JPS646328B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides at least one compressor for supplying fresh compressed air to an engine, and at least one compressor operated by exhaust gases from the engine to drive said compressor. The present invention relates to an internal combustion engine that is supercharged by a single turbocompressor device consisting of a turbine.

In such engines, it is common to have a direct and permanent bypass passage which allows fresh air supercharged by the compressor to be delivered to the exhaust gas side coming from the engine. Additionally, a combustion chamber is generally provided upstream of the turbine and is supplied with exhaust gas and fresh air taken in from the above-mentioned shunt pipe.

It is an object of the present invention to significantly reduce the amount of work required to scavenge engine exhaust gases, thereby increasing engine power and reducing fuel consumption.

Another object of the invention is to adapt the turbo-compressor to high boost pressures by operating the compressor close to the limits of its discharge characteristics, in other words by operating it at optimum conditions. .

Still another object of the present invention is to improve engine scavenging by creating a pressure difference between the intake side and the exhaust side of the engine.

According to the present invention, a compressor for supplying compressed air to the engine, a turbine operated by exhaust gas from the engine, a compressed air passage between the engine and the compressor, and an exhaust gas passage between the engine and the turbine are connected in parallel with the engine. In a supercharged internal combustion engine including a bypass passage, there is provided a method of operation, characterized in that a pressure difference is generated between an upstream part and a downstream part of the bypass passage, which is an increasing function of the pressure in the upstream part. Ru.

Further, according to the present invention, a compressor for supplying compressed air to the engine, a turbine operated by exhaust gas from the engine, a compressed air passage between the engine and the compressor, and an exhaust gas passage between the engine and the turbine are connected in parallel with the engine. In a supercharged internal combustion engine, a throttle valve is movably provided in the bypass passage and receives pressure on the compressor side on one side and receives pressure on the turbine side on the other side; A supercharged internal combustion engine is provided, further comprising a compressed air flow rate control device comprising means for biasing the throttle valve in a valve closing direction based on a pressure difference between a pressure on the compressor side and a predetermined pressure. This creates a pressure difference between the upstream part of the bypass passage (the part connected to the compressor) and the downstream part of the bypass passage (the part connected to the turbine, if required, via the combustion chamber), which It is desirable that the upstream pressure of the passage be linear, that is, a linear increasing function.

In the present invention, as the pressure P of air entering the intake manifold of the engine (hereinafter referred to as boost pressure) increases, the pressure difference ΔP between the upstream and downstream portions of the bypass passage increases. In other words, the throttle is closed, and the downstream pressure, that is, the pressure of exhaust gas in the exhaust manifold of the engine (hereinafter referred to as exhaust pressure) is relatively reduced.

Conversely, if the boost pressure P is low, the above △
P becomes smaller.

Therefore, if the boost pressure is the same, the increase in exhaust pressure can be reduced compared to the conventional system.

Thus, lower exhaust pressure means less work is done by the engine's pistons to expel the exhaust gases into the exhaust manifold, which increases the engine's power output, in other words: This means improved engine efficiency.

Furthermore, it is possible to operate the compressor close to the limits of the pump characteristic curve and operate the engine at high boost pressures. The engine can easily remove exhaust gas because of the pressure difference maintained between the intake port (pressure upstream of the throttle valve) and the exhaust port (pressure downstream of the throttle valve).
Embodiments of the present invention will be described with reference to the accompanying drawings.

The diesel engine shown in FIG. 1 is designated by the reference numeral 101 and is supercharged by a turbo compressor unit designated by the reference numeral 102.

This turbo compressor device 102 includes a compressor 103 that supplies compressed air to the engine via a pipe, and a turbine 10 that drives the compressor 103 via a shaft 105.
This turbine 104 is operated by exhaust gas from the engine 101.

A bypass passage 106 of the direct and permanent passage through which the fresh air taken in via the compressor 103 passes to the exhaust gas side originating from the engine.
is provided.

A combustion chamber 107 is preferably provided upstream of the turbine 104 and is supplied with exhaust gases and fresh compressed air taken from the bypass passage 106.

According to the invention, a throttle valve 108 with a variable outlet cross section is provided, and a bypass passage 106 is provided.
It is constructed so that the air coming in from the This throttle valve 108 is connected to the upstream part of the bypass passage 106 (the part connected to the compressor 103) and the downstream part of the bypass passage 106 (the part connected to the combustion chamber 103).
7)
A pressure difference ΔP is created between the This pressure difference ΔP
is preferably an increasing function of the upstream pressure, that is, a linear or nearly linear increasing function.

This linear function can be written as ΔP=α′P+β′.

Here, α' and β' represent two constants.

In the first embodiment of the invention shown in FIG.
It consists of a valve 108a disposed in the valve 108a and a fixed seat 108e cooperating with the valve 108a.

The valve 108a is supported by a stem 108b, the end of which is fixed to a balance piston 108c and connected to the bypass passage 106 via a deformable wall 108d.

Diameter of valve 108a and balance piston 108c
The diameter of the valve 108a is determined by the upstream pressure P applied to the upstream surface and the inner surface of the piston 108c, the downstream pressure P-ΔP applied to the downstream surface, and the atmospheric pressure applied to the outer surface of the piston 108c. The size is such that it can be balanced depending on the

An elastic biasing device also acts on the throttle member 108a to maintain a constant value of the function ΔP=α'P+β'.

This elastic biasing device includes a spring 109 and/or
Alternatively, it is constructed by the elasticity itself of the deformable wall 108d.

In order to vary this coefficient β', it is necessary to adjust the force applied by the elastic biasing device to the valve 108a. This adjustment device can be constructed by a nut 110 that changes the tension of the elastic biasing device. This feature is particularly advantageous since it allows the pressure difference created by valve 108 to be adapted to the supercharged engine characteristics.

In particular, this pressure difference is used to eliminate load losses caused by a filtration device 111 located at the inlet of the compressor 103 and/or by a muffler 112 located at the outlet of the turbine 104. I can do things.

A second embodiment of the present invention will be described with reference to FIG. 2. The throttle valve has a cylindrical housing 11 located on the upstream side of the bypass passage (compressor side).
12 and the downstream side (turbine side) 13. The valve 15 fixed to the stem 14 has a fixed valve seat 16
In cooperation with this, a fluid passage 17 of variable cross section is formed. The central portion of the mandrel 14 is slidably supported by a support 18, and the end portion is connected to a hydraulic damper 19. Furthermore, the mandrel 14 is hollow and open at 20, allowing compressed air to enter inside. Therefore, the valve 15 receives the pressure P-ΔP on the downstream side (turbine side) of the bypass passage on one surface, and receives the pressure P on the upstream side (compressor side) on the other surface. On the other hand, the mandrel 14 receives the pressure P of the internal compressed air and at the same time receives the pressure within the chamber 21 at its end surface. The hydraulic damper 19 is connected to a hydraulic power source 22, serves as an elastic biasing member, and absorbs shocks caused by fluctuations in the flow rate of compressed air. Further, the pressure inside the chamber 21 can also be adjusted using compressed air or the like.

Further, the present invention does not require any physical linkage between the operation of the throttle valve and the auxiliary combustor.

Therefore, in the present invention, even when the engine speed decreases, the boost pressure can be increased in response to the load (ie, torque) on the engine.

In such a case, according to the invention, ΔP increases and the valve closes according to the above relationship: ΔP−kP=P ^* .

Also, if both engine speed and load drop simultaneously, the throttle valve opens.

The throttle valve, which is a feature of the present invention, operates only when boost pressure increases and decreases, regardless of engine load and/or speed. Therefore, the relationship between engine load and speed can be any of the following combinations: Low speed - low load (low torque) Low speed - high load (high torque) High speed - low load (low torque) High speed - high load (High torque) For example, when a truck is traveling on a flat road and suddenly climbs up a hill, the engine speed decreases due to the increase in load, but in the present invention, the valve is closed and the engine is boosted. As pressure P increases, pressure difference ΔP
can be made larger.

Additionally, the present valves can be balanced independently of engine speed and/or load and are physically linked to components that respond to output shaft speed, load fluctuations, engine fuel consumption, etc. There's no need to do it.

Furthermore, when the boost pressure P is low, the above ΔP/
If P becomes high, the turbine inlet temperature T will become extremely high, causing damage to the turbine, which is extremely undesirable. In the present invention, when the boost pressure P is low, the value of ΔP/P can be made small so as not to be as close as possible to the allowable range T _L of the turbine inlet temperature T.

The throttle valve of the present invention can control any internal combustion engine (diesel engine, spark ignition type internal combustion engine).

A case will be described in which the present invention is applied to an engine controlled by a speed governor. That is, when the engine is required to accelerate to a certain speed depending on the operating conditions, the governor is adjusted to increase the amount of fuel injected per unit stroke into the diesel engine until the number of revolutions per unit time increases. . Then, when the desired speed is reached, the governor is operated to reduce fuel injection to an amount sufficient to maintain the speed.

On the other hand, depending on the load at this speed, the boost pressure increased by the turbo compressor driven by the turbine acts on the balanced piston according to the invention, and the relation according to the invention: ΔP=αP−β is achieved. The opening degree of the throttle valve changes until the

The device having the above configuration according to the present invention has the following effects: Generally, for thermal reasons such as preventing overheating of an engine, it is necessary to improve scavenging air when the engine output is high, that is, when the boost pressure is high.
This is extremely important, especially in the case of two-stroke engines. Also, many 4-stroke engines have to maintain exhaust valve temperatures below permissible values, especially at high outputs.
At the end of the expansion stroke, it is highly desirable to have better scavenging to better expel the exhaust gases from the cylinder.

On the other hand, during low power operation, the boost pressure is low,
Furthermore, since there is no thermal problem mentioned above, there is no need for strong scavenging. Furthermore, it is preferable that the scavenging air becomes poor and the gas circulation becomes slow, from the viewpoint of improving combustion.

Generally, as the discharge pressure P of the compressor increases, the above ΔP increases, so the pressure on the inlet side of the turbine decreases (P-ΔP). However, during low output operation when the compressor discharge pressure P is low,
This ΔP must be minimized. Naturally, if this pressure difference ΔP is abnormally large, there is a risk that the turbine inlet temperature will rise abnormally, resulting in damage to both the turbine and the engine.

In other words, when viewed from the turbine side, the above pressure difference ΔP must correspond to the boost pressure P.

In the case of the present invention, the relationship between the pressure difference ΔP and the boost pressure P is a linear function: ΔP−k(P−P ^* ), that is, ΔP−kP=P ^* ) (P ^* is the reference pressure). Because it is a traditional place, there is no danger mentioned above.

Although the present invention has been described above using Examples, it is obvious that the technical scope of the present invention is not limited to those Examples.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a supercharged internal combustion engine according to the present invention, and FIG. 2 is a schematic diagram of a flow rate control device for a supercharged internal combustion engine of the present invention according to another embodiment. 101...Engine, 103...Compressor, 104...Turbine, 106...Bypass passage, 107...Combustion chamber, 108...Throttle valve, 108a, 15...Valve, 108b, 14...
...Mandrel, 109,19...Elastic biasing device.

Claims (1)

[Claims] 1. A compressor that sends compressed air to an engine;
A method for operating a supercharged internal combustion engine including a turbine operated by exhaust gas from the engine, and a bypass passage connecting a compressed air passage between the engine and a compressor and an exhaust gas passage between the engine and the turbine in parallel with the engine, An operating method characterized in that a pressure difference is constantly generated between an upstream part and a downstream part of the bypass passage, which is a linear increasing function of the pressure in the upstream part. 2 A compressor that sends compressed air to the engine,
A supercharged internal combustion engine that includes a turbine operated by exhaust gas from the engine, and a bypass passage that connects a compressed air passage between the engine and a compressor and an exhaust gas passage between the engine and the turbine in parallel with the engine. It is movably installed inside and receives pressure from the compressor side on one side.
A compressed air flow control device comprising a throttle valve that receives pressure from the turbine side on the other side, and means for biasing the throttle valve in the valve closing direction based on the differential pressure between the pressure on the compressor side and a predetermined pressure in the bypass passage. A supercharged internal combustion engine further comprising: