JP4779951B2 - Brake device and stroke simulator - Google Patents

Description

  The present invention relates to a stroke simulator that creates a reaction force against a driver's braking operation. Moreover, it is related with a brake device provided with a stroke simulator.

Conventionally, in a brake-by-wire type brake device, a stroke simulator is often used to give a driver a good brake feeling. This stroke simulator may incorporate a so-called gas spring in order to generate a reaction force against the driver's braking operation (see, for example, Patent Document 1 and Patent Document 2).
JP 2001-151091 A JP 2006-142939 A

  By the way, in the stroke simulator incorporating the gas spring described above, there is a certain non-linear relationship between the amount of hydraulic fluid that flows in and the reaction force that is obtained. This is in order to achieve a good brake feeling. desirable. However, there is a possibility that the gas pressure changes due to the temperature change of the stroke simulator, and the relationship between the hydraulic fluid amount and the reaction force, that is, the brake feeling is fluctuated.

  Then, an object of this invention is to provide the stroke simulator which can implement | achieve favorable brake feeling stably.

  A brake device according to an aspect of the present invention houses a master cylinder including two pressurizing chambers in which hydraulic fluid is pressurized to substantially the same pressure by a driver's brake operation, and hydraulic fluid flowing from the master cylinder. A stroke simulator that includes a hydraulic fluid chamber and a gas chamber in which gas is sealed, and that creates a reaction force against a brake operation by a gas pressure generated according to the amount of hydraulic fluid flowing into the hydraulic fluid chamber; A first communication path that connects one of the pressurizing chambers to the hydraulic fluid chamber so that the hydraulic fluid is allowed to flow and the hydraulic fluid is blocked when the stroke simulator is not used, the other of the pressurizing chambers, and the hydraulic fluid And a second communication path connecting the chambers.

  According to this aspect, the hydraulic fluid chamber of the stroke simulator is connected to each of the two pressurization chambers of the master cylinder through each of the first communication path and the second communication path. The first communication path is a path for allowing the hydraulic fluid from the master cylinder to flow into and out of the stroke simulator when the stroke simulator is to be used, typically, for example, when a brake operation is performed by the driver. . The second communication path is a path that allows the working fluid to flow between the master cylinder and the stroke simulator. For example, the second communication path may allow the hydraulic fluid to flow between the stroke simulator and the master cylinder, at least when the brake is not operated, regardless of whether the driver operates the brake. For example, even if the gas sealed in the gas chamber expands or contracts due to a temperature change, the hydraulic fluid flows into and out of the hydraulic fluid chamber through the second communication path so as to reduce the expansion or contraction. Thereby, it can suppress that the gas pressure of a stroke simulator deviates from predetermined pressures, such as atmospheric pressure, for example. Therefore, the gas pressure at the start of the brake operation can be maintained at a predetermined pressure, and a good brake feeling can be stably realized.

  The second communication path may be provided with a check valve that allows the hydraulic fluid to flow out of the hydraulic fluid chamber when the gas pressure exceeds a predetermined pressure. According to this aspect, when the gas pressure exceeds the predetermined pressure, it is possible to suppress the deviation of the gas pressure from the predetermined pressure by discharging the hydraulic fluid through the check valve. Therefore, a favorable brake feeling can be realized stably.

  Another aspect of the present invention is a stroke simulator. This stroke simulator is filled with a hydraulic fluid chamber that contains hydraulic fluid that flows in and out in response to a brake operation, and has a volume that is complementary to the hydraulic fluid chamber according to a differential pressure with the hydraulic fluid chamber. A gas chamber that increases and decreases, and a first outlet that is formed in the hydraulic fluid chamber so that the hydraulic fluid is allowed to flow into and out of the hydraulic fluid chamber when the brake is operated and the flow of the hydraulic fluid is blocked when the brake is not operated, A second inlet / outlet formed in the hydraulic fluid chamber so as to allow the hydraulic fluid to flow in and out to maintain the gas pressure in the gas chamber at a predetermined pressure when the brake is not operated.

  According to this aspect, the two outflow inlets are formed in the working fluid chamber of the stroke simulator for the circulation of the working fluid. Basically, the first outflow inlet is provided for the inflow and outflow of the hydraulic fluid accompanying the brake operation. Further, the second outlet / inlet enables the flow of hydraulic fluid between the stroke simulator and the outside, particularly when the brake is not operated, regardless of whether or not the driver operates the brake. It is possible to prevent the gas pressure of the stroke simulator from deviating from a predetermined pressure by flowing the working fluid from the outside through the second outflow inlet according to the expansion or contraction of the enclosed gas. Therefore, a favorable brake feeling can be stably realized.

  According to the present invention, a good brake feeling can be stably realized.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a system diagram showing a brake control device 20 according to an embodiment of the present invention. A brake control device 20 shown in the figure constitutes an electronically controlled brake system (ECB) for a vehicle, and controls braking force applied to four wheels provided on the vehicle. The brake control device 20 according to the present embodiment is mounted on, for example, a hybrid vehicle that includes an electric motor and an internal combustion engine as a travel drive source. In such a hybrid vehicle, each of regenerative braking that brakes the vehicle by regenerating kinetic energy of the vehicle into electric energy and hydraulic braking by the brake control device 20 can be used for braking the vehicle. The vehicle in the present embodiment can execute brake regenerative cooperative control that generates a desired braking force by using both the regenerative braking and the hydraulic braking together.

  As shown in FIG. 1, the brake control device 20 includes disc brake units 21FR, 21FL, 21RR and 21RL provided for each wheel, a master cylinder unit 27, a power hydraulic pressure source 30, a hydraulic pressure, Actuator 40.

  Disc brake units 21FR, 21FL, 21RR, and 21RL apply braking force to the right front wheel, the left front wheel, the right rear wheel, and the left rear wheel of the vehicle, respectively. The master cylinder unit 27 as the manual hydraulic pressure source in the present embodiment sends the brake fluid pressurized according to the operation amount by the driver of the brake pedal 24 as the brake operation member to the disc brake units 21FR to 21RL. To do. The power hydraulic pressure source 30 can send the brake fluid as the working fluid pressurized by the power supply to the disc brake units 21FR to 21RL independently from the operation of the brake pedal 24 by the driver. is there. The hydraulic actuator 40 appropriately adjusts the hydraulic pressure of the brake fluid supplied from the power hydraulic pressure source 30 or the master cylinder unit 27 and sends it to the disc brake units 21FR to 21RL. Thereby, the braking force with respect to each wheel by hydraulic braking is adjusted.

  Each of the disc brake units 21FR to 21RL, the master cylinder unit 27, the power hydraulic pressure source 30, and the hydraulic actuator 40 will be described in more detail below. Each of the disc brake units 21FR to 21RL includes a brake disc 22 and wheel cylinders 23FR to 23RL incorporated in the brake caliper, respectively. The wheel cylinders 23FR to 23RL are connected to the hydraulic actuator 40 via different fluid passages. Hereinafter, the wheel cylinders 23FR to 23RL are collectively referred to as “wheel cylinders 23” as appropriate.

  In the disc brake units 21FR to 21RL, when brake fluid is supplied to the wheel cylinder 23 from the hydraulic actuator 40, a brake pad as a friction member is pressed against the brake disc 22 that rotates together with the wheel. Thereby, a braking force is applied to each wheel. In the present embodiment, the disc brake units 21FR to 21RL are used, but other braking force applying mechanisms including a wheel cylinder 23 such as a drum brake may be used.

  In this embodiment, the master cylinder unit 27 is a master cylinder with a hydraulic booster, and includes a hydraulic booster 31, a master cylinder 32, a regulator 33, and a reservoir. The hydraulic booster 31 is connected to the brake pedal 24, amplifies the pedal effort applied to the brake pedal 24, and transmits it to the master cylinder 32. When the brake fluid is supplied from the power hydraulic pressure source 30 to the hydraulic pressure booster 31 via the regulator 33, the pedal effort is amplified. The master cylinder 32 generates a master cylinder pressure having a predetermined boost ratio with respect to the pedal effort.

  A reservoir 34 for storing brake fluid is disposed above the master cylinder 32 and the regulator 33. The hydraulic pressure in the reservoir 34 is, for example, atmospheric pressure. The master cylinder 32 communicates with the reservoir 34 when the depression of the brake pedal 24 is released. On the other hand, the regulator 33 is in communication with both the reservoir 34 and the accumulator 35 of the power hydraulic pressure source 30, and the reservoir 34 is used as a low pressure source, the accumulator 35 is used as a high pressure source, and the hydraulic pressure is approximately equal to the master cylinder pressure. Is generated. Hereinafter, the hydraulic pressure in the regulator 33 is appropriately referred to as “regulator pressure”. The master cylinder pressure and the regulator pressure do not need to be exactly the same pressure. For example, the master cylinder unit 27 can be designed so that the regulator pressure is slightly higher.

  The power hydraulic pressure source 30 includes an accumulator 35 and a pump 36. The accumulator 35 converts the pressure energy of the brake fluid boosted by the pump 36 into the pressure energy of an enclosed gas such as nitrogen, for example, about 14 to 22 MPa and stores it. The pump 36 has a motor 36 a as a drive source, and its suction port is connected to the reservoir 34, while its discharge port is connected to the accumulator 35. The accumulator 35 is also connected to a relief valve 35 a provided in the master cylinder unit 27. When the pressure of the brake fluid in the accumulator 35 increases abnormally to about 25 MPa, for example, the relief valve 35 a is opened, and the high-pressure brake fluid is returned to the reservoir 34.

  As described above, the brake control device 20 includes the master cylinder 32, the regulator 33, and the accumulator 35 as a supply source of brake fluid to the wheel cylinder 23. A master pipe 37 is connected to the master cylinder 32, a regulator pipe 38 is connected to the regulator 33, and an accumulator pipe 39 is connected to the accumulator 35. These master pipe 37, regulator pipe 38 and accumulator pipe 39 are each connected to a hydraulic actuator 40.

  The hydraulic actuator 40 includes an actuator block in which a plurality of flow paths are formed, and a plurality of electromagnetic control valves. The flow paths formed in the actuator block include individual flow paths 41, 42, 43 and 44 and a main flow path 45. The individual flow paths 41 to 44 are respectively branched from the main flow path 45 and connected to the wheel cylinders 23FR, 23FL, 23RR, 23RL of the corresponding disc brake units 21FR, 21FL, 21RR, 21RL. Thereby, each wheel cylinder 23 can communicate with the main flow path 45.

  In addition, ABS holding valves 51, 52, 53 and 54 are provided in the middle of the individual flow paths 41, 42, 43 and 44. Each of the ABS holding valves 51 to 54 has a solenoid and a spring that are ON / OFF controlled, and both are normally open electromagnetic control valves that are opened when the solenoid is in a non-energized state. Each of the ABS holding valves 51 to 54 in the opened state can distribute the brake fluid in both directions. That is, the brake fluid can flow from the main flow path 45 to the wheel cylinder 23, and conversely, the brake fluid can also flow from the wheel cylinder 23 to the main flow path 45. When the solenoid is energized and the ABS holding valves 51 to 54 are closed, the flow of brake fluid in the individual flow paths 41 to 44 is blocked.

  Further, the wheel cylinder 23 is connected to the reservoir channel 55 via pressure reducing channels 46, 47, 48 and 49 connected to the individual channels 41 to 44, respectively. ABS decompression valves 56, 57, 58 and 59 are provided in the middle of the decompression channels 46, 47, 48 and 49. Each of the ABS pressure reducing valves 56 to 59 has a solenoid and a spring that are ON / OFF controlled, and is a normally closed electromagnetic control valve that is closed when the solenoid is in a non-energized state. When the ABS pressure reducing valves 56 to 59 are closed, the flow of brake fluid in the pressure reducing flow paths 46 to 49 is blocked. When the solenoid is energized and the ABS pressure reducing valves 56 to 59 are opened, the brake fluid is allowed to flow through the pressure reducing flow paths 46 to 49, and the brake fluid flows from the wheel cylinder 23 to the pressure reducing flow paths 46 to 49 and It returns to the reservoir 34 via the reservoir channel 55. The reservoir channel 55 is connected to the reservoir 34 of the master cylinder unit 27 via a reservoir pipe 77.

  The main channel 45 has a separation valve 60 in the middle. By this separation valve 60, the main channel 45 is divided into a first channel 45 a connected to the individual channels 41 and 42 and a second channel 45 b connected to the individual channels 43 and 44. The first flow path 45a is connected to the front wheel wheel cylinders 23FR and 23FL via the individual flow paths 41 and 42, and the second flow path 45b is connected to the rear wheel wheel cylinder via the individual flow paths 43 and 44. Connected to 23RR and 23RL.

  The separation valve 60 has a solenoid and a spring that are ON / OFF controlled, and is a normally closed electromagnetic control valve that is closed when the solenoid is in a non-energized state. When the separation valve 60 is in the closed state, the flow of brake fluid in the main flow path 45 is blocked. When the solenoid is energized and the separation valve 60 is opened, the brake fluid can be circulated bidirectionally between the first flow path 45a and the second flow path 45b.

  In the hydraulic actuator 40, a master channel 61 and a regulator channel 62 communicating with the main channel 45 are formed. More specifically, the master channel 61 is connected to the first channel 45 a of the main channel 45, and the regulator channel 62 is connected to the second channel 45 b of the main channel 45. The master channel 61 is connected to a master pipe 37 that communicates with the master cylinder 32. The regulator channel 62 is connected to a regulator pipe 38 that communicates with the regulator 33.

  The master channel 61 has a master cut valve 64 in the middle. The master cut valve 64 is provided on the brake fluid supply path from the master cylinder 32 to each wheel cylinder 23. The master cut valve 64 has a solenoid and a spring that are ON / OFF-controlled, and the valve closing state is guaranteed by the electromagnetic force generated by the solenoid when supplied with a prescribed control current, so that the solenoid is in a non-energized state. It is a normally open electromagnetic control valve that is opened in some cases. The master cut valve 64 in the opened state can cause the brake fluid to flow in both directions between the master cylinder 32 and the first flow path 45 a of the main flow path 45. When a prescribed control current is applied to the solenoid and the master cut valve 64 is closed, the flow of brake fluid in the master flow path 61 is interrupted.

  A stroke simulator 69 is connected to the master channel 61 via a simulator cut valve 68 on the upstream side of the master cut valve 64. That is, the simulator cut valve 68 is provided in the first simulator flow path 78 that branches from the master flow path 61 upstream of the master cut valve 64 and is connected to the stroke simulator 69. The stroke simulator 69 is also connected to the system on the regulator 33 side by the second simulator flow path 79.

  The simulator cut valve 68 has a solenoid and a spring that are ON / OFF controlled, and the valve opening state is guaranteed by the electromagnetic force generated by the solenoid upon receipt of a specified control current, and the solenoid is in a non-energized state. It is a normally closed electromagnetic control valve that is closed in some cases. When the simulator cut valve 68 is closed, the flow of brake fluid between the master flow path 61 and the stroke simulator 69 is blocked. When the solenoid is energized and the simulator cut valve 68 is opened, the brake fluid can be circulated bidirectionally between the master cylinder 32 and the stroke simulator 69.

  The stroke simulator 69 creates a reaction force corresponding to the depression force of the brake pedal 24 by the driver when the simulator cut valve 68 is opened. In the present embodiment, as will be described later with reference to FIG. 2, a stroke simulator 69 of a type incorporating a so-called gas spring is employed. As a characteristic of the stroke simulator 69 for realizing a good brake feeling, for example, when the stroke is small, the reaction force increase rate with respect to the stroke increase is relatively large, and when the stroke is large, the reaction force increase rate with respect to the stroke increase is Non-linearity is desirable, such as being relatively small. A stroke simulator incorporating a gas spring is preferable in that it is possible to realize such non-linearity at a low cost with a relatively simple structure. As the stroke simulator 69, one including a plurality of pistons and springs can be adopted. In this case, one having a multistage spring characteristic is adopted in order to improve the feeling of brake operation by the driver. It is preferable.

  The regulator flow path 62 has a regulator cut valve 65 in the middle. The regulator cut valve 65 is provided on the brake fluid supply path from the regulator 33 to each wheel cylinder 23. The regulator cut valve 65 also has a solenoid and a spring that are ON / OFF controlled, and the valve closing state is guaranteed by the electromagnetic force generated by the solenoid upon receipt of a specified control current, and the solenoid is in a non-energized state. It is a normally open electromagnetic control valve that is opened in some cases. The regulator cut valve 65 that has been opened can cause the brake fluid to flow in both directions between the regulator 33 and the second flow path 45 b of the main flow path 45. When the solenoid is energized and the regulator cut valve 65 is closed, the flow of brake fluid in the regulator flow path 62 is blocked.

  In the hydraulic actuator 40, an accumulator channel 63 is also formed in addition to the master channel 61 and the regulator channel 62. One end of the accumulator channel 63 is connected to the second channel 45 b of the main channel 45, and the other end is connected to an accumulator pipe 39 that communicates with the accumulator 35.

  The accumulator flow path 63 has a pressure-increasing linear control valve 66 in the middle. Further, the accumulator channel 63 and the second channel 45 b of the main channel 45 are connected to the reservoir channel 55 via the pressure-reducing linear control valve 67. The pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67 each have a linear solenoid and a spring, and both are normally closed electromagnetic control valves that are closed when the solenoid is in a non-energized state. In the pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67, the opening degree of the valve is adjusted in proportion to the current supplied to each solenoid.

  The pressure-increasing linear control valve 66 is provided as a common pressure-increasing control valve for each of the wheel cylinders 23 provided corresponding to each wheel. Similarly, the pressure reducing linear control valve 67 is provided as a pressure reducing control valve common to the wheel cylinders 23. That is, in this embodiment, the pressure-increasing linear control valve 66 and the pressure-reducing linear control valve 67 are a pair of common control valves that control the supply and discharge of the working fluid sent from the power hydraulic pressure source 30 to each wheel cylinder 23. It is provided as. If the pressure-increasing linear control valve 66 and the like are made common to each wheel cylinder 23 in this way, it is preferable from the viewpoint of cost as compared with the case where a linear control valve is provided for each wheel cylinder 23.

  Here, the differential pressure between the inlet and outlet of the pressure-increasing linear control valve 66 corresponds to the differential pressure between the pressure of the brake fluid in the accumulator 35 and the pressure of the brake fluid in the main flow path 45, and the inlet and outlet of the pressure-reducing linear control valve 67. The pressure difference therebetween corresponds to the pressure difference between the brake fluid pressure in the main flow path 45 and the brake fluid pressure in the reservoir 34. Further, the electromagnetic driving force according to the power supplied to the linear solenoid of the pressure increasing linear control valve 66 and the pressure reducing linear control valve 67 is F1, the spring biasing force is F2, and the pressure increasing linear control valve 66 and the pressure reducing linear control valve are Assuming that the differential pressure acting force according to the differential pressure between the inlet / outlet of 67 is F3, the relationship of F1 + F3 = F2 is established. Therefore, the differential pressure between the inlet and outlet of the pressure-increasing linear control valve 66 and the pressure-reducing linear control valve 67 is controlled by continuously controlling the power supplied to the linear solenoids of the pressure-increasing linear control valve 66 and the pressure-reducing linear control valve 67. can do.

  In the brake control device 20, the power hydraulic pressure source 30 and the hydraulic actuator 40 are controlled by a brake ECU 70 as a control unit in the present embodiment. The brake ECU 70 is configured as a microprocessor including a CPU, and includes a ROM that stores various programs, a RAM that temporarily stores data, an input / output port, a communication port, and the like in addition to the CPU. The brake ECU 70 can communicate with a host hybrid ECU (not shown) and the like, and based on control signals from the hybrid ECU and signals from various sensors, the pump 36 of the power hydraulic pressure source 30 and the hydraulic pressure The electromagnetic control valves 51 to 54, 56 to 59, 60, and 64 to 68 constituting the actuator 40 are controlled.

  Further, a regulator pressure sensor 71, an accumulator pressure sensor 72, and a control pressure sensor 73 are connected to the brake ECU 70. The regulator pressure sensor 71 detects the pressure of the brake fluid in the regulator flow path 62 on the upstream side of the regulator cut valve 65, that is, the regulator pressure, and gives a signal indicating the detected value to the brake ECU 70. The accumulator pressure sensor 72 detects the pressure of the brake fluid in the accumulator flow path 63, that is, the accumulator pressure on the upstream side of the pressure increasing linear control valve 66, and gives a signal indicating the detected value to the brake ECU 70. The control pressure sensor 73 detects the pressure of the brake fluid in the first flow path 45a of the main flow path 45, and gives a signal indicating the detected value to the brake ECU 70. The detection values of the pressure sensors 71 to 73 are sequentially given to the brake ECU 70 every predetermined time, and are stored and held in a predetermined storage area of the brake ECU 70 by a predetermined amount.

  When the separation valve 60 is opened and the first flow path 45 a and the second flow path 45 b of the main flow path 45 communicate with each other, the output value of the control pressure sensor 73 is the low pressure of the pressure-increasing linear control valve 66. This indicates the hydraulic pressure on the high pressure side of the pressure-reducing linear control valve 67 and the output value can be used to control the pressure-increasing linear control valve 66 and the pressure-reducing linear control valve 67. When the pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67 are closed and the master cut valve 64 is opened, the output value of the control pressure sensor 73 indicates the master cylinder pressure. Further, the separation valve 60 is opened so that the first flow path 45a and the second flow path 45b of the main flow path 45 communicate with each other, and the ABS holding valves 51 to 54 are opened, while the ABS pressure reducing valves 56 are opened. When? 59 is closed, the output value of the control pressure sensor 73 indicates the working fluid pressure acting on each wheel cylinder 23, i.e., the wheel cylinder pressure.

  Further, the sensor connected to the brake ECU 70 includes a stroke sensor 25 provided on the brake pedal 24. The stroke sensor 25 detects a pedal stroke as an operation amount of the brake pedal 24 and gives a signal indicating the detected value to the brake ECU 70. The output value of the stroke sensor 25 is also sequentially given to the brake ECU 70 every predetermined time, and is stored and held in a predetermined storage area of the brake ECU 70 by a predetermined amount. A brake operation state detection unit other than the stroke sensor 25 may be provided in addition to the stroke sensor 25 or in place of the stroke sensor 25 and connected to the brake ECU 70. Examples of the brake operation state detection means include a pedal depression force sensor that detects an operation force of the brake pedal 24 and a brake switch that detects that the brake pedal 24 is depressed.

  The brake control device 20 configured as described above can execute brake regeneration cooperative control. The brake control device 20 starts braking in response to a braking request. The braking request is generated when a braking force should be applied to the vehicle, for example, when the driver operates the brake pedal 24. In response to the braking request, the brake ECU 70 calculates a required braking force, and calculates a required hydraulic braking force that is a braking force to be generated by the brake control device 20 by subtracting the braking force due to regeneration from the required braking force. Here, the braking force by regeneration is supplied to the brake control device 20 from the hybrid ECU. Then, the brake ECU 70 calculates the target hydraulic pressure of each wheel cylinder 23FR to 23RL based on the calculated required hydraulic braking force. The brake ECU 70 determines the value of the control current supplied to the pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67 based on the feedback control law so that the wheel cylinder pressure becomes the target hydraulic pressure.

  As a result, in the brake control device 20, the brake fluid is supplied from the power hydraulic pressure source 30 to the wheel cylinders 23 via the pressure-increasing linear control valve 66, and braking force is applied to the wheels. Further, brake fluid is discharged from each wheel cylinder 23 through the pressure-reducing linear control valve 67 as necessary, and the braking force applied to the wheel is adjusted. In the present embodiment, a wheel cylinder pressure control system is configured including the power hydraulic pressure source 30, the pressure-increasing linear control valve 66, the pressure-decreasing linear control valve 67, and the like. Braking force control by so-called brake-by-wire is performed by the wheel cylinder pressure control system. The wheel cylinder pressure control system is provided in parallel to the brake fluid supply path from the master cylinder unit 27 to the wheel cylinder 23.

  At this time, the brake ECU 70 closes the regulator cut valve 65 so that the brake fluid sent from the regulator 33 is not supplied to the wheel cylinder 23. Further, the brake ECU 70 closes the master cut valve 64 and opens the simulator cut valve 68. This is because the brake fluid sent from the master cylinder 32 in accordance with the operation of the brake pedal 24 by the driver is supplied not to the wheel cylinder 23 but to the stroke simulator 69. During the brake regeneration cooperative control, a differential pressure corresponding to the magnitude of the regenerative braking force acts between the upstream and downstream of the regulator cut valve 65 and the master cut valve 64.

  FIG. 2 is a diagram schematically showing a stroke simulator 69 according to an embodiment of the present invention. In the present embodiment, a so-called bellows type accumulator incorporating a metal bellows 80 is used as the stroke simulator 69, for example. Inside the stroke simulator 69, a gas chamber 82 in which a gas such as nitrogen is sealed, and a fluid chamber 84 as a hydraulic fluid chamber for accommodating a brake fluid flowing from the master cylinder 32 in response to a brake operation are formed. Has been.

  Since this metal bellows accumulator has a structure in which gas leakage is less likely to occur than other types of gas springs, it is preferable in that the possibility of gas leaking into the brake system can be reduced. Other types of gas springs include, for example, a bladder type using a diaphragm such as rubber, a free piston type using a free piston, and the like, and these can be employed as a stroke simulator according to the present invention.

  The stroke simulator 69 is formed with two outflow inlets, that is, a first port 86 and a second port 88 for communicating the fluid chamber 84 with the outside. A first simulator channel 78 is connected to the first port 86. For this reason, the brake fluid pressurized by the master cylinder 32 according to the brake operation flows into the fluid chamber 84 from the first port 86 through the master channel 61, the simulator cut valve, the first simulator channel 78, and the like. The second simulator channel 79 is connected to the second port 88. The fluid chamber 84 is in direct communication with the regulator 33 through the second port 88 and the second simulator flow path 79 without passing through an on-off valve or the like. For this reason, the brake fluid can circulate between the fluid chamber 84 and the regulator 33 regardless of the presence or absence of the brake operation.

  In the present embodiment, the first communication path is configured including the first port 86 and the first simulator flow path, and the second communication path is configured including the second port 88 and the second simulator flow path. Has been. The second communication path connects the regulator 33 and the fluid chamber 84, and circulates the hydraulic fluid so that the gas pressure in the gas chamber is maintained at a predetermined pressure such as atmospheric pressure when the brake is not operated. The second communication path may be configured to allow the flow of the hydraulic fluid at least when the brake simulator is not operated when the stroke simulator 69 is not used.

  The stroke simulator 69 mainly includes a container 90, a bellows 80, a seal plate 92, and a lip seal 94. The container 90 has a substantially cylindrical shape, and in this embodiment, one end is closed and the other end is opened. A bellows mounting portion 96 is fixed to the inner surface of the closed end of the container 90. A lip seal attachment 98 is attached to the open end of the container 90. A connecting portion between the container 90 and the lip seal attaching portion 98 is joined in a liquid-tight manner.

  The bellows 80 is, for example, a metal member configured in a cylindrical shape so as to be expandable and contractable in the axial direction. One end of the bellows 80 is fixed to a bellows attachment portion 96, and a seal plate 92 is airtightly attached to the other end of the bellows 80. The bellows 80 is disposed coaxially with the container 90 inside the cylindrical container 90, and the diameter of the bellows 80 is slightly smaller than the inner diameter of the container 90. Therefore, a gap 100 is formed between the outer side of the bellows 80 and the inner surface of the container 90.

  The seal plate 92 is a disk-shaped member, and its diameter is slightly smaller than the inner diameter of the container 90. A guide 102 is attached to the outer periphery of the seal plate 92. The guide 102 is formed so as to slide smoothly along the inner surface of the container 90 when the seal plate 92 moves in the axial direction of the container 90 as the bellows 80 expands and contracts. For example, the guides 102 are discretely provided at a plurality of locations on the outer peripheral portion of the seal plate 92. In the present embodiment, the guide 102 is provided at a position facing the center of the seal plate 92 across the center. The guide 102 is attached to the surface of the seal plate 92 on the bellows 80 side.

  A plug member 104 for filling and sealing the gas sealed in the gas chamber 82 is provided at the center of the closed end of the container 90. A through-hole extending from the plug member 104 to the gas chamber 82 is formed in the central portion of the bellows attachment portion 96 in the axial direction. Therefore, the gas can be filled from the plug member 104 into the gas chamber 82, and the gas can be sealed in the gas chamber 82 by closing the plug member 104. The gas pressure sealed in the gas chamber 82 is set to an appropriate value as the gas pressure in the gas chamber 82 at normal temperature and when the stroke simulator 69 is not used, for example, atmospheric pressure.

  The bellows 80 and the seal plate 92 form a movable part inside the stroke simulator 69. By this movable portion, pressure is transmitted between the gas chamber 82 and the fluid chamber 84 which are formed inside the stroke simulator 69 and partitioned adjacent to each other. This movable part functions as a pressure transmission member between the gas chamber 82 and the fluid chamber 84. As described above, the seal plate 92 is attached to the end of the bellows 80 so as to be movable in the axial direction along the inner surface of the container 90. Therefore, the bellows 80 is expanded and contracted by the differential pressure received from both surfaces of the seal plate 92, that is, the differential pressure between the gas pressure and the hydraulic fluid pressure, and the seal plate 92 moves inside the container 90. The seal plate 92 moves to a position where the forces acting on the seal plate 92 are balanced.

  The force acting on the seal plate 92 includes, for example, the gas pressure in the gas chamber 82, the fluid pressure in the fluid chamber 84, the elastic force due to the expansion and contraction of the bellows 80, and the sliding friction force with the inner surface of the container 90. When the elastic force due to the expansion and contraction of the bellows 80 and the sliding frictional force with the inner surface of the container 90 are sufficiently small, the differential pressure between the gas pressure in the gas chamber 82 and the fluid pressure in the fluid chamber 84 becomes zero. Move to a position where the pressures are equal.

  When the seal plate 92 moves, the volume of the gas chamber 82 increases and the volume of the fluid chamber 84 decreases, or the volume of the gas chamber 82 decreases and the volume of the fluid chamber 84 increases. The change amount of the volume of the gas chamber 82 is equal to the change amount of the volume of the fluid chamber 84. As described above, the seal plate 92 moves according to the differential pressure between the gas pressure and the hydraulic fluid pressure, and the volumes of the gas chamber 82 and the fluid chamber 84 increase or decrease in a complementary manner.

  An annular lip seal 94 is attached to the lip seal attachment portion 98. The lip seal 94 and the seal plate 92 cooperate with each other when they abut against each other to block the flow of the hydraulic fluid in the fluid chamber 84 from the outside. The lip seal mounting portion 98 is formed with a recess 105 for accommodating the lip seal 94 on the inner surface side of the container 90, and the lip seal 94 is fitted into the recess 105. The lip seal attachment portion 98 is formed with a first through hole 106 that forms a part of the first port 86 along the axial direction of the container 90. The fluid chamber 84 communicates with the outside through the first through hole 106. The seal plate 92 is attached to the end of the bellows 80 so as to face the first port 86 in the axial direction of the container 90.

  Further, a second through hole 108 that forms a second port 88 is provided on the side surface of the container 90. The fluid chamber 84 communicates with the outside through the second through hole 108. Through this second through hole 108, the brake fluid can flow in and out of the outside regardless of the operating state of the brake and whether or not the stroke simulator 69 is used. The second through hole 108 is formed in the vicinity of the container end on the opposite side of the gas chamber 82 on the cylindrical side surface of the container 90, that is, in the vicinity of the container end on the fluid chamber 84 side. When a bladder type or free piston type gas spring is used, the second port 88 maintains communication between the fluid chamber 84 and the outside even when the bladder is expanded to the maximum or the free piston is displaced to the maximum. For example, the second through hole 108 is preferably formed at the end of the container opposite to the gas chamber 82.

  In the stroke simulator 69 according to the present embodiment, the inner region of the bellows 80 is basically defined as the gas chamber 82. The gas chamber 82 is an area surrounded by the movable portion including the seal plate 92 and the bellows 80 and the bellows mounting portion 96. The fluid chamber 84 is basically a portion of the internal space of the container 90 excluding the gas chamber 82. The fluid chamber 84 is an area sandwiched between the movable portion including the seal plate 92 and the bellows 80 and the container 90. The fluid chamber 84 is formed so as to surround the gas chamber 82 inside.

  When the seal plate 92 is away from the lip seal 94 as indicated by a solid line in FIG. 2, the fluid chamber 84 is a cylindrical space sandwiched between the seal plate 92 and the lip seal mounting portion 98 inside the container 90. And a gap 100 between the cylindrical side surface of the container 90 and the bellows 80. On the other hand, when the seal plate 92 is in contact with the lip seal 94 as indicated by a broken line in FIG. 2, most of the internal space of the container 90 is occupied by the gas chamber 82. The remainder of the space, that is, the gap 100 between the cylindrical side surface of the container 90 and the bellows 80 becomes the fluid chamber 84.

  As described above, in this embodiment, the gap 100 between the cylindrical inner surface of the container 90 and the bellows 80 constitutes a part of the fluid chamber 84, and the fluid chamber 84 is formed so as to surround the gas chamber 82 inside. ing. Therefore, it is preferable in that the second port 88 for allowing the fluid chamber 84 to communicate with the outside and to distribute the brake fluid can be easily formed at an arbitrary position on the side surface of the container 90.

  In the stroke simulator 69 configured as described above, in the initial state, the seal plate 92 is in contact with the lip seal 94 as shown by a broken line in FIG. Here, the initial state refers to a state where the stroke simulator 69 does not need to generate a reaction force when the stroke simulator 69 is not used, that is, a brake operation. In the brake control device of the brake-by-wire system, for example, the initial state is typically when the brake pedal 24 is not operated. However, in the so-called manual brake mode in which the brake fluid pressurized by the driver's pedal force is supplied directly to the wheel cylinder 23, it is necessary to generate a reaction force using the stroke simulator 69 even when the brake is operated. The stroke simulator 69 takes an initial state.

  In the initial state, the seal plate 92 contacts the lip seal 94 to seal the first port 86. Thereby, the distribution of the brake fluid in the first port 86 is blocked. In the brake control device according to the present embodiment, the normally closed simulator cut valve 68 is closed when the brake operation is not performed as described above. Therefore, the flow of brake fluid from the master cylinder 32 to the stroke simulator 69 is also blocked by the simulator cut valve 68.

  In the present embodiment, when the brake pedal 24 is operated by the driver and the simulator cut valve 68 is opened by the brake ECU 70, the master cylinder pressure pressurized according to the stroke of the brake pedal 24 is the first port 86. It acts on the seal plate 92 through. The bellows 80 is contracted by the hydraulic pressure acting on the seal plate 92, the seal between the seal plate 92 and the lip seal 94 is released, and the brake fluid flows into the fluid chamber 84 of the stroke simulator 69. As shown in FIG. 2, the gas chamber 82 is compressed by the seal plate 92 that moves to a position where the hydraulic pressure and the gas pressure are balanced, and a reaction force against the brake operation is generated.

  At this time, since the regulator pressure is substantially the same as the master cylinder pressure, the hydraulic pressure is balanced between the regulator 33 and the fluid chamber 84, and basically the brake fluid flows between them. do not do. Therefore, the influence on the brake feeling when the stroke simulator 69 is used by connecting the stroke simulator 69 and the regulator 33 is negligible or not at all.

  Incidentally, the gas sealed in the gas chamber 82 may expand or contract due to, for example, a temperature change. For example, when the vehicle travels, the temperature of the stroke simulator 69 increases with the vehicle temperature, and the gas may expand. If the second port 88 is not provided, the stroke simulator 69 is sealed in the initial state. For example, when the temperature rises, the gas pressure increases. When the use of the stroke simulator 69 is started in this state, the operational feeling of the brake pedal 24 is different from the original one because the gas pressure is different from the original initial state. For example, when the gas pressure is increased due to a temperature rise, the operation feeling is harder than the original operation feeling.

  According to this embodiment, the fluid chamber 84 is communicated with the regulator 33 through the second port 88 and the second simulator flow path 79. When the brake is not operated, the regulator pressure is equal to the reservoir pressure, which is a low pressure source, and becomes atmospheric pressure. For this reason, the gas pressure and the regulator pressure of the stroke simulator 69 are basically equal. Therefore, the brake fluid flows between the fluid chamber 84 and the regulator 33 according to the expansion or contraction of the gas chamber 82, and the gas pressure in the gas chamber 82 is kept constant at atmospheric pressure.

  Specifically, the bellows 80 expands and contracts according to the expansion or contraction of the gas in the gas chamber 82, and the seal plate 92 moves. As a result, the volume of the fluid chamber 84 increases or decreases in a complementary manner to the volume of the gas chamber 82. Brake fluid corresponding to the amount of change in the volume of the fluid chamber 84 flows between the fluid chamber 84 and the regulator 33. As described above, the brake fluid flows between the fluid chamber 84 and the regulator 33 according to the fluctuation of the gas pressure, so that the expansion or contraction of the gas in the gas chamber 82 is alleviated and the gas pressure is changed regardless of the temperature change. Maintained at atmospheric pressure. Thereby, the fluctuation | variation of gas pressure is suppressed and the brake feeling implement | achieved by the stroke simulator 69 can be stabilized.

  In the present embodiment, the fluid chamber 84 of the stroke simulator 69 is communicated with the regulator 33. The regulator 33 is a pressurizing chamber that substantially regulates the working fluid to the working fluid pressure in the master cylinder 32. For this reason, when the brake is not operated, the regulator pressure is adjusted to the atmospheric pressure similarly to the master cylinder pressure. Therefore, for example, even if hydraulic fluid flows from the fluid chamber 84 into the regulator 33 due to a temperature rise, the regulator pressure is quickly adjusted to atmospheric pressure without greatly increasing. Thus, since the regulator pressure is quickly adjusted to atmospheric pressure, it is also preferable in that the fluctuation of the gas pressure is quickly suppressed.

  Further, according to the present embodiment, even if the gas leaks from the gas chamber 82, the gas from the master cylinder unit 27 or the power hydraulic pressure source 30 to the hydraulic fluid path for braking to the wheel cylinder 23 is supplied. This is preferable in that mixing is difficult to occur. In particular, when the brake is not operated, the fluid chamber 84 of the stroke simulator 69 is cut off from the brake hydraulic fluid path by the seal plate 92 and the lip seal 94 and is further cut off from the brake system by the simulator cut valve 68. Therefore, the leaked gas easily flows into the regulator 33 through the second port 88 and the second simulator flow path 79 without being mixed into the brake hydraulic fluid path. Gas leaking from the regulator 33 to the atmosphere through the reservoir 34 is released.

  FIG. 3 is a diagram schematically illustrating a stroke simulator 69 according to a modification of the present embodiment. This modification is an embodiment particularly effective when the gas pressure in the initial state is set to a value different from atmospheric pressure, for example, higher than atmospheric pressure. For example, when a firm brake feeling is required as a required characteristic for the stroke simulator 69, the gas pressure may be higher than the atmospheric pressure. A predetermined set pressure is appropriately set according to the required characteristics. In this case, the stroke simulator 69 may be a hybrid structure stroke simulator 69 in which gas springs and coil springs are provided in multiple stages.

  This modification differs from the above-described embodiment in that the check valve 110 is provided in the middle of the second simulator flow path 79. When the check valve 110 is opened, the brake fluid can flow between the fluid chamber 84 and the regulator 33, and the pressures in the gas chamber 82, the fluid chamber 84, and the regulator 33 become equal. On the other hand, when the check valve 110 is closed, the flow of brake fluid between the fluid chamber 84 and the regulator 33 is blocked, and the fluid chamber 84 and the regulator 33 are kept at different pressures.

  The check valve 110 is opened when the gas pressure in the gas chamber 82 exceeds the set pressure described above, and the valve opening pressure is set so that the brake fluid can flow out from the fluid chamber 84 to the regulator 33. . For this reason, for example, when the gas expands due to a temperature rise or the like in the stroke simulator 69, the check valve 110 is opened while the fluid pressure in the fluid chamber 84 rises and exceeds the set pressure as the gas pressure rises. The brake fluid flows out from the fluid chamber 84 to the regulator 33 and the pressure in the gas chamber 82 and the fluid chamber 84 is reduced to the set pressure. When the pressures of the gas chamber 82 and the fluid chamber 84 reach the set pressure, the check valve 110 is naturally closed and the gas pressure and the fluid chamber 84 are maintained at the set pressure. As a result, similarly to the above-described embodiment, the fluctuation of the brake feeling due to the temperature change is suppressed, and a good brake feeling can be stably realized.

  Further, in this modification, the gas pressure inside the stroke simulator 69 and the hydraulic fluid pressure can be kept at the same pressure. For this reason, the load acting on the bellows 80 or the like from the gas pressure or the hydraulic fluid pressure is small, which is preferable from the viewpoint of improving the durability of the bellows 80 or the like.

It is a distribution diagram showing a brake control device concerning one embodiment of the present invention. It is a figure showing typically the stroke simulator concerning one embodiment of the present invention. It is a figure which shows typically the stroke simulator which concerns on the modification of one Embodiment of this invention.

Explanation of symbols

  20 brake control device, 32 master cylinder, 33 regulator, 69 stroke simulator, 78 first simulator flow path, 79 second simulator flow path, 86 first port, 88 second port, 110 check valve.

Claims (3)

A master cylinder including two pressurizing chambers in which the hydraulic fluid is pressurized to substantially the same pressure by a driver's brake operation;
A reaction force against a brake operation due to a gas pressure generated in accordance with the amount of hydraulic fluid flowing into the hydraulic fluid chamber, including a hydraulic fluid chamber containing hydraulic fluid flowing from the master cylinder and a gas chamber in which gas is sealed A stroke simulator that creates
A first communication path that connects one of the pressurizing chamber and the hydraulic fluid chamber so that the hydraulic fluid is allowed to flow when the stroke simulator is used and the hydraulic fluid is blocked when the stroke simulator is not used;
A brake device comprising: a second communication path connecting the other of the pressurizing chamber and the hydraulic fluid chamber.   2. The check valve that allows the second communication passage to be provided with a check valve that allows the hydraulic fluid to flow out of the hydraulic fluid chamber when the gas pressure exceeds a predetermined pressure. Brake equipment. A hydraulic fluid chamber for containing hydraulic fluid flowing in and out in response to a brake operation;
A gas chamber in which a gas is enclosed, and whose volume is increased or decreased in a complementary manner to the hydraulic fluid chamber according to a differential pressure with the hydraulic fluid chamber;
A pressure transmission member between the hydraulic fluid chamber and the gas chamber;
A first inlet and outlet opening formed in the hydraulic fluid chamber for the inflow and outflow of hydraulic fluid to the hydraulic fluid chamber of the braking operation,
A stroke simulator comprising: a second inlet / outlet formed in the hydraulic fluid chamber ;
The pressure transmission member interrupts the flow of hydraulic fluid at the first outlet when the stroke simulator is not used;
The second outlet / inlet allows the hydraulic fluid to flow in / out of the hydraulic fluid chamber and the outside in which the first outlet / inlet is blocked by the pressure transmission member in accordance with the gas pressure in the gas chamber. Stroke simulator characterized by

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