JPS6263164A - Egr controller for internal combustion engine - Google Patents

Abstract

PURPOSE:To improve reliability by constituting a negative pressure control valve for controlling an EGR valve from a movable iron core inserted in slidable ways into a valve body and a means for controlling the communication between an EGR pipe, vacuum pipe, and an atmosphere passage according to the shift of the movable iron core. CONSTITUTION:When the solenoid 56 of a negative pressure control valve 40 conducts, a movable iron core 42 is attracted and lowered against a compression spring 58. Then the movable iron core 42 is separated from a spool valve 45, and the upper edge of an axis part passage 43a is opened, and an EGR valve 15 and an EGR pipe 21 communicate each other. The spool valve 45 is lowered by a compression spring 49, and a valve seat 47 is attached closely onto a flange part 41a, and the communication between the atmosphere and a control chamber 44 is cut off. Therefore, a negative pressure source 24 communicate to the EGR valve 15, and a negative pressure is introduced into a diaphragm chamber, and then a diaphragm is attracted, and a valve piece is separated from the valve seat, and the EGR valve 15 is opened. Therefore, the exhaust in an exhaust passage is allowed to circulate in an intake passage.

Description

Detailed Description of the Invention [Technical Field] The present invention relates to an EGR (exhaust gas recirculation) device suitable for internal combustion engines, especially diesel engines, and in particular to an EGR (exhaust gas recirculation) device that is capable of adjusting the amount of EGR (exhaust gas recirculation). Regarding a control device.

"Prior Art and its Problems" Conventionally, as a measure to reduce NOx in the exhaust gas of automobile engines, an EGR device has been put into practical use that directs a portion of the exhaust gas to the intake side. This EGR device for gasoline engines has a fixed orifice installed in the circulation passage connecting the exhaust passage and intake passage, and this fixed orifice is opened and closed by on/off control of the EGR valve.
The effect of reducing x can be obtained. However, when this fixed orifice type EGR device is used in a diesel engine, if the orifice diameter is small, no effect of NOx reduction can be expected; on the other hand, if the orifice diameter is too large,
Although NOX can be reduced, serious problems such as an increase in graphite in the exhaust gas and a decrease in output occur, as well as an increase in SOx and corrosion of the exhaust system. To solve these problems, it is necessary to precisely control the amount of EGR depending on the engine operating state, etc., and an EGR device that simply opens and closes two fixed orifices cannot meet this requirement.

Against this background, an EGR valve that changes the opening degree has already been installed in the circulation passage connecting the intake passage and the exhaust passage, and a negative pressure control valve that controls the opening degree of this EGR valve has already been installed. By controlling the EG according to the engine operating condition, etc.
An EGR control device that allows the R amount to be obtained is known.

Figure 7 is a conceptual diagram of this EGR control device, and shows the internal combustion engine
The exhaust passage 12 and intake passage 13 communicate with each other through a circulation passage 14, and an EGR valve 15 is provided in this circulation passage 14. This EGR valve 15 has a valve body 17 that is brought into contact with and separated from a valve seat 16, and the valve body 17 is connected to a diaphragm 1.
It is connected to 8. This diaphragm 18 is normally biased by a compression spring 19 in the direction of seating the valve body 17 on the valve seat 16, and when the diaphragm chamber 20 becomes negative pressure and overcomes the force of the compression spring 19, the valve body 17 The valve seat 16
Separate from. Diaphragm chamber 20 is EGR pipe 2
1. It communicates with a negative pressure source (vacuum pump) 24 via a negative pressure control valve 22 and a negative pressure pipe 23, and the negative pressure control valve 22 controls the magnitude of the negative pressure introduced into the diaphragm chamber 20. The negative pressure control valve 22 is computer-controlled according to operating conditions such as engine speed, load, and cooling water temperature.

FIG. 8 shows a conventional example of this negative pressure control valve 22. The diaphragm chamber 25 has the EGR pipe 21 on its wall.
is open, and the negative pressure pipe 23 is extended to the inside of the central portion.

The diaphragm 26 defining the diaphragm chamber 25 includes:
An opening/closing member 27 that moves up and down in the figure by a solenoid S is fixed, and within this opening/closing member 27 is the negative pressure pipe 2.
A valve body 28 for opening and closing the lower end of the valve body 3 is movably disposed. This valve body 28 is normally in close contact with the lower end of the negative pressure pipe 23 by a compression spring 29, and cuts off communication between the negative pressure pipe 23 and the EGR pipe 21. The other diaphragm chamber 25
A compression spring 30 that pushes the opening/closing member 27 downward is inserted therein, and the force of this compression spring 30 causes the opening/closing member 2 to move downward.
The flange valve portion 31 of No. 7 engages with the No. 1 valve body 28 to cut off communication between the diaphragm chamber 25 and the atmosphere.

This conventional negative pressure control valve z2 controls the amount of electricity supplied to S according to the operating state of the engine and moves the opening/closing member 27 up and down, thereby controlling the diaphragm chamber 20 of the EGR valve 15.
It is possible to control the negative pressure introduced into the That is, when the opening/closing member 27 is lowered as shown in FIG.
5 and an EGR pipe 21 to a diaphragm chamber 20 of the EGR valve 15 . In contrast, the same figure (C)
When the opening/closing member 27 is raised as shown in FIG. Atmospheric air is introduced into the diaphragm chamber 25,
This atmospheric air is also introduced into the diaphragm chamber 25 of the EGR valve 15. In the intermediate region between the two ((B) in the same figure), the diaphragm chamber 25 does not communicate with either the negative pressure source 24 or the atmosphere. Therefore, if the amount of electricity supplied to the solenoid S is controlled according to the engine operating state, In the state shown in FIG. 8(A), the negative pressure introduced into the diaphragm chamber 20 of the EGR valve 15 increases, and as a result, the amount of separation between the diaphragm 18 and the valve seat 16 increases, and the opening degree of the EGR valve 15 increases. On the contrary, in the state (B), the opening degree of the EGR valve 15 decreases, and in the state (C), the opening degree of the EGR valve 15 at that time is maintained.

However, this conventional device requires a diaphragm 26 to form the diaphragm chamber 25, and because the opening/closing member 27 is fixed to the diaphragm 26, the device configuration is unstable and susceptible to vibration. Further, the properties of the diaphragm 26 deteriorate due to long-term use, and there was a problem in durability.

``Object of the Invention'' The present invention solves the problems of the conventional EGR control device, and in particular, provides a negative pressure control valve for controlling the EGR valve that is resistant to vibration, does not use a diaphragm, and has excellent magnetic properties. The aim is to obtain a device with a simple structure.

"Summary of the Invention" The present invention controls the amount of negative pressure introduced into the EGR valve by controlling the position of a movable core that slides inside the valve body. Negative pressure pipe connected to the source, EGR pipe connected to the EGR valve,
The valve body has an open atmospheric passage, and is provided with electromagnetic moving means for moving and controlling the position of the movable iron core fitted within the valve body. Then, according to the moving position of this movable iron core, the state of communication between the EGR pipe, the vacuum pipe, and the atmospheric passage is controlled, and the amount of negative pressure introduced into the EGR valve is controlled.

"Embodiments of the Invention" The present invention will be described below with reference to illustrated embodiments. 1 to 3 show a first embodiment of the present invention. A negative pressure control valve 40 according to the present invention has a cylindrical valve body 41 having different axial positions on the circumferential surface thereof. , above EG
EGR pipe 21 connected to R valve 15 and negative pressure source 24
A negative pressure pipe 23 connected to is open. A movable iron core 42 is slidably fitted into the valve body 41, and a communication passage 43 for communicating the EGR vibe 21 and the negative pressure pipe 23 is bored in the movable iron core 42. The communication path 43 is composed of a shaft passage 43a of the movable core 42 and a radial passage 43b, and the shaft passage 43a is defined by the movable core 42 and communicates with the control chamber 44 of the EGR pipe 21. The radial passage 43b is the negative pressure pipe 2
3, each is directly connected to each other. This radial passage 4
3b and the negative pressure pipe 23 are maintained throughout the entire movement range of the movable iron core 42.

Inside the valve body 41, a spool valve 45 is provided as a passage opening/closing means for communicating the EGR pipe 21 with the negative pressure pipe 23 or the atmosphere according to the movement position of the movable iron core 42.
is slidably fitted. This spool valve 45 is
a small diameter portion 45a that passes through the shaft hole 41b of the flange portion 41a of the valve body 41 and comes into contact with the shaft portion of the movable iron core 42;
This has a large diameter part 45b located above this, and this small diameter part 4
Valve seats 46 and 47 made of elastic bodies are attached to the lower surfaces of 5a and large diameter portion 45b, respectively.

This spool valve 45 is pressed in the direction in which the valve seat 47 is brought into close contact with the flange portion 41a by a compression spring 49 inserted between the spring seat plug 48, and in the state of close contact, the control chamber 44 is connected to the atmosphere. Communication is cut off.

That is, the fitting portion between the shaft hole 41b of the valve body 41 and the small diameter portion 45a of the spool valve 45, and the valve body 4
1 and the small diameter portion 45 & are each provided with an atmospheric passage 5.
0.51 is formed, and the spring seat plug 48 has an air hole 52.
is bored, and the valve seat 47 is attached to the flange portion 41.
When away from a, the control room 44 communicates with the atmosphere. However, when the valve seat 47 comes into close contact with the flange portion 41a, this communication is cut off. 53 indicates a filter,
In addition, the valve seat 47 on the lower surface of the small diameter portion 45a is connected to the movable iron core 4.
When the upper end of the shaft passage 43a of No. 2 is closed, the EGR pipe 21
Communication between the negative pressure pipe 23 is cut off.

A solenoid case 55 is fixed to the lower part of the valve body 41. A solenoid 56 and a fixed core 57 are fixed in the solenoid case 55, and the movable core 42 is positioned on the fixed core 57 with a compression spring 58 in between. The movable iron core 42 is the solenoid 5
6, the fixed iron core 5 resists the force of the compression spring 58.
It is made of a magnetic material that is attracted to the 7 side. 59 is an air vent passage that allows the movable iron core 42 to move up and down.

The amount of current applied to the solenoid 56 depends on the engine rotation speed,
It is controlled by a control device 60 that receives input of operating data such as load and cooling water temperature.

This device having the above configuration operates as follows. First, when the solenoid 56 is not energized, the movable core 42 is at the rising end due to the force of the compression spring 58 (Fig. 2). Touch it and push it up against the force of 49. Therefore, the shaft passage 43a is closed by the valve seat 47, whereas the valve seat 47 is separated from the flange 4La, so that the air hole 52. The control chamber 44 and the diaphragm chamber 20 of the EGR valve 15 communicate with the atmosphere via the atmospheric passages 51 and 50, respectively. Therefore, the EGR valve 15 is closed and the exhaust passage 12 is closed.
The exhaust gas does not circulate to the intake passage 13 side.

On the other hand, when the solenoid 56 is energized, the compression spring 58
The movable iron core 42 is attracted and descends against the force of the third
), the movable core 42 is then separated from the spool valve 45, so the upper end of the shaft passage 43a is opened and the EGR valve 15 and EGR vibe 21 communicate with each other. Also, spool valve 4
As a result of the removal of the force that was suppressing the descent of 5, the compression spring 4
The spool valve 45 is lowered by the force of 9, and its valve seat 47 comes into close contact with the flange portion 41a, cutting off communication between the control chamber 44 and the atmosphere. Therefore, the negative pressure source 24 communicates with the EGR valve 15, and negative pressure is introduced into the diaphragm chamber 20. As a result, the diaphragm 18 is sucked and the valve body 17
is removed from the valve seat 16, and the EGR valve 15 is opened.
When the valve 15 opens, the exhaust from the exhaust passage 12 flows into the intake passage 13.
The EGR system is activated. The amount of circulation increases as the negative pressure introduced into the diaphragm chamber 20 increases.

FIG. 1 shows an intermediate case between the above two cases, in which the valve seat 47 of the spool valve 45 is in close contact with the flange portion 41a, cutting off communication between the control chamber 44 and the atmosphere, and at the same time, the valve seat 47 is also attached to the upper end of the movable iron core 42. The shaft part passage 43a is closed by closely contacting the shaft part passage 43a. In this state, neither negative pressure nor atmospheric air is introduced into the diaphragm chamber 20 of the EGR valve 15, so the EGR valve 15 maintains its current opening degree.

The control device 60 controls the amount of current supplied to the solenoid 56 of the mokugyo pressure control valve 40, which operates in this way, in accordance with the operating state of the engine and the like. Generally, when the engine speed and load are above a certain value and when they are below a certain value, the energization to the solenoid 56 is stopped (that is, the EGR valve 15 is closed), and in the intermediate range of the engine speed and load. , the solenoid 56 is energized (the EGR valve 15 opens), but as is clear from the above description, the present invention does not care about the mode of control, by precisely controlling the amount of energization to the solenoid 56, the EGR valve 15 is opened. The opening degree of the pulp 15,
In other words, the amount of EGR can be precisely controlled, reducing the amount of NOx in the exhaust gas.
can be ideally reduced.

4 to 6 show a second embodiment of the invention.

In this embodiment, only the movable iron core 42 is used as a movable member, and members functionally the same as those in the first embodiment are given the same reference numerals.

The EGR pipe 21 and the negative pressure pipe 23 are connected to the valve body 4.
A control chamber 61 above the movable iron core 42 opens into the head of the
The negative pressure pipe 23 extends to the center of the control chamber 61 .

The movable iron core 42 is movably fitted into a cylinder 62 fitted into the valve body 41, and a valve seat 63 is attached to the center of the upper end of the figure to open and close the negative pressure pipe 23 by moving into and out of contact with it. ing. Also, this movable iron core 42
The lower part of the figure is a small diameter part 42a, and this small diameter part 4
2 a extends downward through the shaft hole 64 a of the valve seat 64 and faces the fixed iron core 57 . An atmospheric passage 65 is formed between the cylinder 62 and the movable iron core 42, and an atmospheric passage 66 is similarly formed between the shaft hole 64a of the valve seat 64 and the small diameter portion 42a of the movable iron core 42. .

Further, an atmospheric passage 67 is formed in the shaft portion of the fixed core 57 to allow the movement of the movable core 42 and to guide the atmosphere into the valve body 41 . 68 is movable iron core 4
A compression spring inserted between the movable core 42 and the fixed core 57 normally separates the movable core 42 from the fixed core 57. When the movable core 42 is separated from the valve seat 64, the control chamber 61 communicates with the atmosphere via atmospheric passages 67, 66 and 65. 69 is a filter. Further, a sheet 70 is attached to the lower end of the movable core 42 in the figure, which opens and closes the atmospheric passage 67 by coming into contact with and separating from the fixed core 57.

In this embodiment, when the solenoid 56 is not energized, the movable core 42 rises due to the force of the compression spring 68, and its valve seat 61 comes into contact with the negative pressure pipe 23 to block it (FIG. 5). Communication between the control chamber 61 and the negative pressure source 24 is cut off.

On the other hand, since the movable core 42 is separated from the valve seat 64, the control room 61 is
communicates with the atmosphere, and as a result, the atmosphere is introduced into the EGR pipe 21. Therefore, the EGR valve 15 is closed, and the exhaust gas from the exhaust passage 12 does not circulate to the intake passage 13 side.

On the other hand, when the maximum current is applied to the solenoid 56 to attract the movable core 42 toward the fixed core 57, the movable core 42 is seated on the valve seat 64 as shown in FIG.
The communication between 5 and 66 is cut off, and the sea) 70 is connected to the fixed core 57.
and closes the atmospheric passage 67. On the other hand, at this time, since the valve seat 63 is away from the negative pressure pipe 23, the EGR' pipe 21 is connected to the negative pressure pipe 23.
The negative pressure of a negative pressure source 24 is introduced via E
The GR valve 15 opens, and the exhaust gas from the exhaust passage 12 is circulated to the intake passage 13 side.

FIG. 4 shows an intermediate case between the above two states. In this state, the amount of air sucked in by the negative pressure pipe 23 and the amount of air supplied to the control chamber 61 via the atmospheric passages 67, 66 and 65 are balanced.

Therefore, the opening degree of the EGR valve 15 at this time is maintained.

As described above, according to this embodiment, the same function as the first embodiment can be obtained with only a single moving member, the movable iron core 42, and the structure is simpler, the cost is lower, and there are fewer failures. An EGR control device can be obtained.

As is clear from the above description, the present invention is particularly suitable as an EGR device for diesel engines, but it may also be used for gasoline engines as a more ideal EGR device.

"Effects of the Invention" As described above, in the EGR control device of the present invention, the negative pressure control valve that controls the EGR valve has a movable iron core that is slidably fitted into a cylindrical valve body, and a movement of the movable iron core. It is composed of an EGR pipe, a passage opening/closing means that controls the state of communication with the vacuum pipe and the atmospheric passage according to the position, and the movement of this movable iron core is controlled by an electromagnetic control means.

The amount of negative pressure introduced into the EGR pipe is controlled, ensuring reliable operation and high reliability against vibration.
That is, unlike conventional devices, a diaphragm is not used, so that performance does not deteriorate even after long-term use, and an EGR control device with high durability and reliability can be obtained.

[Brief explanation of the drawing]

1 to 3 show a first embodiment of the present invention, in which FIG. 1 is a vertical sectional view of a negative pressure control valve used in an EGR control device according to the present invention, and FIGS. 2 and 3 are each first
FIG. 4 is a cross-sectional view of a main part of the negative pressure control valve shown in the figure showing different operating states. 4 to 6 show a second embodiment of the present invention, in which FIG. 4 is a vertical cross-sectional view of a negative pressure control valve, and FIGS. 5 and 6 are negative pressure control valves shown in FIG. 4. FIG. 3 is a cross-sectional view of a main part showing different operating states of the valve. Figure 7 shows EGR
System connection diagram showing an example of the configuration of the entire device, Fig. 8 (A), (
B) and (C) are sectional views showing examples of conventional negative pressure control valves in different operating states. 11... Internal combustion engine, 12... Exhaust passage, 13...
Intake passage, 14... Circulation passage, 15... EGR valve, 16... Valve seat, 17... Valve body, I8... Diaphragm, 19... Compression spring, 20... Diaphragm chamber , 21... EGR pipe, 23... Negative pressure pipe, 24... Negative pressure source, 40... Vacuum control valve, 41
...Valve body, 41a...Flange part, 41b
...Shaft hole, 42...Movable iron core, 43...Communication path,
44... Control room, 45... Spool valve, 45a...
・Small diameter part, 45b... Large diameter part, 46° 47... Valve seat, 50.51... Atmospheric passage, 52... Atmospheric hole, 55... Solenoid case, 56... Solenoid, 56... Fixed iron core, 58... Compression spring, 59...
...Air vent passage, 60...Control device, 61...Control room, 63.64...Valve seat, 65.66.6
7... Atmospheric passage, 68... Compression spring.

Claims (1)

[Claims] (1) An EGR valve that changes its opening depending on the magnitude of introduced negative pressure is installed in the circulation passage connecting the exhaust passage and intake passage of the internal combustion engine, and an EGR valve is installed between the EGR valve and the negative pressure source.
In an EGR control device for an internal combustion engine that is equipped with a negative pressure control valve that adjusts the amount of negative pressure introduced into the R valve, the negative pressure control valve is connected to a vacuum pipe connected to a negative pressure source, an EGR pipe connected to the EGR valve, and the atmosphere. a cylindrical valve body with a passage opened; a movable core slidably fitted into the valve body; an electromagnetic moving means for moving the movable core within the valve body; a moving position of the movable core; Accordingly, an EGR control device for an internal combustion engine, comprising the EGR pipe and passage opening/closing means for controlling the communication state between the vacuum pipe and the atmosphere passage.