Exhaust gas cleaning device for internal combustion engine

An exhaust gas cleaning device for collecting and burning off particulates within exhaust gases discharged from an internal combustion engine of an automobile or the like is disclosed. The device comprises a filter member which is disposed in an exhaust gas passage of the engine for collecting particulates within exhaust gases, an electrically heating member which is disposed on or near the upstream end of the filter member for igniting and burning off the collected particulates, a by-pass passage having a flowing resistance smaller than that of the filter member, which is communicated with the upstream side and the downstream side of the filter member for flowing most of the exhaust gases without passing the filter member at the filter member regenerating time, a valve means which is disposed in the by-pass passage for controlling the exhaust gas amount flowing into the by-pass passage and the filter member by opening or closing the by-pass passage and a valve control means which controls the valve opening so as to flow a small amount of exhaust gases enough to supply the most proper amount of oxygen to the filter member for burning off the collected particulates, into the filter member when said filter member is regenerated.

BACKGROUND OF THE INVENTION 
The present invention relates to an exhaust gas cleaning device for 
collecting particulates within exhaust gases discharged from an internal 
combustion engine of an automobile or the like, and cleaning exhaust gases 
by burning off the collected particulates by means of a heater member. 
Particulates collecting devices provided with a filter member made of a 
ceramic honeycomb structure or a ceramic foamed body, have been proposed 
for collecting particulates such as carbon particles contained within 
exhaust gases. In these devices, the flowing resistance of the filter 
member increases as the particulates accumulate the filter member to 
reduce the output of an engine. In addition, the accumulated particulates 
fall from the filter member to reduce the filtering efficiency thereof. 
Therefore, it is required to regenerate the filter member by periodically 
removing the particulates from the filter member. 
As the filter member regenerating means, it has been proposed to mount a 
heater on the filter member for heating the collected particulates to be 
burnt off. However, in this device, since the exhaust gas temperature is 
lower than the ignition point of carbon particulates under the normal 
driving condition of an automobile, the heater is cooled by the exhaust 
gases so that the particulates are obstructed from being ignited or the 
flame is blown out by the exhaust gas flow. 
In order to improve the ignitability of the collected particulates and in 
order to prevent the ignited particulates from being blown out, it has 
been proposed to divide an exhaust gas passage communicated with the 
engine into two divergent passages and to provide a filter member in each 
of two divergent passages and a diverter valve on the upstream side or the 
downstream side of the filter members. By this device having the above 
structure, exhaust gases are selectively introduced into one of two 
passages while the filter member of the other passage is heated to burn 
off the collected particulates. 
However, while one of two divergent passages of this device is closed, 
pressure loss in the filter member of the other divergent passage 
increases and the flowing speed of the exhaust gases also increases. 
The increase in pressure loss makes the durability worse and reduces the 
output of the engine. 
And due to the increase in flowing speed, the particulates collected by the 
filter member are apt to be blown off when the valve is changed. As a 
result, the filtering efficiency is reduced. 
The above described problem can be overcome by providing a large sized 
filter member in each of the divergent passages. 
However, this device requires two large casings for accommodating such 
large sized filter members so that the device becomes large. 
In addition, while the particulates collected by one of the filter members 
are heated by the heater, the exhaust gases are not supplied thereto so 
that a sufficient amount of oxygen is not supplied to the filter member. 
Therefore, all of the collected particulates cannot be burnt off. 
Accordingly, one object of the present invention is to provide an exhaust 
particulates cleaning device for an engine, having a single filter element 
and a heater for burning off the particulates collected by the filter 
member, of which the construction is simple and filter regenerability is 
excellent. 
Another object of the present invention is to provide an exhaust 
particulates cleaning device for an engine, wherein ignitability and 
combustibility of collected particulates are improved by controlling the 
exhaust gas amount supplied to the filter member at the filter member 
regenerating time. 
Still another object of the present invention is to provide an exhaust 
particulates cleaning device having a means for controlling the exhaust 
gas amount to be supplied to the filter member into the amount required 
for regenerating the filter member in accordance with the engine driving 
condition. 
SUMMARY OF THE INVENTION 
The exhaust particulates cleaning device of the present invention comprises 
a filter member which is disposed in an exhaust gas passage of an internal 
combustion engine for collecting particulates within exhaust gases; an 
electrically heating means which is disposed on or near the upstream end 
of the filter member for igniting and burning off the collected 
particulates; a by-pass passage having a flowing resistance smaller than 
that of the filter member, which is communicated with the upstream side 
and the downstream side of the filter member for flowing most of the 
exhaust gases without passing the filter member at the filter member 
regenerating time; and a valve means which is disposed in the by-pass 
passage for controlling the exhaust gas amount flowing into the by-pass 
passage and the filter member by opening or closing the by-pass passage. 
Furthermore, the exhaust particulates cleaning device is further provided 
with a valve control means which controls the valve opening so as to flow 
a small amount of exhaust gases enough to supply the most proper amount of 
oxygen to the filter member for burning off the collected particulates, 
into the filter member when the filter member is regenerated.

DETAILED DESCRIPTION OF THE INVENTION 
Hereinafter, the present invention will be explained in accordance with the 
several embodiments with reference to the drawings. 
FIG. 1 is a schematic view of an exhaust system of an internal combustion 
engine which is provided with an exhaust particulates cleaning device 
according to the present invention. 
The reference numeral 1 designates an internal combustion engine such as a 
diesel engine, 2 designates an exhaust manifold, 3 designates an exhaust 
pipe and F designates an exhaust particulates cleaning device which is 
provided in the exhaust pipe 3. 
The exhaust particulates cleaning device F comprises a casing 4, a filter 
member 5, and a plurality of electric heaters 6 which are closely fixed to 
the upstream end surface of the filter member 5. 
The reference numeral 7 designates a separator for dividing the exhaust gas 
flowing passage formed within the casing 4 into one passage 40a and 
another passage (by-pass passge) 40b. The exhaust gas amount flowing into 
the by-pass passage 40b is controlled by a control valve 8. 
The reference numeral 9 designates a differential pressure sensor for 
measuring the differential pressure between the upstream side and the 
downstream side of the filter member 5 and detecting the pressure loss of 
the exhaust gases passing the filter member 5. 10 designates a temperature 
sensor for detecting the temperature of the exhaust gases on the 
downstream side of the filter member 5. 11 designates a rotating speed 
sensor for detecting the rotating speed of the engine 1. 12 designates a 
control circuit for calculating the particulates accumulating degree of 
the filter member 5 from the output signals from the differential pressure 
sensor 9, the temperature sensor 10 and the rotating speed sensor 11 and 
supplying output signals to the electric heaters 6 and the control valve 8 
when the particulates accumulating degree exceeds a predetermined amount. 
13 designates a battery, 14 designates a heater switch for supplying an 
electric power to the electric heaters 6 from the battery 13 upon 
receiving the output signals from the control circuit 12. 15 designates a 
valve actuator for operating the control valve 8 upon receiving the output 
signals from the control circuit 12. 
The by-pass passage 40b has a flowing resistance much smaller than that of 
the filter member 5 and has such a cross sectional area that most part of 
the exhaust gases flow into the by-pass passage 40b when the control valve 
8 is fully opened. 
In operation, while the exhaust gases discharged from the internal 
combustion engine 1 through the exhaust manifold 2 and the exhaust pipe 3 
pass the filter member 5, the exhaust particulates contained within the 
exhaust gases are collected by the filter member 5. During the exhaust 
particulates collecting time, the control valve 8 is operated to close the 
by-pass passage 40b. 
As the exhaust particulates collecting operation proceeds, the flowing 
resistance of the filter member 5 gradually increases. The increase in 
flowing resistance is observed by detecting the differential pressure 
between both sides of the filter member 5 by the differential pressure 
sensor 9. This differential pressure also varies broadly with the change 
of the exhaust gas temperature and the change of the engine rotating 
speed. By removing the influence of the exhaust gas temperature and the 
engine rotating speed from the obtained differential pressure, true 
flowing resistance of the filter member 5, namely, exhaust particulates 
accumulating degree can be obtained. 
When the exhaust particulates accumulating degree reaches a predetermined 
amount, output signals are supplied to the valve actuator 15 from the 
control circuit 12. 
Then, the control valve 8 operates to open the by-pass passage 40b so that 
the exhaust gas amount flowing through the passage 40a is decreased. 
Namely, when the by-pass passage 40b is opened, almost all of the exhaust 
gases flow into the by-pass passage 40b of which pressure loss is much 
smaller than that of the filter member 5 and only a small amount of 
exhaust gases flow into the filter member 5. 
Then, an electric current is applied to the electric heaters 6 provided in 
the filter member 5 to generate heat. The exhaust particulates collected 
by the filter member 5 in contact with the heaters 6 are heated and starts 
burning. The flame expands towards the downstream side of the filter 
member 5 to burn off the exhaust particulates collected therein. In this 
case, since a small amount of exhaust gases flow into the filter member 5, 
oxygen is supplied to the filter member 5 so that the exhaust particulates 
can be completely burnt off. The exhaust gas amount to be supplied to the 
filter member 5 is determined by the difference between the flowing 
resistance of the filter member 5 and that of the by-pass passage 40b. 
Since the exhaust gas amount flowing into the filter member is small as 
described above, the heating efficiency of the heaters 6 is not reduced. 
FIGS. 2 to 4 illustrate a first embodiment of the exhaust gas cleaning 
device according to the present invention. 
The cylindrical casing 4 having an elliptical cross section defines exhaust 
gas passages 40a, 40b which are separated by the separator 7. 
The filter member 5 is disposed in the exhaust gas passage 40a and 
elastically supported by a wire net 41 and a sealing member 42. 
The filter member 5 is made of a ceramic foamed body, for example. 
The control valve 8 is turnably supported within the exhaust gas 
passage(by-pass passage)40b. The exhaust gas amount flowing into the 
by-pass passage 40b is controlled by the turning of the control valve 8. 
Nichrome wire heaters 6 are disposed on the upstream end surface of the 
filter member 5. The heaters 6 are fixed by a ceramic honeycomb body 60 
which is provided so as to cover the heater 6. The ceramic honeycomb body 
10 serves as a heater pushing means and a thermal insulator. 
At the exhaust particulates collecting time, the control valve 8 turns and 
closes the by-pass passage 40b. All amount of exhaust gases flow into the 
upper exhaust gas passage 40a as shown in FIG. 2 and after the exhaust 
particulates are collected by the filter member 5, the exhaust gases flow 
out of the filter member 5. 
When the collecting amount of exhaust particulates reaches a predetermined 
amount, the control valve 8 turns to open the by-pass passage 40b. As a 
result, almost all of the exhaust gases flow into the by-pass passage 40b 
as shown in FIG. 4. At the same time, an electric current is applied to 
the heaters 6 to ignite the exhaust particulates collected near the 
upstream end surface of the filter member 5. The combustion of the 
particulates expands to those collected in the downstream portion of the 
filter member 5. Consequently, the filter member 5 is regenerated. 
When the regeneration of the filter member 5 is completed, the control 
valve 8 turns to close the by-pass passage 40b. Then, almost all of 
exhaust gases begin to flow into the filter member 5 again and the filter 
member 5 restarts collecting the exhaust particulates. 
FIGS. 5 and 6 illustrate a second embodiment of the exhaust particulates 
cleaning device according to the present invention. 
The by-pass passage 40b is formed separately from the casing 4. 
The control valve 8 is disposed in the by-pass passage 40b. 
The other structure and operation of the second embodiment are 
substantially equal to those of the first embodiment. 
According to the second embodiment, the by-pass passage 40b can be formed 
only by slightly changing the structure of the conventional casing for 
retaining the filter member. 
FIGS. 7 and 8 illustrate a third embodiment of the exhaust particulates 
cleaning device according to the present invention. 
In the third embodiment, the by-pass passage 40b is formed so as to have a 
crescent cross section. 
Since the surface area of the separator 7 which defines the exhaust gas 
passages 40a, 40b is large, the heat of the exhaust gases flowing through 
the by-pass passage 40b is easily transmitted to the filter member 5 at 
the filter regenerating time. Therefore, the filter member 5 is 
effectively maintained at higher temperature. 
FIGS. 9, 10, 11 illustrate a fourth embodiment of the exhaust particulates 
cleaning device according to the present invention. 
In the fourth embodiment, the casing 4 comprising the exhaust gas passage 
40a for retaining the filter member 5 and the by-pass passage 40b wherein 
the control valve 8 is disposed, is mounted on the outlet end portion of 
the exhaust manifold 2. 
The exhaust gas passage 40a and the by-pass passage 40b are separated by 
the separator 7. 
The other sturcture of the fourth embodiment is substantially equal to that 
of the first embodiment. 
According to the fourth embodiment, the filter member 5 is positioned close 
to the outlet end portion of the exhaust manifold 2. Therefore, higher 
temperature exhaust gases flow into the filter member 5 so that the filter 
member 5 can be maintained at higher temperature. In addition, the casing 
4 can be made compact. 
FIG. 12 illustrates a fifth embodiment of the exhaust particulates cleaning 
device according to the present invention. 
The space within the casing 4 is divided into two exhaust gas passages 40a, 
40b by the separator 7 which extends toward the inlet end of the casing 4. 
In the exhaust gas passage 40a having a larger cross sectional area, the 
filter member 5 is disposed. 
The exhaust gas control valve 8 is turnably fixed to the upper stream end 
of the separator 7. The valve 8 has such a shape and size that a small gap 
exists between the valve 8 and the inner wall of the casing 4 when the 
valve 8 closes the exhaust gas passage 40a. Therefore, when the exhaust 
gas passage 40a is closed by the valve 8, a small amount of exhaust gases 
flow into the exhaust gas passage 40a. 
The other structure of the fifth embodiment is substantially equal to that 
of the first embodiment. 
In the fifth embodiment, at the exhaust particulates collecting time, the 
exhaust gas passage 40b is closed by the control valve 8 so that all of 
the exhaust gases flow into the filter member 5. At the filter member 
regenerating time, the exhaust gas passage 40a is closed by the valve 8 
and an electric current is applied to the heaters 6. 
At this time, a small amount of exhaust gases is supplied to the filter 
member 5 through the gap between the valve 8 and the casing 4 so as not to 
reduce the heating efficiency of the heaters 6. 
The collected exhaust particulates are ignited by the heaters 6 and the 
combustion of the collected particulates continues since oxygen is 
supplied to the filter member 5 from the exhaust gases flowing thereinto. 
FIG. 13 illustrates a sixth embodiment of the exhaust particulates cleaning 
device according to the present invention. 
In the sixth embodiment, the exhaust gas passages 40a, 40b are communicated 
with each other through a cylindrical pipe. 
Into the cylindrical pipe, the control valve 8 of a piston type is slidably 
inserted. 
According to the sixth embodiment, the exhaust gas amount flowing into the 
exhaust gas passages 40a, 40b is controlled by the upward and downward 
movement of the control valve 8. 
FIG. 14 illustrates a seventh embodiment of the exhaust particulates 
cleaning device according to the present invention. 
In the seventh embodiment, the casing 4 which retains the filter member 5 
and is provided with the by-pass passage 40b like the fourth embodiment 
shown in FIG. 10 is mounted to the outlet end portion of the exhaust 
manifold 2. 
The exhaust gas control valve 8 is turnably fixed to the end of the 
separator 7 which extends toward the outlet end of the casing 4. 
As shown in the seventh embodiment, by providing the control valve 8 on the 
downstream side of the exhaust gas passages 40a, 40b, the exhaust gas 
amount flowing into each of the passages 40a, 40b can be also controlled. 
Hereinafter, a valve actuator for supplying the most proper amount of 
exhaust gases into the filter member at the filter member regenerating 
time in accordance with the engine driving condition, will be explained. 
As described above, a small amount of exhaust gases are required for 
continuing the combustion of the collected particulates at the filter 
member regenerating time. 
For example, in the first embodiment shown in FIGS. 2 to 4, the exhaust 
gases of which amount is determined by the difference in pressure loss 
between the exhaust gas passage 40a and the by-pass passage 40b, flow into 
the exhaust gas passage 40a at the filter member regenerating time. 
In the fifth embodiment shown in FIG. 12, by forming the valve 8 so as to 
produce a small gap between the valve 8 and the inner wall of the casing 4 
when the valve 8 closes the exhaust gas passages 40a, a small amount of 
exhaust gases flow into the exhaust gas passage 40a at the filter member 
regenerating time. 
The exhaust gas amount discharged from the engine, broadly changes in 
accordance with the driving condition such as an engine rotating speed. 
Therefore, when the engine rotaing speed is high, an excess amount of 
exhaust gases are supplied to the filter member 5 at the filter member 
regenerating time so that the heating efficiency of the heater member is 
reduced. 
When the engine rotating speed is low, the supplying amount of exhaust 
gases is too small to continue the combustion of the ignited exhaust 
particulates. 
FIG. 15 is a graph showing the relation between the exhast gas amount 
discharged from the engine, which is plotted on the abscissa and the 
exhaust gas amount passing the filter member, which is plotted on the 
ordinate. The region defined by oblique lines shows the region of the 
exhaust gas amount suitable for the regeneration of the filter member. 
The curve C shows the above relation when the control valve 8 of the first 
embodiment is full-open. In this case, when the exhaust gas amount 
discharged from the engine is small, a sufficiently large amount of 
exhaust gases enough to regenerate the filter member are not supplied to 
the filter member. 
The curve B shows the above relation when the control valve 8 is half-open. 
In this case, even when the discharged exhaust gas amount is small, enough 
exhaust gas amount passing the filter member to regenerate the filter 
member can be obtained. 
Namely, when the exhaust gas amount discharged from the engine is large, 
the valve 8 should be full-open while when the above amount is small, the 
valve 8 should be half-open. 
As described above, by controlling the opening degree of the by-pass 
passage in accordance with the exhaust gas amount discharged from the 
engine, the filter member can be effectively regenerated in any engine 
driving condition. 
FIG. 16 illustrates a first embodiment of a valve actuator which is 
employed in the present invention. 
In the first embodiment, the valve actuator comprises a first vacuum 
housing 21 and a second vacuum housing 22, which are separated from each 
other. Within the vacuum housings 21, 22, a bellowphragms 23, 24 and 
springs 25, 26 are accomodated, respectively. A rod 27 driven by the 
bellowphragm 23 is coaxially opposed to a rod 28 driven by the 
bellowphragm 24. The rods 27 and 28 relatively moves by the distance 
D.sub.1. 
When the valve 8 is set half-open shown by "B" in FIG. 16, an electric 
current is applied to an electromagnetic valve V.sub.1 to apply a negative 
pressure from a vacuum pump V.P. to the first vacuum housing 21 through an 
opening 21a. Then, the rod 27 moves by the distance D.sub.1 upward so that 
the arm 29 connected to the rod 27 turns to set the valve 8 into the 
position "B". 
When the valve 8 is set full-open shown by C in FIG. 16, an electric 
current is applied to an electromagnetic valve V.sub.2 to apply a negative 
pressure from the vacuum pump V.P. to the second vacuum housing 22 through 
an opening 22a. The rod 28 is pulled upward by the maximum stroke of 
D.sub.2 so that the arm 29 connected to the rod 28 through the rod 27 
turns to set the valve 8 into the position "C". 
When the exhaust particulates are collected by the filter member 5, the 
valve 8 is set closed (position "A"). When the engine rotating speed is 
under a predetermined value so that the exhaust gas amount discharged from 
the engine is small at the filter member regenerating time, an electric 
current is applied to the electromagnetic valve V.sub.1 to set the valve 8 
half-open (position "B") and when the engine rotating speed is over a 
predetermined value, an electric current is applied to the electromagnetic 
valve V.sub.2 to set the valve 8 full-open (position "C"). 
The opening degree of the half-opening valve 8 is freely controlled by 
adjusting the stroke D.sub.1 in accordance with the engine driving 
condition. 
FIG. 17 illustrates a second embodiment of the valve actuator. 
In the second embodiment, the first vacuum housing 21 is formed so as to 
surround the second vacuum housing 22. By applying a negative pressure to 
the housing 21 or 22, the second housing 22 or the rod 27 moves by the 
stroke D.sub.1 or D.sub.2. 
FIG. 18 illustrates a third embodiment of the valve actuator. 
In the third embodiment, an actuator 30 for setting the valve 8 half-open, 
and an actuator 31 for setting the valve 8 full-open are separately 
provided. 
The rod 34 of the actuator 30 is turnably connected to the arm 35 which is 
turnably supported by a rotating shaft 8a of the valve 8. 
The rod 33 of the actuator 31 is turnably connected to the arm 32 which is 
fixed to the shaft 8a. 
When the valve 8 is set half-open, a negative pressure is applied to the 
actuator 30 to pull the rod 34 downward so that the arm 35 turns. Then, a 
projecting portion 35a formed in the arm 35 engages with the arm 32 to 
turn the arm 32 counterclockwise. Consequently, the valve 8 turns to its 
half-open position. 
When the valve 8 is full-open, a negative pressure is applied to the 
actuator 31 to pull the arm 33 upward so that the arm 32 disengages from 
the projecting portion 35a and turns counterclockwise. Consequently, the 
valve 8 turns to its full-open position. 
The opening degree of the valve 8 can be controlled by detecting the engine 
rotating speed and the intake air amount. 
In the above embodiments, the exhaust gas amount passing the filter member 
is controlled by detecting the change of the exhaust gas amount discharged 
from the engine by some means and adjusting the opening degree of the 
control valve in accordance with the detected data. 
In the following embodiment, the control valve itself has an exhaust gas 
amount controlling property. 
FIGS. 19 and 20 illustrate a fourth embodiment of the valve actuator which 
controls the exhaust gas amount passing the filter member into a proper 
amount regardless of the engine driving condition at the filter member 
regenerating time. 
As shown in FIG. 19, in the exhaust gas passage 40a, the filter member 5 is 
disposed. 
At the downstream connecting portion of the exhaust gas passage 40a and the 
by-pass passage 40b, the valve 8 is provided. 
The differential pressure between the upstream side and the downstream side 
of the filter member 5 changes nearly in proportion to the flow rate of 
exhaust gases passing the filter member 5. 
Since the valve 8 is provided at the downstream end of the by-pass passage 
40b so as to face the downstream end of the exhaust gas passage 40a, the 
differential pressure between the upstream side and the downstream side of 
the valve 8 is nearly equal to that of the filter member 5. 
Therefore, by keeping the differential pressure between the upstream side 
and the downstream side of the valve 8 constant in any driving condition, 
the differential pressure of the filter member 5 can be also kept constant 
so that the exhaust gas amount passing the filter member 5 can be kept 
constant. 
The valve 8 is fixed to one end of a first arm 36 while the other end of 
the arm 36 is fixed to the shaft 39 which is turnably supported by the 
casing 4. 
To the shaft 39, the central portion of a second arm 41 is fixed. And one 
end of a third arm 42 is turnably supported by the shaft 39. 
One end of a spring 43 is fixed to the second arm 41 so as to urge the arm 
41 counterclockwise while the other end of the spring 43 is fixed to the 
casing 4. 
One end of the rod 44 is turnably supported by the other end of the third 
arm 42 while the other end of the rod 44 is connected to a bellowphragm 51 
of an actuator 50. 
In the other end of the second arm 41, a projecting portion 45 is formed so 
as to contact with the third arm 42 when the arm 42 turns. 
At the exhaust particulates collecting time, the rod 44 is pushed upward by 
a spring 53 of the actuator 50 through the bellowphragm 51. The third arm 
42 turns counterclockwise about the shaft 39 to engage with the projecting 
portion 45. As a result, the arm 41 turns with the arm 42 so that the 
valve 8 is pushed to the downstream end of the by-pass passage 40b. 
Therefore, the by-pass passage 40b is closed and all of the exhaust gases 
flow into the filter member 5. 
At the filter member regenerating time, a negative pressure is applied to a 
vacuum housing 52 of the actuator 50 to pull the bellowphragm 51 downward. 
The third arm 42 connected to the bellowphragm 51 through the rod 44 
disengages from the projecting portion 45 and turns clockwise as shown in 
FIG. 20. 
Therefore, at this time, the valve 8 is pushed toward the downstream end of 
the by-pass passage 40b only by the spring 43. 
Since the biasing force of the spring 43 is not so large, the exhaust gas 
pressure applied from the by-pass passage 40b overcomes the biasing force 
of the spring 43 to set the valve 8 half-open. 
The opening degree of the valve 8 changes in accordance with the amount of 
exhaust gases flowing into the by-pass passage 40b. Consequently, the 
pressure difference between the upstream side and the downstream side of 
the valve 8 can be kept nearly constant in any engine driving condition. 
Therefore, the pressure difference between the upstream side and the 
downstream side of the filter member 5 can be also kept nearly constant so 
taht the exhaust gas amount passing the filter member 5 at the filter 
member regenerating time can be kept constant regardless of the exhaust 
gas amount discharged from the engine. 
The constant exhaust gas amount passing the filter member 5 can be adjusted 
by selecting the biasing force of the spring 43. 
A weight 49 is provided at one end of the arm 41 for preventing the valve 8 
from vibrating due to the pulsation of exhaust gases. 
FIGS. 21, 22 illustrate a fifth embodiment of the valve actuator. 
In this embodiment, a butterfly valve 80 is further provided for 
restricting the exhaust gas amount passing the filter member at the filter 
member regenerating time. 
At the filter member regenerating time, the opening degree of the valve 8 
which is biased by the spring 43, changes in accordance with the 
differential pressure between the upstream side and the downstream side of 
the filter member. 
When the filter member having a low flowing resistance is used, the 
differential pressure between the upstream side and the downstream side of 
the filter member must be made especially small at the filter member 
regenerating time by decreasing the biasing force of the spring 43. 
However, when the biasing force of the spring 43 is decreased, the rotating 
resistance of the shaft 39 relatively increases so that the opening degree 
of the valve 8 cannot be accurately adjusted. 
The valve 80 is provided for preventing the occurrance of the adjusting 
error. The valve 80 closes the exhaust gas passage 40a at the filter 
member regenerating time to increase the apparent flowing resistance of 
the filter member. 
By providing the valve 80 in the exhaust gas passage 40a, the exhaust gas 
amount passing the filter member can be accurately controlled without 
decreasing the biasing force of the spring 43. 
In order to operate the valve 80, a second valve actuator 55 of the same 
type as that of the actuator 50, is provided. In the exhaust gas passage 
40a, the valve 80 provided with a plurality of small passages 80a is 
disposed on the downstream side of the filter member (not shown). 
The second actuator 55 comprises a bellowphragm 56 to which one end of the 
rod 46 is fixed. 
The other end of the rod 46 turnably connected to one end of an arm 47 
while the other end of the arm 47 is fixed to a rotating shaft 80b of the 
valve 80. 
The other structure of this embodiment is substantially equal to that of 
the fourth embodiment shown in FIG. 20. 
FIG. 21 illustrates the operation of the valves 8, 80 at the filter member 
regenerating time. 
A negative pressure is applied to vacuum housings 52, 57 of the valve 
actuators 50, 55, respectively. As a result, the valve 8 closes the 
by-pass passage 40b only by the biasing force of the spring 43 and the 
valve 80 closes the exhaust gas passage 40a on the downstream side of the 
filter member. 
Differential pressure between the upstream side and the downstream side of 
the filter member increases as well as that between the upstream side and 
the downstream side of the valve 8 so that the valve 8 opens the by-pass 
passage 40a, overcoming the biasing force of the spring 43. 
The opening degree of the valve 8 changes in accordance with the change of 
pressure difference. Therefore, in any driving condition, a proper amount 
of exhaust gases pass the filter member. 
FIG. 22 illustrates the operation of the valves 8, 80 at the exhaust 
particulates collecting time. 
At this time, a negative pressure is not supplied to the actuators 50, 55, 
respectively so that the valve 8 closes the by-pass passage 40b and the 
valve 80 is fully opened. 
As described above, according to the present invention, almost all amount 
of exhaust gases pass the filter member at the exhaust particulates 
collecting time, and exhaust particulates contained therewithin are 
collected by the filter member. 
At the filter member regenerating time, the exhaust gas amount passing the 
filter member can be accurately adjusted into the minimum amount anough to 
continue the combustion of the collected exhaust particulates. 
Therefore, the heating efficiency of the heater is not reduced. 
In addition, since exhaust gases containing enough amount of oxygen to 
continue the combustion of the exhaust particulates are supplied to the 
filter member at the filter member regenerating time, all of the exhaust 
particulates can be completely burnt off. 
Furthermore, according to the present invention, at the filter member 
regenerating time, the most proper amount of exhaust gases can be supplied 
to the filter member regardless of the change of the exhaust gas amount 
discharged from the engine.