JPH0437245B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for regenerating a filter that collects diesel particulate from the exhaust passage of a diesel engine, and in particular, a device for regenerating a filter that collects diesel particulate from the exhaust passage of a diesel engine, and in particular, a device for regenerating a filter that collects diesel particulate from the exhaust passage of a diesel engine. The present invention relates to a diesel particulate filter regeneration device.

Diesel engine exhaust gas contains particulate, a combustible, finely divided carbonized compound, which is the main cause of black smoke in the exhaust gas. This particulate has an exhaust gas temperature of approx.
If the temperature exceeds 500℃, it will spontaneously ignite and burn when the vehicle is running at high speed and under high load, but if the temperature does not reach 500℃, such as during steady driving or idling (accounting for more than 90% of vehicle operation), it will be released into the atmosphere. . However, patyquirate is harmful to the human body, so
Generally, a vehicle has a filter installed in its exhaust path to collect diesel particulate matter.

By the way, as this filter is used, it tends to collect particulate matter and block the exhaust passage.
Usually, a device is installed to reburn the particulate to regenerate the filter. For example, it is known that re-combustion can be carried out by using various burners, by retarding the injection pump, and by discharging exhaust gas containing a large amount of carbon monoxide compounds that have been activated by an oxidation catalyst to make them highly combustible. There is. Of these, the latter method has the advantage of not requiring a separate burner, etc., but the regenerable exhaust gas temperature can only be obtained in the operating region A, which is biased toward the high speed and high load side as shown in Figure 1. Reproduction is not possible in area B where the frequency is high. Furthermore, as the injection timing is moved in the retard direction C, the temperature at the center of the oxidation catalyst in the exhaust path, for example, increases as shown in Figure 2 (along the broken line), but the maximum output increases along this line. tends to decrease significantly. In this case, in order to maintain the same output as before starting regeneration, it is necessary to significantly increase the accelerator lever opening α.
This change in the opening degree of the accelerator lever greatly deteriorates driving operability and poses many dangers in terms of safety.

SUMMARY OF THE INVENTION An object of the present invention is to provide a diesel particulate filter regeneration device that can reburn particulates regardless of engine driving conditions and without deteriorating driveability.

The diesel particulate filter regenerating device according to the present invention includes a diesel engine exhaust passage equipped with a diesel particulate collecting filter, driven by the diesel engine via an advance device, and equipped with an injection amount adjusting means. a rotational speed sensor for detecting the engine rotational speed of the diesel engine, an accelerator opening sensor for detecting the displacement amount of an accelerator operation system of the diesel engine, and both the rotational speed sensor and the accelerator opening sensor. This configuration includes a control unit that has a built-in characteristic of increasing the fuel injection amount based on the detection signal and delaying the injection timing at the same time.

The present invention will be described below with reference to the accompanying drawings.

FIG. 3 shows a diesel particulate filter regeneration device (hereinafter simply referred to as the regeneration device) as an embodiment of the present invention. This regeneration device is attached to a diesel engine (hereinafter simply referred to as engine) 1, and regenerates a diesel engine particulate filter (hereinafter simply referred to as filter) 3 attached to an exhaust path 2 of this engine. An exhaust manifold 4 fixed to the engine 1, an oxidation catalyst (hereinafter referred to as a front catalyst) 5, which is attached following the manifold and supported on a base having a ceramic honeycomb structure, and a filter 3.
An exhaust path 2 is formed by connecting a muffler (not shown) and the like through an exhaust pipe. In addition,
The filter 3 is made of a heat-resistant ceramic foam with a catalyst. A pressure sensor 7 is attached to the inflow side exhaust passage 2 of this filter for detecting the exhaust pressure at that position and outputting a detection signal to a control section 6 to be described later. The fuel injection pump 8 attached to the engine 1 is a distribution type pump, and is equipped with a hydraulic automatic timer 9 as a timing means, and furthermore, the injection amount of fuel per injection can be adjusted by an injection amount adjustment means 10. . The accelerator lever opening degree α is detected in the accelerator 11 that operates this injection amount adjustment means,
It is output to the control section 6. An accelerator opening sensor 12 is attached. Note that reference numeral 13 indicates a rotation speed sensor that detects the rotation speed of the engine 1. The injection amount adjusting means 10 of the injection pump 8, as shown in FIG.
and a movement operation in the decreasing direction E. Reference numeral 16 indicates a drive shaft, and this shaft drives a governor 17 that is interlocked with the drive shaft. The operating force of the governor is applied to the control lever 1 via the weight sleeve 18.
It acts on 9. A supporting lever 20 that pivotally supports the upper end of this control lever is pivotally supported by a guide lever 23 together with a tension lever 21 via a branch pin 22. This guide lever is pivotally connected to a pin 24 fixed to the base body, and its upper end faces a fuel increasing device 25. Note that the lower end of the supporting lever 20 is formed with a spherical portion 201, which slideably projects into the recessed portion of the spill ring 15. Reference numeral 26 indicates a compression spring, which urges the spill ring 15 in the fuel reduction direction E. The fuel increase device 25 includes a fuel increase screw 27 that is screwed into the base, a reduction gear 28 that is integrated with this screw, and a motor 29 that transmits rotational force to this gear.
and a position sensor 30 that detects and outputs the rotation angle of the reduction gear 28, that is, the increase screw 27. The position sensor 30 is connected to the increase screw 27
From position H of the screw, a detection signal corresponding to the rotation angle of the screw in the fuel increase direction I, that is, the amount of fuel increase ΔQ, is fed back to the control section 6.

On the other hand, the drive shaft 16 of the injection pump 8
is connected to a gear train (not shown) on the engine 1 side via an injection timing retard device (hereinafter simply referred to as a retard device) 31 as shown in FIG. The retard device 31 transmits the rotational force from the engine 1 side to the drive shaft 16 via the planetary gear train 32, and fixes the ring gear 321 on the input side of the planetary gear train.
By rotating the ring gear 322 on the output side by the piston 34 in the hydraulic cylinder 33, a phase difference between input and output is generated in the range of 0° to 60° in terms of crank angle. The hydraulic cylinder 33 is a retardation chamber 331
and an advance angle chamber 332, both of which are supplied with pressure oil from an oil pump 36 via an electromagnetic spool valve 35. This spool valve moves the piston 34 by a predetermined amount each time it receives an output signal of a fixed time width from the control section 6. The reference numeral 37 indicates a filter, the reference numeral 38 indicates a relief valve, and the reference numeral 39 indicates a position sensor that generates a detection signal according to the amount of movement of the piston 34 from the home position H. The electromagnetic spool valve 35 is switched in response to an output signal from the control section 6, and at this time, the amount of movement of the piston 34 corresponding to the amount of retardation is fed back to the control section 6 as a detection signal.

Next, such engine 1 is driven and the sixth
The measurement data shown in Figs. 9 to 9 was obtained. First, FIG. 6 shows the relationship between the engine rotational speed and the average effective pressure when the pre-catalyst 5 is maintained at 700° C. as an isocurve of the total injection amount Q per stroke of the injection pump. FIG. 7 shows the relationship between the engine rotational speed and the average effective pressure when the pre-catalyst 5 is maintained at 700° C. as a retardation amount θ isocurve. Figure 8 shows the front stage catalyst 5
The relationship between the engine rotational speed and the accelerator lever opening degree α when the engine is maintained at 700°C is shown as an isocurve of the increased injection amount ΔQ per stroke of the injection pump. FIG. 9 shows the relationship between the engine rotational speed and the accelerator lever opening degree α when the pre-catalyst 5 is maintained at 700° C. as a retardation amount θ isocurve. Of these,
If, for example, the total injection amount Q per stroke in FIG. 6 is taken out along the average effective pressure and the engine rotational speed is constant, and this is plotted, FIG. 10 is obtained. At this time, the injection pump is retarded by the retard amount θ shown in FIG. In this case, since the total injection amount Q1 per stroke during steady state at each mean effective pressure is shown by a broken line, the difference between the two is the fuel increase amount ΔQ. However, this increased fuel △Q significantly reduces the thermal efficiency of the engine 1 due to the setting of the retardation amount θ.
The effective work of the engine 1 does not appear as an increase in the average effective pressure, but is released as heat loss. That is,
The amount of heat equivalent to the total amount of fuel Q per stroke is the sum of the amount of work and heat loss, but here, the amount of fuel equivalent to the amount of fuel increase △Q is all converted into heat loss by setting the retard amount θ. It releases the energy and suppresses the increase or decrease in the amount of work itself. Note that the incompletely combusted exhaust gas, which results in heat loss, is oxidized by the pre-stage catalyst 5 and the catalyst on the filter to generate combustion heat.

By the way, the control unit 6 controls the accelerator opening sensor 1
2 and the detection signal of the rotational speed sensor 13 to control the injection amount adjusting means 10 and the retardation device 31, and is created by a computer. That is,
As shown in FIG. 11, a map is created based on the detection signals of both sensors 12 and 13, and the rotation angle β of the fuel increase screw 27 corresponding to the fuel increase amount ΔQ at that time, based on the data shown in FIG. 40 and input this to the comparator 41 as the target value. Comparator 4
1 receives the current rotation angle β1 from the position sensor 30 and outputs a difference signal from the target value β. The amplifier 44 outputs an output signal corresponding to this difference signal to the motor 29, and this motor rotates the increase screw 27 according to the output. Similarly, both sensors 1
Based on the detection signals 2 and 13, the amount of movement γ of the piston 34 corresponding to the amount of retardation θ at that time is determined from a map 42 formed based on the data shown in FIG. Enter as a value. The comparator 43 receives the current movement amount γ1 from the position sensor 39 and outputs a difference signal from the target value γ. The spool valve driving section 45 outputs an output signal with a time width corresponding to this difference signal to the electromagnetic spool valve 35.
As a result, this spool valve moves the piston 34, creating a phase difference between the input and output shafts, and causing a decrease in the thermal efficiency of the engine 1 due to the retardation.

In addition, FIG. 12 shows the relationship between the engine rotation speed and the average effective pressure when the pre-catalyst is maintained at 700° C. as an isocurve of the inlet temperature of the pre-catalyst.

The operation of such a reproducing device will be explained based on FIG. 13. Engine 1 has a rotational speed of 1500 [rpm],
When the vehicle is traveling steadily at a speed of 60 [Km/h], when the pressure sensor 7 detects the exhaust pressure P due to the clogging of the filter 3 and issues a detection signal, the control unit 6
starts driving the playback device P1. Both sensors 1
Injection amount adjusting means 10 based on the detection signals 2 and 13
The fuel increasing device 25 increases the amount of fuel by a predetermined fuel increase amount ΔQ and injects it into the injection pump 8, and the retard device 31 gives a large retard amount θ to the injection pump. As a result, P2 regeneration start operation is performed after 17 to 20 seconds, here the retard amount θ = 25° (crank angle),
Fuel increase amount △Q = 15mm ³ /1 stroke is completed. First, the pre-catalyst temperature T1 rises rapidly, and the resulting high-temperature exhaust gas burns the particulate matter on the filter 3. Therefore, the filter front end temperature T2, the filter center temperature T3, and the filter rear end temperature T4 each rise. As a result, the exhaust pressure P decreases, and when the exhaust pressure P falls below the set value, the control section 6 enters a regeneration stop operation start P3. In addition,
This operation may be performed using a timer when a set time has elapsed. After approximately 18 seconds, the injection pump 8 returns to its original injection amount and advance angle due to the regeneration stop operation.
The playback stop operation is ended P4. As a result, the temperature on each exhaust path returns to the normal temperature side, and the exhaust pressure P further decreases.

In this manner, the reproducing device can remove particulate matter from the filter 8. Furthermore, although the amount of fuel for re-combustion is increased during regeneration, the large retardation process performed at the same time reduces the thermal efficiency of the engine 1, suppressing the increase in output itself despite the increase in fuel. Through this process, the amount of heat equivalent to the increased amount of fuel is discharged from the engine as a heat loss, but this allows the front-stage filter 5 to easily generate high-temperature gas (see Figure 12), and this high-temperature gas can be used to drive the filter 3. Easy to play.

[Brief explanation of drawings]

Figure 1 shows the relationship between engine rotational speed and average effective pressure divided into operating ranges in which filter regeneration is possible using conventional equipment. 3 is a schematic configuration diagram of a playback device as an embodiment of the present invention,
Fig. 4 is a sectional side view of the main part of the injection amount adjustment means in the above device, Fig. 5 is a schematic configuration diagram of the retardation device in the same device, and Fig. 6 is the total injection amount per stroke of the engine with the above device. Fig. 7 is a retardation amount isocurve for the engine equipped with the above device, Fig. 8 is an isocurve for the increased injection amount per stroke based on the accelerator lever opening of the engine equipped with the above device, and Fig. 9 is an isocurve for the increased injection amount per stroke of the engine with the above device. Fig. 10 is an explanatory diagram of the injection amount at a constant engine speed; Fig. 11 is a schematic block diagram of the control section in Fig. 6; The figure shows the exhaust temperature isocurve diagram of the engine equipped with the regeneration device shown in Figure 6, and the diagram shown in Figure 13 shows the relationship between elapsed operation time, exhaust pressure, and temperature of each part during regeneration of the engine equipped with the same device. . DESCRIPTION OF SYMBOLS 1...Engine, 2...Exhaust path, 3...Filter, 5...Pre-stage catalyst, 6...Control unit, 8...Injection pump, 9...Timer, 10...Injection amount adjustment means, 12... Accelerator opening sensor, 13... Rotation speed sensor, 25... Fuel increase device, 31... Retard device.

Claims (1)

[Claims] 1. An exhaust passage of a diesel engine equipped with a diesel particulate collection filter, an injection pump driven by the diesel engine and equipped with an injection amount adjusting means and a timing means, and an engine rotation speed of the diesel engine. a rotational speed sensor to detect, an accelerator opening sensor to detect a displacement amount of an accelerator operation system of the diesel engine, and at the same time increase the fuel injection amount based on detection signals from both the rotational speed sensor and the accelerator opening sensor, A diesel particulate filter regeneration device having a control section with a built-in characteristic for delaying injection timing.