JP4900320B2 - Master cylinder - Google Patents

Description

  The present invention relates to a master cylinder that is provided in an electronically controlled brake system for a vehicle and generates a hydraulic pressure corresponding to an operation of a brake pedal.

  2. Description of the Related Art In recent years, many electronically controlled brake systems that control the braking force of each wheel so as to give an optimal braking force to the vehicle according to the traveling state of the vehicle have been adopted as a braking device in the vehicle. In such an electronically controlled brake system, an electromagnetic flow control valve is used to monitor the wheel cylinder pressure of each wheel by a pressure sensor and to achieve a target hydraulic pressure calculated based on the brake pedal operation amount of the driver. Is controlling.

A master cylinder provided in such an electronically controlled brake system usually has a master hydraulic chamber that generates hydraulic pressure in response to an operation of a brake pedal by a piston slidably accommodated in a cylinder housing, and a reservoir tank. An atmospheric pressure chamber is formed in which the hydraulic pressure is maintained at atmospheric pressure. When the piston is in the initial position, the master hydraulic chamber communicates with the atmospheric pressure chamber, and when the piston moves forward from the initial position by a predetermined stroke or more, the communication between the master hydraulic chamber and the atmospheric pressure chamber is blocked. It is configured as follows. The stroke amount from the initial position of the piston until the communication between the master hydraulic pressure chamber and the atmospheric pressure chamber is cut off is referred to as “port idle”. In the master cylinder, by providing the port idle in this manner, in a state where the piston is in the initial position, that is, in a state where the brake pedal is not depressed, so-called brake drag is generated due to the hydraulic pressure generated in the master cylinder. This can be prevented (see, for example, Patent Document 1).
JP 2005-313703 A

  However, in such a master cylinder having a port idle, hydraulic oil flows from the master hydraulic pressure chamber to the atmospheric pressure chamber even if the brake pedal is depressed until the piston moves forward from the initial position by the amount of the port idle. Not so much pedal reaction force is generated, and since the pedal reaction force suddenly occurs after the piston moves by the port idle, the driver may feel rattling at the beginning of the brake operation, and the pedal feeling may be uncomfortable. is there.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a master cylinder capable of improving pedal feeling in brake operation.

In order to solve the above problems, a master cylinder according to an aspect of the present invention is a master cylinder that is provided in a brake control device of a vehicle and that sends hydraulic oil in response to an operation of a brake pedal by a driver. A piston that is slidably received in the cylinder housing, forms a master hydraulic pressure chamber and an atmospheric pressure chamber in the cylinder housing, a piston rod that connects the piston and the brake pedal, and a piston in an initial position A communication control means for connecting the master hydraulic pressure chamber to the atmospheric pressure chamber and shutting off the communication between the master hydraulic pressure chamber and the atmospheric pressure chamber when the piston moves forward from the initial position beyond a predetermined port idle; and the piston rod; by generating a suction force between the vehicle body side of the vehicle, the piston moves port idle content from the initial position Until that, and a resistance force generating means for generating a resistance force against the forward movement of the piston.

  According to this aspect, by providing the resistance force generating means for generating the resistance force against the forward movement of the piston before the piston moves from the initial position by the port idle, the driver can Since the pedal reaction force can be felt in the case, the backlash feeling is reduced and the pedal feeling can be improved.

  The resistance force generating means may generate a resistance force against the forward movement of the piston by a magnetic force. The resistance force generation means may include an electromagnet and a control unit that generates a resistance force with respect to the forward movement of the piston by controlling a current supplied to the electromagnet. In this case, a resistance force can be suitably generated.

The control unit may energize the electromagnet so that a backward force is generated in the piston when the piston moves forward from the initial position by the amount of port idle .

  The control unit may stop energization of the electromagnet when the brake pedal is operated for a predetermined stroke amount or more. When it is not necessary to generate a resistance force, power consumption can be reduced by stopping energization.

  The control unit may energize the electromagnet so that a forward force is generated in the piston when the brake pedal is operated at a predetermined stroke speed or higher. When the brake pedal is operated at a high speed, it is considered that a sudden braking force is required. In such a case, the braking force can be quickly generated by energizing the electromagnet so that a forward force is generated in the piston and assisting the pedal operation force.

  The resistance generating means generates a suction force between the piston rod and the vehicle body side, thereby resisting the forward movement of the piston until the piston moves from the initial position by the amount of port idle. It may generate a force. In this case, there is little backlash and a suitable pedal feeling can be realized.

  ADVANTAGE OF THE INVENTION According to this invention, the master cylinder which can improve the pedal feeling in brake operation can be provided.

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

  FIG. 1 is a diagram illustrating a configuration of a brake control device including a master cylinder 14 according to an embodiment of the present invention. A brake control device 10 shown in FIG. 1 constitutes an electronically controlled brake system (ECB) for a vehicle, and brakes for four wheels of a vehicle based on an operation amount of a brake pedal 12 as a brake operation member by a driver. Is optimally controlled.

  The brake pedal 12 is connected to a master cylinder 14 that sends hydraulic oil in response to a depression operation by the driver. The detailed configuration of the master cylinder 14 will be described later. The brake pedal 12 is provided with a stroke sensor 46 for detecting the depression stroke.

  Connected to the first output port 14a of the master cylinder 14 is a stroke simulator 24 that creates a pedal stroke according to the depression force of the brake pedal 12 by the driver. The detailed configuration of the stroke simulator 24 will be described later.

  A simulator cut valve 23 is provided in the middle of the flow path connecting the master cylinder 14 and the stroke simulator 24. The simulator cut valve 23 is a normally-closed electromagnetic on-off valve that opens when energized during normal operation and closes when de-energized such as during an abnormality. The master cylinder 14 is connected to a reservoir tank 26 for storing hydraulic oil.

  A brake hydraulic control pipe 18 for the right front wheel is connected to the first output port 14a of the master cylinder 14, and the brake hydraulic control pipe 18 is a wheel cylinder for the right front wheel that applies a braking force to the right front wheel. It is connected to 20FR. A brake hydraulic control pipe 16 for the left front wheel is connected to the second output port 14b of the master cylinder 14, and the brake hydraulic control pipe 16 is used for the left front wheel that applies a braking force to the left front wheel. It is connected to the wheel cylinder 20FL.

  A right electromagnetic on-off valve 22FR is provided in the middle of the brake hydraulic control pipe 18 for the right front wheel, and a left electromagnetic on-off valve 22FL is provided in the middle of the brake hydraulic control pipe 16 for the left front wheel. The right solenoid on-off valve 22FR and the left solenoid on-off valve 22FL are both normally open solenoid valves that are open when not energized and switched to closed when energized.

  A right master pressure sensor 48FR for detecting the master cylinder pressure on the right front wheel side is provided in the middle of the brake hydraulic control pipe 18 for the right front wheel. A left master pressure sensor 48FL for measuring the master cylinder pressure on the left front wheel side is provided.

  In the brake control apparatus 10, when the brake pedal 12 is depressed by the driver, the stroke operation amount is detected by the stroke sensor 46. The master detected by the right master pressure sensor 48FR and the left master pressure sensor 48FL is detected. The depressing operation force (depressing force) of the brake pedal 12 can also be obtained from the cylinder pressure. As described above, it is preferable from the viewpoint of fail-safe that the master cylinder pressure is monitored by the two pressure sensors 48FR and 48FL on the assumption of the failure of the stroke sensor 46. Hereinafter, the right master pressure sensor 48FR and the left master pressure sensor 48FL are collectively referred to as a master cylinder pressure sensor 48 as appropriate.

  On the other hand, one end of a hydraulic supply / discharge pipe 28 is connected to the reservoir tank 26, and a suction port of an oil pump 34 driven by a motor 32 is connected to the other end of the hydraulic supply / discharge pipe 28. . The discharge port of the oil pump 34 is connected to a high pressure pipe 30, and an accumulator 50 and a relief valve 53 are connected to the high pressure pipe 30. In the present embodiment, a reciprocating pump including two or more pistons (not shown) that are reciprocally moved by the motor 32 is employed as the oil pump 34. As the accumulator 50, an accumulator 50 that converts the pressure energy of hydraulic oil into pressure energy of an enclosed gas such as nitrogen is stored.

  The accumulator 50 stores the hydraulic oil whose pressure has been increased to about 14 to 22 MPa by the oil pump 34, for example. Further, the valve outlet of the relief valve 53 is connected to the hydraulic supply / exhaust pipe 28. When the pressure of the hydraulic oil in the accumulator 50 increases abnormally to, for example, about 25 MPa, the relief valve 53 is opened and the high pressure operation is performed. The oil is returned to the hydraulic supply / discharge pipe 28. Further, the high-pressure pipe 30 is provided with an accumulator pressure sensor 51 that detects an outlet pressure of the accumulator 50, that is, a pressure of hydraulic oil in the accumulator 50.

  The high pressure pipe 30 is connected to the right front wheel wheel cylinder 20FR, the left front wheel wheel cylinder 20FL, the right rear wheel wheel cylinder 20RR, and the left rear wheel through the pressure increasing valves 40FR, 40FL, 40RR, and 40RL. It is connected to the cylinder 20RL. Hereinafter, the wheel cylinders 20FR to 20RL will be collectively referred to as “wheel cylinders 20”, and the pressure increase valves 40FR to 40RL will be appropriately collectively referred to as “pressure increase valves 40”. Each of the pressure increasing valves 40 is a normally closed electromagnetic flow control valve (linear valve) that is closed when not energized and is used to increase the pressure of the wheel cylinder 20 as necessary. A disc brake unit is provided for each wheel of the vehicle (not shown), and each disc brake unit generates a braking force by pressing the brake pad against the disc by the action of the wheel cylinder 20.

  Further, the wheel cylinder 20FR for the right front wheel and the wheel cylinder 20FL for the left front wheel are connected to the hydraulic supply / discharge pipe 28 via the pressure reducing valve 42FR or 42FL, respectively. The pressure reducing valves 42FR and 42FL are normally closed electromagnetic flow control valves (linear valves) used for pressure reduction of the wheel cylinders 20FR and 20FL as necessary. On the other hand, the wheel cylinder 20RR for the right rear wheel and the wheel cylinder 20RL for the left rear wheel are connected to the hydraulic supply / discharge pipe 28 via a pressure reducing valve 42RR or 42RL which is a normally open electromagnetic flow control valve. . Hereinafter, the pressure reducing valves 42FR to 42RL are collectively referred to as “pressure reducing valve 42” as appropriate.

  Wheel cylinders for detecting the wheel cylinder pressure, which is the pressure of the hydraulic oil acting on the corresponding wheel cylinder 20, in the vicinity of the wheel cylinders 20FR to 20RL for the right front wheel, the left front wheel, the right rear wheel, and the left rear wheel Pressure sensors 44FR, 44FL, 44RR and 44RL are provided. Hereinafter, the wheel cylinder pressure sensors 44FR to 44RL are collectively referred to as “wheel cylinder pressure sensor 44” as appropriate.

  The right electromagnetic on-off valve 22FR and the left electromagnetic on-off valve 22FL, the pressure increasing valves 40FR to 40RL, the pressure reducing valves 42FR to 42RL, the oil pump 34, the accumulator 50, and the like constitute the hydraulic actuator 81 of the brake control device 10. The hydraulic actuator 81 is controlled by an electronic control unit (hereinafter referred to as “ECU”) 200.

  The ECU 200 functions as a control unit that controls the wheel cylinder pressure in the wheel cylinders 20FR to 20RL. The ECU 200 is a nonvolatile memory such as a CPU that executes various arithmetic processes, a ROM that stores various control programs, a RAM that is used as a work area for data storage and program execution, and a backup RAM that can retain stored contents even when the engine is stopped. An A / D converter for converting an analog signal input from a memory, an input / output interface, various sensors, and the like into a digital signal and taking it in, a timer for timing, and the like are provided.

  The ECU 200 is electrically connected to various actuators including the hydraulic on-off valves 81FR, 22FL, the simulator cut valve 23, the pressure increasing valves 40FR to 40RL, the pressure reducing valves 42FR to 42RL, and the like.

  The ECU 200 is electrically connected to various sensors / switches that output signals for use in control. That is, a signal indicating the wheel cylinder pressure in the wheel cylinders 20FR to 20RL is input to the ECU 200 from the wheel cylinder pressure sensors 44FR to 44RL.

  Further, a signal indicating the pedal stroke of the brake pedal 12 is input from the stroke sensor 46 to the ECU 200, and signals indicating the master cylinder pressure are input from the right master pressure sensor 48FR and the left master pressure sensor 48FL, and from the accumulator pressure sensor 51. A signal indicating the accumulator pressure is input.

  Further, although not shown, ECU 200 receives a signal indicating the wheel speed of each wheel from a wheel speed sensor installed for each wheel, a signal indicating a yaw rate from the yaw rate sensor, and a steering wheel from the steering angle sensor. A signal indicating the steering angle is input.

  In the brake control device 10 configured as described above, when the brake pedal 12 is depressed by the driver, the ECU 200 calculates the target deceleration of the vehicle from the pedal stroke representing the depression amount of the brake pedal 12 and the master cylinder pressure. Then, a target hydraulic pressure that is a target value of the wheel cylinder pressure of each wheel is obtained in accordance with the calculated target deceleration. Then, the ECU 200 controls the pressure increasing valve 40 and the pressure reducing valve 42 so that the wheel cylinder pressure of each wheel becomes the target hydraulic pressure.

  On the other hand, at this time, the electromagnetic on-off valves 22FR and 22FL are closed, and the simulator cut valve 23 is opened. Therefore, the hydraulic oil sent from the master cylinder 14 by the depression of the brake pedal 12 by the driver flows into the stroke simulator 24 through the simulator cut valve 23.

  When the accumulator pressure is less than the lower limit value of the preset control range, the oil pump 34 is driven by the ECU 200 to increase the accumulator pressure. When the accumulator pressure enters the control range, the drive of the oil pump 34 is stopped. Is done.

  FIG. 2 is a view for explaining the configuration of the master cylinder 14 according to the embodiment of the present invention. The master cylinder 14 includes a cylinder housing 60, a first piston 62, and a second piston 64. The master cylinder 14 is a so-called center port type master cylinder.

  The master cylinder 14 has a first piston 62 slidably accommodated in a cylinder housing 60. A piston rod 70 that connects the first piston 62 and the brake pedal 12 is provided at one end of the first piston 62. Further, a second piston 64 is slidably accommodated in the cylinder housing 60. By inserting the two pistons into the cylinder housing 60 in this way, a first master hydraulic pressure chamber 78 is formed between the first piston 62 and the second piston 64, and the second piston 64 and the cylinder housing 60 A second master hydraulic chamber 80 is formed between the bottom and the bottom.

  Further, a first spring 66 is provided between the first piston 62 and the second piston 64 with a predetermined mounting load, and a predetermined mounting is provided between the second piston 64 and the bottom of the cylinder housing 60. A second spring 68 is provided with a load.

  The first output port 14a of the master cylinder 14 communicates with the first master hydraulic chamber 78, and the brake oil pressure control pipe 18 for the right front wheel is connected to the first output port 14a. Further, as described above, the stroke simulator 24 is connected to the first output port 14a via the brake hydraulic pressure control pipe 18. In FIG. 2, the illustration of a simulator cut valve provided between the brake hydraulic control pipe 18 and the stroke simulator 24 is omitted.

  Two annular grooves are formed on the outer peripheral surface of the first piston 62. A first coupling 72 is accommodated in the groove on the one piston rod 70 side, and a second coupling 74 is accommodated in the groove on the other side of the first master hydraulic pressure chamber 78. The first coupling 72 and the second coupling 74 are cross-sectional cup-shaped seal members formed of an elastic material such as rubber. The first coupling 72 and the second coupling 74 are provided so that the inner surface of the cup faces the front of the master cylinder 14. The first large coupling 72 and the second coupling 74 are provided between the first coupling 72 and the second coupling 74. A pressure chamber 73 is formed. The first atmospheric pressure chamber 73 communicates with a reservoir tank (not shown) via a first input port 71 provided on the side surface of the cylinder housing 60. In this specification, the front of the master cylinder 14 is a direction in which the first piston 62 moves when the brake pedal 12 is depressed, and the rear of the master cylinder 14 is the depression of the brake pedal 12. This is the direction in which the first piston 62 moves when it is released and returns to a predetermined initial position.

  Two annular grooves are also formed on the outer peripheral surface of the second piston 64. The third coupling 76 is accommodated in the groove portion on the side of the first master hydraulic pressure chamber 78, and the fourth coupling 77 is accommodated in the groove portion on the side of the second master hydraulic pressure chamber 80. The third coupling 76 is provided such that the inner surface of the cup faces the rear of the master cylinder 14, and the fourth coupling 77 is provided such that the inner surface of the cup faces the front of the master cylinder 14. Yes. A second atmospheric pressure chamber 75 is formed between the third coupling 76 and the fourth coupling 77. The second atmospheric pressure chamber 75 communicates with the reservoir tank via a second input port 79 provided on the side surface of the cylinder housing 60.

  As described above, the stroke simulator 24 creates a pedal stroke corresponding to the depression force of the brake pedal 12 by the driver. In the stroke simulator 24, a piston 162 is accommodated in a cylinder housing 160 having a bottomed cylindrical shape via a coupling 172 so as to be fluid-tightly slidable. In the stroke simulator 24, a liquid chamber 178 and an atmospheric pressure chamber 180 are formed in the cylinder housing 160 by the piston 162. A first stroke simulator spring 166 and a second stroke simulator spring 167 are provided in the atmospheric pressure chamber 180 so as to urge the piston 162 toward the liquid chamber 178. The fluid chamber 178 of the stroke simulator 24 is communicated with the first master fluid pressure chamber 78 of the master cylinder 14 via the input port 182 and the brake hydraulic pressure control pipe 18. The atmospheric pressure chamber 180 of the stroke simulator 24 is communicated with the first atmospheric pressure chamber 73 of the master cylinder 14 or the reservoir tank via an output port (not shown).

  FIG. 3 is a diagram for explaining the master cylinder 14 according to the embodiment of the present invention in more detail. 3, the peripheral part of the first piston 62 of the master cylinder 14 is shown enlarged.

  The first atmospheric pressure chamber 73 communicating with a reservoir tank (not shown) opens to the front surface through a through hole 82 penetrating the intermediate portion of the first piston 62 in the lateral direction and from there through the central portion of the first piston 62. The first master hydraulic chamber 78 communicates with the relief port 84.

  A relief port valve 86 for opening and closing the relief port 84 is provided at the front end of the first piston 62. The relief port valve 86 includes a valve box 88, a poppet valve 90, a valve opening pin 93, a sealing member 94, and a valve spring 95.

  The valve box 88 has a cup shape with a bottom wall positioned on the rear side as a valve seat, and a relief port 84 is opened at the center of the valve seat. An opening that opens to the first master hydraulic chamber 78 is provided at the center of the upper wall of the valve box 88 located on the front side.

  The poppet valve 90 includes an umbrella part 91 and a valve rod 92 that supports the umbrella part 91. The poppet valve 90 is provided by allowing the umbrella portion 91 to face the valve seat via a sealing member 94 that is a rubber O-ring, and the valve rod 92 is loosely inserted into the relief port 84.

  The valve spring 95 is provided in the valve box 88 so as to bias the poppet valve 90 toward the valve seat, that is, rearward. The valve opening pin 93 is loosely inserted into the through hole 82 of the first piston 62 so that the rear end of the valve rod 92 of the poppet valve 90 can be pushed or separated. Further, both ends of the valve opening pin 93 are fixed to the cylinder housing 60.

  In the relief port valve 86, when the first piston 62 is in the initial position, the valve opening pin 93 is located at the front end portion of the through hole 82, and the rear end of the valve rod 92 contacts the valve opening pin 93. It is in contact. The time when the first piston 62 is in the initial position is when the brake pedal 12 is not operated. At this time, the poppet valve 90 is formed such that the umbrella portion 91 is separated from the sealing member 94 by a distance Dpi. This distance Dpi is referred to as port idle. By providing the port idle Dpi as described above, the relief port valve 86 is opened when the first piston 62 is in the initial position, and the first master hydraulic pressure chamber 78 is connected to the relief port 84 and the through hole 82. It communicates with the first atmospheric pressure chamber 73.

  When the brake pedal 12 is depressed and the first piston 62 moves forward for the port idle Dpi or more, the relief port 84 is closed by the umbrella portion 91 of the poppet valve 90, and the first master hydraulic pressure chamber 78 and the first atmospheric pressure are closed. Communication with the chamber 73 is blocked. As a result, a master cylinder pressure is generated in the first master hydraulic pressure chamber 78, the target hydraulic pressure of the wheel cylinder pressure is set as described above, and the pressure increasing valve 40 and the pressure reducing valve 42 of each wheel are set with the target hydraulic pressure as a target value. Be controlled. Further, the piston 162 of the stroke simulator 24 is pushed against the urging force of the first stroke simulator spring 166 and the second stroke simulator spring 167 by the master cylinder pressure, and the first stroke simulator spring 166 and the second stroke simulator spring are driven. By 167, a pedal reaction force is created. In the present embodiment, in the normal control state of the brake control device 10, the left electromagnetic on-off valve 22FL that communicates with the second output port 14b of the second master hydraulic chamber 80 is closed, so The two pistons 64 do not move.

  Thus, in the master cylinder 14, by providing the port idle Dpi, the first master hydraulic pressure chamber 78 and the first atmospheric pressure chamber 73 communicate with each other when the first piston 62 is in the initial position. The oil pressure in the first master hydraulic pressure chamber 78 is always equal to the atmospheric pressure, and it is possible to prevent a situation in which the master cylinder pressure is generated and the brake is dragged when the brake is not operated.

  However, by providing the port idle Dpi, the master cylinder pressure is not generated until the first piston 62 moves forward from the initial position by the port idle Dpi, and therefore the pedal reaction force is not created by the stroke simulator 24. . Then, after the first piston 62 has moved forward by the port idle Dpi or more, the master cylinder pressure is generated and the pedal reaction force is created by the stroke simulator 24. Therefore, the driver feels rattling at the initial stage of the brake operation, The pedal feeling may be uncomfortable.

  Therefore, in the present embodiment, as shown in FIG. 2, a resistance force is generated against the forward movement of the first piston 62 until the first piston 62 moves from the initial position by the port idle Dpi. A resistance force generator 96 is provided. The resistance force generator 96 is formed of a permanent magnet 97 attached to the rear end of the piston rod 70 and a ferromagnetic material such as iron, for example. The dash portion on the vehicle body side faces the permanent magnet 97. 99 and a fixing part 98 attached to 99. By generating an attractive force between the permanent magnet 97 and the fixed portion 98, a resistance force to the forward movement of the first piston 62 is generated. Because of this resistance, the feeling of rattling at the initial stage of braking can be reduced, so that pedal feeling can be improved.

  FIG. 4 is a diagram showing a pedaling force-stroke curve when the resistance force generator 96 is not provided. In this case, since the port idle Dpi is provided as shown by the characteristic curve A, a stroke occurs even when the brake pedal 12 is depressed with a low pedaling force A1 at the initial stage of the brake operation. At this time, since no master cylinder pressure is generated, no pedal reaction force is created by the stroke simulator 24. Thereafter, when the pedaling force is increased and the first piston 62 moves forward by the port idle Dpi when the pedaling force is A2, the master cylinder pressure is generated and the pedal reaction force is suddenly created by the stroke simulator 24. A feeling of looseness is felt in the pedal operation until A2.

  FIG. 5 is a diagram showing the relationship between the attractive force between the permanent magnet 97 and the fixed portion 98 of the resistance force generating portion 96 and the stroke of the first piston 62. As shown by the characteristic curve B in FIG. 5, the attraction force between the permanent magnet 97 and the fixed portion 98 decreases nonlinearly as the stroke of the first piston 62 increases.

  FIG. 6 is a diagram showing a pedaling force-stroke curve of the master cylinder 14 according to the embodiment of the present invention. In the present embodiment, by providing the resistance generating portion 96, the attractive force between the permanent magnet 97 and the fixed portion 98 becomes the resistance force when the first piston 62 starts to move, and the characteristic curve shown in FIG. The portion of A's treading force A1 to A2 and the characteristic curve B shown in FIG. As described above, in the master cylinder 14 according to the present embodiment, since the first piston 62 is prevented from stroking in a state where the pedal reaction force is small at the initial stage of pedal operation, the occurrence of rattling is reduced and the brake feeling is reduced. Can be improved.

  In the above-described embodiment, the permanent magnet 97 of the resistance generating unit 96 may be replaced with an electromagnet. In this case, for example, the ECU 200 controls the current flowing through the electromagnet to provide resistance to the forward movement of the first piston 62 until the first piston 62 moves from the initial position by the port idle Dpi. A current control unit to be generated is provided. Thereby, various controls are possible as compared with the case where a permanent magnet is used.

  For example, the current control unit of the ECU 200 controls the electromagnet so that a backward force is generated in the first piston 62 when the first piston 62 moves forward from the initial position by the port idle Dpi. The electromagnet may be controlled so as to generate a forward force when moving to the initial position. This can be realized by switching the polarity of the current flowing through the electromagnet. In the case of a permanent magnet, when the first piston 62 moves rearward and returns to the initial position, there is a possibility that the brake pedal 12 is pulled by the permanent magnet and the pedal feeling is deteriorated. Thus, by controlling the electromagnet so that a forward force is generated when the first piston 62 returns to the initial position in this way, the feeling of being pulled by the brake pedal 12 is reduced, and the pedal feeling can be improved.

  Further, the current control unit of the ECU 200 may stop energization of the electromagnet when the brake pedal 12 is operated for a predetermined stroke amount or more. In this case, power consumption by the electromagnet can be reduced.

  The current control unit may stop energization of the electromagnet when the brake pedal 12 is operated at a predetermined stroke speed or higher. When the brake pedal 12 is depressed at a high speed, it is considered that a sudden braking force is required. In such a case, the braking force can be quickly increased by assisting the operation force of the brake pedal 12. Can be generated.

  If the resistance generating part 96 generates a resistance against the forward movement of the first piston 62 until the first piston 62 moves from the initial position by the port idle Dpi, this embodiment is implemented. As in this embodiment, the piston rod 70 is not limited to the end portion on the rear side. For example, an attractive force may be generated between the permanent magnet or electromagnet provided on the brake pedal 12 and the vehicle body side fixing portion. However, in this case, there is a possibility that the pedal feeling may be deteriorated due to backlash of the clevis pin that connects the brake pedal 12 and the piston rod 70. Therefore, as shown in FIG. Is preferably provided.

  The present invention has been described above based on the embodiment. It should be understood by those skilled in the art that these embodiments are exemplifications, and that various modifications can be made to the combination of each component and each processing process, and such modifications are also within the scope of the present invention.

  For example, the resistance force generation unit may be configured such that a permanent magnet or an electromagnet is attached to the dash portion on the vehicle body side, and a fixed portion is attached to the rear end portion of the piston rod.

  In the above-described embodiment, the center port type master cylinder 14 has been described as an example. However, a side port type master in which a relief port for communicating the master hydraulic pressure chamber and the atmospheric pressure chamber is provided on the side wall of the cylinder housing 60. Also in the case of a cylinder, by providing the resistance generating portion 96, the feeling of rattling can be reduced and the pedal feeling can be improved.

It is a figure which shows the structure of the brake control apparatus provided with the master cylinder which concerns on embodiment of this invention. It is a figure for demonstrating the structure of the master cylinder which concerns on embodiment of this invention. It is a figure for demonstrating in detail the master cylinder which concerns on embodiment of this invention. It is a figure which shows the treading force-stroke curve at the time of not providing a resistance generation part. It is a figure which shows the relationship between the attractive force between the permanent magnet of a resistive force generation part, and a fixed part, and the stroke of a 1st piston. It is a figure which shows the treading force-stroke curve of the master cylinder which concerns on embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Brake control apparatus, 12 Brake pedal, 14 Master cylinder, 20 Wheel cylinder, 24 Stroke simulator, 26 Reservoir tank, 40 Pressure increasing valve, 42 Pressure reducing valve, 60 Cylinder housing, 62 1st piston, 64 2nd piston, 66 1st Spring, 68 Second spring, 70 Piston rod, 78 First master hydraulic chamber, 80 Second master hydraulic chamber, 82 Through hole, 84 Relief port, 86 Relief port valve, 88 Valve box, 90 poppet valve, 93 Open Valve pin, 96 resistance generating part, 97 permanent magnet, 98 fixing part, 200 ECU.

Claims (6)

A master cylinder that is provided in a brake control device of a vehicle and sends hydraulic oil in response to an operation of a brake pedal by a driver,
A cylinder housing;
A piston slidably accommodated in the cylinder housing and forming a master hydraulic pressure chamber and an atmospheric pressure chamber in the cylinder housing;
A piston rod connecting the piston and the brake pedal;
When the piston is in the initial position, the master hydraulic pressure chamber communicates with the atmospheric pressure chamber, and when the piston moves forward from the initial position by a predetermined port idle or more, the master hydraulic pressure chamber and the atmospheric pressure chamber A communication control means for blocking communication;
By generating a suction force between the piston rod and the vehicle body side, the resisting force against the forward movement of the piston until the piston moves from the initial position by the amount of the port idle. Resistance force generating means for generating
A master cylinder comprising:   2. The master cylinder according to claim 1, wherein the resistance force generating means generates a resistance force against the forward movement of the piston by a magnetic force.   2. The resistance generation means includes: an electromagnet; and a control unit that generates a resistance force with respect to the forward movement of the piston by controlling a current supplied to the electromagnet. The master cylinder according to 2. 4. The master cylinder according to claim 3, wherein the controller energizes the electromagnet so that a backward force is generated in the piston when the piston moves forward from the initial position by the amount of port idle. 5.   5. The master cylinder according to claim 3, wherein the controller stops energization of the electromagnet when the brake pedal is operated for a predetermined stroke amount or more. 6.   6. The control unit according to claim 3, wherein when the brake pedal is operated at a predetermined stroke speed or more, the controller energizes the electromagnet so that a forward force is generated in the piston. The master cylinder described in Crab.

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