Piston return structure and brake caliper assembly

Abstract

The application belongs to the technical field of vehicle brake system, and particularly relates to a piston return structure applied to piston return of a brake caliper assembly. The piston return structure comprises a screw rod, a screw sleeve and an elastic assembly. The first end of the screw rod is provided with external threads. The screw sleeve is provided with internal threads, and the screw sleeve is threadedly matched with the screw rod. The screw sleeve is located in the piston and axially slidably matched with the piston. The elastic assembly is located in the piston and connected with the screw sleeve and the piston respectively, and is configured to give the piston a force towards the second end of the screw rod. The piston return structure provided by the application is equipped with the elastic assembly between the piston and the screw sleeve. When the parking brake is released, the screw sleeve is retracted to a parking brake release position, and the piston is also returned under the action of the elastic assembly. The return amount of the piston is much larger than that provided by the rectangular rubber ring, and the problem of insufficient piston return amount in the existing vehicle brake system is solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of vehicle braking system, and particularly relates to a piston return structure, an electronic parking brake caliper assembly and a parking and braking integrated caliper assembly. BACKGROUND

[0002] The drag of a vehicle braking system is caused by the fact that the vehicle is running in a state where the friction plate and the brake disc are not completely separated (residual clamping). The main hazards of the drag are: first, the waste of kinetic energy; second, the excessive wear of the friction plate and the brake disc, which reduces the service life of the parts; and third, the long-term drag overheating leads to the attenuation of the braking performance. Increasing the return amount of the piston is one of the effective ways to solve the drag. At present, the return of the piston of the brake caliper assembly is generally achieved by using the deformation restoring force of a rectangular rubber ring. The return force and the return amount provided by the rectangular rubber ring for the piston are very limited, so the drag problem is difficult to avoid. SUMMARY

[0003] The application provides a piston return structure to solve the problem of insufficient piston return amount in the existing vehicle braking system.

[0004] The first aspect of the application provides a piston return structure applied to the piston return of a brake caliper assembly, which comprises:

[0005] a screw rod, the first end of the screw rod being provided with external threads;

[0006] a screw sleeve provided with internal threads, the screw sleeve being threadedly matched with the screw rod; the screw sleeve is located in the piston and is axially slidably matched with the piston;

[0007] an elastic assembly located in the piston, the elastic assembly being connected between the screw sleeve and the piston.

[0008] The piston return structure described above is provided with an elastic assembly between the piston and the screw sleeve. When the parking is released, the screw sleeve is retracted to the parking release position, and the piston is also returned under the action of the elastic assembly. The return amount of the piston is much larger than the return amount provided by the rectangular rubber ring, thereby solving the problem of insufficient piston return amount in the existing vehicle braking system.

[0009] In the technical scheme of an embodiment, the elastic assembly is a coil spring, which is sleeved on the screw sleeve; the inner wall of the piston is provided with a first groove, the first groove is annular, and a first snap spring is arranged in the first groove; the outer wall of the screw sleeve is provided with a third protruding portion; the first end of the coil spring is abutted against the end face of the third protruding portion, the second end of the coil spring is abutted against the end face of the first snap spring, and the coil spring is arranged in a compressed state between the first snap spring and the third protruding portion.

[0010] In an embodiment, the elastic assembly comprises:

[0011] A positioning ring is located in the piston and is in interference fit with the inner wall of the piston.

[0012] A coil spring is sleeved on the screw sleeve, the first end of the coil spring is connected with the screw sleeve, and the second end of the coil spring is in abutment with the first end face of the positioning ring.

[0013] A retaining ring is fixedly sleeved on the screw sleeve, the positioning ring is located between the retaining ring and the coil spring, and the retaining ring is configured to be capable of being in abutment with the second end face of the positioning ring.

[0014] In an embodiment, the outer wall of the screw sleeve has a third protruding part, the first end of the coil spring is in abutment with the end face of the third protruding part, the second end of the coil spring is in abutment with the end face of the positioning ring located on one side of the coil spring, the outer wall of the screw sleeve is provided with a fourth groove, the fourth groove is annular, the fourth groove is configured with a third snap spring, the outer wall of the screw sleeve has a sixth protruding part, and the retaining ring is clamped and fixed between the third snap spring and the sixth protruding part.

[0015] In an embodiment, the retaining ring has a seventh protruding part on the ring wall, the seventh protruding part is arc-shaped and matched with the inner wall of the positioning ring, and the seventh protruding part is in contact with the inner wall of the positioning ring when the retaining ring is in contact with the positioning ring.

[0016] In an embodiment, the retaining ring has a through hole or a notch groove on the ring wall, for passing of liquid medium or gas medium.

[0017] In an embodiment, the positioning ring comprises a rectangular ring and a skeleton ring, the skeleton ring has a “concave” cross section, the rectangular ring is inlaid on the skeleton ring, the skeleton ring is used for being connected with or in contact with the retaining ring and the coil spring, and the rectangular ring is in interference fit with the inner wall of the piston.

[0018] In an embodiment, the piston is internally provided with a second groove, the second groove is an axial through groove; the outer wall of the screw sleeve has a fourth protruding part, the fourth protruding part is located in the second groove, and the fourth protruding part is configured to be capable of moving axially in the second groove.

[0019] In an embodiment, the inner wall of the piston is provided with a first groove, the first groove is annular, the first groove is configured with a second snap spring; when the screw sleeve is retreated to an overtravel position after the parking brake is released, the retaining ring is in contact with the second snap spring, and the fourth protruding part is also in the second groove.

[0020] In the technical scheme of one embodiment, the outer wall of the second end of the screw rod has a first protruding part, the first protruding part has a second protruding part on the end face of the first end of the screw rod; the end face of the screw sleeve towards the first protruding part has a fifth protruding part, the fifth protruding part and the second protruding part are in position corresponding relation; when the screw sleeve is retracted to the limit position, the side face of the fifth protruding part abuts against the side face of the second protruding part.

[0021] In the technical scheme of one embodiment, the end face of the piston is provided with a score; the end face of the piston is provided with at least two third grooves, and all the third grooves are arranged in an annular array.

[0022] The second aspect embodiment of the application provides an electronic parking brake caliper assembly, comprising a caliper body, the caliper body has a piston cavity, the piston cavity is configured with any of the above-mentioned piston return structures; wherein the piston and the piston cavity are in sliding fit.

[0023] In the technical scheme of one embodiment, the electronic parking brake caliper assembly further comprises:

[0024] A caliper support is connected to the caliper body through a pin shaft in sliding connection;

[0025] Two pieces of friction plates are both installed on the caliper support in sliding connection;

[0026] A driving return spring is installed between the friction plate and the caliper support, and the driving return spring is configured to drive the friction plate to return;

[0027] The return tension of the driving return spring matched with the inner friction plate is greater than the sliding resistance between the inner friction plate and the caliper support, and the return tension of the driving return spring matched with the outer friction plate is greater than the sum of the sliding resistance between the outer friction plate and the caliper support and the sliding resistance of the pin shaft.

[0028] The electronic parking brake caliper assembly first realizes the complete return of the piston through the piston return structure, thereby providing the necessary gap for the complete disengagement between the friction plate and the brake disc; secondly, the sufficient return of the friction plate is realized through the driving return spring between the friction plate and the caliper support, thereby forming sufficient gap between the inner and outer friction plates and the brake disc, to ensure no drag, which well solves the problem of drag in the vehicle braking system.

[0029] The third aspect embodiment of the application provides a combined parking brake caliper assembly, comprising any of the above-mentioned electronic parking brake caliper assemblies, wherein

[0030] The caliper body is provided with an oil hole, which is communicated with the piston cavity.

[0031] In the technical scheme of one embodiment, the piston cavity is provided with an annular groove, and a rectangular rubber ring is arranged in the annular groove, and the rectangular rubber ring is in interference fit with the outer wall of the piston, and the maximum static friction between the rectangular rubber ring and the piston is greater than the maximum static friction between the positioning ring and the piston.

[0032] In the technical scheme of one embodiment, the caliper body is further provided with an air hole, which is communicated with the piston cavity.

[0033] The above-mentioned integrated brake caliper assembly is characterized in that an oil hole is additionally arranged on the caliper body of the electronic parking brake caliper assembly, the oil hole connects the piston cavity with the oil supply system of the vehicle to perform service brake, and a motor driving mechanism is arranged to drive the screw rod to perform parking brake, so that the hydraulic service brake and the electronic parking brake are integrated, the structure is simplified, the weight is reduced, the cost is lowered, the piston return structure is introduced to ensure complete return of the piston, sufficient clearance is provided between the inner and outer friction plates and the brake disc, and the problem of drag of the vehicle brake system is solved. BRIEF DESCRIPTION OF DRAWINGS

[0034] The drawings in the present application are used to show the preferred embodiments, facilitate the understanding of various other advantages and benefits by those skilled in the art, and cannot be considered as limiting the present application. Moreover, the same reference numerals are used to represent the same components in all the drawings.

[0035] Figure 1 FIG. 1 is a sectional view of a piston return structure according to an embodiment of the present application.

[0036] Figure 2 FIG. 2 is a first perspective view of a screw rod, a screw sleeve and other components according to an embodiment of the present application.

[0037] Figure 3 FIG. 3 is a second perspective view of a screw rod, a screw sleeve and other components according to an embodiment of the present application.

[0038] Figure 4 FIG. 4 is a sectional view of another piston return structure according to an embodiment of the present application.

[0039] Figure 5 FIG. 5 is a third perspective view of a screw rod, a screw sleeve and other components according to an embodiment of the present application.

[0040] Figure 6 FIG. 6 is a perspective view of a screw sleeve according to an embodiment of the present application.

[0041] Figure 7 FIG. 7 is a perspective view of a retaining ring according to an embodiment of the present application.

[0042] Figure 8 The figure is a perspective view of the cooperation between the blocking ring and the positioning ring in an embodiment of the present application.

[0043] Figure 9 The figure is a sectional view of the piston in an embodiment of the present application.

[0044] Figure 10 The figure is a view of the end surface of the piston in an embodiment of the present application.

[0045] Figure 11 The figure is a sectional view of the electronic parking brake caliper assembly in an embodiment of the present application.

[0046] Figure 12 The figure is a perspective view of the electronic parking brake caliper assembly in an embodiment of the present application.

[0047] Figure 13 The figure is a sectional view of the integrated brake caliper assembly in an embodiment of the present application.

[0048] Figure 14 The figure is a perspective view of the integrated brake caliper assembly in an embodiment of the present application.

[0049] Figure 15 The figure is a view of the cooperation between the caliper bracket and the friction plate and the active return spring in an embodiment of the present application.

[0050] BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Caliper body 100, caliper bracket 200, piston 300, friction plate 400, brake disc 500, actuator 600, active return spring 700;

[0052] Piston cavity 110, rectangular rubber ring 120, oil hole 130, air hole 140;

[0053] First groove 310, second groove 320, engraved line 330, third groove 340;

[0054] Screw rod 610, first protruding part 611, second protruding part 612; screw sleeve 620, third protruding part 621, fourth protruding part 622, fifth protruding part 623, sixth protruding part 624, fourth groove 625, oil guide groove 626; helical spring 630; first clamping spring 640, second clamping spring 641, third clamping spring 642; positioning ring 650, skeleton ring 651, rectangular ring 652; blocking ring 660, seventh protruding part 661, fifth groove 662. DETAILED DESCRIPTION

[0055] The technical solutions in the embodiments of the present application will be clearly and completely described below with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work belong to the scope of protection of the present application.

[0056] Reference to "embodiments" herein means that the particular features, structures, or characteristics described with respect to the embodiments can be included in at least one embodiment of the present application. The phrase appears at various locations in the specification does not necessarily refer to the same embodiments, and is not necessarily mutually exclusive of other embodiments or alternative embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0057] In the description of the embodiments of the present application, the technical terms "first", "second", and the like are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "a plurality of" is two or more (including two), unless otherwise explicitly and specifically limited.

[0058] In the description of the embodiments of the present application, the orientation or positional relationship indicated by the technical terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", and the like are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0059] In the description of the embodiments of the present application, unless otherwise explicitly specified and limited, the technical terms "mounting", "connecting", "connecting", "fixing", and the like should be understood in a broad sense, for example, can be fixedly connected, or can be detachably connected, or can be integrated; can be mechanically connected, or can be electrically connected; can be directly connected, or can be indirectly connected through an intermediate medium; can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0060] The drag of the vehicle brake system components is caused by the vehicle driving in the state that the friction plate and the brake disc are not completely separated (residual clamping). The main hazards of the drag are: 1. causing the useless consumption of kinetic energy; 2. the excessive wear of the friction plate and the brake disc, reducing the service life of the components; 3. the long-term drag overheating leading to the attenuation of the braking performance.

[0061] Through research, it is found that the piston return of the electronic parking brake (EPB) brake caliper assembly and the parking and driving integrated brake caliper assembly is generally achieved by using the deformation restoring force of a rectangular rubber ring. The return amount provided by the rectangular rubber ring for the piston is very limited, so the problem of drag is difficult to avoid. The reason is that the parking force applied by the parking is generally large, the caliper body is deformed greatly under the force, and the friction plate is also compressed to a certain extent under the force. After parking, the piston moves forward (towards the friction plate) for a long distance. Especially after the slope parking, the forward movement amount of the piston exceeds the limit of the forward distortion of the rectangular rubber ring, the piston slips forward relative to the rectangular rubber ring, that is, the contact position between the piston and the rectangular rubber ring changes. After releasing the parking, the deformation restoring force of the rectangular rubber ring generates a pullback force on the piston. The return amount of the piston generated by the deformation restoring force of the rectangular rubber ring is offset by the deformation restoring amount of the caliper body and the friction plate. The pullback amount of the piston by the rectangular rubber ring is less than the forward movement amount of the piston during parking, so that an effective return gap cannot be formed between the friction plate and the brake disc. Even the friction plate may be stuck on the brake disc by the piston and cannot be separated, causing the drag, and in severe cases, even the brake may be locked. According to the above research, it is known that improving the return amount of the piston is one of the effective ways to eliminate the parking drag. Therefore, how to improve the return amount of the piston becomes a primary problem.

[0062] Referring to Figures 1-15 The first aspect embodiment of the present application provides a piston return structure applied to the return of the piston 300 of the brake caliper assembly, in particular the electronic parking brake caliper assembly and the parking and driving integrated brake caliper assembly. The main components involved in the piston return structure include the piston 300, the screw rod 610, the screw sleeve 620 and the elastic assembly. The first end (the right end of the screw rod 610) of the screw rod 610 has external threads, the screw sleeve 620 has internal threads, the screw sleeve 620 is threadedly connected with the screw rod 610 to form a screw sleeve and screw rod pair. The screw sleeve 620 is located in the piston 300 and axially slidably connected with the piston 300. The elastic assembly is located in the piston 300 and connected with the screw sleeve 620 and the piston 300 respectively. The elastic assembly provides the piston 300 with a force towards the second end (the left end of the screw rod 610) of the screw rod 610 through the elastic force of the elastic assembly. Figure 1 The first end (the right end of the screw rod 610) of the screw rod 610 has external threads, the screw sleeve 620 has internal threads, the screw sleeve 620 is threadedly connected with the screw rod 610 to form a screw sleeve and screw rod pair. The screw sleeve 620 is located in the piston 300 and axially slidably connected with the piston 300. The elastic assembly is located in the piston 300 and connected with the screw sleeve 620 and the piston 300 respectively. The elastic assembly provides the piston 300 with a force towards the second end (the left end of the screw rod 610) of the screw rod 610 through the elastic force of the elastic assembly. Figure 1The left end of the middle screw rod 610 is the force of the piston 300 in the return direction, i.e. the force of the piston 300 in the return direction. When parking, the screw rod 610 is driven in the forward direction by the motor to move the sleeve 620 forward, which pushes the piston 300 forward, and the piston 300 pushes the friction plate 400 to clamp the brake disc 500, thereby achieving parking brake; when the parking brake is released, the screw rod 610 is reversed by the motor to move the sleeve 620 backward to the parking brake release position, and the elastic component provides a force to the piston 300 in the return direction, and the piston 300 also returns under the action of the elastic component. The return amount of the piston 300 is much larger than the return amount provided by the rectangular rubber ring (even without the rectangular rubber ring), and is not affected by any factors, effectively solving the problem of insufficient piston return amount in the existing vehicle brake system.

[0063] Specifically, the front end of the sleeve 620 can be designed as a conical surface or a spherical surface for contacting the inner conical surface or the inner spherical surface of the piston 300 to transmit the parking force.

[0064] Continuing to refer to Figures 1-3 In some embodiments, the elastic component is a coil spring 630 sleeved on the sleeve 620 and connected to the piston 300 and the sleeve 620 at both ends. The selection of the coil spring 630 makes the installation convenient and stable.

[0065] Continuing to refer to Figure 1 , 2 , 3 and 9, specifically, the right end of the outer wall of the sleeve 620 has a third protruding part 621 which is a circular annular protrusion; the inner wall of the piston 300 is provided with a first slot 310 which is a circular annular slot, and the first slot 310 is configured with a first snap spring 640; the two ends of the coil spring 630 abut against the end face of the third protruding part 621 and the end face of the first snap spring 640, respectively, and the coil spring 630 is in a compressed state. The first snap spring 640 is used to assemble the coil spring 630 by cooperating with the third protruding part 621, i.e. the sleeve 620 is first installed in the piston 300, then the coil spring 630 is sleeved on the sleeve 620, and finally the first snap spring 640 is used to press the coil spring 630 until it is clamped in the first slot 310, completing the installation. The entire installation process is convenient and simple.

[0066] Further, the coil spring 630 is preferably a conical coil spring, the thin end of which is sleeved on the sleeve 620 and abuts against the end face of the third protruding part 621, and the thick end of which can abut against the end face of the first snap spring 640.

[0067] Referring to Figures 4-8In some embodiments, the elastic assembly can include a positioning ring 650, a coil spring 630, and a stop ring 660. The coil spring 630 is sleeved on the sleeve 620, the first end of the coil spring 630 is in abutment or fixed connection with the sleeve 620, and the stop ring 660 is fixedly sleeved on the sleeve 620, wherein the stop ring 660 is located on one side of the opening of the piston 300, and the coil spring 630 is located on one side of the end face of the piston 300; the positioning ring 650 is located in the piston 300 and is in interference fit with the inner wall of the piston 300, the positioning ring 650 is located between the stop ring 660 and the coil spring 630, the second end of the coil spring 630 is in abutment with the first end face of the positioning ring 650, and the stop ring 660 is configured to be capable of abutting the second end face of the positioning ring 650. When parking, the sleeve 620 is moved forward by driving the screw rod 610 (motor) to rotate forward, the forward movement of the sleeve 620 pushes the piston 300 to move forward, the forward movement of the piston 300 pushes the friction plate 400 to clamp the brake disc 500, thereby realizing parking brake; when the parking is released, the sleeve 620 is retracted to the parking release brake position by reversing the screw rod 610 (motor) to rotate, and the coil spring 630 is compressed during the retraction of the sleeve 620, the compression force of the coil spring 630 acts on the positioning ring 650, and due to the friction force between the positioning ring 650 and the piston 300 in interference fit, the positioning ring 650 provides a force to the piston 300 in the return direction, so that the piston 300 returns together, and the total return force is much larger than the return force provided by the rectangular rubber ring through the superposition of the return force of the rectangular rubber ring, thereby increasing the piston return amount, effectively solving the problem of insufficient piston return amount in the existing vehicle brake system.

[0068] It should be noted that when the stop ring 660 abuts the second end face of the positioning ring 650, the coil spring 630 can abut the first end face of the positioning ring 650 or have a small gap with the first end face of the positioning ring 650. As a preferred, the coil spring 630 is preferably in abutment with the first end face of the positioning ring 650, and the coil spring 630 is in a zero compression state or a critical compression state or a micro-compression state, so as to ensure that the piston 300 can be provided with a return force through the coil spring 630 when the sleeve 620 starts to retract, without delay.

[0069] Specifically Figures 4-8In the shown embodiment, the outer wall of the screw sleeve 620 is designed with a third protruding part 621, the first end of the helical spring 630 abuts against the end face of the third protruding part 621, and the second end of the helical spring 630 abuts against the end face of the positioning ring 650 on the side of the helical spring 630. The outer wall of the screw sleeve 620 is provided with a fourth slot 625 in the shape of a circular ring, the third snap spring 642 is installed in the fourth slot 625, and the outer wall of the screw sleeve 620 is further designed with a sixth protruding part 624, and the retaining ring 660 is clamped and fixed between the third snap spring 642 and the sixth protruding part 624. During installation, only the helical spring 630, the positioning ring 650, and the retaining ring 660 need to be sequentially installed into the piston 300, and finally the third snap spring 642 is installed in the fourth slot 625 to achieve the final installation, which is convenient and simple in structure.

[0070] Referring to Figures 7-8 In some embodiments, the retaining ring 660 has a seventh protruding part 661 on the ring wall, which can enhance the strength of the retaining ring 660. When the retaining ring 660 contacts the positioning ring 650, the seventh protruding part 661 contacts the inner wall of the positioning ring 650, which serves to support the positioning ring 650 and prevent radial deformation of the positioning ring 650, and also serves to center the positioning ring 650 during assembly.

[0071] It can be understood that the seventh protruding part 661 can be in the shape of a circular ring matching the inner wall of the positioning ring 650, or in the shape of a multi-segment arc matching the inner wall of the positioning ring 650.

[0072] Continuing to refer to Figures 7-8 In some embodiments, the retaining ring 660 has a through hole or a notched slot on the ring wall for the passage of liquid or gas medium. When applied to a brake caliper assembly of a brake-by-wire system, the through hole or notched slot design can facilitate the entry of hydraulic oil to achieve hydraulic parking brake.

[0073] Specifically, when the seventh protruding part 661 is in the shape of a multi-segment arc matching the inner wall of the positioning ring 650, a fifth slot 662 is provided between each segment of the arc.

[0074] It can be understood that the medium here currently mainly refers to hydraulic oil, but should not be considered as a limitation of the present application.

[0075] Continuing to refer to Figure 8In some embodiments, the positioning ring 650 comprises a rectangular ring 652 and a skeleton ring 651, the rectangular ring 652 is generally made of rubber, and the skeleton ring 651 is generally made of a metal material with high hardness, a ceramic material or a plastic material. The skeleton ring 651 has a "concave" cross section, and the rectangular ring 652 is embedded on the skeleton ring 651, the outer surface of which is exposed to the skeleton ring 651, and the rectangular ring 652 is used for interference fit with the inner wall of the piston 300. The skeleton ring 651 is used to contact the retaining ring 660 and the coil spring 630, which can prevent the compression deformation of the rectangular ring 652 and play a protective role.

[0076] Continuing to refer to Figure 2 , 9 In some embodiments, the piston 300 is internally provided with second grooves 320, generally three, which are axial through grooves. The outer wall of the sleeve 620 has fourth protrusions 622, which are the same in number as the second grooves 320, and the fourth protrusions 622 are located in the second grooves 320. Through the limitation of the second grooves 320, the fourth protrusions 622 can only move axially in the second grooves 320, thereby preventing the sleeve 620 from rotating with the screw rod 610.

[0077] Further, the cross section of the second groove 320 is arc-shaped, and the fourth protrusion 622 corresponding thereto is also arc-shaped. The cooperation of the arc-shaped groove and the arc-shaped protrusion can facilitate the alignment of the sleeve 620 when it is inserted into the piston 300, and can also avoid the problem of impact noise that is prone to occur when a rectangular groove is used.

[0078] Referring to Figure 4 , 9 In some embodiments, the inner wall of the piston 300 is provided with a first groove 310 in the form of a circular ring, and the first groove 310 is configured with a second snap spring 641. When the sleeve 620 is retracted to an overtravel position after the parking brake is released, the retaining ring 660 contacts the second snap spring 641, and the fourth protrusion 622 is also in the second groove 320. When the friction plate 400 needs to be replaced, after the sleeve 620 is retracted to the parking brake release position, it needs to be further retracted to a dead point. The continued retreat of the sleeve 620, under the pushing of the retaining ring 660 on the second snap spring 641, causes the piston 300 to retreat together with the sleeve 620 until the sleeve 620 is retracted to the dead point. If there is no second snap spring 64 provided in the piston 620 for limiting position, the sleeve 620 continues to retreat, while the piston 300 does not retreat all the time, and the fourth protrusion 622 of the sleeve 620 will be detached from the second groove 320, resulting in the loss of the anti-rotation function.

[0079] It should be noted that the "overtravel position" refers to a position where the sleeve 620 is retracted to the parking brake release position and then continues to retreat for a certain distance, but the fourth protrusion 622 of the sleeve 620 cannot be detached from the second groove 320.

[0080] Referring to Figure 3 In some embodiments, the second end outer wall of the screw rod 610 has a first protrusion 611, and the first protrusion 611 has a second protrusion 612 on the end face towards the first end of the screw rod 610. The screw sleeve 620 has a fifth protrusion 623 on the end face towards the first protrusion 611, and the fifth protrusion 623 and the second protrusion 612 are in position corresponding to each other. When the screw rod 610 is rotated in reverse, the screw sleeve 620 will be retracted to the parking brake release position, at this time the side surface of the fifth protrusion 623 and the side surface of the second protrusion 612 abut, preventing the screw rod 610 from continuing to rotate; correspondingly, the current of the motor driving the screw rod 610 to rotate will rise, and the signal of the current rise will be received by the vehicle computer to stop the operation of the motor. By abutting the side surface of the fifth protrusion 623 and the side surface of the second protrusion 612 to prevent the screw rod 610 from continuing to rotate, the end face of the first protrusion 611 and the end face of the screw sleeve 620 are not in contact (or not under force), which can prevent the locking of the end face of the first protrusion 611 and the end face of the screw sleeve 620 caused by excessive repositioning.

[0081] Referring to Figure 10 In some embodiments, the end face of the piston 300 is provided with a notch 330, which abuts against the brake disc 500 to prevent slipping.

[0082] Continuing to refer to Figure 10 In some embodiments, the end face of the piston 300 is provided with at least two third grooves 340, preferably three third grooves 340, and all the third grooves 340 are arranged in a ring array. When installing the piston 300, the piston 300 can be rotated into the piston cavity 110 of the caliper body 100 by clamping the third grooves 340 with a tool, so that the installation of the piston 300 is more convenient.

[0083] Referring to Figure 11 , 12 , 15, the second aspect embodiment of the present application provides an electronic parking brake caliper assembly, which generally comprises a caliper body 100 and any of the above-mentioned piston repositioning structures. The caliper body 100 has a piston cavity 110, and the piston repositioning structure is installed in the piston cavity 110, wherein the piston 300 is in sliding fit with the piston cavity 110. The electronic parking brake caliper assembly is matched with an electronic driving mechanism such as a motor and a speed reduction gear, and the screw rod 610 is driven by the electronic driving mechanism to realize parking brake and parking release. By designing the electronic parking brake caliper assembly with the piston repositioning structure, the problem of insufficient repositioning amount of the piston 300 in the existing vehicle brake system can be effectively solved.

[0084] Continuing to refer to Figure 11 , 12,15, In some embodiments, the electronic parking brake caliper assembly further comprises a caliper bracket 200, two friction plates 400, a main return spring 700 and a motor. The caliper bracket 200 is connected with the caliper body 100, the two friction plates 400 are each slidingly installed on the caliper bracket 200, the main return spring 700 is installed between the friction plate 400 and the caliper bracket 200, and is used to drive the friction plate 400 to return by elastic force. The output end of the motor is connected with the screw rod 610, and is used to drive the screw rod 610 to rotate in opposite directions. The above-mentioned electronic parking brake caliper assembly firstly realizes complete return of the piston 300 through the piston return structure, thereby providing a necessary gap for complete disengagement between the friction plate 400 and the brake disc 500; and secondly realizes sufficient return of the friction plate 400 through the main return spring 700 of the friction plate 400 and the caliper bracket 200, thereby forming sufficient gaps between the inner and outer friction plates 400 and the brake disc 500, to ensure no drag, and thus the problem of drag of the vehicle braking system is well solved.

[0085] Continuing to refer to Figure 11 、 12 ,15, In some embodiments, the caliper bracket 200 and the caliper body 100 are slidingly connected through a pin shaft to form a floating type electronic parking brake caliper assembly.

[0086] When the floating type electronic parking brake caliper assembly is in use:

[0087] When parking, the screw sleeve 620 pushes the piston 300 to move forward, and overcomes the force of forward torsional deformation of the rectangular rubber ring, the return tension of the main return spring 700 of the inner friction plate 400, and the sliding resistance of the inner friction plate 400, and pushes the inner friction plate 400 to press against the inner braking surface of the brake disc 500; at the same time, the screw rod 610 that is rotationally connected with the screw sleeve 620 pushes the caliper body 100 to retreat, overcomes the sliding resistance of the connecting pin shaft of the caliper bracket 200, the sliding resistance of the outer friction plate 400, and the return tension of the outer main return spring 700, and pushes the outer friction plate 400 to press against the outer braking surface of the brake disc 500 through the caliper body 100, and further exerts force to clamp the brake disc 500 to realize braking.

[0088] At this time, the main return spring 700 of the inner and outer friction plates 400 is elastically deformed under tension, and stores elastic potential energy for return. After releasing the brake, the screw rod 610 is reversed, the screw sleeve 620 is pulled back, and the screw sleeve 620 retreats to compress the spring. At this time, the screw sleeve 620 is disengaged from the piston, a gap is formed, on the one hand, the restoring force of the deformation of the rectangular rubber ring makes the piston 300 retreat, and on the other hand, the spring also makes the piston 300 retreat by elastic force, so that the piston 300 completes sufficient return stroke, and provides a necessary gap for complete disengagement between the friction plate 300 and the brake disc 500.

[0089] At the same time, the active return spring 700 of the inner friction plate 400 pulls back the inner friction plate 400 against the sliding resistance of the inner friction plate 400. The active return spring 700 of the outer friction plate 400 pulls back the outer friction plate 400 and the caliper body 100 against the sliding resistance of the pin shaft and the sliding resistance of the outer friction plate 400, so that the inner and outer friction plates 400 form a uniform effective gap between the friction surfaces and the brake disc 500, and eliminate the drag.

[0090] It should be noted that the return tension of the active return spring 700 of the inner friction plate 400 is slightly greater than the sliding resistance of the inner friction plate 400, and the return tension of the active return spring 700 of the outer friction plate 400 is slightly greater than the sum of the sliding resistance of the outer friction plate 400 and the sliding resistance of the pin shaft. Such a setting is to ensure that neither the inner nor the outer friction plate 400 drags, that is, both sides have an effective and uniform gap. The difference in the elasticity of the active return spring 700 of the inner and outer friction plates 400 can be achieved by designing the effective cross-sectional area of the elastic portion of the active return spring 700 to deform, and the effective cross-sectional area of the elastic portion of the outer active return spring 700 is greater than that of the inner active return spring 700.

[0091] Continuing to refer to Figure 13 , 14 The third aspect of the present application provides a combined service and parking brake caliper assembly, which comprises any of the above electronic parking brake caliper assemblies, and an oil hole 130 is formed in the caliper body 100, and the oil hole 130 is connected to the piston cavity 110 and the oil supply system of the vehicle, that is, a combined service and parking brake caliper assembly is formed, which uses hydraulic drive for service braking and motor drive for parking braking, and the two functions of braking share one piston 300. The above combined service and parking brake caliper assembly adds an oil hole 130 to the caliper body 100 of the electronic parking brake caliper assembly, the oil hole 130 connects the piston cavity 110 and the oil supply system of the vehicle for service braking, and a motor drive mechanism drives the screw rod 610 for parking braking, realizing the integration of hydraulic service braking and electronic parking braking. While simplifying the structure, reducing the weight and cost, the piston return structure is also introduced to ensure the complete return of the piston 300, provide sufficient gap between the inner and outer friction plates 400 and the brake disc 500, prevent drag, and well solve the problem of drag of the vehicle braking system.

[0092] Continuing to refer to Figure 13In some embodiments, the piston cavity 110 has an annular groove, and a rectangular rubber ring 120 is arranged in the annular groove and is in interference fit with the outer wall of the piston 300; and the maximum static friction between the rectangular rubber ring 120 and the piston 300 is greater than the maximum static friction between the positioning ring 650 and the piston 300. This design can still achieve effective and reliable hydraulic braking when the parking brake is abnormal. For example, when the screw sleeve 620 is excessively moved backward under the pulling of the screw rod 610, the piston 300 will not excessively move backward to cause insufficient oil supply of the hydraulic service brake. The reason is that the screw sleeve 620 excessively moves backward to compress the coil spring 630, and when the coil spring 630 reaches a certain compression amount, the compression force generated by the coil spring 630 is greater than the maximum static friction between the positioning ring 650 and the inner surface of the piston 300, and because the maximum static friction between the positioning ring 650 and the inner surface of the piston 300 is less than the maximum static friction between the rectangular rubber ring 120 and the outer surface of the piston 300, the positioning ring 650 slips backward on the inner surface of the piston 300, and the piston 300 does not move, so that the piston has a limited backward stroke and will not cause insufficient oil supply of the hydraulic brake due to excessive backward movement. After the parking fault is ruled out, a normal parking brake is performed, and then the normal original position is restored, because the push disc attached to the screw sleeve 620 pushes the positioning ring 650 to the original position together with the parking brake process, and the function of the piston return structure is restored.

[0093] Continuing to refer to Figure 14 In some embodiments, the caliper body 100 is also provided with an air hole 140, which is in communication with the piston cavity 110 and is used for air exhaust.

[0094] In order to clearly understand the above technical solutions, the following specifically introduces several common states of the brake caliper assembly, especially the integrated parking and service brake caliper assembly. The following description is only for the convenience of understanding the present application and does not limit the present application in any way.

[0095] 1. Initial installation state

[0096] When the friction plate is initially installed or replaced, the screw sleeve 620 needs to be retreated to the dead point (i.e. the limit point), and the piston 300 is completely retreated to the position, that is, the front conical surface of the screw sleeve 620 abuts against the inner conical surface of the piston 300. Among them

[0097] The screw sleeve 620 starts to retreat under the pulling of the screw rod 610 in reverse rotation, the screw sleeve 620 compresses the coil spring 630, the coil spring 630 presses the positioning ring 650, and the positioning ring 650 pushes the piston 300 to retreat after being compressed.

[0098] When the piston 300 retreats beyond the amount of deformation of the rectangular rubber ring 120, the piston 300 no longer retreats. The reason is that the maximum static friction of the rectangular rubber ring 120 on the outer surface of the piston 300 is greater than the maximum static friction of the positioning ring 650 on the inner surface of the piston 300. For this reason, the sleeve 620 further retreats to further compress the positioning ring 650, so that the positioning ring 650 generates backward sliding from the inner surface of the piston 300. The sleeve 620 continues to retreat until the end surface of the stop ring 660 abuts against the second snap spring 641.

[0099] The sleeve 620 continues to retreat, and under the pushing of the stop ring 660 on the second snap spring 641, the piston 300 retreats together with the sleeve 620 until the sleeve 620 retreats to the dead point. It should be noted that if there is no second snap spring 641 for limiting the piston 300, the sleeve 620 continues to retreat, and the piston 300 does not retreat all the time, and the fourth protruding part 622 will be out of the second groove 320 and lose the anti-rotation function.

[0100] After the sleeve 620 retreats to the dead point, the piston 300 is retreated to the original starting point by using the piston 300 zero reset tool, that is, the front outer conical surface of the sleeve 620 is in contact with the front inner conical surface in the hole of the piston 300.

[0101] 2. Electronic parking inspection on assembly line

[0102] From the initial state to the realization of normal electronic parking and release on the assembly line, the action principle is as follows: when parking, the screw rod 610 rotates forward to push the sleeve 620 and the piston 300 to move axially forward, the forward movement of the sleeve 620 drives the stop ring 660 to move forward, and then the stop ring 660 pushes the positioning ring 650 to move forward; when parking, the compression amount of the spiral spring 630 is zero. After parking release, the screw rod 610 reverses, the sleeve 620 retreats, the positioning ring 650 is limited by the friction resistance of the surface of the piston 300 and does not retreat, and the spiral spring 630 is slightly compressed, at this time the piston 300 is reset under the action of the double retreat forces of the rectangular rubber ring 120 and the spiral spring 630.

[0103] 3. Normal parking state and release state

[0104] When parking on a flat road or in a normal parking state, the set parking force is small, so the deformation of the caliper body 100, the friction plate 400 and the like is small, the forward movement amount of the piston 300 is the inherent reset gap plus the small deformation amount of the caliper body 100, the forward movement amount of the piston 300 is small, the inner surface of the rectangular rubber ring 120 is twisted and deformed by the friction of the outer surface of the piston 300, and the spiral spring 630 is in a zero compression state.

[0105] Screw 610 reverse rotation drives screw sleeve 620 back to release parking position, complete release parking. On one hand, rectangular rubber ring 120 deformation recovery force makes piston 300 back; on the other hand, helical spring 630 is slightly compressed by back screw sleeve 620, superimposed force piston 300 back. Under the joint action of two return force, piston 300 back to release parking position, restore the gap between the brake disc 500 and the friction plate 400.

[0106] 4, limit parking state and release state

[0107] Screw 610 forward rotation, drive screw sleeve 620, piston 300 forward to achieve parking. Because the parking force of the limit parking such as slope is larger, the deformation of the caliper body 100, friction plate 400 and so on is large, the forward movement of the screw sleeve 620 and piston 300 is large.

[0108] Parking release, screw sleeve 620 back to the original position of the back stroke is increased accordingly, the compression of the helical spring 630 is increased, the spring force of the helical spring 630 is increased, the piston 300 back is also increased. The increased piston 300 back stroke compensates the deformation of the caliper body 100, friction plate 400 and so on to the consumption of the rectangular rubber ring 120 back, so that the piston 300 can return to the release parking brake position, ensure the gap between the friction plate 400 and the brake disc 500.

[0109] 5, normal hydraulic braking state

[0110] Normal hydraulic braking, the hydraulic pressure used for braking is small, the caliper body 100 and the friction plate 400 are almost not deformed, the piston 300 forward stroke is short, the rectangular rubber ring 120 forward distortion is also small; at the same time, because the position of the screw sleeve 620 is limited by the screw 610 and does not move, the piston 300 forward drives the positioning ring 650 forward, the positioning ring 650 forward will slightly compress the helical spring 630.

[0111] Hydraulic braking release, piston 300 back under the action of rectangular rubber ring 120 deformation recovery force, at the same time, under the action of the thrust of the slightly compressed helical spring 630, the positioning ring 650 resets, plays the role of auxiliary piston 300 back, makes the piston 300 fully back to the release hydraulic braking position.

[0112] 6, high pressure (or limit) hydraulic braking state

[0113] When high pressure or extreme hydraulic service braking occurs, the caliper body 100 and the friction plate 400 are deformed greatly, the piston 300 moves forward and the stroke increases, at this time the rectangular rubber ring 120 is twisted and deformed forward and the deformation also increases; at the same time, since the position of the screw sleeve 620 is limited by the screw rod 610 and does not move, the piston 300 moves forward and drives the positioning ring 650 to move forward and compress the spiral spring 630. Since the piston 300 moves forward by a large amount, the compression amount of the spiral spring 630 is also large, and the elastic potential energy stored is also large.

[0114] After the hydraulic service braking is released, the piston 300 is fully and completely reset under the action of the strong deformation recovery force of the rectangular rubber ring 120 and the greater elastic force of the spiral spring 630.

[0115] 7. Abnormal state of the parking brake

[0116] The abnormal state of the electronic parking brake includes excessive reset, which specifically refers to that when the parking control is abnormal, the screw sleeve 620 moves backward excessively under the pulling of the screw rod 610, and the piston 300 also moves backward together. If the piston 300 moves backward excessively, the hydraulic service braking needs more liquid, and the oil supply system also needs to increase the oil supply. If the oil supply system cannot increase the oil supply in time, the hydraulic service braking will fail. Since the maximum static friction between the positioning ring 650 and the inner surface of the piston 300 is less than the maximum static friction between the rectangular rubber ring 120 and the outer surface of the piston 300, the screw sleeve 620 compresses the spiral spring 630 excessively, and when the compression amount of the spiral spring 630 reaches a certain amount, the elastic force generated by the spiral spring 630 is greater than the maximum static friction between the positioning ring 650 and the inner surface of the piston 300, the positioning ring 650 slips backward on the inner surface of the piston 300, and the piston 300 does not move backward excessively. Therefore, after the parking control is abnormal, effective and reliable hydraulic braking can still be achieved. After the fault is eliminated, a normal parking brake is performed to restore to normal; this is because the blocking ring 660 attached to the screw sleeve 620 pushes the positioning ring 650 to the normal position during the parking process, and the normal function of the piston reset structure is restored.

[0117] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than limit them. Although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that the technical solutions recorded in the foregoing embodiments can be modified, or some or all of the technical features can be replaced equivalently; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should be covered in the scope of the claims and the description of the present application. In particular, the technical features mentioned in each embodiment can be combined in any manner as long as there is no contradiction and conflict. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A piston return structure characterized by, The application is applied to piston (300) return of brake caliper assembly, comprising: Screw rod (610), the first end of the screw rod (610) has external threads; Screw sleeve (620), having internal threads, the screw sleeve (620) is threadedly connected with the screw rod (610); the screw sleeve (620) is located in the piston (300), and is in axial sliding fit with the piston (300); Elastic assembly, located in the piston (300), the elastic assembly is connected between the screw sleeve (620) and the piston (300); The elastic assembly comprises: Positioning ring (650), the positioning ring (650) is located in the piston (300), and the positioning ring (650) is in interference fit with the inner wall of the piston (300); Spiral spring (630), the spiral spring (630) is sleeved on the screw sleeve (620), the outer wall of the screw sleeve (620) has a third protruding portion (621), the first end of the spiral spring (630) abuts against the end face of the third protruding portion (621) of the screw sleeve (620), and the second end of the spiral spring (630) abuts against the end face of the positioning ring (650) located on one side of the spiral spring (630); Retaining ring (660), the retaining ring (660) is fixedly sleeved on the screw sleeve (620), the positioning ring (650) is located between the retaining ring (660) and the spiral spring (630), and the retaining ring (660) is configured to abut against the second end face of the positioning ring (650).

2. The piston return structure of claim 1, wherein: The outer wall of the screw sleeve (620) is provided with a fourth groove (625), the fourth groove (625) is annular, the fourth groove (625) is provided with a third snap spring (642), the outer wall of the screw sleeve (620) has a sixth protruding portion (624), and the retaining ring (660) is clamped and fixed between the third snap spring (642) and the sixth protruding portion (624).

3. The piston return structure of claim 1, wherein: The ring wall of the retaining ring (660) has a seventh protruding portion (661), the seventh protruding portion (661) is arc-shaped and matched with the inner wall of the positioning ring (650), and the seventh protruding portion (661) contacts the inner wall of the positioning ring (650) when the retaining ring (660) contacts the positioning ring (650); the ring wall of the retaining ring (660) has a fifth groove (662) for passing of liquid medium or gas medium.

4. The piston return structure of claim 1, wherein: The positioning ring (650) comprises a rectangular ring (652) and a skeleton ring (651), the skeleton ring (651) is "concave” in cross section, the rectangular ring (652) is embedded on the skeleton ring (651), the skeleton ring (651) is used for being connected with or contacting the retaining ring (660) and the spiral spring (630), and the rectangular ring (652) is in interference fit with the inner wall of the piston (300).

5. The piston return structure of claim 2, wherein: The piston (300) is internally provided with a second groove (320), which is an axial through groove; the outer wall of the sleeve (620) has a fourth protruding part (622), which is located in the second groove (320) and is configured to be axially movable in the second groove (320); the inner wall of the piston (300) is provided with a first groove (310) in the form of a circular ring, and the first groove (310) is configured with a second circlip (641); when the sleeve (620) is returned to the overtravel position after the parking brake is released, the retaining ring (660) is in contact with the second circlip (641), and the fourth protruding part (622) is also in the second groove (320).

6. An electronic parking brake caliper assembly characterized by: The caliper body (100) is provided with a piston cavity (110) configured with the piston return structure of any one of claims 1-5; wherein the piston (300) is in sliding fit with the piston cavity (110).

7. The electronic parking brake caliper assembly of claim 6, wherein: The electronic parking brake caliper assembly further comprises: A caliper bracket (200) is in sliding connection with the caliper body (100) through a pin shaft; Two friction plates (400) are both slidingly installed on the caliper bracket (200); A driving return spring (700) is installed between the friction plate (400) and the caliper bracket (200), and is configured to drive the friction plate (400) to return; Wherein, the return tension of the driving return spring (700) matched with the inner friction plate (400) is greater than the sliding resistance between the inner friction plate (400) and the caliper bracket (200), and the return tension of the driving return spring (700) matched with the outer friction plate (400) is greater than the sum of the sliding resistance between the outer friction plate (400) and the caliper bracket (200) and the sliding resistance of the pin shaft.

8. A park-and-hold brake caliper assembly characterized by: The electronic parking brake caliper assembly of any one of claims 6-7, wherein The caliper body (100) is provided with an oil hole (130) in communication with the piston cavity (110); The piston cavity (110) has an annular groove, and the annular groove is configured with a rectangular rubber ring (120), which is in interference fit with the outer wall of the piston (300), and the maximum static friction between the rectangular rubber ring (120) and the piston (300) is greater than the maximum static friction between the positioning ring (650) and the piston (300).

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