Rotary Damper and Brake System

Abstract

To provide a rotary damper which is suitable as a damper for a brake pedal including a fail-safe function.SOLUTION: In a rotary damper 1 for a brake pedal of a motor vehicle which generates brake torque when a case 11 rotates in a normal rotation direction N relative to a rotor 12, the case 11 is formed by a thermoplastic resin, and a pair of arm parts 19a, 19b, which protrude to the radial outer side and sandwich a plate 5 which rotates around a pedal rotation center O in conjunction with a brake pedal 4, are provided at the case 11. Further, the arm part 19a, which is located at the downstream side in the normal rotation direction N, of the pair of arm parts 19a, 19b is provided with a curved part 191 having a constant width, and the plate 5 is supported by a support part 192 located at the tip side relative to the curved part 191.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a rotary damper, and more particularly to a rotary damper suitable for use as a damper for a brake pedal. [Background technology]

[0002] There is known a rotary damper that generates a strong braking torque for rotation in the forward direction and a weak braking torque for rotation in the reverse direction. For example, Patent Document 1 discloses a rotary damper that has a simple structure and can be manufactured at low cost.

[0003] The rotary damper described in Patent Document 1 comprises a case with a cylindrical chamber, a rotor rotatably accommodated in the cylindrical chamber, a viscous fluid filled in the cylindrical chamber, and a lid attached to the open end face of the case to enclose the rotor together with the viscous fluid within the cylindrical chamber.

[0004] The rotor has a cylindrical rotor body and a vane formed to protrude radially outward from the outer circumferential surface of the rotor body so as to form a small gap with the side wall surface of the cylindrical chamber. The vane has a flow path formed therein that connects one side surface (called the first side surface) to the other side surface (called the second side surface) along the rotation direction of the rotor. A seal material is attached to the tip surface of the vane (the surface facing the side wall surface of the cylindrical chamber) to fill the small gap with the side wall surface of the cylindrical chamber. This seal material has an elastic check valve that opens and closes the flow path formed in the vane. A partition portion is formed on the side wall surface of the cylindrical chamber so as to form a small gap with the outer circumferential surface of the rotor body and protrudes radially inward.

[0005] In the rotary damper described in Patent Document 1, when a force is applied to the rotor to rotate it in a direction from the first side surface of the vane to the second side surface (forward rotation direction), the check valve is pressed against the second side surface of the vane by the viscous fluid in the cylindrical chamber, and the flow path is blocked by the check valve. As a result, the movement of the viscous fluid is limited only through the gap between the partition of the cylindrical chamber and the outer circumferential surface of the rotor body and the gap between the closing end surface (bottom surface) of the case and the lower surface of the vane (the surface facing the closing end surface of the case), and the pressure on the viscous fluid on the second side surface side of the vane increases, generating a strong braking torque. On the other hand, when a force is applied to the rotor to rotate it in a direction from the second side surface of the vane to the first side surface (reverse rotation direction), the viscous fluid on the first side surface side of the vane flows into the flow path and pushes up the check valve to open the flow path. Therefore, since the movement of the viscous fluid also occurs in the flow passages formed in the vane, the pressure on the viscous fluid on the first side surface side of the vane does not become high, and as a result, a weak braking torque is generated. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 7-301272 Summary of the Invention [Problem to be solved by the invention]

[0007] The rotary damper described in Patent Document 1 can be used as a damper for an automobile brake pedal by linking it to a brake pedal so as to generate a strong braking torque when the automobile driver depresses the brake pedal.

[0008] However, when the rotary damper described in Patent Document 1 is used as a damper for an automobile brake pedal, from the standpoint of fail-safe, it is necessary to ensure that the brakes can be applied reliably by firmly pressing the brake pedal even when a malfunction occurs in the rotary damper and the relative rotation between the case and the rotor is prevented.

[0009] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a rotary damper that is suitable as a damper for a brake pedal with a fail-safe function, and a brake system that uses this rotary damper. [Means for solving the problem]

[0010] In order to solve the above problems, the present invention provides a rotary damper for an automobile brake pedal that generates a braking torque when the case rotates in the forward rotation direction relative to a rotor, the case being made of a thermoplastic resin, the case being provided with a pair of arms protruding radially outward and sandwiching a plate that rotates around the pedal rotation center in conjunction with the brake pedal, the pair of arms being provided with a curved portion of a constant width on the arm located downstream in the forward rotation direction, and the plate being supported on the tip side of the curved portion of the arm.

[0011] For example, the rotary damper of the present invention has A rotary damper for a brake pedal of an automobile, comprising: a rotor; and a case that accommodates the rotor so as to be rotatable relative to the rotor, the rotary damper generating a braking torque when the case rotates in a forward rotation direction relative to the rotor, The case is It is made of thermoplastic resin, A pair of arms protruding radially outward sandwich a plate that rotates around a pedal rotation center in conjunction with the brake pedal, Of the pair of arms, the arm located downstream in the forward rotation direction is A curved portion of a constant width; The plate has a support portion that is located distal to the curved portion and supports the plate. The brake system of the present invention further comprises: A brake system including the rotary damper described above, A shaft located at the center of pedal rotation; a brake arm rotatably attached to the shaft and connected to a brake master cylinder; A brake pedal attached to an end of the brake arm; a plate attached to the brake arm so as to rotate about a pedal rotation center in conjunction with the brake pedal; The rotary damper includes: The rotor is fixed to the shaft, and the rotation of the rotor around the pedal rotation center is restricted. When the brake pedal is depressed and the plate rotates around the pedal rotation center in the forward rotation direction, the plate is supported by the support portion of the arm portion that is located downstream in the forward rotation direction of the pair of arm portions, and when the brake pedal is released and the plate rotates around the pedal rotation center in the reverse rotation direction, the plate is supported by the arm portion of the pair of arm portions that is located upstream in the forward rotation direction, The plate is The terminal is sandwiched and held by the pair of arms so as not to interfere with the base portion between the pair of arms. Effect of the Invention

[0012] In the present invention, the rotary damper is installed so that the plate presses the arm portion located downstream in the forward rotation direction in conjunction with the depression of the brake pedal, thereby generating a braking torque in response to the depression of the brake pedal. In addition, the case is made of a thermoplastic resin, and a curved portion is provided on the arm portion located downstream in the forward rotation direction, and the plate is supported on the tip side of the curved portion of the arm portion, so that the stress generated on the arm portion by the pressing of the plate is concentrated on the curved portion. Therefore, even if a malfunction occurs in the rotary damper and the relative rotation between the case and the rotor is prevented, the curved portion can be broken by strongly depressing the brake pedal, thereby applying the brakes. Furthermore, since the width of the curved portion is constant, the variation in the brake pedal pressing force required to break the curved portion due to the variation in the pressing direction of the plate applied to the tip side of the curved portion of the arm portion can be reduced.

[0013] Therefore, according to the present invention, it is possible to provide a rotary damper suitable as a brake pedal damper having a fail-safe function, and a brake system using this rotary damper. [Brief description of the drawings]

[0014] [Figure 1] 1(A) to 1(C) are a front view, a side view, and a rear view of a rotary damper 1 according to an embodiment of the present invention. [Diagram 2] FIG. 2A is a cross-sectional view taken along line AA of the rotary damper 1 shown in FIG. 1A, and FIG. 2B is a cross-sectional view taken along line BB of the rotary damper 1 shown in FIG. 1B. [Diagram 3] 3(A) and 3(B) are enlarged views of part A and part B of the rotary damper 1 shown in FIG. 2(A). [Figure 4] FIG. 4(A) is an enlarged view of a portion C of the rotary damper 1 shown in FIG. 2(A), and FIG. 4(B) is an enlarged view of a portion D of the rotary damper 1 shown in FIG. 2(B). [Diagram 5]5(A) is a front view of case 11, FIG. 5(B) is a CC cross-sectional view of case 11 shown in FIG. 5(A), FIG. 5(C) is a rear view of case 11, FIG. 5(D) is an enlarged view of E portion of case 11 shown in FIG. 5(A), FIG. 5(E) is an enlarged DD cross-sectional view of case 11 shown in FIG. 5(A), and FIG. 5(F) is an enlarged EE cross-sectional view of case 11 shown in FIG. 5(A). [Figure 6] 6(A) and 6(B) are a front view and a side view of the rotor 12, and FIG. 6(C) is an FF cross-sectional view of the rotor 12 shown in FIG. 6(A). [Figure 7] 7(A) and 7(B) are a front view and a side view of the first sealant 13, and FIG. 7(C) is a cross-sectional view of the first sealant 13 shown in FIG. 7(A) along line GG. [Figure 8] 8(A) and 8(B) are a front view and a side view of the second sealant 14, and FIG. 8(C) is an HH cross-sectional view of the second sealant 14 shown in FIG. 8(A). [Figure 9] 9(A) to 9(C) are a front view, a side view, and a rear view of the lid 15, and FIG. 9(D) is a cross-sectional view of the lid 15 shown in FIG. 9(A) taken along line II. [Figure 10] 10(A) to 10(D) are a front view, a top view, a bottom view and a side view of the axial force generating member 17, FIG. 10(E) is an enlarged view of the JJ cross section of the axial force generating member 17 shown in FIG. 10(C), and FIG. 10(F) is an enlarged view of the KK cross section of the axial force generating member 17 shown in FIG. 10(D). [Figure 11] FIG. 11(A) is an enlarged view of the axial force generating member 17 attached to the protrusion 18 of the partition 115 of the case 11 in a rotary damper 1 according to one embodiment of the present invention, as viewed from the center of the rotary damper 1, and FIG. 11(B) is an enlarged view of the LL cross section of the axial force generating member 17 shown in FIG. 11(A). [Figure 12] 12(A) and 12(B) are diagrams showing an example of an automobile brake system to which a rotary damper 1 according to an embodiment of the present invention is applied. [Figure 13]13(A) and 13(B) are diagrams showing an example of operation when a malfunction occurs in the rotary damper 1 in the brake system of the automobile shown in FIG. [Figure 14] FIG. 14 is a diagram for explaining the positional relationship between the rotary damper 1 and the plate 5 of the brake pedal 4. As shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] An embodiment of the present invention will now be described with reference to the drawings.

[0016] Fig. 1(A) to Fig. 1(C) are a front view, a side view, and a rear view of a rotary damper 1 according to an embodiment of the present invention. Fig. 2(A) is a cross-sectional view of the rotary damper 1 shown in Fig. 1(A) taken along line AA, and Fig. 2(B) is a cross-sectional view of the rotary damper 1 shown in Fig. 1(B). Fig. 3(A) and Fig. 3(B) are enlarged views of parts A and B of the rotary damper 1 shown in Fig. 2(A), Fig. 4(A) is an enlarged view of part C of the rotary damper 1 shown in Fig. 2(A), and Fig. 4(B) is an enlarged view of part D of the rotary damper 1 shown in Fig. 2(B).

[0017] As shown in the figure, the rotary damper 1 according to this embodiment includes a case 11, a rotor 12 housed in the case 11 so as to be rotatable relative to the case 11, a viscous fluid (not shown) such as oil or silicon filled in the case 11, a lid 15 that seals the rotor 12 together with the viscous fluid in the case 11, and a pair of axial force generating members 17. This rotary damper 1 is a damper for an automobile brake pedal, and generates a strong braking torque when the case 11 rotates in a forward direction N relative to the rotor 12, and generates a weak braking torque when the case 11 rotates in a reverse direction R relative to the rotor 12 (see Figures 1(C) and 2(B)).

[0018] 5(A) is a front view of case 11, FIG. 5(B) is a CC cross-sectional view of case 11 shown in FIG. 5(A), FIG. 5(C) is a rear view of case 11, FIG. 5(D) is an enlarged view of E portion of case 11 shown in FIG. 5(A), FIG. 5(E) is an enlarged DD cross-sectional view of case 11 shown in FIG. 5(A), and FIG. 5(F) is an enlarged EE cross-sectional view of case 11 shown in FIG. 5(A).

[0019] The case 11 is made of a thermoplastic resin such as polyacetal, and as shown in the figure, a cylindrical chamber (a cylindrical space with a bottom) 111 with one open end is formed in the case 11, and an opening 113 for inserting the rotor 12 is formed in a bottom 112 of the cylindrical chamber 111. The rotor 12 is accommodated in the cylindrical chamber 111 such that a rotation axis 120 of the rotor 12 coincides with a center line 110 of the cylindrical chamber 111 by inserting a lower end 123a (see FIG. 6) of a rotor body 121 (described later) into the opening 113 (see FIG. 2(A)). In addition, a pair of partitions 115 that partition the cylindrical chamber 111 are formed on a side wall surface 114 of the cylindrical chamber 111 along the center line 110 of the cylindrical chamber 111 and axially symmetrical with respect to the center line 110, protruding radially inward and with a tip surface 116 adjacent to an outer circumferential surface 124 (see FIG. 6) of a rotor body 121 (described later) of the rotor 12.

[0020] A first seal member 13, which will be described later, is attached to each of the pair of partitions 115 (see FIG. 4(B)). Each of the pair of partitions 115 has a protrusion 18 formed on an upper surface 119, which faces the rear surface 153 (see FIG. 9) of the lid 15, for attaching the axial force generating member 17. A groove 181, for inserting an adjustment portion 174, which will be described later, of the axial force generating member 17, is formed on an upper surface 180 of the protrusion 18 along the radial direction of the cylindrical chamber 111, and a bottom 182 of the groove is located closer to the lid 15 than the upper surface 119 of the partitions 115. A groove 184, for attaching a first pressure contact portion 175, which will be described later, of the axial force generating member 17, is formed on both side surfaces 183 of the protrusion 18 along the radial direction of the case 11 along the center line 110 of the cylindrical chamber 111.

[0021] An opening side 118 of the side wall surface 114 of the cylindrical chamber 111 is formed with a female screw portion 117 which screws into a male screw portion 152 (see FIG. 9) of the lid 15, which will be described later.

[0022] In addition, a pair of arm portions 19a, 19b are formed protruding radially outward on the outer peripheral surface 190 of the case 11 at the opening side 118 of the cylindrical chamber 111 and sandwich a plate 5 that rotates around the pedal rotation center O in conjunction with the brake pedal 4 of the automobile (see Figure 12).

[0023] Arm portion 19a is located downstream of arm portion 19b in the forward rotation direction N (see FIG. 2(B)) of rotor 12 of case 11 in which rotary damper 1 generates a strong braking torque. Arm portion 19a also has a curved portion 191 curved in the rotation direction N, a support portion 192, and a connecting portion 193.

[0024] The curved portion 191 has a radial cross section with the same shape throughout the entire curved portion 191 with respect to the center of curvature C of the curved portion 191 (see FIG. 5(F)), and has a constant radial width W (see FIG. 5(C)).

[0025] The support portion 192 is located on the tip side of the curved portion 191 and supports the plate 5 which rotates in the forward direction N around the pedal rotation center O in conjunction with the brake pedal 4 (see FIG. 12), and has a support surface 195 which contacts the plate 5 to support the plate 5. Here, the angle α (see FIG. 5(C)) between the support surface 195 and a straight line passing through the support portion 192 side end 197 on the inner circumferential surface 196 of the curved portion 191 and the curved portion 191 side end 201 of the support surface 195 is preferably within an angle range in which the curved portion 191 side end 201 of the support surface 195 can maintain line contact with the plate 5 when the curved portion 191 is pressed by the plate 5 and deformed (see FIG. 13). However, if the angle α is smaller than 10 degrees, the arm portion 19a needs to be longer in order to reliably contact the support surface 195 with the plate 5, and the rotary damper 1 becomes larger. Furthermore, if the angle α is greater than 90 degrees, the arm portion 19a becomes longer and the rotary damper 1 becomes larger. Usually, there is a restriction on the installation space for the rotary damper 1 on the brake pedal 4, and an increase in the size of the rotary damper 1 makes it difficult to attach it to the brake pedal 4. The angle α is preferably 30 degrees to 60 degrees.

[0026] The connecting portion 193 extends radially outward from the outer circumferential surface 190 of the case 11 and connects to the curved portion 191 .

[0027] Arm portion 19b is located upstream of arm portion 19a in the forward rotation direction N (see FIG. 2(B)) of rotor 12 of case 11 in which rotary damper 1 generates strong braking torque. Arm portion 19b also has a flat surface 194 that faces arm portion 19a and extends radially outward from an outer circumferential surface 190 of case 11. Flat surface 194 supports plate 5 that rotates in reverse direction R around pedal rotation center O in conjunction with brake pedal 4.

[0028] 6(A) and 6(B) are a front view and a side view of the rotor 12, and FIG. 6(C) is an FF cross-sectional view of the rotor 12 shown in FIG. 6(A).

[0029] The rotor 12 is made of a thermoplastic resin such as polyamide resin, and includes a cylindrical rotor body 121 and a pair of vanes (rotating blades) 122 formed symmetrically with respect to a rotation shaft 120 of the rotor 12, as shown in the figure. The vanes 122 are formed along the rotation shaft 120 of the rotor 12, protrude radially outward from an outer circumferential surface 124 of the rotor body 121, and have a tip surface 125 adjacent to a side wall surface 114 of the cylindrical chamber 111 of the case 11 to partition the cylindrical chamber 111. A flow path 126 is formed in the vane 122, penetrating between both side surfaces 127a, 127b of the vane 122 along the rotation direction of the rotor 12. A second seal material 14, which will be described later, is attached to each of the pair of vanes 122 (see FIG. 4(B)).

[0030] In the rotor body 121, a two-chamfered through hole 128 of the rotor for inserting a two-chamfered shaft (not shown) that transmits external rotational force to the rotor 12 is formed around the rotation axis 120. The lower end 123a of the rotor body 121 is rotatably inserted into an opening 113 formed in the bottom 112 of the cylindrical chamber 111 of the case 11 (see FIG. 4(A)), and the upper end 123b of the rotor body 121 is rotatably inserted into an opening 150 (see FIG. 9) of the lid 15 (see FIGS. 3(A) and (B)).

[0031] In addition, to prevent the viscous fluid from leaking to the outside from the opening 113 of the cylindrical chamber 111, a sealing material such as an O-ring 16a may be interposed between the lower end 123a of the rotor body 121 and the opening 113 of the cylindrical chamber 111 (see Figure 4(A)).

[0032] 7(A) and 7(B) are a front view and a side view of the first sealant 13, and FIG. 7(C) is a cross-sectional view of the first sealant 13 shown in FIG. 7(A) along line GG.

[0033] As shown in the figure, the first sealant 13 has a U-shape that can be attached to a partition 115 formed in the cylindrical chamber 111 of the case 11, and a bottom 130 is interposed between a tip surface 116 of the partition 115 and an outer circumferential surface 124 of the rotor body 121 of the rotor 12, thereby closing the gap between them (see FIG. 4(B)). Note that since the first sealant 13 is disposed between the case 11 and the rotor 12, which rotate relative to each other, it is preferable to use a resin with excellent sliding properties, such as polyamide, as its material.

[0034] 8(A) and 8(B) are a front view and a side view of the second sealant 14, and FIG. 8(C) is an HH cross-sectional view of the second sealant 14 shown in FIG. 8(A).

[0035] As shown in the figure, the second sealing material 14 has a U-shape that can be attached to the vane 122 of the rotor 12, and has a bottom 140 having a width t2 wider than the rotational width t1 of the vane 122 (see Figure 6(A)), a first leg 143 formed integrally with one end 141 of the bottom 140 and having a width t4 wider than the radial width t3 of the flow path 126 formed in the vane 122 (see Figure 6(B)), and a second leg 144 formed integrally with the other end 142 of the bottom 140 and having a width t5 narrower than the radial width t3 of the flow path 126 formed in the vane 122.

[0036] The second seal member 14 attached to the vane 122 has a bottom 140 interposed between the tip surface 125 of the vane 122 and the side wall surface 114 of the cylindrical chamber 111 of the case 11, thereby sealing the gap between them (see FIG. 4(B)). Also, as shown in FIG. 2(B), when the case 11 rotates in the normal direction N relative to the rotor 12, Partition 115 and Partition 115 Located downstream of the forward rotation direction N Vane 122 The pressure on the viscous fluid in the region 111a (see FIG. 2(B)) separated by the first and second sealants 14 increases, causing the second sealant 14 to move in the forward rotation direction N, and the first leg 143 of the second sealant 14 abuts against one side 127a of the vane 122, blocking the flow path 126 formed in the vane 122.

[0037] On the other hand, when the case 11 rotates in the reverse direction R relative to the rotor 12, Partition 115 and Partition 115 Located downstream of the reversal direction R Vane 122 The pressure on the viscous fluid in region 111b (see FIG. 2(B)) separated by the vane 122 and the second sealant 14 moves in the inversion direction R, and the second leg 144 comes into contact with the other side surface 127b of the vane 122, opening the flow path 126 formed in the vane 122. Since the second sealant 14 is disposed between the case 11 and the rotor 12, which rotate relative to one another, it is preferable to use a resin with excellent sliding properties, such as polyamide, as its material.

[0038] 9(A) to 9(C) are a front view, a side view, and a rear view of the lid 15, and FIG. 9(D) is a cross-sectional view of the lid 15 shown in FIG. 9(A) taken along line II.

[0039] As shown in the figure, the lid 15 has an opening 150 for inserting the upper end 123b of the rotor body 121 of the rotor 12 at a position opposite to the opening 113 formed in the bottom 112 of the cylindrical chamber 111 of the case 11. In addition, an external thread 152 is formed on the outer circumferential surface 151 of the lid 15 to screw into the female thread 117 formed on the opening side 118 of the side wall surface 114 of the cylindrical chamber 111. In addition, a gap G1 is formed between the lower surface (rear surface) 153 of the lid 15 and the upper surface 129 of the vane 122 of the rotor 12, functioning as a flow path for the viscous fluid filled in the cylindrical chamber 111 (see FIG. 3(B)). The gap G1 functioning as a flow path for the viscous fluid can be adjusted by adjusting the amount of screwing of the lid 15 into the case 11 (the amount of screwing between the male thread 152 of the lid 15 and the female thread 117 of the case 11).

[0040] In order to prevent the viscous fluid from leaking to the outside from the opening 150 of the lid 15, a seal material such as an O-ring 16b may be interposed between the upper end 123b of the rotor body 121 of the rotor 12 and the opening 150 of the lid 15. Similarly, in order to prevent the viscous fluid from leaking to the outside from the screwed portion between the male screw portion 152 of the lid 15 and the female screw portion 117 of the cylindrical chamber 111 of the case 11, a seal material such as an O-ring 16c may be interposed between the outer peripheral surface 151 of the lid 15 and the side wall surface 114 of the cylindrical chamber 111 (see FIGS. 3(A) and 3(B)).

[0041] Fig. 10(A) to Fig. 10(D) are a front view, a top view, a bottom view and a side view of the axial force generating member 17, Fig. 10(E) is an enlarged view of the JJ cross section of the axial force generating member 17 shown in Fig. 10(C), and Fig. 10(F) is an enlarged view of the KK cross section of the axial force generating member 17 shown in Fig. 10(D). Fig. 11(A) is an enlarged view of the axial force generating member 17 attached to the protrusion 18 of the partitioning part 115 of the case 11 in the rotary damper 1 according to this embodiment, as viewed from the center of the rotary damper 1 (corresponding to a view seen in the direction of the arrow F in Fig. 5(A)), and Fig. 11(B) is an enlarged view of the LL cross section of the axial force generating member 17 shown in Fig. 11(A).

[0042] The axial force generating member 17 is formed from a plastically deformable material such as a thermoplastic resin such as polyacetal, or a sintered metal, or an elastically deformable material such as natural rubber, synthetic rubber, or a synthetic resin elastomer. It is attached to each of the protrusions 18 formed on the upper surface 119 of a pair of partitions 115 of the case 11 and is interposed between the upper surface 119 of the partitions 115 and the back surface 153 of the lid 15, sealing the gap between the back surface 153 of the lid 15 and the upper surface 119 of the partitions 115, and generates an axial force when the lid 15 is screwed into the case 11.

[0043] As shown in the figure, the axial force generating member 17 includes a rectangular main body portion 170 having an upper surface 171 that contacts the back surface 153 of the lid 15, a pair of arm portions 173 formed on the lower surface 172 of the main body portion 170 that sandwich both side surfaces 183 of a convex portion 18 formed on the upper surface 119 of the partition portion 115 of the case 11 to grip the convex portion 18, and an adjustment portion 174 disposed between the pair of arm portions 173 that protrudes toward the convex portion 18 and is inserted into a groove 181 of the convex portion 18.

[0044] Each of the pair of arm portions 173 has a first pressure contact portion 175 that is in pressure contact with a groove 184 formed on both side surfaces 183 of the convex portion 18. The first pressure contact portion 175 functions as a positioning means when the axial force generating member 17 is attached to the convex portion 18 together with the grooves 184 formed on both side surfaces 183 of the convex portion 18. Further, by this first pressure contact portion 175, the pair of arm portions 173 firmly grip the axial force generating member 17 so that the axial force generating member 17 does not fall off from the convex portion 18. The pair of arm portions 173 has a length L4 (<L2 + L3) that is shorter than the sum of the length L2 of the adjustment portion 174 and the length L3 (see FIG. 5(E)) from the upper surface 119 of the partition portion 115 to the groove bottom 182 of the groove 181 of the convex portion 18 formed on this upper surface 119.

[0045] The adjustment portion 174 has a length L2 (>L1) that is longer than the depth L1 (see FIG. 5(E)) of the groove 181 of the convex portion 18 formed on the upper surface 119 of the partition portion 115, and the tip portion 176 thereof is formed to be narrower in the thickness direction than its root portion 177. Here, the groove 181 of the convex portion 18 has a size that allows plastic deformation or elastic deformation of the tip portion 176 of the adjustment portion 174. Further, the root portion 177 of the adjustment portion 174 has second pressure contact portions 178 on both side surfaces 179 in the thickness direction that are in pressure contact with both side walls 185 of the groove 181 of the convex portion 18. By this second pressure contact portion 178, the adjustment portion 174 fits into the groove 181 of the convex portion 18 and more reliably prevents the axial force generating member 17 from falling off from the convex portion 18.

[0046] Since the pair of arm portions 173 have a length L4 that is shorter than the sum of the length L2 of the adjustment portion 174 and the length L3 from the upper surface 119 of the partition portion 115 to the groove bottom 182 of the groove 181 of the convex portion 18, and the adjustment portion 174 has a length L2 that is longer than the depth L1 of the groove 181 of the convex portion 18, the tip portion 176 of the adjustment portion 174 can be abutted against the groove bottom 182 of the groove 181 of the convex portion 18 without abutting the pair of arm portions 173 against the upper surface 119 of the partition portion 115. In addition, since groove 181 of convex portion 18 has a size that allows plastic or elastic deformation of tip 176 of adjustment portion 174, when lid 15 is screwed into case 11, an axial force is generated, and in addition to the plastic or elastic deformation of main body portion 170, tip 176 of adjustment portion 174 actively undergoes plastic or elastic deformation, thereby increasing the adjustment margin of gap G1 between back surface 153 of lid 15 and upper surface 129 of vane 122.

[0047] In the rotary damper 1 having the above configuration, when the case 11 rotates in the normal direction N relative to the rotor 12 (see FIG. 2B), the second seal 14 moves toward the normal direction N, and the first leg 143 of the second seal 14 abuts against one side surface 127a of the vane 122, blocking the flow path 126 formed in the vane 122. At this time, the first seal 13 attached to the partition 115 of the cylindrical chamber 111 of the case 11 blocks the gap between the tip surface 116 of the partition 115 and the outer circumferential surface 124 of the rotor body 121 of the rotor 12, and the second seal 14 attached to the vane 122 of the rotor 12 blocks the gap between the tip surface 125 of the vane 122 and the side wall surface 114 of the cylindrical chamber 111 of the case 11 (see FIG. 4B). Therefore, the movement of the viscous fluid filled in the cylindrical chamber 111 is restricted only via the gap G1 between the back surface 153 of the lid 15 and the upper surface 129 of the vane 122. Partition 115 and Partition 115 Located downstream of the forward rotation direction N Vane 122 The pressure on the viscous fluid in the region 111a (see FIG. 2B) partitioned by the gap between the two increases, generating a strong braking torque.

[0048] Here, the gap G1 between the back surface 153 of the lid 15 and the top surface 129 of the vane 122 can be adjusted by adjusting the amount of screwing of the lid 15 into the case 11 (the amount of screwing between the male screw portion 152 of the lid 15 and the female screw portion 117 of the case 11). Therefore, by adjusting the amount of movement of the viscous fluid that moves through this gap G1, the braking torque generated by rotation can be adjusted.

[0049] Furthermore, by disposing an axial force generating member 17 that applies a reaction force to the lid 15 between the rear surface 153 of the lid 15 and the upper surface 119 of the partition portion 115, an axial force is generated when the lid 15 is screwed into the case 11, preventing leakage of viscous fluid from the screwed portion between the male threaded portion 152 of the lid 15 and the female threaded portion 117 of the case 11, while increasing the adjustment margin for the gap G1 and widening the adjustment range of the braking torque.

[0050] On the other hand, when the case 11 rotates in the reverse direction R relative to the rotor 12 (see FIG. 2B), the second seal 14 moves in the reverse direction R, and the second leg 144 abuts against the other side surface 127b of the vane 122, opening the flow path 126 formed in the vane 122. Therefore, the viscous fluid filled in the cylindrical chamber 111 moves not only through the gap G1 between the back surface 153 of the lid 15 and the upper surface 129 of the vane 122, but also through the flow path 126 formed in the vane 122. Partition 115 and Partition 115 Located on the reverse direction R side Vane 122 The pressure on the viscous fluid in the region 111b (see FIG. 2B) separated by the gap does not increase, and therefore a weak braking torque is generated.

[0051] 12(A) and 12(B) are diagrams showing an example of an automobile brake system to which the rotary damper 1 according to this embodiment is applied.

[0052] This brake system comprises a shaft 2 arranged at a pedal rotation center O, a brake arm 3 rotatably attached to the shaft 2 and connected to a brake master cylinder 6, a brake pedal 4 attached to the end of the brake arm 3, a plate 5 attached to the brake arm 3 so as to rotate around the pedal rotation center O in conjunction with the brake pedal 4, and a rotary damper 1 attached to the shaft 2 so as to sandwich the plate 5 between a pair of arm portions 19a, 19b.

[0053] Here, the tip of the shaft 2 is chamfered on two sides, and this tip is inserted into a two-chamfered through hole 128 of the rotor 12 of the rotary damper 1, whereby the rotor 12 is fixed to the shaft 2 and its rotation around the pedal rotation center O is restricted. The rotary damper 1 is also attached so that when the brake pedal 4 is depressed and the plate 5 rotates around the pedal rotation center O in the forward direction N, the plate 5 is supported by the support surface 195 of the support portion 192 of the arm portion 19a, and when the brake pedal 4 is released and the plate 5 rotates around the pedal rotation center O in the reverse direction R, the plate 5 is supported by the flat surface 194 of the arm portion 19b. In addition, the plate 5 is sandwiched between the support surface 195 of the support portion 192 of the arm portion 19a and the flat surface 194 of the arm portion 19b so as not to interfere with the base portion 199 (see FIG. 12(A)) between the pair of arm portions 19a, 19b, and is gripped by the pair of arm portions 19a, 19b.

[0054] In the brake system having the above configuration, as shown in Fig. 12(A), when the brake pedal 4 is depressed, the brake master cylinder 6 is compressed and the plate 5 rotates in the normal direction N around the pedal rotation center O, and this rotational torque is transmitted to the case 11 of the rotary damper 1 via the arm portion 19a. Here, since the rotor 12 of the rotary damper 1 is constrained from rotating around the pedal rotation center O, the case 11 rotates in the normal direction N relative to the rotor 12, generating a strong braking torque. As a result, a strong reaction force can be applied to the depression of the brake pedal 4, and a good brake feel can be obtained.

[0055] In FIG. 12(A), the stress generated in the arm portion 19a by the rotation torque in the normal rotation direction N transmitted from the plate 5 to the arm portion 19a is concentrated on the curved portion 191 of the arm portion 19a. Therefore, even if a malfunction occurs in the rotary damper 1 and the rotation in the normal rotation direction N relative to the rotor 12 of the case 11 is prevented, as shown in FIGS. 13(A) to 13(C), by strongly depressing the brake pedal 4, the curved portion 191 can be deformed and possibly broken, releasing the plate 5 from the support of the arm portion 19a, compressing the brake master cylinder 6, and applying the brakes. At this time, the curved portion 191 is deformed toward the space D (see FIG. 13(A)) secured between the curved portion 191 and the case 11 by the connecting portion 193, so that the curved portion 191 can be deformed without interfering with the brake pedal 4. In addition, the curved portion 191 does not hinder the movement of the brake pedal 4 even after it is broken.

[0056] 12(B), when the brake pedal 4 is released, the brake master cylinder 6 expands, causing the plate 5 to rotate in the reverse direction R around the pedal rotation center O, and this rotational torque is transmitted to the case 11 of the rotary damper 1 via the arm portion 19b. Here, the rotor 12 of the rotary damper 1 is constrained from rotating around the pedal rotation center O, so the case 11 rotates in the reverse direction R relative to the rotor 12, but since the braking torque generated in this case is weak, the extension force of the brake master cylinder 6 overcomes this weak braking torque, and the brake pedal 4 returns to its original position before it was depressed.

[0057] As shown in Fig. 14, if the distance from the center O of the rotary damper 1 (pedal rotation center) to the plate 5 is r1, the distance from the center O of the rotary damper 1 to the outer circumferential surface 198 at the end 197 of the curved portion 191 on the support portion 192 side is r2, and the distance from the center O of the rotary damper 1 to the outermost periphery (the outermost periphery of the connecting portion 193) 200 of the root portion 199 between the pair of arm portions 19a and 19b is r3, it is preferable that r1>r2 and r1>r3. If r1≦r2, the arm portion 19a becomes longer and the rotary damper 1 becomes larger. Usually, there is a restriction on the installation space of the rotary damper 1 on the brake pedal 4, and the larger the rotary damper 1, the more difficult it is to attach it to the brake pedal 4. Furthermore, if r1≦r3, plate 5 comes into contact not only with support surface 195 but also with base portion 199, and when arm portion 19a is pressed against plate 5, it becomes difficult to concentrate the stress generated in arm portion 19a by that force on curved portion 191.

[0058] One embodiment of the present invention has been described above.

[0059] In this embodiment, the rotary damper 1 is installed so that the plate 5 presses the arm portion 19a located downstream in the forward rotation direction N in conjunction with depression of the brake pedal 4, thereby making it possible to generate a strong braking torque in response to depression of the brake pedal 4.

[0060] In addition, the case 11 is made of a thermoplastic resin, and the arm portion 19a, which is located downstream in the forward rotation direction N, of the pair of arm portions 19a, 19b, is provided with a curved portion 191, and the plate 5 rotating in the forward rotation direction N is supported by a support portion 192 located on the tip side of the arm portion 19a relative to the curved portion 191. Therefore, even if a malfunction occurs in the rotary damper 1 and the rotation of the case 11 in the forward rotation direction N relative to the rotor 12 is prevented, the curved portion 191 can be broken by strongly depressing the brake pedal 4, releasing the plate 5 from the support of the arm portion 19a, and the brake master cylinder 6 can be compressed to apply the brakes.

[0061] Furthermore, since the radial cross section of the curved portion 191 has the same shape throughout the entire curved portion 191 with respect to the center of curvature C of the curved portion 191 (see FIG. 5(F)), and the radial width W is constant (see FIG. 5(C)), it is possible to reduce the variation in the brake pedal depression force required to damage the curved portion 191 due to the variation in the pressing direction of the plate 5 applied to the support portion 192.

[0062] Therefore, according to this embodiment, it is possible to provide a rotary damper 1 that is suitable as a damper for a brake pedal having a fail-safe function.

[0063] In the present embodiment, the arm portion 19a has a connecting portion 193 that extends radially outward from the outer circumferential surface 190 of the case 11 and connects to the curved portion 191. This connecting portion 193 ensures a space for the curved portion 191 to bend in the forward rotation direction N. Therefore, even if a malfunction occurs in the rotary damper 1 and the rotation of the case 11 in the forward rotation direction N relative to the rotor 12 is prevented, by strongly depressing the brake pedal 4, the curved portion 191 bends in the forward rotation direction N and the brake pedal 4 moves in the forward rotation direction N, thereby achieving a brake feel that is less uncomfortable.

[0064] Furthermore, according to this embodiment, in the rotary damper 1 that generates a braking torque against an applied rotational force by restricting the movement of the filled viscous fluid, the lid 15 is screwed into the case 11, and the gap G1 between the back surface 153 of the lid 15 and the top surface 129 of the vane 122 can be adjusted by the amount by which the lid 15 is screwed into the case 11. Therefore, the amount of movement of the viscous fluid that moves through the gap G1 can be adjusted with a simple configuration and simple work without increasing the number of parts, to adjust the braking torque generated by rotation.

[0065] Furthermore, according to this embodiment, by disposing axial force generating member 17, which is formed of a plastically or elastically deformable member and applies a reaction force to lid 15, between rear surface 153 of lid 15 and upper surface 119 of partition portion 115, an axial force is generated when lid 15 is screwed into case 11, preventing leakage of viscous fluid from the screwed portion between male thread portion 152 of lid 15 and female thread portion 117 of case 11, while increasing the adjustment margin for gap G1 and widening the adjustment range of the braking torque.

[0066] In this embodiment, the partition 115 has a protrusion 18 on its upper surface 119, and the axial force generating member 17 has a pair of arms 173 that sandwich and grip the protrusion 18. This makes it possible to easily attach the axial force generating member 17 to the partition 115.

[0067] In this embodiment, the axial force generating member 17 is provided with an adjustment portion 174 that is disposed between the pair of arm portions 173, protrudes toward the convex portion 18 provided on the upper surface 119 of the partition portion 115, is inserted into a groove 181 of the convex portion 18, and abuts against a groove bottom 182 of the groove 181, and the groove 181 of the convex portion 18 is sized to allow plastic or elastic deformation of the tip portion 176 of the adjustment portion 174. Therefore, when the lid 15 is screwed into the case 11, the tip portion 176 of the adjustment portion 174 presses the groove bottom 182 of the groove 181 and actively undergoes plastic or elastic deformation, so that the adjustment margin of the gap G1 can be further increased.

[0068] In this embodiment, the pair of arms 173 of the axial force generating member 17 each have a first pressure contact portion 175 that is in pressure contact with a groove 184 formed in both side surfaces 183 of a protrusion 18 formed on the upper surface 119 of the partition portion 115. The first pressure contact portion 175 enables the pair of arms 173 to firmly grip the axial force generating member 17 so that the axial force generating member 17 does not fall off the protrusion 18. The first pressure contact portion 175, together with the grooves 184 formed in both side surfaces 183 of the protrusion 18, also functions as a positioning element when the axial force generating member 17 is attached to the protrusion 18, allowing the axial force generating member 17 to be attached correctly to the protrusion 18.

[0069] In this embodiment, the adjustment portion 174 of the axial force generating member 17 has second pressure contact portions 178 on both side surfaces 179 of the base portion 177, which are in pressure contact with both side walls 185 of the groove 181 of the convex portion 18. The second pressure contact portions 178 allow the adjustment portion 174 to fit into the groove 181 of the convex portion 18, and can more reliably prevent the axial force generating member 17 from falling off from the convex portion 18.

[0070] Furthermore, according to this embodiment, by using a resin with excellent sliding properties such as polyamide for the first sealing material 13 and the second sealing material 14, the first sealing material 13 and the second sealing material 14 function as a sliding bearing that slidably supports the outer peripheral surface 124 of the rotor body 121 of the rotor 12, thereby absorbing rattling caused by eccentricity, etc. of the shaft 2 that transmits external rotational force to the rotor 12, and allowing the shaft 2 to rotate smoothly.

[0071] The present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the present invention.

[0072] For example, in the above embodiment, the gap G1 between the back surface 153 of the lid 15 and the upper surface 129 of the vane 122 is used as a flow path for the viscous fluid other than the flow path 126 formed in the vane 122. However, the present invention is not limited to this. By arranging the axial force generating member 17 so as not to block the gap between the back surface 153 of the lid 15 and the upper surface 119 of the partitioning portion 115, in addition to the gap G1 between the back surface 153 of the lid 15 and the upper surface 129 of the vane 122, the gap between the back surface 153 of the lid 15 and the upper surface 119 of the partitioning portion 115 may be used as a flow path for the viscous fluid other than the flow path 126 formed in the vane 122.

[0073] In the present embodiment, a pair of partitions 115 is provided in the cylindrical chamber 111, and a pair of vanes 122 is provided in the rotor 12. However, the present invention is not limited to this. As long as the number of partitions 115 formed in the cylindrical chamber 111 and the number of vanes 122 formed in the rotor 12 are the same, one or three or more may be formed.

[0074] In addition, in this embodiment, the second seal material 14 attached to the vane 122 has the function of a check valve that opens and closes the flow path 126 formed in the vane 122, but the present invention is not limited to this. Case 11 but Rotor 12 When the vane 122 rotates in the normal direction N relative to the vane 122, the flow passage 126 is blocked. Case 11 but Rotor 12 A check valve that opens a flow passage 126 formed in the vane 122 when the vane 122 rotates in the reverse direction R relative to the second seal member 14 may be provided separately from the second seal member 14.

[0075] In this embodiment, the vane 122 is formed with the flow passage 126 penetrating both side surfaces 127a, 127b of the vane 122 along the rotation direction of the rotor 12, but the present invention is not limited to this. Instead of the vane 122, or together with the vane 122, a flow passage may be formed in the partition 115 penetrating both side surfaces of the partition 115 along the rotation direction of the rotor 12. In this case, Case 11 but Rotor 12When the rotor 11 rotates in the normal direction N relative to the rotor 11, the rotor 11 closes the flow path formed in the partition portion 115, Case 11 but Rotor 12 When the partition portion 115 rotates in a reverse direction R relative to the partition portion 115, a check valve is provided which opens the flow path formed in the partition portion 115.

[0076] When a flow path is formed in the partition portion 115, the first seal material 13 is formed in the same shape as the second seal material 14, that is, Inside The shape may have a bottom having a width wider than the circumferential width of the rim, a first leg integrally formed at one end of the bottom and having a width wider than the radial width of the flow path formed in the partition 115, and a second leg integrally formed at the other end of the bottom and having a width narrower than the radial width of the flow path formed in the partition 115. Case 11 but Rotor 12 When the first seal member 13 rotates in the normal direction N relative to the first seal member 13, the first leg portion of the first seal member 13 comes into contact with one side surface of the partition portion 115, blocking the flow path formed in the partition portion 115. Case 11 but Rotor 12 When rotated in the reverse direction R relative to the first sealant 13, the first leg of the first sealant 13 moves away from one side of the partition portion 115 and the second leg abuts against the other side of the partition portion 115, thereby giving the first sealant 13 the function of a check valve that opens the flow path formed in the partition portion 115.

[0077] Furthermore, if no flow path 126 is formed in the vane 122, the second sealing material 14 may have any shape as long as it can seal the gap between the tip surface 125 of the vane 122 and the side wall surface 114 of the cylindrical chamber 111 of the case 11.

[0078] In the present embodiment, the first seal 13 is attached to the partition 115 provided in the cylindrical chamber 111 of the case 11, but the present invention is not limited to this. The first seal 13 may be omitted. Similarly, the second seal 14 is attached to the vane 122 of the rotor 12, but the second seal 14 may also be omitted.

[0079] In this embodiment, an axial force generating member 17 made of a plastically or elastically deformable member is disposed between the back surface 153 of the lid 15 and the top surface 119 of the partitioning portion 115, so that an axial force is generated when the lid 15 is screwed into the case 11. However, the present invention is not limited to this. The case 11 may be made of a thermoplastic resin, and a convex portion that abuts against the back surface 153 of the lid 15 may be integrally formed with the case 11 as an axial force generating portion on the top surface 119 of the partitioning portion 115. In this case, the axial force generating portion (convex portion) generates an axial force when the lid 15 is screwed into the case 11, and while preventing the viscous fluid from leaking from the screwed portion between the male thread portion 152 of the lid 15 and the female thread portion 117 of the case 11, the axial force generating portion (convex portion) plastically deforms, thereby increasing the adjustment margin of the gap G1 and widening the adjustment range of the braking torque. [Explanation of symbols]

[0080] 1: Rotary damper 2: Shaft 3: Brake arm 4: Brake pedal 5: Plate 6: Brake master cylinder 11: Case 12: Rotor 13: First seal material 14: Second seal material 15: Lid 16a, 16b, 16c: O-rings 17: Axial force generating member 18: Convex portion 111: Cylindrical chamber 19a, 19b: arm portion 112: bottom portion of cylindrical chamber 111 113: Opening of cylindrical chamber 111 114: Side wall surface of cylindrical chamber 111 115: Partition portion 116: Tip surface of partition portion 115 117: Female thread portion 118: Opening side of cylindrical chamber 111 119: Upper surface of partition 115 121: Rotor body 122: vane 123a, 123b: end portions of rotor body 121 124: Outer circumferential surface of rotor body 125: Tip surface of vane 122 126: flow passage 127a, 127b: side surface of vane 122 128: Through hole of rotor body 121 129: Top surface of vane 122 130: bottom of first seal material 13 140: bottom of second seal material 14 141, 142: Ends of the bottom 140 of the second seal material 14 143: First leg of second seal member 14 144: second leg of second seal member 14 150: Opening of the lid 15 151: Outer periphery of the lid 15 152: Male thread portion 153: Underside of lid 15 170: Main body of axial force generating member 17 171: Upper surface of main body 170 172: Lower surface of main body 170; 173: Arm portion 174: Adjustment section 175: First pressure contact section 176: Tip portion of adjustment portion 174 177: Base portion of adjustment portion 174 178: Second pressure contact portion 179: Side surface of base portion 177 180: Upper surface of protrusion 18; 181: Groove; 182: Groove bottom 183: Side surface of protrusion 18; 184: Groove; 185: Side wall of groove 181 190: Outer surface of case 11 191: Curved portion 192: Support portion 193: Connecting part 194: Flat surface 195: Support surface 196: Inner circumferential surface of curved portion 191 197: End of curved portion 191 on the support portion 192 side 198: Outer surface of curved portion 191 199: Base portion between arm portions 19a and 19b 200: The outermost part of the base part 199 201: end of the support surface 195 on the curved portion 191 side

Claims

1. A rotary damper for a brake pedal of an automobile, comprising: a rotor; and a case that accommodates the rotor so as to be capable of rotating relative to the rotor, and that generates a braking torque when the case rotates in a forward rotation direction relative to the rotor, The case is It is made of thermoplastic resin, A pair of arms protruding radially outward sandwich a plate that rotates around a pedal rotation center in conjunction with the brake pedal, Of the pair of arms, the arm located downstream in the forward rotation direction is A curved portion of a constant width; a support portion that is located on the distal side of the curved portion and supports the plate; A rotary damper comprising:

2. 2. The rotary damper according to claim 1, The arm portion located downstream in the forward rotation direction is The case further includes a connecting portion extending radially outward and connecting to the curved portion. A rotary damper comprising:

3. 3. The rotary damper according to claim 1 or 2, The case is a cylindrical chamber filled with a viscous fluid; a partition portion protruding radially inward from a side wall surface of the cylindrical chamber to partition the cylindrical chamber, The rotor is a cylindrical rotor body having an outer circumferential surface adjacent to a tip end surface of the partition portion; a vane that protrudes radially outward from an outer circumferential surface of the rotor body and has a tip surface that is adjacent to a side wall surface of the cylindrical chamber to partition the cylindrical chamber, The rotary damper further includes: a flow passage formed in the partition portion or the vane and penetrating between both side surfaces of the partition portion or the vane along a rotational direction of the rotor; a check valve that closes the flow path when the case rotates in the forward rotation direction relative to the rotor and opens the flow path when the case rotates in the reverse rotation direction relative to the rotor. A rotary damper comprising:

4. 4. The rotary damper according to claim 3, The rotor body further includes at least one of a first seal material that seals a gap between a tip end surface of the partition portion and an outer circumferential surface of the rotor body, and a second seal material that seals a gap between a tip end surface of the vane and a side wall surface of the cylindrical chamber. A rotary damper comprising:

5. A brake system comprising the rotary damper according to any one of claims 1 to 4, A shaft located at the center of pedal rotation; a brake arm rotatably attached to the shaft and connected to a brake master cylinder; A brake pedal attached to an end of the brake arm; a plate attached to the brake arm so as to rotate about a pedal rotation center in conjunction with the brake pedal; The rotary damper includes: The rotor is fixed to the shaft, and the rotation of the rotor around the pedal rotation center is restricted. When the brake pedal is depressed and the plate rotates around the pedal rotation center in the forward rotation direction, the plate is supported by the support portion of the arm portion that is located downstream in the forward rotation direction of the pair of arm portions, and when the brake pedal is released and the plate rotates around the pedal rotation center in the reverse rotation direction, the plate is supported by the arm portion of the pair of arm portions that is located upstream in the forward rotation direction, The plate is The base portion is sandwiched and held by the pair of arms so as not to interfere with the base portion between the pair of arms. A brake system characterized by:

Images