JP5296908B2 - Electric brake - Google Patents

Description

  The present invention relates to 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.

  By the way, in the disc type brake, when the disc is worn, the clearance between the disc and the piston is increased. When the clearance becomes large, it takes time to start braking after operating the electric brake, and the aircraft runs idle during that time. Therefore, in order to prevent the idling time from becoming longer due to wear of the disc, it is necessary to keep the clearance between the disc and the piston constant even if the disc is worn.

  Patent Document 1 discloses an electric brake that adjusts a clearance using a rotation angle sensor of an electric motor.

JP 2006-105224 A

  However, in the method of adjusting the clearance based on the position where it is detected that the piston is in contact with the disk, the motor current increases greatly at the same time as the piston and disk come into contact with the clearance adjustment. Detection delay occurred depending on the period, and it was difficult to detect the exact contact position between the piston and the disk. Therefore, there is a possibility that the clearance between the disk and the piston cannot always be adjusted to be constant.

  Accordingly, an object of the present invention is to provide an electric brake capable of adjusting the clearance between the disc and the piston to be constant.

  The present invention includes a rotating disk that rotates together with a wheel, a wheel control unit that is supported so as not to rotate with respect to the airframe, and that is displaceable toward the rotating disk, and a piston that is capable of moving back and forth toward the wheel control unit. An electric actuator that linearly moves the piston, and a controller that controls the operation of the electric actuator, and the electric actuator brakes the wheel control means against the rotating disk via the piston. An electric brake for generating torque, wherein when the initial position of the piston is adjusted, driving stop means for stopping the operation of the electric actuator after being driven until the piston is pressed against the wheel control means; and operation of the electric actuator Based on the position where the piston is stopped by being pushed back by the reaction force when stopping Piston initial position adjusting means for adjusting the initial position of the piston, and the piston initial position adjusting means moves the piston from the stop position toward the wheel control means by a predetermined stroke, and It is set as the initial position of.

  In the present invention, the initial position of the piston is adjusted by the piston initial position adjusting means based on the position where the piston is pushed back by the reaction force and stopped. The reaction force that pushes back the piston is a force that is mechanically determined by the members that make up the electric brake, and is therefore generally constant. Therefore, it is possible to obtain an electric brake that can adjust the clearance between the disc and the piston to be constant.

  Further, the piston initial position adjusting means moves the piston toward the wheel control means by a predetermined stroke from the position where the piston is pushed back by the reaction force from the wheel control means and stops the piston initial position. Therefore, by reducing the clearance between the piston and the wheel control means, the distance between the piston and the wheel control means can be made minute and the response of the electric brake can be improved.

It is the figure which showed the upper half from the central axis of the electric brake which concerns on embodiment of this invention in the cross section. It is a flowchart figure of the control which determines the clearance variable of an electric brake. It is a flowchart figure which concerns on other embodiment of the control which determines the clearance variable of an electric brake.

  Hereinafter, an electric brake 100 according to an embodiment of the present invention will be described with reference to the drawings.

  First, the configuration of the electric brake 100 will be described with reference to FIG. A center axis O in FIG. 1 is a center axis of an unillustrated airframe shaft (hereinafter referred to as “axle”) fixed to an unillustrated airframe.

  The electric brake 100 is a multi-disc disc type brake provided inside a wheel (not shown). The electric brake 100 is used as a brake for braking an aircraft wheel.

  The wheel is configured by attaching a tire (not shown) to the outer periphery of the wheel (not shown). The wheel is attached to the axle via a bearing (not shown). That is, the axle does not rotate even if the wheel rotates.

  The electric brake 100 includes a rotating disk 6 that rotates integrally with a wheel, and a non-rotating disk 4 that is attached to an axle and does not rotate. The electric brake 100 presses the rotating disk 6 and the non-rotating disk 4 in contact with each other, and generates a braking torque by a frictional force.

  A plurality of the rotating disks 6 are provided at a predetermined interval. The non-rotating disk 4 is provided on both surfaces of the rotating disk 6. Therefore, a plurality of non-rotating disks 4 are also provided at a predetermined interval. In the electric brake 100, the three rotating disks 6 are sandwiched between the four non-rotating disks 4. The number of each of the non-rotating disk 4 and the rotating disk 6 is set according to the required braking force or the like, and is not limited to this number.

  The rotating disk 6 has a disk shape in which a circular hole is formed at the center. The outer periphery of the rotating disk 6 is supported by the inner periphery of the wheel, and rotates together with the wheel. The rotating disk 6 is supported so as to be displaceable in the axle direction with respect to the wheel, that is, slidable.

  The non-rotating disk 4 has a disk shape in which a circular hole is formed at the center. The inner periphery of the non-rotating disk 4 is supported on the axle via the torque tube 3. The non-rotating disc 4 does not rotate even if the wheel rotates. The non-rotating disc 4 is supported so as to be displaceable in the axle direction, that is, slidable. This non-rotating disk 4 corresponds to the wheel control means. In the case of a caliper type disc brake instead of the multi disc type as in the electric brake 100, for example, a brake pad can be provided as a wheel control means.

  The torque tube 3 has a bobbin shape in which disk-shaped flange portions 3b and 3c are provided at both ends in the axial direction of a cylindrical cylindrical portion 3a. The flanges 3b and 3c do not have to be disk-shaped, and for example, a plurality of protrusions corresponding to positions where the piston 28 and the disk presser 3d are provided may be formed. The torque tube 3 supports a plurality of non-rotating disks 4 on the outer periphery of the cylindrical portion 3a. A gap is provided between the torque tube 3 and the rotating disk 6 so that the torque tube 3 and the rotating disk 6 do not contact each other. That is, the diameter of the hole formed at the center of the rotating disk 6 in the radial direction is formed so as not to come into contact with the torque tube 3, so that the diameter of the hole formed at the center of the non-rotating disk 4 in the radial direction is larger. Is also formed large.

  One flange portion 3 c of the torque tube 3 is attached to the axle via the housing 2. A disk presser 3 d is provided on the other flange 3 b of the torque tube 3. Between the piston 28 protruding from the housing 2 and the disk retainer 3d, the rotating disk 6 and the non-rotating disk 4 are pressed so as to contact each other. Therefore, the torque tube 3 receives a reaction force of a force that presses the rotating disk 6 and the non-rotating disk 4.

  The housing 2 is fixed to the axle, and an electric motor 21 as an electric actuator for driving the electric brake 100, a speed reduction mechanism 24 for reducing the rotation of the electric motor 21 and transmitting it to the ball screw 25, and a piston pushed out by the ball screw 25 28 in the inside.

  The piston 28 is provided to face the non-rotating disk 4 so as to be able to advance and retreat toward the non-rotating disk 4. The piston 28 is formed integrally with the ball nut 26 of the ball screw / nut mechanism 27. X0 in FIG. 1 is a clearance between the piston 28 and the non-rotating disk 4. That is, the piston 28 faces the non-rotating disk 4 with a clearance X0. The piston 28 is driven by the electric motor 21 so as to advance and retreat with respect to the non-rotating disk 4. Plural pistons 28 are arranged at predetermined intervals in the rotational circumferential direction of the wheel. The number of pistons 28 and the number of electric motors 21 are arbitrarily set according to the braking force required for the electric brake 100 and the like.

  The clearance X0 between the piston 28 and the non-rotating disk 4 when the braking of the electric brake 100 is released is adjusted by the electric motor 21. When the thickness of the non-rotating disc 4 changes due to wear, the clearance X0 between the piston 28 and the non-rotating disc 4 when the piston 28 returns increases. Therefore, the electric brake 100 performs control to keep the clearance X0 constant. The contents of the control will be described later in detail with reference to FIG.

  A plurality of (for example, 4 to 6) electric motors 21 are provided inside the housing 2. The electric motor 21 linearly moves the piston 28 via the speed reduction mechanism 24, and presses the piston 28 against the non-rotating disk 4, so that the non-rotating disk 4 and the rotating disk 6 are pressed against each other. As a result, a frictional force is generated at the sliding surface portion between the non-rotating disk 4 and the rotating disk 6 so that a braking torque is obtained. As the electric motor 21, for example, a motor including a rotation angle detection unit that can detect a rotation angle and a rotation number, such as an AC servo motor or a stepping motor, is used. Or you may make it the structure which provides rotation angle detection means, such as a rotary encoder, as a member different from the electric motor 21. FIG.

  The speed reduction mechanism 24 is configured to transmit the rotation of the electric motor 21 to the ball screw 25. The speed reduction mechanism 24 includes a drive gear 22 connected to the motor shaft 29 of the electric motor 21 and a driven gear 23 connected to the base end portion of the ball screw 25. The speed reduction mechanism 24 transmits the rotation of the drive gear 22 to the driven gear 23. In the electric brake 100, a gear having a smaller number of teeth and a smaller diameter is used as the drive gear 22, and a gear having a larger number of teeth and a larger diameter than the drive gear 22 is used as the driven gear 23. That is, the rotation of the electric motor 21 is decelerated and transmitted to the ball screw 25.

  The ball screw / nut mechanism 27 is interposed inside the piston 28. The ball screw / nut mechanism 27 protrudes to the inside of the piston 28, is fixed to the driven gear 23 and rotates as a unit, and the ball nut 26 is fixed to the piston 28 and advances / retreats with respect to the non-rotating disk 4. Is provided. The ball nut 26 is screwed onto the ball screw 25 via a large number of balls (not shown). The ball screw / nut mechanism 27 converts the rotational motion of the ball screw 25 into linear motion, and moves the piston 28 forward and backward with respect to the non-rotating disc 4.

  Incidentally, 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. The aircraft is provided with a controller 30 that controls the operation of the electric motor 21 based on the output piston pressing force command value signal.

  The controller 30 controls the electric brake 100 and includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and an I / O interface (input / output interface). Consists of a microcomputer. The RAM stores data in the processing of the CPU, the ROM stores a control program of the CPU in advance, and the I / O interface is used for input / output of information with the connected device. Control of the electric brake 100 is realized by operating a CPU, RAM, and the like according to a program stored in the ROM.

  A signal from the brake pedal is input to the CPU via the I / O interface. The CPU calculates a piston pressing force command value signal corresponding to the input signal. The CPU outputs a command drive current io corresponding to the piston pressing force command value signal to the electric motor 21 via the I / O interface, and the electric motor 21 is rotated. The driving force of the electric motor 21 is transmitted to the piston 28 via the speed reduction mechanism 24 and the ball screw / nut mechanism 27, and a piston pressing force is generated. At this time, the rotation angle θ of the motor shaft 29 of the electric motor 21 is detected by a rotation angle detection means (not shown) and is input to the controller 30 together with the actual drive current i of the electric motor 21.

  In the electric brake 100, the electric motor 21 rotates in the positive direction by the output from the controller 30, so that the piston 28 contacts the non-rotating disk 4 and presses each non-rotating disk 4 against each rotating disk 6. can get. On the other hand, when the electric motor 21 is rotated in the reverse direction by the command drive current io, the pistons 28 are separated from the non-rotating disks 4 and the non-rotating disks 4 are not pressed against the rotating disks 6 and the braking is released. Is done.

  Hereinafter, the clearance adjustment control between the piston 28 and the non-rotating disc 4 in the electric brake 100 will be described with reference to FIG. This clearance adjustment control is performed, for example, when there is a request from the aircraft side during inspection.

  First, in step 11, a minute current for rotating the electric motor 21 in the forward direction is applied according to a command from the controller 30. The piston 28 slowly protrudes toward the non-rotating disk 4 by the rotation of the electric motor 21.

  Next, in step 12, it is determined whether or not the electric motor 21 has stopped. When the piston 28 contacts the non-rotating disc 4 facing the piston 28, the piston 28 cannot advance any further. When the piston 28 cannot be advanced by the driving torque of the electric motor 21, the electric motor 21 stops. At this time, the electric motor 21 stops while attempting to rotate in the forward direction. Therefore, the piston 28 and the non-rotating disk 4 and the non-rotating disk 4 and the rotating disk 6 are pressed so as to contact each other. In step 12, the determination in step 12 is repeated until the electric motor 21 stops, and if it is determined that the electric motor 21 has stopped, the process proceeds to step 13.

  In step 13, it is determined whether or not the actual drive current i of the electric motor 21 has become a predetermined value or more. If it is determined that the value is not equal to or greater than the predetermined value, the command current is increased in step 14, and the process returns to step 12 to repeat the determination of whether or not the electric motor 21 has stopped. If it is determined that the actual drive current i of the electric motor 21 has become a predetermined value or more, the routine proceeds to step 15. At this time, 28 pressing force is generated on the piston by the driving torque corresponding to the predetermined driving current, and the disks 4 and 6 and the torque tube 3 are bent.

  In step 15, the operation of the electric motor 21 is stopped. At this time, the electric motor 21 is in a servo-off state, and the motor shaft 29 is freed. When the operation of the electric motor 21 is stopped, the process proceeds to step 16. Steps 11 to 15 correspond to drive stop means.

  In step 16, it is determined whether or not a predetermined time has elapsed since the operation of the electric motor 21 was stopped. If it is determined that the predetermined time has not elapsed, the determination in step 16 is repeated, and if it is determined that the predetermined time has elapsed, the process proceeds to step 17.

  When the operation of the electric motor 21 is stopped, the piston 28 is pushed back by the reaction force of the force pressing the non-rotating disc 4. The piston 28 is separated from the non-rotating disk 4 by the force pushed back, and naturally stops at a predetermined interval. Since time is required for the operation until the piston 28 is pushed back and stopped, it is determined in step 16 whether or not a predetermined time has elapsed. Here, the predetermined time is a sufficient time until the piston 28 is pushed back and naturally stops.

  When the piston 28 is pushed back by the reaction force, the ball nut 26 to which the piston 28 is fixed is pushed away from the non-rotating disk 4, that is, into the housing 2. When the ball nut 26 is pushed, the ball screw 25 is rotated, and the rotation is transmitted to the driven gear 23 of the speed reduction mechanism 24 to which the ball screw 25 is fixed. When the driven gear 23 is rotated, the drive gear 22 meshing with the driven gear 23 is also rotated, and the motor shaft 29 of the electric motor 21 connected to the drive gear 22 is also rotated.

  Thus, the ball nut 26, the driven gear 23, the drive gear 22, and the motor shaft 29 are rotated by the piston 28 being pushed back by the reaction force. Therefore, the piston 28 moves until the rotation of these rotated members naturally stops. That is, the piston 28 initially moved by the reaction force received by the piston 28 is moved by the rotational inertia of the rotated member immediately before stopping.

  Here, the force for pushing back the piston 28 is mechanically determined by the components constituting the electric brake 100. Specifically, there are a force for the bent torque tube 3 to return to the original, a force for the rotating disk 6 and the non-rotating disk 4 that have been pressed and compressed so as to contact each other to return to the original, and the like. Therefore, the distance that the piston 28 moves away after being pushed back is always substantially constant.

  In step 17, the position at which the piston 28 pushed back by the reaction force stops is detected from the rotation angle θ of the electric motor 21 at that time. That is, the clearance between the piston 28 and the non-rotating disk 4 is detected. Steps 16 and 17 correspond to piston stop position detecting means. When the position where the piston 28 is stopped is detected, the routine proceeds to step 18.

  In step 18, the clearance variable is reset. That is, this position where the piston 28 naturally stops is set to the initial value of the clearance X0. This step 18 corresponds to the piston initial position adjusting means.

  In this way, the position where the piston 28 naturally stops may be set to the initial value of the clearance X0. However, when the force to push back the piston 28 is large and the clearance X0 is too large, the piston 28 is moved from the position where the piston 28 naturally stopped. The clearance variable may be reset after moving toward the non-rotating disk 4 by a predetermined stroke and further reducing the clearance X0 between the piston 28 and the non-rotating disk 4. This corresponds to the case where the rigidity of the torque tube 3 is not high and the electric brake 100 is bent relatively large during braking. Thus, by further reducing the clearance X0, the interval between the piston 28 and the non-rotating disk 4 can be made minute, and the responsiveness of the electric brake 100 can be improved.

  According to the above embodiment, the following effects can be obtained.

  In the electric brake 100, the position where the piston 28 is pushed back by the reaction force and stopped is detected, and the initial value of the clearance X0 is set based on the detected value. At this time, the reaction force that pushes back the piston 28 is a force that is mechanically determined by the members constituting the electric brake 100, and is therefore substantially constant.

  Therefore, the clearance X0 between the non-rotating disk 4 and the piston 28 can be adjusted to be constant.

  Hereinafter, another embodiment will be described with reference to FIG. In this embodiment, the adjustment control of the clearance X0 is performed when the braking of the electric brake 100 in the braking state starts to be released. In this embodiment, the clearance X0 can be adjusted to be constant without providing the electric motor 21 with a rotation angle detection means.

  In step 21, it is detected that a brake release command has been issued due to the start of the operation of returning the brake pedal by the pilot. That is, it is considered that the braking of the electric brake 100 has started to be released due to the start of the operation of returning the brake pedal. The determination in step 21 is repeated until a brake release command is detected, and when a brake release command is detected, the process proceeds to step 22.

  In step 22, it is determined whether or not the current of the electric motor 21 is equal to or less than a command value. If it is determined that the current of the electric motor 21 is equal to or greater than the command value, the command current is decreased in step 23, and if it is determined that the current of the electric motor 21 is equal to or less than the command value, the process proceeds to step 24. That is, the current of the electric motor 21 is gradually decreased so as to be equal to or less than the command value.

  In step 24, it is determined whether or not the current of the electric motor 21 is equal to or greater than a command value. If it is determined that the current of the electric motor 21 is equal to or greater than the command value, the command current is increased in step 25. If it is determined that the current of the electric motor 21 is equal to or greater than the command value, the process proceeds to step 26. That is, the current of the electric motor 21 is gradually increased so as to be equal to or greater than the command value.

  Here, the motor current command value in step 24 is set larger than the motor current command value in step 22. Therefore, the motor current command value at the time of shifting to step 26 is almost constant at a value when the motor current command value at step 24 is always greater than or equal to the motor current command value. In this way, in step 22 to step 25, the current value applied to the electric motor 21 is adjusted to a predetermined value.

  In step 26, the operation of the electric motor 21 is stopped. At this time, the electric motor 21 is in a servo-off state, and the motor shaft 29 is freed. When the operation of the electric motor 21 is stopped, the routine proceeds to step 27. Steps 21 to 26 correspond to drive stop means.

  In step 27, it is determined whether or not a predetermined time has elapsed since the operation of the electric motor 21 was stopped. If it is determined that the predetermined time has not elapsed, the determination in step 27 is repeated, and if it is determined that the predetermined time has elapsed, the process proceeds to step 28. Here, the predetermined time is a sufficient time until the piston 28 is pushed back and naturally stops.

  In step 28, the clearance variable is reset. That is, this position where the piston 28 naturally stops is set to the initial value of the clearance X0. This step 28 corresponds to the piston initial position adjusting means.

  Here, the motor current command value when the operation of the electric motor 21 is stopped is substantially constant. That is, the pressing force for pressing the piston 28 against the non-rotating disk 4 by the electric motor 21 is substantially constant. Accordingly, the distance that is separated from when the operation of the electric motor 21 is stopped to when the piston 28 is pushed back and then stopped is substantially constant. Therefore, if the clearance X0 at this time is set as an initial value, the clearance X0 can always be kept substantially constant.

  According to the above embodiment, in the electric brake 100, the operation of the electric motor 21 is stopped from the state where the piston 28 is pressed against the non-rotating disk 4 with a predetermined pressing force. Then, the position where the piston 28 is pushed back by the reaction force and stopped is detected, and the initial value of the clearance X0 is set based on the detected value. At this time, the clearance X0 is a substantially constant value due to a predetermined pressing force.

  Therefore, the clearance X0 between the non-rotating disk 4 and the piston 28 can be adjusted to be constant without providing a rotation angle detection means.

  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 according to the present invention is not limited to one that brakes wheels for an aircraft, but can be used for other types of electric brakes such as those provided in other vehicles and machines, and caliper types.

DESCRIPTION OF SYMBOLS 100 Electric brake 3 Torque tube 4 Non-rotating disk 6 Rotating disk 21 Electric motor 24 Reduction mechanism 27 Ball screw / nut mechanism 28 Piston 30 Controller

Claims (4)

A rotating disk that rotates with the wheels;
A wheel control means supported non-rotatably with respect to the airframe and displaceable toward the rotating disk;
A piston capable of advancing and retracting toward the wheel control means;
An electric actuator for linearly moving the piston;
A controller for controlling the operation of the electric actuator,
An electric brake that generates a braking torque by the electric actuator pressing the wheel control means toward the rotating disk via the piston;
Drive stop means for stopping the operation of the electric actuator after driving until the piston is pressed against the wheel control means at the time of adjusting the initial position of the piston;
A piston initial position adjusting means for adjusting an initial position of the piston based on a position where the piston is stopped by being pushed back by a reaction force when the operation of the electric actuator is stopped;
The electric brake according to claim 1, wherein the piston initial position adjusting means moves the piston from the stop position toward the wheel control means by a predetermined stroke to obtain an initial position of the piston.   The electric brake according to claim 1, wherein the wheel control means is a non-rotating disk.   The electric brake according to claim 1 or 2, further comprising piston stop position detecting means for detecting a position where the piston stops. A rotating disk that rotates with the wheels;
A wheel control means supported non-rotatably with respect to the airframe and displaceable toward the rotating disk;
A piston capable of advancing and retracting toward the wheel control means,
A method for adjusting an initial position of a piston of an electric brake, wherein the piston generates a braking torque by pressing the braking means toward the rotating disk,
The piston is pressed against the wheel control means and stopped;
An electric motor characterized in that the piston is moved by a predetermined stroke from the position where the piston is pushed back and stopped by a reaction force when the piston is stopped to a predetermined stroke toward the wheel control means. Brake piston initial position adjustment method.

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