CN112644447B

CN112644447B - Pneumatic relay system for automobile

Info

Publication number: CN112644447B
Application number: CN201910963652.8A
Authority: CN
Inventors: 梁助兴
Original assignee: Individual
Current assignee: Individual
Priority date: 2019-10-11
Filing date: 2019-10-11
Publication date: 2022-01-25
Anticipated expiration: 2039-10-11
Also published as: CN112644447A

Abstract

The invention relates to a pneumatic relay system for an automobile. Pneumatic relay valves are commonly used in heavy-duty vehicles, and have the function of preventing air flow entering and exiting a brake chamber from bypassing a master brake valve, so that the air flow speed of the brake chamber can be increased. There are many types of relay valves available on the market. However, the prior relay valves have a common disadvantage: at low intensity braking, the dynamic response is sluggish. Analysis and experiments show that the problem is caused because the throttling effect of the valve port of the relay valve is strong during low-intensity braking, so that the outlet pressure of the relay valve can only be equal to the expected brake chamber pressure, and the low outlet pressure causes the result of slow inflation. The invention adopts a novel relay valve structure, adds a feedback cavity directly communicated with a brake air chamber and also adds a special feedback pipe. The invention reduces the throttle resistance of the valve port to the lowest level, and greatly improves the dynamic response speed during low-intensity braking.

Description

Pneumatic relay system for automobile

Technical Field

The invention relates to an air pressure relay system for braking a heavy-duty car. Patent classification No. B60T 15/18.

Background

Pneumatic relay valves are commonly used in heavy-duty vehicles, and have the function of preventing air flow entering and exiting a brake chamber from bypassing a master brake valve, so that the response speed of a brake system can be increased. Various types of relay valves are already on the market, some of which are integrated with an emergency brake valve and are called emergency relay valves, and some of which are integrated with an ABS anti-lock device and are called anti-lock relay valves. The following applies to both a stand-alone relay valve and to an emergency relay valve and an anti-lock relay valve. For convenience of description, the combination of the three is referred to as a relay valve in the present application.

The prior relay valves have a common disadvantage: at low intensity braking, the dynamic response is sluggish. Analysis and experiments show that the reason for causing the problem is that when the low-intensity braking is carried out, the control air pressure acting on the front surface of the relay valve piston (or diaphragm) is low, the very high inlet air pressure can quickly act on the back surface of the piston at the moment when the valve port of the relay valve is opened, the piston can move towards the closing direction of the valve port, the opening degree of the valve port is reduced, the throttling resistance is generated, and the reaction time of the low-intensity braking is prolonged.

An example of low intensity braking would help to understand the problems with existing relay valves. Assuming that the pressure of the brake air cylinder is 8 bar (which is a common value of an automobile), assuming that a driver lightly steps on a brake pedal to enable a brake main valve to transmit 1 bar of pressure to a relay valve, the pressure value of 1 bar of the brake air chamber can be expected to be obtained, and primary low-intensity braking is realized. After the piston of the relay valve has reached a pressure of 1 bar on the front side and pushed open the valve port, the pressure downstream of the valve port (and on the back side of the piston) reaches an air reservoir pressure of approximately 8 bar, which is much higher than the pressure on the front side of the piston (1 bar), forcing the piston to retract immediately and causing throttling of the valve port. The result of throttling is that the pressure downstream of the valve port (i.e. the output pressure of the relay valve) cannot be higher than 1 bar (otherwise the piston would be pushed upwards and the valve port would close completely, causing interruption of the inlet air). That is, although the pressure of the air reservoir is up to 8 bar, the relay valve always reduces the pressure at the outlet to 1 bar by throttling and then charges the brake chamber. The throttling effect makes the high pressure of the air reservoir not fully utilized. It is envisaged that if the relay valve outlet pressure is not 1 bar, but 8 bar, the rate of inflation will certainly be greatly increased.

From this example we can identify an important feature of the relay valve: it is also a pressure regulating valve in nature, which always uses the throttling action of valve port to reduce the pressure of air storage cylinder to be equal to the input pressure (equal to the target pressure of brake chamber), and then supplies air to the brake chamber from output port. That is, the relay valve outputs an equal pressure to inflate the brake chamber, rather than the high pressure of the air reservoir. It has been found that the negative effects of such reduced pressure charging are very significant during low intensity braking.

Disclosure of Invention

In order to overcome the defects of the conventional relay valve and shorten the time for charging the brake chamber, the design idea is to eliminate the throttling function of the valve port of the relay valve, enable the valve port to always work in a fully-opened state and a fully-closed state and directly charge the brake chamber without reducing the pressure of the air storage cylinder.

The invention adopts the technical scheme shown in figure 1. A partition layer (12) is added between the valve port (11) and the piston (6), so that high-pressure gas entering the brake cavity (3) cannot directly impact the piston (or the diaphragm) upwards.

After the addition of the diaphragm (12), a feedback chamber (5) is formed between the diaphragm and the piston. Thus, the pressure difference between the control chamber (7) and the feedback chamber determines the movement of the piston and the opening and closing of the valve port, and the pressure in the brake chamber (3) does not directly influence the action of the piston.

The invention arranges a feedback air port (2) on the interlayer, and a feedback pipe (17) is used to connect a brake chamber (commonly called a slave cylinder) (16) with a feedback cavity (5) through the air port. Because of the small volume of the feedback chamber, the pressure therein can quickly follow the pressure change of the brake chamber.

When the brake is started, the piston cannot move upwards even if the valve port is fully opened so that the pressure in the brake cavity (3) is close to the pressure of the air storage cylinder. The valve port is kept in a full-open state until the pressure of the brake air chamber (16) and the feedback chamber (5) rises to be equal to the pressure of the control chamber (7), and the valve port can not be closed rapidly. In the process, the throttling function of the valve port is reduced to the lowest level, the pressure of the brake air port (1) is increased to be close to the pressure of the air storage cylinder, and the air charging speed is accelerated.

Since the change in pressure in the feedback chamber (5) will slightly lag behind the pressure in the brake chamber, the pressure in the brake chamber will slightly overshoot. In order to reduce the overshoot, a sealing ring is not arranged in a matching hole of the piston rod (10) and the interlayer (12), but a matching gap is properly enlarged, or a throttling groove (4) is machined, so that a very small amount of gas is allowed to directly enter a feedback cavity (5) from a brake cavity (3) in a 'leakage' mode, the pressure lag of the feedback cavity is offset, and the pressure overshoot in the brake cavity is reduced.

From the above description, it can be seen that the present invention includes two parts, the first part is a new relay valve structure and adds a feedback chamber, and the second part is an additional feedback pipe between the relay valve and the brake chamber.

The invention is further illustrated with reference to the following figures and examples.

Drawings

FIG. 1 depicts the system components and relay valve modifications of the present invention.

The meaning of the reference numerals in the figures: 1. the brake system comprises a brake air port, 2 a feedback air port, 3 a brake cavity, 4 a throttling groove, 5 a feedback cavity, 6 a piston (or a diaphragm), 7 a control cavity, 8 a control air port (connected with a brake main valve), 9 an upper cover, 10 a piston rod, 11 a valve port, 12 a partition layer, 13 a valve body, 14 an air inlet (connected with an air storage cylinder), 15 an exhaust port, 16 a brake air chamber, 17 a feedback pipe and 18 a brake air chamber pipeline.

Detailed Description

In the embodiment, a partition (12) is arranged between the piston (6) and the valve port (11), and the partition separates the brake cavity from the feedback cavity. The piston rod (10) passes through the interlayer to control the opening and closing of the valve port (11) and the exhaust port (15).

The feedback cavity (5) is connected with the feedback air port (2). The brake chamber (16) and the feedback chamber (5) are communicated with each other through the feedback air port and the feedback pipe (17).

In an embodiment, the return air port is arranged on the side of the barrier. It may also be arranged on the side of the upper cover as long as it is able to communicate with the feedback chamber.

In an embodiment, the interlayer is sandwiched between the upper cover and the valve body and is exposed. If the feedback air port is arranged on the side surface of the upper cover, the interlayer can be embedded into the upper cover or the valve body and is not exposed.

In the embodiment, a gap is left at the matching part of the piston rod and the interlayer, and the gap plays the role of a throttling groove.

The invention adds a feedback tube (17). The feedback pipe can be linked to any brake chamber, and a brake chamber with a longer pipeline is preferably selected.

The feedback tube is preferably independently connected to the brake chamber, or the brake chamber line (18) and feedback tube (17) may be connected to the brake chamber via a three-way connection.

The working process is as follows: when a driver steps on a brake pedal, air output by the master brake valve enters the control cavity (7) from the control air port (8) to push the piston to move downwards. The piston rod closes the exhaust port (15) and opens the air inlet valve port (11), and air in the air storage cylinder enters the brake air chamber (16) through the air inlet (14), the valve port (11), the brake air port (1) and the brake air chamber pipeline (18) to realize braking. In the process, the valve port is in a full-open state all the time, and the valve port can not be closed quickly until the pressure of the brake air chamber (16) and the feedback chamber (5) is equal to the control pressure.

The invention has the beneficial effects that: when the novel system is used for braking, the valve port always charges air to the brake chamber in a fully-opened state, so that the throttling effect of the valve port is reduced, and the pressure rise time of the brake chamber is obviously shortened. Still taking the target pressure of 1 bar as an example, the outlet pressure of the old relay valve is 1 bar, the outlet pressure of the new relay valve is 8 bar, and the inflation speed of the new system is obviously several times faster. The practical test proves that the air charging time of the brake chamber can be even shortened to less than one third when the brake is braked with low intensity. The pressure in the brake chamber rises quickly and the driver feels that the pressure is more comfortable.

The new system can improve not only the dynamic response when the brake pedal is depressed, but also the dynamic response when the brake pedal is released. That is, it is fast to inflate and fast to deflate.

In both cases, the benefits of the present invention are not evident: the first case is to press the brake pedal to the bottom extremely quickly; the second situation is a very quick complete release of the brake pedal. In addition to both cases, the present invention can significantly improve dynamic response. In summary, the invention aims to solve the problem of foot following in non-emergency situations, and the heavy vehicle driver can realize low-intensity braking by slightly stepping on the brake pedal like driving a car without needing 'spot braking' operation.

Claims

1. The pneumatic relay system used by the automobile consists of a valve body (13), an upper cover (9), a piston or diaphragm (6) and a valve port (11), and is characterized in that an interlayer (12) is arranged between the piston or diaphragm (6) and the valve port (11), and the interlayer separates a brake cavity (3) from a feedback cavity (5); the piston rod (10) penetrates through the partition layer to control the opening and closing of the valve port (11) and the exhaust port (15); the feedback cavity (5) is connected with a feedback air port (2); the brake chamber (16) and the feedback cavity (5) are communicated with each other through the feedback air port (2) and the feedback pipe (17).

2. Pneumatic relay system according to claim 1, characterised in that the return air port is arranged on the side of the diaphragm (12) or on the side of the upper cover (9).

3. A pneumatic relay system according to claim 1, wherein the diaphragm is sandwiched between the upper cover (9) and the valve body (13), or embedded inside the upper cover (9), or embedded inside the valve body (13).