Master cylinder unit

Abstract

Master cylinder unit (12), comprising: a master cylinder (26) which causes a fluid pressure to be generated in a pressure chamber (61) inside a cylinder (32) according to an actuation amount of a brake pedal (11); a container (25) that supplies brake fluid to the pressure chamber (61); a lifting simulator (27) that communicates with the pressure chamber (61) and applies a reaction force to the brake pedal (11) corresponding to an actuation force of the brake pedal (11); and a communication link (141) that causes the main cylinder (26) and the lifting simulator (27) to communicate with each other. wherein the stroke simulator (27) comprises a tubular simulator piston (126) with a base and a simulator cylinder (33) in which the simulator piston (126) moves, wherein a cylinder bore (120) is provided in the simulator cylinder (33), wherein the cylinder bore (120) has a lower cylinder section (121) and a cylinder wall section (122), wherein the simulator piston (126) is arranged such that the lower cylinder section (121) and an opening section (171b) of the simulator piston (126) face each other, wherein a space is formed by the opening section (171b) between an end section of the simulator piston (126) on the lower side and the lower section of the simulator cylinder (33), wherein the communication path (141) comprises a recess section (502) provided in the lower cylinder section (121) and a through-bore (503) which communicates with the recess section (502), wherein the communication path (141) is open via an outer circumferential section and an inner circumferential section of the opening section (171b) of the simulator piston (126), wherein the communication line (141) connects the room and the main cylinder (26), and wherein the through-bore (503) of the communication path (141) is provided such that the communication path (141) extends in a vertical direction from the lower section of the simulator cylinder (33) upwards as it approaches the pressure chamber (61).

Description

[Technical field]

[0001] The present invention relates to a main cylinder unit. [State of the art]

[0002] A braking device is provided which includes a lifting simulator that applies a reaction force to the brake pedal corresponding to a force applied to a brake pedal. [Patent literature 1]

[0003] Japanese unexamined patent application (JP2014-061817 A). It describes a braking device with a bypass oil channel.

[0004] Furthermore, US 6,808,238 B2 is known. This document relates to an actuating unit for an electro-hydraulic brake system of the "brake-by-wire" type, which is designed as a tandem master cylinder, the first and second pistons of which are each biased against the direction of actuation by a return spring. [Subject of the invention][Technical problem]

[0005] The invention aims to simplify a design for venting in a brake system.

[0006] It is an object of the present invention to provide a main cylinder unit in which a design for venting can be simplified. [Technical solution]

[0007] According to the invention, a main cylinder unit is provided with the features according to claim 1 and claim 5. [Advantageous effects of the invention]

[0008] Based on the previously described main cylinder unit, a simplified design for venting is possible. [Brief description of the drawings] Fig. Figure 1 is a view of an embodiment of a brake device comprising a master cylinder unit of a first embodiment. Fig. Figure 2 is a cross-sectional view of the main cylinder unit of the first embodiment. Fig. Figure 3 is a cross-sectional view of an SS cylinder of the main cylinder unit of the first embodiment. Fig. Figure 4 is a partial cross-sectional view of the main cylinder unit of the first embodiment. Fig. Figure 5 is a partial cross-sectional view of the main cylinder unit of the first embodiment. Fig. Figure 6 is a hydraulic circuit diagram of a power module that designs the braking device together with the master cylinder unit of the first embodiment. Fig. Figure 7 is a cross-sectional view of a main cylinder unit of a second embodiment. Fig. Figure 8 is a partial cross-sectional view of the main cylinder unit of the second embodiment. [Description of the embodiments] First embodiment

[0009] A first embodiment is described below with reference to Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5 to Fig. 6 described. A braking device 10, which is in Fig. Figure 1 shows a braking system for a four-wheeled vehicle. The braking system 10 comprises a brake pedal 11, a master cylinder unit 12, a power module 13, a brake cylinder 15VR, a brake cylinder 15HL, a brake cylinder 15HR, and a brake cylinder 15VL. The brake cylinder 15VR is a front right wheel brake cylinder, located in the front right wheel of the four wheels. The brake cylinder 15HL is a rear left wheel brake cylinder, located in the rear left wheel of the four wheels. The brake cylinder 15HR is a rear right wheel brake cylinder, located in the rear right wheel of the four wheels. The brake cylinder 15VL is a front left wheel brake cylinder, located in the front left wheel between the four wheels. The brake cylinders 15VR, 15 HL, 15HR and 15VL are fluid pressure actuation mechanisms such as disc brakes and drum brakes that apply a braking force to the rotation of the wheels.

[0010] The master cylinder unit 12 has an input rod 21 and a stroke sensor 22. A base end of the input rod 21 is connected to the brake pedal 11, and the input rod 21 moves in an axial direction according to the amount of actuation of the brake pedal 11. The stroke sensor 22 detects the amount of movement of the input rod 21. The power module 13 generates brake fluid pressure. Furthermore, the power module 13 controls the brake fluid pressure of each of the brake cylinders 15VR, 15HL, 15HR, and 15VL based on a detection result from the stroke sensor 22 or similar. That is, the braking device 10 is a brake-by-wire braking device. In particular, this braking device 10 is a braking device that incorporates a lateral skid prevention device, which prevents a vehicle from skidding sideways.

[0011] The master cylinder unit 12 comprises a reservoir 25, a master cylinder 26, and a lifting simulator 27. The reservoir 25 contains brake fluid for a brake. The master cylinder 26 is capable of generating a brake fluid pressure corresponding to the actuation force of the brake pedal 11. The master cylinder 26 exchanges the brake fluid with the reservoir 25. The lifting simulator 27 also exchanges the brake fluid with the master cylinder 26. The lifting simulator 27 generates a reaction force corresponding to the actuation force of the brake pedal 11 and applies this reaction force to the brake pedal 11. The reservoir 25 is detachably mounted vertically on the upper side of the master cylinder 26. The lifting simulator 27 is mounted vertically on the lower side of the master cylinder 26. The lifting simulator 27 is integrally formed with the master cylinder 26.

[0012] As in Fig. As shown in Figure 2, the main cylinder unit 12 has a metal cylinder element 31, which is machined and formed from a raw material. This cylinder element 31 is shared by the main cylinder 26 and the lift simulator 27. Within the cylinder element 31, an MC cylinder 32 (cylinder) and an SS cylinder 33 (simulator cylinder) are formed in parallel as a single piece. The MC cylinder 32 forms the main cylinder 26. The SS cylinder 33 forms the lift simulator 27. That is, the main cylinder 26 and the lift simulator 27 are arranged within the cylinder element 31, which is formed in one piece from a raw material.

[0013] In the MC cylinder 32 of the main cylinder 26, a cylinder bore 40 is formed. Therefore, the MC cylinder 32 has a lower cylinder section 41 and a cylinder wall section 42. The lower cylinder section 41 is located on a deep side of the cylinder bore 40. The cylinder wall section 42 has a tubular shape and extends from the lower cylinder section 41 to a cylinder opening 43 on a side opposite the lower cylinder section 41.

[0014] A primary piston 46 is installed on the side of the cylinder wall section 42 that is closer to the cylinder opening 43, allowing it to move axially. The primary piston 46 forms the main cylinder 26 and is made of a metal. Additionally, a secondary piston 47 is installed on the side of the cylinder wall section 42 that is closer to the lower cylinder section 41 than the primary piston 46, also allowing it to move axially. The secondary piston 47 forms the main cylinder 26 and is made of a metal similar to the primary piston 46. As shown in Fig. As shown in Figure 1, the primary piston 46 is arranged in the primary piston 46 and the secondary piston 47 on a side that is closer to the brake pedal 11 than the secondary piston 47. In the primary piston 46 and the secondary piston 47, the secondary piston 47 is arranged on a side opposite the brake pedal 11 of the primary piston 46.

[0015] A pointed end section of the input rod 21 comes into contact with the primary piston 46 on one side opposite the brake pedal 11. The primary piston 46 receives a force applied to the brake pedal 11 via this input rod 21. The primary piston 46 moves inside the MC cylinder 32 in response to the actuation of the brake pedal 11. The stroke sensor 22 is attached to the primary piston 46. The stroke sensor 22 detects the amount of movement of the primary piston 46. Similarly, the stroke sensor 22 detects the amount of movement of the input rod 21, which moves in conjunction with the primary piston 46. That is, the stroke sensor 22 detects the amount of movement of the brake pedal 11.

[0016] As in Fig. As shown in Figure 2, a tubular stop element 51 is screwed into an end section of the cylinder section 42 on one side opposite the lower cylinder section 41. The input rod 21 is inserted through an inner surface of this stop element 51. A flange element 52 is fixed to an intermediate section of the input rod 21. The stop element 51 comes into contact with this flange element 52 from the opposite side of the lower cylinder section 41. Accordingly, the stop element 51 defines a limit position for the movement of the input rod 21 in a direction opposite the lower cylinder section 41. As shown in Figure 2, the stop element 51 is set to a limit position for the input rod 21 in a direction opposite the lower cylinder section 41. Fig. As shown in Figure 1, an expandable cuff 53 is inserted between the stop element 51 and the input rod 21, covering its gap.

[0017] A space between the primary piston 46 and the secondary piston 47 inside the MC cylinder 32 of the master cylinder 26 serves as a primary pressure chamber 56. The pressure in the primary pressure chamber 56 changes according to the movement of the primary piston 46 and the secondary piston 47. A spring assembly 57 is provided between the primary piston 46 and the secondary piston 47. The spring assembly 57 determines the distance between the primary piston 46 and the secondary piston 47 in a non-braking state, i.e., without input from the brake pedal 11. As shown in Fig. As shown in Figure 2, the spring assembly 57 comprises an adjusting ring 58 and a primary piston spring 59. The adjusting ring 58 is expandable within a predetermined range. The primary piston spring 59 is a helical spring that biases the adjusting ring 58 in an expansion direction. The adjusting ring 58 controls the expansion of the primary piston spring 59 so that its maximum length does not exceed a predetermined length. The secondary piston 47, which is connected to the primary piston 46 via the spring assembly 57, also moves inside the MC cylinder 32 in response to actuation of the brake pedal 11. The master cylinder 26 has the primary piston 46 and the secondary piston 47 as the main piston, which move inside the MC cylinder 32 in response to actuation of the brake pedal 11.

[0018] As in Fig. As shown in Figure 1, a space between the secondary piston 47 and the lower cylinder section 41 inside the MC cylinder 32 of the master cylinder 26 serves as a secondary pressure chamber 61 (pressure chamber). The pressure in the secondary pressure chamber 61 changes according to the movement of the secondary piston 47. A spring assembly 62 is provided between the secondary piston 47 and the lower cylinder section 41. The spring assembly 62 determines the distance between the secondary piston 47 and the lower cylinder section 41 in a non-braking state, i.e., without input from the brake pedal 11. As shown in Figure 1, the pressure in the secondary piston 47 changes according to the movement of the secondary piston 47. Fig. As shown in Figure 2, the spring unit 62 comprises an adjusting ring 63 and a secondary piston spring 64. The adjusting ring 63 is expandable within a predetermined range. The secondary piston spring 64 is a helical spring that biases the adjusting ring 63 in the expansion direction. The adjusting ring 63 controls the expansion of the secondary piston spring 64 so that its maximum length does not exceed a predetermined length.

[0019] Both the primary piston 46 and the secondary piston 47 have a plunger shape. The master cylinder 26 is therefore a so-called plunger master cylinder. Furthermore, the master cylinder 26 is a tandem master cylinder, comprising two pistons, namely the primary piston 46 and the secondary piston 47. The present invention is not limited to application to the tandem master cylinder. The present invention need only be applied to a plunger master cylinder and can be applied to any plunger master cylinder, such as a single master cylinder in which one piston is arranged in an MC cylinder, and to a master cylinder comprising three or more pistons.

[0020] A mounting base section 65, projecting upwards in the vertical direction from the cylinder wall section 42 of the master cylinder 26, is formed integrally with the MC cylinder 32. A mounting bore 66 and a mounting bore 67 for securing the container 25 are formed in this mounting base section 65. The mounting bore 66 and the mounting bore 67 are formed such that their positions coincide in a circumferential direction of the cylinder bore 40. The mounting bore 66 and the mounting bore 67 are formed such that their positions differ from each other in an axial direction of the cylinder bore 40. The master cylinder unit 12 is arranged in a vehicle such that the axial direction of the MC cylinder 32, encompassing the cylinder bore 40 of the master cylinder 26, is arranged horizontally along a front / rear direction of the vehicle.The main cylinder unit 12 is arranged in the vehicle in a position in which the lower cylinder section 41 is directed towards the front of the vehicle.

[0021] In the cylinder wall section 42 of the main cylinder 26, a secondary drain section 68 is formed in the vicinity of the lower cylinder section 41. The secondary drain section 68 extends upwards from an upper end position in the vicinity of the lower cylinder section 41 such that its axial centerline is orthogonal to the axial centerline of the cylinder bore 40. Additionally, a primary drain section 69 is formed in the cylinder wall section 42 of the main cylinder 26 on the side that is closer to the cylinder opening 43 than the secondary drain section 68. The axial centerline of the primary drain section 69 is parallel in a direction orthogonal to the axial centerline of the cylinder bore 40 and extends horizontally when the cylinder is inside the vehicle. The secondary drain section 68 and the primary drain section 69 communicate with the power module 13 as indicated by the two-dot dashed line in the diagram. Fig. Figure 1 shows the secondary drain section 68 and the primary drain section 69 communicating with the brake cylinders 15VR, 15HL, 15HR, and 15VL via the power module 13. The secondary drain section 68 and the primary drain section 69 are designed to drain the brake fluid from the secondary pressure chamber 61 and the primary pressure chamber 56 to the brake cylinders 15VR, 15HL, 15HR, and 15VL. The primary pressure chamber 56 and the secondary pressure chamber 61 communicate with the power module 13.

[0022] As in Fig. Figure 2 shows, in order from the lower cylinder section 41, a sliding inner diameter section 70, a large inner diameter section 71, and a screw diameter section 72 formed in an inner circumferential section of the cylinder wall section 42. The sliding inner diameter section 70 has a cylindrical surface-formed inner diameter surface. The large inner diameter section 71 has a cylindrical surface-formed inner diameter surface with a diameter larger than that of the sliding inner diameter section 70. The internal thread section 72 has a diameter larger than that of the sliding inner diameter section 70. The axial centerlines of the inner diameter surfaces of the sliding inner diameter section 70 and the large inner diameter section 71 coincide.These axial centerlines are the axial centerlines of the cylinder bore 40 and the cylinder wall section 42.

[0023] The stroke sensor 22, which is fixed to the primary piston 46, is located inside the large inner diameter section 71. The stroke sensor 22 moves in the axial direction of the MC cylinder 32 inside this large inner diameter section 71. The primary piston 46 and the secondary piston 47 are slidably mounted on the inner diameter surface of the sliding inner diameter section 70. The primary piston 46 and the secondary piston 47 are guided along this inner diameter surface and move in the axial direction of the MC cylinder 32.

[0024] A plurality of circumferential grooves, in particular four, namely a circumferential groove 73, a circumferential groove 74, a circumferential groove 75, and a circumferential groove 76, are formed in this order from the side of the lower cylinder section 41 in the sliding inner diameter section 70. All circumferential grooves 73 to 76 are formed in annular shapes, and all are formed in circular shapes. The circumferential grooves 73 to 76 have a shape that extends radially outward beyond the inner diameter surface of the sliding inner diameter section 70.

[0025] The circumferential groove 73 is located on the side closest to the lower cylinder section 41, between circumferential grooves 73 and 76. The circumferential groove 73 is formed in the vicinity of the mounting bore 66 on the side of the lower cylinder section 41, within the mounting bore 66 and the mounting bore 67. A circular piston seal 81 is arranged inside this circumferential groove 73 to be held in place within it.

[0026] An opening groove 82 is formed on the side closer to the cylinder opening 43 than the circumferential groove 73 in the sliding inner diameter section 70 of the MC cylinder 32. The opening groove 82 extends radially outward beyond the inner diameter surface of the sliding inner diameter section 70 and is formed in an annular shape. The opening groove 82 causes a supply passage 83 to be open inside the cylinder bore 40. The supply passage 83 has a linear shape, with one end open inside the mounting bore 66 on the side of the lower cylinder section 41 and the other end open inside the cylinder bore 40. Here, the positions of the opening groove 82 and the secondary piston 47 overlap axially, and a portion surrounded by them serves as a secondary supply chamber 84.The secondary supply chamber 84 communicates with the container 25 at all times via the supply passage 83 and is formed in a ring shape. Part of the secondary supply chamber 84 is formed by the secondary piston 47.

[0027] An axial groove 85 is formed in an upper section of the MC cylinder 32 on the side that is closer to the lower cylinder section 41 than the circumferential groove 73 of the sliding inner diameter section 70. The axial groove 85 is open to the circumferential groove 73 and extends linearly from the circumferential groove 73 to the lower cylinder section 41. The axial groove 85 is formed to be recessed radially outward beyond the inner diameter surface of the sliding inner diameter section 70. This axial groove 85 forms a roof portion of the secondary pressure chamber 61 between the secondary piston 47 and the lower cylinder section 41. The axial groove 85 is formed to allow the secondary drain section 68 and the circumferential groove 73 to communicate with each other via the secondary pressure chamber 61. The secondary drain section 68 is formed at a position between the lower cylinder section 41 and the circumferential groove 73 and in the vicinity of the lower cylinder section 41.The secondary drain section 68 is formed at an upper end position of the axial groove 85. The secondary drain section 68 extends upwards from an upper end position of the secondary pressure chamber 61.

[0028] In the sliding inner diameter section 70 of the MC cylinder 32, the circumferential groove 74 is formed on one side opposite the circumferential groove 73 of the opening groove 82, i.e., the cylinder opening side 43. A circular dividing seal 86 is arranged inside this circumferential groove 74 in order to be held in the circumferential groove 74.

[0029] In the sliding inner diameter section 70 of the MC cylinder 32, the circumferential groove 75 is formed in the vicinity of the mounting bore 67 on the side of the cylinder opening 43. A circular piston seal 91 is arranged inside this circumferential groove 75 in order to be held in the circumferential groove 75.

[0030] An opening groove 92 is formed on the side closer to the cylinder opening 43 of the circumferential groove 75 in the sliding inner diameter section 70 of the MC cylinder 32. The opening groove 92 extends radially outward beyond the inner diameter surface of the sliding inner diameter section 70 and is formed in an annular shape. The opening groove 92 causes a supply passage 93 to be open inside the cylinder bore 40. The supply passage 93 has a linear shape, with one end open inside the mounting bore 67 on the side of the cylinder opening 43 and the other end open inside the cylinder bore 40. Here, the positions of the opening groove 92 and the primary piston 46 overlap in the axial direction, and a portion surrounded by them serves as a primary supply chamber 94.The primary supply chamber 94 communicates with the container 25 at all times via the supply passage 93 and is formed in an annular shape. Part of the primary supply chamber 94 is formed by the primary piston 46. The main cylinder 26 comprises the secondary supply chamber 84 and the primary supply chamber 94 as main supply chambers, which are connected to the container 25 at all times.

[0031] An axial groove 95 is formed in an upper section of the MC cylinder 32 on the side that is closer to the lower cylinder section 41 than the circumferential groove 75 of the sliding inner diameter section 70. The axial groove 95 is open to the circumferential groove 75 and extends linearly from the circumferential groove 75 to the side of the lower cylinder section 41. The axial groove 95 is open to the circumferential groove 74. The axial groove 95 is recessed radially outward beyond the inner diameter surface of the sliding inner diameter section 70. This axial groove 95 forms a ceiling portion of the primary pressure chamber 56 between the primary piston 46 and the secondary piston 47. The axial groove 95 is formed to allow the primary drain section 69 and the circumferential groove 75 to communicate with each other via the primary pressure chamber 56. The primary drain section 69 is formed at a position between the circumferential groove 74 and the circumferential groove 75 and in the vicinity of the circumferential groove 74.The primary drain section 69 is formed at an upper end position of the axial groove 95. The primary drain section 69 extends laterally from the upper end position of the primary pressure chamber 56.

[0032] In the sliding inner diameter section 70 of the MC cylinder 32, the circumferential groove 76 is formed on one side opposite the circumferential groove 75 of the opening groove 92, i.e., the cylinder opening 43. A circular dividing seal 96 is arranged inside this circumferential groove 76 in order to be held in the circumferential groove 76.

[0033] The secondary piston 47 is located on the side closer to the lower cylinder section 41 than the primary piston 46 of the MC cylinder 32. The secondary piston 47 comprises a cylindrical section 101 and a lower section 102, which is formed at an intermediate position of the cylindrical section 101 in the axial direction, and has a plunger shape. The cylindrical section 101 of the secondary piston 47 is attached to the sliding inner diameter section 70 of the MC cylinder 32, the piston seal 81 provided in the sliding inner diameter section 70, and the subdivision seal 86. The secondary piston 47 is guided by these components and is displaceable within the MC cylinder 32.

[0034] A plurality of ports 103 is formed on the end section of the cylindrical section 101 on the side closer to the lower cylinder section 41. The plurality of ports 103 penetrates radially into the cylindrical section 101. Within the cylindrical section 101, the plurality of ports 103 are arranged radially at positions with equal intervals in the circumferential direction. The spring assembly 62 is inserted into the secondary piston 47 on the side of the lower cylinder section 41 of the cylinder section 101. In the spring assembly 62, one end of the adjusting ring 63 comes into axial contact with the lower section 102 of the secondary piston 47, and the other end of the adjusting ring 63 comes into axial contact with the lower cylinder section 41 of the MC cylinder 32.The secondary piston spring 64 determines the distance between the secondary piston 47 and the lower cylinder section 41 in a non-braking state, which has no input from the input rod 21. The secondary piston spring 64 is reduced in length when there is input from the input rod 21 and pre-tensions the secondary piston 47 towards the cylinder opening 43 using a force corresponding to the reduced length.

[0035] Here, a section surrounded by the lower cylinder section 41, the side of the lower cylinder section 41 of the cylinder wall section 42, and the secondary piston 47 serves as the secondary pressure chamber 61. The secondary pressure chamber 61 generates a brake fluid pressure according to the amount of actuation of the brake pedal 11 and delivers the brake fluid pressure to the secondary discharge section 68. In other words, the master cylinder 26 causes a fluid pressure to be generated in the secondary pressure chamber 61 inside the MC cylinder 32 according to the amount of actuation of the brake pedal 11. This secondary pressure chamber 61 communicates with the secondary supply chamber 84, that is, the reservoir 25, when the secondary piston 47 is in a position where the ports 103 to the opening groove 82 are open. The secondary piston 47 causes the ports 103 to be open to the opening groove 82 when the brake pedal 11 is not actuated.In other words, the secondary supply chamber 84, encompassed by the master cylinder 26, is always connected to and communicates with the reservoir 25 and the secondary pressure chamber 61 when the brake pedal 11 is not depressed. The reservoir 25 thus stores brake fluid, which is supplied to the secondary pressure chamber 61. The reservoir 25 supplies the brake fluid to the secondary pressure chamber 61.

[0036] The subdivision seal 86, which is held by the circumferential groove 74 of the MC cylinder 32, is a one-piece molded product made of synthetic rubber. The subdivision seal 86 is a cup-shaped sleeve whose shape, on one side of a radial cross-section encompassing its centerline, is C-shaped. The subdivision seal 86 is arranged inside the circumferential groove 74, in which a lip portion is positioned to face the cylinder opening 43. In the subdivision seal 86, the inner circumference is in sliding contact with an outer circumferential surface of the secondary piston 47, and the outer circumference comes into contact with the circumferential groove 74 of the MC cylinder 32. Accordingly, the subdivision seal 86 seals the gap at the position of the subdivision seal 86 between the secondary piston 47 and the MC cylinder 32 at all times.

[0037] The piston seal 81, which is held by the circumferential groove 73 of the MC cylinder 32, is a one-piece molded product made of synthetic rubber such as EPDM. The piston seal 81 is a cup-shaped seal whose shape, on one side of a radial cross-section encompassing its centerline, is E-shaped. The piston seal 81 is located inside the circumferential groove 73, in which a lip portion is positioned to face the lower cylinder section 41. In the piston seal 81, the inner circumference is in sliding contact with the outer circumferential surface of the secondary piston 47, and the outer circumference comes into contact with the circumferential groove 73 of the MC cylinder 32. Accordingly, the piston seal 81 is able to seal the gap at the position of the piston seal 81 between the secondary piston 47 and the MC cylinder 32.

[0038] The secondary piston 47 is in a non-braking position, in which the ports 103 are open to the opening groove 82 when there is no input from the input rod 21. The piston seal 81 partially overlaps the ports 103 in the axial direction when the secondary piston 47 is in a non-braking position, as shown in Fig. 2 shown. In this state, the secondary pressure chamber 61 and the container 25 communicate with each other via the secondary supply chamber 84 and the connections 103.

[0039] In response to an input from the input rod 21, the primary piston 46 moves towards the lower cylinder section 41 along its axial direction. Consequently, the secondary piston 47 is pushed by the primary piston 46 via the spring unit 57 and moves towards the lower cylinder section 41 along its axial direction. That is, the primary piston 46 moves linearly inside the MC cylinder 32 in response to a force applied to the brake pedal 11, as shown in Fig. 1. The secondary piston 47 also moves linearly inside the MC cylinder 32 in response to a force applied to the brake pedal 11.

[0040] In this case, as in Fig. Figure 2 shows the secondary piston 47 on the inner circumference of the sliding inner diameter section 70 of the MC cylinder 32, and on the inner circumference of the piston seal 81 and the subdivision seal 86, which are held by the MC cylinder 32. As the secondary piston 47 moves toward the lower cylinder section 41, the ports 103 are in a state where they are positioned closer to the side of the lower cylinder section 41 than the piston seal 81. In this state, the piston seal 81 is in a position to seal a gap between the reservoir 25 and the secondary supply chamber 84 and the secondary pressure chamber 61. Consequently, as the secondary piston 47 moves further toward the lower cylinder section 41, the brake fluid inside the secondary pressure chamber 61 is pressurized. The brake fluid, which is pressurized inside the secondary pressure chamber 61, is drained from the secondary drain section 68.

[0041] When the input from the input rod 21 is reduced from a state in which the brake fluid inside the secondary pressure chamber 61 is pressurized, the secondary piston 47 tends to return to the side of the cylinder opening 43 due to a preload force of the secondary piston spring 64 of the spring assembly 62. The capacity of the secondary pressure chamber 61 increases as a result of this movement of the secondary piston 47. In this case, the return of the brake fluid to the secondary pressure chamber 61 via the secondary drain section 68 sometimes no longer follows the increase in the capacity of the secondary pressure chamber 61. Consequently, after the fluid pressure of the secondary supply chamber 84, which is atmospheric pressure, and the fluid pressure of the secondary pressure chamber 61 have become equal, the fluid pressure inside the secondary pressure chamber 61 becomes a vacuum.

[0042] Consequently, due to this negative pressure inside the secondary pressure chamber 61, the piston seal 81 is deformed, and a gap is formed between the piston seal 81 and the circumferential groove 73. The brake fluid from the secondary supply chamber 84 then passes through this gap and is supplied to the secondary pressure chamber 61. As a result, the fluid pressure in the secondary pressure chamber 61 increases as it returns from the state of negative pressure to atmospheric pressure. In other words, the piston seal 81 acts as a bottom valve, allowing the brake fluid from the secondary supply chamber 84 to flow into the secondary pressure chamber 61 and regulating the flow of brake fluid in the opposite direction.

[0043] The primary piston 46 is located on the side closer to the cylinder opening 43 than the secondary piston 47 of the MC cylinder 32. The primary piston 46 comprises a cylindrical section 106 and a lower section 107, which is formed at an intermediate position of the cylindrical section 106 in the axial direction, and has a plunger shape. The primary piston 46 is attached to the sliding inner diameter section 70 of the MC cylinder 32, the piston seal 91 provided in the sliding inner diameter section 70, and the subdivision seal 96. The primary piston 46 is guided by these components and moves within the MC cylinder 32. The input rod 21 is inserted into the cylindrical section 106. The lower section 107 is pushed by this input rod 21, and the primary piston 46 moves forward toward the lower cylinder section 41.

[0044] A plurality of ports 108 is formed on the side of the lower cylinder section 41 of the cylindrical section 106. The plurality of ports 108 penetrates radially into the cylindrical section 106. The plurality of ports 108 is formed radially in the cylindrical section 106 at positions that have equal intervals in the circumferential direction. The spring assembly 57 is provided on the side of the secondary piston 47 of the primary piston 46. The spring assembly 57 determines the distance between the primary piston 46 and the secondary piston 47 in a non-braking state, which has no input from the input rod 21. In the spring assembly 57, the adjusting ring 58 comes into contact with the lower section 102 of the secondary piston 47 and the lower section 107 of the primary piston 46.The primary piston spring 59 is shortened when input is applied from the input rod 21, and the distance between the primary piston 46 and the secondary piston 47 is reduced. The primary piston spring 59 pre-tensions the primary piston 46 against the input rod 21 using a force corresponding to the reduced length.

[0045] Here, a section formed by being surrounded by the cylinder wall section 42, the primary piston 46, and the secondary piston 47 of the MC cylinder 32 serves as the primary pressure chamber 56. The primary pressure chamber 56 generates a brake fluid pressure according to the amount of actuation of the brake pedal 11 and delivers the brake fluid to the primary drain section 69. In other words, the master cylinder 26 causes a fluid pressure to be generated in the primary pressure chamber 56 inside the MC cylinder 32 according to the amount of actuation of the brake pedal 11. Moreover, the primary piston 46, in other words, forms the primary pressure chamber 56 for supplying fluid pressure to the primary drain section 69 between the secondary piston 47 and the MC cylinder 32. This primary pressure chamber 56 communicates with the primary supply chamber 94, that is, the reservoir 25, when the primary piston 46 is in a position where the ports 108 to the opening groove 92 are open, as shown in Fig. Figure 2 shows that the primary piston 46 causes the ports 108 to be open to the opening groove 92 when the brake pedal 11 is not depressed. In other words, the primary supply chamber 94, encompassed by the master cylinder 26, is always connected to and communicating with the reservoir 25 and the primary pressure chamber 56 when the brake pedal 11 is not depressed. The reservoir 25 thus stores brake fluid, which is supplied to the primary pressure chamber 56. The reservoir 25 supplies the brake fluid to the primary pressure chamber 56.

[0046] The subdivision seal 96, which is held by the circumferential groove 76 of the MC cylinder 32, is a component common to the subdivision seal 86, which is a one-piece molded product made of synthetic rubber. The subdivision seal 96 is a cup-shaped sleeve whose shape, on one side of a radial cross-section encompassing its centerline, is C-shaped. The subdivision seal 96 is arranged inside the circumferential groove 76, in which a lip portion is positioned facing the side of the lower cylinder section 41. In the subdivision seal 96, the inner circumference is in sliding contact with the outer circumferential surface of the moving primary piston 46, and the outer circumference comes into contact with the circumferential groove 76 of the MC cylinder 32. Accordingly, the subdivision seal 96 seals the gap at the position of the subdivision seal 96 of the primary piston 46 and the MC cylinder 32 at all times.

[0047] The piston seal 91, which is held by the circumferential groove 75 of the MC cylinder 32, is a component common to the piston seal 81 and is a one-piece molded product made of synthetic rubber such as EPDM. The piston seal 91 is a cup-shaped seal whose shape, on one side of a radial cross-section encompassing its centerline, is E-shaped. The piston seal 91 is located inside the circumferential groove 75, in which a lip portion is positioned to be guided to the lower cylinder section 41. In the piston seal 91, the inner circumference is in sliding contact with the outer circumferential surface of the primary piston 46, and the outer circumference comes into contact with the circumferential groove 75 of the MC cylinder 32. Accordingly, the piston seal 91 can seal the gap at the position of the piston seal 91 between the primary piston 46 and the MC cylinder 32.

[0048] The primary piston 46 is in a non-braking position, in which the ports 108 to the opening groove 92 are open when there is no input from the input rod 21. The piston seal 91 partially overlaps the ports 108 of the primary piston 46 in the axial direction when the primary piston 46 is in a non-braking position. In this state, the primary pressure chamber 56 and the reservoir 25 communicate with each other via the primary supply chamber 94 and the ports 108.

[0049] In response to input from the input rod 21, the primary piston 46 moves towards the lower cylinder section 41 along its axial direction. In this case, the primary piston 46 moves on the inner circumference of the sliding inner diameter section 70 of the MC cylinder 32, and on the inner circumference of the piston seal 91 and the subdivision seal 96, which are held by the MC cylinder 32. As the primary piston 46 moves towards the lower cylinder section 41, the ports 108 are positioned closer to the side of the lower cylinder section 41 than the piston seal 91. In this state, the piston seal 91 is in a position to seal a gap between the reservoir 25 and the primary supply chamber 94 and the primary pressure chamber 56.Consequently, as the primary piston 46 moves further towards the lower cylinder section 41, the brake fluid inside the primary pressure chamber 56 is pressurized. The pressurized brake fluid inside the primary pressure chamber 56 is then discharged from the primary drain section 69.

[0050] When the input from the input rod 21 is reduced from a state in which the brake fluid inside the primary pressure chamber 56 is pressurized, the primary piston 46 tends to return to one side opposite the lower cylinder section 41 due to a preload force of the primary piston spring 59 of the spring assembly 57. The capacity of the primary pressure chamber 56 increases as a result of this movement of the primary piston 46. In this case, the return of the brake fluid via the primary drain section 69 sometimes no longer follows the increase in the capacity of the primary pressure chamber 56. Consequently, once the fluid pressure of the primary supply chamber 94, which is atmospheric pressure, and the fluid pressure of the primary pressure chamber 56 have equalized, the fluid pressure inside the primary pressure chamber 56 becomes a vacuum.

[0051] Consequently, due to this negative pressure inside the primary pressure chamber 56, the piston seal 91 is deformed, and a gap is formed between the piston seal 91 and the circumferential groove 75. The brake fluid from the primary supply chamber 94 then passes through this gap and is fed into the primary pressure chamber 56. As a result, the fluid pressure in the primary pressure chamber 56 increases as it returns from the state of negative pressure to atmospheric pressure. In other words, the piston seal 91 acts as a bottom valve, allowing the brake fluid from the primary supply chamber 94 to flow into the primary pressure chamber 56 and regulating the flow of brake fluid in the opposite direction.

[0052] A cylinder bore 120, parallel to the cylinder bore 40 of the MC cylinder 32, is formed in the SS cylinder 33 of the lifting simulator 27. Therefore, the SS cylinder 33 comprises a lower cylinder section 121 (lower section of the simulator cylinder) and a cylinder wall section 122. The lower cylinder section 121 is located on a deep side within the cylinder bore 120. The cylinder wall section 122 has a tubular shape and extends from the lower cylinder section 121 to a cylinder opening 123 on a side opposite the lower cylinder section 121. The main cylinder unit 12 is arranged in a vehicle such that the axial direction of the SS cylinder 33, comprising the cylinder bore 120 of the lifting simulator 27, is horizontal along a front / rear direction of the vehicle.The main cylinder unit 12 is arranged in the vehicle in a position where the lower cylinder section 121 faces the front of the vehicle. The cylinder bore 40 and the cylinder bore 120 are formed on the same side surface of the cylinder element 31, and the positions of their axial centerlines coincide in a horizontal direction. In other words, the axial centerline of the cylinder bore 120 is arranged parallel to the axial centerline of the cylinder bore 40, vertically below it. The position of the cylinder opening 123 of the SS cylinder 33 partially coincides axially with that of the cylinder opening 43 of the MC cylinder 32. The position of the lower cylinder section 121 of the SS cylinder 33 deviates axially towards the side that is closer to the cylinder openings 43 and 123 than the lower cylinder section 41 of the MC cylinder 32.

[0053] An SS piston 126 (simulator piston) is movably installed on the side closer to the lower cylinder section 121 in the cylinder wall section 122. The SS piston 126 forms the stroke simulator 27 and is made of metal. The SS piston 126 moves inside the SS cylinder 33. The SS cylinder 33 is a part in which the SS piston 126 moves within the stroke simulator 27. Furthermore, a reaction force generation mechanism 127 is located in Fig. 4 is shown, on the side that is closer to the cylinder opening 123 than the SS piston 126 inside the cylinder wall section 122. As in Fig. As shown in Figure 2, the reaction force generation mechanism 127 pre-tensions the SS piston 126 to the lower cylinder section 121.

[0054] Starting from the side of the lower cylinder section 121, a sliding inner diameter section 130, an intermediate inner diameter section 131, a large inner diameter section 132, and an internal thread section 133 are formed in the inner circumferential section of the cylinder wall section 122. The sliding inner diameter section 130 has a cylindrical surface-formed inner diameter surface. The intermediate inner diameter section 131 has a cylindrical surface-formed inner diameter surface with a diameter larger than that of the sliding inner diameter section 130. In the large inner diameter section 132, the inner diameter surface has a diameter larger than that of the intermediate inner diameter section 131.The axial centerlines of the inner diameter surfaces of the sliding inner diameter section 130, the intermediate inner diameter section 131, and the large inner diameter section 132 coincide. These axial centerlines are the axial centerlines of the cylinder bore 120 and the cylinder wall section 122.

[0055] A plurality of circumferential grooves, in particular two, namely a circumferential groove 136 and a circumferential groove 137, are formed in this order from the side of the lower cylinder section 121 onto the sliding inner diameter section 130. Both circumferential grooves 136 and 137 are formed in annular shapes, and both are formed in circular shapes. The circumferential grooves 136 and 137 have a shape that extends radially outward beyond the inner diameter surface of the sliding inner diameter section 130.

[0056] A communication path 141 is formed at a position adjacent to the cylinder section 122 and the lower cylinder section 121. The communication path 141 extends upwards from an upper end section of the cylinder bore 120 adjacent to the lower cylinder section 121 and is open inside the secondary pressure chamber 61 of the main cylinder 26. In other words, the communication path 141 enables the cylinder bore 40 and the cylinder bore 120 to communicate with each other. Furthermore, in other words, the lift simulator 27 communicates with the secondary pressure chamber 61 via the communication path 141. The communication path 141 enables the main cylinder 26 and the lift simulator 27 to communicate with each other. The communication path 141 is connected to the lower cylinder section 121.

[0057] A vent passage 142 is formed in the cylinder wall section 122.

[0058] The vent passage 142 is open at an upper section of the intermediate inner diameter section 131 on the side closer to the sliding inner diameter section 130. The vent passage 142 extends to a position on an outer surface of the cylinder element 31. A vent plug (not shown) for opening and closing the vent passage 142 is located in this part of the vent passage 142. The vent plug switches the vent passage 142 open to outside air in an open state and blocks the vent passage 142 from outside air in a closed state. As indicated by the two-dot dashed line in Fig. As shown in Figure 1, the vent passage 142 also communicates with the power module 13.

[0059] As in Fig. As shown in Figure 2, a circular subdivision seal 151 (sealing element) is arranged inside the circumferential groove 136 (annular groove) to be held in the circumferential groove 136. The subdivision seal 151 also forms the stroke simulator 27. The subdivision seal 151 is arranged on the side of the SS cylinder 33 in the SS cylinder 33 and the SS piston 126. The subdivision seal 151 is possibly arranged here on the side of the SS piston 126 in the SS cylinder 33 and the SS piston 126.

[0060] An axial groove 152 (recess section) is formed in an upper section of the SS cylinder 33 on the side that is closer to the lower cylinder section 121 than the circumferential groove 136 of the sliding inner diameter section 130. The axial groove 152 is open to the circumferential groove 136 and extends linearly from the circumferential groove 136 to the lower cylinder section 121. The axial groove 152 is a recess section that extends radially outward beyond the inner diameter surface of the sliding inner diameter section 130. As shown in Fig. As shown in Figure 3, a lower main surface 121a, which has the largest area on the lower surface, is formed in the lower cylinder section 121 and is a flat surface orthogonal to the axial centerline of the cylinder bore 120, as shown in Fig. 2 shown. The axial groove 152 is formed by the circumferential groove 136 at a position that is somewhat closer to the cylinder opening 123 than the position of this lower main surface 121a.

[0061] In the sliding inner diameter section 130 of the SS cylinder 33, the circumferential groove 137 is formed in the vicinity of the end section that is closer to the cylinder opening 123. A circular subdivision seal 161 is arranged inside this circumferential groove 137 to be held in the circumferential groove 137. The subdivision seal 161 is arranged on the side of the SS cylinder 33 in the SS cylinder 33 and the SS piston 126. The subdivision seal 161 may also be arranged on the side of the SS piston 126 in the SS cylinder 33 and the SS piston 126.

[0062] In the subdivision seals 151 and 161, the subdivision seal 151 is positioned on the front side of the subdivision seal 161 (forward direction of movement) at the time the brake pedal 11 is pressed, in the direction of travel of the input rod 21, the primary piston 46, and the secondary piston 47. The subdivision seal 161 is also positioned on the rear side of the subdivision seal 151 (reverse direction of movement) at the time the brake pedal 11 is pressed, in the direction of travel of the input rod 21, the primary piston 46, and the secondary piston 47.

[0063] An axial groove 165 is formed in an upper section of the SS cylinder 33 on the side that is closer to the cylinder opening 123 than the circumferential groove 137 of the sliding inner diameter section 130. One end of the axial groove 165 is open to the circumferential groove 137 and extends linearly from the circumferential groove 137 to the cylinder opening 123. The axial groove 165 is formed to be recessed radially outward beyond the inner diameter surface of the sliding inner diameter section 130.

[0064] As in Fig. As shown in Figure 3, in the axial groove 152, the cross-sectional shape of a surface orthogonal to the axial centerline of the sliding inner diameter section 130 is an arc. This arc has a diameter smaller than that of the inner diameter surface of the sliding inner diameter section 130. The axial groove 152 is an eccentric groove in which the center of the arc is offset with respect to the center of the inner diameter surface of the sliding inner diameter section 130. Similarly, the axial groove 165 is also an eccentric groove in which the cross-sectional shape of a surface orthogonal to the axial centerline of the sliding inner diameter section 130 is an arc, having a diameter smaller than that of the inner diameter surface of the sliding inner diameter section 130 (not shown).The axial grooves 85 and 95 of the main cylinder 26 are also eccentric grooves in which the shape of a cross-section on a surface orthogonal to the axial centerline of the sliding inner diameter section 70 is also an arc shape having a diameter smaller than that of the inner diameter surface of the sliding inner diameter section 70.

[0065] As in Fig. As shown in Figure 5, the communication section 141 is formed from a through-bore 501, a recess section 502, and a through-bore 503. The through-bore 501 is linear and extends downwards in the vertical direction from the cylinder bore 40. The through-bore 501 has a circular cross-sectional shape and is formed on the same straight line as the secondary drain section 68. The through-bore 501 is coaxial with the secondary drain section 68 and has the same diameter. Thus, the secondary drain section 68 and the through-bore 501 are formed by a bore opening that is made once using a drilling tool. In the through-bore 501, the axial centerline, similar to that of the secondary drain section 68, is also orthogonal to the axial centerline of the cylinder bore 40.

[0066] As in Fig. As shown in Figure 3, the recess section 502 has a circular cross-sectional shape with a diameter slightly smaller than the diameter of the axial groove 152. As shown in Fig. As shown in Figure 2, the recess section 502 is provided in the upper section of the cylinder bore 120. The recess section 502 extends on one side opposite the cylinder opening 123 beyond an end face 152a of the axial groove 152 and the lower main surface 121a of the lower cylinder section 121. The position of the axial centerline of the recess section 502 in the horizontal direction overlaps the positions of the axial centerline of the inner diameter surface of the sliding inner diameter section 130 and the axial centerline of the axial groove 152. The axial centerline of the recess section 502 is inclined with respect to the axial centerline of the cylinder bore 120 to be closer to the axial centerline of the cylinder bore 40 of the main cylinder 26 when the axial centerline is farther from the cylinder opening 123. The recess section 502 is formed by an end mill which is inserted through the cylinder opening 123.A lower surface 502a of the recess section 502 is formed orthogonally to the axial center line of the recess cutout 502.

[0067] The through-bore 503 is formed linearly in the upper section of the recess section 502 and extends from the lower surface 502a to a side opposite the cylinder opening 123. The through-bore 503 communicates with the through-bore 501. The through-bore 503 has a circular cross-sectional shape. The position of the axial centerline of the through-bore 503 overlaps, in the horizontal direction, the positions of the axial centerline of the inner diameter surface of the sliding inner diameter section 130 and the axial centerline of the axial groove 152. The axial centerline of the through-bore 503 is parallel to the axial centerline of the recess section 502.This means that the axial centerline of the through-bore 503 is inclined relative to the axial centerline of the cylinder bore 120 to be closer to the axial centerline of the cylinder bore 40 of the main cylinder 26 when the axial centerline is farther from the cylinder opening 123. The through-bore 503 is formed by a drill or similar tool that is inserted through the cylinder opening 123. During this process, a tip section of the drill moves forward within a region of the through-bore 501 and then moves backward.

[0068] Here, the axial centerline of the cylinder bore 120 is horizontally oriented. Therefore, the recess section 502 and the through-bore 503 are inclined to be positioned vertically on their upper side when the recess section 502 and the through-bore 503 are further away from the cylinder opening 123. The axial groove 152 communicates with the recess section 502. Thus, the axial groove 152 communicates with the communication path 141, which is formed from the recess section 502 and the through-bores 501 and 503. The lower cylinder section 121, to which the communication path 141 is connected, is recessed in the axial direction of the SS cylinder 33 compared to a section to which the communication path 141 is not connected. In the lower cylinder section 121, to which the communication line 141 is connected, the communication line 141 formed therein extends radially outwards.

[0069] The SS piston 126 has a cylindrical section 171, a lower piston section 172 (lower simulator piston section) formed at an intermediate position of the cylindrical section 171 in the axial direction, and a projecting section 173 extending axially from the lower piston section 172. The lower piston section 172 deviates laterally from the center of the cylindrical section 171 in the axial direction. The projecting section 173 extends from the lower piston section 172 in the same direction as the lower piston section 172 deviates from the center of the cylindrical section 171. An end section of the cylindrical section 171 on one side opposite the projecting section 173 is a piston opening 171b (opening section of the simulator piston) in an open state. The SS piston 126 has a tubular shape with a base, in other words a plunger shape.In the SS piston 126, the cylindrical section 171 is attached to both the sliding inner diameter section 130 of the SS cylinder 33 and to the dividing seals 151 and 161 provided in the sliding inner diameter section 130. The SS piston 126 is guided by these seals and moves within the SS cylinder 33. In this case, both dividing seals 151 and 161 seal an annular gap between the inner circumference of the SS cylinder 33 and the outer circumference of the SS piston 126. The dividing seals 151 and 161 are located between the outer circumference section of the SS piston 126 and the SS cylinder 33. The SS piston 126 is arranged in the SS cylinder 33 such that its piston opening 171b faces the lower cylinder section 121. In the SS piston 126, the lower piston section 172 is formed on the side that is closer to the cylinder opening 123 than the center of the cylindrical section 171 in the axial direction.The projecting section 173 extends from the lower piston section 172 to the cylinder opening 123. The dividing seal 151 divides the lower piston section 172 and the piston opening 171b in the SS piston 126. In the SS cylinder 33, the axial groove 152 is provided in a portion that is closer to the lower piston section 172 than to the lower cylinder section 121. The axial groove 152 is a recessed section that extends radially outward beyond the side of the piston opening 171b in the SS cylinder 33. The axial groove 152 extends from the dividing seal 151 to the lower cylinder section 121. Ports that penetrate radially into the cylindrical section 171 are not formed in the SS piston 126.

[0070] As in Fig. As shown in Figure 5, in the SS piston 126, an end surface 171a of the cylindrical section 171, which is near the lower cylindrical section 121, is a flat surface along a direction orthogonal to the axis and has a circular shape. The SS piston 126 comes into surface contact with the lower main surface 121a of the lower cylindrical section 121 on this end surface 171a. An end edge section 502b at the boundary with respect to the lower main surface 121a of the recess section 502 is a position that radially intersects the end surface 171a of the cylindrical section 171 of the SS piston 126, as shown in Figure 5. Fig. 3 shown. Thus, although the SS piston 126 is in a state of being in contact with the lower cylinder section 121, as shown in Fig. As shown in Figure 5, the communication path 141, comprising the recess section 502, is simultaneously open to and communicates with both an inner and an outer circumferential side of the SS piston 126. Consequently, even though the SS piston 126 is in a state of contact with the lower cylindrical section 121, the communication path 141 causes the axial groove 152 and the interior of the cylindrical section 171 to communicate with each other. That is, the communication path 141, comprising the recess section 502, communicates with both the inner and outer circumferential sides of the SS piston 126 at all times, regardless of the position of the SS piston 126. The communication path 141 causes the axial groove 152 and the interior of the cylindrical section 171 to communicate with each other at all times. Here, the boundary between the through-hole 503 and the lower surface 502a of the recess section 502 is an end-edge section 503a.The end edge section 503a is also at a position that radially crosses the end surface 171a of the cylindrical section 171 of the SS piston 126, as shown in . Fig. 3 shown. As in Fig. As shown in Figure 2, the recess section 502 and the through-hole 503 are inclined to be positioned on their upper side in the vertical direction when the recess section 502 and the through-hole 503 are further away from the cylinder opening 123. The through-hole 501 extends vertically upwards from the through-hole 503. Thus, the communication path 141 is designed such that it extends vertically upwards from the lower cylinder section 121 as it approaches the secondary pressure chamber 61.

[0071] As previously described, the communication link 141 includes the one in Fig. Figure 5 shows the recess section 502, the through-bore 503, and the through-bore 501 in the lower cylinder section 121. The lower cylinder section 121 is an facing section that faces the tip end section of the SS piston 126 in the SS cylinder 33. The lower cylinder section 121 faces an opening section 171b of the SS piston 126. The recess section 502 is designed to be recessed in a direction away from the tip end section of the SS piston 126. The through-bore 503 extends linearly from the recess section 502. The through-bore 501 has a linear shape in which one end is perpendicularly connected to the MC cylinder 32 and the other end is connected to the through-bore 503. The communication path 141 is open over the outer circumferential section and the inner circumferential section of the piston opening 171b and is connected to the lower cylinder section 121.The through-hole 501 may be slightly inclined with respect to the vertical state, instead of being perpendicular to the MC cylinder 32. That is to say, the through-hole 501 only needs to be connected to the MC cylinder 32 in a substantially perpendicular manner.

[0072] Here, a section formed by the lower cylinder section 121, a side of the cylinder wall section 122 that is closer to the lower cylinder section 121, and the SS piston 126 serves as an SS pressure chamber 181. The SS pressure chamber 181 communicates with the secondary pressure chamber 61 of the main cylinder 26 via the communication path 141. Accordingly, the pressure in the SS pressure chamber 181 changes according to the movement of the SS piston 126. The axial groove 152 forms a ceiling section of this SS pressure chamber 181. The communication path 141 extends across both the entire MC cylinder and the entire SS cylinder 33. The communication path 141 enables the entire SS pressure chamber 181 to communicate with the secondary pressure chamber 61 at all times. The communication path 141 is open to an upper section of the SS pressure chamber 181 from the lower cylinder section 121.The communication path 141 is connected to a region of a part on a vertical upper side in the lower cylinder section 121 at the recess section 502. In addition to being open to a region of a part in the lower cylinder section 121, the communication path 141 can be open to the entire lower cylinder section 121. Alternatively, the communication path 141 can be open to a part of the lower cylinder section 121 across its entire diameter. The SS piston 126 defines the SS pressure chamber 181. The SS piston 126 applies a reaction force corresponding to the force applied to the brake pedal 11, which is located in... Fig. Figure 1 shows the brake pedal 11 via the brake fluid inside the SS pressure chamber 181, the brake fluid inside the secondary pressure chamber 61, the brake fluids of the secondary pistons 47, the primary pressure chamber 56, which is in Fig. Figure 2 shows the primary piston 46 and the input rod 21.

[0073] As in Fig. As shown in Figure 2, the subdivision seal 151, which is held by the circumferential groove 136 of the SS cylinder 33, is a one-piece molded product made of synthetic rubber. The subdivision seal 151 is a cup-shaped sleeve whose shape, on one side of a radial cross-section encompassing its centerline, is C-shaped. The subdivision seal 151 is arranged inside the circumferential groove 136, in which a lip portion is in a state oriented towards the lower cylinder section 121. In the subdivision seal 151, the inner circumference is in sliding contact with the outer circumferential surface of the SS piston 126, and the outer circumference comes into contact with the circumferential groove 136 of the SS cylinder 33. Accordingly, the subdivision seal 151 seals the gap at the position of the subdivision seal 151 of the SS piston 126 and the SS cylinder 33 at all times.

[0074] The subdivision seal 161, which is held by the circumferential groove 137 of the SS cylinder 33, is a one-piece molded product made of synthetic rubber. The subdivision seal 161 is a cup-shaped sleeve whose shape, on one side of a radial cross-section encompassing its centerline, is C-shaped. The subdivision seal 161 is arranged inside the circumferential groove 137, in which a lip portion is positioned to face the cylinder opening 123. In the subdivision seal 161, the inner circumference is in sliding contact with the outer circumferential surface of the SS piston 126, and the outer circumference comes into contact with the circumferential groove 137 of the SS cylinder 33. Accordingly, the subdivision seal 161 can seal the gap at the position of the subdivision seal 161 of the SS piston 126 and the SS cylinder 33 at all times.

[0075] The reaction force generation mechanism 127 comprises a metal cover element 191, a rubber sealing element 192, and a buffer element 193, which is an elastic element. The cover element 191 is attached to the large inner diameter section 132 of the SS cylinder 33 and is screwed into the internally threaded section 133. The sealing element 192 is held by the cover element 191 and seals a gap between the cover element 191 and the large inner diameter section 132 of the SS cylinder 33. The buffer element 193 is mounted in the cover element 191.

[0076] The cover element 191 has a mating section 195 and a projecting section 196. The mating section 195 is attached to the SS cylinder 33. The projecting section 196 has an outer diameter smaller than that of the mating section 195 and projects from the mating section 195 to the lower cylinder section 121. An external threaded section 197, an external diameter mating section 198, and a circumferential groove 199 are formed on the outer circumferential side of the mating section 195. The external threaded section 197 is screwed into the internal threaded section 133. The external diameter mating section 198 is attached to the large internal diameter section 132. The circumferential groove 199 is recessed radially inward from the outer diameter surface of the external diameter mating section 198 and has an annular shape. The sealing element 192, which is an O-ring, is arranged in the circumferential groove 199.An engagement recess section 200 is formed in the radial center of the fitting section 195. The engagement recess section 200 extends axially from the end face on one side opposite the lower cylinder section 121 of the fitting section 195. A screwdriving tool, such as a hex key, engages in the engagement recess section 200 when the external threaded section 197 of the fitting section 195 is screwed into the internal threaded section 133 of the SS cylinder 33.

[0077] A recess section 201 is formed on the side of the lower cylindrical section 121 at the radial center of the projecting section 196. The recess section 201 is recessed on one side opposite the lower cylindrical section 121 by a pointed end surface on the side that is closer to the lower cylindrical section 121 of the projecting section 196. A column-like buffer element 193, which is the elastic element, is attached and fixed in this recess section 201. When the buffer element 193 is in a state of contact with the lower surface of the recess section 201, the buffer element 193 projects to the side that is closer to the lower cylindrical section 121 than the pointed end surface 121 of the projecting section 196.

[0078] The reaction force generation mechanism 127 comprises a metal spring 206, a metal adjusting ring 207, a metal spring assembly 208, and a buffer element 209, which is an elastic element. One end of the spring 206 comes into contact with the fitting section 195 in a state in which the projecting section 196 is inserted into the inside. The adjusting ring 207 comes into contact with the other end of the spring 206. The spring assembly 208 is provided between the adjusting ring 207 and the SS piston 126. The buffer element 209 is mounted inside the spring assembly 208.

[0079] As in Fig. As shown in Figure 4, the spring 206 is a preload mechanism (helical spring) that generates a preload force. The adjusting ring 207 has a cover section 221, a body section 222, and a flange section 223. The cover section 221 is disc-shaped. The body section 222 extends axially from an outer circumferential edge section of the cover section 221 and is cylindrical. The flange section 223 extends radially outward from an end edge section on one side opposite the cover section 221 of the body section 222, beyond the body section 222, and is circular in shape. In the adjusting ring 207, the flange section 223 comes into contact with the end section of the spring 206 and locks into place.

[0080] The spring unit 208 comprises an adjusting ring 226 and a spring 227. The adjusting ring 226 is expandable within a predetermined range. The spring 227 is a preload mechanism (coil spring) that preloads the adjusting ring 226 in the expansion direction. The adjusting ring 226 controls the expansion of the spring 227 so that its maximum length does not exceed a predetermined length.

[0081] The adjusting ring 226 comprises a packing element 231, a guide shaft 232, and a locking element 233. The locking element 231 is disc-shaped, comes into contact with one end of the spring 227, and locks into it. The guide shaft 232 is fixed to the radial center of the locking element 231 and extends from the locking element 231 into the spring 227. The guide shaft 232 includes a shaft section 236 and a flange section 237. The shaft section 236 extends from the locking element 231. The flange section 237 extends radially outward beyond the shaft section 236 from the end section on one side opposite the locking element 231 of the shaft section 236 and is circular in shape.

[0082] The locking element 233 has a sliding section 241, a body section 242, and a flange section 243. The sliding section 241 is attached to the shaft section 236 of the guide shaft 232 and slides along the shaft section 236. The body section 242 extends from the sliding section 241 to one side opposite the locking element 231 and has a tubular shape. The flange section 243 extends radially outward beyond the body section 242 from the end edge section on one side opposite the sliding section 241 of the body section 242 and is circular in shape. In the locking element 233, the flange section 243 comes into contact with the other end of the spring 227 and locks with it.In the adjusting ring 226, the sliding section 241 of the locking element 233 comes into contact with the flange section 237 of the guide shaft 232 and thus controls the extension of the spring 227.

[0083] In the spring unit 208, the locking element 231 is inserted into the adjusting ring 207 and comes into contact with the cover section 221 of the adjusting ring 207. In the spring unit 208, in a state where the locking element 233 causes the projecting section 173 to be positioned inside the body section 242, the flange section 243 is brought into contact with the lower piston section 172 of the SS piston 126. The buffer element 209 is an elastic element with a cylindrical shape. The buffer element 209 is located inside the body section 242 of the locking element 233 in a state where it is positioned between the projecting section 173 of the SS piston 126 and the flange section 237 of the guide shaft 232.

[0084] A section surrounded by the SS piston 126, the cylinder wall section 122 of the SS cylinder 33, and the cover element 191 forms a spring chamber 245. The spring chamber 245 also forms the stroke simulator 27. The spring chamber 245 is defined against the SS pressure chamber 181 by the piston seals 151 and 161, which are located in Fig. 2 are shown.

[0085] As in Fig. As shown in Figure 4, the buffer element 193, the spring 206, the adjusting ring 207, the spring unit 208, and the buffer element 209 of the reaction force generation mechanism 127 are arranged inside this spring chamber 245. Thus, the springs 206 and 227 are arranged in the spring chamber 245. The vent passage 142 of the SS cylinder 33 communicates with this spring chamber 245. The spring chamber 245 communicates with the vent plug (not shown) for opening and closing this spring chamber 245 with respect to the outside air. Additionally, the spring chamber 245 communicates with the power module 13. In the axial groove 165 of the SS cylinder 33, one end is open inside the circumferential groove 137, and the other end is open to the spring chamber 245.

[0086] When the SS piston 126 is in a state of being in contact with the lower cylinder section 121 of the SS cylinder 33, as in Fig. 2 shown, comes in spring unit 208, as in Fig. As shown in Figure 4, one end of the SS piston 126 is in contact with the lower piston section 172 while its length is reduced, and the other end comes into contact with the cover section 221 of the adjusting ring 207. Additionally, in this state, one end of the spring 206 comes into contact with the flange section 223 of the adjusting ring 207, and the other end comes into contact with the fitting section 195 of the cover element 191, which is fixed to the SS cylinder 33. Additionally, in this state, the buffer element 193 is separated from the cover section 221 of the adjusting ring 207, and the buffer element 209 is separated from the flange section 237 of the guide shaft 232 of the spring assembly 208. The springs 206 and 227 bias the SS piston 126 in one direction towards the lower cylinder section 121, as shown in Figure 4. Fig. 2 shown.

[0087] The dividing seal 151 is provided on the side of the SS cylinder 33 in the SS cylinder 33 and the SS piston 126. Furthermore, the dividing seal 151 is arranged on one side opposite the springs 206 and 227 of the dividing seal 161 of the SS piston 126. The dividing seal 161 is provided on the side of the SS cylinder 33 in the SS cylinder 33 and the SS piston 126. Furthermore, the dividing seal 161 is arranged on the side of the springs 206 and 227 of the dividing seal 151 of the SS piston 126.

[0088] When the primary piston 46 moves in response to an input from the brake pedal 11, as shown in Fig. As the primary piston 46 moves to the lower cylinder section 41, it pressurizes the brake fluid inside the primary pressure chamber 56 as previously described. The pressurized brake fluid inside the primary pressure chamber 56 is discharged from the primary drain section 69 to the power module 13. In a normal state, however, the power module 13 blocks the fluid pressure from the primary drain section 69.

[0089] Additionally, when the primary piston 46 of the master cylinder 26 moves toward the side of the lower cylinder section 41 in response to input from the brake pedal 11, the secondary piston 47 is pushed by this primary piston 46 via the spring unit 57 and moves toward the side of the lower cylinder section 41. Consequently, the secondary piston 47 pressurizes the brake fluid inside the secondary pressure chamber 61 as previously described. The pressurized brake fluid inside the primary pressure chamber 61 is discharged from the secondary outlet 68 to the power module 13. In a normal state, however, the power module 13 blocks the fluid pressure from the secondary drain section 68. Therefore, the brake fluid, which is pressurized inside the secondary pressure chamber 61, is introduced via the communication section 141 into the SS pressure chamber 181 of the lifting simulator 27 and pressurizes the brake fluid inside the SS pressure chamber 181.

[0090] Consequently, the SS piston 126 moves in a direction that separates it from the lower cylinder section 121, that is, in a direction that brings it closer to the cover element 191. Consequently, the SS piston 126 initially causes the spring 227 of the spring unit 208 to move, which in Fig. As shown in section 4, the spring is reduced in length against the preload force. In this case, a reaction force corresponding to the reduced length of the spring 227, which is shown in Fig. As shown in 4, the brake pedal 11, which is in Fig. As shown in Figure 1, the SS piston 126, in a state where the spring 227 remains reduced in length, causes the buffer element 209 to come into contact with the flange section 237 of the guide shaft 232 and causes the buffer element 209 to reduce in length against the preload force. In this case, a reaction force corresponding to the reduced length of the spring 227 and the buffer element 209 is applied. Fig. 4 are shown, on the brake pedal 11, which is in Fig. As shown in Figure 1, the SS piston 126 is applied. Next, the spring 206, in a state where the spring 227 and the buffer element 209 remain reduced in length, causes the spring 206 to compress against the preload force. In this case, a reaction force corresponding to the reduced length of the spring 227, the buffer element 209, and the spring 206 is generated. Fig. 4 are shown, on the brake pedal 11, which is in Fig. As shown in Figure 1, the SS piston 126, in a state where the spring 227, the buffer element 209, and the spring 206 remain reduced in length, causes the adjusting ring 207 to come into contact with the buffer element 193, causing the buffer element 193 to be reduced in length against the preload force. In this case, a reaction force corresponding to the reduced length of the spring 227, the buffer element 209, the spring 206, and the buffer element 193 is applied. Fig. 4 are shown, on the brake pedal 11, which is in Fig. As shown in 1, the lifting simulator 27 applies a reaction force corresponding to a pressing force to the brake pedal 11, which is located in Fig. As shown in Figure 1, the brake pedal 11 is applied, creating a pseudo-operational feeling.

[0091] As in Fig. As shown in Figure 2, in the subdivision seals 151 and 161, which are provided with respect to the SS piston 126, the subdivision seal 161 is arranged on the front side (forward direction of movement) of the subdivision seal 151 in the direction of travel of the SS piston 126 when the brake pedal 11 is pressed. The subdivision seal 151 is arranged on the rear side (reverse direction of movement) of the subdivision seal 161 in the direction of travel of the SS piston 126 when the brake pedal 11 is pressed.

[0092] As in Fig. As shown in Figure 6, the power module 13 has a passage 301, a passage 302, a passage 303, a passage 304, and a passage 305. Passage 301 communicates via a communication port 301a at one end with the primary drain section 69 of the master cylinder 26, which is located in Fig. As shown in Figure 1, passage 302 branches off from terminal position 301b in passage 301 and communicates with brake cylinder 15VR. Passage 303 branches off from position 302a in passage 302 and communicates with brake cylinder 15HL. Passage 304 branches off from position 301b in passage 301 and communicates with brake cylinder 15HR. Passage 305 branches off from position 301b in passage 301 and communicates with brake cylinder 15VL.

[0093] Additionally, the power module 13 has a passage 308, a passage 309, a passage 310, a passage 311 and a passage 312. Passage 308 communicates via a communication port 308a at one end with the secondary drain section 68 of the master cylinder 26, which is located in Fig. 1 is shown. As in Fig. As shown in Figure 6, an inner end communicates with position 302a in passage 302. Passage 309 branches off from position 302b in passage 302 and communicates via a communication port 309a at the outer end with container 25, which is located in Fig. As shown in Figure 1, passage 310 branches off from position 303a in passage 303 and communicates with position 309b in passage 309. Passage 311 branches off from position 304a in passage 304 and communicates with position 310a in passage 310. Passage 312 branches off from position 305a in passage 305 and communicates with position 311a in passage 311.

[0094] Additionally, performance module 13 has a pass 315, a pass 316 and a pass 317. Passage 315 branches off from position 309c between communication port 309a and position 309b in passage 309 and communicates with position 302c between position 302a and position 301b in passage 302. Passage 315 also communicates with position 311b between position 311a and position 310a in passage 311. Passage 316 branches off from position 302d between position 302a and position 302b in passage 302 and communicates with position 309d between position 309b and position 309c in passage 309. Passage 317 branches off from position 316a in passage 316 and communicates via a communication port 317a at the outer end, as shown in Fig. 1 shown, with the vent passage 142.

[0095] Additionally, as shown in Fig. Figure 6 shows that the power module 13 includes an opening / closing valve 321, an opening / closing valve 322, an opening / closing valve 323, and an opening / closing valve 324. The opening / closing valve 321 is located at an intermediate position in the passage 301 and opens and closes the passage 301. The opening / closing valve 322 is located between position 301b and position 302c in the passage 302 and opens and closes the passage 302. The opening / closing valve 323 is located between position 302a and position 302c in the passage 302 and opens and closes the passage 302. The opening / closing valve 324 is located between position 302b and position 302d in the passage 302 and opens and closes the passage 302.

[0096] Additionally, the power module 13 includes an open / close valve 325, an open / close valve 326, and an open / close valve 327. The open / close valve 325 is located between position 302a and position 303a in passage 303 and opens and closes passage 303. The open / close valve 326 is located between position 301b and position 304a in passage 304 and opens and closes passage 304. The open / close valve 327 is located between position 301b and position 305a in passage 305 and opens and closes passage 305.

[0097] Additionally, the power module 13 includes an opening / closing valve 330, an opening / closing valve 331, an opening / closing valve 332, an opening / closing valve 333 and an opening / closing valve 334. The open / close valve 330 is located at an intermediate position in the passage 308 and opens and closes the passage 308. The open / close valve 331 is located between position 302b and position 309b in the passage 309 and opens and closes the passage 309. The open / close valve 332 is located between position 303a and position 310a in the passage 310 and opens and closes the passage 310. The open / close valve 333 is located between position 304a and position 311a in the passage 311 and opens and closes the passage 311. The open / close valve 334 is located between position 305a and position 311a in the passage 312 and opens and closes the passage 312.

[0098] Additionally, the power module 13 includes a reservoir 337 and a pump 339. The reservoir 337 is located between position 309c and position 302c in passage 315 and communicates with the reservoir 25 of the main cylinder unit 12, which is located in Fig. 1 is shown, and contains the brake fluid. The pump 339, which is in Fig. The unit shown in Figure 6 is driven by a motor 338, draws the brake fluid from the reservoir 337, and discharges the brake fluid to position 302c. The pump 339 is located on the side that is closer to position 302c than the reservoir 337.

[0099] Additionally, the power module 13 includes an open / close valve 340, an open / close valve 341, and an open / close valve 342. The open / close valve 340 is located between position 302c and position 311b in passage 315 and opens and closes passage 315. The open / close valve 341 is located between position 302d and position 316a in passage 316 and opens and closes passage 316. The open / close valve 342 is located between position 316a and position 309d in passage 316 and opens and closes passage 316.

[0100] Here are the opening / closing valves 321, 324, 325, 326, 327, 330 and 340 in an open state, as shown in Fig. Figure 6 shows the valves in an unactuated state, where they are not electrically actuated, and in a closed state, and in an actuated state, where they are electrically actuated. Additionally, the open / close valves 322, 323, 331, 332, 333, 334, 341, and 342 are shown in a closed state, as shown in Figure 6. Fig. Figure 6 shows the valves in an uncontrolled state, where they are not electrically controlled, and in an open state, where they are electrically controlled.

[0101] The power module 13 has a bypass passage 345, a bottom valve 346, a bypass passage 347, a bottom valve 348, a bypass passage 349, and a bottom valve 350. The bypass passage 354 bypasses the open / close valve 324 and connects position 302b and position 302d in passage 302. The bottom valve 346 is located in the bypass passage 345 and allows the brake fluid to flow only from position 302b to position 302d. The bypass passage 347 bypasses the open / close valve 325 and connects position 303a and position 302a in passage 303. The bottom valve 348 is provided in the bypass passage 347 and allows the brake fluid to flow only from position 303a to position 302a. The bypass passage 349 bypasses the opening / closing valve 326 and connects position 304a and position 301b in passage 304.The bottom valve 350 is provided in the bypass passage 349 and allows the brake fluid to flow only from position 304a to the side of position 301b.

[0102] Additionally, the power module 13 has a bypass passage 351, a bottom valve 352, a bypass passage 353, a bottom valve 354, a bypass passage 355, and a bottom valve 356. The bypass passage 351 bypasses the open / close valve 327 and connects position 305a and position 301b in passage 305. The bottom valve 352 is located in the bypass passage 351 and allows the brake fluid to flow only from position 305a to the side of position 301b. The bypass passage 353 bypasses the open / close valve 341 and connects position 316a and position 302d in passage 316. The bottom valve 354 is provided in the bypass passage 353 and allows the brake fluid to flow only from position 316a to position 302d. The bypass passage 355 bypasses the opening / closing valve 342 and connects position 316a and position 309d of passage 316.The bottom valve 356 allows the brake fluid to flow in the bypass passage 355 only from position 309d to position 316a.

[0103] Additionally, the power module 13 includes a pressure sensor 357, a pressure sensor 358, a pressure sensor 359, and a pressure sensor 360. Pressure sensor 357 is connected to position 302d in passage 302 and detects the pressure at this point. Pressure sensor 358 is connected to a point between position 301b in passage 305 and the open / close valve 327 and the bottom valve 352, and detects the pressure at this point. Pressure sensor 359 is connected to a point between communication port 308a and the open / close valve 330 in passage 308, and detects the pressure at this point. Pressure sensor 360 is connected to a point between pump 339 and position 302c in passage 315, and detects the pressure at this point.

[0104] In the braking system 10, when a driver presses the brake pedal 11 in a normal power supply state, the input rod 21 moves to the lower cylinder section 41 of the master cylinder 26. Consequently, the stroke sensor 22 detects this movement of the input rod 21. Based on this detection, the open / close valves 321 and 330 of the power module 13 are electrically actuated and are in a closed state. The open / close valves 322 and 323 are electrically actuated and are in an open state. The open / close valve 340 is electrically actuated and is in a closed state. During normal operation of the brake pedal 11, the open / close valve 342 is electrically actuated and is in an open state. During sudden actuation of the brake pedal 11, the open / close valve 342 is not electrically actuated and is in a closed state.

[0105] When the opening / closing valves 321 and 330 are in a closed state, as previously described, passages 301 and 308 are closed. Consequently, the opening / closing valves 321 and 330 block the brake fluid from being supplied from the secondary drain section 68 and the primary drain section 69 of the master cylinder 26 to the brake cylinders 15VR, 15HL, 15HR, and 15VL. Accordingly, when the primary piston 46 and the secondary piston 47 move to the lower cylinder section 41 in accordance with the movement of the input rod 21, the brake fluid from the secondary pressure chamber 61 is introduced into the SS pressure chamber 181 of the stroke simulator 27 via the communication section 141. Consequently, the fluid pressure of the SS pressure chamber 181 increases, causing the SS piston 126 to move in one direction toward the cover element 191.Accordingly, a reaction force corresponding to a pressing force on the brake pedal 11 is applied to the brake pedal 11 by means of the spring 227 of the spring unit 208, the buffer element 209, the spring 206 and the buffer element 193, thereby creating a pseudo-operational feeling.

[0106] As previously described, when the opening / closing valves 322 and 323 are electrically actuated and in an open state, and when the opening / closing valve 340 is electrically actuated and in a closed state, the pump 339 communicates with the brake cylinders 15VR, 15HL, 15HR, and 15VL. In this case, the pump 339 communicates with the brake cylinders 15VR, 15HL, 15HR, and 15VL via a section from the pump 339 to position 302c in passage 315 and passages 302 to 305. The motor 338 is then driven based on the amount of movement of the input rod 21, which is similarly detected by the stroke sensor 22. Consequently, the pump 339 draws brake fluid from reservoir 337 and reservoir 25 and discharges the brake fluid. The drained brake fluid is fed to brake cylinder 15VR via passage 315 between position 302c and brake cylinder 15VR through passage 302.Additionally, the drained brake fluid is fed to brake cylinder 15HL via passage 315 between position 302c and position 302a and passage 303. Additionally, the drained brake fluid is fed to brake cylinder 15HR via passage 315 between position 302c and position 301b and passage 304. Additionally, the drained brake fluid is fed to brake cylinder 15VL via passage 315 between position 302c and position 301b and passage 305. In this way, brake cylinders 15VR, 15HL, 15HR, and 15VL are pressurized. Accordingly, braking is applied to the wheels.

[0107] At the time of the power supply failure, the open / close valves 321 and 330 of power module 13 are not electrically actuated and are in an open state. Open / close valves 321 and 330 thus open passage 301 and passage 308, respectively. Additionally, open / close valves 322, 323, and 341 are in a closed state, open / close valves 324 to 327 are in an open state, and open / close valves 331 to 334 and 342 are in a closed state. Thus, the brake fluid, which is drained from the primary pressure chamber 56 of the master cylinder 26 via the primary drain section 69 to the passage 301, is supplied to each of the brake cylinders 15HR via the passage 304 and to the brake cylinder 15VL via the passage 305.Additionally, the brake fluid, which is drained from the secondary pressure chamber 61 of the master cylinder 26 via the secondary drain section 68 to the passage 308, is supplied to each of the brake cylinders 15VR via the passage 302 between position 302a and the brake cylinder 15VR and to the brake cylinder 15HL via the passage 303.

[0108] During the bleeding of the brake system 10, the primary pressure chamber 56 of the master cylinder 26, the secondary pressure chamber 61, and the SS pressure chamber 181 of the lifting simulator 27 are vented. Since the SS pressure chamber 181 communicates with the secondary pressure chamber 61 via the communication line 141, the SS pressure chamber 181 is vented together with the secondary pressure chamber 61 in this case. Next, the spring chamber 245 of the lifting simulator 27 is vented.

[0109] The communication line 141, which enables the SS pressure chamber 181 and the secondary pressure chamber 61 to communicate with each other, is shaped such that its position in the vertical direction increases as the communication line 141 approaches the secondary pressure chamber 61. Therefore, during the venting of the SS pressure chamber 181 of the lifting simulator 27, air in the SS pressure chamber 181 is uniformly vented from the communication line 141 to the secondary vent line 68 via the secondary pressure chamber 61. Consequently, there is no need to provide a vent passage and a vent plug for venting the SS pressure chamber 181 in the SS cylinder 33.

[0110] The braking device disclosed in patent literature 1 comprises a stroke simulator that applies a reaction force corresponding to a pressing force on a brake pedal to the brake pedal. In such a braking device, it is desirable to simplify the design for venting.

[0111] The first embodiment comprises the communication path 141, which enables the main cylinder 26 and the stroke simulator 27 to communicate with each other. The stroke simulator 27 comprises a tubular stainless steel piston with a base 126 and the stainless steel cylinder 33, in which the stainless steel piston 126 moves. The stainless steel piston 126 is arranged such that the lower cylinder section 121 and the piston opening 171b face each other. The communication path 141 is open across the outer and inner circumferential sections of the piston opening 171b and is connected to the lower cylinder section 121. The communication path 141 is designed to extend upwards in the vertical direction as it approaches the secondary pressure chamber 61 from the lower cylinder section 121. Therefore, air in the stainless steel pressure chamber 181 is able to move uniformly towards the secondary pressure chamber 61.Thus, the design for venting the SS pressure chamber 181 can be simplified.

[0112] Additionally, the communication path 141 in the recess section 502 is connected to a region of a part on a vertical upper side in the lower cylinder section 121. Therefore, compared to a case where it is formed over the entire lower cylinder section 121 or its entire diameter, the processing hours can be reduced, thus improving manufacturing efficiency.

[0113] Additionally, the axial groove 152, which is a recessed section extending radially outwards from the subdivision seal 151 to the lower cylinder section 121 across the side of the piston opening 171b, is provided in a portion on the side that is closer to the lower cylinder section 172 than the lower cylinder section 121 of the SS cylinder 33. Therefore, air in the circumferential groove 136, in which the subdivision seal 151 is located, can also be subjected to uniform venting.

[0114] Additionally, in the first embodiment, the lower cylinder section 121, which is connected to the communication line 141, is recessed compared to a section to which the communication line 141 is not connected. The communication line 141 extends radially outwards in the lower cylinder section 121. Therefore, air in the SS pressure chamber 181 is able to move uniformly to the secondary pressure chamber 61. This simplifies the design for venting the SS pressure chamber 181.

[0115] In the first embodiment, even when the SS piston 126 is in contact with the lower cylinder section 121, the communication path 141, comprising the recess section 502, is simultaneously open to and communicates with both the inner and outer circumferential sides of the SS piston 126. In other words, the communication path 141 communicates with both the inner and outer circumferential sides of the SS piston at all times. Therefore, the communication path 141 causes air in the SS pressure chamber 181 between the SS cylinder 33 and the SS piston 126 to flow to the secondary pressure chamber 61. Thus, there is no need to provide a vent passage and a vent plug solely for venting the SS pressure chamber 181. That is, the machining for a vent passage is no longer necessary, nor is a vent plug and its installation.Additionally, there is no need to form connections that penetrate radially into the cylindrical section 171 on the side where the SS pressure chamber 181 of the cylindrical section 171 of the SS piston 126 is formed. That is, machining for connections is no longer necessary. Therefore, the venting design can be simplified and costs can be reduced.

[0116] Additionally, the communication path 141 comprises the recessed section 502, the through-bore 503, and the through-bore 501. The recessed section 502 is provided in the lower cylinder section 121 in a recessed manner. The through-bore 503 extends linearly from the recessed section 502. In the through-bore 501, one end is linearly connected to the MC cylinder 32 in a substantially perpendicular manner, and the other end is connected to the through-bore 503. Therefore, due to the projecting section 502, the communication path 141 can conveniently communicate with the inner and outer circumferential sides of the SS piston 126. Thus, venting of the SS pressure chamber 181 can conveniently be carried out. Second embodiment

[0117] Next, a second embodiment will be developed, primarily based on Fig. 7 and Fig. Section 8 describes the differences from the first embodiment. The sections common to the first embodiment are designated by the same names and reference numerals.

[0118] In the second embodiment, a cylinder bore 120A, which is deeper than the cylinder bore 120 of the first embodiment, is provided in the lifting simulator 27. In the second embodiment, a communication line 141A, which differs partially from the communication line 141, is provided in the lifting simulator 27.

[0119] This communication path 141A has a linear shape. The communication path 141A extends vertically downwards from the cylinder bore 40 of the MC cylinder 32 to a point in the vicinity of the axial centerline of the cylinder bore 120 of the SS cylinder 33. The communication path 141A communicates with the axial groove 152. The communication path 141A is recessed in one direction opposite the cylinder opening 123 across the lower main surface 121a of the lower cylinder section 121 in one direction of the axial centerline of the cylinder bore 120.

[0120] The communication line 141A, which is also in Fig.Figure 8 shows a circular cross-sectional shape, except for the opening portion to the cylinder bore 120A. The communication section 141A is coaxial with the secondary drain section 68, forming the same straight line as the secondary drain section 68 of the main cylinder 26, and has the same diameter. Thus, the secondary drain section 68 and the communication section 141A are formed by a bore opening that is made using a drill. In the communication section 141A, the axial centerline, similar to that of the secondary drain section 68, is also orthogonal to the axial centerline of the cylinder bore 40.

[0121] An end-edge section 141Aa on the boundary between the lower main surface 121a and the communication path 141A is located at a position where it radially intersects the end surface 171a of the cylindrical section 171 of the SS piston 126. Thus, even when the SS piston 126 is in contact with the lower cylindrical section 121, the communication path 141A is simultaneously open to and communicates with both the inner and outer circumferential sides of the SS piston 126. Consequently, even when the SS piston 126 is in contact with the lower cylindrical section 121, the communication path 141A causes the axial groove 152 and the interior of the cylindrical section 171 to communicate with each other.This means that the communication path 141A communicates with the inner and outer circumferential sides at all times, regardless of the position of the SS piston 126, and causes the axial groove 152 and the interior of the cylindrical section 171 to communicate with each other at all times. The communication path 141A is open across the outer and inner circumferential sections of the piston opening 171b. The communication path 141A is connected to the lower cylinder section 121. The lower cylinder section 121, to which the communication path 141A is connected, is recessed compared to a section to which the communication path 141A is not connected, and the communication path 141A extends radially outward. The communication path 141A extends linearly from the SS cylinder 33 to be perpendicular to the SS cylinder 33 and is perpendicularly connected to the secondary pressure chamber 61.The communication path 141A extends vertically and linearly from the SS cylinder 121 and is connected perpendicularly to the MC cylinder 32. The communication path 141A extends vertically upwards from the cylinder bore 120A. Thus, the communication path 141A is designed to extend vertically upwards as it approaches the secondary pressure chamber 61 from the lower cylinder section 121. The communication path 141A is connected to a region of a part on the vertical upper side of the lower cylinder section 121. In addition to being open to a region of a part in the lower cylinder section 121, the communication path 141A can be open to the entire lower cylinder section 121. The communication line 141A may be slightly inclined with respect to the vertical state, instead of being perpendicular to the MC cylinder 32 and the SS cylinder 33.This means that the communication path 141A only needs to be connected to the MC cylinder 32 and the SS cylinder 33 in a substantially perpendicular manner. The communication path 141A only needs to extend linearly from the lower cylinder section 121 to the SS cylinder 33 in a substantially perpendicular manner and be connected to the secondary pressure chamber 61 in a substantially perpendicular manner. The communication path 141A, which extends over both the entire MC cylinder 32 and the entire SS cylinder 33, causes the entire SS pressure chamber 181 to communicate with the secondary pressure chamber 61 at all times.

[0122] In the second embodiment, the communication path 141A extends vertically and linearly from the MC cylinder 32 and is connected perpendicularly to the SS cylinder 33. Therefore, the design of the communication path 141A can be further simplified, thus facilitating the processing required to create the communication path 141A and further reducing costs.

[0123] The embodiments described above include a reservoir for holding brake fluid, a master cylinder that exchanges the brake fluid with the reservoir, and a stroke simulator that exchanges the brake fluid with the master cylinder. The master cylinder comprises a master cylinder piston that moves linearly in response to a force applied to a brake pedal, and a first pressure chamber in which the pressure changes according to the movement of the master cylinder piston. The stroke simulator comprises the stroke simulator piston, which applies a reaction force in response to a force applied to the brake pedal, and a second pressure chamber in which the pressure changes according to the movement of the stroke simulator piston. A communication link is provided that enables the first and second pressure chambers to communicate with each other. The communication link communicates with the inner and outer circumferential sides of the stroke simulator piston.The communication path causes air in the second pressure chamber to flow into the first pressure chamber. Therefore, there is no need to provide a vent passage and vent plug solely for venting the second pressure chamber. Additionally, there is no need to include connections in the part forming the second pressure chamber of the stroke simulator piston to allow the inner and outer circumferential sides to communicate with each other. Consequently, the venting design can be simplified and costs reduced.

[0124] Additionally, the communication path comprises a recessed section provided on an approaching section of a stroke simulator cylinder, facing a tip end section of the stroke simulator piston, recessed in a direction away from the tip end section of the stroke simulator piston; a first communication port extending linearly from the recessed section; and a second linear communication port, one end of which is connected to a cylinder for a master cylinder in a substantially perpendicular manner, and the other end of which is connected to the first communication port. Therefore, due to the recessed section, the communication path can advantageously communicate with both the inner and outer circumferential sides of the stroke simulator piston. Thus, venting of the second pressure chamber can advantageously be implemented.

[0125] Additionally, the communication path extends essentially vertically from the cylinder to a main cylinder and is connected to the stroke simulator cylinder in an essentially vertical manner. Therefore, the communication path can be easily designed. Consequently, the venting design can be further simplified, and costs can be further reduced.

[0126] For example, as a main cylinder unit based on the embodiments described above, it is possible to consider the following aspects.

[0127] As a first aspect, a master cylinder unit comprises a master cylinder that causes fluid pressure to be generated in a pressure chamber inside a cylinder according to the amount of force applied to the brake pedal, a reservoir that supplies brake fluid to the pressure chamber, a stroke simulator that communicates with the pressure chamber and applies a reaction force to the brake pedal corresponding to the amount of force applied to the brake pedal, and a communication link that enables the master cylinder and stroke simulator to communicate with each other. The stroke simulator comprises a tubular simulator piston with a base and a simulator cylinder in which the simulator piston moves. The simulator piston is arranged such that a lower section of the simulator cylinder and an opening section of the simulator piston face each other.The communication path is open via an outer circumferential section and an inner circumferential section of the opening section of the simulator piston, is connected to the lower section of the simulator cylinder, and is designed such that the communication path extends upwards in a vertical direction from the lower section of the simulator cylinder as it approaches the pressure chamber.

[0128] As a second point of view, in accordance with the first point of view, the communication path is connected to an area on an upper side in the vertical direction in the lower section of the simulator cylinder.

[0129] As a third aspect, in accordance with the first or second aspect, a sealing element is provided in the simulator cylinder, separating the lower section side of the simulator piston from the simulator piston opening side, between the outer circumferential section of the simulator piston and the simulator cylinder. A recessed section extending from the sealing element to the lower section of the simulator cylinder beyond the simulator piston opening side is provided in a portion of the simulator cylinder on the lower section side of the simulator piston.

[0130] As a fourth point of view according to any of the first to third points of view, the communication path extends linearly in a substantially perpendicular manner from the lower section of the simulator cylinder and is connected to the pressure chamber in a substantially perpendicular manner.

[0131] As a fifth aspect, a master cylinder unit comprises a master cylinder that causes fluid pressure to be generated in a pressure chamber inside a cylinder according to the amount of brake pedal actuation; a reservoir that supplies brake fluid to the pressure chamber; a stroke simulator that communicates with the pressure chamber and applies a reaction force to the brake pedal corresponding to the amount of brake pedal actuation; and a communication link that enables the master cylinder and stroke simulator to communicate with each other. The stroke simulator comprises a tubular simulator piston with a base and a simulator cylinder in which the simulator piston moves. The simulator piston is arranged such that a lower section of the simulator cylinder and an opening section of the simulator piston face each other. The communication link is connected to the lower section of the simulator cylinder.The lower section of the simulator cylinder, to which the communication link is connected, is recessed compared to a part to which the communication link is not connected, and the communication link extends radially outwards. [Commercial Applicability]

[0132] Based on the previously described main cylinder unit, a simplified design for venting is possible. [List of reference symbols] 11 Brake pedal 12 Main cylinder unit 25 containers 26 master cylinders 27 Hub Simulator 32 MC cylinders (cylinders) 33 SS cylinders (simulator cylinders) 61 Secondary pressure chamber (pressure chamber) 121 lower cylinder section (lower section of the simulator cylinder) 126 SS pistons (simulator pistons) 141 Communication link 151 Subdivision seal (sealing element) 152 Axial groove (recess section) 171b Piston opening (opening section of the simulator piston) 172 lower piston section (lower section of the simulator piston)

Claims

[1] Master cylinder unit (12), comprising: a master cylinder (26) which causes a fluid pressure to be generated in a pressure chamber (61) inside a cylinder (32) according to an actuation amount of a brake pedal (11); a container (25) that supplies brake fluid to the pressure chamber (61); a lifting simulator (27) that communicates with the pressure chamber (61) and applies a reaction force to the brake pedal (11) corresponding to an actuation force of the brake pedal (11); and a communication link (141) that causes the main cylinder (26) and the lifting simulator (27) to communicate with each other. wherein the stroke simulator (27) comprises a tubular simulator piston (126) with a base and a simulator cylinder (33) in which the simulator piston (126) moves, wherein a cylinder bore (120) is provided in the simulator cylinder (33), wherein the cylinder bore (120) has a lower cylinder section (121) and a cylinder wall section (122), wherein the simulator piston (126) is arranged such that the lower cylinder section (121) and an opening section (171b) of the simulator piston (126) face each other, wherein a space is formed by the opening section (171b) between an end section of the simulator piston (126) on the lower side and the lower section of the simulator cylinder (33), wherein the communication path (141) comprises a recess section (502) provided in the lower cylinder section (121) and a through-bore (503) which communicates with the recess section (502), wherein the communication path (141) is open via an outer circumferential section and an inner circumferential section of the opening section (171b) of the simulator piston (126), wherein the communication line (141) connects the room and the main cylinder (26), and wherein the through-bore (503) of the communication path (141) is provided such that the communication path (141) extends in a vertical direction from the lower section of the simulator cylinder (33) upwards as it approaches the pressure chamber (61). [2] Main cylinder unit (12) according to claim 1, wherein the communication line (141) is connected to an area on an upper side in the vertical direction in the lower section of the simulator cylinder (33). [3] Main cylinder unit (12) according to claim 1 or 2, wherein in the simulator cylinder (33) a sealing element (151) is provided which divides the lower section side of the simulator piston (126) and the simulator piston opening side between the outer circumferential section of the simulator piston (126) and the simulator cylinder (33), and wherein a recess section (152) extending from the sealing element (151) to the lower section of the simulator cylinder (33) beyond the simulator piston opening side is provided in a part of the simulator cylinder (33) on the lower section side of the simulator piston (126). [4] Main cylinder unit (12) according to any one of claims 1 to 3, wherein the communication path (141) extends linearly from the lower section of the simulator cylinder (33) in a substantially perpendicular manner and is connected to the pressure chamber (61) in a substantially perpendicular manner. [5] Main cylinder unit (12), comprising: a master cylinder (26) which causes a fluid pressure to be generated in a pressure chamber (61) inside a cylinder (32) according to an actuation amount of a brake pedal (11); a container (25) that supplies brake fluid to the pressure chamber (61); a lifting simulator (27) that communicates with the pressure chamber (61) and applies a reaction force to the brake pedal (11) corresponding to an actuation force of the brake pedal (11); and a communication link (141A) that causes the main cylinder (26) and the lifting simulator (27) to communicate with each other, wherein the stroke simulator (27) comprises a tubular simulator piston (126) with a base and a simulator cylinder (33) in which the simulator piston (126) moves, wherein a cylinder bore (120) is provided in the simulator cylinder (33), wherein the cylinder bore (120) has a lower cylinder section (121) and a cylinder wall section (122), wherein the simulator piston (126) is arranged such that the lower cylinder section (121) and an opening section (171b) of the simulator piston (33) face each other, wherein a space is formed by the opening section (171b) between an end section of the simulator piston (126) on the lower side and the lower section of the simulator cylinder (33), wherein the communication path (141A) comprises a recess section (502) provided in the lower cylinder section (121) and a through-bore (503) which communicates with the recess section (502), wherein the communication line (141A) connects the room and the main cylinder (26), and wherein the lower cylinder section (121) to which the communication path (141A) is connected is recessed compared to a part to which the communication path (141A) is not connected, and the communication path (141A) extends radially outwards.

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