JPH05231248A - Fuel steam detecting device for internal combustion engine - Google Patents

Abstract

(57) [Abstract] [Purpose] To improve the detection accuracy of the fuel vapor component in the air-fuel mixture supplied from the canister of the fuel vapor emission suppression device to the engine intake system. [Structure] A hot wire type flow meter 18 is attached to a bottom chamber 153 of a closed bottom type canister 15. The flow rate of the air-fuel mixture mixture passing through the purge pipe 17 is calculated based on the detection values of the throttle valve opening sensor 4 and the intake pipe absolute pressure sensor 10. The fuel vapor flow rate (component) is calculated based on this flow rate and the output value of the hot-wire flow meter 18. Since the flow rate of the air-fuel mixture in the bottom chamber 153 is low, the flow rate is measured by the flow meter 18 at a low flow rate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel vapor detection device for an internal combustion engine having a fuel vapor emission suppressing device, and more particularly to a fuel vapor component in a mixture gas supplied from a canister of the fuel vapor emission suppressing device to an engine intake system. To a device for detecting.

[0002]

2. Description of the Related Art As a device for detecting a fuel vapor component in an air-fuel mixture supplied from a canister of a fuel vapor emission suppressing device to an engine intake system, a canister 100 and an engine intake system are shown in FIG. 10 (a). Purge passage 1 to connect
A mass flowmeter 102 (for example, a hot wire type flowmeter) is provided in the middle of 01, and the fuel vapor component in the air-fuel mixture is detected based on the output value of the flowmeter. Proposed (Japanese Patent Application No. 3-80726)
issue).

Further, a so-called closed bottom type canister in which the atmosphere is introduced from the upper part of the canister as shown in FIG. 10 (b) is conventionally known (Japanese Utility Model Laid-Open No. 60-70766, Japanese Patent Laid-Open Publication No. 60-70676). Kaisho 62-265
460).

[0004]

Generally, the output value of a mass flowmeter tends to increase as the flow velocity of gas increases, as shown in FIG. On the other hand, the flow velocity of the air-fuel mixture flowing through the purge passage largely changes depending on the throttle valve opening of the engine intake system and the absolute pressure in the intake pipe, so that the amount of change in the output value of the mass flowmeter also becomes large and the detection error increases. For this reason, the above proposed fuel vapor detection apparatus has room for improvement in terms of detection accuracy. The present invention has been made in view of the above points, and can detect the fuel vapor component in the air-fuel mixture and reduce the detection error without being affected by the flow velocity of the air-fuel mixture flowing in the purge passage. An object is to provide a fuel vapor detection device.

[0005]

To achieve the above object, the present invention provides a canister for adsorbing fuel vapor generated from a fuel tank and an air-fuel mixture containing the fuel vapor adsorbed in the canister to an engine intake system. In a fuel vapor detection device for detecting a fuel vapor component in the air-fuel mixture of an internal combustion engine having a purge passage for supplying, a purge flow rate calculating means for calculating a flow rate of the air-fuel mixture flowing in the purge passage, and the purge passage are provided. The mass flow meter for measuring the flow rate of the flowing air-fuel mixture, and the fuel vapor detection means for detecting the fuel vapor component based on the purge flow rate calculation value of the purge flow rate calculation means and the output value of the mass flow meter are provided. The passage has a chamber in the middle thereof, and the mass flowmeter is arranged in the chamber.

Further, a closed bottom type canister for adsorbing fuel vapor generated from a fuel tank and an internal combustion engine having a purge passage for supplying a mixture containing the fuel vapor adsorbed in the canister to an engine intake system A fuel vapor detection device for detecting a fuel vapor component in the air-fuel mixture, a purge flow rate calculating means for calculating a flow rate of the air-fuel mixture flowing through the purge passage, and a mass flow rate for measuring a flow rate of the air-fuel mixture flowing through the purge passage. And a fuel vapor detection means for detecting a fuel vapor component based on the purge flow rate calculation value of the purge flow rate calculation means and the output value of the mass flow rate meter, wherein the mass flow rate meter is in the bottom chamber of the canister. It is arranged to be.

[0007]

In the chamber provided in the middle of the purge passage, the flow velocity of the air-fuel mixture decreases, and the measurement by the mass flow meter
It is performed under a low flow rate.

In the bottom chamber of the closed bottom type canister, the flow velocity of the air-fuel mixture is low, and the measurement by the mass flow meter is performed at a low flow velocity.

[0009]

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is an overall configuration diagram of a fuel supply control device according to an embodiment of the present invention. Reference numeral 1 indicates, for example, a 4-cylinder internal combustion engine, and a throttle body is provided in the middle of an intake pipe 2 of the engine 1. 3 is provided, and a throttle valve 301 is arranged inside thereof. A throttle valve opening (θTH) sensor 4 is connected to the throttle valve 301, and an electronic control unit (hereinafter referred to as “ECU”) outputs an electric signal according to the opening of the throttle valve 301.
Supply to 5. The ECU 5 constitutes a purge flow rate calculation means and a fuel vapor detection means.

The fuel injection valve 6 is provided for each cylinder between the engine 1 and the throttle valve 301 and slightly upstream of an intake valve (not shown) of the intake pipe 2, and each fuel injection valve 6 is provided with a fuel pump 7. Is connected to the fuel tank 8 via and is electrically connected to the ECU 5, and the valve opening time of the fuel injection valve 6 is controlled by a signal from the ECU 5.

An intake pipe absolute pressure (PBA) sensor 10 is provided immediately downstream of the throttle valve 301 via a pipe 9. The absolute pressure signal converted into an electric signal by the absolute pressure sensor 10 is sent to the ECU 5. Supplied.

The engine speed (NE) sensor 11 is mounted around a cam shaft or crank shaft (not shown) of the engine 1, and a signal pulse (hereinafter referred to as "hereinafter referred to as" a signal pulse "at a predetermined crank angle position every 180 degrees rotation of the crank shaft of the engine 1). (Referred to as “TDC signal pulse”), and this TDC signal pulse is supplied to the ECU 5.

O ₂ sensor 1 as an exhaust gas concentration detector
2 is attached to the exhaust pipe 13 of the engine 1, detects the oxygen concentration in the exhaust gas, outputs a signal according to the concentration, and supplies it to the ECU 5.

A two-way valve 14 which constitutes a fuel vapor discharge suppressing device, a canister 15 containing an adsorbent 151, and a solenoid for driving the valve are provided between the closed upper portion of the fuel tank 8 and the throttle body 3. A purge control valve 16 which is a linear control valve (EACV) is provided. The solenoid of the purge control valve 16 is connected to the ECU 5, and the purge control valve 16 is controlled according to a signal from the ECU 5 to linearly change the valve opening amount.

The canister 15 is of a closed bottom type having an air introduction hole 152 in its upper part and a bottom chamber 153 in its lower part, and the bottom chamber 153 has a heating wire for measuring the flow rate of the air-fuel mixture in the chamber. A type flow meter (mass flow meter) 18 is attached. The hot-wire flow meter 18 is connected to the ECU 5 and supplies the ECU 5 with an output signal according to the flow rate of the air-fuel mixture containing the fuel vapor flowing in the bottom chamber 153. This hot wire type flow meter 1
No. 8 exposes the heated platinum wire to the air flow,
The platinum wire takes advantage of the fact that heat is taken away and the temperature of the platinum wire lowers, so that its electric resistance decreases. Since this hot-wire type flow meter 18 has a characteristic that the output value changes depending on the flow velocity of the gas to be measured as shown in FIG. 2, the flow amount should be measured, for example, at a flow velocity of 0.4 [m / min] or less. Is desirable. Therefore, in this embodiment, by providing the flow meter 18 in the bottom chamber 153, the flow rate of the air-fuel mixture can be measured while satisfying this condition. Thereby, the measurement error of the heat ray flow meter 18 can be reduced.

According to this fuel vapor discharge inhibiting device, when the fuel vapor (fuel vapor) generated in the fuel tank 8 reaches a predetermined set pressure, the positive pressure valve of the two-way valve 14 is opened and the canister 15 is opened. It flows in, is adsorbed by the adsorbent 151 in the canister 15, and is stored. The purge control valve 16 is closed when the solenoid is not energized by the control signal from the ECU 5, but when the solenoid is energized according to the control signal, the valve is opened according to the energizing amount. The purge control valve 16 is opened by the amount, and the canister 1
Due to the negative pressure in the intake pipe 2, the vaporized fuel temporarily stored in the atmosphere 5 is introduced into the atmosphere introduction port 152 provided in the canister 15.
The air is sucked into the intake pipe 2 through the purge control valve 16 together with the outside air sucked from and is sent to each cylinder. Further, when the fuel tank 8 is cooled by the outside air and the negative pressure in the fuel tank increases,
The negative pressure valve of the two-way valve 14 opens, and the evaporated fuel temporarily stored in the canister 15 is returned to the fuel tank 8. In this way, the fuel vapor generated in the fuel tank 8 is prevented from being released to the atmosphere.

The ECU 5 shapes the waveforms of input signals from various sensors, corrects the voltage level to a predetermined level, converts an analog signal value into a digital signal value, and the like, a correction coefficient KO described later. ₂ and a central processing circuit that executes an EACV value calculation program (hereinafter, “CPU”)
That is, it is composed of various calculation programs executed by the CPU, a storage unit for storing a Ti map and a calculation result, which will be described later, an output circuit for supplying a drive signal to the fuel injection valve 6 and the purge control valve 16.

The CPU discriminates various engine operating conditions such as a feedback control operating region and an open loop control operating region according to the oxygen concentration in the exhaust gas based on the engine operating parameter signals from the various sensors described above, and Based on the following equation (1) according to the operating state,
The fuel injection time Tout of the fuel injection valve 6 is calculated in synchronization with the TDC signal pulse.

Tout = Ti × KO ₂ × K1 + K2 (1) Here, Ti is a reference value (basic fuel amount) of the fuel injection time Tout of the fuel injection valve 6, and the engine speed NE and the intake pipe absolute pressure PBA. Is read from the Ti map set in accordance with

KO ₂ is an air-fuel ratio feedback correction coefficient and is set according to the oxygen concentration in the exhaust gas detected by the O ₂ sensor 12 during feedback control, and a plurality of open loop control operations without feedback control are performed. In the region, it is a coefficient set according to each operating region.

K1 and K2 are other correction coefficients and correction variables calculated according to various engine operating parameter signals, respectively, and optimization of various characteristics such as fuel consumption characteristics and engine acceleration characteristics according to the engine operating state is performed. Is set to a predetermined value.

The CPU supplies the drive signal for opening the fuel injection valve 6 based on the fuel injection time Tout obtained as described above to the fuel injection valve 6 through the output circuit.

Next, referring to FIGS. 3 to 6, the purge pipe 1 will be described.
A method of calculating the flow rate VQ of the flow rate of the fuel vapor (actual fuel vapor flow rate, hereinafter referred to as “vapor flow rate”) supplied to the throttle body 3 via the PC port 17a of No. 7 will be described. The PC port 17a is provided so as to be located downstream of the valve 301 when the throttle valve 301 is open and upstream of the valve 301 when the throttle valve 301 is closed. Further, in the following description, “PC flow rate” means the flow rate of the mixture of fuel vapor and air calculated based on the throttle valve opening degree θTH and the intake pipe absolute pressure PBA. The PC flow rate coincides with the purge flow rate (actual flow rate of the mixture of fuel vapor and air) TQ only when the air concentration is 100% (that is, when the fuel vapor concentration (hereinafter referred to as “vapor concentration”) is 0%). At other times, it has a constant relationship with the purge flow rate TQ as described later.

FIG. 3 is a diagram showing the relationship between the throttle valve opening degree θTH [%] and the basic PC flow rate PCQ0 [l / min]. Curves A, B and C are shown in the intake pipe, respectively. It corresponds to the value of the absolute pressure PBA. Here, for the basic PC flow rate PCQ0, the purge control valve 16 is fully opened,
It also represents the PC flow rate when the air is 100%. Using the relationship of FIG. 3, the basic PC flow rate PCQ0 can be calculated according to the throttle valve opening degree θTH and the intake pipe absolute pressure PBA.

FIG. 4 is a diagram showing the flow rate characteristic of the purge control valve 16, and the flow rate ratio ηQ [%] is shown in FIG.
Is a parameter indicating the ratio of the PC flow rate corresponding to the valve opening area ratio VS [%] of the above, and the PC flow rate PCQ1 can be obtained by multiplying the basic PC flow rate PCQ0 by the flow rate ratio ηQ.

FIG. 5 is a diagram showing the relationship between the vapor concentration β in the air-fuel mixture and the rate of change in the flow rate display. In the figure, the solid line corresponds to the output value QH of the hot-wire flow meter 22, and the broken line is the PC flow rate. (P
Corresponds to CQ1). Here, the flow rate display change rate is the ratio of the flow rate display value when β> 0% to the flow rate display value when β = 0% (that is, the above QH value or PCQ1 value) when the purge flow rate TQ is constant. Is a parameter indicating. That is, the flow rate display change rate represents the ratio of the QH value or PCQ1 value to the purge flow rate TQ (QH / TQ or PCQ1 / TQ), for example β = 0%.
In the case of, as shown in FIG. 6A, PCQ1 = QH =
Although TQ = 1 [l / min], when β = 100%, PCQ1 = 1.69 [l / min], QH for TQ = 1 [l / min] as shown in FIG. = 4.45 [l / m
in]. Therefore, using the relationship of FIG. 5, the PC flow rate P
The purge flow rate TQ and the vapor concentration β can be calculated based on the CQ1 and the hot wire flow meter output value QH. More specifically, since the relationship is as shown in FIG. 6 (c),
From the QH value and the PCQ1 value, the vapor concentration β and the purge flow rate TQ (the TQ is indicated by 1 l, 2 l, ... On the line where β is constant in the figure) can be obtained.

FIG. 7 is a flowchart of a program for calculating the above-mentioned vapor flow rate VQ and vapor concentration β.

In step S1, the throttle valve opening θT
Basic PC flow rate PC according to H and absolute pressure PBA in intake pipe
Q0 is calculated (see FIG. 3), and in step S2, the flow rate ratio ηQ is calculated according to the valve opening area ratio VS of the purge control valve (see FIG. 4). The basic PC flow rate PCQ0 is calculated, for example, by searching a PCQ0 map in which a PCQ0 value is set corresponding to a plurality of predetermined throttle valve openings and predetermined absolute pressures in the intake pipe, and performing interpolation calculation. In addition, the flow rate ratio ηQ corresponds to, for example, a plurality of predetermined valve opening area ratios η
It is calculated by searching the ηQ table in which the Q value is set and performing interpolation calculation.

In step S3, the PC is calculated by the following equation (2).
The flow rate PCQ1 is calculated.

PCQ1 = PCQ0 × ηQ (2) In step S4, the output value QH of the hot-wire flow meter 22 is read, and in step S5, VH is output according to the QH value and the PCQ1 value.
The vapor flow rate VQ is calculated by searching the Q map and performing interpolation calculation. The VQ map is a single map of the relationship of FIG. 6C and the relationship of VQ = TQ × β, and corresponds to, for example, a plurality of predetermined output values of the flow meter 18 and a plurality of predetermined values of the PC flow rate. Then, the vapor flow rate VQ is set.

In step S6, the purge flow rate TQ is calculated by searching the TQ map according to the QH value and the PCQ1 value and performing interpolation calculation. Figure 6 shows the TQ map.
Based on the relationship of (c), the purge flow rate TQ is set similarly to the VQ map. In step S7, the vapor concentration β (= VQ / TQ) is obtained, and this program ends.

FIG. 8 shows a flow chart of a program for calculating the vapor flow rate correction coefficient VQKO ₂ and the EAVC value, and this program is executed by the CPU of the ECU 5. Here, the vapor flow rate correction coefficient VQKO ₂ corrects the air-fuel ratio correction coefficient KO ₂ according to the vapor flow rate VQ, and the EAVC value controls the opening degree (opening area ratio VS) of the purge control valve 16. Is a control parameter value of.
As the EACV value increases, the opening degree of the purge control valve increases and the vapor flow rate VQ increases.

In step S11 of FIG. 8, the air amount QENG taken into the engine 1 is calculated by the following equation (3).

QENG = Tout × NE × CEQ (3) Here, Tout is the fuel injection time calculated by the equation (1), and CEQ is a constant for converting into the intake air amount.

In step S12, the target vapor flow rate ratio KQPOBJ is searched in the KQPOBJ map according to the detected engine speed NE and the intake pipe absolute pressure PBA. KQPOBJ map shows the engine intake air amount QEN
6 is a map in which a target vapor flow rate ratio with respect to G is set corresponding to a plurality of predetermined engine speeds NE and an intake pipe absolute pressure PBA.

In step S13, the engine intake air amount QENG and the target vapor flow rate ratio KQPOBJ are applied to the following equation (4) to calculate the target vapor flow rate QPOBJ.

QPOBJ = QENG × KQPOBJ (4) This target vapor flow rate QPOBJ may be appropriately corrected by the engine water temperature TW.

[0039] In step S14, temporarily stores the previously calculated value of VQKO ₂ value to a variable AVQKO _2. This is because the previously calculated value is used in step S17 described later. In step S15, the vapor flow rate VQ [l / min] calculated by the program of FIG.
Liquid gasoline equivalent GVQ (g / mi
n).

[0040]

[Equation 1] KVQ is a coefficient indicating the ratio of the gasoline vapor flow rate (l / min) included in the vapor flow rate VQ (l / min), and is 1 / 1.69. VMOL is 1 molar volume value,
It is represented by 22.4 l / MOL value at 0 ° C. Gasoline vapor molecular weight is about 64.

In step S16, the vapor flow rate correction coefficient VQKO ₂ is calculated based on the following equation (6) using the gasoline weight equivalent amount GVQ (g / min) thus obtained.

[0042]

[Equation 2] The basic injection weight is a value obtained by converting the reference value Ti of the fuel injection time into the fuel weight (g).

Vapor flow rate correction coefficient VQ thus obtained
KO ₂ is 1.0 when the purge control valve 16 is closed and when the purge is cut, and becomes 1.0 or less when the purge control valve 16 is opened and the purge is executed.

In step S17, the air-fuel ratio correction coefficient KO ₂ is corrected by the following equation (7).

KO ₂ = KO ₂ × VQKO ₂ / AVQKO ₂ (7) The fuel injection time Tout is calculated based on the equation (1) using the KO ₂ value thus corrected, and the fuel injection valve 6 Therefore, the fuel amount that suppresses the fluctuation of the air-fuel ratio due to the magnitude of the purge amount is supplied to the engine 1.

Further, in step S18, the vapor flow rate VQ is the target vapor flow rate QP calculated in step S3.
It is determined whether it is OBJ or more.

The answer to step S18 is negative (NO), that is, the calculated vapor flow rate VQ is the target vapor flow rate QPOBJ.
If it is smaller, the control amount EACV value corresponding to the valve opening amount of the purge control valve 16 is increased by the value C from the current value in order to increase the vapor amount to increase the fuel vapor emission suppression capability (step S19). This program ends.
The value C is an EACV value update constant. On the other hand, step S1
The answer of 8 is affirmative (YES), that is, the calculated vapor flow rate V
If Q is equal to or greater than the target vapor flow rate QPOBJ, the vapor amount is reduced to prevent the feedback control response from deteriorating, and the control amount EACV value of the purge control valve 16 is reduced from the current value by the value C (step S20), this program ends.

As described above, the actual vapor flow rate VQ is detected, and the fuel injection amount is corrected accordingly (step S1).
7) The air-fuel ratio variation caused by the purge is prevented, and the valve opening amount of the purge control valve 16 is controlled according to the detected vapor flow rate (steps S19, S20).
The average value of O ₂ is prevented from deviating significantly from the value of 1.0. As a result, when the air-fuel ratio control shifts from the open loop mode to the feedback mode, the air-fuel ratio correction coefficient KO
It is possible to prevent deterioration of responsiveness of feedback control that occurs when the average value used as the initial value of ₂ deviates significantly from the value of 1.0.

Further, according to this embodiment, the vapor flow rate VQ is calculated based on the flow rate value QH measured by the hot-wire flow meter 18 in the state where the flow velocity of the air-fuel mixture is low, so that the vapor flow rate VQ is higher than that of the conventional one. It is possible to improve the detection accuracy of the flow rate VQ and perform more appropriate air-fuel ratio control.

FIG. 9 is an overall configuration diagram of a fuel supply control device according to another embodiment of the present invention. A chamber 19 is provided in the middle of a purge passage 17, and a hot wire type flow meter 18 is provided in a canister 15. Instead, it is mounted in the chamber 19.
The other points are the same as the embodiment of FIG.

Also in this embodiment, since the flow velocity of the air-fuel mixture containing the fuel vapor decreases in the chamber 19, the flowmeter 1
8, the flow rate of the air-fuel mixture can be measured under a low flow velocity, and the same effect as the embodiment of FIG. 1 can be obtained.

In the case of this embodiment, the canister 1
5 is not limited to the closed bottom type, but FIG.
It is also possible to use one having an air introduction hole at the bottom as shown in 0 (a).

[0053]

As described in detail above, according to the fuel vapor detection device of the first aspect, the flow velocity of the air-fuel mixture decreases in the chamber provided in the middle of the purge passage, and the measurement by the mass flowmeter is low. Since it is performed under the flow velocity, the fuel vapor component can be detected and the detection error can be reduced without being affected by the flow velocity of the air-fuel mixture flowing in the purge passage.

Further, according to the fuel vapor detection device of the second aspect, the flow velocity of the air-fuel mixture is low in the bottom chamber of the closed bottom type canister, and the measurement by the mass flowmeter is performed under the low flow velocity. Therefore, the same effect as that of the first aspect can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a change rate of an output value of a hot-wire flow meter and a flow velocity of a gas to be measured.

FIG. 3 is a diagram showing a relationship between a throttle valve opening (θTH), an intake pipe absolute pressure (PBA), and a basic flow rate (PCQ0).

FIG. 4 is a diagram showing a flow rate characteristic of a purge pipe (17).

FIG. 5 is a diagram showing a relationship between a fuel vapor concentration (β) and a flow rate display change rate.

FIG. 6 is a diagram for explaining a relationship between a PC flow rate (PCQ1) and an output value (QH) of a hot wire type flow meter.

FIG. 7: Fuel vapor flow rate (VQ) and fuel vapor concentration (β)
6 is a flowchart of a program for calculating

FIG. 8 is a flow chart of a program for controlling a purge control valve opening degree and a fuel supply amount according to a fuel vapor flow rate (VQ).

FIG. 9 is a block diagram of another embodiment of the present invention.

FIG. 10 is a diagram showing a configuration of a conventional canister and its peripheral portion.

[Explanation of symbols]

 1 Internal Combustion Engine 2 Intake Pipe 4 Throttle Valve Opening Sensor 5 Electronic Control Unit (ECU) 6 Fuel Injection Valve 8 Fuel Tank 10 Intake Pipe Absolute Pressure Sensor 15 Canister 16 Purge Control Valve 17 Purge Pipe 18 Hot Wire Flowmeter 19 Chamber 153 Bottom Part chamber

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[Procedure amendment]

[Submission date] August 20, 1991

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0027

[Correction method] Change

[Correction content]

FIG. 5 is a diagram showing the relationship between the vapor concentration β in the air-fuel mixture and the rate of change in the flow rate display. In the figure, the solid line corresponds to the output value QH of the hot-wire flow meter 22, and the broken line is the PC flow rate. (P
Corresponds to CQ1). Here, the flow rate display change rate is the ratio of the flow rate display value when β> 0% to the flow rate display value when β = 0% (that is, the above QH value or PCQ1 value) when the purge flow rate TQ is constant. Is a parameter indicating. That is, the flow rate display change rate represents the ratio of the QH value or PCQ1 value to the purge flow rate TQ (QH / TQ or PCQ1 / TQ), for example β = 0%.
In the case of, as shown in FIG. 6A, PCQ1 = QH =
Although TQ = 1 [l / min], when β = 100%, PCQ1 = 1.69 [l / min], QH for TQ = 1 [l / min] as shown in FIG. = 4.45 [l / m
in]. Therefore, using the relationship of FIG. 5, the PC flow rate P
The vapor concentration β 1 , the vapor flow rate VQ, and the purge flow rate TQ can be calculated based on the CQ1 and the hot wire type flow meter output value QH. More specifically, since the relationship is as shown in FIG. 6 (c), the vapor concentration β , the vapor flow rate V Q, and the purge flow rate TQ from the QH value and the PCQ1 value (11, 2l on the line of constant β in the figure, ... is V Q der those display and is,
The purge flow rate TQ can be calculated as VQ / β ).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroaki Mihara 1-4-1, Chuo, Wako-shi, Saitama Honda R & D Co., Ltd. (72) Inventor Teruo Wakashiro 1-4-1, Wako-shi, Saitama No. Incorporated in Honda R & D Co., Ltd. (72) Inventor Takashi Kiyomiya 1-4-1 Chuo, Wako, Saitama Incorporated in Honda R & D Co., Ltd.

Claims (2)

[Claims] 1. An air-fuel mixture of an internal combustion engine having a canister for adsorbing fuel vapor generated from a fuel tank and a purge passage for supplying an air-fuel mixture containing the fuel vapor adsorbed in the canister to an engine intake system. In a fuel vapor detection device for detecting a fuel vapor component therein, a purge flow rate calculating means for calculating a flow rate of an air-fuel mixture flowing in the purge passage, a mass flow meter for measuring a flow rate of the air-fuel mixture flowing in the purge passage, Fuel vapor detection means for detecting a fuel vapor component based on the calculated purge flow rate of the purge flow rate calculation means and the output value of the mass flow meter is provided, and the purge passage has a chamber in the middle thereof, and the mass flow meter Is provided in the chamber, and the fuel vapor detection device for an internal combustion engine is characterized in that: 2. An internal combustion engine having a closed bottom type canister for adsorbing fuel vapor generated from a fuel tank and a purge passage for supplying an air-fuel mixture containing the fuel vapor adsorbed in the canister to an engine intake system. A fuel vapor detection device for detecting a fuel vapor component in the air-fuel mixture, a purge flow rate calculating means for calculating a flow rate of the air-fuel mixture flowing through the purge passage, and a mass flow rate for measuring a flow rate of the air-fuel mixture flowing through the purge passage. And a fuel vapor detection means for detecting a fuel vapor component based on the purge flow rate calculation value of the purge flow rate calculation means and the output value of the mass flow rate meter, wherein the mass flow rate meter is in the bottom chamber of the canister. And a fuel vapor detection device for an internal combustion engine.