JPS58222908A - Exhaust gas particle purifier of internal-combustion engine - Google Patents

Abstract

PURPOSE:To enable a filter of being refreshed under a wide range condition of an engine by regulating the opening of an opening-and-closing valve according to the amount of the flow of engine exhaust gas at the refreshing time of the filter so as to control the quantity of gas which passes through the filter member. CONSTITUTION:When a filter is refreshed, electric current is fed from a terminal 3' and a heater is then heated to ignite and burn particle. An opening-and-closing valve 5 is disposed in the way of a bypass flow passage 4. When particle is going to be trapped, the opening-and closing valve 5 takes a fully closed position as shown by A in the drawing so that the entire amount of exhaust gas passes through the filter 2 and is trapped. When the filter is going to be refreshed, the opening-and-closing valve 5 takes a fully opened position C so that exhaust gas mostly passes through a bypass pipe 4. If the amount of exhaust gas is little, the opening and-closing valve 5 is set to take a half-closed position as shown by C to increase pressure loss in the bypass flow passage in order to maintain a differential pressure applied on the filter member, therefore assuring the quantity of gas which passes through the filter member.

Description

Detailed Description of the Invention The present invention is an exhaust gas particulate purification system that collects particulates in exhaust gas emitted from internal combustion engines of automobiles, etc., and uses the collected particulates as fuel using electric heating means to purify the exhaust gas. It is related to the device.

In order to collect fine particles such as carbon particles contained in exhaust gas emitted from a diesel engine, the internal combustion engine patent claims include a particulate trap incorporating a filter member such as a ceramic honeycomb structure or a ceramic foam. A collection device has been proposed. In these devices, as particulates accumulate on the filter member, the ventilation resistance of the filter member increases, leading to a decrease in the output of the engine, and the accumulated particulates fall off, reducing the filter function. Therefore, it is necessary to periodically remove the particulates accumulated on the filter member and restore the function of the filter member to the state before collecting the particulates.
'As this regeneration means, a method has been proposed in which a heating means (3) is attached to the filter member to heat and burn the collected particulates. However, under normal driving conditions, the exhaust gas temperature is lower than the ignition point of carbon particles, so the heat source is cooled by the exhaust gas, preventing the particles from igniting, and even if they are ignited, they are blown out by the exhaust gas flow. or

Therefore, the operating conditions under which it can be reliably regenerated are extremely limited.

As a means to improve the ignitability of particulates and to prevent them from being blown out during combustion, the exhaust gas passage connected to the internal combustion engine is divided into two, a filter member is provided in each passage, and the exhaust gas of the filter member is A method has been proposed in which a flow path switching pulp is provided on the upstream or downstream side, the exhaust gas is selectively guided to one path, and the filter member installed in the path through which the exhaust gas does not flow during pulp operation is heated and regenerated. . However, with this method, when one passage is closed, the pressure loss (hereinafter referred to as pressure loss 25゛) of the filter member in the other passage is more than double.
“.

In addition, the flow rate of the exhaust gas is also approximately doubled.

(4) Increased pressure loss worsens the driving feeling and also has a negative effect on the engine output. Furthermore, due to the increase in flow velocity, particulates collected on the filter member may be blown away depending on the operating conditions at the time of pulp switching, resulting in a decrease in filter function.

Furthermore, according to our test results, it has been found that when the heating means ignites and burns off the particulates deposited on the filter, there is an optimum flow rate of exhaust gas passing through the filter member for combustion. When the exhaust gas flow rate is relatively large, the combustion region is cooled by the gas flow and combustion is stopped. Conversely, if the gas flow rate is extremely low,
Combustion also ceases because the oxygen necessary for combustion cannot be provided. However, in the above method, although it is possible to reduce the gas flow rate passing through the filter during regeneration, the gas flow rate passing through the filter depends on the leakage characteristics of the flow path switching pulp (although this can be adjusted arbitrarily in the design). ) and the engine exhaust gas flow rate.

On the other hand, in the case of a diesel engine, the engine exhaust gas flow rate is proportional to the engine speed, but the engine speed (5) varies significantly depending on the vehicle driving conditions. Therefore, in the above method, it is possible to reduce the flow rate of gas passing through the filter during regeneration, but it is impossible to flow the optimal exhaust gas flow rate, which we know from test results, over a wide range of engine operating ranges. It is.

In view of the above points, the present invention aims to enable the regeneration of filter members under a wide range of operating conditions, and is basically installed in the exhaust gas passage of an internal combustion engine to attach and collect particulates in the exhaust gas. an electric heating means installed on or near the upstream side of the exhaust gas of the filter member and generating heat when energized to ignite and burn the collected particulates; and upstream and downstream sides of the filter member in the exhaust gas passage. A bypass passage with low ventilation resistance that allows most of the exhaust gas to flow through without passing through the filter member when fully opened, and a bypass passage that is installed in the bypass passage and opens and closes it to reduce the amount of exhaust gas passing through the filter member. By adjusting the opening degree of the opening/closing valve according to the engine operating conditions, an appropriate amount of exhaust gas can be generated for combustion during regeneration regardless of the operating conditions. The above object is achieved by passing it through a filter member.

The present invention relates to two methods that enable the above-mentioned operation. First, a specific example of the first method will be described below with reference to the drawings.

FIG. 1 shows the basic configuration of a particulate purification device according to the present invention. Reference numeral 1 designates a filter container with a particulate collection filter 2 built therein, and 3 designates an electric heater installed closely on the upstream end face of the filter member 2. During filter regeneration, power is supplied from terminal 3', and the heater becomes red hot and collects particulates. Perform ignition combustion.

Reference numeral 4 denotes a bypass flow path which is a component of the present invention, and an on-off valve 5 is installed in the middle. When collecting particulates, the on-off valve 5 assumes the fully open position shown by A in the figure, and the entire amount of exhaust gas flows through the filter 2.
It passes through and is collected. During filter regeneration, the valve normally assumes the fully open position at C in the figure, and most of the exhaust gas passes through the bypass pipe 4. A minute pressure difference corresponding to the pressure loss of the bypass pipe 4 is applied to the filter material 2, and a minute flow rate determined by this pressure (7) and the ventilation resistance of the filter member flows through the filter material. Here, if the bypass pipe diameter is determined so that the amount of gas passing through the filter member is appropriate when the exhaust gas flow rate is relatively large, if the operating conditions change and the exhaust gas amount decreases, the bypass pipe 4 The pressure loss decreases, the pressure difference applied to the filter material also decreases, and the amount of gas passing through the filter material also decreases below an appropriate amount. Conversely, if the bypass pipe diameter is reduced so that the amount of gas passing through the filter material is appropriate when the amount of exhaust gas is relatively small, the amount of gas passing through the filter material will be excessive when the amount of exhaust gas increases. becomes. As shown in the first embodiment, in order to prevent the following problems, the present invention sets the diameter of the bypass pipe so that the amount of gas passing through the filter material becomes appropriate when the amount of exhaust gas increases,
During regeneration, the on-off valve 5 is fully opened. In other words, at the position shown here in the figure, when the amount of exhaust gas decreases, the on-off valve 5 is placed in the half-open state indicated by B in the figure, thereby increasing the pressure loss in the bypass flow path and reducing the filter material. The first feature is that the applied pressure difference can be maintained and the amount of gas (8) passing through the filter material can be secured.

Next, this effect will be explained according to FIG. In FIG. 2, the horizontal axis represents the flow rate of engine exhaust gas, and the vertical axis represents the flow rate of gas passing through the filter member. The shaded area represents the range of exhaust gas flow rate passing through the filter member suitable for regeneration. Curve C shows the correspondence between the exhaust gas flow rate and the amount of gas passing through the filter member when the opening/closing valve position C1 is fully opened. As is clear from this, the amount of gas passing through the filter necessary for regeneration cannot be secured on the low flow rate side. The curve already shown in the figure is the amount of gas passing through the filter member when the opening/closing valve is in the half-open position according to the present invention, that is, the position shown by B in FIG. This shows that it is possible to prevent a decrease in

As described above, by adjusting the valve opening degree of the bypass passage according to the engine exhaust gas flow rate, it is possible to regenerate the filter under a wide range of exhaust gas flow rates.

(9) Next, an embodiment of a valve actuator that allows the valve to be in a half-open position will be described.

FIG. 3 shows an embodiment of a vacuum actuator with three-position operation, in which 1a is a first vacuum housing, 2a is a second vacuum housing, and bellophrams 6a, 6a' and springs 10, 11 are built inside, respectively. There is. 7a' is a rod driven by the bellow ram 6a,
between the rod taa driven by the bellow frame 6a'
For example, by energizing the solenoid valve Vl and applying negative pressure from the vacuum housing 1a to the vacuum housing 1a, the rod 7a moves by an amount a, and the arm connected to the rod 14, the valve plate 8 assumes the half-open position indicated by B in the figure. Furthermore, in order to bring the valve opening degree to the fully open position shown by C in 1, for example, by energizing the solenoid valve ■λ and applying negative pressure to the 4-way vacuum bousing 2, the stroke in the range already shown in the figure can be adjusted. The rod 13a that has the valve plate can be opened to the fully open position shown by C via the rod 7a (1
0). The degree of opening when the valve is half open can be adjusted arbitrarily by adjusting the stroke a.

FIG. 4 shows another embodiment of a valve actuator that allows similar operation. 1b is a first vacuum housing, 2b is a second vacuum housing, and by applying negative pressure to each, a.

Strokes within the range indicated by b are possible.

The above is an example in which one actuator capable of three-position operation is used, but FIG. 5 shows an example in which two actuators are used to enable similar operation.

In FIG. 5, 16G is a small-stroke actuator that allows the valve to be half-opened, and 15c is a large-stroke actuator that allows the valve to be fully opened, which rotates the valve 8c via an arm 14at fixed to the valve and shaft. The half-opening operation of the valve is performed by pushing the arm 14-a by the protruding portion 14-0 of the arm 1, lb, which rotates freely around the shaft 3cl.

The opening/closing valve drive mechanism has been explained above, and next, an actual valve drive control method will be described.

The first method of the present invention is characterized in that the degree of opening of the opening/closing valve is adjusted depending on the magnitude of the exhaust gas flow rate of the engine.

Although it is difficult to directly measure the exhaust gas flow rate of an engine, we focused on the fact that there is a good correspondence between engine speed and exhaust gas flow rate in diesel engines. It was found that by adjusting the valve opening degree, it was possible to control the exhaust gas flow rate sufficiently for practical purposes. As a method for detecting the engine rotation speed, a conventionally known method such as attaching a magnetic pickup or the like close to a gear provided on the outer periphery of the flywheel and counting the number of pulses generated in the pickup is sufficient. Further, a mechanism for determining the magnitude of the engine rotation speed relative to the set rotation speed can be implemented using conventional technology. The above describes the case where the engine speed, which has a correlation with the exhaust gas flow rate, is used as a method for detecting the magnitude of the exhaust gas flow rate.
), ri, it goes without saying that another signal having a correlation with the engine speed may also be used.

For example, in some types of fuel injection pumps for diesel engines, the fuel pressure within the injection pump changes approximately depending on the engine speed.

In an engine using this type of pump, by detecting the fuel pressure within the injection pump, it is possible to detect the engine speed and, by extension, the size of the exhaust gas raw material. In this method, the desired signal can be obtained by attaching a pressure switch that operates at an appropriate pressure to the fuel injection pump.

It is also possible to control the opening/closing valve by detecting the engine intake air material which is approximately equal to the exhaust gas material. In this case, a venturi is provided in the engine suction pipe, and the intake air amount, that is, the exhaust gas flow rate can be detected based on the magnitude of the venturi negative pressure.

As described above, the present invention reduces the amount of gas passing through the filter material during filter regeneration (1"3) by adjusting the opening degree of the on-off valve attached to the bypass pipe section depending on the magnitude of the exhaust gas flow rate. It is characterized by controlling the amount to be suitable for reproduction.

In the above, the magnitude of the exhaust gas flow rate is detected by some means,
We have described a method for controlling the amount of gas passing through the filter material by adjusting the opening degree of the on-off valve based on this signal, but the above purpose can be achieved by providing the on-off valve itself with flow rate control characteristics. A second method of the present invention will be described.

The pressure loss of the filter member, that is, the differential pressure across the filter changes approximately in proportion to the amount of gas passing through the filter. Therefore, by controlling the bypass flow rate so that the differential pressure across the filter remains constant, the amount of gas passing through the filter can be controlled to be constant. A second aspect of the present invention is that the above-mentioned operations can be performed using a simple valve mechanism.

FIG. 6 is a block diagram of an embodiment of the second method of the present invention, with four
d is a filter container having a filter member 5d and an electric heater block 6 built therein. 1 is an exhaust gas inflow pipe section,
2 is the outflow pipe section, and 3d (14) shows the bypass flow path. 3a is the upstream branch of the bypass pipe;
3b shows the inflow part of the bypass pipe to the flow rate control valve.

Note that 7 indicates a heater divided into a plurality of parts, and 8 indicates a terminal for supplying power to each heater. 9d is a flow control pulp according to the present invention, which has a built-in poppet valve 10 for opening and closing a bypass flow path. 10 indicated by a solid line in the figure indicates the valve closed position, and 10' indicated by a two-dot chain line indicates the valve open position. Reference numeral 9a indicates an inflow portion for gas passing through the filter member into the control valve, and reference numeral 9b indicates an inflow portion for bypass gas.

The basis of the second method of the present invention is the f & differential pressure in front of the filter,
That is, the purpose is to control the amount of gas passing through the filter to a constant value by controlling the pressure difference shown by PL+P in the figure to be constant. Here, by making the diameter of the bypass pipe 3 sufficiently large and sufficiently reducing the ventilation resistance of the bypass pipe, the front and rear pressures of the poppet valve 10, indicated by P1' and Pz' in the figure, can be adjusted to P :t l P >, respectively. almost equal. Therefore, the pressure difference between the front and rear of the poppet valve P1' - P
The objective can be achieved by keeping y′ constant regardless of the exhaust gas flow rate.

Next, an embodiment of a valve structure that makes this possible will be described below with reference to the drawings.

FIG. 7 shows a first embodiment of the second method of the present invention. lOe is a valve plate attached to the arm 12 by a pin 10e', and the arm 12 is fixed to the shaft 13e. An arm 14e is fixedly attached to the shaft 13e, and an arm 15 is attached which is freely rotatable about the shaft 13e. Reference numeral 16 denotes a rod of an actuator (not shown). When closing the bypass flow path, the rod pushes the arm 15, and the arm 15 pushes the protrusion 14e' of the arm 14e to move the valve plate 10e to the valve material 9-c. Crimp to close the flow path.

When repassing the filter, that is, when most of the exhaust gas is bypassed and the amount of gas passing through the filter member is controlled to a constant amount, the arm 15 is separated from the arm 14 by pulling the actuator rod 16. 176 is arm 146
This is a spring for pressing the valve plate IQe against the valve seat 9-c with a constant pressure. Here, as mentioned above, the differential pressure across the filter material is approximately equal to the difference in pressure between the front and rear of the valve plate, indicated by Pyu' and PΣ' in the figure, that is, P'-P≧', but the strength of the spring 17e By appropriately adjusting P%
P2' can be kept at a constant value almost regardless of the exhaust gas flow rate. In other words, when the exhaust gas flow rate increases, the valve opening automatically increases, and when the exhaust gas flow rate decreases, the valve opening decreases; however, the differential pressure pi'-pχ' after the valve cylinder depends on the strength of the spring 17e. Since the pressure is determined and remains almost constant, the differential pressure P1-P across the filter becomes constant, and the amount of gas passing through the filter also becomes constant. As described above, the second method of the present invention is
Focusing on the point that the differential pressure after the valve cylinder of the bypass flow rate adjustment valve is almost equal to the differential pressure across the filter material, we determined the flow rate at which the differential pressure after the valve cylinder remains constant regardless of the magnitude of the exhaust gas flow rate, that is, regardless of the magnitude of the bypass flow rate. By using a regulating valve, the differential pressure across the filter is kept constant and the amount of gas passing through the filter is controlled. As a valve that can maintain a constant differential pressure after the valve cylinder, when the valve is opened, the valve plate is pressed against the valve seat by spring force (17
) It is characterized by using a poppet valve with a pressing configuration.

Next, another embodiment will be described. FIG. 8 shows an example in which a butterfly valve 18f for limiting the amount of gas passing through the filter during bypass is provided in addition to the above-mentioned control pulp. This valve is provided for the following purposes. The method of the present invention is to control the amount of gas passing through the filter to a constant value by controlling the differential pressure across the filter to a constant value, and the poppet valve 10 is pressed against the valve seat 9-c with a constant force by the spring 17. This is achieved by: On the other hand, filter members with various ventilation resistances may be used, and in general, the lower the particle collection efficiency, the lower the ventilation resistance.When using filter members with low ventilation resistance in this way, it is natural that ,
The differential pressure across the filter, which should be kept constant, also becomes small. Although this is possible by weakening the force of the spring 17, the rotational resistance of the shaft 13 becomes relatively large, which appears as a setting error. The purpose of the valve plate 18f is to prevent this, and it closes the valve plate 18f when bypassing, making the valve plate 18f appear to be closed.
) By increasing the ventilation resistance of the router member, it is possible to smoothly control the flow rate without weakening the force of the spring 17. In some cases, the valve plate 18f is provided with a small hole 18f' to adjust the ventilation resistance of the valve.

The figure shows each operating position during filter regeneration, ie, bypass. Reference numeral 11 is an actuator for driving a poppet type flow rate regulating valve, and when the valve is bypassed, negative pressure is supplied to the supply hole 11', and the arm 15 is pulled to set the valve 10 to the open position. Further, 20f is an actuator for driving the valve plate 18f, and when bypassing, negative pressure is supplied to the supply hole 20', and the valve plate 18f is supplied with negative pressure.
8f is the closed position.

FIG. 9 shows each operating position during non-regeneration in the same embodiment, and negative pressure is not supplied to each supply hole 20', 11'.
The valve plate 18f takes the open position, and the poppet valve plate 1
o is pressed against the valve member 9-c by the pressing force of the rod 16 of the actuator 11, thereby closing the bypass passage.

FIG. 10 shows a modification of the embodiment shown in FIG. 9th
In the figure, an example is shown in which a spring 17 is installed between the arm 14 and the valve housing 9 as a method of pressing the poppet valve 1o against the valve seat 9-c with a constant force, but in this embodiment, this spring is installed inside the actuator. The case where it is built in is shown. The actuator of this embodiment can apply negative pressure to both sides of the diaphragm through the supply holes 21' or 21''. During bypass, negative pressure is not applied to either side, and the spring 21a causes the rod 16, arm 1
5, the valve plate 1o is weakly pressed against the valve seat 9-c. When not bypassed, by supplying negative pressure to 21',
The valve plate 10 is strongly pressed against the valve seat and closes the bypass flow path. Further, when it is necessary to reduce the ventilation resistance of the exhaust system as much as possible, such as when the engine is at maximum output, the valve plate 10 can be forced to the fully open position 10'' by applying negative pressure to the valve 21''.

Next, 6 degrees when the flow rate adjustment mechanism of the present invention is put to practical use:
('tFj! L 7, M!"'"6 m!Ill
An example of the structure "fJmHIJn:R, , □" will be described.

During bypass, the flow rate control valve 10 (10e) shown in FIGS. 7 to 9 operates in a half-open state because the exhaust gas pressure applied to the valve plate 10 and the tension of the spring 17 (17e) are balanced, but the exhaust gas Since the pressure includes a large pulsation component, the valve plate 10 may vibrate and the flow rate adjustment function may be impaired.

FIG. 11 shows an embodiment of a mechanism for preventing this vibration. In the figure, 14h' indicates a damper weight added to the arm 14. 14 on the arm 14 fixed to the valve stem 13.
By adding the weight indicated by h', vibration of the valve plate caused by exhaust pulse pressure can be effectively prevented.

The vibration prevention method is not limited to this, and it is also possible to add a damper that utilizes fluid flow resistance, but this has the drawback of complicating the configuration. Further, in the embodiment shown in FIG. 11, since the actuator is directly connected to the arm fixed to the valve shaft, the mass of the rod 16 diaphragm, etc. acts as a damper weight, and the valve plate 1
Oscillation of o (21) The motion is relaxed.

As explained in detail above, the present invention bypasses most of the exhaust gas during filter regeneration, reduces the amount of gas passing through the filter material, and automatically and continuously By controlling the bypass flow rate and controlling the amount of gas passing through the filter material, it has the excellent advantage that filter regeneration is possible under a wide range of engine operating conditions.

[Brief explanation of the drawing]

1 to 5 relate to the first method of the present invention, in which FIG. 1 is a block diagram showing the basic configuration, FIG. 2 is a graph showing the effect, and FIG. 3 is a first * method of the actuator. Embodiment sectional views, FIG. 4 shows a second embodiment of the actuator, and FIG. 5 shows a third embodiment of the actuator. Further, FIGS. 6 to 11 relate to the second method of the present invention, and FIG. 6 is a configuration diagram showing the basic configuration, and FIG.
The figure shows a first embodiment of the flow control valve, FIG. 8 shows a second embodiment of the flow control valve, and FIG. 9 is a cross-sectional view showing the positional relationship of the flow control valve shown in FIG. 8 (22) during non-regeneration. , FIG. 10 is a sectional view of the third embodiment of the flow control valve, and FIG.
The figures each show a sectional view of a fourth embodiment of the flow control valve. 1... Filter storage container, 2... Filter material, 3...
...Electric heater, 4...Bypass flow path, 5...Bypass flow path opening/closing valve, la, 2a...Vacuum housing, 6a, 6a'...Verofram, 7a...Roso l', 13a ...Rod, lb, 2b...Vacuum housing, 7b...Rod, 16a...Small stroke actuator, 15c...Large stroke actuator, 8C...Valve plate, 4d...Filter storage container , 5d...filter material, 3d...bypass flow path, 9d...flow control valve, 9-c...valve seat, lO
e... Valve plate, 13e... Shaft, 14e... Arm, 17e... Spring, 18f... Valve plate, 2
0f...Actuator, 18f'...Small hole, 1
4h'...damper weight. Representative Patent Attorney Takashi Okabe (23) Figure 1 Figure 2 Figure 3 Figure 6 Figure 7 Figure 8-h Figure 9

Claims (1)

[Scope of Claims] (11) A filter member installed in the exhaust gas passage of an internal combustion engine to collect particulates in the exhaust gas; and a filter member installed at or near the upstream end face of the filter member to collect fine particles in the exhaust gas. Exhaust gas particulate purification for an internal combustion engine, comprising an electric heating means for heating and burning the collected particulates, a bypass passage through which most of the exhaust gas can flow, and an opening/closing valve installed in the bypass passage for opening and closing the bypass passage. An exhaust gas particulate purification device for an internal combustion engine, characterized in that the device adjusts the opening degree of the opening/closing valve in response to the magnitude of the engine exhaust gas flow rate during filter regeneration to control the amount of gas passing through the filter member. ( 2) As a means of determining the magnitude of engine exhaust gas flow rate,
Exhaust gas from an internal combustion engine according to claim 1, characterized in that the engine speed is detected and the opening degree of the opening/closing valve is adjusted in response to the magnitude of the engine speed. Device. (3) An exhaust gas particulate purification device for an internal combustion engine as described in which the opening degree of the opening/closing valve can be adjusted in multiple positions. (4) An exhaust gas particulate purification device for an engine that keeps the differential pressure across the filter constant as a means for controlling the amount of gas passing through the filter during filter regeneration. (5) The on-off valve installed in the bypass flow path, which adjusts the flow rate of exhaust gas on the bypass side so as to keep the front and rear pressure of the filter constant during filter regeneration, is a poppet valve with a valve seat located on the upstream side and a valve plate located on the lower side; During filter regeneration, a valve is used that is operated by pressing the valve plate against the valve seat with a constant force by a spring. (6) An on-off valve is provided in the middle of the filter member side passage, and the on-off valve is closed during filter regeneration. and (2) a combustion engine exhaust gas particulate purification device.