A braking device based on magnetostrictive material and a control method thereof

Abstract

The present invention discloses a brake device based on magnetostrictive material and a control method thereof. A new type of magnetostrictive intelligent material is used in the device. The size of the magnetic field is controlled by changing the size of the current in the coil, and the expansion and contraction amount of the magnetostrictive material is further controlled. The force generated by the expansion and contraction process of the magnetostrictive material is used to replace the air pressure or the hydraulic pressure as the braking driving force. In addition, the device replaces the original oil circuit and the air circuit with the circuit during the working process, which simplifies the structure of the brake system and improves the response speed of the brake system.

Description

Technical Field

[0001] The invention belongs to the technical field of automobile mechanical brakes, and specifically refers to a brake device based on magnetostrictive materials and a control method thereof. Background Art

[0002] Magnetostrictive materials are a type of material that can convert electromagnetic energy into mechanical energy. When the material is magnetized in a magnetic field, it can expand and contract along the direction of magnetization. If a powered coil is used as a 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. Among them, magnetostrictive materials whose size change is much larger than that of magnetostrictive materials such as ferrites and whose energy generated is also large are called giant magnetostrictive materials. The rare earth-iron alloy (RFe2) materials with giant magnetostrictive properties at room temperature that appeared in the 1970s have a larger expansion and contraction capacity and are called rare earth giant magnetostrictive materials. Because they are controlled by magnetic fields with fast response time, good frequency characteristics, high energy density, large coupling coefficient, and have sensing and driving functions, they have been increasingly widely used and developed in the field of smart materials as smart materials or corresponding devices.

[0003] Since magnetostrictive materials are controlled by magnetic fields, have fast response time, good frequency characteristics, high energy density, large coupling coefficient, controllable energy consumption, and have sensing and driving functions, they are used in many aspects; for example, the Chinese invention patent application number is 201410785712.9, and the patent name is "A disc brake with giant magnetostrictive boosting function and its method", which uses the magnetostrictive phenomenon of magnetostrictive materials to propose a disc brake with magnetostrictive boosting function. It has the characteristics of simple and reliable structure, good compatibility with existing brake systems, and does not affect the normal operation of ABS. It can improve driving safety while reducing the braking distance during emergency braking; the Chinese invention patent application number is 201811204066.7, and the patent name is "Self-sensing driver based on magnetostrictive material". A driver based on magnetostrictive material is proposed, which can simultaneously realize the functions of driver and sensor, improve structural compactness, driving accuracy and sensing efficiency; the Chinese invention patent application number is 201410346464.8, and the patent name is "Magnetostrictive-electromagnetic composite vibration energy harvester and method thereof". A new type of vibration energy harvester is proposed. The device has a compact structure, is easy to miniaturize, has the characteristics of piezomagnetic-electromagnetic composite power generation, and can be used for vibration energy harvesting in high-load vibration environments.

[0004] Drum brakes are the earliest type of brakes. Compared with disc brakes, they have low manufacturing costs and high braking efficiency, and are used on various types of vehicles. However, since drum brakes are mostly driven by hydraulic or pneumatic pressure, the braking response has a certain lag during braking, so the brake drive device has to be in a servo state at all times, resulting in excessive energy consumption of the braking system and difficulty in ensuring the maximum braking force. In addition, the layout of the oil and air circuits also increases the complexity of the brake. Summary of the invention

[0005] In view of the above-mentioned deficiencies of the prior art, the purpose of the present invention is to provide a brake device based on magnetostrictive materials and a control method thereof, so as to solve the technical problems of the prior art such as the delayed braking response of drum brakes, excessive energy consumption of the braking system, insufficient maximum braking force and complex layout of the braking system; the present invention controls the size of the magnetic field by changing the size of the current in the coil, further controls the expansion and contraction amount of the magnetostrictive material, and uses the force generated by the expansion and contraction process of the magnetostrictive material to replace the air pressure or hydraulic pressure as the braking driving force. The present invention uses a magnetostrictive device to replace the hydraulic and air pressure devices, so that the air circuit and the oil circuit are replaced by the circuit, which greatly simplifies the structure of the braking system. Moreover, since the magnetostrictive material responds very quickly (only one millionth of a second, faster than human thinking) when controlled by the magnetic field and has good frequency characteristics, the disadvantage of the delayed brake response is eliminated while reducing the energy consumption of the braking system. At the same time, since the braking force of the brake device can be adjusted according to the current size, the maximum braking force can be guaranteed.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A brake device based on magnetostrictive material of the present invention comprises: a brake base plate, a support pin A, a support pin B, a support pin C, a fixed baffle, a driver bracket, a brake execution unit, a displacement amplification mechanism and a driver;

[0008] The brake bottom plate is fixedly mounted with a support pin A, a support pin B, a fixed baffle and a driver bracket;

[0009] The brake actuating unit comprises a first brake shoe, a first friction lining, a second friction lining, a second brake shoe, a first brake shoe return spring, a second brake shoe return spring, a tension spring, a brake drum, an adjustment screw, and a floating push rod;

[0010] The first friction lining and the second friction lining are respectively mounted on the outer cylindrical surfaces of the first brake shoe and the second brake shoe; during braking, the first and second friction linings rub against the inner cylindrical surface of the brake drum to brake;

[0011] When the upper ends of the first brake shoe and the second brake shoe are not braking, the upper ends are pulled against the support pin A by means of the first brake shoe return spring and the second brake shoe return spring, and the lower ends are suspended and supported on both sides of the floating push rod by means of the tension spring; the first brake shoe and the second brake shoe are respectively provided with a return spring mounting hole and a tension spring mounting hole, and the mounting holes are respectively used to install the first brake shoe return spring, the second brake shoe return spring and the tension spring; a support pin C is fixed on one of the brake shoes;

[0012] The upper ends of the first brake shoe return spring and the second brake shoe return spring are respectively hooked on the support pin A, and the lower ends are respectively hooked on the return spring mounting holes;

[0013] The two ends of the tension spring are respectively hooked to the tension spring installation holes opened at the first and second brake shoe ends;

[0014] The floating push rod comprises an adjustable push rod body and a push rod sleeve, wherein the push rod sleeve is the support point of the lower end of the first brake shoe; the adjustable push rod body is the support point of the lower end of the second brake shoe;

[0015] The adjusting screw is mounted on the floating ejector rod and is used to adjust the braking clearance;

[0016] The displacement amplification mechanism includes an active rod and a driven rod; the output end of the active rod is hinged on the driven rod, and the input end is fixed to the bottom end inside the driver housing; the lower end of the driven rod is hinged on the support pin B, and the upper end is hinged on the support pin C;

[0017] The bottom end of the driver is fixedly connected to the fixed baffle on the brake bottom plate by fixing screws, and the driver comprises a driver housing, an active rod, an excitation coil, a demagnetization coil, a magnetic isolation pad and a magnetic isolation top cover;

[0018] The excitation coil and the degaussing coil are both wound on the giant magnetostrictive rod;

[0019] The magnetic isolation pad is closely attached to the inner side of the driver housing; the magnetic isolation top cover is located at the top of the driver and, together with the magnetic isolation pad, isolates the influence of the magnetic field on the outside.

[0020] Preferably, the support pin C is fixedly connected to the upper end of the first brake shoe.

[0021] Preferably, the cross section of the active rod is circular, and the length should be greater than 5 cm and the diameter should be greater than 10 mm.

[0022] Preferably, the material used for the active rod should be a rare earth giant magnetostrictive material with a magnetostriction coefficient of not less than 2000 ppm.

[0023] Preferably, the output end of the active rod is hinged at 1 / 3 to 1 / 4 of the lower end of the driven rod.

[0024] Preferably, the cross section of the driver housing is square or circular.

[0025] The present invention also provides a control method for a brake device based on a magnetostrictive material, comprising the following steps:

[0026] (1) When the driver presses the brake pedal to brake, the sensor collects relevant pedal information and transmits the information to the ECU;

[0027] (2) The ECU (electronic control unit) receives the pedal information, processes it to obtain the required target braking force, and then calculates the required current in the excitation coil based on the required target braking force;

[0028] (3) The ECU adjusts the current in the excitation coil according to the driver's operation of the brake pedal, changing the magnetic field strength in the excitation coil, causing the giant magnetostrictive rod to deform and output the required braking force;

[0029] (4) When braking is completed, the ECU controls the excitation coil to be powered off, and the demagnetization coil is fed with a current in the opposite direction to the current previously fed into the excitation coil, thereby eliminating the magnetic field, causing the giant magnetostrictive rod to return to its original length, and braking is completed.

[0030] Preferably, the pedal information includes a pedal displacement signal, a pedal speed signal, a vehicle speed signal and a wheel speed signal.

[0031] Preferably, the formula used in step (2) is:

[0032] F c =κF z (1)

[0033]

[0034]

[0035] In the formula, F c is the required output force of the giant magnetostrictive rod; κ is the displacement amplification factor of the displacement amplification mechanism; F z is the required braking force; ε is the required deformation of the giant magnetostrictive rod; 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 is the current in the required coil; 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 magnetic permeability; N is the number of coil turns.

[0036] Preferably, the step (3) further comprises: during the braking force adjustment process, if the braking force needs to be reduced, passing a current opposite to that of the excitation coil through the demagnetization coil to eliminate the influence of hysteresis on the braking force.

[0037] Beneficial effects of the present invention:

[0038] Compared with the existing brake device, the present invention adopts magnetostrictive material, utilizes the force generated by the deformation to replace the hydraulic pressure or gas pressure, and uses the circuit to replace the liquid circuit or gas circuit, which greatly simplifies the system structure and saves the manufacturing cost.

[0039] The present invention controls the deformation of the giant magnetostrictive rod by controlling the current in the energized coil to control the magnetic field strength, thereby improving the response speed of the system while ensuring the maximum braking force and eliminating the drawbacks of hysteresis in the original braking device.

[0040] The ultra-fast response speed of the driver in the present invention means that the driver does not need to be in a servo state all the time, and only needs to work when braking is required, which greatly reduces the energy consumption of the braking system and improves the economy of the braking system. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a schematic diagram of the braking device based on magnetostrictive material of the present invention;

[0042] Figure 2 AA is a cross-sectional schematic diagram of the driver of the present invention;

[0043] Figure 3 It is a cross-sectional schematic diagram of the driver BB of the present invention;

[0044] Figure 4 This is a flow chart of the braking device control method of the present invention;

[0045] In the figure, 1-brake base plate, 2-support pin C, 3-brake drum, 4-driven rod, 5-first brake shoe return spring 27-second brake shoe return spring, 6, 26-return spring mounting holes, 7-first friction lining, 28-second friction lining, 8-active rod, 9-magnetic isolation top cover, 10-support pin B, 11-first brake shoe, 12-tensioning spring, 13-thrust rod sleeve, 14-adjusting screw, 15-adjustable push rod body, 16-tensioning spring mounting hole, 17-second brake shoe, 18-magnetic isolation pad, 19-demagnetization coil, 20-excitation coil, 21 fixed baffle, 22-fixing screw 23-driver housing, 24-driver bracket, 25-driver, 29-support pin A. DETAILED DESCRIPTION

[0046] 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.

[0047] Reference Figures 1 to 3 As shown, a brake device based on magnetostrictive material of the present invention comprises: a brake base plate 1, a support pin A29, a support pin B10, a support pin C2, a fixed baffle 21, a driver bracket 24, a brake actuator unit, a displacement amplification mechanism and a driver 25;

[0048] The brake base plate 1 is fixedly mounted with a support pin A29, a support pin B10, a fixed baffle 21 and a driver bracket 24;

[0049] The brake actuating unit comprises a first brake shoe 11, a first friction lining 7, a second friction lining 28, a second brake shoe 17, a first brake shoe return spring 5, a second brake shoe return spring 27, a tension spring 12, a brake drum 3, an adjustment screw 14 and a floating push rod;

[0050] The first friction lining 7 and the second friction lining 28 are respectively mounted on the outer cylindrical surfaces of the first brake shoe 11 and the second brake shoe 17; during braking, the first friction lining 7 and the second friction lining 28 rub against the inner cylindrical surface of the brake drum 3 to perform braking;

[0051] When the upper ends of the first brake shoe 11 and the second brake shoe 17 are not braking, the upper ends are pulled against the support pin A29 by means of the first brake shoe return spring 5 and the second brake shoe return spring 27 respectively; the lower ends are suspended and supported on both sides of the floating push rod by means of the tension spring 12; the first brake shoe 11 and the second brake shoe 16 are respectively provided with return spring mounting holes 6, 26 and tension spring mounting holes 16, and the mounting holes 6, 26 and 16 are respectively used to mount the first brake shoe return spring 5, the second brake shoe return spring 27 and the tension spring 12; wherein a support pin C2 is fixed on the first brake shoe 11;

[0052] The upper ends of the first brake shoe return spring 5 and the second brake shoe return spring are respectively hooked on the support pin A29, and the lower ends are respectively hooked on the return spring mounting holes 6 and 26;

[0053] The two ends of the tension spring 12 are respectively hooked at the tension spring mounting holes 16 opened at the lower ends of the first and second brake shoes 11 and 17;

[0054] The floating push rod comprises an adjustable push rod body 15 and a push rod sleeve 13, wherein the push rod sleeve 13 is the support point of the lower end of the first brake shoe 11; the adjustable push rod body 15 is the support point of the lower end of the second brake shoe 17;

[0055] The adjusting screw 14 is mounted on the floating push rod and is used to adjust the braking clearance;

[0056] The displacement amplification mechanism includes an active rod 8 and a driven rod 4; the output end of the active rod 8 is hinged on the driven rod 4, and the input end is fixed to the bottom end inside the driver housing 23; the lower end of the driven rod is hinged on the support pin B10, and the upper end is hinged on the support pin C2;

[0057] The bottom end of the driver 25 is fixedly connected to the fixed baffle 21 on the brake base plate 1 by the fixing screws 22, and includes a driver housing 23, an active rod 8, an excitation coil 20, a demagnetization coil 19, a magnetic isolation pad 18 and a magnetic isolation top cover 9;

[0058] The excitation coil 19 and the demagnetization coil 18 are both wound on the active rod 8;

[0059] The magnetic isolation pad 17 is closely attached to the inner side of the driver housing 23 ; the magnetic isolation top cover 9 is located at the top of the driver, and together with the magnetic isolation pad 17 , isolates the influence of the magnetic field on the outside.

[0060] The support pin C2 is fixedly connected to the upper end of the first brake shoe 11 .

[0061] The cross section of the active rod 8 is circular, and the length should be greater than 5 cm and the diameter should be greater than 10 mm.

[0062] The material used for the active rod 8 should be a rare earth giant magnetostrictive material with a magnetostrictive coefficient of not less than 2000 ppm.

[0063] The output end of the active rod 8 should be hinged at 1 / 3 to 1 / 4 of the lower end of the driven rod.

[0064] The cross section of the driver housing 23 should be square or circular.

[0065] Reference Figure 4 This embodiment also provides a control method for the above-mentioned braking device, comprising the following steps:

[0066] (1) When the driver steps on the brake pedal to perform a braking operation, the sensor collects a pedal displacement signal 29, a pedal speed signal 30, a vehicle speed signal 31, a wheel speed signal 32 and a braking force signal 28, and transmits the collected information to the ECU 33;

[0067] (2) The pedal displacement signal 29, the pedal speed signal 30, the vehicle speed signal 31, and the wheel speed signal 32 received by the ECU 33 are processed to obtain the required target braking force, and then the required current in the excitation coil is calculated based on the required target braking force;

[0068] (3) The ECU controls the current regulating module 35 to regulate the current in the excitation coil according to the received pedal displacement signal 29, pedal speed signal 30, vehicle speed signal 31, wheel speed signal 32 and braking force signal 28, thereby changing the magnetic field strength in the excitation coil in real time, adjusting the deformation of the giant magnetostrictive rod, and amplifying the displacement of the giant magnetostrictive rod through the displacement amplification mechanism, driving the brake shoe to contact the brake drum for braking, so that the brake driver can provide sufficient braking displacement to eliminate the braking gap and ensure the maximum braking force;

[0069] (4) During the braking process, if the required braking force change rate is less than or equal to 0, the ECU 33 controls the current regulation module 35 to pass a current opposite to that in the excitation coil into the degaussing coil, so as to provide braking force while eliminating the influence of hysteresis on the brake driver, thereby ensuring that the brake driver works stably and reliably; if the required braking force change rate is greater than 0, the degaussing coil is not powered;

[0070] (5) When braking is completed, ECU33 controls the excitation coil to be powered off, and the demagnetization coil is fed with a current in the opposite direction to the current previously fed into the excitation coil to eliminate the magnetic field. The giant magnetostrictive rod returns to its original length, and the brake shoe return spring and tension spring pull the brake shoe back to its original position, thus ending braking.

[0071] Wherein, the formula used in step (2) is:

[0072] F c =κF z (1)

[0073]

[0074]

[0075] In the formula, F c is the required output force of the giant magnetostrictive rod; κ is the displacement amplification factor of the displacement amplification mechanism; F z is the required braking force; ε is the required deformation of the giant magnetostrictive rod; 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 is the current in the required coil; 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 magnetic permeability; N is the number of coil turns.

[0076] 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 braking device based on magnetostrictive material, characterized in that: include: Braking base plate, supporting pin A, supporting pin B, supporting pin C, fixed baffle, driver bracket, brake actuator unit, displacement amplification mechanism and driver; The brake bottom plate is fixedly mounted with a support pin A, a support pin B, a fixed baffle and a driver bracket; The brake actuating unit comprises a first brake shoe, a first friction lining, a second friction lining, a second brake shoe, a first brake shoe return spring, a second brake shoe return spring, a tension spring, a brake drum, an adjustment screw, and a floating push rod; The first friction lining and the second friction lining are respectively mounted on the outer cylindrical surfaces of the first brake shoe and the second brake shoe; during braking, the first friction lining and the second friction lining rub against the inner cylindrical surface of the brake drum to perform braking; When the upper ends of the first brake shoe and the second brake shoe are not braking, the upper ends are pulled against the support pin A by means of the first brake shoe return spring and the second brake shoe return spring, and the lower ends are suspended and supported on both sides of the floating push rod by means of the tension spring; the first brake shoe and the second brake shoe are respectively provided with a return spring mounting hole and a tension spring mounting hole, and the return spring mounting hole and the tension spring mounting hole are respectively used to install the first brake shoe return spring, the second brake shoe return spring and the tension spring; a support pin C is fixed on one of the brake shoes; The upper ends of the first brake shoe return spring and the second brake shoe return spring are respectively hooked on the support pin A, and the lower ends are respectively hooked on the return spring mounting holes; The two ends of the tension spring are respectively hooked to the tension spring installation holes opened at the ends of the first brake shoe and the second brake shoe; The floating push rod comprises an adjustable push rod body and a push rod sleeve, wherein the push rod sleeve is the support point of the lower end of the first brake shoe; the adjustable push rod body is the support point of the lower end of the second brake shoe; The adjusting screw is mounted on the floating ejector rod and is used to adjust the braking clearance; The displacement amplification mechanism includes an active rod and a driven rod; the output end of the active rod is hinged on the driven rod, and the input end is fixed to the bottom end inside the driver housing; the lower end of the driven rod is hinged on the support pin B, and the upper end is hinged on the support pin C; The bottom end of the driver is fixedly connected to the fixed baffle on the brake bottom plate by fixing screws, and the driver comprises a driver housing, an active rod, an excitation coil, a demagnetization coil, a magnetic isolation pad and a magnetic isolation top cover; The excitation coil and the degaussing coil are both wound on the giant magnetostrictive rod; The magnetic isolation pad is closely attached to the inner side of the driver housing; the magnetic isolation top cover is located at the top of the driver, and together with the magnetic isolation pad, isolates the influence of the magnetic field on the outside; The support pin C is fixedly connected to the upper end of the first brake shoe; The cross section of the active rod is circular, and the length should be greater than 5 cm and the diameter should be greater than 10 mm.

2. The brake device based on magnetostrictive material according to claim 1, characterized in that: The output end of the active rod is hinged at 1 / 3 to 1 / 4 of the lower end of the driven rod.

3. The brake device based on magnetostrictive material according to claim 1, characterized in that: The cross section of the driver housing is square or circular.

4. A control method for a brake device based on magnetostrictive material, based on the device according to claim 1, characterized in that: The method comprises the following steps: (1) When the driver presses the brake pedal to brake, the sensor collects relevant pedal information and transmits the information to the ECU; (2) The ECU receives the pedal information, processes it to obtain the required target braking force, and then calculates the required current in the excitation coil based on the required target braking force; (3) The ECU adjusts the current in the excitation coil according to the driver's operation of the brake pedal, changing the magnetic field strength in the excitation coil, causing the giant magnetostrictive rod to deform and output the required braking force; (4) When braking is completed, the ECU controls the excitation coil to be powered off, and the demagnetization coil is fed with a current in the opposite direction to the current previously fed into the excitation coil, thereby eliminating the magnetic field, causing the giant magnetostrictive rod to return to its original length, and braking is completed.

5. The control method of the brake device based on magnetostrictive material according to claim 4, characterized in that: The pedal information includes a pedal displacement signal, a pedal speed signal, a vehicle speed signal and a wheel speed signal.

6. The control method of the brake device based on magnetostrictive material according to claim 4, characterized in that: The formula used in step (2) is: Fc=κFz (1) In the formula, F c is the required output force of the giant magnetostrictive rod; κ is the displacement amplification coefficient of the displacement amplification mechanism; F z is the required braking force; ε is the required deformation of the giant magnetostrictive rod; 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 is the current in the required coil; L is the length of the part of the giant magnetostrictive rod wound with the coil; a is the characteristic constant; μ0 is the magnetic permeability of vacuum; N is the number of turns of the coil.

7. The control method of a brake device based on a magnetostrictive material according to claim 4, characterized in that: The step (3) also includes: during the braking force adjustment process, if the braking force needs to be reduced, a current opposite to that of the excitation coil is passed through the demagnetization coil to eliminate the influence of hysteresis on the braking force.

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