JPH08295226A - Brake system - Google Patents

Abstract

PURPOSE: To automatically compensate an insufficient pedal force if the pedal force is not enough to obtain the necessary braking force. CONSTITUTION: A normally open first switching valve 17 is disposed in a first variable pressure passage 16 which communicates a negative pressure source 15 to the internal chamber of a negative pressure booster 3, and a second switching valve 19 by which the first variable pressure passage 16 is communicated to or shut off from the atmosphere is also disposed. A third variable pressure passage 20, branching from the first variable pressure passage 16, connected to the variable pressure chamber of the negative pressure booster 3, and having a check valve 21, is provided. On sudden braking, for example, the atmosphere is introduced into the variable pressure chamber through the control valve of the negative pressure booster 3 to operate the brake. In this case, an electronic control unit 24 switches the first and second switching valves 17, 19 from one to the other according to detection signals from a stroke sensor and a pedal force gage. Therefore, the atmosphere is introduced into the variable pressure chamber also through the first and second passages 16, 20, resulting in increased braking force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to a case where the braking force is insufficient by the braking force corresponding to the pedaling force, such as in the case of sudden braking, when the brake is applied by the driver's depression of the brake pedal. In addition, the present invention relates to a braking system that increases the braking force.

[0002]

2. Description of the Related Art Recently, in automobiles, it is possible to easily start a vehicle such as an automobile on a slope without requiring a sudden pedal change operation from a parking brake or a brake pedal to an accelerator pedal. For,
In order to reduce the fatigue caused by brake operation by eliminating the need to operate the brake pedal while waiting for traffic lights and in congested roads, traction control should be performed when the drive wheels run idle to ensure proper start and acceleration. In order to ensure that the vehicle is stopped on a hill, the inter-vehicle distance is automatically controlled while driving, and the vehicle traveling speed is controlled to prevent overspeed on a downhill. Brake systems have been developed that are used to prevent forgetting to apply the side brakes in order to automatically suppress them.

As such a braking system, there is a conventional braking system disclosed in Japanese Patent Laid-Open No. 5-24532 as shown in FIG. The brake system shown in FIG. 5 is equipped with a tandem-type vacuum booster, and in this state, the vacuum booster 150 includes the control valve 15
The atmosphere valve 151a of No. 1 is closed and the vacuum valve 151b is opened, so that the chambers A, B, C and D are in a brake inoperative state in which a vacuum is introduced. Also, the solenoid valve 152 is normally set to the vacuum side at the position shown in the figure, and therefore the chamber A ′ surrounded by the bellows 153 is normally supplied with vacuum.

When the brake pedal (not shown) is depressed and the input shaft 154 moves forward during normal braking in this brake non-operating state, the atmospheric valve 15 of the control valve 151.
Since 1a is opened and the vacuum valve 151b is closed, the atmosphere is introduced into the variable pressure chambers B and D through the variable pressure passages 155 and 156, respectively. As a result, a differential pressure is generated between the chambers A, B and C, D before and after the diaphragms 157, 158, and the diaphragms 157, 158 and the power pistons 159, 160.
Moves forward, and an output is generated from the output shaft 161. Then, this output causes the master cylinder 162 to operate,
The brake normally operates.

The advance of the diaphragms 157, 158 and the power pistons 159, 160 is continued until the atmosphere valve 151a is closed and the atmosphere is not introduced into the variable pressure chambers B, D. As a result, the output depends on the input, that is, the brake pedal depression amount. A large output boosted by a predetermined servo ratio is obtained. In this state, the atmospheric valve 151a and the vacuum valve 151b of the control valve 151 are both closed.

On the other hand, in the brake non-operating state, when the controller switches the solenoid valve 152 to the atmosphere side under the automatic brake operating condition, the chamber A'is disconnected from the negative pressure source and the chamber A'is exposed to the atmosphere. Is introduced, and the atmosphere further passes through the constant pressure passage 163, the open vacuum valve 151b, the variable pressure passages 155 and 156, and the variable pressure chamber B,
D respectively. As a result, the diaphragms 157, 158 and the power pistons 159, 160 move forward and the brake operates, as in the normal braking described above. In this way, when the automatic brake operating condition is reached, the solenoid valve 15 is activated by the control signal from the controller.
By switching 2 the automatic braking is activated.

[0007]

By the way, using this conventional brake system, for example, the risk of a vehicle collision is extremely high, and the driver rapidly depresses the brake pedal with a large pedaling force to activate the sudden braking. In such a case, it is possible to quickly obtain a large braking force.

However, when the driver depresses the brake pedal for sudden braking, the vacuum valve 151
b is closed, and the constant pressure passage 163 and the variable pressure passage 155 are cut off. Therefore, even if the controller detects sudden braking and switches the solenoid valve 152 to introduce the atmosphere into the chamber A ′ and the constant pressure passage 163,
This atmosphere is not introduced into the variable pressure passage 155, and the braking force cannot be increased. Therefore, when the pedal depression force is insufficient to obtain the required braking force, such as during a sudden braking operation, it is impossible to control so as to automatically compensate for the insufficient pedal depression force. .

The present invention has been made in view of the above problems, and an object thereof is to provide a sufficient pedaling force when the pedaling force is insufficient to obtain a necessary braking force. It is to provide a brake system that can automatically compensate.

[0010]

In order to solve the above-mentioned problems, the invention of claim 1 provides a brake operating member, a constant pressure chamber to which a negative pressure is constantly introduced from a negative pressure source, and a negative pressure when the brake is not operated. Is introduced and the atmosphere is introduced at the time of brake operation, the diaphragm is operated by dividing the constant pressure chamber and the variable pressure chamber into the variable pressure chamber, and the negative pressure is normally introduced. At the same time, the internal chamber into which the atmosphere is selectively introduced when necessary, and the switching operation is controlled by the brake operating member to communicate the variable pressure chamber with the internal chamber when the brake is not operated and to shut off from the atmosphere and to communicate with the atmosphere when the brake is operated. A negative pressure booster equipped with a control valve that shuts off from the internal chamber and an output shaft that outputs when the diaphragm operates, and a negative pressure booster operated by the output shaft of the negative pressure booster. To generate a brake fluid pressure, a brake cylinder to which a brake fluid pressure of the master cylinder is introduced to generate a braking force, a first passage connected to the internal chamber, and a first passage which is normally connected to the first passage. A pressure switching valve that communicates with a negative pressure source and communicates with the atmosphere when necessary, a second passage that introduces the atmosphere flowing in the first passage into the variable pressure chamber, and the second passage that is provided in the second passage. From the variable pressure chamber to the variable pressure chamber but blocks the flow of air from the variable pressure chamber to the first passage, a manipulated variable detection sensor for detecting a manipulated variable of the brake operating member, and An operation force detection sensor that detects the operation force of the brake operation member, and each detection signal from the operation amount detection sensor and the operation force detection sensor, and the detection signals An electronic control unit that controls the pressure switching valve based on the above, and when the electronic control unit switches the pressure switching valve and communicates the first passage with the atmosphere at the time of a sudden braking or the like, the braking force is increased. It is characterized by increasing.

Further, the invention of claim 2 further comprises hydraulic pressure detecting means for detecting the brake hydraulic pressure of the master cylinder, and the electronic control unit is adapted to perform the pressure control based on a detection signal from the hydraulic pressure detecting means. It is characterized by controlling the switching valve. Furthermore, the invention of claim 3 is characterized in that the second passage is a passage that connects the first passage and the variable pressure chamber.

Further, according to the invention of claim 4, there is provided a valve body having a third passage for accommodating and supporting the control valve and communicating the control valve and the internal chamber, and the second passage is formed in the valve body. It is a passage that connects the third passage and the variable pressure chamber.

Further, in the invention of claim 5, the pressure switching valve communicates the first passage and the atmosphere with a normally open first on-off valve which communicates and cuts off the first passage and the negative pressure source. And a normally closed second on-off valve for shutting off.

[0014]

According to the invention of claim 1 having such a structure, in the normal brake, the control valve of the negative pressure booster is switched by the brake operating member being brake-operated by the normal pedaling force, so that the transformer is transformed. Atmosphere is introduced into the chamber through a control valve and the vacuum booster produces an output. At this time, the atmosphere introduced into the variable pressure chamber tries to leak through the second passage, but the check valve in the second passage prevents this leakage of the atmosphere, so the output of the negative pressure booster is It is an output that boosts the pedal effort with a predetermined servo ratio without loss. With this output, the master cylinder operates to generate a brake fluid pressure, and this brake fluid pressure is supplied to the brake cylinder to perform normal braking.

When the brake operating member is operated rapidly and with a large operating force, for example, during sudden braking, the control valve is switched as in the case of the above-mentioned normal braking, and the atmosphere is introduced into the variable pressure chamber through the control valve. Then, the negative pressure booster outputs and the brake operates. In that case, since the opening amount of the control valve is relatively small and the atmosphere flowing through the control valve is limited, the pressure rise in the variable pressure chamber is small. Therefore, even if the brake operating member is operated rapidly and with a large operating force,
The braking force is small, and the generated braking force does not reach the required braking force.

However, based on the detection signal of the operation amount of the brake operation member from the operation amount detection sensor and the detection signal of the operation force of the brake operation member from the operation force detection sensor,
When the electronic control unit detects an operation of the brake operating member with a rapid and large operating force, the electronic control unit switches and controls the pressure switching valve. As a result, the variable pressure chamber of the negative pressure booster communicates with the atmosphere through the second passage and the first passage so that the atmosphere can be introduced into the variable pressure chamber through the first and second passages without any restriction. Become. Therefore,
Since the pressure in the variable pressure chamber rises and the output of the negative pressure booster increases, when the brake operating member is operated by a rapid and large operating force, the braking force is increased to a required amount.

According to the second aspect of the invention, the electronic control unit also controls the pressure switching valve based on the brake fluid pressure detection signal of the master cylinder from the fluid pressure detection means. As a result, when the brake operating member is operated with a rapid and large operating force, the braking force can be controlled more accurately.

Further, according to the invention of claim 3, the second passage communicating the first passage and the variable pressure chamber can be arranged outside the conventionally known negative pressure booster. Accordingly, since it is only necessary to provide the second passage with the normal brake pipe and the conventionally known check valve, the brake system of the present invention can be formed inexpensively and easily.

Further, according to the invention of claim 4, since the second passage is formed in the valve body of the negative pressure booster, no special pipe is provided outside the negative pressure booster.
It becomes compact as a whole. Further, in the invention of claim 5, the pressure switching valve can be constituted by an on-off valve which is a solenoid valve which is well known and has a simple structure, so that the cost is reduced.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an embodiment of a brake system according to the present invention. As shown in FIG. 1, a brake system 1 of this embodiment includes a brake pedal 2 which is a brake operating member of the present invention, and a tandem type negative pressure doubler which is operated by the depression of the brake pedal 2 during normal braking to output. The force device 3, the tandem master cylinder 4 that generates a brake fluid pressure in each of the two fluid chambers by the output of the negative pressure booster 3, and the brake fluid pressure that is generated in one fluid chamber of the tandem master cylinder 4 Wheel cylinders 6 and 7 for the left and right rear wheels supplied through the hydraulic passage 5.
The brake fluid pressure generated in the other fluid chamber of the tandem master cylinder 4 is supplied through the fluid pressure passage 8 to the wheel cylinders 9 and 10 of the left and right front wheels, and to both fluid pressure passages 5 and 8. Anti-skid control device (hereinafter also referred to as ABS) 11, tandem master cylinder 4 and ABS 11
Between the tandem master cylinder 4 and the PV 12, which is disposed in the hydraulic pressure passages 5 and 8 between the tandem master cylinder 4 and the PV 12, and which detects the brake hydraulic pressure of the master cylinder 4. Hereinafter, also referred to as hydraulic pressure PU) 13, a negative pressure source 15 for supplying a negative pressure to the negative pressure booster 3 via a negative pressure passage 14, and a branch from the negative pressure passage 14 to the negative pressure booster 3. A first variable pressure passage 16 (corresponding to the first passage of the present invention) for selectively supplying either the negative pressure of the negative pressure source 15 or the atmosphere, and a communication position provided in the first variable pressure passage 16 A normally open first opening / closing valve 17 (corresponding to the pressure switching valve of the present invention) including a solenoid valve provided with a shutoff position, and a first transformer on the negative pressure booster 3 side from the first opening / closing valve 17. A second variable pressure passage 18 which communicates the passage 16 with the atmosphere, and a second pressure variable passage 18 which is disposed in the second variable pressure passage 18 and communicates with the cutoff position. A normally closed second on-off valve 19 (corresponding to the pressure switching valve of the present invention) which is an electromagnetic valve provided with a through position, and a negative pressure booster 3 branched from the first variable pressure passage 16
And a third variable pressure passage 20 (corresponding to the second variable passage of the present invention) connected to the first variable pressure passage 20 and a flow of air from the first variable pressure passage 16 toward the negative pressure booster 3 provided in the third variable pressure passage 20. A check valve 21, a pedal force meter 22 provided on the brake pedal 2 for detecting a pedal effort, a stroke sensor 23 for detecting a stroke of the brake pedal 2, a brake fluid pressure detection signal of the master cylinder from the fluid pressure pickup 13, and a pedal effort. The pedal depression force detection signal from the total 22 and the pedal stroke detection signal from the stroke sensor 23 are input, and the first and second opening / closing valves 17,
19 and a controller 24 for outputting a control signal. The hydraulic pressure passage 8 below ABS11 is branched into two independent hydraulic pressure passages 8a and 8b for each of the left and right front wheels.

FIG. 2 is an enlarged sectional view showing the negative pressure booster 3. As shown in FIG. 2, the negative pressure booster 3 is the same as the conventional tandem type negative pressure booster disclosed in the above-mentioned publication, and includes an input shaft 25 connected to the brake pedal 2. A center plate 28 that divides an internal space formed by the front shell 26 and the rear shell 27 into a front chamber and a rear chamber, a front power piston 29 disposed in the front chamber, and a rear surface of the front power piston 29. Are arranged in such a manner that the front chamber is a constant pressure chamber 30 on the front side and the variable pressure chamber 3 on the front side.
1, a front diaphragm 32, a rear power piston 33 disposed in the rear chamber, and a rear constant pressure chamber 34 and a rear constant pressure chamber 34 disposed so as to be located on the rear surface of the rear power piston 33. A rear diaphragm 36 that divides into a variable pressure chamber 35, a bellows 38 that is arranged in the constant pressure chamber 30 on the front side and divides and forms an internal chamber 37, an atmosphere valve 39a that is closed when the brake is not activated and that is opened by advancing the input shaft 25, and a brake. Open when not operating and input shaft 25
Input shaft 25, which consists of a vacuum valve 39b that is closed by the forward movement of
Control valve 39, which is switch-controlled by the forward movement of the front diaphragm 32, a constant pressure passage 40 which is formed outside the bead portion of the front diaphragm 32, and which always connects the front constant pressure chamber 30 and the rear constant pressure chamber 34, and the atmospheric valve 39a. And a vacuum valve 39b, and an annular space between the rear side variable pressure chamber 35 and the fourth variable pressure passage 41, and the front side variable pressure chamber 31 and the rear side variable pressure chamber 35 always communicate. Passage 42 and internal chamber 3
7 and the outer annular space of the vacuum valve 39b always communicate with each other, the sixth variable pressure passage 43, the output shaft 44 that operates the piston of the master cylinder 4, and the reaction force of the output of the output shaft 44 to the input shaft 2
5 and at least a reaction disc 45 for transmission to the vehicle.

A negative pressure passage 14 is provided in the constant pressure chamber 30 on the front side.
Is connected so that the negative pressure is constantly introduced from the negative pressure source 15. The negative pressure introduced into the constant pressure chamber 30 is further always introduced into the constant pressure chamber 34 on the rear side through the constant pressure passage 40. Also, the bellows 38
The first variable pressure passage 16 is connected to the inner chamber 37 of
When the first opening / closing valve 17 is open and the second opening / closing valve 19 is closed, negative pressure is introduced from the negative pressure source 15 into the internal chamber 37, and the first opening / closing valve 17 is closed and the second opening / closing valve 19 is opened. Atmosphere is introduced into the internal chamber 37 during operation.
Furthermore, the third variable pressure passage 20 is connected to the variable pressure chamber 35 on the rear side so that the first open / close valve 17 is opened and the second open / close valve 19 is opened.
Negative pressure is introduced from the negative pressure source 15 into the variable pressure chamber 35 when is closed, and the atmosphere is introduced into the variable pressure chamber 35 when the first opening / closing valve 17 is closed and the second opening / closing valve 19 is open. It has become.

In the brake system 1 of the present embodiment constructed as described above, the atmosphere valve 39a is closed and the vacuum valve 39b is opened when the brake is not operated as shown in FIGS. 17 is open and the second on-off valve 19 is closed. Therefore, both constant pressure chambers 30, 3
4. Both the variable pressure chambers 31 and 35 and the internal chamber 37 are in a state where negative pressure is introduced.

During normal braking, the input shaft 25 is advanced by depressing the brake pedal 2, the vacuum valve 39b is closed and the atmospheric valve 39a is opened. As a result, the atmosphere passes through the open atmosphere valve 39a, the annular space between the atmosphere valve 39a and the vacuum valve 39b, and the fourth variable pressure passage 41, and the rear pressure chamber 35.
In addition to being introduced into the transformer chamber 31 on the front side through the fifth transformer passage 42. As a result, a pressure difference occurs between the front diaphragm 32 and the rear diaphragm 36, and the front diaphragm 32,
The front power piston 29, the rear diaphragm 36, and the rear power piston 33 move forward. For this reason, the output shaft 44 also advances and outputs, and operates the piston of the master cylinder 4. In that case, the atmosphere introduced into the rear pressure changing chamber 35 tries to leak through the third pressure changing passage 20, but the check valve 21 blocks the flow of air toward the negative pressure source 15, so Leakage of the atmosphere in the variable pressure chamber 35 on the side is reliably prevented. Therefore, the negative pressure booster 3 outputs the pressure without loss.

The master cylinder 4 generates a brake fluid pressure in two fluid chambers by the operation of the piston, and the brake fluid pressure in one fluid chamber is supplied to the rear wheel cylinders 6 and 7 of the rear wheels through the fluid pressure passage 5. Then, the normal brake of the rear wheels is activated. Similarly, the brake fluid pressure of the other fluid chamber is supplied to the front wheel cylinders 9 and 10 of the front wheels through the fluid pressure passage 8 and the left and right branch passages 8a and 8b, and the normal brakes of the left and right front wheels are activated.

The forward movement of the front diaphragm 32, the front power piston 29, the rear diaphragm 36 and the rear power piston 33 gradually closes the atmosphere valve 39a, and when both the atmosphere valve 39a and the vacuum valve 39b are closed, the front diaphragm 32 is closed. The forward movement of the front power piston 29, the rear diaphragm 36 and the rear power piston 33 is stopped. As a result, the output of the negative pressure booster 3 becomes an output obtained by boosting the input of the input shaft 25 with a predetermined servo ratio.

When the brake pedal 2 is released, the input shaft 2
5 is retracted and the vacuum valve 39b is opened. As a result, the atmosphere in both the front and rear transformer chambers 31 and 35 is
The variable pressure passage 42, the fourth variable pressure passage 41, the annular space between the atmosphere valve 39a and the vacuum valve 39b, the open vacuum valve 39b,
Sixth variable pressure passage 43, internal chamber 37 and first variable pressure passage 16
Through the negative pressure source 15. Therefore, the front diaphragm 32, the front power piston 29,
The rear diaphragm 36 and the rear power piston 33 retreat, the output shaft 44 and the piston of the master cylinder 4 also retreat, and the brake is released, and the brake system becomes the non-operating state shown in FIGS. 1 and 2.

A case where the vehicle is highly likely to collide and the driver depresses the brake pedal 2 rapidly and with a large pedal force to apply a sudden brake will be described. In this case, first, like the normal brake described above, the vacuum valve 39b is closed and the atmospheric valve 39a is opened by depressing the brake pedal 2.
Atmosphere is introduced into 35. As a result, the negative pressure booster 3 outputs, so that the master cylinder 4 generates brake fluid pressure and the brake is applied. However, in the case of such a sudden braking, even if the brake pedal 2 is depressed rapidly and with a large pedal effort, the opening amount of the atmosphere valve 39a is not so large originally and the atmosphere to be introduced is limited, so that each transformation chamber is The pressure increase at 31, 35 is not great, and the braking force of the applied brake is not so great. That is, the required large braking force cannot be obtained by depressing the brake pedal 2 at the time of sudden braking.

Therefore, in this embodiment, in such a case, the controller 24 controls the driver based on the pedal depression speed calculated from the pedal stroke detection signal from the stroke sensor 23 and the pedal depression force detection signal from the pedal force meter 22. Decides that he has braked suddenly. With this determination, the controller 24 causes the hydraulic pickup 1 to
When it is determined that the brake fluid pressure generated for the current pedal effort is insufficient based on the brake fluid pressure detection signal of the master cylinder 4 from 3 and the pedal depression force detection signal from the pedal force meter 22, the first opening / closing operation is performed. The second opening / closing valve 19 is set to the communication position at the same time when the valve 17 is set to the shutoff position. As a result, the first on-off valve 17 on the negative pressure booster 3 side
Since the variable pressure passage 16 is disconnected from the negative pressure source 15 and communicates with the atmosphere at the same time, the atmospheric air passes through the second variable pressure passage 18, the first variable pressure passage 16, the third variable pressure passage 20 and the check valve 21 to the rear variable pressure chamber. In addition to being introduced into the variable pressure chamber 35, the variable pressure chamber 35 is introduced into the variable pressure chamber 31 on the front side through the fifth variable pressure passage 42. As a result, each transformer room 31, 35
Since the pressure of is increased more than the pressure corresponding to the pedal effort and the output of the negative pressure booster 3 is increased, the brake fluid pressure generated by the master cylinder 4 is also increased and the braking force is increased. Therefore, the shortage of the braking force due to the shortage of the pedaling force at the time of sudden braking is reliably compensated, and, for example, a vehicle collision or the like can be surely prevented.

Incidentally, it is conceivable that the wheels are locked due to the increased braking force. Therefore, in the case of the present embodiment, when the controller 24 detects a wheel lock tendency based on a wheel speed signal from a wheel speed sensor (not shown), the controller 24 controls the operation of the ABS 11 as in the conventional anti-skid control. And the wheel cylinders 6, 7, 9, 10 of the wheels that tend to lock
The brake fluid pressure is adjusted so that the locking tendency is eliminated (the electrical connection between the controller 24 and the ABS 11 is omitted in FIG. 1).

Further, in this case, the atmosphere is the first variable pressure passage 16
Is introduced into the inner chamber 37 from the above, and further introduced into the annular space on the outer peripheral side of the vacuum valve 39b through the sixth variable pressure passage 43,
Since the vacuum valve 39b is closed by depressing the brake pedal 2, this atmosphere is not introduced into the variable pressure chambers 31 and 35.

By the way, the brake system 1 of this embodiment may be an automatic brake system as disclosed in the above-mentioned publication. To make this automatic braking system, although not shown, for example, wheel speed sensors, headway distance sensors, clutch stroke sensors, clutch switches, neutral switches, stop lamp switches,
Install various sensors such as parking brake switch and door switch at the related designated places, and
These sensors are connected to the controller 24.

Then, in the brake non-operating state shown in the figure, the controller 24 calculates based on the detection signals from these various sensors, and when it judges that the automatic brake operating condition is established based on the calculation result, the first The second opening / closing valve 19 is set to the communicating position while the opening / closing valve 17 is set to the shutoff position. As a result, as in the case of increasing the braking force described above, the first variable pressure passage 16 on the negative pressure booster 3 side of the first opening / closing valve 17 is blocked from the negative pressure source 15 and communicates with the atmosphere. Is the second variable pressure passage 18, the first variable pressure passage 16, the third variable pressure passage 20 and the check valve 2.
1 is introduced into the transformer room 35 on the rear side,
The variable pressure chamber 35 is introduced into the variable pressure chamber 31 on the front side through the fifth variable pressure passage 42. At the same time, in the case of this automatic braking, from the first variable pressure passage 16 to the inner chamber 37 and the sixth
The atmosphere introduced into the annular space on the outer peripheral side of the vacuum valve 39b through the variable pressure passage 43 is opened vacuum valve 39b, the annular space between the vacuum valve 39b and the atmospheric valve 39a, and the fourth space.
It is introduced into the rear side variable pressure chamber 35 through the variable pressure passage 41, and is introduced into the front side variable pressure chamber 31 from the fourth variable pressure passage 41 through the fifth variable pressure passage 42.

As a result, as in the case of the normal brake described above, the negative pressure booster 3 outputs and the master cylinder 4 generates brake fluid pressure. This brake fluid pressure is supplied to each wheel cylinder 6, 7, 9, 10 and each wheel cylinder 6, 7, 9, 10 brakes the corresponding wheel. Thus, the automatic brake operates.

When the automatic brake operating condition is canceled, the controller 24 sets the first opening / closing valve 17 to the communicating position and simultaneously sets the second opening / closing valve 19 to the shutoff position. As a result, the first variable pressure passage 16 on the negative pressure booster 3 side of the first opening / closing valve 17 is cut off from the atmosphere and communicated with the negative pressure source. The atmosphere introduced into each of the front and rear variable pressure chambers 31 and 35 includes a fifth variable pressure passage 42, a fourth variable pressure passage 41, an annular space between the vacuum valve 39b and the atmospheric valve 39a, an open vacuum valve. 39b, the sixth variable pressure passage 43, the internal chamber 37, the first variable pressure passage 16 and the first opening / closing valve 17 to flow toward the negative pressure source 15. Therefore, the front diaphragm 32, the front power piston 29, the rear diaphragm 36, the rear power piston 33, and the output shaft 4
4 returns to the non-operating position, each piston of the master cylinder 4 also returns to the non-operating position, and the brake fluid pressure disappears.
The automatic brake is released. The automatic brake operating conditions include the conditions for starting a slope, the conditions for maintaining the braking operation in a signal waiting state and a congested road, the conditions for performing traction control by braking when the drive wheels tend to idle, and the conditions for driving on a slope. The conditions for holding the vehicle stopped state, the conditions for controlling the distance between vehicles during traveling, the conditions for suppressing the traveling speed of the vehicle, the conditions for preventing forgetting to apply the side brake, etc. is there.

Further, when the automatic brake operating condition is satisfied during the normal brake operation by depressing the brake pedal 2, the controller 24 sets the first opening / closing valve 17 to the shut-off position at the same time as in the case of the automatic brake described above. 2 The on-off valve 19 is set to the communication position. Therefore, the atmosphere is introduced into the rear-side variable pressure chamber 35 through the second variable pressure passage 18, the first variable pressure passage 16 and the third variable pressure passage 20.
As a result, the automatic brake can be operated during the normal brake operation, and the braking force can be further increased by the automatic brake. Further, in this state, even if the brake pedal 2 is released and the normal brake is released, the automatic brake is kept in operation. The release of the automatic brake at this time is the same as in the case of the automatic brake described above.

When the normal brake is operated by depressing the brake pedal 2 in order to further increase the braking force during the automatic braking operation, the vacuum valve 39b is closed and the atmosphere valve 39a is opened, so that the atmosphere is transformed into each pressure chamber 31. , 35 is also introduced through the atmosphere valve 39a. Therefore, the normal brake operates even during the automatic brake operation. This normal brake can increase the braking force. In this state, even if the automatic brake is released, the normal brake is kept in operation. Further, the release of the normal brake at this time is the same as in the case of the above-mentioned normal brake.

FIG. 3 is a diagram showing another embodiment of the present invention, and FIG. 4 is an enlarged view of portion P of FIG. The same components as those in the above-described embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

In the above embodiment, the third variable pressure passage 2 is branched from the first variable pressure passage 16 and connected to the rear variable pressure chamber 35.
0 and the check valve 21 are provided in the third variable pressure passage 20. In this embodiment, as shown in FIG. 3, the third variable pressure passage 20 and the check valve 21 are provided.
Is provided in the valve body 46 of the negative pressure booster 3. That is, as shown in FIG. 4, the third variable pressure passage 20 includes the sixth variable pressure passage 43 of the valve body 46 and the variable pressure chamber 3 on the rear side.
It is provided so as to communicate with 5. Further, the third variable pressure passage 20 on the surface of the valve body 46 on the variable pressure chamber 35 side.
A check valve 21 made of an elastic member such as a rubber plate is provided at the opening of the check valve 21. The check valve 21 bends outward to open the third variable pressure passage 20 and allows the flow of air from the sixth variable pressure passage 43 to the variable pressure chamber 35. The third variable pressure passage 20 is closed to prevent the flow of air toward it.

Also in this embodiment, the same operational effects as the above-mentioned embodiments can be obtained. Further, in addition to this, in the present embodiment, since the third variable pressure passage 20 is provided in the negative pressure booster 3, external piping is unnecessary and the overall size is made compact.

The third variable pressure passage 20 may be provided in the valve body 46 so that the sixth variable pressure passage 43 communicates with the variable pressure chamber 31 on the front side. Further, the check valve 21 may be a check valve of a ball valve type instead of an elastic member such as a rubber plate.

Although the present invention is applied to the two-brake system in the above-mentioned embodiments, the present invention can be applied to a mere one-brake system in addition to the two-brake system.
The negative pressure booster 3 may be a single type negative pressure booster. Further, the first opening / closing valve 17 and the second opening / closing valve 19 may be formed by a single two-position three-way valve solenoid valve.

[0043]

As is apparent from the above description, according to the brake system of the present invention, when the brake operating member is operated rapidly and with a large operating force, for example, during sudden braking, the negative pressure is doubled. Since the variable pressure chamber of the power unit is communicated with the atmosphere through the second passage and the first passage without passing through the control valve, the atmospheric air can be introduced into the variable pressure chamber without being restricted by the control valve. Therefore, the output of the negative pressure booster can be increased, and when the brake operating member is operated by a rapid and large operating force, the braking force can be made a required amount of braking force. As a result, the shortage of the braking force due to the shortage of the pedal effort when the brake is suddenly actuated can be reliably compensated, and, for example, a vehicle collision can be surely prevented.

In particular, according to the second aspect of the present invention, the braking force is controlled in consideration of the brake fluid pressure detection signal of the master cylinder. Therefore, when the brake operating member is operated by a rapid and large operating force, the braking force is controlled. Can be controlled more accurately. Further, according to the invention of claim 3,
Since a normal brake pipe and a conventionally known check valve can be used, the brake system can be formed inexpensively and easily.

Further, according to the invention of claim 4, since the second passage is formed in the valve body of the negative pressure booster, no special pipe is provided outside the negative pressure booster. , Can be made compact as a whole. Further, according to the invention of claim 5, as the pressure switching valve, a solenoid valve which is well known and has a simple structure can be used, so that the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a brake system according to the present invention.

FIG. 2 is a sectional view showing an example of a negative pressure booster used in the brake system of the embodiment shown in FIG.

FIG. 3 is a diagram showing another embodiment of the present invention.

FIG. 4 is an enlarged view of a P portion in FIG.

FIG. 5 is a schematic and partial view of a conventional braking system.

[Explanation of symbols]

1 ... Brake system, 2 ... Brake pedal, 3 ... Negative pressure booster, 4 ... Tandem master cylinder, 5,8,8a,
8b ... hydraulic passage, 6, 7 ... rear wheel cylinder, 9,
10 ... Wheel cylinder of front wheel, 11 ... Anti-skid control device (ABS), 13 ... Hydraulic pickup, 14 ...
Negative pressure passage, 15 ... Negative pressure source, 16 ... First variable pressure passage, 17 ...
First on-off valve, 18 ... Second variable pressure passage, 19 ... Second on-off valve,
20 ... Third variable passage, 21 ... Check valve, 22 ... Pedometer, 23 ... Stroke sensor, 24 ... Controller,
25 ... Input shaft, 26 ... Front shell, 27 ... Rear shell, 28 ... Center plate, 29 ... Front power piston, 30 ... Front side constant pressure chamber, 31 ... Front side variable pressure chamber, 32 ... Front diaphragm, 33 ... Rear power Piston, 34 ... Constant pressure chamber on rear side, 35 ... Transformer chamber on rear side, 36 ... Rear diaphragm, 37 ... Internal chamber, 38
... Bellows, 39 ... Control valve, 39a ... Atmospheric valve, 39b ...
Vacuum valve, 40 ... Constant pressure passage, 41 ... Fourth variable pressure passage, 42 ...
5th variable pressure passage, 43 ... 6th variable pressure passage, 44 ... Output shaft, 4
5 ... Reaction disc, 46 ... Valve body

Claims (5)

[Claims] 1. A brake operating member, a constant pressure chamber to which a negative pressure is constantly introduced from a negative pressure source, a variable pressure chamber to which a negative pressure is introduced when the brake is not operated and an atmosphere is introduced when the brake is operated, and the constant pressure chamber. A diaphragm that divides the variable pressure chamber and operates by introducing air into the variable pressure chamber, an internal chamber that normally introduces negative pressure and selectively introduces atmospheric pressure when necessary, and switching control by a brake operating member And a control valve for communicating the variable pressure chamber with the internal chamber and shutting off from the atmosphere when the brake is not operating and for communicating with the atmospheric air when the brake is operating and shutting off from the internal chamber, and an output shaft for outputting by the operation of the diaphragm. A negative pressure booster, a master cylinder that is operated by the output shaft of the negative pressure booster to generate brake fluid pressure, and a master cylinder. Brake cylinder to which a brake fluid pressure is introduced to generate a braking force, a first passage connected to the internal chamber, and the first passage normally communicates with the negative pressure source and with the atmosphere when necessary. A pressure switching valve, a second passage for introducing the atmosphere flowing in the first passage into the variable pressure chamber, and a second passage provided in the second passage for allowing a flow of air from the first passage toward the variable pressure chamber. A check valve that blocks the flow of air from the variable pressure chamber toward the first passage, an operation amount detection sensor that detects an operation amount of the brake operation member, and an operation force detection sensor that detects an operation force of the brake operation member. And an electronic control unit that inputs each detection signal from the operation amount detection sensor and the operation force detection sensor, and controls the pressure switching valve based on these detection signals, A braking system, wherein the braking force is increased by the electronic control unit switching the pressure switching valve to communicate the first passage with the atmosphere when necessary such as during sudden braking. 2. A hydraulic pressure detecting means for detecting the brake hydraulic pressure of the master cylinder is further provided, and the electronic control unit controls the pressure switching valve also based on a detection signal from the hydraulic pressure detecting means. The brake system according to claim 1, wherein: 3. The brake system according to claim 1, wherein the second passage is a passage that connects the first passage and the variable pressure chamber. 4. A valve body having a third passage for accommodating and supporting the control valve and communicating the control valve with the internal chamber, wherein the second passage is formed in the valve body to form the third passage. The brake system according to claim 1, wherein the brake system is a passage that communicates with the variable pressure chamber. 5. The pressure switching valve includes a normally open first opening / closing valve that connects and disconnects the first passage and the negative pressure source, and a normally closed valve that connects and disconnects the first passage and the atmosphere. 5. A second opening / closing valve according to claim 1.
Brake system as described.