Lead screw transmission, electromechanical brake system and vehicle

Abstract

This utility model discloses a lead screw transmission device, comprising: a lead screw, including a helical portion, a joint portion, and a transmission portion, wherein the helical portion and the transmission portion extend along a first direction, the joint portion connects the helical portion and the transmission portion, and the joint portion has a first abutting portion; a planar thrust bearing for supporting the joint portion; and a nut, which is movably sleeved on the outside of the helical portion in a first direction and is used for movement relative to the helical portion in the first direction, wherein the nut has a first washer inside, the first washer is arranged around the joint portion, and the first washer includes a second abutting portion; the first abutting portion and the second abutting portion abut against each other in the first direction, and the first abutting portion and the second abutting portion are in line contact. This utility model can reduce the wear of the lead screw transmission device, improve its service life and transmission efficiency, while reducing the heat generated by friction and slowing down grease aging. This utility model also provides an electromechanical braking system and a vehicle.

Description

Technical Field

[0001] This utility model relates to the field of brake technology, and in particular to a screw drive device, an electromechanical braking system, and a vehicle. Background Technology

[0002] The automotive braking system is used to decelerate and stop a vehicle, and is a core system ensuring vehicle safety. It mainly includes hydraulic braking systems and electromechanical braking systems (EMB). With the development of automotive braking technology, electromechanical braking systems are demonstrating unique advantages due to their higher response speed and more precise control capabilities.

[0003] In electromechanical braking systems, the brake is a crucial component that directly generates braking torque to bring the vehicle to a stop. Taking a disc brake as an example, it mainly consists of a caliper. The caliper is the actuator that directly applies braking force, and it integrates friction pads inside to press the friction pads tightly against the brake disc, thereby achieving braking. In this process, a ball screw is often placed between the motor and the caliper to convert the rotational motion of the motor into linear motion, which then pushes the friction pads.

[0004] After a ball screw is introduced into a caliper, axial forces are typically balanced and distributed using shims. For example, a front shim is required between the ball screw shaft and the caliper, and this front shim is positioned around the joint of the ball screw shaft and makes contact with the joint surface of the ball screw shaft.

[0005] During braking, the caliper housing deforms under stress, causing the ball screw and front washer to tilt within the caliper housing. Since the screw shaft and the front washer are in surface-to-surface contact, their relative compression prevents angle adjustment, easily leading to uneven stress on the thrust bearing connected to the screw shaft. This results in more severe wear on the thrust bearing, shortening its service life and reducing transmission efficiency. Simultaneously, it generates higher frictional temperatures, accelerating grease aging. Furthermore, during braking, the screw shaft and the front washer rotate relative to each other in a circumferential direction, further increasing wear and frictional heat between them. Utility Model Content

[0006] The purpose of this invention is to solve the technical problem that the fit between the lead screw and the washer in existing lead screw drive devices easily leads to uneven bearing stress and high temperature. This invention provides a lead screw drive device, an electromechanical braking system, and a vehicle, which can improve the service life and transmission efficiency of the lead screw drive device with lower design and production costs, and reduce the heat generated by friction, thereby slowing down grease aging.

[0007] To solve the above-mentioned technical problems, the present invention discloses a lead screw transmission device, comprising:

[0008] A lead screw includes a helical portion, a joint portion, and a transmission portion, wherein the helical portion and the transmission portion extend along a first direction, the joint portion connects the helical portion and the transmission portion, and the joint portion has a first abutting portion;

[0009] A planar thrust bearing is used to support the joint portion;

[0010] A nut is fitted onto the outside of the helical portion in a manner movable along the first direction and is used to move relative to the helical portion along the first direction. The nut has a first washer inside, which is arranged around the joint portion. The first washer includes a second abutment portion.

[0011] The first abutting portion and the second abutting portion abut against each other along the first direction, and the first abutting portion and the second abutting portion are in line contact.

[0012] In traditional lead screw drives, the lead screw shaft and washer typically have a plane-to-plane contact. When the caliper housing deforms under stress, it squeezes the lead screw shaft and washer inside the housing, causing them to tilt. Because the two planes of the lead screw shaft and washer are in contact with each other, they maintain a relatively fixed contact angle (which can be understood as the two planes being forcibly aligned). That is, they cannot adjust the contact angle, which leads to uneven stress. On the one hand, this uneven stress causes abnormal wear on the thrust bearing, affecting its service life and the transmission efficiency of the lead screw drive. On the other hand, it generates a large amount of frictional heat. Furthermore, the generated frictional heat acts on the grease on the thrust bearing, washer, lead screw shaft, or other components, thus accelerating grease aging.

[0013] Using the above technical solution, in this embodiment of the application, the joint portion of the lead screw and the first washer surrounding the joint portion are configured in a line contact abutment form. That is, the first abutment portion of the joint portion and the second abutment portion of the first washer are not in a plane-to-plane abutment. In other words, it can be understood that there is a set of ball joints between the first abutment portion and the second abutment portion. Then, when the lead screw and the first washer are subjected to the pressure of the caliper housing deformation, one of the abutment portions can deflect at the tangential point relative to the other abutment portion. That is, the angle can be finely adjusted as the caliper housing deforms and squeezes, so as to ensure a uniform pressure distribution between the first abutment portion and the second abutment portion. This ensures that the planar thrust bearing is subjected to uniform force, effectively improving the service life and transmission efficiency of the planar thrust bearing and the lead screw transmission device. At the same time, it can also effectively reduce abnormal wear and frictional heat generation of the planar thrust bearing and slow down grease aging.

[0014] According to another specific embodiment of the present invention, one of the first abutting part and the second abutting part is a convex surface and the other is a concave surface.

[0015] According to another specific embodiment of the present invention, the convex surface is a convex spherical surface, and the concave surface is a concave spherical surface.

[0016] According to another specific embodiment of the present invention, one of the first abutting part and the second abutting part is a conical surface and the other is a convex surface.

[0017] According to another specific embodiment of the present invention, the convex surface is a convex spherical surface.

[0018] According to another specific embodiment of the present invention, the joint portion is provided with a protrusion, and the first washer is provided with a groove; in the operating state of the lead screw transmission device, the protrusion is used to drive the groove so that the first washer rotates synchronously with the joint portion.

[0019] Using the above technical solution, in traditional lead screw transmission devices, relative rotation usually occurs between the lead screw shaft and the washer, which easily leads to wear and heat generation. In the embodiments of this application, the lead screw and the first washer are designed to have a structure that does not produce large relative rotation. That is, a protrusion is provided on the joint of the lead screw, and a corresponding groove is provided on the first washer. When braking is required (i.e., when the lead screw transmission device is in operation), the lead screw rotates (for example, driven by an external motor) so that the protrusion can drive the groove of the first washer. Thus, when the lead screw transmission device is running, the joint and the first washer can rotate synchronously without large relative rotation, thereby effectively reducing wear and heat generation between the joint and the first washer.

[0020] According to another specific embodiment of the present invention, the lead screw transmission device further includes:

[0021] The second washer, used to abut against the external caliper, is spaced apart from the first washer along the first direction.

[0022] This utility model also discloses an electromechanical braking system, comprising:

[0023] Calipers;

[0024] As described in any of the above embodiments, in the first direction, the nut of the screw drive device is used to drive the caliper.

[0025] The present invention also discloses a vehicle including an electromechanical braking system as described in any of the above embodiments. Attached Figure Description

[0026] Figure 1 A partial cross-sectional view of a vehicle according to an embodiment of the present invention is shown; wherein, the electromechanical braking system and the lead screw drive device are shown in the figure.

[0027] Figure 2 A perspective view of the lead screw transmission device according to an embodiment of the present invention is shown.

[0028] Figure 3 This diagram shows a partial enlargement of the lead screw transmission device according to an embodiment of the present invention. Figure 1 .

[0029] Figure 4 This diagram shows a partial enlargement of the lead screw transmission device according to an embodiment of the present invention. Figure 2 .

[0030] Figure 5 This diagram shows a partial enlargement of the lead screw transmission device according to an embodiment of the present invention. Figure 3 .

[0031] Figure 6 This diagram shows a partial enlargement of the lead screw transmission device according to an embodiment of the present invention. Figure 4 .

[0032] Figure 7 This is a perspective view of the first washer in the lead screw transmission device according to an embodiment of the present invention.

[0033] Figure 8 A cross-sectional view of the lead screw transmission device according to an embodiment of the present invention is shown. Figure 1 .

[0034] Figure 9 A cross-sectional view of the lead screw transmission device according to an embodiment of the present invention is shown. Figure 2 . Detailed Implementation

[0035] The following specific embodiments illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. Although the description of this utility model will be presented in conjunction with preferred embodiments, this does not mean that the features of this utility model are limited to this embodiment. On the contrary, the purpose of describing the utility model in conjunction with the embodiments is to cover other options or modifications that may be derived based on the claims of this utility model. To provide a deep understanding of this utility model, many specific details will be included in the following description. This utility model may also be implemented without using these details. Furthermore, to avoid confusion or obscuring the focus of this utility model, some specific details will be omitted in the description. It should be noted that, without conflict, the embodiments and features in the embodiments of this utility model can be combined with each other.

[0036] It should be noted that in this specification, similar reference numerals and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0037] In the description of this embodiment, it should be noted that the terms "upper", "lower", "inner", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship that the utility model product is usually placed in during use. They are only for the convenience of describing the utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the utility model.

[0038] The terms “first”, “second”, etc., are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0039] In the description of this embodiment, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set up," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this embodiment based on the specific circumstances.

[0040] To make the objectives, technical solutions, and advantages of this utility model clearer, the embodiments of this utility model will be described in further detail below with reference to the accompanying drawings.

[0041] refer to Figure 1 , Figure 1 A cross-sectional view of a vehicle according to an embodiment of this application is shown as an example.

[0042] like Figure 1 As shown in the embodiment of this application, a vehicle 100 is disclosed. The braking system of the vehicle 100 adopts an electromechanical braking system 200, which has a high response speed and braking accuracy, making the braking force output of the vehicle 100 more direct and linear.

[0043] In this embodiment, the electromechanical braking system 200 of the vehicle 100 adopts a screw drive device 300 with better structural design performance. By changing the contact mode of the parts in the screw drive device 300 at low cost, the wear and high heat of the parts during the operation of the traditional screw drive device are effectively reduced, and the aging of the grease is slowed down. At the same time, the service life of the planar thrust bearing is guaranteed, and the braking efficiency of the electromechanical braking system 200 is improved.

[0044] refer to Figure 1 and Figure 2 , Figure 2 An exemplary perspective view of the lead screw drive 300 is shown.

[0045] Specifically, the electromechanical braking system 200 of this application embodiment includes: the aforementioned lead screw drive device 300 and caliper 400.

[0046] like Figure 1 As shown, the caliper 400 includes a housing 410 and a caliper claw 420 disposed inside the housing 410.

[0047] As can be seen, at least a portion of the lead screw drive 300 is disposed inside the housing 410, and along the first direction (e.g. Figure 1 (shown in the Z direction), the lead screw drive 300 can drive one end of the caliper jaw 420 (i.e., in the Z direction). Figure 1 (The end pointed to in the Z1 direction).

[0048] The caliper claw portion 420 has a piston, friction pads and a brake disc inside. Although not shown in the figure, those skilled in the art will understand that the friction pads are located on both sides of the brake disc. The lead screw drive 300 can generate linear motion in a first direction, thereby pushing the piston inside the caliper claw portion 420 so that the piston pushes the friction pads and presses the friction pads against the brake disc, thereby achieving vehicle deceleration or stopping.

[0049] refer to Figure 1 and Figure 2 In this embodiment of the application, the lead screw drive device 300 includes: a lead screw 310 (e.g., a ball screw), a nut 320 (e.g., a ball nut), and a planar thrust bearing 350.

[0050] As can be seen, the lead screw 310 includes a helical portion 311 (not clearly shown in the figure, but it can be understood that the helical portion 311 is located inside the nut 320), a joint portion 312, and a transmission portion 313. The helical portion 311 and the transmission portion 313 are respectively along a first direction (e.g., Figure 1 and Figure 2 It extends in the Z direction shown in the figure, and the joint portion 312 is connected between the helical portion 311 and the transmission portion 313.

[0051] Nut 320 is positioned along the first direction (e.g.) Figure 1 and Figure 2 The nut 320 is movably sleeved on the outside of the spiral portion 311 in the Z direction shown in the figure, and can move relative to the spiral portion 311 in the first direction. The nut 320 has a first washer 330 inside, which surrounds the joint portion 312 and can restrict the movement of the joint portion 312 in the first direction.

[0052] The planar thrust bearing 350 is located between the first washer 330 and the second washer 340 described later, and the planar thrust bearing 350 is connected to the transmission part 313 mentioned above, that is, the planar thrust bearing 350 can support the joint part 312.

[0053] refer to Figures 3 to 6 The first gasket 330 includes a second abutting portion 331, and the joint portion 312 includes a first abutting portion 3121. The second abutting portion 331 and the first abutting portion 3121 abut against each other in a first direction, and the second abutting portion 331 and / or the first abutting portion 3121 are in line contact.

[0054] In traditional lead screw drives, the lead screw shaft and the washer typically have a plane-to-plane contact. When the housing 410 of the caliper 400 is deformed under stress (e.g. Figure 1 As shown, this will squeeze the lead screw shaft and shims inside the housing 410, causing the lead screw shaft and shims to tilt. Since the two planes of the lead screw shaft and shims abut against each other, they will maintain a relatively fixed abutting angle (which can be understood as the two planes being forcibly aligned). That is, the two cannot adjust the abutting angle, which will cause uneven force. On the one hand, it will cause abnormal wear of the planar thrust bearing 350 due to uneven force, affecting the service life of the planar thrust bearing 350 and the transmission efficiency of the lead screw transmission device 300. On the other hand, it will generate a lot of frictional heat. Furthermore, the generated frictional heat will act on the grease on the planar thrust bearing 350, shims, lead screw shaft or other components, thereby accelerating the aging of the grease.

[0055] refer to Figure 1 and Figure 2 Using the above technical solution, in this embodiment of the application, the joint portion 312 in the lead screw 310 and the first washer 330 surrounding the joint portion 312 are configured to be in line contact abutment. That is to say, the first abutment portion 3121 of the joint portion 312 and the second abutment portion 331 of the first washer 330 are not in plane-to-plane abutment. In other words, it can be understood that there is a set of ball joints between the first abutment portion 3121 and the second abutment portion 331. Therefore, when the lead screw 310 and the first washer 330 are subjected to the deformation of the caliper 400 housing 410, one of the abutting parts can deflect at the tangential point relative to the other abutting part. That is, the angle can be finely adjusted as the caliper 400 housing 410 deforms and squeezes, so as to ensure a uniform pressure distribution between the first abutting part 3121 and the second abutting part 331. This ensures that the planar thrust bearing 350 is subjected to uniform force, effectively improving the service life and transmission efficiency of the planar thrust bearing 350 and the lead screw transmission device 300. At the same time, it can also effectively reduce abnormal wear and frictional heat generation of the planar thrust bearing 350 and slow down grease aging.

[0056] refer to Figure 3In some possible implementations, the second abutment portion 331 of the first gasket 330 can be seen to be concave (e.g., Figure 3 The concave spherical surface shown), the first abutting part 3121 of the joint 312 in the lead screw 310 is a convex surface (e.g., a concave spherical surface). Figure 3 (as shown by the convex spherical surface), at the same time, the second abutting part 331 and the first abutting part 3121 are tangent.

[0057] refer to Figure 4 In some possible implementations, the second abutment portion 331 of the first gasket 330 can be seen to be convex (e.g., Figure 4 The first abutment portion 3121 of the joint portion 312 in the lead screw 310 is concave (e.g., a convex spherical surface). Figure 4 (as shown in the concave spherical surface), at the same time, the second abutting part 331 and the first abutting part 3121 are tangent.

[0058] refer to Figure 5 In some possible implementations, the second abutment portion 331 of the first gasket 330 can be seen to be convex (e.g., Figure 5 The convex spherical surface shown is different from the above embodiment in that the first abutting part 3121 of the joint part 312 in the lead screw 310 is a conical surface. In this case, the second abutting part 331 and the first abutting part 3121 are tangent.

[0059] refer to Figure 6 In some possible implementations, the second abutting portion 331 of the first gasket 330 can be seen to be a conical surface, and the first abutting portion 3121 can be a convex surface (e.g., Figure 6 (The convex spherical surface shown).

[0060] Further integration Figure 1 and Figure 2 The above embodiment can be understood as follows: a set of ball joints (first abutment portion 3121 and second abutment portion 331) is provided between the joint portion 312 and the first washer 330. When the lead screw transmission device 300 is running, the lead screw 310 and the nut 320 can convert the rotational motion of the motor (not shown in the figure) into linear motion, and push the piston in the caliper claw portion 420 to push the friction plate in the caliper claw portion 420 to the brake disc. During this process, the housing 410 of the caliper 400 is deformed by force, but since the first abutment portion 3121 and the second abutment portion 331 in this embodiment can be angled to adjust with the deformation of the caliper 400 (that is, the tangent point of the first abutment portion 3121 and the second abutment portion 331 moves with the deformation of the caliper 400), wear and frictional heat are reduced.

[0061] refer to Figure 1In some possible implementations, the lead screw drive device 300 of this application embodiment further includes a second shim 340. The second shim 340 is disposed inside the housing 410 of the caliper 400 and supported by the bottom wall of the housing 410. It can be seen that the second shim 340 is spaced apart from the first shim 330.

[0062] refer to Figures 7 to 9 In this embodiment, a structural design is also provided to prevent the lead screw 310 and the first washer 330 from rotating relative to each other in the circumferential direction. That is, on the basis of the line contact between the lead screw 310 and the first washer 330 to protect the planar thrust bearing, the relative rotation between the lead screw 310 and the first washer 330 is further restricted, thereby further reducing the wear and heat generation between the lead screw 310 and the first washer 330.

[0063] Specifically, refer to Figure 2 and Figure 7 In some possible implementations, the first gasket 330 is provided with a groove 332 (e.g., Figure 7 and Figure 9 As shown), the joint portion 312 is provided with a protrusion 3122 (as shown). Figure 2 and Figure 8 (As shown).

[0064] In the operating state of the lead screw drive 300 (e.g.) Figure 4 As shown, the protrusion 3122 is accommodated in the groove 332, and the protrusion 3122 can drive the groove 332 so that the first pad 330 rotates synchronously with the joint 312.

[0065] Using the above technical solution, in a traditional lead screw drive 300, relative rotation usually occurs between the lead screw shaft and the washer, which easily leads to wear and heat generation. In this embodiment, the lead screw 310 and the first washer 330 are designed to avoid large relative rotation. That is, a protrusion 3122 is provided on the joint 312 of the lead screw 310, and a corresponding groove 332 is provided on the first washer 330. When braking is required (i.e., when the lead screw drive 300 is in operation), the lead screw 310 rotates (e.g., driven by an external motor) so that the protrusion 3122 can drive the groove 332 of the first washer 330. Then, when the lead screw drive 300 is running, the joint 312 and the first washer 330 can rotate synchronously without large relative rotation, thereby effectively reducing wear and heat generation between the joint 312 and the first washer 330.

[0066] Although the present invention has been illustrated and described with reference to certain preferred embodiments, those skilled in the art should understand that the above description is a further detailed explanation of the present invention in conjunction with specific embodiments, and should not be construed as limiting the specific implementation of the present invention to these descriptions. Those skilled in the art can make various changes in form and detail, including some simple deductions or substitutions, without departing from the spirit and scope of the present invention.

Claims

1. A lead screw transmission device, characterized in that, include: A lead screw includes a helical portion, a joint portion, and a transmission portion, wherein the helical portion and the transmission portion extend along a first direction, the joint portion connects the helical portion and the transmission portion, and the joint portion has a first abutting portion; A planar thrust bearing is used to support the joint portion; A nut is fitted onto the outside of the helical portion in a manner movable along the first direction and is used to move relative to the helical portion along the first direction. The nut has a first washer inside, which is arranged around the joint portion. The first washer includes a second abutment portion. The first abutting portion and the second abutting portion abut against each other along the first direction, and the first abutting portion and the second abutting portion are in line contact.

2. The lead screw transmission device according to claim 1, characterized in that, One of the first abutting part and the second abutting part is a convex surface, and the other is a concave surface.

3. The lead screw transmission device according to claim 2, characterized in that, The convex surface is a convex spherical surface, and the concave surface is a concave spherical surface.

4. The lead screw transmission device according to claim 1, characterized in that, One of the first abutting part and the second abutting part is a conical surface, and the other is a convex surface.

5. The lead screw transmission device according to claim 4, characterized in that, The convex surface is a convex spherical surface.

6. The lead screw drive device according to any one of claims 1 to 5, characterized in that, The joint is provided with a protrusion, and the first washer is provided with a groove; in the operating state of the lead screw transmission device, the protrusion is used to drive the groove so that the first washer rotates synchronously with the joint.

7. The lead screw transmission device according to claim 6, characterized in that, The lead screw drive device also includes: The second washer, used to abut against the external caliper, is spaced apart from the first washer along the first direction.

8. The lead screw transmission device according to claim 1, characterized in that, The lead screw is a ball screw, and the nut is a ball nut.

9. An electromechanical braking system, characterized in that, include: Calipers; According to any one of claims 1 to 8, in the first direction, the nut of the screw drive is used to drive the caliper.

10. A vehicle, characterized in that, Including the electromechanical braking system as described in claim 9.

Images