JPS6337469Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an exhaust particulate treatment device for an internal combustion engine.

<Conventional technology> In internal combustion engines such as diesel engines,
The exhaust particulates contained in the exhaust gas are collected by a trap to prevent the exhaust particulates from being released into the atmosphere. Such a conventional example is shown in FIG. 3 (see SAE paper 840078, published in 1984).

That is, in the exhaust passage 2 of the engine 1, there is a trap 3 made of ceramic that collects particulates (soot) in the exhaust gas.
is interposed. On the other hand, fuel is supplied to the engine 1 from a fuel tank 4 through a fuel supply passage 6 in which a fuel filter 5 is interposed.

Further, an additive supply passage 7 is connected in the middle of the fuel supply passage 6, and an additive is mixed into the fuel from an additive tank 8 via an electromagnetic flow control valve 9. The opening of the electromagnetic flow control valve 9 is controlled by a drive signal from a control circuit 10 based on engine rotational speed and engine torque, and the additive is supplied into the fuel in an amount commensurate with the amount of fuel consumed by the engine. The additive concentration is controlled to be approximately constant.

Here, the additive is formed by mixing Mn, Cu, Pb, Zn, Ca, Fe, etc. into an organic solvent.

When the additive is mixed into the fuel in this way, the additive is burned in the combustion chamber of the engine 1, and the metal components in the additive are discharged together with the exhaust particles.
When these exhaust particulates are collected in the trap 3, the exhaust particulates are combusted by the action of the metal component at a lower exhaust temperature than when no additive is mixed, and the trap 3 can be regenerated. This eliminates the need for a burner or a heater for heating and burning the exhaust particulates of the trap 3, and also simplifies the need for a burner or heater, thereby making it possible to regenerate the trap 3 from an operating range where the exhaust temperature is low.

A predetermined supercharging pressure is introduced into the additive tank 8 from the exhaust turbocharger 11, and the additive is supplied under pressure to the fuel supply passage 6 at this supercharging pressure. Further, surplus fuel in the engine 1 flows through the fuel return passage 12, passes through the cooling passage 13, is cooled, and is returned to the fuel supply passage 6 again.

<Problems to be solved by the invention> However, in such conventional exhaust particulate treatment devices, the fuel consumption of the engine is calculated from the engine rotation speed and the engine torque. There was an error between the consumption amount and the actual engine fuel consumption amount. For this reason, it is difficult to control the additive concentration in the fuel to be substantially constant, resulting in variations in the additive concentration and variations in trap regeneration performance. As a result, for example, if the additive concentration becomes dilute, the regeneration performance of the trap will decrease and a large amount of exhaust particulates will be collected in the trap 3, leading to an increase in exhaust pressure, and if the additive concentration becomes too high, a large amount of exhaust particulates will be collected in the trap 3. There was a problem that combustion occurred in a short period of time, raising the temperature inside the trap and causing burnout of the trap.

The present invention was developed in view of these circumstances, and is an exhaust particulate treatment device that controls the additive concentration in the fuel with high precision and stabilizes the trap regeneration performance regardless of changes in the amount of fuel supplied to the engine. The purpose is to provide.

<Means for Solving the Problems> For this reason, the present invention provides an additive supply means for supplying fuel supplied to an engine with an additive that promotes combustion of exhaust particulates collected in a trap in an exhaust passage; An additive concentration detection means for detecting the additive concentration in the fuel, and a control means for controlling the additive supply means based on the detected additive concentration are provided.

<Function> By controlling the additive supply means based on the actual additive concentration in the fuel, the additive concentration can be controlled with high precision regardless of changes in the amount of fuel supplied to the engine, thereby reducing the trap. Made playback performance more stable.

<Example> An example of the present invention will be described below with reference to FIGS. 1 and 2. Incidentally, the same elements as those in the conventional example are given the same reference numerals as in FIG. 3, and the explanation thereof will be omitted.

In the figure, a fuel injection pump 21 of an engine 1 is supplied with fuel from a fuel tank 4 via a fuel supply passage 6. Further, a downstream end of an additive supply passage 7 is connected to the middle of the fuel supply passage 6, and the fuel supply passage 6 downstream of the connection part is provided with a concentration detection means for detecting the additive concentration in the fuel. A concentration detector 22 is provided.

As shown in FIG. 2, the concentration detector 22 includes a first transparent case 23 which is interposed in the fuel supply passage 6 and through which the fuel mixed with the additive passes, and a first transparent case 23 which is inserted into the fuel supply passage 6 and through which the fuel mixed with the additive is mixed. A second transparent case 24 enclosing the fuel is provided, and these first transparent cases 24
A light emitting element 25 such as a light emitting diode is provided between the second transparent cases 23 and 24. Further, first and second light receiving elements 26a and 26b such as phototransistors are mounted on the sides of the first and second transparent cases 23 and 24, respectively.
The transparent case 23,
The first and second light receiving elements 26a and 26b generate voltage according to the intensity of light input from the light emitting element 25 passing through the internal space of the light emitting element 24.

The output voltage of the first light receiving element 26a is applied to the non-inverting side terminal of the comparator 28 via the first amplifier 27a, and the output voltage of the second light receiving element 26b is applied to the inverting side terminal of the comparator 28. is applied via the second amplifier 27b. The output signal of the comparator 28 is input to the control device 29. Further, first and second transparent cases 2 are provided on both sides of the light emitting element 25.
The slit member 3 is used to form a slit with a predetermined gap that adjusts the amount of light flowing into the slit members 3 and 24 to be approximately constant.
0a and 30b are provided.

Here, the additive concentration in the fuel sealed in the second transparent case 24 is set to a concentration suitable for regenerating the trap 3.

When the input signal from the comparator 28 becomes "H", the control device 29 outputs a pulse signal with a constant duty ratio to the electromagnetic flow control valve 9, and controls the control valve 9.
It is configured to supply a predetermined amount of additive from the additive tank 8 to the fuel supply passage 6 by controlling ON/OFF. Further, a predetermined voltage is applied from the control device 29 to the light emitting element 25, and the light emitting element 25 is configured to emit light. Here, the additive tank 8 and the flow rate control valve 9 constitute an additive supply means.

Note that 30 in FIG. 1 is a silencer, and 31 in FIG. 2 is a battery power source.

Next, the action will be explained.

When a predetermined voltage is applied to the light emitting element 25 from the control device 29, the light emitting element 25 emits light, and the light passes through the gap between the slit members 30a and 30b, and then passes through the first and second transparent cases 23 and 24. The light is then input to each light receiving element 26a, 26b.

At this time, since fuel mixed with a predetermined concentration of additives is sealed in the second transparent case 24, the intensity of the light passing through the second transparent case 24 is approximately equal to 100% due to light absorption by the additives, etc. Reduced by a certain value. Therefore, the second light receiving element 26b has a second
Since the light having a reduced and substantially constant intensity is input inside the transparent case 24, the second light receiving element 26b generates a substantially constant voltage. This voltage is applied to the second amplifier 2
It is input to the inverting side terminal of the comparator 28 via 7b.

On the other hand, the fuel supplied to the fuel injection pump 21 flows through the first transparent case 23, but due to changes in the concentration of additives mixed into this fuel, the intensity of light input to the first light receiving element 26a changes.
That is, the additive concentration is lower than that of the second transparent case 2.
When the additive concentration is lower than that in 4, the amount of light absorbed by the additive decreases, so the intensity of light input to the first light receiving element 26a increases. Therefore, the output voltage of the light receiving element 26a increases and the output voltage of the comparator 28 increases.
Since the voltage applied to the non-inverting side terminal exceeds the voltage applied to the inverting side terminal from the second light receiving element 26b, the output of the comparator 28 becomes "H".

As a result, a pulse signal with a constant duty ratio is output from the control device 29 to the flow rate control valve 9, and the flow rate control valve 9 is controlled to turn on and off, thereby supplying the additive into the fuel in the fuel supply passage 6.

Therefore, since the additive concentration in the fuel passing through the first transparent case 23 increases, the intensity of light input to the first light receiving element 26a decreases, and the output voltage of the first light receiving element 26a decreases. decreases. and,
When the additive concentration in the fuel passing through the first transparent case 23 becomes higher than the additive concentration in the second transparent case 24, the output voltage of the first light receiving element 26a changes to the output voltage of the second light receiving element 26b. Since the output of the comparator 28 becomes "L", the control device 29 stops outputting the pulse signal to the flow rate control valve 9 and stops adding the additive to the fuel.

By repeating the control of the flow rate control valve 9, the addition and stopping of the additive to the fuel supplied to the engine is repeated, and the concentration of the additive in the fuel passing through the first transparent case 23 increases to the level in the second transparent case 24. The additive concentration is controlled so that the additive concentration is as follows.

As explained above, since the actual additive concentration in the fuel supplied to the engine is directly detected and the additive is supplied to the fuel based on this detected value,
The additive concentration can be controlled with high precision to a substantially constant value regardless of changes in the amount of fuel supplied to the engine. Therefore, since the additive can be supplied to the engine at a substantially constant concentration regardless of the operating state of the engine, the metal component of the additive emitted into the exhaust gas is approximately proportional to the amount of fuel consumed, so the exhaust gas due to the action of the metal component can be The particulate combustion performance can be kept approximately constant regardless of the operating state of the engine. This makes it possible to stabilize the regeneration performance of the trap, and prevent the exhaust pressure from increasing due to a decrease in the regeneration performance of the trap, which has conventionally occurred. In addition, it is possible to suppress a sudden rise in the temperature inside the trap due to excessive concentration of the additive, thereby preventing burnout of the trap 3, and also suppressing the dispersion of metal components into the atmosphere and the consumption of the additive to the necessary minimum.

In this embodiment, the output signal of the control device 29 is a pulse signal with a constant duty ratio, but for example, as the additive concentration in the fuel supplied to the engine approaches a predetermined additive concentration, the flow control valve 9 The duty ratio of the pulse signal may be changed depending on the additive concentration so that the valve opening time is shortened, and in this case, the control accuracy of the additive concentration is improved. A differential amplifier is used instead of the comparator 28 when changing the duty ratio of the pulse signal according to the additive concentration.

<Effects of the invention> As explained above, the present invention supplies additives to the fuel based on the actual additive concentration in the fuel supplied to the engine. The concentration of the additive in the trap can be controlled with high precision, thereby stabilizing the regeneration performance of the trap, preventing an increase in exhaust pressure due to trap clogging, and preventing burnout of the trap due to rapid combustion of exhaust particles. It is possible to suppress consumption and the release of metal components into the atmosphere.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram showing one embodiment of the present invention;
The figure is an enlarged view of the same essential parts as above, and FIG. 3 is a configuration diagram showing a conventional example of an exhaust particulate processing device. 1... Engine, 2... Exhaust passage, 3... Trap, 8... Additive tank, 9... Flow rate control valve, 2
2... Concentration detector, 29... Control device.

Claims (1)

[Scope of utility model registration request] a trap installed in an exhaust passage of an engine to collect particulates in the exhaust; an additive supply means for supplying the engine fuel with an additive that promotes combustion of the exhaust particulates collected in the trap; 1. An exhaust particulate treatment device for an internal combustion engine, comprising: a concentration detection means for detecting an additive concentration; and a control means for controlling the additive supply means based on the detected additive concentration.