Disc brake device

Abstract

The dual-purpose piston (7) is configured as a two-part structure consisting of a piston body (22) and a piston cover (23). A one-way rotation limiting part (40) is arranged between the piston body (22) and the piston cover (23). When the main shaft (82) is driven to rotate in the forward rotation direction, the one-way rotation limiting part (40) restricts the relative rotation of the piston body (22) with respect to the piston cover (23) in the forward rotation direction. When the main shaft (82) is driven to rotate in the reverse rotation direction, the one-way rotation limiting part (40) allows the piston body (22) to rotate relative to the piston cover (23) in the reverse rotation direction.

Description

Technical Field

[0001] This invention relates to disc brake devices. Background Technology

[0002] Disc brakes have excellent heat dissipation and are increasingly used not only on the front wheels of cars but also on the rear wheels because they allow for fine adjustments to braking force during driving.

[0003] Disc brake systems can be broadly classified into hydraulic disc brake systems that use working oil to obtain braking force, and electric disc brake systems that use electrically driven actuators to obtain braking force.

[0004] As for electric disc brake devices, as disclosed in Japanese Patent Application Publication No. 2018-184093, there are known electric parking brake structures that generate braking force based on the service brake by supplying brake oil (fluid) into the cylinder, and generate braking force based on the parking brake by using an electric actuator such as a rotary linear motion conversion mechanism.

[0005] In disc brake systems with electric parking brakes, since the cylinder contains brake fluid, if the rotor becomes hot due to pressure on the rotating pads, heat can be transferred to the brake fluid via the piston, causing the brake fluid temperature to rise. This temperature rise leads to brake fluid deterioration and can cause vapor lock.

[0006] Therefore, to prevent heat transfer from the brake pads to the brake fluid, as disclosed in Japanese Patent Application Publication No. 2015-25550, a split piston structure is considered. Specifically, it is considered to consist of a piston body that is fitted into the cylinder and subjected to hydraulic pressure, and a piston cap that presses against the brake pads. With this structure, compared to a one-piece piston structure, the amount of heat transferred to the brake fluid can be reduced. Therefore, the temperature rise of the brake fluid can be suppressed.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent Application Publication No. 2018-184093

[0010] Patent Document 2: Japanese Patent Application Publication No. 2015-25550 Summary of the Invention

[0011] The technical problem that the invention aims to solve

[0012] The structure described in Japanese Patent Application Publication No. 2015-25550 connects the piston body and piston cover by interlocking the protrusion of the piston cover with the recess of the piston body. However, if such a piston body-piston cover connection structure is directly applied to a disc brake device for electric parking brakes, the following problems may occur.

[0013] That is, as an electric actuator, when using a rotary-linear motion conversion mechanism consisting of a main shaft as a rotating component and a nut as a linear motion component, in order to obtain braking force based on the parking brake, when the drive shaft is rotated in the forward rotation direction, slippage occurs between the part from the nut to the piston body that is subjected to torque and the piston cover, and the piston body may spin freely along with the nut. Therefore, it is difficult to reliably obtain braking force based on the parking brake.

[0014] To eliminate the aforementioned problems, consider connecting the piston body and piston cover in a manner that prevents relative rotation. With such a structure, when the drive shaft rotates in the forward direction, free spin of the piston body and nut can be prevented, ensuring a stable braking force based on the parking brake.

[0015] However, to release the parking brake, when the drive shaft is rotated in the opposite direction, the nut moves (fully released) to its limit position on the reverse side, thereby locking the nut and shaft (i.e., the axial movement of the nut as the shaft rotates cannot proceed further, and the nut and shaft are forced to rotate together). When the nut and shaft are locked, the electric motor, as the drive source, may reach its stopping torque (maximum current). That is, if the nut and shaft are locked, the torque acting on the piston body from the nut increases sharply. Conversely, the piston body is restricted from rotating by the piston cap, thus the shaft stops abruptly, and the electric motor easily reaches its stopping torque. Therefore, the durability of the electric motor is easily reduced. Furthermore, when a reduction mechanism such as a gear reducer is provided between the motor and the shaft, the torque acting on the reduction mechanism becomes excessive, and the durability of the reduction mechanism is also easily reduced.

[0016] The present invention was made to solve the above-mentioned problems, and its object is to provide an electric parking brake type disc brake device that can suppress the temperature rise of brake fluid, can stably obtain braking force based on the parking brake, and can eliminate the problems that occur when the linear motion component is completely released to the reverse side.

[0017] Technical means for solving problems

[0018] The disc brake device of the present invention includes a liner, a brake caliper, a piston, and a rotary-linear motion conversion mechanism.

[0019] The brake caliper has a cylinder with an opening on the side of the liner.

[0020] The piston is fitted into the cylinder body, pressing the liner towards the rotor.

[0021] The rotary-to-linear motion conversion mechanism pushes the piston toward the rotor by converting the rotational motion of the drive source into linear motion.

[0022] The disc brake device of the present invention generates braking force based on a service brake by supplying brake fluid into the cylinder and generates braking force based on a parking brake by activating the rotary linear motion conversion mechanism.

[0023] Furthermore, the disc brake device of the present invention consists of a piston body and a piston cover, which are formed by dividing the piston into two parts in the axial direction.

[0024] The rotary-linear motion conversion mechanism includes: a rotary component that is driven to rotate by the drive source; and a linear motion component that is screwed onto the rotary component and disposed inside the piston body, engaging with the piston body in a manner that prevents relative rotation, and pressing the piston body axially.

[0025] A one-way rotation limiting part is provided between the piston body and the piston cover. When the rotating component is driven to rotate in the forward rotation direction in order to move the linear motion component toward the rotor side, the one-way rotation limiting part restricts the relative rotation of the piston body with respect to the piston cover in the forward rotation direction. When the rotating component is driven to rotate in the reverse rotation direction in order to move the linear motion component toward the reverse rotation side, the one-way rotation limiting part allows the relative rotation of the piston body with respect to the piston cover in the reverse rotation direction.

[0026] In a first embodiment of the disc brake device of the present invention, the unidirectional rotation limiting part includes: at least one (preferably multiple) convex or concave body-side engaging part disposed on the piston body; and at least one (preferably multiple) convex or concave cover-side engaging part disposed on the piston cover, which mechanically engages with the body-side engaging part when the rotating component is driven to rotate in the positive rotation direction.

[0027] The main body side engaging portion can be integrally formed with other parts constituting the piston body, or it can be separately formed from the other parts and fixed to the other parts.

[0028] The cover-side engaging portion can be integrally formed with other parts constituting the piston cover, or it can be separately formed from the other parts and fixed to the other parts.

[0029] In one aspect of the disc brake device of the present invention, the piston body may be made of metal, and the piston cover may be made of metal or synthetic resin.

[0030] In one aspect of the disc brake device of the present invention, at least one of the portion of the main body-side engagement portion that contacts the cover-side engagement portion when rotating the rotating component in the forward rotation direction and the portion of the cover-side engagement portion that contacts the main body-side engagement portion when rotating the rotating component in the forward rotation direction has a limiting surface that is parallel (including substantially parallel) to the central axis of the piston.

[0031] In one aspect of the disc brake device of the present invention, the portion of the main body side engaging portion that contacts the cover side engaging portion when the rotating component is driven to rotate in the opposite direction has a main body side guide surface. The main body side guide surface is more rearward in the opposite direction and closer to the rotor in the axial direction. When the rotating component is driven to rotate in the opposite direction, the main body side guide surface can be pushed up by the cover side engaging portion.

[0032] In this case, the main body side guide surface can be set as an inclined surface or a curved surface (including a partially cylindrical surface with a cross-sectional arc and a partially spherical surface).

[0033] In one aspect of the disc brake device of the present invention, the portion of the cover-side engaging portion that contacts the main body-side engaging portion when the rotating component is driven to rotate in the reverse rotation direction has a cover-side guide surface. The more the cover-side guide surface moves towards the front in the reverse rotation direction and further away from the rotor in the axial direction, the more the main body-side engaging portion can be pushed up when the rotating component is driven to rotate in the reverse rotation direction.

[0034] In this case, the cover-side guide surface can be set as an inclined surface or a curved surface (including a partially cylindrical surface with an arc cross-section and a partially spherical surface).

[0035] In one aspect of the disc brake device of the present invention, at least the cover-side engagement portion of the piston cover may be made of metal.

[0036] In this case, the piston cap may be configured to have a cap body made of synthetic resin and a metal engaging piece molded into the cap body, with a portion of the engaging piece forming the cap-side engaging portion.

[0037] In this case, the piston cap may further include: a cap body made of synthetic resin; a metal engaging tab, a portion (base) of which is molded into the cap body; and a metal power transmission component. Furthermore, the power transmission component may be exposed from the end face of the cap body, forming the cap-side transmission surface described later.

[0038] In a disc brake device according to one aspect of the present invention, a plurality of the main body side engaging portions and a plurality of the cover side engaging portions may be provided separately in the circumferential direction.

[0039] In this case, a plurality of the main body side engaging portions can be arranged at equal intervals in the circumferential direction, and a plurality of the cover side engaging portions can be arranged at equal intervals in the circumferential direction.

[0040] In one aspect of the disc brake device according to the present invention, the piston cover may be supported on the piston body in a manner that allows for relative displacement in the axial direction.

[0041] In this case, the piston cover can be supported on the piston body in such a way that it can be axially displaced relative to the amount corresponding to the amount by which at least the body-side engagement portion can pass over the cover-side engagement portion when the rotating component is driven to rotate in the opposite direction.

[0042] In one aspect of the disc brake device of the present invention, an axial force transmission part may be provided between the piston body and the piston cover, which transmits axial force between the piston body and the piston cover. The axial force transmission part may be provided in addition to the unidirectional rotation limiting part.

[0043] In this case, the axial force transmission section can be composed of the following parts: a flat, planar body-side transmission surface located on an imaginary plane in the piston body orthogonal to the central axis of the piston body; and a flat, planar cover-side transmission surface located on an imaginary plane in the piston cover orthogonal to the central axis of the piston cover.

[0044] In a second embodiment of the disc brake device of the present invention, the unidirectional rotation limiting part can also function as a means of transmitting axial force between the piston body and the piston cover.

[0045] In this case, the unidirectional rotation limiting part can be composed of a body-side sliding contact surface and a cover-side sliding contact surface. The body-side sliding contact surface is disposed on the piston body, and the cover-side sliding contact surface is disposed on the piston cover and is axially opposed to the body-side sliding contact surface.

[0046] At least one of the body-side sliding contact surface and the cover-side sliding contact surface may be surface-processed to increase the coefficient of friction between the body-side sliding contact surface and the cover-side sliding contact surface, or at least one of the body-side sliding contact surface and the cover-side sliding contact surface may be composed of a friction component.

[0047] When the rotating component is driven to rotate in the forward rotation direction, as the axial force acting on the cover-side sliding contact surface from the main body side sliding contact surface increases, the main body side sliding contact surface and the cover-side sliding contact surface are rubbed together in a manner that prevents them from rotating relative to each other. When the rotating component is driven to rotate in the reverse rotation direction, as the axial force acting on the cover-side sliding contact surface from the main body side sliding contact surface decreases, the main body side sliding contact surface can rotate relative to the cover-side sliding contact surface in the reverse rotation direction.

[0048] Invention Effects

[0049] According to the present invention, an electric parking brake disc brake device can be realized, which can suppress the temperature rise of brake fluid, stably obtain braking force based on the parking brake, and eliminate the problems that occur when the linear motion component is fully released to the reverse side. Attached Figure Description

[0050] Figure 1 This is a front view of a disc brake device illustrating a first example of an embodiment.

[0051] Figure 2 This is a top view of a disc brake device illustrating a first example of an embodiment.

[0052] Figure 3 yes Figure 1 A sectional view along line AA.

[0053] Figure 4 yes Figure 3 A magnified view of a portion of the image.

[0054] Figure 5 This is the first example of an implementation, showing a cross-sectional schematic diagram of an example of an anti-rotation structure of the piston cover relative to the inner liner block.

[0055] Figure 6 This is the first example of an implementation method, showing a cross-sectional view with the dual-use piston removed. Figure 6 (A) shows the case where the main shaft is driven to rotate in the positive rotation direction. Figure 6 (B) shows the case where the main axis is driven to rotate in the opposite direction of rotation.

[0056] Figure 7 This is the first example of an implementation method, showing a diagram of the piston body. Figure 7 (A) is the front view. Figure 7 (B) is a three-dimensional diagram.

[0057] Figure 8 yes Figure 7 A magnified view of (B).

[0058] Figure 9 This is the first example of an implementation method, showing a diagram of the piston cap being removed. Figure 9 (A) is the rear view. Figure 9 (B) is a three-dimensional diagram.

[0059] Figure 10 yes Figure 9 A magnified view of (B).

[0060] Figure 11 This is the first example of an implementation method, showing a front view of the piston body to illustrate the function of the unidirectional rotation limiting part. Figure 11 (A) shows the positional relationship between the main body side engagement part and the cover side engagement part when the main axis is driven to rotate in the positive rotation direction. Figure 11 (B) shows the positional relationship between the main body side engagement part and the cover side engagement part when the main axis is driven to rotate in the opposite direction of rotation.

[0061] Figure 12 (A) is Figure 6 A magnified view of (A). Figure 12 (B) is Figure 6 A magnified view of (B).

[0062] Figure 13 This is a top view of a disc brake device illustrating a second example of an embodiment.

[0063] Figure 14 This is a rear view of a disc brake device illustrating a second example of an embodiment.

[0064] Figure 15 yes Figure 14 BB line section view.

[0065] Figure 16 This is a second example of the implementation method, showing a cross-sectional view with the piston removed.

[0066] Figure 17 This is a third example of the implementation method, equivalent to Figure 7 The image.

[0067] Figure 18 This is a third example of the implementation method, equivalent to Figure 9 The image.

[0068] Figure 19 This is a cross-sectional schematic diagram of the piston cover, illustrating the fourth embodiment.

[0069] Figure 20 This is a cross-sectional schematic diagram of the piston cover, illustrating the fifth embodiment.

[0070] Figure 21 This is the sixth example of the implementation method, equivalent to Figure 12 A schematic diagram.

[0071] Figure 22 This is the seventh example of the implementation method, equivalent to Figure 12 A schematic diagram.

[0072] Symbol Explanation

[0073] 1.1a Disc Braking System

[0074] 2 Opposed Piston Braking Mechanism

[0075] 3. Floating Braking Mechanism

[0076] 4. 4a brake caliper

[0077] 5 clamping components

[0078] 6a and 6c outer liner blocks

[0079] 6b and 6d inner lining blocks

[0080] 7. Dual-purpose piston

[0081] 8. Special pistons for automobiles

[0082] 9 rotors

[0083] 10a is transferred to the outer cylinder block.

[0084] 10b Rotate outward side outer cylinder block

[0085] 11a Transfer to the inner cylinder block

[0086] 11b Rotation outward side inner cylinder block

[0087] 12 Actuators

[0088] 13 External Main Body

[0089] 14 inner body part

[0090] 15a Turn-in side connection

[0091] 15b Turn-out side connection

[0092] 16. Intermediate connecting part

[0093] 17 Mounting base

[0094] Oil passages 18a and 18b

[0095] 19 Large diameter hole

[0096] 20 Small Diameter Hole Section

[0097] 21 Guide tube

[0098] Piston bodies 22, 22a, and 22b

[0099] Piston caps 23, 23a, 23b, 23c, 23d

[0100] 24 large diameter barrel

[0101] 25 Small Diameter Cylindrical Section

[0102] 26, 26a, 26b, 26c partition sections

[0103] 27 Bottom

[0104] 28 Hydraulic Chamber

[0105] 29, 29a internal splines

[0106] 30a, 30b, 30c piston seals

[0107] 31a, 31b, 31c sealing grooves

[0108] 32, 32a, 32b, 32c, 32d, 32e cylindrical part

[0109] 33, 33a, 33b Closed plate section

[0110] 34 engagement recess

[0111] 35. The cartilaginous protuberance.

[0112] 36, 36a Piston Protector

[0113] 37 Annular Grooves

[0114] 38, 38a piston rings

[0115] 39, 39a retain grooves

[0116] 40, 40a Unidirectional Rotation Restriction Section

[0117] 41, 41b Main body side locking part

[0118] 42, 42a, 42b, 42c cover side locking parts

[0119] 43, 43a Main body side limiting surface

[0120] 44 Main body side guide surface

[0121] 45, 45a, 45b, 45c cover side limiting surfaces

[0122] 46, 46a, 46b cover side guide surfaces

[0123] 47 Axial force transmission unit

[0124] 48 Main body side transfer surface

[0125] 49, 49a Cover side transfer surface

[0126] 50 Hydraulic Chambers

[0127] 51 Sealing groove

[0128] 52 Piston Seals

[0129] 53 Dust Cover

[0130] 54 Drain screw

[0131] 55a, 55b guide wall sections

[0132] 56a, 56b guide grooves

[0133] 57 Liner

[0134] 58 Backplate

[0135] 59 Ears

[0136] 60, 60a pressing part

[0137] 61, 61a Clamping base

[0138] Bridge sections 62 and 62a

[0139] 63, 63a Base Main Body

[0140] 64, 64a arm

[0141] 65 Accommodation

[0142] 66, 66a bottom

[0143] 67, 67a Through Holes

[0144] 68 Support cylinder section

[0145] 69 First Guiding Department

[0146] 70 Second Guiding Section

[0147] 71 Third Guiding Department

[0148] 72 Sealing groove

[0149] 73 Sealing components

[0150] 74 Dust Cover

[0151] 75 Inner guide pin

[0152] 76. Protruding support portion

[0153] 77 Outer guide pin

[0154] 78 Electric drive unit

[0155] 79 Rotary-to-linear motion conversion mechanism

[0156] 80 housing

[0157] 81 Rotation axis

[0158] 82 Spindle

[0159] 83 Nuts

[0160] 84 External thread section

[0161] 85 Flange portion

[0162] 86 Thrust Bearing

[0163] 87 Internal thread section

[0164] 88 external splines

[0165] 89 Support components

[0166] 90 Piston

[0167] 91 Support base

[0168] 92 Outer connecting part

[0169] 93 Connecting arm

[0170] 94 mounting holes

[0171] 95 cylinder block

[0172] 96 Guide Sales

[0173] 97 Shield

[0174] 98 Hydraulic Chamber

[0175] 99 Main body side sliding contact surface

[0176] 100 Cover side sliding contact surface

[0177] 101 Cover Body

[0178] 102 Cards

[0179] 103 Base

[0180] 104 Axial force transmission components

[0181] 105 corner

[0182] 106. Cylindrical section

[0183] 107 cover Detailed Implementation

[0184] [First Example of Implementation]

[0185] use Figures 1 to 12 The first example of the implementation method will be described.

[0186] [Overall structure of disc brake system]

[0187] The disc brake device 1 in this example is an electric parking brake type disc brake device, which simultaneously functions as a hydraulic service brake and as an electric parking brake. The disc brake device 1 has a structure that combines an electric floating brake mechanism 3, which functions as a parking brake, with a hydraulic opposed piston brake mechanism 2 that functions as a service brake.

[0188] The disc brake device 1 includes a opposed piston type brake caliper 4 fixed to a suspension device such as a steering knuckle, a clamping member 5 supported on the brake caliper 4 in a manner that allows for axial displacement, a pair of pads 6a and 6b (outer pad 6a and inner pad 6b), and a total of 4 pistons 7 and 8 (one general-purpose piston 7 and three vehicle-specific pistons 8).

[0189] In this example, unless otherwise specified, axial, circumferential, and radial directions refer to the disc-shaped rotor 9 that rotates with the wheel (see reference). Figure 2 ) in the axial, circumferential and radial directions. Figure 1 , Figure 7 (A) Figure 9 The back direction of (A) Figure 2 as well as Figure 3 Up and down directions and Figures 4-6 The left and right directions correspond to the axial directions, respectively. The central side of the vehicle body in its assembled state is called the axial inner side, and the outer side of the vehicle body in its assembled state is called the axial outer side. Furthermore, Figures 1 to 3 left and right directions and Figure 4 The vertical direction corresponds to the circumferential direction. Figures 1-3 The right side and Figure 4 The upper side is called the circumferential side, and the upper side is called the circumferential side. Figures 1-3 The left side and Figure 4The lower side is referred to as the other side of the circumference. In this example, one side of the circumference becomes the turning-in side when the vehicle is moving forward and the turning-out side when the vehicle is moving backward, while the other side of the circumference becomes the turning-out side when the vehicle is moving forward and the turning-in side when the vehicle is moving backward. Furthermore, Figure 1 The up and down directions, and Figure 2 and Figure 3 The directions of the front and back of the face correspond to the radial directions, respectively. Figure 1 The upper side and Figure 2 as well as Figure 3 The outer sides are radially outer. Figure 1 The lower side and Figure 2 as well as Figure 3 The back sides are radially inner sides. In addition, the rotating-in side refers to the side where the rotor 9 enters the brake caliper 4, and the rotating-out side refers to the side where the rotor 9 leaves the brake caliper 4.

[0190] The disc brake 1 obtains braking force based on the service brake by supplying brake fluid (pressurized oil) as working fluid into all (four in the illustrated example) cylinders 10a, 10b, 11a, and 11b of the brake caliper 4, which constitutes the opposed piston brake mechanism 2. In contrast, the disc brake 1 obtains parking brake-based braking force by driving an electric actuator 12, which constitutes the floating brake mechanism 3, without using working fluid, to axially displace the clamping member 5 relative to the brake caliper 4. Both the opposed piston brake mechanism 2 and the floating brake mechanism 3 share a pair of bushings 6a and 6b and a combined piston 7.

[0191] [Opposite Piston Braking Mechanism]

[0192] The brake caliper 4, which constitutes the opposed piston type brake mechanism 2, supports the outer liner 6a and the inner liner 6b so that they can move axially ( Figure 1 The direction of the back of the watch, Figure 2 as well as Figure 3 The brake caliper 4 moves in the vertical direction. This brake caliper 4 is a casting (including die-cast) of a light alloy such as aluminum alloy, and has an outer body portion 13 and an inner body portion 14 disposed on both axial sides of the rotor 9, and connecting portions 15a, 15b, and 16 disposed radially outward of the rotor 9. The brake caliper 4 is supported and fixed to the suspension device by a pair of mounting seats 17 provided in the inner body portion 14.

[0193] The connecting part 15a is disposed on the circumferential side of the brake caliper 4 (in Figures 1-3 On the right side (the turning side when the vehicle is moving forward), and located radially outside the rotor 9, the outer main body 13 is axially connected to the inner main body 14 on one circumferential side. The turning-out side connection 15b is located on the other circumferential side of the brake caliper 4 (on the right side, the turning-in side). Figures 1-3The outer body portion 13 is located on the left side (the side where the vehicle turns out when moving forward), and is positioned radially outside the rotor 9, connecting the other circumferential side of the outer body portion 13 and the other circumferential side of the inner body portion 14 axially. The intermediate connecting portion 16 is positioned circumferentially in the middle of the brake caliper 4 and radially outside the rotor 9, connecting the middle circumferential side of the outer body portion 13 and the middle circumferential side of the inner body portion 14 axially.

[0194] The outer main body 13 is disposed on the axially outer side of the rotor 9, having an infeed-side outer cylinder 10a on one circumferential side and an outfeed-side outer cylinder 10b on the other circumferential side. The inner main body 14 is disposed on the axially inner side of the rotor 9, having an infeed-side inner cylinder 11a on one circumferential side and an outfeed-side inner cylinder 11b on the other circumferential side. The infeed-side outer cylinder 10a and the infeed-side inner cylinder 11a are coaxially arranged facing each other in the axial direction, and the outfeed-side outer cylinder 10b and the outfeed-side inner cylinder 11b are coaxially arranged facing each other in the axial direction.

[0195] The outer main body 13 and the inner main body 14 each have internal oil passages 18a and 18b, respectively. The oil passage 18a inside the outer main body 13 extends circumferentially, connecting the inner cylinder 10a on the rotating side to the outer cylinder 10b on the rotating out side. The oil passage 18b inside the inner main body 14 extends circumferentially, connecting the inner cylinder 11a on the rotating side to the inner cylinder 11b on the rotating out side. The two oil passages 18a and 18b are interconnected.

[0196] Of the four cylinders 10a, 10b, 11a, and 11b, a dual-purpose piston 7, used in both the service brake and parking brake, is fitted inside the inner cylinder 11a on the rotating side in such a way that it can be displaced axially. Inside the remaining three cylinders 10a, 10b, and 11b (excluding the inner cylinder 11a on the rotating side), a dedicated service piston 8, used only in the service brake, is fitted inside such a way that it can be displaced axially.

[0197] The inner cylinder block 11a is equivalent to the cylinder block described in the claims, such as... Figure 3 and Figure 4 As shown, it opens not only to the axially outer side of the inner main body 14, but also to the axially inner side of the inner main body 14. That is, the inner cylinder 11a on the rotating side is formed to penetrate the inner main body 14 axially. The inner cylinder 11a on the rotating side is a stepped bore, with a large-diameter bore 19 in the axially outer half and a small-diameter bore 20 in the axially inner half.

[0198] A guide cylinder 21 is provided at the opening edge of the small-diameter bore 20. The guide cylinder 21 extends axially inward from the opening edge of the small-diameter bore 20 of the inner cylinder 11a on the rotating side and is coaxially disposed with the inner cylinder 11a on the rotating side. The guide cylinder 21 has a cylindrical shape and has the same inner diameter as the small-diameter bore 20. The axial length of the guide cylinder 21 is greater than the displacement of the clamping member 5, which moves axially when the parking brake is engaged.

[0199] [Dual-purpose piston]

[0200] The dual-purpose piston 7, fitted into the inner cylinder 11a on the rotating side, corresponds to the piston described in the claims and has a split structure that is divided into two parts in the axial direction. The dual-purpose piston 7 consists of a piston body 22 and a piston cap 23.

[0201] The piston body 22 is made of carbon steel such as S10C or S45C, and is configured as a bottomed cylindrical shape, fitting into the inner cylinder 11a on the rotating side. The piston body 22 has: a large-diameter cylindrical portion 24, which is disposed on the axially outer side and fitted into the large-diameter bore portion 19; and a small-diameter cylindrical portion 25, which is disposed on the axially inner side and fitted into the small-diameter bore portion 20.

[0202] The large-diameter cylindrical section 24 has a generally circular plate-shaped partition wall 26. The partition wall 26 is disposed in the axial middle portion of the large-diameter cylindrical section 24, axially separating (sealing off) the interior of the large-diameter cylindrical section 24. For example... Figure 4 As shown, the inner end face of the large-diameter cylinder portion 24 and the outer radial portion of the inner axial surface of the partition wall portion 26 are axially opposed to the bottom surface 27 of the large-diameter bore portion 19 of the inner cylinder body 11a. An annular hydraulic chamber 28 for introducing brake fluid is formed between the inner end face of the large-diameter cylinder portion 24, the outer radial portion of the inner axial surface of the partition wall portion 26, and the bottom surface 27 of the large-diameter bore portion 19 of the inner cylinder body 11a. The hydraulic chamber 28 is connected to the oil passage 18b.

[0203] The small-diameter cylindrical section 25 extends axially inward from the radially central portion of the axially inner side of the partition wall section 26 and is coaxially arranged with the large-diameter cylindrical section 24. An internal spline 29 is provided on the inner circumferential surface of the small-diameter cylindrical section 25.

[0204] The portions between the large-diameter cylindrical section 24 and the large-diameter bore section 19, and the portions between the small-diameter cylindrical section 25 and the small-diameter bore section 20, are respectively sealed by annular piston seals 30a and 30b. Piston seal 30a is installed in a sealing groove 31a formed on the inner circumferential surface of the axially intermediate portion of the large-diameter bore section 19. Piston seal 30b is installed in a sealing groove 31b formed on the inner circumferential surface of the axially intermediate portion of the small-diameter bore section 20.

[0205] The piston cap 23 is made of, for example, stainless steel, titanium, or synthetic resin, and is composed of a cylindrical portion 32 and a closing plate portion 33, forming a bottomed cylindrical shape. The axially inner side of the cylindrical portion 32 of the piston cap 23 is disposed inside the large-diameter cylindrical portion 24, and the axially outer side of the cylindrical portion 32 is anti-rotating relative to the inner liner block 6b. Specifically, as... Figure 5 As shown, by engaging the engaging protrusion (tenon) 35 of the inner liner block 6b (back plate 58) with the engaging recess 34 of the end face of the cylindrical portion 32 on the axially outer side, the relative rotation of the piston cover 23 with respect to the inner liner block 6b is restricted.

[0206] Alternatively, in implementing the present invention, the anti-rotation structure between the piston cover and the inner liner block can be omitted, and the relative rotation of the piston cover with respect to the inner liner block can be restricted by the frictional force acting between the piston cover and the inner liner block.

[0207] A piston shield 36 is provided between the cylindrical portion 32 of the piston cap 23 and the axially outer opening edge of the large-diameter bore portion 19 of the inner cylinder 11a. The radially outer portion of the piston shield 36 is fitted into the annular groove 37 provided in the axially outer opening edge of the large-diameter bore portion 19, and the radially inner portion of the piston shield 36 is externally fitted into the axially middle portion of the cylindrical portion 32.

[0208] In the cylindrical portion 32 of the piston cap 23, a piston ring 38, integrally C-shaped, is externally fitted into the portion disposed inside the large-diameter cylindrical portion 24 of the piston body 22. The piston ring 38 has a circular cross-sectional shape. The radially outer portion of the piston ring 38 engages with a retaining groove 39, which has a generally rectangular cross-section, on the inner circumferential surface of the large-diameter cylindrical portion 24, in a manner that allows for axial displacement. Thus, the piston cap 23 is held in a position to allow relative axial displacement with respect to the piston body 22. In implementing the present invention, the piston ring may also be fitted into the inner circumferential surface of the large-diameter cylindrical portion, such that the radially inner portion of the piston ring engages with the retaining groove formed on the outer circumferential surface of the piston cap in a manner that allows for axial displacement. Furthermore, when the piston cap 23 is held in the piston body 22, the central axis O of the piston cap 23 is... 23 (Refer to Figure 9 ) and the central axis O of piston body 22 22 (Refer to Figure 7 They are coaxially arranged. The central axis of the piston cap 23 and the central axis of the piston body 22, which are coaxially arranged, are also called the central axis of the dual-use piston 7.

[0209] <One-way rotation restriction section>

[0210] In this example, a one-way rotation limiting part 40 is disposed between the piston body 22 and the piston cover 23. Moreover, the piston body 22 and the piston cover 23 are not connected by interlocking or relative rotation in either direction, as in the existing structures described above, but are connected via the one-way rotation limiting part 40.

[0211] The one-way rotation limiting part 40 functions like a one-way clutch, limiting (preventing) the piston body 22 from rotating in the forward direction relative to the piston cover 23. Figure 7 , Figure 11 and Figure 12 Relative rotation in the direction of the arrow X) but allows rotation in the opposite direction ( Figure 7 , Figure 11 and Figure 12 The relative rotation of the piston body 22 relative to the piston cover 23 in the forward rotation direction is restricted, as described later. Specifically, when the main shaft 82 of the electric actuator 12, which constitutes the linear motion conversion mechanism 79, is driven to rotate in the forward rotation direction to obtain braking force based on the parking brake (when applied), the one-way rotation restriction unit 40 restricts the relative rotation of the piston body 22 relative to the piston cover 23 in the forward rotation direction. Conversely, when the main shaft 82 is driven to rotate in the reverse rotation direction to release the braking force based on the parking brake (when released), the one-way rotation restriction unit 40 allows the relative rotation of the piston body 22 relative to the piston cover 23 in the reverse rotation direction.

[0212] In order to perform the functions described above, the unidirectional rotation limiting part 40 has a body-side engaging part 41 on the piston body 22 and a cover-side engaging part 42 on the piston cover 23. The body-side engaging part 41 and the cover-side engaging part 42 are mechanically (and cannot be disengaged) engaged when the main shaft 82 is driven to rotate in the forward rotation direction.

[0213] The main body side engaging portion 41 is provided on the axial outer side of the partition wall portion 26 of the piston body 22. For example... Figure 7 as well as Figure 8 As shown, the main body side engaging portion 41 has a convex shape protruding in the axial direction, and multiple portions (four in the illustrated example) are provided at equal intervals in the circumferential direction on the radially outer side of the axially outer surface of the partition wall portion 26. The multiple main body side engaging portions 41 are arranged around the central axis O of the piston body 22. 22 On the concentric circles centered on the center.

[0214] The main body side engaging portions 41 each have a generally triangular prism shape, a generally fan-shaped shape when viewed axially, and a triangular shape when viewed radially. Therefore, the axial height of each main body side engaging portion 41, from its axially outer surface of the partition wall portion 26, varies in the circumferential direction. Specifically, the main body side engaging portions 41 each have a shape that varies in the positive rotation direction (…). Figure 7The arrow (in the X direction) points from back towards the front (in the opposite rotation direction). Figure 7 The shape is such that the axial height gradually increases from front to rear (in the direction of arrow Y). Therefore, the axial height of the main body side engaging part 41 is highest at the front end in the positive rotation direction and lowest at the rear end in the positive rotation direction.

[0215] like Figure 8 As shown, the main body side engaging portion 41 has a main body side limiting surface 43 on its front side in the positive rotation direction. The main body side limiting surface 43 is configured as a flat surface and is perpendicular to the central axis O of the piston body 22. 22 They are arranged in parallel. That is, the main body side limiting surface 43 is a right-angled surface that is perpendicular to the axial outer surface of the partition wall portion 26. In this example, the main body side limiting surface 43 is arranged on the central axis O including the piston body 22. 22 On the imaginary plane. When the main shaft 82 is driven to rotate in the positive rotation direction, the main body side limiting surface 43 contacts the cover side limiting surface 45, which will be described later, of the cover side engaging part 42.

[0216] like Figure 8 As shown, the main body side engaging portion 41 has a main body side guide surface 44 on its axial end face. The main body side guide surface 44 is a flat surface that is inclined in a straight line from the front towards the rear and closer to the rotor 9 in the counter-rotation direction. That is, the main body side guide surface 44 is an inclined surface inclined relative to the axial outer surface of the partition wall portion 26. The inclination angle α relative to the axial outer surface of the partition wall portion 26 (refer to...) Figure 12 (A) The angle is preferably set in the range of 10 degrees to 70 degrees, and more preferably in the range of 25 degrees to 55 degrees. When the main drive spindle 82 is rotated in the reverse rotation direction, the main body side guide surface 44 contacts the cover side guide surface 46, which will be described later, provided in the cover side engaging portion 42. The main body side guide surface 44 and the main body side limiting surface 43 are connected via a chamfered portion.

[0217] The cover-side engaging portion 42 is located on the axially inner end face of the cylindrical portion 32 of the piston cover 23. For example... Figure 9 as well as Figure 10 As shown, the cover-side engaging portion 42 has a convex shape protruding in the axial direction, and multiple portions (four in the illustrated example) are evenly spaced apart in the circumferential direction on the end face of the cylindrical portion 32 on the axially inner side. The multiple cover-side engaging portions 42 are arranged around the central axis O of the piston cover 23. 23 On the concentric circles centered on the center.

[0218] The cover-side engaging portions 42 each have a shape substantially the same as the respective main body-side engaging portions 41. That is, each cover-side engaging portion 42 has a substantially triangular prism shape, a substantially fan-shaped shape when viewed axially, and a triangular shape when viewed radially. Therefore, the axial height of each cover-side engaging portion 42, from the end face axially inside the cylindrical portion 32, varies in the circumferential direction. Specifically, each cover-side engaging portion 42 has a shape that varies in the counter-rotation direction ( Figure 9 The arrow (in the Y direction) points from back towards the front (in the positive rotation direction). Figure 9 The shape gradually increases in axial height from front to rear (in the direction of arrow X). Therefore, the axial height of the cover-side engaging portion 42 is highest at the front end in the reverse rotation direction and lowest at the rear end in the reverse rotation direction.

[0219] like Figure 10 As shown, the cover-side engaging portion 42 has a cover-side limiting surface 45 on its rear side in the positive rotation direction. The cover-side limiting surface 45 is configured as a flat surface and is aligned with the central axis O of the piston cover 23. 23 They are arranged in parallel. That is, the cover-side limiting surface 45 is a right-angled surface perpendicular to the end face of the axially inner side of the cylindrical portion 32. In this example, the cover-side limiting surface 45 is arranged on the central axis O including the piston cover 23. 23 On the imaginary plane. When the main shaft 82 is driven to rotate in the positive rotation direction, the cover side limiting surface 45 contacts the main body side limiting surface 43 of the main body side engaging part 41.

[0220] like Figure 10 As shown, the cover-side engaging portion 42 has a cover-side guide surface 46 on its axial end face. The cover-side guide surface 46 is configured as a flat surface, and is an inclined surface that slopes linearly from the rear towards the front and away from the rotor 9 in the reverse rotation direction. That is, the cover-side guide surface 46 is an inclined surface that slopes relative to the axially inner end face of the cylindrical portion 32. The inclination angle β relative to the axially inner end face of the cylindrical portion 32 (refer to...) Figure 12 (A) The angle is preferably set in the range of 10 degrees to 70 degrees, and more preferably in the range of 25 degrees to 55 degrees. In this example, the tilt angle β of the cover-side guide surface 46 is set to be the same as the tilt angle α of the main body-side guide surface 44. However, the tilt angle β and the tilt angle α can also be different. When the drive spindle 82 is rotated in the reverse rotation direction, the cover-side guide surface 46 contacts the main body-side guide surface 44 of the main body-side engaging portion 41. The cover-side guide surface 46 and the cover-side limiting surface 45 are connected by a chamfered portion.

[0221] The tilt angle α of the main body side guide surface 44 and the tilt angle β of the cover side guide surface 46 can be determined by taking into account the situation that the main body side guide surface 44 overcomes the frictional force of the piston seals 30a and 30b acting on the piston body 22 and jumps onto the cover side guide surface 46, and the main body side guide surface 44 slides off the cover side guide surface 46 during positive rotation drive.

[0222] like Figure 11 (A) and Figure 12 As shown in (A), when the main shaft 82 is rotated in the positive rotation direction, each main body side limiting surface 43, which is a right angle surface, and each cover side limiting surface 45, which is a right angle surface, simultaneously make surface contact, and the main body side engaging part 41 and the cover side engaging part 42 mechanically engage. Here, the piston cover 23, which has the cover side engaging part 42, stops rotating relative to the inner liner block 6b and cannot rotate around the central axis O. 23 Rotation. Therefore, when the main shaft 82 is driven to rotate in the positive rotation direction, the relative rotation of the piston body 22 with respect to the piston cover 23 in the positive rotation direction is restricted.

[0223] In contrast, such as Figure 11 (B) and Figure 12 As shown in (B), when the main drive shaft 82 is rotated in the reverse rotation direction, each body-side guide surface 44, which is an inclined surface, simultaneously contacts each cover-side guide surface 46, which is also an inclined surface. Here, the piston cover 23, which has the cover-side engaging portion 42, is held so that it can be axially displaced relative to the piston body 22, which has the body-side engaging portion 41, and the axial outward displacement is limited by the rotor 9. Therefore, the cover-side guide surface 46 can use its inclination to push the body-side guide surface 44 axially upward (move towards the rotor 9). This allows the piston body 22 to rotate (displace) relative to the piston cover 23 in the reverse rotation direction.

[0224] In this example, sufficient axial clearance (loosening) is ensured for the piston ring 38 and the retaining groove 39. Specifically, the piston cap 23 is held in a position to allow relative axial displacement with respect to the piston body 22 by an amount corresponding to the body-side engagement 41 being able to pass over the cap-side engagement 42. Thus, allowing the body-side engagement 41 to pass over the cap-side engagement 42 allows the piston body 22 to rotate relative to the piston cap 23 in the opposite direction of rotation.

[0225] In addition to the aforementioned unidirectional rotation limiting part 40, an axial force transmission part 47 for transmitting axial force between the piston body 22 and the piston cover 23 is provided between the piston body 22 and the piston cover 23.

[0226] The axial force transmission unit 47 includes: a main body side transmission surface 48 disposed on the piston body 22; and a cover side transmission surface 49 disposed on the piston cover 23. The main body side transmission surface 48 and the cover side transmission surface 49 are arranged opposite each other in the axial direction.

[0227] like Figure 7 As shown, the main body-side transmission surface 48 has an annular shape and is positioned radially outward from the main body-side engaging portion 41 on the axially outer side of the partition wall portion 26 of the piston body 22. The main body-side transmission surface 48 is configured as a flat surface and is arranged relative to the central axis O of the piston body 22. 22 On an orthogonal imaginary plane.

[0228] like Figure 9 As shown, the cover-side transmission surface 49 has an annular shape and is positioned radially outward from the cover-side engaging portion 42 on the end face of the cylindrical portion 32 of the piston cover 23, axially inner side. The cover-side transmission surface 49 is configured as a flat surface and is positioned relative to the central axis O of the piston cover 23. 23 On an orthogonal imaginary plane.

[0229] (Driving-specific piston)

[0230] The dedicated piston 8, like the dual-purpose piston 7, has a two-part structure. For example... Figure 3 As shown, the crane-specific piston 8 is made of carbon steel, for example, and consists of a cylindrical portion 106 with a bottom and a cover portion 107, for example made of stainless steel, installed at the end of the cylindrical portion 106. A hydraulic chamber 50 for introducing pressurized oil is formed between the bottom surface of the crane-specific piston 8 and the inner portion of each cylinder 10a, 10b, 11b on which the crane-specific piston 8 is fitted. Furthermore, annular piston seals 52 are installed in sealing grooves 51 formed on the inner circumferential surfaces of each cylinder 10a, 10b, 11b. Additionally, a dust cover 53 is provided between the opening edge of each cylinder 10a, 10b, 11b and the end portion of the crane-specific piston 8.

[0231] Brake fluid is supplied to the hydraulic chambers 28 and 50 of each cylinder 10a, 10b, 11a, and 11b through oil passages 18a and 18b provided in the outer main body 13 and the inner main body 14. In this example, the pressure-bearing area of ​​the shared piston 7 and the pressure-bearing area of ​​the dedicated service piston 8 opposite to the shared piston 7 are equal. Therefore, during service braking, the shared piston 7 and the dedicated service piston 8 (and other dedicated service pistons 8) opposite to the shared piston 7 in the axial direction press against the two axial sides of the rotor 9 with equal force. The opening of the oil passage 18a is blocked by the vent screw 54.

[0232] A pair of guide wall portions 55a and 55b extending axially toward the rotor 9 are respectively provided on the circumferential sides of the inner side of the outer main body portion 13 and the circumferential sides of the outer side of the inner main body portion 14. The guide wall portion 55a disposed on one circumferential side has a guide groove 56a opening to the axial direction and the other circumferential direction, and the guide wall portion 55b disposed on the other circumferential side has a guide groove 56b opening to the axial direction and one circumferential direction.

[0233] [Outer liner block and inner liner block]

[0234] Outer liner 6a and inner liner 6b are disposed on both axial sides of rotor 9. Specifically, outer liner 6a is disposed between rotor 9 and outer body portion 13, and inner liner 6b is disposed between rotor 9 and inner body portion 14. Outer liner 6a and inner liner 6b each have a liner (friction member) 57 and a metal back plate (pressure plate) 58 supporting the back of the liner 57. In this example, inner liner 6b corresponds to the liner described in the claims.

[0235] The back plate 58 has circumferentially protruding ears 59 on both sides. The pair of ears 59 on the outer liner 6a are loosely engaged with a pair of guide grooves 56a and 56b on the outer main body 13. Similarly, the pair of ears 59 on the inner liner 6b are loosely engaged with a pair of guide grooves 56a and 56b on the inner main body 14. Thus, the outer liner 6a and inner liner 6b are supported such that they can move axially relative to the brake caliper 4 but cannot move circumferentially or radially. Furthermore, the back of the back plate 58 constituting the inner liner 6b has a generally cylindrical engaging protrusion 35 protruding axially inward (see reference). Figure 5 The engaging recess 34 of the piston cover 23, which constitutes the dual-purpose piston 7, engages with the engaging protrusion 35.

[0236] [Floating Braking Mechanism]

[0237] The clamping member 5 constituting the floating brake mechanism 3 is made of aluminum alloy or iron alloy and has an inverted U-shape. The clamping member 5 is circumferentially positioned between the insertion-side connecting portion 15a and the intermediate connecting portion 16, extending radially outward across a pair of bushings 6a and 6b and the inner main body portion 14. That is, the clamping member 5 is mounted on the brake caliper 4. The clamping member 5 has two strand-shaped pressing portions 60 on its axially outer side and a clamping base 61 on its axially inner side. Furthermore, the clamping member 5 has a bridge portion 62 disposed radially outward of the rotor 9, connecting the pressing portions 60 and the clamping base 61 axially.

[0238] The pressing part 60 is inserted radially outward into the portion between the axial inner side of the circumferential side half of the outer main body part 13 and the axial outer side of the circumferential side half of the outer liner 6a, in a manner that crosses the outer cylinder 10a on the rotating side.

[0239] The clamping base 61 is disposed on the axial inner side of the inner body 14, and includes a base body 63 and an arm 64 extending circumferentially from the base body 63 to the other side. Figure 3 and Figure 4 As shown, the base body 63 has a generally cylindrical space, namely a receiving portion 65, inside. The receiving portion 65 opens outward in the axial direction, but the opening on the inward side is blocked by the bottom 66. The receiving portion 65 has an inner diameter that is slightly larger than the outer diameter of the guide tube 21 provided in the inner body portion 14. A through hole 67 extending in the axial direction is provided in the center of the bottom 66.

[0240] The arm portion 64 has an axially elongated support cylinder portion 68 at its end. The support cylinder portion 68 is open on both sides in the axial direction, and the central axis of the support cylinder portion 68 is parallel to the central axis of the receiving portion 65 provided in the base body 63.

[0241] <Support structure for clamping components>

[0242] The clamping member 5 described above is supported so that it can be displaced axially relative to the brake caliper 4. In this example, the clamping member 5 is supported on the brake caliper 4 by a total of three parts: the first guide 69, the second guide 70, and the third guide 71.

[0243] like Figure 3 as well as Figure 4 As shown, the first guide portion 69 is composed of a guide cylinder 21 provided in the inner main body portion 14 and a receiving portion 65 provided in the clamping base portion 61. That is, the first guide portion 69 is constructed by fitting the front half of the guide cylinder 21 into the inner side of the receiving portion 65 in a manner that allows for relative displacement in the axial direction. Furthermore, the central axis of the guide cylinder 21 is coaxially arranged with the central axis of the receiving portion 65. The radial clearance between the outer peripheral surface of the guide cylinder 21 and the inner peripheral surface of the receiving portion 65 is set to such that even when the parking brake is applied and the pressing portion 60 and the clamping base portion 61 are displaced in a direction that separates them in the axial direction, there will be no prying between the outer peripheral surface of the guide cylinder 21 and the inner peripheral surface of the receiving portion 65. In addition, a sealing groove 72 with a generally rectangular cross-section is formed on the axially inner side of the inner peripheral surface of the receiving portion 65, and an annular sealing member 73 is installed in the sealing groove 72. Thus, a sealing member 73 is clamped between the outer peripheral surface of the guide cylinder 21 and the inner peripheral surface of the receiving portion 65, thereby sealing the guide cylinder 21 within the receiving portion 65. Furthermore, a dust cover 74 is provided between the opening edge of the receiving portion 65 and the axial midpoint of the outer peripheral surface of the guide cylinder 21.

[0244] The second guide portion 70 is positioned circumferentially offset from the first guide portion 69, at the same circumferential position as the intermediate connecting portion 16, and together with the first guide portion 69, supports the clamping member 5 in a manner that allows axial displacement relative to the brake caliper 4. This second guide portion 70 consists of a support cylinder portion 68 provided in the arm portion 64 constituting the clamping base portion 61 and an inner guide pin 75 fixed to the inner body portion 14. The outer axial portion of the inner guide pin 75 is fixed to the inner body portion 14, and the middle axial portion is inserted into the inner side of the support cylinder portion 68 in a manner that allows axial sliding (relative displacement). Therefore, the inner guide pin 75 is axially positioned between the inner body portion 14 and the support cylinder portion 68. Furthermore, the central axis of the inner guide pin 75 is arranged parallel to the central axis of the guide cylinder 21.

[0245] The third guide portion 71 is positioned circumferentially at the same location as the first guide portion 69, and together with the first guide portion 69 and the second guide portion 70, supports the clamping member 5 so that it can be displaced axially relative to the brake caliper 4. This third guide portion 71 consists of a protruding support portion 76 provided on the outer body portion 13 and an outer guide pin 77 fixed to the clamping member 5. The protruding support portion 76 is located radially outward of the rotating outer cylinder 10a in the outer body portion 13. The axially inner portion of the outer guide pin 77 is fixed to the pressing portion 60 of the clamping member 5, and the axially outer portion is inserted into the inner side of the protruding support portion 76 in a manner that allows axial sliding (relative displacement). Therefore, the outer guide pin 77 is axially positioned between the outer body portion 13 and the pressing portion 60. Furthermore, the central axis of the outer guide pin 77 is arranged parallel to the central axis of the receiving portion 65.

[0246] <Actuator>

[0247] The electric actuator 12 constituting the floating brake mechanism 3 includes: an electric drive unit (MGU) 78 disposed on the axial inner side of the clamping base 61; and a rotary linear motion conversion mechanism 79 disposed on the inner side of the receiving portion 65.

[0248] The electric drive unit 78 includes a housing 80 and a speed reduction mechanism, such as an electric motor serving as a drive source and a gear reducer, which are respectively housed inside the housing 80. Furthermore, a rotating shaft 81, on which the final gear constituting the speed reduction mechanism is fixed, is inserted into the inside of a through hole 67 formed in the bottom 66 of the clamping base 61.

[0249] like Figure 3 and Figure 4As shown, the rotary-to-linear motion conversion mechanism 79 is a feed screw mechanism that converts rotary motion into linear motion and changes its total length in the axial direction during operation. It includes a main shaft 82, which is equivalent to the rotary component described in the claims, and a nut 83, which is equivalent to the linear motion component described in the claims.

[0250] The spindle 82 has an externally threaded portion 84 on its outer circumferential surface extending from the end portion (outer axial portion) to the middle portion. The spindle 82 has a flange portion 85 near its base end, with a larger diameter than the other portions. The base end portion (inner axial portion) of the spindle 82 is rotatably supported inside a through hole 67 formed in the bottom 66 of the clamping base 61, and is connected to the end portion of the rotating shaft 81 in a non-rotatable manner. Therefore, the spindle 82 can be driven to rotate by an electric motor.

[0251] The end portion of the main shaft 82 is inserted into the inner side of the combined piston 7 from the axial inner side. The central axis of the main shaft 82 is coaxial with the central axis of the receiving portion 65 (guide cylinder 21). A thrust bearing 86 is disposed between the axial inner side of the flange portion 85 and the axial outer side of the bottom 66. Thus, the axial load acting on the flange portion 85 can be supported by the bottom 66, and the flange portion 85 can be rotated relative to the bottom 66.

[0252] The nut 83 has an internal thread 87 on its inner circumferential surface, which engages with the external thread 84 of the main shaft 82. At the end (axially outer side) of the nut 83, there is an external spline 88 with a larger diameter than the other parts. Furthermore, when the nut 83 is positioned inside the small-diameter cylindrical portion 25 of the piston body 22, the external spline 88 engages with the internal spline 29 formed on the inner circumferential surface of the small-diameter cylindrical portion 25. Therefore, the nut 83 engages with the shared piston 7 in a manner that allows for axial relative displacement but not relative rotation. Thus, by rotating the main shaft 82, the nut 83 can be moved axially. Specifically, when the main shaft 82 is driven to rotate in the forward direction, the nut 83 moves toward the rotor 9, pressing the piston body 22 axially; conversely, when the main shaft 82 is driven to rotate in the reverse direction, the nut 83 moves toward the reverse rotor 9.

[0253] [Instructions for the Operation of Disc Brakes]

[0254] When the service brake is activated by the disc brake device 1 in this example, brake fluid is supplied to the hydraulic chambers 28 and 50 of all cylinders 10a, 10b, 11a, and 11b of the brake caliper 4 via oil passages 18a and 18b. This pushes all pistons 7 and 8 (one dual-use piston 7 and three dedicated service pistons 8) out of cylinders 10a, 10b, 11a, and 11b, pressing a pair of bushings 6a and 6b against the axial sides of the rotor 9. As a result, the rotor 9 is forcefully pressed from both axial sides, thus applying braking force. In this way, the disc brake device 1 obtains braking force based on the service brake by introducing brake fluid and pushing out all pistons 7 and 8.

[0255] When the parking brake is actuated by the disc brake device 1, the electric motor constituting the electric drive device 78 is energized, driving the main shaft 82 constituting the rotary linear motion conversion mechanism 79 to rotate in the forward direction. At this time, the torque in the forward direction of rotation acts on the piston body 22 from the nut 83. Therefore, the piston body 22 tends to rotate relative to the piston cover 23 in the forward direction of rotation. However, since the piston seal 30a (30b) is held between the piston body 22 and the inner cylinder 11a on the rotating side, the rotation of the piston body 22 is restricted by the frictional force acting between the piston body 22 and the piston seal 30a (30b). Therefore, the nut 83 and the piston body 22 do not rotate, but the nut 83 moves axially outward relative to the inner body portion 14. Then, the end of the nut 83 is pressed against the axially inner side of the partition wall portion 26 of the combined piston 7, pushing the combined piston 7 toward the rotor 9, thereby pressing the inner liner block 6b against the axially inner side of the rotor 9.

[0256] Furthermore, the reaction force from the pressing action is transmitted from the main shaft 82 to the clamping member 5 via the thrust bearing 86. This causes the main shaft 82 and the clamping member 5 to move axially inward relative to the brake caliper 4. At this time, the guide cylinder 21 and the receiving portion 65 (first guide portion 69), the inner guide pin 75 and the support cylinder portion 68 (second guide portion 70), and the outer guide pin 77 and the protruding support portion 76 (third guide portion 71) slide axially. Then, the pressing portion 60 of the clamping member 5 presses the outer bushing 6a against the axially outer side of the rotor 9. This clamps the rotor 9 from both axial sides using a pair of bushings 6a and 6b, thus obtaining braking force. In this way, the disc brake device 1, by using the electric actuator 12 to push out the combined piston 7, moves the clamping member 5 axially inward relative to the brake caliper 4, thereby obtaining braking force based on the parking brake.

[0257] In contrast, when the parking brake is released, the electric motor constituting the electric drive unit 78 drives the main shaft 82 to rotate in the opposite direction. At this time, the torque in the opposite direction of rotation acts on the piston body 22 from the nut 83. Therefore, the piston body 22 tends to rotate relative to the piston cover 23 in the opposite direction of rotation. However, since the piston seal 30a (30b) is clamped between the piston body 22 and the inner cylinder 11a on the rotating side, the rotation of the piston body 22 can be limited by the frictional force acting between the piston body 22 and the piston seal 30a (30b) as long as the torque acting on the piston body 22 from the nut 83 is not too large as when the nut 83 and the main shaft 82 are locked. As a result, the nut 83 is displaced axially inward relative to the inner body portion 14. Furthermore, by displacing the main shaft 82 axially outward relative to the inner body portion 14, the clamping member 5 is displaced axially outward relative to the inner body portion 14. At this time, the guide cylinder 21 and the receiving part 65, the inner guide pin 75 and the support cylinder part 68, and the outer guide pin 77 and the protruding support part 76 slide axially.

[0258] The disc brake device 1 of this example, as described above, is a structure that can suppress the temperature rise of the brake fluid contained in the hydraulic chamber 28 of the inner cylinder 11a on the rotating side, and can stably obtain braking force based on the parking brake, and can eliminate the problems that occur when the nut 83 is fully released to the rotating side 9.

[0259] That is, in this example, the dual-use piston 7 is a two-part structure consisting of the piston body 22 and the piston cap 23. Therefore, even when the inner liner 6b is pressed against the rotating rotor 9 and becomes hot, in this example using the dual-use piston 7, the amount of heat transferred to the brake fluid contained in the hydraulic chamber 28 can be reduced compared to the case where the piston is a single-piece structure. Furthermore, by making the dual-use piston 7 a two-part structure, the hydraulic chamber 28 can also be moved away from the inner liner 6b. Therefore, the temperature rise of the brake fluid can be suppressed. As a result, brake fluid deterioration can be suppressed, and the occurrence of vapor lock can be suppressed.

[0260] As described above, when the braking force based on the parking brake is obtained, the main shaft 82 is driven to rotate in the forward rotation direction. The torque in the forward rotation direction acting on the piston body 22 from the nut 83 is supported by the frictional force between the piston body 22 and the piston seal 30a (30b). However, depending on the operating conditions of the disc brake device 1, the contact state between the piston body 22 and the piston seal 30a (30b) may become unstable, and there is a possibility that sufficient frictional force cannot be obtained through the piston seal 30a (30b). In such a case, if the piston body 22 rotates relative to the piston cover 23 in the forward rotation direction, it will be impossible to push the auxiliary piston 7 towards the rotor 9 side, making it difficult to obtain a stable braking force.

[0261] In the disc brake device 1 of this example, since a one-way rotation limiting part 40 is provided between the piston body 22, which constitutes the dual-purpose piston 7, and the piston cover 23, it is possible to prevent the piston body 22 and the piston cover 23 from rotating relative to each other even when sufficient friction cannot be obtained through the piston seal 30a (30b).

[0262] Specifically, such as Figure 11 (A) and Figure 12 As shown in (A), by bringing the right-angled surface of the body-side engaging portion 41 of the piston body 22, i.e., the body-side limiting surface 43, into contact with the right-angled surface of the cover-side engaging portion 42 of the piston cover 23, i.e., the cover-side limiting surface 45, the body-side engaging portion 41 and the cover-side engaging portion 42 can be mechanically engaged. Therefore, the relative rotation of the piston body 22 with respect to the piston cover 23 in the positive rotation direction can be restricted. Therefore, a stable braking force based on the parking brake can be obtained. Furthermore, in this example, the engaging protrusion 35 of the inner liner 6b engages with the engaging recess 34 of the piston cover 23, thereby preventing the piston cover 23 from rotating. Therefore, compared to the case where rotation is prevented by friction acting between the piston cover and the inner liner, rotation can be prevented more reliably, and a more stable braking force can be obtained.

[0263] Furthermore, when the drive shaft 82 is rotated in the opposite direction to release the braking force based on the parking brake, even if the nut 83 is completely released to the rotor 9 side until it comes into contact with the axial outer side of the flange portion 85 due to the electric motor malfunction, the durability of the electric motor and the reduction mechanism constituting the electric drive device 78 can be effectively prevented from decreasing.

[0264] That is, such as Figure 4 As shown by the dashed line, when the nut 83 is fully released towards the reverse rotor 9, the nut 83 and the main shaft 82 are locked, and the torque acting on the piston body 22 from the nut 83 increases sharply. If the torque acting on the piston body 22 becomes too large, the piston body 22 overcomes the frictional force acting between the piston body 22 and the piston seals 30a (30b) and attempts to rotate in the opposite direction. Furthermore, as... Figure 11 (B) and Figure 12As shown in (B), the inclined surface of the body-side engaging portion 41 of the piston body 22, i.e., the body-side guide surface 44, contacts the inclined surface of the cover-side engaging portion 42 of the piston cover 23, i.e., the cover-side guide surface 46. Here, the piston cover 23, which has the cover-side engaging portion 42, is held by the piston ring 38 in a manner that allows relative displacement with respect to the piston body 22 in the axial direction, and the axial displacement to the outside is limited by the rotor 9. Therefore, the cover-side guide surface 46 can push the body-side guide surface 44 axially upward (moving towards the rotor 9) by tilting. This allows relative rotation (displacement) of the piston body 22 relative to the piston cover 23 in the opposite rotation direction. As a result, it is possible to effectively prevent the electric motor constituting the electric drive device from reaching the stopping torque (maximum current). Therefore, it is possible to suppress the reduction in the durability of the electric motor. In addition, it is possible to prevent the torque acting on the reduction mechanism such as the gear reducer from becoming too large, and therefore it is also possible to suppress the reduction in the durability of the reduction mechanism.

[0265] Furthermore, in this example, by an amount corresponding to the body-side engagement portion 41 overtaking the cover-side engagement portion 42, a relatively large axial clearance (loosening) between the piston ring 38 and the retaining groove 39 is ensured. Therefore, the piston body 22 relative to the piston cap 23 allows not only a few degrees of relative rotation (displacement) caused by the body-side engagement portion 41 leaping over the cover-side engagement portion 42, but also full rotation. Thus, damage to the electric motor and the reduction gear mechanism can be effectively prevented.

[0266] Furthermore, even when the nut 83 is fully released towards the reverse rotor 9 and the nut 83 and spindle 82 are locked, the piston body 22 can still rotate relative to the piston cover 23 in the opposite direction of rotation. Therefore, torque can be prevented from acting on the piston guard 36 mounted between the piston cover 23 and the opening edge of the inner cylinder 11a on the rotating side. This also prevents damage to the piston guard 36.

[0267] [Second example of implementation]

[0268] use Figures 13-16 A second example of the implementation will be described. In this example, the same components as in the first example of the implementation are labeled with the same symbols as in the first example of the implementation, and detailed descriptions are omitted.

[0269] The disc brake device 1a in this example is the same as the first example of the embodiment. It is an electric parking brake type disc brake device, which has the functions of both a hydraulic service brake and an electric parking brake.

[0270] The disc brake device 1a includes a support 89, a brake caliper 4a, a pair of pads 6c and 6d (outer pad 6c and inner pad 6d), a piston 90, and an electric actuator 12.

[0271] Support member 89 is a casting of ferrous alloy such as cast iron, and includes: a support base 91, which is disposed on rotor 9 (see reference). Figure 15 The support base 91 has an axial inner side; an outer connecting portion 92 disposed on the axial outer side of the rotor 9; and a pair of connecting arms 93, which axially connect the circumferential ends of the support base 91 and the circumferential ends of the outer connecting portion 92. The support member 89 is fixed to the suspension device by means of a pair of mounting holes 94 formed on the radial inner side of the support base 91. A guide hole (not shown) opening axially inward is formed on the radial outer side (rotor passage portion) of the connecting arm 93.

[0272] The outer liner 6c is disposed on the axially outer side of the rotor 9 and is supported so as to be axially displaceable relative to the support member 89. Furthermore, the inner liner 6d is disposed on the axially inner side of the rotor 9 and is supported so as to be axially displaceable relative to the support member 89.

[0273] The brake caliper 4a is made of aluminum alloy or iron alloy and has an inverted U-shape. The brake caliper 4a has two strand-shaped pressing parts 60a on the outer axial side and a clamping base 61a on the inner axial side. In addition, the brake caliper 4a has a bridge part 62a, which is disposed on the outer radial side of the rotor 9 and connects the pressing parts 60a and the clamping base 61a axially.

[0274] The clamping base 61a includes a base body 63a and a pair of arms 64a extending circumferentially from the base body 63a to both sides. The base body 63a has a cylinder 95 inside, which is a generally cylindrical space. The cylinder 95 has an opening on the outer side in the axial direction, but the opening on the inner side in the axial direction is blocked by a bottom 66a.

[0275] The brake caliper 4a, as described above, is supported so that it can be displaced axially relative to the support member 89. Therefore, the axially inner ends of the guide pins 96 are fixed to a pair of arms 64a constituting the clamping base 61a, and the axially inner ends to the middle portion of the guide pins 96 are inserted into the guide holes formed in the pair of connecting arms 93 constituting the support member 89 in a manner that allows for relative axial displacement. Furthermore, a protective cover 97 is provided between the outer peripheral surface of the guide pins 96 and the opening of the guide holes.

[0276] The piston 90 has a split structure that is divided into two parts in the axial direction. The piston 90 consists of a piston body 22a and a piston cap 23a.

[0277] The piston body 22a is made of a metal such as carbon steel and is configured as a bottomed cylindrical shape, fitted and mounted on the cylinder 95. The piston body 22a has a generally circular plate-shaped partition portion 26a. The partition portion 26a is disposed at the axial middle portion of the piston body 22a, separating the interior of the piston body 22a axially. An internal spline 29a is provided on the inner circumferential surface of the piston body 22a at a position axially inner than the partition portion 26a.

[0278] The portion between the piston body 22a and the cylinder 95 is sealed by an annular piston seal 30c. The piston seal 30c is installed in a sealing groove 31c formed on the inner circumferential surface of the axially outer portion of the cylinder 95.

[0279] The piston cap 23a is made of, for example, stainless steel, titanium, or synthetic resin, and is composed of a cylindrical portion 32a and a closed plate portion 33a, forming a bottomed cylindrical shape. The axially inner portion of the cylindrical portion 32a of the piston cap 23a is disposed inside the piston body 22a, and the axially outer portion of the cylindrical portion 32a is anti-rotating relative to the inner liner block 6d. A piston shield 36a is provided between the cylindrical portion 32a of the piston cap 23a and the axially outer opening edge of the cylinder body 95.

[0280] In the cylindrical portion 32a of the piston cap 23a, a piston ring 38a is externally fitted into the portion disposed on the inner side of the piston body 22a. The piston ring 38a has a circular cross-sectional shape, and its radially outer portion engages with a generally rectangular retaining groove 39a provided on the inner circumferential surface of the axially outer portion of the piston body 22a in a manner that allows it to be displaced axially.

[0281] In this example, the piston body 22a and the piston cap 23a are also connected via a unidirectional rotation limiting part 40 having the same structure as the first example of the above embodiment. Therefore, on the axial outer side of the partition wall 26a of the piston body 22a, body-side engaging parts 41 with convex shapes are arranged at equal intervals in the circumferential direction (see reference). Figure 7 (etc.), on the end face of the cylindrical portion 32a of the piston cover 23a, cover-side engaging portions 42 having convex shapes are arranged at equal intervals in the circumferential direction (see reference). Figure 9 wait).

[0282] Similar to the structure in the first embodiment, between the piston body 22 and the piston cap 23, in addition to the unidirectional rotation limiting part 40, an axial force transmission part 47 for transmitting axial force between the piston body 22a and the piston cap 23a is also provided. Therefore, an annular body-side transmission surface 48 is provided on the axially outer side of the partition wall portion 26a of the piston body 22a at a position radially outer than the body-side engaging part 41, and an annular cap-side transmission surface 49 is provided on the axially inner end face of the cylindrical portion 32a of the piston cap 23a at a position radially outer than the cap-side engaging part 42.

[0283] The electric actuator 12 has the same structure as in the first embodiment, including an electric drive device 78 disposed axially inside the clamping base 61a and a rotary linear motion conversion mechanism 79 disposed within the cylinder 95. Furthermore, the rotating shaft 81 constituting the electric drive device 78 is inserted into the inside of a through hole 67a formed in the bottom 66a of the clamping base 61a, and the base end of the main shaft 82 constituting the rotary linear motion conversion mechanism 79 is connected to the end of the rotating shaft 81 in a manner that prevents relative rotation.

[0284] The nut 83, which is screwed into the end to the middle of the main shaft 82, engages with the external spline 88 formed on the outer peripheral surface and the internal spline 29a formed on the inner peripheral surface of the piston 90. Thus, the nut 83 is positioned inside the piston 90 such that it can be axially displaced but cannot rotate relative to it.

[0285] To obtain braking force based on the service brake using the disc brake device 1a in this example, brake fluid is supplied to the hydraulic chamber 98 of the cylinder 95 of the brake caliper 4a via an oil passage (not shown). This pushes the piston 90 out of the cylinder 95, pressing the inner liner 6d against the axially inward side of the rotor 9. Furthermore, the reaction force from the pressing is transmitted from the main shaft 82 to the brake caliper 4a via the thrust bearing 86. This causes the brake caliper 4a to displace axially inward relative to the support member 89. Then, the pressing part 60a of the brake caliper 4a presses the outer liner 6c against the axially outward side of the rotor 9. As a result, the rotor 9 is forcefully pressed from both axial sides, thus achieving braking. In this way, the disc brake device 1a obtains braking force based on the service brake by introducing brake fluid and pushing out the piston 90.

[0286] In contrast, to obtain parking brake-based braking force using the disc brake device 1a in this example, similar to the structure in the first embodiment, the electric motor constituting the electric drive device 78 is energized, driving the main shaft 82 to rotate in the forward direction. This causes the nut 83 to displace axially outward relative to the support member 89. Then, the end of the nut 83 is pressed against the axially inner side of the partition wall 26a of the piston body 22a, pushing the piston 90 toward the rotor 9, thereby pressing the inner liner 6d against the axially inner side of the rotor 9. Furthermore, the reaction force from the pressing is transmitted from the main shaft 82 to the brake caliper 4a via the thrust bearing 86. This causes the brake caliper 4a to displace axially inward relative to the support member 89. Then, the pressing portion 60a of the brake caliper 4a presses the outer liner 6c against the axially outer side of the rotor 9. As a result, the rotor 9 is clamped from both axial sides, obtaining braking force. In this way, the disc brake device 1a uses an electric actuator 12 to push out the piston 90, causing the brake caliper 4a to move axially inward relative to the support member 89, thereby obtaining the braking force based on the parking brake.

[0287] In this example, in particular, because a one-way rotation limiting part 40 is provided between the piston body 22a and the piston cover 23a, even if sufficient frictional force cannot be obtained through the piston seal 30c, it is possible to prevent the piston body 22a from rotating relative to the piston cover 23a in the positive rotation direction. Therefore, a stable braking force based on the parking brake can be obtained.

[0288] To release the parking brake, the main shaft 82 is driven to rotate in the opposite direction. This causes the nut 83 to displace axially inward relative to the support member 89. Furthermore, by displacing the main shaft 82 axially outward relative to the support member 89, the brake caliper 4a is displaced axially outward relative to the support member 89. At this time, the outer peripheral surfaces of the pair of guide pins 96 and the inner peripheral surfaces of the pair of guide holes slide axially. Particularly in this example, because a one-way rotation limiting part 40 is provided between the piston body 22a and the piston cover 23a, even if the nut 83 is completely released towards the reverse rotor 9 due to a malfunction of the electric motor, the piston body 22a can still rotate relative to the piston cover 23a in the opposite direction. Therefore, it is possible to effectively prevent a decrease in the durability of the electric motor and reduction mechanism constituting the electric drive device 78.

[0289] In the case of the disc brake device 1a in this example as described above, the piston 90 is also set as a two-part structure of piston body 22a and piston cover 23a, and these piston body 22a and piston cover 23a are connected via a one-way rotation limiting part 40. Therefore, the temperature rise of brake fluid can be suppressed, the braking force based on the parking brake can be stably obtained, and the problem that occurs when the nut 83 is completely released to the rotor 9 side can be solved.

[0290] The other structures and effects are the same as in the first example of the implementation method.

[0291] [Third example of implementation]

[0292] use Figures 17-18 A third example of the implementation will be described. In this example, the same components as in the first example of the implementation are labeled with the same symbols as in the first example of the implementation, and detailed descriptions are omitted.

[0293] This example is a variation of the first embodiment, modifying the structure of the first embodiment to construct a dual-purpose piston 7 (see reference). Figure 6 The structure of the piston body 22b and piston cover 23b having a one-way rotation restriction part 40a.

[0294] In this example, the unidirectional rotation limiting part 40a not only limits the forward rotation of the piston body 22b relative to the piston cover 23b, but also... Figure 17 and Figure 18 The relative rotation (in the X direction of the arrow) and allow rotation in the opposite direction ( Figure 17 and Figure 18 It has the function of relative rotation (in the direction of arrow Y), and also has the function of transmitting axial force between piston body 22b and piston cover 23b.

[0295] The unidirectional rotation limiting part 40a includes: a main body side sliding contact surface 99, which is disposed on the axially outer side of the partition portion 26b constituting the piston main body 22b; and a cover side sliding contact surface 100, which is disposed on the end face of the axially inner side of the cylindrical portion 32b constituting the piston cover 23b. The main body side sliding contact surface 99 and the cover side sliding contact surface 100 are axially opposed to each other.

[0296] like Figure 17 As shown, the main body-side sliding contact surface 99 is configured as a flat surface and is disposed on an imaginary plane orthogonal to the central axis of the piston body 22b. The main body-side sliding contact surface 99 has an annular shape and is surface-machined to increase the coefficient of friction between the main body-side sliding contact surface 99 and the cover-side sliding contact surface 100. Specifically, the main body-side sliding contact surface 99 is roughened, meaning its surface roughness is greater than that of other parts of the partition wall portion 26b.

[0297] like Figure 18 As shown, the cover-side sliding contact surface 100 is configured as a flat surface and is disposed on an imaginary plane orthogonal to the central axis of the piston cover 23b. The cover-side sliding contact surface 100 has an annular shape and is composed of friction components to increase the coefficient of friction between the main body-side sliding contact surface 99 and the cover-side sliding contact surface 100. Specifically, the cover-side sliding contact surface 100 is made of an elastic material such as rubber.

[0298] In this example, the disc brake device equipped with a one-way rotation limiting part 40a rotates the drive shaft 82 in the forward rotation direction to obtain braking force based on the parking brake (see reference). Figure 3 When (etc.), the structure is the same as in the first example of the embodiment, such that nut 83 (refer to) Figure 3 Move the nut 83 axially outward, pressing the end of the nut 83 against the axially inner side of the partition wall 26b of the piston body 22b. Then, move the dual-use piston 7 toward the rotor 9 (refer to...). Figure 2 ) will be launched, with the inner liner block 6b (refer to) Figure 3 (etc.) press against the axial inner side of the rotor 9. Furthermore, the reaction force accompanying the pressing is transmitted from the main shaft 82 to the clamping member 5 (see reference). Figure 3 (etc.). This causes the spindle 82 and clamping member 5 to be positioned relative to the brake caliper 4 (see reference). Figure 3The rotor 9 is then displaced axially inward. Then, the clamping member 5 presses the outer bushing 6a against the axially outer side of the rotor 9. Thus, the rotor 9 is clamped from both axial sides by a pair of bushings 6a and 6b, generating braking force.

[0299] In particular, in this example, because a one-way rotation limiting part 40a is provided between the piston body 22b and the piston cap 23b, even if the piston seal 30a (see reference) cannot be passed through, Figure 3 With sufficient friction, the piston body 22b can be prevented from rotating relative to the piston cap 23b in the forward rotation direction. Specifically, by clamping the rotor 9 from both axial sides by a pair of bushings 6a and 6b, the axial force acting from the body-side sliding contact surface 99 on the cap-side sliding contact surface 100 is increased. Consequently, the body-side sliding contact surface 99 and the cap-side sliding contact surface 100 are frictionally engaged in a manner that prevents relative rotation. Therefore, the piston body 22b can be prevented from rotating relative to the piston cap 23b in the forward rotation direction, and the braking force based on the parking brake can be stably obtained.

[0300] To release the braking force based on the parking brake, when the drive shaft 82 is rotated in the reverse direction, if the nut 83 is completely released to the reverse side due to a malfunction of the motor, the end of the nut 83 separates from the axial inner side of the partition wall 26b that serves as the piston 7, or the force of the end of the nut 83 pressing against the partition wall 26b is reduced. As a result, the axial force acting on the cover-side sliding contact surface 100 from the main body-side sliding contact surface 99 is reduced, thus allowing the main body-side sliding contact surface 99 to rotate relative to the cover-side sliding contact surface 100 in the reverse direction. Therefore, it is possible to allow the piston body 22b to rotate relative to the piston cover 23b in the reverse direction. Therefore, it is possible to effectively prevent a decrease in the durability of the electric motor or reduction mechanism.

[0301] In the case of the disc brake device described above, the piston 7 is also configured as a two-part structure consisting of a piston body 22b and a piston cover 23b, and these piston bodies 22b and piston covers 23b are connected via a one-way rotation limiting part 40a having the aforementioned function. Therefore, it is possible to suppress the temperature rise of the brake fluid, obtain stable braking force based on the parking brake, and solve the problems that arise when the nut 83 is fully released towards the reverse rotor 9. Furthermore, since no separate power transmission part is required, it is advantageous to achieve miniaturization and weight reduction of the piston body 22b and piston cover 23b.

[0302] The other structures and effects are the same as in the first example of the implementation method.

[0303] [Fourth example of implementation]

[0304] use Figure 19 The fourth example of the implementation will be described. In this example, the same components as in the first example of the implementation are labeled with the same symbols as in the first example of the implementation, and detailed descriptions are omitted.

[0305] This example is a variation of the first embodiment, only changing the structure of the first embodiment to construct a dual-purpose piston 7 (see reference). Figure 6 The structure of piston cap 23c (etc.).

[0306] The piston cap 23c is composed of a cap body 101 made of synthetic resin and a plurality of metal engaging tabs 102. The cap body 101 has a cylindrical portion 32c and a closing plate portion 33b. The engaging tabs 102 are composed of a generally cylindrical base 103 and a generally triangular prism-shaped cap-side engaging portion 42a. The base 103 is molded and fixed to the axially inner side of the cylindrical portion 32c constituting the cap body 101. The cap-side engaging portion 42a has the same structure as in the first embodiment, having a cap-side limiting surface 45a that is perpendicular to the end face of the axially inner side of the cylindrical portion 32c, and an inclined surface, namely a cap-side guiding surface 46a, that is inclined relative to the end face of the axially inner side of the cylindrical portion 32c.

[0307] In this example with the structure described above, since most of the piston cover 23c is made of synthetic resin, the amount of fluid entering the hydraulic chamber 28 (see reference 23c) can be reduced compared to the case where the piston cover is made of metal. Figure 3 The amount of heat transfer of the brake fluid contained in the cover is reduced. Therefore, the temperature rise of the brake fluid can be effectively suppressed. Furthermore, since the cover-side engaging portion 42a is made of metal, the amount of wear and deformation of the cover-side engaging portion 42a can be suppressed compared to the case where it is made of synthetic resin.

[0308] The other structures and effects are the same as in the first example of the implementation method.

[0309] Furthermore, in implementing the present invention, as a variation of the fourth embodiment, the engaging piece can also be constructed from a metal pin that is cylindrical in shape, with the base half of the pin molded and fixed to the cover body, so that the front half of the pin functions as a cover-side engaging portion. In this case, the cover-side engaging portion formed by the front half of the pin and the cover-side engaging portion 42c of the seventh embodiment described later (see reference) Figure 22 Similarly, in the forward rotation direction, the rear side has a cover-side limiting surface but no cover-side guiding surface, and in the reverse rotation direction, there is a corner (including a chamfer) between the rear side and the axial end surface.

[0310] [Fifth example of an implementation method]

[0311] use Figure 20The fifth example of the implementation will be described. In this example, the same components as in the first example of the implementation are labeled with the same symbols as in the first example of the implementation, and detailed descriptions are omitted.

[0312] This example is a variation of the first and fourth examples of the implementation method, with the structure of the piston cover 23d changed based on the structure of the first example of the implementation method.

[0313] The piston cap 23d has the following structure: In the fourth embodiment of the piston cap 23c (refer to...) Figure 19 It also includes a metal axial force transmission component 104. The axial force transmission component 104 has a generally cylindrical shape and is molded and fixed to the cylindrical portion 32c constituting the cover body 101. The axially inner end face of the axial force transmission component 104 is exposed on the axially inner end face of the cylindrical portion 32c, and this exposed end face serves as the cover-side transmission surface 49a. In addition, the axially outer end face of the axial force transmission component 104 is also exposed on the axially outer end face of the cylindrical portion 32c. The axially inner portion of the axial force transmission component 104 is exposed on the outer peripheral surface of the cylindrical portion 32c, and this portion has a retaining groove 39a. The axially outer portion of the axial force transmission component 104 is molded inside the cylindrical portion 32c. In this example, the axial force transmission component 104 is separate from the plurality of engaging tabs 102, but it is also possible to integrally construct the power transmission component with the plurality of engaging tabs or fix them together.

[0314] In this example with the structure described above, a metal axial force transmission member 104 is provided inside the synthetic resin cap body 101, so that the axial force acting on the piston cap 23d can be transmitted via the axial force transmission member 104. Therefore, the strength and durability of the piston cap 23d can be improved.

[0315] The other structures and effects are the same as in the first and fourth examples of the implementation.

[0316] [Sixth Example of Implementation]

[0317] use Figure 21 The sixth example of the implementation will be described. In this example, the same components as in the first example of the implementation are labeled with the same symbols as in the first example of the implementation, and detailed descriptions are omitted.

[0318] This example is a variation of the first embodiment, modifying the structure of the cover-side engaging portion 42b based on the structure of the first embodiment.

[0319] The piston cover 23e has a plurality of cover-side engaging portions 42b on the axially inner end face of the cylindrical portion 32d. Each cover-side engaging portion 42b has a concave shape that is recessed in the axial direction, and a plurality of them are provided at equal intervals in the circumferential direction on the axially inner end face of the cylindrical portion 32d. The plurality of cover-side engaging portions 42b are arranged on a concentric circle centered on the central axis of the piston cover 23e.

[0320] The cover-side engaging portions 42b each have a recessed, generally triangular prism shape, and their axial depth, extending from the axially inner end face of the cylindrical portion 32d, varies in the circumferential direction. Specifically, the cover-side engaging portions 42b each have a shape that, in the positive rotation direction ( Figure 21 (The arrow in the X direction) starts from the back and moves towards the front (in the opposite direction of rotation) Figure 21 The shape gradually increases in axial depth from front to rear (in the direction of arrow Y). Therefore, the axial depth of the cover-side engaging portion 42b is deepest at the front end in the positive rotation direction and shallowest at the rear end in the positive rotation direction.

[0321] Each of the cover-side engaging portions 42b has a cover-side limiting surface 45b on its front side in the forward rotation direction. The cover-side limiting surface 45b is configured as a flat surface and is arranged parallel to the central axis of the piston cover 23e. That is, the cover-side limiting surface 45b is a right-angled surface perpendicular to the axially inner end face of the cylindrical portion 32d. In this example, the cover-side limiting surface 45b is arranged on an imaginary plane containing the central axis of the piston cover 23e. The drive shaft 82 (refer to...) rotates in the forward rotation direction. Figure 3 When (etc.), the cover side limiting surface 45b contacts the main body side limiting surface 43 of the main body side engaging part 41.

[0322] Each cover-side engaging portion 42b has a cover-side guide surface 46b on its axial bottom surface. The cover-side guide surface 46b is a flat surface that is inclined in a straight line from the rear towards the front and away from the rotor 9 in the reverse rotation direction. That is, the cover-side guide surface 46b is an inclined surface inclined relative to the axially inner end face of the cylindrical portion 32d. When the main shaft 82 is rotated in the reverse rotation direction, the cover-side guide surface 46b contacts the main body-side guide surface 44 of the main body-side engaging portion 41. The cover-side guide surface 46b and the cover-side limiting surface 45b are connected via a chamfered portion.

[0323] In this example with the structure described above, when the drive spindle 82 rotates in the positive rotation direction, as... Figure 21As shown in (A), each main body side limiting surface 43, which is a right angle, and each cover side limiting surface 45b, which is also a right angle, simultaneously make surface contact, and the main body side engaging portion 41 and the cover side engaging portion 42b mechanically engage. Therefore, when the main drive shaft 82 is rotated in the forward rotation direction, the piston body 22 is restricted to rotate relative to the piston cover 23e in the forward rotation direction.

[0324] In contrast, when the drive spindle 82 rotates in the opposite direction, as... Figure 21 As shown in (B), each body-side guide surface 44, which is an inclined surface, simultaneously contacts each cover-side guide surface 46b, which is also an inclined surface. Therefore, the cover-side guide surface 46b can use its inclination to push the body-side guide surface 44 axially upward (move towards the reverse rotor 9). This allows the piston body 22 to rotate (displace) relative to the piston cover 23e in the opposite rotation direction.

[0325] In this example with the structure described above, the main body side engaging portion 41 can be positioned inside the cover side engaging portion 42b, which is beneficial for shortening the axial dimension of the dual-use piston 7.

[0326] The other structures and effects are the same as in the first example of the implementation method.

[0327] Furthermore, in implementing the present invention, as a sixth variation of the embodiment, the main body side engaging parts may be respectively configured as concave shapes that are recessed in the axial direction, and the cover side engaging parts may be respectively configured as convex shapes that protrude in the axial direction.

[0328] [Seventh Example of Implementation]

[0329] use Figure 22 The seventh example of the implementation will be described. In this example, the same components as in the first example of the implementation are labeled with the same symbols as in the first example of the implementation, and detailed descriptions are omitted.

[0330] This example is a variation of the first embodiment, modifying the structure of the main body side engaging portion 41b and the cover side engaging portion 42c based on the structure of the first embodiment.

[0331] Each of the main body side engaging portions 41b has a roughly fan-shaped shape when viewed axially, and a roughly quarter-circle shape when viewed radially. Therefore, the axial height of each of the main body side engaging portions 41b from the partition wall portion 26c varies in the circumferential direction.

[0332] The main body side engaging portion 41b has a main body side limiting surface 43a on the front side in the forward rotation direction and a main body side guiding surface 44b on the axial end surface. The main body side guiding surface 44b is a curved surface (partially cylindrical surface) that is curved from the front towards the rear and closer to the rotor 9 in the reverse rotation direction.

[0333] The cover-side engaging portions 42c each have a generally cuboid shape, which is approximately fan-shaped when viewed axially and rectangular when viewed radially. Therefore, the axial height of each cover-side engaging portion 42c from the end face of the axially inner side of the cylindrical portion 32e is constant in the circumferential direction.

[0334] The cover-side engaging portion 42c has a cover-side limiting surface 45c on its rear side in the forward rotation direction. In this example, the axial end face of the cover-side engaging portion 42c is a flat surface parallel to the axial inner end face of the cylindrical portion 32e, and does not have a cover-side guiding surface. The cover-side engaging portion 42c has a corner portion (including a chamfered portion) 105 between its rear side side in the reverse rotation direction and its axial end face.

[0335] In this example with the structure described above, the main drive spindle 82 (see reference) rotates in the forward rotation direction. Figure 3 (etc.) such as Figure 22 As shown in (A), each main body-side limiting surface 43a and each cover-side limiting surface 45c simultaneously make surface contact, and the main body-side engaging portion 41b and the cover-side engaging portion 42c mechanically engage. Therefore, when the main drive shaft 82 is rotated in the forward rotation direction, the relative rotation of the piston body 22 with respect to the piston cover 23 in the forward rotation direction is restricted.

[0336] In contrast, when the drive spindle 82 rotates in the opposite direction, as... Figure 22 As shown in (B), each of the body-side guide surfaces 44b, which are curved surfaces, of the body-side engaging portion 41b simultaneously contacts each of the corner portions 105 of the cover-side engaging portion 42c. Therefore, the corner portions 105 can use the curved surfaces of the body-side guide surfaces 44b to push the body-side guide surfaces 44b axially upward (move towards the reverse rotor 9). This allows the piston body 22 to rotate (displace) relative to the piston cover 23 in the opposite rotation direction.

[0337] In this example with the structure described above, the structure of the cover-side engaging portion 42c can be simplified, thereby reducing the manufacturing cost of the piston cover 23.

[0338] The other structures and effects are the same as in the first example of the implementation method.

[0339] Furthermore, in implementing the present invention, the first example of a seventh variation of the embodiment can be formed as follows: the main body side engaging portions are respectively provided with corners instead of the main body side guide surface, and the cover side engaging portions are respectively provided with cover side guide surfaces that are curved surfaces. Furthermore, as a second variation, a structure can also be adopted in which either the main body side engaging portion or the cover side engaging portion is provided with corners, and the other is provided with an inclined surface as a guide surface. Furthermore, as a third variation, a structure can also be adopted in which either the main body side engaging portion or the cover side engaging portion is provided with a curved guide surface, and the other is provided with an inclined guide surface.

[0340] The embodiments of the present invention have been described above, but the present invention is not limited thereto, and appropriate modifications can be made without departing from the inventive concept. Furthermore, the structures of the various embodiments can be appropriately combined for implementation as long as they do not create contradictions.

[0341] The present invention is not limited to the embodiments. For example, the shape and number of the convex or concave main body side engaging part and cover side engaging part constituting the unidirectional rotation limiting part, as well as the surface characteristics of the main body side sliding contact surface and cover side sliding contact surface constituting the unidirectional rotation limiting part, and the type of friction component can be appropriately changed.

[0342] Hereinafter, the features of the embodiments of the disc brake device according to the present invention described above will be briefly summarized and listed. [1]

[0344] A disc brake device (1, 1a) comprising:

[0345] Liner blocks (6b, 6a);

[0346] Brake caliper (4), having a cylinder (11a) with an opening on the side of the liner;

[0347] Piston (7), which is fitted into the cylinder body, presses the liner toward the rotor; and

[0348] A rotary-to-linear motion conversion mechanism (79) pushes the piston toward the rotor by converting the rotary motion of the drive source into linear motion.

[0349] Braking force based on the service brake is generated by supplying brake fluid into the cylinder, and braking force based on the parking brake is generated by activating the rotary linear motion conversion mechanism.

[0350] The piston comprises a piston body (22, 22a, 22b) and a piston cap (23, 23a, 23b, 23c, 23d) that are axially divided into two parts.

[0351] The rotary-linear motion conversion mechanism (79) includes: a rotating component (main shaft 82) that is rotaryly driven by the drive source; and a linear motion component (nut 83) that is screwed onto the rotating component and disposed inside the piston body, engaging with the piston body in a non-rotatable manner, and pressing the piston body axially.

[0352] A one-way rotation limiting part (40, 40a) is provided between the piston body and the piston cover. When the rotating component is driven to rotate in the forward rotation direction in order to move the linear motion component toward the rotor side, the one-way rotation limiting part restricts the relative rotation of the piston body with respect to the piston cover in the forward rotation direction. When the rotating component is driven to rotate in the reverse rotation direction in order to move the linear motion component toward the reverse rotation side, the one-way rotation limiting part allows the relative rotation of the piston body with respect to the piston cover in the reverse rotation direction. [2]

[0354] According to the disc brake device (1, 1a) described above [1], wherein,

[0355] The unidirectional rotation limiting part includes: at least one convex or concave body-side engaging part (41, 41b) disposed on the piston body; and at least one convex or concave cover-side engaging part (42, 42a, 42b, 42c) disposed on the piston cover, which mechanically engages with the body-side engaging part when the rotating component is driven to rotate in the positive rotation direction. [3]

[0357] According to the disc brake device (1, 1a) described above [2], wherein,

[0358] At least one of the portion of the main body-side engaging portion that contacts the cover-side engaging portion when the rotating component is driven to rotate in the positive rotation direction and the portion of the cover-side engaging portion that contacts the main body-side engaging portion when the rotating component is driven to rotate in the positive rotation direction has a limiting surface (main body-side limiting surface 43, 43a, cover-side limiting surface 45, 45a, 45b, 45c) parallel to the central axis of the piston. [4]

[0360] According to the disc brake device (1, 1a) described in [2] or [3] above, wherein,

[0361] The portion of the main body side engaging part that contacts the cover side engaging part when the rotating component is driven to rotate in the opposite direction has a main body side guide surface (44). The main body side guide surface (44) is more rearward in the opposite rotation direction and closer to the rotor in the axial direction.

[0362] When the rotating component is driven to rotate in the opposite direction, the main body side guide surface is pushed up by the cover-side engaging portion. [5]

[0364] According to the disc brake device (1, 1a) described above [4], wherein,

[0365] The main body side guide surface (44) is an inclined surface or a curved surface. [6]

[0367] According to any one of the disc brake devices (1, 1a) described in [2] to [5] above, wherein,

[0368] When the cover-side engaging portion rotates to drive the rotating component in the opposite rotation direction, the portion that contacts the main body-side engaging portion has cover-side guide surfaces (46, 46a, 46b). These cover-side guide surfaces are more forward-facing in the opposite rotation direction and further away from the rotor axially.

[0369] When the rotating component is driven to rotate in the opposite direction, the main body side engaging portion is pushed up by the cover side guide surface. [7]

[0371] According to the disc brake device (1, 1a) described above [6], wherein,

[0372] The cover-side guide surfaces (46, 46a, 46b) are inclined or curved surfaces. [8]

[0374] According to any one of the disc brake devices (1, 1a) described in [2] to [7] above, wherein,

[0375] At least the cover-side engaging portions (42, 42a, 42b, 42c) in the piston cover are made of metal. [9]

[0377] According to any one of the disc brake devices (1, 1a) described in [2] to [8] above, wherein,

[0378] The main body side engaging portions (41, 41b) are provided in multiple circumferential directions.

[0379] The cover-side engaging portions (42, 42a, 42b, 42c) are provided in multiple circumferential directions.

[10]

[0381] According to the disc brake device (1, 1a) described above [9], wherein,

[0382] The plurality of the main body side engaging portions (41, 41b) are arranged at equal intervals in the circumferential direction.

[0383] The plurality of the cover-side engaging portions (42, 42a, 42b, 42c) are arranged at equal intervals in the circumferential direction.

[11]

[0385] According to any one of the disc brake devices (1, 1a) described in [2] to

[10] above, wherein,

[0386] The piston caps (23, 23a, 23b, 23c, 23d) are supported so that they can be axially displaced relative to the piston body.

[12]

[0388] According to the disc brake device (1, 1a) described above

[11] , wherein,

[0389] The piston caps (23, 23a, 23b, 23c, 23d) are supported so that they can be axially displaced relative to the piston body by an amount corresponding to the amount by which at least the body-side engagement portion can pass over the cap-side engagement portion when the rotating component is driven to rotate in the opposite direction of rotation.

[13]

[0391] According to any one of the disc brake devices (1, 1a) described in [1] to

[12] above, wherein,

[0392] Between the piston body and the piston cover, there is also an axial force transmission part (47) that transmits axial force between the piston body and the piston cover.

[0393] The axial force transmission part is disposed separately from the unidirectional rotation restriction part.

[14]

[0395] According to the disc brake device (1, 1a) described above

[13] , wherein,

[0396] The axial force transmission part includes: a flat body-side transmission surface (48) located on an imaginary plane in the piston body orthogonal to the central axis of the piston body; and a flat cover-side transmission surface (49, 49a) located on an imaginary plane in the piston cover orthogonal to the central axis of the piston cover.

[15]

[0398] According to the disc brake device (1a) described above [1], wherein,

[0399] The unidirectional rotation limiting part (40a) also functions to transmit axial force between the piston body and the piston cover.

[16]

[0401] According to the disc brake device (1a) described above

[15] , wherein,

[0402] The unidirectional rotation limiting part (40a) includes: a main body-side sliding contact surface (99) disposed on the piston body; and a cover-side sliding contact surface (100) disposed on the piston cover and axially opposite to the main body-side sliding contact surface.

[0403] At least one of the body-side sliding contact surface and the cover-side sliding contact surface has been subjected to a surface finish that increases the coefficient of friction between the body-side sliding contact surface and the cover-side sliding contact surface, or at least one of the body-side sliding contact surface and the cover-side sliding contact surface is composed of a friction component.

[0404] When the rotating component is driven to rotate in the forward rotation direction, as the axial force acting on the cover-side sliding contact surface from the main body side sliding contact surface increases, the main body side sliding contact surface and the cover-side sliding contact surface engage in a frictional manner in which they cannot rotate relative to each other. When the rotating component is driven to rotate in the reverse rotation direction, as the axial force acting on the cover-side sliding contact surface from the main body side sliding contact surface decreases, the main body side sliding contact surface rotates relative to the cover-side sliding contact surface in the reverse rotation direction.

[17]

[0406] According to any one of the disc brake devices (1a) described in [1] to

[16] above, wherein,

[0407] It also includes the drive source, which is an electric motor.

[0408] Furthermore, this application is based on Japanese Patent Application No. 2020-125242, filed on July 22, 2020, the contents of which are incorporated herein by reference.

[0409] Industrial utilization potential

[0410] The disc brake device according to the present invention can suppress the temperature rise of the brake fluid, can stably obtain braking force based on the parking brake, and can solve the problems that arise when the linear motion component is fully released to the reverse side.

Claims

1. A disc brake device characterized by comprising: have: Liner block; A brake caliper having a cylinder body that opens on the side of the bushing; Piston, which is fitted into the cylinder body, presses the liner against the rotor; and A rotary-to-linear motion conversion mechanism, which pushes the piston toward the rotor by converting the rotational motion of the drive source into linear motion. Braking force based on the service brake is generated by supplying brake fluid into the cylinder, and braking force based on the parking brake is generated by activating the rotary-linear motion conversion mechanism. The piston comprises a piston body and a piston cap that are divided into two parts in the axial direction. The rotary-linear motion conversion mechanism includes: a rotating component, which is driven to rotate by the drive source; and a linear motion component, which is screwed onto the rotating component and disposed inside the piston body, engaging with the piston body in a manner that prevents relative rotation, and pressing the piston body axially. A one-way rotation limiting part is provided between the piston body and the piston cover. When the rotating component is driven to rotate in the forward rotation direction to move the linear motion component towards the rotor side, the one-way rotation limiting part restricts the relative rotation of the piston body with respect to the piston cover in the forward rotation direction. Conversely, when the rotating component is driven to rotate in the reverse rotation direction to move the linear motion component towards the rotor side, the one-way rotation limiting part allows the relative rotation of the piston body with respect to the piston cover in the reverse rotation direction. The unidirectional rotation limiting part includes: at least one convex or concave body-side engaging part disposed on the piston body; and at least one convex or concave cover-side engaging part disposed on the piston cover, which mechanically engages with the body-side engaging part when the rotating component is driven to rotate in the forward rotation direction. The piston cap is supported so that it can be displaced axially relative to the piston body.

2. The disc brake device according to claim 1, characterized in that, At least one of the portion of the main body side engaging portion that contacts the cover side engaging portion when the rotating component is driven to rotate in the positive rotation direction, and the portion of the cover side engaging portion that contacts the main body side engaging portion when the rotating component is driven to rotate in the positive rotation direction, has a limiting surface parallel to the central axis of the piston.

3. The disc brake device according to claim 1 or 2, characterized in that, The portion of the main body-side engaging part that contacts the cover-side engaging part when driving the rotating component in the reverse rotation direction has a main body-side guide surface. This main body-side guide surface is more rearward in the reverse rotation direction and closer to the rotor axially. When the rotating component is driven to rotate in the opposite direction, the main body side guide surface is pushed up by the cover-side engaging portion.

4. The disc brake device according to claim 3, characterized in that, The main body side guide surface is an inclined surface or a curved surface.

5. The disc brake device according to claim 1 or 2, characterized in that, The portion of the cover-side engaging part that contacts the main body-side engaging part when driving the rotating component in the reverse rotation direction has a cover-side guide surface. This cover-side guide surface is more forward-facing in the reverse rotation direction and further away from the rotor axially. When the rotating component is driven to rotate in the opposite direction, the main body side engaging portion is pushed up by the cover side guide surface.

6. The disc brake device according to claim 5, characterized in that, The guide surface on the cover side is an inclined surface or a curved surface.

7. The disc brake device according to claim 1 or 2, characterized in that, At least the cover-side engagement portion of the piston cover is made of metal.

8. The disc brake device according to claim 1 or 2, characterized in that, The main body side engaging portion has multiple parts that are separated in the circumferential direction. The cover side engaging portion has multiple portions that are separated in the circumferential direction.

9. The disc brake device according to claim 8, characterized in that, The plurality of the main body side engaging portions are arranged at equal intervals in the circumferential direction. The plurality of the cover-side engaging portions are arranged at equal intervals in the circumferential direction.

10. The disc brake device according to claim 1, characterized in that, The piston cover is supported such that it can be axially displaced relative to the piston body by an amount corresponding to the amount by which at least the body-side engagement portion can pass over the cover-side engagement portion when the rotating component is driven to rotate in the opposite direction of rotation.

11. The disc brake device according to claim 1, characterized in that, The unidirectional rotation limiting part also functions to transmit axial force between the piston body and the piston cover.

12. The disc brake device according to claim 11, characterized in that, The unidirectional rotation limiting part is composed of a main body-side sliding contact surface and a cover-side sliding contact surface. The main body-side sliding contact surface is disposed on the piston body, and the cover-side sliding contact surface is disposed on the piston cover and is axially opposite to the main body-side sliding contact surface. At least one of the body-side sliding contact surface and the cover-side sliding contact surface has been subjected to a surface finish that increases the coefficient of friction between the body-side sliding contact surface and the cover-side sliding contact surface, or at least one of the body-side sliding contact surface and the cover-side sliding contact surface is composed of a friction component. When the rotating component is driven to rotate in the forward rotation direction, as the axial force acting on the cover-side sliding contact surface from the main body side sliding contact surface increases, the main body side sliding contact surface and the cover-side sliding contact surface engage in a frictional manner in which they cannot rotate relative to each other. When the rotating component is driven to rotate in the reverse rotation direction, as the axial force acting on the cover-side sliding contact surface from the main body side sliding contact surface decreases, the main body side sliding contact surface rotates relative to the cover-side sliding contact surface in the reverse rotation direction.

13. The disc brake device according to claim 1 or 2, characterized in that, The disc brake device also includes the drive source, which is an electric motor.

14. A disc brake device characterized by comprising: have: Liner block; A brake caliper having a cylinder body that opens on the side of the bushing; Piston, which is fitted into the cylinder body, presses the liner against the rotor; and A rotary-to-linear motion conversion mechanism, which pushes the piston toward the rotor by converting the rotational motion of the drive source into linear motion. Braking force based on the service brake is generated by supplying brake fluid into the cylinder, and braking force based on the parking brake is generated by activating the rotary-linear motion conversion mechanism. The piston comprises a piston body and a piston cap that are divided into two parts in the axial direction. The rotary-linear motion conversion mechanism includes: a rotating component, which is driven to rotate by the drive source; and a linear motion component, which is screwed onto the rotating component and disposed inside the piston body, engaging with the piston body in a manner that prevents relative rotation, and pressing the piston body axially. A one-way rotation limiting part is provided between the piston body and the piston cover. When the rotating component is driven to rotate in the forward rotation direction to move the linear motion component towards the rotor side, the one-way rotation limiting part restricts the relative rotation of the piston body with respect to the piston cover in the forward rotation direction. Conversely, when the rotating component is driven to rotate in the reverse rotation direction to move the linear motion component towards the rotor side, the one-way rotation limiting part allows the relative rotation of the piston body with respect to the piston cover in the reverse rotation direction. The unidirectional rotation limiting part includes: at least one convex or concave body-side engaging part disposed on the piston body; and at least one convex or concave cover-side engaging part disposed on the piston cover, which mechanically engages with the body-side engaging part when the rotating component is driven to rotate in the forward rotation direction. An axial force transmission part is also provided between the piston body and the piston cover, which transmits axial force between the piston body and the piston cover. The axial force transmission part is separately disposed from the unidirectional rotation restriction part.

15. The disc brake device according to claim 14, characterized in that, The axial force transmission part includes: a flat, planar body-side transmission surface located on an imaginary plane in the piston body orthogonal to the central axis of the piston body; and a flat, planar cover-side transmission surface located on an imaginary plane in the piston cover orthogonal to the central axis of the piston cover.

16. The disc brake device according to claim 14, characterized in that, At least one of the portion of the main body side engaging portion that contacts the cover side engaging portion when the rotating component is driven to rotate in the positive rotation direction, and the portion of the cover side engaging portion that contacts the main body side engaging portion when the rotating component is driven to rotate in the positive rotation direction, has a limiting surface parallel to the central axis of the piston.

17. The disc brake device according to any one of claims 14-16, characterized in that, The portion of the main body-side engaging part that contacts the cover-side engaging part when driving the rotating component in the reverse rotation direction has a main body-side guide surface. This main body-side guide surface is more rearward in the reverse rotation direction and closer to the rotor axially. When the rotating component is driven to rotate in the opposite direction, the main body side guide surface is pushed up by the cover-side engaging portion.

18. The disc brake device according to claim 17, characterized in that, The main body side guide surface is an inclined surface or a curved surface.

19. The disc brake device according to any one of claims 14-16, characterized in that, The portion of the cover-side engaging part that contacts the main body-side engaging part when driving the rotating component in the reverse rotation direction has a cover-side guide surface. This cover-side guide surface is more forward-facing in the reverse rotation direction and further away from the rotor axially. When the rotating component is driven to rotate in the opposite direction, the main body side engaging portion is pushed up by the cover side guide surface.

20. The disc brake device according to claim 19, characterized in that, The guide surface on the cover side is an inclined surface or a curved surface.

21. The disc brake device according to any one of claims 14-16, characterized in that, At least the cover-side engagement portion of the piston cover is made of metal.

22. The disc brake device according to any one of claims 14-16, characterized in that, The main body side engaging portion has multiple parts that are separated in the circumferential direction. The cover side engaging portion has multiple portions that are separated in the circumferential direction.

23. The disc brake device according to claim 22, characterized in that, The plurality of the main body side engaging portions are arranged at equal intervals in the circumferential direction. The plurality of the cover-side engaging portions are arranged at equal intervals in the circumferential direction.

24. The disc brake device according to claim 14, characterized in that, The unidirectional rotation limiting part also functions to transmit axial force between the piston body and the piston cover.

25. The disc brake device according to claim 24, characterized in that, The unidirectional rotation limiting part is composed of a main body-side sliding contact surface and a cover-side sliding contact surface. The main body-side sliding contact surface is disposed on the piston body, and the cover-side sliding contact surface is disposed on the piston cover and is axially opposite to the main body-side sliding contact surface. At least one of the body-side sliding contact surface and the cover-side sliding contact surface has been subjected to a surface finish that increases the coefficient of friction between the body-side sliding contact surface and the cover-side sliding contact surface, or at least one of the body-side sliding contact surface and the cover-side sliding contact surface is composed of a friction component. When the rotating component is driven to rotate in the forward rotation direction, as the axial force acting on the cover-side sliding contact surface from the main body side sliding contact surface increases, the main body side sliding contact surface and the cover-side sliding contact surface engage in a frictional manner in which they cannot rotate relative to each other. When the rotating component is driven to rotate in the reverse rotation direction, as the axial force acting on the cover-side sliding contact surface from the main body side sliding contact surface decreases, the main body side sliding contact surface rotates relative to the cover-side sliding contact surface in the reverse rotation direction.

26. The disc brake device according to any one of claims 14-16, characterized in that, The disc brake device also includes the drive source, which is an electric motor.

Images