JPS6231652Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an exhaust brake device, and more particularly, to an exhaust brake device in which the sealing function of a valve stem supporting a butterfly valve is improved.

The exhaust brake device has a butterfly valve disposed in the exhaust pipe, and by closing the butterfly valve, increases back pressure to the engine side, thereby increasing the effect of engine braking and ensuring safe driving. This butterfly valve is fixed to a pair of valve shafts supported by a body fixed to the exhaust pipe, but since the exhaust gas passing through the exhaust pipe is high temperature,
Thermal deformation of the valve stem is unavoidable, and the valve stem cannot be completely sealed. Such an insufficient seal will cause exhaust gas to escape from between the body and the valve stem to the atmosphere, and the back pressure on the engine side will rise below a specified value, reducing the effectiveness of engine braking. let Furthermore, the escape of exhaust gas from around the valve stem is not only a cause of air pollution, but also
This will lead to early corrosion of the valve stem, causing malfunction of the butterfly valve. Therefore, the seal of the valve stem that supports the butterfly valve is an extremely important requirement in maintaining the function of the exhaust brake.

Therefore, the purpose of this invention is to achieve a sealing effect by sliding the bushing that supports the valve shaft into the body, and making the bushing and the ring housed in the counterbore of the bushing come into close contact with the bracket. To provide an exhaust brake device which prevents deterioration of sealing effect by slidingly fitting a bushing to a body so as not to be affected by the temperature of exhaust gas.

An embodiment of this invention will be described with reference to the accompanying drawings.

An example of an exhaust brake system is shown in Figure 1.
In the figure, 1 is a pipe connected to an exhaust manifold (not shown), and 2 is a pipe connected to a muffler (not shown), through which exhaust gas is discharged into the atmosphere. A butterfly valve 3 is arranged between both pipes 1 and 2, and the butterfly valve 3 cooperates with a lever 7 pivotally mounted on a rod 6 whose one end is connected to a diaphragm 5 of an actuator 4. One chamber 8 defined by a diaphragm 5 in the actuator 4 is maintained at atmospheric pressure, and the other chamber 9 facing the actuator 4 can communicate with a vacuum pump 11 via a switching valve 10 . In room 9,
Also, when the selector switch 12 is off, the selector valve 1
Atmospheric pressure is introduced via 0. Therefore, there is no pressure difference between the chambers 8 and 9 when the changeover switch 12 is turned off, and the butterfly valve 3 is positioned along the flow of exhaust gas as shown in FIG. 1, reducing high back pressure to the engine side. Not created artificially. When the changeover switch 12 is turned on and the changeover valve 10 is operated, the chamber 9 is communicated with the vacuum pump 11 and becomes a negative pressure state, the diaphragm 5 moves to the chamber 9 side, and the rod 6 and lever 7 are actuated. Put the butterfly valve 3 in the closed position. In this state, the butterfly valve 3 is perpendicular to the flow direction of exhaust gas, creating a large back pressure on the engine side and increasing the effect of engine braking.

An example of the structure between the lever 7 and the butterfly valve 3 will be described with reference to FIG. Both pipes 1 and 2
The hollow body 13 between has a central through hole 14,
The second valve shaft 15 fixed to one end of the butterfly valve 3 is inserted into the central hole 14, and the cover 1 is inserted into the center hole 14.
6 is bolted to the body 13 to prevent exhaust gas from leaking from this part.

A bush 17 is slidably fitted between the body 13 and the second valve shaft 15.

The first valve shaft 18 has one end fixed to the butterfly valve 3 and is connected to the body 13 through the central hole 14.
penetrates and extends to the outside. The lever 7 is fixed to the end of the second valve shaft 18. A hollow bush 20 is seated on the stepped portion 19 of the central hole 14 of the body 13.
into the central hole 14. The tolerance between the inner wall surface of the central hole 14 of the body 13 and the bush 20 is selected so that the two do not come into a static fit relationship due to deformation or expansion due to heat of exhaust gas. This is Butsuyu 2
This prevents the bush 20 and the body 13 from cracking due to thermal expansion, which occurs when the bushing 20 and the body 13 are press-fitted into the center hole 14 of the body 13. A counterbore portion 21 is formed on the outer end surface of the bush 20. The outer annular end face of the counterbore portion 21 and the outer end face of the body 13 are brought into close contact with the bracket 22, and the bracket 22 is bolted to the body 13. A self-shrinkable ring 23 is arranged in the counterbore 21 of the bush 20, and the inner circumferential wall surface of the ring 23 is
closely to the outer peripheral surface of the valve stem 18.

In the configuration described above, the pressure of the exhaust gas acts on the bushing 20, pushing it upwards as seen in FIG.
The bracket 22 and the annular surface around the counterbore 21 of the bush 20 are brought into pressure contact to prevent gas leakage. Further, the ring 23 is pressed against the bracket 22 by the pressure of the exhaust gas entering the counterbore portion 21 from around the second valve shaft 18, thereby preventing gas leakage from this portion. When the butterfly valve 3 moves upward as seen in FIG. 2 under the pressure of the exhaust gas and reaches the amount of movement _S1 , the large diameter part of the second valve stem 18 to which the butterfly valve 3 is attached pushes up the bush 20, so The sealing effect becomes greater. Also, butterfly valve 3
When the valve stem 18 returns downward by S1 by closing the ring ₂₃ , which is pressed against the valve stem 18,
returns by _S0 , which is a smaller gap than _S1 , and the ring 23 comes into close contact with the surface of the counterbore 21, so that the sealing function is not impaired even when the exhaust gas pressure to the ring 23 is reduced.

As is clear from the above, in this invention, the bush is housed in the body in such a way that it will not crack due to thermal deformation of the exhaust gas, and the bush can be brought into close contact with the bracket by the pressure of the exhaust gas, resulting in a greater sealing effect. Further, since the self-contracting ring of the counterbore of the bushing comes into pressure contact with the surface of the bracket or the counterbore, gas leakage along the valve stem is prevented and the sealing effect is improved.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of an exhaust brake system including an embodiment of this invention, and FIG. 2 is a sectional view of an exhaust brake device according to an example of this invention. In the figure, 3... butterfly valve, 13... body, 20... valve stem, 21... counterbore, 22...
Bracket, 23...Ring.

Claims (1)

[Scope of utility model registration request] A hollow body provided in an exhaust passage, a pair of valve shafts pivotally supported by the body, a butterfly valve supported by the valve shaft and rotatably disposed within the body, and the valve shaft and the body. a self-contracting ring that is slidably arranged in the axial direction in a counterbore provided on the outer end surface of one of the bushes; and a bush having the counterbore portion, and a bracket that comes into close contact with the outer end surface of the body, and has a large diameter portion where the valve shaft comes into contact with the inner end surface of the bush due to movement of the valve shaft in its axial direction. An exhaust brake device characterized by: