JPH0738846Y2 - Alcohol concentration measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an alcohol concentration measuring device which is preferably used in a fuel injection control unit of an engine which uses, for example, a methanol mixed fuel as a fuel, and particularly to a temperature measuring device. The present invention relates to an alcohol concentration measuring device capable of improving characteristics.

[Conventional technology]

Recently, alcohol-mixed gasoline containing methanol has been used as a fuel for automobile engines instead of pure gasoline.

Since the stoichiometric air-fuel ratio naturally changes between genuine gasoline and alcohol-blended gasoline, the fuel injection amount, ignition timing, etc. of the engine also differ.

Here, looking at the fuel injection amount T _i when using genuine gasoline with an alcohol concentration of 0%, T _i = T _P × α × α ′ × C _oef + T _S (1) where T _P : basic Injection amount α: Air-fuel ratio feedback correction coefficient α ′: Basic air-fuel ratio learning correction coefficient _Coef : Various correction coefficients T _S : Battery voltage correction coefficient At this time, the air-fuel ratio feedback correction coefficient α is corrected based on the oxygen concentration signal from the oxygen sensor, and the basic air-fuel ratio learning correction coefficient α ′ is learned and corrected from the basic injection amount T _P and the engine speed N. , The theoretical air-fuel ratio A / F is controlled to be 14.7.

In this way, the air-fuel ratio A / F of genuine gasoline is 14.7, but when using methanol with an alcohol concentration of 100%, it is necessary to control the air-fuel ratio A / F to 6.5.
The stoichiometric air-fuel ratio A / F is about twice different when the alcohol concentration is in the range of 0 to 100%.

Therefore, when using alcohol blended gasoline,
From equation (1), the fuel injection amount T _i ′ is calculated as T _i ′ = M _K × T _P × α × α ′ × C _oef + T _S (2) where M _K is a constant determined by the alcohol concentration. is there.

Therefore, an engine using alcohol-blended gasoline is equipped with an alcohol concentration measuring device called an alcohol sensor, generates an output voltage corresponding to the alcohol concentration, and calculates the equation (2) based on the output voltage value. Is designed to do. As this type of alcohol concentration measuring device, a resistance type alcohol concentration measuring device that detects the alcohol concentration from the electric conductivity of gasoline and alcohol, a capacitance type alcohol concentration measuring device that uses the change in the dielectric constant of alcohol mixed gasoline An apparatus, an optical alcohol concentration measuring apparatus utilizing a change in refractive index, and the like are known.

Here, among the above-described alcohol concentration measuring devices, as a fuel injection control device using a capacitance type alcohol concentration measuring device, those shown in FIGS. 2 to 6 are conventionally known.

First, in FIG. 2, reference numeral 1 is an automobile engine, and the engine 1 has a combustion chamber with an alcohol-mixed gasoline 8 to be described later.
An intake valve 3 for injecting air is provided, an intake manifold 3 for intake of outside air is provided, and an air flow meter 5 for measuring an intake air amount Q is provided between the intake manifold 3 and the intake filter 4. In addition, the engine 1 has an exhaust manifold 6
The exhaust manifold 6 is provided with an oxygen sensor (not shown).

A fuel tank 7 stores the alcohol-mixed gasoline 8 as a liquid, and a fuel pump 9 for discharging the alcohol-mixed gasoline 8 is provided in the fuel tank 7.

10 is a fuel pipe, and one end of the fuel pipe 10 is a fuel filter 11
Is connected to the discharge side of the fuel pump 9, the other end is connected to the injection valve 2 and the inflow side of the pressure regulator 12, and the outflow side of the pressure regulator 12 is connected to the fuel tank 7 via the return pipe 13. ing.

Reference numeral 14 is, for example, a capacitance type alcohol concentration measuring device provided in the middle of the fuel pipe 10 as a flow path. The alcohol concentration measuring device 14 detects the alcohol concentration in the alcohol mixed gasoline 8 flowing in the fuel pipe 10. To do.
Here, as shown in FIG. 3, the alcohol concentration measuring device 14 has cylindrical pipe members 15 and 16 each having a substantially L shape or a substantially T shape.
A tubular casing 18 formed by joining in a letter shape, one end side of the pipe member 15 being closed by an insulating plug body 17, and a concentration detector 19 and a temperature sensor 27 described later, etc., and a casing. The 18 pipe members 15 and 16 are formed of, for example, a conductive iron pipe plated with nickel or the like. The other end of the pipe member 15 serves as an inflow port 15A for the alcohol-mixed gasoline 8, and the pipe member 1
The tip side of 6 becomes an outlet 16A, and the inlet 15A and the outlet 16A
Is connected in the middle of the fuel pipe 10, and the alcohol-blended gasoline 8 flows in the casing 18 in the direction of arrow A.

A concentration detector 19 is provided in the casing 18 and detects the alcohol concentration of the alcohol-mixed gasoline 8 flowing in the casing 18. The concentration detector 19 is provided from one end of the pipe member 15 via the plug body 17. An elongated rod-shaped center electrode 20 that projects into the pipe member 15 in the axial direction and constitutes a coaxial cylindrical counter electrode together with the pipe member 15, and a pipe member for supporting one end side of the center electrode 20 together with the plug body 17. An insulating fitting member 22 fitted to one end side of 15 via a conductive cylindrical body 21.
And a center electrode that is radially outwardly projected from the outer end surface of the fitting member 22 and is fastened to the fitting member 22 via a washer 24 by screwing a nut 23 onto one end of the center electrode 20.
It is composed of a terminal 25 on the side of 20 and a terminal 26 on the ground side that is sandwiched between the tubular body 21 and the fitting member 22 and projects outward in the radial direction. The terminal 26 is made of a conductive tubular body 21. It is connected to the pipe member 15 via.

Here, since the center electrode 20 of the concentration detector 19 extends in the pipe member 15 in the axial direction and constitutes a coaxial cylindrical counter electrode together with the pipe member 15, the concentration detector 19 has terminals 25, 26.
By applying a voltage from the outside between the center electrode 20 and the pipe member 15 via the
The alcohol concentration of the alcohol-mixed gasoline 8 flowing in the direction of the arrow A between and can be detected as the electrostatic capacitance C _S as in the following formula (3).

C _S = ε _S / d (3) where ε: Dielectric constant of alcohol-blended gasoline S: Electrode area d: Distance between electrodes And the concentration detector 19 is an oscillation circuit externally connected between terminals 25 and 26. The capacitance C _S is converted into an output voltage V _{O as} shown in FIG. 5 through a frequency-voltage conversion circuit (neither is shown) or the like, and this is output to a control unit 29 described later. It has become.

27 is a temperature sensor located between the inlet 15A of the pipe member 15 and the pipe member 16 and fixed to the outer peripheral side of the pipe member 15 with an adhesive 28 or the like, and the temperature sensor 27 is a thermistor, a posistor, or the like. The temperature of the alcohol-mixed gasoline 8 flowing in the casing 18 (hereinafter referred to as the fuel temperature t) is detected by the temperature sensitive resistance element. That is, the temperature sensor 27 detects the fuel temperature t of the alcohol-mixed gasoline 8 as the temperature transmitted to the pipe member 15, and outputs this detection signal to the control unit 29.

Reference numeral 29 is a control unit composed of, for example, a microcomputer. The control unit 29 is, as shown in FIG. 4, an injection charge calculating device 30 for calculating the injection charge T _i ′ of the formula (2), and an input side for detecting the concentration. It is connected to the device 19 and the temperature sensor 27, and is configured to include an alcohol concentration temperature correction device 31 for correcting the temperature of the alcohol concentration M on the basis of these signals, which will be described later. The alcohol concentration M is output to the injection charge calculation device 30. The injection charge computing device 30 has an input side connected to the air flow meter 5 for detecting the intake air amount Q, a crank angle sensor 32 for detecting the engine speed N, and the like, and an output side connected to the injection valve 2.

In the fuel injection control device configured as described above, first, when the engine 1 is started, the fuel pump 9 is operated to discharge the alcohol-mixed gasoline 8 in the fuel tank 7 toward the injection valve 2 into the fuel pipe 10. . An alcohol concentration measuring device 14 provided in the middle of the fuel pipe 10 detects the alcohol concentration M of the alcohol-blended gasoline 8 flowing through the casing 18 with a built-in concentration detector 19, and a temperature sensor 27. The fuel temperature t of the alcohol-mixed gasoline 8 is detected, and these detection signals are output to the alcohol concentration temperature correction device 31 of the control unit 29.

Here, the output voltage V _O output from the concentration detector 19 corresponding to the alcohol concentration M has temperature dependence as shown in FIG. 5, and for example, the fuel temperature t is t = 0 ° C., 20 ° C., The output voltage V _O drops as it changes to 60 ° C. Therefore, the alcohol concentration temperature correction device 31 uses the output voltage from the concentration detector 19.
Based on the fuel temperature t from the temperature sensor 27, V _O
There t = 0 ° C., even when the 60 ° C., the output voltage V _O is t = 20 ° C. is corrected to a value corresponding to the output voltage V _O at a standard output voltage or standard corrected at this time The alcohol concentration is output to the injection amount calculation device 30.

Then, the injection amount calculation device 30 calculates the basic injection amount T _P based on the intake air amount Q from the air flow meter 5 and the engine speed N from the crank angle sensor 32, and the alcohol from the alcohol concentration temperature correction device 31. wherein based on the concentration M, etc. (2) of the injection amount T _i 'is calculated and the injection amount T _i'
An injection pulse having a pulse duty corresponding to is output to the injection valve 2 to inject the alcohol-mixed gasoline 8 having the injection amount T _i ′ into the engine 1 from the injection valve 2.

[Problems to be solved by the device]

By the way, in the above-mentioned conventional technique, the temperature sensor 27 is fixed to the outer peripheral surface of the pipe member 15 of the casing 18 using the adhesive 28, and the temperature sensor 27 is brought into contact with the outer peripheral surface of the pipe member 15. Since the pipe member 15 is formed by applying nickel plating or the like to the iron pipe, the thermal conductivity cannot be increased so much, and the fuel temperature t of the alcohol-mixed gasoline 8 flowing inside the pipe member 15 is Although it is transmitted to the temperature-sensitive sensor 27 through the temperature sensor 27, a time delay of several seconds occurs as shown in FIG. That is, the characteristic line shown in FIG.
33 indicates that when the fuel of 100% methanol at 40 ° C. is circulated in the casing 18, the temperature sensor 27 detects the fuel temperature t (=
The relationship between the time after the start of (40 ° C) detection and the detection signal is shown, and it can be seen that this also causes a time delay of about several seconds.

Therefore, in the prior art, when the fuel temperature t of the alcohol-mixed gasoline 8 flowing through the casing 18 changes, this change cannot be detected by the temperature sensor 27 with a desired responsiveness, and the alcohol concentration temperature correction device during this period. The temperature correction of the alcohol concentration M cannot be normally performed by 31, and an incorrect alcohol concentration M is output to the injection amount calculation device 30, so that the injection amount T _i ′ changes abnormally and the rotational output of the engine 1 fluctuates. There is a problem.

The present invention has been made in view of the above-mentioned problems of the prior art, and the present invention can effectively improve the responsiveness of the temperature sensor.
It is an object of the present invention to provide an alcohol concentration measuring device capable of constantly measuring alcohol concentration with improved temperature characteristics.

[Means for Solving the Problems]

The feature of the configuration adopted by the present invention to solve the above-mentioned problems is that a flow path of liquid flowing in the casing is formed in a crank shape in a casing, and a concentration detector is provided on one side of the crank shape flow path. The mounting bracket is provided on the other side of the crank-shaped channel so as to project, and the mounting bracket is provided with a temperature sensor so as to come into contact with the liquid flowing in the casing.

Further, it is preferable that the temperature-sensitive sensor is composed of a temperature-sensitive element made of platinum.

[Action]

With the above configuration, the concentration detector and the temperature sensor can be reasonably arranged in the casing, and the temperature sensor can be brought into direct contact with the liquid flowing in the casing. Can be detected. Further, the temperature sensor can be constituted by a temperature sensitive element made of platinum,
Liquid temperature can be detected with high accuracy.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. In the embodiments, the same components as those of the prior art shown in FIGS. 2 to 4 described above are designated by the same reference numerals, and the description thereof will be omitted.

In the figure, 41 is an alcohol concentration measuring device, and 42 is the measuring device 41.
Shows a cylindrical casing that constitutes the main body of the casing 42. The casing 42 is formed into a substantially H shape by joining pipe members 43 and 44, which are cylindrical iron pipes whose surfaces are nickel-plated, with an intermediate pipe 45. Formed, pipe member 4
3,44 extend in parallel in opposite directions through the intermediate pipe 45. One end of the pipe member 43 is closed by the plug 17 like the pipe member 15 described in the prior art, the concentration detector 19 is attached, and the other end becomes the inlet 43A of the alcohol-mixed gasoline 8. ing.
Further, one end of the pipe member 44 serves as the outflow port 44A, and the other end thereof is closed by the insulating plug 46. And
The casing 41 has an inlet 43A and an outlet 44A for the fuel pipe 10
Is connected in the middle thereof, and the inside thereof is a crank-shaped flow passage F having a “” shape in which the alcohol-mixed gasoline 8 flows in the direction of arrow A. The concentration detector 19 is provided in the pipe member 43 on one side of the flow path F, and the temperature sensor 54 described later is provided in the pipe member 44 on the other side of the flow path F.
Is provided.

47 is an insulating fitting member fitted to the other end of the pipe member 44 via an insulating cylinder 48, and 49 is the fitting member 47, the plug 46.
Showing a mounting bracket that axially penetrates through the pipe member 44 and has one end protruding into the pipe member 44.The mounting bracket 49 is formed of an elongated metal pipe. Is screwed on.
A temperature sensor 54, which will be described later, is attached to one end of the mounting bracket 49, and a positive side lead wire 52, one end of which is connected to the temperature sensor 54, is inserted into the attachment bracket 49 to the outside. It has been derived. The mounting bracket 49 is connected to the minus side of the temperature sensor 54, and is grounded on the pipe member 44 side through the conductive plate 53 fixed to the end surface of the plug 46.

Further, 54 is a temperature sensor attached to one end of the mounting bracket 49, the temperature sensor 54 is constituted by a temperature sensitive element such as a temperature sensitive resistance element having platinum deposited on its surface,
The resistance value changes sensitively to the ambient temperature, and at the same time, it has corrosion resistance to methanol and the like. The temperature sensor 54 has a positive side connected to an external power source (not shown) and the control unit 29 via a lead wire 52, and a negative side connected to a pipe member 44 via a mounting bracket 49 and a conductive plate 53. ing. The temperature sensor 54 is disposed in the pipe member 44 at a position facing the intermediate pipe 45.
The fuel temperature t can be detected with high responsiveness by directly contacting the alcohol-mixed gasoline 8 flowing into the inside of the cylinder 44 in the direction of the arrow A.

The alcohol concentration measuring device 41 according to the present embodiment has the above-mentioned configuration, and its basic operation is not particularly different from that according to the prior art.

Therefore, in the present embodiment, the crank-shaped flow passage F is formed in the casing 42, the concentration detector 19 is provided in the pipe member 43 that is one side of the flow passage F, and the other side of the flow passage F is provided. A mounting bracket 49 is projected into the pipe member 44, a temperature sensor 54 made of platinum is attached to the projecting end of the mounting bracket 49, and the temperature sensor 54 flows in the casing 42 in the arrow A direction. 8, the concentration detector 19 and the temperature sensor 54 can be rationally arranged in the limited space of the casing 42, and the workability at the time of assembling can be improved. The fuel temperature t of the gasoline 8 can be detected by the temperature sensor 54 with high responsiveness, and the detection accuracy of the fuel temperature t can be improved.
In particular, since the temperature sensor 54 is arranged in the vicinity of the connecting portion between the pipe member 44 and the intermediate pipe 45, the temperature sensor 54 is provided in the intermediate pipe.
The alcohol-mixed gasoline 8 flowing into the pipe member 44 from 45 can be brought into contact without stagnation, the change in the fuel temperature t can be detected more sensitively, and the responsiveness can be greatly improved.

Therefore, in this embodiment, the fuel temperature t of the alcohol-blended gasoline 8 can be detected with high responsiveness by the temperature sensor 54, the temperature characteristic of the concentration detector 19 can be effectively improved, and the alcohol concentration can be measured. Can always be stabilized. Then, as described in the prior art, it is possible to prevent the injection amount T _i ′ from changing abnormally, stabilize the rotational output of the engine 1, and so on.

In the above embodiment, the temperature sensor 54 is provided in the pipe member 44 via the mounting bracket 49, but instead of this, the temperature sensor is provided in the middle of the intermediate pipe 45, for example, from the pipe member 44 side. The sensor 54 may be provided so as to project. Further, the alcohol concentration measuring device 41 may be provided not only in the middle of the fuel pipe 10 but also in another passage, for example, in the return pipe 13.

Further, in the above-mentioned embodiment, it was described that the crank-shaped flow passage F having a “” shape, through which the alcohol-mixed gasoline 8 circulates, is formed in the casing 41, but the crank-shaped flow passage has an F “” shape. However, the present invention is not limited to this, as long as it has two corners, and it may be, for example, a C-shaped crank-shaped channel. Further, the pipe members 43 and 44 forming the casing 41 do not necessarily have to be arranged in parallel on the same plane, and the pipe seating members 43 and 44 may be arranged above and below the intermediate pipe 45 or left and right. You may make it arrange | position in a crank shape by giving an angle.

Further, in the above embodiment, the alcohol concentration temperature correction device
Although 31 is described as being provided in the control unit 29, instead of this, the alcohol concentration temperature correction device 31 is divided from the control unit 29, and is disposed near the terminals 25 and 26 of the alcohol concentration measuring device 41. Alternatively, in this case, the number of lead wires connecting the measuring device 41 and the control unit 29 can be reduced.

[Effect of device]

As described above in detail, according to the present invention, a crank-shaped flow path is formed in a casing, a concentration detector is provided on one side of the flow path, and a temperature sensor is provided on the other side of the flow path via a mounting bracket. Since the sensor is provided, the concentration detector and the temperature sensor can be reasonably arranged in the limited space in the casing, the workability at the time of assembly can be improved, and the liquid flowing in the casing can be prevented. The temperature sensor can detect with high responsiveness, and even when the temperature of the liquid changes, the alcohol concentration in the liquid can be measured by improving the temperature characteristics, and it is effective to change the injection amount and the rotational output of the engine, for example. It is possible to achieve various effects such as being able to be prevented.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of an alcohol concentration measuring apparatus showing an embodiment of the present invention, FIGS. 2 to 6 show prior arts, FIG. 2 is an overall view of a fuel injection control apparatus, and FIG. 3 is alcohol. FIG. 4 is a control sectional view of the concentration measuring device, FIG. 4 is a control block diagram, FIG. 5 is a characteristic diagram showing the relationship between alcohol concentration and output voltage, and FIG. 6 is a characteristic diagram showing the detection characteristic of the temperature sensor. is there. 17,46 ... Plug, 19 ... Concentration detector, 20 ... Center electrode, 2
5,26 …… Terminal, 41 …… Alcohol concentration measuring device, 42 ……
Casing, 43,44 ... Pipe member, 45 ... Intermediate pipe, 49 ... Mounting bracket, 54 ... Temperature sensor.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hideki Kano Inventor Hideki Kano 1671 Kasukawa-cho, Isesaki-gun, Gunma Nippon Electric Equipment Co., Ltd. (72) Toshiro Takahashi 1671 1 Kasukawa-cho, Isesaki-shi, Gunma Nippon Electric Equipment Incorporated (72) Inventor, Satoshi Kobayashi 1672, Kasukawa-cho, Isesaki-shi, Gunma Nippon Electric Equipment Co., Ltd. (72) Inventor Kiyoshi Takeuchi, 2 Takara-cho, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd. (72) Creator Toru Kita 2 Takara-cho, Kanagawa-ku, Yokohama, Kanagawa Pref. Nissan Motor Co., Ltd. (56) References: JP-A-1-196557 (JP, A) Fukukaihei 1-163862 (JP, U)

Claims (2)

[Scope of utility model registration request] 1. A cylindrical casing which is provided in the flow path of a liquid mixed with alcohol and through which the liquid flows, and an alcohol concentration of the liquid which is provided inside the casing and flows through the casing. In an alcohol concentration measuring device comprising a concentration detector and a temperature sensor for detecting the temperature of the liquid in order to perform temperature correction of the alcohol concentration detected by the concentration detector, the casing is circulated in the casing. A liquid flow path is formed in a crank shape, the concentration detector is provided on one side of the crank shape flow path, and a mounting bracket is provided so as to project on the other side of the crank shape flow path. An alcohol concentration measuring device, wherein the temperature sensor is provided so as to come into contact with a liquid flowing in the casing. 2. The alcohol concentration measuring device according to claim 1, wherein the temperature sensor is a utility model registration device including a temperature sensor made of platinum.