JP5761130B2 - Master cylinder device - Google Patents

Description

  The present invention relates to a master cylinder device used in a hydraulic brake system.

In a hydraulic brake system that operates a brake device with pressurized hydraulic fluid, a master cylinder device has been conventionally used to pressurize hydraulic fluid. When the hydraulic brake system is used in a vehicle, the master cylinder device generally uses not only the driver's brake operation force but also a high pressure, including the master cylinder device described in the following patent document. The hydraulic fluid is configured to be pressurized by using an auxiliary force generated by the hydraulic fluid. Therefore, such a master cylinder device is relatively large in the brake device by pressurizing the hydraulic fluid to a relatively high pressure by using the auxiliary force even if the driver himself does not operate the brake operation member strongly. A braking force can be generated.

JP 2008-024098 A

  As described above, the master cylinder device is configured to operate using an auxiliary force in order to improve the operational feeling in the driver's brake operation. In the master cylinder device, there is still a lot of room for improvement in order to improve the operational feeling, including the use of such auxiliary force. Therefore, if any improvement is made, it is possible to improve the practicality of the master cylinder device. This invention is made | formed in view of such a situation, and makes it a subject to improve the practicality of a master cylinder apparatus.

  The master cylinder device of the present invention has a housing, a pressure receiving portion that receives the pressure of hydraulic fluid introduced from a high pressure source, a pressure piston that moves forward by the pressure of the hydraulic fluid, and a brake operation member at the rear end portion. (A) a pressurizing chamber for pressurizing the working fluid to the front side of the pressurizing piston, and (b) filled with the working fluid between the pressurizing piston and the input piston. The inter-piston chamber and (c) the input chamber into which the hydraulic fluid from the high pressure source is introduced are separated from the rear side of the pressure receiving part, and the pressurizing piston and the input piston act as the operation of the inter-piston chamber. The hydraulic fluid moves forward in conjunction with the fluid, and is configured to be able to pressurize the hydraulic fluid in the pressurizing chamber by both the pressure of the hydraulic fluid in the input chamber and the operating force applied to the brake operating member. Piston advance amount is larger than input piston advance amount And it has a differential forward function to grass.

  According to the master cylinder device of the present invention, the pressure piston and the input piston can be moved forward in conjunction with each other, and the advance amount of the pressurization piston can be made larger than the advance amount of the input piston. Therefore, the driver can pressurize the hydraulic fluid by greatly moving the pressure piston forward with a small amount of brake operation. Therefore, a relatively large braking force can be generated by the brake device with a small amount of brake operation. Therefore, the operation of the brake operation member by the driver is reduced and the operational feeling in the brake operation is improved, that is, the practicality of the master cylinder device is improved.

Aspects of the Invention

  In the following, some aspects of the invention that can be claimed in the present application (hereinafter sometimes referred to as “claimable invention”) will be exemplified and described. As with the claims, each aspect is divided into sections, each section is numbered, and is described in a form that cites the numbers of other sections as necessary. This is merely for the purpose of facilitating the understanding of the claimable inventions, and is not intended to limit the combinations of the constituent elements constituting those inventions to those described in the following sections. In other words, the claimable invention should be construed in consideration of the description accompanying each section, the description of the embodiments, etc., and as long as the interpretation is followed, another aspect is added to the form of each section. In addition, an aspect in which some constituent elements are deleted from the aspect of each item can be an aspect of the claimable invention. Some of the aspects of the claimable invention correspond to the invention according to the claims described in the claims. The item (0) is a technically specific matter that is a premise of the claimable invention, and the term after the (0) item indicates a technically specific item that is recognized as being capable of being claimed.

Specifically, in each of the following terms , the combination of the (0) term, the (13) term, and the (1) term is the claim 1, the (0) term, the (13) term, and the (6) term. And the technical feature of (11) added to claim 1 or claim 2 corresponds to claim 3 respectively.

(0) A master cylinder device for supplying pressurized hydraulic fluid to a brake device that is provided on a wheel and operates by the pressure of hydraulic fluid,
A housing;
A pressure piston disposed in the housing and receiving a pressure of hydraulic fluid introduced from the high-pressure source into the master cylinder device, and advanced by the pressure of the hydraulic fluid;
An input piston disposed in the housing behind the pressure piston and connected to a brake operation member at a rear end;
(a) a pressurizing chamber for pressurizing the hydraulic fluid supplied to the brake device on the front side of the pressurizing piston; and (b) the hydraulic fluid is filled between the pressurizing piston and the input piston. A chamber between the pistons, and (c) an input chamber into which hydraulic fluid from a high pressure source is introduced on the rear side of the pressure receiving portion of the pressurizing piston.
The pressurizing piston and the input piston advance in conjunction with each other via the hydraulic fluid in the inter-piston chamber, and depending on either the pressure of the hydraulic fluid in the input chamber or the operating force applied to the brake operation member A master cylinder device configured to be able to pressurize the hydraulic fluid in the pressurizing chamber.

  According to this master cylinder device, when the pressure piston moves forward due to the pressure of the hydraulic fluid in the input chamber acting on the pressure piston, the hydraulic fluid in the inter-piston chamber becomes negative pressure. Will move forward. Further, when the input piston moves forward by the operating force, the operating force is transmitted to the pressurizing piston via the hydraulic fluid in the inter-piston chamber, so that the pressurizing piston moves forward so as to be pushed out. Therefore, in this master cylinder device, the pressurizing piston and the input piston advance in conjunction with each other via the hydraulic fluid in the inter-piston chamber, and the hydraulic fluid in the pressurizing chamber is used as either the operating force or the pressure in the input chamber. Can also be pressurized. That is, the pressure can be applied only by the operating force, the pressure can be increased only by the pressure of the input chamber, and the pressure can be increased by both the operating force and the pressure of the input chamber.

(1) The pressurizing piston has a flange formed around the pressurizing piston,
The input chamber is partitioned on the rear side of the ridge so that the rear end surface of the ridge is used as the pressure receiving portion, and the opposite chamber facing the input chamber is defined on the front side of the ridge with the ridge interposed therebetween. And
An inter-chamber communication path for communicating the counter chamber and the inter-piston chamber;
The master according to (0), wherein the pressure receiving area where the pressure in the inter-piston chamber acts on the pressure piston is greater than the pressure receiving area where the pressure in the counter chamber acts on the flange of the pressure piston. Cylinder device.

  In the master cylinder device of this aspect, the two pressure receiving areas are different sizes. The two pressure receiving areas will be described in detail. First, the pressure receiving area where the pressure of the hydraulic fluid in the inter-piston chamber acts on the pressure piston is the force by which the pressure piston moves forward by the pressure of the hydraulic fluid in the inter-piston chamber. It can be considered as the area that acts. In other words, the forward force applied to the pressure piston by the pressure of the hydraulic fluid in the inter-piston chamber divided by the pressure of the hydraulic fluid in the inter-piston chamber increases the pressure of the hydraulic fluid in the inter-piston chamber. This is the pressure receiving area that acts on the piston. On the other hand, the pressure receiving area where the pressure of the working fluid in the facing chamber acts on the flange of the pressurizing piston can be considered as the area where the force for retreating the pressurizing piston acts by the pressure of the working fluid in the facing chamber. In other words, the backward force applied to the pressurizing piston by the pressure of the working fluid in the opposing chamber is divided by the pressure of the working fluid in the facing chamber. It becomes the pressure receiving area which acts on.

  According to the master cylinder device of this aspect, the pressure in the inter-piston chamber and the pressure in the counter chamber are equalized via the inter-chamber communication path. Further, due to the difference between the two pressure receiving areas, the force for moving the pressure piston forward by the pressure in the inter-piston chamber becomes larger than the force for moving the pressure piston backward by the pressure in the facing chamber. Therefore, when the operating force is transmitted to the hydraulic fluid in the inter-piston chamber through the input piston due to the brake operation, and the pressure in the inter-piston chamber and the opposing chamber rises, it is added by the difference between the forward force and the backward force. The pressure piston moves forward, and the hydraulic fluid in the pressurizing chamber is pressurized.

  When the input piston and the pressurizing piston move forward in conjunction with each other, the working fluid in the facing chamber flows into the inter-piston chamber through the inter-chamber communication path. However, the pressure receiving area where the pressure of the hydraulic fluid in the inter-piston chamber acts on the pressure piston is larger than the pressure receiving area where the pressure of the hydraulic fluid in the counter chamber acts on the flange of the pressure piston. Therefore, according to the master cylinder device of this aspect, the advance amount of the input piston is smaller than the advance amount of the pressurizing piston by the amount of the hydraulic fluid flowing into the inter-piston chamber due to the advance of the pressurizing piston. Therefore, the driver can advance the pressurizing piston relatively large with a relatively small amount of brake operation, and can generate a relatively large braking force with the brake device. Therefore, the operation of the brake operation member by the driver is reduced, and the operational feeling in the brake operation is improved.

  (2) The pressure receiving area where the pressure of the hydraulic fluid in the inter-piston chamber acts on the pressure piston is 1.3 times the pressure receiving area where the pressure of the hydraulic fluid in the counter chamber acts on the flange of the pressure piston. The master cylinder device as set forth above in (1).

  According to the master cylinder device of this aspect, the pressure piston can be moved relatively large even with a relatively small amount of brake operation, and a sufficiently large braking force can be generated by the brake device. Therefore, the operation of the brake operation member by the driver is reduced, and the operational feeling in the brake operation is improved.

  (3) The pressure receiving area where the pressure of the hydraulic fluid in the inter-piston chamber acts on the pressure piston is 4.33 times the pressure receiving area where the pressure of the hydraulic fluid in the counter chamber acts on the flange of the pressure piston. The master cylinder device according to (1) or (2), which is defined as follows.

  According to the master cylinder device of this aspect, the pressurizing piston does not move forward relatively large despite the relatively small amount of brake operation, and an excessive braking force is not generated in the brake device. As a result, an appropriate braking force is generated. Therefore, the operational feeling in the brake operation is improved.

(4) The pressure piston has a bottomed hole that opens toward the rear,
By arranging the input piston so that the front end of the input piston is inserted into the bottomed hole, the inter-piston chamber is partitioned inside the bottomed hole,
The inter-chamber communication passage is formed in the pressurizing piston so that one end opens into the inter-piston chamber through the bottomed hole and the other end opens into the counter chamber in front of the flange. The master cylinder device according to any one of (1) to (3), which includes a passage.

  According to the master cylinder device of this aspect, for example, when the inter-piston chamber and the counter chamber are positioned so as to be adjacent to each other inside the bottomed hole of the pressurizing piston and outside the bottomed hole, The inter-chamber communication path can be configured by providing an internal communication path in the pressure piston that separates the inter-piston chamber and the opposing chamber. Therefore, for example, since it is not necessary to provide an inter-chamber communication path outside the housing, the master cylinder device can be configured relatively simple and compact.

(5) The pressurizing piston has an extending portion extending rearward from the flange,
The inter-piston chamber is partitioned so that the rear end of the extension portion faces the input piston,
The inter-chamber communication path has an internal communication formed in the pressurizing piston such that one end opens to the inter-piston chamber at the extension and the other end opens to the counter chamber in front of the flange. The master cylinder device according to any one of (1) to (3), which includes a passage.

  According to the master cylinder device of this aspect, the inter-chamber communication path can be configured by providing the communication path inside the pressurizing piston. Therefore, for example, since it is not necessary to provide an inter-chamber communication path outside the housing, the master cylinder device can be configured relatively simple and compact.

  (6) The master according to item (0), wherein the pressure receiving area where the pressure in the inter-piston chamber acts on the input piston is larger than the pressure receiving area where the pressure in the inter-piston chamber acts on the pressurizing piston. Cylinder device.

  In the master cylinder device of this aspect, the two pressure receiving areas are different sizes. The two pressure receiving areas will be described in detail. First, the pressure receiving area where the pressure of the hydraulic fluid in the inter-piston chamber acts on the input piston is the force by which the input piston moves backward by the pressure of the hydraulic fluid in the inter-piston chamber. It can be considered an area. In other words, the rearward force applied to the input piston by the pressure of the hydraulic fluid in the inter-piston chamber divided by the pressure of the hydraulic fluid in the inter-piston chamber is the pressure of the hydraulic fluid in the inter-piston chamber applied to the input piston. This is the pressure receiving area that acts. On the other hand, the pressure-receiving area where the pressure of the hydraulic fluid in the piston chamber acts on the pressure piston can be considered as the area where the force that advances the pressure piston acts on the pressure of the hydraulic fluid in the inter-piston chamber. In other words, the forward force applied to the pressure piston by the pressure of the hydraulic fluid in the inter-piston chamber divided by the pressure of the hydraulic fluid in the inter-piston chamber increases the pressure of the hydraulic fluid in the inter-piston chamber. This is the pressure receiving area that acts on the piston.

  In the master cylinder device of this aspect, when the inter-piston chamber is sealed, the pressurizing piston and the input piston move forward in conjunction with the hydraulic fluid in the sealed inter-piston chamber. Moreover, in the advance, the advance amount of the pressure piston having a smaller pressure receiving area can be made larger than the advance amount of the input piston. Therefore, the driver can advance the pressurizing piston relatively large with a relatively small amount of brake operation, and can generate a relatively large braking force with the brake device. Therefore, the operation of the brake operation member by the driver is reduced, and the operational feeling in the brake operation is improved.

  (7) The pressure receiving area of the input piston to which the pressure of the inter-piston chamber acts is 1.3 times or more than the pressure receiving area of the pressurizing piston to which the pressure of the inter-piston chamber acts. The master cylinder device described in 1.

  According to the master cylinder device of this aspect, the pressure piston can be moved relatively large even with a relatively small amount of brake operation, and a sufficiently large braking force can be generated by the brake device.

  (8) The pressure receiving area of the input piston to which the pressure in the inter-piston chamber acts is 4.33 times or less than the pressure receiving area of the pressurizing piston in which the pressure of the inter-piston chamber acts. Or the master cylinder device as described in the item (7).

  According to the master cylinder device of this aspect, the pressurizing piston does not move forward relatively large despite the relatively small amount of brake operation, and an excessive braking force is not generated in the brake device. As a result, an appropriate braking force is generated.

(9) The pressurizing piston has an extending portion extending rearward from the pressure receiving portion,
The master cylinder device according to any one of (6) to (8), wherein the inter-piston chamber is partitioned so that a rear end of the extension portion faces the input piston.

  According to the master cylinder device of this aspect, for example, the inter-piston chamber can be partitioned behind the input chamber.

(10) The housing has a partition portion in which an inside of the housing is partitioned into a front chamber positioned forward and a rear chamber positioned rearward and an opening penetrating the housing is formed.
The pressure piston is disposed so that the pressure receiving portion is located in the front chamber, the input piston is disposed in the rear chamber, and the inter-piston chamber is partitioned using the opening of the partition portion ( The master cylinder device according to any one of items 1) to (9).

  According to the master cylinder device of this aspect, the inter-piston chamber can be easily partitioned using the opening of the partition portion. For example, in the case of the aforementioned master cylinder device in which the pressure piston has a bottomed hole, the front end of the input piston in the rear chamber can be inserted into the bottomed hole of the pressure piston using the opening. Further, in the case of the above-described master cylinder device in which the pressurizing piston has the extending portion, the extending portion can extend into the rear chamber while the pressure receiving portion of the pressurizing piston is located in the front chamber. Therefore, as will be described later in detail, the input chamber and the inter-piston chamber can be partitioned using the partitioning portion.

  (11) The master cylinder device according to any one of (0) to (10), further including a low-pressure source communication mechanism that allows the piston chamber to communicate with a low-pressure source by its own operation.

  According to the master cylinder device of this aspect, when the high pressure source cannot increase the pressure of the hydraulic fluid due to, for example, an electrical failure, the inter-piston chamber can be communicated with the low pressure source. When the inter-piston chamber communicates with the low-pressure source, the input piston advances by flowing out the hydraulic fluid in the inter-piston chamber and comes into contact with the pressurizing piston. The input piston and the pressurizing piston advance integrally. Thus, the hydraulic fluid can be pressurized. Therefore, in this case, the advance amount of the input piston and the advance amount of the pressure piston are the same. As described above, when the input piston and the pressurizing piston move forward through the hydraulic fluid in the inter-piston chamber, the pressurizing piston moves relatively large with respect to the brake operation amount. A relatively large operating force is required to advance the pistons alone. However, according to the master cylinder device of this aspect, for example, when pressurizing the hydraulic fluid with only the operating force, the advancement amount of the pressurizing piston with respect to the brake operation amount can be made relatively small. The liquid can be pressurized. Therefore, according to the master cylinder device of this aspect, even when the high pressure is not introduced from the high pressure source to the input chamber and the hydraulic fluid must be pressurized only by the operating force, the brake by the driver The operation of the operation member is reduced, and the operational feeling in the brake operation is improved.

  (12) The master cylinder device according to (11), wherein the low-pressure source communication mechanism includes a low-pressure communication path that connects the inter-piston chamber to the low-pressure source, and an on-off valve provided in the low-pressure communication path.

  According to the master cylinder device of this aspect, the inter-piston chamber can be communicated with the low pressure source simply by opening the on-off valve. For example, when the on / off valve is an electromagnetic on / off valve that opens in a non-excited state, the piston chamber is communicated with a low pressure source when an electrical failure occurs. . Therefore, the input piston and the pressurizing piston can advance together to pressurize the hydraulic fluid. Therefore, according to the master cylinder device of this aspect, the low-pressure source communication mechanism can have a relatively simple configuration.

  (13) The master cylinder device according to any one of (0) to (12), wherein the master cylinder device has a differential advance function that makes the advance amount of the pressure piston larger than the advance amount of the input piston.

  The operation advance function of this aspect can be realized by the above-described aspect, for example. More specifically, in the case of a master cylinder device in which a counter chamber is defined and an inter-chamber communication passage is provided for communicating the counter chamber and the inter-piston chamber, the pressure of the hydraulic fluid in the inter-piston chamber is applied. The forward movement function can be realized by a mode in which the pressure receiving area acting on the pressure piston is larger than the pressure receiving area where the pressure of the working fluid in the facing chamber acts on the flange of the pressurizing piston. Further, in the master cylinder device, the forward movement function is also realized by an aspect in which the pressure receiving area of the input piston on which the pressure in the inter-piston chamber acts is larger than the pressure receiving area of the pressure piston in which the pressure in the inter-piston chamber acts be able to. Therefore, according to the master cylinder device of this aspect, the driver can generate a relatively large braking force by the brake device with a relatively small amount of brake operation.

  (14) The master cylinder device according to (13), wherein the operation advance function is configured such that a ratio of an advance amount of the pressurizing piston to an advance amount of the input piston is 1.3 or more.

  According to the master cylinder device of this aspect, a sufficiently large braking force can be generated by the brake device even with a relatively small amount of brake operation. Therefore, the operation of the brake operation member by the driver is reduced, and the operational feeling in the brake operation is improved. The operation advance function of this aspect is, for example, the above-described aspect, that is, the pressure receiving area where the pressure of the hydraulic fluid in the inter-piston chamber acts on the pressure piston, This can be realized by an aspect in which the pressure receiving area acting is 1.3 times or more. For example, the pressure receiving area of the input piston to which the pressure in the inter-piston chamber acts can be realized by an aspect in which the pressure receiving area of the pressurizing piston to which the pressure in the inter-piston chamber acts is 1.3 times or more.

  (15) The operation forward function according to (13) or (14), wherein the ratio of the advance amount of the input piston and the advance amount of the pressurizing piston is 3.0 or less. Master cylinder device.

  According to the master cylinder device of this aspect, it is possible to generate an appropriate braking force without causing an excessive braking force to be generated by the brake device, despite a relatively small amount of brake operation. Therefore, the operational feeling in the brake operation is improved. The operation advance function of this mode is, for example, the aforementioned mode, that is, the pressure receiving area where the pressure of the hydraulic fluid in the inter-piston chamber acts on the pressure piston, and the pressure of the hydraulic fluid in the opposite chamber acts on the flange of the pressure piston. This can be realized by a mode in which the pressure receiving area is 4.33 times or less. For example, the pressure receiving area of the input piston on which the pressure in the inter-piston chamber acts can be realized by an aspect in which the pressure receiving area of the pressure piston on which the pressure in the inter-piston chamber acts is 4.33 times or less.

1 is a schematic diagram showing a drive system and a braking system for a hybrid vehicle equipped with a vehicle brake system equipped with a master cylinder device according to a first embodiment of the claimable invention. It is a figure which shows the hydraulic brake system provided with the master cylinder apparatus of 1st Example. It is a figure which shows the pressure regulator of the hydraulic brake system shown in FIG. FIG. 4 is a diagram showing the relationship between the pressure in the pilot chamber and the pressure of the hydraulic fluid adjusted according to the pressure in the pilot chamber in the pressure regulator shown in FIG. 3. It is a figure which shows the hydraulic brake system provided with the master cylinder apparatus of 2nd Example. It is a figure which shows the hydraulic brake system provided with the master cylinder apparatus of 3rd Example. It is a figure which shows the hydraulic brake system provided with the master cylinder apparatus of 4th Example.

  Hereinafter, embodiments of the claimable invention will be described in detail with reference to the drawings. The claimable invention is not limited to the following examples and modifications, and can be implemented in various modes with various changes and improvements based on the knowledge of those skilled in the art.

≪Vehicle configuration≫
FIG. 1 schematically shows a drive system and a braking system for a hybrid vehicle. In the vehicle, an engine 10 and an electric motor 12 are mounted as power sources, and a generator 14 that generates electric power by the output of the engine 10 is also mounted. The engine 10, electric motor 12, and generator 14 are connected to each other by a power split mechanism 16. By controlling the power split mechanism 16, the output of the engine 10 can be divided into an output for operating the generator 14 and an output for rotating one of the four wheels 18 as a driving wheel. The output of the electric motor 12 can be transmitted to the drive wheels. That is, the power split mechanism 16 functions as a transmission related to the driving force transmitted to the drive wheels via the speed reducer 20 and the drive shaft 22. In addition, some components such as “wheel 18” correspond to the left front wheel, the right front wheel, the left rear wheel, and the right rear wheel, respectively, when indicating that they correspond to any of the four wheels. The subscripts “FL”, “FR”, “RL”, and “RR” are used. If this notation is followed, the drive wheels in this vehicle are the wheel 18RL and the wheel 18RR.

  The electric motor 12 is an AC synchronous motor and is driven by AC power. The vehicle is provided with an inverter 24, and the inverter 24 can convert electric power from direct current to alternating current or from alternating current to direct current. Therefore, by controlling the inverter 24, the AC power output from the generator 14 is converted to DC power for storing in the battery 26, or the DC power stored in the battery 26 is converted to the electric motor. 12 can be converted into alternating current power for driving 12. Like the electric motor 12, the generator 14 has a configuration as an AC synchronous motor. That is, in the vehicle of the present embodiment, it can be considered that two AC synchronous motors are mounted, and one is used mainly as an electric motor 12 for outputting driving force, and the other is a generator. 14 is mainly used to generate electric power from the output of the engine 10.

  Further, the electric motor 12 can also generate power (regenerative power generation) by using the rotation of the wheels 18RL and 18RR accompanying the traveling of the vehicle. At this time, in the electric motor 12 connected to the wheels 18RL and 18RR, electric power is generated, and resistance for stopping the rotation of the electric motor 12 is generated. Therefore, the resistance can be used as a braking force for braking the vehicle. That is, the electric motor 12 is used as a regenerative braking system that generates a regenerative braking force that brakes the vehicle while generating electric power. Therefore, the vehicle is braked by controlling the regenerative brake system together with the engine brake and the hydraulic brake system described later. On the other hand, the generator 14 generates power mainly by the output of the engine 10, but also functions as an electric motor when power is supplied from the battery 26 via the inverter 24.

  In the present vehicle, the above-described brake control and various types of control relating to other vehicles are performed by a plurality of electronic control units (ECUs). Of the plurality of ECUs, the main ECU 30 has a function of supervising these controls. For example, the hybrid vehicle can travel by driving the engine 10 and the electric motor 12. The driving of the engine 10 and the driving of the electric motor 12 are comprehensively controlled by the main ECU 30. . A battery ECU 36 that controls the battery 26 is also connected to the main ECU 30. The battery ECU 36 monitors the state of charge of the battery 26, and outputs a charge request command to the main ECU 30 when the amount of charge is insufficient. The main ECU 30 that has received the charge request command outputs a power generation command from the generator 14 to the motor ECU 34 in order to charge the battery 26.

  The main ECU 30 is also connected to a brake ECU 38 that controls the brake. The vehicle is provided with a brake operation member (hereinafter sometimes simply referred to as “operation member”) operated by the driver, and the brake ECU 38 is a brake that is a driver's force applied to the operation member. The required braking force is determined based on the operating force (hereinafter sometimes simply referred to as “operating force”). The brake ECU 38, which will be described in detail later, includes the braking force generated by the regenerative braking system (hereinafter sometimes simply referred to as “regenerative braking force”) and the liquid mounted on the vehicle. The braking force generated by the pressure brake system 40 (hereinafter, sometimes simply referred to as “hydraulic braking force”) is determined. The regenerative braking force is output from the brake ECU 38 to the main ECU 30, and the main ECU 30 outputs this regenerative braking force to the motor ECU 34. The motor ECU 34 controls the electric motor 12 based on the regenerative braking force. The hydraulic brake system 40 is controlled by the brake ECU 38 based on the hydraulic braking force. Thus, in this vehicle, the vehicle brake system for braking the vehicle is configured including the regenerative brake system using the electric motor 12 and the hydraulic brake system 40.

≪Configuration of hydraulic brake system≫
The hydraulic brake system 40 mounted on the hybrid vehicle configured as described above will be described in detail with reference to FIG. In the following description, “front” represents the left side in FIG. 2, and “rear” represents the right side in FIG. In addition, “front side”, “front end”, “forward”, “rear side”, “rear end”, “reverse”, and the like are also represented in the same manner. In the following description, the character [] is a symbol used when a sensor or the like is shown in the drawings.

  FIG. 2 schematically shows a hydraulic brake system 40 provided in the vehicle. The hydraulic brake system 40 has a master cylinder device 50 for pressurizing hydraulic fluid. The driver of the vehicle can operate the master cylinder device 50 by operating the operating device 52 connected to the master cylinder device 50, and the master cylinder device 50 pressurizes the hydraulic fluid by its own operation. The pressurized hydraulic fluid is supplied to a brake device 56 provided on each wheel via an antilock device 54 connected to the master cylinder device 50. The brake device 56 generates a force for stopping the rotation of the wheel 18, that is, a hydraulic braking force, depending on the pressure of the pressurized hydraulic fluid (hereinafter sometimes referred to as “master pressure”). .

  The hydraulic brake system 40 has a high pressure source device 58 for increasing the pressure of the hydraulic fluid as a high pressure source. The high-pressure source device 58 is connected to the master cylinder device 50 via the pressure regulating device 60. The pressure adjusting device 60 is a device that controls the pressure of the hydraulic fluid that has been increased in pressure by the high-pressure source device 58 (hereinafter sometimes referred to as “high-pressure source pressure”) to a pressure that is lower than that pressure. The pressure of the hydraulic fluid (hereinafter also referred to as “adjusted pressure”) input to is increased and decreased. That is, the adjustment pressure is a pressure obtained by regulating the hydraulic fluid having a high source pressure, and can also be referred to as a control high pressure source pressure. The master cylinder device 50 is configured to be operable by increasing or decreasing the adjustment pressure. The hydraulic brake system 40 has a reservoir 62 that stores hydraulic fluid under atmospheric pressure as a low pressure source. The reservoir 62 is connected to each of the master cylinder device 50, the pressure adjusting device 60, and the high pressure source device 58.

  The operation device 52 includes a brake pedal 70 as a brake operation member and an operation rod 72 connected to the brake pedal 70. The brake pedal 70 is rotatably held by the vehicle body at the upper end portion. The operation rod 72 is connected to the brake pedal 70 at the rear end, and is connected to the master cylinder device 50 at the front end. The operation device 52 includes an operation amount sensor [SP] 74 for detecting the operation amount of the brake pedal 70 and an operation force sensor [FP] 76 for detecting the operation force. The operation amount sensor 74 and the operation force sensor 76 are connected to the brake ECU 38.

  The brake device 56 is connected to the master cylinder device 50 via liquid passages 80 and 82. The fluid passages 80 and 82 are fluid passages for supplying hydraulic fluid pressurized to the master pressure by the master cylinder device 50 to the brake device 56. Incidentally, the fluid passage 80 is connected to the brake devices 56RL and 56RR on the rear wheel side, and the fluid passage 82 is connected to the brake devices 56FL and 56FR on the front wheel side. A master pressure sensor [Po] 84 is provided in the fluid passage 80, and the master pressure sensor 84 is connected to the brake ECU 38. Although not described in detail, each brake device 56 is a general disc brake device, and includes a brake caliper 86 supported by a carrier that supports wheels, and a brake disc 88 that rotates together with each wheel 18. It consists of The brake caliper 86 has a brake cylinder that operates depending on the master pressure, and a brake pad that is pressed against the brake disc 88 by the operation. That is, each brake device 56 is configured such that the brake cylinder presses the brake pad against the brake disc 88 and the rotation of the wheel is stopped by the frictional force generated by the pressing depending on the master pressure.

  The anti-lock device 54 is a general device, and simply has four pairs of on-off valves corresponding to each wheel. One of the pair of on-off valves is a boosting on-off valve, and when the wheel is not locked, the valve is open, and the other is a decompression on-off valve. When not locked, the valve is closed. When the wheel is locked, the pressure increasing / closing valve shuts off the flow of hydraulic fluid from the master cylinder device 50 to the brake device 56, and the pressure reducing on / off valve allows the hydraulic fluid to flow from the brake device 56 to the reservoir. It is configured to allow and unlock the wheels.

  The high-pressure source device 58 includes a hydraulic pump 90 that sucks the hydraulic fluid from the reservoir 62 and raises the hydraulic pressure of the hydraulic fluid, and an accumulator 92 that stores the pressurized hydraulic fluid. Incidentally, the hydraulic pump 90 is driven by an electric motor 94. Further, the high-pressure source device 58 includes a high-pressure source pressure sensor [Ph] 96 for detecting the pressure of the hydraulic fluid that is set to a high pressure. The brake ECU 38 monitors the detected value of the high-pressure source pressure sensor 96, and the hydraulic pump 90 is controlled and driven based on the detected value. By this control drive, the high-pressure source device 58 always supplies hydraulic fluid having a set pressure to the pressure adjusting device 60.

  The pressure regulating device 60 includes a pressure regulator 100 connected to the high pressure source device 58 and the reservoir 62, a pressure increasing linear valve 102 connected to the high pressure source device 58, and a pressure reducing linear valve 104 connected to the reservoir 62. Yes. As will be described in detail later, the pressure regulator 100 adjusts the pressure of the hydraulic fluid from the high pressure source device 58 based on the pilot pressure introduced to itself, and supplies the hydraulic fluid to the master cylinder device 50. it can. Further, the pressure-increasing linear valve 102 and the pressure-decreasing linear valve 104 are each connected to the brake ECU 38 and operate based on a command from the brake ECU 38. The pressure-increasing linear valve 102 can operate so that the pressure of the hydraulic fluid supplied to the master cylinder device 50 increases, and the pressure-decreasing linear valve 104 has a pressure of the hydraulic fluid supplied to the master cylinder device 50. Can operate to decrease. Further, the pressure increasing linear valve 102 is configured to be closed in a non-excited state, and the pressure reducing linear valve 104 is configured to be opened in a non-excited state. Further, the pressure regulating device 60 is a normally open valve, and includes a first pilot pressure introducing valve 106 and a second pilot pressure introducing valve 108 for introducing and shutting off a pilot pressure working fluid introduced into the pressure regulator 100. Have. The pilot pressure introduction valve 106 and the second pilot pressure introduction valve 108 are connected to the brake ECU 38 and operate based on a command from the brake ECU 38.

<Configuration of master cylinder device>
The master cylinder device 50 includes a housing 150 that is a housing of the master cylinder device 50, a first pressure piston 152 and a second pressure piston 154 that pressurize the hydraulic fluid supplied to the brake device 56, and a driver's operation. An input piston 156 that is input through the operation device 112 is included. FIG. 2 shows a state where the master cylinder device 50 is not operating, that is, a state where the brake operation is not performed.

  The housing 150 is mainly composed of two members, specifically, a first housing member 158 and a second housing member 160. The first housing member 158 has a generally cylindrical shape with the front end closed, and is fixed to the vehicle body at a flange 162 formed on the outer periphery at the rear. The first housing member 158 includes two parts having different inner diameters, specifically, a front small diameter part 164 having a small inner diameter located on the front side, and a rear large diameter part 166 having a large inner diameter located on the rear side. It is divided into. The second housing member 160 is roughly cylindrical, and is divided into a front large-diameter portion 168 having a large inner diameter located on the front side and a rear small-diameter portion 170 having a small inner diameter located on the rear side. ing. The second housing member 160 is fitted into the first housing member 158 such that the front end of the second housing member 160 is in contact with the step surface between the front small diameter portion 164 and the rear large diameter portion 166 of the first housing member 158.

  The second pressurizing piston 154 has a bottomed cylindrical shape with a closed rear end portion, and is slidably fitted to the front small diameter portion 164 of the first housing member 158 via a seal. The first pressurizing piston 152 is disposed behind the second pressurizing piston 154 and has a cylindrical main body portion 172. On the outer periphery of the rear end portion of the main body portion 172, 174 is provided. The interior of the main body 172 is divided into two parts by a partition wall 176 provided at an intermediate position in the front-rear direction. That is, the first pressurizing piston 152 has a shape having two bottomed holes that are opened at the front end and the rear end by the partition wall portion 176. Incidentally, the first pressurizing piston 152 is restricted from retreating by the flange 174 coming into contact with the step surface between the front large-diameter portion 168 and the rear small-diameter portion 170 of the second housing member 160.

  Between the 1st pressurization piston 152 and the 2nd pressurization piston 154, the 1st pressurization chamber R1 for pressurizing the hydraulic fluid supplied to brake devices 56RL and RR provided in two rear wheels is provided. A second pressurizing chamber R2 for pressurizing the hydraulic fluid supplied to the brake devices 56FL and FR provided on the two front wheels is defined in front of the second pressurizing piston 154. Is formed. In the first pressure piston 152, a headed pin 178 is screwed up at the bottom of a bottomed hole that opens forward, and in the second pressure piston 154, a pin holding cylinder 180 is provided at the rear end surface. Is fixed. Due to the headed pin 178 and the pin holding cylinder 180, the separation distance between the first pressure piston 152 and the second pressure piston 154 is limited within a set range. Further, in the first pressurizing chamber R1 and the second pressurizing chamber R2, compression coil springs (hereinafter also referred to as “return springs”) 182 and 184 are disposed, respectively. The first pressurizing piston 152 and the second pressurizing piston 154 are biased toward the rear while being biased in the direction in which they are separated from each other.

  The input piston 156 is roughly cylindrical. The front side of the input piston 156 is fitted into the first pressure piston 152 so as to be in sliding contact with the inner peripheral surface of the bottomed hole opened at the rear end of the first pressure piston 152, and the rear side of the input piston 156 is The second housing member 160 is fitted so as to be in sliding contact with the inner peripheral surface of the rear small diameter portion 170 of the second housing member 160. An operation rod 72 is connected to the rear end of the input piston 156 in order to transmit the operation force of the brake pedal 70 to the input piston 156 and to advance and retract the input piston 156 according to the operation amount of the brake pedal 70. ing. Incidentally, the input piston 156 has its rear end portion locked to the rear end portion of the second housing member 160 so that the backward movement of the input piston 156 is restricted. The operation rod 72 is provided with a disk-shaped spring seat 186, and a compression coil spring 188 is disposed between the spring seat 186 and the second housing member 160. The operation coil 72 is urged rearward by the compression coil spring 188. Note that a boot 190 is passed between the spring seat 186 and the housing 150 to prevent dust at the rear portion of the master cylinder device 50.

  In the master cylinder device 50 configured as described above, an annular liquid chamber (hereinafter referred to as an “input chamber”) to which hydraulic fluid is supplied from the pressure regulating device 60 is provided on the rear side of the flange 174 of the first pressure piston 152. R3 is partitioned. That is, the rear end surface of the flange 174 is a pressure receiving portion to which the pressure of the input chamber R3 acts in the first pressurizing piston 152. Incidentally, the input chamber R3 is shown in a substantially collapsed state in FIG. Further, an annular liquid chamber (hereinafter referred to as the input chamber R3) is sandwiched between the inner peripheral surface of the second housing member 160 and the outer peripheral surface of the first pressure piston 152 on the front side of the flange 174. R4 is defined as a compartment. Further, a gap is provided between the bottomed hole of the first pressure piston 152 and the front end surface of the input piston 156. That is, a liquid chamber (hereinafter also referred to as “inter-piston chamber”) R5 in which the first pressurizing piston 352 and the input piston 156 face each other across the gap is partitioned.

In the first pressurizing piston 152, the pressure receiving area S ₁ in which the pressure of the hydraulic fluid inter-piston chamber R5 is applied to the first pressurizing piston 152 is, the pressure of the hydraulic fluid in the opposing chamber R4 is first pressure The pressure receiving area S ₂ acting on the flange 174 of the piston 152 is made larger. The pressure receiving area S ₁ where the pressure of the hydraulic fluid in the inter-piston chamber R5 acts on the first pressurizing piston 152 is a force that advances the first pressurizing piston 152 by the pressure of the hydraulic fluid in the inter-piston chamber R5. It can be considered an area. In other words, the forward force applied to the first pressurizing piston 152 by the pressure of the hydraulic fluid in the inter-piston chamber R5 divided by the pressure of the hydraulic fluid in the inter-piston chamber R5 is the operation of the inter-piston chamber R5. The pressure of the liquid is a pressure receiving area that acts on the first pressure piston 152. On the other hand, the pressure receiving area S _{2 at} which the pressure of the hydraulic fluid in the counter chamber R4 acts on the flange 174 of the first pressurization piston 152 is the force that causes the first pressurization piston 152 to move backward by the pressure of the hydraulic fluid in the counter chamber R4. Can be thought of as the area where the action acts. In other words, the pressure of the hydraulic fluid in the counter chamber R4 is obtained by dividing the backward force applied to the first pressurizing piston 152 by the pressure of the hydraulic fluid in the counter chamber R4 by the pressure of the hydraulic fluid in the counter chamber R4. Is a pressure receiving area acting on the flange 174 of the first pressure piston 152.

In the first pressurizing piston 152, the pressure receiving area S _{1 on which} the pressure in the inter-piston chamber R5 acts is 1.5 times or more and 4.33 times or less than the pressure receiving area S _{2 on which} the pressure in the counter chamber R4 acts. That is, it is set so that the relationship of 1.5 ≦ S ₁ / S ₂ ≦ 4.33 is established. Further, the pressure receiving area where the pressure of the hydraulic fluid in the inter-piston chamber R5 acts on the input piston 156, that is, the area where the force for retreating the input piston 156 by the pressure of the hydraulic fluid in the inter-piston chamber R5 acts is the inter-piston chamber. pressure R5 is almost the same size as the pressure receiving area S ₁ that acts on the first pressurizing piston 152.

  The first pressurizing chamber R1 communicates with a liquid passage 80 connected to the antilock device 54 via a communication hole 200 provided in the first housing member 158, and communicates with the first pressurizing piston 152. It is possible to communicate with the reservoir 62 through a communication hole 204 provided in the hole 202 and the first housing member 158. On the other hand, the second pressurizing chamber R <b> 2 communicates with the liquid passage 82 connected to the antilock device 54 through the communication hole 206 provided in the first housing member 158, and is provided in the second pressurizing piston 154. The reservoir 62 can be communicated through the communication hole 208 and the communication hole 210 provided in the first housing member 158.

  The first pressurizing piston 152 has an outer diameter that is somewhat smaller than the inner diameter of the front small-diameter portion 164 of the first housing member 158, and a liquid passage 212 having a certain flow passage area is formed between them. . In addition, a communication hole 214 having one end opened in the inter-piston chamber R5 and the other end opened in the liquid passage 212 is formed in the side wall of the bottomed hole that opens to the rear of the first pressure piston 152. One housing member 158 is provided with a communication hole 216 having one end opened to the liquid passage 212 and the other end opened to the outside. Therefore, the inter-piston chamber R5 communicates with the outside through the communication hole 214, the liquid passage 212, and the communication hole 216.

  At the front end of the front large-diameter portion 168 of the second housing member 160, a communication hole 218 having one end opened to the facing chamber R4 and the other end opened on the outer peripheral surface of the second housing member 160 is provided. The first housing member 158 is provided with a communication hole 220 having one end facing the other end of the communication hole 218 and opening, and the other end serving as a connection port opening to the outside. Therefore, the facing chamber R4 communicates with the outside through the communication holes 218 and 220.

  Further, the portion of the second housing member 160 located on the rear side of the front large-diameter portion 168 has an outer diameter that is somewhat smaller than the inner diameter of the rear large-diameter portion 166 of the first housing member 158, and the housing members 158, A liquid passage 222 having a certain flow path area is formed between 160. The liquid passage 222 communicates with the outside through a communication hole 224 whose opening serves as a connection port. The second housing member 160 is provided with a communication hole 226 having one end opened to the liquid passage 222 and the other end opened to the input chamber R3. Accordingly, the input chamber R3 communicates with the outside through the communication hole 226, the liquid passage 222, and the communication hole 224.

  An inter-chamber communication path 228 is provided outside the housing 150, with one end connected to the connection port of the communication hole 216 and the other end connected to the connection port of the communication hole 220. Therefore, the inter-piston chamber R5 and the counter chamber R4 can communicate with each other via the inter-chamber communication passage 228.

  Further, the inter-chamber communication path 228 also branches between the communication hole of the communication hole 220 and the communication on / off valve 230, and the low-pressure communication path 232 that is the branched communication path is connected to the reservoir 62. An electromagnetic low-pressure communication valve 234 is provided in the middle of the low-pressure communication path. Therefore, the low-pressure communication path 232 and the low-pressure communication valve 234 serve as a low-pressure source communication mechanism that connects the inter-piston chamber R5 to the reservoir 62 via the counter chamber R4. Note that the low-pressure communication valve 234 is a normally open valve that is opened in a non-excited state. The inter-chamber communication path 228 is branched between the communication hole 216 and the communication opening / closing valve 230, and the branched first pilot pressure supply path 236 is connected to the pressure regulator 100 of the pressure regulating device 60. Yes. The first pilot pressure introduction valve 106 described above is provided in the middle of the first pilot pressure supply path 236. The liquid passage 80 is branched between the communication hole 200 and the antilock device 54, and the branched second pilot pressure supply path 238 is also connected to the pressure regulator 100 of the pressure regulating device 60. The above-described second pilot pressure introduction valve 108 is provided in the middle of the second pilot pressure supply path 238.

One end of the connection port of the communication hole 224 is connected to the pressure regulating device 60, and the other end of the regulated pressure supply path 240 to which the regulated hydraulic fluid is supplied is connected. Therefore, the adjustment chamber 60 can be supplied with the hydraulic fluid with the regulated pressure regulated by the pressure regulating device 60. Incidentally, in the middle of the adjustment pressure supply passage 240 is a pressure of the hydraulic fluid in the input chamber R3 adjusting pressure P _A is adjusted pressure sensor [Pa] 242 for detecting are provided to, the adjustment pressure sensor 242 The brake ECU 38 is connected.

≪Structure of pressure regulator≫
Below, the structure of the pressure regulator 100 is demonstrated in detail, referring FIG. In the following description, “front” represents the left side in FIG. 3, and “rear” represents the right side in FIG.

  The pressure regulator 100 includes a cylindrical housing 250 closed at both ends, a movable rod 252 disposed in the housing 250, a reaction force plunger 256 disposed in front of the movable rod 252, A cylindrical balance piston 258 externally fitted to the force plunger 256 and a reaction disk 260 arranged in front of the reaction force plunger 256 and the balance piston 258 are configured.

  The housing 250 is divided into three parts having different inner diameters, with the rear side being one end side that is one end side and the front side being the other end side that is the other end side. Specifically, the front part 262 having a large inner diameter located at the front, the rear part 264 having a smaller inner diameter than the front part 262 located at the rear, and located between the front part 262 and the rear part 264, Are divided into a front part 262 and an intermediate part 266 smaller than the rear part 264. The movable rod 252 has a proximal end portion 268 located at the rear and a spool portion 270 extending forward from the proximal end portion 268, and the proximal end portion 268 is an inner peripheral surface of the rear portion 264 of the housing 250. Further, the spool portion 270 is disposed so as to be in sliding contact with the inner peripheral surface of the intermediate portion 266. A pressing piston 271 having the same diameter as that of the base end portion 268 is disposed behind the movable rod 252. A balance piston 258 is disposed on the front portion 262 of the housing 250 so as to be in sliding contact with the inner peripheral surface of the front portion 262. A reaction disk 260 is also disposed in the front portion 262. The reaction disk 260 is made of rubber having a disk shape, and has an outer diameter that fits the front portion 262 exactly. Further, the balance piston 258 and the reaction disk 260 are disposed in the front portion 262 so that no gap is generated in the front-rear direction between the housing 250, the balance piston 258, and the reaction disk 260. Therefore, the cylindrical balance piston 258 is always in contact with the outer peripheral portion of the disc-shaped reaction disk 260, that is, the portion excluding the central portion. The reaction force plunger 256 is disposed so as to be in sliding contact with the inner peripheral surface of the balance piston 258 so that the front end surface thereof faces the central portion of the reaction disk 260. A protrusion 272 that protrudes forward is provided at the front end of the reaction force plunger 256. Therefore, the front end portion of the reaction force plunger 256 has a shape in which a step surface facing the front side is formed.

  In the pressure regulator 100, a compression coil spring 274 is disposed between the step surface formed on the inner peripheral surface of the balance piston 258 and the step surface formed on the outer peripheral surface of the reaction force plunger 256. . Therefore, the reaction force plunger 256 and the movable rod 252 are urged toward the rear side by the elastic force generated by the compression coil spring 274.

  In the pressure regulator 100 configured as described above, a pilot pressure hydraulic fluid for operating the pressure regulator 100 is received between the rear end face of the movable rod 252 and the pressing piston 271 in detail. A liquid chamber (hereinafter sometimes referred to as a “first pilot chamber”) P1 is partitioned. In addition, a liquid chamber (hereinafter sometimes referred to as “second pilot chamber”) P <b> 2 for receiving a pilot pressure hydraulic fluid for operating the pressure regulator 100 is also defined between the pressing piston 271 and the housing 250. ing

  The housing 250 has a plurality of communication holes. Specifically, the intermediate portion 266 is formed with a communication hole 282 having one end opened to the inner peripheral surface and the other end opened to the outside as a connection port. The intermediate portion 266 has a communication hole 284 having one end opened on the inner peripheral surface and the other end opened on the rear end surface of the front portion 262. Further, the intermediate portion 266 is formed with a communication hole 286 having one end opened to the inner peripheral surface and the other end opened to the outside as a connection port. The front portion 262 also has a communication hole 288 having one end opened to the inner peripheral surface and the other end opened to the outside as a connection port. The communication hole 288 communicates with the communication hole 284 through a liquid passage 290 formed between the inner peripheral surface of the front portion 262 and the outer peripheral surface of the balance piston 258. The housing 250 further has a communication hole 292 having one end opened to the first pilot chamber P1 and the other end opened to the outside as a connection port, one end opened to the second pilot chamber P2, and the other end externally serving as a connection port. A communication hole 294 is formed in the opening. In addition, the movable rod 252 is provided with a circulation portion 296 that allows the circulation of the hydraulic fluid by reducing the outer diameter on the outer peripheral portion of the spool portion 270. The length in the front-rear direction of the flow portion 296 is slightly smaller than the distance between the opening of the communication hole 282 and the opening of the communication hole 286. That is, the circulation part 296 is formed so that the communication hole 282 and the communication hole 286 do not communicate with each other by the circulation part 296.

  A low pressure communication path 232 communicating with the reservoir 62 is connected to the connection port of the communication hole 282, and a high pressure communication path 302 communicating with the high pressure source device 58 is connected to the connection port of the communication hole 286. Further, an adjustment pressure supply path 240 is connected to the connection port of the communication hole 288, and the hydraulic fluid adjusted by the pressure regulator 100 passes through the adjustment pressure supply path 240 as will be described in detail later. It is supplied to the input chamber R3 of the master cylinder device 50. A first pilot pressure supply path 236 communicating with the inter-piston chamber R5 is connected to the connection port of the communication hole 292. Therefore, the hydraulic fluid having the pressure in the facing chamber R4 and the inter-piston chamber R5 can be supplied to the first pilot chamber P1. The connection port of the communication hole 294 is connected to a second pilot pressure supply path 238 that communicates with the first pressurizing chamber R1. Therefore, the hydraulic fluid having the pressure in the first pressurizing chamber R1 can be supplied to the second pilot chamber P2.

In the pressure regulator 100, in the state shown in FIG. 3, the distance between the front end of the flow portion 296 and the opening of the communication hole 286 is D ₁ , the front end surface of the protruding portion 272 of the reaction force plunger 256 and the rear end surface of the reaction disk 260. The distance to is D ₂ . The distance D ₂ is made somewhat larger than the distance D ₁ .

≪Operation of pressure regulator≫
Hereinafter, the operation of the pressure regulator 100 configured as described above will be described in detail. Since the spring constant of the compression coil spring 274 is relatively small, in the following description of the operation of the pressure regulator 100, the influence of the force generated by the compression coil spring 274 is ignored. When the pressure in the first pilot chamber P1 or the second pilot chamber P2, that is, the pilot pressure is atmospheric pressure, the movable rod 252 is positioned at the moving end on the rear side by the elastic force of the compression coil spring 274. The communication hole 282 and the communication hole 284 communicate with each other via the flow part 296 of the movable rod 252. That is, the communication hole 284 communicates with the reservoir 62, and the pressure of the communication hole 284 becomes atmospheric pressure. When the pilot pressure rises from this state, the movable rod 252 moves forward by receiving the pilot pressure, and the movable rod 252 pushes the reaction force plunger 256 forward. When the rear end of the circulation portion 296 moves forward from the opening of the communication hole 282 by the advance, the communication between the communication hole 284 and the reservoir 62 is blocked. Further, when the movable rod 252 advances slightly from the interruption, the front end of the flow part 296 reaches the opening of the communication hole 286, and the communication hole 286 and the communication hole 284 communicate with each other via the flow part 296. That is, the communication hole 284 communicates with the high pressure source device 58, and the pressure of the communication hole 284 increases.

  When the pressure in the communication hole 284 increases, the pressure in the liquid passage 290 communicating with the communication hole 284 increases, so that the balance piston 258 receives the pressure at the rear end face and is pressed forward. Therefore, the balance piston 258 moves forward while crushing the outer periphery of the reaction disc 260, and the reaction disc 260 is deformed so that the central portion where the balance piston 258 does not contact protrudes rearward. Therefore, when this deformation progresses, the central portion of the variaction disc 260 comes into contact with the protruding portion 272 of the reaction force plunger 256 and presses the movable rod 252 to retreat. As a result, the communication between the communication hole 286 and the communication hole 284 is blocked, and the pressure increase in the liquid passage 290 is stopped. Further, when the pilot pressure decreases from that state, the movable rod 252 moves backward, the communication hole 284 communicates with the reservoir 62, and the pressures of the communication hole 284 and the liquid passage 290 decrease. Therefore, the force with which the reaction disk 260 presses the reaction force plunger 256 and the movable rod 252 rearward is reduced, and the movable rod 252 is advanced to stop the pressure drop in the communication hole 284 and the liquid passage 290.

In such operation to pressure regulator 100, to changes in the pilot pressure P _P, adjusting pressure P _A changes as shown in the graph of FIG. When the pilot pressure P _P reaches an increased height, in the pressure regulator 100, the movable rod 252 moves forward by overcoming friction or the like due to sliding with the housing 250, and the adjustment pressure increases as described above. In addition, the reaction disk 260 must be deformed so that the central portion fills the gap between the distances D _{2 and} D ₁ after the adjustment pressure increases and before the increase in the adjustment pressure stops. Therefore, as shown in the first section of FIG. 4, at a certain pilot pressure P _P , the adjustment pressure P _A rises at a stretch by the initial pressure increase amount ΔP _AJ . Therefore, adjustment pressure increase gradient, i.e., the gradient of the increase in the adjusted pressure P _A for increasing the pilot pressure P _P, becomes very large.

When the pilot pressure P _P further increases, as shown in the second section of FIG. 4, the pressure regulator 100 is movable by the force that urges the movable rod 252 forward by the pilot pressure and the pressure of the liquid passage 290. The adjustment pressure P _A increases in proportion to the increase in the pilot pressure P _P so that the force urging the rod 252 toward the rear is balanced. Further, as the pilot pressure P _P increases, that is, as the amount of deformation of the reaction disk 260 increases, the reaction disk 260 also comes into contact with the front end surface of the reaction force plunger 256 around the protrusion 272. It will be. That is, the contact area between the reaction disk 260 and the reaction force plunger 256 increases. Therefore, the area where the pressure generated by the reaction disk 260 acts on the reaction force plunger 256 increases, and the force that pushes the reaction force plunger 256 and the movable rod 252 backward increases. As a result, as shown in the third section of FIG. 4, the adjustment pressure increase gradient is smaller than that in the second section. Since the reaction disk 260 is made of rubber, when the reaction disk 260 comes into contact with the front end surface of the reaction force plunger 256 from the protruding portion 272, it gradually comes into contact with the front end surface of the reaction force plunger 256. become. For this reason, the transition from the second section to the third section is performed relatively slowly.

≪Operation of vehicle brake system≫
The operation of the vehicle brake system will be described in detail below. When the driver applies an operating force to the brake pedal 70 from a state where the brake pedal 70 is not depressed, the low-pressure communication valve 234 is excited and closed to the reservoir 62 in the facing chamber R4 and the inter-piston chamber R5. Communication is blocked. That is, the facing chamber R4 and the inter-piston chamber R5 are in a sealed state. When the operating force is transmitted to the hydraulic fluid in the inter-piston chamber R5 through the input piston 156 by the brake operation, the pressure of the hydraulic fluid in the inter-piston chamber R5 and the facing chamber R4 increases. As described above, in the first pressure piston 152, the pressure receiving area S _{1 on which} the pressure in the inter-piston chamber R5 acts is larger than the pressure receiving area S ₂ on which the pressure in the counter chamber R4 acts. The force for moving the first pressure piston 152 forward by the pressure of the hydraulic fluid in the chamber R5 is larger than the force for moving the first pressure piston 152 backward by the pressure of the hydraulic fluid in the facing chamber R4. Become. Therefore, when the pressure of the hydraulic fluid in the inter-piston chamber R5 and the counter chamber R4 increases due to the operating force, the first pressurizing piston 152 moves forward due to the force due to the difference between these forces.

  Further, when the driver applies an operating force to the brake pedal 70, the first pilot pressure introduction valve 106 and the second pilot pressure introduction valve 108 are deenergized and opened, respectively. The linear valve 102 and the pressure-reducing linear valve 104 are also de-energized and closed and opened, respectively. Accordingly, the pilot pressure hydraulic fluid is introduced into the pressure regulator 60, and the hydraulic fluid regulated in the input chamber R3 is supplied by operating the pressure regulator 100. When the driver applies an operating force to the brake pedal 70, the hydraulic fluid in the inter-piston chamber R5 immediately rises due to the brake operating force. Therefore, the pressure regulator 100 that uses the hydraulic fluid pressure as a pilot pressure is It works immediately after the start of brake operation. As a result, in addition to the operating force, the first pressurizing piston 152 moves forward by the pressure of the hydraulic fluid in the input chamber R3. Further, when the first pressurizing piston 152 is advanced only by the pressure of the input chamber R3, the inter-piston chamber R5 is in a negative pressure state, and the input piston 156 is retracted to advance. That is, in the master cylinder device 50, the first pressurizing piston 152 and the input piston 156 advance in conjunction with each other via the hydraulic fluid in the inter-piston chamber R5 in a state where the facing chamber R4 and the inter-piston chamber R5 are sealed. Is configured to do.

In the master cylinder device 50, when the first pressurizing piston 152 moves forward, the hydraulic fluid in the facing chamber R4 flows into the inter-piston chamber R5 via the inter-chamber communication passage 228. As described above, the pressure receiving area S _{1 on which} the pressure in the inter-piston chamber R5 acts is larger than the pressure receiving area S ₂ on which the pressure in the facing chamber R4 acts. Further, the area of the front end face of the input piston 156 is substantially the same as the pressure receiving area S _{1 on} which the pressure of the inter-piston chamber R5 acts. Therefore, the advance amount of the input piston 156 is smaller than the advance amount of the first pressurizing piston 152 by the amount of the hydraulic fluid flowing into the inter-piston chamber R5 due to the advancement of the first pressurizing piston 152. That is, in the master cylinder device 50, when the inter-piston chamber R5 is sealed by the low-pressure communication valve 234, an operation advance function that makes the advance amount of the first pressurizing piston 152 larger than the advance amount of the input piston 156 is realized. Can be considered. Therefore, the master cylinder device 50 can pressurize the hydraulic fluid to a relatively high pressure with a relatively small amount of brake operation. Therefore, in the vehicle brake system provided with the master cylinder device 50, the operation of the brake operation member by the driver is reduced, and the operational feeling in the brake operation is improved.

Further, as described above, the first pressurizing piston 152, the pressure receiving area S ₁ in which the pressure in the inter-piston chamber R5 acts, since the pressure of the opposing chamber R4 is larger than the pressure receiving area S ₂ acting, working Due to the advance function, the ratio of the advance amount of the first pressurizing piston 152 to the advance amount of the input piston 156 is 1.3 or more and 3.0 or less, more specifically about 2.0. Therefore, even with a relatively small amount of brake operation, the brake device 56 can generate a sufficiently large braking force, and an appropriate braking force can be generated without generating an excessive braking force. Can do.

As described above, when the first pressurizing piston 152 and the input piston 156 move forward through the hydraulic fluid in the inter-piston chamber R5, the hydraulic fluid in the first pressurizing chamber R1 is pressurized. Moreover, the 2nd pressurization piston 154 advances with the pressurization, and the hydraulic fluid in 2nd pressurization chamber R2 is pressurized. Therefore, the hydraulic fluid supplied to the brake device 56 is pressurized by the operation force and the adjustment pressure, and the hydraulic brake system 40 generates a braking force having a magnitude depending on the operation force and the adjustment pressure. Incidentally, pressure regulator 100, as described above, the adjustment pressure P _A by an initial boost amount [Delta] P _AJ increases suddenly. Therefore, at a relatively early stage after the driver's braking operation is started, the first pressurizing piston 152 moves relatively large, and the brake device 56 can generate a braking force.

  When regenerative braking force is generated by the regenerative braking system, the first pilot pressure introduction valve 106 and the second pilot pressure introduction valve 108 are excited and closed, respectively, and the boost linear valve 102 and Each of the pressure-reducing linear valves 104 is operated based on a command from the brake ECU 38. Accordingly, the hydraulic fluid regulated by the pressure-increasing linear valve 102 and the pressure-decreasing linear valve 104 is supplied to the input chamber R3 of the master cylinder device 50. Therefore, the hydraulic brake system 40 can change the magnitude of the hydraulic braking force according to the magnitude of the regenerative braking force. Therefore, for example, if the adjustment pressure is changed so as to reduce the hydraulic braking force by the amount of the regenerative braking force, the regenerative braking force is generated without changing the braking force generated in the entire vehicle brake system. be able to.

  Next, the operation of the hydraulic brake system 40 when an electrical failure occurs in the hydraulic brake system 40 will be described. At the time of electrical failure, in the pressure regulating device 60, the first pilot pressure introduction valve 106 and the second pilot pressure introduction valve 108 are opened without being excited, respectively, and the input chamber R3 is opened by the pressure regulator 100. The adjusted hydraulic fluid is supplied. However, since the motor 94 of the high-pressure source device 58 cannot drive the hydraulic pump 90, the adjusted hydraulic fluid is not supplied to the input chamber R3 when no high-pressure hydraulic fluid is left in the accumulator 92. It will be. Further, in the event of electrical failure, the low pressure communication valve 234 is de-energized and opens, so that the facing chamber R4 and the inter-piston chamber R5 are communicated with the reservoir 62 via the low pressure open path 234. Therefore, the input piston 156 advanced by the operating force causes the hydraulic fluid in the inter-piston chamber R5 to flow out to the reservoir 62 and contact the first pressurizing piston 152. Therefore, at the time of electrical failure, the input piston 156 and the first pressurizing piston 152 are integrated and advance by only the operating force to pressurize the hydraulic fluid. Therefore, the advance amount of the input piston 156 and the advance amount of the first pressurizing piston 152 at the time of electrical failure are the same. For example, if the inter-piston chamber R5 is sealed even during electrical failure, the master cylinder device 50 determines that the advance amount of the first pressurizing piston 152 is greater than the advance amount of the input piston 156 as described above. Therefore, in order to advance the first pressurizing piston 152, a relatively large operating force is required. However, in the hydraulic brake system 40, when the electric failure occurs, the advance amount of the input piston 156 and the advance amount of the first pressurizing piston 152 are the same, and therefore, the first pressurizing piston with a relatively small operating force. The hydraulic fluid can be pressurized by advancing 152. Therefore, in the vehicle brake system including the master cylinder device 50, the operation of the brake operation member by the driver is reduced even in the case of an electrical failure, and the operational feeling in the brake operation is improved. Therefore, this vehicle brake system is an excellent brake system from the viewpoint of fail-safe.

  In the event of an electrical failure, when the hydraulic fluid having a high pressure remains in the accumulator 92, the pressure regulator 100 may operate using the pressure of the hydraulic fluid in the first pressurizing chamber R1 as a pilot pressure. Thus, the regulated hydraulic fluid is supplied to the input chamber R3. Therefore, the hydraulic fluid supplied to the brake device 56 is pressurized by the operation force and the adjustment pressure, and the hydraulic brake system 40 can generate a braking force having a magnitude depending on the operation force and the adjustment pressure. it can.

  FIG. 5 shows a hydraulic brake system 320 including the master cylinder device of the second embodiment. The hydraulic brake system 320 has a master cylinder device 322. The hydraulic brake system 320 is generally configured similarly to the hydraulic brake system 40 of the first embodiment. In the following description, considering the simplification of the description, the configuration and operation different from the hydraulic brake system 40 of the first embodiment will be described, and the same configuration and operation as the hydraulic brake system 40 of the first embodiment will be described. Description is omitted.

<Configuration of master cylinder device>
The master cylinder device 322 includes a housing 324 that is a housing, a first pressurizing piston 326 and a second pressurizing piston 328 that pressurize hydraulic fluid supplied to the brake device 56, and a driver's operation is input through the operating device 52. The input piston 330 is configured to be included.

  The housing 324 is mainly composed of four members, specifically, a first housing member 332, a second housing member 334, a third housing member 336, and a fourth housing member 338. The first housing member 332 has a generally cylindrical shape whose front end is closed. The second housing member 334 has a generally cylindrical shape, and is integrated with the first housing member 332 by fitting the rear portion of the first housing member 332 into the front end portion. A cylindrical third housing member 336 is disposed inside the second housing member 334 such that its front end fits into the rear end of the first housing member 420. Note that the inner diameter of the third housing member 336 is larger than the inner diameter of the first housing member 332. The fourth housing member 338 has a cylindrical shape with a small diameter portion 340 having a small outer diameter at the front and a large diameter portion 342 having a large outer diameter at the rear. The fourth housing member 338 has a large diameter portion 342 between a rear end portion of the second housing member 334 and a rear end portion of the third housing member 336 in a state where the small diameter portion 340 is located inside the third housing member 336. It is fixed by being sandwiched between them.

  In the housing 324 configured as described above, the large-diameter portion 342 of the third housing member 336 is an annular partition wall portion projecting radially inward, and the small-diameter portion 340 is the partition wall portion. It becomes the cylindrical inner cylinder part extended ahead from the inner end. That is, in the housing 324, a partition portion that partitions the inside of the housing 324 is formed by the small diameter portion 340 and the large diameter portion 342 of the fourth housing member 338. Therefore, the interior of the housing 324 is partitioned into a front chamber R11 including a space outside the small diameter portion 340 and a rear chamber R12 including a space inside the small diameter portion 340. Moreover, the front end of the small diameter part 340 is an opening formed in the partition part.

  The first pressure piston 326 has a shape having a bottomed hole that opens to the front and a bottomed hole that opens to the rear, and a flange 344 is formed on the outer periphery at the rear end. The first pressurizing piston 326 is slidably fitted to the inner peripheral surface of the first housing member 332 at the front, and the flange 344 is slidably fitted to the inner peripheral surface of the third housing member 336. Furthermore, the inner peripheral surface of the bottomed hole that opens to the rear is slidably fitted to the outer peripheral surface of the fourth housing member 338. That is, the small diameter portion 340 of the fourth housing member 338 is inserted into the rear portion of the first pressurizing piston 326, in other words, the rear portion thereof is the third housing member 336 and the fourth housing member 338. It is in a state sandwiched between the small diameter portions 340. The input piston 330 has a substantially cylindrical shape and is disposed in the rear chamber R12. Specifically, a seal is fitted inside the fourth housing member 338.

  In the master cylinder device 322 configured as described above, an input chamber R13 into which hydraulic fluid from the pressure adjusting device 60 is input is defined on the rear side of the flange 344 of the first pressure piston 326. That is, the rear end surface of the flange 344 is a pressure receiving portion to which the pressure of the input chamber R13 acts in the first pressurizing piston 326. In addition, between the inner peripheral surface of the third housing member 336 and the outer peripheral surface of the first pressure piston 326 on the front side of the flange 344, an annular facing chamber R14 that faces the input chamber R13 with the flange 344 interposed therebetween. A compartment is formed. In addition, using the opening at the front end of the small diameter portion 340 of the fourth housing member 338, there is no piston between the front end surface of the input piston 330 and the bottom surface of the bottomed hole that opens behind the first pressure piston 326. A chamber R15 is formed.

In the first pressurizing piston 326, a pressure receiving area S ₃ of the pressure of the hydraulic fluid inter-piston chamber R15 is applied to the first pressurizing piston 326, the pressure of the hydraulic fluid in the opposing chamber R14 is the first pressure The pressure receiving area S ₄ acting on the flange 344 of the piston 326 is made larger. The pressure receiving area S ₃ where the pressure of the hydraulic fluid in the inter-piston chamber R15 acts on the first pressurizing piston 326 is a force that advances the first pressurizing piston 326 by the pressure of the hydraulic fluid in the inter-piston chamber R15. It can be considered an area. In other words, the forward force applied to the first pressurizing piston 326 by the pressure of the hydraulic fluid in the inter-piston chamber R15 divided by the pressure of the hydraulic fluid in the inter-piston chamber R15 is the operation of the inter-piston chamber R15. The pressure of the liquid is a pressure receiving area that acts on the first pressure piston 326. On the other hand, the pressure receiving area S _{4 where} the pressure of the hydraulic fluid in the counter chamber R14 acts on the flange 344 of the first pressure piston 326 is the force that causes the first pressure piston 326 to retract by the pressure of the hydraulic fluid in the counter chamber R14. Can be thought of as the area where the action acts. In other words, the pressure of the hydraulic fluid in the counter chamber R14 is obtained by dividing the backward force applied to the first pressurizing piston 326 by the pressure of the hydraulic fluid in the counter chamber R14 by the pressure of the hydraulic fluid in the counter chamber R14. Is a pressure receiving area acting on the flange 344 of the first pressure piston 326.

Further, the pressure receiving area S ₅ where the pressure of the hydraulic fluid in the inter-piston chamber R15 acts on the input piston 330, that is, the area S ₅ where the force for moving the input piston 330 backward by the pressure of the hydraulic fluid in the inter-piston chamber R15 acts. is smaller than the pressure receiving area S ₃ of the pressure in the inter-piston chamber R15 is applied to the first pressurizing piston 326. In the master cylinder device 322, the pressure receiving area S ₃ of the pressure in the inter-piston chamber R15 is applied to the first pressurizing piston 326, a pressure receiving area S ₄ of the pressure of the opposing chamber R14 is applied to the first pressurizing piston 326 The pressure receiving area S ₅ where the pressure in the inter-piston chamber R15 acts on the input piston 330 is set so that the relationship of 1.3 ≦ S ₅ / (S ₃ −S ₄ ) ≦ 3.0 is established.

  A gap having a channel area capable of allowing the hydraulic fluid to flow to some extent between the inner peripheral surface of the bottomed hole that opens to the rear of the first pressure piston 326 and the small diameter portion 340 of the fourth housing member 338. 346 is provided. The first pressurizing piston 326 is provided with a communication hole 348 having one end opened in the gap 346 and the other end opened in the facing chamber R14. Therefore, the clearance 346 and the communication hole 348 form an inter-chamber communication path that communicates the facing chamber R14 and the inter-piston chamber R15. Further, assuming that the inter-piston chamber R15 including the gap 346 is partitioned, the communication hole 348 has one end opened to the inter-piston chamber R15 with a bottomed hole, and the other end is in front of the flange 344. It can be considered that this is an internal communication path formed inside the first pressurizing piston 326 so as to open to the inside. Therefore, the master cylinder device 322 does not have an inter-chamber communication path outside the housing 324, and has a relatively simple and compact configuration. The second housing member 334 is provided with a communication hole 350 having one end opened to the facing chamber R14. The third housing member 336 has one end facing the other end of the communication hole 350. A communication hole 352 that is open and has a connection port that opens to the outside at the other end is provided. Therefore, the inter-piston chamber R15 communicates with the outside via the counter chamber R14. Between the outer peripheral surface of the second housing member 334 and the inner peripheral surface of the fourth housing member 338, there is provided a gap 354 having a flow path area through which hydraulic fluid can flow to some extent. In addition, the third housing member 336 is provided with a communication hole 356 having one end opened in the gap 354 and the other end opened in the input chamber R13. In addition, the second housing member 334 is provided with a communication hole 358 having a connection port with one end opening in the gap 354 and the other end opening outside. Therefore, the input chamber R13 communicates with the outside.

  Outside the housing 324, the other end of the adjustment pressure supply path 240 to which the adjusted hydraulic fluid is supplied is connected to the connection port of the communication hole 358. Therefore, the hydraulic fluid regulated by the pressure regulating device 60 can be supplied to the input chamber R13. One end of the low-pressure communication path 232 is connected to a connection port of the communication hole 352. The low-pressure communication path 232 branches between the low-pressure communication valve 234 and the communication hole 352, and the branched communication path serves as a first pilot pressure supply path 360 to a connection port of the communication hole 292 of the pressure regulator 100. It is connected. Therefore, the hydraulic fluid having the pressure in the facing chamber R14 and the inter-piston chamber R15 can be supplied to the first pilot chamber P1 of the pressure regulator 100.

≪Operation of vehicle brake system≫
The operation of the vehicle brake system will be described in detail below. When the driver applies an operating force to the brake pedal 70 from a state where the brake pedal 70 is not depressed, the low-pressure communication valve 234 is excited and closed to the reservoir 62 of the facing chamber R14 and the inter-piston chamber R15. Communication is blocked. Therefore, when the input piston 330 moves forward by the brake operation, the pressure of the hydraulic fluid in the inter-piston chamber R15 and the opposing chamber R14 increases. As described above, the first pressurizing piston 326, a pressure receiving area S ₃ of the pressure in the inter-piston chamber R15 acts, since the pressure of the opposing chamber R14 is larger than the pressure receiving area S ₄ which acts, inter piston The force for moving the first pressurizing piston 326 forward by the pressure of the hydraulic fluid in the chamber R15 is larger than the force for moving the first pressurizing piston 326 backward by the pressure of the hydraulic fluid in the facing chamber R14. Become. Therefore, when the pressure of the hydraulic fluid in the inter-piston chamber R15 and the counter chamber R14 rises due to the operating force, the first pressurizing piston 326 moves forward due to the force due to the difference between these forces.

  Further, when the driver applies an operating force to the brake pedal 70, the hydraulic fluid regulated by the pressure regulator 100 is supplied to the input chamber R13. Therefore, the first pressurizing piston 326 moves forward based on the pressure of the hydraulic fluid in the input chamber R13 in addition to the operating force. Further, the second pressurizing piston 328 moves forward with the advance, and the hydraulic fluid in the pressurizing chambers R1 and R2 is pressurized. Further, when the first pressurizing piston 326 is advanced only by the pressure of the input chamber R13, the inter-piston chamber R15 is in a negative pressure state, and the input piston 330 is retracted to advance. That is, in the master cylinder device 322, the first pressurizing piston 326 and the input piston 330 advance in conjunction with each other via the hydraulic fluid in the inter-piston chamber R15 in a state where the facing chamber R14 and the inter-piston chamber R15 are sealed. Is configured to do.

In the master cylinder device 322, when the first pressurizing piston 326 moves forward, the working fluid of the working fluid in the facing chamber R14 flows into the inter-piston chamber R15 via the gap 346 and the communication hole 348. Further, as described above, the pressure receiving area S _{3 on which} the pressure in the inter-piston chamber R15 acts is larger than the pressure receiving area S ₄ on which the pressure in the facing chamber R14 acts. Further, the pressure receiving area S ₅ where the pressure of the hydraulic fluid in the inter-piston chamber R15 acts on the input piston 330 is greater than the pressure receiving area S ₃ where the pressure in the inter-piston chamber R15 acts on the first pressurizing piston 326 as described above. However, the area S ₃ is set so that at least the advance amount of the first pressurizing piston 326 is larger than the advance amount of the input piston 330. Specifically, forward amount D _I of the input piston 330, when the forward movement amount of the first pressurizing piston 326 and D _P, the advancement of the input piston 330 and the first pressurizing piston 326 described above, pistons The relationship of the following equation is established between the change in the inter-piston chamber volume due to the forward movement and the volume of the hydraulic fluid flowing into the inter-piston chamber R15 from the facing chamber R14.
S ₅ × D _I = (S ₃ −S ₄ ) × D _P
Accordingly, in a state where this relationship holds, specifically, the advance amount D _{I of the} input piston 330 is larger than the advance amount D _I of the input piston 330 so that the advance amount D _{P of} the first pressurizing piston 326 is larger. the ratio of the forward amount D _P of the first pressurizing piston 326 against is such that 1.3 or more and 3.0 or less, and more specifically, so that the 2.0, the inter-piston chamber R15 A pressure receiving area S ₅ where the pressure of the hydraulic fluid acts on the input piston 330 is set. That is, the pressure receiving area S ₅ is set so that the relationship of the following equation is established.
S ₅ = 2 × (S ₃ −S ₄ )

  Therefore, in the master cylinder device 322, when the inter-piston chamber R15 is sealed by the low-pressure communication valve 234, an operation advance function that makes the advance amount of the first pressurizing piston 326 larger than the advance amount of the input piston 330 is realized. Can be considered. Therefore, the master cylinder device 322 can pressurize the hydraulic fluid to a high pressure with a relatively small amount of brake operation. Therefore, in the vehicle brake system provided with the master cylinder device 322, the operation of the brake operation member by the driver is reduced, and the operational feeling in the brake operation is improved. Further, as described above, the ratio of the advance amount of the first pressurizing piston 326 to the advance amount of the input piston 330 is 2.0 by the operation advance function. Therefore, a sufficiently large braking force can be generated by the brake device 56 even with a relatively small amount of brake operation, and an appropriate braking force can be generated without generating an excessive braking force. it can.

  Next, when an electrical failure occurs in the hydraulic brake system 320, the facing chamber R <b> 14 and the inter-piston chamber R <b> 15 are communicated with the reservoir 62 via the low pressure release path 234. Therefore, the input piston 330 advanced by the operating force causes the hydraulic fluid in the inter-piston chamber R15 to flow into the reservoir 62 and contact the first pressurizing piston 326. The input piston 330 and the first pressurizing piston 326 are Integrally, the hydraulic fluid can be pressurized by moving forward by relying only on the operating force. Therefore, the advance amount of the input piston 330 and the advance amount of the first pressurizing piston 326 at the time of electrical failure are the same. Therefore, the hydraulic fluid can be pressurized by moving the first pressurizing piston 326 forward with a relatively small operating force. Therefore, in the brake system for a vehicle provided with the master cylinder device 322, the operation of the brake operation member by the driver is reduced even when there is an electrical failure, and the operational feeling in the brake operation is improved. Therefore, this vehicle brake system is an excellent brake system from the viewpoint of fail-safe.

  FIG. 6 shows a hydraulic brake system 400 including the master cylinder device of the third embodiment. The hydraulic brake system 400 has a master cylinder device 402. The hydraulic brake system 400 is generally configured similarly to the hydraulic brake system 40 of the first embodiment. In the following description, considering the simplification of the description, the configuration and operation different from the hydraulic brake system 40 of the first embodiment will be described, and the same configuration and operation as the hydraulic brake system 40 of the first embodiment will be described. Description is omitted.

<Configuration of master cylinder device>
The master cylinder device 402 includes a housing 412 that is a housing of the master cylinder device 402, a first pressurizing piston 414 and a second pressurizing piston 416 that pressurize the hydraulic fluid supplied to the brake device 56, and a driver's operation. An input piston 418 that is input through the operation device 52 is included. FIG. 6 shows a state where the master cylinder device 402 is not operating, that is, a state where the brake operation is not performed.

  The housing 412 mainly includes four members, specifically, a first housing member 420, a second housing member 422, a third housing member 424, and a fourth housing member 426. The first housing member 420 has a generally cylindrical shape whose front end is closed. The second housing member 422 has a generally cylindrical shape, and is integrated with the first housing member 420 by fitting the rear portion of the first housing member 420 into the front end portion.

  A cylindrical third housing member 424 is disposed inside the second housing member 422 so that its front end fits into the rear end of the first housing member 420. The third housing member 424 has a cylindrical shape with an inner collar 428 formed at the rear end. Further, a through hole 430 is formed at the rear end of the third housing member 424 by the inner flange 428. The inner diameter of the third housing member 424 is larger than the inner diameter of the first housing member 420. A cylindrical fourth housing member 426 is further disposed in the second housing member 422 between the rear end surface of the third housing member 424 and the rear end portion of the second housing member 422. The interior of the housing 412 configured as described above is partitioned into a front chamber R21 located on the front side and a rear chamber R22 located on the rear side by the inner flange 428 of the second housing member 422. That is, the inner flange 428 is a partition portion that partitions the inside of the housing 412, and the through hole 430 is an opening in the partition portion.

  The second pressurizing piston 416 is slidably fitted to the first housing member 420 in the front chamber R21 through a seal. The first pressurizing piston 414 is disposed behind the second pressurizing piston 416 in the front chamber R <b> 21, and has a bottomed cylindrical main body 432 with a closed rear end, and penetrates from the main body 432. And an extending portion 434 extending into the rear chamber R22 through the hole 430. Further, a flange 436 is provided on the outer periphery of the rear end portion of the main body portion 432. In the first pressure piston 414, the front side of the main body 432 is in the first housing member 420, the flange 436 is in the inner peripheral surface of the third housing member 424, and the extension 434 is in the through hole 430 in the third housing member 424. Each is slidably fitted into the housing 412 via a seal. Incidentally, the first pressurizing piston 414 has its rear end restricted by abutting the rear end of the main body portion 432 against the front end surface of the inner flange 428 of the third housing member 424.

  The input piston 418 is roughly cylindrical. The input piston 418 is disposed in the rear chamber R22, and is fitted to the fourth housing member 426 via a seal behind the extending portion 434 of the first pressure piston 414. Incidentally, the input piston 418 has its stepped portion provided on the outer peripheral surface in front of itself being brought into contact with the stepped portion provided on the inner peripheral surface at the rear of the fourth housing member 426, so that the backward movement of the input piston 418 is restricted. Yes.

  In the master cylinder device 402 configured as described above, an input chamber R23 into which hydraulic fluid from the pressure adjusting device 60 is input is defined on the rear side of the flange 436 of the main body portion 432 of the first pressure piston 414. ing. That is, the rear end surface of the flange 436 is a pressure receiving portion to which the pressure of the input chamber R23 acts in the first pressure piston 414. In addition, an annular facing chamber R24 facing the input chamber R23 across the flange 436 is defined between the inner peripheral surface of the third housing member 424 and the outer peripheral surface of the first pressure piston 414 in front of the flange 436. Is formed. Further, in a state where the brake operation is not performed between the rear end surface of the extending portion 434 of the first pressure piston 414 extending to the rear chamber R22 using the through hole 430 and the front end surface of the input piston 418. A gap is provided. That is, the first pressure piston 414 and the input piston 418 face each other across the gap, and an inter-piston chamber R25 is formed around the extending portion 434 including the gap.

In the first pressurizing piston 414, the pressure of the working fluid in the inter-piston chamber R25 is the first pressurizing piston 414, the pressure receiving area S ₆ acting at the rear end surface of the extension portion 434, the opposing chamber R24 of The pressure of the hydraulic fluid is larger than the pressure receiving area S ₇ that acts on the flange 436 of the first pressurizing piston 152. The pressure receiving area S ₆ where the pressure of the hydraulic fluid in the inter-piston chamber R25 acts on the first pressurizing piston 414 is the force that advances the first pressurizing piston 414 by the pressure of the hydraulic fluid in the inter-piston chamber R25. It can be considered an area. In other words, the forward force applied to the first pressurizing piston 414 by the pressure of the hydraulic fluid in the inter-piston chamber R25 divided by the pressure of the hydraulic fluid in the inter-piston chamber R25 is the operation of the inter-piston chamber R25. The pressure of the liquid is a pressure receiving area that acts on the first pressure piston 414. On the other hand, the pressure receiving area S _{7 where} the pressure of the hydraulic fluid in the counter chamber R24 acts on the flange 436 of the first pressure piston 414 is the force that causes the first pressure piston 414 to move backward by the pressure of the hydraulic fluid in the counter chamber R24. Can be thought of as the area where the action acts. In other words, the pressure of the hydraulic fluid in the counter chamber R24 is obtained by dividing the backward force applied to the first pressurizing piston 414 by the pressure of the hydraulic fluid in the counter chamber R24 by the pressure of the hydraulic fluid in the counter chamber R24. Is a pressure receiving area acting on the flange 436 of the first pressure piston 414.

In the first pressurizing piston 414, the pressure receiving area S ₆ acting pressure of the inter-piston chamber R25 is more than 1.5 times the pressure-receiving area S ₇ acting pressure of the opposing chamber R24 and 4.33 times and less That is, it is set so that the relationship of 1.5 ≦ S ₆ / S ₇ ≦ 4.33 is established. Further, the pressure receiving area where the pressure of the hydraulic fluid in the inter-piston chamber R25 acts on the input piston 418, that is, the area where the force for retreating the input piston 418 by the pressure of the hydraulic fluid in the inter-piston chamber R25 is the inter-piston chamber. pressure R25 is almost the same size as the pressure-receiving area S ₆ that acts on the first pressurizing piston 418.

  The first housing member 420 is provided with a communication hole 450 having one end opened to the facing chamber R24. The third housing member 424 has a communication hole 452 having one end facing the other end of the communication hole 450 and opening. Is provided. Further, the second housing member 422 is provided with a communication hole 454 having one end facing the other end of the communication hole 452 and the other end being a connection port that opens to the outside. The counter chamber R24 communicates with the outside through the holes 450, 452, and 454. The first pressurizing piston 414 is provided with a liquid passage 455 having one end opened on the rear end surface of the extending portion 434 and the other end opened on the side surface of the main body 432 in front of the flange 436. That is, the liquid passage 455 forms an inter-chamber communication passage that connects the inter-piston chamber R25 and the counter chamber R24. The liquid passage 455 is formed inside the first pressurizing piston 414 so that one end opens to the inter-piston chamber R25 at the extending portion 434 and the other end opens to the facing chamber R24 in front of the flange 436. It is an internal communication path. Therefore, the master cylinder device 402 does not have an inter-chamber communication path outside the housing 412 and has a relatively simple and compact configuration. The third housing member 424 is provided with a communication hole 456 having one end opened to the input chamber R23, and the second housing member 422 has one end opened to face the other end of the communication hole 456 and the other end A communication hole 458 is provided as a connection port that opens to the outside. That is, the input chamber R23 communicates with the outside through the communication holes 456 and 458.

  A communication hole 460 having one end opened to the inter-piston chamber R25 is provided at the front end portion of the fourth housing member 426. One end of the second housing member 422 faces the other end of the communication hole 460. A communication hole 462 that is open and has a connection port that opens to the outside at the other end is provided. That is, the inter-piston chamber R25 communicates with the outside through the communication holes 460 and 462.

  Outside the housing 412, the other end of the adjustment pressure supply path 240 to which the adjusted hydraulic fluid is supplied is connected to the connection port of the communication hole 458. Therefore, the hydraulic fluid regulated by the pressure regulating device 60 can be supplied to the input chamber R23. One end of a first pilot pressure supply path 464 connected to the pressure regulator 100 is connected to the connection port of the communication hole 462. Therefore, the first pilot chamber P1 of the pressure regulator 100 can be supplied with hydraulic fluid having the pressure in the facing chamber R24 and the inter-piston chamber R25.

≪Operation of vehicle brake system≫
The operation of the vehicle brake system will be described in detail below. When the driver applies an operating force to the brake pedal 70 from a state where the brake pedal 70 is not depressed, the low-pressure communication valve 234 is excited and closed to the reservoir 62 in the facing chamber R24 and the inter-piston chamber R25. Communication is blocked. Accordingly, when the input piston 418 moves forward by the brake operation, the pressure of the hydraulic fluid in the inter-piston chamber R25 and the opposing chamber R24 increases. As described above, the first pressurizing piston 326, the pressure receiving area S ₆ the pressure in the inter-piston chamber R25 acts, because they are larger than the pressure receiving area S ₇ that the pressure of the opposing chamber R24 acts, between the piston The force for moving the first pressurizing piston 326 forward by the pressure of the hydraulic fluid in the chamber R25 is larger than the force for moving the first pressurizing piston 326 backward by the pressure of the hydraulic fluid in the facing chamber R24. Become. Therefore, when the pressure of the hydraulic fluid in the inter-piston chamber R25 and the counter chamber R24 increases due to the operating force, the first pressurizing piston 414 moves forward due to the force due to the difference between these forces.

  Further, when the driver applies an operating force to the brake pedal 70, the hydraulic fluid regulated by the pressure regulator 100 is supplied to the input chamber R23. Therefore, the first pressurizing piston 414 moves forward based on the pressure of the hydraulic fluid in the input chamber R23 in addition to the operating force. Further, the second pressurizing piston 416 moves forward with the advance, and the hydraulic fluid in the pressurizing chambers R1 and R2 is pressurized. Further, when the first pressurizing piston 414 is advanced only by the pressure in the input chamber R23, the inter-piston chamber R25 is in a negative pressure state, and the input piston 418 is retracted to advance. That is, in the master cylinder device 402, the first pressurizing piston 414 and the input piston 418 advance in conjunction with each other via the hydraulic fluid in the inter-piston chamber R25 in a state where the facing chamber R24 and the inter-piston chamber R25 are sealed. Is configured to do.

In the master cylinder device 402, when the first pressurizing piston 414 moves forward, the hydraulic fluid in the facing chamber R24 flows into the inter-piston chamber R25 through the gap 346 and the communication hole 348. Further, as described above, the pressure receiving area S ₆ where the pressure in the inter-piston chamber R25 acts is larger than the pressure receiving area S ₇ where the pressure in the facing chamber R24 acts. The area of the front end face of the input piston 418 has a pressure receiving area S ₆ the pressure in the inter-piston chamber R25 acts substantially the same size. Therefore, the advance amount of the input piston 418 is smaller than the advance amount of the first pressurizing piston 414 by the amount of the hydraulic fluid flowing into the inter-piston chamber R25 due to the advancement of the first pressurizing piston 414. In other words, in the master cylinder device 402, when the inter-piston chamber R5 is sealed by the low-pressure communication valve 234, an operation advance function that makes the advance amount of the first pressurizing piston 414 larger than the advance amount of the input piston 418 is realized. Can be considered. Therefore, the master cylinder device 402 can pressurize the hydraulic fluid to a relatively high pressure with a relatively small amount of brake operation. Therefore, in the vehicle brake system provided with the master cylinder device 402, the operation of the brake operation member by the driver is reduced, and the operational feeling in the brake operation is improved.

Further, as described above, the first pressurizing piston 414, the pressure receiving area S ₆ the pressure in the inter-piston chamber R25 acts, since the pressure of the opposing chamber R24 is larger than the pressure receiving area S ₇ acting, working Due to the advance function, the ratio of the advance amount of the first pressurizing piston 414 to the advance amount of the input piston 418 is 1.3 or more and 3.0 or less, more specifically about 2.0. Therefore, even with a relatively small amount of brake operation, the brake device 56 can generate a sufficiently large braking force, and an appropriate braking force can be generated without generating an excessive braking force. Can do.

  Next, when an electrical failure occurs in the hydraulic brake system 400, the facing chamber R24 and the inter-piston chamber R25 are communicated with the reservoir 62 via the low-pressure release path 234. Therefore, the input piston 418 advanced by the operating force causes the hydraulic fluid in the inter-piston chamber R25 to flow out into the reservoir 62 and contact the first pressurizing piston 414. The input piston 418 and the first pressurizing piston 414 are Integrally, the hydraulic fluid can be pressurized by moving forward by relying only on the operating force. Therefore, the advance amount of the input piston 418 and the advance amount of the first pressurizing piston 414 at the time of electrical failure are the same. Therefore, the hydraulic fluid can be pressurized by moving the first pressurizing piston 414 forward with a relatively small operating force. Therefore, in the vehicle brake system including the master cylinder device 402, the operation of the brake operation member by the driver is reduced even in the case of an electrical failure, and the operational feeling in the brake operation is improved. Therefore, this vehicle brake system is an excellent brake system from the viewpoint of fail-safe.

  FIG. 7 shows a hydraulic brake system 500 used in the vehicle brake system of the fourth embodiment. The hydraulic brake system 500 has a master cylinder device 502. The hydraulic brake system 500 is generally configured similarly to the hydraulic brake system 400 of the third embodiment. In the following description, considering the simplification of the description, the configuration and operation different from the hydraulic brake system 400 of the first embodiment will be described, and the same configuration and operation as the hydraulic brake system 400 of the third embodiment will be described. Description is omitted.

<Configuration of master cylinder device>
In the master cylinder device 502, the liquid passage 455 is not provided in the first pressurizing piston 414, and the facing chamber R24 and the inter-piston chamber R25 are not communicated with each other. The facing chamber R24 is connected to the low-pressure communication path 232 via a gap between the outer peripheral surface of the first pressurizing piston 414 and the inner peripheral surface of the first housing member 420, and is always in communication with the reservoir 62. Yes. One end of the low-pressure communication path 232 is connected to the connection port of the communication hole 462 so that the inter-piston chamber R25 can communicate with the reservoir 62.

Further, in the master cylinder device 502, which is thinner outer diameter of the extending portion 434 of the first pressurizing piston 414, the pressure receiving area S ₈ the pressure in the inter-piston chamber R25 is applied to the input piston 418, inter-piston chamber pressure R25 is larger than the pressure receiving area S ₉ that acts on the first pressurizing piston 414. A pressure-receiving area S ₈ the pressure in the inter-piston chamber R25 is applied to the input piston 418, the pressure of the hydraulic fluid inter-piston chamber R25, the force to retract the input piston 418 can be considered as an area to act. In other words, the backward force applied to the input piston 418 by the pressure of the hydraulic fluid in the inter-piston chamber R25 divided by the pressure of the hydraulic fluid in the inter-piston chamber R25 is the pressure of the hydraulic fluid in the inter-piston chamber R25. Becomes the pressure receiving area acting on the input piston 418. On the other hand, the pressure receiving area S ₉ that the pressure of the piston chamber R25 is applied to the first pressurizing piston 414, by the pressure of the hydraulic fluid inter-piston chamber R25, and the area of force to advance the first pressurizing piston 414 acts Can think. In other words, the forward force applied to the first pressurizing piston 414 by the pressure of the hydraulic fluid in the inter-piston chamber R25 divided by the pressure of the hydraulic fluid in the inter-piston chamber R25 is the operation of the inter-piston chamber R25. The pressure of the liquid is a pressure receiving area that acts on the first pressure piston 414.

The pressure receiving area S ₈ where the pressure in the inter-piston chamber R25 acts on the input piston 418 is 1.3 times or more the pressure receiving area S ₉ where the pressure in the piston chamber R25 acts on the first pressurizing piston 414 and 3.0. More specifically, it is about 2.0 times in the master cylinder device 502.

≪Operation of vehicle brake system≫
The operation of the vehicle brake system will be described in detail below. When the driver applies operating force to the brake pedal 70 from a state where the brake pedal 70 is not depressed, the low-pressure communication valve 234 is excited and closed, and communication between the inter-piston chamber R25 and the reservoir 62 is cut off. Is done. That is, the inter-piston chamber R25 is sealed. When the driver applies an operating force to the brake pedal 70, the first pressurizing piston 414 is advanced through the hydraulic fluid in the inter-piston chamber R25. In the master cylinder device 502, when the first pressurizing piston 414 is advanced only by the pressure of the input chamber R23, the inter-piston chamber R25 is in a negative pressure state, and the input piston 418 is pulled. Will move forward. That is, the master cylinder device 502 is configured such that the first pressurizing piston 414 and the input piston 418 advance in conjunction with each other via the hydraulic fluid in the inter-piston chamber R25 in a state where the inter-piston chamber R25 is sealed. Has been.

Further, as described above, the pressure receiving area S ₈ where the pressure in the inter-piston chamber R25 acts on the input piston 418 is made larger than the pressure receiving area S ₉ where the pressure in the piston chamber R25 acts on the first pressurizing piston 414. Yes. Therefore, when the input piston 418 and the first pressurizing piston 414 move forward by the brake operation, the advance amount of the input piston 418 is larger than the advance amount of the first pressurizing piston 414 by an amount corresponding to the difference in area. Get smaller. In other words, in the master cylinder device 402, when the inter-piston chamber R25 is sealed by the low-pressure communication valve 234, an operation advance function that makes the advance amount of the first pressurizing piston 414 larger than the advance amount of the input piston 418 is realized. Can be considered. Therefore, the master cylinder device 502 can pressurize the hydraulic fluid to a high pressure with a relatively small amount of brake operation. Therefore, in the vehicle brake system provided with the master cylinder device 502, the operation of the brake operation member by the driver is reduced, and the operational feeling in the brake operation is improved.

As described above, the pressure receiving area S ₈ where the pressure in the inter-piston chamber R25 acts on the input piston 418 is about 2.0 of the pressure receiving area S ₉ where the pressure in the piston chamber R25 acts on the first pressurizing piston 414. Therefore, the ratio of the advance amount of the first pressurizing piston 414 to the advance amount of the input piston 418 is 1.3 or more and 3.0 or less, more specifically about 2.0. Therefore, even with a relatively small amount of brake operation, the brake device 56 can generate a sufficiently large braking force, and an appropriate braking force can be generated without generating an excessive braking force. Can do.

  Next, when an electrical failure occurs in the hydraulic brake system 400, the hydraulic fluid adjusted by the pressure regulator 100 is supplied to the input chamber R23, and the inter-piston chamber R25 is connected to the low-pressure open path. 234 communicates with the reservoir 62. Therefore, the input piston 418 advanced by the operating force causes the hydraulic fluid in the inter-piston chamber R25 to flow out into the reservoir 62 and contact the first pressurizing piston 414. The input piston 418 and the first pressurizing piston 414 are Integrally, the hydraulic fluid can be pressurized by moving forward by relying only on the operating force. Therefore, the advance amount of the input piston 418 and the advance amount of the first pressurizing piston 414 at the time of electrical failure are the same. Therefore, the hydraulic fluid can be pressurized by moving the first pressurizing piston 414 forward with a relatively small operating force. Therefore, in the vehicle brake system including the master cylinder device 502, the operation of the brake operation member by the driver is reduced even in the case of an electrical failure, and the operational feeling in the brake operation is improved. Therefore, this vehicle brake system is an excellent brake system from the viewpoint of fail-safe.

  50: Master cylinder device 56: Brake device 58: High pressure source device 70: Brake pedal (brake operating member) 150: Housing 152: First pressurizing piston (pressurizing piston) 156: Input piston 174: 鍔 228: Inter-chamber link Passage 232: Low pressure communication passage 234: Low pressure communication valve (low pressure source communication mechanism) R1: First pressurizing chamber (pressurizing chamber) R3: Input chamber R4: Opposite chamber R5: Piston chamber 322: Master cylinder device 324: Housing 326: first pressurizing piston (pressurizing piston) 330: input piston 344: rod 348: communication hole (internal communication path) R11: front chamber R12: rear chamber R13: input chamber R14: counter chamber R15: chamber between pistons 402 : Master cylinder device 412: Housing 41 4: First pressurizing piston (pressurizing piston) 418: Input piston 428: Inner flange (partition section) 430: Through hole (opening) 434: Extension section 436: Spear 455: Liquid path (internal communication path) R21: Front chamber R22: Rear chamber R23: Input chamber R24: Opposite chamber R25: Piston chamber 502: Master cylinder device

Claims (3)

A master cylinder device for supplying pressurized hydraulic fluid to a brake device that is provided on a wheel and operates by the pressure of the hydraulic fluid,
A housing;
A pressure piston disposed in the housing and receiving a pressure of hydraulic fluid introduced from the high-pressure source into the master cylinder device, and advanced by the pressure of the hydraulic fluid;
An input piston disposed in the housing behind the pressurizing piston and connected to a brake operation member at a rear end;
Have
(a) To pressurize the hydraulic fluid supplied to the brake device on the front side of the pressurizing piston.
A pressure chamber, and (b) a pipe filled with hydraulic fluid between the pressure piston and the input piston.
And (c) hydraulic fluid from a high pressure source is introduced into the rear side of the pressure receiving portion of the pressurizing piston.
Are divided into input rooms,
The pressurizing piston and the input piston advance in conjunction with each other via the hydraulic fluid in the inter-piston chamber, and depending on either the pressure of the hydraulic fluid in the input chamber or the operating force applied to the brake operation member Is configured to be able to pressurize the hydraulic fluid in the pressurizing chamber,
Furthermore, the pressurizing piston has a flange formed around the pressurizing piston,
The input chamber is partitioned on the rear side of the ridge so that the rear end surface of the ridge is used as the pressure receiving portion, and the opposite chamber facing the input chamber is defined on the front side of the ridge with the ridge interposed therebetween. And
An inter-chamber communication path for communicating the counter chamber and the inter-piston chamber;
By the pressure of the hydraulic fluid of the inter-piston chamber is the pressure receiving area that acts on the pressure piston is larger than the pressure receiving area of the pressure of the hydraulic fluid of the opposing chamber acts on the collar of the pressure piston A master cylinder device having a differential advance function that makes the advance amount of the pressure piston larger than the advance amount of the input piston . A master cylinder device for supplying pressurized hydraulic fluid to a brake device that is provided on a wheel and operates by the pressure of the hydraulic fluid,
A housing;
A pressure piston disposed in the housing and receiving a pressure of hydraulic fluid introduced from the high-pressure source into the master cylinder device, and advanced by the pressure of the hydraulic fluid;
An input piston disposed in the housing behind the pressurizing piston and connected to a brake operation member at a rear end;
Have
(a) To pressurize the hydraulic fluid supplied to the brake device on the front side of the pressurizing piston.
A pressure chamber, and (b) a pipe filled with hydraulic fluid between the pressure piston and the input piston.
And (c) hydraulic fluid from a high pressure source is introduced into the rear side of the pressure receiving portion of the pressurizing piston.
Are divided into input rooms,
The pressurizing piston and the input piston advance in conjunction with each other via the hydraulic fluid in the inter-piston chamber, and depending on either the pressure of the hydraulic fluid in the input chamber or the operating force applied to the brake operation member Is configured to be able to pressurize the hydraulic fluid in the pressurizing chamber,
The pressure receiving area in which the pressure in the inter-piston chamber acts on the input piston is made larger than the pressure receiving area in which the pressure in the inter-piston chamber acts on the pressurizing piston. A master cylinder device having a differential advance function for making it larger than the advance amount of the input piston . 3. The master cylinder device according to claim 1 , further comprising a low-pressure source communication mechanism that communicates the inter-piston chamber with a low-pressure source by its own operation.

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