JP3147410B2 - Purge air control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a purge air control device, and more particularly, to a purge air control device, in which a canister is provided in the middle of a ventilation passage communicating an intake passage of an internal combustion engine and a fuel tank, and the ventilation between the canister and the intake passage. The present invention relates to a purge air control device provided with a purge valve in the middle of a road.

[0002]

2. Description of the Related Art An internal combustion engine mounted on a vehicle or the like is provided with a purge air control device to prevent the evaporative fuel, which is HC gas, generated in a fuel tank or the like from being released to the atmosphere when the engine is stopped. There is. In the purge air control device, a canister is provided in the middle of an air passage communicating the intake passage of the internal combustion engine and the fuel tank, and a purge valve is provided in the middle of an air passage between the canister and the intake passage.

This purge air control device closes a purge valve when the engine is stopped and causes the canister to temporarily adsorb and hold the vaporized fuel, and releases the purge valve during operation of the engine to introduce fresh air into the canister. The evaporated fuel is purged (separated) and supplied to the intake passage.

Further, as disclosed in Japanese Patent Application Laid-Open No. 63-85249, a purge flow rate control device for a fuel evaporative gas uses a feedback correction amount based on a deviation between an actual air-fuel ratio and a target air-fuel ratio in a feedback control range. Means for controlling the amount of fuel supplied to the engine, a canister containing an adsorbent for evaporating gas of the fuel, a purge passage communicating the canister with the intake passage, and a valve opened according to the control amount interposed in the purge passage. A purge valve for increasing the degree, a means for controlling a purge valve control amount in a feedback control range according to an operation state, a means for determining whether a feedback correction amount exceeds a predetermined control range, and a means for determining whether a feedback correction amount exceeds a predetermined control range. Further, there has been provided a means for reducing the purge valve control amount when the feedback correction amount exceeds the control range.

[0005]

In a conventional purge air control apparatus, there is a conventional purge air control apparatus that performs duty control of a vacuum switching valve (VSV) which is a purge valve. In this control method, for example, the duty ratio (purge flow rate) in which the engine speed and the load are set as the X and Y axes, respectively, is always constant from the initial stage of running to after the endurance running. That is, the purge flow rate was constant irrespective of the traveling distance of the car and the level of adsorption of HC gas to the canister.

[0006] However, the level of HC gas adsorbed on the canister varies with changes in the mileage of the vehicle and operating conditions.

As a result, HC exceeding the performance of the canister
If gas is released from the fuel tank, HC
There is a fear that gas may leak, which is disadvantageous in practical use. In such a case, it is necessary to maintain the performance of the canister by increasing the purge flow rate. However, there is no conventional purge air control apparatus that changes the purge flow rate in response to such conditions.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is to provide a canister in the middle of an air passage communicating an intake passage of an internal combustion engine and a fuel tank. In a purge air control device having a purge valve interposed in the middle of the ventilation path between passages, an operation state sensor for detecting an operation state of the internal combustion engine is provided, and an HC gas concentration sensor for detecting a concentration of HC gas is provided. A gas concentration sensor is disposed on the fresh air passage side with the HC gas adsorbent interposed from the ventilation path side communicating with the fuel tank of the canister, and when an input signal from the HC gas concentration sensor becomes a predetermined value or more. And a controller for changing a duty ratio to increase a purge flow rate of the purge valve.

[0009]

According to the invention described above, when the internal combustion engine is operated, when the internal combustion engine is operated, the HC gas disposed on the fresh air passage side with the HC gas adsorbent interposed therebetween from the air passage side communicating with the fuel tank of the canister. A concentration sensor detects the concentration of HC gas in the canister, and an input signal is input from the HC gas concentration sensor to the control unit. When the input signal is equal to or higher than a set value, the duty ratio is changed to increase the purge flow rate. ing.

[0010]

Next, an embodiment of the present invention will be described in detail with reference to the drawings.

1 to 4 show an embodiment of the present invention. In FIG. 3, 2 is an internal combustion engine, 4 is an intake passage, and 6 is an exhaust passage. The intake passage 4 of the internal combustion engine 2
An air cleaner 8 is provided on the start end side, a throttle valve 10 is provided on an intermediate portion, and the end side is communicated with the combustion chamber 12. The exhaust passage 6, which communicates with the combustion chamber 12 at the start end, has the end open to the atmosphere.

A fuel injection valve 14 is provided in the intake passage 4 of the internal combustion engine 2 so as to be directed to the combustion chamber 12. The fuel injection valve 14 is connected to a fuel tank 18 by a fuel passage 16. The fuel in the fuel tank 18 is supplied to the fuel injection valve 14 through a fuel passage 16 by a fuel pump (not shown), and is supplied to the combustion chamber 12 by injection.

The fuel injection valve 14 is connected to a control unit 20. The control unit 20 includes an air flow meter 22 that detects an intake air amount, an opening sensor 24 that detects an opening of the throttle valve 10, and an engine speed as an operating state sensor that detects an operating state of the internal combustion engine 2. The igniter 26 is connected for detection. The igniter 26
Distributor 3 via ignition coil 28
Connected to 0. The control unit 20 controls these sensors 2
The driving of the fuel injection valve 14 is controlled by signals input from 2 to 26, and fuel is injected and supplied so that the air-fuel ratio required by the internal combustion engine 2 is obtained.

A purge air control device 32 for treating fuel vapor generated in the fuel tank 18 has one end communicating with the intake passage 4 downstream of the throttle valve 10 of the internal combustion engine 2 and the other end communicating with the fuel tank 18. Air passage 3
4, and a canister 36 is provided in the middle of the ventilation path 34. The air passage 34 includes a first air passage 34-1 communicating the fuel tank 18 and the canister 36, a second air passage 34-2 communicating the canister 36 and the intake passage 4,
Consists of A check valve 38 is provided in the middle of the first ventilation path 34-1. Second intake passage 34-
In the middle of 2, a purge valve 40 is provided.

Reference numeral 42 denotes a fresh air passage for introducing fresh air.

The purge air control device 32 closes the purge valve 40 when the engine is stopped, causes the canister 36 to once adsorb and hold the fuel vapor through the first ventilation path 34-1. Fresh air is introduced through the fresh air passage 42, and the evaporated fuel adsorbed and held by the fresh air is purged (separated) and supplied to the intake passage 4 through the second ventilation passage 34-2.

Further, an HC gas concentration sensor 44 for detecting the concentration of HC gas in the canister 36 is provided between the vent passage 34 communicating with the fuel tank 18 of the canister 36 with an adsorbent 48 for HC gas to be described later interposed therebetween. It is arranged on the side of the fresh air passage 42 and connected to the control unit 20. When the input signal from the HC gas concentration sensor 44 exceeds a predetermined value, the duty ratio is changed to increase the purge flow rate of the purge valve 40.

More specifically, an HC gas concentration sensor 44 is provided at a substantially intermediate portion of the hollow portion 36a of the canister 36. That is, as shown in FIG. 4, the hollow portion 36a of the canister 36 is partitioned by the adsorbent holding member 46, and five first to fifth hollow portions 36a-1 are formed from the side of the air passage 34 communicating with the fuel tank 18. , 36a-2, 36a-3, 36a
-4, 36a-5 are formed, and the HC gas adsorbent 48 is accommodated in the second hollow portion 36a-2 and the fourth hollow portion 36a-4. At this time, the HC gas concentration sensor 44 is connected to the second hollow portion 36 from the side of the ventilation passage 34 communicating with the fuel tank 18.
The fresh air passage 42 sandwiching the HC gas adsorbent 48 in the a-2
The third hollow portion 36a-3 is located on the side. Then, the HC gas concentration sensor 44 and the purge valve 40 are connected to the control unit 20.

The control unit 20 includes an HC gas concentration sensor 4
When the input signal is less than the set value, the purge valve 40 is controlled by the duty ratio from the basic map Pmap using the engine speed (Ne) and the load as the X and Y axes, as shown in FIG. If the input signal from the HC gas concentration sensor 44 is equal to or greater than the set value, the total duty ratio Tprg (Pmap × Fpr) obtained by multiplying the basic map Pmap and the multiplier Fprg for detecting the HC gas concentration is used.
g) controls the purge valve 40.

Next, the operation will be described.

As shown in FIG. 1, when the internal combustion engine 2 is stopped (1
02), the purge valve is turned off (104), and the second ventilation path 34-2 is closed. Thereby, the fuel tank 1
Evaporated fuel No. 8 is adsorbed and held in the canister 36 by the first ventilation path 34-2.

When the internal combustion engine 2 is driven (106), the concentration of HC gas in the canister 36 is measured by the HC gas concentration sensor 4.
4 and the input signal from the HC gas concentration sensor 44 is input to the control unit 20.

At this time, the concentration of HC gas is low (10
8) That is, when the input signal to the control unit 20 is less than the set value, the duty ratio of the purge valve is reduced (11).
0), that is, the purge valve 40 is operated according to the duty ratio from the basic map Pmap to reduce the purge flow rate (112).

Further, the concentration of HC gas is high (114),
That is, when the input signal to the control unit 20 is equal to or greater than the set value, the duty ratio of the purge valve is increased (116).
That is, the duty ratio from the basic map Pmap and H
The total duty ratio Tprg (Pmap × Fprg) is calculated from the multiplier Fprg when the concentration of C gas is detected, and the purge valve 40 is operated according to the total duty ratio Tprg to increase the purge flow rate.

The control unit 20 includes an HC gas concentration sensor 4
When the engine is turned on again after the engine is turned off, the HC gas concentration sensor 44 operates. If the HC gas concentration is less than the set value, the normal duty control is performed. In the above case, the duty control is performed by the duty ratio from the basic map Pmap and the total duty ratio Tprg calculated from the multiplier Fprg at the time of detecting the concentration of the HC gas.

Thus, when HC gas is adsorbed to the canister 36 more than necessary, the purge flow rate can be increased, the HC gas can be desorbed from the canister 36, and the performance of the canister 36 can be restored at an early stage. It is advantageous.

Further, by restoring the performance of the canister 36 at an early stage, the release of HC gas into the atmosphere can be prevented, which contributes to the reduction of air pollution.

Further, since the HC gas concentration sensor 44 is provided in the canister 36, and the HC gas concentration sensor 44 and the purge valve 40 are connected to the control unit 20, the structure of the purge air control device can be simplified.

Further, the HC gas concentration sensor 44 is connected to the fresh air passage 42 from the side of the ventilation passage 34 communicating with the fuel tank 18 of the canister 36 with the HC gas adsorbent 48 interposed therebetween.
Since it is disposed on the side, the following operation and effect can be obtained. (1) It is possible to reliably detect that HC gas exceeding the performance of the canister passes through the canister and is released to the atmosphere. (2) The state of adsorbing and holding the evaporated fuel in the canister can be accurately grasped, and accurate control can be performed. (3) It is not necessary to unnecessarily increase the size of the canister to secure a margin, and the canister can be reduced in size. (4) The detection is not affected by the temporary fluctuation of the gas concentration due to the release of the fuel vapor from the fuel tank, so that accurate detection is possible. Moreover, by attaching the HC gas concentration sensor 44 to a substantially intermediate portion of the canister 36, that is, to the third hollow portion 36a-3, the concentration of the HC gas in the canister 36 can be accurately measured, and the HC gas is adsorbed more than necessary. After that, while the HC gas concentration sensor 44 detects,
The C gas can be adsorbed to the canister 36 on the fresh air passage 42 side.

It should be noted that the present invention is not limited to the above-described embodiment, and various application modifications are possible.

For example, the HC gas concentration sensor 44 is provided at a substantially intermediate portion of the canister 36. However, as shown in FIG. 5, the HC gas concentration sensor 44 is provided below the canister 36 on the side of the fresh air passage 42. It is also possible to use. That is, as shown in FIG. 5, the hollow portion 36a of the canister 36 is partitioned by the adsorbent holder 46, and three first to third hollow portions 36 are formed from the side of the ventilation path communicating with the fuel tank.
a-1, 36a-2, and 36a-3 are formed, and the HC gas adsorbent 48 is accommodated in the second hollow portion 36a-2. At this time, the HC gas concentration sensor 44 is connected to the third hollow portion 36a-, which is on the fresh air passage side with respect to the HC gas adsorbent 48 in the second hollow portion 36a-2 from the side of the air passage communicating with the fuel tank. 3 is provided.

Further, in the present invention, an HC gas concentration sensor is provided in the canister of the purge air control device in order to prevent the HC gas in the canister from leaking into the atmosphere. Combined with a controller that performs feedback control
Highly accurate air-fuel ratio control can be performed while preventing outflow of C gas.

Further, in the present invention, the total duty ratio is calculated by using the basic map and the multiplier for detecting the concentration of HC gas. However, a total duty ratio map is created separately from the basic map. It is also possible to calculate the total duty ratio from.

[0034]

As described above, according to the present invention, the canister is provided in the middle of the air passage communicating the intake passage of the internal combustion engine and the fuel tank, and the purge valve is provided in the middle of the air passage between the canister and the intake passage. In the purge air control device interposed, an operating state sensor for detecting an operating state of the internal combustion engine is provided, an HC gas concentration sensor for detecting the concentration of HC gas is provided, and the HC gas concentration sensor communicates with a fuel tank of the canister. A control in which the duty ratio is changed to increase the purge flow rate of the purge valve when the input signal from the HC gas concentration sensor exceeds a predetermined value when the input signal from the HC gas concentration sensor exceeds a predetermined value. The canister can restore the performance of the canister at an early stage and prevent the HC gas from leaking into the atmosphere from the canister. Is an interest. Further, since the HC gas concentration sensor is disposed on the side of the fresh air passage with the HC gas adsorbent interposed therebetween from the side of the air passage communicating with the fuel tank of the canister, the following effects are also obtained. (1) It is possible to reliably detect that HC gas exceeding the performance of the canister passes through the canister and is released to the atmosphere. (2) The state of adsorbing and holding the evaporated fuel in the canister can be accurately grasped, and accurate control can be performed. (3) It is not necessary to unnecessarily increase the size of the canister to secure a margin, and the canister can be reduced in size. (4) Accurate detection is possible because there is no effect of temporary fluctuations in gas concentration due to the release of fuel vapor from the fuel tank.

[Brief description of the drawings]

FIG. 1 is a flowchart of a purge air control device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a map of basic values based on engine speed and load.

FIG. 3 is a schematic configuration diagram of a purge air control device.

FIG. 4 is an enlarged view of a main part of the purge air control device.

FIG. 5 is an enlarged view of a main part of a purge air control device showing another embodiment.

[Explanation of symbols]

 Reference Signs List 2 internal combustion engine 4 intake passage 8 air cleaner 10 throttle valve 14 fuel injection valve 18 fuel tank 20 control unit 22 air flow meter 24 opening sensor 32 purge air control device 34 air passage 36 canister 38 check valve 40 purge valve 42 fresh air passage 44 HC gas concentration Sensor

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-64-3258 (JP, A) JP-A-63-188695 (JP, A) JP-A-2-42167 (JP, A) 128959 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) F02M 25/08 301 F02M 25/08 311

Claims (1)

(57) [Claims] 1. A purge air control device in which a canister is interposed in an air passage connecting an intake passage of an internal combustion engine and a fuel tank, and a purge valve is interposed in the air passage between the canister and the intake passage. in the provided HC gas concentration sensor for detecting the concentration of HC gas is provided with the operating condition sensor for detecting the operating state of the internal combustion engine, the HC gas concentration sensor of the canister
Adsorption of HC gas from the ventilation path side communicating with the fuel tank
Is disposed on the side of the fresh air passage with the HC gas concentration sensor
Purge air control device, characterized in that the input signal from the sub is provided with a control unit for changing the duty ratio in order to increase the purge flow rate of the purge valve when equal to or larger than a predetermined value.