JPH0953472A - Exhaust brake device - Google Patents

Abstract

(57) [Abstract] [Problem] To prevent the exhaust valve from being forcibly opened,
Immediately after the exhaust brake is activated, the pressure in the exhaust manifold is rapidly increased to obtain a large braking force. SOLUTION: A support shaft 20a which is integral with the valve body 20 and a supporting member which slidably holds the support shaft 20a are provided on a back surface of a valve body 20 which is provided with a rotary shaft 24 laterally offset in an exhaust pipe 6. 21,
A pressure adjusting mechanism P including an elastic member 22 for urging the support shaft 20a toward the exhaust gas upstream side is provided. When the pressure in the exhaust manifold rises to a predetermined value, the valve body 20 opens slightly against the elastic member 22 to reduce the pressure in the exhaust manifold.

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.

[0002]

2. Description of the Related Art Exhaust brakes are intended to enhance the braking effect when a so-called engine brake is used. By operating an exhaust shutter provided in an exhaust pipe to block the exhaust passage and increase the internal pressure of an exhaust manifold, The engine acts as a compressor to obtain a braking effect.

FIG. 7 schematically shows a conventional exhaust brake device. (1) is an engine cylinder, (2) is a piston, (3) is an exhaust valve, (4) is an intake valve, and (5) is. Is an exhaust manifold, (6) is an exhaust pipe, (7) is an intake manifold, and (8) is an intake pipe. is there.

The exhaust pipe (6) and the intake pipe (8) are respectively
An exhaust shutter (11) and an intake shutter (12) that are opened and closed by a first air cylinder (9) and a second air cylinder (10) are provided, and both air cylinders (9) and (10) have an air tank (1
The compressed air in 3) is simultaneously supplied through the solenoid valve (15) and the air pipe (14). (16) is an accelerator switch for actuating the solenoid valve (15).

In the above-mentioned device, an accelerator pedal (not shown) is actuated to operate the accelerator pedal.
When you release your foot from (17), the accelerator switch (16) will close and the solenoid valve (15) will open.
Compressed air is supplied to (9) and (10), and the exhaust shutter (11) and the intake shutter (12) are closed at the same time.

As a result, the internal pressure of the exhaust manifold (5) rises rapidly and the reciprocating motion of the piston (2) is restricted,
A great braking effect is obtained.

[0007]

In such an exhaust brake device, in order to enhance the braking effect, the exhaust shutter (11) is rapidly closed to instantly increase the internal pressure of the exhaust manifold (5). Is desirable. However, if the exhaust shutter (11) is rapidly closed during high-speed operation, the internal pressure of the exhaust manifold (5) rises above the set load of the valve spring (not shown) of the exhaust valve (3), and Valve (3)
Valve is forcibly opened and air flows backward to the intake manifold (7) side, making a loud noise, or the exhaust valve (3) abuts on the head of the piston (2) and damages them. It may happen.

In order to prevent the above-mentioned problems from occurring, the opening degree of the exhaust shutter (11) is finely controlled,
It is necessary that the pressure inside the exhaust manifold does not exceed the valve opening pressure of the exhaust valve.

However, in this case, it is necessary to provide a sensor for detecting the pressure in the exhaust manifold, a control means for controlling the actuator for operating the exhaust shutter, and the like, which complicates the control system and increases the number of parts. Therefore, the cost is high.

The present invention has been made in view of the above problems, and by changing the shape and driving form of the exhaust shutter, a large braking effect can be obtained immediately after the exhaust brake is activated without opening the exhaust valve. It is an object of the present invention to provide an exhaust brake device of the above type.

[0011]

According to the present invention, the above problems can be solved as follows.

(1) A valve body supported by a rotary shaft that is laterally offset from the center of the pipe axis in the exhaust pipe is driven by an actuator to rotate the valve body to the exhaust upstream side. When the valve body is closed, the flow passage is closed when moving, and the flow passage is opened when rotating to the exhaust downstream side. The linking member that links the valve body and the actuator is provided with an exhaust manifold when the valve body is closed. A pressure adjusting mechanism is provided so that, when the internal pressure approaches a predetermined upper limit pressure, the valve body is slightly opened to reduce the internal pressure of the exhaust manifold.

(2) In the above item (1), the pressure adjusting mechanism is
A support shaft provided on the surface of the valve body on the exhaust downstream side, a support member that holds the support shaft slidably in the pipe axis direction, and an elastic member provided between the support shaft and the support member.

(3) In the above item (1), the pressure adjusting mechanism is linked to an external drive lever for driving the rotating shaft, and a connecting member for slidably holding the piston rod of the actuator, and a piston rod tip end. An elastic member provided between the elastic member and the connecting member.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. It should be noted that the same members as those in the above-described conventional example are denoted by the same reference numerals, and detailed description thereof will be omitted.

1 to 3 show a first embodiment of the present invention, in which a pressure regulating device (1) connected near the base end of an exhaust pipe (6) is shown.
In the substantially box-shaped valve box (19) in 8), a disk-shaped valve body (20) is provided with a support shaft (20a) at the center of the rear surface in a cylindrical shape instead of the conventional exhaust shutter. A link piece (23) having one end slidably fitted in the support member (21) through a compression coil spring (22) in the pipe axial direction, and one end of which is pivotally attached to the end of the support member (21). By fixing the other end of the rotary shaft (24), which is pivotally supported by the cylindrical wall (19a) at a position completely removed from the flow path in the valve box (19), and which is oriented in the direction orthogonal to the pipe line, It is housed so as to be rotatable. The valve body (20) is a support member by screwing a bolt (26) from the support member (21) side into an axially long groove (25) formed on the outer peripheral surface of the support shaft (20a). (21) is prevented from coming off.

The support shaft (20a), the support member (21), the compression coil spring (22) and the like constitute a pressure adjusting mechanism (P).

As shown in FIG. 2, the valve body (20) is a valve-closing valve whose seat surface (20b) formed in the front surface thereof abuts an opening in the valve box (19) on the exhaust upstream side. Position (solid line position shown)
And the link piece (23) and the valve body (20) rotate about 90 ° about the rotation shaft (24), and the valve body (20) greatly opens the flow path (the open position shown in the figure). Position). When the valve is opened, the link piece (23)
9a) is housed in a recess (19b) formed on the inner surface of the valve body (2
0) and the link piece (23) are completely retracted from the flow path.

In the compression coil spring (22), when the valve body (20) is closed, the pressure in the exhaust pipe upstream of the valve body (20) becomes
The spring constant of the exhaust valve (3) is set so that the valve spring (not shown) is compressed when it reaches the vicinity of the set load.

A drive arm (27) is fixed to the protruding end of the rotary shaft (24) from the valve box (19), and a long hole (27a) facing the longitudinal direction is formed at the tip end thereof. There is.

In the elongated hole (27a), the tip of the piston rod (28a) in the single-acting air cylinder (28) fixed to the immovable body (not shown) along with the exhaust pipe (6) is connected to the connector. Pin-pinned via (29).

The air cylinder (28) is a constant pressure air tank which is always kept at a predetermined pressure through the air pipe (14) and the solenoid valve (15).
It is connected to (13).

In the device of the first embodiment, when the exhaust brake is inactive, the solenoid valve (15) is off, so the air cylinder (28) does not operate and its piston rod
As the valve (28a) retracts, the valve body (20) rotates to the position indicated by the imaginary line in FIG. 2, and the exhaust gas passage is largely opened.

When the foot is released from the accelerator pedal (17) in order to operate the exhaust brake, the solenoid valve (15) is operated by the accelerator switch (16) and the constant pressure tank (13) causes an air cylinder for the intake shutter. Compressed air is supplied to the air cylinder (28) and the air cylinder (28) at the same time, the intake shutter (12) is closed to a predetermined opening, the piston rod (28a) is projected, and the valve body (20) is compressed by a coil. It is closed via the spring (22) to the position shown in full line in FIG. As a result, the internal pressure of the exhaust manifold (5) rises and a braking effect is obtained.

When the vehicle is operating at high speed, the valve body (20) is rapidly closed, and the pressure in the exhaust manifold (5) is a predetermined upper limit pressure, that is, a valve spring (not shown) of the exhaust valve (3). As shown in Fig. 3, the valve body (20)
Is slightly opened by compressing the compression coil spring (22). As a result, the pressure in the exhaust manifold (5) is reduced, and the exhaust valve (3) is prevented from being forcibly opened. When the pressure in the exhaust manifold (5) is reduced to a predetermined pressure, the valve body (20) is closed again by the urging force of the compression coil spring (22) to increase the pressure in the exhaust manifold (5). By repeating this opening / closing operation, the pressure in the exhaust manifold (5) during the operation of the exhaust brake is maintained at a high pressure slightly lower than the valve opening pressure of the exhaust valve (3), and the braking effect is maintained.

When the center of rotation of the valve body (20) is at a position largely deviated laterally from the flow path of the exhaust pipe (6) as in the above embodiment, when the valve body (20) is fully opened, By completely retreating from the flow path, the exhaust gas flow resistance can be greatly reduced.

4 and 5 show a second embodiment of the present invention. In this embodiment, the pressure adjusting mechanism (P) is connected to the drive arm (27).
And between the piston rod (28a). That is, the pressure adjusting mechanism (P) moves the tip of the drive arm (27) to
Coupling tool whose air cylinder (28) side is the cylindrical part (30a)
It is connected to the tip of (30) and the enlarged diameter part (28b) of the tip of the piston rod (28a) is slidably fitted into the cylindrical part (30a) via the compression coil spring (22). It is configured by

(31) is a cylindrical portion (30) of the piston rod (28a)
a) A cap to prevent it from falling out of the inside of the cylindrical part (3
It is screwed to the outer peripheral surface of 0a).

Also in this second embodiment, when the pressure in the exhaust manifold (5) reaches a predetermined upper limit pressure when the valve body (20) is closed, as shown in FIG. ) Compresses the compression coil spring (22) and moves to the left, so that the valve body (20) is slightly opened. As a result, as in the first embodiment, the pressure in the exhaust manifold (5) is reduced, and the exhaust valve (3) is prevented from being forcibly opened.

In the second embodiment, since it is only necessary to provide a short protruding piece (20c) for pivotally attaching to the link piece (23) on the rear surface of the valve body (20), the first embodiment Link piece (2
The rotation range of 3) and the valve body (20) is small, and the valve box (19) can be downsized.

Further, since the pressure adjusting mechanism (P) is provided outside, it is hardly affected by heat. The present invention relates to the first,
It is not limited to the second embodiment. For example, as shown in FIG. 6, the rotary shaft (24) protruding outward from the valve box (19).
End of the torsion coil spring (33) fitted to the drive shaft (32) connected to the drive arm (27) in a rotatable manner, and each end of the torsion coil spring (33) externally fitted to the connecting portion of both shafts. , Respectively the rotation axis
The rotary shaft (24) and the valve body (20) linked to the rotary shaft (24) are engaged with the drive shaft (32) and driven by the torsion coil spring (33).

Also in this embodiment, when the pressure in the exhaust manifold (5) reaches a predetermined upper limit pressure when the valve body (20) is closed, the drive shaft (32) does not rotate but the rotary shaft (24 ) Rotates against the biasing force of the torsion coil spring (33), and as a result, the valve body (20) is slightly opened and the pressure in the exhaust manifold (5) is reduced.

Although the actuator for driving the valve body (20) is the air cylinder (28) in the above embodiment, it may be a solenoid.

[0034]

According to the present invention, even if the valve body is suddenly closed and the pressure in the exhaust manifold is rapidly increased, the valve body is automatically opened by the pressure adjusting mechanism to adjust the pressure when the pressure reaches a predetermined pressure. Therefore, the opening pressure of the exhaust valve is not exceeded. Also,
Since the pressure in the exhaust manifold can be rapidly increased immediately after the exhaust brake is activated, a great braking effect can be obtained in a wide operating range from low speed to high speed.

According to the second aspect, the structure of the pressure adjusting mechanism is simplified, so that it can be manufactured at low cost.

According to the third aspect, in addition to the effect of the second aspect, the pressure adjusting mechanism is less susceptible to the exhaust heat and the durability is improved.

[Brief description of drawings]

FIG. 1 is a schematic front view showing a first embodiment of the present invention.

FIG. 2 is a vertical cross-sectional front view showing details of the form of linkage between the valve body accommodating portion and the air cylinder.

FIG. 3 is a vertical sectional front view showing a state in which the valve element is slightly opened during the operation of the exhaust brake.

FIG. 4 is a partially cutaway vertical front view showing a second embodiment of the present invention.

FIG. 5 is a vertical sectional front view showing a state in which the valve body is slightly opened when the exhaust brake is activated.

FIG. 6 is a partially cutaway plan view of a rotary shaft portion showing another embodiment of the present invention.

FIG. 7 is a schematic front view showing a conventional exhaust brake device.

[Explanation of symbols]

 (1) Cylinder (2) Piston (3) Exhaust valve (4) Intake valve (5) Exhaust manifold (6) Exhaust pipe (7) Intake manifold (8) Intake pipe (9) First air cylinder (10) Second Air cylinder (11) Exhaust shutter (12) Intake shutter (13) Air tank (14) Air pipe (15) Solenoid valve (16) Accelerator switch (17) Accelerator pedal (18) Pressure regulator (19) Valve box (19a) Tube Wall (19b) Recess (20) Valve body (20a) Spindle (20b) Seat surface (20c) Projection piece (21) Spindle member (22) Compression coil spring (23) Link piece (24) Rotating shaft (25) Slot (26) Bolt (27) Drive arm (27a) Slot (28) Air cylinder (actuator) (28a) Piston rod (29) (30) Coupling (30a) Cylindrical part (31) Cap (32) Drive shaft (33) Torsion coil spring (P) Pressure adjustment mechanism

Claims (3)

[Claims] 1. A valve body supported in an exhaust pipe by a rotary shaft that is laterally offset from the center of the pipe axis, and the rotary shaft is driven by an actuator to rotate the valve body toward the exhaust upstream side. The flow passage is closed at the same time, and the flow passage is opened at the time of turning to the exhaust downstream side, and a linking member that links the valve body and the actuator is provided in the exhaust manifold when the valve body is closed. The exhaust brake device is provided with a pressure adjusting mechanism configured to reduce the pressure inside the exhaust manifold by slightly opening the valve body when the pressure in the exhaust gas approaches a predetermined upper limit pressure. 2. A pressure adjusting mechanism, wherein a support shaft provided on the exhaust gas downstream surface of the valve body, a support member for holding the support shaft slidably in the pipe axis direction, and a support member provided between the support shaft and the support member. The exhaust brake device according to claim 1, comprising an elastic member. 3. A pressure adjusting mechanism is provided between a connecting member linked to an external drive lever for driving a rotary shaft and slidably holding a piston rod of an actuator, and a tip of the piston rod and the connecting member. The exhaust brake device according to claim 1, comprising an elastic member.