a brake disc <NUM> of a wheel such that the brake disc is provided between the pads of the caliper. For example, the brake disc <NUM>, is connected to at least one wheel of the vehicle, e.g. to the wheel itself or on a wheel axle directly connected to the wheel and brake disc. Preferably, the brake mechanism <NUM> as described herein comprises a floating type caliper with one or more pistons (configured to operate the one or more brake pads and/or clamp the brake disc <NUM>) exclusively on one side of the caliper.

In a preferred embodiment, the electric brake motor <NUM> is connected to a high-voltage energy source <NUM> via an inverter <NUM>. A power inverter, or inverter, is a power electronic device or circuitry that changes direct current (DC) to alternating current (AC). Typically, the inverter does not produce any power; the power is provided by the DC source, e.g. battery. For example, the inverter comprising metal-oxide-semiconductor field-effect transistors (MOSFET). Alternatively, or additionally, the inverter comprises Insulated Gate Bipolar Transistors (IGBT).

In a preferred embodiment, the electric brake motor <NUM> is configured to receive power from the energy source <NUM> delivering its output voltage V (= |V+ - V-|) to the inverter <NUM>. Preferably, this output voltage V of the energy source <NUM> is in range of the aforementioned high voltage "HV". In other words, the (DC) input voltage to the inverter <NUM> is the output voltage V+,V- of the energy source <NUM> and the electric brake motor <NUM> is preferably connected directly to the high-voltage energy source <NUM> via the inverter <NUM>. Alternatively, the output voltage of the high-voltage energy source <NUM> can be converted, e.g. by an optional DC/DC converter (not shown), to match an optimal (high) voltage of the inverter and/or motor, e.g. to work in an optimal efficiency range.

Typically, the inverter <NUM> is configured to output polyphase voltages, e.g. three-phase electric power, wherein each of the voltages V1,V2,V3 alternates with different phases. The conductors between the inverter and the motor are called lines, and the voltage between any two lines is called line voltage. The voltage measured between any line and neutral is called phase voltage. In some embodiments, at least one of the line voltage or the phase voltage of the inverter is in range of the aforementioned high voltage "HV".

In some embodiments, the electric brake motor <NUM> comprises a permanent magnet synchronous machine. Advantageously, this can provide a relatively high torque. Normally such motor can have the risk of demagnetizing the permanent magnets, e.g. using rare earth magnets, at high temperature. However, in view of the low current requirements of the present systems, this problem can be alleviated. Of course also other electrical motors can be used such as a switched reluctance motor, or a brushed or brushless direct current motor.

<FIG> illustrates aspects of an integrated drive and brake system <NUM>. In a preferred embodiment, the integrated system <NUM> comprises the electromechanical brake system <NUM>, as described herein, e.g. configured to apply or release braking "BR" to a wheel <NUM>. Most preferably, the integrated system <NUM> further comprises an electromechanical drive system <NUM>, e.g. configured to drive "DR" the wheel <NUM>.

In some embodiments, the integrated system <NUM> comprises a power distribution system <NUM> configured to receive the high voltage "HV" from a high voltage energy source <NUM> and distribute the high voltage "HV" to both the brake system <NUM> and drive system <NUM>,<NUM>. In a preferred embodiment, the power distribution system <NUM> is configured to supply the high voltage "HV" to the electric brake motor <NUM> of the electromechanical brake system <NUM> via a first inverter <NUM>. In another or further preferred embodiment, the power distribution system <NUM> is configured to supply the high voltage "HV" to a traction motor of the electromechanical drive system <NUM> via a second inverter <NUM>. In a preferred embodiment, the same high voltage "HV" energy source <NUM> is used for the brake motor in the brake system <NUM> and for a traction motor of the drive system <NUM>, which drives the wheel. In another or further preferred embodiment, the power distribution system <NUM> is disposed between the first and second inverters <NUM>,<NUM>. Accordingly, power cables can be kept relatively short.

Some aspects of the present invention can be embodied as a road vehicle comprising one or more of the integrated drive and brake systems <NUM> as described herein, preferably one for each wheel of the vehicle. Preferably, the vehicle comprises at least one high-voltage energy source <NUM> configured to supply the high voltage "HV" to the respective power distribution system <NUM> of each integrated drive and brake system <NUM>. For example, the high-voltage energy source <NUM> is a high-voltage rechargeable energy storage system. In some embodiments, the high-voltage energy source <NUM> comprises at least one of a Lithium-ion battery, a molten-salt battery, and a high-capacity lead battery. In other or further embodiments, the high-voltage energy source <NUM> comprises a super-capacitor or ultra-capacitor bank. For example, the vehicle can be a fully electric vehicle or hybrid vehicle. The brake system, as described herein can of course also be applied to a normal (non-electric) vehicle.

<FIG> illustrates other or further aspects of an integrated drive and brake system <NUM>. In some embodiments, the drive system <NUM> is configured for driving DR the wheel <NUM>, and the brake system <NUM> is configured for friction braking FB the wheel <NUM>. In other or further embodiments, the drive system <NUM> is configured to apply regenerative braking RB to the wheel <NUM> and supply regenerated power from the regenerative braking RB to charge CH the energy source <NUM>. For example, the system is configured to apply the friction braking FB in case the regenerative braking is insufficient.

In a preferred embodiment, the integrated drive and brake system <NUM> is configured to receive regenerated power from regeneratively braking RB the wheel <NUM> by the drive system <NUM>, and supply the regenerated power directly to the electromechanical brake system <NUM> for additionally applying friction braking FB to the wheel <NUM>, at least partially bypassing "BP" the energy source <NUM>, as illustrated. For example, the regenerated power can be output from the second inverter <NUM>, connected to the drive system <NUM>, to the first inverter <NUM>, connected to the electromechanical brake system <NUM>. This may be more efficient than first charging and then depleting the battery. In one embodiment, the output voltage from the second inverter <NUM> is converted before being fed into the first inverter <NUM>, e.g. by an optional DC/DC converter (not shown) there between. The same or another DC/DC converter (not shown) can be placed between the energy source <NUM> and the first inverter <NUM>.

<FIG> illustrates aspects of a cooling system <NUM>. In some embodiments, the integrated system comprises a shared cooling system <NUM> configured to apply cooling to both the first inverter <NUM> and the second inverter <NUM>. For example, the cooling system <NUM> can be integrated as part of a cooling block that houses both inverters. Typically, the cooling system <NUM> comprises an inlet 12i where cooling fluid is fed into the system, and an outlet where the fluid exits the system after absorbing heat from the electrical and/or mechanical systems.

In a preferred embodiment, e.g. as shown in <FIG>, the second inverter <NUM> is placed along a path of the cooling system <NUM> before first inverter <NUM>. For example, the second inverter <NUM> typically produces more heat since it has to drive motion of the vehicle, whereas the first inverter <NUM> only has to apply the braking. In another or further preferred embodiment, e.g. as shown in <FIG>, the first and second inverters <NUM>,<NUM> are disposed on opposite sides of the cooling system <NUM>, e.g. on opposite sides of the cooling block or plate housing the cooling system <NUM>. This can provide a particularly compact solution. For example, the cooling system can be integrated as part of the power distribution system <NUM>.

<FIG> illustrates a preferred embodiment wherein the drive and brake system <NUM> is integrated and arranged (at least partially) inside a wheel <NUM>. For example, the wheel <NUM> houses both the electromechanical brake system <NUM> and the drive system <NUM>. Most preferably, the wheel also houses the first and second inverters <NUM>,<NUM>, optionally including the power distribution system and/or cooling system (not indicated here). In some embodiments, the brake system <NUM> is arranged on a side of the wheel facing a chassis <NUM> of the vehicle and the drive system <NUM> is arranged on an opposite side facing away from the of chassis <NUM>. For example, a brake disc <NUM> is connected to rotate with the wheel <NUM>, and the brake system <NUM> is stationary inside the wheel and configured to grip brake disc <NUM> from inside the wheel, opposite the vehicle chassis <NUM>. In some embodiments, the drive system <NUM> comprises a stator <NUM> that is fixed inside the wheel <NUM>, and a rotor 200r configured to drive the wheel <NUM>.

<FIG> illustrate a respective force transmission chain of an electromechanical brake system <NUM>. Typically, the electric brake motor <NUM> comprises a stator <NUM> and a rotor 20r. In some embodiments, e.g. as shown in <FIG>, the rotor 20r is connected to an output shaft 20a. Preferably, the transmission <NUM> comprises at least one planetary gear set (PGS). In one embodiment, the output shaft 20a is connected to a sun gear 31a of the PGS. In another or further embodiment, the PGS comprises a planet gear 31b configured to rotate while the ring gear 31c is stationary. In some embodiments, a rotating planet cage and transmission output shaft 31d is connected to rotate with the planet gear 31b. In one embodiment, the output shaft 31d is connected to a rotating cage or spindle 32a which forms part of the mechanism <NUM>. The mechanism <NUM> comprises a profile 32b which, when rotated, causes an inner gear 32c to translate a shaft 32d which actuates the brake pad <NUM> against the brake disc <NUM>. Preferably, the mechanism <NUM> comprises a ball screw. Of course also other forms of linear actuation can be used.

Now with reference to <FIG>, it will be observed that an axial length of the system can substantially shortened compared to <FIG>. In a preferred embodiment, the brake system <NUM> comprises the mechanism <NUM> at partially inside a stator <NUM> of the electric brake motor <NUM>. For example, the rotor 20r comprises a hollow tube which rotates to directly or indirectly drive the mechanism <NUM>. In some embodiments, e.g. as shown in the figure, the rotor 20r forms part of a sun gear 31a that rotates against a planet gear 31b. In other or further embodiments, the planet gear 31b is connected to a rotating cage or spindle 32a that is part of the mechanism <NUM> disposed inside the rotor 20r. For example, as described before, The mechanism <NUM> comprises a profile 32b which, when rotated, causes an inner gear 32c to translate a shaft 32d which actuates the brake pad <NUM> against the brake disc <NUM>. While the PGS can be advantageous to increase the torque of the brake motor, it can also be envisaged to provide brake motor rotor 20r with the inner screw profile 32b, i.e. directly actuating the translating shaft 32d and brake pad <NUM>.

For the purpose of clarity and a concise description, features are described herein as part of the same or separate embodiments, however, it will be appreciated that the scope of the invention as defined in the appended claims may include embodiments having combinations of all or some of the features described. For example, while embodiments were shown for various arrangements of electrical and mechanical systems, also alternative ways may be envisaged by those skilled in the art having the benefit of the present invention for achieving a similar function and result. the electrical and mechanical components may be combined or split up into one or more alternative components. The various elements of the embodiments as discussed and shown offer certain advantages, such as providing a compact and efficient brake system. For example, the system can run at a higher efficiency point, because its operating point can be tuned by the transmission ratio. The simplified transmission ratio can also means less moving parts and a higher efficiency, improving also brake NVH (Noise, Vibration, and Harshness). The packaging of the complete solution can be smaller as well, because of the lower transmission ratio required, and the heatsink can also be smaller given that the heat dissipation is lower. Advantages offered by invention may also include very low heat dissipation because of the much lower current drawn from the electrical machine.

In interpreting the appended claims, it should be understood that the word "comprising" does not exclude the presence of other elements or acts than those listed in a given claim; the word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements; any reference signs in the claims do not limit their scope; several "means" may be represented by the same or different item(s) or implemented structure or function. Where one claim refers to another claim, this may indicate synergetic advantage achieved by the combination of their respective features. But the mere fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot also be used to advantage.

Claim 1:
An electromechanical brake system (<NUM>) for a road vehicle comprising
a brake mechanism (<NUM>) configured to apply braking to a wheel (<NUM>) of a vehicle, or release braking of the wheel (<NUM>), depending on a position (X) of the brake mechanism (<NUM>);
an electric brake motor (<NUM>) configured to transduce electrical power into mechanical power (Tm); and
a force transmission chain (<NUM>) configured to transmit (Tm→Tt→Fa) the mechanical power (Tm) from the electric brake motor (<NUM>) to the brake mechanism (<NUM>) for changing the position (X) of the brake mechanism (<NUM>);
characterised in that
the electric brake motor (<NUM>) is a high-voltage motor configured to receive a high voltage (HV) of at least two hundred volt.