JPS60123761A - Apparatus for detecting particulate substance in exhaust gas - Google Patents

Abstract

PURPOSE:To make it possible to accurately detect the particulate substance in exhaust gas, by intermittently supplying a current to an electrode and generating heat from the electrode to burn off the particulate substance adhered to said electrode. CONSTITUTION:The responding time of each relay 11 is set by a timer 9 and all of relays are simultaneously closed at black dot contact sides during an ion current detecting period but said black dot contact sides are opened all at once at every definite time while other white dot contact sides are closed. In this case, simultaneously with the closing at white dot contact sides, all of the earth electrodes 41a, 41b and the high voltage electrode 42 in a discharge electrode side and the earth electrodes 51a, 51b and the low voltage electrode 52 in a detection electrode side are connected in series and voltage necessary for heating each electrode to 500 deg.C or more is applied from a heating power source 8. The particulate substance having being adhered to each electrode during an ion current detecting period is burnt off and removed during this time. As a result, because a large amount of the particulate substance is not adhered to each electrode and a discharge condition or a detection condition can be kept almost constant, the particulate substance in exhaust gas can be accurately detected.

Description

【発明の詳細な説明】 本発明は自動車の排ガス中において長時間連続的且つ正
確に機能する粒子状物質検出装置に関するものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a particulate matter detection device that functions continuously and accurately for a long time in automobile exhaust gas.

従来排ガス中の粒子状物質を長時間連続的に検出する装
置として、コロナ放電による粒子状物質の静電帯電を利
用し後方に静電界基を設置して、ここでイオン化された
粒子を偏向させ、それを電流変化として粒子状物質の測
定をする装置（特開昭５０−４８９９０号）が知られて
いる。上記従来装置はコロナ放電により粒子状物質を帯
電させる電極とイオン化された粒子状物質を静電界基に
おいて偏向させ、これに伴う電流変化を検出する電極と
を備えたものである処、各電極に付着した粒子状物質を
除去する手段は備えられていなかった。従ってこのよう
に電極に付着した粒子状物質が電極間隔を狭めて放電条
件や検出条件を変化させ、検出精度を劣化させてしまう
ことがあった。Conventionally, as a device that continuously detects particulate matter in exhaust gas over a long period of time, an electrostatic field group is installed at the rear using electrostatic charging of particulate matter caused by corona discharge, and the ionized particles are deflected here. There is a known device (Japanese Patent Application Laid-open No. 48990/1983) that measures particulate matter by using it as a change in current. The above-mentioned conventional device is equipped with an electrode that charges particulate matter by corona discharge, and an electrode that deflects the ionized particulate matter in an electrostatic field group and detects the resulting current change. No means were provided to remove attached particulate matter. Therefore, the particulate matter adhering to the electrodes may narrow the electrode spacing and change the discharge conditions and detection conditions, thereby deteriorating the detection accuracy.

本発明は上記の劣化をなくするためになされたもので、
その要旨は特許請求の範囲に記載の通りである。The present invention was made to eliminate the above-mentioned deterioration.
The gist is as described in the claims.

以下添付図面により説明する。This will be explained below with reference to the attached drawings.

第１図は本発明検出装置の排ガス接触部分の一実施例を
示す斜視図である。この装置は図中矢印の方向に排ガス
が流れるようεこ排気管に取り付けられて使用される。FIG. 1 is a perspective view showing an embodiment of the exhaust gas contact portion of the detection device of the present invention. This device is used by being attached to an exhaust pipe so that the exhaust gas flows in the direction of the arrow in the figure.

放電電極用碍子１ａ、ｌｂ及び検出電極用碍子２ａ、２
ｂを排ガス流路の上流側に前者が、下流側に後者が位置
するようにそれぞれフランジ３に固定されている。碍子
１ａ＋１ｂは接地極４１ａ、４１ｂと（−）高圧電極４
２とからなる放電電極を支持している。Insulators 1a, lb for discharge electrodes and insulators 2a, 2 for detection electrodes
b are respectively fixed to the flange 3 such that the former is located on the upstream side of the exhaust gas flow path, and the latter is located on the downstream side. Insulators 1a+1b are ground electrodes 41a, 41b and (-) high voltage electrode 4
It supports a discharge electrode consisting of 2.

（−）高圧電極４２には通常（−）の直流電圧数ＫＶが
印加されており、接地極４１ａ、４１ｂとの間でコロナ
放電を起こすようになしている。排ガス中の粒子状物質
はここで（−）に帯電される。A normal (-) DC voltage of several KV is applied to the (-) high-voltage electrode 42 to cause corona discharge between it and the ground electrodes 41a, 41b. Particulate matter in the exhaust gas is charged (-) here.

一方検出電極用碍子’ｌａ、”ｌｂは、接地極５１ａ。On the other hand, the detection electrode insulator 'la,'lb is the ground electrode 51a.

５１ｂとく＋）低圧電極５２とからなる検出電極を支持
している。（＋）低圧電極５２には（＋）の直流電圧（
＋）１０数Ｖが印加され、接地極５１ａ、５１ｂとの間
で静電界基を形成している。51b supports a detection electrode consisting of a low voltage electrode 52. The (+) low voltage electrode 52 has a (+) DC voltage (
+) 10-odd V is applied to form an electrostatic field group between the ground electrodes 51a and 51b.

上記　（−）に帯電された粒子状物質はこの静電界基に
流入すると電位の高い（＋）低圧電極５２側へ偏向する
ために、これと逆向きにイオン電流が流れ、粒子状物質
の個数に比例した電流の変化を検出することができる。When the (-) charged particulate matter flows into this electrostatic field group, it is deflected toward the high potential (+) low-voltage electrode 52, so an ionic current flows in the opposite direction, and the number of particulate matter increases. Changes in current proportional to can be detected.

この電流は接地極５１ａ５１ｂより取り出され図示しな
い項中型電流計で常時個数及び粒子の大きさに応じた大
きさを指示し、同時に図示しない演算回路を経て記録さ
れる。This current is taken out from the ground electrode 51a51b, and is constantly indicated by a medium-sized ammeter (not shown) in accordance with the number and size of the particles, and is simultaneously recorded via an arithmetic circuit (not shown).

偏向した粒子状物質はその後出口に排出される。The deflected particulate matter is then discharged to the outlet.

ところで排ガス中の粒子状物質は必ずしもそのすべてが
上述の経路を通るとは限らず、所望でない経路を通って
電極に付着するものが少なくない。By the way, not all of the particulate matter in the exhaust gas necessarily passes through the above-mentioned route, and many of them adhere to the electrodes through undesired routes.

付着した粒子状物質を放置しておくと前述の如く検出精
度を劣化させるので好ましくない。本発明は、電極に間
欠的に通電し該電極を発熱させて、付着した粒子状物質
を焼失させるもので、これを実施する手段を第２図に電
気回路図として示す。If the attached particulate matter is left unattended, the detection accuracy will deteriorate as described above, which is not preferable. According to the present invention, the electrodes are intermittently energized to generate heat, thereby burning out attached particulate matter. FIG. 2 shows a means for implementing this as an electric circuit diagram.

６は放電電圧用電源、７は検出電圧用電源、８は加熱用
電源、９はタイマー、１０はイオン電流検出回路、１１
，１１．・・・・・・１１は継電器である。6 is a power supply for discharge voltage, 7 is a power supply for detection voltage, 8 is a power supply for heating, 9 is a timer, 10 is an ion current detection circuit, 11
, 11. ...11 is a relay.

継電器１１．１１・・・・・・１１の応動時間はタイマ
ー９によって設定されており、イオン電流検出期間中は
すべての継電器が同時に図中の黒丸接点側で閉じている
が、一定時間毎に一斉に黒丸接点側が開いて他方の白丸
接点で閉じるようになっている。白丸接点側で閉じると
同時に放電電極側の接地極４１ａ、４１ｂ、高圧電極４
２、検出電極側の接地極５１ａ、５１ｂ及び低圧電極５
２のすべてが直列に接続され、加熱用電源８より各電極
を５００℃異席に発熱させるに必要な電圧が印加される
。イオン電流検出期間中に電極に付着していた粒子状物
質はこの間に焼失し除去される。従って電極に粒子状物
質が多量に付着することはなく、放電条件や検出条件が
略一定に維持されるので、排ガス中の粒子状物質を正確
に検出することができる。The response time of the relays 11.11...11 is set by the timer 9, and during the ion current detection period, all the relays are closed at the same time on the black circle contact side in the figure, but at regular intervals The black circle contact side opens all at once, and the other white circle contact closes. At the same time as closing on the white circle contact side, the ground electrodes 41a and 41b on the discharge electrode side, and the high voltage electrode 4
2. Ground electrodes 51a, 51b and low voltage electrode 5 on the detection electrode side
2 are connected in series, and a heating power source 8 applies a voltage necessary to cause each electrode to generate heat of 500°C. Particulate matter adhering to the electrode during the ion current detection period is burned away and removed during this period. Therefore, a large amount of particulate matter does not adhere to the electrode, and the discharge conditions and detection conditions are maintained substantially constant, so particulate matter in the exhaust gas can be detected accurately.

尚、発熱時の電極は必ずしも直列に接続されることはな
く、並列でも良い。又、各電極に対して異なる加熱用電
源を使用しても良い。各電極を支持している碍子に発熱
体を内蔵させ、電極発熱時に同時に碍子を発熱させれば
碍子表面での漏洩を防止することもできる。Note that the electrodes for generating heat are not necessarily connected in series, but may be connected in parallel. Also, different heating power sources may be used for each electrode. If a heating element is built into the insulator supporting each electrode and the insulator generates heat at the same time as the electrodes generate heat, leakage on the surface of the insulator can also be prevented.

【図面の簡単な説明】[Brief explanation of the drawing]

第１図は本発明検出装置の排ガス接触部分の一実施例を
示す斜視図、第２図は本発明検出装置の一実施例を示す
電気回路図である。FIG. 1 is a perspective view showing one embodiment of the exhaust gas contacting portion of the detection device of the present invention, and FIG. 2 is an electric circuit diagram showing one embodiment of the detection device of the present invention.

Claims (1)

【特許請求の範囲】[Claims] コロナ放電により粒子状物質を帯電させる放電電圧用電
源及び放電電極からなる帯電手段と、帯電粒子状物質に
よるイオン電流を検出する検出電圧用電源及び検出電極
からなる検出手段とを具備したものにおいて、前記放電
電極及び検出電極に一定時間毎に断続的に通電すること
によりこれら両電極を発熱させる間欠加熱手段を付設し
たことを特徴とする排ガス中粒子状物質検出装置。A charging device comprising a discharge voltage power source and a discharge electrode for charging particulate matter by corona discharge, and a detection means comprising a detection voltage power source and a detection electrode for detecting an ionic current due to the charged particulate matter, An apparatus for detecting particulate matter in exhaust gas, characterized in that an intermittent heating means is provided for causing the discharge electrode and the detection electrode to generate heat by intermittently applying electricity to the discharge electrode and the detection electrode at regular intervals.