JP2006306221A - Brake device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To ensure pedal reaction force while simplifying a structure by abolishing a stroke simulator, in a brake device embodied as a by-wire system. <P>SOLUTION: Normally, while an atmosphere shut-off valve 19 is opened to respectively communicate a master cylinder 10 and a motor cylinder 20 to a reservoir 18 and a wheel cylinder 16, pedal reaction force is added by reaction force springs 15a, 15b of the master cylinder 10. Therefore, even in case that the master cylinder 10 does not generate brake fluid pressure, the pedal reaction force can be generated on a brake pedal 11 without requiring a stroke simulator, so that parts count can be reduced. Under an abnormal condition, an atmosphere shut-off valve 19 is closed to shut off the master cylinder 10 from the reservoir 18 and communicate that to the wheel cylinder 16, thereby actuating the wheel cylinder 16 without requiring the motor cylinder 20. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a brake device that brakes a wheel with a brake fluid pressure that is electrically generated by a brake fluid pressure generating means during normal operation and brakes a wheel with a brake fluid pressure that is generated by a master cylinder by a driver's brake operation when an abnormality occurs.

When the oil pump that generates the brake fluid pressure is in normal operation, the solenoid cylinder shuts off the communication between the master cylinder that generates the brake fluid pressure and the disc brake device that brakes the wheels when the driver depresses the brake pedal. Then, when the disc brake device is operated with the brake fluid pressure generated by the oil pump, and when the oil pump cannot be operated, the electromagnetic on-off valve is opened and the disc brake device is operated with the brake fluid pressure generated by the master cylinder. A so-called brake-by-wire type brake device that is operated is known from Japanese Patent Application Laid-Open No. 2004-122867.
JP 2005-14883 A

  By the way, in this type of brake-by-wire type brake device, a stroke simulator in which a piston biased by a spring is housed in the cylinder is provided, and the master cylinder does not substantially generate brake fluid pressure at a normal time. The stroke simulator applies pedal reaction force to the brake pedal to eliminate the driver's discomfort. Such a stroke simulator requires an on-off valve that controls the communication / blocking between the stroke simulator and the master cylinder, which further increases the number of parts.

  The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a brake-by-wire brake device that eliminates a stroke simulator and ensures pedal reaction force while simplifying the structure. And

  In order to achieve the above object, according to the first aspect of the present invention, a reservoir for storing brake fluid, a master cylinder that includes a reaction spring therein and generates brake fluid pressure by a driver's brake operation, The brake cylinder includes a wheel cylinder capable of braking the wheel by brake fluid pressure, and a brake fluid pressure generating means for electrically generating brake fluid pressure. A brake device is proposed in which a pedal reaction force is applied by a reaction force spring of the master cylinder in a state where the master cylinder communicates with the brake cylinder, and the master cylinder is disconnected from the reservoir and communicated with the wheel cylinder when an abnormality occurs.

  According to the invention described in claim 2, in addition to the structure of claim 1, the brake fluid pressure generating means has a port that closes when the brake fluid pressure is generated, and the port is closed when it is normal. A brake device is proposed which is characterized in that the wheel cylinder is disconnected from the master cylinder.

  The motor cylinder 20 and the hydraulic pump 34 of the embodiment correspond to the brake hydraulic pressure generating means of the present invention.

  According to the first aspect of the present invention, the pedal reaction force is applied by the reaction force spring of the master cylinder in a state where the master cylinder communicates with the reservoir and the brake fluid pressure generating means communicates with the wheel cylinder. Even in a state where the cylinder does not generate brake fluid pressure, it is possible to generate a pedal reaction force on the brake pedal without requiring a stroke simulator, which can contribute to a reduction in the number of parts. Further, in the event of an abnormality, the wheel cylinder can be operated without requiring a brake fluid pressure generating means by shutting off the master cylinder from the reservoir and communicating with the wheel cylinder.

  According to the configuration of the second aspect, since the brake fluid pressure generating means has a port that closes when the brake fluid pressure is generated, the wheel cylinder is shut off from the master cylinder without requiring a special valve. Pressure can be prevented from escaping into the reservoir.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on examples of the present invention shown in the accompanying drawings.

  1 and 2 show a first embodiment of the present invention. FIG. 1 is a hydraulic system diagram at the time of normal operation of the vehicle brake device, and FIG. 2 is an hydraulic system diagram at the time of abnormality corresponding to FIG. is there.

  As shown in FIG. 1, the tandem master cylinder 10 includes first and second output ports 12 a and 12 b that output brake fluid pressure in accordance with the pedaling force applied by the driver to the brake pedal 11. The port 12a is connected to the disc brake device 13 for the left front wheel, for example, and the second output port 12b is connected to the disc brake device for the right front wheel, for example. The master cylinder 10 includes a pair of pistons 14a and 14b, and reaction force is applied to the pistons 14a and 14b by reaction force springs 15a and 15b. In the drawing, only one brake system connected to the first output port 12a is shown, and the other brake system connected to the second output port 12b is not shown, but the structures of the one and other brake systems are substantially the same. Are identical. Hereinafter, one brake system connected to the first output port 12a will be described.

  The first output port 12a of the master cylinder 10 and the wheel cylinder 16 of the disc brake device 13 are connected by liquid passages 17a, 17b, and 17c, and the liquid passage 17b and the reservoir 18 of the master cylinder 10 are connected by a liquid passage 17d. . Further, an atmospheric shutoff valve 19 that is a normally closed electromagnetic valve is disposed between the liquid passage 17b and the liquid passage 17d. The motor cylinder 20 is disposed between the liquid path 17b and the liquid path 17c. The piston 21 slidably fitted to the motor cylinder 20 is driven by the electric motor 22 via the speed reduction mechanism 23, and can generate brake fluid pressure in the fluid chamber 24 formed on the front surface of the piston 21. it can. The port 25a connecting the liquid chamber 24 of the motor cylinder 20 to the liquid path 17b is closed when the piston 21 advances, and the port 25b connecting the liquid chamber 24 of the motor cylinder 20 to the liquid path 17c is always open regardless of the position of the piston 21. To do.

  An electronic control unit (not shown) that controls the operation of the air shutoff valve 19 and the electric motor 22 of the motor cylinder 20 includes a pedaling force sensor 26 that detects the pedaling force of the brake pedal 11, and a fluid pressure of the fluid passage 17 c connected to the wheel cylinder 16. Is connected to a hydraulic pressure sensor 27 for detecting

  Next, the operation of the first embodiment of the present invention having the above configuration will be described.

  In the normal state shown in FIG. 1, the solenoid of the atmospheric shutoff valve 19 is excited and opened by a command from the electronic control unit. Even if the driver depresses the brake pedal 11 in this state, the first output port 12a of the master cylinder 10 communicates with the reservoir 18 through the path of the liquid path 17a → the liquid path 17b → the atmospheric shut-off valve 19 → the liquid path 17d. No pressure is generated. At the same time, the electric motor 22 operates and the piston 21 of the motor cylinder 20 moves forward via the speed reduction mechanism 23, so that the brake fluid pressure generated in the fluid chamber 24 is transferred from the port 25b to the wheel cylinder via the fluid path 17c. 16 is transmitted to brake the front wheels. At this time, the operation amount of the brake pedal 11 is detected by the stroke sensor 26, the electronic control unit sets the target brake fluid pressure based on the pedal operation amount, and the brake fluid pressure detected by the fluid pressure sensor 27 is the target brake. The electronic control unit performs feedback control of the operation of the electric motor 22 so that the hydraulic pressure is reached. Further, since the port 21a of the motor cylinder 20 is closed at the same time as the piston 21 moves forward, there is no possibility that the brake fluid pressure generated in the fluid chamber 24 escapes to the reservoir 18 from the open air shutoff valve 19.

  In the normal state described above, when the driver steps on the brake pedal 11, the reaction force springs 15a and 15b of the master cylinder 10 are compressed, so that a predetermined pedal reaction force is applied to the brake pedal 11. Therefore, although the disc brake device 13 is actually operated by the driving force of the electric motor 22, an operation feeling equivalent to that when the disc brake device 13 is operated by the driver's stepping force can be obtained. it can. As described above, even if the stroke simulator that has been conventionally required is abolished, a predetermined reaction force can be applied to the brake pedal 11, so that the number of parts can be reduced and the structure can be simplified.

  However, in order to obtain a pedal reaction force that is comfortable for the driver, it is necessary to set the spring constants of the reaction force springs 15a and 15b to be higher than the spring constant of the normal reaction force spring.

  When the power supply is lost due to battery disconnection or the like, the air shut-off valve 19 is closed as shown in FIG. 2 to cut off the communication between the master cylinder 10 and the reservoir 18. As a result, the brake fluid pressure generated by the master cylinder 10 when the driver depresses the brake pedal 11 is the first output port 12a of the master cylinder 10 → the fluid passage 17a → the fluid passage 17b → the port 25a of the motor cylinder 20 → the motor cylinder. 20 is transmitted to the wheel cylinder 16 of the disc brake device 13 through the path of the liquid chamber 24 → the port 25b of the motor cylinder 20 → the liquid path 17c, and the front wheels are braked.

  Even if the power supply fails and the air shutoff valve 19 and the electric motor 22 become inoperable, the driver steps on the brake pedal 11 and the brake fluid pressure generated by the master cylinder 10 obstructs the front wheel cylinder 16. The vehicle can be operated without any trouble, and the vehicle can be safely stopped even in the event of an abnormality.

  In the case of the above-described abnormality, the pedal reaction force generated by operating the wheel cylinder 16 with the brake fluid pressure generated by the master cylinder 10 is added to the pedal reaction force generated by the reaction force springs 15a and 15b. Although the pedal feeling of the pedal 11 is heavier than normal, safety is given priority over the pedal feeling when there is an abnormality, so there is no problem.

  According to the first embodiment, not only is the stroke simulator unnecessary, but the number of parts can be greatly reduced by limiting the number of valves to only one of the atmospheric cutoff valves 19.

  Next, a second embodiment of the present invention will be described with reference to FIGS. In the second embodiment, the same reference numerals as those in the first embodiment are assigned to the components corresponding to the components in the first embodiment, and the duplicate description is omitted.

  The first output port 12a of the master cylinder 10 and the wheel cylinder 16 of the disc brake device 13 are connected via a liquid path 31a and a liquid path 31b, and a normally open solenoid valve is provided between the liquid path 31a and the liquid path 31b. A pedal force shut-off valve 32 is arranged. A liquid path 31c branched from the liquid path 31b communicates with the reservoir 18 via a pressurizing valve 33 made of a normally closed electromagnetic valve, a liquid path 31d, and a hydraulic pump 34. Although this reservoir 18 is drawn separately from the reservoir 18 of the master cylinder 10, it may be the same. An accumulator 35 is connected to the liquid passage 31d to which the hydraulic pump 34 is connected.

  The liquid passage 31e branched from the middle portion of the liquid passage 31c is a pressure reducing valve 36 made of a normally closed electromagnetic valve, a liquid passage 31f communicating with the liquid passage 31a, an air shut-off valve 19 made of a normally closed electromagnetic valve, The reservoir 18 is communicated with the liquid passage 31g.

  Next, the operation of the second embodiment of the present invention having the above configuration will be described.

  In the normal state shown in FIG. 3, the solenoid of the atmospheric cutoff valve 19 is excited and opened by a command from the electronic control unit, and the solenoid of the pedaling force cutoff valve 32 is excited and closed. Even if the driver depresses the brake pedal 11 in this state, the first output port 12a of the master cylinder 10 communicates with the reservoir 18 through the path of the liquid path 31a → the liquid path 31f → the atmospheric shut-off valve 19 → the liquid path 31g. No pressure is generated.

  At the same time, the solenoid of the pressurizing valve 33 is energized to open, and the brake hydraulic pressure pumped up from the reservoir 18 by the hydraulic pump 34g and accumulated in the accumulator 35 is the fluid path 31d → pressure valve 33 → liquid path 31c → liquid path. It is transmitted to the wheel cylinder 16 through the path 31b to brake the front wheel. At this time, by opening and closing the pressure reducing valve 36, a part of the brake fluid pressure in the liquid path 31c is released to the reservoir 18 through the path of the liquid path 31e → the pressure reducing valve 36 → the liquid path 31f → the air shutoff valve 19 → the liquid path 31g. The braking force can be controlled by adjusting the brake fluid pressure transmitted to the wheel cylinder 16. In the second embodiment, the electronic control unit opens and closes the pressure reducing valve 36 so that the pedal force of the brake pedal 11 is detected by the pedal force sensor 26 and the brake fluid pressure detected by the fluid pressure sensor 27 becomes a value corresponding to the pedal force. Feedback control.

  In the normal state described above, when the driver steps on the brake pedal 11, the reaction force springs 15a and 15b of the master cylinder 10 are compressed, so that a predetermined pedal reaction force is applied to the brake pedal 11. Therefore, although the disc brake device 13 is actually operated with the brake fluid pressure accumulated in the accumulator 35, the operation feeling is equivalent to that when the disc brake device 13 is operated with the driver's pedal effort. Obtainable. As described above, even if the stroke simulator that has been conventionally required is abolished, a predetermined reaction force can be applied to the brake pedal 11, so that the number of parts can be reduced and the structure can be simplified.

  When the power supply is lost due to battery disconnection or the like, the air shut-off valve 19, the pressurizing valve 33 and the pressure reducing valve 36 are closed and the pedal force shut-off valve 32 is opened as shown in FIG. As a result, the brake fluid pressure generated by the master cylinder 10 when the driver depresses the brake pedal 11 does not escape to the reservoir 18, and the first output port 12 a → the fluid path 31 a → the treading force cutoff valve 32 → the fluid path 31 b of the master cylinder 10. Is transmitted to the wheel cylinder 16 of the disc brake device 13 through this path, and the front wheels are braked.

  Thus, even if the power supply fails and the atmospheric shutoff valve 19, the pressurizing valve 33, the pressure reducing valve 36, the stepping force shutoff valve 32, and the hydraulic pressure pump 34 become inoperable, the driver steps on the brake pedal 11 and master cylinder 10 The wheel cylinder 16 of the front wheel can be operated without any trouble by the brake fluid pressure generated, and thus the vehicle can be safely stopped even in the event of an abnormality.

  Although the embodiments of the present invention have been described above, various design changes can be made without departing from the scope of the present invention.

Hydraulic system diagram at normal time of the vehicle brake device according to the first embodiment Hydraulic system diagram at the time of abnormality corresponding to FIG. Hydraulic system diagram at normal time of vehicle brake device according to second embodiment Hydraulic system diagram at the time of abnormality corresponding to FIG.

Explanation of symbols

10 master cylinder 15a reaction force spring 15b reaction force spring 16 wheel cylinder 18 reservoir 20 motor cylinder (brake fluid pressure generating means)
25a port 34 hydraulic pump (brake hydraulic pressure generating means)

Claims (2)

A reservoir (18) for storing brake fluid;
A master cylinder (10) having reaction force springs (15a, 15b) inside and generating brake fluid pressure by a driver's brake operation;
A wheel cylinder (16) capable of braking the wheel by brake fluid pressure;
Brake fluid pressure generating means (20, 34) for electrically generating brake fluid pressure;
With
Under normal conditions, the master cylinder (10) is connected to the reservoir (18) and the brake fluid pressure generating means (20, 34) is connected to the wheel cylinder (16). 15b), the pedal reaction force is applied,
A brake device characterized by disconnecting the master cylinder (10) from the reservoir (18) and communicating with the wheel cylinder (16) in the event of an abnormality. The brake fluid pressure generating means (20) has a port (25a) that closes when the brake fluid pressure is generated. When the port (25a) closes normally, the wheel cylinder (16) is disconnected from the master cylinder (10). The brake device according to claim 1, wherein:

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