JPH0137962Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a brake device for a vehicle.

In a vehicle's brake system, there is a space between the brake pedal and the master cylinder in order to always obtain sufficient braking force for the maximum speed and weight of the vehicle, and to reduce driver fatigue by reducing the force applied to the brake pedal. Some models are equipped with a booster that amplifies the pedal effort. In boosters that have been commonly used in the past, the output of the booster that is amplified is in a constant relationship with the pedal depression force. However, especially for commercial vehicles such as trucks, the vehicle weight varies greatly between when it is fully loaded and when it is empty.
In order to obtain the same deceleration rate, it is necessary to change the pedal depression force according to the increase or decrease in weight. If the output of the booster is set so that sufficient braking force can be obtained even when the vehicle weight is large,
If the weight is light, there is a risk that the wheels will lock with a small pedal force, impairing braking stability. Further, since the pedal depression force and its reaction force are proportional, if the weight of the vehicle is large, the driver will receive a large reaction force, increasing the driver's fatigue level.

In addition, in the brake system, in order to prevent the rear wheels from locking up before the front wheels due to load transfer during braking, a pressure control valve is installed in the brake circuit connected to the rear wheel brakes. It is already known that when the force exceeds a certain predetermined value, its rate of increase is lower than the rate of increase of the front wheel braking force. Pressure control valves that have been generally employed have a structure in which the transition point at which the rate of increase in rear wheel braking force begins to decrease is fixed. However, in order to always maintain high braking efficiency without causing the rear wheels to lock, regardless of the vehicle weight, it is necessary to change the front and rear wheel brake force distribution in accordance with the vehicle weight.

The present invention has been made in view of the above, and consists of a fluid pressure source and a multiplier that is actuated by the fluid from the fluid pressure source according to the depression force of the brake pedal and transmits the amplified output to the master cylinder. a front wheel brake and a rear wheel brake that are operated by brake fluid pressure generated by a master cylinder; and a front wheel brake and a rear wheel brake that are provided between the fluid pressure source and the booster; A regulating valve that adjusts the pressure or flow rate of the supplied fluid, and provided between the master cylinder and the rear wheel brake,
At least in response to pressure within the same rear brake,
A pressure control valve that reduces the brake fluid pressure supplied to the rear wheel brake when the pressure exceeds a predetermined pressure value, and a pressure control valve that is operated based on a command from the controller according to the vehicle weight, and the adjustment valve. a first drive device that controls the regulating valve so as to change the pressure or flow rate to be regulated; and the pressure that is operated based on a command from the controller according to the vehicle weight and that is set by the pressure control valve. The gist of the present invention is a brake device characterized by comprising a second drive device that controls the pressure control valve so as to change the value thereof.

According to the above configuration, the transition point at which the output of the booster and the rate of increase in rear wheel braking force begin to decrease is changed in response to changes in vehicle weight,
Therefore, even if the weight of the vehicle changes, it is possible to obtain a constant deceleration with a constant pedal force, and even when the vehicle weight is light, it is possible to prevent the rear wheels from locking with a small pedal force, improving braking stability and This allows high braking efficiency to be maintained at all times.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing an outline of a hydraulic servo brake device according to a first embodiment of the present invention. Oil is pumped from a reservoir 1 through a hydraulic source 2 such as an oil pump, and After the flow rate is adjusted according to the weight of the vehicle by the flow rate adjustment valve or the variable throttle valve 3, it is supplied to the hydraulic booster 4, and a portion returns to the reservoir 1. During braking, the pressure oil supplied to the booster 4 drives the booster 4 according to the pedal force applied from the pedal 5, and the amplified output from the booster operates the master cylinder 6, but when the brake is released. Sometimes it returns to Reservoir 1. The brake hydraulic pressure generated by the master cylinder 6 is
The pressure is directly supplied to the front wheel brakes 7, and after the pressure is controlled by a variable pressure control valve 8 according to the weight of the vehicle, it is supplied to the rear wheel brakes 9. The weight signal detected by the vehicle weight sensor 10 is input to the controller 11, and the controller controls the drive device 12 that controls the flow rate of the variable throttle valve 3 and the pressure of the variable pressure control valve 8 based on this signal. The drive devices 13 are respectively operated.

Next, each component will be explained in detail.

In FIG. 2, the variable throttle valve 3 is connected to the cylinder 2.
0, an inlet 21 connected to a hydraulic source 2 and a return opening 2 connected to a reservoir 1;
The spool valve 23 has two springs 26 and 27 interposed between lands 24 and 25 of the spool valve and the cylinder 20. By adjusting the opening degree of the opening 22, the flow rate of the pressure oil flowing from the chamber 28 between the lands 24 and 25 to the booster 4 via the outlet 29 is controlled. Spool valve land 2
A rod 30 is provided protruding from the rod 4 and is connected to the drive device 12.

The booster 4 is slidably fitted into the cylinder 40 and includes an inlet chamber 41 communicating with the outlet 29 and a return chamber 4 communicating with the reservoir 1 via a return opening 42.
3 and a spool-shaped piston 45 whose limits are the pressure chamber 44; a spool valve 47 that is slidably fitted into a cylindrical hole 46 of the piston to control communication between the chambers 41, 43, and 44; A valve member 50 is slidably fitted into the cylindrical hole 48 of the valve and is connected to a rod 49 that interlocks with the pedal 5, and is interposed between the cylinder 40 and the piston 45, and is arranged to move the piston to the right. A spring 52 is interposed between the bottom wall of the hole 46 and the spool valve 47, and the spring 52 is biased to the right to abut the stopper 51, and the spring 52 is inserted between the bottom wall of the hole 46 and the spool valve 47. A spring 54 is inserted between the bottom wall of the hole 48 and the valve member 50, and a spring 56 is inserted between the bottom wall of the hole 48 and the valve member 50, and urges the valve member to the right to contact the stopper 55 on the spool valve 47. have. A rod 57 is provided protruding from the piston 45 and is connected to a push rod 58 of the master cylinder 6. In the brake release position of the booster 4 shown in FIG. 2, the land 59 of the spool valve 47 is located to the right of the opening 60 provided in the piston 45, and the inlet chamber 41
0, opening 6 provided in hole 46 and piston 45
1 and communicates with a return chamber 43. Further, the opening 62 provided in the spool valve 47 and the T-shaped opening 63 provided in the valve member 50 are aligned, and the pressure chamber 4
4 also communicates with the return chamber 43 via openings 62 and 63, the bore 48 and an opening 64 provided in the spool valve 47.

The drive device 12 includes a booster 4 necessary to generate the optimum maximum braking force depending on the vehicle weight.
maximum output (highest hydraulic pressure generated within the pressure chamber 44)
Spool valve 2 of variable throttle valve 3 so as to set
controller 1.
1, a motor 70 is rotationally driven in a predetermined direction by
, a plate 72 screwed onto a screw shaft 71 integral with the rotating shaft of the motor, and an arm 73 connecting the plate and the rod 30 of the spool valve 23. The intermediate portion of the arm 73 is formed in the shape of a band plate, and is slidably fitted into a groove of a block 74 fixed to an immovable member, thereby preventing rotation of the plate 72. Accordingly, the plate 72, arm 73, rod 30, and spool valve 23 move left and right as one body depending on the direction of rotation of the screw shaft 71. The amount of displacement of the spool valve 23 is measured by a tachometer 75 attached to the motor 70 or a displacement meter 77 that accommodates the free end of the arm 76 fixed to the plate 72 and directly detects the amount of displacement. Ru.

In FIG. 3, the variable pressure control valve 8 controls the rear wheel brake oil pressure according to the brake oil pressure from the master cylinder 6 and the oil pressure to the rear wheel brake 9, and according to the vehicle weight. Hole 8
0, an inlet 81 connected to the oil outlet of the master cylinder 6 and an outlet 82 connected to the rear wheel brake 9
a housing 83 having a housing 83 slidably disposed within the bore 80 to demarcate an inlet pressure chamber 84 and an outlet pressure chamber 85 and cooperating with an annular seal 87 mounted on a step 86 of the bore 80; Both pressure chambers 84 and 8
A piston-shaped valve member 88 that controls communication between 5 and 5.
, the large diameter left end portion 89 of the valve member and the housing 8
The spring 91 is interposed between the valve member 88 and the adjusting screw 90 screwed into the valve member 88, and urges the valve member 88 rightward to the open position shown in FIG. In this open position, the small diameter right end 92 of the valve member 88 is spaced from the seal 87, and the land 93 abuts a plurality of circumferentially spaced protrusions 94 on the seal 87; Additionally, the annular lip 95 of the seal 87 is in pressure contact with the inner surface of the hole 80;
Therefore, the inlet pressure chamber 84 communicates with the outlet pressure chamber 85 via the plurality of grooves 96 provided on the outer periphery of the land 93 and the gap between the seal 87 and the valve member 88. The seal 87 is provided with a groove 97 on its bottom and outer circumference that allows oil to flow from the outlet pressure chamber 85 to the inlet pressure chamber 84 when the brake is released.
The adjusting screw 90 has an end (not shown) attached to a drive device 13 having a structure similar to the drive device 12 shown in FIG.
When rotated in one direction, the spring 9 moves toward the valve member 88 .
1 increases the setting force; when rotated in the opposite direction, it moves away from the valve member 88 and decreases the setting force. In this case, it is necessary to connect the adjustment screw 90 to the rotating shaft of the motor 70 via a spline joint or the like, and to attach the plate 72 to the joint part that moves from side to side integrally with the adjustment screw. be.

First, the basic operation of the above-mentioned brake device will be explained.

When no pedal force is applied to the pedal 5, the booster 4 is in the brake release position shown in FIG.
The pressure oil from the hydraulic source 2 whose flow rate is adjusted by the variable throttle valve 3 flows into the chamber 2 as shown by the arrow in FIG.
8. Returns to the reservoir 1 through the inlet chamber 41, return chamber 43, and return opening 42, and the pressure chamber 44 communicates with the return chamber 43 and is at low pressure, so the booster 4 outputs to the master cylinder 6. not given.

When applying force to the pedal 5 during braking, the rod 49
The valve member 50 moves relative to the spool valve 47 while compressing the spring 56 and opens the opening 6.
2 is closed by the valve member 50, and the pressure chamber 44
Communication between this and the return chamber 43 is cut off. At the same time, the pedal depression force transmitted via the spring 56 is
While compressing the spring 54, the spool valve 47
is moved relative to the piston 45, and the land 59 is positioned approximately at the center of the opening 60, so that the inlet chamber 41 and the pressure chamber 44 are communicated through the opening. Therefore, part of the pressure oil that has flowed into the inlet chamber 41 from the chamber 28 flows into the pressure chamber 44, and the pressure within the chamber 44 begins to rise, causing the piston 45 to move to the left against the force of the spring 52. The output for operating the master cylinder 6 is transmitted via rods 57 and 58.

When further pedal force is applied, the land 59 is positioned to the left of the opening 60, and communication between the entrance chamber 41 and the return chamber 43 is cut off. Therefore, the entire amount of the pressure oil that has flowed into the inlet chamber 41 flows into the pressure chamber 44, the pressure within the same chamber 44 further increases, and the maximum output transmitted to the master cylinder 6 is obtained.

The brake hydraulic pressure generated by the operation of the master cylinder 6 is supplied directly to the front wheel brake 7 and also to the inlet pressure chamber 84 of the variable pressure control valve 8 . Since the valve member 88 is normally in the open position shown in FIG. power and rear wheel braking force.

The valve member 88 has a biasing force to the left due to the outlet pressure in the outlet pressure chamber 85 that acts on a large pressure-receiving area at the right end portion 92, and an inlet pressure chamber that acts on a small pressure-receiving area at the left peripheral edge of the land 93. A biasing force to the right is exerted due to the inlet pressure in 84 and the force of spring 91. Therefore, as the oil pressure from the master cylinder 6 increases, the inlet pressure and the outlet pressure equally increase, and when the above two biasing forces exceed a balanced value (hereinafter referred to as the transition point), the biasing force to the left will shift to the right. The valve member 88 is moved to the left, and the right end portion 92 approaches the seal 87, thereby restricting communication between the inlet pressure chamber 84 and the outlet pressure chamber 85. After the transition point, the outlet pressure is maintained at a value lower than the inlet pressure, corresponding to the ratio between the two pressure-receiving areas of the valve member 88. As a result, after the transition point, the rate of increase in rear wheel brake force is kept lower than the rate of increase in front wheel brake force, and locking of the rear wheels is prevented.

When the pedal 5 is released from the force when the brake is released, the springs 52, 54, and 56 push the piston 45, spool valve 47, and valve member 50 back to the positions shown in FIG.
is again communicated with the return chamber 43, the oil pressure in the chambers 41 and 44 is discharged to the reservoir 1 and lowered, and the output to the master cylinder 6 is also canceled.

At the same time, as the oil pressure from the master cylinder 6 decreases, the oil pressure supplied to the front wheel brakes 7 and the variable pressure control valve 8 also decreases. As the inlet pressure in the inlet pressure chamber 84 decreases, the biasing force to the left increases, and the right end 92 of the valve member 88
is engaged with seal 87 to cut off communication between pressure chambers 84 and 85, but the outlet pressure, which is higher than the inlet pressure, acts on lip 95 through groove 97 and forces it into hole 80. Because it is separated from the surface,
The hydraulic pressure in the rear brake 9 is discharged to the master cylinder 6 via the outlet pressure chamber 85, the gap between the lip 95 of the seal and the hole 80, and the inlet pressure chamber 84. When the rightward biasing force becomes greater than the leftward biasing force due to the decrease in outlet pressure, the valve member 88 is moved again to the open position shown in FIG. It is discharged to the master cylinder 6 through the gap between the valve member 88 and the valve member 88 .

The above operation is performed when the vehicle weight is in a certain constant state, but if the weight changes, the maximum hydraulic pressure that can be generated in the booster 4 is adjusted by the variable throttle valve 3. By adjusting and controlling the maximum output of the booster 4 and the maximum brake oil pressure of the master cylinder 6, a desired braking deceleration can be obtained regardless of changes in weight. In the variable pressure control valve 8, the outlet pressure is a constant ratio between the pressure receiving areas and the inlet pressure, and since the pressure receiving area is a constant, the outlet pressure and the spring 9
The force is proportional to 1, and the outlet pressure increases or decreases as the spring force increases or decreases, so if you change the spring force in response to changes in vehicle weight, you can also change the transition point of the rear wheel braking force. The desired front and rear wheel brake force distribution can be obtained.

Therefore, the vehicle weight W is detected by the vehicle weight sensor 10, and a weight signal corresponding to this weight W is input to the controller 11. Controller 1
Based on this signal, the maximum hydraulic pressure in the booster 4 and the spring force of the variable pressure control valve 8 suitable for the weight W are determined from preset characteristic data, and the displacement of the spool valve 23 is determined. and the amount of displacement of the adjusting screw 90, and each drive device 12, 13
the actual displacement amount detected by the tachometer 75 or the displacement meter 77 while driving the motor 70;
Feedback control is performed by comparing the amount of displacement with the predetermined displacement amount.

To explain this control mode, in the variable throttle valve 3, for example, the vehicle weight W is set to a value like when the vehicle is empty.
In the case of W ₁ , the controller 11 rotates the motor 70 of the drive device 12 in one direction according to this value, and the plate 72 and the spool valve 23 integrally connected thereto move a relatively small amount to the left. will be moved. As a result, the opening degree of the return opening 22 is narrowed to a predetermined maximum value by the land 24 of the spool valve,
Since the flow rate of the pressure oil flowing from the chamber 28 to the inlet chamber 41 of the booster 4 is small, the maximum oil pressure that can be generated in the pressure chamber 44 during braking is a certain low value. Conversely, when the vehicle weight W is the value W ₃ such as when the vehicle is at its maximum load, the controller 11 further rotates the motor 70 according to this value, and the plate 72 and the spool valve 2
3 is further moved to the left, and the opening degree of the opening 22 is narrowed down to a predetermined minimum value or the opening is completely blocked. Therefore, the maximum oil pressure that can be generated in the pressure chamber 44 during braking becomes a certain large value or the maximum pressure of the oil supplied to the inlet 21, and the maximum output of the booster 4 increases. Vehicle weight W has values W ₁ and W ₃
For example, when the value is a predetermined intermediate value _W2 as in the case of a light-duty vehicle, the spool valve 23 is moved to a predetermined position by the controller 11 and motor 70, and the opening 22 is opened. The maximum oil pressure in the pressure chamber 44 and the maximum output of the booster 4 are set to predetermined intermediate values.

Incidentally, the reaction force when the pedal 5 is depressed is determined by the reaction force of the spring 54, and this spring force is determined by the amount of displacement of the spool valve 47 with respect to the piston 45. In other words, if the amount of displacement is the same,
The pressing force on the pedal 5 is the same.

As a result, by changing the amount of displacement of the spool valve 23 in response to changes in vehicle weight, the output of the booster 4 changes even with the same pedal effort, and the booster also changes the output of the booster 4 from the master cylinder 6. The brake hydraulic pressure generated in the master cylinder can also be varied accordingly.

The characteristic of brake force with respect to pedal depression force obtained in this manner is shown in FIG.

Next, in the variable pressure control valve 8, the vehicle weight W is set to a value
In the case of W ₁ , the controller 11 rotates the motor of the drive device 13 according to this value, rotates the adjustment screw 90 in one direction, moves it to the predetermined left end position, and therefore moves the valve member 88 to the right. The setting force of the spring 91 that biases the position becomes a predetermined minimum value. As a result, the outlet pressure at the transition point will be at a certain low value. Conversely, when the vehicle weight W is the value _W3 , the controller 11 drives the motor according to this value to rotate the adjusting screw 90 in the opposite direction and move it to a predetermined right end position. As a result, the setting force of the spring 91 is at a predetermined maximum value, and the outlet pressure at the transition point is at a certain high value. When the vehicle weight W is an intermediate value _W2 between _W1 and _W3 , the adjusting screw 90 is moved to a predetermined intermediate position between the two end positions according to this value via the controller 11 and the drive device 13. , the setting force and outlet pressure of spring 91 are set to predetermined intermediate values.

The operation of this variable pressure control valve 8 is controlled by the variable throttle valve 3.
This is done in synchronization with the operation of As a result, even with the same pedal depression force, the brake oil pressure in the master cylinder 6 is continuously changed in response to changes in vehicle weight and is directly supplied to the front wheel brakes 7, resulting in an increase in front wheel brake force as shown in FIG. At the same time, this brake oil pressure is supplied to the rear wheel brake 9 after being lowered to a different pressure value or more, and the front and rear wheel brake force distribution characteristics as shown by the solid line in FIG. 5 are obtained. be.

Therefore, according to the present invention, even if the weight of the vehicle changes, it is possible to obtain a constant deceleration with a constant pedal force, and even when the vehicle weight is light, the rear wheels can be prevented from locking with a small pedal force. Therefore, braking stability and high braking efficiency can always be maintained.

In Fig. 5, the dashed line represents the front and rear brake force distribution characteristics by the variable pressure control valve in the case where the front wheel brake force, that is, the brake oil pressure of the master cylinder does not change even if the vehicle weight changes, and the dashed line represents the ideal brake force. It represents the force distribution characteristics.

In the embodiment described above, the setting force of the spring 91 of the variable pressure control valve 8 is continuously adjusted using electric means consisting of the vehicle weight sensor 10, the controller 11, and the drive device 13. Thus, the biasing force that biases the valve member 88 toward the open position can be continuously changed. That is, in a vehicle equipped with an air spring type suspension, the weight of the vehicle and the air pressure of the air spring are proportional. Therefore, this air pressure can be used as a weight signal and as a means for changing the setting force of the spring or a means for changing the urging force of the valve member 88 to the open position.

A modification of the first embodiment shown in FIG. 6 shows an example using pneumatic means, and the same components as those in FIG. 3 will be described with the same reference numerals.

In the variable pressure control valve 8 of FIG.
1 is interposed between the land 93 of the valve member 88 and the partition wall 98 of the inlet pressure chamber 84, and urges the valve member 88 to the open position with a predetermined setting force. Further, the left end portion 89 of the valve member 88 is sealingly and slidably engaged with the inner surface of the hole 80 so that the end wall of the hole 80 limits a control pressure chamber 99 . This control pressure chamber 99
is directly connected to the air spring via an inlet 100. Other structures are the same as those in FIG.

The operation of this variable pressure control valve 8 is substantially the same as that shown in FIG. Since this air pressure is proportional to the weight of the vehicle, the valve member 88 is biased to the right to the open position in response to changes in weight. The biasing force changes, and the transition point of the rear wheel braking force changes.

Therefore, this modification can also achieve the same effects as the first embodiment.

Although the above description is an example of a hydraulic servo brake device, it can also be implemented in an air servo brake device in the same manner as in the above embodiment.

An air servo brake device according to a second embodiment of the present invention will be described below, in which the same reference numerals are given to the same components as in the first embodiment.

In the block diagram of the air servo brake device shown in FIG.
The compressed air generated by the compressed air is stored in an accumulator 15, and after the pressure is adjusted according to the weight of the vehicle by a variable pressure regulating valve 16, it is supplied to a pneumatic booster 17. . The booster 17 generates an amplified output according to the pedal force applied to the pedal 5, and operates the master cylinder 6.

The structures and operations of the other components 6 to 13 are the same as those of the first embodiment, so detailed explanation thereof will be omitted.

In FIG. 8, the variable pressure regulating valve 16 has an inlet 110 connected to the air pressure source 14 and a booster 1.
housing 1 with an outlet 111 connected to 7;
12, and is slidably disposed within the same housing,
A valve member 115 that controls communication between the inlet pressure chamber 113 and the outlet pressure chamber 114, and a pressure chamber 117 that is fixed within the housing 112 and communicates with the outlet pressure chamber 114 through an opening 116 and an atmospheric release chamber 118. In addition, a diaphragm 119 that cooperates with the tip of the valve member 115 to control communication between the chambers 117 and 118, a spring 120 that biases the valve member 115 in the closing direction, and a spring 120 that is screwed to the housing 112. A spring 122 is interposed between the adjusting screw 121 and the diaphragm 119 and biases the diaphragm in the opening direction of the valve member 115. The adjusting screw 121 has its free end rotationally connected to the rotating shaft of the motor 70 of the drive device 12 described in detail with respect to FIG. 2 via a spline shaft joint 78, and when rotated in one direction, The spring 122 moves toward the diaphragm 119.
When rotated in the opposite direction, it moves away from the diaphragm and decreases the setting force. Note that the plate 72 is attached to a joint portion that moves from side to side integrally with the adjustment screw 121.

In FIG. 9, a booster 17 is slidably fitted in a housing 130 to limit a pressure chamber 131 and an atmosphere open chamber 132, and also limits both chambers 131 and 132.
a piston 134 having a cylindrical hole 133 that communicates between the piston 1 and 132; a regulator 136 that is slidably fitted in the hole 133 and connected to a rod 135 that interlocks with the pedal 5; and a housing 130.
A spring 137 is interposed between the bottom wall of the hole 133 and the regulator 136, and is interposed between the bottom wall of the hole 133 and the regulator 136, and urges the piston to the right to abut the housing 130. It has springs 140 and 141 that bias the seal 138 to the right and seat the seal 138 on the seat 139, and the spring 141 has a shorter natural length than the spring 140. The regulator 136 is connected to the inlet 14
2, the pressure chamber 131 and the atmosphere release chamber 132 are connected to the outlet 111 of the variable pressure regulating valve through the regulator 136. a pilot chamber 145 that communicates with the inlet chamber 143 and a nozzle 146 that communicates the pilot chamber with the hole 133;
7 to the pilot chamber 145 , a passage 149 which can communicate with the same and communicate with the pressure chamber 131 , and a passage 149 which is delimited by the diaphragm 144 and which can communicate with the passage 149 . In addition, an exhaust chamber 151 communicating with the atmosphere open chamber 132 via an exhaust passage 150, and a passage 14.
8 and 149, and the passage 14.
Valve member 15 that controls communication between 9 and exhaust chamber 151
2, and a spring 153 that biases the valve member toward the diaphragm 144. A pad 154 is attached to the piston 134 facing the nozzle 146, and a rod 155 that is connected to the master cylinder 6 is protruded from the opposite side.

The operation of the above brake device will be explained.

In a certain state of vehicle weight, the air pressure source 14 flows into the inlet pressure chamber 113 of the variable pressure regulating valve 16.
The compressed air from If it rises above the value,
Since both pressure chambers 114 and 117 communicate with each other through the opening 116, as the pressure inside the pressure chamber 117 increases, the diaphragm 119 is moved by the spring 122.
The valve member 115 is moved to the right and the communication between the inlet pressure chamber 113 and the outlet pressure chamber 114 is cut off. When the pressure within the outlet pressure chamber 114 falls below the above value, the spring 122 pushes the diaphragm 119 and the valve member 155 back to the left, allowing the outlet pressure chamber 114 to communicate with the inlet pressure chamber 113 again. In this way, spring 1
The valve member 115 is maintained in a state where the force of 22 and the pressure in the pressure chambers 114 and 117 acting on the diaphragm 119 are balanced, and the air pressure supplied from the outlet pressure chamber 114 to the booster 17 is adjusted.

When no pedal force is applied to the pedal 5, the booster 17 is in the brake release position shown in FIG. On the other hand, the pilot chamber 145 and the exhaust chamber 151 are opened to the atmosphere via the atmosphere opening chamber 132.

When applying force to pedal 5 during braking, rod 13
5, the regulator 136 is moved relative to the piston 134 while first compressing the spring 140, and the seal 138 is separated from the seat 139.
Compressed air within inlet chamber 143 flows into passageway 148 . A part of this air flows into the pilot chamber 145 through the pilot passage 147, and further flows into the nozzle 14.
6 and flows out from the atmosphere open chamber 132 to the atmosphere. When the pedal force is further applied, the spring 141 with a short natural length is also compressed, and the relative movement between the regulator 136 and the piston 134 increases, causing the nozzle 14
6 approaches pad 154, the nozzle back pressure, ie, the pressure within pilot chamber 145, increases. As a result, the diaphragm 144 and the valve member 152 are pushed to the right, the passage 148 and the passage 149 are communicated with each other, compressed air flows into the pressure chamber 131, the pressure in the same chamber begins to rise, and the piston 134 moves to the spring 137. The power to actuate the master cylinder 6 is transmitted via the rod 155. At the same time, the pressure in pressure chamber 131 is acting on diaphragm 144, and when the pressure increases until it balances the force due to the pressure in pilot chamber 145, spring 153 moves valve member 152 to the closed position.

In this way, the nozzle back pressure is determined according to the amount of displacement of the regulator 136 with respect to the piston 134, and therefore the pressure within the pressure chamber 131 and the output transmitted to the master cylinder 6 are determined.

When the force on the pedal 5 is released when the brake is released, the regulator 136 is activated by the springs 140 and 141.
is pushed back, and as a result, the gap between the nozzle 146 and the pad 154 becomes larger, and the pilot chamber 14
The pressure inside 5 decreases. As a result, the diaphragm 144 is moved to the left and separated from the valve member 152, and the air pressure in the pressure chamber 131 is transferred to the atmosphere opening chamber through the passage 149, the exhaust chamber 151, and the exhaust passage 150.
32 to the atmosphere and lowers the spring 1
37 pushes back the piston 134, and the output to the master cylinder 6 is released.

In the above operation, when the vehicle weight changes, the maximum air pressure that can be generated in the pressure chamber 131 of the booster 17 is adjusted by the variable pressure regulating valve 16 in response to the change, and the maximum air pressure of the booster is adjusted. By controlling the output and the maximum brake oil pressure of the master cylinder 6, a desired braking deceleration can be obtained regardless of changes in weight.

For this reason, the amount of displacement of the adjusting screw 121 of the variable pressure regulating valve is feedback-controlled by the vehicle weight sensor 10, controller 11, and drive device 12 in the same manner as described in connection with the first embodiment.

That is, in a certain state of the vehicle weight shown in FIG. 8, for example, when the vehicle weight W changes from a value W ₂ like when the vehicle is lightly loaded to a value W ₁ when the vehicle is empty, the controller 11 responds to this change. Accordingly, the motor 70 is rotationally driven to rotate the adjusting screw 121 in one direction to move it to a predetermined right end position, thereby reducing the setting force of the spring 122 that urges the diaphragm 119 to the left to a predetermined minimum value. . As a result, the pressure chamber 11
7 becomes larger than the force of the spring 122, the diaphragm 119 is moved to the right, and the valve member 115 separates both the pressure chambers 113 and 1.
14 is cut off, and the valve member 115
The tip of the diaphragm 119 separates from the diaphragm 119, and the pressure in the outlet pressure chamber 114 is exhausted through the atmosphere release chamber 118 and is reduced to a predetermined minimum value. When the pressure reaches a predetermined minimum value, diaphragm 119 engages valve member 115 and maintains the same in balance.

Conversely, when the vehicle weight W is at its maximum load, the value W ₃
, the controller 11 drives the motor 70 in response to this change, rotates the adjustment screw 121 in the opposite direction to move it to a predetermined left end position, and increases the setting force of the spring 122 to a predetermined maximum value. . As a result, the force of the spring 122 becomes greater than the force due to the pressure in the pressure chamber 117, the diaphragm 119 and the valve member 115 are moved to the left, the pressure in the outlet pressure chamber 114 is increased to a predetermined maximum value, Valve member 115 is then held in balance.

In this way, in response to changes in vehicle weight,
The air pressure supplied to the booster 17 is adjusted to a predetermined value, and the maximum air pressure in the pressure chamber 131 and the output of the booster are changed.

On the other hand, the reaction force when the pedal 5 is depressed is determined by the reaction force of the springs 140 and 141, but this spring force is determined by the amount of displacement of the regulator 136 with respect to the piston 134, and if the amount of displacement is the same, the pedal depression force will be be the same.

As a result, the amount of displacement of the adjustment screw 121 is changed in response to changes in vehicle weight, and the spring 12 is
By changing the setting force 2, the output of the booster 17 is changed even with the same pedal depression force,
The brake oil pressure from the master cylinder 6 can be changed accordingly, and the characteristics of the brake force with respect to the pedal depression force as shown in FIG. 4 can be obtained.

Since this operation is performed in synchronization with the control operation of the rear wheel brake force by the variable pressure control valve 8 described in detail in connection with the first embodiment, it is possible to obtain the front and rear wheel brake force distribution characteristics shown in FIG. It can be done.

Therefore, also in this second embodiment, the first
Effects equivalent to those of the embodiment can be achieved.

A modification of the second embodiment shown in FIG. 10 uses pneumatic means to change the biasing force to the left of the diaphragm 119 of the variable pressure regulating valve 16 in response to changes in vehicle weight. 8th
Components equivalent to those in the figures will be described with the same reference numerals.

In the variable pressure regulating valve 16 of FIG. 10, the spring 122 connects the diaphragm 119 and the housing 11.
2, and urges the diaphragm to the left with a predetermined setting force. Further, a piston 123 is fitted in the housing 112 in a sealed and slidable manner, and the piston 123 is fitted in the housing 112 to connect the control pressure chamber 1 with the housing.
24 and engages the diaphragm 119. This control pressure chamber 124 has an inlet 125
via which it is directly connected to the air spring of the air spring suspension described in connection with FIG.
Other structures are the same as those in FIG.

The operation of this variable pressure regulating valve 16 is substantially the same as the eighth one.
Although it is the same as the one shown in the figure, on the right side of the diaphragm 119, a constant force of the spring 122 and a force due to the air pressure in the control pressure chamber 124 acting on the piston 123 are acting, and this air pressure is controlled as described above. Since the weight of the vehicle is proportional to the weight of the vehicle, the air pressure applied to the booster 17 changes in response to a change in weight.

Therefore, this modification can also achieve the same effects as the first embodiment.

Although the preferred embodiments of the present invention have been illustrated and described, the present invention is not limited thereto, and can be modified in many ways.

For example, the valve member 88 of the variable pressure control valve 8 may respond only to the pressure in the outlet pressure chamber instead of responding to the pressure in the inlet pressure chamber and the outlet pressure chamber as in the above embodiment. In this case,
The valve member has a biasing force due to the outlet pressure acting on its pressure-receiving area, a biasing force due to a variable force of a spring as shown in FIG. 3, or a constant force of a spring and added thereto as shown in FIG. This structure controls the outlet pressure by balancing the biasing force generated by the variable air pressure.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an outline of a hydraulic servo brake device according to a first embodiment of the present invention, Fig. 2 is a detailed cross-sectional view showing the variable throttle valve, booster, and drive device shown in Fig. 1; The figure is a detailed sectional view of the variable pressure control valve in Figure 1, Figure 4 is a characteristic diagram of braking force with respect to pedal depression force, Figure 5 is a characteristic diagram of distribution of front and rear wheel brake force, and Figure 6 is a diagram of the characteristics of brake force in the first embodiment. FIG. 7 is a detailed cross-sectional view of a variable pressure control valve showing a modified example.
A block diagram showing an outline of an air servo brake device showing an embodiment, FIG. 8 is a detailed cross-sectional view showing the variable pressure regulating valve and drive device shown in FIG. 7, and FIG. 9 is a detailed cross-sectional view of the booster shown in FIG. 7. 10 are detailed sectional views of a variable pressure regulating valve showing a modification of the second embodiment. 1... Reservoir, 2... Hydraulic source, 3... Variable throttle valve, 4, 17... Boost device, 5... Pedal, 6
...Master cylinder, 7...Front wheel brake, 8
... Variable pressure control valve, 9 ... Rear wheel brake, 10
... Vehicle weight sensor, 11 ... Controller, 1
2, 13... Drive device, 14... Air pressure source, 15
...Accumulator, 16...Variable pressure regulating valve.

Claims (1)

[Scope of utility model registration request] a fluid pressure source; a booster that is actuated by fluid from the fluid pressure source in response to a brake pedal depression force and transmits an amplified output to a master cylinder; and a brake fluid pressure generated by the master cylinder. a front wheel brake and a rear wheel brake operated by a controller, and a regulating valve provided between the fluid pressure source and the booster to adjust the pressure or flow rate of the fluid supplied to the booster; The master cylinder is provided between the master cylinder and the rear brake, and is configured to control brake fluid pressure supplied to the rear brake in response to at least the pressure within the rear brake when the pressure exceeds a predetermined pressure value. a pressure control valve to reduce the pressure; and a first drive device that is operated based on a command from the controller according to the vehicle weight and controls the regulating valve so as to change the pressure or flow rate regulated by the regulating valve. and a second drive device that is operated based on a command from the controller according to the vehicle weight and controls the pressure control valve so as to change the pressure value set by the pressure control valve. A brake device characterized by: