JPH08270465A - Exhaust brake device - Google Patents

Abstract

PURPOSE: To provide an exhaust brake device simplified in by-pass passage constitution. CONSTITUTION: An exhaust shutter 2 is interposed in the exhaust passage 4 of an engine, and a pressure reducing valve 11 with the pressure receiving face 13a is provided facing an exhaust passage 4 near the shutter 2, where exhaust pressure on the upper reaches side acts when the exhaust shutter 2 is closed in the case of closing the exhaust shutter 2 at the speed reducing time. When the pressure reducing valve 11 is opened, a clearance for making exhaust flow is formed between the pressure receiving face 13a and the exhaust shutter 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle exhaust brake device.

[0002]

2. Description of the Related Art In a vehicle equipped with a diesel engine, there is known an exhaust brake device which has a shutter provided in an exhaust passage of the engine and closes the shutter at the time of deceleration so as to increase exhaust pressure and apply engine braking. There is.

If the average exhaust gas pressure when the exhaust brake is applied becomes too high, such as during deceleration from the high engine speed range, the exhaust valve, which is not in the exhaust stroke, acts as back pressure, causing a pulsating change in exhaust pressure. It receives and opens and closes, and the impact when seated reduces the durability of the exhaust valve and causes problems such as damage.

Therefore, in the prior art, for example, actual Kaihei 3-1715.
As disclosed in Japanese Patent No. 4 and Japanese Utility Model Laid-Open No. 2-126050, a shutter for the exhaust passage is bypassed to provide a passage, a relief valve is provided in the bypass passage, and the exhaust pressure reaches an allowable upper limit during exhaust braking. There is a device in which the relief valve is opened when it reaches the limit, and further increase of the exhaust pressure is suppressed to prevent malfunction of the exhaust valve.

[0005]

However, in the case of relief of such exhaust pressure, a bypass passage is provided in parallel with the exhaust passage, and a relief valve is provided in this bypass passage, so that the exhaust passage is constructed. Will be complicated, and it will lead to cost increase as well as space problems.

Therefore, an object of the present invention is to provide an exhaust brake device having a simplified bypass passage structure.

[0007]

According to a first aspect of the present invention, there is provided an exhaust brake device in which an exhaust shutter is provided in an exhaust passage of an engine so that the exhaust shutter is closed at the time of deceleration. A pressure reducing valve having a pressure receiving surface is provided facing the exhaust passage near the shutter where the side exhaust pressure acts, and when the pressure reducing valve opens, a gap is created between the pressure receiving surface and the exhaust shutter to allow the exhaust gas to flow. I chose

In a second aspect based on the first aspect, the gap is formed so as to increase as the displacement of the pressure reducing valve increases.

In a third aspect based on the first or second aspect, the pressure reducing valve slidably supports the piston valve in the housing, and a part of the pressure receiving surface of the piston valve is exhausted at the exhaust shutter closed position. Face the upstream side of the passage, and urge this piston valve with a spring toward the exhaust shutter,
A locking step is provided on the cylinder so that the piston valve can be locked at a position close to the flat surface formed at the exhaust shutter rotation tip, and when the piston valve opens against the spring, it becomes a flat surface of the exhaust shutter. It is configured so that a gap is formed between them.

In a fourth aspect based on the first or second aspect, the pressure reducing valve slidably supports a piston valve in a housing formed integrally with a shutter body coaxially with a rotation axis of an exhaust shutter. , A part of the pressure receiving surface of the piston valve coaxially inserted through the rotary shaft is exposed to the upstream side of the exhaust passage at the exhaust shutter closing position, and the piston valve is biased by a spring toward the exhaust shutter, A locking step is provided on the rotating shaft so that the valve is locked at a position close to the flat surface formed on the exhaust shutter rotation side surface, and when the piston valve opens against the spring, the exhaust shutter flat surface is provided. It is configured so that a gap is formed between them.

[0011]

In the first aspect of the invention, when the exhaust shutter is closed during deceleration of the engine, the pressure in the exhaust passage increases and the exhaust brake works. However, when the exhaust pressure applied to the pressure receiving surface of the pressure reducing valve reaches the allowable upper limit value during exhaust braking from high rotation, the pressure reducing valve retracts from the exhaust passage, and a gap is formed between the exhaust shutter and the pressure receiving surface. It

Exhaust gas flows from the upstream side to the downstream side of the exhaust shutter via this gap, which suppresses an increase in exhaust pressure and reliably prevents the behavior of the exhaust valve from becoming unstable.

According to the second aspect of the invention, after the pressure reducing valve is opened, the area of the gap is increased in accordance with the amount of displacement, and the exhaust pressure is reliably maintained within the allowable limit.

According to the third aspect of the invention, the piston valve located at the rotating tip of the exhaust shutter senses the exhaust pressure and retracts, thereby forming a gap for flowing exhaust gas between the exhaust valve and the flat surface of the rotating tip of the exhaust shutter. Therefore, it is possible to suppress an abnormal increase in exhaust pressure.

In the fourth aspect of the invention, the piston valve arranged coaxially with the rotation axis of the exhaust shutter detects the exhaust pressure and moves backward, thereby forming a gap between the exhaust valve and the flat surface on the side of the exhaust shutter. This makes it possible to suppress an abnormal rise in exhaust pressure.

[0016]

1 to 4 show a first embodiment of the present invention, in which reference numeral 1 denotes a shutter body which constitutes a part of an exhaust pipe, and an exhaust shutter 2 faces an exhaust passage 4 thereof. Rotating shaft 3
It can be freely attached by. The exhaust shutter 2 is driven by an actuator (not shown), and closes the exhaust passage 4 to increase exhaust pressure when the engine is decelerating, thereby exerting engine braking.

When the exhaust pressure at the time of exhaust braking reaches the upper limit, a pressure reducing valve 11 that bypasses the exhaust shutter 2 and flows a part of the exhaust gas from the upstream side to the downstream side is located near the front end of the rotation of the shutter 2. Then, it is attached to a part of the shutter body 1.

The pressure reducing valve 11 has a cylindrical housing 12 mounted via bolts 17 so as to be orthogonal to the axis of the shutter body 1, and a cylindrical piston valve 13 is also slidably inserted therein. 13 is a spring 14
As a result, the housing 12 is biased toward the flat surface 5 formed at the turning front end of the exhaust shutter 2 at the valve closed position and is prevented from advancing at the position immediately before the contact with the flat surface 5. The piston valve 13 is locked to the locking step portion 16 formed in.

The pressure receiving surface 13a at the tip of the piston valve 13 is
At the position where the exhaust shutter 2 is closed, the exhaust passage 2 is provided so as to partially face the exhaust passage 4 on the upstream side of the shutter 2. When the exhaust pressure reaches a predetermined upper limit value, it retreats against the spring 14 to receive the pressure receiving surface. A gap 18 is formed between 13a and the flat surface 5 of the exhaust shutter 2 so that a part of the exhaust gas flows downstream.

The piston valve 13 is provided on the upstream side of the exhaust passage with respect to the pivoting tip of the shutter 2 so that the pressure receiving area on the upstream side of the exhaust shutter 2 with respect to the exhaust pressure is as large as possible. Further, near the tip of the piston valve 13, a flange portion 12a is formed in the housing 12 on the upstream side of the exhaust passage to suppress the radial force applied to the piston valve 13 due to the exhaust pressure, prevent the piston valve 13 from galling, and smooth the valve. Guaranteed operability.

With the above construction, the operation will be described below.

When the exhaust shutter 2 is closed as shown in FIG. 1 during deceleration of the engine, the exhaust pressure flowing through the exhaust passage 4 rises, and the engine brake works accordingly.

When the exhaust pressure upstream of the exhaust shutter 2 reaches the allowable upper limit value, such as during deceleration from the high engine speed range,
The upstream exhaust pressure acting on the pressure receiving surface 13a of the piston valve 13 of the pressure reducing valve 11 causes the piston valve 13 to retreat against the spring 14.

As a result, the pressure receiving surface 13 of the piston valve 13
A gap 18 is formed between a and the flat surface 5 of the exhaust shutter 2, and a part of the exhaust gas flows downstream through this gap 18.
For this reason, as shown in FIG. 5, it is possible to prevent the exhaust pressure on the upstream side of the exhaust shutter 2 from increasing, and to reliably prevent the behavior of the exhaust valve from becoming unstable due to an abnormal increase in the exhaust pressure.

By providing the pressure reducing valve 11 and controlling the upper limit of the exhaust pressure in this way, the exhaust shutter 2 can be operated in the normal engine rotation range until the pressure reducing valve 11 is opened.
The clearance can be reduced, and as a result, the effect of the exhaust brake can be enhanced in the low engine speed range (indicated by the shaded area), as is apparent from comparison with the conventional example.

Further, when the pressure reducing valve 11 is opened, a gap 18 for releasing the exhaust gas is formed between the flat surface 5 of the rotating tip of the exhaust shutter 2 and the pressure receiving surface 13a of the piston valve 13, so that the conventional structure is used. As described above, it is not necessary to provide the exhaust bypass passage separately from the shutter body 1. Therefore, the exhaust passage structure can be remarkably simplified, and the mounting of the exhaust bypass passage can also be performed by the housing 12.
Since it is simply attached to the shutter body 1, it is very simple and the maintainability such as maintenance and inspection is good.

Next, a second embodiment shown in FIGS. 6 to 8 will be described.

In this embodiment, the pressure reducing valve 11 is arranged coaxially with the rotary shaft 3 of the exhaust shutter 2, and the housing 21 formed integrally with the shutter body 1 has a piston valve 23 slidably interposed therein. The piston valve 23 is arranged so as to pass through the rotary shaft 3, its pressure receiving surface 23a faces the flat surface 6 provided on the side surface of the shutter 2, and the position of the pressure receiving surface 23a is formed on the rotary shaft 3. It is regulated by the stop 25. The piston valve 23 is biased toward the exhaust shutter 2 by the spring 24, a part of the pressure receiving surface 23a faces the upstream side of the exhaust shutter 2, and retreats when the exhaust pressure reaches an allowable upper limit value, Pressure receiving surface 23a and flat surface 6
A gap 26 through which exhaust gas flows is formed between and.

Also in this embodiment, when the exhaust pressure reaches the allowable upper limit value with the exhaust shutter 2 closed, the piston valve 23 retracts to form the gap 26, and a part of the exhaust gas is exhausted from the exhaust shutter 2. It escapes from upstream to downstream, and suppresses further increase in exhaust pressure. In this case, the housing 2
1 is formed integrally with the shutter body 1 coaxially with the rotating shaft 3 of the exhaust shutter 2, so that the number of parts can be reduced, and the piston valve 13 and the spring 24 can be assembled together with the exhaust shutter 2, The property is also improved.

[0030]

According to the first aspect of the invention, in the exhaust brake device in which the shutter is provided in the exhaust passage of the engine and the shutter is closed at the time of deceleration, the exhaust pressure on the upstream side acts when the shutter is closed. A pressure reducing valve having a pressure receiving surface is provided facing the exhaust passage near the shutter, and when the pressure reducing valve opens, a gap is created between the pressure receiving surface and the shutter to allow exhaust gas to flow. Such,
When the exhaust pressure on the pressure receiving surface of the pressure reducing valve reaches the allowable upper limit value, the pressure reducing valve retracts from the exhaust passage, and a gap is formed between the shutter and the pressure receiving surface. The exhaust gas is controlled to prevent the exhaust valve from becoming unstable by suppressing the increase of the exhaust gas pressure, while the exhaust gas escapes through the gap between the shutter and the pressure receiving surface.
Unlike the conventional case, it is not necessary to separately provide an exhaust bypass passage, the structure of the exhaust passage can be remarkably simplified, and the cost can be reduced together with the reduction of the number of parts.

According to the second aspect of the invention, since the gap is formed so as to increase as the displacement of the pressure reducing valve increases, the area of the gap also increases according to the displacement amount when the valve is opened, and the exhaust pressure is increased. Can be reliably maintained within acceptable limits.

According to the third aspect of the invention, the pressure reducing valve slidably supports the piston valve in the housing, and a part of the pressure receiving surface of the piston valve faces the upstream side of the exhaust passage at the shutter closing position. The piston valve is biased toward the shutter by a spring, and a locking step is provided on the cylinder so that the piston valve is locked at a position close to a flat surface formed at the shutter rotation tip. Since a gap is formed between the flat surface of the shutter and the shutter when it is opened against the spring, it is possible to reliably open the piston valve when the pressure rises abnormally during exhaust braking and suppress the pressure rise. Also, the pressure reducing valve can be mounted simply by mounting the housing in which the piston valve and the spring are installed in advance to the shutter body, which makes the assembly very simple and makes maintenance such as maintenance and inspection easy. The good.

According to the fourth invention, the pressure reducing valve slidably supports the piston valve in a housing formed integrally with the shutter body coaxially with the rotation shaft of the exhaust shutter, and coaxially with the rotation shaft. A part of the pressure receiving surface of the inserted piston valve faces the upstream side of the exhaust passage at the shutter closed position, and this piston valve is biased toward the shutter by a spring, and the piston valve is formed on the shutter rotation side surface. Locking step is provided on the rotary shaft so that it can be locked at a position close to the flat surface, and a gap is formed between the piston valve and the flat surface of the shutter when the piston valve opens against the spring. Therefore, the piston valve arranged coaxially with the rotation axis of the shutter can detect an exhaust pressure and move backward to suppress an abnormal increase in the exhaust pressure. By body of, the cost can be reduced by reducing the number of parts, the number of assembling steps.

[Brief description of drawings]

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

FIG. 2 is a view similarly showing the AA line arrow.

FIG. 3 is a view similarly showing the BB line arrow.

FIG. 4 is a partially omitted sectional view showing the operating state of the same.

FIG. 5 is an explanatory diagram showing characteristics of exhaust pressure at the time of exhaust braking.

FIG. 6 is a sectional view showing a second embodiment.

FIG. 7 is a sectional view in which a portion thereof is also enlarged.

FIG. 8 is a sectional view showing the operating state of the same.

[Explanation of symbols]

 1 Shutter body 2 Exhaust shutter 3 Rotating shaft 4 Exhaust passage 5 Flat surface 6 Flat surface 11 Pressure reducing valve 12 Housing 13 Piston valve 13a Pressure receiving surface 14 Spring 16 Locking step part 18 Gap 21 Housing 13 Piston valve 25 Locking step part 26 Gap

Claims (4)

[Claims] 1. An exhaust brake device in which an exhaust shutter is provided in an exhaust passage of an engine so that the exhaust shutter is closed at the time of deceleration, in the vicinity of the shutter where upstream exhaust pressure acts when the exhaust shutter is closed. An exhaust brake device characterized in that a pressure reducing valve having a pressure receiving surface facing the exhaust passage is provided, and when the pressure reducing valve is opened, a gap for allowing exhaust gas to flow is formed between the pressure receiving surface and the exhaust shutter. . 2. The exhaust brake device according to claim 1, wherein the gap is formed so as to increase as the displacement of the pressure reducing valve increases. 3. The pressure reducing valve slidably supports a piston valve in a housing, a part of a pressure receiving surface of the piston valve is exposed to an upstream side of an exhaust passage at an exhaust shutter closing position, and the piston valve is a spring. Urging the exhaust valve toward the exhaust shutter, the cylinder is provided with a locking step so that the piston valve can be locked at a position close to the flat surface formed on the exhaust shutter rotation tip, and the piston valve resists the spring. The exhaust brake device according to claim 1 or 2, wherein a gap is formed between the exhaust shutter and the flat surface of the exhaust shutter when opened. 4. The pressure reducing valve includes a housing formed integrally with a shutter body coaxially with a rotary shaft of an exhaust shutter, the piston valve slidably supported on the housing, and the piston valve coaxially inserted through the rotary shaft. A part of the pressure receiving surface faces the upstream side of the exhaust passage at the exhaust shutter closed position, and the piston valve is biased toward the exhaust shutter by a spring, and the piston valve is made flat on the exhaust shutter rotating side surface. A locking step portion is provided on the rotary shaft so as to be locked at a position close to each other, and a gap is formed between the piston valve and the flat surface of the exhaust shutter when the piston valve opens against the spring. The exhaust brake device according to claim 1.