A piezoelectric brake hydraulic regulator and its hydraulic brake system and control method

Abstract

The present invention discloses a piezoelectric brake hydraulic regulator and its hydraulic brake system and control method, wherein the piezoelectric brake hydraulic regulator comprises a cylindrical shell filled with brake fluid and a plurality of piezoelectric ceramic sheets axially spaced in the shell, the inner wall of the shell is provided with a plurality of rubber mounting rings axially spaced, each piezoelectric ceramic sheet is correspondingly mounted on each rubber mounting ring, the rubber mounting ring is provided with a flow hole for the brake fluid to flow when the volume of the piezoelectric ceramic sheet changes, the shell is provided with a plurality of wire interfaces, each piezoelectric ceramic sheet is provided with a wire electrically connected to the corresponding wire interface. When the regulator of the present invention is energized, the piezoelectric sheet expands along the axial direction, and the disc gap is reduced before the brake master cylinder builds pressure, so as to achieve the purpose of reducing the amount of brake fluid required; when the power is stopped, the piezoelectric sheet contracts, and the caliper piston retreats, so as to achieve the purpose of reducing the drag torque.

Description

Technical Field

[0001] The invention relates to vehicle braking technology, in particular to a piezoelectric brake hydraulic regulator and a hydraulic brake system and a control method thereof. Background Art

[0002] In the design process of hydraulic disc brakes, there are two key performances - fluid requirement and drag torque. Fluid requirement is the volume of brake fluid that needs to be injected from the master cylinder into the brake system to reach a certain pressure. Drag torque is the friction torque generated by the friction between the brake disc and the brake pad after the brake caliper is released.

[0003] There is a certain contradiction between the two key performances mentioned above. 1) Reducing the drag torque can optimize noise, increase the service life of the brake disc and brake pad, and increase the vehicle's driving range, but it requires an increase in the required fluid volume; and the increase in the required fluid volume will affect the pedal feel, increase the brake idle travel, and feel powerless when stepping on the pedal. In addition, the amount of fluid provided by the master cylinder to the hydraulic pipeline is limited, and the required fluid volume cannot be increased arbitrarily. 2) Reducing the required fluid volume requires a small gap between the brake disc and the friction pad under existing technical conditions, which can optimize the pedal feel, but will increase the drag.

[0004] At present, in order to meet the needs of new energy vehicles to reduce the drag torque of wheel side parts, various brake caliper suppliers basically adopt methods such as increasing and optimizing the friction plate return spring and optimizing the rectangular ring groove size between the caliper piston and the caliper body. These methods have limited effect in reducing drag and need to balance the impact of increased fluid volume. Alternatively, IBC boosters can be used to quickly build pressure and reduce the impact of increased fluid volume on pedal feel.

[0005] Piezoelectric ceramics are functional materials that can convert mechanical energy and electrical energy into each other, and have an inverse piezoelectric effect: the material produces controllable strain at the moment an electric field is applied. This principle can be used in piezoelectric ceramic micro-displacement actuators. The Chinese invention patent with publication number CN 114433993 A discloses a cutter adjustment device, which is used in the field of semiconductor packaging. Through the inverse piezoelectric effect of piezoelectric ceramics, the deformation is controlled by voltage changes, and the deformation of the piezoelectric ceramics is converted into a specific direction of movement of the cutter head through the structure of the cutter, thereby adjusting the distance between the cutter and the splitting knife, thereby changing the cutting length of the aluminum wire. The Chinese invention patent with publication number CN 112112786 A discloses a design method for a silent variable displacement pump and a piezoelectric ceramic pump, which belongs to the field of pumps. The inverse piezoelectric effect of piezoelectric ceramics is used to drive the volume change of the pump cavity, and cooperates with two one-way valves F1 and F2 to drive the liquid to flow in one direction. The devices in the above patents cannot be applied to the field of automobile braking, and there is no device in the prior art that can solve the contradiction between the required fluid volume and the drag torque through piezoelectric ceramics.

[0006] Therefore, it is necessary to develop a piezoelectric brake hydraulic regulator and its hydraulic brake system and control method which are simple in structure, easy to use, reduce the required fluid volume and reduce the drag torque. Summary of the invention

[0007] The purpose of the present invention is to solve the shortcomings of the above-mentioned background technology and provide a piezoelectric brake hydraulic regulator and its hydraulic brake system and control method which are simple in structure, easy to use, reduce the required fluid volume and reduce the drag torque.

[0008] The technical solution of the present invention is: a piezoelectric brake fluid pressure regulator, characterized in that it includes a cylindrical shell filled with brake fluid and a plurality of piezoelectric ceramic sheets axially spaced apart in the shell, a plurality of rubber mounting rings axially spaced apart are arranged on the inner wall of the shell, each piezoelectric ceramic sheet is correspondingly mounted on each rubber mounting ring, a flow hole is provided on the rubber mounting ring for the brake fluid to flow when the volume of the piezoelectric ceramic sheet changes, a plurality of wire interfaces are provided on the shell, and each piezoelectric ceramic sheet is provided with a wire electrically connected to the corresponding wire interface.

[0009] Preferably, the rubber mounting ring is coaxially arranged with the housing, an annular mounting groove is provided on the inner edge of the rubber mounting ring, and the edge of the piezoelectric ceramic sheet is clamped in the mounting groove.

[0010] Preferably, a through hole is provided between the bottom of the mounting groove and the outer wall of the rubber mounting ring, and the wire of the piezoelectric ceramic sheet passes through the through hole, and the aperture of the through hole corresponds to the outer diameter of the wire.

[0011] Preferably, the rubber mounting ring is bonded to the inner wall of the shell or clamped in an annular groove formed on the inner wall of the shell.

[0012] Preferably, the surface of the piezoelectric ceramic sheet is coated with a resin material resistant to brake fluid corrosion.

[0013] Preferably, the flow holes are oblong holes, which are arranged at equal intervals in the circumferential direction on the rubber mounting ring.

[0014] Preferably, pipeline interfaces are provided at both axial ends of the shell.

[0015] Preferably, a plurality of piezoelectric ceramic sheets are axially evenly spaced within the housing, and a plurality of wire interfaces are axially evenly spaced on the housing.

[0016] The present invention also provides a hydraulic brake system, including a vacuum booster, a brake pedal and a brake master cylinder, a hydraulic brake pipe, and a brake caliper, wherein the brake pedal is connected to the brake master cylinder via the vacuum booster, and the hydraulic brake pipe connects the brake master cylinder and the brake caliper, and also includes any of the piezoelectric brake hydraulic regulators described above, wherein the piezoelectric brake hydraulic regulator is connected in series to the hydraulic brake pipe, the piezoelectric brake hydraulic regulator is located adjacent to the brake caliper or integrated on the brake caliper, and the piezoelectric brake hydraulic regulator is electrically connected to a power management module.

[0017] The present invention also provides at least one control method of a hydraulic brake system, including a braking control method and a brake release control method, wherein the braking control method comprises the following steps:

[0018] S1. The driver steps on the brake pedal, and the brake pedal signal is transmitted to the ECU, which then inputs a signal to the power management module. The power management module inputs a voltage to the piezoelectric brake hydraulic regulator according to the signal;

[0019] S2. The piezoelectric ceramic inside the piezoelectric brake hydraulic regulator expands due to the reverse piezoelectric effect, the hydraulic pressure inside the hydraulic brake pipe increases, the friction pad moves toward the brake disc, and the disc gap is reduced. It takes no more than 10ms from the time the brake pedal is pressed to send a brake signal to the time the disc gap is reduced.

[0020] S3. The vacuum booster builds pressure in the brake master cylinder, driving the friction pad of the brake caliper to clamp the brake disc to complete braking.

[0021] Preferably, the disc gap H after being reduced in step S2 satisfies 0mm≤H≤0.05mm.

[0022] Preferably, the brake release control method comprises the following steps:

[0023] S1. After the braking is completed, the driver releases the brake pedal, and the brake pedal release signal is transmitted to the ECU, which then inputs a signal to the power management module. The power management module cancels the input voltage to the piezoelectric brake hydraulic regulator according to the signal;

[0024] S2. The piezoelectric ceramic inside the piezoelectric brake hydraulic regulator shrinks due to the inverse piezoelectric effect, and the hydraulic pressure inside the hydraulic brake pipe decreases.

[0025] S3. The vacuum booster relieves the pressure in the brake master cylinder, driving the friction pad of the brake caliper to separate from the brake disc, thus releasing the brake.

[0026] The beneficial effects of the present invention are:

[0027] 1. There are wires extending from the edge of the piezoelectric ceramic sheet to connect to the power supply. At the moment of power on, the piezoelectric sheet expands and deforms along the axial direction, squeezing the space occupied by the brake fluid, increasing the hydraulic pressure, applying pressure to the caliper piston to move it outward, and pushing the friction plate closer to the brake disc. Reducing the disc gap before the brake master cylinder builds pressure can achieve the purpose of reducing the amount of brake fluid required.

[0028] 2. The deformation of a single piezoelectric ceramic piece is small, and multiple piezoelectric ceramic pieces can be integrated inside the housing to reduce the disc gap to the required value during braking, thereby improving the pressure-building capacity of the hydraulic regulator. The piezoelectric ceramic piece is fixed in the housing through a rubber mounting ring, and the rubber mounting ring can be fixed to the inner wall of the housing by gluing or slotting, and the setting method is simple and flexible.

[0029] 3. The piezoelectric ceramic material is immersed in brake fluid for a long time, and the surface of the piezoelectric ceramic sheet is encapsulated with a resin material with epoxy resin, polytetrafluoroethylene resin or EPDM as the main component to resist brake fluid corrosion.

[0030] 4. The rubber mounting ring is provided with flow holes so that the brake fluid can flow freely on both sides of the piezoelectric ceramic plate to balance the hydraulic pressure.

[0031] 5. When the hydraulic regulator is used for brake control in the brake system, it takes about 150 to 200 ms from the time the brake pedal is pressed to the time the brake master cylinder builds pressure. Due to the rapid deformation characteristics of the piezoelectric ceramic sheet, it takes less than 10 ms from the time the brake pedal is pressed to the time the disc gap is reduced, which is much shorter than the time it takes for the brake master cylinder to complete pressure building. The disc gap can be quickly reduced before the brake master cylinder completes pressure building, thereby reducing the amount of brake fluid required.

[0032] 6. When the hydraulic regulator is used in the brake system to release the brake control, the hydraulic regulator is powered off and contracted, and the brake master cylinder is depressurized, the pressure in the hydraulic brake pipeline is reduced, and the piston of the brake caliper retreats. The retreat amount is greater than that of the caliper on the ordinary hydraulic pipeline that is not equipped with a hydraulic regulator, so that the disc is separated, achieving the purpose of reducing the drag torque. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the housing structure of the piezoelectric brake hydraulic regulator of the present invention

[0034] Figure 2 Schematic diagram of the piezoelectric ceramic structure of the piezoelectric brake hydraulic regulator of the present invention

[0035] Figure 3 Schematic diagram of the connection between the piezoelectric ceramic sheet and the rubber mounting ring

[0036] Figure 4 Axial cross-sectional view of the connection between the piezoelectric ceramic plate and the rubber mounting ring

[0037] Figure 5 Flow chart of the braking control method of the present invention

[0038] Figure 6 Flow chart of the brake release control method of the present invention

[0039] Wherein: 1-housing 2-piezoelectric ceramic sheet 3-rubber mounting ring 4-flow hole 5-conductor 6-conductor interface 7-mounting groove 8-through hole 9-pipeline interface 10-piezoelectric brake hydraulic regulator. DETAILED DESCRIPTION

[0040] The following specific examples further illustrate the present invention in detail.

[0041] like Figure 1-4 As shown, the present invention provides a piezoelectric brake fluid regulator, including a cylindrical shell 1 filled with brake fluid and a plurality of piezoelectric ceramic sheets 2 axially spaced apart in the shell 1, pipeline interfaces 9 are provided at both axial ends of the shell 1, a plurality of rubber mounting rings 3 are axially spaced apart on the inner wall of the shell 1, each piezoelectric ceramic sheet 2 is correspondingly mounted on each rubber mounting ring 3, and a flow hole 4 is provided on the rubber mounting ring 3 for the brake fluid to flow when the volume of the piezoelectric ceramic sheet 2 changes, a plurality of wire interfaces 6 are provided on the shell 1, and each piezoelectric ceramic sheet 2 is provided with a wire 5 electrically connected to the corresponding wire interface 6.

[0042] The rubber mounting ring 3 is coaxially arranged in the housing 1, and an annular mounting groove 7 is provided on the inner edge of the rubber mounting ring 3, and the edge of the piezoelectric ceramic piece 2 is clamped in the mounting groove 7. A through hole 8 is provided between the bottom of the mounting groove 7 and the outer wall of the rubber mounting ring 3, and the wire 5 of the piezoelectric ceramic piece 2 passes through the through hole 8, and the aperture of the through hole 8 corresponds to the outer diameter of the wire 5. The piezoelectric ceramic piece 2 is fixedly installed by the rubber mounting ring 3 because the rubber mounting ring 3 has elasticity, so that the piezoelectric ceramic piece 2 can be stably connected inside the housing 1 even if it is deformed.

[0043] The rubber mounting ring 3 is bonded to the inner wall of the housing 1 or clamped in the annular groove provided on the inner wall of the housing 1. The installation method of the rubber mounting ring 3 can be flexibly selected according to needs. In this embodiment, the rubber mounting ring 3 is bonded to the inner wall of the housing 1. The flow holes 4 on the rubber mounting ring 3 are oblong holes, which are arranged at equal intervals on the rubber mounting ring 3 in the circumferential direction.

[0044] In this embodiment, the number of piezoelectric ceramic sheets 2 is 3, which are arranged at equal intervals in the axial direction in the housing 1. The piezoelectric ceramic sheets 2 are deformed in the axial direction when the power is turned on. The surface of the piezoelectric ceramic sheets 2 is coated with a resin or rubber material resistant to brake fluid corrosion, such as epoxy resin, polytetrafluoroethylene resin or EPDM resin as the main component. The number of rubber mounting rings 3 is also 3, and each piezoelectric ceramic sheet 2 is installed accordingly. Four flow holes 4 are arranged at equal intervals in the circumferential direction on the rubber mounting rings 3. The number of wire interfaces 6 is also 3, which are arranged at equal intervals in the axial direction at the top of the housing 1.

[0045] This embodiment also provides a hydraulic brake system, including a vacuum booster, a brake pedal and a brake master cylinder, a hydraulic brake pipe, and a brake caliper. The brake pedal is connected to the brake master cylinder via the vacuum booster, and the hydraulic brake pipe connects the brake master cylinder and the brake caliper. It also includes the above-mentioned piezoelectric brake hydraulic regulator 10, which is connected in series to the hydraulic brake pipe through a pipeline interface 9. The piezoelectric brake hydraulic regulator 10 is located near the brake caliper or integrated on the brake caliper. The piezoelectric brake hydraulic regulator 10 is electrically connected to the power management module through a wire interface 6.

[0046] like Figure 5 As shown, the braking control method of the above hydraulic brake system includes the following steps:

[0047] S1. At zero time, the driver steps on the brake pedal, and the brake pedal signal is transmitted to the ECU, and the ECU inputs a signal to the power management module, and the power management module inputs a voltage to the piezoelectric brake hydraulic regulator 10 according to the signal;

[0048] S2. The piezoelectric ceramic piece 2 inside the piezoelectric brake fluid pressure regulator 10 expands in volume due to the inverse piezoelectric effect. At about 10 μs, the hydraulic pressure inside the hydraulic brake pipe increases, and the friction plate moves toward the brake disc, reducing the disc gap. The disc gap is completely reduced at 1 to 10 ms, and the disc gap H after reduction satisfies 0 mm ≤ H ≤ 0.05 mm (in the prior art, the disc gap of ordinary calipers when not braking is as high as 0.5-1 mm);

[0049] At S3.150~200ms, the vacuum booster completes the pressure building of the brake master cylinder, drives the friction pad of the brake caliper to clamp the brake disc, and completes braking (because the disc gap has been reduced to 0mm≤H≤0.05mm before the brake master cylinder builds pressure, the amount of fluid required for the caliper brake is reduced).

[0050] like Figure 6 As shown, the above hydraulic brake system brake release control method includes the following steps:

[0051] S1. After the braking is completed, the driver releases the brake pedal, and the brake pedal release signal is transmitted to the ECU, and the ECU inputs a signal to the power management module, and the power management module cancels the input voltage to the piezoelectric brake hydraulic regulator 10 according to the signal;

[0052] S2. The piezoelectric ceramic piece 2 inside the piezoelectric brake fluid pressure regulator 10 shrinks in volume due to the inverse piezoelectric effect, and the hydraulic pressure inside the brake line decreases;

[0053] S3. The vacuum booster releases pressure from the brake master cylinder, and the pressure in the hydraulic brake pipeline drops to 0. The brake caliper piston retreats (the retreat amount of the piston in the present invention = the retreat amount caused by the decompression of the brake master cylinder + the retreat amount caused by the volume contraction of the piezoelectric ceramic piece 2. Therefore, compared with the brake caliper in the prior art that is not equipped with a hydraulic regulator, the retreat amount of the present invention is greatly increased), driving the friction plate of the brake caliper to separate from the brake disc. At this time, the drag torque is greatly reduced or even eliminated, and the brake is released.

Claims

1. A hydraulic brake system, comprising a vacuum booster, a brake pedal and a brake master cylinder, a hydraulic brake pipe, and a brake caliper, wherein the brake pedal is connected to the brake master cylinder via the vacuum booster, and the hydraulic brake pipe connects the brake master cylinder to the brake caliper. It is characterized in that It also includes a piezoelectric brake hydraulic pressure regulator (10), the piezoelectric brake hydraulic pressure regulator (10) is connected in series to the hydraulic brake pipeline, the piezoelectric brake hydraulic pressure regulator (10) is located near the brake caliper or integrated on the brake caliper, and the piezoelectric brake hydraulic pressure regulator (10) is electrically connected to the power management module via a wire interface (6); The piezoelectric brake fluid regulator (10) comprises a cylindrical housing (1) filled with brake fluid and a plurality of piezoelectric ceramic sheets (2) axially spaced apart in the housing (1); a plurality of rubber mounting rings (3) are axially spaced apart on the inner wall of the housing (1); each piezoelectric ceramic sheet (2) is correspondingly mounted on each rubber mounting ring (3); a flow hole (4) is provided on the rubber mounting ring (3) for the brake fluid to flow when the volume of the piezoelectric ceramic sheet (2) changes; the flow hole (4) is an oblong hole and is circumferentially evenly spaced apart on the rubber mounting ring (3); a plurality of wire interfaces (6) are provided on the housing (1); each piezoelectric ceramic sheet (2) is provided with a wire (5) electrically connected to the corresponding wire interface (6); The control method of the hydraulic brake system includes a braking control method and a brake release control method, and the braking control method includes the following steps: S1. The driver presses the brake pedal, and the brake pedal signal is transmitted to the ECU, and the ECU then inputs a signal to the power management module, and the power management module inputs a voltage to the piezoelectric brake hydraulic regulator (10) according to the signal; S2. The piezoelectric ceramic sheet (2) inside the piezoelectric brake hydraulic regulator (10) expands in volume due to the inverse piezoelectric effect, the hydraulic pressure inside the hydraulic brake pipe increases, the friction plate moves toward the brake disc, and the disc gap is reduced. It takes no more than 10 ms from the time the brake pedal is pressed to send a brake signal to the time the disc gap is reduced. S3. The vacuum booster builds pressure in the brake master cylinder, driving the friction pad of the brake caliper to clamp the brake disc to complete the braking process; The brake release control method comprises the following steps: S1. After the braking is completed, the driver releases the brake pedal, and the brake pedal release signal is transmitted to the ECU, and the ECU then inputs a signal to the power management module. The power management module cancels the input voltage to the piezoelectric brake hydraulic regulator (10) according to the signal; S2. The piezoelectric ceramic sheet (2) inside the piezoelectric brake hydraulic regulator (10) shrinks in volume due to the inverse piezoelectric effect, and the hydraulic pressure inside the hydraulic brake pipe decreases. S3. The vacuum booster relieves the pressure in the brake master cylinder, driving the friction pad of the brake caliper to separate from the brake disc, thus releasing the brake.

2. The hydraulic brake system according to claim 1, It is characterized in that The rubber mounting ring (3) is coaxially arranged with the housing (1); an annular mounting groove (7) is provided on the inner edge of the rubber mounting ring (3); and the edge of the piezoelectric ceramic sheet (2) is clamped in the mounting groove (7).

3. The hydraulic brake system according to claim 2, It is characterized in that A through hole (8) is provided between the bottom of the mounting groove (7) and the outer wall of the rubber mounting ring (3), and the wire (5) of the piezoelectric ceramic sheet (2) passes through the through hole (8), and the diameter of the through hole (8) corresponds to the outer diameter of the wire (5).

4. The hydraulic brake system according to claim 1, It is characterized in that The rubber mounting ring (3) is bonded to the inner wall of the shell (1) or clamped in an annular groove formed on the inner wall of the shell (1).

5. The hydraulic brake system according to claim 1, It is characterized in that The surface of the piezoelectric ceramic sheet (2) is coated with a resin material that is resistant to brake fluid corrosion.

6. The hydraulic brake system according to claim 1, It is characterized in that Pipeline interfaces (9) are provided at both axial ends of the housing (1).

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