JPH0343403Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a supercharged engine that compresses and supplies air to the engine.

As is well known in the art, supercharged engines have a problem in that when the charge air is compressed by the supercharger, the temperature of the intake air inevitably increases, which hinders improvement in charging efficiency. Therefore, in order to further improve the charging efficiency of the engine by cooling the compressed air discharged from the supercharger, intercoolers are often used in supercharged engines for vehicles. An intercooler generally has a structure similar to a radiator that cools engine cooling water.
This system circulates supercharged air inside a large number of heat exchange tubes with heat radiating fins, and cools the supercharged air by the traveling air flowing outside the heat exchange tubes, but the structure is complicated, expensive, and This has the disadvantage that it occupies a large space in a narrow engine compartment, and furthermore, the cooling capacity fluctuates significantly depending on the vehicle's running speed. On the other hand, as another method to lower the temperature of supercharged air and improve charging efficiency, a method has already been proposed in which water is injected into the supercharged air and the air temperature is lowered by vaporization. In a supercharged vehicle engine whose rotational speed fluctuates widely, it is by no means easy to inject just the right amount of water depending on the operating condition of the engine. When it happens,
This is extremely dangerous, as it may cause rust in various parts, poor lubrication due to dilution of lubricating oil, and abnormal wear of engine components due to this.

The present invention was devised in view of the above, and includes a supercharger that compresses and supplies air to the engine, a compressed air passage that guides the compressed air discharged from the supercharger to the air supply pipe of the engine, and a A water injection device disposed in a compressed air passage and injecting water in an amount that increases or decreases depending on the temperature of the compressed air, and a water injection device disposed in the compressed air passage downstream of the water injection device to separate unevaporated moisture. A steam/water separator that removes the air to the outside of the passage, a dew condensation sensor that detects the relative humidity of the compressed air provided in the compressed air passage on the downstream side of the steam/water separator, and a relative humidity detected by the dew condensation sensor. The gist of the invention is a supercharged engine characterized in that it is equipped with a water injection operation stop device that stops the operation of the water injection device when the water injection device exceeds a certain value.

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The reference numeral 10 in the figure generally indicates a vehicle engine, and the engine includes an exhaust pipe 12 and an intake pipe 14. Reference numeral 16 denotes a supercharger comprising an exhaust gas turbine 18 connected to the exhaust pipe 12 and driven by the exhaust gas of the engine 10, and a compressor 20 directly connected to and driven by the exhaust gas turbine. The compressor 20 compresses the outside air taken in through the air cleaner 22 and supplies the compressed air to the air supply pipe 14 through the compressed air passage 24. 26 is a water injection nozzle provided in the compressed air passage 24, and is a water injection nozzle provided in the water tank 2.
Water stored in the tank 8 is supplied via an electromagnetic water pump 30, an electromagnetic switching valve 32, and a temperature sensing water supply valve 34, while compressed air for promoting atomization of water is supplied to an air tank 36 and a filter. 38, an electromagnetic switching valve 40 and a pressure regulating valve 42. Reference numeral 44 denotes a steam/water separation device provided downstream of the water injection nozzle 26 in the compressed air passage 24, and in the illustrated embodiment, a part of the pipe constituting the compressed air passage 24 is separated and separated by a distance d. It has a simple structure in which the tubes are spaced apart by a distance of 1.5 mm, preferably the diameter of the upstream tube is slightly larger than that of the downstream tube, and a casing 44b is provided to surround the outer periphery of the spaced apart portion 44a. Reference numeral 46 is a trap for receiving unevaporated water accumulated in the casing 44b of the steam/water separator, and the water collected in the trap is collected in the water tank 28. 48 is the above-mentioned steam/water separation device 4
A temperature-sensitive sensor provided in the compressed air passage 24 on the downstream side of 4, for example, a temperature-sensitive wax,
It is composed of temperature-responsive elements such as bimetal,
When the temperature of the compressed air is high, the temperature sensing water supply valve 34 is opened to increase the amount of water to be injected, and when the temperature of the compressed air is low, the opening degree of the water supply valve 34 is reduced to reduce the amount of water to be injected. 34. Similarly, 50 is a dew condensation sensor installed in the compressed air passage 24 on the downstream side of the steam/water separator 44, and is used to detect relative humidity.
When it reaches 94% or more, a switching action is performed to energize the coil 52a of the normally closed first relay 52, and open the relay contact 52b inserted into the energizing circuit of the electromagnetic switching valves 32 and 40. It is set up like this. A switch 54 corresponds to the load of the engine 10, that is, the accelerator opening, and is closed when the accelerator opening is set in advance, for example, 75% or more, and energizes the coil 56a of the second relay 56. It is provided to close a relay contact 56b inserted into the energizing circuit of the electromagnetic switching valves 32 and 40. 58 is an in-vehicle power supply, such as a battery, 60
is a well-known relief valve installed in the injection water supply circuit.

In the above configuration, while the engine 10 is operating, the exhaust gas is supplied to the exhaust turbine 18 of the supercharger 16 to drive the compressor 20, which compresses the outside air sucked in through the air filter 22 and fills the compressed air passage 24. The supercharged air is fed under pressure to the engine's intake pipe 14 to supply supercharging air to the engine 10. In this case, the temperature of the supply air inevitably increases due to the adiabatic compression performed within the compressor 20, which impedes the effect of supercharging on the engine 10, in other words, the improvement of charging efficiency.
It is preferable to cool the discharged compressed air and supply it to the engine. Now, when the driver of the vehicle depresses the accelerator pedal according to the engine load and the accelerator opening exceeds 75%, the accelerator switch 54 is closed and the relay coil 56a of the second relay 56 is closed.
is energized and relay contact 56b is closed. On the other hand, the relative humidity of the supercharged air flowing inside the compressed air passage 24 is
When the condition is 94% or less and there is no risk of condensation, the contact 52b of the first relay 52 is closed, so the power supply 58
From electromagnetic switching valves 32, 40 and electromagnetic water pump 3
0, the switching valves 32 and 40 are opened, and at the same time, the water pump 30 starts operating. water tank 2
8 is pumped by the water pump 30 to the water injection nozzle 26 via the switching valve 32 and the temperature sensing water supply valve 34, and at the same time, the compressed air in the air tank 36 is pumped through the filter 38, the switching valve 40, and the pressure regulating valve 42. The water that has been effectively atomized by the compressed air is injected into the compressed air passage 24, mixes with the compressed air, that is, the supercharged air, and evaporates to form the supercharged air. to cool down. At this time, temperature sensor 4
8 detects the temperature of the supercharged air, and when the temperature is high, the opening of the water supply valve 34 is increased, and when the temperature is low, the opening of the water supply valve 34 is decreased, so that the relative humidity remains approximately constant. The amount of water injected is controlled so that Further, unevaporated water injected from the water injection nozzle 26 is captured by the steam/water separator 44 and returned to the water tank 28, so that water droplets are brought into the engine 10 and each There is no possibility of rusting of the components or dilution of the lubricating oil, resulting in poor lubrication and abnormal wear due to this.
Furthermore, a dew condensation sensor 50 is provided downstream of the steam/water separator 44, and the relative humidity of the supercharged air is 94°C.
% or more and there is a risk of condensation, the relay 52 opens its contact 52b, so the switching valves 32 and 40 are closed and water injection is stopped. As a result, water droplets due to condensation in the supercharging air pipe downstream of the steam separation device 44 are removed from the engine 1.
0 is reliably prevented. In addition, in the low load operating range of the engine 10, the merit of water injection is small, so in the above embodiment, the accelerator switch 54 is set so that water injection is performed only when the accelerator opening is 75% or more. This set load can be changed arbitrarily, and the accelerator switch 54 and the second relay 56 can be omitted in some cases. This device has a simpler structure and is less expensive than conventional intercoolers, and does not have the problem of large fluctuations in cooling capacity depending on running speed. Furthermore, water tank 2
8 is advantageous because it does not need to be installed in a narrow engine room, and the installation space can be easily obtained in another location where space constraints are small.
In addition, water injection not only lowers the temperature of the supply air to a level similar to or even higher than that of an intercooler and improves charging efficiency, but also the presence of water vapor in the supply air reduces the amount of harmful components in the exhaust gas. There is an additional benefit in that NO _X generation is suppressed and fuel efficiency can be improved by suppressing NO _X generation.

As mentioned above, the supercharged engine according to the present invention,
A supercharger that compresses the air supplied to the engine and supplies it to the engine, a compressed air passage that guides the compressed air discharged from the supercharger to the engine air supply pipe, and a compressed air passage installed in the compressed air passage that controls the temperature of the compressed air. a water injection device that injects an amount of water that increases or decreases depending on the water injection device; a steam-water separation device that is installed in a compressed air passage downstream of the water injection device and separates unevaporated water and removes it from the passage;
A dew condensation sensor is provided in the compressed air passage on the downstream side of the steam/water separation device to detect the relative humidity of the compressed air, and when the relative humidity detected by the dew condensation sensor exceeds a set value, the water injection device is activated. The present invention is characterized by being equipped with a water injection operation stop device that stops the operation, and has a simple and inexpensive configuration to effectively cool supercharged air, improve engine filling efficiency, and improve its performance. It is extremely advantageous because it allows

[Brief explanation of the drawing]

The accompanying drawing is a schematic diagram showing an embodiment of the present invention. 10...Engine, 16...Supercharger, 24...
Compressed air passage, 26... Water injection nozzle, 30...
Water pump, 34...temperature detection water supply valve, 44...steam/water separator, 48...temperature sensor, 50...condensation sensor.

Claims (1)

[Scope of utility model registration request] A supercharger that compresses the intake air of the engine and supplies it to the engine, a compressed air passage that guides the compressed air discharged from the supercharger to the engine air intake pipe, and a compressed air passage that is arranged in the compressed air passage and changes the temperature of the compressed air. a water injection device that injects an amount of water that increases or decreases depending on the water injection device; a steam-water separation device that is installed in a compressed air passage on the downstream side of the water injection device and separates unevaporated moisture and removes it from the passage; a dew condensation sensor that detects the relative humidity of the compressed air provided in the compressed air passage on the downstream side of the separation device, and stops the operation of the water injection device when the relative humidity detected by the dew condensation sensor exceeds a set value. A supercharged engine characterized by being equipped with a water injection operation stop device.