CN110725879A - Disc brake based on magnetostrictive material and control method thereof - Google Patents

Abstract

The invention discloses a magnetostrictive material-based disc brake and a control method thereof. A new type of magnetostrictive intelligent material is adopted in the disc brake, and the material can be stretched and deformed under the influence of a magnetic field. and generate enough thrust. In the present invention, it is used in the disc brake, as a brake driver to replace the original hydraulic pump structure, and the double magnetic hysteresis telescopic driver is used to drive the two brake pistons of the fixed caliper disc brake respectively. The volume of fixed-caliper disc brakes is increased, so that they can be used in cars. In addition, the brake cancels the hydraulic oil circuit, which simplifies the system structure and saves the cost.

Description

A magnetostrictive material-based disc brake and its control method

technical field

The invention belongs to the technical field of automobile mechanical brakes, and specifically refers to a disc brake based on magnetostrictive materials and a control method thereof.

Background technique

The rotating element in the friction pair of the disc brake is a metal disc working on the end face, called the brake disc; the friction element clamps the brake disc from both sides to generate braking. There are various structural forms of fixed elements, and disc brakes can be roughly divided into two types: caliper disc type and full disc type.

The existing disc brakes on the market are mainly hydraulic type, controlled by hydraulic pressure, and the main components are brake disc, wheel cylinder, brake caliper, oil pipe, brake block, etc. The disc brake has fast heat dissipation, light weight, simple structure and convenient adjustment. Especially under high load, it has good high temperature resistance, stable braking effect, and is not afraid of muddy water invasion, so it can drive in winter and harsh road conditions.

At present, the research on disc brakes has achieved a lot of results. For example, the Chinese invention patent application number is 201410785712.9, titled "a disc brake with a giant magnetostrictive boosting function and its method", using the magnetostrictive phenomenon of the magnetostrictive material to propose a magnetostrictive The disc brake with the afterburner function has the characteristics of simple and reliable structure, good compatibility with the existing braking system, and does not affect the normal operation of the ABS; it can reduce the braking distance during emergency braking and at the same time improve driving safety; China The invention patent application number is 201610902190.5, and the name is "a hydraulic self-energizing disc brake", which provides a set of boosting device on the basis of the existing floating caliper disc brake to realize the braking process of the automobile. The hydraulic self-energizing disc brake with two-way boosting action and improving braking efficiency; the Chinese invention patent application number is 201811214157.9, the name is "a magnetic fluid disc brake", which uses the smart material magnetic fluid to provide a different kind of traditional The disc brake in braking mode combines hydraulic braking with magnetic fluid regulating braking to realize multi-stage braking mode.

From the above research on disc brakes, although disc brakes have many advantages, the problems of high cost, complex brake structure, complex hydraulic system layout and hydraulic hysteresis have not been solved.

Magnetostrictive material is a new type of smart material that can expand and contract along the direction of magnetization when magnetized in a magnetic field, and generate a large thrust when magnetostrictive strain occurs. If an energized coil is used as the magnetic field source, the change in the size of the magnetostrictive material can be controlled when the current through the coil changes or the distance from the magnet changes. Because they are controlled by the magnetic field with fast response time, good frequency characteristics, high energy density, large coupling coefficient, and have sensing and driving functions, they have broad application prospects in many fields.

SUMMARY OF THE INVENTION

In view of the above-mentioned deficiencies of the prior art, the purpose of the present invention is to provide a magnetostrictive material-based disc brake and a control method thereof, so as to solve the problems of high cost, complex brake structure, The hydraulic system is complicated in layout and hydraulic hysteresis. The invention takes advantage of the advantages of the new smart material magnetostrictive material, such as fast response time under magnetic field control, good frequency characteristics, high energy density, and large thrust generated during deformation. By controlling the current in the energized coil To control the change of the magnetic field and realize the control of the expansion and contraction of the magnetostrictive material, it is used as a brake driver to replace the original hydraulic drive, which improves the response speed of the brake and removes the hydraulic system, which greatly simplifies the braking system and the brake. structure, saving costs.

For achieving the above object, the technical scheme adopted in the present invention is as follows:

A magnetostrictive material-based disc brake of the present invention comprises: a brake assembly, a left brake driver, a right brake driver and a force and displacement transmission module;

The brake assembly includes: a brake caliper body, a guide pin, a left brake pad back plate, a left brake pad, a left piston, a right piston, a rubber ring, a right brake pad, a right brake pad back plate and brake disc;

The brake caliper body is fixed on the steering knuckle of the front axle of the car, and the left brake driver and the right brake driver are installed on it;

The brake disc is fixed on the wheel hub of the car and extends between the left brake pad and the right brake pad;

The left brake pad back plate and the right brake pad back plate are respectively connected with the left piston and the right piston, are suspended on the guide pin, and can move along the guide pin; the left brake pad and the right brake pad They are respectively fixed on the left brake block backplane and the right brake block backplane;

Rubber rings are respectively embedded in the trapezoidal section ring grooves on the inner walls of the holes of the left piston and the right piston, and the rubber rings are used to return the brakes when the braking ends;

The left brake driver and the right brake driver both include: a driver housing, a giant magnetostrictive rod, an excitation coil, a degaussing coil, a magnetic isolation liner and a magnetic isolation top cover;

The input end of the giant magnetostrictive rod is fixed at the bottom end inside the driver housing;

Both the excitation coil and the demagnetization coil are wound on the giant magnetostrictive rod;

The magnetic isolation gasket is closely attached to the inner side of the driver housing; the magnetic isolation top cover is screwed on the top of the left brake driver and the right brake driver, and together with the magnetic isolation gasket, isolates the influence of the magnetic field on the outside;

The force and displacement transmission module is used to transmit the force and displacement output by the left brake driver and the right brake driver, and includes: a giant magnetostrictive rod, a transmission rod, a piston push rod and a support pin;

the support pins are fixed on both sides of the brake caliper body;

The middle part of the transmission rod is hinged on the support pin, the lower end is hinged with the input end of the piston push rod, and the upper end of the transmission rod is hinged with the output end of the giant magnetostrictive rod;

The output end of the piston push rod is fixedly connected with the piston.

Further, sliding grooves are respectively opened on the left and right sides of the brake caliper body for installing the left brake driver and the right brake driver.

Further, the left brake driver and the right brake driver are fixed on the brake caliper body by fixing screws.

Further, the brake further includes: an adjusting pad, which is used in cooperation with the fixing screw, and is used for adjusting the positions of the left brake driver and the right brake driver.

Further, the cross section of the giant magnetostrictive rod is circular, and the length should be greater than 5 cm and the diameter should be greater than 10 mm.

Further, the material used for the giant magnetostrictive rod should be a giant magnetostrictive material with a magnetostrictive coefficient of not less than 2000 ppm.

Further, the section of the driver housing is ⊥-shaped.

Further, the two brake drivers have the same internal arrangement and are symmetrically installed at the front and rear of the upper part of the brake caliper body.

Further, one wire is used for the excitation coils in the two brake drivers, the wires in the excitation coils are arranged exactly the same, and the currents of the two excitation coils are in the same direction relative to the brake driver after the current is applied.

Further, one wire is used for the degaussing coils in the two brake drivers, the wires in the degaussing coils are arranged exactly the same, and the currents of the two degaussing coils are in the same direction relative to the brake driver after current is applied.

The present invention also provides a method for controlling a disc brake based on magnetostrictive materials, comprising the following steps:

(1) When the brake pedal is pressed for braking, the vehicle status information and pedal information are collected, and the information is transmitted to the electronic control unit (ECU);

(2) The electronic control unit receives the vehicle status information and pedal information, obtains the required target braking force after processing, and then calculates the current required by the excitation coil according to the required target braking force, and adjusts the current to the desired target braking force. The current value needs to be input into the excitation coil;

(3) The electronic control unit adjusts the current in the excitation coil according to the working state of the brake pedal to change the magnetic field strength in the excitation coil, so that the giant magnetostrictive rods in the two brake drivers are deformed and output all required braking force;

(4) At the end of braking, the electronic control unit controls the excitation coil to be powered off, and the degaussing coils in the two brake drivers pass the current in the opposite direction (relative to the drive structure) to the current passed before the excitation coil, eliminating the magnetic field and exceeding the The magnetostrictive rod returns to its original length and stops braking.

Preferably, the vehicle state information includes: a vehicle speed signal and a wheel speed signal.

Preferably, the pedal information is a pedal displacement signal and a pedal speed signal.

Preferably, when calculating the current in the excitation coil in the step (2), it is only necessary to calculate the current required in the excitation coil in a single brake driver according to half of the required target braking force, which is the required input current size.

Preferably, the force and the displacement output by the two brake drivers during the braking process in the step (3) should be exactly the same, which are respectively half of the required braking force and displacement.

Preferably, in the step (2), the formula used to calculate the braking force required to be output by the giant magnetostrictive rod in a single braking driver is:

The formula for calculating the amount of deformation of the giant magnetostrictive rod required to output the required braking force is:

The formula to calculate the magnitude of the current input in the desired coil is:

In the formula, F _c is the output force of the giant magnetostrictive rod of the required single brake driver; F _z is the required braking force; ε is the deformation amount of the giant magnetostrictive rod of the required single brake driver; E is the giant magnetostrictive rod The elastic modulus of the magnetostrictive rod; r is the radius of the giant magnetostrictive rod; π is the pi constant; I is the current in the required coil; L is the length of the coiled part of the giant magnetostrictive rod; a is the characteristic constant (depending on due to material properties); μ ₀ is the vacuum permeability; N is the number of turns of the coil.

Preferably, the step (3) further includes: in the braking force adjustment process, if the braking force needs to be reduced, the degaussing coil is fed with a current opposite to the excitation coil to eliminate the influence of the hysteresis phenomenon on the braking force.

Beneficial effects of the present invention:

Compared with the existing disc brake, the present invention adopts the method of controlling the magnetostrictive deformation by controlling the current of the energized coil, realizes the braking drive, uses the current as the signal transmission medium, and makes the electrification of the automobile braking system easier to realize.

Since the invention cancels the hydraulic oil circuit, the designed disc brake retains the advantages of the traditional disc brake and greatly simplifies the structure of the braking system and the brake.

The core of the brake driver of the present invention is a magnetostrictive material, so its own high response rate is also inherited into the brake, which greatly improves the response rate of the brake.

Description of drawings

Fig. 1 is the front view of the disc brake based on magnetostrictive material of the present invention;

Fig. 2 is the top view of the disc brake based on magnetostrictive material of the present invention;

Fig. 3 is the side view of the disc brake based on magnetostrictive material of the present invention;

4 is a schematic cross-sectional view of the driver A-A of the present invention;

Fig. 5 is the flow chart of the disc brake control method of the present invention;

6 is a schematic structural diagram of the present invention applied to a floating caliper disc brake;

In the figure, 1-brake caliper body, 2-guide pin, 3-left brake pad back plate, 4-left brake pad, 5-left piston, 6-rubber ring, 7-support pin, 8-right Brake pad, 9- Right brake pad back plate, 10- Brake disc, 11- Right piston, 12- Driver housing, 13- Magnetic isolation pad, 14- Giant magnetostrictive rod, 15- Magnetic isolation Top cover, 16-drive rod, 17-piston push rod, 18-adjusting spacer, 19-left brake driver, 20-fixing screw, 21-excitation coil, 22-degaussing coil, 23-right brake driver , 24-chutes.

Detailed ways

In order to facilitate the understanding of those skilled in the art, the present invention will be further described below with reference to the embodiments and the accompanying drawings, and the contents mentioned in the embodiments are not intended to limit the present invention.

1 to 4, a magnetostrictive material-based disc brake of the present invention includes: a brake assembly, a left brake driver 19, a right brake driver 23 and a force and displacement transmission module;

The brake assembly includes: brake caliper body 1, guide pin 2, left brake pad back plate 3, left brake pad 4, left piston 5, right piston 11, rubber ring 6, right brake pad 8 , Right brake pad back plate 9 and brake disc 10;

The brake caliper body 1 is fixed on the steering knuckle of the front axle of the automobile, and a left brake driver 19 and a right brake driver 23 are installed on it;

The brake disc 10 is fixed on the wheel hub of the automobile, and extends between the left brake pad 4 and the right brake pad 8;

The left brake pad back plate 3 and the right brake pad back plate 9 are respectively connected with the left piston 5 and the right piston 11, are suspended on the guide pin 2, and can move along the guide pin 2; The brake block 4 and the right brake block 8 are respectively fixed on the left brake block back plate 3 and the right brake block back plate 9;

Rubber rings 6 are respectively embedded in the trapezoidal section ring grooves on the inner walls of the holes of the left side piston 5 and the right side piston 11, and the rubber rings 6 are used to return the brakes when the braking ends;

The left brake driver 19 and the right brake driver 23 both include: a driver housing 12, a giant magnetostrictive rod 14, an excitation coil 21, a degaussing coil 22, a magnetic isolation pad 13 and a magnetic isolation top cover 15;

The input end of the giant magnetostrictive rod 14 is fixed at the bottom end inside the driver housing 12;

The excitation coil 21 and the degaussing coil 22 are both wound on the giant magnetostrictive rod 14;

The magnetic isolation gasket 13 is closely attached to the inside of the driver housing 12 ; the magnetic isolation top cover 15 is screwed on the top of the left brake driver 19 and the right brake driver 23 , and is isolated from the magnetic isolation gasket 13 . The influence of the magnetic field on the outside;

The force and displacement transmission module is used to transmit the force and displacement output by the left brake driver 19 and the right brake driver 23, and includes: a giant magnetostrictive rod 14, a transmission rod 16, a piston push rod 17 and a support pin 7;

The support pins 7 are fixed on both sides of the brake caliper body 1;

The middle of the transmission rod 16 is hinged on the support pin 7, the lower end is hinged with the input end of the piston push rod 17, and the upper end of the transmission rod 16 is hinged with the output end of the giant magnetostrictive rod 14;

The output end of the piston push rod 17 is fixedly connected with the piston.

The left and right sides of the brake caliper body 1 are respectively provided with sliding grooves 24 for installing the left brake driver 19 and the right brake driver 23 .

The left brake driver 19 and the right brake driver 23 are fixed on the brake caliper body 1 by fixing screws 20 .

The brake further includes an adjusting pad 18 , which is used in cooperation with the fixing screw 20 to adjust the positions of the left brake driver 19 and the right brake driver 23 .

The cross section of the giant magnetostrictive rod 14 is circular, and the length should be greater than 5 cm and the diameter should be greater than 10 mm.

The material used for the giant magnetostrictive rod 14 should be a giant magnetostrictive material with a magnetostrictive coefficient of not less than 2000 ppm.

The section of the driver housing 12 is ⊥-shaped.

The two brake drivers have the same internal arrangement and are symmetrically installed at the front and rear of the upper part of the brake caliper body.

The excitation coils 21 in the two brake drivers use one wire, the wires in the excitation coils are arranged exactly the same, and the currents of the two excitation coils are in the same direction relative to the brake driver after current is applied.

The degaussing coils 22 in the two brake drivers use one wire, the wires in the degaussing coils are arranged exactly the same, and the currents of the two degaussing coils are in the same direction relative to the brake driver after current is applied.

Referring to FIG. 5 , the present embodiment also provides the control method for the above-mentioned disc brake, based on the above-mentioned system, including the following steps:

(1) When the driver steps on the brake pedal to brake, the sensor collects the pedal displacement signal 26, the pedal speed signal 27, the vehicle speed signal 28, the wheel speed signal 29 and the braking force signal 25, and transmits the collected information to the ECU30;

(2) The ECU 30 (electronic control unit) receives the pedal displacement signal 26, the pedal speed signal 27, the vehicle speed signal 28, and the wheel speed signal 29, obtains the required target braking force after processing, and then calculates the required target braking force according to the required target braking force. The current size required by the excitation coil 21; and the current is adjusted to the required current value and input into the excitation coil.

(3) According to the operation of the brake pedal by the driver, the ECU changes the magnetic field strength in the excitation coil 21 by adjusting the current in the excitation coil 21, so that the supermagnetism in the left brake driver 19 and the right brake driver 23 The telescopic rods 14 are all deformed and output the required braking force. Then, the braking force output by the left brake driver 19 and the right brake driver 23 acts on the left and right pistons 5 and 11 through the transmission rod 16 and the piston push rod 17, so that the two pistons move to the brake disc 10 and pass through The left brake pad back plate 3 and the right brake pad back plate 9 press the left brake pad 4 and the right brake pad 8 against the brake disc 10 to complete the braking.

(4) At the end of braking, the ECU controls the excitation coil 21 to be powered off, and the degaussing coils 22 in the two brake drivers are fed with a current in the opposite direction (relative to the structure of the brake driver) to the current in the opposite direction (relative to the structure of the brake driver) before the excitation coil 21 to eliminate the magnetic field. , the giant magnetostrictive rod 14 restores its original length. At the same time, as the rubber ring 6 and the giant magnetostrictive rod 14 return to their original state, the left piston 5 and the right piston 11 together with the left brake pad back plate 3 and the right brake pad back plate 9 and the left brake pad 4 and The right brake block 8 is returned to its original position together, and the braking is completed.

The pedal information is the pedal displacement signal 26 and the pedal speed signal 27 , and the vehicle status signal is the vehicle speed signal 28 and the wheel speed signal 29 .

Wherein, when calculating the current size in the excitation coil 21, it is only necessary to calculate the current size required in the excitation coil 21 in a single brake driver according to half of the required target braking force, which is the current size that needs to be input;

Wherein, the output force and displacement of the left brake driver 19 and the right brake driver 23 during the braking process should be exactly the same, which are respectively half of the required braking force and displacement;

Wherein, the formula used for calculating the braking force required to output the giant magnetostrictive rod in the single braking driver in the step (2) is:

The formula for calculating the amount of deformation of the giant magnetostrictive rod required to output the required braking force is:

The formula to calculate the magnitude of the current input in the desired coil is:

In the formula, F _c is the output force of the giant magnetostrictive rod in the required single brake driver; F _z is the required braking force; ε is the deformation amount of the giant magnetostrictive rod in the required single brake driver; E is the giant magnetostrictive rod The elastic modulus of the magnetostrictive rod; r is the radius of the giant magnetostrictive rod; π is the pi constant; I is the current in the required coil; L is the length of the coiled part of the giant magnetostrictive rod; a is the characteristic constant (depending on due to material properties); μ ₀ is the vacuum permeability; N is the number of turns of the coil.

Wherein, the step (3) further includes: in the braking force adjustment process, if the braking force needs to be reduced, the degaussing coil is fed with a current opposite to the excitation coil to eliminate the influence of the hysteresis phenomenon on the braking force.

As shown in FIG. 6 , the present invention can also be applied to floating caliper disc brakes in addition to fixed caliper disc brakes.

There are many specific application ways of the present invention, and the above are only the preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, without departing from the principle of the present invention, several improvements can be made. These Improvements should also be considered as the protection scope of the present invention.

Claims (10)

1. A disc brake based on magnetostrictive material, characterized in that it comprises: the brake assembly, the left brake driver, the right brake driver and the force and displacement transmission module;

the brake assembly includes: the brake caliper comprises a brake caliper body, a guide pin, a left brake block back plate, a left brake block, a left piston, a right piston, a rubber ring, a right brake block back plate and a brake disc;

the brake caliper body is fixed on a steering knuckle of a front axle of the automobile, and a left brake driver and a right brake driver are installed on the brake caliper body;

the brake disc is fixed on a hub of the automobile and extends into a space between the left brake block and the right brake block;

the left brake block back plate and the right brake block back plate are respectively connected with the left piston and the right piston, are suspended on the guide pins and can move along the guide pins; the left brake block and the right brake block are respectively fixed on a left brake block back plate and a right brake block back plate;

rubber rings are respectively embedded in the annular grooves with the trapezoidal sections on the inner walls of the holes of the left piston and the right piston, and the rubber rings are used for returning the brake when braking is finished;

the left and right brake actuators each include: the device comprises a driver shell, a giant magnetostrictive rod, an excitation coil, a demagnetizing coil, a magnetic isolation liner and a magnetic isolation top cover;

the input end of the giant magnetostrictive rod is fixed at the bottom end inside the driver shell;

the excitation coil and the demagnetizing coil are wound on the giant magnetostrictive rod;

the magnetic isolation gasket is tightly attached to the inner side of the driver shell; the magnetic isolation top cover is rotatably arranged at the top ends of the left brake driver and the right brake driver and isolates the influence of a magnetic field on the outside together with the magnetic isolation liner;

the force and displacement transmission module is used for transmitting force and displacement output by the left brake driver and the right brake driver, and comprises: the giant magnetostrictive rod, the transmission rod, the piston push rod and the support pin;

the supporting pins are fixed on two sides of the brake caliper body;

the middle part of the transmission rod is hinged on the supporting pin, the lower end of the transmission rod is hinged with the input end of the piston push rod, and the upper end of the transmission rod is hinged with the output end of the giant magnetostrictive rod;

the output end of the piston push rod is fixedly connected with the piston.

2. The disc brake based on magnetostrictive materials according to claim 1, characterized in that the left and right sides of the caliper body are respectively provided with a sliding groove for mounting the left and right brake actuators.

3. The magnetostrictive material-based disc brake according to claim 1, characterized in that the left and right brake actuators are fixed to the caliper body by means of fixing screws.

4. The magnetostrictive material-based disc brake according to claim 3, characterized in that the brake further comprises: and the adjusting shim is matched with the fixing screw for use and is used for adjusting the positions of the left brake driver and the right brake driver.

5. The disc brake based on magnetostrictive materials according to claim 1, characterized in that the number of the conducting wires used for the exciting coils in the two brake actuators is one, the arrangement of the conducting wires in the exciting coils is identical, and the direction of the currents of the two exciting coils relative to the brake actuators is identical after the currents are supplied.

6. The disc brake based on magnetostrictive materials according to claim 1, characterized in that the number of the wires used for the degaussing coils in the two brake actuators is one, the arrangement of the wires in the degaussing coils is identical, and the direction of the current of the degaussing coils relative to the brake actuators is identical after the current is applied.

7. A method for controlling a disc brake based on magnetostrictive material, based on a brake as claimed in any one of claims 1-6, characterized in that it comprises the following steps:

(1) when a brake pedal is stepped down for braking, vehicle state information and pedal information are collected and transmitted to an electronic control unit;

(2) the electronic control unit receives the vehicle state information and the pedal information, obtains the required target braking force after processing, calculates the current required by the magnet exciting coil according to the required target braking force, adjusts the current to the required current value and inputs the current value into the magnet exciting coil;

(3) the electronic control unit adjusts the current in the excitation coil according to the working state of the brake pedal to change the magnetic field intensity in the excitation coil, so that the giant magnetostrictive rods in the two brake drivers are deformed and output the required braking force;

(4) when braking is finished, the electronic control unit controls the exciting coil to be powered off, the demagnetizing coils in the two brake drivers are connected with current in the direction opposite to the current connected before the exciting coil, the magnetic field is eliminated, the giant magnetostrictive rod restores to the original length, and braking is finished.

8. The method of claim 7, wherein the step (2) of calculating the current magnitude of the exciting coil is performed by calculating the current magnitude required by the exciting coil in a single brake actuator according to only half of the required target braking force, that is, the current magnitude required to be input.

9. The method of claim 7, wherein the force and displacement output by the two brake actuators during braking in step (3) are exactly the same as half the required braking force and displacement, respectively.

10. The method for controlling a disc brake based on magnetostrictive materials according to claim 7, characterized in that the formula for calculating the braking force required to be output by the magnetostrictive rod in a single brake actuator in step (2) is as follows:

the formula for calculating the deformation of the giant magnetostrictive rod required by outputting the required braking force is as follows:

the formula for calculating the magnitude of the current input into the required coil is:

in the formula, F_cThe output force of the giant magnetostrictive rod is required for a single braking actuator; f_zThe required braking force is obtained; epsilon is the deformation of the needed single brake driver giant magnetostrictive rod; e is the elastic modulus of the giant magnetostrictive rod; r is the radius of the giant magnetostrictive rod; pi is a circumferential rate constant; i is the current in the required coil; l is the length of the coil part wound by the giant magnetostrictive rod; a is a characteristic constant; mu.s₀Is a vacuum magnetic conductivity; and N is the number of coil turns.

Images