JPH1073053A - Intake throttle device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To mechanically control the opening or closing motion of a throttle valve disposed in an intake pipe corresponding to the EGR temperature and the intake negative pressure which fluctuate according to the operational conditions of the engine. SOLUTION: An intake throttle device is provided for an internal combustion engine having an exhaust-gas recirculation system of extracting part of exhaust gas from the exhaust system and returning it to the downstream side of a throttle valve 3 disposed in an intake pipe 1. The intake throttle device includes a torsion spring 7 formed out of a shape memory alloy for continuously urging the throttle valve 3 in its closed side. The torsion spring 7 is adapted to close the throttle valve 3 when the temperature of EGR gas is lower and to open it when the temperature is higher. Even when the temperature of EGR gas is lower, if the intake negative pressure acting on the throttle valve 3 is higher, however, the throttle valve 3 operates to open by the intake negative pressure against the torsion spring 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention includes an exhaust gas recirculation device (hereinafter, referred to as EGR) for extracting a part of exhaust gas from an exhaust system and recirculating the exhaust gas downstream of a throttle valve provided in an intake pipe. The present invention relates to an intake throttle device for an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, as a measure for purifying NOx in exhaust gas, a part of the exhaust gas is taken out of an exhaust system, and the temperature, timing, flow rate, etc. are controlled and the exhaust gas is recycled to an intake system. A recirculation device (hereinafter, referred to as EGR) is known. FIG. 9 shows exhaust gas (hereinafter referred to as EG) which is recirculated to the intake system.
1 shows a conventional intake throttle device for controlling the inflow amount of R gas).

As shown in the drawing, in a conventional intake throttle device, an EGR gas taken out of an exhaust system is returned to the intake pipe 31 downstream of a throttle valve (butterfly valve) 32 provided in the intake pipe 31. E with EGR valve 33
The GR pipe 34 is connected. If exhaust gas is mixed into the intake air, NOx can be reduced, but on the other hand, the amount of air is insufficient.Therefore, when the engine that requires high output has a high load, mixing of the exhaust gas into the intake air should be suppressed. ing. Further, at low temperatures, the throttle valve 32 is controlled to the closed side so that the EGR gas easily flows into the intake pipe 31, and the idle stability at the time of low temperature starting is improved.

Conventionally, the above control is performed by detecting the operating state of the engine by various sensors and controlling the negative pressure regulating valve 36 by a signal output from a control circuit 35 to reduce the negative pressure supplied from the vacuum pump. Adjust the EGR valve 3
3 and the throttle valve 32 are operated through the actuator 37, respectively.

[0005]

However, the above-described electric control system using the conventional control circuit has a problem that the control system becomes complicated and expensive, which is not preferable.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a simple and inexpensive intake throttle device.

[0007]

Means for Solving the Problems In order to solve the above problems, the present invention is configured as follows. That is, the invention of claim 1 is directed to an internal combustion engine having an exhaust gas recirculation device that takes out a part of exhaust gas from an exhaust system and recirculates via an EGR valve to a downstream side of a throttle valve provided in an intake pipe. The intake throttle device includes a temperature-sensitive responsive member that opens and closes the throttle valve by being deformed in accordance with the level of the temperature. It is characterized in that it is sometimes deformed to the valve opening side.

When the load of the engine is low, such as during idling operation, the exhaust gas temperature is low because the fuel injection amount is small. Therefore, when the engine is under a low load, the temperature-sensitive responsive member is deformed so as to close the throttle valve, thereby generating an intake throttle and promoting the inflow of the EGR gas. On the other hand, the exhaust gas temperature is high because the fuel injection amount is large when the engine requires a relatively high output at medium / high load. Therefore, when the engine is at a medium or high load, the temperature-sensitive responsive member is deformed so as to open the throttle valve, and the intake throttle is released to suppress the inflow of the EGR gas and prevent the output from decreasing. That is, according to the first aspect of the invention, the throttle valve is mechanically opened and closed according to the level of the exhaust gas temperature, and the EGR flowing into the suction pipe
The amount of gas can be controlled.

According to a second aspect of the present invention, there is provided an internal combustion engine provided with an exhaust gas recirculation device for extracting a part of exhaust gas from an exhaust system and returning the exhaust gas to a downstream side of a throttle valve provided in an intake pipe through an EGR valve. In the intake throttle device, a temperature-sensitive responsive member that opens and closes the throttle valve by deforming according to the temperature is provided, and the temperature-sensitive responsive member is deformed to the valve closing side when the intake temperature is low, It is characterized in that it is configured to be deformed to the valve opening side at high temperature.

When the engine is started at a low temperature, the temperature of the intake air (fresh air) taken into the intake pipe is low because the temperature around the engine is low. Therefore, the temperature-sensitive responsive member is deformed to the side that closes the throttle valve, and generates an intake throttle to promote the inflow of the EGR gas. As a result, the temperature of the combustion chamber is easily increased, and the warm-up property is improved, and the generation of white smoke is reduced. On the other hand, after the warm-up operation, when the intake air temperature reaches a set high temperature range as the ambient temperature of the engine rises, the temperature-sensitive responsive member deforms to the side that opens the throttle valve, releases the intake throttle, and releases the EGR gas. Suppress the inflow of water. That is, according to the second aspect of the present invention, it is possible to mechanically open and close the throttle valve according to the level of the intake air temperature and control the amount of EGR gas flowing into the intake pipe.

According to a third aspect of the present invention, in the intake throttle device according to the first or second aspect, the temperature-sensitive responsive member is formed by a spring made of a shape memory alloy. In such a configuration, the spring made of the shape memory alloy is deformed according to the level of the exhaust gas temperature or the intake air temperature to control the opening and closing of the throttle valve as in the first or second aspect of the invention. In addition, when the engine is rotating at high speed, the intake negative pressure of the intake manifold is large and EGR gas is likely to flow in, so at this time, even if the exhaust gas temperature or the intake temperature is low,
The intake negative pressure overcomes the spring and opens the throttle valve to open,
Control is performed to suppress excessive inflow of the EGR gas amount.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be specifically described below with reference to FIGS. FIG. 1 is an explanatory diagram of an intake throttle device according to the present embodiment, FIG. 2 is an explanatory diagram of an operation of the intake throttle device, and FIG.
(B) shows when the intake throttle is released, and (C) shows when the EGR valve is closed at high speed and high load. FIG. 3 is a graph showing the relationship between the EGR gas temperature and the valve opening and the relationship between the intake negative pressure and the valve opening. As shown in FIG.
A throttle valve (butterfly valve) 3 that is rotatable about a shaft 2 is provided therein. An EGR pipe 5 provided with an EGR valve 4 is connected to a downstream side of the throttle valve 3 in the intake pipe 1 so that EGR gas extracted from an exhaust system is introduced.

Outside the intake pipe 1, the shaft 2 of the throttle valve 3
Is provided at one end thereof with a torsion spring 7 made of a shape memory alloy as a temperature-sensitive responsive member for opening and closing the throttle valve 3.
One end of the torsion spring 7 is fixed to the shaft 2 side, and the other end is fixed to the wall side of the intake pipe 1. And the torsion spring 7
Is covered by a casing 6 provided at the end of the EGR pipe 5, and comes into direct contact with the EGR gas introduced from the exhaust system, and is deformed according to the EGR gas temperature.

That is, the torsion spring 7 is assembled such that a spring force in a closing direction acts on the throttle valve 3 in the steady state when the temperature is low. That is, the throttle valve 3 is deformed into a shape that opens the throttle valve (a direction in which the spring is involved).

Although the temperature of the exhaust gas is slightly different depending on the model, the EGR gas needs to be cooled to 400 ° C. or less in view of the reliability and durability of the EGR valve 4. Therefore, the EG introduced into the intake pipe 1
R gas has a maximum of around 400 ° C. and a minimum of 100 to 200
° C. Accordingly, the deformation temperature of the torsion spring 7 is appropriately set within the range between the maximum temperature and the minimum temperature.

Further, as the engine speed increases, the intake negative pressure of the intake manifold also increases in proportion to the increase of the engine speed. Therefore, this phenomenon is utilized, and when the intake negative pressure exceeding a predetermined magnitude acts on the throttle valve 3, The spring constant of the torsion spring 7 is set so that the throttle valve 3 is opened. As a result, at the time of low-temperature high-speed rotation, the intake negative pressure increases, and the exhaust gas pressure (hereinafter referred to as the back pressure) increases, and E
The shortage of air due to the easy flow of GR gas is eliminated. In FIG. 1, 8
Indicates a bush and 9 indicates a retaining ring.

The intake throttle device according to the present embodiment is configured as described above, and its operation and effect will be described below. During the operation of the engine, EGR which is taken out of the exhaust system by the EGR pipe 5 and recirculated into the intake pipe 1
When the gas temperature is low and the intake negative pressure is low, the torsion spring 7 made of a shape memory alloy is deformed into a shape that closes the throttle valve 3. In this case, the throttle valve 3 is held at the minimum opening degree by a stopper not shown.

That is, when the engine is running at low speed and low load such as idling, the amount of fuel injection is small and the exhaust gas temperature is low. Further, since the intake negative pressure is small and the back pressure is also low, the EGR gas hardly flows into the intake pipe 1. Accordingly, in such a case, the throttle valve 3 operates to the closing side, and as shown in FIG. 2A, an intake throttle that suppresses the inflow of fresh air is generated to promote the inflow of EGR gas.

When the rotational speed of the engine increases, the intake negative pressure increases and the back pressure increases, so that the EGR gas easily flows in and the inflowing air becomes insufficient. Therefore, EG
Even when the R gas temperature is low, when the intake negative pressure acting on the throttle valve 3 increases, the intake negative pressure overcomes the torsion spring 7 to rotate the throttle valve 3 to the open side, and as shown in FIG. As shown in (B), the intake throttle is released. This allows E
Since the inflow of the GR gas is suppressed and the air easily enters, the shortage of the air is eliminated.

On the other hand, when the engine requiring a high output has a high load, the fuel injection amount is large, so that the exhaust gas temperature becomes high.
Therefore, at this time, the torsion spring 7 is deformed and the throttle valve 3 is operated to the open side, so that the intake throttle is released and the EGR gas flows more than necessary as shown in FIG. , The shortage of air is prevented and the output is prevented from lowering.

When the engine is running at high speed and high load, the EGR valve 4 is closed and EGR gas does not flow into the intake pipe 1. At this time, the throttle valve 3 rotates to the opening side due to the deformation of the torsion spring 7 or the intake negative pressure, and the intake throttle is released as shown in FIG. 2C. Thus, only the air in which the EGR gas is not mixed is sent to the engine, so that a high output can be obtained.

As described above, according to the present embodiment, by forming the torsion spring 7 which always urges the throttle valve 3 to the closing side from a shape memory alloy, the exhaust gas can be exhausted as shown in the graph of FIG. When the gas temperature is low, the throttle valve 3 is closed and EG
The control of opening the throttle valve 3 to suppress the inflow of the EGR gas can be mechanically performed by promoting the inflow of the R gas and opening the throttle valve 3 when the temperature of the exhaust gas is high and the intake negative pressure is large.

Next, a second embodiment of the present invention will be described with reference to FIGS.
Explanation will be given based on FIG. In this embodiment,
As shown in FIGS. 4 and 5, outside the intake pipe 1,
The throttle valve 3 is closed by a torsion spring 11 made of spring steel which is hooked at one end to the outer wall of the intake pipe 1 and at the other end to a first disk 10 fixed to the shaft 2 of the throttle valve 3. Has been energized. A second disk 12 is rotatably mounted on the shaft 2, and an engagement pin 13 provided on the first disk 10 is provided in a long arc-shaped escape hole 12 a formed in the second disk 12. Are slidably engaged.

On the other hand, a cylindrical body 14 is provided on the outer wall of the intake pipe 1 by EG.
A protruding end of a piston rod 17 slidably fitted into the cylindrical body 14 is attached to the second disk 12 so as to be in contact with the R gas so as to be in contact with the R gas. The pin 18 is connected to a long hole 18 a via a pin 19. As shown in FIG. 6, the cylindrical body 14 has a double structure composed of an inner cylinder 15 and an outer cylinder 16 fitted to the inner cylinder. A thermo-wax 20 is sealed as a temperature-sensitive responsive member that expands and solidifies and contracts at low temperatures, and a return compression coil spring 21 is housed on the opposite side. The other configuration is the same as that of the first embodiment.

The second embodiment is configured as described above, and FIG. 4A shows a case where the EGR gas is at a low temperature. At this time, the thermo wax 20 solidifies and contracts, the piston rod 17 is pushed out of the cylinder 14 by the compression coil spring 21, and the escape hole 12a is
The second disk 12 is rotated in a direction away from the valve (a valve closing direction). Therefore, the throttle valve 3 whose regulation has been released is rotated to the closing side by the torsion spring 11, and an intake throttle is generated.
Promote the introduction of EGR gas. At this time, the engagement pin 13 contacts the end of the escape hole 12a.

On the other hand, when the EGR gas is at a high temperature, the thermo wax 20 liquefies and expands, and the piston rod 17 is drawn into the cylinder 14 against the compression coil spring 21, and the second
(B) of FIG. 4 in order to rotate the circular plate 12 in the valve opening direction.
1, the first disk 10 is rotated integrally with the second disk 12 via the engagement pins 13. Therefore, the throttle valve 3
Is rotated to the open side against the torsion spring 11, and the intake throttle is released.

Further, even when the EGR gas temperature is low, when the intake negative pressure acting on the throttle valve 3 is large, the throttle valve 3 opens against the torsion spring 11 by the intake negative pressure. Is rotated. In this case, the first disk 10
Only moves along the escape hole 12a of the second disk 12, and the throttle valve 3 is turned to the open side by the intake negative pressure without being restricted by the second disk 12. As a result, the intake throttle is released. Thus, the second
According to this embodiment, the same operation and effect as those of the first embodiment can be obtained.

Next, a third embodiment of the present invention will be described with reference to FIGS. In this embodiment, a torsion spring 22 made of a shape memory alloy as a temperature-sensitive responsive member for opening and closing the throttle valve 3 is provided in the intake pipe 1. The torsion spring 22 has one end of the throttle valve 3.
And the other end is fixed to the inner wall of the intake pipe 1 and deforms according to the intake air temperature in the intake pipe 1.

The torsion spring 22 has a steady state at a low temperature,
The throttle valve 3 is assembled so that a spring force in the closing direction acts on the throttle valve 3 in the steady state, and is deformed into a predetermined shape stored in advance at a high temperature, that is, a shape in which the throttle valve 3 is opened (a direction in which the spring is involved). ing. Also, a torsion spring 2
Reference numeral 2 denotes a spring constant set so that when the intake negative pressure of the intake manifold exceeding a predetermined size acts on the throttle valve 3, the throttle valve 3 is opened by losing the intake negative pressure. Note that the other configuration is the same as that of the first embodiment, and thus the same reference numerals are given and the description thereof is omitted.

As described above, the configuration of the third embodiment is as follows.
The opening and closing of the throttle valve 3 is controlled by the intake air temperature of fresh air taken into the intake pipe 1. Therefore,
When starting the engine, around the engine (in the engine room)
Is low, the temperature of fresh air introduced into the intake pipe 1 via the air cleaner is also low. Therefore, when the intake air temperature is low and the intake negative pressure is low, the torsion spring 22 made of a shape memory alloy is deformed in a direction to close the throttle valve 3, and as shown in FIG. Is generated to promote the inflow of the EGR gas.

As described above, when the EGR gas is introduced into the intake system at a low temperature, the room temperature of the combustion chamber is easily increased, and the warm-up is promoted, and the combustion temperature is increased to generate white smoke. Is reduced, and the idle stability at the time of low temperature start can be improved. It should be noted that such an effect of improving the idle stability at the time of the low temperature start can be similarly obtained in the first and second embodiments.

On the other hand, after the warm-up operation, when the temperature around the engine in the engine room rises and the intake air temperature reaches a high temperature setting range, the torsion spring 22 deforms to open the throttle valve 3, As shown in FIG. 8B, the intake throttle is released to suppress the inflow of the EGR gas, thereby preventing a shortage of air and preventing a decrease in output.

When the engine speed is increased, the intake negative pressure is increased and the back pressure is increased, so that the EGR gas is easily introduced and the inflow air is insufficient. Therefore, even when the intake air temperature is low, if the intake negative pressure acting on the throttle valve 3 increases, the intake negative pressure overcomes the torsion spring 7 and rotates the throttle valve 3 to the open side. Also, as shown in FIG. 8B, the intake throttle is released. This allows
Since the inflow of the EGR gas is suppressed and the air easily enters, the shortage of the air is eliminated.

When the engine is running at high speed and high load, the EG
The R valve 4 is closed, and the EGR gas does not flow into the intake pipe 1. At this time, the throttle valve 3 rotates to the open side due to the deformation of the torsion spring 22 or the intake negative pressure, and the intake throttle is released as shown in FIG. 8C. Thus, only the air in which the EGR gas is not mixed is sent to the engine, so that a high output can be obtained.

As described above, also in the third embodiment, the torsion spring 22 for constantly biasing the throttle valve 3 to the closed side is formed from a shape memory alloy, thereby providing the first embodiment. Similarly to the case, as shown in the graph of FIG. 3, when the intake air temperature is low, the throttle valve 3 is closed to promote the inflow of EGR gas, and when the intake air temperature is high and the intake negative pressure is large, the throttle valve 3 is turned on. The control of opening to suppress the inflow of the EGR gas can be performed mechanically.

In the embodiment, the opening / closing control of the throttle valve 3 is performed by the deformation of the temperature-sensitive responsive member due to the temperature and the intake negative pressure. However, the temperature-sensitive responsive member is controlled only by the temperature regardless of the intake negative pressure. The shape may be changed correspondingly.
In the embodiment, at the time of high speed rotation and high load, the EGR
Although the case where the valve 4 is closed and the EGR gas does not flow into the intake pipe 1 has been described, the EGR valve 4 may be omitted.

In the first and second embodiments, the torsion spring 7 made of a shape memory alloy as the temperature-responsive member and the cylindrical body 14 containing the thermowax 13 are made to contact the EGR gas directly. Although it is shown in the case where the EGR gas temperature is detected, the portion may be disposed outside the tube as long as the portion can detect the EGR gas temperature. Further, in the second embodiment, the piston of the piston rod 17 may be changed to a diaphragm. Further, as the temperature-sensitive responsive member, a bimetal may be used in addition to the shape memory alloy and the thermowax.

[0038]

As described in detail above, according to the present invention,
Since the opening and closing of the throttle valve in the intake pipe can be controlled by a temperature-sensitive responsive member that changes in accordance with the EGR gas temperature or the intake air temperature, a simple and inexpensive intake throttle device can be provided.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an intake throttle device according to a first embodiment.

FIGS. 2A and 2B are explanatory diagrams of the operation of the intake throttle device, wherein FIG.
(B) shows the time of intake throttling with the GR valve open.
(C) shows when the intake throttle is released with the EGR valve open, and (C) shows when the intake throttle is released with the EGR valve closed.

FIG. 3 is a graph showing a relationship between an EGR gas temperature and a valve opening and a relationship between an intake negative pressure and a valve opening.

FIGS. 4A and 4B are explanatory diagrams of an intake throttle device according to a second embodiment, in which FIG. 4A shows the state of the intake throttle, and FIG. 4B shows the state of the release of the intake throttle.

FIG. 5 is an enlarged perspective view of a portion A in FIG. 4;

FIG. 6 is an enlarged sectional view of a portion B in FIG. 4;

FIG. 7 is an explanatory diagram of an intake throttle device according to a third embodiment.

FIGS. 8A and 8B are explanatory diagrams of the operation of the intake throttle device, wherein FIG.
(B) shows the time of intake throttling with the GR valve open.
(C) shows when the intake throttle is released with the EGR valve open, and (C) shows when the intake throttle is released with the EGR valve closed.

FIG. 9 is an explanatory diagram of a conventional intake throttle device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Intake pipe 3 ... Throttle valve 5 ... EGR pipe 7 ... Torsion spring (temperature-sensitive responsive member)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location F02M 25/07 520 F02M 25/07 520Z

Claims (3)

[Claims] 1. A method for removing a part of exhaust gas from an exhaust system,
In an intake throttle device of an internal combustion engine having an exhaust gas recirculation device that recirculates downstream of a throttle valve provided in an intake pipe via an EGR valve, the throttle valve is opened and closed by being deformed according to the level of temperature. An intake throttle device comprising a temperature-sensitive responsive member that operates, wherein the temperature-sensitive responsive member is deformed toward the valve closing side when the temperature of the exhaust gas is low, and is deformed toward the valve opening side when the temperature of the exhaust gas is high. 2. A part of exhaust gas is taken out from an exhaust system,
In an intake throttle device of an internal combustion engine having an exhaust gas recirculation device that recirculates downstream of a throttle valve provided in an intake pipe via an EGR valve, the throttle valve is opened and closed by being deformed according to the level of temperature. An intake throttle device comprising a temperature-sensitive responsive member that operates, wherein the temperature-sensitive responsive member is deformed toward the valve closing side when the intake air temperature is low, and is deformed toward the valve opening side when the intake air temperature is high. 3. The intake throttle device according to claim 1, wherein the temperature-responsive member is formed of a spring made of a shape memory alloy.