JP3570456B2 - Braking system with brake booster - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a braking system, and more particularly to a braking system with a brake booster.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a braking system including a brake booster that boosts the depression force of a brake pedal and a master cylinder that is activated by the brake booster and generates a brake hydraulic pressure is well known.
The brake booster is usually provided movably in the shell, and a valve body having a rear end cylindrical portion protruding outside the shell, and an outer peripheral portion of the valve body. A power piston that defines a constant pressure chamber on the side and a variable pressure chamber on the rear side, a valve mechanism housed in the valve body to switch the flow path, and a pressure passage formed in the end cylindrical portion and opened to the atmosphere And an input shaft for operating the valve mechanism to switch the flow path, supplying the atmosphere from the pressure passage to the transformation chamber, and advancing the power piston.
In an electric vehicle, a braking system including the above-described brake booster is used in combination with a regenerative braking device that increases or decreases a regenerative braking force in accordance with an increase or decrease in the operation amount of a brake pedal (Japanese Patent Laid-Open No. Hei 2 (1990) -1990). 123902). In this case, in order to detect the operation amount of the brake pedal, the depression force of the brake pedal and the brake fluid pressure that increases and decreases in response to the depression force are detected, or the stroke amount of the brake pedal is detected.
In this type of electric vehicle, the regenerative braking force is increased or decreased in accordance with an increase or decrease in the operation amount of the brake pedal until the braking system including the brake booster is activated, and the braking system outputs the braking force. , The regenerative braking force is kept constant.
[0003]
[Problems to be solved by the invention]
By the way, in a truck, the required braking force differs greatly between the loaded state and the empty state. However, in the braking system having the above-described brake booster, the boosting ratio of the brake booster is constant, It has been difficult to secure a suitable braking force in both the vehicle state and the empty state.
On the other hand, in the electric vehicle, the regenerative braking force is increased in accordance with the increase in the operation amount of the brake pedal only until the braking system starts braking. The regenerative braking force cannot be increased, and the regenerative braking force of the regenerative braking device cannot be used effectively.
That is, in order to increase the regenerative braking force when the braking system starts braking and to effectively utilize the regenerative braking force, it is sufficient to set the braking system to start braking only by giving a large operation amount. For this purpose, the set load of the return spring of the master cylinder and the return spring of the brake booster constituting the braking system may be increased.
However, when such setting is performed, if the regenerative braking device does not operate, the braking force by the above-described braking system cannot be obtained until the brake pedal is largely operated, and the braking force is not applied. It feels ineffective.
In view of such circumstances, the present invention can make the braking force different depending on the request when the required braking force differs greatly between the loaded state and the empty state such as a truck, and In the case where the regenerative braking device is not used in an electric vehicle, the regenerative braking force when the braking system starts braking can be effectively used by increasing the regenerative braking force. Even so, the present invention provides a braking system including a brake booster that can operate the above-mentioned braking system with a small operation amount.
[0004]
[Means for Solving the Problems]
That is, the present invention relates to a conventional general braking system including a brake booster, wherein an actuator for biasing the input shaft of the brake booster in a direction opposite to a stepping direction of the brake pedal is provided , and When the pedaling force is applied, the actuator is deactivated, and the input shaft is advanced with respect to the valve body to operate the valve mechanism.
[0005]
[Action]
According to the above configuration, if the input shaft is biased by the actuator with a required force in the direction opposite to the brake pedal depression direction, the valve mechanism is operated until the brake pedal depression force overcomes the biasing force. During this time, the boosting function of the brake booster is lost, so that the brake fluid pressure rises in response to the depression force of the brake pedal without being boosted by the brake booster. Therefore, in this state, the brake fluid pressure does not increase unless a large pedaling force is applied.
On the other hand, if the bias of the input shaft by the actuator is released, the brake fluid pressure is increased by the brake pedal depressing force while being subjected to the boosting action by the brake booster, similarly to a conventionally known brake booster without an actuator. It will rise accordingly. Therefore, in this state, a large brake fluid pressure can be obtained with a small pedaling force.
Therefore, when the braking system of the present invention is applied to a truck in which the required braking force differs greatly between the loaded state and the empty state, for example, manually or automatically, the loading force of the input shaft by the actuator is loaded when the vehicle is loaded. It should be small or zero. In this state, a boosting action by the brake booster can be performed with a light pedaling force, so that a strong braking action corresponding to the loaded state can be obtained.
On the other hand, when the input shaft is set to a large force by the actuator when the vehicle is idle, the brake booster cannot be operated until a large depressing force is applied to the input shaft. The effect can be small or substantially zero, so that the braking force can be small enough to be suitable when the vehicle is idle.
Further, when the braking system of the present invention is applied to the electric vehicle, the valve mechanism is not switched by the biasing force of the actuator until a large regenerative braking force is obtained, that is, the boosting action by the brake booster is performed. Should not be obtained. Then, when the regenerative braking force of the regenerative braking device becomes inaccurate, the boosting effect of the brake booster can be obtained by releasing the urging force of the actuator. The braking force can be increased by the device.
In the event that the regenerative braking device does not operate, the urging force of the actuator may be released, and the boosting effect of the brake booster is immediately obtained. A safe braking action can be performed from within.
[0006]
【Example】
Hereinafter, an embodiment in which the present invention is applied to an electric vehicle will be described. In FIG. 1, the electric vehicle includes a braking system 2 according to the present invention which increases and decreases a mechanical braking force in accordance with an increase and decrease in a depression force of a brake pedal 1. And a regenerative braking device 3 for increasing or decreasing the regenerative braking force in accordance with the increase or decrease in the stroke amount of the brake pedal 1.
The braking system 2 includes a tandem-type negative pressure type brake booster 4, which will be described in detail later, and a negative pressure is supplied to the brake booster 4 through a negative pressure introducing pipe 5. It has become. The above-described brake pedal 1 is connected to the input shaft 6 of the brake booster 4. The brake booster 4 boosts the pedaling force applied to the input shaft 6 through the brake pedal 1 to master the brake pedal. The power can be transmitted to the cylinder 7. The brake fluid pressure generated in the master cylinder 7 is supplied to a wheel cylinder (not shown) of the wheel to generate a mechanical braking force.
On the other hand, the regenerative braking device 3 performs a regenerative braking operation at the time of braking by using a drive motor 8 that drives the wheels of an electric vehicle, as is well known in the related art. A control device 10 for inputting a signal from a stroke sensor 9 for detecting a stroke amount is provided. The control device 10 increases the regenerative braking force up to the maximum regenerative braking force of the regenerative braking device 3 when the brake pedal 1 is depressed, in accordance with the increase in the depression force applied to the brake pedal 1, and When the braking force reaches the maximum regenerative braking force, the maximum regenerative braking force is maintained thereafter even when the brake pedal 1 is depressed.
[0007]
Next, the inside of the shell 11 of the brake booster 4 is defined by a center plate 12 into a front chamber 13 on the front side and a rear chamber 14 on the rear side. A substantially cylindrical valve body 18 is slidably penetrated through the shaft portion of the end via bearings 16 and 17, and the end cylindrical portion of the valve body 18 is projected outside from the opening of the shell 11.
A front power piston 20 and a rear power piston 21 are connected to the outer periphery of the valve body 18 located in the front chamber 13 and the rear chamber 14, respectively. The rear diaphragm 23 is stretched. A constant pressure chamber A and a variable pressure chamber B are formed before and after the front diaphragm 22, and a constant pressure chamber C and a variable pressure chamber D are formed before and after the rear diaphragm 23.
A valve mechanism 25 for switching the communication between the constant pressure chambers A and C and the variable pressure chambers B and D is provided in the valve body 18. As shown in an enlarged manner in FIG. 2, the valve mechanism 25 has an annular first valve seat 26 formed on the valve body 18, and is slidably mounted on the valve body 18 inside the annular first valve seat 26. An annular second valve seat 28 formed on the provided valve plunger 27 and a valve body 30 further seated on both valve seats 26, 28 by a spring 29.
A vacuum valve 32 is constituted by the first valve seat 26 and an annular seat portion of a valve body 30 which comes in contact with and separates from the first valve seat 26. The constant pressure chamber A communicates with the constant pressure chamber A via a constant pressure passage 34 extending in the other axial direction. Negative pressure is constantly introduced into the constant-pressure chamber A via the above-described negative-pressure introduction pipe 5, whereby the atmosphere is also introduced into the variable-pressure chamber C via the constant-pressure passage 34.
Further, a space inside the vacuum valve 32 and on the outer periphery side of the atmosphere valve 35 formed by the second valve seat 28 and the seat portion of the valve body 30 which comes in contact with and separates from the second valve seat 28 has a radial direction formed in the valve body 18. The variable pressure chamber D communicates with the variable pressure chamber D via the variable pressure passage 36, and the variable pressure chamber D communicates with the variable pressure chamber B via a variable pressure passage 37 formed in the axial direction of the valve body 18.
Further, a space on the inner peripheral side of the atmosphere valve 35 is provided via a pressure passage 38 formed between the inner peripheral surface of the valve body 18 and the outer peripheral surface of the input shaft 6 pivotally connected to the right end of the valve plunger 27. The filter 39 is provided in the pressure passage 38 in communication with the atmosphere, as will be described later in detail.
On the other hand, the left end of the valve plunger 27 is opposed to a reaction disk 41 housed in the base of the output shaft 40. The left end of the output shaft 40 penetrates the opening of the wall surface of the shell 11 and is linked to the piston of the master cylinder 7. The valve body 18 is normally held at a non-operating position by a return spring 42 mounted on the shell 11 and the valve body 18.
The above-described configuration and the operation based on the configuration are the same as those of a conventionally known tandem brake booster.
[0008]
In this embodiment, however, the brake booster 4 is provided with an actuator 50 for urging the input shaft 6 in the direction in which the brake pedal 1 is depressed, that is, in the right direction opposite to the left direction in FIG.
The actuator 50 includes a piston 51 and a cylinder 52. The piston 51 is held between a step 6 a formed on the input shaft 6 and a retainer 53 attached to the input shaft 6 and fixed to the input shaft 6. are doing. On the other hand, the cylinder 52 is slidably attached to the input shaft 6, and this cylinder 52 is composed of a bottomed cylindrical shell 54 and a spherical member 55 for closing the front opening of the shell 54. is there.
The shell 54 is formed with a large thickness and is slidably fitted on the input shaft 6 and extends radially outward. A sliding wall 54a extends axially forward from the outer periphery of the sliding wall 54a. The piston 51 is slidably fitted in the tubular portion 54b. The spherical member 55 includes a cylindrical sliding portion 55a surrounding the outer peripheral portion of the input shaft 6, and a wall portion 55b extending radially outward from a rear end of the sliding portion 55a.
[0009]
The cylinder 52 is urged toward the front side by a spring 57 elastically mounted between the cylinder 52 and a clevis 56 attached to the rear end of the input shaft 6, and the spherical member 55 of the cylinder 52 is moved toward the valve body. 18 is in contact with the end cylindrical portion. At this time, the contact surface of the spherical member 55 with the end cylindrical portion of the valve body 18 is formed into a concave spherical shape centered on the distal end spherical portion 6b of the input shaft 6, so that the input shaft 6 is Even if the cylinder 52 swings around the tip spherical portion 6b, the cylinder 52 is not displaced in the axial direction.
When the spherical member 55 is brought into contact with the end cylindrical portion of the valve body 18 , the pressure passage 38 is closed. Therefore, an atmosphere chamber 58 is formed on the left side of the piston 51 in the cylinder 52. The air chamber 58 is communicated with the atmosphere through a plurality of openings 59 formed in the cylindrical portion 54b of the shell 54 and the opening 60a of the dust cover 60 that overlaps the same, and at the same time, the atmosphere chamber 58 is connected to the wall 55b of the spherical member 55. By communicating with the pressure passage 38 through the formed air introduction hole 61, the atmosphere can be always introduced into the pressure passage 38.
On the other hand, a pressure chamber 62 is formed on the right side of the piston 51 in the cylinder 52. In the pressure chamber 62, an atmosphere or a negative pressure is selected via a flexible conduit 63 and a flow path switching valve 64. It can be supplied on a regular basis. The flow path of the flow path switching valve 64 is controlled to be switched by the control device 10.
[0010]
In the above configuration, during normal traveling in which the brake pedal 1 is not depressed, the control device 10 deenergizes the flow path switching valve 64 to introduce atmospheric pressure into the pressure chamber 62. When the brake pedal 1 is depressed from this state, the control device 10 detects this by the stroke sensor 9 and immediately excites the flow path switching valve 64 to introduce a negative pressure into the pressure chamber 62. Then, the cylinder 52 tries to move to the left side with respect to the input shaft 6, but since the cylinder 52 is in contact with the terminal cylindrical portion of the valve body 18, the input shaft 6 moves to the right in FIG. That is, the brake pedal 1 is urged in a direction opposite to the stepping direction. At this time, the rightward movement of the input shaft 6 is regulated by a key member 65 for preventing the valve plunger 27 from falling off the valve body 18.
Therefore, in this state, even if the brake pedal 1 is depressed, the input shaft 6 cannot advance relatively to the valve body 18, so that the input shaft 6 is integrated with the valve body 18 without switching the valve mechanism 25. That is, the vehicle is advanced against the return spring 42 without obtaining the boosting action of the brake booster 4. When the valve body 18 is advanced, the output shaft 40 is advanced accordingly, so that a brake fluid pressure is generated in the master cylinder 7 to perform the braking action.
On the other hand, when the brake pedal 1 is depressed by the stroke sensor 9, the control device 10 immediately causes the regenerative braking device 3 to perform the regenerative braking action. At this time, since the boosting action of the brake booster 4 is not performed as described above, the braking force by the braking system 2 is maintained at a minimum, and therefore the braking action by the regenerative braking device 3 is reduced. It can be used effectively. During this time, the control device 10 increases the regenerative braking force to the maximum regenerative braking force according to the increase in the stroke amount of the brake pedal 1.
When it is detected via the stroke sensor 9 that the stroke amount of the brake pedal 1 has exceeded a predetermined value, in that case, the control device 10 determines that a large braking force is required, and The switching valve 64 is deenergized to introduce the atmosphere into the pressure chamber 62. As a result, the input shaft 6 can move forward with respect to the valve body 18, whereby the flow path of the valve mechanism 25 is switched, and the boosting action by the brake booster 4 can be obtained. Therefore, thereafter, a powerful braking action by the brake booster 4 is performed.
If the vehicle speed is equal to or lower than a predetermined value when the brake pedal 1 is depressed, the control device 10 sets the flow path switching valve 64 to a state in which the flow path switching valve 64 remains deenergized regardless of the stroke amount of the brake pedal 1. Therefore, in this case, the boosting action by the brake booster 4 can be immediately obtained.
[0011]
By the way, in the above embodiment, the braking system 2 is incorporated in the electric vehicle having the regenerative braking device 3 for increasing / decreasing the regenerative braking force. However, it is needless to say that the braking system 2 can be incorporated in a vehicle without the regenerative braking device 3. It is.
More specifically, for example, the braking system 2 including the above-described brake booster 4 is incorporated in a truck, and when the truck is in a loaded state, the urging force by the actuator 50 is made substantially zero, so that the brake booster 4 is used. A boosting action is immediately obtained so that a strong braking force is obtained. On the other hand, when the truck is empty, the urging force of the actuator 50 is increased to prevent the boosting action of the brake booster 4 from being obtained, thereby preventing an excessively large braking force from being generated and locking the wheels. Can be prevented.
In this case, by controlling the magnitude of the negative pressure introduced into the pressure chamber 62 by a load sensor that detects whether the vehicle is in a loaded state or an empty state, the urging force by the actuator 50 can be controlled to be large or small. When the pedaling force of the pedal 1 exceeds the biasing force of the actuator 50, the brake 1 can be variably controlled so that the boosting action of the brake booster 4 is obtained.
[0012]
FIG. 3 shows a second embodiment of the present invention. In the first embodiment described above, the piston 51 constituting the actuator 50 is fixed to the input shaft 6 and the cylinder 52 is slid. In the present embodiment, a cylinder 152 constituting the actuator 150 is fixed to the input shaft 106, and the piston 151 is slidable.
The cylinder 152 includes a cup-shaped shell 154 fitted on the outer periphery of the input shaft 106, and a side wall 171 disposed on the right side of the shell 154, and a stepped portion 106b having the side wall 171 formed on the input shaft 106. And a retainer 153 fixed to the input shaft 106 and fixed to the input shaft 106. Then, the cylinder 152 is fixed to the input shaft 106 by caulking the right end engaging portion 154a of the shell 154 to the outer peripheral surface of the side wall 171 and connecting them together.
On the other hand, a piston 151 slidably provided on the input shaft 106 has a cylindrical sliding portion 151a extending to the front side along the outer peripheral surface of the input shaft 106, and a radius from the center of the sliding portion 151a. A movable wall portion 151b extending outward in the direction is provided, and the left end of the sliding portion 151a protrudes forward from the shell 154 to engage with the spherical member 155. The spherical member 155 is brought into contact with the end cylindrical portion of the valve body 118 by a spring 157.
In this embodiment, the air can be constantly introduced into the pressure passage 138 by the slit 172 formed at the end of the valve body 118. It is needless to say that a through hole may be formed instead of the slit 172.
Further, a pressure chamber 162 is formed on the left side of the movable wall portion 151b of the piston 151, and this pressure chamber 162 is connected to a flow path switching valve via a flexible conduit 163 as in the above-described embodiment. ing. The chamber on the right side of the movable wall portion 151b communicates with the atmosphere via an opening 171a formed in the side wall 171.
Other configurations are the same as those of the first embodiment, and the same members as those of the first embodiment are denoted by the reference numerals obtained by adding 100 to the reference numerals used in the first embodiment.
It is clear that the same operation and effect as those of the first embodiment can be obtained by the configuration of the second embodiment.
[0013]
【The invention's effect】
As described above, according to the present invention, the input shaft of the brake booster can be urged by the actuator in the direction opposite to the direction in which the brake pedal is depressed. When the required braking force differs greatly, the braking force can be varied according to the requirement. In addition, when used in electric vehicles, the regenerative braking force can be increased to increase its effective use. Therefore, the effect that the safety can be improved can be obtained.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a first embodiment of the present invention.
FIG. 2 is an enlarged sectional view of a main part of FIG.
FIG. 3 is a sectional view showing a second embodiment of the present invention.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 brake pedal 2 braking system 3 regenerative braking device 4 brake booster 6, 106 input shaft 10 control device 18, 118 valve body 25, 125 valve mechanism 26 first valve seat 27, 127 Valve plunger 28 second valve seat 30 valve element 50, 150 actuator 51, 151 piston 52, 152 cylinder 55, 155 spherical member 62, 162 pressure chamber 61 air introduction hole 172 slit

Claims (5)

A brake booster that boosts the depression force of the brake pedal, and a master cylinder that is activated by the brake booster and generates brake fluid pressure,
The brake booster is movably provided in the shell, and has a valve body having a rear cylindrical portion projecting to the outside of the shell, and a valve body provided on an outer periphery of the valve body. A power piston that forms a variable pressure chamber on the rear side, a valve mechanism that is housed in the valve body and switches a flow path, a pressure passage that is formed in the end cylindrical portion and that is open to the atmosphere, A braking mechanism provided with a brake booster, comprising: an input shaft for operating the valve mechanism to switch the flow path, supply air to the variable pressure chamber from the pressure passage, and advance the power piston.
An actuator is provided on the input shaft of the brake booster to urge the brake pedal in a direction opposite to the stepping direction of the brake pedal, and when a predetermined pedaling force is applied to the brake pedal, the actuator is deenergized, and the input shaft is moved relative to the valve body. A braking system comprising a brake booster, wherein the brake mechanism is operated by moving the valve forward . The actuator is slidably provided on the input shaft and abuts against the end cylindrical portion of the valve body from the rear side. The actuator is slidably fitted in the cylinder while maintaining airtightness. A piston fixed to the input shaft, and a cylinder formed in the cylinder, which presses the cylinder against the terminal cylindrical portion of the valve body when the pressure fluid is introduced, thereby causing the input shaft to move in a direction opposite to the direction in which the brake pedal is depressed. The braking system according to claim 1, further comprising a pressure chamber that biases in a direction. The actuator includes a cylinder fixed to the input shaft, a piston slidably fitted in the cylinder and abutting against the rear end of the valve body from the rear side thereof, and a pressure valve formed in the cylinder. A pressure chamber for biasing the input shaft in a direction opposite to a direction in which a brake pedal is depressed by pressing a piston against a terminal cylindrical portion of the valve body when a fluid is introduced. Item 2. A braking system comprising the brake booster according to item 1. The contact surface of the cylinder or the piston with the end cylindrical portion of the valve body is formed in a concave spherical shape centered on a spherical end portion of the input shaft. A braking system comprising the brake booster according to any one of the above. The brake booster and the master cylinder are used for an electric vehicle, and the electric vehicle uses an electric drive motor that drives a wheel and a regenerative braking force of the wheel using the drive motor. The brake booster according to any one of claims 1 to 4, further comprising: a regenerative braking device, wherein the operation of the actuator is controlled based on the operation of the regenerative braking device. Braking system.

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