Patent Description:
In general, an electronic brake system may include a hydraulic pressure supply device. Once a driver operates a brake pedal, the hydraulic pressure supply device of the electronic brake system receives an electrical signal indicating the driver's braking intention from a pedal displacement sensor that detects a displacement of the brake pedal, such that the hydraulic pressure is supplied to wheel cylinders.

The electronic brake system provided with the above-described hydraulic pressure supply device has been disclosed in European Registered Patent No. <CIT>. According to this European Patent document, the hydraulic pressure supply device may generate a hydraulic pressure required for braking and supply the hydraulic pressure to wheel cylinders by operating a motor based on a pedal effort of a brake pedal and changing a position of a piston due to a rotational force of the motor.

An electric motor apparatus disclosed in <CIT> is configured such that an energized system is divided into two independent systems. In a normal state, windings of a first system and a second system cooperate to rotate a rotor. When an error occurs in one of the two systems, the rotor may be rotated only by the winding of the other system. That is, even when one of the two systems fails, the other system is capable of functioning, and thus a fail-safe electric motor may be realized. As such, a separate winding motor is used for vehicle safety.

For example <CIT> discloses an electronic brake system which comprises: a reservoir storing brake fluid therein; an integrated master cylinder; a reservoir flow path allowing the reservoir to communicate with the integrated master cylinder; a hydraulic pressure supply device; and a hydraulic pressure control unit.

<CIT> relates to an electronic brake system comprising: a pedal operation unit for transmitting braking force to an electronic control unit; a reservoir in which working fluid is stored; and a braking pressure regulation unit operated by a pressure supply unit which is hydraulically connected to a wheel brake. The braking pressure regulation unit includes first and second hydraulic circuits which connect the pressure supply unit and the wheel brake through an inlet valve and directly or indirectly connect the wheel brake and the reservoir through an outlet valve. The first and second hydraulic circuits may be hydraulically provided independently of each other so that one of the first and second hydraulic circuits generates a braking pressure while the other operates.

<CIT> describes an electric brake system including a valve and a motor receiving power from a battery of a vehicle comprising: a motor speed detection unit detecting the rotational speed of the motor; a battery voltage detection unit detecting the voltage of a battery; a pedal detection unit detecting the operation and displacement of a brake pedal; a valve current detection unit the current of the valve; and an electronic control unit which determines the current limit of the battery according to the operating time of the brake pedal, determines the output limit of an inverter driving the motor based on the determined current limit of the battery, the current of the valve, and the voltage of the battery, determines the d-axis current of the motor based on the rotational speed of the motor and the voltage of the battery, determines the torque limit of the motor based on the determined d-axis current, the output limit of the inverter, and the dynamic loss of the motor, compares the determined torque limit of the motor with a torque command according to the displacement of the brake pedal to determine a final torque command, and outputs the determined final torque command.

<CIT> discloses an electric brake system including a hydraulic pressure supply device configured to generate hydraulic pressure using a piston which is operated by means of an electrical signal that is output corresponding to a displacement of a brake pedal, and including a first pressure chamber provided at one side of the piston being movably accommodated inside a cylinder block and connected to one or more wheel cylinders, and a second pressure chamber provided at the other side of the piston and connected to one or more wheel cylinders, a first hydraulic flow path configured to communicate with the first pressure chamber, a second hydraulic flow path configured to branch from the first hydraulic flow path, a third hydraulic flow path configured to branch from the first hydraulic flow path, a fourth hydraulic flow path configured to communicate with the second pressure chamber, a fifth hydraulic flow path configured to branch from the fourth hydraulic flow path and connected to the second hydraulic flow path, a sixth hydraulic flow path configured to branch from the fourth hydraulic flow path and connected to the third hydraulic flow path, a first hydraulic circuit including first and second branching flow paths which branch from the second hydraulic flow path and are connected to two wheel cylinders, respectively, and a second hydraulic circuit including third and fourth branching flow paths which branch from the third hydraulic flow path and are connected to two wheel cylinders, respectively. <CIT> relates to a brake device for motor vehicles which has a master brake cylinder for generating brake pressure at at least one wheel brake. To be able to vary the brake pressure at particular wheel brakes individually, a pressure modulation cylinder having a plurality of chambers is provided between the master brake cylinder and the wheel brakes, a first chamber being connected via a first fluid line to the master brake cylinder, and a second chamber being connected via a second fluid line to the at least one wheel brake.

An electronic brake system requires high safety, since it greatly affects a safety of vehicle. Accordingly, a separate winding motor has been recently employed in an electronic brake system.

In the electronic brake system using the separate winding motor, when an error occurs in one system of a motor, only half of the motor performance is capable of being used. However, because a vehicle driven by the motor is not changed, more current is used to achieve a similar level of performance, causing a risk of excessive motor heat, and the like.

To prevent the above, a larger size motor is required to be designed considering a failure of one of the systems. However, a large motor may lead to a difficulty in packaging and integration with an existing motor.

An aspect of the invention provides an electronic brake system and a control method thereof that may miniaturize a motor as well as stably secure a braking performance even when a motor performance is reduced.

According to a first aspect of the present invention, there is provided an electronic brake system including: a motor comprising a first winding and a second winding; a piston coupled to the motor through a power transmission member; a cylinder configured to accommodate the piston, and comprising a first chamber and a second chamber partitioned by the piston; a flow path coupled to the first chamber and the second chamber; a control valve provided on the flow path; a first inverter configured to supply a current to the first winding; a second inverter configured to supply a current to the second winding; and a processor configured to control the first inverter, the second inverter and the control valve, based on an output of a pedal displacement sensor, wherein the processor is configured to open the control valve based on identifying a failure of at least one of the first winding, the second winding, the first inverter or the second inverter and wherein, when the failure of the at least one of the first winding, the second winding, the first inverter or the second inverter is not identified, the processor is configured to close the control valve.

Preferably, a first current sensor is configured to detect a current supplied to the first winding; and a second current sensor configured to detect a current supplied to the second winding.

In a preferred embodiment of the present invention, the processor is configured to identify the failure of the at least one of the first winding, the second winding, the first inverter or the second inverter based on an output of the first current sensor and an output of the second current sensor.

In another preferred embodiment of the present invention, the processor is also configured to: control the second inverter to drive the motor based on identifying the failure of at least one of the first winding or the first inverter, and control the first inverter to drive the motor based on identifying the failure of at least one of the second winding or the second inverter.

In a still another preferred embodiment of the present invention, the processor is configured to control the motor so that at least a portion of a hydraulic pressure of the first chamber is provided to the second chamber while the control valve is open.

According to another aspect of the present invention, there is provided an electronic brake system further comprising a first hydraulic circuit is configured to control a hydraulic pressure transferred from the first chamber to a first wheel cylinder; and a second hydraulic circuit configured to control a hydraulic pressure transferred from the first chamber to a second wheel cylinder.

In a preferred embodiment of the present invention, the motor further comprises a stator and a rotor, and the first winding and the second winding is alternately arranged on the stator.

According to still another aspect of the present invention, there is provided a control method of an electronic brake system comprising a motor comprising a first winding and a second winding, a piston configured to be connected to the motor through a power transmission member, a cylinder configured to accommodate the piston and comprising a first chamber and a second chamber partitioned by the piston, a flow path configured to connect the first chamber and the second chamber, a control valve provided on the flow path, a first inverter configured to supply a current to the first winding; and a second inverter configured to supply a current to the second winding, the control method comprising: controlling the first inverter, the second inverter and the control valve based on an output of a pedal displacement sensor; identifying whether at least one of the first winding, the second winding, the first inverter or the second inverter fails; and opening the control valve based on identifying a failure of the at least one of the first winding, the second winding, the first inverter or the second inverter wherein when the failure of the at least one of the first winding, the second winding, the first inverter or the second inverter is not identified, closing the control valve.

In another embodiment of the present invention the electronic brake system includes: a reservoir in which a pressurized medium is stored; a hydraulic pressure supply device including a first pressure chamber provided in front of a hydraulic piston and a second pressure chamber provided at a rear of the hydraulic piston, and configured to generate a hydraulic pressure by moving the hydraulic piston forward or backward; a hydraulic control unit configured to control a flow of the hydraulic pressure transferred to a wheel cylinder from the hydraulic pressure supply device; and a controller configured to control the hydraulic pressure supply device and the hydraulic control unit, wherein the hydraulic pressure supply device includes a motor having a plurality of separate system windings for moving the hydraulic piston, and a control valve configured to open and close a flow path that communicates the first pressure chamber and the second pressure chamber, and when a portion of the plurality of separate system windings of the motor fails, the controller is configured to open the control valve to push the hydraulic piston so that a portion of a hydraulic pressure discharged from a pressure chamber is transferred to another pressure chamber.

According to one embodiment of the present invention the motor includes a first system stator winding driven by a first inverter and a second system stator winding driven by a second inverter.

According to another embodiment of the present invention the electronic brake system includes: a first current sensor configured to detect a current supplied to the first system stator winding from the first inverter, and a second current sensor configured to detect a current supplied to the second system stator winding from the second inverter.

According to one embodiment of the present invention the controller is configured to determine a failure of the first system stator winding based on a first system stator winding current detected by the first current sensor, and a failure of the second system stator winding based on a second system stator winding current detected by the second current sensor.

According to another embodiment of the present invention the controller is configured to cut off a current input to a malfunctioning system stator winding.

According to another embodiment of the present invention the electronic brake system includes: a reservoir in which a pressurized medium is stored; a hydraulic pressure supply device including a first pressure chamber provided in front of a hydraulic piston and a second pressure chamber provided at a rear of the hydraulic piston, and configured to generate a hydraulic pressure by moving the hydraulic piston forward or backward; a hydraulic control unit configured to control a flow of the hydraulic pressure transferred to a wheel cylinder from the hydraulic pressure supply device; and a controller configured to control the hydraulic pressure supply device and the hydraulic control unit, wherein the hydraulic pressure supply device includes a motor having a first system stator winding driven by a first inverter and a second system stator winding driven by a second inverter, and a control valve configured to open and close a flow path that communicates the first pressure chamber and the second pressure chamber, and when the first system stator winding or the second system stator winding fails during a normal braking mode, the controller is configured to switch to a safe braking mode for opening the control valve to push the hydraulic piston, so that a portion of a hydraulic pressure discharged from a pressure chamber is transferred to another pressure chamber.

According to still another embodiment of the present invention, the control method of an electronic brake system includes a reservoir in which a pressurized medium is stored, a hydraulic pressure supply device including a first pressure chamber provided in front of a hydraulic piston and a second pressure chamber provided at a rear of the hydraulic piston and configured to generate a hydraulic pressure by moving the hydraulic piston forward or backward, a hydraulic control unit configured to control a flow of the hydraulic pressure transferred to a wheel cylinder from the hydraulic pressure supply device, and a controller configured to control the hydraulic pressure supply device and the hydraulic control unit, wherein the hydraulic pressure supply device includes a motor having a plurality of separate system windings for moving the hydraulic piston and a control valve configured to open and close a flow path that communicates the first pressure chamber and the second pressure chamber, the control method including: determining whether a portion of the plurality of system windings of the motor fails, and when the portion of the plurality of system windings fails, opening the control valve to push the hydraulic piston, so that a portion of a hydraulic pressure discharged from a pressure chamber is transferred to another pressure chamber.

According to an aspect of the invention, an electronic brake system and a control method thereof can miniaturize a motor as well as stably secure a braking performance even when a motor performance is reduced due to a partial failure of the motor.

Like reference numerals throughout the specification denote like elements. Also, this specification does not describe all the elements according to embodiments of the invention, and descriptions well-known in the art to which the invention pertains or overlapped portions are omitted. The terms such as "~part", "~member", "~module", "~block", and the like may refer to at least one process processed by at least one hardware or software. According to embodiments, a plurality of "~part", "~member", "~module", "~block" may be embodied as a single element, or a single of "~part", "~member", "~module", "~block" may include a plurality of elements.

It will be understood that when an element is referred to as being "connected" to another element, it can be directly or indirectly connected to the other element, wherein the indirect connection includes connection via a wireless communication network.

It will be understood that the term "include" when used in this specification, specifies the presence of stated elements, but do not preclude the presence or addition of one or more other elements.

It will be understood that when it is stated in this specification that a member is located "on" another member, not only a member may be in contact with another member, but also still another member may be present between the two members.

It is to be understood that the singular forms are intended to include the plural forms as well, unless the context clearly dictates otherwise.

Reference numerals used for method steps are just used for convenience of explanation, but not to limit an order of the steps. Thus, unless the context clearly dictates otherwise, the written order may be practiced otherwise.

<FIG> is a hydraulic circuit diagram illustrating an electronic brake system according to an embodiment.

Referring to <FIG>, the electronic brake system may include a master cylinder <NUM> that pressurizes and discharges a pressurized medium accommodated therein by an operation of a brake pedal <NUM>, a reservoir <NUM> which is connected to a upper side of the master cylinder <NUM> and stores the pressurized medium, wheel cylinders <NUM> provided in respective wheels RR, RL, FR and FL, a hydraulic pressure supply device <NUM> operated by an electrical signal corresponding to a displacement of the brake pedal <NUM> to generate a hydraulic pressure and supply the generated hydraulic pressure to each of the wheel cylinders <NUM> provided in the respective wheels RR, RL, FR and FL, and a hydraulic control unit <NUM> that controls a flow of the hydraulic pressure transferred to each of the wheel cylinders <NUM> by the hydraulic pressure supply device <NUM>.

The hydraulic pressure supply device <NUM> may be provided to receive an electrical signal corresponding to a driver's braking intention from a pedal displacement sensor (PTS) detecting a displacement of the brake pedal <NUM> and generate a hydraulic pressure of the pressurized medium through a mechanical operation.

The hydraulic pressure supply device <NUM> may include a hydraulic pressure providing unit <NUM> that provides a pressure of the pressurized medium transferred to each of the wheel cylinders <NUM>, a motor-driven actuator <NUM> that operates the hydraulic pressure providing unit <NUM> using a motor <NUM>, and a plurality of control valves <NUM> that control the flow of the hydraulic pressure.

The hydraulic pressure providing unit <NUM> may include a cylinder block <NUM> provided to accommodate the pressurized medium, a hydraulic piston <NUM> accommodated in the cylinder block <NUM>, and a drive shaft <NUM> that transfers power output from the motor-driven actuator <NUM> to the hydraulic piston <NUM>. The cylinder block <NUM> may include a first pressure chamber <NUM> positioned in front of the hydraulic piston <NUM> and a second pressure chamber <NUM> positioned at a rear of the hydraulic piston <NUM>.

The plurality of control valves <NUM> may include first to fourth control valves <NUM>, <NUM>, <NUM> and <NUM>.

The first to third control valves <NUM>, <NUM> and <NUM> may control a flow of the pressurized medium transferred to the hydraulic control unit <NUM> from the first pressure chamber <NUM> and/or the second pressure chamber <NUM> or a flow of the pressurized medium between the first pressure chamber <NUM> and the second pressure chamber <NUM>, by a formation of flow paths depending on an opening and closing of valves. For example, the first to third control valves <NUM>, <NUM> and <NUM> may be provided as a normally closed type solenoid valve that operates to be open when an on-driving signal is received from a controller <NUM> in a normally closed state.

The fourth control valve <NUM> may control a flow of the pressurized medium between the second pressure chamber <NUM> and the reservoir <NUM>. For example, the fourth control valve <NUM> may be provided as a normally open type solenoid valve that operates to be closed when an on-driving signal is received from the controller <NUM> in a normally open state.

Types and the number of the plurality of control valves <NUM> may vary depending on a structure of flow paths.

The hydraulic pressure supply device <NUM> may include a motor pump or a high pressure accumulator instead of the hydraulic pressure providing unit <NUM> and the motor-driven actuator <NUM>.

The hydraulic control unit <NUM> may include a first hydraulic circuit <NUM> that controls the flow of the pressurized medium transferred to first and second wheel cylinders <NUM> and <NUM> among the four wheel cylinders, and a second hydraulic circuit <NUM> that controls the flow of the pressurized medium transferred to third and fourth wheel cylinders <NUM> and <NUM>.

For example, the first hydraulic circuit <NUM> may control a braking force of the front right wheel FR and the rear left wheel RL. The second hydraulic circuit <NUM> may control a braking force of the rear right wheel RR and the front left wheel FL.

The hydraulic control unit <NUM> may include an inlet valve provided at a front end of each of the wheel cylinders <NUM>, <NUM>, <NUM> and <NUM> to control the hydraulic pressure, and an outlet valve branched between the inlet valve and the wheel cylinders <NUM>, <NUM>, <NUM> and <NUM> and connected to the reservoir <NUM>. The hydraulic pressure supply device <NUM> and a front end of the inlet valve of the first hydraulic circuit <NUM> may be connected to each other, and the hydraulic pressure supply device <NUM> and a front end of the inlet valve of the second hydraulic circuit <NUM> may be connected to each other. The hydraulic pressure generated and provided from the hydraulic pressure supply device <NUM> may be supplied to each of the first hydraulic circuit <NUM> and the second hydraulic circuit <NUM>.

<FIG> is a control block diagram illustrating an electronic brake system according to an embodiment.

Referring to <FIG>, the electronic brake system may include the controller <NUM> that performs an overall control.

The controller <NUM> is electrically connected to a pedal displacement sensor (PTS), a first current sensor <NUM>, a second current sensor <NUM>, a first inverter <NUM>, a second inverter <NUM> and the control valves <NUM>, <NUM>, <NUM> and <NUM>.

The pedal displacement sensor (PTS) may detect an operation and a displacement of the brake pedal <NUM>.

The first current sensor <NUM> may detect current supplied from the first inverter <NUM> to stator windings (221a : U1, V1 and W1) of a first system of the motor <NUM>.

The second current sensor <NUM> may detect current supplied from the second inverter <NUM> to stator windings (221b : U2, V2 and W2) of a second system of the motor <NUM>.

The first inverter <NUM> may supply current to the stator windings (U1, V1 and W1) of the first system of the motor <NUM>.

The second inverter <NUM> may supply current to the stator windings (U2, V2 and W2) of the second system of the motor <NUM>.

The first inverter <NUM> and the second inverter <NUM> may drive the motor <NUM> by converting a DC voltage provided from a battery of a vehicle into a three-phase AC voltage in a form of a pulse having an arbitrary variable frequency through pulse width modulation (PWM). The first inverter <NUM> and the second inverter <NUM> may include a plurality of power switching elements and a plurality of diodes. For example, each of the first inverter <NUM> and the second inverter <NUM> may include six power switching elements Q1 to Q6 and six diodes D1 to D6. The six power switching elements Q1 to Q6 may be paired in series and connected to the stator windings (U1, V1 and W1) of the first system of the motor <NUM> or the stator windings (U2, V2 and W2) of the second system of the motor <NUM>, respectively. The first inverter <NUM> and the second inverter <NUM> may convert the current, provided from the battery, to AC from DC by turning on or off each of the power switching elements according to a control signal of the controller <NUM>, thereby supplying the current to the stator windings (U1, V1 and W1) of the first system of the motor <NUM> and/or the stator windings (U2, V2 and W2) of the second system of the motor <NUM>.

The controller <NUM> may perform an overall control of the electronic brake system.

The controller <NUM> may control the hydraulic pressure supply device <NUM> and the hydraulic control unit <NUM>.

The controller <NUM> may be referred to as an electronic control unit (ECU).

The controller <NUM> may include a processor <NUM> and a memory <NUM>.

The memory <NUM> may store a program for processing or controlling the processor <NUM> and various data for operating the electronic brake system.

The memory <NUM> may include a volatile memory such as a static random access memory (S-RAM) and dynamic random access memory (D-RAM), and a non-volatile memory such as a flash memory, a read only memory (ROM), an erasable programmable read only memory (EPROM), and the like.

The processor <NUM> may control overall operations of the electronic brake system.

The processor <NUM> may receive brake pedal displacement information through the pedal displacement sensor (PTS).

The processor <NUM> may receive current information of the stator windings (U1, V1 and W1) of the first system detected through the first current sensor <NUM>.

The processor <NUM> may receive current information of the stator windings (U2, V2 and W2) of the second system detected through the second current sensor <NUM>.

The processor <NUM> may diagnose the current information of the stator windings (U1, V1 and W1) of the first system, detected through the first current sensor <NUM>, and thereby may determine whether a temporary failure or permanent failure such as disconnection or short circuit occurs in the stator windings (U1, V1 and W1) of the first system. The processor <NUM> may determine a failure of the first inverter <NUM>.

The processor <NUM> may diagnose the current information of the stator windings (U2, V2 and W2) of the second system, detected through the second current sensor <NUM>, and thereby may determine whether a temporary failure or permanent failure such as disconnection or short circuit occurs in the stator windings (U2, V2 and W2) of the second system. The processor <NUM> may determine a failure of the second inverter <NUM>.

The processor <NUM> may control operations of the first inverter <NUM> and/or the second inverter <NUM>.

The processor <NUM> may operate the motor <NUM> by outputting a motor command signal to the first inverter <NUM> to supply the current to the stator windings (U1, V1 and W1) of the first system of the motor <NUM>.

The processor <NUM> may operate the motor <NUM> by outputting a motor command signal to the second inverter <NUM> to supply the current to the stator windings (U2, V2 and W2) of the second system of the motor <NUM>. The motor command signal may include a target pressure requested by a driver and a difference in requested target pressure between a previous driver and a current driver.

The processor <NUM> may control operations of each electronic valve by outputting a valve command signal to each of the electronic valves of the electronic brake system including the control valves <NUM>, <NUM>, <NUM> and <NUM>.

<FIG> illustrates a configuration of a motor of an electronic brake system according to an embodiment.

Referring to <FIG>, the motor <NUM> may include a stator <NUM> disposed outside and a rotor <NUM> disposed inside.

The stator <NUM> may include a housing <NUM>, a stator core <NUM> fixed to an inner circumferential side of the housing <NUM>, and three-phase (U,V, W) stator windings (coil) <NUM> wound on the stator core <NUM>.

In the stator core <NUM>, a yoke portion <NUM> and a plurality of teeth <NUM> protruding inward from the yoke portion <NUM> may be formed. For example, twelve teeth <NUM> may be provided in the motor <NUM>. A slot <NUM> may be formed between each of the teeth <NUM>. The motor <NUM> may have twelve slots <NUM>. The stator winding <NUM> wound around the tooth <NUM> may be accommodated in the slot <NUM>.

The rotor <NUM> may be positioned inside of the stator <NUM>. The rotor <NUM> may include a rotation shaft <NUM>, a rotor core <NUM> and a magnet <NUM>. The rotation shaft <NUM>, the rotor core <NUM> and the magnet <NUM> may be disposed on a same axis.

The rotor core <NUM> may be disposed around the rotation shaft <NUM>. The magnet <NUM> is fixed around an outer circumference of the rotor core <NUM>. Fourteen magnets <NUM> are disposed along the outer circumference of the rotor core <NUM>. The motor <NUM> may be a motor having fourteen poles and twelve slots.

The motor <NUM> may be driven by two independent energized systems.

The stator windings <NUM> of the motor <NUM> are divided into two independent systems and wired.

The numbers <NUM> and <NUM> after U, V and W shown in <FIG> indicate a system (a first system or a second system) to which the stator winding <NUM> belongs.

The stator windings <NUM> of the first system may be connected in a Y configuration. The stator windings <NUM> of the second system may also be connected in a Y configuration.

The stator windings <NUM> of the two systems may be alternately arranged in a circumferential direction. In phase windings of the same system may be arranged to face each other. The stator windings of the first system (first group three-phase coils) and the stator windings of the second system (second group three-phase coils) of the stator windings <NUM> may be alternately arranged in an order of U1a(+), W2b(+), W1b(-), V2b(-), V1b(+), U2b(+), U1b(-), W2a(-), W1a(+), V2a(+), V1a(-) and U2a(-).

<FIG> illustrates a failure of a first system of a motor of an electronic brake system according to an embodiment.

Referring to <FIG>, it is illustrated that, in the motor <NUM>, the stator windings (U1a(+), W1b(-), V1b(+), U1b(-), W1a(+), V1a(-)) of the first system fail, and the stator windings (W2b(+), V2b(-), U2b(+), W2a(-), V2a(+), U2a(-)) of the second system are normal.

When the first system fails, the processor <NUM> may operate the motor <NUM> by supplying current to the stator windings (W2b(+), V2b(-), U2b(+), W2a(-), V2a(+), U2a(-)) of the second system through the second inverter <NUM>. That is, the current may be supplied to only the stator windings (W2b(+), V2b(-), U2b(+), W2a(-), V2a(+), U2a(-)) of the second system which is normal, without supplying the current to the stator windings (U1a(+), W1b(-), V1b(+), U1b(-), W1a(+), V1a(-)) of the first system which is malfunctioning. Accordingly, the rotor <NUM> of the motor <NUM> may be rotated only by the stator windings (W2b(+), V2b(-), U2b(+), W2a(-), V2a(+), U2a(-)) of the second system.

<FIG> illustrates a failure of a second system of a motor of an electronic brake system according to an embodiment.

Referring to <FIG>, it is illustrated that, in the motor <NUM>, the stator windings (U1a(+), W1b(-), V1b(+), U1b(-), W1a(+), V1a(-)) of the first system are normal, and the stator windings (W2b(+), V2b(-), U2b(+), W2a(-), V2a(+), U2a(-)) of the second system fail.

When the second system fails, the processor <NUM> may operate the motor <NUM> by supplying current to the stator windings (U1a(+), W1b(-), V1b(+), U1b(-), W1a(+), V1a(-)) of the first system through the first inverter <NUM>. That is, the current may be supplied to only the stator windings (U1a(+), W1b(-), V1b(+), U1b(-), W1a(+), V1a(-)) of the first system which is normal, without supplying the current to the stator windings (W2b(+), V2b(-), U2b(+), W2a(-), V2a(+), U2a(-)) of the second system which is malfunctioning. Accordingly, the rotor <NUM> of the motor <NUM> may be rotated only by the stator windings (U1a(+), W1b(-), V1b(+), U1b(-), W1a(+), V1a(-)) of the first system.

As described above, because the motor includes two independent systems, the first system and the second system cooperate to rotate the rotor in a normal state, and when one of the two systems fails, the rotor may be rotated only the stator windings of the other system. Accordingly, even when one of the systems fails, the other system may continue to function, and thus the motor may be continuously driven by reducing a motor performance without stopping the motor.

However, when one of the systems fails, the motor performance may be reduced in half because the motor is required to be driven using only the normal system. To achieve a similar level of performance as before the motor failure even in the above-described state, more current is required to be supplied to the stator windings of normal system, causing an excessive motor heat. Conventionally, a larger size motor has been designed considering a failure of one system to prevent the above, but a large motor may lead to a difficulty in packaging and integration with an existing motor.

According to an embodiment, when one of the systems of the motor <NUM> fails during braking control, the electronic brake system may drive the motor <NUM> by using only the normal system, and increase a hydraulic pressure discharged from the first pressure chamber <NUM> or the second pressure chamber <NUM> by communicating the first pressure chamber <NUM> and the second pressure chamber <NUM>. Accordingly, a deterioration of the motor performance due to a failure of one of the systems of the motor may be compensated for by increasing the hydraulic pressure discharged from the pressure chamber, and thereby may stably secure a braking performance of system. The first pressure chamber <NUM> and the second pressure chamber <NUM> may communicate with each other by opening control valves provided on a flow path connecting the first pressure chamber <NUM> and the second pressure chamber <NUM>. By transferring a portion of the hydraulic pressure discharged from the first pressure chamber <NUM> to the second pressure chamber <NUM> to be used to push the hydraulic piston <NUM>, the hydraulic pressure discharged from the first pressure chamber <NUM> may be increased. Also, by transferring a portion of the hydraulic pressure discharged from the second pressure chamber <NUM> to the first pressure chamber <NUM> to be used to push the hydraulic piston <NUM>, the hydraulic pressure discharged from the second pressure chamber <NUM> may be increased.

<FIG> illustrates a state where an electronic brake system according to an embodiment performs a normal braking mode.

Once a driver operates the brake pedal <NUM>, the controller <NUM> may operate the hydraulic pressure supply device <NUM> depending on a displacement of the brake pedal <NUM>.

The controller <NUM> may open the first control valve <NUM> and the second control valve <NUM>, and drive the motor <NUM> by supplying current to stator windings (U1a(+), W1b(-), V1b(+), U1b(-), W1a(+), V1a(-)) of the first system through the first inverter <NUM> and supplying current to the stator windings (W2b(+), V2b(-), U2b(+), W2a(-), V2a(+), U2a(-)) of the second system through the second inverter <NUM>. As such, the controller <NUM> may perform a normal braking mode that opens the first control valve <NUM> and the second control valve <NUM> and drives the motor <NUM>. The third control valve <NUM> may be in a closed state in the normal braking mode. That is, the first pressure chamber <NUM> and the second pressure chamber <NUM> may not communicate with each other in the normal braking mode.

As the controller <NUM> performs the normal braking mode, the hydraulic piston <NUM> is moved by an operation of the motor <NUM>, generating a hydraulic pressure in the first pressure chamber <NUM>. The hydraulic pressure discharged from the first pressure chamber <NUM> may be transferred to the first hydraulic circuit <NUM> and the second hydraulic circuit <NUM> of the hydraulic control unit <NUM> through the first control valve <NUM> and the second control valve <NUM> which are switched to the open state. The hydraulic pressure transferred to the first hydraulic circuit <NUM> and the second hydraulic circuit <NUM> may be transferred to each of the wheel cylinders <NUM> through inlet valves, generating a braking force to each vehicle wheel.

<FIG> illustrates a state where an electronic brake system according to an embodiment performs a safe braking mode.

Referring to <FIG>, when one of the first and second systems of the motor <NUM> fails during a normal braking mode, the controller <NUM> may switch the normal braking mode to a safe braking mode to additionally open the third control valve <NUM>, thereby communicating the first pressure chamber <NUM> and the second pressure chamber <NUM>. In this instance, the fourth control valve <NUM> may be in a closed state. Accordingly, by transferring a portion of the hydraulic pressure discharged from the first pressure chamber <NUM> to the second pressure chamber <NUM> to be used to push the hydraulic piston <NUM>, the hydraulic pressure discharged from the first pressure chamber <NUM> may be increased.

When one of the systems of the motor fails, a motor performance may be reduced in half because the motor is required to be driven using only the normal system. Accordingly, the hydraulic pressure discharged from the first pressure chamber <NUM> may be decreased. However, by switching the normal braking mode to the safe braking mode and communicating the first pressure chamber <NUM> and the second pressure chamber <NUM>, the portion of the hydraulic pressure discharged from the first pressure chamber <NUM> may be transferred to the second pressure chamber <NUM> to be used to push the hydraulic piston <NUM>, thereby increasing the hydraulic pressure discharged from the first pressure chamber <NUM>. Accordingly, a deterioration of the motor performance due to a failure of one of the systems of the motor may be compensated for by increasing the hydraulic pressure discharged from the pressure chamber, and thus a similar braking performance as before the motor failure may be stably secured, without supplying more current to stator windings of the normal system.

<FIG> illustrates a control method of an electronic brake system according to an embodiment.

Referring to <FIG>, during braking control, the controller <NUM> may detect current of the stator windings (U1, V1 and W1) of the first system detected through the first current sensor <NUM> (<NUM>), and also detect current of the stator windings (U2, V2 and W2) of the second system detected through the second current sensor <NUM> (<NUM>).

The controller <NUM> may determine whether the first system or the second system fails based on information about the detected current (<NUM>).

When no failure of the first system or the second system is determined, the controller <NUM> may maintain a normal braking mode as a braking mode (<NUM>). In the normal braking mode, the first control valve <NUM> and the second control valve <NUM> are open, the motor <NUM> is driven, and the third control valve <NUM> may be in a closed state in order not to communicate the first pressure chamber <NUM> and the second pressure chamber <NUM>.

On the other hand, when the first system or the second system fails, the controller <NUM> may switch the normal braking mode to a safe braking mode (<NUM>). In the safe braking mode, the third control valve <NUM> is additionally open in addition to the normal braking mode, and thus the first pressure chamber <NUM> and the second pressure chamber <NUM> communicate with each other. In this instance, the fourth control valve <NUM> may be in a closed state.

As such, when one of the systems of the motor fails, by switching the normal braking mode to the safe braking mode and communicating the first pressure chamber <NUM> and the second pressure chamber <NUM>, a portion of a hydraulic pressure discharged from the first pressure chamber <NUM> may be transferred to the second pressure chamber <NUM> to be used to push the hydraulic piston <NUM>, thereby increasing the hydraulic pressure discharged from the first pressure chamber <NUM>. Accordingly, a deterioration of the motor performance due to a failure of one of the systems of the motor may be compensated for by increasing the hydraulic pressure discharged from the pressure chamber, and thus a similar braking performance as before the motor failure may be stably secured, without supplying more current to stator windings of the normal system.

<FIG> is a hydraulic circuit diagram illustrating an electronic brake system according to another embodiment.

Referring to <FIG>, the hydraulic pressure supply device <NUM> may include a plurality of control valves <NUM>.

The plurality of control valves <NUM> may include first to third control valves <NUM>, <NUM> and <NUM>.

The first and second control valves <NUM> and <NUM> may control a flow of a pressurized medium transferred to the hydraulic control unit <NUM> from the first pressure chamber <NUM> and/or the second pressure chamber <NUM> or a flow of the pressurized medium between the first pressure chamber <NUM> and the second pressure chamber <NUM>, by a formation of flow paths depending on an opening and closing of valves. For example, the first and second control valves <NUM> and <NUM> may be provided as a normally closed type solenoid valve that operates to be open when an on-driving signal is received from the controller <NUM> in a normally closed state.

The third control valve <NUM> may control a flow of the pressurized medium between the second pressure chamber <NUM> and the reservoir <NUM>. For example, the third control valve <NUM> may be provided as a normally open type solenoid valve that operates to be closed when an on-driving signal is received from the controller <NUM> in a normally open state.

<FIG> illustrates a state where an electronic brake system according to another embodiment performs a normal braking mode.

The controller <NUM> may open the first control valve <NUM> and close the second control valve <NUM>. Also, the controller <NUM> may drive the motor <NUM> by supplying current to stator windings (U1a(+), W1b(-), V1b(+), U1b(-), W1a(+), V1a(-)) of a first system through the first inverter <NUM> and supplying current to the stator windings (W2b(+), V2b(-), U2b(+), W2a(-), V2a(+), U2a(-)) of a second system through the second inverter <NUM>. As such, the controller <NUM> may perform a normal braking mode that drives the motor <NUM> and closes one of the first control valve <NUM> and the second control valve <NUM> (for example, opens the first control valve <NUM> and closes the second control valve <NUM>). The third control valve <NUM> may be in a closed state in the normal braking mode. That is, the first pressure chamber <NUM> and the second pressure chamber <NUM> may not communicate with each other in the normal braking mode.

As the controller <NUM> performs the normal braking mode, the hydraulic piston <NUM> is moved by an operation of the motor <NUM>, generating a hydraulic pressure in the first pressure chamber <NUM>. The hydraulic pressure discharged from the first pressure chamber <NUM> may be transferred to the first hydraulic circuit <NUM> and the second hydraulic circuit <NUM> of the hydraulic control unit <NUM> by flowing in a direction of an arrow. The hydraulic pressure transferred to the first hydraulic circuit <NUM> and the second hydraulic circuit <NUM> may be transferred to each of the wheel cylinders <NUM> through inlet valves, generating a braking force to each vehicle wheel.

<FIG> illustrates a state where an electronic brake system according to another embodiment performs a safe braking mode.

Referring to <FIG>, when one of the first and second systems of the motor <NUM> fails during a normal braking mode, the controller <NUM> may switch the normal braking mode to a safe braking mode that opens both the first control valve <NUM> and the second control valve <NUM>, thereby communicating the first pressure chamber <NUM> and the second pressure chamber <NUM>. Accordingly, by transferring a portion of a hydraulic pressure discharged from the first pressure chamber <NUM> to the second pressure chamber <NUM> to be used to push the hydraulic piston <NUM>, the hydraulic pressure discharged from the first pressure chamber <NUM> may be increased.

Claim 1:
An electronic brake system, comprising:
a motor (<NUM>);
a piston (<NUM>) coupled to the motor through a power transmission member;
a cylinder (<NUM>) configured to accommodate the piston (<NUM>), and comprising a first chamber (<NUM>) and a second chamber (<NUM>) partitioned by the piston (<NUM>);
a flow path coupled to the first chamber (<NUM>) and the second chamber (<NUM>);
a control valve (<NUM>, <NUM>, <NUM>) provided on the flow path;
a pedal displacement sensor (PTS); and
a processor (<NUM>),
the electronic brake system being characterised in that:
the motor (<NUM>) comprises a first winding (U1, V1 and W1) and a second winding (U2, V2 and W2);
the electronic brake system further comprises:
a first inverter (<NUM>) configured to supply a current to the first winding (U1, V1 and W1);
a second inverter (<NUM>) configured to supply a current to the second winding (U2, V2 and W2); and
the processor (<NUM>) is configured to control the first inverter (<NUM>), the second inverter (<NUM>) and the control valve (<NUM>, <NUM>, <NUM>), based on an output of the pedal displacement sensor (PTS),
wherein the processor (<NUM>) is configured to open the control valve (<NUM>, <NUM>, <NUM>) based on identifying a failure of at least one of the first winding (U1, V1 and W1), the second winding (U2, V2 and W2), the first inverter (<NUM>) or the second inverter (<NUM>) and
wherein, when the failure of the at least one of the first winding (U1, V1 and W1), the second winding (U2, V2 and W2), the first inverter (<NUM>) or the second inverter (<NUM>) is not identified, the processor (<NUM>) is configured to close the control valve (<NUM>, <NUM>, <NUM>).