JPS5982526A - Supercharger for internal-combustion engine - Google Patents

Abstract

PURPOSE:To control the supplied gas pressure according to the operation state of an engine by installing each bypass passage onto the turbine and compressor for a supercharger on the high-pressure stage side and installing each bypass valve for varying flow-rate onto the turbine, compressor, and the both bypass passages. CONSTITUTION:During the intermediate and the low speed operation of an engine, bypass valves 6 and 7 are perfectly closed, and bypass valves 8 and 9 are perfectly opened, and two-stage supercharging is executed in which the exhaust gas discharged from the engine drives the turbine 3b of a high-pressure stage exhaust turbosupercharger 3 and the turbine 2b of a low-pressure stage exhaust turbosupercharger 2. In high-speed operation, the bypass valves 6 and 7 are opened perfectly, and the bypass valves 8 and 9 are perfectly closed, and only the low-pressure stage exhaust turbosupercharger 2 is driven. When an exhaust brake is operated, all the bypass valves are perfectly closed, and the compressor 3a, turbine 3b of the high-pressure exhaust turbosupercharger 3 and the both bypass passages 4 and 5 are closed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a supercharging device for an internal combustion engine used as an automobile engine or the like.

For internal combustion engines such as the 48 engine for automobiles, which are required to be compact and lightweight, high output, and low fuel consumption, it is effective to improve the combustion conditions by adding an exhaust turbo supercharger.

However, within a wide operating rotation range and load range like an automobile engine? Simply combining an exhaust turbocharger with an engine does not necessarily result in good engine operability.

That is, if the supercharger is matched in the high speed range with emphasis on the maximum output of machine 1, the torque and acceleration performance in the medium and low speed range where turbine efficiency decreases will decrease, resulting in deterioration of drivability.

On the other hand, if the turbocharger is matched in the mid-to-low speed range with emphasis on torque and acceleration in the mid-to-low speed range, the boost pressure in the high-speed range will become excessive, which will have a negative impact on engine durability and noise. At the same time, there was an inconvenience in that excess air in the private room became excessively large, increasing the engine's pumping loss and deteriorating the fuel consumption rate.

On the other hand, there is also a two-stage supercharging system in which two exhaust turbo superchargers are connected in series in order to improve the recovery rate of exhaust energy of the engine, but this two-stage supercharging system is also similar to the above case. The drawback was that similar characteristics were observed.

The present invention has been made in view of the above-mentioned circumstances.
The main exhaust turbo superchargers are connected in series to perform so-called two-stage supercharging, and the turbine and compressor of the first pressure stage (FIl+ supercharger are connected to an exhaust bypass passage and an air intake bypass passage, respectively). By providing a bypass valve that variably controls the flow rates of the turbine, compressor, and both bypass paths, the operating pattern of the supercharger can be changed according to the operating state of the engine. The aim is to optimally control the boost pressure in response to the engine's engine output performance, acceleration performance, fuel consumption rate, etc.

The present invention will be explained in detail below based on an illustrated embodiment.

In the intake passage of the engine 1 mounted on a car (not shown),
A low-pressure stage exhaust turbo supercharger 2 that pressurizes air taken in through an air cleaner (not shown). The compressor 3a of the high pressure stage exhaust turbo supercharger 3 is interposed between the turbine 2b of the low pressure stage exhaust turbo supercharger 2 and the exhaust manifold of the engine 1. Feeder 3
By interposing the turbine 3b, a so-called two-stage supercharging device is constructed.

Further, the inlet and outlet of the compressor 3a and turbine 3b of the high-pressure exhaust turbocharger 3 are connected via a sheath air bypass passage 4 and an exhaust bypass passage 5, respectively. Bypass valves 6 and 7 are provided at the upper and lower ends of the bypass passages 4 and 5, respectively, for variably controlling the bypass flow rate by adjusting the opening degree of the bypass passages 4 and 5, respectively. The part downstream from the branching point with both bypass passages 4 and 5 and the part upstream from the junction with both bypass passages 4 and 5, i.e., the compressor 3a and the turbine 3b.
By providing t1 bypass valves 8.9 at the inlet and outlet portions of the t1 bypass valves 8.9, the opening degrees of these bypass valves 8.9 can be adjusted to adjust the flow rates of the compressor 3a and the turbine 3b. 10 is an intercooler installed at the compressor inlet of the high-pressure stage exhaust turbo supercharger 3; 11 (
1-1 is an aftercooler installed at the downstream end of the air supply passage, for example, at the connection between the air supply passage and the air supply manifold, and each of the bypass valves 6, 7, 8.9 The controller to which operating information (rotational speed, load, etc.) is input is configured to perform the Open JM NL'111 adjustment.

In the above configuration, 111 from each sensor (not shown)
When it is determined that the engine is operating in a medium-low speed range based on the engine power signal (engine operating information), the bypass valves 6 and 7 provided in the air supply bypass path 4 and the exhaust bypass path 5 are fully closed. At the same time, the bypass valves 8 and 9 provided at the inlet and outlet portions of the compressor 3a and turbine 3b of the high-pressure stage exhaust turbo supercharger 3 are respectively kept fully open. Therefore, at this time, the exhaust gas of the engine l drives the turbine 3b of the high-pressure stage exhaust turbo supercharger 3 and then the turbine 2b of the low-pressure stage exhaust turbo supercharger 2, so that the conventionally known two-stage supercharging is performed. It is done.

Also, when it is determined that the engine 1 is being operated at high speed based on the above-mentioned operating status information, the bypass valves 6 and 7 of each bypass path 4.511411 are held fully open by a command from the controller, and at the same time Stage a1 air turbo: +1φ feeder 3
Bypasses 8.9 provided at the inlet and outlet portions of the compressor 3a and turbine 3b are kept fully closed. Then +1
The exhaust gas discharged from the engine 1 bypasses the turbine 3b of the high-pressure exhaust turbocharger 3 and is directly supplied to the turbine 2b of the low-pressure exhaust turbocharger 2. Only feeder 2 is driven i'L. For this,
Even if the exhaust energy increases in the high-speed operating range of the engine 1, excessive boost pressure and temperature rise are suppressed, and the engine 1 can be operated efficiently with little surplus air leakage.

On the other hand, when there is a necessary intake that blocks both the supply and exhaust passages, such as when the exhaust brake is activated, all the bypass valves 6, 7,
8. Operate 9 fully.

Then, the compressor 3a, turbine 3b, and both bypass passages 4.5 of the 1f71 pressure stage exhaust turbo supercharger 3 are blocked, cutting off the supply and exhaust, so an independent exhaust brake valve, noise suppressor, etc. are provided as in the past. The need disappears.

Incidentally, in the above embodiment, the bypass valve is only operated by switching between fully open and completely open, but the opening degree of the bypass valve is adjusted in multiple stages or steplessly to control the bypass passages 4, 5 and the compressor 3a. , turbine 3b, etc. may be finely and variably controlled to optimally control the supply air pressure, etc., and the operating state of the engine may be controlled in addition to the rotation speed and load to determine the supply air pressure, supply air temperature, It is desirable to make a comprehensive judgment based on exhaust pressure, exhaust temperature, fluctuations in rotational peak and load, engine temperature, supercharger rotation speed, etc.

As explained above, according to the present invention, the low pressure stage 1. A high-pressure stage exhaust turbo that constitutes a two-stage supercharging device together with a gas turbo supercharger]! A bypass passage is provided for each of the compressor and turbine of the feeder, and a bypass valve is provided to variably control the flow rate (opening degree) of the compressor, turbine, and both bypass passages. Controls engine output by controlling opening and closing to optimally control supply pressure.
Acceleration performance, fuel consumption rate, etc. can be improved.

[Brief explanation of drawings]

The figure shows an embodiment of the present invention. 1. Engine 2. Low-pressure stage exhaust turbocharger 2a
...Compressor 2b...Turbine 3...High pressure stage exhaust turbo supercharger 3a...Compressor 3b middle turbine 4...Air supply bypass path 5...Exhaust bypass path 6, 7.8.
9...Bypass valve. Patent applicant Hino Motors Co., Ltd. 149

Claims (1)

[Claims] A low pressure stage exhaust turbo supercharger that pressurizes air taken in through an air cleaner, and a high pressure stage exhaust turbo supercharger that further pressurizes the air pressurized by the supercharger and sends it to the engine, The turbine of the high pressure stage exhaust turbo supercharger is interposed between the exhaust manifold of the engine and the turbine inlet of the low pressure stage exhaust turbo supercharger, and the inlet and outlet of the compressor and turbine of the high pressure stage exhaust turbo supercharger are connected. An internal combustion engine characterized by being provided with a bypass valve that is connected to each other via an air supply bypass passage and an exhaust bypass passage, and that variably controls the compressor and turbine of a high-pressure stage exhaust turbo supercharger, and the flow rates of both of the bypass passages. Supercharging@place.