Electric booster for autonomous vehicles with dual actuators

Abstract

An electric brake booster for an autonomous driving vehicle is provided. The electric brake booster includes a main body, accommodating a power cylinder that generates brake pressure in an autonomous driving / braking mode and a master cylinder that generates brake pressure in a manual driver braking mode. A drive shaft is axially movable in the power cylinder and is connected to a piston. A first motor is connected to a first side of the drive shaft and provides a driving force to the drive shaft. A second motor is connected to a second side of the drive shaft and provides a driving force to the drive shaft in the same direction as the driving force provided from the first motor. A controller determines whether the first motor or the second motor is operating normally, and operates the first motor and the second motor simultaneously or separately based on the magnitude of the pressure in the power cylinder or whether emergency braking occurs.

Description

Technical Field

[0001] The present invention relates to an electric brake booster for an autonomous vehicle having dual actuators, and more particularly, to an electric brake booster that reduces the capacity of the actuators by cooperatively operating two actuators that generate brake pressure in the autonomous vehicle. Background Art

[0002] Different from the mechanical or hydraulic booster system in the prior art, the electric brake booster system is a brake system that uses an electric motor or an actuator. In the electric brake booster system, the piston is advanced by the rotation of the electric motor, thereby forming brake pressure in the master cylinder.

[0003] Typically, in an electric brake booster system, when a driver engages a brake pedal, a pedal force sensor detects the driver's pedal force, and an electronic controller (ECU) operates a motor of a booster based on a value detected by the pedal force sensor and transmits the force to a master cylinder. The master cylinder transmits hydraulic pressure to wheel brakes based on the force transmitted from the booster.

[0004] Meanwhile, the electric brake booster may include a main actuator and a redundant actuator, thereby forming a redundant brake system. In other words, during normal operation, the redundant brake system generates hydraulic brake pressure only by operating the main actuator (high-output motor), and when the main actuator fails, the redundant brake system generates hydraulic brake pressure by operating the redundant actuator (of the low-output motor). In particular, the high-output motor is used as the main actuator, and the low-output motor is used as the redundant actuator.

[0005] The prior art related to a redundant braking system discloses an electric braking system, comprising: a master cylinder configured to generate braking pressure based on a pedal force applied to a brake pedal; and a redundant control device configured to transmit a fluid pressure generated using an electric motor and a pump to a wheel cylinder arranged in each wheel, wherein, during normal operation of the system, braking pressure is generated by the master cylinder, and when the system is not operating normally, braking pressure is generated by rotating the electric motor (redundant actuator) after operating a flow control valve.

[0006] However, since the high-output motor is used as the main actuator, the cost, weight and size increase due to the increase in the capacity of the motor, which is disadvantageous for packaging. In addition, in the case where the main actuator and the redundant actuator are separately configured in the redundant braking system, the system is complicated and inefficient. In addition, in the case where the redundant braking system is operated using only the redundant actuator, since the low-output motor is used as the redundant actuator, the performance is degraded compared with the main actuator. Summary of the invention

[0007] The present invention provides a new type of invention that reduces the capacity of the motor by achieving one package of symmetry of the main actuator and the redundant actuator and by operating the main actuator and the redundant actuator simultaneously.

[0008] In order to achieve the above-mentioned objectives, the present invention provides an electric brake booster for an autonomous driving vehicle with a dual actuator, which electric brake booster may include: a main body, configured to accommodate a power cylinder for generating brake pressure in an autonomous driving / braking mode and a master cylinder for generating brake pressure in a manual driver braking mode; a drive shaft, which is axially movable in the power cylinder and connected to a piston; a first motor, connected to a first side of the drive shaft, and configured to provide a driving force to the drive shaft; a second motor, connected to a second side of the drive shaft, and configured to provide a driving force to the drive shaft in the same direction as the driving force provided from the first motor; and a controller, configured to determine whether the first motor or the second motor is operating normally, and configured to operate the first motor and the second motor simultaneously or separately based on the magnitude of the pressure in the power cylinder or based on whether emergency braking occurs.

[0009] Any one of the first motor and the second motor may have a hollow structure to accommodate the piston and move the piston. The first motor and the second motor may be connected to separate power supplies, and power is supplied to the first motor and the second motor. Motor position sensors may be connected to the first motor and the second motor, respectively, to detect the rotational position of the rotors of the motors. A pressure sensor may be connected to the power cylinder to detect the pressure in the power cylinder.

[0010] The master cylinder and the power cylinder may cross each other, and the first motor and the second motor may be disposed on both sides of the main body, with the master cylinder interposed between the first motor and the second motor. In response to determining that any one of the first motor and the second motor fails, the controller may be configured to operate another normal motor. In response to determining that any one of the first motor and the second motor fails, the controller may be configured to operate another normal motor from a rotation position detected by a motor position sensor.

[0011] In addition, in response to determining that both the first motor and the second motor have failed, the controller can be configured to switch from the automatic driving mode to the manual driver braking mode. When the current situation is not an emergency braking situation or the pressure in the power cylinder is less than a predetermined reference pressure, the controller can be configured to operate only one of the first motor and the second motor. When the current situation is an emergency braking situation or the pressure in the power cylinder is greater than a predetermined reference pressure, the controller can be configured to operate the first motor and the second motor at the same time.

[0012] When the controller distributes the driving force by operating the first motor and the second motor simultaneously, the controller may be configured to distribute the driving force so that at least one motor has a driving force less than its capacity. When the controller distributes the driving force by operating the first motor and the second motor simultaneously, the controller may be configured to distribute the driving force at a predetermined ratio.

[0013] According to the present invention, since the first motor and the second motor can be operated at the same time, the capacity of the motor can be reduced, and since the first motor and the second motor are symmetrically arranged on both sides of the main body, the package can be reduced. According to the present invention, there is an effect of improving the braking performance by operating the dual actuator in the case of emergency braking. In addition, when any one of the first motor and the second motor fails, the delay of the response can be minimized by adjusting the position of the normal motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] These and / or other aspects of the present invention will become apparent and more readily understood through the following description of exemplary embodiments in conjunction with the accompanying drawings:

[0015] Figure 1 is a view schematically showing an overall configuration of an electric brake booster for an autonomous driving vehicle having dual actuators according to an exemplary embodiment of the present invention;

[0016] Figure 2 is a diagram showing an exemplary embodiment of the present invention, Figure 1 A view of the internal structure of the dual actuator shown in; and

[0017] Figure 3 is a flowchart illustrating a process of controlling an electric brake booster for an autonomous driving vehicle with dual actuators according to an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0018] It should be understood that the terms "vehicle" or "vehicle-based" or other similar terms used in this document generally include common motor vehicles, such as passenger vehicles including sport utility vehicles (SUVs), buses, trucks, various commercial vehicles, watercraft including various boats and ships, and aircraft, etc., and include hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other alternative fuel vehicles (e.g., fuels obtained from resources other than petroleum).

[0019] Although the exemplary embodiments are described as using multiple units to perform the exemplary processes, it should be understood that the exemplary processes can also be performed by one or more modules. In addition, it is understood that the term controller / control unit refers to a hardware device including a memory and a processor, and is specifically programmed to perform the processes described herein. The memory is configured to store the modules, and the processor is specifically configured to execute the modules to perform one or more processes described further below.

[0020] The terms used herein are only used to illustrate the purpose of specific embodiments and are not intended to limit the present invention. As used herein, the singular forms "one", "a kind of" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that when used in this specification, the words "include" and / or "comprise" specify the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or their groups. As used herein, the word "and / or" includes any and all combinations of one or more related listed items.

[0021] Unless otherwise specified or apparent from the context, the term "about" as used herein should be understood to be within the normal tolerance range in the art, such as within 2 standard deviations of the mean. "About" can be understood to be within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value. Unless otherwise clear from the context, all numerical values ​​provided herein are modified by the term "about".

[0022] Hereinafter, an exemplary embodiment of an electric brake booster for an autonomous driving vehicle with dual actuators according to the present invention will be described in detail with reference to the accompanying drawings. The terms or words used herein should not be interpreted as limited to the general meaning or the meaning of the dictionary, but should be interpreted as the meaning and concept that conforms to the technical spirit of the present invention based on the principle that the inventor can appropriately define the concept of the term in order to describe his / her own invention in the best way.

[0023] An electric brake booster for an autonomous vehicle with a dual actuator according to an exemplary embodiment of the present invention may include: a booster device configured to switch between an autonomous driving / braking mode or a manual driver braking mode. In the booster device in the manual driver braking mode, when the driver engages the brake pedal 1, the pedal force sensor 2 may be configured to detect the driver's pedal force, and the controller 50 may be configured to operate the booster's motor (not shown) based on the value detected by the pedal force sensor 2, and transmit the boost to the master cylinder 3, and thus to the brake. In an exemplary embodiment of the present invention, the construction of the booster device in the manual driver braking mode may be similar to the construction of a known electric brake booster device.

[0024] In the automatic driving / braking mode, the booster device can be configured to operate the dual actuator based on the braking force required by the automatic driving controller (not shown), and transmit the boost to the power cylinder 20, and thus to the brake. In this specification, the booster device in the automatic driving / braking mode will be described with emphasis. At the same time, the hydraulic pressure generated in each braking mode can be adjusted by valve control of the hydraulic control unit (HCU).

[0025] Figure 1 is a view schematically showing an overall configuration of an electric brake booster for an autonomous driving vehicle having a dual actuator according to an exemplary embodiment of the present invention, and Figure 2 It is shown Figure 1 The structure of the dual actuator is shown in FIG. Figure 1 is a view showing an electric brake booster according to an exemplary embodiment of the present invention when viewed from above.

[0026] Reference Figure 1 According to an exemplary embodiment of the present invention, an electric brake booster for an autonomous driving vehicle with a dual actuator may include: a master cylinder 3 accommodated in a main body 10, a power cylinder 20, a drive shaft 22, a first motor 30, a second motor 40, and a controller 50. The master cylinder 3 may be connected to a brake pedal 1 and may be configured to generate a brake pressure based on a driver's intention. Figure 1 As shown, the master cylinder 3 according to the exemplary embodiment of the present invention may be configured to be arranged along the front-rear direction of the main body 10 .

[0027] The power cylinder 20 may be configured to generate brake pressure based on a control signal corresponding to the braking force required by an autopilot controller (not shown). Figure 1As shown, the power cylinder 20 according to the exemplary embodiment of the present invention can be arranged in the left-right direction of the main body 10. Therefore, in the main body 10, the master cylinder 3 and the power cylinder 20 can be arranged in directions crossing each other. The arrangement of the master cylinder 3 and the power cylinder 20 is not limited, but the master cylinder 3 and the power cylinder 20 can be arranged nearly perpendicular to each other.

[0028] A flow path (a movement path of the fluid) may be formed in the power cylinder 20, and the drive shaft 22 may be inserted into the power cylinder 20. A thread may be formed on the outer circumferential surface of the drive shaft 22, and the drive shaft 22 may be coupled to the piston 24. Therefore, the piston 24 may advance and retract with the rotation of the drive shaft 22, so that hydraulic pressure may be formed or eliminated in the flow path. At the same time, the pressure sensor 7 connected to the flow path may be configured to sense the pressure in the flow path in real time.

[0029] Reference Figure 2 , the first motor 30 can be connected to the first portion of the drive shaft 22, and the second motor 40 can be connected to the second portion of the drive shaft 22. Figure 1 As shown, the first motor 30 and the second motor 40 may be connected to the driving shaft 22 and may be symmetrically disposed on the left and right sides of the main body 10 to integrally form one package.

[0030] Any one of the first motor 30 and the second motor 40 can be configured as a main actuator, and the other of the first motor 30 and the second motor 40 can be configured as a redundant actuator, thereby realizing a redundant braking system. In a redundant braking system, in a case where only the main actuator operates during normal times and the redundant actuator operates during an emergency, the capacity of the main actuator is inevitably increased. When a high-output motor is used as a main actuator, the cost and weight increase due to the increase in size, which is not conducive to packaging, and causes noise, vibration and harshness (NVH) and durability problems due to the asymmetric weight structure. According to an exemplary embodiment of the present invention, the first motor 30 and the second motor 40 can be configured to operate even during normal times (for example, during no fault, emergency, failure, etc.), so due to the symmetrical weight structure, the capacity of the main actuator can be reduced and the above-mentioned problems can be solved.

[0031] In the first motor 30, the first rotor 32 extends outward and is connected to the first end of the drive shaft 22. Therefore, the drive shaft 22 also rotates in the rotation direction of the first rotor 32. A first motor position sensor 35 may be connected to one side of the first motor 30. The first motor position sensor 35 may be configured to detect a rotation position or a rotation angle of the first rotor 32 that changes based on the operation of the first motor 30 in real time.

[0032] The second motor 40 has a hollow structure so that the second rotor 42 is positioned in the motor. The second rotor 42 has a cylindrical shape, and the second side of the drive shaft 22 can be accommodated in the second rotor 42 and connected to the second rotor 42. Specifically, the piston 24 can be formed on the second side of the drive shaft 22, and the outer surface of the piston 24 can be connected to the inner surface of the second rotor 42. Therefore, the drive shaft 22 can also rotate in the rotation direction of the second rotor 42. The second motor position sensor 45 can be connected to one side of the second motor 40. The second motor position sensor 45 can be configured to detect the rotation position or rotation angle of the second rotor 42 that changes based on the operation of the second motor 40 in real time.

[0033] The first rotor 32 and the second rotor 42 may be connected to the same drive shaft 22. Therefore, the rotational positions of the first rotor 32 and the second rotor 42 measured by the first motor position sensor 35 and the second motor position sensor 45 may be detected as equal values. The first motor 30 and the second motor 40 may be connected to separate power supplies, respectively, and powered. Therefore, in the event that there is a problem that power cannot be supplied to any one of the first motor 30 and the second motor 40, the other motor may operate.

[0034] At the same time, the first motor 30 may be selected as the main actuator, and the second motor 40 may be selected as the redundant actuator, or vice versa. Figure 2 The first motor 30 and the second motor 40 shown in the figure may have opposite structures (for example, the first motor 30 may have a hollow structure). In the automatic driving / braking mode, the controller 50 may be configured to determine a specific condition and determine whether to operate the first motor 30 and the second motor 40 based on the specific condition.

[0035] The controller 50 may be configured to determine whether the first motor 30 or the second motor 40 meets the conditions for normal operation. Whether the motor is operating normally (e.g., without fault or error) may be determined by detecting in real time whether the rotational position or rotational angle of the motor changes when current is applied to the motor through the motor position sensors 35 and 45. For example, when the rotational position does not change even when current is applied to the first motor 30, the controller 50 may be configured to determine that the first motor 30 has failed or has failed.

[0036] In response to determining that the first motor 30 and the second motor 40 are normal, the controller 50 can be configured to determine whether the first motor 30 and the second motor 40 meet an emergency braking condition or a pressure condition. In particular, the emergency braking condition or the pressure condition can be determined simultaneously. When an emergency braking situation occurs while the vehicle is traveling in an automatic driving mode, a high braking force may be required. Therefore, in order to meet the braking force, the controller 50 can be configured to operate both the first motor 30 and the second motor 40. The emergency braking condition can be set by detecting a sensed value by the pressure sensor 7.

[0037] In contrast, when the current situation is not an emergency braking situation, the controller may be configured to determine whether the pressure in the power cylinder 20 satisfies the pressure condition. The pressure condition may be set by comparing the pressure in the power cylinder 20 detected by the pressure sensor 7 with a predetermined reference pressure. In particular, the reference pressure may be set in consideration of the capacity of the first motor 30 or the second motor 40. For example, assuming that the capacity of the first motor 30 as the main actuator is 100, and the capacity of the second motor 40 as the redundant actuator is 60, the reference pressure converted into the driving force of the motor may be set to a value less than 100.

[0038] When the pressure in the power cylinder 20 is less than the reference pressure, the controller 50 may be configured to operate only the first motor 30 because the first motor 30 can generate sufficient braking force. Conversely, when the pressure in the power cylinder 20 is greater than the reference pressure, the controller 50 may be configured to operate both the first motor 30 and the second motor 40. In particular, various methods may be used to distribute the driving force to the first motor 30 and the second motor 40. In this specification, a first distribution method and a second distribution method will be described.

[0039] According to the first allocation method, a reference driving force set to be less than the capacity of the first motor 30 can be allocated to the first motor 30, and the remaining driving force can be allocated to the second motor 40. In the above example, when the value obtained by converting the pressure in the power cylinder 20 into the driving force of the motor is 120, and the reference driving force of the first motor 30 is set to 80, the controller 50 can be configured to allocate 80 driving force to the first motor 30, and 40 driving force to the second motor 40. Of course, the reference pressure converted into the driving force of the motor and the reference driving force can be set to equal values ​​or different values. The first allocation method is an allocation method of a fixed value concept, in which any one motor driving force can be set to a predetermined reference value.

[0040] According to the second allocation method, the driving force may be allocated to the first motor 30 and the second motor 40 according to a predetermined ratio. In the above example, assuming that the value obtained by converting the pressure in the power cylinder 20 into the driving force of the motor is 120, and the predetermined ratio is "first motor: second motor = 6:4", the controller 50 may be configured to allocate 72 of the driving force to the first motor 30 and 48 of the driving force to the second motor 40. The second allocation method is an allocation method of a fixed ratio concept.

[0041] Even if the first allocation method and the second allocation method are applied, the controller 50 may be configured to allocate the maximum driving force to each motor when the magnitude of the pressure of the power cylinder 20 increases and the maximum capacity of each motor 30 and 40 is required. In an exemplary embodiment of the present invention, when the first motor 30 and the second motor 40 rotate in the same direction, both the driving force of the first motor 30 and the driving force of the second motor 40 may be applied to satisfy the brake pressure required by the automatic driving controller (not shown), thereby preventing any one motor from being required to apply excessive driving force.

[0042] At the same time, in response to determining that any one of the first motor 30 and the second motor 40 fails, the controller 50 can be configured to determine whether the other motor is normal. In response to the other motor also failing and the determination of the automatic driving / braking mode can no longer be performed, the controller 50 can be configured to switch to the manual driver braking mode. In the manual driver braking mode, the valve in the hydraulic control unit (HCU) is operated, and the braking force is generated by the driver's pedal effort.

[0043] On the contrary, in response to determining that the other motor is normal, the controller 50 may be configured to continuously operate the normal motor. Specifically, the controller 50 may be configured to determine the fault time point as the time point when the rotation position or rotation angle is last input from the faulty motor, and the controller 50 may be configured to determine the fault position as the rotation position of the rotor input from the motor position sensors 35 and 45. Therefore, the controller 50 may be configured to operate the normal motor after the fault point, and continuously operate the normal motor from the fault position.

[0044] Because determining whether the motor fails and adjusting the position of the normal motor can be performed quickly in real time by the controller 50, the delay of the response can be minimized, thereby preventing the braking delay felt by the occupants in the vehicle. At the same time, in this case, because a dangerous situation may occur if the pressure in the power cylinder 20 exceeds the capacity of the normal motor, the controller 50 can be configured to output a warning message or switch to a manual driver braking mode.

[0045] Figure 3 is a flowchart showing a process of controlling an electric brake booster for an autonomous driving vehicle with dual actuators according to an exemplary embodiment of the present invention. Figure 3 A control process of an electric brake booster for an autonomous driving vehicle having dual actuators according to an exemplary embodiment of the present invention is described.

[0046] First, the controller 50 may be configured to determine whether the first motor 30 is operating normally (S10). In response to determining that the first motor 30 is operating normally, the controller may be configured to determine whether the pressure in the power cylinder 20 is less than a reference pressure (S20). In particular, the controller may be configured to simultaneously operate the first motor 30 and the second motor 40 if the pressure in the power cylinder 20 is greater than the reference pressure (S32), and the controller may be configured to determine whether an emergency braking situation occurs if the pressure in the power cylinder 20 is less than the reference pressure (S30). If the current situation is not an emergency braking situation, the controller 50 may be configured to operate the first motor 30 (S34), and if the current situation is an emergency braking situation, the controller 50 may be configured to simultaneously operate the first motor 30 and the second motor 40 (S32).

[0047] At the same time, in response to determining that the first motor 30 is not operating normally, the controller 50 can be configured to receive the fault time point and fault location of the first motor 30 (S12), and determine whether the second motor 40 is operating normally (S40). In response to the determination that the second motor 40 has a fault, the controller 50 can be configured to switch from the automatic driving / braking mode to the manual driver braking mode (S42). Conversely, in response to determining that the second motor 40 is operating normally, the controller 50 can be configured to operate the second motor 40 from the received fault time point and the received fault location (S44).

[0048] The present invention has been described with reference to limited exemplary embodiments and drawings, but the present invention is not limited thereto. Those skilled in the art may make various changes or modifications to the described exemplary embodiments within the technical spirit of the present invention and the scope equivalent to the appended claims.

Claims

1. An electric brake booster for an autonomous vehicle having dual actuators, comprising: a main body portion configured to accommodate a power cylinder for generating brake pressure in an automatic driving / braking mode; a drive shaft axially movable in the power cylinder and coupled to the piston; a first motor connected to a first side of the drive shaft and configured to provide a driving force to the drive shaft; a second motor connected to a second side of the drive shaft and configured to provide a driving force to the drive shaft in the same direction as the driving force provided from the first motor; as well as a controller configured to determine whether the first motor or the second motor is operating normally, and configured to: operate the first motor and the second motor simultaneously or separately based on the magnitude of the pressure in the power cylinder or based on whether emergency braking occurs; Wherein, any one of the first motor and the second motor has a hollow structure to accommodate the piston and move the piston.

2. The electric brake booster according to claim 1, wherein: The main body also includes a master cylinder for generating brake pressure in a manual driver braking mode.

3. The electric brake booster according to claim 1, wherein: The first motor and the second motor are respectively connected to separate power sources, and power is supplied to the first motor and the second motor.

4. The electric brake booster according to claim 1, wherein: Motor position sensors are connected to the first motor and the second motor, respectively, to detect rotational positions of rotors of the motors.

5. The electric brake booster according to claim 1, wherein: A pressure sensor is connected to the power cylinder to detect the pressure in the power cylinder.

6. The electric brake booster according to claim 2, wherein: The master cylinder and the power cylinder are arranged to cross each other, and the first motor and the second motor are provided on both sides of the main body with the master cylinder interposed therebetween.

7. The electric brake booster according to claim 1, wherein: In response to determining that any one of the first motor and the second motor is faulty, the controller is configured to operate any one of the first motor and the second motor that is determined not to be faulty.

8. The electric brake booster according to claim 4, wherein: In response to a determination that any one of the first and second motors is faulty, the controller is configured to operate any one of the first and second motors determined not to be faulty from a rotational position detected by a motor position sensor.

9. The electric brake booster according to claim 2, wherein: In response to determining that both the first motor and the second motor have failed, the controller is configured to switch from an autonomous driving mode to a manual driver braking mode.

10. The electric brake booster according to claim 1, wherein: When a current condition is not an emergency braking situation or a pressure in the power cylinder is less than a predetermined reference pressure, the controller is configured to operate one of the first motor and the second motor.

11. The electric brake booster according to claim 1, wherein: When a current situation is an emergency braking situation or a pressure in the power cylinder is greater than a predetermined reference pressure, the controller is configured to simultaneously operate the first motor and the second motor.

12. The electric brake booster according to claim 1, wherein: When the controller distributes the driving force by operating the first motor and the second motor simultaneously, the controller is configured to distribute the driving force so that at least one motor has a driving force smaller than a capacity thereof.

13. The electric brake booster according to claim 1, wherein: When the controller distributes the driving force by operating the first motor and the second motor simultaneously, the controller is configured to distribute the driving force at a predetermined ratio.

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