JPH0137963Y2 - - 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 be subject to 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 braking 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 multi-layer brake system that is actuated by the fluid from the fluid pressure source in response 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,
When the same pressure exceeds a predetermined pressure value, the brake fluid pressure supplied to the rear wheel brake is reduced.The pressure control valve has a plurality of different characteristics and is operated based on a command according to the vehicle weight from the controller. a drive device that controls the regulating valve so as to change the pressure or flow rate regulated by the regulating valve; and one of the plurality of pressure control valves, which is operated based on a command from the controller according to the vehicle weight. The braking device is characterized in that it is equipped with switching means for communicating a pressure control valve with characteristics adapted to the weight of a vehicle with the master cylinder.

According to the above configuration, the output of the booster is changed in response to changes in vehicle weight, and the transition point at which the rate of increase in rear wheel braking force begins to decrease is set in accordance with several vehicle weight ranks. 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 weight is light, the rear wheels can be prevented from locking with a small pedal force. Therefore, braking stability and high braking efficiency can 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 stop 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 according to the weight of the vehicle by a fixed pressure control valve device 8, 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 operates the drive device 12 that controls the flow rate of the variable swell valve 3 based on this signal. The fixed pressure control valve device 8 includes in this example three pressure control valves with different characteristics, and the controller 11 also includes:
Based on the weight signal, any one pressure control valve adapted to the vehicle weight is operated.

Next, each component will be explained in detail.

In FIG. 2, the variable valve 3 is connected to the cylinder 2.
an inlet 21 slidably mounted in 0 and connected to a hydraulic source 2 and a return opening 2 connected to a reservoir 1;
2, and 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, lands 24 and 25
The flow rate of pressure oil flowing from the intermediate chamber 28 to the booster 4 via the outlet 29 is controlled. A rod 30 projects from the land 24 of the spool valve 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 that limits 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; Cylindrical hole 4
A valve member 50 is slidably fitted in the cylinder 40 and connected to a rod 49 that interlocks with the pedal 5, and a valve member 50 is interposed between the cylinder 40 and the piston 45 and urges the piston to the right. A spring 52 is inserted between the bottom wall of the hole 46 and the spool valve 47 and biases the spool valve to the right to bring the stopper 53 into contact with the cylinder 40. 54, the bottom wall of the hole 48 and the valve member 5
0, and urges the valve member rightward to abut against a stopper 55 on the spool valve 47. 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.
It is located to the right of the opening 60 provided in the entrance chamber 4.
1 communicates with the return chamber 43 via an opening 60, a hole 46 and an opening 61 provided in the piston 45.
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 44 is also
8 and an opening 64 provided in the spool valve 47 to communicate with the return chamber 43 .

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 crest 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 displacement position 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 thereof. Ru.

In FIG. 3, a fixed pressure control valve arrangement 8 is connected to the master cylinder 6 with three pressure control valves 82, 82' and 82'' supplying regulated hydraulic pressure to an outlet 81 connected to the rear brake 9. It is comprised of two, for example, electromagnetic type switching valves 83 and 84 that selectively switch the supply of hydraulic pressure from the inlet 80 to any one pressure control valve.

The switching valve 83 switches the hydraulic pressure at the inlet 80 to the pressure control valve 8.
The switching valve 84 switches between the A position where the oil pressure is supplied to the switching valve 84 and the B position where the same hydraulic pressure is supplied to the switching valve 84.
4 is switched between a C position where the supplied hydraulic pressure is supplied to the pressure control valve 82' and a D position where the same hydraulic pressure is supplied to the pressure control valve 82''.The switching operation of each switching valve is controlled by the controller 11. controlled.

Since the basic structure and operation of each pressure control valve is substantially the same, only pressure control valve 82 will be described, and corresponding components of the other two pressure control valves 82' and 82'' will be designated by the same reference numerals. “′” in each
and "'', and the explanation thereof will be omitted.

The pressure control valve 82 is slidably disposed within a stepped hole 86 provided in the housing 85 to define an inlet pressure chamber 87 and an outlet pressure chamber 88, and is attached to a stepped portion 89 of the hole 86. A piston-shaped valve member 91 is interposed between the wall of the hole 86 and the land 92 of the valve member 91, and controls the communication between the pressure chambers 87 and 88 in cooperation with the annular seal 90. A spring 93 biases the member to the right toward the open position shown in FIG. In this open position, the small diameter right end 94 of the valve member 91 is spaced from the seal 90 and the land 92 is connected to a plurality of circumferentially spaced projections 9 on the seal 90.
5, and the annular lip 96 of the seal 90 is in pressure contact with the inner surface of the hole 86, so that the inlet pressure chamber 87 is formed between a plurality of grooves 97 provided on the outer periphery of the land 92, the seal 90, and the valve member. It communicates with the outlet pressure chamber 88 through a gap between the outlet pressure chamber 91 and the outlet pressure chamber 88 . The seal 90 is provided with a groove 98 on its bottom and outer circumference that allows oil to communicate from the outlet pressure chamber 88 to the inlet pressure chamber 87 when the brake is released.

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 stop 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 80 of the fixed pressure control valve device 8 . Since the valve member 91 is normally in the open position shown in FIG. and is supplied to the rear wheel brake 9, resulting in equal front wheel braking force and rear wheel braking force.

The valve member 91 has a biasing force to the left due to the outlet pressure in the outlet pressure chamber 88 that acts on a large pressure-receiving area at the right end portion 94, and an inlet pressure chamber that acts on a small pressure-receiving area at the left peripheral edge of the land 92. A biasing force to the right is exerted by the inlet pressure in 87 and the force of spring 93. 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 91 is moved to the left, and the right end portion 94 approaches the seal 90, thereby restricting communication between the inlet pressure chamber 87 and the outlet pressure chamber 88. After the transition point, the outlet pressure is maintained at a value smaller than the inlet pressure, corresponding to the ratio between the two pressure-receiving areas of the valve member 91. 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 fixed pressure control valve device 8 also decreases. As the inlet pressure in the inlet pressure chamber 87 decreases, the biasing force to the left increases, and the right end 94 of the valve member 91 engages with the seal 90, thereby preventing communication between the pressure chambers 87 and 88. Outlet pressure, which is blocked but higher than the inlet pressure, passes through groove 98 to lip 96.
Since the lip is separated from the surface of the hole 86, the hydraulic pressure in the rear wheel brake 9 is transferred to the outlet pressure chamber 8.
8. It is discharged into the master cylinder 6 through the gap between the lip 96 of the seal and the hole 86 and the inlet pressure chamber 87. When the biasing force to the right becomes greater than the biasing force to the left due to a decrease in the outlet pressure, the valve member 91 is moved again to the open position shown in FIG. and valve member 91
It is discharged to the master cylinder 6 through the gap between the two.

The above operation is performed when the vehicle weight is constant. However, if the weight changes, the maximum oil pressure that can be generated in the booster 4 is adjusted by the variable pressure valve 3. By adjusting the maximum output of the booster 4 and the maximum brake oil pressure of the master cylinder 6, it is possible to obtain the desired braking deceleration regardless of the change in weight. Furthermore, in the fixed pressure control valve device 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 force of the spring 93 are proportional. As the spring force increases or decreases, the outlet pressure also increases or decreases, so if you change the spring force according to the vehicle weight, the transition point of the rear wheel braking force will also change, and the desired front and rear wheel braking force will be achieved. You can get your share.

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 oil pressure in the booster 4 suitable for the weight W is determined from preset characteristic data, the position of the spool valve 23 is determined, and the drive device 12 The motor 70 is driven, and the actual displacement position detected by the tachometer 75 or displacement meter 77 is compared with the predetermined displacement position to perform feedback control. or,
Based on the weight signal, the controller 11 determines three preset vehicle weight ranks in this embodiment, for example, rank W ₁ when the vehicle is empty, rank W ₂ when the vehicle is 1/2 loaded, and rank W ₃ when the vehicle is fully loaded. The pressure control valve 82, 82' is adapted to the weight rank.
or 82'', switching valves 83 and 8
4 switching control is performed. Furthermore, the springs 93, 93' of the pressure control valves 82, 82' and 82''
and 93'' set forces F ₁ , F ₂ and F ₃ are different so as to obtain front and rear wheel brake force distributions respectively adapted to the weight ranks W ₁ , W ₂ and W ₃ ,
It is set so that F ₁ < F ₂ < F ₃ .

To explain this control mode, the variable control valve 3 controls the vehicle weight W to a value such as when the vehicle is empty, for example.
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 set 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 as at the time of maximum loading, 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 reduced 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 ₂
For example, in the case of a predetermined intermediate value W ₂ such as when the vehicle is 1/2 loaded, the spool valve 23 is moved to a predetermined position by the controller 11 and the motor 70 according to this value, and the opening 22 is moved to a predetermined position. The opening degree of is set to a predetermined intermediate value, and the maximum oil pressure in the pressure chamber 44 and the maximum output of the booster 4 are set to a predetermined intermediate value.

By the way, 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 position of the spool valve 47 with respect to the piston 45. That is, if the displacement is the same,
The pressing force on the pedal 5 is the same.

As a result, by changing the position of the spool valve 23 in response to changes in vehicle weight, the output of the booster 4 changes even with the same pedal depression force, and the booster 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 fixed pressure control valve device 8, when the controller 11 detects the weight rank W ₁ , the switching valve 83
is switched to position A, and the hydraulic pressure supplied to the inlet 80 during braking is supplied to the rear wheel brake 9 via the pressure control valve 82 and the outlet 81, but this valve has a small spring setting force _F1. Because I am doing
By operating in the manner described above, the outlet pressure at the transition point is set to a predetermined low value. When the controller 11 detects the weight rank _W2 , it switches the switching valve 83 to the B position and switches the switching valve 84 to the C position. As a result, the hydraulic pressure at the inlet 80 is supplied to a pressure control valve 82' having a spring setting force _F2 greater than the setting force _F1 , which operates in a manner similar to that described above to provide an outlet at the transition point. Set the pressure to a predetermined intermediate value. Furthermore, the controller 11 has a weight rank.
When W ₃ is detected, the switching valve 83 is maintained at the B position, while the switching valve 84 is switched to the D position. As a result, the hydraulic pressure at the inlet 80 is supplied to the pressure control valve 82'', which has a spring setting force _F3 which is even greater than the setting force _F2 , and which operates in a manner similar to that described above, at the transition point. Set the outlet pressure to a predetermined large value.

The operation of the fixed pressure control valve device 8 is performed in synchronization with the operation of the variable pressure control valve 3. 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 the characteristics of the 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 different pressure values or more depending on the weight rank of the vehicle, and the front and rear wheel brake force is increased as shown by the solid line in Fig. 5. This gives us the distribution characteristics.

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 be maintained at all times.

In Fig. 5, the dashed line represents the front and rear brake force distribution characteristics by the fixed pressure control valve device 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 distribution characteristic. It represents the brake force distribution characteristics.

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 14, and after having its pressure adjusted according to the weight of the vehicle by a variable pressure regulating valve 15, it is supplied to a pneumatic booster 16. There is. The booster 16 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 12 are the same as those of the first embodiment, so detailed explanation thereof will be omitted. In FIG. 7, the variable pressure regulating valve 15 is slidably disposed within the housing 112 having an inlet 110 connected to the air pressure source 13 and an outlet 111 connected to the booster 16. , inlet pressure chamber 113 and outlet pressure chamber 11
A valve member 115 is fixed in the housing 112 and limits a pressure chamber 117 communicating with the outlet pressure chamber 114 through an opening 116 and an atmosphere release chamber 118, a diaphragm 119 that controls communication between the chambers 117 and 118, a spring 120 that biases the valve member 115 in the closing direction, an adjustment screw 121 screwed into the housing 112, and the diaphragm 119. A spring 12 is interposed between the valve member 115 and biases the diaphragm in the opening direction of the valve member 115.
2. 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, Movement towards the diaphragm 119 increases the setting force of the spring 122, and when rotated in the opposite direction it moves away from the diaphragm to decrease 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. 8, a booster 16 is slidably fitted into a housing 130 to limit a pressure chamber 131 and an atmosphere open chamber 132, and also
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 1
42 to control the communication between the inlet chamber 143, the pressure chamber 131, and the atmosphere release chamber 132, which 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;
47 to the pilot chamber 145, a passage 149 which may communicate with the same and communicate with the pressure chamber 131, and which may be delimited by the diaphragm 144 and 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 1
48 and 149 as well as passage 1.
Valve member 1 that controls communication between 49 and exhaust chamber 151
52 and a spring 153 that urges 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 13 flows into the inlet pressure chamber 113 of the variable pressure regulating valve 15.
The compressed air from When the pressure rises above this level, since both pressure chambers 114 and 117 communicate with each other through the opening 116, as the pressure within the pressure chamber 117 increases, the diaphragm 119 moves against the force of the spring 122, causing the valve to open. The member 115 moves to the right and 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 115 back to the left, allowing the outlet pressure chamber 114 to communicate with the inlet pressure chamber 113 again. In this way, the spring 12
2 force and pressure chamber 1 acting on diaphragm 119
The valve member 115 is maintained in a state in which the pressures in the pressure chambers 14 and 117 are balanced, and the air pressure supplied from the outlet pressure chamber 114 to the booster 16 is adjusted.

When no pedal force is applied to the pedal 5, the booster 16 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 depending on the 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 16 is adjusted by the variable pressure regulating valve 15 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. 7, for example, when the vehicle weight W changes from the value W ₂ when the vehicle is 1/2 loaded to the value W ₁ when the vehicle is empty, the controller 11 In response to this change, the motor 70 is rotationally driven to rotate the adjustment screw 121 in one direction and move it to a predetermined right end position, and the diaphragm 119
The setting force of spring 122, which biases leftward, is reduced to a predetermined minimum value. As a result, pressure chamber 1
The force due to the pressure inside 17 becomes larger than the force of spring 122, and diaphragm 119 is moved to the right, and communication between both pressure chambers 113 and 114 is cut off by valve member 115, and valve member 11
5 separates from the diaphragm 119, and the pressure within 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, the diaphragm 119
engages the valve member 115, which is held 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 16 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 16 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 rear wheel brake force control operation by the fixed pressure control valve device 8 described in detail in connection with the first embodiment, the front and rear wheel brake force distribution characteristics shown in FIG. 5 can be obtained. This is possible.

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

In the second embodiment, the setting force of the spring 122 of the variable pressure regulating valve 15 is controlled by the vehicle weight sensor 1.
0, it is continuously adjusted using electrical means consisting of a controller 11 and a drive device 12,
The leftward biasing force of the diaphragm 119 can be continuously changed using air pressure. That is, in a vehicle equipped with an air spring 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 leftward biasing force of the diaphragm.

The modification of the two embodiments shown in FIG. 9 shows an example using pneumatic means, and the same components as those in FIG. 7 will be described with the same reference numerals.

In the variable pressure regulating valve 15 of FIG. 9, the spring 122 is connected to the diaphragm 119 and the housing 119
and biases the diaphragm to the left with a predetermined setting force. Also, housing 1
A piston 123 is fitted in a sealed and slidable manner within the control pressure chamber 12.
4 and engages the diaphragm 119. This control pressure chamber 124 is directly connected via an inlet 125 to the air spring of the air spring suspension. Other structures are the same as those in FIG.

The operation of this variable pressure regulating valve 15 is substantially the same as the seventh one.
Although it is the same as that 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 16 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, in the above embodiment, the ratio between the pressure receiving areas of the valve members 91, 91', 91'' of each pressure control valve is constant, and the setting forces F ₁ , F 2 , F ₂ of the springs 93, 93', 93'' are set constant. ₃ , the transition point of the rear wheel brake force is changed while the rate of increase of the rear wheel brake force after the transition point is kept constant. However, the ratio between the above pressure receiving areas of each pressure control valve is Alternatively, the rate of increase in rear wheel braking force after the transition point may be varied, which may be more beneficial in some cases. In addition, the springs 93, 9 of each pressure control valve
3', 93'' are kept constant, and the valve member 9
By changing the ratio between the pressure receiving areas of 1, 91', and 91'', it is possible to simultaneously change the transition point of the rear wheel braking force and the rate of increase in the rear wheel braking force after the transition point.

Furthermore, in the above embodiment, the vehicle weight is divided into three weight ranks and three pressure control valves are provided.
This number may be arbitrary, and the larger the number, the more finely controlled brake force distribution can be obtained depending on the vehicle weight.

Furthermore, the valve members 91, 91', 9 of each pressure control valve
1'' 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 The urging force due to the outlet pressure acting on the pressure receiving area of the springs 39, 93',
This structure controls the outlet pressure by balancing the urging force due to the force of 93''.

[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. Fig. 3 is a detailed sectional view of the fixed pressure control valve device shown in Fig. 1, Fig. 4 is a characteristic diagram of braking force with respect to pedal depression force, Fig. 5 is a characteristic diagram of distribution of braking force between front and rear wheels, and Fig. 6 is a diagram of the distribution characteristic of the brake force of the front and rear wheels. A block diagram showing an outline of the air servo brake device showing the second embodiment, FIG. 7 is a detailed sectional view showing the variable pressure regulating valve and drive device shown in FIG. 6, and FIG. 8 is a detailed sectional view showing the booster shown in FIG. 6. Detailed sectional view, FIG. 9 is a detailed sectional view of a variable pressure regulating valve showing a modification of the second embodiment. 1...Reservoir, 2...Hydraulic power source, 3...Variable pressure valve, 4, 16...Boosting device, 5...Pedal, 6
...Master cylinder, 7...Front wheel brake, 8
... Fixed pressure control valve device, 9 ... Rear wheel brake,
10... Vehicle weight sensor, 11... Controller, 12... Drive device, 13... Air pressure source, 14
...Accumulator, 15...Variable pressure regulating valve,
82, 82', 82''...Pressure control valve, 83, 84
...Switching 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 plurality of pressure control valves having different characteristics to be lowered are operated based on a command according to the vehicle weight from a controller, and the regulating valve is controlled so as to change the pressure or flow rate regulated by the regulating valve. a driving device; and a switching means that is operated based on a command from a controller according to the vehicle weight and connects one of the plurality of pressure control valves with characteristics adapted to the vehicle weight to the master cylinder. A brake device comprising: