Small electronic brake with brushless motor rotor position detection

Abstract

The present invention discloses a small electronic brake with brushless motor rotor position detection, comprising a brake master cylinder assembly, a trapezoidal screw, a motor shaft end position sensor, and a brushless motor drive unit. A pressure sensor is mounted on the lower side of the rear end of the brake master cylinder assembly, the front end of the brake master cylinder assembly is connected to a rear housing, the front end of the rear housing is connected to a front housing, the front housing, the rear housing, and the brake master cylinder assembly are fixed by mounting bolts, a large gear is disposed inside the rear housing, a trapezoidal screw is mounted on the axis of the large gear, a bearing is disposed between the front end of the large gear and the front housing, the front end of the bearing is fixed by a retaining spring, and a guide sleeve is disposed on the outside of the front side of the trapezoidal screw. The present invention is driven by a brushless motor drive unit, the large gear and the trapezoidal screw cooperate, and the device is small in size. The brushless motor is used, resulting in low noise, long life, and low failure rate. The device can detect the number of revolutions and angles of the motor, calculate the position of the trapezoidal screw, and has low processing cost.

Description

Technical Field

[0001] The present invention relates to the field of vehicle brake components, in particular to a small electronic brake with brushless motor rotor position detection. Background Art

[0002] A vehicle's electronic brake-by-wire system applies brake fluid pressure to the vehicle's wheel brakes to slow or stop the vehicle when it receives an external signal, such as an active brake command signal on the CAN bus. Its performance directly impacts vehicle safety. The rapid rise of autonomous logistics vehicles and sightseeing vehicles has intensified the demand for brake-by-wire systems with low failure rates and long service lives. Currently, most low-speed autonomous vehicles are powered by brushed DC motors. Due to the presence of a mechanical commutator, brushed DC motors have a shorter service life and a higher failure rate than brushless motors. Braking system failure is unacceptable.

[0003] In the field of purely autonomous driving, existing brake system technologies suffer from being oversized (Bosch ibooster), having a short lifespan (brushless motor solutions), being noisy (brushless motor solutions), and having poor reliability (brushless motor solutions). A compact electronic brake system based on a brushless motor is proposed to address the short lifespan, poor reliability, and large size of conventional electronic brakes in vehicles with limited installation space. Summary of the Invention

[0004] The object of the present invention is to provide a small electronic brake with brushless motor rotor position detection in order to solve the above problems.

[0005] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0006] A small electronic brake with brushless motor rotor position detection includes a brake master cylinder assembly, a trapezoidal screw, a motor shaft end position sensor, and a brushless motor drive unit. A pressure sensor is installed on the lower side of the rear end of the brake master cylinder assembly, the front end of the brake master cylinder assembly is connected to the rear housing, the front end of the rear housing is connected to the front housing, the front housing, the rear housing, and the brake master cylinder assembly are fixed by mounting bolts, a large gear is provided inside the rear housing, the trapezoidal screw is installed on the axis of the large gear, a bearing is provided between the front end of the large gear and the front housing, the front end of the bearing is fixed by a retaining spring, a guide sleeve is provided on the outside of the front side of the large gear, the lower end of the top front side of the trapezoidal screw is connected to the front housing through a limit pin, a guide groove is provided between the trapezoidal screw and the front housing, the lower end of the large gear is meshed with the brushless motor pinion, the axis of the brushless motor pinion is connected to the brushless motor output shaft of the brushless motor drive unit, and an ECU is installed on the rear end of the brushless motor drive unit A motor shaft end position sensor is provided between the brushless motor drive unit and the ECU controller.

[0007] Preferably, the brushless motor output shaft is keyed to the motor shaft end position sensor and the brushless motor pinion.

[0008] With such an arrangement, the motor shaft end position sensor is used to detect the rotation angle of the output shaft of the brushless motor, and the brushless motor pinion is used to output power.

[0009] Preferably, the large gear is connected to the trapezoidal lead screw via a thread, the limiting pin is connected to the trapezoidal lead screw via a thread, and the guide groove is integrally formed with the front housing.

[0010] With such arrangement, the rotating shaft of the large gear cooperates with the trapezoidal screw rod to reciprocate and extend.

[0011] Preferably, the guide sleeve and the front housing are interference fit, the guide sleeve and the trapezoidal lead screw are clearance fit, and the bearing is interference fit with the large gear and the front housing.

[0012] With such arrangement, the guide sleeve is used to stabilize the stability of the trapezoidal lead screw during its extension and retraction.

[0013] Preferably, the brushless motor drive unit is connected to the rear housing via bolts, and the ECU controller is connected to the brushless motor drive unit via screws.

[0014] With this arrangement, the brushless motor drive unit is used to provide power, and the ECU controller is used for control and detection.

[0015] Preferably, the pressure sensor is connected to the brake master cylinder assembly via bolts.

[0016] With this arrangement, the pressure sensor is used to detect the pressure of the brake master cylinder assembly.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. This solution uses a brushless motor drive unit, a large gear and a trapezoidal lead screw. It is small in size and uses a brushless motor with low noise, long life and low failure rate. It can detect the number of turns and angles of the motor to calculate the moving position of the trapezoidal lead screw, and the processing cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 It is a structural schematic diagram of a small electronic brake with brushless motor rotor position detection according to the present invention;

[0021] Figure 2 It is a schematic diagram of the exploded structure of the small electronic brake with brushless motor rotor position detection according to the present invention;

[0022] Figure 3 It is a schematic diagram of the internal structure of the small electronic brake with brushless motor rotor position detection according to the present invention.

[0023] The following are the descriptions of the reference numerals:

[0024] 1. Pressure sensor; 2. Brake master cylinder assembly; 3. Front housing; 4. Rear housing; 5. Large gear; 6. Bearing; 7. Guide sleeve; 8. Trapezoidal lead screw; 9. Limit pin; 10. Guide groove; 11. Circlip; 12. Mounting bolt; 13. Brushless motor pinion; 14. Brushless motor output shaft; 15. Brushless motor drive unit; 16. ECU controller; 17. Motor shaft end position sensor. DETAILED DESCRIPTION

[0025] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0026] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0027] The present invention will be further described below in conjunction with the accompanying drawings:

[0028] Example 1

[0029] like Figure 1-Figure 3 As shown, a small electronic brake with brushless motor rotor position detection includes a brake master cylinder assembly 2, a trapezoidal screw 8, a motor shaft end position sensor 17, and a brushless motor drive unit 15. A pressure sensor 1 is installed on the lower side of the rear end of the brake master cylinder assembly 2. The front end of the brake master cylinder assembly 2 is connected to the rear housing 4, and the front end of the rear housing 4 is connected to the front housing 3. The front housing 3, the rear housing 4, and the brake master cylinder assembly 2 are fixed by mounting bolts 12. A large gear 5 is provided inside the rear housing 4, and a trapezoidal screw 8 is installed on the axis of the large gear 5. A bearing 6 is provided between the front end of the large gear 5 and the front housing 3, and the front end of the bearing 6 is fixed by a retaining spring 11. A trapezoidal screw rod 8 is located on the front side of the large gear 5 and is provided with a guide sleeve 7 on the outside. The lower end of the top front end of the trapezoidal screw rod 8 is connected to the front housing 3 through a limit pin 9. A guide groove 10 is provided between the trapezoidal screw rod 8 and the front housing 3. The lower end of the large gear 5 is engaged with the brushless motor pinion 13. The axis of the brushless motor pinion 13 is connected to the brushless motor output shaft 14 of the brushless motor drive unit 15. An ECU controller 16 is installed at the rear end of the brushless motor drive unit 15, and a motor shaft end position sensor 17 is provided between the brushless motor drive unit 15 and the ECU controller 16.

[0030] Preferably: the brushless motor output shaft 14 is key-connected to the motor shaft end position sensor 17 and the brushless motor pinion 13, the motor shaft end position sensor 17 is used to detect the rotation angle of the brushless motor output shaft 14, and the brushless motor pinion 13 is used to output power; the large gear 5 is connected to the trapezoidal screw rod 8 by a thread, the limit pin 9 is connected to the trapezoidal screw rod 8 by a thread, and the guide groove 10 is integrally formed on the front housing 3, and the rotating shaft of the large gear 5 cooperates with the trapezoidal screw rod 8 to reciprocate and extend; the guide sleeve 7 and the front housing 3 have an interference fit, the guide sleeve 7 and the trapezoidal screw rod 8 have a clearance fit, the bearing 6 has an interference fit with the large gear 5 and the front housing 3, and the guide sleeve 7 is used to stabilize the stability of the trapezoidal screw rod 8 during extension and retraction; the brushless motor drive unit 15 is connected to the rear housing 4 by bolts, and the ECU controller 16 is connected to the brushless motor drive unit 15 by screws. The brushless motor drive unit 15 is used to provide power, and the ECU controller 16 is used for control and detection; the pressure sensor 1 is connected to the brake master cylinder assembly 2 by bolts, and the pressure sensor 1 is used to detect the pressure of the brake master cylinder assembly 2.

[0031] Working principle:

[0032] Normal working mode: After the ECU controller 16 receives the active braking command sent via the CAN bus, it drives the brushless motor output shaft 14 of the brushless motor drive unit 15 to rotate, and the brushless motor pinion 13 coaxial with the brushless motor output shaft 14 rotates together. The coaxial brushless motor pinion 13 engages with the large gear 5 for transmission. The center of the large gear 5 has a trapezoidal thread. The rotation of the large gear 5 drives the trapezoidal screw 8 with a limit pin 9 to perform linear motion in the guide groove 10 in the guide sleeve 7 embedded in the front housing 3 and positioned by the retaining spring 11, pushing the brake master cylinder assembly 2 to establish braking pressure. The ECU controller 16 detects the brake fluid pressure in the brake master cylinder assembly 2 in real time and compares it with the target pressure in real time. According to the actual pressure feedback and the target braking pressure in the command, the torque and rotation direction of the brushless motor drive unit 15 are adjusted to perform precise pressure closed-loop control. The mounting bolts 12 on the front housing 3 are used for installation to the use environment.

[0033] Pressure sensor failure: When the pressure sensor 1 fails, the ECU controller 16 cannot accurately determine the master cylinder pressure. The ECU controller 16 calculates the number of revolutions of the motor shaft through the motor shaft end position sensor 17. Since there is a fixed transmission ratio between the brushless motor output shaft 14 and the trapezoidal screw 8, the ECU controller 16 can accurately control the position of the trapezoidal screw 8 in this way. Since there is a mathematical correspondence between the brake pressure in the brake master cylinder assembly 2 and the trapezoidal screw 8, the ECU controller 16 can use the motor shaft end position sensor 17 to achieve open-loop control of the pressure after receiving the brake command.

[0034] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications fall within the scope of the invention as claimed.

Claims

1. A small electronic brake with brushless motor rotor position detection, characterized by: The invention comprises a brake master cylinder assembly (2), a trapezoidal screw rod (8), a motor shaft end position sensor (17), and a brushless motor drive unit (15). A pressure sensor (1) is installed on the lower side of the rear end of the brake master cylinder assembly (2). The front end of the brake master cylinder assembly (2) is connected to a rear housing (4). The front end of the rear housing (4) is connected to a front housing (3). The front housing (3), the rear housing (4), and the brake master cylinder assembly (2) are fixed by mounting bolts (12). A large gear (5) is provided inside the rear housing (4). The trapezoidal screw rod (8) is installed on the axis of the large gear (5). A bearing (6) is provided between the front end of the large gear (5) and the front housing (3). The front end of the bearing (6) is fixed by a retaining spring ( 11) is fixed, the trapezoidal screw rod (8) is located on the front side of the large gear (5) and is provided with a guide sleeve (7), the lower end of the front top of the trapezoidal screw rod (8) is connected to the front housing (3) through a limit pin (9), a guide groove (10) is provided between the trapezoidal screw rod (8) and the front housing (3), the lower end of the large gear (5) is meshed with the brushless motor pinion (13), the axis of the brushless motor pinion (13) is connected to the brushless motor output shaft (14) of the brushless motor drive unit (15), the rear end of the brushless motor drive unit (15) is installed with an ECU controller (16), and a motor shaft end position sensor (17) is provided between the brushless motor drive unit (15) and the ECU controller (16); The motor shaft end position sensor (17) is used to detect the rotation angle of the brushless motor output shaft (14), and calculate the number of revolutions of the brushless motor output shaft (14) through the ECU controller (16) to control the moving position of the trapezoidal lead screw (8); There is a preset mathematical correspondence between the brake pressure in the brake master cylinder assembly (2) and the trapezoidal screw (8), and the ECU controller (16) uses the motor shaft end position sensor (17) to achieve open-loop control of the brake pressure; The guide sleeve (7) and the trapezoidal screw rod (8) are clearance-fitted.

2. The small electronic brake with brushless motor rotor position detection according to claim 1, characterized in that: The brushless motor output shaft (14) is key-connected to the motor shaft end position sensor (17) and the brushless motor pinion (13).

3. The small electronic brake with brushless motor rotor position detection according to claim 1, characterized in that: The large gear (5) is connected to the trapezoidal screw rod (8) via a thread, the limiting pin (9) is connected to the trapezoidal screw rod (8) via a thread, and the guide groove (10) is integrally formed on the front housing (3).

4. The small electronic brake with brushless motor rotor position detection according to claim 1, characterized in that: The guide sleeve (7) and the front housing (3) are interference-fitted, and the bearing (6) is interference-fitted with the large gear (5) and the front housing (3).

5. The small electronic brake with brushless motor rotor position detection according to claim 1, characterized in that: The brushless motor drive unit (15) is connected to the rear housing (4) via bolts, and the ECU controller (16) is connected to the brushless motor drive unit (15) via screws.

6. The small electronic brake with brushless motor rotor position detection according to claim 1, characterized in that: The pressure sensor (1) is connected to the brake master cylinder assembly (2) via bolts.

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