JPH0686850B2 - 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.

[Prior Art] Conventionally, a fuel vapor emission suppression device has been widely used which prevents the fuel vapor generated from the fuel in the fuel tank from being released into the atmosphere. 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, the purge flow rate of the fuel vapor is controlled during the period from the start of the engine start immediately after refueling until the vehicle speed reaches a predetermined value, and during the period that continues from that point until the vehicle speed reaches a predetermined value. Applicants have proposed a purge flow controller to reduce.

[Problems to be solved by the invention]

However, in the above device, for example, when the vehicle speed stops once after the vehicle speed reaches the predetermined value, or until the vehicle stops, the fuel vapor is not purged.
Even when the vehicle enters the traveling range such as low speed and low load, the elapsed time from the time when the vehicle speed reaches the predetermined value is kept. Therefore, when the vehicle enters the travel range where the fuel vapor is purged after the predetermined time has elapsed, the above-described device cannot reduce the purge flow rate, and a large amount of fuel vapor rapidly flows into the engine. There was a problem to do.

The present invention has been made in view of the above problems, and provides a fuel vapor purge flow rate control device that reliably prevents a large amount of fuel vapor from flowing into the engine during the first engine operation after refueling. With the goal.

[Means for solving problems]

To achieve the above object, in the present invention, as shown in FIG. 1, a device for controlling a purge flow rate of fuel vapor purged from a fuel vapor emission restraining device to an intake system of an internal combustion engine, comprising a fuel tank A refueling operation detecting means (A) for detecting refueling operation to the engine, which outputs a refueling operation detection signal when the refueling operation is detected, and a start detecting means (B) for detecting the start of the engine. , A device for outputting a start detection signal when the start is detected, a vehicle speed detecting means (C) for detecting a vehicle speed of a vehicle on which the engine is mounted, the fuel vapor discharge restraining device and an intake system of the engine. And a purge flow rate adjusting means (E) for adjusting the purge flow rate of the fuel vapor.
Then, the first engine start after the refueling operation is determined by the refueling operation detection signal and the start detection signal, and the vehicle speed detected by the vehicle speed detecting means (C) has exceeded the predetermined vehicle speed since the first start. Until the accumulated time reaches the specified time,
There is provided a fuel vapor purge flow rate control device comprising a control means (D) for controlling the purge flow rate adjusting means (E) so as to reduce the fuel vapor purge flow rate.

[Work]

According to the fuel vapor purge flow rate control device of the present invention, the control means D is the first engine start after the refueling operation based on the detection signals output from the refueling operation detection means A, the start detection means B and the vehicle speed detection means C. From the time, the purge flow rate adjusting means E is controlled so as to reduce the purge flow rate of the fuel vapor until the integrated time of the time when the vehicle speed detected by the vehicle speed detecting means C exceeds the predetermined vehicle speed reaches the predetermined time.

〔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, reference numeral 1 is an engine, and an intake passage 2 of the engine 1 has a throttle valve 3 and an exhaust passage 4
An oxygen concentration sensor (O ₂ sensor) 5 is provided in each. The oxygen concentration signal output by the O ₂ sensor 5 is supplied to the A / D converter 101 of the control circuit 10 corresponding to the control means D in FIG.

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 C 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.

11 is a fuel tank, the cap 11b of the inlet 11a,
A cap switch 12 corresponding to the refueling operation detecting means A in FIG. 1 is provided. This cap switch 12
Is for detecting the attachment / detachment of the cap 11b, that is, the refueling operation, and is turned on when the cap 11b is removed from the inlet 11a, and the battery voltage of the battery 20 is used as the refueling operation detection signal to input / output interface 102 of the control circuit 10. Supply to. At the same time, when the cap switch 12 is turned on, the control circuit 10 is supplied with power, and the program of the purge flow rate control routine described later runs.

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 biased in the right direction in the figure by the spring force of the spring 15c, so that the valve body 15e is set at the outlet port 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, a throttle 17a is provided in the bypass passage 16c, 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 equal to that of the diaphragm 17b.
It is preferable to set the ratio smaller than that, and in the present embodiment, their ratio is set to approximately 1: 2. The VSV 15, the bypass passage 16 and the throttle 17 correspond to the purge flow rate adjusting means E 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.

Reference numeral 21 is a starter switch, which corresponds to the start detecting means B in FIG. When the starter switch 21 is closed, the battery voltage of the battery 20 is taken into the control circuit 10 via the input / output interface 102 as a start detection signal.

The control circuit 10 is configured as, for example, a microcomputer, and has the A / D converter 101 and the input / output interface 102 described above.
In addition, 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 closed, 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 closed, 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, referring to the flowchart shown in FIG. 3, the control circuit
The operation of 10 will be described.

FIG. 3 is a flow chart showing a purge flow rate control routine, which is 500 in this embodiment.
Runs every millisecond. In addition, this program is, of course, not only when the ignition key (not shown) is on,
Even if it is off, it will run when the cap switch 12 (Fig. 2) is on.

First, the control procedure during the refueling operation will be described.
In this case, since the cap 11b of the fuel tank 11 is removed from the inlet 11a, the result of the determination in step 301 as to whether or not the cap switch 12 is on is affirmative (YES), and the routine proceeds to step 302. In step 302, the refueling flag RFF is set to "1" to indicate that refueling is in progress. The refueling flag RFF is stored in the backup RAM 106 in order to retain the information even when the ignition switch (not shown) is turned off. Next, at step 303, the count value CNT of an internal counter (not shown) in the CPU 103 is cleared to "0", and the routine proceeds to step 304. The count value CNT is also backed up in RAM 106.
Stored in.

In step 304, it is judged whether or not the starter switch 21 is on. In this case, since the starter switch is off, the judgment result is negative (NO), and the routine proceeds to step 314. Then, in step 314, it is determined whether or not a start flag ESF described later is "1". As will be described later, the start flag ESF is set to "0" at the previous engine operation, so the determination result of step 314 is negative (NO), and the process proceeds to step 312, the details of which will be described later in VSV15. The valve opening control of is executed.

Next, a control procedure when the refueling operation is completed will be described. In this case, the cap 11b is attached to the inlet 11a, so the cap switch 12 is turned off. Then, when the cap switch 12 is turned off, this program is stopped, but at the same time, the control circuit 10 is also turned off, so that the valve opening control of the VSV 15 is eventually executed. Then, when the ignition switch is turned on, this program runs again, but in this case, since the determination result of step 301 is negative (NO), the routine proceeds to step 304, and the determination result of step 304 is also negative (NO). Step 314
Since the determination result of step 314 is also negative (NO), the process proceeds to step 312, and the valve opening control of the VSV 15 is executed.

Next, the control procedure at the first engine start after refueling will be described. In this case, the determination result of step 301 is negative (NO), so the routine proceeds to step 304, where it is determined whether or not the starter switch 21 is on. In this case, the starter switch is on because the engine is starting. Therefore, the determination result of step 304 is affirmative (YES), the process proceeds to step 305, the start flag ESF is set to "1" to indicate that the engine is being started, and step 3
Go to 06. The start flag ESF is also stored in the backup RAM 106.

At step 306, it is judged if the refueling flag RFF is "1". In this case, since the refueling flag RFF is set to "1" in step 302, step 306
The determination result of is affirmative (YES), and proceeds to step 307.

In step 307, 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 313, 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 15c, and the valve body 15e closes the fuel vapor outlet port 15g.

On the other hand, if the determination result of step 307 is negative (NO), that is, if the actual vehicle speed SPD exceeds the set vehicle speed SPDset, the process proceeds to step 308, the count value CNT is incremented by “1”, and the process proceeds to step 309.

In step 309, the count value CNT is set to "36".
It is determined whether it is smaller than "0". In other words, since this program is executed every 500 milliseconds, it is determined whether the cumulative time of the time when the actual vehicle speed SPD exceeds the set vehicle speed SPDset from the engine start time has exceeded the set time of 3 minutes. Will be done. The set value, that is, the set time is appropriately selected according to the engine, and the set time is preferably about 2 to 5 minutes. If the determination result of step 309 is affirmative (YES), that is, if the accumulated time of the time when the actual vehicle speed SPD exceeds the set vehicle speed SPDset from the engine start start time has not passed 3 minutes, the above step 31
Proceeding to 3, VSV15 valve closing control is executed. It should be noted that the starter switch 21 may be turned off before, for example, the cranking is completed before the integrated time exceeds 3 minutes.
In this case, the determination result in step 304 is negative (NO)
However, since the starting flag ESP is set to "1" in step 305, the determination result of step 314 becomes affirmative (YES), and the routine proceeds to step 306. Therefore, the valve closing control of the VSV 15 is continuously executed until the determination result of step 309 becomes negative (NO).

Next, a case will be described in which the integrated time exceeds 3 minutes which is the set time. In this case, the determination result of step 309 is negative (NO), and the refueling flag RFF is determined in step 310.
Is set to "0", then the start flag ESF is set to "0" in step 311, and the VSV15 valve opening control is performed in step 312, that is, the supply of the control signal from the control circuit 10 to the coil 15b of the VSV15 is stopped. Is executed.

Next, a control procedure at the time of starting the engine for the second time after refueling will be described. In this case, step 301, step 304 and step 305 are stepped on, and the process proceeds to step 306, where it is determined whether or not the refueling flag RFF is "1". In step 310, the refueling flag RFF is "0". Since it is set to, the determination result is negative (NO). Then, in step 311, the start flag ESF is set to "0".
Then, in step 312, the VSV15 valve opening control is executed. In other words, the VSV15 valve closing control is not executed during the second and subsequent engine operations after refueling.

In the present embodiment, the cap switch attached to the cap of the fuel tank is used as the refueling operation detecting means, but the present invention is not limited to this, and the switch is attached to, for example, the portion where the lid of the cap is opened or the lid opener, The switch may be used as the refueling operation detecting means.

〔The invention's effect〕

As described above, according to the fuel vapor purge flow rate control device of the present invention, from the first engine operation after refueling,
Until the accumulated time of the time when the vehicle speed exceeds the set vehicle speed at which the fuel vapor is reliably purged reaches a predetermined time,
Since the purge flow rate is reduced, it is possible to reliably prevent a large amount of fuel vapor from flowing into the engine during the first engine operation after refueling.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is a schematic configuration diagram of an internal combustion engine and its peripheral devices equipped with an embodiment of the present invention device, and FIG. 3 is a flowchart showing a purge flow rate control routine, And FIG. 4 is a purge characteristic diagram of the charcoal canister. 1 ... Internal combustion engine, 7 ... Crank angle sensor, 9 ... Vehicle speed sensor, 10 ... Control circuit, 11 ... Fuel tank, 12 ... Cap switch, 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, 21 …… starter switch.

Claims (2)

[Claims] 1. A device for controlling a purge flow rate of a fuel vapor purged from a fuel vapor discharge restraining device to an intake system of an internal combustion engine, the device being a fueling operation detecting means for detecting a fueling operation to a fuel tank, A unit that outputs a refueling operation detection signal when the refueling operation is detected, a start detection unit that detects the start of the engine, and a start detection signal that outputs the start detection signal when the start is detected, and the engine is mounted. Vehicle speed detecting means for detecting the vehicle speed of the vehicle, purge flow rate adjusting means for adjusting the purge flow rate of the fuel vapor, which is provided between the fuel vapor discharge restraining device and the intake system of the engine, and the refueling operation detection signal and The start detection signal determines the first engine start after refueling operation, and from the first start,
Control means for controlling the purge flow rate adjusting means so as to reduce the purge flow rate of the fuel vapor until the accumulated time of the vehicle speed detected by the vehicle speed detecting means exceeds the predetermined vehicle speed reaches a predetermined time; 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.