JPH0925833A - Exhaust brake device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide great braking effect by rapidly increasing the pressure in an exhaust manifold up to near the upper limit just after an exhaust brake operation without opening an exhaust valve. SOLUTION: A pressure control valve 18 is arranged among a single-acting type fluid pressure cylinder 17 having a return spring by which an exhaust brake valve 7 arranged in an exhaust pipe 3 is opened and closed, a pressure sensor 19 by which pressure in an exhaust pipe further upstream from the exhaust brake valve 7 is detected and a pressure fluid supply source 9 by which pressure fluid is supplied to the fluid pressure cylinder 17. When the exhaust brake valve 7 is fully closed by the operation of the fluid pressure cylinder 17, the pressure sensor 19 detects that pressure in the exhaust pipe 3 has come up to preset upper limit pressure and the pressure control valve 18 reduces fluid pressure supplied to the fluid pressure cylinder 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust brake device mounted on, for example, a large diesel vehicle, and more particularly,
The present invention relates to an exhaust brake device that operates an exhaust brake valve using a fluid pressure cylinder.

[0002]

2. Description of the Related Art Exhaust brake devices increase the braking effect when using so-called engine braking, and actuate a butterfly-type exhaust brake valve provided in an exhaust pipe to close the pipe line and act the engine as a compressor. By letting. Braking force is obtained. In such an exhaust brake device, an air cylinder operated by compressed air is generally used as a means for opening and closing the exhaust brake valve. This is because the operation is reliable and inexpensive.

FIG. 5 shows a schematic system diagram of a commonly used exhaust brake device. To explain this briefly,
(1) is the exhaust manifold of the engine (2), (3)
Is an exhaust pipe connected to the exhaust manifold (1), (4)
Is an intake manifold, and (5) is an intake pipe connected to the intake manifold (4).

An exhaust brake valve (7) operated by air cylinders (6) and (6) is provided in the exhaust pipe (3) and the intake pipe (5).
And an intake shutter (8) are provided respectively. The compressed air in the air tank (9) is simultaneously supplied to each air cylinder (6) through the solenoid valve (10). (11) is an accelerator switch that operates the solenoid valve (10).

In the above conventional exhaust brake device, when the foot is released from the accelerator pedal (12) with the exhaust brake switch (not shown) turned on, the accelerator switch (11)
Is activated and the solenoid valve (10) is opened. Then, the compressed air in the air tank (9) is supplied to both air cylinders (6) and (6), and the exhaust brake valve (7) and the intake shutter (8) are simultaneously closed.

[0006] The intake shutter (8) is for preventing air from flowing backward and generating unpleasant noise during operation of the exhaust brake, and is completely provided to continuously supply air into the cylinder. It cannot be closed. When the exhaust brake valve (7) is closed, the air in the exhaust manifold (1) is compressed and the pressure increases, and the engine (2) acts as a compressor, so that a great braking effect is obtained.

In such an exhaust brake device, in order to obtain a larger braking force, it is desirable to close the exhaust brake valve (7) as quickly as possible and instantly increase the pressure in the exhaust manifold (1). However, in this case, especially during high-speed operation, the pressure in the exhaust manifold (1) rises above the set load of the valve spring (not shown) of the exhaust valve (13), and the exhaust valve (13) is forced to operate. Is opened to allow a large amount of air to enter the intake manifold.
There is a problem that it flows back to the (4) side and makes a loud noise, or the exhaust valve (13) comes into contact with the piston head and damages them.

Therefore, conventionally, as shown in FIG. 6, the pressure in the exhaust manifold (1) rises relatively slowly so as to reach the vicinity of the valve opening pressure (P) in the exhaust valve (13). In addition, the exhaust brake valve (7) is prevented from being completely closed to prevent the pressure in the exhaust manifold (1) from rapidly increasing.

[0009]

As described above, when the exhaust brake valve (7) is not closed completely and the pressure in the exhaust manifold (1) is increased relatively slowly, the exhaust brake is Immediately after the start of operation, a large braking force cannot be obtained. In particular, if the above-described control is performed during low-speed operation, the pressure in the exhaust manifold (1) will not rise sufficiently, and the exhaust brake will be less effective.

The object of the present invention is to rapidly increase the pressure in the exhaust manifold immediately after the operation of the exhaust brake to near the upper limit without opening the exhaust valve, so that a large braking effect can be obtained in almost the entire operating range. I did it,
It is to provide an exhaust brake device.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. The same members as those in the conventional example described above are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIG. 1 shows a schematic system diagram of an exhaust brake device of the present invention. In the cylindrical valve box (14) connected to the upstream side of the exhaust pipe (3), a butterfly type exhaust brake valve (7) having an elliptical plate shape is housed so as to be openable and closable as in the conventional case. .

As shown in detail in FIG. 2, the exhaust brake valve (7) has one end of a valve shaft (15) via a drive lever (16) and a piston rod (of a single-acting air cylinder (17)). It is linked to 17a). The air cylinder (17) is connected to the solenoid valve (10) via a solenoid type pressure control valve (pressure reducing valve) (18).

A pressure sensor (19) is attached to the exhaust pipe (3) upstream of the exhaust brake valve (7).
The pressure sensor (19) is electrically connected to the pressure control valve (18) via the control circuit (20).

The pressure control valve (18) is normally open, and the pressure sensor (19) is connected to the exhaust pipe (3) (exhaust manifold).
When the control circuit (20) outputs a signal to turn on when it detects that the pressure has reached a predetermined pressure, the internal control piston operates and the air from the high pressure air tank (9) on the primary side is released. The supply is shut off and the air on the secondary side, which is the discharge side, is leaked to the outside to reduce the pressure of the air between the air cylinder (17) and the pressure control valve (18).

In the exhaust brake device of the above embodiment,
Release the accelerator pedal (12) to operate the exhaust brake, and use the accelerator switch (11) to release the solenoid valve (10).
Is operated, compressed air is simultaneously supplied to the air cylinders (6) and (17), the intake shutter (8) is closed to a predetermined opening, and the exhaust brake valve (7) is shown in FIG. As described above, the piston (21) in the air cylinder (17) is moved rightward against the return spring (22) to be closed to the fully closed position. As a result, the pressure in the exhaust manifold (1) rises and a braking effect is obtained.

The exhaust brake valve (7) is suddenly closed during high-speed operation of the vehicle, and the pressure in the exhaust manifold (1) is set to a predetermined upper limit pressure, that is, a value of a valve spring (not shown) of the exhaust valve (13). When the pressure sensor (19) detects that the set load is approaching, the control circuit (20) operates, and the pressure control valve (18) is operated based on the signal generated from this. Then, the air from the air tank (9) to the air cylinder (17) is shut off, and the pressure of the air between the air cylinder (17) and the pressure control valve (18) is reduced, so that the air cylinder (17) As shown in FIG. 3, the inner piston (21) is slightly pushed back by the urging force of the return spring (22).

As a result, the piston rod (17a) is slightly retracted, the exhaust brake valve (7) is slightly opened, and the pressure in the exhaust manifold (1) is reduced.

When the pressure sensor (19) detects that the pressure in the exhaust manifold (1) has dropped to a predetermined pressure, the control circuit (20) receives the signal and turns off the pressure control valve (18). Compress the compressed air from the air tank (9) into the air cylinder again.
(17) to fully close the exhaust brake valve (7) to increase the pressure in the exhaust manifold (1).

In this way, when the pressure in the exhaust manifold (1) is detected, the pressure control valve (18) is turned on and off, and the degree of closure of the exhaust brake valve (7) is finely controlled.
As shown in FIG. 4, the pressure in the exhaust manifold (1) is
Even though the pressure rises suddenly, the valve opening pressure of the exhaust valve (13) is not exceeded, and is maintained near the upper limit pressure, so that a large braking force is maintained.

Further, since it becomes possible to fully close the exhaust brake valve (7) at the same time as the operation of the exhaust brake, the pressure in the exhaust manifold (1) rises sharply and a large control is performed even when the vehicle is operating at a low speed. Power is obtained.

[0022]

According to the present invention, even if the exhaust brake valve is suddenly closed and the pressure in the exhaust manifold is rapidly increased, the pressure control valve operates before the opening pressure of the exhaust valve is exceeded. Since the pressure of the fluid supplied to the fluid pressure cylinder is reduced and the fluid pressure cylinder is pushed back by the return spring to open the exhaust brake valve slightly, the inconvenience of opening the exhaust valve is eliminated.

Since the pressure in the exhaust manifold can be rapidly increased immediately after the exhaust brake is activated, a large braking effect can be obtained in a wide operating range from low speed to high speed.

[Brief description of drawings]

FIG. 1 is a schematic system diagram showing one embodiment of the present invention.

FIG. 2 is a vertical sectional side view showing details of a linking portion between the air cylinder and the exhaust brake valve.

FIG. 3 is a vertical sectional side view showing a state in which the exhaust brake valve is also slightly open.

FIG. 4 is an explanatory diagram showing an example of controlling the pressure in the exhaust manifold during the operation of the exhaust brake.

FIG. 5 is a schematic system diagram of a conventional exhaust brake device.

FIG. 6 is an explanatory diagram showing an example of controlling the pressure in the exhaust manifold in the same manner.

[Explanation of symbols]

 (1) Exhaust manifold (2) Engine (3) Exhaust pipe (4) Intake manifold (5) Intake pipe (6) Air cylinder (7) Exhaust brake valve (8) Intake shutter (9) Air tank (pressure fluid supply source) (10) Solenoid valve (11) Accelerator switch (12) Accelerator pedal (13) Exhaust valve (14) Valve box (15) Valve shaft (16) Drive lever (17) Air cylinder (Fluid pressure cylinder) (17a) Piston rod (18) Pressure control valve (19) Pressure sensor (20) Control circuit (21) Piston (22) Return spring

Claims (1)

[Claims] 1. A single-acting fluid pressure cylinder with a return spring for opening and closing an exhaust brake valve provided in the exhaust pipe, a pressure sensor for detecting a pressure in the exhaust pipe upstream of the exhaust brake valve, and the fluid pressure. When the exhaust brake valve is provided between the cylinder and a pressure fluid supply source that supplies pressure fluid to the cylinder and the exhaust brake valve is fully closed by the operation of the fluid pressure cylinder, the pressure sensor determines the pressure in the exhaust pipe in advance. An exhaust brake device, comprising: a pressure control valve for reducing the pressure of the fluid supplied to the fluid pressure cylinder by detecting that the upper limit pressure is approached.