JPH02176118A - Diesel engine - Google Patents

Abstract

PURPOSE:To suppress the NOx concentration in the exhaust gas within the preset allowable concentration range throughout the year by providing a humidifier capable of adjusting the humidification quantity on an intake pipeline system. CONSTITUTION:A humidifier 7 is provided on an intake pipe 2 on the downstream side of an air cooler 6. A controller 9 receives the detected signals from an absolute humidity sensor 8 and a rack scale sensor 4 and calculates the humidification quantity based on the detected signal of the former and the reference absolute humidity when the engine output indicated by the detected signal of the latter becomes the preset value or above and outputs it to the humidifier 7. The humidifier 7 flow-controls the water droplets atomized by a flow control valve opened or closed in proportion to the signal indicating the humidification quantity inputted from the controller 9 and feeds it to the intake pipe 2. The absolute humidity of the intake air is kept at the reference absolute humidity throughout the year, thus the nitrogen oxide concentration in the exhaust gas is controlled within the allowable range throughout the year.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a diesel engine capable of controlling the concentration of nitrogen oxides in the exhaust gas, which increases and decreases as the supply air becomes dry and wet due to seasonal changes in the absolute humidity of the atmosphere.

<Prior Art> Generally, the absolute humidity of the atmosphere changes seasonally throughout the year as shown in the lower half of Figure 6, being high in the summer and low in the winter. Diesel engines breathe in the atmosphere and burn fuel to obtain power, so the concentration of nitrogen oxide NOX in the exhaust changes as the supply air becomes dry and humid, as shown in the upper half of Figure 6. It changes seasonally, becoming lower in the winter and higher in the winter.

Now, in August, when the absolute humidity of the atmosphere is
Suppose that the diesel engine is adjusted so that the oxia degree reaches the regulation value c, and the allowable concentration range of NOx in the exhaust is c′
±△C, the corresponding absolute humidity cycle of the supply air is X*±
If △X, then NOx exceeding the permissible concentration will be emitted from the operating diesel engine from October when the absolute humidity of the atmosphere reaches XX to June of the following year. Additionally, if such adjustments are made at the time of shipment of the diesel engine, the absolute humidity will change seasonally in various patterns different from those shown in Figure 6 depending on the installation location of the shipped diesel engine, and the allowable concentration of NOx will change depending on the installation location of the shipped diesel engine. Since the range differs from place to place, it is not possible to achieve the NOX emission standards required at each installation site unless the diesel engine is readjusted on site.

Conventionally, on-site reconditioning of diesel engines has been carried out in the following manner. This method involves measuring seasonal changes in the absolute humidity of the atmosphere at the site (see the lower half of Figure 6) and adjusting the diesel engine so that the Noxa degree in the exhaust gas falls between the allowable upper limit C*+ and below C.

In this method, if the fuel injection timing is delayed, NOx in the exhaust gas will be reduced.
Utilizing the characteristic that the concentration decreases in proportion to the delay angle (see the upper half of Figure 7), the sixth
This is a method of suppressing the emissions of the portion exceeding the allowable limit value c8+ΔC of the Noxa degree in the exhaust gas, which increases and decreases as shown in the upper half of the figure, by delaying the fuel injection timing.

<Problems to be Solved by the Invention> However, in the above conventional method, the fuel injection timing is delayed in order to reduce the NOX concentration in the exhaust gas, so the fuel consumption rate be
On the contrary, it increases and worsens as shown in the lower half of Figure 7, and NOx a
The fuel consumption rate be to maintain the temperature control bell at the regulation value C* in Figure 6 throughout the year is as shown in Figure 8, and the winter fuel consumption rate is the best summer fuel consumption rate be'. The downside is that it is considerably worse than it is. In addition, this method requires adjustment of the engine each time based on seasonal changes in NOX due to air supply conditions, so readjustment is time-consuming.
In winter, the engine may not start.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to appropriately humidify supply air that becomes dry and humid due to seasonal changes in the absolute humidity of the atmosphere, thereby eliminating the need for complex engine adjustments on site and reducing engine fuel consumption. Nox in the exhaust without any negative effects
It is an object of the present invention to provide a diesel engine capable of suppressing a degree of concentration within a predetermined permissible concentration range throughout the year.

<Means for Solving the Problems> In order to achieve the above object, the diesel engine of the present invention has the following features:
This is a device that can control the concentration of nitrogen oxides in the exhaust gas, which increases and decreases as the supply air becomes dry and moist due to seasonal changes in the absolute humidity of the atmosphere in the installation environment. The present invention includes a humidifier capable of adjusting the amount of humidification that humidifies the atmosphere to a reference absolute humidity that brings the concentration of nitrogen oxides in the exhaust gas into a predetermined allowable concentration range.

The humidifier may be activated by a control device that receives a detection signal from an output sensor of the diesel engine when the engine output exceeds a predetermined set value. Further, the humidifier may be one in which the amount of humidification is adjusted based on a detection signal from an absolute humidity detection means for detecting the absolute humidity of the atmosphere.

Furthermore, the amount of humidification is calculated based on the detection signal from the absolute humidity detection means for detecting the popular absolute humidity and the reference absolute humidity, and a signal representing this amount of humidification is output to the humidifier. It may be something you do. In addition, the control device calculates the amount of humidification based on the meteorological data on the absolute humidity of the atmosphere in the installation environment manually inputted in advance and the reference absolute humidity, and outputs a signal representing this humidification to the humidifier. It can also be used as something to do.

A humidifier installed in the air supply piping system of a diesel engine heats the inhaled air to a standard absolute temperature of 79 degrees, which brings the concentration of nitrogen oxides in the exhaust gas within a predetermined permissible range. Humidify by adjusting the amount of humidification according to seasonal changes in humidity. As a result, the absolute humidity of the supply air becomes the reference absolute humidity throughout the year, and the concentration of nitrogen oxides in the exhaust gas is controlled within the above-mentioned allowable range throughout the year.

Note that if the humidifier is operated by the control device when the engine output exceeds a predetermined set value, the adverse effect of excessive moisture on the engine at low output can be prevented. In addition, if the humidification amount of the humidifier is adjusted based on the detection signal from the atmospheric absolute humidity detection means, the nitrogen oxide concentration can be constantly maintained even if seasonal changes in the atmospheric absolute humidity in the installation environment are not known in advance. Be able to control.

Further, the control device calculates the amount of humidification based on the detection signal from the absolute humidity detection means and the reference absolute humidity,
By outputting a signal representing the amount of humidification to the humidifier, the nitrogen oxide concentration can be controlled fully automatically. In addition, the amount of humidification is calculated based on the meteorological data on the absolute humidity of the atmosphere in the installation environment manually entered in advance by the 1-1 control device and the above reference absolute humidity, and this humidification Q-Hk is expressed by the humidification signal. By outputting to a device, the nitrogen oxide concentration can be controlled without the need for atmospheric absolute humidity detection means.

<Example> The present invention will now be described in detail with reference to illustrated embodiments.

FIG. 1 is a schematic diagram showing an embodiment of a diesel engine according to the present invention, where l is an engine body equipped with an intake pipe 2 and an exhaust pipe 3, and 4 is an output for detecting the displacement of the fuel rack of this engine body l. a rack scale sensor as a sensor; 5 a supercharger having a compressor 5a disposed at the inlet of the air supply pipe 2; and a turbine 5b connected to the compressor disposed at the exhaust pipe outlet;
6 is an air cooler installed in the air supply pipe 2 on the downstream side of this supercharger 5, and 7 is installed in the air supply pipe 2 on the downstream side of this air cooler 6, and 7 is installed in the air supply pipe 2 on the downstream side of this air cooler 6, and 7 is installed in the air supply pipe 2 on the downstream side of this air cooler 6. This is a humidifier that can adjust the amount of humidification that humidifies to absolute humidity so that the NOx humidity falls within a predetermined permissible range.

Further, 8 is an absolute humidity sensor that detects the absolute humidity of the atmosphere near the inlet of the air supply pipe 2, and 9 is a sensor that receives detection signals from this absolute humidity sensor 8 and the rack scale sensor 4, and a table of the latter detection signals. When the engine output exceeds a predetermined set value, the amount of humidification is calculated based on the fore-sound detection signal and the absolute humidity, and the signal representing this humidification rGlffi is sent to the humidifier along with the activation signal. This is a control device consisting of a computer that outputs output to 7.

The humidifier 7 uses exhaust gas from the exhaust pipe 3, steam sent through a cock from a boiler heated by an electric heater or an external boiler, water droplets atomized by an ultrasonic generator, or water jet. The flow rate of the atomized water droplets is controlled by a flow control valve that opens and closes in proportion to a signal representing the amount of humidification manually inputted from the control device 9 to the air supply pipe 2.
There is no shortage of supplies.

On the other hand, the control device 9 has a program for calculating a value K that governs NOx 6 degrees in exhaust gas defined by the following function, and is designed to perform calculations as shown in FIG.

K −= K (x, T b, γ", y) ・
・(1) Where, As shown in FIG. 2, the control device 9 determines the initial setting value K using equation (1) using the above-mentioned variable values xo, Tbo, and γfa+Yo at the time of shipping adjustment of the engine. If you calculate this (see S1), this K.

The target value Ks during operation is calculated by dividing the product of the value and the regulation value C6* of NoxfilK at the time of shipping adjustment by the regulation value C* of NOx'a degree during operation. Next, K(x,
Calculate the standard absolute humidity X* that makes Tb, 7', y) the target value Ks, and subtract the atmospheric absolute humidity X detected by the absolute humidity sensor 8 during operation from this value
(See 3). Further, the engine output I7 detected by the rack scale sensor 4 is set to the set value. When determining whether or not the above is true, and determining that L≧Lo and 'l', l+, calculate the amount of humidification Y required to bring the NOx concentration in the exhaust to the regulation value cx, based on the above subtraction result X*-X. (see S4 for details), and outputs a control signal representing this addition UfflY to the flow rate control valve of the humidifier 7 (S4).
(see 5). The absolute humidity difference (x'-X) and the humidification amount Y have a proportional relationship as shown in FIG. 3, and this relational expression is given to the control device 9 in advance.

The operation of the humidifying device for a diesel engine having the above configuration is as follows.

Prior to the operation of the diesel engine, the control device 9 receives the supply air humidity X at the time of shipping adjustment. , supply air temperature Tbo, fuel specific gravity γr
o, Fuel N included *ff1yo, Noxa degree regulation value C88
and the regulation value C* of NOX concentration during operation, as well as the condition value Tb during operation.

γf and y are manually calculated. When the operation starts, a detection signal representing the engine output from the rack scale sensor 4 and a detection signal representing the absolute humidity X of the atmosphere from the absolute humidity sensor 8 are input to the control device 9. In accordance with the flowchart of FIG. 2 already mentioned, the control device 9 determines the value K at the time of shipment j, ;l in step St based on the human data. After calculating the target value Ks during operation in step S2, the reference absolute humidity X is calculated based on the target value Ks and the input condition value in step S3.
* is calculated, and the difference between this and the absolute humidity X of the atmosphere is determined. Furthermore, when it is determined in step S4 that the engine output 17 is greater than or equal to the set value 1-o, the absolute humidity difference (X
XX) necessary addition/! Find 1ilfft Y,
A signal representing this is output to the flow control valve of the humidifier 7 in step S5.

In this way, when the actually measured atmospheric absolute humidity X falls below the reference absolute humidity X'X shown in the lower half of Figure 6, the difference
) is supplied from the humidifier 7 to the air supply pipe 2, suppressing the increase in NOx concentration in the exhaust gas that would exceed the regulation value C shown in the upper half of Figure 6, and reducing the concentration of NOx in the exhaust gas. The NOX concentration is always controlled to be below the above-mentioned regulation value of 0 lines. Note that the operation of such a humidifying device usually involves errors such as some time delay, or even in that case, the NOX concentration in the exhaust gas, which is about to increase, exceeds the regulation value c shown in Fig. 6, 4-2. The concentration should be kept within the range of ΔC centered on wood, that is, within the permissible concentration range. This range also indicates the absolute humidity of the atmosphere -4
In the graph in the lower half of FIG. 6, this corresponds to a range of ΔX centered on the reference absolute humidity XX.

FIG. 4 shows an example of the humidification 1y by the humidifying device and the temporal change in the engine output. In FIG. 4(b), time 1. The diesel engine starts and the engine output reaches time t.
, Teshi. When the humidifier reaches 6N Y, the humidifier 7 starts operating according to the control signal from the control device 9 as shown in Fig. 4(a), and the humidification increases gradually as the engine output increases until the engine output reaches the rated value. Then, the amount of addition t becomes constant. Then, at the same time as the engine stop signal is issued, the humidification i1 sharply decreases to 0, while the engine output sharply decreases, and the engine completely stops at time L3.

In the above embodiment, the control device 9 is configured by a computer with a program for calculating the value K that governs the NOx concentration, and this control device receives the detection signal (x
) and the target value Ks during operation to calculate the reference absolute humidity (
Since the humidification amount Y is calculated based on the amount of humidification Y based on Of course, there is no deterioration in fuel efficiency (see figure), and there is no need for the time-consuming on-site readjustment of the engine as in conventional methods, and the NOx concentration is constantly maintained within the allowable concentration range C to C Be able to hold it down and live a certain life. In addition, humidification is performed only when the engine output 7, which is indicated by the detection signal from the rack sensor 4, reaches the set value. In the above embodiment, the absolute humidity sensor 8 was used as the absolute humidity detection means, and the rack scale sensor 4 was used as the engine output sensor, but for example, the former could be combined with a temperature sensor and a relative humidity sensor. Toshi, the rear stand 71
! Current, voltage? It can also be used as an output sensor for IT force, etc.

FIG. 5 shows another embodiment of the diesel engine of the present invention. In this embodiment, the absolute humidity sensor 8 of the embodiment shown in FIG. 1 is omitted, and instead of this, the graph in the lower half of FIG. It stores weather data such as: That is, the control device 19, instead of the output value X of the absolute humidity sensor in step S3 of FIG.
The same arithmetic processing as described in FIG. 2 is performed using the absolute humidity data value corresponding to the month of operation of the stored weather data. Therefore, by the humidifier 7 controlled by this control device 19, the absolute humidity of the supply air is adjusted within the range of xx±△X shown in the lower half of Fig. 6, and the NOx concentration in the exhaust air is always maintained at c mainland △C.
controlled within an acceptable range.

In the above embodiment, since the control device 19 is pre-stored with meteorological data regarding the absolute humidity of the atmosphere in the environment where the engine is installed, NOx in the exhaust gas and 9 degrees Celsius can be constantly controlled within the permissible range even without an absolute humidity sensor. In addition to this, there are 111 points that can be used in a wide range of installation environments, which vary depending on the purpose of the engine, simply by replacing weather data. Further, as in the above-mentioned embodiment, there is no deterioration in fuel efficiency, no on-site readjustment of the engine is required, and the NOx concentration can of course be controlled fully automatically.

Hereinafter, the present invention has been described with reference to two embodiments, but the absolute humidity sensor 8 of the embodiment shown in FIG. Worth it. When the above conditions occur, the control device 9 outputs a start signal to the humidifier 7, and the opening degree of the steam flow control valve of the humidifier 7 is manually adjusted according to the absolute humidity of the atmosphere during the month of operation. . If we do this, it will be possible to suppress the NOx concentration in the exhaust gas to within the permissible concentration range with a simple and inexpensive groove structure without deteriorating fuel efficiency or readjusting the engine on site. It is possible to prevent negative effects on the engine such as combustion delay due to excess moisture in the engine by +1 = -4''.
Humidification by the humidifier 7 does not necessarily have to start when the absolute humidity X of the atmosphere falls below the reference absolute humidity It is sufficient that X becomes approximately X1'-△X. Furthermore, the control device 9 of the embodiment of FIG. Humidifier 7 that can omit the output sensor 4, add, and adjust 9 m
This achieves the essential functions and effects of the present invention.

It goes without saying that the present invention is not limited to the illustrated embodiment.

<Effects of the Invention> As is clear from the following J2-1 explanation, the diesel engine of the present invention has an air supply piping system that sucks air that becomes dry and humid with seasonal changes in absolute humidity at the installation site. Equipped with an adjustable humidifier that humidifies the atmosphere to the standard absolute humidity that keeps the concentration of nitrogen oxides (NOx) in the exhaust gas within a predetermined permissible concentration range, it eliminates the need for conventional fuel injection timing. Noxit in exhaust gas can be removed without deterioration of fuel efficiency or time-consuming on-site engine readjustment like controlling NOx concentration.
It is possible to control the degree A at all times within the permissible concentration range, and it is possible to significantly ease restrictions on the installation location due to diesel engine exhaust gas regulations.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment of the diesel engine of the present invention, FIG. 2 is a flowchart showing the operation of the humidifying device of the above embodiment, and FIG. 3 is a graph showing the relationship between the absolute humidity difference and the humidifier. FIG. 4 is a diagram showing an example of the temporal change in engine output during humidification 6 by the humidifying device, FIG. 5 is a schematic diagram showing another embodiment of the present invention, and FIG. 6 is a diagram showing seasonal changes in atmospheric absolute humidity. Figure 7 shows the relationship between the fuel injection timing, NOx concentration in the air, and fuel efficiency, and Figure 8 shows the relationship between the fuel injection timing and the NOx concentration in the exhaust gas. FIG. 3 is a diagram showing changes in fuel consumption rate when the NOX degree in exhaust gas is maintained at a constant regulation value throughout the year through adjustment. l...Engine body, 2...Air supply pipe, 3...Exhaust pipe, 4...Rack scale sensor, 5...Supercharger, 6...
- Air cooler, 7. Humidifier, 8... Absolute humidity sensor, 9.19... Control device. Patent applicant: Daihatsu Diesel Co., Ltd. Representative Patent attorney: Mr. Ao and one other person Figure 6 (eye)

Claims (5)

[Claims] (1) A diesel engine that can control the concentration of nitrogen oxides in the exhaust gas, which increases or decreases as the supply air becomes dry or wet due to seasonal changes in the absolute humidity of the atmosphere in the installation environment, and that is installed in the supply air piping system of this diesel engine. , a diesel engine equipped with a humidifier that can adjust the amount of humidification that humidifies the inhaled air to a standard absolute humidity that brings the concentration of nitrogen oxides in the exhaust gas to a predetermined permissible concentration range. (2) In the diesel engine according to claim 1, the humidifier is operated by a control device that receives a detection signal from an output sensor of the diesel engine when the engine output exceeds a predetermined set value. . (3) In the diesel engine according to claim 1 or 2, the humidifier is adapted to adjust the amount of humidification based on a detection signal from an absolute humidity detection means for detecting the absolute humidity of the atmosphere. institution. (4) In the diesel engine according to claim 2, the control device calculates the amount of humidification based on the reference absolute humidity and a detection signal from an absolute humidity detection means for detecting at least the absolute humidity of the atmosphere, and calculates the amount of humidification based on the reference absolute humidity. A diesel engine that outputs a signal representing the amount to the humidifier. (5) In the diesel engine according to claim 2, the control device calculates the amount of humidification based on meteorological data regarding the absolute humidity of the atmosphere in the installation environment inputted in advance and the reference absolute humidity, and calculates the amount of humidification. A diesel engine that outputs a signal representing the above to the humidifier.