JP5249690B2 - Electric brake - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric brake capable of correctly controlling the piston pressing force against a brake disk. <P>SOLUTION: The electric brake has a piston 1 to be pressed against a non-rotary brake disk 9 by the rotation of an electric motor 11, and a controller 20 for driving the electric motor 11 based on the control command value of the piston pressing force. The controller 20 has a friction torque loss corresponding current calculating means 31 for calculating the friction torque loss corresponding current value i<SB>f</SB>for compensating the friction torque loss generated in the process of transmitting the torque generated by the electric motor 11 to each piston 1 based on the motor current i<SB>m</SB>of the electric motor 11 and the motor rotational speed d&theta;<SB>m</SB>/dt of the electric motor 11, and the controller drives the electric motor 11 by adding the friction torque loss corresponding current value i<SB>f</SB>to the motor current i<SB>m</SB>. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an improvement of an electric brake that drives a braking member of a wheel with an electric motor.

  In recent years, in order to reduce or eliminate the hydraulic pressure source mounted on an aircraft, there is a tendency to change a brake for braking a wheel from a hydraulic brake to an electric brake.

Patent Document 1 discloses an electric brake that generates a braking force by converting a rotary motion of an electric motor into a reciprocating motion of a piston.
Japanese Patent Laying-Open No. 2005-069398

  However, in such a conventional electric brake, a friction torque loss occurs in the process of transmitting the generated torque of the electric motor to the piston. Therefore, the piston pressing force against the brake disc is accurately determined due to the friction torque loss. There was a problem that it could not be controlled.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide an electric brake capable of accurately controlling a piston pressing force against a brake disk.

The present invention relates to a rotary brake disc that rotates with a wheel, a non-rotary brake disc that is displaceable and non-rotatable toward the rotary brake disc, an electric motor that is rotated by a motor current, and a reciprocating motion from a rotational motion. A ball screw that has a predetermined mechanical efficiency when converting into a reciprocating motion and converts the rotational operation of the electric motor into a reciprocating motion based on the mechanical efficiency, and a piston that is pressed against the non-rotating brake disk by the reciprocating motion of the ball screw It controls the electric motor includes a controller for adjusting the piston pressing force of the piston, the controller, based on the mechanical efficiency of the motor current and the electric motor the motor speed and a ball screw, a piston generation torque of the electric motor Friction torque loss equivalent power to compensate for friction torque loss generated in the process of transmission to Comprising a friction torque loss equivalent current calculating means for calculating a value, and shall be characterized configured to drive the electric motor the friction torque loss equivalent current value by adding to the motor current.
The present invention relates to a rotating brake disc that rotates with a wheel, a non-rotating brake disc that is displaceable and non-rotatable toward the rotating brake disc, an electric motor that is rotated by a motor current, and a rotating operation of the electric motor. A piston that is pressed against the non-rotating brake disc, and a controller that controls the electric motor to adjust the piston pressing force of the piston, the controller being a function proportional to the motor current, the motor rotation of the electric motor Friction torque loss that occurs in the process of transmitting the generated torque of the electric motor to the piston based on a function that takes a positive value when the electric motor accelerates positively according to the speed and takes a negative value when the electric motor decelerates positively Friction torque loss equivalent current calculation means for calculating the friction torque loss equivalent current value For example, and as characterized by arrangement for driving the electric motor the friction torque loss equivalent current value by adding to the motor current.

  According to the present invention, hysteresis due to friction torque loss generated in the process of transmitting the generated torque of the electric motor to each piston is eliminated, and the pressing force of the piston can be accurately controlled, and the braking force generated by the electric brake Control responsiveness and accuracy can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  The electric brake for aircraft shown in FIG. 1 is a multi-plate disc type provided inside the wheel of the wheel.

  The electric brake includes a disc-shaped rotating brake disc 6 that rotates together with wheels, a disc-shaped non-rotating brake disc 9 attached to a body shaft (axle), a piston 1 that faces the non-rotating brake disc 9, and a piston 1 And an electric actuator 5 that drives the non-rotating brake disk 9 to move forward and backward.

  A plurality of rotating brake discs 6 are arranged between a plurality of non-rotating brake discs 9. The non-rotating brake disk 9 is supported so as to be displaceable in the axle direction via a torque tube or the like with respect to a body shaft (not shown). The rotary brake disc 6 rotates integrally with a wheel (not shown), and is supported so as to be displaceable in the axle direction with respect to the wheel.

  In a state where the electric actuator 5 is contracted, the non-rotating brake disk 9 and the rotating brake disk 6 are separated from each other, and no braking torque is generated. When the electric actuator 5 is extended from this brake released state, the non-rotating brake disk 9 and the rotating brake disk 6 are pressed against each other by the pressing force of each piston 1, and frictional force is generated at this sliding portion, and the braking torque is increased. can get.

  The piston 1 is slidably supported by the housing 7, and a ball screw / nut mechanism 2 is interposed therein. The ball screw / nut mechanism 2 includes a ball screw 15 protruding from the base end portion of the piston 1 and a ball nut (not shown) screwed into each ball screw 15 via a number of balls. The rotation of 15 is converted into the linear motion of the piston 1, and the piston 1 is configured to advance and retract with respect to the non-rotating brake disk 9.

  The housing 7 includes two electric motors 11, four pistons 1, and two speed reduction mechanisms 10 that transmit the rotation of one electric motor 11 to two ball screws 15. The four pistons 1 are arranged with a certain interval in the circumferential direction of the wheel. The speed reduction mechanism 10 may be configured to transmit the rotation of one electric motor 11 to one ball screw 15.

  The number Np of the pistons 1 and the number Nm of the electric motors 11 are not limited to this, and are arbitrarily set according to the braking force required for the electric brake.

  The speed reduction mechanism 10 is configured to transmit the rotation of one electric motor 11 to two ball screws 15. A drive gear 14 is connected to the motor shaft 13 of the electric motor 11, and a driven gear 16 is connected to the base end portion of the ball screw 15, and the rotation of one drive gear 14 is transmitted to the two driven gears 16.

  When the electric motor 11 rotates in the forward direction, each piston 1 comes into contact with the non-rotating brake disk 9 and presses each non-rotating brake disk 9 against each rotating brake disk 6 to obtain a braking torque. On the other hand, when the electric motor 11 is rotated in the return direction by the drive current, each piston 1 is separated from the non-rotating brake disk 9, and the non-rotating brake disk 9 is not pressed against each rotating brake disk 6. Canceled.

  The aircraft control system outputs a piston pressing force command value signal in accordance with the amount of operation of the brake pedal operated by the pilot.

  As shown in FIG. 2, an electric brake controller 20 is provided as motor control means for driving the electric motor 11 based on the piston pressing force command value signal.

  In principle, since the pressing force of each piston 1 is proportional to the motor current of the electric motor 11, the controller 20 can adjust the pressing force of each piston 1 by controlling the motor current. However, in actuality, a friction torque loss occurs when the electric motor 3, the speed reduction mechanism 10, the ball screw / nut mechanism 2, etc. are operated in the process of transmitting the generated torque of the electric motor 11 to each piston 1. Hysteresis due to loss occurs between the piston pressing force command value and the actual piston pressing force.

  FIG. 3 shows how the piston pressing force by the conventional open control based on the piston pressing force command value changes. When the piston pressing force command value changes periodically, the actual piston pressing force includes the electric motor 3. Hysteresis due to friction torque loss of the speed reduction mechanism 10 and the ball screw / nut mechanism 2 occurs. A positive hysteresis H is generated when the braking force increases when the piston pressing force increases, and a negative hysteresis H occurs when the braking force decreases when the piston pressing force decreases. For this reason, with the conventional open control method, the piston pressing force cannot be accurately controlled.

  In response to this, the controller 20 of the present invention corrects the frictional torque loss required in the process of transmitting the torque generated by the electric motor 11 to each piston 1 according to the motor current and the motor rotation speed. The electric motor 11 is driven by the motor current obtained by calculating the friction torque loss equivalent current that generates the generated torque and adding the friction torque loss equivalent current.

  FIG. 2 is a block diagram showing a configuration for generating a piston pressing force by controlling the drive current of the electric motor 11.

The controller 20 includes a piston pressing force controller 22 that calculates a control command value according to a piston pressing force command value signal sent from an aircraft control system, and a pressing force current conversion gain that converts the control command value into a current command value. 23, a motor driver 24 that outputs a motor current to the electric motor 11 according to the current command value signal, and a friction torque loss equivalent current that outputs a friction torque loss equivalent current command value signal according to the motor current and the motor rotation speed. And a calculation means 31 for adding the friction torque loss equivalent current command value signal to the current command value signal output to the motor driver 24 via the low-pass filter 32. However, the present invention is not limited to this, and the low-pass filter 32 may be eliminated. It is also possible to enter the motor current to the friction torque loss equivalent current calculating section 31 through a low-pass filter.

  The controller 20 outputs drive power corresponding to the current command value signal to the electric motor 11 to rotate the electric motor 11. The driving force of the electric motor 11 is transmitted to the piston 1 via the speed reducer 10 and the ball screw / nut mechanism 2, and a piston pressing force is generated.

  The piston pressing force controller 22 calculates a control command value according to the piston pressing force command value based on a preset map, and outputs a control command value signal.

  The pressing force current conversion gain 23 converts a control command value into a current command value based on a preset gain, and outputs a current command value signal.

Motor driver 24, motor current i _m of the electric motor 11 to input the detection value signal of the motor current i _m flowing to the detection signal and the electric motor 11 of the motor rotational angle theta _m of the current command value signal and the electric motor 11, respectively Feedback control.

  The drive power is controlled by, for example, controlling the drive voltage by PWM (Plus Width Modulation), so that an average current corresponding to the ON / OFF time flows.

Friction torque loss equivalent current calculating section 31 inputs the motor rotation speed d [theta] _m / dt of the detection signal and the electric motor 11 of the motor current i _m flowing through the electric motor 11 to calculate the friction torque loss equivalent current i _f, The friction torque loss equivalent current command value signal is output.
The friction torque loss equivalent current _if is calculated by the following equation.

i _f = (1−η _m ) × i _m × sgn (dθ _m / dt) (1)

Here, η _m is the rotational efficiency of the ball screw / nut mechanism 2 and the mechanical efficiency of the reciprocating motion conversion unit.
Further, sgn (dθ _m / dt) is a value representing the rotation direction of the electric motor 11 and is calculated by the following equation.

_{sgn (dθ m / dt) =} | (dθ m / dt) | / (dθ m / dt) ... (2)

The sgn (dθ _m / dt) becomes +1 when the electric motor 3 is accelerated in the positive rotation (when the braking force is increased), and becomes -1 when the electric motor 3 is decelerated in the positive rotation (when the braking force is reduced).

Thereby, as shown by a broken line in FIG. 3, when the piston pressing force command value periodically changes, the friction torque loss equivalent current value i becomes a positive value when the braking force increases so that the piston pressing force command value increases. _By adding _f to the current command value, the positive hysteresis H is eliminated. On the other hand, when the braking force is reduced to reduce the piston pressing force, the friction hysteresis loss equivalent current value _if is added to the current command value, thereby eliminating the negative hysteresis H.

The friction torque loss equivalent current value i _f is to increase or decrease depending on the motor current i _m flowing through the electric motor 11, the hysteresis H which increases or decreases according to the pressing force of the piston 1 is eliminated accurately.

Although friction torque loss equivalent current value i _f shown in equation (1) it is in the form proportional to the motor current i _m, if the hysteresis H is a strong non-linearity with respect to the motor current i _m, using different functions Also good.

As described above, in the present embodiment, the rotary brake disc 6 that rotates together with the wheels, the non-rotary brake disc 9 that is supported so as to be displaceable and non-rotatable toward the rotary brake disc 6, and the motor current rotates. An electric motor 11, a piston 1 that is pressed against the non-rotating brake disk 9 by the rotation of the electric motor 11, and a controller 20 that drives the electric motor 11 based on a piston pressing force command value are provided. friction torque loss equivalent current to compensate for the frictional torque loss caused in the process of transmitting the torque generated by the electric motor 11 to the piston 1 based on the motor rotation speed d [theta] _m / dt of the motor current i _m and the electric motor 11 of the electric motor 11 comprising a friction torque loss equivalent current calculating section 31 for calculating the value i _f, friction torque loss And configured to drive the electric motor 11 a corresponding current value i _f is added to the motor current i _m.

  As a result, the hysteresis caused by the loss of friction torque generated in the process of transmitting the torque generated by the electric motor 11 to each piston 1 is eliminated, the pressing force fp of the piston 1 can be accurately controlled, and an electric brake is generated. Control response and accuracy of braking force can be improved.

  In the present embodiment, a plurality of pistons 1 that face the non-rotating brake disk 9, a ball screw 15 that is rotatably connected to the piston 1, and the rotation of one electric motor 11 are transmitted to the plurality of ball screws 15. Therefore, the hysteresis caused by the friction torque loss of the speed reduction mechanism 10 and the ball screw / nut mechanism 2 can be eliminated, and the actual piston pressing force can be accurately controlled. In addition, the number of electric motors used is halved compared to conventional devices, and the number of electric motor drivers and cables is reduced. Thereby, the reliability of the product can be improved and the cost of the product can be reduced.

In this embodiment, the friction torque loss equivalent current calculating section 31 was configured to calculate a frictional torque loss equivalent current value i _f in accordance with the detection value signal of the motor current i _m flowing through the electric motor 11.

As another embodiment, as shown in FIG. 4, the friction torque loss equivalent current calculation means 31 includes a command value signal of the current output from the pressing force current conversion gain and the motor rotational speed dθ _m / dt of the electric motor 11. preparative enter calculates the friction torque loss equivalent current i _f, may output a frictional torque loss equivalent current command value signal.

  Next, another embodiment shown in FIG. 5 will be described. This basically has the same configuration as that of the embodiment of FIG. 2, and only different portions will be described. In addition, the same code | symbol is attached | subjected to the same structure part as the said embodiment.

The piston pressing force estimator 21 receives a detection signal of the motor rotation angle θm of the electric motor 11, calculates an estimated value of the pressing force fp of the piston 1 according to the motor rotation angle θm, and a piston pressing force controller 22. feedback controls the control command value for the electric motor 11 so as to approach the estimated value of the piston pressing force fp to the piston pressing force command value.

FIG. 1 shows a model diagram of an electric brake composed of Nm electric motors 11 and Np pistons 1. The equation of motion of the equivalent inertia mass Me composed of the rotor of the electric motor 11 and the inertia moment of the speed reduction mechanism 10 and the mass of the rotary brake disc 6 is expressed by the following equation.

However,
M _c : Equivalent inertia mass C _e : Equivalent viscous resistance coefficient K _e : Spring constant of brake structure R _g : Reduction ratio of reduction mechanism 10 L _b : Lead of ball screw / nut mechanism 2 K _T : Torque of electric motor 11 constant y _p: stroke of the piston 1 theta _m: rotation angle of the electric motor 11 f _a: 1 per theoretical thrust f _f of the piston 1: friction force per one piston 1 i _m: 1 of the electric motor 11 Current τ _f per unit: friction torque per deceleration mechanism 10 The sum of the viscosity term and the spring term in equation (3) is the total pressing force fp of the piston 1, and this total pressing force fp is expressed by the following equation: The

As described above, if the rotation angle θ _m of the electric motor 11 is detected and the rotation speed dθ _m / dt is calculated, the total pressing force fp of the piston 1 can be estimated from the equation (7).

In the present embodiment, the piston pressing force fp of the piston 1 against the non-rotating brake disk 9 is estimated according to the motor rotation angle θ _m of the electric motor 11, and the estimated value of this piston pressing force fp is used as the piston pressing force command value. Since the control command value for the electric motor 11 is feedback-controlled so as to be close to, the control responsiveness and accuracy of the braking force generated by the electric brake can be improved without being affected by disturbance. Moreover, since it is not necessary to provide the load sensor which measures the pressing force fp of piston 1 by the said structure, the cost increase of a product can be avoided.

  The present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea.

  The electric brake of the present invention can be used not only for braking aircraft wheels but also for other vehicles.

The block diagram of the electric brake which shows embodiment of this invention. The block diagram of a controller similarly. The diagram which shows a mode that the piston pressing force command value by the conventional control and an actual piston pressing force change. The block diagram of the controller which shows other embodiment. The block diagram of the controller which shows other embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piston 2 Ball screw / nut mechanism 3 Electric motor 6 Rotating brake disk 7 Housing 9 Non-rotating brake disk 10 Deceleration mechanism 11 Electric motor 20 Controller 21 Piston pressing force estimator 22 Piston pressing force controller 24 Motor driver 31 Corresponding to friction torque loss Current calculation means

Claims (6)

A rotating brake disc that rotates with the wheels,
A non-rotating brake disks displaceably and non-rotatably supported toward the rotating brake disc,
An electric motor that rotates by a motor current;
A ball screw having a predetermined mechanical efficiency when converting from a rotational motion to a reciprocating motion, and converting a rotational operation of the electric motor to a reciprocating motion based on the mechanical efficiency;
A piston pressed against the non-rotating brake disc by reciprocating motion of the ball screw ;
And a controller for adjusting the piston pressing force of the piston by controlling the electric motor,
Wherein the controller,
Based on the motor current and the motor rotation speed of the electric motor and the mechanical efficiency of the ball screw, the friction torque loss equivalent current value of the generated torque of the electric motor supplementing the frictional torque loss caused in the process of transferring to the piston Friction torque loss equivalent current calculating means for calculating,
Dynamic brake conductive, characterized in that the frictional torque loss equivalent current value by adding to the motor current for driving the electric motor. The friction torque loss equivalent current calculation means includes:
The motor rotation angle of the electric motor is θm, the motor rotation speed of the electric motor is dθm / dt, and a value sgn (dθm / dt) representing the rotation direction of the electric motor is
sgn (dθm / dt) = | (dθm / dt) | / (dθm / dt)
Calculated by the formula
The mechanical efficiency of the ball screw is ηm, the motor current is im, the friction torque loss equivalent current value is if, and the friction torque loss equivalent current value if is
if = (1-.eta.m) .times.im.times.sgn (d.theta.m / dt)
Dynamic braking electric according to claim 1, characterized in that calculated by the formula. The friction torque loss equivalent current calculation means calculates the friction torque loss equivalent current value based on the motor current output from the electric motor, the rotational speed of the electric motor, and the mechanical efficiency of the ball screw. The electric brake according to claim 1 or 2, characterized in that: The controller further includes a pressing force current conversion gain for converting a control command value based on a piston pressing force command value signal sent from the control system into a motor current,
The friction torque loss equivalent current value is calculated based on the motor current output from the pressing force current conversion gain, the motor rotation speed of the electric motor, and the mechanical efficiency of the ball screw. The electric brake according to claim 1, wherein the electric brake is calculated. A rotating brake disc that rotates with the wheels,
A non-rotating brake disc supported displaceably and non-rotatably toward the rotating brake disc;
An electric motor that rotates by a motor current;
A piston that is pressed against the non-rotating brake disc by the rotation of the electric motor;
A controller for controlling the electric motor to adjust the piston pressing force of the piston,
The controller is
Based on a function that is proportional to the motor current and has a positive value during positive rotation acceleration of the electric motor and a negative value during positive rotation deceleration of the electric motor according to the motor rotation speed of the electric motor. A friction torque loss equivalent current calculating means for calculating a friction torque loss equivalent current value that compensates for a friction torque loss generated in the process of transmitting the generated torque of the electric motor to the piston,
An electric brake characterized by adding the friction torque loss equivalent current value to a motor current to drive the electric motor. The controller is
A piston pressing force estimator that calculates an estimated value of the piston pressing force according to a motor rotation angle of the electric motor;
6. The electric brake according to claim 1, wherein the control command value for the electric motor is feedback-controlled so that the estimated value of the piston pressing force approaches the piston pressing force command value.

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