Hydraulic brake system

Abstract

The present application provides a new configuration of hydraulic brake system not including a master cylinder. The present hydraulic brake system includes: hydraulic brakes respectively provided at a plurality of wheels; and electric cylinder devices respectively connected to wheel cylinders of one or more of the plurality of hydraulic brakes. The plurality of electric cylinder devices included in the present hydraulic brake system each includes a housing, a piston capable of being slidably and liquid-tightly fitted to the housing, an electric motor as a drive source, a linear motion and rotation conversion device that converts rotation of the electric motor to linear movement, and a volume change chamber provided in front of the piston and connected to a hydraulic chamber of the wheel cylinder of one or more of the hydraulic brakes. Thus, the hydraulic brake system to which the present application is applied, including the plurality of hydraulic brakes and the plurality of electric cylinder devices, is a new hydraulic brake system.

Description

TECHNICAL FIELD

[0001] The present application relates to a hydraulic brake system that applies a brake force generated by hydraulic pressure to a vehicle. BACKGROUND

[0002] In Patent Document 1, a hydraulic brake system is described that does not include a master cylinder, but includes a plurality of hydraulic brakes, and pressure generating devices connected to wheel cylinders of the plurality of hydraulic brakes, respectively. However, the configuration of the pressure generating devices is not disclosed in Patent Document 1.

[0003] Patent Document 1: Japanese Patent Application Publication No. H8-26099 SUMMARY

[0004] The present application relates to a hydraulic brake system that applies a brake force generated by hydraulic pressure to a vehicle.

[0005] The hydraulic brake system according to the present application includes: hydraulic brakes provided to a plurality of wheels, respectively; and electric cylinder devices connected to wheel cylinders of one or more of the plurality of hydraulic brakes, respectively. The plurality of electric cylinder devices included in the hydraulic brake system according to the present application each include a housing, a piston that is able to be fitted to the housing in a liquid-tight and slidable manner, an electric motor that is a drive source, a linear and rotary motion conversion device that converts rotation of the electric motor to linear movement of the piston, and a volume change chamber provided to a front of the piston and connected to a hydraulic chamber of the wheel cylinder of one or more of the hydraulic brakes. Thus, the hydraulic brake system according to the present application that includes the plurality of hydraulic brakes and the plurality of electric cylinder devices is not described in Patent Document 1. The hydraulic brake system according to the present application is a new hydraulic brake system. BRIEF DESCRIPTION OF DRAWINGS

[0006] Figure 1 FIG. 1 is a diagram schematically showing an overall configuration of a hydraulic brake system according to an embodiment of the present application.

[0007] Figure 2 FIG. 2 is an exploded side view of an electric cylinder device of the hydraulic brake system described above.

[0008] Figure 3 FIG. 3 is a diagram showing a vehicle on which the hydraulic brake system described above is mounted.

[0009] Figure 4 FIG. 4 is a diagram showing another vehicle on which the hydraulic brake system described above is mounted.

[0010] Figure 5 FIG. 5 is a diagram showing still another vehicle on which the hydraulic brake system described above is mounted.

[0011] Figure 6 FIG. 6 is a diagram showing still another vehicle on which the hydraulic brake system described above is mounted.

[0012] Figure 7 This is a flowchart representing the normal braking control program stored in the driving assistance ECU of the aforementioned hydraulic braking system.

[0013] Figure 8 This is a flowchart representing the motor control program stored in the brake ECU of the aforementioned hydraulic braking system.

[0014] Figure 9 This is a flowchart representing the slip suppression control program stored in the brake ECU of the aforementioned hydraulic braking system.

[0015] Figure 10 This is a flowchart representing the braking control program when an abnormality occurs in the brake ECU of the aforementioned hydraulic braking system.

[0016] Explanation of reference numerals in the attached figures

[0017] 10…Hydraulic brake; 12…Electric cylinder device; 25…Wheel cylinder; 26…Hydraulic chamber; 27…Wheel-side piston; 40…Housing; 40f…Front housing; 40r…Rear housing; 42…Electric piston assembly; 44…Electric motor; 48…Direct-drive conversion device; 50…Storage device; 80…Threaded assembly; 82…Nut assembly; 86…Brake ECU; 96…Driver assistance ECU; V…Power supply. Detailed Implementation

[0018] Hereinafter, a hydraulic braking system as an embodiment of the present invention will be described with reference to the accompanying drawings.

[0019]

Example

[0020] The hydraulic braking system described in this embodiment does not include a manual hydraulic source (e.g., a master cylinder) that generates hydraulic pressure due to the driver's operation of the braking components.

[0021] like Figure 3 As shown, this hydraulic braking system includes hydraulic brakes 10FL, 10FR, 10RL, and 10RR respectively installed on the four wheels WFL, WFR, WRL, and WRR of the vehicle, and electric cylinder devices 12FL, 12FR, 12RL, and 12RR connected to each of the hydraulic brakes 10FL, 10FR, 10RL, and 10RR in a one-to-one correspondence. Hereinafter, in general terms or in descriptions unrelated to wheel positions, the suffixes FL, FR, RL, RR, F, and R indicating wheel positions may be omitted.

[0022] In this embodiment, as Figure 1As shown, the hydraulic brake 10 includes, as a pair of friction engagement members, friction plates 21, 22 on both sides of a brake rotor 20 provided to be integrally rotatable with a wheel W, and a press device 23 that presses the friction plates 21, 22 against the brake rotor 20. The press device 23 includes a brake caliper 24 that is movably held to a non-rotating member in a direction parallel to a rotation axis N of the wheel (hereinafter, referred to as a rotation axis direction), and a wheel cylinder 25 provided to the brake caliper 24. The wheel cylinder 25 includes a piston (hereinafter, referred to as a wheel-side piston) 27 that is capable of achieving a fluid seal and is slidably fitted to a cylinder bore formed in the brake caliper 24, and a hydraulic chamber 26 provided to a rear side of the wheel-side piston 27. In addition, a piston seal 28 is attached to the brake caliper 24.

[0023] The wheel-side piston 27 is advanced by supplying hydraulic pressure to the hydraulic chamber 26 of the wheel cylinder 25, and the brake caliper 24 is moved in the rotation axis direction. The pair of friction plates 21, 22 are pressed against the brake rotor 20 and frictionally engaged by a pressing force Fp corresponding to the hydraulic pressure P of the hydraulic chamber 26. Thus, the rotation of the wheel is suppressed. In addition, the pressing force Fp is increased or decreased by increasing or decreasing the hydraulic pressure P of the hydraulic chamber 26.

[0024] The electric cylinder device 12 includes a housing 40, a piston member (hereinafter, referred to as an electric piston member) 42 that is capable of achieving a fluid seal and is slidably fitted to the housing 40 as a piston, an electric motor 44 as a drive source, a linear motion and rotation conversion device (hereinafter, simply referred to as a linear conversion device) 48 that performs conversion between rotation of the electric motor 44 and linear movement of the electric piston member 42, and a reservoir 50. The electric piston member 42 is not rotatable about an axis M of the electric piston member 42 and is movably held to the housing 40 in a direction parallel to the axis M.

[0025] The reservoir 50 stores a working fluid used in the hydraulic brake 10, and stores a working fluid that enables a certain brake even after a consumed fluid amount changes in elastic deformation caused by wear and pressurization of the friction plates 21, 22, and leakage of the working fluid. In addition, in the reservoir 50, a working fluid returned from the wheel cylinder 25 of the hydraulic brake 10 connected to the electric cylinder device 12 is stored.

[0026] In the present embodiment, the electric piston member 42 is constituted by a piston portion 47 and a rod portion (hereinafter, simply referred to as a rod) 46 that is slidably fitted to the piston portion 47. In addition, the piston portion 47 and the rod portion 46 can be integrally manufactured. In the present embodiment, it can be considered that a piston recited in a claim corresponds to the piston portion 47 or the electric piston member 42, or the like.

[0027] The housing 40 includes a rear side housing 40r that is a first housing in which the electric motor 44 is accommodated, a front side housing 40f that is a second housing formed in a bottomed cylindrical shape, and an intermediate housing 40m that is located between the front side housing 40f and the rear side housing 40r. These rear side housing 40r, intermediate housing 40m, and front side housing 40f can be disassembled from each other.

[0028] The electric motor 44 is disposed coaxially with the electric piston member 42 on the outer peripheral side of the rod portion 46. In addition, the electric motor 44 includes a plurality of coils 52 that are a stator, are mainly accommodated in the rear side housing 40r, and are held to the rear side housing 40r and the intermediate housing 40m, and a rotor 54 that is located on the inner peripheral side of the coils 52 and is formed in a substantially cylindrical shape with a plurality of magnets Z. The rotor 54 is rotatably held to the rear side housing 40r and the intermediate housing 40m via a pair of bearings 56, 57 that are disposed apart in a direction parallel to the axis M. Further, in the rotor 54, the magnets Z can be disposed on an outer peripheral surface or can be embedded in an inner portion.

[0029] In addition, a linear motion conversion device 48 is disposed between the inner peripheral portion of the rotor 54 and the outer peripheral portion of the rod portion 46. In the present embodiment, the linear motion conversion device 48 is provided with a ball screw mechanism including an external thread portion 62 disposed on the outer peripheral portion of the rod portion 46, an internal thread portion 63 disposed on the inner peripheral portion of the rotor 54, and a plurality of balls 64 interposed between the external thread portion 62 and the internal thread portion 63.

[0030] The front side housing 40f is formed with a cylinder bore in which the electric piston member 42 is held in a liquid-tight and slidable manner via a seal member 66, and a front of the electric piston member 42 in the cylinder bore of the front side housing 40f is a volume change chamber 67. In addition, a return spring 68 is disposed between the electric piston member 42 and a bottom portion of the front side housing 40f. The electric piston member 42 is given an elastic force in a backward direction by the return spring 68.

[0031] A front side cylinder port 70 and a rear side cylinder port 72 are provided in portions of the front side housing 40f (which is a portion of the housing 40 that surrounds the volume change chamber 67) that are spaced apart in a direction parallel to the axis M. In the front side cylinder port 70, the hydraulic chamber 26 of the wheel cylinder 25 is directly connected via a liquid passage 74, and in the rear side cylinder port 72, the reservoir 50 is connected. The rear side cylinder port 72 can be referred to as an idle cylinder port.

[0032] The front side cylinder port 70 is always in an open state, and the volume change chamber 67 and the hydraulic chamber 26 of the wheel cylinder 25 are always in communication via the liquid passage 74. In the present embodiment, no solenoid valve or the like is provided in the liquid passage 74.

[0033] The rear-side cylinder port 72 is in an open state in the case where the electric piston member 42 is in the retracted end position, but is switched to a closed state by the advance of the electric piston member 42, causing the volume change chamber 67 to generate hydraulic pressure. The retracted end position of the electric piston member 42 is a position where the electric piston member 42 abuts against a non-illustrated stopper provided to the housing 40.

[0034] In addition, in the electric cylinder device 12 according to the present embodiment, the diameter D (refer to Fig. 2) of the piston portion 47 of the electric piston member 42 is small, and the maximum stroke L of the electric piston member 42 is large. For example, the maximum stroke L of the electric piston member 42 can be considered to be the length L between the front end surface of the piston portion 47 in the case where the electric piston member 42 is in the retracted end position and the bottom surface of the front-side housing 40f. In addition, the full stroke as the maximum stroke L includes an empty stroke Lp as the stroke from the retracted end position of the electric piston member 42 to the plugging idle cylinder port 72. Figure 2

[0035] For example, in a master cylinder as a manual hydraulic pressure source, a pressurizing piston is coupled to a brake pedal as a brake operation member that can be operated by a driver, and the pressurizing piston advances in conjunction with the depression operation of the brake pedal. On the other hand, the brake pedal is depressed by the driver, and thus the maximum stroke of the brake pedal is determined based on ergonomics and the like, and the maximum stroke of the pressurizing piston is also determined by the maximum stroke of the brake pedal. Therefore, the maximum stroke of the pressurizing piston of the master cylinder is usually less than 50 mm.

[0036] In contrast, in the electric cylinder device 12 according to the present embodiment, the electric piston member 42 is moved not by the operation of the brake operation member but by the electric motor 44. Therefore, the maximum stroke can be increased without the constraints of ergonomics and the like. Moreover, since the maximum stroke of the electric piston member 42 can be increased, even if the diameter D (pressure receiving area SA) of the electric piston member 42 is small, the amount of working fluid required in the wheel cylinder 25 can be supplied. In other words, in order to supply the amount of working fluid required in the wheel cylinder 25, by increasing the maximum stroke of the electric piston member 42, the pressure receiving area SA (diameter D) of the piston portion 47 can be reduced.

[0037] In this way, by reducing the pressure receiving area SA of the electric piston member 42, the value of the pressure receiving area SW of the wheel-side piston 27 of the wheel cylinder 25 of the hydraulic brake 10 divided by the pressure receiving area SA of the electric piston member 42 (hereinafter, simply referred to as the pressure receiving area ratio) SW / SA can be increased. Therefore, when the required pressing force Fp in the wheel cylinder 25 is the same, the axial force Fs applied to the rod portion 46 of the direct conversion device 48 can be reduced, and accordingly the reduction of the consumed electric power in the electric motor 44 can be achieved.

[0038] The following will be described in detail.​

[0039] (a) By increasing the ratio SW / SA of the pressure receiving area and reducing the axial force Fs applied to the rod portion 46, it is possible to reduce the transmission ratio of the electric motor 44 (for example, which can be expressed as "rotational speed of the electric motor 44 / rotational speed of the rod portion 46") and reduce the output of the electric motor 44.

[0040] If the axial force Fs applied to the rod portion 46 is large, it is possible to consider providing a speed reducer between the electric motor 44 and the direct motion conversion device 48 to increase the reduction ratio. On the other hand, in the speed reducer, an involute gear is generally used, but the teeth and the tooth edge slide while transmitting force when the involute gear is engaged. In addition, rotational resistance is generated due to friction caused by the thrust load of the gear of the speed reducer and the thrust and pull between the shafts, and the amount of energy consumption in the speed reducer becomes large. In this way, in the case where the reduction ratio is increased and the efficiency of the speed reducer is greatly reduced, the transmission efficiency of the electric motor 44 (for example, which can be expressed as "energy transmitted to the piston portion 47 / energy supplied to the electric motor 44") is greatly reduced.

[0041] In contrast, in the present embodiment, since the axial force Fs is reduced, it is possible to reduce the reduction ratio, eliminate the speed reducer, reduce the output of the electric motor 44, and the like, and accordingly, it is possible to improve the transmission efficiency of the electric motor 44. In addition, in the present embodiment, since the axial force Fs is reduced, it is possible to reduce the diameter of the rod portion 46, and accordingly, it is possible to reduce the reduction ratio of the direct motion conversion device 48 and increase the lead angle. Figure 1 、 2 The case where the speed reducer is not provided in the electric cylinder device 12 is described in the above.

[0042] (b) Since the axial force Fs applied to the rod portion 46 is reduced, it is possible to reduce the diameter of the rod portion 46 of the direct motion conversion device 48. Therefore, it is possible to suppress the reduction of the reduction ratio of the direct motion conversion device 48 (for example, which can be expressed as "feed speed / (lead x input rotational speed of the direct motion conversion device 48)") and increase the lead angle, and thus it is possible to improve the transmission efficiency of the electric motor 44.

[0043] If the axial force Fs is large, it is necessary to increase the ball 64 of the ball screw mechanism to increase the diameter of the rod portion 46. In the case where the lead angle is the same, if the diameter of the rod portion 46 is increased, the lead is increased, and thus the reduction ratio of the direct motion conversion device 48 is reduced. Therefore, it is necessary to increase the transmission ratio of the electric motor 44 and increase the output of the electric motor 44. In addition, if the lead angle is reduced, the reduction ratio of the direct motion conversion device 48 becomes large, and thus it is possible to reduce the transmission ratio of the electric motor 44, but the transmission efficiency of the electric motor 44 is reduced due to the reduction of the lead angle.

[0044] In contrast, in the electric cylinder device 12 related to the present embodiment, since the axial force Fs is reduced, it is possible to reduce the diameter of the rod portion 46, and it is possible to suppress the reduction of the reduction ratio of the direct motion conversion device 48 and increase the lead angle. Therefore, it is possible to improve the transmission efficiency of the electric motor 44.

[0045] In other words, the position of the linear motion conversion device 48 in the electric cylinder device 12 is designed so as to make the shaft force Fs applied to the linear motion conversion device 48 as small as possible. For example, in the electric cylinder device 12, the electric motor 44, the linear motion conversion device 48, and the piston portion 47 are arranged in series, and the volume change chamber 67 in front of the piston portion 47 is connected to the hydraulic brake 10, but in the present hydraulic brake system, the ratio of the pressure receiving areas is made large, so the push pressure of the friction plates 21, 22 against the brake rotor 20 can be increased with respect to the hydraulic pressure of the volume change chamber 67. Therefore, the linear motion conversion device 48 is arranged on the upstream side of the piston portion 47, or on the downstream side of the electric motor 44 or the speed reducer.

[0046] (c) The stroke of the electric piston portion 42 is made large, and the length of the cylinder bore formed in the front side housing 40f is made large, but the position of the idle cylinder port 72 in the housing 40 of the electric cylinder device 12 is the same regardless of the size of the length of the cylinder bore formed in the front side housing 40f. Therefore, if the maximum stroke L is made long, the ratio (Lp / L) of the idle stroke Lp with respect to the maximum stroke L of the electric piston portion 42 is made small. As a result, the transmission efficiency of the electric motor 44 is made high.

[0047] According to the above, the transmission efficiency of the electric motor 44 can be improved to reduce the consumed electric power of the electric motor 44.

[0048] In addition, since the transmission ratio of the electric motor 44 can be made small, the speed reducer can not be needed, and the speed reducer can be made small, so the electric cylinder device 12 can be made small and light, and the number of components in the electric cylinder device 12 can be reduced.

[0049] In addition, since the lead angle θ can be made large in the linear motion conversion device 48, the direct and reverse efficiencies, i.e., the direct efficiency (wheel cylinder pressure / axial force) and the reverse efficiency (axial force / wheel cylinder pressure) can be made large.

[0050] The above describes the case where the linear motion conversion device 48 is a ball screw mechanism, but the linear motion conversion device 48 can include an acme screw mechanism, and in the case where the linear motion conversion device 48 includes an acme screw mechanism, the same effects as the above can be obtained, i.e., the transmission efficiency of the electric motor 44 can be improved to reduce the consumed electric power.

[0051] Especially in trapezoidal thread mechanisms, grease plays a crucial role as a lubricant in reducing the friction between the external and internal threads. Generally, the frictional force is greater when the surface pressure between the external and internal threads is higher than when it is lower. Furthermore, when the surface pressure is below a set value, grease provides good lubrication between the external and internal threads. However, if the surface pressure exceeds the set value, the temperature increases, the viscosity of the grease decreases, and the lubrication effect diminishes. As a result, the friction between the external and internal threads increases, leading to damage to the external and internal threads (a condition sometimes referred to as grease deficiency).

[0052] On the other hand, the sliding area between the external thread and the internal thread can be increased by increasing the diameter of the rod 46, and the friction can be reduced by reducing the surface pressure acting between them, but other problems arise such as the increase in the size of the electric cylinder device 12 and the change in the reduction ratio of the direct drive conversion device 48.

[0053] In contrast, in this embodiment, the axial force Fs applied to the rod portion 46 can be reduced, thus reducing the surface pressure and suppressing the decrease in grease viscosity, thereby effectively reducing the friction between the external and internal threads. Furthermore, by suppressing grease overheating, grease deterioration can also be prevented. Moreover, generally, a small lead angle makes grease loss more likely, but by increasing the lead angle, grease loss is less likely, further reducing friction.

[0054] Furthermore, in the case where the direct-acting conversion device 48 includes a ball screw mechanism, grease is used in the ball screw mechanism to reduce the sliding resistance between the ball 64 and the external thread portion 62 and the internal thread portion 63. However, even in this case, as described above, the same effect can be achieved by reducing the axial force Fs.

[0055] On the other hand, such as Figure 2 As shown, the electric cylinder device 12 can be easily disassembled. Specifically, the rear housing 40r, the intermediate housing 40m, and the front housing 40f are joined by a coupling device. The coupling device may include, for example, a plurality of threaded parts 80 extending in the axial direction and a nut part 82 that engages with the threaded parts 80.

[0056] In addition, the bearing 56, the electric motor 44 (the coil 52, the rotor 54), the rod portion 46, the piston portion 47, the sealing member 66, the ball 64, and the like are easily assembled separately in the inner portions of the rear-side housing 40r, the intermediate housing 40m, and the front-side housing 40f. Therefore, by removing the nut member 82, the electric cylinder device 12 can be separated into the front-side housing 40f, the intermediate housing 40m, and the rear-side housing 40r, and each constituent element of the electric cylinder device 12 can be removed.

[0057] The electric cylinder device 12 is not provided to the brake caliper 24 but is provided to the fluid passage 74 extending from the brake caliper 24. On the other hand, in a case where an electric actuator of an electric brake that suppresses the rotation of the wheel W is provided to the brake caliper 24, the electric actuator needs to be closed and unitized in order not to splash mud and water to the electric actuator. In contrast to this, in the present electric cylinder device 12, mud, water, and the like are less likely to splash compared to the electric actuator of the electric brake, and thus the necessity of unitization and closing of the housing is reduced.

[0058] In addition, in the present embodiment, a solenoid valve is not provided on the downstream side of the electric cylinder device 12. Therefore, in a case where the electric cylinder device 12 is disassembled, there is no risk that a foreign object or the like intrudes into the eye portion of the solenoid valve and a failure occurs in the solenoid valve.

[0059] As a result, a configuration in which the electric cylinder device 12 can be easily disassembled can be said to be achieved, and maintenance can be individually performed for each of the constituent elements. For example, in a case where a failure occurs in one of the plurality of constituent elements, the entire electric cylinder device 12 does not need to be replaced, and the one constituent element in which the failure has occurred can be replaced or the like. As a result, for the user, reduction of the maintenance cost of the vehicle can be achieved, and reduction of waste can be achieved. In addition, since the electric cylinder device 12 is provided in the vicinity of the wheel, the maintenance work becomes easy.

[0060] As shown in FIG. 1, the electric cylinder device 12 is provided with a brake ECU 86 as a control portion corresponding one-to-one and including a computer as a main body. The electric cylinder device 12 is controlled by the brake ECU 86. The brake ECU 86 includes a drive circuit 88 such as an inverter, and controls the supply current to the electric motor 44 and the operation of the electric motor 44 by the control of the drive circuit 88. Figure 1 3 In addition, the brake ECU 86 is connected to a liquid level sensor 90, a stroke sensor 92, a rotation speed sensor 94, a wheel speed sensor 100 as a wheel speed detection device, a hydraulic pressure sensor 102, and the like as constituent elements of the electric cylinder device 12.

[0061] In addition, the brake ECU 86 is connected to a liquid level sensor 90, a stroke sensor 92, a rotation speed sensor 94, a wheel speed sensor 100 as a wheel speed detection device, a hydraulic pressure sensor 102, and the like as constituent elements of the electric cylinder device 12.

[0062] ​The liquid level sensor 90 detects the position (liquid level height) of the working fluid contained in the reservoir 50. The liquid level sensor 90 can detect the liquid level height using methods such as optics, magnetism, electrostatic capacitance, ultrasound, or pressure. Alternatively, it can be a contact or non-contact sensor, or a sensor that uses a buoy for detection.

[0063] The stroke sensor 92 detects the stroke of the electric piston component 42, for example, by detecting the relative position of the rod 46 or piston 47 relative to the housing 40.

[0064] The speed sensor 94 detects the rotational speed of the electric motor 44. Furthermore, based on the rotational speed of the electric motor 44, the stroke of the electric piston component 42 can be obtained.

[0065] Wheel speed sensors 100 are respectively set to correspond to each wheel W located at the front, rear, left, and right, and respectively detect the rotational speed of each wheel W. The vehicle speed and the slip state of each wheel W are obtained based on the detection values ​​of the four wheel speed sensors 100.

[0066] The hydraulic sensor 102 detects the hydraulic pressure (hereinafter referred to as the hydraulic pressure of the hydraulic brake 10 or the hydraulic pressure of the wheel cylinder 25) of the hydraulic brake 10 located at the front, rear, left, and right of each wheel W. The hydraulic sensor 102 is often located in the fluid passage 74.

[0067] In addition, such as Figure 3 As shown, each of the electric cylinder devices 12 is equipped with a power supply V corresponding to each other. The power supply V is, for example, a lithium-ion battery, a capacitor, etc. The electric cylinder device 12, namely the brake ECU 86, the drive circuit 88, the liquid level sensor 90, the stroke sensor 92, the speed sensor 94, the wheel speed sensor 100, the hydraulic sensor 102, etc., can operate through a separate, in other words, a dedicated power supply V for the electric cylinder device.

[0068] Further, the brake ECUs 86 (each of the brake ECUs 86FL, 86FR, 86RL, 86RR provided to each of the wheels WFL, WFR, WRL, WRR at the front, rear, left, and right) are connected to a computer-based drive assist ECU 96 via a vehicle body communication network such as a CAN (Controller Area Network) 95. In this embodiment, communication is performed between the drive assist ECU 96 and each of the brake ECUs 86 via the CAN 95, and communication is performed among the four brake ECUs 86. The drive assist ECU 96 outputs a brake request to the electric cylinder device 12, acquires and outputs a requested brake force. The drive assist ECU 96 is connected to an operation state detection device 104, a surrounding information acquisition device 106, and the like.

[0069] The operation state detection device 104 detects an operation state (e.g., stroke, operation force) of a not-illustrated brake operation member that can be operated by a driver.

[0070] The surrounding information acquisition device 106 includes a camera, a radar device, and the like, acquires an object located in the surroundings of a host vehicle that is a vehicle, a lane line of a road in the surroundings of the host vehicle, a curved shape of the road, and the like, and acquires a relative positional relationship between the object and the host vehicle.

[0071] In the hydraulic brake system configured as described above, in the drive assist ECU 96, it is determined whether there is a brake request based on the operation state of the brake operation member detected by the operation state detection device 104, the relative positional relationship between the object in the surroundings and the host vehicle acquired by the surrounding information acquisition device 106, and the like. Further, in the case where there is a brake request, a requested brake force is acquired based on these operation states of the brake operation member, the relative positional relationship between the object in the surroundings and the host vehicle, and the like, and is supplied to the electric cylinder device 12 (brake ECU 86) respectively.

[0072] In the brake ECU 86, based on the requested brake force, a target hydraulic pressure of the hydraulic brake 10 is acquired respectively, and the supply current to the electric motor 44 is controlled in such a manner that the actual hydraulic pressure as a detection value of the hydraulic pressure sensor 102 approaches the target hydraulic pressure, and the electric piston member 42 is advanced or retracted.

[0073] In the electric cylinder device 12, by advancing the electric piston member 42, the volume of the volume change chamber 67 becomes smaller, the working fluid is supplied to the hydraulic chamber 26 of the wheel cylinder 25, and the hydraulic pressure becomes higher. In the electric cylinder device 12, by retracting the electric piston member 42, the volume of the volume change chamber 67 becomes larger, the working fluid flows out from the hydraulic chamber 26 of the wheel cylinder 25, and the hydraulic pressure becomes lower. The electric piston member 42 is advanced or retracted in such a manner that the hydraulic pressure of the wheel cylinder 25 approaches the target hydraulic pressure, and the supply current to the electric motor 44 is controlled.

[0074] In the absence of a brake request, the electric cylinder device 12 is caused to return the electric piston member 42. By this, the idle cylinder port 72 is opened, and the hydraulic chamber 26 is caused to communicate with the reservoir 50. The electric piston member 42 is caused to return until abutting against the stopper. In the wheel cylinder 25, the wheel-side piston 27 is caused to return by the piston seal 28, and the friction plates 21, 22 are caused to separate from the brake rotor 20. The hydraulic brake 10 becomes a non-operating state.

[0075] In addition, if the slip of the wheel W is excessively large, slip suppression control is performed. In the slip suppression control, the electric piston member 42 is caused to retreat, advance by control of the supply current to the electric motor 44, and thereby the hydraulic pressure of the hydraulic chamber 26 of the wheel cylinder 25 is caused to decrease, increase, and the slip rate of the wheel W is caused to be an appropriate size determined by the friction coefficient of the road surface.

[0076] The brake control program at normal time shown in the flowchart of FIG. 8 is executed by the drive assist ECU 96 every predetermined cycle time. Figure 7 Here, the normal time means a case where no abnormality is detected in the electric cylinder device 12 or the like.

[0077] In step 1 (hereinafter, abbreviated as S1. The same applies to other steps), the operation state of the brake operation member detected by the operation state detection device 104 is acquired, in S2, information indicating the relative positional relationship between the host vehicle and the surrounding objects acquired by the surrounding information acquisition device 106 or the like is acquired, and in S3, it is determined whether or not there is a brake request based on these. In braking, it is determined that there is a brake request. In the case where it is determined YES, the requested brake force is acquired in S4, and in S5, it is supplied to the brake ECU 86 of the wheel W corresponding thereto.

[0078] The motor control program shown in the flowchart of FIG. 9 is executed by the brake ECU 86 every predetermined cycle time. Figure 8

[0079] In Sll, the target hydraulic pressure Pt is acquired from the requested brake force, and the actual hydraulic pressure Ps as the measured value of the hydraulic pressure sensor 102 is acquired. In S12, it is determined whether or not the target hydraulic pressure Pt is 0. In the case where the requested brake force is not acquired, it is determined that the target hydraulic pressure Pt is 0.

[0080] In the case where it is determined NO, in S13, it is determined whether or not the target hydraulic pressure Pt is larger than the actual hydraulic pressure Ps. In the case where it is determined YES, in S14, the electric piston member 42 is caused to advance against the elastic force of the return spring 68 by control of the electric motor 44. By this, the volume of the volume change chamber 67 is decreased, and the hydraulic pressure of the wheel cylinder 25 is increased.

[0081] ​In the case where the determination in S13 is NO, in S15, it is determined whether the actual hydraulic pressure Ps is greater than the target hydraulic pressure Pt. In the case where the determination is YES, in S16, the electric piston member 42 is retracted by control of the electric motor 44. The volume of the volume change chamber 67 increases, and the hydraulic pressure of the wheel cylinder 25 decreases.

[0082] In the case where the difference between the target hydraulic pressure Pt and the actual hydraulic pressure Ps is small, almost the same, in S17, the position of the electric piston member 42 is maintained, and the hydraulic pressure is maintained. In the case where the determination in S12 is YES, the target hydraulic pressure Pt is 0, in S18, the electric piston member 42 is retracted to the retracted end by control of the electric motor 44.

[0083] In addition, the brake ECU 86 executes the slip suppression control program shown in the flowchart of Figure 9 respectively.

[0084] In S21, the slip ratio of each wheel W is acquired. The slip ratio is acquired on the basis of the vehicle body speed and the wheel speed, but the vehicle body speed can be acquired, for example, by communication among the brake ECUs 86FL, 86FR, 86RL, 86RR. For example, each brake ECU 86 acquires the vehicle body speed Vh on the basis of the wheel speed Vwa detected by the wheel speed sensor 100 connected thereto and the wheel speeds Vwb, Vwc, Vwd received via the CAN 95. Also, the slip state of the wheel W can be acquired on the basis of this vehicle body speed Vh and the wheel speed Vwa detected by the wheel speed sensor 100 connected thereto. The vehicle body speed Vh changes more slowly than the wheel speed Vw, so a value acquired on the basis of information received via the CAN 95 can be used.

[0085] In S22, it is determined whether it is in the slip suppression control, and in the case where the determination is NO, in S23, it is determined, for example, whether a start condition including that the slip ratio is excessively large or the like is satisfied. In the case where the determination is YES, in S24, the slip suppression control is started. Next, in the case where the present program is executed, since it is in the slip suppression control, in S25, it is determined whether an end condition including that the slip ratio is suppressed or the like is satisfied. In the case where the determination is NO, in S26, the slip suppression control is continued. The target hydraulic pressure is acquired in order to suppress the slip ratio, and the electric motor 44 is controlled so that the actual hydraulic pressure approaches the target hydraulic pressure. In S21, 22, 25, 26 are repeatedly executed, and if the determination in S25 becomes YES, the slip suppression control is ended.

[0086] Thus, in the present embodiment, in each of the brake ECUs 86, the slip suppression control is performed independently of each other, such as the target hydraulic pressure is acquired based on the slip state of the wheel W. However, it is not indispensable to perform the slip suppression control independently of each other, and the requested braking force can be acquired by the drive assist ECU 96 to supply to each of the brake ECUs 86.

[0087] Further, in the present embodiment, the detection of the presence or absence of each abnormality of the electric cylinder devices 12 is performed.

[0088] For example, as described above, each of the brake ECUs 86 outputs the acquired vehicle body speed Vha to the CAN 95, and each of the brake ECUs 86 determines whether there is an abnormal value among the four vehicle body speeds (Vha, Vhb, Vhc, Vhd), for example, based on the four vehicle body speeds (Vha, Vhb, Vhc, Vhd). When there is a value that is significantly different from the average value <Vh> of the above-described speeds among the four vehicle body speeds (Vha, Vhb, Vhc, Vhd), the value can be regarded as an abnormal value, and the brake ECU 86 that acquired the abnormal value is determined to be abnormal. Further, based on each of the determination results in the brake ECUs 86, the brake ECU 86 that is finally determined to be abnormal is determined by majority decision or the like. The determination of the brake ECU 86 that is finally abnormal, that is, the electric cylinder device 12 that is abnormal, can be performed by the drive assist ECU 96 or by one of the plurality of brake ECUs 86, or the like.

[0089] Further, it can also be configured that, in the drive assist ECU 96, the vehicle body speeds (Vha, Vhb, Vhc, Vhd) acquired by the brake ECUs 86 are received, an abnormal value is detected based on the four vehicle body speeds (Vha, Vhb, Vhc, Vhd), and the brake ECU 86 that outputs the abnormal value is determined to be abnormal.

[0090] Further, the method of detecting the presence or absence of abnormality of the electric cylinder device 12 is not limited, and the presence or absence of each abnormality of the electric cylinder device 12 can be detected based on the deviation of the actual hydraulic pressure from the target hydraulic pressure as the hydraulic pressure detected by the hydraulic pressure sensor 102, or based on the relationship between the hydraulic pressure detected by the hydraulic pressure sensor 102 and the stroke of the electric piston member 42 acquired based on the detection value of the rotation speed sensor 94, or the like.

[0091] Further, when it is detected that at least one of the four electric cylinder devices 12 is abnormal, the electric cylinder device 12 that is detected to be abnormal is stopped, and the normal electric cylinder device 12 is operated.

[0092] In Figure 10An example of a flowchart showing the abnormality-time brake control program is shown in FIG. 31. In S31, it is detected whether or not each of the electric cylinder devices 12 is abnormal, and in S32, it is determined whether or not at least one of the electric cylinder devices 12 is abnormal. In the case of NO in the determination, the control of the electric cylinder devices 12 is performed normally in S33. As described above, the electric motors 44 are controlled (for example, controlled so as to approach the target hydraulic pressure determined based on the relative positional relationship between the surrounding object and the host vehicle, the operation state of the brake operation member, and the like, in the manner detected by the hydraulic pressure sensor 102) in accordance with the execution of the normal-time brake control program shown in the flowchart. Figure 7 In the case of YES in S32, the abnormal electric cylinder device 12 is stopped, and the normal electric cylinder devices 12 are controlled in S34 and S35. For example, in the case where it is detected that the electric cylinder device 12RL of the left rear wheel WRL is abnormal, the electric cylinder device 12RL of the left rear wheel WRL is stopped, and the normal three electric cylinder devices, the electric cylinder devices 12FL, 12FR, and 12RR of the left front wheel WFL, the right front wheel WFR, and the right rear wheel WRR, are operated. For example, it is preferable that these electric cylinder devices 12FL, 12FR, and 12RR are controlled so as to suppress the yaw rate of the vehicle caused by the stop of the electric cylinder device 12RL of the left rear wheel WRL. In addition, the yaw rate can also be suppressed by the control of the regenerative braking force by the not-shown regenerative brake device.

[0093] Thus, in the present embodiment, four electric cylinder devices 12 are provided in the first vehicle, and thus even if a part of the four electric cylinder devices 12 is abnormal, the wheel cylinder 25 can be caused to generate the hydraulic pressure by the operation of the remaining electric cylinder devices 12, and thus the hydraulic brake system can be caused to continue to operate. In addition, even if the brake operation member is not operated, the hydraulic brake system can be caused to continue to operate in the case where a part of the four electric cylinder devices 12 is inoperable. Thus, the hydraulic brake system according to the present embodiment is a fail-operable system.

[0094] For example, in the case where the first vehicle is an automatic driving vehicle, there are cases where a part of the electric cylinder devices 12 is inoperable due to the fact that the driver fails to recognize that a bad situation has occurred in a part of the electric cylinder devices 12, the fact that the owner is negligent in maintenance, and the like. Even in these cases, the hydraulic brake system can be caused to continue to operate.

[0095] Further, since the power supply V is provided in one-to-one correspondence with each of the electric cylinder devices 12, even in the case where one of the four power supplies V is inoperable, the electric cylinder device 12 corresponding to the remaining power supply V can be caused to operate.

[0096] Also, since the brake ECU 86 is provided corresponding to each of the electric cylinder devices 12, even if one of the four brake ECUs 86 fails, the remaining electric cylinder devices 12 can be operated. Also, for the drive assist ECU 96, the operation state detection device 104, the surrounding information acquisition device 106, and the like, redundant configuration is possible.

[0097] As described above, a hydraulic brake system in which even if a part of the constituent elements thereof generates an abnormality, the hydraulic brake system can continue to operate through other constituent elements is referred to as a fail-operable hydraulic brake system, but in this case, depending on the probability of failure and the like, the hydraulic brake system is required to have three or more mutually independent hydraulic sources (for example, including the electric cylinder device 12). In contrast, in the present embodiment, the hydraulic brake system includes four electric cylinder devices 12 as hydraulic sources, and thus it can be said that the hydraulic brake system is fail-operable.

[0098] Also, in the hydraulic brake system according to the present embodiment, the electric cylinder device 12 is provided corresponding to each of the wheel cylinders 25, and the consumption power in each of the electric cylinder devices 12 is reduced. Thus, the number of electric motors 44 mounted on the vehicle increases, but since the increase in consumption power in the entire vehicle can be suppressed, four electric motors 44 can be mounted on the first vehicle.

[0099] For example, in a vehicle (an example of the first vehicle) in which the vehicle weight is 3.5 t to 8 t, a large brake force is required to stop the vehicle, and a large amount of working fluid is required for each of the wheel cylinders provided at the four wheels W. Thus, in the conventional hydraulic brake system, there is a problem in that the master cylinder, the electric supercharger, and the like must be upsized.

[0100] In contrast, in the hydraulic brake system according to the present embodiment, the electric cylinder device 12 is provided corresponding to each of the wheel cylinders 25. In other words, it is not necessary to make each of the electric cylinder devices 12 large in order to supply the amount of working fluid required for one wheel cylinder 25. Also, as described above, the stroke of the electric piston member 42 can be increased (for example, 50 mm or more) and the pressure receiving area of the piston 47 can be reduced (for example, 30 mm or less). Thus, the ratio of the pressure receiving area can be increased, and the axial force applied to the direct motion conversion device 48 can be reduced, and thus the consumption power of the electric motor 44 can be reduced. Thus, four electric motors 44 can be provided without upsizing the battery (not shown) provided in the first vehicle.

[0101] In addition, in the case where the first vehicle is an industrial vehicle, in order to prevent failure of the constituent elements of the hydraulic brake system such as the master cylinder, the electric supercharger, the solenoid valve device including one or more solenoid valves, and the like, the constituent elements and the like are generally replaced periodically. In particular, for the solenoid valve device and the like, it is difficult to individually replace and assemble each of the solenoid valves, and thus there are cases where the solenoid valve device as a whole (as a unit) is replaced. Therefore, there are problems such as an increase in the cost required for maintenance and a large amount of waste.

[0102] In contrast, in the present embodiment, instead of periodically replacing each of the solenoid cylinder devices 12 as a whole, it is possible to easily disassemble and replace the component that has generated an abnormality. For example, the rubber component such as the seal member 66 deteriorates easily compared to other metal components, but it is possible to replace only the seal member 66. As a result, it is possible to reduce the cost required for maintenance, and thus it is possible to reduce waste and achieve efficient use of resources.

[0103] In addition, in the case where the vehicle is large and the capacity of the hydraulic brake 10 is large, the hydraulic pressure at which the response is started is high, and the diameter of the wheel-side piston 27 is large, and thus a large amount of working fluid needs to be supplied before the response is started. On the other hand, if the diameter of the electric piston member 42 of the solenoid cylinder device 12 is reduced, the stroke of the electric piston member 42 before the response is started becomes long, and a delay in the response occurs. In contrast, there is a technique of weakening the magnetic field of the electric motor 44, and by this technique, a current slightly larger than the prescribed rotational speed is supplied to the electric motor 44 at the time of weak reaction force before the response is started, and thus the rotational speed of the electric motor 44 is increased, the advancing speed of the electric piston member 42 is increased, the stroke can be immediately increased, and a delay in the work can be suppressed.

[0104] In addition, even in the case where the solenoid cylinder device 12 has a configuration (referred to as a charging configuration) that is capable of supplying a large amount of flow to the wheel cylinder 25 at the time of starting of the work, it is possible to similarly increase the advancing speed of the electric piston member 42 before the response is started, and a delay in the work can be suppressed.

[0105] As described above, in the present embodiment, the hydraulic control device is constituted by the wheel speed sensor 100, the hydraulic pressure sensor 102, the operation state detection device 104, the surrounding information acquisition device 106, the drive assist ECU 96, the brake ECUs 86, and the like. The portion of S31 of the abnormality-time brake control program shown in the flowchart stored in the storage Figure 10 of the hydraulic control device, the portion that executes the abnormality-time brake control program, and the like constitute the abnormality detection portion.

[0106] Furthermore, the exchange of information between the drive assist ECU 96 and each of the brake ECUs 86, the load sharing, and the like are not limited to the description in the above embodiment, and can be arbitrarily set.

[0107] In addition, the vehicle equipped with the hydraulic brake system can be an autonomous vehicle, can be a manual driving vehicle of a line control type (a vehicle in which the operation state of the brake operation member is detected by the operation state detection device 104 and the electric cylinder device 12 is controlled based on the operation state of the brake operation member), or can be a vehicle in which a manual driving state and an autonomous driving state can be switched. Also, it can be applied to a vehicle having four or more wheels.

[0108] In addition, in the above-described embodiment, the electric cylinder device 12 is mounted on the first vehicle, but can be mounted on a second vehicle that is smaller in weight than the first vehicle. In the present hydraulic brake system, as shown in FIG. 6, of the hydraulic brakes 10 of the respective wheels of the front and rear and left and right provided in the second vehicle, the electric cylinder devices 12FL, 12FR are provided one-to-one via the liquid passages 74FL, 74FR in the hydraulic brakes 10FL, 10FR of the left and right front wheels WFL, WFR, and one electric cylinder device 12R is commonly provided in the hydraulic brakes 10RL, 10RR of the left and right rear wheels WRL, WRR. The wheel cylinders 25 of the hydraulic brakes 10RL, 10RR of the left and right rear wheels WRL, WRR are connected to each other by the liquid passage 74R, and the electric cylinder device 12R is provided in the liquid passage 74R. In addition, the power supplies VFL, VFR, VR are provided one-to-one in each of the electric cylinder devices 12FL, 12FR, 12R, respectively, and the brake ECUs 86FL, 86FR, 86R are provided. Figure 4

[0109] In addition, in the slip suppression control (for example, anti-lock control, traction control in the case where the rear wheels WRL, WRR are drive wheels, or the like), the electric cylinder device 12R increases or decreases the hydraulic pressure of the wheel cylinders 25RL, 25RR based on the smaller one of the wheel speeds in the left and right rear wheels WRL, WRR, in other words, based on the larger one of the slip rates. Such slip suppression control is referred to as low selection control.

[0110] Thus, the hydraulic brake system mounted on the second vehicle includes three electric cylinder devices 12, and therefore can be said to be a fail-operable system.

[0111] In addition, as shown in FIG. 7, the hydraulic brake system can be applied to a vehicle having four or more wheels. In the present hydraulic brake system, as shown in FIG. 7, of the hydraulic brakes 10 of the respective wheels of the front and rear and left and right provided in the vehicle, the electric cylinder devices 12FL, 12FR are provided one-to-one via the liquid passages 74FL, 74FR in the hydraulic brakes 10FL, 10FR of the left and right front wheels WFL, WFR, and one electric cylinder device 12R is commonly provided in the hydraulic brakes 10RL, 10RR of the left and right rear wheels WRL, WRR. The wheel cylinders 25 of the hydraulic brakes 10RL, 10RR of the left and right rear wheels WRL, WRR are connected to each other by the liquid passage 74R, and the electric cylinder device 12R is provided in the liquid passage 74R. In addition, the power supplies VFL, VFR, VR are provided one-to-one in each of the electric cylinder devices 12FL, 12FR, 12R, respectively, and the brake ECUs 86FL, 86FR, 86R are provided. Figure 5 ​As shown, the electric cylinder device 12 can also be mounted on a third vehicle that is smaller in weight than the second vehicle. In the present hydraulic brake system, one electric cylinder device 12F is commonly provided for the hydraulic brakes 10FL, 10FR of the left and right front wheels WFL, WFR, and one electric cylinder device 12R is commonly provided for the hydraulic brakes 10RL, 10RR of the left and right rear wheels WRL, WRR. Specifically, the wheel cylinders 25 of the hydraulic brakes 10FL, 10FR provided for the left and right front wheels WFL, WFR are connected to the front-wheel-side solenoid valve device 200F and the like via fluid passages 74FL, 74FR, and the electric cylinder device 12F is connected to the front-wheel-side solenoid valve device 200F. In addition, the wheel cylinders 25 of the hydraulic brakes 10RL, 10RR provided for the left and right rear wheels WRL, WRR are connected to the rear-wheel-side solenoid valve device 200R via fluid passages 74RL, 74RR, and the electric cylinder device 12R is connected to the rear-wheel-side solenoid valve device 200R.

[0112] In the present embodiment, the front-wheel-side solenoid valve device 200F and the rear-wheel-side solenoid valve device 200R are independent of each other in terms of hydraulic pressure, and a configuration is formed in which an influence caused by an abnormality in one of the front-wheel-side solenoid valve device 200F and the rear-wheel-side solenoid valve device 200R does not spread to the other. In addition, the solenoid valve device 200 is configured by the front-wheel-side solenoid valve device 200F and the rear-wheel-side solenoid valve device 200R and the like, but the solenoid valve device 200 includes a hydraulic pressure generating device 203 and the like. The hydraulic pressure generating device 203 can include, for example, pumps provided for the front-wheel-side solenoid valve device 200F and the rear-wheel-side solenoid valve device 200R, respectively, and a common electric motor that drives these pumps. The power supply VF, VR is provided for each of the electric cylinder devices 12F, 12R individually 1 to 1, and the power supply VE is provided for the solenoid valve device 200. Also, the brake ECU 86F, 86R, which is a computer-based device, is provided for each of the electric cylinder devices 12F, 12R individually 1 to 1, and one solenoid valve ECU 202 is provided for the solenoid valve devices 200F, 200R commonly.

[0113] Thus, the present hydraulic brake system is a front-and-rear dual system type fail-operational system that includes two electric cylinder devices 12F, 12R and one or more hydraulic pressure generating devices 203.

[0114] Also, as Figure 6As shown, the electric cylinder device 12 can be mounted on the fourth vehicle which is smaller in weight than the third vehicle. In the present hydraulic brake system, one electric cylinder device 12A is provided commonly to the hydraulic brakes 10FL, 10FR, 10RL, 10RR of the respective wheels WFL, WFR, WRL, WRR in the front and rear and left and right. The electric cylinder device 12A is connected to the solenoid valve device 210, and the wheel cylinders 25 of the four hydraulic brakes 10FL, 10FR, 10RL, 10RR are connected via the fluid passages 74FL, 74FR, 74RL, 74RR in the solenoid valve device 210. The hydraulic pressure generated by the electric cylinder device 12A is supplied to the wheel cylinders 25 of the four hydraulic brakes 10 via the solenoid valve device 210, and the hydraulic pressures of the four wheel cylinders 25 are individually controlled by the control of the solenoid valve device 210. The power supply VA, VE is provided to each of the electric cylinder device 12A and the solenoid valve device 210, and the brake ECU 86A and the solenoid valve ECU 212 are provided.

[0115] In addition, in the case where the fourth vehicle shown is a vehicle capable of manual driving, a manual hydraulic pressure source (for example, a master cylinder) 220 can be provided in parallel with the electric cylinder device 12A. For example, the manual hydraulic pressure source 220 is designed to be connected to both the electric cylinder device 12A and the solenoid valve device 210. In this case, in the event of failure of the electric cylinder device 12A, hydraulic pressure is generated in the manual hydraulic pressure source 220 by operation of a brake operation member 222, and is supplied to the wheel cylinders 25, whereby the hydraulic brakes 10 can be caused to generate hydraulic pressure. Figure 6

[0116] Thus, in the present hydraulic brake system, in the event of failure of the electric cylinder device 12A, the electric cylinder device 12A is stopped, and the vehicle can be stopped by manual operation of the brake operation member 222 by the driver. Further, such a hydraulic brake system can be referred to as a fail-safe system (which means that, in the event of abnormality, the operation of the electric cylinder device 12A is stopped, and the vehicle is stopped by manual operation).

[0117] Thus, by changing the number of vehicles to which the electric cylinder device 12 is mounted, such as the first vehicle, the second vehicle, the third vehicle, the fourth vehicle, and the like, which differ in weight, the same electric cylinder device 12 can be used. In other words, the brake force required for each of the first vehicle, the second vehicle, the third vehicle, and the fourth vehicle can be applied by one or more electric cylinder devices 12 which are common. The electric cylinder device 12 can be used commonly for a plurality of types of vehicles, and as a whole, cost reduction can be achieved. In particular, by being used for a small number of vehicles, cost reduction can be further achieved.

[0118] ​For example, the number of sales differs greatly depending on the size of the vehicle, and if a dedicated component is developed only for the vehicle with a small number of sales, the component cost rises because the development cost, mold cost, and the like are distributed to a small number of units. However, if the same electric cylinder device 12 is used for both the vehicle with a large number of sales and the vehicle with a small number of sales, the cost of one electric cylinder device 12 can be suppressed despite the difference in the number of units, and as a result, the overall cost can be suppressed.

[0119] Also, by changing the number of electric cylinder devices 12 depending on the presence or absence of automatic driving and the like, it is possible to change the hydraulic system to be fail-operable or fail-safe. In addition, it is not necessary to develop a hydraulic system for each vehicle type, and thus it is possible to suppress a new cost increase factor.

[0120] In addition, the electric cylinder device 12 has the same configuration, and by changing each element and the like, it is possible to commonly apply to a plurality of types of vehicles. It is possible to commonly apply to a plurality of types of vehicles without performing the same configuration, that is, a new configuration design. In other words, in the present specification, commonly using the electric cylinder device 12 means "using the electric cylinder device 12 having the same configuration", and each element such as the capacity of the electric motor 44, the shape of the electric piston member 42, and the bore is not limited.

[0121] For example, by changing the number of turns of the coil and the coil diameter of the electric motor 44 depending on the size of the vehicle, the vehicle type, and the like, it is possible to adjust the size of the axial force. In addition, it is possible to change the maximum stroke of the electric piston member 42 and the like depending on the capacity of the wheel cylinder 25 and the like to which it is connected.

[0122] In this way, by changing each element of the electric cylinder device 12, it is possible to one-to-one correspondingly provide the hydraulic brake 10 and the electric cylinder device 12 in a plurality of types of vehicles, for example.

[0123] In addition, the electric cylinder device 12 can be directly connected to the wheel cylinder 25 or connected to a device such as a solenoid valve.

[0124] Also, the electric cylinder device 12 can be provided one-to-one, one-to-many, and the like, and the number of electric cylinder devices 12 can be designed depending on the requested braking force. In addition, the electric cylinder device 12 can be provided by being connected to a fluid passage extending from the wheel cylinder of the hydraulic brake provided to the wheel W, and thus the mounting position and the like can be freely determined. Also, the stroke of the electric piston member 42, the diameter of the electric piston member 42, and the like in each of the electric cylinder devices 12 can be designed in correspondence with the requested braking force. In this way, the electric cylinder device 12 has high versatility, and is easy to use. In addition, since the electric cylinder device 12 has high versatility, reuse of the electric cylinder device 12 or its constituent elements is possible, and thus efficient use of resources can be achieved.

[0125] In addition, the configuration of the electric cylinder device 12 is not limited. It is not indispensable that the electric motor 44 is disposed coaxially with the rod portion 46, and it can be disposed in a parallel state.

[0126] Also, a speed reducer can be disposed between the electric motor 44 and the rod portion 46.

[0127] Also, in the above-described embodiment, the hydraulic control device includes the drive assist ECU 96, the brake ECU 86, and the like, but the hydraulic control device can include one ECU or the like, and the configuration of the hydraulic control device is not limited.

[0128] In addition, in the above-described embodiment, in the present hydraulic brake system, the case where the hydraulic pressure of the wheel cylinder 25 is controlled so as to approach the target hydraulic pressure determined based on the situation of the surroundings and the operation state of the brake operation member, and the case where the slip suppression control is performed, are described, but these controls are not limited, and various controls such as the front-rear brake force distribution control can be performed.

[0129] In addition, the hydraulic brake 10 can be a disc brake, a drum brake, or the like, and the present application can be implemented in various modes in which various modifications and improvements based on the knowledge of a person skilled in the art are implemented.

[0130] [INVENTION THAT CAN BE CLAIMED]

[0131] (1) A hydraulic brake system, comprising:

[0132] a hydraulic brake provided for each of a plurality of wheels of a vehicle and suppressing rotation of the wheel by hydraulic pressure of a hydraulic chamber of a wheel cylinder; and

[0133] an electric cylinder device provided corresponding to one or more of the plurality of hydraulic brakes, wherein

[0134] the plurality of electric cylinder devices each include a housing, a piston that is capable of being fitted to the housing in a liquid-tight and slidable manner, an electric motor as a drive source, a linear motion and rotation conversion device that converts rotation of the electric motor into linear movement of the piston, and a volume change chamber provided in front of the piston and connected to the hydraulic chamber of the wheel cylinder of the one or more hydraulic brakes.

[0135] The hydraulic brake and the electric cylinder device can be provided in a one-to-one correspondence or in a two-to-one correspondence, but in the hydraulic brake system described in the present item, a plurality of electric cylinder devices are included.

[0136] (2) The hydraulic brake system according to the item (1), wherein

[0137] The plurality of electric cylinder devices each include a reservoir that stores working fluid returned from a hydraulic chamber of a wheel cylinder of the one or more hydraulic brakes.

[0138] (3) The hydraulic brake system according to item (2), wherein

[0139] In each of the plurality of electric cylinder devices,

[0140] In a portion of the housing that surrounds the volume change chamber, two cylinder ports are disposed apart from each other in the axial direction of the piston,

[0141] The reservoir is connected to a rear-side cylinder port of the two cylinder ports that is located on the rear side in the direction of piston retraction,

[0142] The rear-side cylinder port is in an open state when the piston is in the retracted end position, but is switched to a closed state as the piston advances.

[0143] The cylinder ports are disposed open toward the volume change chamber.

[0144] (4) The hydraulic brake system according to item (3), wherein

[0145] A front-side cylinder port of the two cylinder ports that is located on the front side in the direction of piston advancement is directly connected to a hydraulic chamber of a wheel cylinder of the one or more hydraulic brakes.

[0146] The front-side cylinder port is always in an open state, which allows the volume change chamber to communicate with the wheel cylinder. Additionally, the volume change chamber and the wheel cylinder are connected via a liquid passage, but there are cases where an electromagnetic valve or the like is provided in the liquid passage and cases where no electromagnetic valve or the like is provided.

[0147] (5) The hydraulic brake system according to any one of items (1) to (4), wherein

[0148] The hydraulic brake system includes a plurality of power sources,

[0149] Each of the plurality of power sources is provided in one-to-one correspondence with each of the plurality of electric cylinder devices.

[0150] It is preferable that the plurality of power sources be independent of each other.

[0151] (6) The hydraulic brake system according to any one of items (1) to (5), wherein

[0152] The hydraulic brake system includes a plurality of computer-based control units,

[0153] Each of the plurality of control units is provided in one-to-one correspondence with each of the plurality of electric cylinder devices.

[0154] (7) The hydraulic brake system according to any one of (1) to (6), wherein

[0155] Each of the plurality of electric cylinder devices is provided corresponding to each of the plurality of hydraulic brakes.

[0156] (8) The hydraulic brake system according to any one of (1) to (7), wherein

[0157] The hydraulic brake system includes three or more electric cylinder devices as the plurality of electric cylinder devices.

[0158] For example, the vehicle includes four wheels as the plurality of wheels,

[0159] The hydraulic brakes are provided corresponding to the four wheels,

[0160] One of the three or more electric cylinder devices as the plurality of electric cylinder devices is provided corresponding to one or two of the four hydraulic brakes.

[0161] (9) The hydraulic brake system according to any one of (1) to (8), wherein

[0162] The hydraulic brake system includes two electric cylinder devices as the plurality of electric cylinder devices, and one or more hydraulic pressure generating devices that form a different configuration from the electric cylinder devices.

[0163] The hydraulic pressure generating device can be a power hydraulic pressure generating device such as a pump device (a device that is not a manual hydraulic pressure generating device). The hydraulic pressure generating device provided in the hydraulic brake system can be one or two.

[0164] For example, it can be a hydraulic brake system in which,

[0165] The vehicle includes four wheels at the front, rear, left, and right,

[0166] The hydraulic brakes are provided corresponding to the four wheels at the front, rear, left, and right,

[0167] Each of the two electric cylinder devices as the plurality of electric cylinder devices is provided corresponding to one hydraulic brake for every two wheels among the four wheels,

[0168] One or more first solenoid valves are provided between one of the two electric cylinder devices and the two hydraulic brakes corresponding thereto, and one or more second solenoid valves different from the first solenoid valves are provided between the other of the two electric cylinder devices and the two hydraulic brakes corresponding thereto.

[0169] In the above-described embodiments, one of the front-wheel-side electromagnetic valve device and the rear-wheel-side electromagnetic valve device is constituted by one or more first electromagnetic valves, and the other of the front-wheel-side electromagnetic valve device and the rear-wheel-side electromagnetic valve device is constituted by one or more second electromagnetic valves.

[0170] (10) The hydraulic brake system according to any one of (1) to (9), wherein

[0171] The hydraulic brake system includes a hydraulic control device that controls the hydraulic pressure of the hydraulic chambers of the wheel cylinders of the plurality of hydraulic brakes by controlling the supply current to each of the plurality of electric motors of the plurality of electric cylinder devices, respectively.

[0172] The hydraulic control device is configured to cause the volume of the volume change chamber to decrease or increase by advancing or retreating the piston by controlling the supply current to the electric motor in each of the plurality of electric cylinder devices, and further cause the hydraulic pressure of the hydraulic chambers of the wheel cylinders of the plurality of hydraulic brakes to increase or decrease.

[0173] The hydraulic control device can include a plurality of control sections.

[0174] (11) The hydraulic brake system according to (10), wherein

[0175] The hydraulic brake system includes:

[0176] a surrounding information acquisition device that acquires information of a surrounding of the vehicle, and

[0177] a wheel speed detection device that is provided corresponding to each of the plurality of wheels and detects a wheel speed that is a rotational speed of the wheel, respectively,

[0178] The hydraulic control device is configured to:

[0179] control the supply current to the plurality of electric motors so that the respective hydraulic pressures of the wheel cylinders of the plurality of hydraulic brakes respectively approach target hydraulic pressures that are determined based on at least the information of the surrounding of the vehicle acquired by the surrounding information acquisition device, and

[0180] control the supply current to the plurality of electric motors so that the respective slip states of the plurality of wheels based on the respective wheel speeds of the plurality of wheels detected by the plurality of wheel speed detection devices are within an appropriate range determined by a friction coefficient of a road surface.

[0181] (12) The hydraulic brake system according to (10), wherein

[0182] The hydraulic brake system includes:

[0183] An operation state detection device detects an operation state of a brake operation member that can be operated by a driver.

[0184] A surrounding information acquisition device acquires information about a surrounding of the vehicle, and

[0185] A wheel speed detection device is provided corresponding to each of the plurality of wheels and detects a wheel speed as a rotational speed of the wheel,

[0186] The hydraulic control device is configured to:

[0187] The supply currents to the plurality of electric motors are controlled so that the respective hydraulics of the wheel cylinders of the plurality of hydraulic brakes respectively approach target hydraulics that are determined based on at least one of the information about the surrounding of the vehicle acquired by the surrounding information acquisition device and the operation state of the brake operation member detected by the operation state detection device, and

[0188] The supply currents to the plurality of electric motors are controlled so that the respective slip states of the plurality of wheels based on the respective wheel speeds of the plurality of wheels detected by the plurality of wheel speed detection devices are within an appropriate range determined by a friction coefficient of a road surface.

[0189] In a case where the vehicle is an autonomous vehicle and does not include a brake operation member that can be operated by a driver, the target hydraulics are determined based on the information about the surrounding acquired by the surrounding information acquisition device, but in a case where the vehicle includes the brake operation member, the target hydraulics are acquired also in consideration of the operation state of the brake operation member. For example, the target hydraulics can be acquired based on at least one of the brake operation state and the information about the surrounding.

[0190] (13) The hydraulic brake system according to any one of (10) to (12), wherein

[0191] The hydraulic control device includes an abnormality detection unit that detects presence or absence of an abnormality of each of the plurality of electric cylinder devices, and in a case where one or more of the plurality of electric cylinder devices is detected as being abnormal by the abnormality detection unit, the hydraulic control device stops the one or more electric cylinder devices detected as being abnormal and controls one or more electric cylinder devices from which the one or more electric cylinder devices detected as being abnormal is excluded from the plurality of electric cylinder devices.

[0192] In the hydraulic brake system described in this item, each of one or more electric cylinder devices from which one or more electric cylinder devices detected as being abnormal is excluded from the plurality of electric cylinder devices can be controlled independently of each other.

[0193] (14) The hydraulic brake system according to any one of (1) to (13), wherein

[0194] The housing includes a first housing that houses the electric motor, and a second housing in which the piston is slidably fitted in a liquid-tight manner,

[0195] The first housing and the second housing are detachably assembled.

[0196] The first housing and the second housing are coupled, for example, by a coupling device including a threaded member and a nut member. Thus, by removing the nut member, the housing can be separated into the first housing and the second housing to individually remove the electric motor, the piston, the linear-rotary motion conversion device, and the like. The first housing corresponds to the rear housing 40r, and the second housing corresponds to the front housing 40f. The first housing 40r and the second housing 40f are coupled, for example, by a coupling device including a threaded member 80 and a nut member 82.

[0197] In addition, a cylinder bore is provided in the second housing, but the cylinder bore can have an elongated shape, for example, such that the ratio of the diameter to the length (diameter / length) is less than 0.6.

[0198] (15) The hydraulic brake system according to any one of (1) to (14), wherein

[0199] The hydraulic brake system does not include a manual hydraulic source that generates hydraulic pressure due to an operation of a brake operation member by a driver, and a pump hydraulic source that has a pump device and generates hydraulic pressure due to an operation of the pump device.

[0200] In the electric cylinder device, a manual hydraulic source, a pump hydraulic source, or the like is not connected.

[0201] (16) The hydraulic brake system according to any one of (1) to (15), wherein

[0202] Between the electric cylinder device and the hydraulic brake, an electromagnetic valve that operates by application of voltage to a solenoid is not provided.

Claims

1. A hydraulic brake system comprising: a hydraulic brake provided for each of a plurality of wheels of a vehicle and suppressing rotation of the wheel by hydraulic pressure of a hydraulic chamber of a wheel cylinder, respectively; an electric cylinder device provided corresponding to each of the plurality of hydraulic brakes, respectively; and a power source provided corresponding to each of the plurality of electric cylinder devices, respectively, wherein the plurality of electric cylinder devices each include a housing, a piston capable of being slidably fitted to the housing in a liquid-tight manner, an electric motor as a drive source, a linear motion and rotation conversion device that converts rotation of the electric motor to linear movement of the piston, and a volume change chamber provided in front of the piston and connected to the hydraulic chamber of the wheel cylinder of the hydraulic brake, the electric cylinder devices are provided as four or more, and the power source is provided as four or more, each of the four or more electric cylinder devices is provided corresponding to each of the four or more hydraulic brakes on a one-to-one basis, on a downstream side of each of the four or more electric cylinder devices, an electromagnetic valve that operates by application of voltage to a solenoid is not provided, the four or more electric cylinder devices are hydraulically independent from each other, the hydraulic brake system does not include a manual hydraulic source that generates hydraulic pressure due to operation of a brake operation member by a driver and is capable of supplying hydraulic pressure to one or more of the four or more wheel cylinders, the hydraulic brake system comprising: an operation state detection device that detects an operation state of a brake operation member that is capable of being operated by a driver; a surrounding information acquisition device that acquires information of a surrounding of the vehicle; a wheel speed detection device provided corresponding to each of the four or more wheels and detecting a rotational speed of the wheel, respectively; and a hydraulic pressure control device that controls hydraulic pressure of the hydraulic chamber of the wheel cylinder of the four or more hydraulic brakes by controlling supply current to the electric motor of each of the four or more electric cylinder devices, respectively, the hydraulic pressure control device being configured to: control the supply current to each of the four or more electric motors so that the hydraulic pressure of each of the four or more wheel cylinders respectively approaches a target hydraulic pressure determined based on at least one of the information of the surrounding of the vehicle acquired by the surrounding information acquisition device and the operation state of the brake operation member detected by the operation state detection device, respectively, and control the supply current to each of the four or more electric motors so that a slip state of each of the four or more wheels based on the rotational speed of each of the four or more wheels detected by the four or more wheel speed detection devices is within an appropriate range determined by a friction coefficient of a road surface, respectively. Further comprising an abnormality detection unit that detects the presence or absence of an abnormality in each of the four or more electric cylinder devices, and in a case where one or more of the four or more electric cylinder devices is detected as abnormal by the abnormality detection unit, stopping the one or more electric cylinder devices detected as abnormal, and controlling one or more electric cylinder devices from which the one or more electric cylinder devices detected as abnormal are excluded.

2. The hydraulic brake system according to claim 1, wherein Each of the four or more electric cylinder devices includes a reservoir that stores working fluid returned from a hydraulic chamber of the wheel cylinder.

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