JPH0686848B2 - Fuel vapor purge flow controller - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel vapor purge flow rate control device that controls the purge flow rate of fuel vapor that is purged from a fuel vapor emission suppression device to an intake system of an internal combustion engine.

[Conventional technology]

2. Description of the Related Art Conventionally, a fuel vapor emission suppression device that prevents the fuel vapor generated from the fuel in a fuel tank from being released into the atmosphere has been widely used. In this case, the fuel vapor is once adsorbed by the adsorbent of the fuel vapor emission suppression device and then purged into the intake system of the engine.However, during and immediately after refueling, a large amount of fuel vapor is removed from the fuel tank. Therefore, a large amount of fuel vapor is adsorbed on the adsorbent. When purging the fuel vapor adsorbed by the adsorbent, taking a charcoal canister as an example of a fuel vapor discharge suppression device, as shown in FIG. It is generally known that vapor leaves the adsorbent. Therefore, a large amount of fuel vapor is drawn into the engine when the vehicle is running immediately after refueling, and when the engine is under air-fuel ratio control, a fuel amount exceeding the control range may be supplied to the engine, which may cause emissions. Will deteriorate and drivability will also deteriorate.

Therefore, a cap switch that turns on or off when the cap of the tank is removed is attached to the fuel tank, the refueling operation is detected by turning the cap switch on and off, and the fuel is supplied for a predetermined time during the first engine operation after refueling. The present applicant has proposed a purge flow rate control device that reduces the purge flow rate of steam.

[Problems to be solved by the invention]

However, since the cap switch used as a means for detecting the refueling operation in the above device is a mechanical switch, it has a problem in durability and reliability. Therefore, the above-mentioned device has a problem in durability and reliability of the entire device.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a fuel vapor purge flow rate control device that is highly durable and reliable by detecting refueling operation without using a mechanical switch. And

[Means for solving problems]

In order to achieve the above object, in the present invention, as shown in FIG. 1, there is provided a device for controlling a purge flow rate of a fuel vapor purged from a fuel vapor emission suppression device to an intake system of an internal combustion engine, the device comprising: The air-fuel ratio detecting means A provided in the exhaust system of the vehicle, the vehicle speed detecting means B for detecting the vehicle speed of the vehicle in which the engine is mounted, the fuel vapor emission suppressing device and the intake system of the engine, When the purge flow rate adjusting means D for adjusting the purge flow rate of the fuel vapor and the air-fuel ratio detecting means A output a rich signal for the first predetermined time, the vehicle speed detected by the vehicle speed detecting means B becomes the predetermined vehicle speed. The purge flow rate of the fuel vapor, which comprises a control means C for controlling the purge flow rate adjusting means D so as to reduce the purge flow rate of the fuel vapor until the accumulated time of the exceeding times reaches the second predetermined time. Controller provided That.

[Work]

According to the fuel vapor purge flow rate control device of the present invention, when the air-fuel ratio detection means A outputs the rich signal for the first predetermined time, the control means C considers that the refueling operation is performed, Until the accumulated time of the time when the vehicle speed detected by the vehicle speed detecting means B exceeds the predetermined vehicle speed reaches the second predetermined time,
The purge flow rate adjusting means D is controlled so as to reduce the purge flow rate of the fuel vapor.

〔Example〕

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

FIG. 2 is a schematic configuration diagram of an internal combustion engine and its peripheral devices provided with an embodiment of the fuel vapor purge flow rate control device of the present invention. In the figure, 1 is an internal combustion engine (engine),
The intake passage 2 of the engine 1 is provided with a throttle valve 3 and the exhaust passage 4 is provided with an oxygen concentration sensor (O ₂ sensor) 5 corresponding to the air-fuel ratio detecting means A in FIG. The oxygen concentration signal output by the O ₂ sensor 5 is the A / D converter 1 of the control circuit 10 corresponding to the control means C in FIG.
Supplied to 01.

6 is a distributor, and distributor 6
Is provided with a crank angle sensor 7 whose axis generates a pulse signal every 30 ° CA. A signal from the crank angle sensor 7 for each 30 ° of crank angle is taken into the control circuit 10 through the input / output interface 102, and the rotation speed N
It becomes a 30 ° CA interrupt signal that calculates e.

8 is a transmission, and transmission 8
The vehicle speed sensor 9 provided on the speedometer cable from 1 corresponds to the vehicle speed detecting means B in FIG. The vehicle speed signal from the vehicle speed sensor 9 is the A / D in the control circuit 10.
It is sent to the converter 101.

13 is a charcoal canister as a fuel vapor emission suppression device. The charcoal canister 13 has a fuel vapor inlet port 13a, an atmosphere communication port 13b, and a fuel vapor outlet port 13c, and the inside thereof is filled with activated carbon 13d as an adsorbent. The fuel vapor introduction port 13a communicates with the upper portion of the fuel tank 11 via the fuel vapor passage 14a.

15 is a solenoid valve (VSV) 15 for purge control. The VSV 15 is a normally open solenoid valve, and is composed of a casing 15a, a coil 15b, a spring 15c, a plunger portion 15d, and a valve body 15e connected to the plunger portion 15d. A vapor inlet 15f and a fuel vapor outlet 15g are provided. When the coil 15b is not excited, the plunger portion 15d is urged to the right in the figure by the spring force of the spring 1c, so that the valve body 15e has the outlet 15g.
Open up. On the other hand, when the coil 15b is excited by the control signal supplied from the control circuit 10, the plunger portion 15d
Is attracted by the magnetic force generated by the coil 15b against the spring force of the spring 15c, and the valve body 15e closes the outflow port 15g.

The inlet 15f of the VSV 15 communicates with the fuel vapor discharge port 13c of the charcoal canister 13 via the fuel vapor passage 14b,
The outlet 15g communicates with a fuel vapor inlet 18f of a purge control negative pressure control valve 18, which will be described later, via a fuel vapor passage 14c. Then, between the passage 14b and the passage 14c, a bypass passage 16 that connects them is provided, and further, the throttle 17a is provided in the bypass passage 16, and the bypass passage 16 and the inflow port 15f of the fuel vapor passage 14b are provided. The diaphragms 17b are provided between them. The aperture area of the diaphragm 17a is preferably set smaller than that of the diaphragm 17b, and in the present embodiment, their ratio is set to approximately 1: 2.
The VSV 15, the bypass valve 16 and the throttle 17 correspond to the purge flow rate adjusting means D in FIG.

The purge control negative pressure control valve (VCV) 18 includes a casing 18a, a spring 18b, a diaphragm 18c, and a valve element 18d connected to the diaphragm 18c. The casing 15a includes a negative pressure inlet port 18e. A fuel vapor inlet port 18f and a fuel vapor outlet port 18g are provided. Inside the casing 15a, a spring 18b is provided by a diaphragm 18c.
18h for housing the valve body chamber 18i for housing the valve body 18d
It is divided into and. The spring 18c constantly urges the diaphragm 18c by its spring force in a direction in which the volume of the spring chamber 18h is increased, that is, in a direction in which the valve body 18d closes the inflow port 18f. However, when the atmospheric pressure in the spring chamber 18h becomes lower than the predetermined pressure, the diaphragm 18c is deformed in the direction of reducing the volume of the spring chamber 18h against the spring force of the spring 18b, and as a result, the valve body 18d is Open the inflow port 18f.

The negative pressure inlet port 18e of the VCV 18 communicates with the purge signal port 2a provided in the intake passage 2 via the negative pressure passage 19, and the outlet 18g passes through the fuel vapor passage 14d. It communicates with a purge port 2b provided in the intake passage 2. The purge signal port 2a is located in the vicinity of the throttle valve 3 and slightly upstream thereof, and the purge port
2b is located downstream of the purge signal port 2a.

The control circuit 10 is configured as, for example, a microcomputer, and includes the A / D converter 101 and the input / output interface 10 described above.
In addition to 2, a CPU 103, a ROM 104, a RAM 105, and a backup RAM 106 that retains information even after an ignition switch (not shown) is turned off are provided, and these are connected by a bus 107.

The operation of the above configuration will be described below.

When the slot valve 3 opens during the operation of the engine 1, negative pressure is applied to the purge signal port 2a provided in the intake passage 2, and the VCV 18 opens. As a result, the fuel vapor adsorbed on the activated carbon 13d filled in the charcoal canister 13 is purged by the atmosphere introduced from the atmosphere communication port 13b and separated from the activated carbon 13d.

The fuel vapor separated from the activated carbon 13d is supplied to the throttle 17a provided in the bypass passage 16 when the VSV 15 is open.
And the throttle port 17b provided in the fuel vapor passage 14b to reach the purge port 2b provided in the intake passage 2 and flow into the intake passage 2.

On the other hand, when the VSV 15 is open, the fuel vapor can only pass through the bypass passage 16. Moreover, in the present embodiment, the opening area of the throttle 17a provided in the bypass passage is equal to that of the throttle 17b provided in the fuel vapor passage 14b.
It is almost half of that. Therefore, when the VSV 15 is open, the amount of fuel vapor flowing into the intake passage 2 is much smaller than when the VSV 15 is open. That is, the purge flow rate of the fuel vapor is reduced. And
The opening / closing valve operation of the VSV 15 is controlled by the control circuit 10.

Next, the operation of the control circuit 10 will be described with reference to the flowcharts shown in FIGS.

FIG. 3 is a flow chart showing a refueling operation detection routine for detecting a refueling operation.
In this embodiment, it is executed every 4 milliseconds.

First, at step 301, it is judged if the O ₂ sensor 5 is outputting a rich signal indicating that the air-fuel ratio is rich. When the result of this determination is negative (NO), that is, when the air-fuel ratio is lean, the routine proceeds to step 310, where it is determined whether or not "1" is set in the refueling operation detection flag RDF described later. In this case, assuming that the flag RDF is set to "0" in the routine before the previous time, the determination result of step 310 is negative (NO), and step 311
And set the time elapsed flag TEF to be described later to “0”,
Further, in step 312, a first count value CI described later will be given.
To "0" and return.

Here, it is assumed that the lean state is changed to the rich state. Then, the determination result of step 301 is positive (YES).
Then, the process proceeds to step 302 and the time lapse flag TEF is set to "1".
It is determined whether or not is set.
In 311 the flag TEF is set to "0", so
The determination result of step 302 is negative (NO), and step 3
Go to 03.

In step 303, the first count value CI of the first internal counter (not shown) in the CPU 103 is incremented by "1", and the process proceeds to step 304.

In step 304, it is judged if the first count value CI is smaller than the first set value "250". In other words, since this program is executed every 4 milliseconds, it is determined whether or not the rich state has continued for 1 second from the time when the lean state changes to the rich state. In this case, the count value CI is "1", so step 30
The determination result of 4 is affirmative (YES), and the process returns. The first set value, that is, the first set time, is appropriately selected according to the engine, and is preferably 0.5 seconds to 2 seconds.

On the other hand, if the determination result of step 304 is negative (NO), that is, if the rich state continues for 1 second from the time when the lean state changes to the rich state, it is determined that the refueling operation has been performed, and step 305 In order to indicate that the refueling operation was detected, the refueling operation detection flag RDF
Is set to "1" and the process proceeds to step 306.

In step 306, it is determined whether or not the first count value CI is smaller than the second predetermined value "375". If the determination result is affirmative (YES), the process returns, and if negative (NO), That is, the rich state is the second set time, that is,
If you continue for 1.5 seconds, step 307
In step 3, set the time elapsed flag TEF to "1" and
At 08, the refueling operation detection flag RDF is set to "0".
Therefore, this flag RDF will be set for 0.5 seconds only, and this 0.5 seconds or 500 milliseconds corresponds to the time interval in which the purge flow rate control routine described later, whose flowchart is shown in FIG. 4, is executed. And step
At 309, the first count value CI is cleared to "0".

If the rich state continues for 1 second or longer but changes to the lean state in less than 1.5 seconds, the process proceeds from step 301 to step 310, but at step 305, the refueling operation detection flag RDF
Is set to "1", the determination result of step 310 is affirmative (YES), and when the process proceeds to step 303 and thereafter, the flag RDF remains set for 0.5 seconds. If the rich state continues for more than 1.5 seconds, the process proceeds from step 301 to step 302, but since the time elapsed flag TEF is set to "1" in step 307, the determination result of step 302 is affirmative (YES ) And return. Therefore, even if the rich state continues for more than 1.5 seconds, the refueling operation detection flag RDF is set for only 0.5 seconds.

FIG. 4 is a flowchart showing a purge flow rate control routine for controlling the purge flow rate, and this routine is executed every 500 milliseconds as described above in this embodiment.

First, in step 401, it is determined whether or not "1" is set in the above-described refueling operation detection flag RDF. If the determination result is affirmative (YES), the process proceeds to step 402,
In order to store that "1" is set in this flag RDF, that is, that the refueling operation is detected, "1" is set in the refueling operation storage flag RMF. The reason is that, in the next routine of this program, the refueling operation detection flag RDF is set to "0" as described above. When the refueling operation storage flag RMF is set to "1", the second count value CII of the second internal counter (not shown) in the CPU 103 is cleared to "0" in step 403, and the process proceeds to step 404.

On the other hand, when the result of the determination in step 401 is negative (NO), the process proceeds to step 410 and the refueling operation storage flag RMF is set to “1”.
It is determined whether or not is set. Then, if the determination result is affirmative (YES), the process proceeds to step 404, and if not (NO), the process proceeds to step 408, and VSV15 described later is executed.
Valve closing control is executed.

In step 404, it is determined whether or not the actual vehicle speed SPD detected by the vehicle speed sensor 9 is less than or equal to a set vehicle speed SPDset (for example, 15 km / h) at which fuel vapor is reliably purged, and the determination result is affirmative (YES. In the case of), that is, when the actual vehicle speed SPD does not exceed the set vehicle speed SPDset, the routine proceeds to step 409, where the valve closing control of the VSV 15 is executed. That is, the control signal is supplied from the input / output interface 102 of the control circuit 10 to the coil 15b of the VSV 15. As a result, coil 1
5b is excited, the plunger portion 15d is attracted against the spring force of the spring 15, and the valve body 15e closes the fuel vapor outlet port 15g.

On the other hand, when the determination result of the above step 404 is negative (NO), that is, when the actual vehicle speed SPD exceeds the set vehicle speed SPDset, the routine proceeds to step 405, where the second count value C II is incremented by “1”, and step 406 Proceed to.

At step 406, it is judged if the count value C II is smaller than the third set value “360”. In other words, since this program is executed every 500 milliseconds, the actual vehicle speed SPD from the start of engine start is the set vehicle speed SPDse.
It is determined whether or not the integrated time of the time exceeding t has passed the third set time of 3 minutes. The third set value, that is, the third set time is appropriately selected according to the engine, and the set time is preferably about 2 to 5 minutes. When the determination result of step 406 is affirmative (YES), that is, when the refueling operation detection flag RDF is set to "1", the accumulated time of the time when the actual vehicle speed SPD exceeds the set vehicle speed SPDset is 3 minutes. If not, step 40
Proceeding to 9, the valve closing control of VSV15 is executed.

On the other hand, when the determination result of the step 406 is negative (NO), that is, when the integrated time has passed 3 minutes, the process proceeds to step 407 to set the refueling operation storage flag RMF to “0”,
In step 408, the valve opening control of the VSV 15, that is, the supply of the control signal from the control circuit 10 to the coil 15b of the VSV 15 is stopped.

〔The invention's effect〕

As described above, according to the fuel vapor purge flow rate control device of the present invention, the lubrication operation is detected by the output of the O ₂ sensor without using the mechanical switch. The property is improved.

Further, when the engine is equipped with the air-fuel ratio control device, the O ₂ sensor provided in the air-fuel ratio control device can be used, so the cost is reduced by the mechanical switch.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of the present invention, FIG. 2 is a schematic configuration diagram of an internal combustion engine having an embodiment of the present invention device and its peripheral devices, and FIG. 3 is a flowchart showing a refueling operation detection routine, FIG. 4 is a flowchart showing a purge flow rate control routine, and FIG. 5 is a purge characteristic diagram of the charcoal canister. 1 ... Internal combustion engine, 5 ... O ₂ sensor, 9 ... Vehicle speed sensor, 10 ... Control circuit, 11 ... Fuel tank, 13 ... Charcoal canister, 14 ... Fuel vapor passage, 15 ... Solenoid valve ( VSV), 16 ... Bypass passage, 17 ... Throttle, 18 ... Negative pressure control valve (VCV), 19 ... Negative pressure passage.

Claims (2)

[Claims] 1. A device for controlling a purge flow rate of a fuel vapor purged from a fuel vapor emission restraining device to an intake system of an internal combustion engine, comprising: an air-fuel ratio detecting means provided in an exhaust system of the engine; A vehicle speed detecting means for detecting a vehicle speed of a vehicle mounted on the vehicle, a purge flow rate adjusting means for adjusting a purge flow rate of the fuel vapor, the purge flow rate adjusting means being provided between the fuel vapor emission restraining device and the intake system of the engine; When the detection means outputs the rich signal for the first predetermined time, the fuel is supplied until the accumulated time of the time when the vehicle speed detected by the vehicle speed detection means exceeds the predetermined vehicle speed reaches the second predetermined time. A control means for controlling the purge flow rate adjusting means so as to reduce the steam purge flow rate, and a fuel vapor purge flow rate control device comprising: 2. The fuel vapor purge flow rate control device according to claim 1, wherein the fuel vapor discharge restraining device is a charcoal canister.