JPH0230379Y2 - - 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 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 valve device having a plurality of circuits having different characteristics for adjusting the pressure of the supplied fluid; and a valve device provided between the master cylinder and the rear wheel brake, the valve device being configured to respond to at least the pressure within the rear wheel brake. a fixed pressure control valve device having a plurality of pressure control valves with different characteristics that reduce the brake fluid pressure supplied to the rear wheel brake when the pressure exceeds a predetermined pressure value; a first means for selectively operating one of the plurality of pressure control valves; and a second means for selectively operating one of the plurality of pressure control valves according to the vehicle weight.
The object of the present invention is to provide a brake device characterized by comprising the following means.

According to the above configuration, the transition point at which the output of the booster and the rate of increase in the rear wheel braking force start to decrease is changed in accordance with several vehicle weight ranks, and therefore the vehicle weight increases. Even when the brake pedal pressure changes, it is possible to obtain a constant deceleration with a constant pedal force, and even when the weight is light, it is possible to prevent the rear wheel from locking up even with a small pedal force, maintaining braking stability and high braking efficiency at all times. can.

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, in which oil is pumped from a reservoir 1 through a hydraulic source 2 such as an oil pump. After the pressure is adjusted by the fixed pressure control valve device 3 according to the vehicle weight, the pressure is supplied to the hydraulic booster 4 . 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 directly supplied to the front wheel brakes 7, and after the pressure is controlled according to the vehicle weight by a second fixed pressure control valve device 8, it is supplied to the rear wheel brakes 9. Supplied. A weight signal detected by vehicle weight sensor 10 is input to controller 11 .
In this embodiment, the first fixed pressure control valve device 3 is
a pressure control circuit with different characteristics;
In this embodiment, the fixed pressure control valve device 8 includes three pressure control valves with different characteristics, and the controller 11 controls one of the pressure control circuits adapted to the vehicle weight based on the weight signal. Activate any one pressure control valve.

Next, each component will be explained in detail.

In FIG. 2, a first fixed pressure control valve device 3
is for controlling the oil pressure from the oil pressure source 2 according to the weight of the vehicle, and an inlet 20 connected to the oil pressure source 2
The pressure control valve 23 is different from the first pressure control circuit comprising a pressure control valve 23 provided in the housing 22 for adjusting the hydraulic pressure from the booster 4 and supplying it to the outlet 21 connected to the booster 4. from a second pressure control circuit comprising a pressure control valve 24 for supplying a regulated hydraulic pressure to the outlet 21 and a communication passage 25 formed in the housing 22 for supplying the hydraulic pressure from the inlet 20 directly to the outlet 21; and two, for example, electromagnetic type switching valves 26 and 27 that selectively switch the supply of hydraulic pressure from the inlet 20 to any one pressure control circuit.

The switching valve 26 switches between a position A where the hydraulic pressure at the inlet 20 is supplied to the communication passage 25 and a position B where the same hydraulic pressure is supplied to the switching valve 27.
Position C supplies the supplied hydraulic pressure to the pressure control valve 24, and position D supplies the same hydraulic pressure to the pressure control valve 23.
Switch between positions. The switching operation of each switching valve is controlled by a controller 11.

Since the basic structure and operation of each pressure control valve are substantially the same, only the pressure control valve 23 will be described, and corresponding components of the other pressure control valves 24 will be denoted by the same reference numerals with "'". The explanation will be omitted.

The pressure control valve 23 is slidably disposed within a stepped hole 28 provided in the housing 22 to define an inlet pressure chamber 29 and an outlet pressure chamber 30, and is attached to the stepped portion of the hole 28. A piston-shaped valve member 32 that cooperates with the return seal 31 to control communication between the pressure chambers 29 and 30, and the wall of the hole 28 and the valve member 32.
A spring 33 is interposed between the valve member and the valve member and urges the valve member rightward to the open position shown in FIG. The valve member 32 is biased to the right in the opening direction by the inlet pressure in the inlet pressure chamber 29 that acts on a small pressure receiving area, and in the closing direction due to the outlet pressure in the outlet pressure chamber 30 that acts on a large pressure receiving area. Since the spring 33 has only a very weak force that positions the valve member 32 in the open position, the outlet pressure is applied to both sides of the valve member 32. The pressure is maintained at a value lower than the inlet pressure in accordance with the ratio between the pressure-receiving areas. Furthermore, the pressure control valve 2
Since the shaft diameter of the valve member 32 of No. 3 is larger than the shaft diameter of the valve member 32' of the pressure control valve 24, the pressure control valve 23
In this case, compared to the pressure control valve 24, the pressure receiving area ratio is large, and therefore the outlet pressure is small.

In FIG. 3, the booster 4 includes a cylinder 40
an inlet chamber 42 which is slidably fitted within and communicates with the outlet 21 of the fixed pressure control valve arrangement 3 via an inlet 41, a return chamber 44 which communicates with the reservoir 1 via a return opening 43 and a pressure chamber 45; a spool-shaped piston 46 that limits the spool-like piston 46; a spool valve 48 that is slidably fitted into a cylindrical hole 47 of the piston to control communication between the chambers 42, 44, and 45; and a spool valve 48 that controls communication between the chambers 42, 44, and 45; The pedal 5 is slidably fitted into the pedal 5.
A valve member 5 connected to a rod 50 interlocking with
1, is interposed between the cylinder 40 and the piston 46, and urges the piston to the right to act as a stopper 52.
A spring 53 is interposed between the bottom wall of the hole 47 and the spool valve 48, and biases the spool valve to the right to push the stopper 54 toward the cylinder 4.
0, and a spring 57 that is interposed between the bottom wall of the hole 49 and the valve member 51 and urges the valve member to the right to abut the stopper 56 on the spool valve 48. It has A rod 58 projects from the piston 46 and is connected to a bushing rod 59 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 61 provided in the entrance chamber 4.
2 communicates with the return chamber 44 through an opening 61, a hole 47, and an opening 62 provided in the piston 46.
Further, the opening 63 provided in the spool valve 48 and the T-shaped opening 64 provided in the valve member 51 are aligned, and the pressure chamber 45 is also
9 and through an opening 65 provided in the spool valve 48 to the return chamber 44 .

In FIG. 4, a second fixed pressure control valve device 8
are three pressure control valves 72, 7 supplying regulated oil pressure to an outlet 71 connected to the rear brake 9.
2' and 72'', and two, for example, electromagnetic type switching valves 73 and 74 that selectively switch the supply of hydraulic pressure from the inlet 70 connected to the master cylinder 6 to any one pressure control valve. .

The switching valve 73 changes the hydraulic pressure at the inlet 70 to the pressure control valve 7.
2, and B position, which supplies the same hydraulic pressure to the switching valve 74.
4 switches between a C position where the supplied hydraulic pressure is supplied to the pressure control valve 72' and a D position where the same hydraulic pressure is supplied to the pressure control valve 72''.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 72 will be described, and corresponding components of the other two pressure control valves 72' and 72'' will be designated by the same reference numerals. “′” in each
and "'', and the explanation thereof will be omitted.

The pressure control valve 72 is slidably disposed within a stepped hole 76 provided in the housing 75 to define an inlet pressure chamber 77 and an outlet pressure chamber 78, and is attached to a stepped portion 79 of the hole 76. A piston-shaped valve member 81 is interposed between the wall of the hole 76 and the land 82 of the valve member 81, and controls the communication between the pressure chambers 77 and 78 in cooperation with the annular seal 80. A spring 83 biases the member to the right toward the open position shown in FIG. In this open position, the small diameter right end 84 of the valve member 81 is spaced apart from the seal 80 and the land 82 is connected to a plurality of circumferentially spaced protrusions 8 on the seal 80.
5, and the annular lip 86 of the seal 80 is in pressure contact with the inner surface of the hole 76, so that the inlet pressure chamber 77 is formed between the plurality of grooves 87 provided on the outer periphery of the land 82, the seal 80, and the valve member. It communicates with the outlet pressure chamber 78 through a gap between the outlet pressure chamber 81 and the outlet pressure chamber 81 . The seal 80 is provided with a groove 88 on its bottom and outer circumference for communicating oil from the outlet pressure chamber 78 to the inlet pressure chamber 77 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 pressure is regulated by the fixed pressure control valve device 3 returns to the reservoir 1 through the inlet chamber 42, return chamber 44 and return opening 43, as shown by the arrow in FIG. The pressure chamber 45 communicates with the return chamber 44 and is at low pressure, so the booster 4 does not provide output to the master cylinder 6.

When applying force to the pedal 5 during braking, the rod 50
The valve member 51 is moved relative to the spool valve 48 while compressing the spring 57 and opens the opening 6.
3 is closed by the valve member 51, and the pressure chamber 45
Communication between this and the return chamber 44 is cut off. At the same time, the pedal depression force transmitted via the spring 57 is
While compressing the spring 55, the spool valve 48
is moved relative to the piston 46, and the land 60 is positioned approximately at the center of the opening 61, so that the inlet chamber 42 and the pressure chamber 45 are communicated through the opening. Therefore,
Part of the pressure oil that has flowed into the inlet chamber 42 from the inlet 41 flows into the pressure chamber 45, and the pressure within the same chamber 45 begins to rise, and the piston 46 moves to the left against the force of the spring 53. The power for actuating the master cylinder 6 is transmitted via rods 58 and 59.

When further pedal force is applied, the land 60 is positioned to the left of the opening 61, and communication between the entrance chamber 42 and the return chamber 44 is cut off. Therefore, the entire amount of the pressure oil that has flowed into the inlet chamber 42 flows into the pressure chamber 45, and the pressure within the chamber 45 further increases, so that the maximum pressure 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 70 of the fixed pressure control valve device 8 . Since the valve member 81 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 81 has a biasing force to the left due to the outlet pressure in the outlet pressure chamber 78 that acts on a large pressure-receiving area at the right end portion 84, and an inlet pressure chamber that acts on a small pressure-receiving area at the left peripheral edge of the land 82. A biasing force to the right is exerted by the inlet pressure in 77 and the force of spring 83. 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 81 is moved to the left, and the right end portion 84 approaches the seal 80, thereby restricting communication between the inlet pressure chamber 77 and the outlet pressure chamber 78. 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 81. 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 53, 55, and 57 push the piston 46, spool valve 48, and valve member 51 back to the positions shown in FIG. 3, so that the inlet chamber 42 and the pressure chamber 45
is again communicated with the return chamber 44, the oil pressure in the chambers 42 and 45 is discharged to the reservoir 1 and lowered, and the output to the master cylinder 6 is also released.

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 77 decreases, the biasing force to the left increases, and the right end 84 of the valve member 81 engages with the seal 80, thereby preventing communication between the pressure chambers 77 and 78. Outlet pressure, which is blocked but higher than the inlet pressure, passes through groove 88 to lip 86.
Since the lip is separated from the surface of the hole 76, the hydraulic pressure in the rear wheel brake 9 is transferred to the outlet pressure chamber 7.
8, is discharged into the master cylinder 6 through the gap between the lip 86 of the seal and the hole 76 and the inlet pressure chamber 77. 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 81 is moved again to the open position shown in FIG. and valve member 81
It is discharged to the master cylinder 6 through the gap between the two.

The above operation is performed when the vehicle weight is in a certain constant state, but if the weight changes, the highest hydraulic pressure that can be generated in the booster 4 is adjusted to the first fixed pressure. By controlling the maximum output of the booster 4 and the maximum brake oil pressure of the master cylinder 6 by adjusting the control valve device 3, a desired braking deceleration can be obtained regardless of changes in weight. In the second 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 83 are is proportional to, and the outlet pressure increases or decreases as the spring force increases or decreases. Therefore, if the spring force is changed according to the vehicle weight, the transition point of the rear wheel braking force will also change, resulting in the desired front and rear brake force. It is possible to obtain wheel brake force distribution.

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
1 indicates three vehicle weight ranks in this embodiment that are set in advance from the weight signal, for example, the rank when the vehicle is empty.
W ₁ , rank W ₂ at 1/2 load, and rank W ₃ at maximum load are determined, and the pressure control circuit and fixed pressure control of the fixed pressure control valve device 3 are adapted to this weight rank. pressure control valve 72 of valve device 8;
72' or 72''.
27 and the switching valves 73 and 74. Additionally, pressure control valves 72, 72' and 7
The setting forces F ₁ , F ₂ , and F ₃ of the 2″ springs 83 , 83 ′, and 83 ″ are different to obtain front and rear wheel braking force distributions adapted to the weight ranks W ₁ , W _{2 ,} and W ₃ , respectively. It is set so that F ₁ < F ₂ < F ₃ .

To explain this control mode, in the first fixed pressure control valve device 3, when the controller 11 detects the weight rank _W1 , it switches the switching valve 26 to the B position, and switches the switching valve 27 to the D position. Activate. As a result, the hydraulic pressure at the inlet 20 is supplied to the pressure control valve 23 having a large pressure receiving area ratio, and the valve member 32 cooperates with the seal 31 to lower the outlet pressure below the inlet pressure in accordance with the ratio. Set to a low value. When the controller 11 detects the weight rank _W2 , it maintains the switching valve 26 at the B position and switches the switching valve 27 to the C position. As a result, the oil pressure at the inlet 20 is reduced to the pressure control valve 23.
The valve member 32' cooperates with the seal 31' to lower the outlet pressure below the inlet pressure in accordance with said ratio, thereby achieving a predetermined pressure area ratio. Set to intermediate value. Furthermore,
When the controller 11 detects the weight rank W ₃ , it switches the switching valve 26 to the A position and closes the inlet 2.
Since the hydraulic pressure of 0 is supplied to the communication passage 25, the outlet 2
1 will be directly supplied with this oil pressure. In this way, the hydraulic pressure from the hydraulic source 2 adjusted according to the vehicle weight rank is supplied to the booster 4,
The maximum oil pressure in the pressure chamber 45 and the maximum output of the booster are set to predetermined values.

Incidentally, the reaction force when the pedal 5 is depressed is determined by the reaction force of the spring 55, and this spring force is determined by the amount of displacement of the spool valve 48 with respect to the piston 46. In other words, if the amount of displacement is the same,
The pressing force on the pedal 5 is the same.

As a result, the pressure control circuit of the fixed pressure control valve device 3 is selectively activated in accordance with the weight rank of the vehicle, so that even with the same pedal depression force, the output of the booster 4 is changed, and Since the booster is mechanically connected to 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 way is shown in FIG.

Next, in the second fixed pressure control valve device 8, when the controller 11 detects the weight rank W1, it switches the switching valve ₇₃ to the A position, and the hydraulic pressure supplied to the inlet 70 during braking is transferred to the pressure control valve. 72 and the outlet 71 to the rear brake 9, which, by operating in the manner described above, has a small spring setting force F ₁ .
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 73 to the B position and switches the switching valve 74 to the C position. As a result, the hydraulic pressure at the inlet 70 is supplied to a pressure control valve 72' 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, when the controller 11 detects the weight rank _W3 , it maintains the switching valve 73 at the B position while switching the switching valve 74 to the D position. As a result, the hydraulic pressure at the inlet 70 is increased by the setting force F ₂
is supplied to a pressure control valve 72'' having an even greater spring set force F ₃ , which also operates in a manner similar to that described above, to set the outlet pressure at the transition point to a predetermined large value.

The operation of this fixed pressure control valve device 8 is performed in synchronization with the operation of the first fixed pressure control valve device 3. As a result, even with the same pedal depression force, the brake hydraulic pressure in the master cylinder 6 is changed in accordance with the weight rank of the vehicle 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. 6. 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. 6, 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
After the pressure is adjusted according to the vehicle weight by 4,
It is designed to be supplied to a pneumatic booster 15. The booster 15 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 11 are the same as those of the first embodiment, so detailed explanation thereof will be omitted.

In FIG. 8, the fixed pressure regulating valve device 14 is
Adjusting the air pressure from the inlet 100 connected to the air pressure source 12, the outlet 1 connected to the booster 15
Pressure regulating valves 102, 102', 1 supplied to 01
02'' and three on-off valves, for example, electromagnetic type, that are selectively opened and closed so as to supply air pressure from the inlet 100 to the outlet 101 through any one of the pressure regulating circuits. 103,
104 and 105.

The on-off valves 103 and 104 are located between the pressure regulating valves 102 and 102' and the outlet 101, respectively.
and the second pressure regulating circuit, while the on-off valve 105 is disposed in the third pressure regulating circuit between the inlet 100 and the pressure regulating valve 102''.
The opening and closing operations of each pressure regulating valve are controlled by a controller 11.

Since the basic structure and operation of each pressure regulating valve are substantially the same, only the pressure regulating valve 102 will be described, and the other two pressure regulating valves 102' and 1
Corresponding components of 02'' are given the same reference numerals with ``''' and ``'', respectively, and their explanations will be omitted.

The pressure regulating valve 102 includes a valve member 109 that is slidably disposed within the housing 106 and controls communication between the inlet pressure chamber 107 and the outlet pressure chamber 108, and a valve member 109 that is fixed within the housing 106 and controls the communication between the inlet pressure chamber 107 and the outlet pressure chamber 108.
The pressure chamber 111 and the atmosphere release chamber 112 which communicate through the opening 110 are limited, and the valve member 10
a diaphragm 113 that controls communication between the chambers 111 and 112 in cooperation with the tip of the valve member 10;
9 in the closing direction, and a spring 115 interposed between the housing 106 and the diaphragm 113 to urge the diaphragm in the opening direction of the valve member 109. Spring 114 has only a very weak force that causes valve member 109 to follow diaphragm 113 .

In FIG. 9, a booster 15 is slidably fitted in a housing 120 to limit a pressure chamber 121 and an atmosphere open chamber 122, and also
1 and 122, a piston 124 having a cylindrical hole 123 communicating with each other, a regulator 126 slidably fitted in the hole 123 and connected to a rod 125 that interlocks with the pedal 5, and a housing 120.
A spring 127 is interposed between the bottom wall of the hole 123 and the regulator 126 and urges the piston to the right to contact the housing 120, and a spring 127 is interposed between the bottom wall of the hole 123 and the regulator 126 to force the regulator It has springs 130 and 131 that bias the seal 128 to the right and seat the seal 128 on the seat 129, and the spring 131 has a shorter natural length than the spring 130. The regulator 126 has an inlet 1
32 to control the communication between the inlet chamber 133, the pressure chamber 121, and the atmosphere release chamber 122, which are connected to the outlet 101 of the fixed pressure regulating valve device through the regulator 126. a pilot chamber 135 that has been opened, a nozzle 136 communicating the pilot chamber with the hole 123
a passageway 138 which can communicate with the inlet chamber 133 and which communicates with the pilot chamber 135 via the pilot passageway 137;
A passage 139 communicating with the pressure chamber 121 includes an exhaust chamber 141 which is bounded by a diaphragm 134 and can communicate with the passage 139 and which communicates with the atmosphere open chamber 132 via an exhaust passage 140, and a passage 138. A valve member 142 that controls communication between the passage 139 and the exhaust chamber 141, and a spring 143 that biases the valve member toward the diaphragm 134 are provided. A pad 144 is attached to the piston 124 facing the nozzle 136, and a rod 145 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 pressure regulating valve 10
Compressed air from the air pressure source 12 flowing into the inlet pressure chamber 107 of No. 2 is guided to the outlet pressure chamber 108 through the valve member 109, and is supplied to the inlet 132 of the booster 15 via the outlet 101. However, when the pressure in the outlet pressure chamber 108 rises above a certain value, since both pressure chambers 108 and 111 are communicating through the opening 110, as the pressure in the pressure chamber 111 increases, the diaphragm 113 is moved against the force of the spring 115, the valve member 109 moves to the right, and communication between the inlet pressure chamber 107 and the outlet pressure chamber 108 is cut off. When the pressure within the outlet pressure chamber 108 drops above the above value, the spring 115 pushes the diaphragm 113 and the valve member 109 back to the left, allowing the outlet pressure chamber 108 to communicate with the inlet pressure chamber 107 again. In this way, the spring 11
Force 5 and pressure chamber 1 acting on diaphragm 113
The valve member 109 is maintained in a state where the pressures in the pressure chambers 08 and 111 are balanced, and the air pressure supplied from the outlet pressure chamber 108 to the booster 15 is adjusted.

When no pedal force is applied to the pedal 5, the booster 15 is in the brake release position shown in FIG. The air is only supplied to the closed inlet chamber 133, while the pilot chamber 135 and exhaust chamber 141 are supplied to the atmosphere open chamber 12.
2 to the atmosphere.

When applying force to pedal 5 during braking, rod 12
5, the regulator 126 is moved relative to the piston 124 while first compressing the spring 130, and the seal 128 is separated from the seat 129.
Compressed air within the inlet chamber 133 flows into the passageway 138. A part of this air flows into the pilot chamber 135 through the pilot passage 137, and further flows into the nozzle 13.
6 and flows out from the atmosphere open chamber 122 to the atmosphere. When the pedal force is further applied, the spring 131 with a short natural length is also compressed, and the relative movement between the regulator 126 and the piston 124 increases, causing the nozzle 13
6 approaches pad 144, the nozzle back pressure, ie, the pressure within pilot chamber 135, increases. As a result, the diaphragm 134 and the valve member 142 are pushed to the right, the passage 138 and the passage 139 are communicated with each other, compressed air flows into the pressure chamber 121, the pressure in the same chamber begins to rise, and the piston 124 moves toward the spring 127. The power to actuate the master cylinder 6 is transmitted through the rod 145. At the same time, the pressure in pressure chamber 121 is acting on diaphragm 134, and when the pressure increases until it balances the force due to the pressure in pilot chamber 135, spring 143 moves valve member 142 to the closed position.

In this manner, the nozzle back pressure is determined depending on the displacement of the regulator 126 with respect to the piston 124, and therefore the pressure within the pressure chamber 121 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 126 is activated by the springs 130 and 131.
is pushed back, and the gap between the nozzle 136 and the pad 144 increases and the pilot chamber 13
The pressure inside 5 decreases. As a result, the diaphragm 134 is moved to the left and separated from the valve member 142, and the air pressure in the pressure chamber 121 is transferred to the atmosphere open chamber 140 through the passage 139, the exhaust chamber 141, and the exhaust passage 140.
22 to the atmosphere and lowers the spring 1
27 pushes back the piston 124, 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 121 of the booster 15 is adjusted by the fixed pressure regulating valve device 14 in response to the change, and the booster increases. By controlling the maximum output and the maximum brake oil pressure of the master cylinder 6, a desired braking deceleration can be obtained regardless of changes in weight.

Therefore, similarly to the first embodiment described above, the controller 11 controls the vehicle weight sensor 10.
From _the weight signal _{detected by} The above fixed pressure regulating valve device 1
The on-off valve 1 is operated so as to operate the pressure regulating circuit of 4.
It controls the opening and closing of 03, 104 and 105. Additionally, pressure regulating valves 102, 102' and 10
The setting forces F ₁ , F ₂ and F ₃ of the 2" springs 115, 115' and 115" correspond to the above weight ranks W ₁ ,
They are different so that maximum air pressures corresponding to W ₂ and W ₃ are generated in the pressure chamber 121 of the booster 15, and are set so that F ₁ , <F ₂ , <F ₃ .

To explain this control mode, when the controller 11 detects the weight rank _W1 , it closes the on-off valves 104 and 105, and closes the on-off valve 103. As a result, the compressed air at the inlet 100 passes through the pressure regulating valve 102 to the booster 1.
5, which has a small spring set force F ₁ , so that by operating in the manner described above it sets the pressure in the outlet pressure chamber 108 to a predetermined low value. . Controller 11
When the weight rank W ₂ is detected, the on-off valve 103
and 105 are operated to close, and the on-off valve 104
Activate the opening. As a result, the compressed air at the inlet 100 is supplied to the booster 15 via a pressure regulating valve 102' having a spring setting force F ₂ greater than the setting force F ₁ , which valve is similar to that described above. operates in a manner to set the pressure within the outlet pressure chamber 108' to a predetermined intermediate value. Furthermore, when the controller 11 detects the weight rank _W3 , it closes the on-off valves 103 and 104, and opens the on-off valve 105. As a result, compressed air at the inlet 100 is applied to the pressure regulating valve 1 having a spring setting force F ₃ which is even larger than the setting force F ₂ .
02'', which operates in a manner similar to that described above to set the pressure in the outlet pressure chamber 108'' to a predetermined high value. In this way, the air pressure from the air pressure source 12 adjusted according to the vehicle weight rank is supplied to the booster 15, and the pressure chamber 12
The maximum air pressure within 1 and the output of the booster are set to predetermined values.

On the other hand, the reaction force when the pedal 5 is depressed is determined by the reaction force of the springs 130 and 131, but this spring force is determined by the amount of displacement of the regulator 126 with respect to the piston 124, and if the amount of displacement is the same, the pedal depression force will be be the same.

As a result, the pressure regulating circuit of the fixed pressure regulating valve device 14 is selectively activated in accordance with the weight rank of the vehicle, so that even with the same pedal depression force,
By changing the output of the booster 15, the brake oil pressure from the master cylinder 6 can be changed accordingly, and the characteristics of the brake force relative to the pedal depression force as shown in FIG. 5 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. 6 can be obtained. This is possible.

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

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 81, 81', 81'' of each pressure control valve is constant, and the setting forces F ₁ , F ₂ , F of the springs 83, 83', 83'' 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 83 and 8 of each pressure control valve
3', 83'' are kept constant, and the valve member 8
By changing the ratio between the pressure receiving areas of 1, 81', and 81'', 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.

Further, in the above embodiment, the vehicle weight is divided into three weight ranks, and three pressure control circuits or pressure adjustment circuits and three pressure control valves 72, 72',
72″ is provided, but this number may be arbitrary.
The larger the number, the more finely controlled brake hydraulic pressure and brake force distribution control can be obtained depending on the vehicle weight.

Furthermore, the valve members 81, 81', 8 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 biasing force due to the outlet pressure acting on the pressure receiving area of the springs 83, 83',
This structure controls the outlet pressure by balancing the urging force with a force of 83''.

[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 sectional view of the first fixed pressure control valve device shown in FIG. 1, and FIG. Figure 1 is a detailed cross-sectional view of the booster shown in Figure 1, Figure 4 is a detailed cross-sectional view of the second fixed pressure control valve device shown in Figure 1, Figure 5 is a characteristic diagram of brake force against pedal depression force, and Figure 6 is a front and rear view. A distribution characteristic diagram of wheel brake force, FIG. 7 is a block diagram showing an outline of an air servo brake device showing a second embodiment of the present invention, FIG. 8 is a detailed sectional view of the fixed pressure regulating valve device of FIG. 7, FIG. 9 is a detailed sectional view of the booster of FIG. 7. DESCRIPTION OF SYMBOLS 1... Reservoir, 2... Hydraulic source, 3, 8... Fixed pressure control valve device, 4, 15... Booster, 5... Pedal,
6...Master cylinder, 7...Front wheel brake, 9...
Rear wheel brake, 10...Vehicle weight sensor, 11...Controller, 12...Pneumatic pressure source, 13...Accumulator, 14...Fixed pressure regulating valve device, 23, 24,
72, 72', 72''...Pressure control valve, 26, 27,
73, 74...Switching valve, 102, 102', 10
2″...Pressure regulating valve, 103, 104, 105...Opening/closing 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 plurality of circuits having different characteristics are provided between front wheel brakes and rear wheel brakes operated by the pump, the fluid pressure source and the booster, and adjust the pressure of the fluid supplied to the booster. a valve device provided between the master cylinder and the rear wheel brake, the valve device being configured to respond to at least the pressure within the rear wheel brake and supplying the valve to the rear wheel brake when the pressure exceeds a predetermined pressure value. a fixed pressure control valve device having a plurality of pressure control valves having different characteristics for reducing brake fluid pressure applied to the vehicle; a first means for selectively operating one of the plurality of circuits according to the weight of the vehicle; A brake device comprising: second means for selectively operating any one of the plurality of pressure control valves according to weight.