A drum-type brake-by-wire system based on magnetostrictive material and control method thereof

Abstract

The present invention discloses a drum-type wire-controlled brake system based on magnetostrictive materials and a control method thereof; the system comprises a brake pedal module, a brake, a wheel module, a power module, a parking brake module, and a control module. The system designs a driving structure by utilizing the characteristics of magnetostrictive materials, controls the length of the super magnetostrictive rod in the brake driver by controlling the current in the excitation coil, and relies on a displacement amplification mechanism to press the brake shoe against the inner side of the brake drum to complete the braking. Since the traditional hydraulic drive is replaced by the magnetostrictive drive, the drawbacks of the electronically controlled hydraulic brake system are eliminated. Compared with the disc-type wire-controlled brake system, the present invention can greatly save the cost of the brake system. In addition, since the present invention has a simple structure, a small volume and a light weight, it is conducive to the lightweighting of the automobile and meets the needs of the market.

Description

Technical Field

[0001] The present invention belongs to the technical field of vehicle brake-by-wire systems, and specifically refers to a drum-type brake-by-wire system based on magnetostrictive materials and a control method thereof. Background Art

[0002] Magnetostrictive materials are a type of material that has the function of mutual conversion between electromagnetic energy and mechanical energy. Rare earth-iron alloy materials with giant magnetostrictive properties at room temperature that began to appear in the 1970s have high energy density, large coupling coefficient, and sensing and driving functions. Therefore, they have been used and developed more and more widely in the field of smart materials as smart materials or corresponding devices. For example, the Chinese invention patent application number is 201811307405.4, and the patent name is "Hot-mounted giant magnetostrictive ultrasonic handle", which provides a hot-mounted giant magnetostrictive ultrasonic handle, which solves the problem of improper ultrasonic handle design affecting processing accuracy; the Chinese invention patent application number is 201210424245.8, and the patent name is "A magnetostrictive follow-up steering mechanism", which provides a magnetostrictive follow-up steering mechanism, which uses the magnetostrictive principle to make the illumination direction of the headlights consistent with the current driving direction of the vehicle, ensuring driving safety at night. It improves the disadvantages of the previous follow-up steering system adjustment method on the lamp, such as complex mechanism, many parts, poor reliability, and high cost.

[0003] Brake-by-wire systems are divided into hydraulic brake-by-wire systems and mechanical brake-by-wire systems. Hydraulic brake-by-wire systems have large mass and are difficult to implement electronic control. Mechanical brake-by-wire systems have no brake lines connected to the system, have a simple structure, and are small in size. Signals are transmitted electrically, are responsive, and reduce braking distances. They operate stably and are easy to maintain. There are no hydraulic oil lines, so there is no hydraulic oil leakage problem. They are directly controlled by an electronic control unit, making it easy to implement various functions of traditional brake systems. However, the addition of four brake drive motors increases the cost of the electronic mechanical brake system.

[0004] Drum brakes are the earliest brakes and are cheaper than disc brakes. However, due to their poor braking performance, long reaction time and low real-time performance, they have been gradually replaced by disc brakes over time and are now often used on heavy vehicles.

[0005] In general, the commonly used braking systems on the market have the following disadvantages: the hydraulic system is difficult to control electronically, not easy to integrate with other electronic control systems, and not conducive to lightweighting; hydraulic or pneumatic drive causes lag in drum brakes; the layout of oil and air circuits makes the brakes more complicated; traditional low-cost drum brake systems are difficult to control by wire. Summary of the invention

[0006] In view of the above-mentioned deficiencies of the prior art, the purpose of the present invention is to combine magnetostrictive materials with brake systems, and provide a drum-type wire-controlled brake system based on magnetostrictive materials and a control method thereof. The present invention utilizes the characteristics of magnetostrictive smart materials such as fast response, good frequency characteristics, and high energy density to design a new drive structure as the driving source of the drum brake system, and realizes drive control by controlling the external magnetic field intensity. After the magnetostrictive material replaces the traditional hydraulic drive, the system structure is simplified, the system response characteristics are improved, and the wire control of the drum brake system can be realized.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A drum-type brake-by-wire system based on magnetostrictive material of the present invention comprises: a brake pedal module, a brake, a wheel module, a power module, a parking brake module and a control module;

[0009] The brake pedal module comprises: a brake pedal, a pedal bracket, a pedal shaft, a connecting rod and a pedal feeling simulator;

[0010] The input end of the pedal shaft is fixedly connected to the output end of the brake pedal, and the output end is fixedly connected to the input end of the connecting rod;

[0011] The lower end of the pedal feel simulator is fixed to the pedal bracket;

[0012] The pedal feeling simulator comprises: a push rod, a simulator housing, an outer ring spring, an inner ring spring, an upper end cover, a lower end cover, an adjustment gasket and a base;

[0013] The upper and lower end covers are screwed onto the upper and lower ends of the pedal feeling simulator respectively;

[0014] The input end of the push rod is hinged to the output end of the connecting rod;

[0015] The outer coil spring and the inner coil spring are located inside the simulator housing and are respectively mounted on the base to generate simulated pedal force;

[0016] The adjustment gasket is located between the pedal feel simulator and the pedal bracket and is used to adjust the preload force of the pedal feel simulator;

[0017] The brake comprises: a first brake shoe, a second brake shoe, a brake drum, a brake base plate, a brake shoe return spring, a friction lining, a brake driver, a displacement amplification mechanism, a first support pin A and a second support pin A, a first support pin B and a second support pin B, a first support pin C and a second support pin C, a first limit pin D, and a second limit pin D;

[0018] The first support pin A and the second support pin A, the first support pin B and the second support pin B and the first limit pin D and the second limit pin D are fixed on the brake bottom plate;

[0019] A first support pin C and a second support pin C are fixed to the first brake shoe and the second brake shoe respectively;

[0020] When the first brake shoe and the second brake shoe are not braking, their upper ends are pulled against the first limit pin D and the second limit pin D by the brake shoe return spring, and their lower ends are hinged on the first support pin A and the second support pin A;

[0021] The brake drum is fixed to the wheel hub of each wheel of the vehicle and rotates with the wheel;

[0022] The front and rear ends of the brake shoe return spring are respectively hooked on the first supporting pin C and the second supporting pin C;

[0023] The friction linings are respectively mounted on the curved surfaces of the first brake shoe and the second brake shoe facing the inner side of the brake drum;

[0024] The displacement amplification mechanism includes: giant magnetostrictive rods Ⅰ, Ⅱ and driven rods Ⅰ, Ⅱ;

[0025] The lower ends of the driven rods I and II are hinged on the first supporting pin B and the second supporting pin B, the middle parts are hinged on the output ends of the giant magnetostrictive rods I and II, and the upper ends are hinged on the first supporting pin C and the second supporting pin C;

[0026] The brake driver comprises: a driver housing, a driver bracket, giant magnetostrictive rods I and II, an excitation coil, a degaussing coil, a magnetic isolation pad and a fixed baffle;

[0027] The bottom end of the driver housing is connected to the fixed baffle, and the middle part is placed on the driver bracket;

[0028] The drive bracket is fixed to the brake base plate;

[0029] The input ends of the giant magnetostrictive rods I and II are respectively fixed at the bottom ends inside the driver housing, and the output ends are hinged to the middle parts of the driven rods I and II;

[0030] The excitation coil and the degaussing coil are both wound around the giant magnetostrictive rods I and II, and the displacement of the giant magnetostrictive rods I and II is controlled by controlling the current in the excitation coil, and the hysteresis phenomenon is eliminated by controlling the current in the degaussing coil;

[0031] The magnetic isolation pad is closely attached to the inner side of the driver housing to isolate the influence of the magnetic field on the outside and the influence of the external magnetic field on the inside;

[0032] The fixed baffle is fixed on the brake bottom plate;

[0033] The wheel module includes: a left front wheel, a left rear wheel, a right front wheel, and a right rear wheel;

[0034] The control module includes: an electronic control unit, a pedal displacement sensor, a vehicle speed sensor, a wheel speed sensor and braking force sensors I and II;

[0035] A pedal displacement sensor is mounted on the push rod and is electrically connected to the electronic control unit to obtain the pedal displacement signal and transmit the signal to the electronic control unit;

[0036] The vehicle speed sensor is installed in the axle housing of the vehicle's drive axle or in the gearbox housing, and is used to obtain the vehicle speed signal and transmit it to the electronic control unit;

[0037] Braking force sensors I and II are respectively mounted on the giant magnetostrictive rods I and II and are electrically connected to the electronic control unit;

[0038] The wheel speed sensor is installed on the wheel hub of each wheel, and is used to obtain the wheel speed signal and transmit the signal to the electronic control unit;

[0039] The power supply module includes: a power supply and a current regulating module;

[0040] The power supply is electrically connected to the current regulation module and is used to supply power to the system;

[0041] The current regulating module is used to receive the control current signal output by the electronic control unit, and input the current into the brake driver after regulating the current, and feed back the current value in the excitation coil to the electronic control unit;

[0042] The parking brake module comprises: a hand pull rod, a pull rod base, a parking brake cable, a hand pull rod return spring, a parking brake rod, a parking brake friction block, and a parking brake friction block return spring;

[0043] The input end of the parking brake cable is connected to the hand lever, and the output end is connected to the parking brake lever;

[0044] The tie rod base is fixed to the vehicle body behind the shift lever;

[0045] The hand pull rod return spring is located at the connection between the hand pull rod and the pull rod base, and is used for returning the hand pull rod;

[0046] The input end of the parking brake lever is hinged to the output end of the parking brake cable, and the output end thereof is hinged to the parking brake friction block;

[0047] The parking brake friction block is limited to the middle of the first supporting pin D and the second supporting pin D;

[0048] The lower end of the parking brake friction block return spring is fixed on the driver bracket, and the upper end is connected to the parking brake friction block for returning the parking brake friction block.

[0049] Preferably, the brake actuator is installed one at the inner side of the first brake shoe and the second brake shoe respectively, and the two brake actuators are of equal length and are placed in parallel up and down and are powered by the power supply.

[0050] Preferably, the number of the brakes is four, namely a left front brake, a right front brake, a left rear brake, and a right rear brake.

[0051] Preferably, the two brake actuators in each brake are completely identical.

[0052] Preferably, each wheel is equipped with a brake, and the left rear brake and the right rear brake are provided with a parking brake module.

[0053] Preferably, the first support pin C and the second support pin C are provided with grooves for limiting the position of the brake shoe return spring.

[0054] Preferably, the brake bracket is placed at the 1 / 2 position of the driver housing.

[0055] Preferably, the outer ring spring is in a natural state when no adjustment gasket is added.

[0056] Preferably, the giant magnetostrictive rod has a circular cross-section, a length greater than 8 cm, and a diameter greater than 10 mm.

[0057] Preferably, the material used for the giant magnetostrictive rod should be a rare earth giant magnetostrictive material with a magnetostriction coefficient of not less than 2000 ppm.

[0058] Preferably, the output end of the giant magnetostrictive rod is hinged at 1 / 2 to 1 / 3 of the lower end of the driven rod.

[0059] Preferably, the two displacement amplification mechanisms have equal amplification ratios.

[0060] Preferably, the excitation coils in the two brake drivers in the brake are wound by the same wire, and the demagnetization coils are also wound by the same wire.

[0061] The present invention also provides a control method for a drum-type brake-by-wire system based on magnetostrictive material, based on the above system, comprising the following steps:

[0062] (1) During normal braking, the brake pedal is depressed, and the pedal displacement sensor, vehicle speed sensor, wheel speed sensor and braking force sensor respectively collect pedal displacement signals, vehicle speed signals, wheel speed signals of each wheel and braking force signals and transmit the signals to the electronic control unit;

[0063] (2) The pedal feel simulator generates feedback force through the deformation of the outer spring and the inner spring, and feeds back the simulated pedal force to the driver through the push rod, the connecting rod and the brake pedal;

[0064] (3) The electronic control unit receives the pedal displacement signal, vehicle speed signal, wheel speed signal and braking force signal collected in the above step (1), calculates the currently required target braking force according to the signals, distributes the braking force to each wheel according to the currently required braking force, calculates the required displacement of the giant magnetostrictive rod in the brake driver of each wheel, and then calculates the required target current signal, and transmits the signal to the current regulation module;

[0065] (4) After receiving the current control signal obtained in the above step (3), the current regulating module regulates the current and inputs it into the brake driver of each brake to control the magnetic field strength attached to the giant magnetostrictive rod, and feeds back the current value in each excitation coil to the electronic control unit;

[0066] (5) Current is input to the brake driver, the magnetic field strength in the excitation coil changes, the giant magnetostrictive rod deforms, and the first brake shoe and the second brake shoe rotate around the first support pin A and the second support pin A respectively through the driven rod. The upper ends of the two brake shoes are separated to both sides so that the friction lining is pressed against the inner surface of the brake drum, completing the braking.

[0067] (6) Release the brake pedal. The electronic control unit adjusts the current in the excitation coil according to the real-time pedal displacement, and controls the current regulation module to pass a current in the opposite direction to the excitation coil into the demagnetization coil to eliminate hysteresis and improve system response until the brake pedal is completely released and the brake is released;

[0068] (7) After the vehicle stops, pull the hand lever to pull the parking brake friction block toward the brake drum through the parking brake cable and the parking brake lever, so that the parking brake friction block is pressed against the inner surface of the brake drum to complete the parking brake;

[0069] (8) When the hand lever returns to its original position, the parking brake friction pad return spring pulls the parking brake friction pad back to its original position, and the hand lever return spring pulls the hand lever back to its original position.

[0070] Preferably, the formula for calculating the output braking force required by each brake driver in the brake in step (3) is:

[0071]

[0072] The formula for calculating the displacement of each giant magnetostrictive rod in the brake is:

[0073]

[0074] The formula for calculating the excitation coil current in the brake is:

[0075]

[0076] In the formula, F ci is the required output braking force of each brake actuator in the brake, where i=1, 2, 3, 4 represent the left front, right front, left rear, and right rear brakes respectively; F zi is the braking force required by the wheel, where i=1,2,3,4 represent the left front, right front, left rear, and right rear wheels respectively; ε i is the deformation of each giant magnetostrictive rod in the required brake, where i = 1, 2, 3, 4 represent the left front, right front, left rear, and right rear brakes respectively; E is the elastic modulus of the giant magnetostrictive rod; r is the radius of the giant magnetostrictive rod; π is the pi constant; I i is the current in the excitation coil of the required brake, where i=1, 2, 3, 4 represent the left front, right front, left rear, and right rear brakes respectively; L is the length of the part of the giant magnetostrictive rod wound with the coil; a is the characteristic constant (depending on the material properties); μ0 is the vacuum permeability; N is the number of coil turns.

[0077] Preferably, the step (5) specifically includes: the braking force F output by the brake driver ci The control adopts the PID closed-loop current control method. The specific steps are as follows:

[0078] (51) The electronic control unit calculates the target braking force F of the current brake actuator according to formula (1): ci_need ;

[0079] (52) The electronic control unit receives the actual braking force signal from the braking force sensor and converts the actual braking force F ci_real and target braking force F ci_need Compare and then calculate the actual braking force F according to formula (4) ci_real and target braking force F ci_need The difference

[0080]

[0081] (53) The error value obtained by formula (4) is used as the input of the current closed-loop control to the controller, and the output model of the controller is:

[0082]

[0083] In the formula, u i (t) is the control quantity output by the electronic control unit; K pi is the proportionality coefficient, T iis the integration constant, T di is the differential constant, u0 is the control constant I i , which can be calculated using formula (2-3).

[0084] Beneficial effects of the present invention:

[0085] 1. The present invention utilizes the characteristics of magnetostrictive smart materials, which have fast response, good frequency characteristics and high energy density.

[0086] 2. The present invention uses magnetostrictive materials to replace traditional hydraulic drive, which simplifies the system structure, improves the system response characteristics, and can realize the wire control of the drum brake system.

[0087] 3. Compared with the disc-type wire-controlled brake system, the present invention can greatly save the cost of the brake system.

[0088] 4. The present invention has a simple structure, small size and light weight, which is beneficial to the lightweighting of vehicles. BRIEF DESCRIPTION OF THE DRAWINGS

[0089] Figure 1 is a structural diagram of the system of the present invention;

[0090] Figure 2 It is a schematic diagram of the structure of the left rear and right rear brakes of the present invention;

[0091] Figure 3 This is a schematic diagram of the structure of the brake driver of the present invention;

[0092] Figure 4 It is a schematic diagram of the left front brake, right front brake and parking brake module of the present invention;

[0093] Figure 5 A schematic diagram of a pedal feel simulator of the present invention;

[0094] Figure 6 This is a flow chart of the control method of the present invention;

[0095] Figure 7 This is a schematic diagram of the PID control principle of the present invention;

[0096] In the figure, 1-left front wheel, 2-left front brake, 3-wheel speed sensor A, 4-pedal shaft, 5-connecting rod, 6-push rod, 7-pedal displacement sensor, 8-pedal feeling simulator, 9-pedal bracket, 10-electronic control unit, 11-power supply, 12-wheel speed sensor B, 13-left rear brake, 14-left rear wheel, 15-vehicle speed sensor, 16-right rear brake, 17-right rear wheel, 18-wheel speed sensor C, 19-current regulation Section module, 20-brake pedal, 21-parking brake cable, 22-pull rod base, 23-hand pull rod return spring, 24-hand pull rod, 25-wheel speed sensor D, 26-right front brake, 27-right front wheel, 28-first support pin C, 29-driven rod Ⅰ, 30-first support pin B, 31-first brake shoe, 32-friction lining, 33-first support pin A, 34-second support pin A, 35-second brake shoe, 36-brake drive Device, 37-magnetostrictive rod Ⅰ, 38-second support pin B, 39-magnetostrictive rod Ⅱ, 40-driven rod Ⅱ, 41-brake drum, 42-brake shoe return spring, 43-second support pin C, 44-second limit pin D, 45-brake bottom plate, 46-first limit pin D, 47-magnetic isolation pad, 48-demagnetization coil, 49-nut, 50-fixed baffle, 51-fixing screw, 52-excitation coil, 53-drive bracket, 54- Driver housing, 55-parking brake friction pad, 56-parking brake friction pad return spring, 57-braking force sensor I, 58-braking force sensor II, 59-parking brake lever, 60-outer ring spring, 61-inner ring spring, 62-adjusting gasket, 63-lower end cover, 64-base, 65-fastening screw, 66-simulator housing, 67-upper end cover, 68-braking force signal 69-pedal displacement signal 70-vehicle speed signal 71-wheel speed signal. DETAILED DESCRIPTION

[0097] In order to facilitate the understanding of those skilled in the art, the present invention is further described below in conjunction with embodiments and drawings. The contents mentioned in the implementation modes are not intended to limit the present invention.

[0098] Reference Figures 1 to 5 The present invention is a drum-type wire-controlled brake system based on magnetostrictive materials, comprising: a brake pedal module, a left front brake 2, a right front brake 26, a left rear brake 13, a right rear brake 16, a wheel module, a power module, a parking brake module and a control module;

[0099] The brake pedal module comprises: a brake pedal 20, a pedal bracket 9, a pedal shaft 4, a connecting rod 5, a fastening screw 65 and a pedal feeling simulator 8;

[0100] The input end of the pedal shaft 4 is fixedly connected to the output end of the brake pedal 20, and the output end is fixedly connected to the input end of the connecting rod 5;

[0101] The lower end of the pedal feeling simulator 8 is fixed to the pedal bracket 9 by a fastening screw 65;

[0102] Reference Figure 5 As shown, the pedal feel simulator 8 includes: a push rod 6, a simulator housing 66, an outer ring spring 60, an inner ring spring 61, an upper end cover 67, a lower end cover 63, an adjustment gasket 62 and a base 64;

[0103] The upper end cover 67 and the lower end cover 63 are screwed onto the upper and lower ends of the pedal feeling simulator 8 respectively;

[0104] The input end of the push rod 6 is hinged to the output end of the connecting rod 5;

[0105] The outer coil spring 60 and the inner coil spring 61 are located inside the simulator housing 66 and are respectively mounted on the base 64 to generate simulated pedal force;

[0106] The adjusting gasket 62 is located between the pedal feeling simulator 8 and the pedal bracket 9 and is used to adjust the preload force of the pedal feeling simulator 8;

[0107] Reference Figure 2 As shown, the four brakes each include: a first brake shoe 31, a second brake shoe 35, a brake drum 41, a brake base plate 45, a brake shoe return spring 42, a friction lining 32, a brake driver 36, a displacement amplification mechanism, a first support pin A33 and a second support pin A34, a first support pin B30 and a second support pin B38, a first support pin C28 and a second support pin C43, a first limit pin D46, and a second limit pin D44;

[0108] The first support pin A33, the second support pin A34, the first support pin B30, the second support pin B38 and the first limit pin D46, the second limit pin D44 are fixed on the brake bottom plate;

[0109] The first support pin C28 and the second support pin C43 are fixed on the first brake shoe 31 and the second brake shoe 35 respectively;

[0110] When the first brake shoe 31 and the second brake shoe 35 are not braking, their upper ends are pulled against the first limit pin D46 and the second limit pin D44 by the brake shoe return spring 42, and their lower ends are hinged to the first support pin A33 and the second support pin A34;

[0111] The brake drum 41 is fixed to the wheel hub of the vehicle wheel and rotates with the wheel;

[0112] The front and rear ends of the brake shoe return spring 42 are respectively hooked on the first support pin C28 and the second support pin C43;

[0113] The friction lining 32 is respectively mounted on the first brake shoe 31 and the second brake shoe 35 on the curved surface facing the inner side of the brake drum 41;

[0114] The displacement amplification mechanism comprises: giant magnetostrictive rods Ⅰ37, Ⅱ39, and driven rods Ⅰ29, Ⅱ40;

[0115] The lower ends of the driven rods Ⅰ29 and Ⅱ40 are hinged on the first supporting pin B30 and the second supporting pin B38, the middle parts are hinged on the output ends of the giant magnetostrictive rods Ⅰ37 and Ⅱ39, and the upper ends are hinged on the first supporting pin C28 and the second supporting pin C43;

[0116] The giant magnetostrictive rods I37 and II39 change in length as the magnetic field changes, and the displacement is amplified by the displacement amplification mechanism, so that the driven rod I29 pushes the first brake shoe 31, and the driven rod II40 pushes the second brake shoe 35, so that the friction lining 32 is pressed against the brake drum 41, thereby completing the braking.

[0117] Reference Figure 3 As shown, the brake driver 36 includes: a driver housing 54, a driver bracket 53, giant magnetostrictive rods I 37, II 39, an excitation coil 52, a degaussing coil 48, a magnetic isolation pad 47, a fixing screw 51, a nut 49 and a fixing baffle 50;

[0118] The bottom end of the driver housing 54 is connected to the fixed baffle 50 through a fixing screw 51 and a nut 49, and the middle part is placed on the driver bracket 53;

[0119] The driver bracket 53 is fixed on the brake base plate 45;

[0120] The input ends of the giant magnetostrictive rods Ⅰ37 and Ⅱ39 are respectively fixed to the bottom end inside the driver housing 54, and the output ends are hinged to the middle of the driven rods Ⅰ29 and Ⅱ40;

[0121] The excitation coil 52 and the degaussing coil 48 are both wound around the giant magnetostrictive rods I37 and II39. The displacement of the giant magnetostrictive rods I37 and II39 is controlled by controlling the current in the excitation coil 52, and the hysteresis phenomenon is eliminated by controlling the current in the degaussing coil 48.

[0122] The magnetic isolation pad 47 is closely attached to the inner side of the driver housing 54 to isolate the influence of the magnetic field on the outside and the influence of the external magnetic field on the inside;

[0123] The fixed baffle 50 is fixed on the brake bottom plate 45;

[0124] The wheel module includes: a left front wheel 1, a left rear wheel 14, a right front wheel 27, and a right rear wheel 17;

[0125] The control module includes: an electronic control unit 10, a pedal displacement sensor 7, a vehicle speed sensor 15, a wheel speed sensor A3, a wheel speed sensor B12, a wheel speed sensor C18, a wheel speed sensor D25 and braking force sensors I57 and II58;

[0126] The pedal displacement sensor 7 is mounted on the push rod 6 and is electrically connected to the electronic control unit 10, so as to obtain the pedal displacement signal 69 and transmit the signal to the electronic control unit 10;

[0127] The vehicle speed sensor 15 is installed in the axle housing of the vehicle's drive axle or in the gearbox housing, and is used to obtain the vehicle speed signal 70 and transmit it to the electronic control unit 10;

[0128] The braking force sensors I57 and II58 are respectively mounted on the giant magnetostrictive rods I37 and II39 and are electrically connected to the electronic control unit;

[0129] The wheel speed sensors A3, B12, C18, and D25 are respectively mounted on the hubs of the left front wheel 1, the left rear wheel 14, the right rear wheel 17, and the right front wheel 27, and are used to obtain the vehicle speed signal 71 and transmit the signal to the electronic control unit 10;

[0130] The power module includes: a power supply (Power) 11 and a current regulation module (CRM) 19;

[0131] The power supply 11 is electrically connected to the current regulating module 19 and is used to supply power to the system;

[0132] The current regulating module 19 is used to receive the control current signal output by the electronic control unit 10, and input the current to the brake driver 36 after regulating the current, and feed back the current value in the excitation coil 52 to the electronic control unit 10;

[0133] Reference Figure 4 As shown, the parking brake module includes: a hand pull rod 24, a pull rod base 22, a parking brake cable 21, a hand pull rod return spring 23, a parking brake rod 59, a parking brake friction block 55, and a parking brake friction block return spring 56;

[0134] The input end of the parking brake cable 21 is connected to the hand lever 24, and the output end is connected to the parking brake lever 59;

[0135] The hand-pull rod return spring 23 is located at the connection between the hand-pull rod 24 and the pull rod base 22, and is used for returning the hand-pull rod;

[0136] The input end of the parking brake lever 59 is hinged to the output end of the parking brake cable 21, and the output end thereof is hinged to the parking brake friction block 55;

[0137] The parking brake friction block 55 is limited to be located between the first limiting pin D46 and the second limiting pin D44;

[0138] The lower end of the parking brake friction block return spring 56 is fixed to the driver bracket 53 , and the upper end is connected to the parking brake friction block 55 , and is used for returning the parking brake friction block.

[0139] The brake actuator 36 is installed one at the inner side of the first brake shoe 31 and the second brake shoe 35 respectively. The two brake actuators 36 are of equal length and are placed in parallel up and down and are powered by the power supply.

[0140] The two brake actuators 36 in each brake are completely identical.

[0141] Each wheel is equipped with a brake, and the left rear brake 13 and the right rear brake 16 are provided with a parking brake module.

[0142] The first support pin C28 and the second support pin C43 are provided with grooves for limiting the position of the brake shoe return spring 42 .

[0143] The brake bracket 53 is placed at the 1 / 2 position of the driver housing 54 .

[0144] When the adjustment gasket 62 is not added, the outer ring spring 60 is in a natural state.

[0145] Wherein, the giant magnetostrictive rods Ⅰ37 and Ⅱ39 have circular cross-sections, and their lengths should be greater than 8 cm and their diameters should be greater than 10 mm.

[0146] The material used for the giant magnetostrictive rods I37 and II39 should be a rare earth giant magnetostrictive material with a magnetostriction coefficient of not less than 2000 ppm.

[0147] Among them, the output ends of the giant magnetostrictive rods Ⅰ37, Ⅱ39 should be hinged at 1 / 2 to 1 / 3 of the lower ends of the driven rods Ⅰ29, Ⅱ40.

[0148] Wherein, the two displacement amplification mechanisms have equal amplification ratios.

[0149] The cross section of the driver housing 54 should be square or circular.

[0150] The excitation coils 52 in the two brake drivers 36 in the brake are wound by the same wire, and the demagnetization coils 48 are also wound by the same wire.

[0151] Reference Figure 6 As shown, this embodiment also provides a control method for a drum-type brake-by-wire system based on magnetostrictive material, comprising the following steps:

[0152] (1) During normal braking, the brake pedal 20 is depressed, and the pedal displacement sensor 7, the vehicle speed sensor 15, the wheel speed sensors A3, B12, C18, D25 and the braking force sensors I57 and II58 respectively collect the pedal displacement signal 69, the vehicle speed signal 70, the wheel speed signal 71 of each wheel and the braking force signal 68 and transmit the signals to the electronic control unit 10;

[0153] (2) The pedal feel simulator 8 generates a feedback force through the deformation of the outer ring spring 60 and the inner ring spring 61, and feeds back the simulated pedal force to the driver through the push rod 6, the connecting rod 5 and the brake pedal 20;

[0154] (3) The electronic control unit 10 receives the pedal displacement signal 69, the vehicle speed signal 70, the wheel speed signal 71 and the braking force signal 68 collected in the above step (1), calculates the currently required target braking force according to the signals, and then distributes the braking force of each wheel according to the currently required braking force, calculates the required displacement of the super magnetostrictive rods I 37 and II 39 in the brake driver 36 of each wheel, and then calculates the required target current signal, and transmits the signal to the current regulation module 19;

[0155] (4) After receiving the current control signal obtained in step (3), the current regulating module 19 regulates the current and inputs it into the brake driver 36 of each brake to control the magnetic field strength attached to the giant magnetostrictive rods I 37 and II 39, and feeds back the current value in each excitation coil 52 to the electronic control unit 10;

[0156] (5) Current is input to the brake driver 36, the magnetic field strength in the excitation coil 52 changes, the giant magnetostrictive rods I37 and II39 are deformed, and the first brake shoe 31 and the second brake shoe 35 are respectively rotated around the first support pin A33 and the second support pin A34 through the driven rods I29 and II40. The upper ends of the two brake shoes are separated to both sides so that the friction lining 32 is pressed against the inner circumferential surface of the brake drum 39, and the braking is completed;

[0157] (6) When the brake pedal 20 is released, the electronic control unit 10 adjusts the current in the excitation coil 52 according to the real-time pedal displacement, and controls the current regulation module 19 to pass a current in the opposite direction to that in the excitation coil 52 into the demagnetization coil 48 to eliminate the hysteresis phenomenon and improve the system response until the brake pedal 20 is completely released and the brake is released;

[0158] (7) After the vehicle stops, the hand lever 24 is pulled, and the parking brake friction block 55 is pulled toward the brake drum 41 through the parking brake cable 21 and the parking brake lever 59, so that the parking brake friction block 55 is pressed against the inner circumferential surface of the brake drum 41, thereby completing the parking brake;

[0159] (8) When the hand lever 24 returns to its original position, the parking brake friction block return spring 42 pulls the parking brake friction block 55 back to its original position, and the hand lever return spring 23 pulls the hand lever 24 back to its original position.

[0160] The formula for calculating the output braking force required by each brake driver in the brake in step (3) is:

[0161]

[0162] The formula for calculating the displacement of each giant magnetostrictive rod in the brake is:

[0163]

[0164] The formula for calculating the excitation coil current in the brake is:

[0165]

[0166] In the formula, F ci is the required output braking force of each brake actuator in the brake, where i=1, 2, 3, 4 represent the left front, right front, left rear, and right rear brakes respectively; F zi is the braking force required by the wheel, where i=1,2,3,4 represent the left front, right front, left rear, and right rear wheels respectively; ε i is the deformation of each giant magnetostrictive rod in the required brake, where i = 1, 2, 3, 4 represent the left front, right front, left rear, and right rear brakes respectively; E is the elastic modulus of the giant magnetostrictive rod; r is the radius of the giant magnetostrictive rod; π is the pi constant; I i is the current in the excitation coil of the required brake, where i=1, 2, 3, 4 represent the left front, right front, left rear, and right rear brakes respectively; L is the length of the part of the giant magnetostrictive rod wound with the coil; a is the characteristic constant (depending on the material properties); μ0 is the vacuum permeability; N is the number of coil turns.

[0167] The step (5) specifically includes: the braking force F output by the brake driver ci The control adopts the PID closed-loop current control method. The specific steps are as follows:

[0168] (51) The electronic control unit calculates the target braking force F of the current brake actuator according to formula (1): ci_need ;

[0169] (52) The electronic control unit receives the actual braking force signal sent by the braking force sensor and converts the actual braking force F ci_real and target braking force F ci_need Compare and then calculate the actual braking force F according to formula (4) ci_real and target braking force F ci_need The difference

[0170]

[0171] (53) The error value obtained by formula (4) is used as the input of the current closed-loop control to the controller, and the output model of the controller is:

[0172]

[0173] In the formula, u i (t) is the control quantity output by the electronic control unit; K pi is the proportionality coefficient, T i is the integration constant, T di is the differential constant, u0 is the control constant I i , which can be calculated using formula (2-3).

[0174] The present invention has many specific application paths. The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements can be made without departing from the principle of the present invention. These improvements should also be regarded as the protection scope of the present invention.

Claims

1. A drum-type brake-by-wire system based on magnetostrictive material, characterized in that: include: brake pedal modules, brakes, wheel modules, power modules, parking brake modules and control modules; The brake pedal module comprises: a brake pedal, a pedal bracket, a pedal shaft, a connecting rod and a pedal feeling simulator; The input end of the pedal shaft is fixedly connected to the output end of the brake pedal, and the output end is fixedly connected to the input end of the connecting rod; The lower end of the pedal feel simulator is fixed to the pedal bracket; The pedal feeling simulator comprises: a push rod, a simulator housing, an outer ring spring, an inner ring spring, an upper end cover, a lower end cover, an adjustment gasket and a base; The upper and lower end covers are screwed onto the upper and lower ends of the pedal feeling simulator respectively; The input end of the push rod is hinged to the output end of the connecting rod; The outer coil spring and the inner coil spring are located inside the simulator housing and are respectively mounted on the base to generate simulated pedal force; The adjustment gasket is located between the pedal feel simulator and the pedal bracket and is used to adjust the preload force of the pedal feel simulator; The brake comprises: a first brake shoe, a second brake shoe, a brake drum, a brake base plate, a brake shoe return spring, a friction lining, a brake driver, a displacement amplification mechanism, a first support pin A and a second support pin A, a first support pin B and a second support pin B, a first support pin C and a second support pin C, a first limit pin D, and a second limit pin D; The first support pin A and the second support pin A, the first support pin B and the second support pin B and the first limit pin D and the second limit pin D are fixed on the brake bottom plate; A first support pin C and a second support pin C are fixed to the first brake shoe and the second brake shoe respectively; When the first brake shoe and the second brake shoe are not braking, their upper ends are pulled against the first limit pin D and the second limit pin D by the brake shoe return spring, and their lower ends are hinged on the first support pin A and the second support pin A; The brake drum is fixed to the wheel hub of each wheel of the vehicle and rotates with the wheel; The front and rear ends of the brake shoe return spring are respectively hooked on the first supporting pin C and the second supporting pin C; The friction linings are respectively mounted on the curved surfaces of the first brake shoe and the second brake shoe facing the inner side of the brake drum; The displacement amplification mechanism includes: giant magnetostrictive rods Ⅰ, Ⅱ and driven rods Ⅰ, Ⅱ; The lower ends of the driven rods I and II are hinged on the first supporting pin B and the second supporting pin B, the middle parts are hinged on the output ends of the giant magnetostrictive rods I and II, and the upper ends are hinged on the first supporting pin C and the second supporting pin C; The brake driver comprises: a driver housing, a driver bracket, giant magnetostrictive rods I and II, an excitation coil, a degaussing coil, a magnetic isolation pad and a fixed baffle; The bottom end of the driver housing is connected to the fixed baffle, and the middle part is placed on the driver bracket; The drive bracket is fixed to the brake base plate; The input ends of the giant magnetostrictive rods I and II are respectively fixed at the bottom ends inside the driver housing, and the output ends are hinged to the middle parts of the driven rods I and II; The excitation coil and the degaussing coil are both wound around the giant magnetostrictive rods I and II, and the displacement of the giant magnetostrictive rods I and II is controlled by controlling the current in the excitation coil, and the hysteresis phenomenon is eliminated by controlling the current in the degaussing coil; The magnetic isolation pad is closely attached to the inner side of the driver housing to isolate the influence of the magnetic field on the outside and the influence of the external magnetic field on the inside; The fixed baffle is fixed on the brake bottom plate; The wheel module includes: a left front wheel, a left rear wheel, a right front wheel, and a right rear wheel; The control module includes: an electronic control unit, a pedal displacement sensor, a vehicle speed sensor, a wheel speed sensor and braking force sensors I and II; A pedal displacement sensor is mounted on the push rod and is electrically connected to the electronic control unit to obtain the pedal displacement signal and transmit the signal to the electronic control unit; The vehicle speed sensor is installed in the axle housing of the vehicle's drive axle or in the gearbox housing, and is used to obtain a vehicle speed signal and transmit it to the electronic control unit; Braking force sensors I and II are respectively mounted on the giant magnetostrictive rods I and II and are electrically connected to the electronic control unit; The wheel speed sensor is installed on the wheel hub of each wheel, and is used to obtain the wheel speed signal and transmit the signal to the electronic control unit; The power supply module includes: a power supply and a current regulating module; The power supply is electrically connected to the current regulation module and is used to supply power to the system; The current regulating module is used to receive the control current signal output by the electronic control unit, and input the current into the brake driver after regulating the current, and feed back the current value in the excitation coil to the electronic control unit; The parking brake module comprises: a hand pull rod, a pull rod base, a parking brake cable, a hand pull rod return spring, a parking brake rod, a parking brake friction block, and a parking brake friction block return spring; The input end of the parking brake cable is connected to the hand lever, and the output end is connected to the parking brake lever; The tie rod base is fixed to the vehicle body behind the shift lever; The hand pull rod return spring is located at the connection between the hand pull rod and the pull rod base, and is used for returning the hand pull rod; The input end of the parking brake lever is hinged to the output end of the parking brake cable, and the output end thereof is hinged to the parking brake friction block; The parking brake friction block is limited to the middle of the first supporting pin D and the second supporting pin D; The lower end of the parking brake friction block return spring is fixed to the driver bracket, and the upper end is connected to the parking brake friction block, and is used for returning the parking brake friction block; The brake actuator is installed one at the inner side of the first brake shoe and the second brake shoe respectively, and the two brake actuators are of equal length and placed in parallel up and down and are powered by the power supply; The number of the brakes is four, namely a left front brake, a right front brake, a left rear brake, and a right rear brake.

2. The drum-type brake-by-wire system based on magnetostrictive material according to claim 1, characterized in that: The two brake actuators in the brake are identical.

3. The drum-type brake-by-wire system based on magnetostrictive material according to claim 2, characterized in that: Each wheel is equipped with a brake, and the left rear brake and the right rear brake are provided with a parking brake module.

4. The drum-type brake-by-wire system based on magnetostrictive material according to claim 1, characterized in that: The brake bracket is placed at the 1 / 2 position of the driver housing.

5. The drum-type brake-by-wire system based on magnetostrictive material according to claim 1, characterized in that: The excitation coils in the two brake drivers in the brake are wound by the same wire, and the demagnetization coils are also wound by the same wire.

6. A control method for a drum-type brake-by-wire system based on magnetostrictive material, based on the system of claim 1, characterized in that: The method comprises the following steps: (1) During normal braking, the brake pedal is depressed, and the pedal displacement sensor, vehicle speed sensor, wheel speed sensor and braking force sensor respectively collect pedal displacement signals, vehicle speed signals, wheel speed signals of each wheel and braking force signals and transmit the signals to the electronic control unit; (2) The pedal feel simulator generates feedback force through the deformation of the outer spring and the inner spring, and feeds back the simulated pedal force to the driver through the push rod, the connecting rod and the brake pedal; (3) The electronic control unit receives the pedal displacement signal, vehicle speed signal, wheel speed signal and braking force signal collected in the above step (1), calculates the currently required target braking force according to the signals, distributes the braking force to each wheel according to the currently required braking force, calculates the required displacement of the giant magnetostrictive rod in the brake driver of each wheel, and then calculates the required target current signal, and transmits the signal to the current regulation module; (4) After receiving the current control signal obtained in the above step (3), the current regulating module regulates the current and inputs it into the brake driver of each brake to control the magnetic field strength attached to the giant magnetostrictive rod, and feeds back the current value in each excitation coil to the electronic control unit; (5) Current is input to the brake driver, the magnetic field strength in the excitation coil changes, the giant magnetostrictive rod deforms, and the first brake shoe and the second brake shoe rotate around the first support pin A and the second support pin A respectively through the driven rod. The upper ends of the two brake shoes are separated to both sides so that the friction lining is pressed against the inner surface of the brake drum, completing the braking. (6) Release the brake pedal. The electronic control unit adjusts the current in the excitation coil according to the real-time pedal displacement, and controls the current regulation module to pass a current in the opposite direction to the excitation coil into the demagnetization coil to eliminate hysteresis and improve system response until the brake pedal is completely released and the brake is released; (7) After the vehicle stops, pull the hand lever to pull the parking brake friction block toward the brake drum through the parking brake cable and the parking brake lever, so that the parking brake friction block is pressed against the inner surface of the brake drum to complete the parking brake; (8) When the hand lever returns to its original position, the parking brake friction pad return spring pulls the parking brake friction pad back to its original position, and the hand lever return spring pulls the hand lever back to its original position.

7. The control method of the drum-type brake-by-wire system based on magnetostrictive material according to claim 6, characterized in that: The formula for calculating the output braking force required by each brake driver in the brake in step (3) is: The formula for calculating the displacement of each giant magnetostrictive rod in the brake is: The formula for calculating the excitation coil current in the brake is: In the formula, F ci is the required output braking force of each brake actuator in the brake, where i=1, 2, 3, 4 represent the left front, right front, left rear, and right rear brakes respectively; F zi is the braking force required by the wheel, where i=1,2,3,4 represent the left front, right front, left rear, and right rear wheels respectively; ε i is the deformation of each giant magnetostrictive rod in the required brake, where i=1, 2, 3, 4 represent the left front, right front, left rear, and right rear brakes respectively; E is the elastic modulus of the giant magnetostrictive rod; r is the radius of the giant magnetostrictive rod; π is the pi constant; I i is the current in the excitation coil of the required brake, where i=1, 2, 3, 4 represent the left front, right front, left rear, and right rear brakes respectively; L is the length of the part of the giant magnetostrictive rod wound with the coil; a is the characteristic constant; μ0 is the vacuum permeability; N is the number of coil turns.

8. The control method of the drum-type brake-by-wire system based on magnetostrictive material according to claim 7, characterized in that: The step (5) specifically includes: the braking force F output by the brake driver ci The control adopts the PID closed-loop current control method. The specific steps are as follows: (51) The electronic control unit calculates the target braking force F of the current brake actuator according to formula (1): ci_need ; (52) The electronic control unit receives the actual braking force signal from the braking force sensor and converts the actual braking force F ci_real and target braking force F ci_need Compare and then calculate the actual braking force F according to formula (4) ci_real and target braking force F ci_need The difference (53) The error value obtained by formula (4) is used as the input of the current closed-loop control to the controller, and the output model of the controller is: In the formula, u i (t) is the control quantity output by the electronic control unit; K pi is the proportionality coefficient, T i is the integration constant, T di is the differential constant, u0 is the control constant I i , which can be calculated using formula (2-3).

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