JP6040097B2 - Brake system for vehicles - Google Patents

Description

  The present invention relates to a vehicle brake system.

  For example, Patent Literature 1 discloses a vehicle brake device (vehicle brake system) that can quickly detect a leak of brake fluid.

International Publication Number WO2012 / 105526

The vehicle brake device described in Patent Document 1 generates a brake fluid pressure by displacing the first and second pistons of a slave cylinder (motor cylinder device) according to the operation of an actuator (ball screw shaft or the like). The brake hydraulic pressure generated in the slave cylinder is supplied to the wheel cylinder (brake operating unit) through two independent hydraulic systems. Each of the two hydraulic systems is provided with a hydraulic pressure sensor so that the brake hydraulic pressure in each hydraulic system can be measured.
In addition, the control means for controlling the vehicle brake device is fed back with the measured value of the brake fluid pressure in each hydraulic system, and the control means is a slave cylinder so that a suitable brake fluid pressure is generated by feedback control. To control.
When it is determined that a brake fluid leak (leakage) has occurred in one hydraulic system, the control means feeds back from a hydraulic sensor disposed in the other hydraulic system in which no leak has occurred. A suitable brake fluid pressure is generated in the slave cylinder by feedback control using the measured value.

  In such a vehicle brake device, when there is no brake fluid leakage or the like, the changes in the brake fluid pressure in the two hydraulic systems are almost equal, and the hydraulic pressure sensor is provided only in one of the hydraulic systems. It is also possible to adopt a configuration. With such a configuration, since one hydraulic pressure sensor can be reduced, the cost of the vehicle brake device can be reduced.

In the case where the hydraulic pressure sensor is provided in one of the two independent hydraulic pressure systems, as described above, there is no inconvenience during normal operation, but for example, the hydraulic pressure at which the hydraulic pressure sensor is provided. When a brake fluid leak occurs in the system, it becomes impossible to accurately measure the brake fluid pressure by the fluid pressure sensor. Therefore, feedback control that feeds back the measured value of the brake hydraulic pressure in the hydraulic system to the control means becomes impossible.
On the other hand, when the brake fluid leaks in the hydraulic system where the hydraulic pressure sensor is not provided, it is possible to accurately measure the brake hydraulic pressure using the hydraulic pressure sensor. Therefore, feedback control in which the measured value of the brake hydraulic pressure in the hydraulic system is fed back to the control means is possible.

However, when a brake fluid leak occurs, it is not determined whether the leak has occurred in the hydraulic system in which the hydraulic sensor is provided or in the hydraulic system in which the hydraulic sensor is not provided. The control means cannot determine whether or not the measured value of the hydraulic pressure sensor is accurate. Therefore, conventionally, when it is determined that a brake fluid leak has occurred, the control unit stops feedback control that feeds back the measurement value of the hydraulic pressure sensor.
For example, the control means calculates a target value (target operation amount) of the operation amount of the actuator of the slave cylinder according to the operation amount of the brake operation unit (brake pedal). The control means controls the actuator by feedback control that feeds back a measured value of the operation amount of the actuator to the control means.

Since there is a certain correspondence between the operation amount of the actuator of the slave cylinder and the brake fluid pressure generated in the slave cylinder, the control means operates the actuator with high accuracy by feedback control, and the brake fluid suitable for the slave cylinder is obtained. Pressure can be generated.
However, if an error occurs in the brake fluid pressure generated in the slave cylinder with respect to the operation of the actuator, the slave cylinder cannot generate a suitable brake fluid pressure even if the actuator operates accurately.
For example, there may be an error in the brake fluid pressure generated in the slave cylinder with respect to the operation of the actuator due to a change in the viscosity of the brake fluid caused by a temperature change or a change in the volume of the brake fluid.

  That is, regarding the accuracy of the brake fluid pressure generated in the slave cylinder, the feedback control that feeds back the operation amount of the actuator is less accurate than the feedback control that feeds back the measured value of the brake fluid pressure.

  Therefore, an object of the present invention is to provide a vehicle brake system that can reduce a decrease in accuracy of hydraulic pressure supplied to a brake operating portion even when a brake fluid leak occurs.

  In order to solve the above-mentioned problems, the present invention is directed to pressurizing brake fluid by an operation of an actuator to generate a hydraulic pressure according to an operation amount of a brake operation unit, and the generated hydraulic pressure is composed of two independent hydraulic systems. A hydraulic pressure generating means for supplying to the brake operating portion via the control means, a control means for controlling the actuator based on a target hydraulic pressure corresponding to an operation amount of the brake operating portion, and one hydraulic pressure system, Supply hydraulic pressure measuring means that feeds back a measurement value obtained by measuring the hydraulic pressure supplied to the brake operating unit in the hydraulic pressure system to the control means, and whether or not the brake fluid leaks in the hydraulic pressure system Leak determining means for determining whether the actuator is operated based on the operation amount of the actuator and the measured value of the hydraulic pressure, and the control means is fed from the target hydraulic pressure and the supplied hydraulic pressure measuring means. The vehicle brake system controls the actuator so that the hydraulic pressure generated by the hydraulic pressure generating means approaches the target hydraulic pressure by executing hydraulic pressure feedback control based on the measured value to be And When the leak determination unit determines that the leak has occurred in the hydraulic system including the supply hydraulic pressure measurement unit, the control unit responds to the target hydraulic pressure from the hydraulic pressure feedback control. Switching to target operation amount control for controlling the actuator based on the target operation amount of the actuator.

  In the vehicle brake system according to the present invention, the hydraulic pressure generated by the operation of the actuator provided in the hydraulic pressure generating means is supplied to the brake operating unit via the hydraulic system consisting of two independent systems. Is provided with a supply hydraulic pressure measuring means for measuring the hydraulic pressure supplied to the brake operating unit. In addition, the control means includes a hydraulic pressure feedback control based on a target hydraulic pressure corresponding to an operation amount of the brake operation unit and a measured value of the brake hydraulic pressure fed back from the supply hydraulic pressure measurement unit, and an operation amount of the brake operation unit. Target operation amount control based on the target operation amount of the corresponding actuator can be executed. Then, the control means controls the actuator by switching from the hydraulic pressure feedback control to the target operation amount control when the leak determination means determines that the brake fluid leaks in the hydraulic system provided with the supply hydraulic pressure measurement means. To do. Therefore, even when the supply hydraulic pressure measuring unit cannot accurately measure the brake hydraulic pressure, the vehicle brake system generates a suitable brake hydraulic pressure corresponding to the operation amount of the brake operation unit and generates the brake operation unit. Can supply.

  The target operation amount control is control based on the operation amount of the actuator, and the control means can control the actuator with high accuracy by executing the target operation amount control. However, when the control means executes the target operation amount control, when an error occurs in the hydraulic pressure generated by the hydraulic pressure generation means in accordance with the operation amount of the actuator, the control means absorbs the error and the target liquid amount is controlled. The hydraulic pressure cannot be accurately generated with respect to the pressure. That is, when the control means executes the target operation amount control, the accuracy of the hydraulic pressure generated by the hydraulic pressure generation means is lower than when the control means executes the hydraulic pressure feedback control in which the measured value of the hydraulic pressure is fed back. To do.

  Therefore, the control means of the present invention is configured to switch from the hydraulic pressure feedback control to the target operation amount control only when a leak occurs in the hydraulic pressure system provided with the supply hydraulic pressure measuring means. With this configuration, for example, when a leak occurs in the hydraulic system that does not include the supply hydraulic pressure measuring unit, the control unit can execute the hydraulic pressure feedback control. Therefore, even if a leak occurs in the hydraulic system, if the hydraulic system is not provided with the supply hydraulic pressure measuring unit, the control unit executes the hydraulic pressure feedback control and the hydraulic pressure generated by the hydraulic pressure generating unit The actuator can be controlled without reducing the pressure accuracy. As a result, even when a brake fluid leak occurs, a vehicle brake system that can reduce a decrease in the accuracy of the hydraulic pressure supplied to the brake operating unit can be provided.

  The control means of the present invention switches to the target operation amount control when the leak determination means determines that the leak does not occur in the hydraulic system provided with the supply hydraulic pressure measurement means. And the hydraulic pressure feedback control is executed.

According to the present invention, when there is no leak in the hydraulic system equipped with the supply hydraulic pressure measuring means, the control means Fluid pressure feedback control is executed without switching to the operation amount control to control the fluid pressure generating means.
Therefore, even if a leak occurs in the hydraulic system that does not include the supply hydraulic pressure measuring means, if the leak does not occur in the hydraulic system that includes the supplied hydraulic pressure measurement means, the control means performs hydraulic feedback control. And the hydraulic pressure corresponding to the operation amount of the brake operation unit can be generated with high accuracy.

  Further, the control means according to the present invention is configured so that the target hydraulic pressure is calculated based on a predetermined intermediate hydraulic pressure generated in the hydraulic pressure generating means when the operation amount of the actuator is half of the maximum operation amount. In the range where the target hydraulic pressure is smaller than the intermediate hydraulic pressure, the target hydraulic pressure is correlated with the target operational quantity so that the change amount of the target operating quantity with respect to the change in the target hydraulic pressure is larger than the range where the target hydraulic pressure is higher than the intermediate hydraulic pressure. On the basis of this, the target operation amount corresponding to the target hydraulic pressure is calculated.

According to the present invention, when executing the target operation amount control, the control means generates a hydraulic pressure (predetermined intermediate hydraulic pressure) generated when the operation amount of the actuator that generates the hydraulic pressure in the brake fluid is half of the maximum operation amount. In the range where the target hydraulic pressure is smaller than that, the actuator can be operated rapidly.
The range where the target hydraulic pressure is small corresponds to the first half of the operation of the brake operation unit, so even if the brake fluid leaks and the hydraulic pressure corresponding to the operation amount of the brake operation unit cannot be generated accurately, The actuator can be operated rapidly during the first operation period of the operation unit. Therefore, even in a state where leakage of the brake fluid occurs, the hydraulic pressure supplied to the brake operation unit can be rapidly increased in the first operation period of the brake operation unit, and a suitable braking force can be applied to the vehicle. .

  ADVANTAGE OF THE INVENTION According to this invention, even if it is a case where the leak of brake fluid generate | occur | produces, the brake system for vehicles which can reduce the fall of the precision of the hydraulic pressure supplied to a brake action part can be provided.

It is a schematic structure figure of a brake system for vehicles concerning this embodiment. It is a block diagram which shows control of the actuator by a control means. (A) is a diagram showing the relationship between the brake fluid pressure and the amount of movement of the ball screw shaft when a leak occurs, and (b) is a flowchart of a leak determination procedure in which the control means determines the leak. It is an example of the operation amount setting map showing the relationship between the target fluid pressure of the brake fluid pressure and the target operation amount of the ball screw shaft.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings as appropriate.

  As shown in FIG. 1, the vehicle brake system 10 according to the present embodiment provides a hydraulic pressure (brake hydraulic pressure) corresponding to an input of an operation when a brake operation unit such as a brake pedal 12 is operated by a driver. , A hydraulic pressure generating device (input device 14) for generating brake fluid as hydraulic fluid, and a pedal stroke sensor for measuring an operation amount when the brake pedal 12 is depressed (hereinafter referred to as "brake operation amount"). It is configured to include St and a vehicle behavior stabilization device 18 (hereinafter referred to as VSA (vehicle stability assist) device 18, referred to as VSA; registered trademark) that supports stabilization of the vehicle behavior.

  These input device 14, motor cylinder device 16, and VSA device 18 are connected by, for example, a pipe line (hydraulic pressure path) formed of a pipe material such as a hose or a tube, and a by-wire type brake. As a system, the input device 14 and the motor cylinder device 16 are electrically connected by a harness (not shown).

  Among these, the hydraulic path will be described. The connection port 20a of the input device 14 and the connection point A1 are connected by the first piping tube 22a with reference to the connection point A1 in FIG. 1 (slightly below the center). The output port 24a of the motor cylinder device 16 and the connection point A1 are connected by the second piping tube 22b, and the introduction port 26a of the VSA device 18 and the connection point A1 are connected by the third piping tube 22c.

  With reference to the other connection point A2 in FIG. 1, the other connection port 20b of the input device 14 and the connection point A2 are connected by the fourth piping tube 22d, and the other output port 24b of the motor cylinder device 16 The connection point A2 is connected by the fifth piping tube 22e, and the other introduction port 26b of the VSA device 18 and the connection point A2 are connected by the sixth piping tube 22f.

  The VSA device 18 is provided with a plurality of outlet ports 28a to 28d. The first outlet port 28a is connected to the brake operating portion (wheel cylinder 32FR) of the disc brake mechanism 30a provided on the right front wheel WFR by the seventh piping tube 22g. The second outlet port 28b is connected to a brake operating portion (wheel cylinder 32RL) of the disc brake mechanism 30b provided on the left rear wheel WRL by an eighth piping tube 22h. The third outlet port 28c is connected to the brake operating portion (wheel cylinder 32RR) of the disc brake mechanism 30c provided on the right rear wheel WRR by the ninth piping tube 22i. The fourth outlet port 28d is connected to a brake operating portion (wheel cylinder 32FL) of the disc brake mechanism 30d provided on the left front wheel WFL by a tenth piping tube 22j.

In this case, the brake fluid is supplied to the wheel cylinders 32FR, 32RL, 32RR, 32FL of the disc brake mechanisms 30a-30d by the piping tubes 22g-22j connected to the outlet ports 28a-28d, and the wheel cylinders 32FR, 32FR, As the brake fluid pressure in 32RL, 32RR, and 32FL increases, each wheel cylinder 32FR, 32RL, 32RR, and 32FL is operated, and the corresponding wheel (right front wheel WFR, left rear wheel WRL, right rear wheel WRR, left front wheel). WFL) increases the frictional force, and braking force is applied.
That is, in the vehicle brake system 10 of the present embodiment, the brake fluid pressure generated by the motor cylinder device 16 is supplied to the wheel cylinders 32FR, 32RL, 32RR, and 32FL (brake operating portions), and each wheel (the right front wheel). The braking force is applied to the WFR, the left rear wheel WRL, the right rear wheel WRR, and the left front wheel WFL.

  The right front wheel WFR, the left rear wheel WRL, the right rear wheel WRR, and the left front wheel WFL are provided with wheel speed sensors 35a, 35b, 35c, and 35d, respectively, for detecting the wheel speed, and the wheel speed sensors 35a and 35b are provided. , 35c, and 35d measure the wheel speed of each wheel and are input to the control means 150.

  The input device 14 includes a tandem master cylinder 34 that can generate hydraulic pressure in the brake fluid by operating the brake pedal 12 by the driver, and a reservoir (first reservoir 36) attached to the master cylinder 34. In the cylinder tube 38 of the master cylinder 34, two pistons (secondary piston 40a and primary piston 40b) spaced apart by a predetermined distance along the axial direction of the cylinder tube 38 are slidably disposed. The secondary piston 40 a is disposed close to the brake pedal 12 and is connected to the brake pedal 12 via the push rod 42. Further, the primary piston 40b is arranged farther from the brake pedal 12 than the secondary piston 40a.

  Further, on the inner wall of the cylinder tube 38, a pair of ring-shaped cup seals 44Pa and 44Pb slidably contacting the outer periphery of the primary piston 40b, and a pair of ring-shaped cup seals 44Sa and 44Sb slidably contacting the outer periphery of the secondary piston 40a. Is installed. Further, a spring member 50a is disposed between the secondary piston 40a and the primary piston 40b, and another spring member 50b is disposed between the primary piston 40b and the side end portion 38a on the closed end side of the cylinder tube 38. Established.

A guide rod 48b extends from the side end 38a of the cylinder tube 38 along the sliding direction of the primary piston 40b, and the primary piston 40b slides while being guided by the guide rod 48b.
A guide rod 48a extends from the end of the primary piston 40b on the secondary piston 40a side along the sliding direction of the secondary piston 40a, and the secondary piston 40a slides while being guided by the guide rod 48a.
The secondary piston 40a and the primary piston 40b are connected by a guide rod 48a and arranged in series. Details of the guide rods 48a and 48b will be described later.

The cylinder tube 38 of the master cylinder 34 has two supply ports (second supply port 46a and first supply port 46b), two relief ports (second relief port 52a and first relief port 52b), Two output ports 54a and 54b are provided. In this case, the second supply port 46a, the first supply port 46b, the second relief port 52a, and the first relief port 52b are provided so as to join and communicate with a reservoir chamber (not shown) in the first reservoir 36, respectively.
Further, the pair of cup seals 44Sa and 44Sb that are in sliding contact with the outer periphery of the secondary piston 40a are disposed with the second relief port 52a interposed in the sliding direction of the secondary piston 40a. Further, the pair of cup seals 44Pa and 44Pb slidably in contact with the outer periphery of the primary piston 40b is disposed with the first relief port 52b interposed in the sliding direction of the primary piston 40b.

Further, in the cylinder tube 38 of the master cylinder 34, a second pressure chamber 56a and a first pressure chamber 56b that generate a hydraulic pressure corresponding to the depression force that the driver steps on the brake pedal 12 are provided. The second pressure chamber 56a is provided so as to communicate with the connection port 20a via the second hydraulic pressure path 58a, and the first pressure chamber 56b communicates with the other connection port 20b via the first hydraulic pressure path 58b. To be provided.
A space between the first pressure chamber 56b and the second pressure chamber 56a is liquid-tightly sealed by a pair of cup seals 44Sa and 44Sb. Further, the brake pedal 12 side of the second pressure chamber 56a is liquid-tightly sealed by a pair of cup seals 44Pa and 44Pb.

The first pressure chamber 56b is configured to generate a hydraulic pressure corresponding to the displacement of the primary piston 40b, and the second pressure chamber 56a is configured to generate a hydraulic pressure corresponding to the displacement of the secondary piston 40a. .
The secondary piston 40 a is connected to the brake pedal 12 via the push rod 42 and is displaced in the cylinder tube 38 with the operation of the brake pedal 12. Further, the primary piston 40b is displaced by the hydraulic pressure generated in the second pressure chamber 56a by the displacement of the secondary piston 40a. That is, the primary piston 40b is displaced in response to the secondary piston 40a.

  Between the master cylinder 34 and the connection port 20a, a pressure sensor Pm is disposed on the upstream side of the second hydraulic pressure path 58a, and a normally open type is provided on the downstream side of the second hydraulic pressure path 58a. A second shut-off valve 60a composed of a (normally open) solenoid valve is provided. The pressure sensor Pm measures the hydraulic pressure upstream of the second shutoff valve 60a on the master cylinder 34 side on the second hydraulic pressure path 58a.

  Between the master cylinder 34 and the other connection port 20b, on the upstream side of the first hydraulic pressure path 58b, a first shutoff valve 60b composed of a normally open type (normally open type) solenoid valve is provided. A pressure sensor Pp is provided on the downstream side of the first hydraulic pressure path 58b as supply hydraulic pressure measuring means for measuring the hydraulic pressure (brake hydraulic pressure) supplied to the wheel cylinders 32FR, 32RL, 32RR, 32FL. This pressure sensor Pp measures the hydraulic pressure downstream of the wheel cylinders 32FR, 32RL, 32RR, 32FL from the first shutoff valve 60b on the first hydraulic pressure path 58b.

  The normal open in the second shut-off valve 60a and the first shut-off valve 60b is a valve configured such that the normal position (the position of the valve body when not energized) is in the open position (normally open). Say. In FIG. 1, the second shut-off valve 60 a and the first shut-off valve 60 b respectively show valve closed states in which solenoids are energized and valve bodies (not shown) are activated.

  A branch hydraulic pressure path 58c branched from the first hydraulic pressure path 58b is provided in the first hydraulic pressure path 58b between the master cylinder 34 and the first shutoff valve 60b, and the branched hydraulic pressure path 58c includes A third shut-off valve 62 composed of a normally closed type (normally closed type) solenoid valve and a stroke simulator 64 are connected in series. The normal close in the third shut-off valve 62 refers to a valve configured such that the normal position (the position of the valve body when not energized) is in the closed position (normally closed). In FIG. 1, the third shut-off valve 62 shows a valve open state in which a solenoid (not shown) is actuated by energizing a solenoid.

  The stroke simulator 64 is a device that gives a stroke and reaction force to the depression operation of the brake pedal 12 during the by-wire control, and makes the driver feel as if braking force is generated by the depression force. The first hydraulic pressure path 58b is disposed closer to the master cylinder 34 than the first shutoff valve 60b. The stroke simulator 64 is provided with a hydraulic pressure chamber 65 communicating with the branch hydraulic pressure path 58c, and brake fluid (brake fluid) led out from the first pressure chamber 56b of the master cylinder 34 via the hydraulic pressure chamber 65 is provided. ) Is provided so as to be absorbable.

The stroke simulator 64 is a simulator that is urged by a first return spring 66a having a high spring constant, a second return spring 66b having a low spring constant, and the first and second return springs 66a and 66b arranged in series. A piston 68, the pedal reaction force of the brake pedal 12 is set to be low when the brake pedal 12 is depressed, and the pedal reaction force of the brake pedal 12 is set high when the brake pedal 12 is depressed late. It is provided to be equivalent to the pedal feeling when the stepping operation is performed.
That is, the stroke simulator 64 is configured to generate a reaction force corresponding to the hydraulic pressure of the brake fluid derived from the first pressure chamber 56 b and to apply the reaction force to the brake pedal 12 via the master cylinder 34. .

  The hydraulic pressure path is roughly divided into a second hydraulic pressure system 70a that connects the second pressure chamber 56a of the master cylinder 34 and the plurality of wheel cylinders 32FR, 32RL, a first pressure chamber 56b of the master cylinder 34, and a plurality of pressure paths. The first hydraulic system 70b is connected to the wheel cylinders 32RR and 32FL. The first hydraulic system 70b and the second hydraulic system 70a are independent hydraulic systems, and are configured such that the brake hydraulic pressure in one hydraulic system is not affected by the brake hydraulic pressure in the other hydraulic system. Has been. In other words, the brake hydraulic pressure generated in the motor cylinder device 16 is supplied to the brake operation unit (wheel cylinder 32FR, wheel brake) via two independent hydraulic systems (first hydraulic system 70b and second hydraulic system 70a). 32RL, 32RR, 32FL).

  The second hydraulic system 70a includes a second hydraulic path 58a that connects the output port 54a of the master cylinder 34 (cylinder tube 38) and the connection port 20a in the input device 14, and the connection port 20a of the input device 14 and the motor cylinder. Piping tubes 22a and 22b connecting the output port 24a of the device 16, piping tubes 22b and 22c connecting the output port 24a of the motor cylinder device 16 and the introduction port 26a of the VSA device 18, and a lead-out port of the VSA device 18 28a, 28b and pipe tubes 22g, 22h connecting the wheel cylinders 32FR, 32RL, respectively.

  The first hydraulic system 70b includes a first hydraulic path 58b that connects the output port 54b of the master cylinder 34 (cylinder tube 38) in the input device 14 and the other connection port 20b, and another connection port of the input device 14. Piping tubes 22d and 22e for connecting 20b and the output port 24b of the motor cylinder device 16, piping tubes 22e and 22f for connecting the output port 24b of the motor cylinder device 16 and the introduction port 26b of the VSA device 18, and a VSA device 18 lead-out ports 28c, 28d and pipe tubes 22i, 22j connecting the wheel cylinders 32RR, 32FL, respectively.

  The motor cylinder device 16 includes an electric motor (electric motor 72), an actuator mechanism 74, and a cylinder mechanism 76 biased by the actuator mechanism 74.

The actuator mechanism 74 is provided on the output shaft 72 b side of the electric motor 72, and a gear mechanism (deceleration mechanism) 78 that transmits a rotational driving force of the electric motor 72 through meshing of a plurality of gears. The ball screw structure 80 includes a ball screw shaft 80a and a ball 80b that move forward and backward along the axial direction when the rotational driving force is transmitted.
In the present embodiment, the ball screw structure 80 is housed in the mechanism housing portion 173 a of the actuator housing 172 together with the gear mechanism 78.

The cylinder mechanism 76 includes a substantially cylindrical cylinder body 82 and a second reservoir 84 attached to the cylinder body 82. The second reservoir 84 is connected to the first reservoir 36 attached to the master cylinder 34 of the input device 14 by a piping tube 86, and the brake fluid stored in the first reservoir 36 is passed through the piping tube 86 to the second reservoir 84. 84 is provided so as to be supplied in the inside. Note that the piping tube 86 may be provided with a tank for storing brake fluid.
An open end (open end) of the cylinder body 82 having a substantially cylindrical shape is fitted into an actuator housing 172 including a housing body 172F and a housing cover 172R, and the cylinder body 82 and the actuator housing 172 are coupled to each other. A cylinder device 16 is configured.

In the cylinder body 82, a second slave piston 88a and a first slave piston 88b that are spaced apart from each other by a predetermined distance along the axial direction of the cylinder body 82 are slidably disposed. The second slave piston 88a is disposed in the vicinity of the ball screw structure 80, contacts with one end of the ball screw shaft 80a, and moves (displaces) integrally with the ball screw shaft 80a in the direction of the arrow X1 or X2. To do. The first slave piston 88b is arranged farther from the ball screw structure 80 side than the second slave piston 88a.
In the present embodiment, the actuator includes the electric motor 72 and the actuator mechanism 74 (such as the ball screw shaft 80a), and the operation amount (displacement) of the ball screw shaft 80a is the operation amount of the actuator.

Further, the electric motor 72 in the present embodiment is configured to be covered with a motor casing 72a formed separately from the cylinder body 82, and the output shaft 72b slides between the second slave piston 88a and the first slave piston 88b. It arrange | positions so that it may become substantially parallel to (axial direction).
The rotational drive of the output shaft 72b is transmitted to the ball screw structure 80 via the gear mechanism 78.

  The gear mechanism 78 is, for example, a third gear 78a that is attached to the output shaft 72b of the electric motor 72 and a ball 80b that moves the ball screw shaft 80a back and forth in the axial direction about the axis of the ball screw shaft 80a. The gear 78c is composed of three gears, a second gear 78b that transmits the rotation of the first gear 78a to the third gear 78c, and the third gear 78c rotates around the axis of the ball screw shaft 80a.

  The actuator mechanism 74 in the present embodiment converts the rotational driving force of the output shaft 72b of the electric motor 72 into the advancing / retreating driving force (linear driving force) of the ball screw shaft 80a by the structure described above.

A pair of slave cup seals 90a and 90b are mounted on the outer peripheral surface of the first slave piston 88b via an annular stepped portion. A first back chamber 94b communicating with a reservoir port 92b described later is formed between the pair of slave cup seals 90a and 90b.
A second return spring 96a is disposed between the second and first slave pistons 88a and 88b, and a first return spring 96b is provided between the first slave piston 88b and the side end of the cylinder body 82. Is disposed.

An annular guide piston 90c that seals between the outer peripheral surface of the second slave piston 88a and the mechanism housing portion 173a in a fluid-tight manner and guides the second slave piston 88a so as to be movable in the axial direction. The cylinder body 82 is provided as a seal member behind the second slave piston 88a. It is preferable that a slave cup seal (not shown) is attached to the inner peripheral surface of the guide piston 90c through which the second slave piston 88a penetrates, and the second slave piston 88a and the guide piston 90c are liquid-tightly configured. Further, a slave cup seal 90b is attached to the front outer peripheral surface of the second slave piston 88a via an annular step portion.
With this configuration, the brake fluid filled in the cylinder body 82 is sealed in the cylinder body 82 by the guide piston 90c and does not flow into the actuator housing 172 side.
A second back chamber 94a communicating with a reservoir port 92a described later is formed between the guide piston 90c and the slave cup seal 90b.

  The cylinder body 82 of the cylinder mechanism 76 is provided with two reservoir ports 92a and 92b and two output ports 24a and 24b. In this case, the reservoir port 92a (92b) is provided so as to communicate with a reservoir chamber (not shown) in the second reservoir 84.

  Further, in the cylinder body 82, a second hydraulic pressure chamber 98a for controlling the brake hydraulic pressure output from the output port 24a to the wheel cylinders 32FR, 32RL side, and the other output port 24b to the wheel cylinders 32RR, 32FL side. A first hydraulic pressure chamber 98b for controlling the output brake hydraulic pressure is provided.

According to this configuration, the second back chamber 94a, the first back chamber 94b, the second hydraulic chamber 98a, and the first hydraulic chamber 98b in which the brake fluid is sealed are brake fluid sealing portions in the cylinder body 82. The guide piston 90c, which functions as a seal member, is partitioned liquid-tight (air-tight) from the mechanism housing portion 173a of the actuator housing 172.
Note that the method of attaching the guide piston 90c to the cylinder body 82 is not limited. For example, the guide piston 90c may be attached with a circlip (not shown).

  A regulating means for regulating the maximum stroke (maximum displacement distance) and the minimum stroke (minimum displacement distance) of the second slave piston 88a and the first slave piston 88b between the second slave piston 88a and the first slave piston 88b. 100 is provided. Further, the first slave piston 88b is provided with a stopper pin 102 that restricts the sliding range of the first slave piston 88b and prevents an overreturn to the second slave piston 88a side. At the time of backup braking at 34, when one system fails, the other system is prevented from failing.

  The VSA device 18 is a known one, and a second brake system that controls a second hydraulic system 70a connected to the disc brake mechanisms 30a, 30b (wheel cylinders 32FR, 32RL) of the right front wheel WFR and the left rear wheel WRL. 110a and a first brake system 110b for controlling the first hydraulic system 70b connected to the disc brake mechanisms 30c, 30d (wheel cylinders 32RR, 32FL) of the right rear wheel WRR and the left front wheel WFL. The second brake system 110a is composed of a hydraulic system connected to a disc brake mechanism provided on the left front wheel WFL and the right front wheel WFR, and the first brake system 110b is connected to the right rear wheel WRR and the left rear wheel WRL. A hydraulic system connected to the provided disc brake mechanism may be used. Further, the second brake system 110a includes a hydraulic system connected to a disc brake mechanism provided on the right front wheel WFR and the right rear wheel WRR on one side of the vehicle body, and the first brake system 110b includes the left front wheel WFL on the vehicle body side. And a hydraulic system connected to a disc brake mechanism provided on the left rear wheel WRL.

  Since the second brake system 110a and the first brake system 110b have the same structure, the corresponding parts in the second brake system 110a and the first brake system 110b are assigned the same reference numerals, and The description of the first brake system 110b will be added in parentheses with a focus on the description of the two brake system 110a.

The second brake system 110a (first brake system 110b) has a common pipe line (first common hydraulic pressure path 112 and second common hydraulic pressure path 114) for the wheel cylinders 32FR, 32RL (32RR, 32FL). Have. Among these, the first common hydraulic pressure path 112 is a supply path for supplying brake hydraulic pressure to the wheel cylinders 32FR, 32RL (32RR, 32FL).
The VSA device 18 includes a regulator valve 116 composed of a normally open type solenoid valve disposed between the introduction port 26a (26b) and the first common hydraulic pressure path 112, and the introduction port disposed in parallel with the regulator valve 116. Allow the brake fluid to flow from the 26a (26b) side to the first common hydraulic path 112 side (block the brake fluid from the first common hydraulic path 112 side to the introduction port 26a (26b) side) A first check valve 118; a first in-valve 120 including a normally open type solenoid valve disposed between the first common hydraulic path 112 and the first outlet port 28a (fourth outlet port 28d); The first common hydraulic pressure path 1 is arranged in parallel with the 1-in valve 120 from the first outlet port 28a (fourth outlet port 28d) side. A second check valve 122 that permits the flow of brake fluid to the second side (blocks the flow of brake fluid from the first common hydraulic pressure passage 112 side to the first outlet port 28a (fourth outlet port 28d) side); A second in-valve 124 composed of a normally open solenoid valve disposed between the first common hydraulic pressure path 112 and the second outlet port 28b (third outlet port 28c); and in parallel with the second inlet valve 124. The brake fluid is allowed to flow from the second outlet port 28b (third outlet port 28c) side to the first common hydraulic path 112 side (from the first common hydraulic path 112 side to the second outlet port 28b (second And 3rd check valve 126 for preventing the flow of brake fluid to the 3 outlet port 28c) side.

  The first in-valve 120 and the second in-valve 124 are opening / closing means for opening / closing a pipe line (first common hydraulic pressure path 112) for supplying brake hydraulic pressure to the wheel cylinders 32FR, 32RL, 32RR, 32FL. When the first in-valve 120 is closed, the supply of the brake fluid pressure from the first common fluid pressure path 112 to the wheel cylinders 32FR and 32RL is interrupted. Further, when the second in valve 124 is closed, the supply of the brake hydraulic pressure from the first common hydraulic pressure path 112 to the wheel cylinders 32RR and 32FL is shut off.

  Further, the VSA device 18 includes a first out valve 128 including a normally closed solenoid valve disposed between the first outlet port 28a (fourth outlet port 28d) and the second common hydraulic pressure path 114, The second out valve 130 formed of a normally closed type solenoid valve disposed between the second outlet port 28b (third outlet port 28c) and the second common hydraulic pressure path 114, and connected to the second common hydraulic pressure path 114 Brake fluid from the second common hydraulic pressure path 114 side to the first common hydraulic pressure path 112 side disposed between the reservoir device 132 and the first common hydraulic pressure path 112 and the second common hydraulic pressure path 114 The fourth check valve 134 (which inhibits the flow of brake fluid from the first common hydraulic pressure path 112 side to the second common hydraulic pressure path 114 side) and the fourth check valve 34 and a first common hydraulic pressure path 112, and a pump 136 that supplies brake fluid from the second common hydraulic pressure path 114 side to the first common hydraulic pressure path 112 side, and provided before and after the pump 136. Suction valve 138 and discharge valve 140, a motor M for driving the pump 136, a normally closed type solenoid valve disposed between the second common hydraulic pressure path 114 and the introduction port 26a (26b). And a valve 142.

The measurement signals measured by the pressure sensors Pm and Pp are input to the control means 150. The VSA device 18 can also control ABS (anti-lock brake system) in addition to VSA control.
Further, instead of the VSA device 18, a configuration in which an ABS device having only an ABS function is connected may be employed.
The vehicle brake system 10 according to the present embodiment is basically configured as described above. Next, the operation and effect will be described.

  When the vehicle brake system 10 is functioning normally, the second shut-off valve 60a and the first shut-off valve 60b, which are normally open type solenoid valves, are energized to be closed, and the first shut-off valve, which is composed of a normally close type solenoid valve. The three shut-off valve 62 is excited and the valve is opened. Accordingly, since the second hydraulic system 70a and the first hydraulic system 70b are shut off by the second shut-off valve 60a and the first shut-off valve 60b, the hydraulic pressure generated in the master cylinder 34 of the input device 14 is disc brake mechanism. It is not transmitted to the wheel cylinders 32FR, 32RL, 32RR, 32FL of 30a to 30d.

  At this time, the hydraulic pressure generated in the first pressure chamber 56b of the master cylinder 34 is transmitted to the hydraulic pressure chamber 65 of the stroke simulator 64 via the branch hydraulic pressure path 58c and the third shut-off valve 62 in the valve open state. The The simulator piston 68 is displaced against the spring force of the first and second return springs 66a and 66b by the hydraulic pressure supplied to the hydraulic pressure chamber 65, so that the stroke of the brake pedal 12 is allowed, and the simulation is performed. A typical pedal reaction force is generated and applied to the brake pedal 12. As a result, it is possible to obtain a brake feeling that is comfortable for the driver.

  In such a system state, the control means 150 determines that the braking is being performed when detecting the depression of the brake pedal 12 by the driver, drives the electric motor 72 of the motor cylinder device 16 to energize the actuator mechanism 74, and 2 The second slave piston 88a and the first slave piston 88b are displaced in the direction of the arrow X1 in FIG. 1 against the spring force of the return spring 96a and the first return spring 96b. Due to the displacement of the second slave piston 88a and the first slave piston 88b, the brake fluid in the second fluid pressure chamber 98a and the first fluid pressure chamber 98b is pressurized so as to be balanced to generate a desired brake fluid pressure. As described above, the motor cylinder device 16 of the present embodiment serves as a hydraulic pressure generating unit that pressurizes the brake fluid by the operation of the electric motor 72 and the actuator mechanism 74 (the operation of the actuator) to generate the hydraulic pressure (brake hydraulic pressure). Function.

  Specifically, the control means 150 calculates the depression operation amount (brake operation amount) of the brake pedal 12 according to the measured value of the pedal stroke sensor St, and considers the regenerative braking force based on the brake operation amount. The target brake fluid pressure is set in step S1, and the set brake fluid pressure is generated in the motor cylinder device 16.

The control means 150 of the present embodiment includes, for example, a microcomputer and peripheral devices that are configured by a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc., not shown. The control means 150 is configured to control the vehicle brake system 10 by executing a program stored in the ROM in advance by the CPU.
Moreover, the electrical signal in this embodiment is a control signal for controlling the electric power which drives the electric motor 72, and the electric motor 72, for example.

  Further, the operation amount measuring means for measuring the depression amount (brake operation amount) of the brake pedal 12 is not limited to the pedal stroke sensor St, and any sensor that can measure the brake operation amount may be used. For example, the operation amount measuring means may be a pressure sensor Pm, and the hydraulic pressure measured by the pressure sensor Pm may be converted into a brake operation amount, or the brake operation amount may be measured by a pedal force sensor (not shown). Also good.

  The brake hydraulic pressure in the second hydraulic pressure chamber 98a and the first hydraulic pressure chamber 98b in the motor cylinder device 16 is supplied to the disc brake mechanism 30a via the first and second in-valves 120 and 124 in the valve open state of the VSA device 18. To 30d wheel cylinders 32FR, 32RL, 32RR, 32FL, and when the wheel cylinders 32FR, 32RL, 32RR, 32FL are operated, each wheel (right front wheel WFR, left rear wheel WRL, right rear wheel WRR, left front wheel) WFL) is given a desired braking force.

  In other words, in the vehicle brake system 10 according to the present embodiment, the motor cylinder device 16 that functions as a power hydraulic pressure source (hydraulic pressure generating means), the control means 150 that performs by-wire control, and the like can be operated normally. The communication between the master cylinder 34 that generates hydraulic pressure when the driver depresses the brake pedal 12 and the disc brake mechanisms 30a to 30d (wheel cylinders 32FR, 32RL, 32RR, and 32FL) that brake each wheel is connected to the second cutoff valve 60a. In addition, a so-called brake-by-wire brake system in which the disc brake mechanisms 30a to 30d are operated with the brake fluid pressure generated by the motor cylinder device 16 in the state where the first shut-off valve 60b is shut off is activated.

  On the other hand, when the motor cylinder device 16 or the like becomes inoperable, the liquid generated in the master cylinder 34 with the second shut-off valve 60a and the first shut-off valve 60b opened and the third shut-off valve 62 closed respectively. The pressure is transmitted as brake fluid pressure to the disc brake mechanisms 30a to 30d (wheel cylinders 32FR, 32RL, 32RR, 32FL), and the disc brake mechanisms 30a to 30d (wheel cylinders 32FR, 32RL, 32RR, 32FL) are operated. The so-called traditional hydraulic brake system becomes active.

The vehicle brake system 10 of this embodiment is configured as shown in FIG. The brake hydraulic pressure supplied to the wheel cylinders 32FR, 32RL, 32RR, and 32FL (brake operating unit) is configured to be measured by a pressure sensor Pp disposed in the first hydraulic pressure path 58b.
Further, the control means 150 calculates a target value of the brake fluid pressure corresponding to the brake operation amount (the brake fluid pressure requested by the driver, which is the target fluid pressure in this embodiment). Furthermore, the control means 150 calculates the brake hydraulic pressure (measured value) supplied to the wheel cylinders 32FR, 32RL, 32RR, 32FL based on the measurement signal input (feedback) from the pressure sensor Pp. Then, the control means 150 controls (feedback control) the motor cylinder device 16 so that the brake fluid pressure supplied to the wheel cylinders 32FR, 32RL, 32RR, 32FL (brake operation unit) approaches the target fluid pressure.

  FIG. 2 is a block diagram showing the control of the actuator (electric motor) by the control means, and FIG. 3A shows the brake fluid pressure and the operation amount of the ball screw shaft (hereinafter referred to as “ACTst”) when a leak occurs. (B) of FIG. 3 is a flowchart of a leak determination procedure in which the control means determines a leak. FIG. 4 is an example of an operation amount setting map showing the relationship between the target hydraulic pressure of the brake fluid pressure and the target operation amount of the ball screw shaft. The vertical axis represents the target operation amount of the ball screw shaft 80a, and the horizontal axis represents the brake. The target hydraulic pressure according to the operation amount is shown. Also, PxMax on the horizontal axis is the maximum value of the brake fluid pressure in the vehicle brake system 10. In addition, the dashed-dotted line and the dashed-two dotted line of FIG. 4 have shown the form of the operation amount setting map which is not employ | adopted by this embodiment as a comparative example.

For example, in a state where no brake fluid leaks (leakage) occurs in either the first hydraulic system 70b or the second hydraulic system 70a (normal state in the present embodiment), the control means 150 is shown in FIG. As shown, the target hydraulic pressure corresponding to the brake operation amount is calculated based on the measurement signal input from the pedal stroke sensor St. For example, the control unit 150 calculates a brake operation amount based on a measurement signal input from the pedal stroke sensor St. Further, the control unit 150 calculates a target hydraulic pressure corresponding to the brake operation amount based on a map (hydraulic pressure setting map MP0) for converting the brake operation amount into the target hydraulic pressure.
Note that the hydraulic pressure setting map MP0 for converting the brake operation amount into the target hydraulic pressure may be set in advance by experimental measurement, simulation, or the like.
Alternatively, the control unit 150 may calculate the target hydraulic pressure using a function indicating the target hydraulic pressure corresponding to the brake operation amount.

  Further, the control means 150 (see FIG. 1) generates the first hydraulic system 70b when the motor cylinder device 16 (see FIG. 1) is actually generated based on the measurement signal input from the pressure sensor Pp (see FIG. 1). The brake fluid pressure (measured value) supplied to (see FIG. 1) is calculated. Then, the control means 150 calculates the deviation between the calculated target hydraulic pressure and the actual brake hydraulic pressure (measured value), and controls the motor cylinder device 16 (actuator mechanism 74) so as to bring this deviation close to zero. A brake fluid pressure equal to the fluid pressure is generated. Thus, the feedback control of the motor cylinder device 16 based on the measurement signal (measured value) fed back from the pressure sensor Pp is referred to as “hydraulic pressure feedback control”. That is, the control means 150 of the present embodiment controls the motor cylinder device 16 by executing hydraulic pressure feedback control.

However, if a leak occurs in the first hydraulic system 70b (see FIG. 1) including the first hydraulic path 58b (see FIG. 1) in which the pressure sensor Pp (see FIG. 1) is disposed, the first hydraulic system The brake fluid pressure at 70b decreases. Therefore, the pressure sensor Pp cannot accurately measure the brake hydraulic pressure supplied from the motor cylinder device 16 (see FIG. 1) to the first hydraulic system 70b.
Therefore, when a leak occurs in the first hydraulic system 70b, the control unit 150 cannot perform the hydraulic pressure feedback control based on the measurement value measured by the pressure sensor Pp.

Therefore, in the vehicle brake system 10 of the present embodiment shown in FIG. 1, the control means 150 stops the hydraulic pressure feedback control when a leak occurs in the first hydraulic system 70b or the second hydraulic system 70a. Configured.
Therefore, the vehicle brake system 10 includes a leak determination unit that determines whether or not a brake fluid leak has occurred in the first hydraulic system 70b and the second hydraulic system 70a.
In the present embodiment, the control unit 150 causes the first hydraulic system 70b and the second hydraulic system 70a to generate a leak based on the operation amount of the ball screw shaft 80a and the measurement signal input from the pressure sensor Pp. It is configured so that it can be determined.

Then, when it is determined that a leak has occurred in the first hydraulic system 70b, the control unit 150, as shown in FIG. 2, based on the measurement signal input from the pedal stroke sensor St, the target fluid for the brake operation amount. Calculate the pressure. Further, the control means 150 refers to the preset operation amount setting map MP1 based on the calculated target fluid pressure, and the target motion amount of the ball screw shaft 80a (see FIG. 1) corresponding to the target fluid pressure. (Target actuator operation amount) is determined. Details of the operation amount setting map MP1 will be described later.
Further, the control unit 150 calculates a deviation between the actual movement amount (actual movement amount) of the ball screw shaft 80a and the determined target movement amount. Then, the control unit 150 controls (or displaces) the ball screw shaft 80a by a target operation amount by controlling the motor cylinder device 16 (electric motor 72) so that the deviation approaches zero. The control means 150 may be configured to detect the actual operation amount of the ball screw shaft 80a based on the rotation angle of the electric motor 72 of the motor cylinder device 16. Or the structure provided with the sensor (not shown) which measures the operation amount of the ball screw shaft 80a may be sufficient.

  The control of the motor cylinder device 16 (see FIG. 1) based on the target operation amount of the ball screw shaft 80a (see FIG. 1) corresponding to the target hydraulic pressure is referred to as “target operation amount control”. That is, when the controller 150 (see FIG. 1) of the present embodiment determines that a leak has occurred in the first hydraulic system 70b (see FIG. 1), the control means 150 (see FIG. 1) switches from the hydraulic feedback control to the target operation amount control. The operation amount control is executed to control the motor cylinder device 16.

  However, if there is a leak in the first hydraulic system 70b (see FIG. 1) or the second hydraulic system 70a (see FIG. 1), the control means 150 (see FIG. 1) controls the motor cylinder with the target operation amount control. When the device 16 (see FIG. 1) is controlled, the brake feel may be lowered.

For example, when a leak occurs in the first hydraulic system 70b shown in FIG. 1, the motor cylinder device 16 supplies the brake hydraulic pressure to the first hydraulic system 70b from the first hydraulic chamber 98b to the VSA device 18. Brake fluid leaks. The brake fluid pressure generated in the first fluid pressure chamber 98b is smaller than the brake fluid pressure generated in the second fluid pressure chamber 98a.
Therefore, in the first slave piston 88b and the second slave piston 88a, the first slave piston 88b disposed in the first hydraulic pressure chamber 98b has a smaller resistance to displacement. For this reason, the first slave piston 88b is more easily displaced than the second slave piston 88a.

  For this reason, when the ball screw shaft 80a is operated (displaced), the first hydraulic chamber 98b is compressed by the first slave piston 88b before the second hydraulic chamber 98a and braked from the first hydraulic chamber 98b. The liquid is supplied to the first brake system 110 b of the VSA device 18. However, since a leak occurs in the first hydraulic system 70b, the brake hydraulic pressure in the first brake system 110b does not increase and no braking force is generated.

  Thereafter, when the second slave piston 88a is displaced after the first slave piston 88b is displaced and comes into contact with the end of the cylinder body 82, the second hydraulic pressure chamber 98a is compressed and the brake fluid is discharged from the second hydraulic pressure chamber 98a. Is supplied to the second brake system 110 a of the VSA device 18. If there is no leak in the second hydraulic system 70a, the brake hydraulic pressure supplied to the second brake system 110a increases and braking force is applied to the disc brake mechanisms 30a, 30b disposed in the second brake system 110a. Occurs.

That is, when a leak occurs in the first hydraulic system 70b, the vehicle brake system 10 is controlled between the time when the motor cylinder device 16 is driven and the time when the first slave piston 88b comes into contact with the end of the cylinder body 82. Power cannot be generated.
Therefore, the brake fluid pressure corresponding to the operation amount of the ball screw shaft 80a is not generated in the motor cylinder device 16, and a time lag occurs after the driver depresses the brake pedal 12 until the braking force is generated, and the brake feel is reduced. descend.

On the other hand, when a leak occurs in the second hydraulic system 70a, the brake fluid supplied to the VSA device 18 leaks from the second hydraulic chamber 98a that supplies the brake hydraulic pressure to the second hydraulic system 70a in the motor cylinder device 16. To do. The brake fluid pressure generated in the second fluid pressure chamber 98a is smaller than the brake fluid pressure generated in the first fluid pressure chamber 98b.
Therefore, in the first slave piston 88b and the second slave piston 88a, the second slave piston 88a disposed in the second hydraulic pressure chamber 98a has a smaller resistance to displacement. For this reason, the second slave piston 88a is more easily displaced than the first slave piston 88b.

  Therefore, when the ball screw shaft 80a operates (displaces), the second hydraulic pressure chamber 98a is compressed by the second slave piston 88a before the first hydraulic pressure chamber 98b, and the brake fluid is discharged from the second hydraulic pressure chamber 98a. Is supplied to the second brake system 110 a of the VSA device 18. However, since a leak occurs in the second hydraulic system 70a, the brake hydraulic pressure in the second brake system 110a does not increase and no braking force is generated.

  Thereafter, when the first slave piston 88b is displaced after the second slave piston 88a is displaced and the regulating means 100 contacts the first slave piston 88b, the first hydraulic chamber 98b is compressed and the first hydraulic chamber 98b is compressed. The brake fluid is supplied to the first brake system 110 b of the VSA device 18. If there is no leak in the first hydraulic system 70b, the brake hydraulic pressure supplied to the first brake system 110b increases and braking force is applied to the disc brake mechanisms 30c and 30d disposed in the first brake system 110b. Occurs.

That is, when a leak occurs in the second hydraulic system 70a, the vehicle brake system 10 generates a braking force between the time when the motor cylinder device 16 is driven and the time when the restricting means 100 contacts the first slave piston 88b. It becomes impossible.
Therefore, even when a leak occurs in the second hydraulic pressure system 70a, the brake hydraulic pressure corresponding to the operation amount of the ball screw shaft 80a (see FIG. 1) does not occur in the motor cylinder device 16 (see FIG. 1), and the driver When the brake pedal 12 is depressed, a time lag occurs until the braking force is generated, and the brake feel is lowered.

Therefore, the vehicle brake system 10 of the present embodiment shown in FIG. 1 reduces the decrease in brake feel when a brake fluid leak occurs in the first hydraulic system 70b and the second hydraulic system 70a. Operate. Specifically, the control unit 150 performs target operation amount control when a leak occurs in the first hydraulic system 70b, and leaks in the first hydraulic system 70b when a leak occurs in the second hydraulic system 70a. If it does not occur, the hydraulic pressure feedback control is executed.
Therefore, the control means 150 (leak determination means) is configured to be able to determine which of the first hydraulic system 70b and the second hydraulic system 70a is leaking.
For example, the control means 150 determines the occurrence of a leak in the first hydraulic system 70b and the second hydraulic system 70a based on the characteristics shown in FIG.

When a leak occurs in the first hydraulic system 70b (see FIG. 1) in which the pressure sensor Pp (see FIG. 1) is disposed, as shown by a solid line in FIG. 3 (a), the ball screw shaft 80a (see FIG. 1). The measured value (brake hydraulic pressure) of the pressure sensor Pp does not increase even if the operation amount ACTst of (see) increases.
On the other hand, when a leak occurs in the second hydraulic system 70a (see FIG. 1) where the pressure sensor Pp is not disposed, the operation of the ball screw shaft 80a (see FIG. 1) as shown by the broken line in FIG. The measured value of the pressure sensor Pp increases when the amount ACTst exceeds a predetermined threshold value (first threshold value SCth1). As described above, when a leak occurs in the second hydraulic system 70a, the first hydraulic system after the regulating means 100 (see FIG. 1) comes into contact with the first slave piston 88b (see FIG. 1). This is because the brake fluid is supplied to 70b and the brake fluid pressure in the first hydraulic system 70b increases.

That is, in the characteristic shown in FIG. 3A, the first threshold value at which the measured value of the pressure sensor Pp (see FIG. 1) starts increasing when a leak occurs in the second hydraulic system 70a (see FIG. 1). SCth1 is the amount of movement ACTst of the ball screw shaft 80a from when the ball screw shaft 80a (see FIG. 1) starts to operate until the regulating means 100 (see FIG. 1) contacts the first slave piston 88b (see FIG. 1). It corresponds to.
Therefore, the first threshold value SCth1 is set as a design value based on the moving distance of the restricting means 100 until it comes into contact with the first slave piston 88b.

Further, the control means 150 (see FIG. 1) indicates that the measured value of the pressure sensor Pp (see FIG. 1) when the operation amount ACTst of the ball screw shaft 80a (see FIG. 1) is larger than the first threshold value SCth1 is shown in FIG. Depending on whether or not it is in the area (leakage determination area Lk1) indicated by diagonal lines in (a) of FIG. 1, there is a leak in the first hydraulic system 70b (see FIG. 1) or the second hydraulic system 70a (see FIG. 1). Determine whether it has occurred.
For example, even when a leak occurs in the first hydraulic system 70b, the leak determination region Lk1 is set to a region lower than the upper limit (Pmax) of the measurement value of the pressure sensor Pp that occurs as an error, for example. Such a leak determination region Lk1 is a characteristic value set by the configuration of the vehicle brake system 10 (see FIG. 1) and the accuracy of the pressure sensor Pp, and may be a value set in advance by experimental measurement or simulation. .
The leak determination region Lk1 is set, for example, as a region where the operation amount ACTst of the ball screw shaft 80a is not less than the first threshold value SCth1 and not more than “1 MPa”.

  Then, the control means 150 (see FIG. 1) measures the measured value of the pressure sensor Pp (see FIG. 1) when the operation amount ACTst of the ball screw shaft 80a (see FIG. 1) is larger than the first threshold value SCth1 (ACTst> SCth1). Is smaller than the upper limit value Pmax (in the leak determination region Lk1), a leak occurs in either the first hydraulic system 70b (see FIG. 1) or the second hydraulic system 70a (see FIG. 1). It is determined that

  Further, the control means 150 (see FIG. 1) of the present embodiment is based on a second threshold value SCth2 (SCth2> SCth1) in which the operation amount ACTst of the ball screw shaft 80a (see FIG. 1) is set larger than the first threshold value SCth1. Is larger (ACTst> SCth2) and the measured value of the pressure sensor Pp (see FIG. 1) is smaller than the upper limit value Pmax (if it is within the leak determination region Lk1), the first pressure sensor Pp is disposed. It is determined that a leak has occurred in the hydraulic system 70b. Note that the control unit 150 determines that the pressure sensor Pp if the measured value of the pressure sensor Pp is equal to or greater than the upper limit Pmax when the operation amount ACTst of the ball screw shaft 80a is greater than the second threshold value SCth2 (if it is outside the leak determination region). It is determined that a leak has occurred in the second hydraulic system 70a where no Pp is disposed.

  The second threshold value SCth2 for the controller 150 (see FIG. 1) to determine a leak in the second hydraulic system 70a (see FIG. 1) is the first hydraulic pressure in a state where a leak has occurred in the second hydraulic system 70a. A value determined based on an increase in brake hydraulic pressure (an increase in measured value of the pressure sensor Pp) in the system 70b (see FIG. 1) may be set in advance by experimental measurement or simulation.

Referring to FIG. 3B, the control means 150 (see FIG. 1) of the present embodiment causes the leakage of the first hydraulic system 70b (see FIG. 1) and the second hydraulic system 70a (see FIG. 1). Will be described (leak determination procedure) (see FIG. 1 as appropriate).
Note that the control unit 150 determines a leak in the first hydraulic system 70b and the second hydraulic system 70a by executing a leak determination procedure when the brake pedal 12 is depressed, for example.

  When the control unit 150 starts the leak determination procedure, the operation amount ACTst of the ball screw shaft 80a is compared with the first threshold value SCth1 (step S1). If the operation amount ACTst of the ball screw shaft 80a is equal to or less than the first threshold value SCth1 (step S1 → No), the control unit 150 returns the procedure to step S1. On the other hand, if the operation amount ACTst of the ball screw shaft 80a is larger than the first threshold value SCth1 (step S1 → Yes), the control means 150 advances the procedure to step S2.

When the measured value of the brake fluid pressure measured by the pressure sensor Pp is larger than the predetermined upper limit value Pmax (step S2 → Yes), that is, when the measured value of the brake fluid pressure is outside the leak determination region Lk1, It is determined that there is no leak in the first hydraulic system 70b and the second hydraulic system 70a (step S3).
Further, when the measured value measured by the pressure sensor Pp is less than or equal to the predetermined upper limit value Pmax (step S2 → No), that is, when the measured value of the brake fluid pressure is within the leak determination region Lk1, Wait until the movement amount ACTst of the shaft 80a becomes larger than the second threshold value SCth2 (step S4 → No).

When the operation amount ACTst of the ball screw shaft 80a becomes larger than the second threshold value SCth2 (step S4 → Yes), the control means 150 determines whether or not the measured value of the pressure sensor Pp is larger than a predetermined upper limit value Pmax ( Step S5).
When the measured value of the pressure sensor Pp is larger than the predetermined upper limit value Pmax (step S5 → Yes), that is, when the measured value of the brake fluid pressure is outside the leak determination region Lk1, the control unit 150 It is determined that a leak has occurred in the system 70a (step S6). On the other hand, when the measured value of the pressure sensor Pp is equal to or less than the predetermined upper limit value Pmax (step S5 → No), that is, when the measured value of the brake fluid pressure is within the leak determination region Lk1, the control unit 150 It is determined that a leak has occurred in the system 70b (step S7).

  As described above, the control unit 150 of the present embodiment functions as a leak determination unit, and leaks in the first hydraulic system 70b in which the pressure sensor Pp is disposed and the second hydraulic system 70a in which the pressure sensor Pp is not disposed. Determine the occurrence of

  When the control means 150 (see FIG. 1) determines that a leak has occurred in the first hydraulic system 70b (see FIG. 1), the control means 150 (see FIG. 1) switches from the hydraulic pressure feedback control to the target operation amount control, and the motor cylinder device 16 (See FIG. 1). Further, when the control unit 150 determines that there is a leak in the second hydraulic system 70a (see FIG. 1), and determines that there is no leak in the first hydraulic system 70b, Without switching to the quantity control, the hydraulic pressure feedback control is executed to control the motor cylinder device 16.

Further, when executing the target operation amount control, the control means 150 of the present embodiment shown in FIG. 1 controls the motor cylinder device 16 so that the brake fluid pressure rapidly increases when the brake pedal 12 is depressed in the first half of the period. Composed.
For this reason, it is preferable that the target operation amount is set so that the ball screw shaft 80a operates rapidly in response to a change in the brake operation amount when the brake pedal 12 is first depressed, and the vehicle brake system according to the present embodiment. 10 includes an operation amount setting map MP1 as shown in FIG.

In the operation amount setting map MP1 of the present embodiment, as indicated by a solid line in FIG. 4, the target operation amount of the ball screw shaft 80a is in a range from “0” to half of the maximum value (maximum operation amount StMax) (StMax / 2). Then, as the target fluid pressure increases, the target operation amount increases rapidly, and when the target operation amount exceeds half of the maximum operation amount StMax, the change in the target operation amount corresponding to the increase in the target fluid pressure becomes gentle. Is set.
Hereinafter, a movement amount that is half of the maximum movement amount StMax is referred to as a specific movement amount StH. A predetermined intermediate hydraulic pressure generated in the motor cylinder device 16 (see FIG. 1) when the operation amount of the ball screw shaft 80a (see FIG. 1) is the specific operation amount StH is referred to as a specific hydraulic pressure Px. The specific hydraulic pressure Px is a hydraulic pressure determined as a design value of the motor cylinder device 16.

  In other words, the operation amount setting map MP1 indicates that the target hydraulic pressure is smaller than the predetermined intermediate hydraulic pressure (specific hydraulic pressure Px) in the range where the target hydraulic pressure is greater than the specific hydraulic pressure Px. There is a correlation between the target hydraulic pressure and the target operation amount that the change amount of the operation amount is set to be large.

  The vehicle brake system 10 (see FIG. 1) of the present embodiment has a ball screw shaft corresponding to the target hydraulic pressure based on such an operation amount setting map MP1 having a correlation between the target hydraulic pressure and the target operation amount. A target motion amount of 80a (see FIG. 1) is set. With this configuration, the brake fluid pressure output from the motor cylinder device 16 (see FIG. 1) is rapidly increased during the first depression of the brake pedal 12 (see FIG. 1) (the range in which the target fluid pressure is smaller than the specific fluid pressure Px). Can be increased. Therefore, even when the brake fluid is leaking from the first hydraulic system 70b (see FIG. 1), the wheel cylinders 32FR, 32RL, 32RR, 32FL (FIG. 1) Brake fluid pressure can be supplied quickly. Therefore, it is possible to reduce a delay in braking force applied to the wheels (the right front wheel WFR, the left rear wheel WRL, the right rear wheel WRR, and the left front wheel WFL).

  Further, in the operation amount setting map MP1, in the range where the target hydraulic pressure is larger than the specific hydraulic pressure Px (at the later stage of depression of the brake pedal 12), the change in the target operation amount according to the increase in the target hydraulic pressure becomes moderate. Therefore, excessive operation of the ball screw shaft 80a at the later stage of depression of the brake pedal 12 is suppressed. Accordingly, excessive displacement of the first slave piston 88b (see FIG. 1) and the second slave piston 88a (see FIG. 1) is suppressed, and wheels (right front wheel WFR, left rear wheel WRL, right rear wheel WRR, left front wheel). WFL) is restrained from applying an excessive braking force.

  In the operation amount setting map MP1 shown in FIG. 4, if the target hydraulic pressure (specific hydraulic pressure Px) with the target operation amount of the ball screw shaft 80a (see FIG. 1) as the specific operation amount StH is too small (for example, a two-dot chain line) Pxs), even if the target hydraulic pressure is small, a larger amount of brake fluid than the amount of brake fluid that leaks is supplied to the first hydraulic system 70b (see FIG. 1) and the second hydraulic system 70a (see FIG. 1). The braking force is applied to the wheels (the right front wheel WFR, the left rear wheel WRL, the right rear wheel WRR, and the left front wheel WFL). Thereafter, the brake fluid leaks from the first hydraulic system 70b and the brake fluid pressure supplied to the wheel cylinders 32FR, 32RL, 32RR, and 32FL (see FIG. 1) is reduced, so that the braking force applied to the wheels is reduced. To do. Therefore, the vehicle becomes unstable since the braking force is released after the braking force is applied. Therefore, it is preferable that the target fluid pressure (specific fluid pressure Px) at which the target motion amount of the ball screw shaft 80a becomes the specific motion amount StH is appropriately set to a value that does not cause such behavior instability.

  For example, the amount of movement of the ball screw shaft 80a (see FIG. 1) is determined by experimental measurement or simulation based on the average amount of leakage of brake fluid when a leak occurs in the first hydraulic system 70b (see FIG. 1). What is necessary is just to set it as the specific hydraulic pressure Px set so that a suitable braking force may be given to a wheel at the specific operation amount StH.

Further, in the present embodiment, the specific operation amount StH at which the slope of the change in the target operation amount with respect to the change in the target hydraulic pressure changes is set to half of the maximum operation amount StMax (StMax / 2).
When the specific operation amount StH is larger than half of the maximum operation amount StMax (for example, Sta indicated by a one-dot chain line), the target operation amount with respect to the change of the target hydraulic pressure in the range where the target hydraulic pressure is larger than the specific hydraulic pressure Px. Therefore, the control unit 150 (see FIG. 1) cannot accurately control the ball screw shaft 80a in response to the change in the target hydraulic pressure.
On the other hand, when the specific operation amount StH is smaller than half of the maximum operation amount StMax (for example, Stb indicated by a one-dot chain line), the brake pedal 12 (see FIG. 1) is depressed in the previous period (the target hydraulic pressure is smaller than the specific hydraulic pressure Px). Thus, the effect of rapidly increasing the brake fluid pressure is reduced, and the effect of reducing the delay in braking force applied to the wheels (the right front wheel WFR, the left rear wheel WRL, the right rear wheel WRR, and the left front wheel WFL) is reduced.

  Therefore, in the operation amount setting map MP1 of the present embodiment, it is preferable that the specific operation amount StH in which the slope of the change in the target operation amount with respect to the change in the target hydraulic pressure changes is half of the maximum operation amount StMax (StMax / 2). It was said that.

As described above, when the controller 150 (see FIG. 1) of the present embodiment determines that there is a brake fluid leak in the first hydraulic system 70b (see FIG. 1), an operation that is set in advance. With reference to the amount setting map MP1 (see FIG. 4), the target operation amount of the ball screw shaft 80a (see FIG. 1) with respect to the target hydraulic pressure is determined. Then, the control means 150 controls the motor cylinder device 16 (see FIG. 1) based on the determined target operation amount (target operation amount control).
Further, the operation amount setting map MP1 indicates a target hydraulic pressure range in which an operation amount smaller than a specific operation amount StH that is half of the maximum operation amount StMax of the ball screw shaft 80a becomes a target operation amount (the first time the brake pedal 12 is depressed) ), The amount of change in the target operation amount with respect to the change in the target hydraulic pressure is larger than the target hydraulic pressure range (at the later stage of depression of the brake pedal 12) in which the operation amount larger than the specific operation amount StH is the target operation amount. Is set to

  As a result, even if there is a leak in the first hydraulic system 70b (see FIG. 1), the motor cylinder device 16 (see FIG. 1) is in the first half of the depression of the brake pedal 12 (see FIG. 1). The brake fluid pressure output from the cylinder quickly increases, and the brake fluid pressure is quickly supplied to the wheel cylinders 32FR, 32RL, 32RR, and 32FL (see FIG. 1). Therefore, a delay in braking force applied to the wheels (right front wheel WFR, left rear wheel WRL, right rear wheel WRR, left front wheel WFL) is reduced. That is, even when the brake fluid leaks and a time lag occurs in the generation of the braking force, the control unit 150 quickly applies the braking force to the wheels by supplying the high brake fluid pressure to the VSA device 18 quickly. can do.

  On the other hand, even when the control means 150 (see FIG. 1) determines that a leak has occurred in the second hydraulic system 70a (see FIG. 1), a leak has occurred in the first hydraulic system 70b (see FIG. 1). If it is determined that the motor cylinder device 16 has not been operated, the motor cylinder device 16 is controlled (hydraulic feedback control) based on the brake fluid pressure calculated from the measurement signal input from the pressure sensor Pp.

  With this configuration, the control means 150 (see FIG. 1) allows the pressure sensor Pp (see FIG. 1) to be arranged even when the brake fluid leaks in the vehicle brake system 10 (see FIG. 1). If it is determined that no leak has occurred in the first hydraulic system 70b (see FIG. 1), the motor cylinder device 16 (see FIG. 1) is hydraulically controlled based on the measured value of the pressure sensor Pp. Feedback control is possible. Therefore, even if an error occurs in the brake hydraulic pressure generated in the motor cylinder device 16 with respect to the operation of the ball screw shaft 80a (see FIG. 1), the control means 150 does not affect the brake operation amount. A brake fluid pressure equal to the corresponding target fluid pressure can be generated in the motor cylinder device 16. Thus, the control unit 150 can accurately apply a braking force suitable for the vehicle.

  If it is determined that a leak has occurred in the first hydraulic system 70b (see FIG. 1) in which the pressure sensor Pp (see FIG. 1) is disposed, the control means 150 (see FIG. 1) The motor cylinder device 16 (see FIG. 1) can be suitably controlled by the target operation amount control that feeds back the operation amount of the ball screw shaft 80a (see FIG. 1) according to the operation amount. Further, the control means 150 is configured to increase the brake fluid pressure supplied to the wheel cylinders 32FR, 32RL, 32RR, and 32FL (see FIG. 1) when the target operation amount control is executed so that the brake fluid pressure is rapidly increased when the brake pedal 12 is depressed. The cylinder device 16 is controlled. Therefore, the time lag from when the driver depresses the brake pedal 12 until the braking force is generated is reduced, and the decrease in brake feel is reduced.

Thus, the vehicle brake system 10 (see FIG. 1) of the present embodiment is one of the independent first hydraulic system 70b (see FIG. 1) and the second hydraulic system 70a (see FIG. 1) (this embodiment). In the embodiment, the pressure sensor Pp (see FIG. 1) is disposed in the first hydraulic system 70b). With this configuration, the number of pressure sensors Pp can be reduced, and an inexpensive vehicle brake system 10 can be obtained.
Further, even if a leak occurs in the second hydraulic system 70a, if no leak occurs in the first hydraulic system 70b, the brake hydraulic pressure fed back from the pressure sensor Pp to the control means 150 (see FIG. 1). The motor cylinder device 16 (see FIG. 1) is controlled by hydraulic pressure feedback control based on the measured value. Therefore, even if an error in the operation of the ball screw shaft 80a (see FIG. 1) occurs in the brake hydraulic pressure generated in the motor cylinder device 16, an accurate brake corresponding to the amount of brake operation is not affected by the error. It can be set as the vehicle brake system 10 which generate | occur | produces hydraulic pressure. Therefore, the vehicular brake system 10 of the present embodiment has a high accuracy of the brake hydraulic pressure supplied to the brake operating portions (wheel cylinders 32FR, 32RL, 32RR, 32FL) even when the brake fluid leaks. Reduction is reduced.

It should be noted that the design of the present invention can be changed as appropriate without departing from the spirit of the invention.
For example, in the present embodiment, the control means 150 (see FIG. 1) determines the target operation amount of the ball screw shaft 80a (see FIG. 1) with respect to the target hydraulic pressure with reference to the operation amount setting map MP1 shown in FIG. The configuration. Instead of this configuration, the control unit 150 may determine the target operation amount of the ball screw shaft 80a with respect to the target hydraulic pressure using a function indicating the relationship between the target hydraulic pressure and the target operation amount.
The function in this case is, for example, a function of the operation amount setting map MP1 shown in FIG. 4, and in a range where the target hydraulic pressure is smaller than the specific hydraulic pressure Px, the target hydraulic pressure is larger than a range larger than the specific hydraulic pressure Px. Also, a function with a large change amount of the target operation amount with respect to the change of the target hydraulic pressure may be used.

  In the present embodiment, the control means 150 (see FIG. 1) is used only when a brake fluid leak occurs in the first hydraulic system 70b (see FIG. 1) in which the pressure sensor Pp (see FIG. 1) is disposed. However, the motor cylinder device 16 (see FIG. 1) is controlled by switching from the hydraulic feedback control to the target operation amount control. For example, when a leak occurs in the second hydraulic system 70a (see FIG. 1), the control unit 150 switches the hydraulic cylinder feedback 16 from the hydraulic feedback control to the target operation amount control, so that the motor cylinder device 16 is switched. It is good also as a structure to control. In addition, when a leak occurs in both the first hydraulic system 70b and the second hydraulic system 70a, the control unit 150 switches the hydraulic feedback control to the target operation amount control to control the motor cylinder device 16. There may be.

10 Brake system for vehicle 16 Motor cylinder device (hydraulic pressure generating means)
70a Second hydraulic system (hydraulic system)
70b First hydraulic system (hydraulic system equipped with supply hydraulic pressure measuring means)
72 Electric motor (actuator)
74 Actuator mechanism (actuator)
80a Ball screw shaft (actuator)
150 Control means (leak judgment means)
Pp Pressure sensor (Supply hydraulic pressure measurement means, leak judgment means)

Claims (2)

Fluid that pressurizes the brake fluid by the operation of the actuator to generate a hydraulic pressure corresponding to the amount of operation of the brake operating unit, and supplies the generated hydraulic pressure to the brake operating unit via two independent hydraulic systems Pressure generating means;
Control means for controlling the actuator based on a target hydraulic pressure corresponding to an operation amount of the brake operation unit;
Provided in one of the hydraulic systems, supply hydraulic pressure measuring means for feeding back to the control means a measurement value obtained by measuring the hydraulic pressure supplied to the brake operating unit in the hydraulic system,
Leak determination means for determining whether or not the brake fluid leaks in the hydraulic system based on the operation amount of the actuator and the measured value of the hydraulic pressure,
The control means includes
The hydraulic pressure feedback control based on the target hydraulic pressure and the measured value fed back from the supply hydraulic pressure measuring means is executed, and the hydraulic pressure generated by the hydraulic pressure generating means becomes the target hydraulic pressure. In a vehicle brake system that controls the actuator to approach,
When the leak determination means determines that the leak has occurred in the hydraulic system provided with the supply hydraulic pressure measurement means, the control means, based on the hydraulic pressure feedback control, corresponds to the target hydraulic pressure. Switch to target operation amount control for controlling the actuator based on the target operation amount of the actuator ,
The control means includes
When executing the target operation amount control,
In a range where the target hydraulic pressure is lower than a predetermined intermediate hydraulic pressure generated in the hydraulic pressure generating means when the operating amount of the actuator is half of the maximum operating amount, the target hydraulic pressure is higher than the intermediate hydraulic pressure. And calculating the target operation amount corresponding to the target hydraulic pressure based on the correlation between the target hydraulic pressure and the target operation amount that the change amount of the target operation amount with respect to the change of the target hydraulic pressure is large. Brake system for vehicles. The control means includes
When the leak determination unit determines that the leak does not occur in the hydraulic system provided with the supply hydraulic pressure measurement unit, the hydraulic pressure feedback control is executed without switching to the target operation amount control. The vehicle brake system according to claim 1.

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