Electromechanical brake actuator

Abstract

The application discloses an electromechanical brake actuator, comprising a motor and a transmission mechanism, the motor comprises a motor body and a motor shaft penetrating through the motor body, a motor bearing is arranged on the motor shaft, a damping mechanism for damping the motor shaft is arranged on one side or both sides of the motor bearing, and the damping mechanism is an elastic element, a damping element or a combination of the elastic element and the damping element. The electromechanical brake actuator can eliminate or reduce the axial vibration of the motor shaft and internal components, reduce the coupling of component vibration and gear meshing movement, and make the transmission stable, so that the release impact noise of the electromechanical brake system is eliminated.

Description

Technical Field

[0001] This invention belongs to the field of braking system technology, specifically, this invention relates to an electromechanical brake actuator. Background Technology

[0002] In existing technologies, electromechanical brake actuators are gradually becoming the mainstream. The first stage of gear transmission mainly uses helical gear transmission or worm gear transmission. When the motor starts, the axial force transmitted by the motor gears or worm causes the motor rotor to move axially. Furthermore, due to the existence of more or less 'play' in the motor, the axial displacement direction of the motor shaft changes, causing the internal components of the motor to vibrate. These vibrations couple with the meshing motion of the gear pair, thus producing a brief period of unstable gear transmission. In actual vehicles, this manifests as a sound similar to a release impact that can be heard from the driver's position.

[0003] The mainstream solution to the impact noise caused by the above problems is as follows:

[0004] Option 1: Use a high-cost motor equipped with deep groove ball bearings;

[0005] Option 2: Use an oil-impregnated bearing motor, but add a vibration damping device (such as a rubber pad) to the transmission system.

[0006] Option 1, a common practice in existing technologies, uses deep groove ball bearings in the motors of electromechanical brake actuators. Deep groove ball bearings have small clearance values, which reduces axial movement of the motor shaft and decreases the coupling between motor shaft vibration and gear meshing motion. Furthermore, under radial loads, vibration is transmitted through the impact between the rolling elements and the inner and outer raceways, resulting in good vibration damping and noise reduction. Motors equipped with deep groove ball bearings used in actuators produce no audible impact noise.

[0007] However, deep groove ball bearings are more expensive than oil-impregnated bearings, and their assembly process is also more complex. Using deep groove ball bearings will lead to increased manufacturing and assembly costs.

[0008] Option 2 still uses an oil-impregnated bearing motor, but adds several rubber pads to the last stage of the actuator's transmission mechanism. For details, see patent document CN104603492A. The rubber damping is used to reduce the vibration generated by the motor, but the installation of rubber pads significantly increases the manufacturing and assembly costs of the product.

[0009] When the first-stage transmission mechanism has helical gears or worm gears and the motor uses oil-impregnated bearings, the axial movement of the motor rotor will be coupled with the meshing movement of the gears, resulting in a noise similar to an impact noise when the electromechanical brake actuator is released. Summary of the Invention

[0010] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, the present invention provides an electromechanical brake actuator, the purpose of which is to reduce or eliminate impact noise.

[0011] To achieve the above objectives, the technical solution adopted by the present invention is as follows: an electromechanical brake actuator, comprising a motor and a transmission mechanism, wherein the motor comprises a motor body and a motor shaft passing through the motor body, a motor bearing is provided on the motor shaft, and a vibration damping mechanism for damping the motor shaft is provided on one or both sides of the motor bearing, wherein the vibration damping mechanism is an elastic element, a damping element, or a combination of an elastic element and a damping element.

[0012] The elastic element is a spring, an elastic washer, or a combination of a spring and an elastic washer, and the damping element is grease.

[0013] The motor bearing is an oil-impregnated bearing, and the number of motor bearings is at least two.

[0014] The vibration damping mechanism is provided with pads on one or both sides, and the number of pads is one or more.

[0015] The end face of the gasket is patterned.

[0016] A limiting device is provided on the motor shaft, and a vibration damping mechanism is provided between the limiting device and the motor bearing. The number of limiting devices is one or more, and the number of vibration damping mechanisms is one or more.

[0017] The limiting device is a limiting ring or a limiting sleeve.

[0018] The limiting device is made of metal, rubber, or plastic.

[0019] A motor gear is mounted on the motor shaft and is connected to the transmission mechanism. The motor gear is either a worm gear or a helical gear.

[0020] The vibration damping mechanism is provided between the motor gear and the motor bearing.

[0021] The transmission mechanism includes a two-stage fixed-axis gear mechanism and a one-stage planetary gear mechanism connected in sequence. The two-stage fixed-axis gear mechanism includes a first double gear and a second double gear that mesh with each other. The first double gear is a spur gear, a helical gear, or a combination of spur gears and helical gears. The second double gear is a spur gear, a helical gear, or a combination of spur gears and helical gears.

[0022] The electromechanical brake actuator of the present invention can eliminate or reduce the axial vibration of the motor shaft and its internal components, reduce the coupling between component vibration and gear meshing motion, and make the transmission smooth, thereby eliminating the abnormal release impact noise of the electromechanical braking system. At the same time, the motor bearing is preferably selected as an oil-impregnated bearing, and the sum of the costs of the elastic element and / or damping element and the limiting device is much smaller than the difference between the oil-impregnated bearing and the deep groove ball bearing, effectively reducing the cost. Under the condition of low cost, it can still achieve the effect of eliminating abnormal release impact noise. Attached Figure Description

[0023] This manual includes the following figures, which illustrate the following:

[0024] Figure 1 This is a schematic diagram of the electromechanical brake actuator used in Case Study 1.

[0025] Figure 2 This is a schematic diagram of the motor structure in Case Study 1;

[0026] Figure 3 This is an enlarged view of the motor bearing end in Case Study 1;

[0027] Figure 4 This is a schematic diagram of the elastic element structure used in the motor in Case Study 1;

[0028] Figure 5 A schematic diagram of the elastic element structure used in the motor in Case Study 2;

[0029] Figure 6 The schematic diagram of the motor in Case 3 is provided for implementation.

[0030] Figure 7 This is a schematic diagram of the motor bearing end in Case Study 4;

[0031] Figure 8 Schematic diagram of the gasket structure used in the motors in Case Studies 1, 2, 3, and 4;

[0032] The markings in the diagram are as follows: 1. Motor; 2. Motor bearing; 3. Motor body; 4. Motor shaft; 5. Elastic element; 6. Limiting device; 7. Shim; 8. Damping element; 9. Motor gear; 10. First double gear; 11. Second double gear; 12. Planetary gear mechanism. Detailed Implementation

[0033] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, in order to help those skilled in the art to have a more complete, accurate and in-depth understanding of the concept and technical solutions of the present invention, and to facilitate its implementation.

[0034] The present invention aims to provide an electromechanical braking actuator that can reduce impact noise and lower the cost of existing actuators.

[0035] A problem with existing electromechanical braking systems is that when the actuator uses a motor with oil-impregnated bearings and helical gears in the first-stage transmission mechanism, a release-like noise can be heard from the driver's position during parking unlocking. This is because when the motor starts, the motor gear 9 experiences axial movement due to the axial force of the helical gear transmission; and due to the presence of some degree of play in the motor, the axial displacement direction of the motor shaft changes, causing vibrations in the internal components of the motor. These vibrations couple with the meshing motion of the gear pair, resulting in a brief period of unstable gear transmission, which manifests as a release-like noise audible from the driver's position in a real vehicle. Currently known solutions for reducing or eliminating the impact noise of electromechanical brake actuators all increase manufacturing and assembly costs.

[0036] A typical electric motor contains many internal components. A limiting ring is installed at the rotor end to secure the coil windings, and shims 7 are installed on both sides of the limiting ring. A bushing and shims 7 are also installed on the commutator side, but these components are not completely fixed. When the motor starts, if the first stage of transmission uses helical gears or worm gears, axial force is generated. The internal components of the motor, subjected to this axial force, will vibrate in random directions. Simultaneously, during motor startup, the motor gear 9 tends to move towards the output end of the motor shaft, exacerbating the axial vibration of the motor shaft. The vibration of the motor shaft and internal components, coupled with the meshing motion of the gear pair, creates a sound similar to an impact noise.

[0037] The electromechanical brake actuator of this invention can simultaneously reduce motor costs and solve abnormal impact noise: In this invention, the motor can be equipped with an oil-impregnated bearing, which is cheaper than a motor equipped with a deep groove ball bearing, thus reducing the cost of the actuator. At the same time, a limiting device 6 is added to the motor shaft end, and an elastic element 5 and / or a damping element 8 are installed between the limiting device 6 and the motor bearing. A shim 7 is set on one or both sides of the elastic element 5 and / or the damping element 8. Its function is to provide an axial preload to the motor shaft, eliminate motor play, suppress the axial movement tendency of the motor gear 9, reduce the coupling between the vibration of the motor shaft and internal components and the gear meshing motion, so that the transmission is smooth when the motor starts, thereby eliminating the release impact noise of the electromechanical braking system.

[0038] In summary, the electromechanical brake actuator of this invention has the following advantages:

[0039] 1. Reduce or eliminate impact noise: By installing elastic elements 5 and / or damping elements 8 on the motor bearing 2 side, as well as limiting device 6, the axial vibration of the motor shaft and its internal components can be eliminated or reduced, the coupling between component vibration and gear meshing motion can be reduced, the transmission can be made smooth, thereby eliminating the abnormal noise of release impact in the motor parking system.

[0040] 2. Cost reduction: The motor bearing 2 in this invention is preferably an oil-impregnated bearing. The sum of the costs of the elastic element 5 and / or damping element 8 and the limiting device 6 is much smaller than the difference between the oil-impregnated bearing and the deep groove ball bearing. Under the condition of low cost, it can still achieve the effect of eliminating abnormal release impact noise.

[0041] As an optional embodiment of the present invention, the limiting device 6 may be a limiting ring or a limiting sleeve, or other structures that can be fitted onto the motor shaft and limit the elastic element 5. The limiting device 6 may be a motor gear 9. The limiting device 6 is fixedly connected to the motor shaft, which can be achieved by press fitting, welding, or other methods. The material of the limiting device 6 may be metal, plastic, or rubber. The elastic element 5 may be a spring, an elastic washer, or other elastic structures or components, or a combination thereof. The material of the elastic element 5 may be metal, plastic, or rubber. Alternatively, a damping element 8 may be used instead of the elastic element 5. The damping element 8 may be made of grease, sludge, etc.

[0042] The combination of elastic element 5 and / or damping element 8 and limiting device 6 can be installed at the output shaft end of the motor shaft, or the opposite end, or inside the motor. Specifically, the installation location is on both sides of all motor bearings installed in the motor. The motor bearings are preferably oil-impregnated bearings, with at least two in number. The combination of limiting device 6 and elastic element 5 and / or damping element 8 can be one or more sets, installed on one or both sides of one or more of the above-mentioned bearings. The gasket 7 is made of wear-resistant material, and there are one or more in number. It can be installed on one or both sides of elastic element 5 or not installed at all.

[0043] A motor gear 9 is mounted on the output shaft end of the motor shaft. The motor gear 9 can be a helical gear or a worm gear, and it can also serve as a limiting device 6. The transmission mechanism includes a two-stage fixed-axis gear mechanism and a one-stage planetary gear mechanism 12 connected in sequence. The two-stage fixed-axis gear mechanism includes a first double gear 10 and a second double gear 11 that mesh with each other. The first double gear 10 is a spur gear, a helical gear, or a combination of spur gears and helical gears, and the second double gear 11 is a spur gear, a helical gear, or a combination of spur gears and helical gears. The transmission mechanism of the actuator can also be a worm gear drive, a full gear drive, or a combination of both.

[0044] The following are some implementation examples:

[0045] Example 1:

[0046] like Figure 1 As shown, Figure 1 The overall structural diagram of the electromechanical brake actuator in Case 1 is shown below: the actuator is preferably a full gear transmission type. The motor, motor gear 9, first double gear 10, second double gear 11, and planetary carrier are housed inside the outer casing. The motor gear 9 is fixedly mounted on the motor shaft 4. The first double gear 10 consists of a first driven gear and a second driving gear. The first driven gear meshes with the motor gear 9. The first driven gear and the second driving gear are coaxially fixedly connected, and the diameter of the first driven gear is larger than the diameter of the second driving gear. The second double gear 11 consists of a second driven gear and a third driving gear. The second driven gear meshes with the second driving gear. The second driven gear and the third driving gear are coaxially fixedly connected, and the diameter of the second driven gear is larger than the diameter of the third driving gear. The third driving gear serves as the sun gear of a planetary gear mechanism 12. The planetary carrier, the third driving gear, the gear ring, and the planetary gears form a first-stage planetary gear mechanism 12. The rotational force generated by the motor is transmitted to the first-stage planetary gear mechanism 12 via the motor gear 9, the first double gear 10, and the second double gear 11, and finally transmitted to the brake caliper assembly via the output shaft. The planetary gears are located between the second double gear 11 and the planet carrier. Multiple planetary gears are arranged, all distributed around the third driving gear of the second double gear 11. The third driving gear meshes with the planetary gears and serves as the sun gear of the planetary gear mechanism 12. The motor gear 9 and the first driven gear of the first double gear 10 are helical gears, while the second driving gear, second driven gear, and third driving gear are all spur gears. The output shaft is connected to a lead screw mechanism, which is installed inside the piston. The outer end face of the piston contacts the brake pads.

[0047] Figure 2 The diagram below shows the structure of the motor in this embodiment. The motor bearing 2 is preferably an oil-impregnated bearing, the limiting device 6 is preferably a limiting ring, and the elastic element 5 is preferably a spring.

[0048] like Figure 2As shown, two motor bearings 2 are installed on the motor shaft 4, providing support for the motor shaft 4. The motor bearings 2 are mounted on the motor body 3 and are oil-impregnated bearings. The two motor bearings 2 are located at the first and second ends of the motor shaft 4, respectively, which are opposite ends of the motor shaft 4 in the axial direction. The motor gear 9 is fixedly installed at the first end of the motor shaft 4, which is also the output shaft end of the motor shaft 4. A vibration damping mechanism and a limiting device 6 are installed on the motor shaft 4, located at the second end of the motor shaft 4. A vibration damping mechanism is installed between the limiting device 6 and the motor bearing 2 located at the second end of the motor shaft 4. Only one limiting device 6 and one vibration damping mechanism are installed. The vibration damping mechanism is an elastic element 5, which is a cylindrical helical spring and is a compression spring.

[0049] The limiting device 6 is a limiting ring, which is a circular metal ring. There is only one ring, which is fitted onto the motor shaft 4. The limiting ring can be fixedly connected to the motor shaft 4 by press-fitting, welding, or other methods. The elastic element 5 is installed between the motor bearing 2 and the limiting device 6. Gaskets 7 are installed on both sides of the elastic element 5. One gasket 7 is sandwiched between the limiting device 6 and the elastic element 5, and its end face that contacts the limiting device 6 has a pattern. The other gasket 7 is sandwiched between the motor bearing 2 and the elastic element 5, and its end face that contacts the motor bearing 2 also has a pattern. The gasket 7 is made of nylon plastic, and the pattern on its end face is involute-shaped to prevent air bubbles from forming inside when the gasket 7 contacts the motor bearing 2 or the limiting ring. The function of the gasket 7 is to reduce adverse friction and noise generated by rotation of the spring, thereby improving the service life of the spring.

[0050] The vibration damping mechanism is used to apply a preload force along the axial direction to the motor shaft 4, which suppresses the tendency of the motor gear 9 to move axially when the parking brake is unlocked; it eliminates the axial displacement variables of the motor shaft 4 and the internal components of the motor, and reduces vibration.

[0051] Example 2:

[0052] The main difference between the electromechanical brake actuator provided in this embodiment and the electromechanical brake actuator provided in Embodiment 1 lies in the structural form of the elastic element 5; the rest are the same. Figure 5 As shown, in this embodiment, the elastic element 5 is a metal wave-shaped gasket, installed between the limiting device 6 and the motor bearing 2, and gaskets 7 are installed on both sides of the elastic element 5. This case only modifies the structure of the elastic element 5 based on Embodiment 1; the remaining structure and working principle are the same as in Embodiment 1.

[0053] Example 3:

[0054] The main difference between the electromechanical brake actuator provided in this embodiment and the electromechanical brake actuator provided in Embodiment 1 lies in the installation position of the elastic element 5 and the limiting device 6.

[0055] like Figure 6 As shown, in this case, the motor gear 9 is used instead of the limiting device 6, meaning that the limiting device 6 is not set separately. A vibration damping mechanism is set between the motor gear 9 and the motor bearing 2, which is located at the first end of the motor shaft 4. One vibration damping mechanism is set. The vibration damping mechanism is an elastic element 5, which is a cylindrical helical spring and is a compression spring.

[0056] An elastic element 5 is installed between the motor gear 9 and the motor bearing 2. Shims 7 are installed on both sides of the elastic element 5; one shim 7 is sandwiched between the motor bearing 2 and the elastic element 5, and the end face of the shim 7 that contacts the motor gear 9 has a pattern. The other shim 7 is sandwiched between the motor bearing 2 and the elastic element 5, and the end face of the shim 7 that contacts the motor bearing 2 also has a pattern. The shims 7 are made of nylon plastic, and the pattern on the end face of the shim 7 is involute-shaped to prevent air bubbles from forming inside when the shim 7 contacts the motor bearing 2 or the motor gear 9. The function of the shims 7 is to reduce adverse friction and noise generated by rotation of the spring, thereby improving the service life of the spring.

[0057] Compared to Embodiment 1, this case reduces the cost of one limiting device 6. However, due to the friction between the motor gear 9 and the washer 7, the motor's output power may be slightly reduced; the rest of the structure and working principle are the same as in Embodiment 1.

[0058] Example 4:

[0059] The main difference between the electromechanical brake actuator provided in this embodiment and the electromechanical brake actuator provided in Embodiment 1 is that the damping element 8 is used instead of the elastic element 5.

[0060] like Figure 7 As shown, the vibration reduction mechanism is a damping element 8.

[0061] In this embodiment, limiting devices 6 are installed on both sides of the motor bearing 2 located at the second end of the motor shaft 4. The motor bearing 2 is preferably an oil-impregnated bearing, and the limiting device 6 is preferably a limiting ring.

[0062] A gasket 7 is installed between the motor bearing 2 and the two limiting devices 6 on both sides. A damping element 8 is placed in one of the four annular spaces between the gasket 7 and the limiting device 6, and between the gasket 7 and the motor bearing 2. The damping element 8 is preferably a high-viscosity grease. That is, the damping element 8 is positioned between the gasket 7 and the motor bearing 2, and between the gasket 7 and the limiting device 6. During operation, the combination of the gasket 7 and the grease absorbs axial impact, thereby eliminating or reducing axial displacement vibration noise of the motor shaft, thus eliminating or weakening the impact sound caused by axial impact and improving sound quality.

[0063] In summary, the electromechanical brake actuator of this invention provides an axial preload to the motor shaft by setting a limiting device 6 and an elastic element 5 and / or a damping element 8 at the end of the motor shaft, thereby reducing or eliminating the vibration of the motor shaft and its internal components. This ensures that no impact sound occurs inside the vehicle when the vehicle is unlocked, while also reducing the manufacturing and assembly costs of the product.

[0064] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution; or the direct application of the inventive concept and technical solution to other situations without modification, are all within the protection scope of the present invention.

Claims

1. An electromechanical brake actuator, comprising a motor and a transmission mechanism, wherein the motor includes a motor body and a motor shaft passing through the motor body, characterized in that: Two motor bearings are provided on the motor shaft, and vibration damping mechanisms are provided on both sides of the motor bearings to reduce the vibration of the motor shaft. The vibration damping mechanisms are elastic elements, which are cylindrical helical springs and are compression springs. The vibration damping mechanism is used to apply a preload force along the axial direction to the motor shaft, suppressing the tendency of the motor gear to move axially when the parking brake is unlocked, and eliminating the axial displacement variables of the motor shaft and internal components. Two motor bearings provide support for the motor shaft. The motor bearings are mounted on the motor body and are oil-impregnated bearings. The two motor bearings are located at the first and second ends of the motor shaft, respectively. The first and second ends of the motor shaft are opposite ends in the axial direction of the motor shaft. The motor gear is fixedly mounted at the first end of the motor shaft, that is, the output shaft end of the motor shaft, and the motor gear is connected to the transmission mechanism. A vibration damping mechanism is provided between the motor gear and the motor bearing located at the first end of the motor shaft; Gaskets are installed on both sides of the elastic element. One gasket is sandwiched between the motor gear and the elastic element. The end face of the gasket that is in contact with the motor gear is patterned. The other gasket is sandwiched between the motor bearing and the elastic element. The end face of the gasket that is in contact with the motor bearing is patterned.

2. The electromechanical brake actuator according to claim 1, characterized in that: The motor gear is a worm gear or a helical gear.

3. The electromechanical brake actuator according to claim 1, characterized in that: The transmission mechanism includes a two-stage fixed-axis gear mechanism and a one-stage planetary gear mechanism connected in sequence. The two-stage fixed-axis gear mechanism includes a first double gear and a second double gear that mesh with each other. The first double gear is a spur gear, a helical gear, or a combination of spur gears and helical gears. The second double gear is a spur gear, a helical gear, or a combination of spur gears and helical gears.

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