JPS6218667Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exhaust brake force control device for an internal combustion engine with an exhaust turbo supercharger, in which an exhaust bypass device prevents the opening of an exhaust valve when the exhaust brake is activated.

Exhaust brake devices in conventional internal combustion engines are
An exhaust brake valve such as a butterfly valve is installed in a part of the exhaust pipe to provide braking by blocking the outflow of exhaust gas during the exhaust stroke, but the exhaust gas discharged by the piston is The backflow overcomes the mounting load of the exhaust valve springs of the exhaust valves of other cylinders that are communicated with each other through the pipe, and as a result, the pressure inside the exhaust pipe is maintained at a substantially constant pressure.

However, when the exhaust valve is pushed open in this way, not only does the backflow of exhaust gas cause a loud blowback sound toward the intake pipe, but when the backflow ends, the exhaust valve strongly hits the valve seat, causing damage to the exhaust valve and its valve train. This caused a strong impact and caused a major problem in terms of the reliability of the exhaust valve and its valve train.

In order to solve this problem, the pressure inside the exhaust pipe must not be increased above the mounting load of the valve spring of the exhaust valve.

On the other hand, in an internal combustion engine equipped with an exhaust turbo supercharger, the boost pressure from the supercharger: the exhaust gas that bypasses part of the exhaust gas flowing into the turbine to prevent the boost pressure from increasing. It is known to provide bypass devices.

The purpose of the present invention is to use the above-mentioned exhaust bypass device as an exhaust pipe internal pressure suppressing device during exhaust braking, so that it not only functions as an exhaust bypass device but also functions as an exhaust pressure suppressing device during exhaust braking. This aims to eliminate the backflow of exhaust gas toward the engine side, prevent impact on the exhaust valve, improve the reliability of the exhaust valve and its valve train, and improve the exhaust braking force as much as possible. It is something.

The present invention achieves the above object by providing a bypass passage with a bypass valve that bypasses the turbine and the exhaust brake in the exhaust passage in which the turbine of the supercharger and the exhaust brake valve are provided, and in which the bypass valve is provided with a bypass valve on the opening side. A diaphragm to which boost pressure acts and a valve spring to act on the valve closing side are provided, and the mounting load W of this valve spring is
_E and the exhaust pressure P _EX just before the exhaust valve is opened by the exhaust pressure during the exhaust brake, W _E = A _D × P _BX
+A _B × P _EO , P _EX ≧ W _E /A _B (where, P _BX : boost pressure when opening the bypass valve, P _EO :
The exhaust pressure when the boost pressure is P _BX , A _B is the pressure receiving area of the bypass valve, and A _D is the pressure receiving area of the diaphragm).

Embodiments of the present invention will be described below with reference to the drawings.

1 is a turbine driven by the exhaust gas of the internal combustion engine; 2 is a compressor driven by the turbine 1; the turbine 1 and the compressor 2 constitute an exhaust turbo supercharger 3; 4 is a cylinder head.

A piston 5 is located at the bottom of the cylinder head 4.
A cylinder liner 6 is provided for reciprocating the cylinder head 4 up and down, while an exhaust pipe 8 is attached to an exhaust port 7 in the cylinder head 4, and an intake pipe 10 is attached to an intake port 9. Also,
The exhaust pipe 8 has a turbine 1 of an exhaust turbo supercharger 3.
However, a compressor 2 is attached to the intake pipe 10.

The intake port 9 is provided with an intake valve 12 having an intake valve spring 11, and the exhaust port 7 is provided with an exhaust valve 14 having an exhaust valve spring 13.

Further, an exhaust brake valve 15 is provided in the exhaust pipe 8 downstream of the turbine 1, and constitutes an exhaust brake device that can be opened and closed by a cylinder 16 or other suitable means. Further, the exhaust pipe 8 is provided with a bypass passage 17 that bypasses the upstream side of the turbine 1 and the downstream side of the exhaust brake valve 15. This bypass passage 17 is opened and closed by a bypass valve 18 controlled by an exhaust bypass device 19, which is indicated by an arrow P _B from the compressor 2 of the exhaust turbo supercharger 3. A diaphragm 20 on which the boost pressure acts and a valve spring 2 which acts to close this bypass valve 18.
1, usually a diaphragm 20
When the boost pressure acting on the valve spring 21 exceeds the mounting load of the valve spring 21, the bypass valve 18 opens, and part of the exhaust gas bypasses the turbine 1 (and the exhaust brake valve 15) as shown by the arrow and is discharged via the bypass passage 17. do.

Further, when the exhaust brake device is activated, the exhaust brake valve 15 closes the exhaust pipe 8, and the exhaust brake valve 15 closes the exhaust pipe 8.
The pressure inside the exhaust valve ₁ increases, and the pressure inside the exhaust _valve 1 increases.
When an attempt is made to exceed the mounting load W _V of the exhaust valve spring 13 of No. 4, the bypass valve 18 is opened against the valve spring 21 by the pressure P _E in the exhaust pipe 8 acting on the bypass valve 18, and the exhaust gas The exhaust brake valve 15
It is designed to be bypassed downstream.

That is, P _BX is the boost pressure when the bypass valve 18 is opened, P _EO is the exhaust pressure when the boost pressure P _BX is generated, and P _EX is the exhaust pressure immediately before the exhaust pressure opens the exhaust valve 14 during exhaust braking. year,
Furthermore, if the pressure-receiving area of the bypass valve 18 is A _B , the pressure-receiving area of the diaphragm 20 is A _D , and the mounting load of the valve spring 21 is W _E , then W _E =A _D ×P _BX +A _B ×P _EO holds true, In addition, each specification is set so that P _EX ≧W _E /A _B holds true.

That is, the predetermined boost pressure state in the operating state of the exhaust turbo supercharger 3 and the exhaust brake valve 15
When the exhaust brake is activated when closed, the exhaust valve 14
The bypass valve 18 is set to open when the exhaust pressure is slightly lower than the limit exhaust pressure at which the bypass valve 18 is opened.

By setting each specification as in the above formula, the exhaust bypass device acts on the exhaust bypass device during normal operation of the supercharger in the same way as before, and when the exhaust brake device is activated, it acts on the exhaust valve 14 immediately before it opens. bypass the exhaust gas. As a result, it is possible to prevent an excessive rise in boost pressure, which improves the durability of the engine, and it also prevents the exhaust valve from opening, which is the case in the past, and prevents the exhaust valve and its movement, which occurs when the exhaust valve strongly hits the valve seat. This has the advantage that damage to the valve devices is eliminated, their reliability is improved, and the problem of blowback noise to the intake side due to backflow is also eliminated. Moreover, by simply taking into account the above considerations during engine design, the present invention can be applied and its effects can be obtained without any increase in the number of parts.

In the above embodiment, the bypass valve was set to open immediately before the exhaust valve was opened by exhaust pressure during exhaust braking, but if safety is a priority, each specification may be set so that it opens at a pressure lower than this. may be set.

[Brief explanation of the drawing]

The drawing is a longitudinal sectional view showing the main parts around the cylinder head of an internal combustion engine with an exhaust turbo supercharger according to an embodiment of the present invention. 1... Turbine, 2... Compressor, 3...
Exhaust turbo supercharger, 7...Exhaust port, 8...Exhaust pipe, 14...Exhaust valve, 15...Exhaust brake valve, 17...Bypass path, 18...Bypass valve,
19... Exhaust bypass device, 20... Diaphragm, 21... Valve spring, P _B ... Boost pressure.

Claims (1)

[Scope of utility model registration request] A bypass passage with a bypass valve that bypasses the turbine and the exhaust brake is provided in the exhaust passage where the turbocharger turbine and exhaust brake valve are provided, and a diaphragm and a diaphragm on which boost pressure acts on the valve opening side of the bypass valve and the valve closing side are provided. A valve spring acting on the side is provided, and the mounting load of this valve spring W _E and the exhaust pressure P _EX just before the exhaust valve is opened by the exhaust pressure during exhaust braking.
, W _E = A _D × P _BX + A _B × P _EO , P _EX ≧ W _E /A
Set to _B (where P _BX : boost pressure when opening the bypass valve, P _EO : exhaust pressure when boost pressure is P _BX , A _B : pressure receiving area of the bypass valve, A _D : pressure receiving area of the diaphragm) Exhaust brake control device for internal combustion engine with exhaust turbo supercharger.