An electronic parking brake

Abstract

The present application relates to a parking brake, in particular to an electronic parking brake, comprising a driving motor, a brake disc, an inner brake pad and an outer brake pad cooperating with the brake disc, and an inner back plate and an outer back plate being hingedly connected together in a middle part, the inner brake pad and the outer brake pad being respectively fixedly arranged at the inner side of the lower end of the inner back plate and the outer back plate; the upper end of the inner back plate is fixedly arranged with a first nut, the output shaft of the driving motor is directly or indirectly fixedly connected with a first screw rod, the first screw rod is screwed with the first nut and is axially fixed with the upper end of the outer back plate and is circumferentially free. Compared with the prior art, the present application can not only be self-locked at the position after the motor stops, but also can amplify the driving motor torque, and can achieve the same function in a simpler way, and has simple structure and low cost.

Description

TECHNICAL FIELD

[0001] The present application relates to a parking brake, in particular to an electronic parking brake. BACKGROUND

[0002] Electronic parking brake (EPB) is a widely used brake safety device on vehicles. In addition to replacing the traditional pull-lock type hand brake device, it also has the ability to sense wheel slip, so it can actively increase brake braking force in the parking state to ensure vehicle parking safety.

[0003] The known electronic parking brake involves a unit that transmits braking force, which is a motor reducer (MGU) composed of a set of reduction gears and a driving motor. When receiving a brake signal from the vehicle control unit or the vehicle computer (ECU), the motor will drive the gear set and push the brake pad to compress the brake disc to achieve the parking brake function. For example, the electronic parking brake, transmission and vehicle disclosed in publication No. CN208348350U includes a caliper, a first friction plate, a second friction plate and a brake disc, a guide screw, and an intermediate piece threadedly connected with the guide screw. When the guide screw rotates, it can drive the intermediate piece to move axially to make the first friction plate approach or move away from the brake disc; an electric drive device drives the guide screw to rotate. The uniqueness of this patent is that the manual drive device action can drive the intermediate piece to move away from the brake disc. However, the manual drive device action can drive the intermediate piece to move away from the brake disc, which means that the gear set and screw of the transmission component are reversed under the action of a small torque. Therefore, the transmission component cannot be self-locked after the motor stops, that is, the electronic parking brake cannot maintain the current braking force when no power (electricity) is provided to the motor after the vehicle is braked. SUMMARY

[0004] To overcome the defects or one of the defects of the prior art, the present application provides a new type of electronic parking brake, and the technical scheme adopted is:

[0005] An electronic parking brake, comprising a driving motor, a brake disc, an inner brake pad and an outer brake pad matched with the brake disc, and an inner back plate and an outer back plate sheared together in the middle part, wherein the inner brake pad and the outer brake pad are respectively fixedly arranged at the inner side of the lower end of the inner back plate and the outer back plate; a first nut is fixedly arranged at the upper end of the inner back plate, the output shaft of the driving motor is directly or indirectly fixedly connected with a first screw rod, the first screw rod is screw-connected with the first nut and axially fixed with the upper end of the outer back plate and circumferentially free.

[0006] Further, the distance from the axis of the first screw rod to the hinge shaft is greater than the distance from the hinge shaft to the centers of the inner brake pad and the outer brake pad.

[0007] Further, the thread angle of the first screw rod and the first nut is less than 5°.

[0008] Further, the upper end of the outer back plate is fixed with a bearing, the first screw rod is a stepped rod, the small diameter section of the first screw rod penetrates into the inner ring of the bearing, the rod shoulder of the first screw rod abuts the inner end of the inner ring of the bearing, and the output shaft of the driving motor directly or indirectly abuts the outer end of the inner ring of the bearing to realize the axial fixing and the circumferential freedom of the first screw rod and the upper end of the outer back plate.

[0009] Further, the upper end of the inner back plate is further fixed with a second nut, the second nut is screwed with a second screw rod, the second screw rod is axially fixed and circumferentially free with the upper end of the outer back plate, a driving gear is fixed on the first screw rod, a driven gear is fixed on the second screw rod, and the driving gear and the driven gear are engaged.

[0010] Further, the thread angle of the second screw rod and the second nut is less than 5°.

[0011] Further, the screw direction of the second screw rod and the second nut is opposite to the screw direction of the first screw rod and the first nut.

[0012] Further, the upper end of the outer back plate is fixed with two bearings, the first screw rod and the second screw rod are stepped rods, the small diameter sections of the first screw rod and the second screw rod respectively penetrate into the inner rings of the two bearings, the rod shoulders of the first screw rod and the second screw rod abut the inner ends of the inner rings of the bearings, and the inner end faces of the driving gear and the driven gear abut the bearings and / or the outer back plate to realize the axial fixing and the circumferential freedom of the first screw rod and the second screw rod and the upper end of the outer back plate.

[0013] Compared with the prior art, the application can not only be self-locked at the position after the motor stops, but also can amplify the driving motor torque in a relatively simple way to achieve the same function, and has a simple structure and low cost. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 is a structural schematic diagram of the application.

[0015] Figure 2 is a longitudinal sectional schematic diagram of Figure 1 . DETAILED DESCRIPTION

[0016] The application will be further described in the specific embodiment mode with reference to the drawings.

[0017] Example 1, refer to Figure 1 and Figure 2A single screw rod shear type electronic parking brake, like the existing electronic parking brake, comprises a driving motor 1, a brake disc 7, an inner brake pad 61 and an outer brake pad 62 matched with the brake disc 7, and further comprises an inner back plate 51 and an outer back plate 52 hingedly connected together in a middle shear type, and the inner brake pad 61 and the outer brake pad 62 are respectively fixedly arranged at the inner side of the lower end of the inner back plate 51 and the outer back plate 52; a first nut 41 is fixedly arranged at the upper end of the inner back plate 51, an output shaft of the driving motor 1 is directly or indirectly connected with a first screw rod 31, the first screw rod 31 is screwed with the first nut 41; a bearing 8 is fixedly arranged at the upper end of the outer back plate 52, the first screw rod 31 is a stepped rod, a small diameter section of the first screw rod 31 penetrates into the inner ring of the bearing 8, a rod shoulder of the first screw rod 31 abuts against the inner end of the inner ring of the bearing 8, the outer diameter of the output shaft of the driving motor 1 is larger than the diameter of the small diameter section and abuts against the outer end of the inner ring of the bearing 8, so that the upper end of the outer back plate 52 is fixed in the axial direction and free in the circumferential direction with the first screw rod 31. That is, the first screw rod 31 cannot axially move but can circumferentially rotate.

[0018] In the embodiment, the thread angle of the first screw rod 31 and the first nut 41 is 4°, which is the thread angle at which the screw rod and nut can be self-locked. The distance L1 from the axis of the first screw rod 31 to the hinge shaft is greater than the distance L2 from the hinge shaft to the centers of the inner brake pad 61 and the outer brake pad 62.

[0019] When the driving motor 1 rotates, it directly drives the first screw rod 31 to rotate, and under the cooperation of the first nut 41 on the inner back plate 51, the inner back plate 51 is pulled to approach the outer back plate 52, thereby generating the action of increasing the brake clamping force, or the inner back plate 51 is pushed to move away from the outer back plate 52, thereby generating the action of releasing the brake clamping force.

[0020] The reducer structure of the embodiment amplifies the torque output of the driving motor through the screw rod and nut structure and forms the self-locking characteristic under less than 5°, thereby achieving the functional requirement of the electronic parking brake. Compared with the reduction ratio of the traditional gear set, under the same reduction ratio condition, there is a lower cost advantage. The main reasons are as follows: first, the embodiment adopts a screw rod driving design, and the axial force can be easily amplified several times through the thread angle of the screw rod and nut, as shown in FIG. 1; second, the output force F1 and the brake clamping force F2 have a lever torque relationship, that is, F1*L1=F2*L2, when L1>L2, then the brake clamping force F2=(L1 / L2)*(screw rod and nut reduction ratio)*F1. Figure 2

[0021] Compared with the reducer design adopting the gear set, the embodiment has fewer parts and lower assembly cost, and does not affect the reliability.

[0022] ​Compared with the reducer design using gear set, the output ratio can be adjusted in a simple way. In addition to adjusting the tooth profile of the screw nut set, the power arm and the resistance arm can also adjust the output ratio. This design can quickly introduce new models and shorten the design and development time.

[0023] Embodiment 2, as shown in Figure 1 and Figure 2 A double-screw rod scissors-type electronic parking brake is different from the embodiment. The first nut 41 is fixedly arranged at the rear upper end of the inner back plate 51, and the second nut 42 is also fixedly arranged at the front upper end of the inner back plate 51. The second nut 42 is screwed with the second screw rod 32. The first screw rod 31 is fixedly connected with the driving gear 21, and the second screw rod 32 is fixedly connected with the driven gear 22. The driving gear 21 and the driven gear 22 are engaged. Two bearings 8 are fixedly arranged at the upper end of the outer back plate 52. The first screw rod 31 and the second screw rod 32 are stepped rods. The small-diameter sections of the first screw rod 31 and the second screw rod 32 respectively pass through the inner rings of the two bearings 8. The rod shoulders of the first screw rod 31 and the second screw rod 32 abut the inner end of the inner ring of the bearing 8. The inner end faces of the driving gear 21 and the driven gear 22 abut the bearing 8 and the outer back plate 52. In this way, the first screw rod 31 and the second screw rod 32 are axially fixed with the upper end of the outer back plate 52 and are circumferentially free. The thread angles of the second screw rod 32 and the second nut 42 are both 4°.

[0024] Of course, the screw direction of the second screw rod 32 and the second nut 42 must be opposite to the screw direction of the first screw rod 31 and the first nut 41.

[0025] When the driving motor 1 rotates, it will directly drive the driving gear 21 and then drive the driven gear 22 engaged therewith. The two gears will rotate in opposite directions. Since the two gears are fixedly connected with the screw rods to form an integral body, the first screw rod 31 and the second screw rod 32 will synchronously rotate in opposite directions. Through the two nuts fixedly connected with the inner brake pad back plate 51, the two screw rods will simultaneously pull the inner back plate 51 to make it close to the outer back plate 52, thereby generating the action of increasing the brake clamping force. Or the two screw rods will simultaneously push the inner back plate 51 away from the outer back plate 52, thereby generating the action of releasing the brake clamping force.

[0026] In addition to using the self-locking characteristics of the screw nut at less than 5°, the double-screw nut set structure is adopted to ensure the stability of the static heavy load. The double-screw nut set structure can also have a more stable self-locking state in static state. A pair of gear sets are used to form opposite rotation directions. In this way, the self-locking ability is strengthened, and the sliding caused by the weakening of the brake friction caused by environmental factors or vibration factors is effectively resisted.

[0027] The above-mentioned embodiment simplifies the design of the conventional reduction gear set, and the designed structure is simple and reliable, and can withstand external harsh environment, such as sudden temperature change and dust pollution, and the design of the patent has better performance.

[0028] Although the present application has been described in detail with general description and specific embodiments above, some modifications or improvements can be made on the basis of the present application, which is obvious to those skilled in the art. Therefore, these modifications or improvements made on the basis of not deviating from the spirit of the present application, all belong to the scope of the present application.

[0029] The part not described in detail of the present application is the prior art or common knowledge in the art.

Claims

1. An electronic parking brake comprising a drive motor (1), a brake disc (7), an inner brake pad (61) and an outer brake pad (62) cooperating with the brake disc (7), characterized in that The inner back plate (51) and the outer back plate (52) are sheared and hinged together in the middle part, the inner brake pad (61) and the outer brake pad (62) are fixedly arranged at the inner side of the lower end of the inner back plate (51) and the outer back plate (52) respectively, the upper end of the inner back plate (51) is fixedly arranged with the first nut (41), the output shaft of the driving motor (1) is directly or indirectly fixedly connected with the first screw rod (31), the first screw rod (31) is screwed with the first nut (41) and is axially fixed and circumferentially free with the upper end of the outer back plate (52), the upper end of the inner back plate (51) is further fixedly arranged with the second nut (42), the second nut (42) is screwed with the second screw rod (32), the second screw rod (32) is axially fixed and circumferentially free with the upper end of the outer back plate (52), the first screw rod (31) is fixedly arranged with the driving gear (21), the second screw rod (32) is fixedly arranged with the driven gear (22), and the driving gear (21) and the driven gear (22) are engaged.

2. An electronic parking brake according to claim 1, characterized in that The distance (L1) from the axis of the first screw rod (31) to the hinge shaft is greater than the distance (L2) from the hinge shaft to the centers of the inner brake pad (61) and the outer brake pad (62).

3. An electronic parking brake according to claim 1, characterized in that The thread angle of the first screw rod (31) and the first nut (41) is less than 5°.

4. An electronic parking brake according to claim 1, characterized in that The upper end of the outer back plate (52) is fixedly arranged with the bearing (8), the first screw rod (31) is a stepped rod, the small-diameter section of the first screw rod (31) penetrates into the inner ring of the bearing (8), the rod shoulder of the first screw rod (31) abuts against the inner end of the inner ring of the bearing (8), and the output shaft of the driving motor (1) directly or indirectly abuts against the outer end of the inner ring of the bearing (8) to realize the axial fixing and circumferential freedom of the upper end of the outer back plate (52) with the first screw rod (31).

5. An electronic parking brake according to claim 1, wherein, The thread angle of the second screw rod (32) and the second nut (42) is less than 5°.

6. An electronic parking brake according to claim 1, characterized in that The screw direction of the second screw rod (32) and the second nut (42) is opposite to that of the first screw rod (31) and the first nut (41).

7. An electronic parking brake according to claim 1, wherein, The upper end of the outer back plate (52) is fixedly arranged with two bearings (8), the first screw rod (31) and the second screw rod (32) are stepped rods, the small-diameter sections of the first screw rod (31) and the second screw rod (32) respectively penetrate into the inner rings of the two bearings (8), the rod shoulders of the first screw rod (31) and the second screw rod (32) abut against the inner ends of the inner rings of the bearings (8), and the inner end faces of the driving gear (21) and the driven gear (22) abut against the bearings (8) and / or the outer back plate (52) to realize the axial fixing and circumferential freedom of the upper end of the outer back plate (52) with the first screw rod (31) and the second screw rod (32).

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