JP2871305B2 - Air brake system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to relates to an air brake system of a vehicle equipped with an auxiliary brake.

[0002]

2. Description of the Related Art A conventional vehicle converts kinetic energy into frictional energy at the time of braking and radiates it to the atmosphere. However, in order to save energy and reduce exhaust gas, a braking energy regeneration system that utilizes braking energy at the time of deceleration of a vehicle and reuses it when starting and accelerating is being developed for practical use.

FIG. 1 shows an example of a configuration of a pressure-accumulation type braking energy regenerating system as an auxiliary brake . A hydraulic pump / motor 3 is connected to an axle 1 via a gear box 2. the port 3a to the hydraulic oil tank 4, connected to the accumulator 6 through the other port 3b of the switch valve (check valve) 5, a brake pedal 7, a brake signal from the accelerator pedal 8, according to No. accelerator signal control Hydraulic pump / motor 3 by unit 9
And the switching valve 5 is controlled. Thus, the braking energy regeneration system 10 is configured.

When the brake pedal 7 is depressed during braking,
The control unit 9 controls the tilt angle of the hydraulic pump / motor 3. The hydraulic pump / motor 3 is driven by wheels to operate as a pump, pumps oil from a hydraulic oil tank 4 through a switching valve 5 to an oil chamber 6a of an accumulator 6, and presses a piston 6b leftward in FIG. The nitrogen gas (N ₂ ) sealed in the chamber 6c is compressed. Thereby, the kinetic energy of the vehicle at the time of deceleration is accumulated in the accumulator 6 via the hydraulic pressure. Then, the braking energy regeneration system 10 functions as an auxiliary brake.

At the time of start / acceleration, the control unit 9 detects a start operation of the driver such as a transmission gear position, a stepping amount of a clutch pedal, an accelerator opening, and the like.
The switching valve 5 is opened, the tilt angle of the hydraulic pump / motor 3 is controlled, and the oil accumulated in the accumulator 6 is caused to flow in the direction opposite to the time of the braking operation.
A torque is generated in the hydraulic motor to drive the wheels to assist the driving force generated by the engine. Thus NO _X in the exhaust gas during start and acceleration, the reduction of CO _2, the fuel consumption, the reduction of black smoke is achieved. This braking energy regeneration system 10 is effective for a route bus or the like that travels in an urban area where many starts and stops are performed.

FIG. 2 shows an air service brake 15 .
The brake shown in Fig. 1 is used as an auxiliary brake using a brake.
1 shows a brake system using an energy regenerating system 10. When a brake pedal 7 is depressed, an air tank 12 is opened through a brake valve 11 that opens according to the amount of depression.
Is supplied to the differential pressure valve 13. A bypass passage 18 is provided in the differential pressure valve 13, and the bypass passage 18
A bypass valve (on-off solenoid valve) 19 for opening and closing the valve is connected. The differential pressure valve 13 opens when the air pressure at the input port 13a becomes higher than the air pressure at the output port 13b and the differential pressure exceeds a set pressure. In addition, the bypass valve 19,
The valve is opened when not energized and closed when energized.

When a signal (brake signal) is input from a pressure sensor 14 for detecting a discharge pressure of a brake valve 11, a control unit 9 activates a braking energy regeneration system (hereinafter, referred to as "auxiliary brake") 10 and bypasses the system. By closing the valve 19 to close the bypass passage 18, the auxiliary brake 10 can be activated before the differential pressure valve 13 is activated, that is, before the service brake 15 is activated, so that braking energy can be effectively recovered. I have. At this time, the vehicle is braked by the auxiliary brake 10.

When the amount of depression of the brake pedal 7 increases and the air pressure discharged from the brake valve 11 exceeds the set pressure of the differential pressure valve 13, the differential pressure valve 13 opens to supply air pressure to the air master 16. As a result, the air master 16 operates to drive the main brake device 17. That is, the service brake 15 operates. At this time, the auxiliary brake 10 is also operating.

[0009]

In the above-mentioned brake system, if the bypass valve 19 is always opened during braking, the service brake 15 always operates.
The effect of using the auxiliary brake for recovering the braking energy is reduced. If the bypass valve 19 is always closed to enhance the effect of the auxiliary brake, the chance of braking by the service brake decreases, and if the bypass valve 19 is suddenly opened when there is a problem with the auxiliary brake, the auxiliary brake There is a feeling of discomfort because the feeling is different from a vehicle that is not equipped. Further, when the vehicle speed is not taken into consideration, there is a problem that tuning on the high speed side and tuning on the low speed side are not compatible, and the brake feeling becomes poor.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and makes the brake feeling of a vehicle having an auxiliary brake used at the time of starting by recovering braking energy different from the brake feeling of a vehicle having no auxiliary brake. an object of the present invention is to provide an air brake system that was set to no.

[0011]

According to the present invention, in order to achieve the above object, according to the amount of depression of a brake pedal,
Between the air master and the brake valve that outputs the compressed air pressure
The air on the output side of the brake valve
The pressure difference between the air pressure and the air pressure on the air master side exceeds the set pressure.
When the air pressure of the brake valve is
Differential pressure valve that can be supplied to the side, and connected in parallel with the differential pressure valve
Air pressure of the brake valve can be supplied to the air master
A bypass valve for opening and closing a bypass passage,
Air pressure detecting means for detecting the air pressure of the key valve;
Air pressure is output from the brake valve by the
When the force is detected, the auxiliary brake is activated and
When the change in air pressure is larger than a predetermined value,
Open the bypass valve and change the air pressure by less than a predetermined value.
Control means for closing the bypass valve when
The predetermined value is set to a large value when the vehicle speed is low.
Note that the setting is small when the vehicle speed is high.
Sign.

[0012]

When the vehicle speed is high , the control means opens the bypass passage even when the brake pedal is depressed at a relatively low stepping speed, and supplies air pressure to the air master of the service brake to activate the service brake. Control means
When the vehicle speed is low, the bypass passage is opened when the brake pedal is quickly depressed, and the service brake is operated. As described above, the determination based on the depressing speed of the brake pedal is changed according to the vehicle speed to improve the brake feeling. Then, in a low vehicle speed range where there is no need for sudden braking, the frequency of use of the auxiliary brake is increased, and the braking energy is effectively recovered. As a result, a brake feeling that is not uncomfortable with a vehicle without the auxiliary brake can be obtained.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the accompanying drawings. The same members as those in FIG. 2 are denoted by the same reference numerals. In FIG. 3, the brake valve 11 of the air brake system has an input port connected to the air tank 12 and a discharge port connected to the input port 13 a of the differential pressure valve 13 through the air passage 30.
And the output port 13b of the differential pressure valve 13
Can be connected to the air master 16 of the service brake 15 via the bypass valve 20. The air master 16 is connected to the main brake device 17.

The air passage 30 is provided with a pressure sensor 14, and the differential pressure valve 13 is provided with a bypass passage 31. The bypass passage 31 has one end connected to the air passage 30 downstream of the pressure sensor 14, and the other end connectable to the air master 16 via the bypass valve 20. The pressure sensor 14 and the bypass valve 20 are connected to a control unit (C / U) 9, and an auxiliary brake 10 is electrically connected to the control unit 9.

The brake valve 11 is connected to the brake pedal 7
The valve is opened according to the amount of stepping on the air tank, and the air pressure in the air tank 12 is supplied to the air passage 30. The differential pressure valve 13 opens when the air pressure in the air passage 30 becomes higher than the air pressure on the input side of the air master 16 and the differential pressure exceeds a set pressure.
Supply air pressure to The air master 16 includes the air tank 1
The main brake device 17 is driven according to the air pressure supplied from 2 through the differential pressure valve 13 to apply a braking force to the wheels.
The pressure sensor 14 detects the air pressure in the air passage 30 and outputs a corresponding pressure signal (brake signal) to apply to the control unit 9.

The bypass valve 20 is a three-way solenoid valve, which is controlled by the control unit 9 to switch the solenoid valve 20s.
Is switched to the position 20A due to the spring force of the return spring, and is switched to the position 20B when the solenoid 20s is biased. When the bypass valve 20 is switched to the position 20A, the differential pressure valve 1
3 and shuts off the output port 13b.
When the position 1 is connected to the air master 16 and switched to the position 20B, the output port 13b of the differential pressure valve 13 and the air master 16 are connected and the bypass passage 31 is shut off.

The control unit 9 includes the pressure sensor 1
The auxiliary brake 10 is controlled and the bypass valve 20 is energized in response to the signal from the control unit 4, and the auxiliary brake 10 is operated before the service brake 15 is operated during normal deceleration. Further, the control unit 9 includes a pressure sensor 14
The bypass valve 20 is controlled by a signal input from the controller.
That is, the control unit 9 closes the bypass passage 31 by urging the bypass valve 20 when the depression speed of the brake pedal 7 is low and the amount of change in pressure is smaller than the threshold value.
When the depression speed of the brake pedal 7 is high and the amount of change in pressure is greater than the threshold value, the bypass valve 20 is deenergized and the bypass passage 31 is opened.

Further, the control unit 9 changes the judgment based on the depressing speed of the brake pedal 7 depending on the vehicle speed. That is, the control unit 9 inputs the vehicle speed signal and changes the threshold value according to the vehicle speed. When the vehicle speed is low, the threshold value is increased and the bypass passage 31 is closed at the time of rapid stepping. The bypass passage 31 is opened even at the desired stepping speed. The relationship between the region where the bypass 31 is closed (bypass closed region) and the region where the bypass passage 31 is opened (bypass open region) based on the stepping speed of the brake pedal and the vehicle speed is set, for example, as shown in FIG.

The operation will be described below with reference to the flowchart of FIG. The brake valve 11 is closed when the brake pedal 7 is released, and the pressure sensor 14 does not output a signal. The control unit 9 holds the auxiliary brake 10 in a non-operating state and deenergizes the bypass valve 20. Bypass valve 2
0 is switched to the position 20A when deenergized, the output port 13b of the differential pressure valve 13 is shut off,
The bypass passage 31 is connected to the air master 16.

When the brake pedal 7 is depressed, the brake valve 11 opens in response to this, and the air pressure in the air tank 12 is supplied to the air passage 30. Pressure sensor 14
Detects this pressure and applies a corresponding signal to the control unit 9. When a signal is input from the pressure sensor 14, the control unit 9 starts controlling the bypass valve 20 (FIG. 5), inputs a vehicle speed signal (step 1), and depresses the brake pedal 7 to open the bypass from the map based on the map. Is set (FIG. 4), and the stepping speed of the brake pedal 7 (the amount of change in air pressure) is obtained from the signal input from the pressure sensor 14 (step 2).

The control unit 9 compares the depressing speed of the brake pedal 7 with the threshold to determine whether or not the brake pedal 7 is in the bypass open area (step 3). When the braking frequency is high and the vehicle speed is high, it is determined that the brake pedal 7 is in the bypass open area even when the stepping speed of the brake pedal 7 is relatively low. Then, the bypass valve 20 is deenergized to open the bypass passage 31 (step 5), and the bypass passage 31 is connected to the air master 16. As a result, the air pressure is supplied from the brake valve 11 to the air master 16 bypassing the differential pressure valve 13 and the main brake device 17 is driven. That is, the vehicle is decelerated by the service brake 15. At this time, the auxiliary brake 10 is also operating.

When the answer to the step 3 is negative (NO), that is, when the control unit 9 determines that the vehicle is in the bypass closed region, the control unit 9 closes the bypass passage 31 by energizing the bypass valve 20 (step 4). Output port 1
3b is connected to the air master 16. Therefore, the service brake 15 does not operate until the differential pressure valve 13 is opened, the vehicle is decelerated only by the auxiliary brake 10, and the braking energy is effectively recovered. As a result, the usage rate of the auxiliary brake in a low vehicle speed range where it is not necessary to apply the braking very rapidly is increased, and the effect of the braking energy is increased.

In the above embodiment, the bypass valve 2
Although a three-way solenoid valve is used as 0, the present invention is not limited to this, and an electromagnetic valve that simply opens and closes the bypass passage may be used as shown in FIG.

[0024]

As described above, according to the present invention, when the vehicle speed is high, the service brake is activated even when the brake pedal is depressed relatively slowly, and when the vehicle speed is low, the service brake is activated when the brake pedal is depressed fast. By operating, it is possible to obtain a brake feeling that is less uncomfortable with a vehicle that is not equipped with an auxiliary brake. Further, there is an effect that the use ratio of the auxiliary brake in a low vehicle speed range where it is not necessary to apply the braking very rapidly can be increased, and the braking energy can be effectively recovered.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an outline of a braking energy regeneration system.

FIG. 2 is a configuration diagram illustrating an air brake system of a vehicle equipped with the braking energy regeneration system of FIG. 1;

Is a block diagram showing an embodiment of an air brake system according to the present invention; FIG.

FIG. 4 is a graph showing an example of conditions for opening and closing a bypass passage of the air brake system of FIG. 3;

FIG. 5 is a flowchart showing a procedure of a control method of the air brake system of FIG. 3;

[Explanation of symbols]

 Reference Signs List 1 axle 2 gearbox 3 hydraulic pump / motor 4 hydraulic oil tank 5 switching valve 6 accumulator 7 brake pedal 8 accelerator pedal 9 control unit 10 braking energy regeneration system (auxiliary brake) 11 brake valve 13 differential pressure valve 14 pressure sensor 15 service brake 16 Air master 17 Main brake device 20 Solenoid valve

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B60T 1/10 B60K 25/00

Claims (1)

(57) [Claims] 1. An air compressor according to the amount of depression of a brake pedal.
Pressure between the brake valve that outputs pressure and the air master
Air pressure on the output side of the brake valve
When the pressure difference from the air pressure on the air master side exceeds the set pressure
The air pressure of the brake valve to the air master side
A differential pressure valve that can be supplied , and air for the brake valve that is connected in parallel with the differential pressure valve.
Open and close a bypass passage that can supply pressure to the air master
A bypass valve that the air pressure detecting means for detecting the air pressure of the brake valve
When, the air from the brake valve by the air pressure detecting means
When the pressure output is detected, the auxiliary brake is activated and
When the amount of change in the air pressure is larger than a predetermined value,
The bypass valve is opened, and the amount of change in the air pressure is predetermined.
Control means for closing the bypass valve when the value is equal to or less than the value
The predetermined value is set to be large when the vehicle speed is low,
It is characterized by being set small when the speed is high
Air brake system.