JPH06323202A - Recirculated gas amount controller for egr device - Google Patents

Abstract

PURPOSE:To improve detection accuracy by improving detection sensitivity in a low velocity region, and to provide a recirculated gas amount controller for an EGR device for which a magnetic stroke detection sensor having excellent heat resistance and heat resistant cycle properties is used. CONSTITUTION:An EGR valve 1 is provided on EGR routes 7, 10 communicating between the exhaust route 8 and an intake route 11 of an engine, and the flow of exhaust gas recirculated in the engine is adjusted by controlling the opening of the EGR valve 1. A valve shaft 5 for supporting the valve element 4a of the EGR valve 1 is made of non-magnetic substance, and magnetic parts are formed on the valve shaft 5 at a specific interval. A magnetic stroke detection sensor 15 for detecting the amount of movement of the valve shaft 5 is also provided. The stroke detection sensor 15 comprises first and second detection side coils 17, 18 and a common exciting side coil 16 for applying a.c. bias magnetic field to the detection side coils 17, 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recirculation gas amount control device for an EGR device that recirculates exhaust gas to an automobile engine, and more particularly to improvement of the structure of a stroke sensor for detecting the opening of an EGR valve.

[0002]

BACKGROUND ART Automotive EGR device is a device part is recycled to the intake system of the engine to reduce the NO _X in the exhaust gas. In this EGR device, the recirculation exhaust gas amount is controlled by controlling the opening degree of the EGR valve. In this case, it is general that the axial movement amount of the valve shaft of the EGR valve is detected by the detection sensor and feedback control is performed by this. As a sensor for detecting the amount of movement of such a valve shaft, a magnetic sensor has been mainly used from the viewpoint of stability and reliability in a bad environment.

Of the above-mentioned magnetic sensors, for example, a commonly used MR element and Hall element have a narrow usable temperature range of about -10 to 80 ° C., so that a large heat such as an engine room or an exhaust system is generated. It cannot be used where a cycle occurs. In the case of the MR element or Hall element, the magnetic scale to be detected must be a magnetized magnetic body such as a magnet, but it is not possible for the detection target to maintain a stable magnetic force at high temperatures (for example, 150 ° C or higher). This is difficult, and the operating temperature environment is limited also from this point.

On the other hand, the stroke detection sensor of the magnetic coil type, which detects the amount of movement by the change in the inductance value of the coil, applies a bias current to the coil to magnetize the core, and thus detects even a non-magnetized magnetic material. be able to. For this reason, the magnetic scale can be used even at high temperatures, and therefore can be used in places such as the engine room and the exhaust system where thermal cycles occur. As such a magnetic coil type stroke detection sensor for EGR, conventionally, a magnetic portion is formed on the outer surface of a valve shaft made of a non-magnetic material at a predetermined interval in the axial direction. There has been proposed a device in which the passage of a part is detected by a detection coil (see, for example, Japanese Patent Laid-Open Publication No.
61-281902, Japanese Examined Patent Publication 1-34328).

The detection coil described in the above publication has a structure in which a coil is wound around the outer circumference of a coil bobbin in which a core is inserted and is housed in a magnetic shield case. Further, as the core of the above-mentioned detection coil, conventionally, for example, one obtained by cutting an oxide type soft ferrite or the like into a predetermined shape and size is adopted.

[0006]

However, in the above-mentioned conventional magnetic stroke detection sensor, since each detection sensor has its own excitation coil, a phase difference occurs in the magnetic flux from each excitation coil. Or, because they interfere with each other, the detection sensitivity is low, which is a bottleneck in improving the detection accuracy. Further, each detection sensor has a problem that the structure is complicated and the size is increased due to the presence of the exciting coil and the detecting coil. Further, since the conventional DC bias type sensor is a differential type of the moving speed, it is difficult to obtain a sufficient output in the low speed range.

Further, in the above-mentioned conventional magnetic stroke detection sensor, the soft ferrite or amorphous alloy used as the core material of the detection coil has a remarkable decrease in magnetic permeability at 150 ° C. or higher. However, the reliability of heat resistance at the place where it is used or heat cycle occurs is low, and improvement in this respect is required.

The present invention has been made in view of the above-mentioned conventional circumstances, and the magnetic type stroke detection which is excellent in heat resistance and heat cycle resistance as well as can improve detection accuracy by improving detection sensitivity in a low speed range. An object of the present invention is to provide a recirculation gas amount control device for an EGR device using a sensor.

[0009]

According to a first aspect of the present invention, an EGR passage is connected to an EGR passage that connects an exhaust passage and an intake passage of an engine.
In a recirculation gas amount control device for an EGR device, in which a GR valve is provided and an opening of the EGR valve is controlled to adjust a flow rate of exhaust gas recirculating to an engine, a valve body of the EGR valve is supported. A magnetic scale is provided by making the valve shaft made of a non-magnetic material and forming magnetic portions on the valve shaft at predetermined intervals, or by making the valve shaft made of a magnetic material and forming a plurality of concave grooves. A magnetic stroke detection sensor for detecting the amount of movement of the valve shaft from the magnetic scale, the stroke detection sensor includes two detection side coils, and a common excitation side coil for applying an AC bias magnetic field to the detection side coils. It is characterized by being composed of and.

The invention according to claim 2 is characterized in that two sets of stroke detection sensors each including the two detection side coils and one excitation side coil are provided in the stroke direction of the valve shaft.

[0011]

According to the recirculation gas amount control device of the EGR device according to the present invention, the magnetic stroke detection sensor is composed of the detection side coil and the common excitation side coil. The same applies to the coils, so that there is no phase difference or mutual interference, and the detection sensitivity can be improved from this point. In this case, by applying an AC bias current, an output corresponding to the bias frequency is always obtained in the detection side coil, and it is detected that the amplitude changes between the magnetic part and the non-magnetic part. There is no reduction in sensitivity even in the low speed range. Further, the structure is simplified by sharing one exciting side coil for the two detecting side coils, and the overall size can be reduced.

Further, according to the second aspect of the invention, since two sets of stroke detection sensors each including two detection side coils and one excitation side coil are provided in the stroke direction of the valve shaft, the valve can be accurately operated over a wide temperature range. The moving direction of the shaft can be detected.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 11 are views for explaining a recirculation gas amount control device for an EGR device according to a first embodiment of the present invention. In the figure, reference numeral 1 denotes an EGR valve of an EGR device, which has a structure in which a bowl-shaped negative pressure housing 3 is covered on an upper surface of a housing body 2. A partition wall 2c that divides the main body 2 into a lower portion 2a and an upper portion 2b is integrally formed in the housing main body 2, whereby an EGR communication chamber A and a detection chamber B are formed in the housing main body 2. .

An exhaust gas introduction port 6 is opened in the EGR communication chamber A of the lower portion 2a, and the exhaust gas introduction port 6 is connected to an exhaust manifold (exhaust passage) 8 via an exhaust gas introduction pipe (EGR passage) 7. ing. Further, an exhaust gas supply port 9 is opened in the communication chamber A of the lower portion 2a, and this supply port 9 is downstream of a throttle valve 23 of an intake pipe (intake passage) 11 via an exhaust supply pipe (EGR passage) 10. Connected to the side. The downstream end of the intake pipe 11 is connected to an intake port of an engine (not shown), and the upstream end of the exhaust manifold 8 is connected to an exhaust port.

A diaphragm type movable plate 24 is provided between the upper portion 2b of the housing body 2 and the negative pressure housing 3.
The movable plate 24 divides the upper part 2b and the negative pressure housing 3 into a detection chamber B and a negative pressure chamber C. A negative pressure passage 3a is opened in the negative pressure chamber C, and the passage 3a is connected to the vicinity of the throttle valve 23 of the intake pipe 11 via a negative pressure introducing pipe 25. A negative pressure actuator 26 is provided in the middle of the negative pressure introducing pipe 25.
6 is configured to open and close the negative pressure introducing pipe 25.

A valve body 4 is provided in the housing body 2.
Is arranged so as to be movable back and forth in the axial direction, and the opening / closing valve 4a of the valve body 4 is configured to open / close the exhaust gas introduction port 6 of the EGR communication chamber A. The lower end 5a of the valve shaft 5 is connected to the on-off valve 4a, and the upper end 5b of the valve shaft 5 penetrates the partition wall 2c and is connected to the movable plate 24. The valve shaft 5 has the same diameter over its entire axial length, and its surface is finished to be smooth. As a result, the outer peripheral surface of the valve shaft 5 and the inner peripheral surface of the through hole of the partition wall 2c are in airtight sliding contact. Further, the valve body 4 is urged in a direction to close the exhaust gas introduction port 6 by a coil spring 27 arranged between the movable plate 24 in the negative pressure chamber C and the upper surface of the negative pressure housing 3. .

The valve shaft 5 is made of SU containing Mn.
The valve shaft 5 is made of a high-manganese non-magnetic steel material such as S304. On the outer peripheral surface of the valve shaft 5, magnetic portions 12 are formed in stripes at a predetermined pitch (for example, 0.4 mm) in the axial direction thereof. The magnetic portion 12 is provided on the valve shaft 5 with a pitch of 0.4 mm in the axial direction, a width of 0.2 mm and a depth.
A ring groove 13 of 0.4 mm is formed, and Fe is filled in the groove 13 by electroplating. The magnetic portion 12 and the valve shaft 5 are formed so as to be flush with each other, and a hard chrome plated film 14 having a thickness of 10 to 30 μm is formed on the outer peripheral surface thereof. The portion between the magnetic portions 12 of the valve shaft 5 is a non-magnetic portion 5c.

Further, the magnetic stroke detection sensor 15 of this embodiment is arranged in a portion of the housing body 2 which faces the upper portion of the valve shaft 5. This detection sensor 15
The CPU 20 is connected to the CPU via a signal processing circuit 23. The CPU 20 calculates the moving distance of the valve shaft 5 by counting the pulse signals from the signal processing circuit 23, compares the calculated moving distance with the target EGR gas amount, and then calculates the target gas amount. The valve body 4 is driven via the actuator 26 to set the opening degree so that the EGR gas amount is controlled in this way.

The detection sensor 15 is, as shown in FIG.
First and second detection side coils 17 and 18 are arranged on both sides of the excitation side coil 16, respectively, and are housed in a magnetic shield case (not shown). Each coil 1
6 to 18 are, for example, a copper wire (coil winding) 20 formed by coating a polyimide amide resin on the outer circumference of a bobbin 19 made of a polyimide amide resin, and each bobbin 19 has a substantially T-shape on its axis. Shaped center core 21, approximately L
The character-shaped first and second detection cores 22a and 22b are inserted and buried, and the upper portions of the respective cores 21, 22a and 22b are attached to the bobbin 1.
It is configured to project from the outside to the outside. Terminals 16a, 17a, 18a are connected to both ends of each copper wire 20.

On both side surfaces of the center core 21 of the excitation side coil 16, the first and second detection side coils 17,
The first and second detection cores 22 a and 22 b of 18 are non-magnetic materials 2
6 are opposed to each other, and a gap is provided between the center core 21 and each of the detection cores 22a and 22b due to the presence of the non-magnetic body 26. Here, the first,
The second detection cores 22a and 22b are arranged so as to correspond to the magnetic portion 12 and the non-magnetic portion 5c, respectively. For example, the formation pitch of the magnetic portions 12 is 360 degrees, and the first and second detection cores 22a and 22b are arranged so as to be separated from each other by 270 degrees or 90 degrees.

As shown in FIG. 5, the center core 21 is composed of a sendust alloy thin plate 21a having a thickness of 0.06 mm.
The detection cores 22a and 22b are also composed of a stack of Sendust alloy thin plates. The sendust alloy thin plate 21a
Is composed of Si 8.8 wt%, Al 5.5 wt%, and the balance Fe, and is manufactured by the twin roll quenching method. This twin roll quenching method is a method in which a pair of rolls are rotated in opposite directions while being pressed against each other, a melt of Sendust-based alloy is supplied between the rolls, and the melt of alloy is rapidly solidified and rolled at a contact portion of the rolls. It is a method of producing a continuous quenched thin plate by carrying out. The center core 21 is formed by adhering a quenched thin plate obtained by the twin roll rapid cooling method with an epoxy resin interposed, and cutting this by machining.

The input terminal 16 of the exciting coil 16 is also provided.
An oscillator 28 for applying an AC bias current of a predetermined frequency is connected between a and 16a. The signal processing circuit 23 is connected between the output terminals 17a and 18a of the first and second detection coils 17 and 18, respectively. The signal processing circuit 23 mainly includes the first and second detection coils 17,
It is composed of a comparator 23a which outputs a comparison signal of 18 outputs and a detector 23b which detects the comparison signal.

Next, the operation of the apparatus of this embodiment will be described. As shown in FIGS. 6 and 7, an oscillator 28 applies an AC bias current of, for example, 6 kHz to the excitation-side coil 16. When the valve shaft 5 moves back and forth in the axial direction in this state, each time the magnetic portion 12 of the shaft 5 passes immediately before the first detection coil 17 and the second detection coil 18,
The impedance of each coil 17, 18 changes (see FIG.
(1) and (2)), this output signal is the signal processing circuit 2
3 is input to the comparator 23a. The detector 23b detects the unnecessary portion of the comparison signal from the comparator 23a (see FIG. 7 (3)) to form a pulse signal (see FIG. 7 (4)), and the pulse signal is input to the CPU 20. And CPU
20 calculates the moving distance of the valve shaft 5 by counting the pulse signals, calculates the opening of the EGR valve 1 based on the calculated moving distance, and this opening corresponds to the target EGR gas amount. The actuator 26 is driven to adjust the EGR gas amount so as to obtain the opening. As a result, the engine output is reduced and unstable combustion is avoided while reducing NOx. Further, the moving direction of the valve shaft 5 is determined by the leading edge and the trailing edge of the pulse signal obtained from both detection coils 15. In order to make this determination accurately, the reference value for binarization is 9 in this embodiment.
It is necessary to set within an allowable range of 4 to 107 mH. In addition,
The neutral position of the valve shaft 5 is set to the most frequent value by learning control.

As described above, according to this embodiment, since the sendust-based alloy thin plates 21a are used for the cores 21, 22a and 22b of the detection sensor 15, it is possible to use them in the range of -40 to 250 ° C. In addition, heat resistance and heat cycle resistance can be improved, and when used in an engine room or exhaust system where a large heat cycle occurs, reliability of heat resistance can be improved and life can be extended.

Further, in this embodiment, since the laminated body formed by laminating the sendust-based alloy thin plates 21a is adopted, a conventional single unlaminated alloy plate (hereinafter, a single alloy plate without laminating alloy plates is used). The detection sensitivity can be improved, and the detection accuracy can be improved accordingly. By the way,
The detection accuracy of the detection sensor 15 of this embodiment is −30 to 150 ° C.
When used in the temperature range of, it was ± 0.2 mm. Moreover, the sensitivity was greatly improved compared to the conventional non-laminated material.

Since the detection sensor 15 is composed of the excitation side coil 16 and the first and second detection side coils 17 and 18,
The detection sensitivity can be improved as compared with the conventional structure in which the exciting coil and the detecting coil are wound around one detecting core. That is, in the conventional structure, since the exciting coil is dedicated, a phase difference occurs in the bias magnetic flux and mutual interference occurs, but these problems are avoided because the exciting side coil is shared in this embodiment. It is possible to improve the detection accuracy. Further, the structure is simple and the size can be reduced because the excitation side coil is shared. Further, since the AC bias current is applied, good sensitivity and accuracy can be obtained even when the valve shaft 5 stands still or moves at a very low speed.

8 to 11 are diagrams for explaining the results of the test conducted to confirm the effect of the detection coil 15 of this embodiment. FIG. 8 shows the test results of measuring the temperature dependence of the detection sensor 15 of this embodiment. As is clear from the figure, by adopting a core made by laminating Sendust alloy thin plates, the magnetic permeability can be maintained at room temperature (20
It shows a value equal to or higher than (° C) and that the temperature characteristics are greatly improved.

FIGS. 9 and 10 show a laminated body of sendust alloy thin plates of this embodiment (shown by a solid line) and a non-laminated core material formed by cutting a sendust ingot of the same component (shown by a broken line). ) And the change in magnetic permeability depending on the plate thickness and the change in magnetic flux density depending on frequency are shown. As is clear from FIG. 9, the laminated core of the present embodiment has a smaller decrease in magnetic permeability due to the thickness as compared with the non-laminated core, and the core thickness before the lamination (0.06
(mm) and the magnetic permeability is almost the same. Further, as is clear from FIG. 10, the laminated core of the present embodiment has less decrease in the saturation magnetic flux density in the high frequency region of 1 kHz or more as compared with the non-laminated core material, and excellent characteristics are obtained also in the high frequency region. You can see that

[0029]

[Table 1]

FIG. 11 shows the test results of measuring the output waveform at room temperature (20 ° C.) and the output voltage value due to temperature change. In this test, the bobbin 19 has a diameter of 0.1 mm
The secondary winding is wound 600 turns and 0.02 mmφ 2
The detection sensor 1 of the present embodiment is obtained by winding the secondary winding 600 turns.
Configured 5. A bias current of 100 mA DC was applied to the primary winding, and a detection terminal was connected to the secondary winding.
Then, a block formed by alternately laminating a PC permalloy plate (thickness 0.1 mm) and a phosphor bronze plate (thickness 0.1 mm) is passed through the detection sensor 15 at a constant speed of 45 mm / sec. The output waveform was observed with a storage scope. Also,
Table 1 shows the results of measuring the output voltage (V _PP ) due to the temperature change of −40 ° C. to 260 ° C.

As is apparent from Table 1, -40 ° C to 260 ° C
It can be seen that the output sufficient for detecting the period of the signal is obtained in the temperature range of, and the amount of displacement in the high temperature atmosphere can be accurately detected.

In the above embodiment, the detection side coil 1
Although it is configured that the moving direction of the valve shaft 5 is determined by using two of 7 and 18, only one detection side coil may be used when it is not necessary to determine the moving direction. Further, in the above embodiment, the Fe-Si-Al-based sendust alloy was adopted as the sendust-based alloy, but a sendust-based alloy in which elements such as Cr and Ti are added to these three elements to improve various characteristics is adopted. May be. Further, in the above embodiment, the case where the Sendust alloy thin plate is adopted has been described as an example, but the present invention is not limited to this. For example, a soft magnetic alloy plate such as Permalloy or Finemet (registered trademark) is used. The detection sensitivity can be improved also in this case.

Further, when a non-laminated core made of the same Sendust alloy is used, a sensor having less temperature dependency in temperature characteristics can be obtained although it is inferior in sensitivity to the laminated core, and can be effectively used depending on the application.

In the above embodiment, the case where the magnetic portions 12 are formed on the outer peripheral surface of the non-magnetic valve shaft 5 at a predetermined pitch has been described. However, the weak magnetic portions are formed on the outer peripheral surface of the magnetic body at a predetermined interval. The groove may be formed to increase or decrease the magnetism at predetermined pitches. In this case, the cost can be reduced as compared with the case where the magnetic substance and the non-magnetic substance are alternately arranged.

In the first embodiment, since the moving direction of the valve shaft 5 is determined by the leading edge and the trailing edge of the pulse signal obtained from both detection coils 15, the reference value for binarization is set. There is a need. However, with this method, there is a concern that it becomes difficult to set the threshold value when the output signal fluctuates due to changes in the temperature of the shaft and the air gap. In order to solve this problem, it is possible to detect the moving direction without setting a threshold value.

12 to 20 are views for explaining the second embodiment according to the inventions of claims 1 and 2, and in order to avoid the above-mentioned concern, in this embodiment, the stroke in the first embodiment is used. A detection sensor A having the same structure as the detection sensor 15,
Two sets of B are arranged in the stroke direction of the shaft with a distance of 1.75 times the formation pitch of the magnetic portions 12. Then, the output signals of the stroke detection sensors A and B are obtained by using the difference between the first and second detection side coils 17 and 18, and the moving direction of the valve shaft 5 is determined by detecting the signs of both output signals. ing.

Next, a method of detecting the moving direction of the valve shaft 5 in this embodiment will be described with reference to FIGS. FIG. 13 shows the magnetic portion 1 of the valve shaft 5.
2, non-magnetic portion 5c and first and second detection side coils 17, 18
14 to 18 are schematic diagrams showing the positional relationship between the stroke detection sensors A and B of the present embodiment, and FIG. 19 is a movement direction of the valve shaft and stroke detection sensors A and B. 20 shows the relationship with the output of FIG.
FIG. 4 is an output waveform diagram of the stroke detection sensors A and B.

In this embodiment, each stroke detection sensor A,
Alternatively, as the output of B, the difference obtained by subtracting the output of the second detection side coil 18 from the output of the first detection side coil 17 is used. Therefore, in FIG. 13, when the valve shaft 5 and the stroke detection sensor A or B are in the relative position shown in (a), the difference (output of the stroke detection sensor) shows + as a result of subtracting 0 from +. ,
When it is in the relative position of (b), it is the first in both cases of (i) and (ii).
Since the outputs of the detection coil 17 and the second detection coil 18 are equal to each other, the difference between them is 0, and when the relative position is (c), the difference is-.

When the valve shaft 5 and the stroke detection sensors A and B are in the relative positions shown in FIGS. 14 to 18, the outputs of the sensors A and B are shown in FIGS. 14 to 18 and 19, respectively. . That is, the sensors A and B in the case of FIG.
The output of (-, as shown in (a) of FIG. 14 and FIG.
0), and the shaft moves 0.25 to the right from this state.
When moved by the pitch, the output becomes (0, +) as shown in FIGS. 15 and 19B, and further 0.25
When moved by the pitch, it becomes (+, 0) as shown in FIGS. 16 and 19C. On the other hand, when moving from the state of FIG. 14 to the left by 0.5 pitch, the output goes through (0, −) of (d) of FIG. 17 and FIG. 19 and (+, of (e) of FIG. 18 and FIG. 0) is shown. This output change becomes a sine wave as shown in FIG. Therefore, the moving direction of the valve shaft 5 can be detected only by detecting the change in the sign of these outputs.

As described above, in this embodiment, two stroke detection sensors A and B are provided, and the output difference between the first and second detection side coils 17 and 18 is used as the output of each stroke detection sensor A and B. Since the moving direction of the valve shaft 5 is detected, the shaft 5
Even if the output signal fluctuates due to changes in the temperature and the air gap, it is not difficult to set the threshold value. Therefore, it is possible to stably detect the moving direction.

Also in the present embodiment, similarly to the first embodiment, the detection sensitivity can be improved as compared with the conventional structure, and the problems that a phase difference occurs in the bias magnetic flux and mutual interference occurs, In addition, the size can be reduced. Further, good sensitivity and accuracy can be obtained even when the valve shaft 5 is stationary or moves at an extremely low speed.

[0042]

As described above, the EG according to the invention of claim 1
According to the reflux gas amount control device of the R device, the stroke detection sensor is configured by the detection side coil and the common excitation side coil, so that the phase difference of the bias magnetic flux and mutual interference are avoided, and the detection accuracy is improved. There is an effect that can be improved.

Further, according to the second aspect of the present invention, since two sets of the stroke detection sensors are provided in the stroke direction, there is an effect that the movement direction of the stroke can be detected stably even at a low stroke speed.

[Brief description of drawings]

FIG. 1 is an EGR according to a first embodiment of the present invention.
It is a schematic block diagram for demonstrating the circulating gas amount control apparatus of an apparatus.

FIG. 2 is a schematic diagram showing a positional relationship between the valve shaft and the magnetic stroke detection sensor of the first embodiment.

FIG. 3 is a perspective view showing a detection sensor of the first embodiment.

FIG. 4 is a perspective view showing an excitation side coil of the first embodiment.

FIG. 5 is a perspective view of the center core of the first embodiment.

FIG. 6 is a circuit diagram of the detection sensor of the first embodiment.

FIG. 7 is an output waveform diagram of the detection sensor of the first embodiment.

FIG. 8 is a characteristic diagram showing a result of a test performed to confirm the effect of the first embodiment.

FIG. 9 is a characteristic diagram showing the results of tests conducted to confirm the effects of the first embodiment.

FIG. 10 is a characteristic diagram showing a result of a test conducted to confirm the effect of the first embodiment.

FIG. 11 is a characteristic diagram showing a result of a test performed to confirm the effect of the first embodiment.

FIG. 12 is a schematic diagram showing a positional relationship between a valve shaft and a detection sensor in a second embodiment according to the first and second aspects of the invention.

FIG. 13 is a schematic diagram showing the relationship between the relative position of the valve shaft and the detection sensor and the output in the second embodiment.

FIG. 14 is a diagram showing a positional relationship between a valve shaft and each detection sensor of the second embodiment and outputs thereof.

FIG. 15 is a diagram showing the positional relationship between the valve shaft and each detection sensor and the output in the second embodiment.

FIG. 16 is a diagram showing an arrangement relationship between a valve shaft and each detection sensor of the second embodiment and an output.

FIG. 17 is a diagram showing an arrangement relationship between a valve shaft and each detection sensor and an output in the second embodiment.

FIG. 18 is a diagram showing an arrangement relationship between a valve shaft and each detection sensor of the second embodiment and an output.

FIG. 19 is a diagram showing the relationship between the moving direction of the valve shaft and the outputs of the detection sensors A and B of the second embodiment.

FIG. 20 is an output waveform diagram of the detection sensors A and B of the second embodiment.

[Explanation of symbols]

 1 EGR valve 4a Valve body 5 Valve shaft 7 and 10 Exhaust introduction and supply pipe (EGR passage) 8 Exhaust manifold (exhaust passage) 11 Intake pipe (intake passage) 12 Magnetic part 15, A, B Magnetic stroke detection sensor 16 Excitation Side coil 17,18 First and second detection side coils 21,22a, 22b Core material

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinichi Murakami 2-2-5 Minamimachi Shinada, Nada-ku, Kobe (72) Inventor Kazuo Inoue 12-23 Umegayacho, Himeji-shi (72) Inventor Tatsuhiro Tani, Yodogawa, Osaka-shi 1-9-11 Miyahara-ku (72) Inventor Mio Uda 684 Shimobu, Kagami-cho, Kami-gun, Kochi Prefecture Minerva Kochi Factory (72) Inventor Mitsuru Ono 1-3-18 Wakihama-cho, Chuo-ku, Kobe -Technology Co., Ltd. (72) Inventor, Yukihisa Takeuchi, 1-1, Showa-cho, Kariya city, Aichi prefecture, Nihondenso Co., Ltd.

Claims (2)

[Claims] 1. An EGR valve is provided in an EGR passage that connects an exhaust passage and an intake passage of an engine, and an opening of the EGR valve is controlled to adjust a flow rate of exhaust gas recirculated to the engine. In the recirculation gas amount control device for the EGR device described above, the valve shaft supporting the valve body of the EGR valve is made of a non-magnetic material, and magnetic portions are formed at predetermined intervals on the valve shaft, or the valve shaft is A magnetic scale is provided by forming a plurality of concave grooves made of a magnetic material, and a magnetic stroke detection sensor for detecting the movement amount of the valve shaft from the magnetic scale is provided. The stroke detection sensor has two detection sides. An EGR device comprising a coil and a common excitation side coil for applying an AC bias magnetic field to the detection side coil. Gas flow rate control device. 2. The recirculation gas amount of an EGR device according to claim 1, wherein two sets of stroke detection sensors each including the two detection side coils and one excitation side coil are provided in a stroke direction of a valve shaft. Control device.