JP2006056449A - Brake system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a brake-by-wire type brake system, capable of avoiding execution of unnecessary functions of a stroke simulator with a simple structure during its abnormal operation. <P>SOLUTION: Pedal effort shut-down valves 17a, 17b close during a normal operation of the brake-by-wire type brake system, and wheel cylinders 16a, 16b are operated by a brake fluid pressure which is generated by brake cylinders 18a, 18b driven by motors 20a, 20b. At this time, an operational reaction force is generated in a brake pedal 12 by stroke simulators 31a, 31b linked to rear-part output ports 30a, 30b of a master cylinder 10. The pedal effort shut-down valves 17a, 17b open during an abnormal operation, and the wheel cylinders 16a, 16b are operated by a brake fluid pressure supplied from front-part output ports 11a, 11b of the master cylinder 10. At that time, the rear-part output ports 30a, 30b are blocked by a forward movement of a piston of the master cylinder 10, causing the stroke simulators 31a, 31b not to function, thus preventing occurrence of a sense of incongruity in a braking operation. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention operates the wheel cylinder with the brake fluid pressure generated by the brake fluid pressure generating means driven by the actuator in the normal state, and the brake fluid pressure generated by the master cylinder by the driver's brake operation when the actuator becomes inoperable. The present invention relates to a brake device that operates a wheel cylinder.

When the pump that generates the brake fluid pressure is operating normally, the driver depresses the brake pedal and the communication between the master cylinder that generates the brake fluid pressure and the wheel cylinder that brakes the wheels is shut off by a multi-position valve that closes the valve. In the state, the wheel cylinder is operated with the brake hydraulic pressure generated by the pump, and when the pump becomes inoperable, the multi-position valve is opened and the wheel cylinder is operated with the brake hydraulic pressure generated by the master cylinder. In a so-called brake-by-wire brake system, brake fluid pressure is applied between the master cylinder and the multi-position valve to prevent the driver from feeling uncomfortable by making the brake pedal stroke normally even when the multi-position valve is closed normally. The following patent document is provided with a stroke simulator as a reaction force applying means for absorbing. It is known by.
JP 58-39551 A

  By the way, when operating the wheel cylinder with the brake fluid pressure generated by the master cylinder due to the driver's brake operation in the event of an abnormality, part of the brake fluid pressure generated by the master cylinder is absorbed by the stroke simulator, so the same braking force is applied. There is a problem that the stroke of the brake pedal required for generating the brake pedal becomes large and the driver feels uncomfortable. In order to solve this problem, the above conventional one is provided with an electromagnetic valve that communicates the stroke simulator with the master cylinder when it is normal, and disables the stroke simulator by interrupting the communication when there is an abnormality. There was a problem that the structure of the brake system was complicated.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to prevent a stroke simulator from performing unnecessary functions in a brake-by-wire type braking device with a simple structure in the event of an abnormality. .

  In order to achieve the above object, according to the invention described in claim 1, a master cylinder that generates a brake fluid pressure by a driver's brake operation, a wheel cylinder that operates with the brake fluid pressure to brake a wheel, Brake with a fluid path that connects the master cylinder and the wheel cylinder, a shut-off valve that shuts off the fluid path, and an actuator that is connected to the fluid path on the wheel cylinder side of the shut-off valve and that is activated by an electrical signal according to the driver's brake A brake fluid pressure generating means for generating a fluid pressure; and a stroke simulator connected to the master cylinder for applying a predetermined reaction force to the driver's brake operation, the master cylinder having a piston that moves forward by the driver's brake operation; Has a hydraulic pressure generating chamber formed on the front surface of the piston. The communication between the hydraulic pressure generating chamber and the stroke simulator Te is blocked brake apparatus according to claim is proposed.

  According to the invention described in claim 2, in addition to the configuration of claim 1, the piston of the master cylinder includes a front seal member and a rear seal member, and the front seal member is moved by the advance of the piston. A brake device is proposed in which after the communication between the hydraulic pressure generating chamber and the stroke simulator is cut off, the rear seal member cuts off the communication between the stroke simulator and the reservoir of the master cylinder.

  The pedal force shut-off valves 17a and 17b of the embodiment correspond to the shut-off valve of the present invention, the brake cylinders 18a and 18b of the embodiment correspond to the brake fluid pressure generating means of the present invention, and the motors 20a and 20b of the embodiment include Corresponding to the actuator of the present invention, the primary cups 44a and 44b of the embodiment correspond to the front seal member of the present invention, and the reflux prevention cups 46a and 46b of the embodiment correspond to the rear seal member of the present invention.

  According to the configuration of the first aspect, when the actuator is normal, the shut-off valve closes and shuts off the fluid path that connects the master cylinder and the wheel cylinder. Therefore, the actuator is operated by an electric signal corresponding to the driver's brake operation. The brake fluid pressure generated by the brake fluid pressure generating means driven by the actuator can be supplied to the wheel cylinder to brake the wheel. At this time, the stroke simulator absorbs the brake fluid pumped from the hydraulic pressure generation chamber of the master cylinder, so that a predetermined reaction force can be applied to the driver's brake operation to prevent a sense of incongruity.

  In addition, when the actuator is abnormal, the shut-off valve opens to open the fluid path that connects the master cylinder and the wheel cylinder, so the brake fluid pressure generated by the master cylinder that is activated by the driver's brake operation is supplied to the wheel cylinder. The wheel can be braked without any problem. At this time, when the piston moves forward by the driver's brake operation, the communication between the hydraulic pressure generation chamber and the stroke simulator is interrupted, so the brake fluid pumped from the hydraulic pressure generation chamber is supplied to the wheel cylinder without being released to the stroke simulator. It is possible to prevent the driver from feeling uncomfortable with the brake operation.

  In this way, the stroke simulator can be invalidated in the event of an abnormality without providing a special solenoid valve or the like between the master cylinder and the stroke simulator, so that the structure of the brake system can be prevented from becoming complicated. .

  According to the configuration of the second aspect, even if the piston of the master cylinder moves forward and the front seal member cuts off the communication between the hydraulic pressure generation chamber and the stroke simulator in the event of an abnormality, the rear seal member does not move between the stroke simulator and the master cylinder. Since the communication with the reservoir is cut off, the brake fluid accumulated in the stroke simulator can be prevented from returning to the reservoir, and the stroke simulator can be maintained in the accumulated pressure state. As a result, even if the piston of the master cylinder moves backward and the front seal member communicates the wheel cylinder and the stroke simulator, the brake fluid is prevented from flowing from the wheel cylinder to the stroke simulator. This can prevent the piston from moving forward and giving the driver a sense of incongruity.

  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 to 4 show an 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 a hydraulic system diagram at the time of abnormality corresponding to FIG. 3 is an enlarged cross-sectional view of a part 3 in FIG. 1, and FIG.

  As shown in FIG. 1, the tandem master cylinder 10 includes first and second front output ports 11 a and 11 b that output brake fluid pressure in accordance with a pedaling force that a driver steps on the brake pedal 12. The first front output port 11a is connected to the wheel cylinder 16a of the brake caliper 15a of the left wheel through the first liquid passages 13a and 14a, and the second front output port 11b is connected to the right through the second liquid passages 13b and 14b. It is connected to the wheel cylinder 16b of the wheel brake caliper 15b.

  Between the first fluid passage 13a on the upstream side connected to the first front output port 11a and the first fluid passage 14a on the downstream side connected to the wheel cylinder 16a, a pedal force cutoff valve 17a that is a normally open solenoid valve is disposed, A brake cylinder 18a is disposed between the pedal force cutoff valve 17a and the wheel cylinder 16a. The piston 19a slidably fitted to the brake cylinder 18a is driven by the motor 20a through the speed reduction mechanism 21a, and can generate brake fluid pressure in the fluid chamber 22a formed on the front surface of the piston 19a. .

  Between the second fluid passage 13b on the upstream side connected to the second front output port 11b and the second fluid passage 14b on the downstream side connected to the wheel cylinder 16b, a pedaling force cutoff valve 17b that is a normally open solenoid valve is disposed, A brake cylinder 18b is disposed between the pedal force cutoff valve 17b and the wheel cylinder 16b. A piston 19b slidably fitted to the brake cylinder 18b is driven by a motor 20b via a speed reduction mechanism 21b, and can generate a brake fluid pressure in a fluid chamber 22b formed on the front surface of the piston 19b. .

  A stroke simulator 31a connected to the first rear output port 30a of the master cylinder 10 is a cylinder 32 in which a piston 34 urged by a spring 33 is slidably fitted. The liquid chamber 35 formed in the communication with the first rear output port 30a. Similarly, a stroke simulator 31b connected to the second rear output port 30b of the master cylinder 10 is a cylinder 32 slidably fitted with a piston 34 biased by a spring 33. A liquid chamber 35 formed on the spring 33 side communicates with the second rear output port 30b.

  The electronic control unit U that controls the operation of the pedal force shut-off valves 17a and 17b and the motors 20a and 20b includes a brake pedal switch 26 that detects the operation of the brake pedal 12, and first and second fluid passages 13a and 13b on the upstream side. Are connected to hydraulic pressure sensors 27a and 27b for detecting the hydraulic pressures of the first and second liquid passages 14a and 14b on the downstream side, respectively.

  As is apparent from FIG. 3, the tandem master cylinder 10 includes a first piston 41a and a second piston 41b that are slidably fitted into a cylindrical cylinder body 40, and includes a front end of the first piston 41a, A first return spring 42a is disposed between the front end of the cylinder body 40, a second return spring 42b is disposed between the rear end of the first piston 41a and the front end of the second piston 41b. The front end of the push rod 43 connected to the brake pedal 12 contacts the rear end.

  Primary cups 44a, 44b and secondary cups 45a, 45b are attached to the front and rear parts of the first and second pistons 41a, 41b, respectively, and reflux prevention cups 46a, 46b are attached adjacent to the rear parts of the primary cups 44a, 44b. Further, a pressure cup 47 is attached to the rear end of the first piston 41a.

  The first and second rear output ports 30a and 30b are opened in the hydraulic pressure generating chambers 48a and 48b partitioned in front of the primary cups 44a and 44b, and the first and second front output ports 11a are further forward. 11b are opened. A reservoir 49 for storing brake fluid is provided at the upper part of the cylinder body 40. The front side of the primary cups 44a and 44b communicates with the reservoir 49 via the relief ports 50a and 50b, and the rear side of the primary cups 44a and 44b is the supply side. The reservoir 49 communicates with the ports 51a and 51b.

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

  In the normal state shown in FIG. 1, the solenoids of the pedal force shut-off valves 17a and 17b are excited by a command from the electronic control unit U, the pedal force shut-off valves 17a and 17b are closed, and the upstream first and second liquid passages 13a and 13a are closed. Communication between 13b and the first and second liquid passages 14a, 14b on the downstream side is blocked.

  When the driver depresses the brake pedal 12 in this state, the second piston 41b pushed by the push rod 43 advances while compressing the second return spring 42a, and the primary cup 44b immediately passes through the relief port 50b. Brake fluid pressure is generated in the fluid pressure generating chamber 48b. When the brake fluid pressure is generated in the fluid pressure generating chamber 48b, the first piston 41a moves forward while compressing the first return spring 42a by the brake fluid pressure, and the primary cup 44a immediately passes through the relief port 50a. Brake fluid pressure is generated in the pressure generating chamber 48a.

  The brake hydraulic pressure generated in the hydraulic pressure generating chambers 48a and 48b of the master cylinder 10 in this way is the upstream side of the first and second front output ports 11a and 11b that are blocked by the pedal force shut-off valves 17a and 17b. 1. It is transmitted to the second fluid passages 13a, 13b, and the fluid pressure is detected by fluid pressure sensors 27a, 27b. The electronic control unit U operates the motors 20a and 20b to generate the target braking fluid pressure in the first and second fluid passages 14a and 14b on the downstream side based on the fluid pressure detected by the fluid pressure sensors 27a and 27b.

  As a result, the driving force of the motors 20a and 20b is transmitted to the pistons 19a and 19b via the speed reduction mechanisms 21a and 21b, and the brake fluid pressure generated in the fluid chambers 22a and 22b of the brake cylinders 18a and 18b is converted into the pedal force cutoff valve 17a. , 17b are transmitted to the wheel cylinders 16a, 16b via the first and second liquid passages 14a, 14b on the downstream side, which are blocked by the left and right wheels. At this time, the hydraulic pressure of the first and second fluid passages 14a and 14b on the downstream side is detected by the fluid pressure sensors 28a and 28b, and the electronic control unit U controls the motor 20a so that the fluid pressure matches the target braking fluid pressure. , 20b is feedback-controlled.

  As described above, when the driver depresses the brake pedal 12 and the master cylinder 10 generates the brake fluid pressure in the normal state, the brake fluid pressure is transmitted from the first and second rear output ports 30a and 30b to the fluid chambers of the stroke simulators 31a and 31b. By transmitting the pistons 34 and 34 against the elastic force of the springs 33 and 33, a reaction force against the depression of the brake pedal 12 can be generated. Thereby, although the wheel cylinders 16a and 16b are actually operated by the driving force of the motors 20a and 20b, the operation feeling equivalent to that when the wheel cylinders 16a and 16b are operated by the driver's stepping force is obtained. Obtainable.

  In the normal state described above, the primary cups 44a and 44b do not exceed the first and second rear output ports 30a and 30b, and the fluid pressure generating chambers 48a and 48b and the stroke simulators 31a and 31b are disconnected from each other. There is no.

  When the power supply is lost due to battery disconnection or the like, the pedal force shut-off valves 17a and 17b are opened as shown in FIG. 2, and the upstream side first and second liquid passages 13a and 13b and the downstream side are opened. The first and second liquid passages 14a and 14b communicate with each other. As a result, the brake hydraulic pressure generated by the hydraulic pressure generation chambers 48a and 48b of the master cylinder 10 when the driver depresses the brake pedal 12 causes the upstream first and second fluid passages 13a and 13b to open, and the pedal force cutoff valve that is opened. The left and right wheels are braked by being transmitted to the wheel cylinders 16a and 16b via the first and second liquid passages 14a and 14b on the downstream side.

  Since the brake fluid pressure generated in the fluid pressure generating chambers 48a and 48b operates the wheel cylinders 16a and 16a at the time of this abnormality, the amount of brake fluid flowing into the wheel cylinders 16a and 16a is the first, compared to the above-described normal state. As the stroke of the second pistons 41a and 41b increases and the first and second pistons 41a and 41b move forward as shown in FIG. 4, the primary cups 44a and 44b become the first and second rear output ports 30a and 30b. The communication between the hydraulic pressure generating chambers 48a and 48b and the stroke simulators 31a and 31b is blocked.

  Therefore, the brake fluid pumped from the hydraulic pressure generation chambers 48a and 48b after the communication is cut off is supplied to the wheel cylinders 16a and 16a without being supplied to the stroke simulators 31a and 31b. It is possible to minimize the increase in the stroke of the brake pedal 12 at the time of abnormality and to eliminate the driver's uncomfortable feeling. In addition, it is not necessary to provide a special solenoid valve to cut off the communication between the hydraulic pressure generating chambers 48a and 48b and the stroke simulators 31a and 31b, thereby simplifying the structure and contributing to cost reduction and reducing power consumption. be able to.

  Even if the power supply fails and the pedal force shut-off valves 17a and 17b and the motors 20a and 20b become inoperable, the wheel cylinders 16a and 16b are driven by the brake fluid pressure generated by the master cylinder 10 when the driver steps on the brake pedal 12. 16b can be operated without hindrance, and at that time, the stroke simulators 31a and 31b can be invalidated to eliminate the driver's uncomfortable feeling.

  If the first and second pistons 41a and 41b are not provided with the reflux prevention cups 46a and 46b, the first and second pistons 41a and 41b move forward and the primary cups 44a and 44b When the first and second rear output ports 30a and 30b are passed, the brake fluid in the stroke simulators 31a and 31b that have been accumulated until then passes through the first and second rear output ports 30a and 30b, and the primary cup 44a. , 44b and then back to the reservoir 49 of the master cylinder 10 via the relief ports 50a, 50b, so that the liquid chambers 35, 35 of the stroke simulators 31a, 31b return to atmospheric pressure.

  Subsequently, when the first and second pistons 41a and 41b are retracted and the primary cups 44a and 44b come to an intermediate position between the first and second rear output ports 30a and 30b and the relief ports 50a and 50b, the pressurized wheel Since the brake fluid flows backward from the cylinders 16a and 16a to the atmospheric pressure stroke simulators 31a and 31b, the amount of the brake fluid in front of the primary cups 44a and 44b gradually decreases and the same braking force is generated. There is a problem that the stroke of the brake pedal 12 for increasing the speed gradually increases.

  However, in the present embodiment, as shown in FIG. 4, even if the primary cups 44a and 44b pass over the first and second rear output ports 30a and 30b in the process of the first and second pistons 41a and 41b moving forward during an abnormality, as shown in FIG. Since the anti-reflux cups 46a and 46b block communication between the first and second rear output ports 30a and 30b and the relief ports 50a and 50b, the brake fluid accumulated in the stroke simulators 31a and 31b returns to the reservoir 49. The stroke simulators 31a and 31b can be maintained in a pressure accumulation state.

  As a result, even if the first and second pistons 41a and 41b move backward and the primary cups 44a and 44b come to an intermediate position between the first and second rear output ports 30a and 30b and the relief ports 50a and 50b, the stroke simulator 31a , 31b is in a pressure accumulation state, preventing the brake fluid from flowing back from the wheel cylinders 16a, 16a, reducing the amount of brake fluid in front of the primary cups 44a, 44b and increasing the stroke of the brake pedal 12. Can be prevented.

  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.

  For example, in the embodiment, the brake cylinders 18a and 18b are employed as the brake fluid pressure generating means, but a fluid pressure pump driven by an actuator may be employed.

Hydraulic system diagram when the brake system for vehicles is normal Hydraulic system diagram at the time of abnormality corresponding to FIG. 3 is an enlarged sectional view of part 3 in FIG. Action diagram at the time of abnormality corresponding to FIG.

Explanation of symbols

10 Master cylinders 13a, 13b Fluid passages 14a, 14b Fluid passages 16a, 16b Wheel cylinders 17a, 17b Pedal force shut-off valves (shut-off valves)
18a, 18b Brake cylinder (brake fluid pressure generating means)
20a, 20b Motor (actuator)
31a, 31b Stroke simulator 41a, 41b Piston 44a, 44b Primary cup (front seal member)
46a, 46b Reflux prevention cup (rear seal member)
48a, 48b Fluid pressure generating chamber 49 Reservoir

Claims (2)

A master cylinder (10) that generates a brake fluid pressure by a driver's brake operation, a wheel cylinder (16a, 16b) that operates with the brake fluid pressure to brake a wheel,
Liquid passages (13a, 13b; 14a, 14b) connecting the master cylinder (10) and the wheel cylinders (16a, 16b);
Shutoff valves (17a, 17b) for shutting off the liquid passages (13a, 13b; 14a, 14b);
The brake fluid is connected to the fluid passages (14a, 14b) closer to the wheel cylinders (16a, 16b) than the shut-off valves (17a, 17b) and is actuated by an electric signal corresponding to the driver's brake operation. Brake fluid pressure generating means (18a, 18b) for generating pressure;
A stroke simulator (31a, 31b) connected to the master cylinder (10) for applying a predetermined reaction force to the driver's brake operation;
With
The master cylinder (10) includes a piston (41a, 41b) that moves forward by a driver's braking operation, and a hydraulic pressure generation chamber (48a, 48b) formed in front of the piston (41a, 41b). A brake device characterized in that communication between the hydraulic pressure generating chambers (48a, 48b) and the stroke simulators (31a, 31b) is cut off as the vehicle advances. The piston (41a, 41b) of the master cylinder (10) includes a front seal member (44a, 44b) and a rear seal member (46a, 46b), and the front seal member is moved forward by the piston (41a, 41b). (44a, 44b) cuts off the communication between the hydraulic pressure generating chambers (48a, 48b) and the stroke simulator (31a, 31b), and then the rear seal members (46a, 46b) become the stroke simulator (31a, 31b) and the master cylinder. The brake device according to claim 1, wherein communication with the reservoir (49) of (10) is cut off.

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