JPH0466761A - Canister purge control device - Google Patents

Abstract

PURPOSE:To reduce the operating sound of a valve body or a noise by a rattling sound of a purge air by providing a linear electromagnetic valve as a valve device provided on the way of a purge passage, and controlling the linear electromagnetic valve almost proportionally according to the input current from a control device which feedback-controls the air-fuel ratio of the mixture gas. CONSTITUTION:To a suction maniford 4, a purge port 7 is provided neighboring the downstream of a throttle valve 3, and one end of a purge passage 8 is connected to the purge port 7. At the upper side of a fuel tank 15, a canister 9 is connected through a vapor passage 14 to pass a fuel vapor, and a linear electromagnetic valve 10 is set at one side of the case 9a of the canister 9. The other side connecting port 27 of the linear electromagnetic valve 10 is connected to the purge port 7 through the purge passage 8. An input current (driving current) to the coil of the linear electromagnetic valve 10 is controlled by a control device 18 under the condition the air-fuel ratio of the mixture gas fed to an engine 1 is feedback-controlled, and the opening of the valve body is controlled almost proportionally to the input current.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention adsorbs fuel vapor from a fuel tank of an automobile or the like into a canister, and causes the vapor to be sucked into the combustion chamber of the engine together with the intake air of the engine. This invention relates to a canister purge control device.

[Prior art] Conventional canister purge control devices include, for example,
There is one disclosed in Publication No. 0-33316. The fuel vapor purge device of this publication is designed for use in engines equipped with an air-fuel ratio control device that feedback controls the air-fuel ratio of the air-fuel mixture supplied to the engine based on a signal generated by an exhaust gas sensor that detects the concentration of exhaust components in exhaust gas. a fuel vapor purge device for the purpose of operation, including a fuel vapor purge passage for guiding stored fuel vapor to an engine intake system, a valve device provided in the middle of the fuel vapor purge passage, and when the control device is in operation. and a control device for opening the valve device.

[Problems to be Solved by the Invention] However, the valve device in the fuel vapor purge device closes the purge passage when it is not energized and opens the passage when it is energized, and the on/off of the energization is controlled by the duty ratio. It was a type of duty solenoid valve.

With such a duty solenoid valve, every time the valve body opens and closes, for example, every time the duty ratio is controlled at 10 to 20 Hz, an operating sound (valve body collision sound) is generated and the flow of purge air is interrupted. An accompanying sound (so-called popping sound) is generated and the noise is loud.

Furthermore, since purge air containing fuel vapor flows intermittently into the intake passage of the engine, there is a problem in that the air-fuel ratio (A/F) varies depending on whether or not purge is performed.

Furthermore, since the amount of fuel vapor contained in the purge air is not constant, this also leads to variations in the air-fuel ratio.

Furthermore, since the purge is performed intermittently, the purge efficiency is impaired, and therefore a large canister with a large fuel vapor adsorption capacity is required.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and its purpose is to provide a canister that can reduce the noise and air-fuel ratio variations caused by the operation of a valve device, and can also reduce the size of the canister. An object of the present invention is to provide a purge control device.

[Means for Solving the Problems] A canister purge control device of the present invention that solves the above problems is based on a signal generated by an exhaust gas sensor that detects the concentration of exhaust components in exhaust scum, and controls the amount of air-fuel mixture supplied to the engine. A control device that performs feedback control of the air-fuel ratio, a canister that adsorbs fuel vapor from the fuel tank, a purge passage that purges the fuel vapor adsorbed in the canister to the engine intake passage, and a A linear solenoid valve that proportionally controls the purge amount of fuel vapor flowing through the passage according to the input current from the control device.

[Operation] According to the above means, the opening degree of the linear solenoid valve is adjusted in proportion to the input current from the control device under the condition that the air-fuel ratio of the air-fuel mixture supplied to the engine is feedback-controlled by the control device. The fuel vapor is purged depending on the opening degree.

As a result, fluctuations in the air-fuel ratio due to purged fuel vapor are compensated for by the feedback control, and the air-fuel ratio of the mixture supplied to the engine is maintained at approximately the target air-fuel ratio, regardless of changes in the amount of purged fuel vapor. Become so.

However, according to the linear solenoid valve installed as a valve device in the middle of the purge passage, unlike conventional duty solenoid valves, the opening degree of the valve body is continuously changed, and at the same time, the purge amount of the fuel vapor is changed. It takes place almost continuously, with continuous changes.

[Example] [First Example] A first example of the present invention will be described with reference to the drawings. 1st
The figure is a schematic configuration diagram showing a canister purge control device of this example.

In the figure, an engine 1 includes an air cleaner (not shown), an intake air amount sensor 2, a fuel injection valve 6, and an intake manifold 4.
A mixture of air and fuel is sucked into the combustion chamber 20 from an intake system including It is designed to be released into the atmosphere after 25 years.

A throttle valve 3 for controlling the flow rate of air supplied to the engine 1 is provided in the middle of the intake passage 5 of the intake system. Further, an intake valve 21 and an exhaust valve 22 are attached to the combustion chamber 20 so as to be able to reciprocate. An 02 sensor 19 is attached to the exhaust pipe 24 to detect the concentration of exhaust components in the exhaust residue.

A purge port 7 is provided in the intake manifold 4 downstream and adjacent to the throttle valve 3 .

Note that the purge port 7 is communicated with a purge passage 8, which will be described later.

Further, a canister 9 is connected to the upper part of the fuel tank 15 storing fuel via a steam passage 14 through which fuel vapor passes. The case 9a of the canister 9 is connected to the steam passage 14 on the negative side (upper surface in the drawing) and is provided with a linear solenoid valve IO, and has an atmosphere opening 9b formed on the other side (lower surface in the drawing). Activated carbon 11 is housed in the interior 12 of the case 9a, and a filter 13 is provided on the open port 9b side.

The structure of the linear solenoid valve 10 will be explained in detail later.
On the other hand, the access port 26 is connected to the inside 12 of the case 9. Further, the other connection port 27 of the solenoid valve 10 is communicated with the purge port 7 via a purge passage 8.

Each detection signal from the intake air amount sensor 2, 02 sensor 19, etc. is input to the control device 18. The control device 18 adjusts the air-fuel ratio of the air-fuel mixture supplied to the engine 1 to the stoichiometric air-fuel ratio based on a signal generated by the 02 sensor 19 or the like during low to medium load operation, excluding idle link operation and high load operation. A pulse signal (feedback signal) that operates the fuel injection valve 6 so that At the same time, the control device 18 outputs a drive current (input current) to the solenoid coil of the linear solenoid valve 10.

Next, the linear electromagnetic valve 10 to which input current is input from the control device 18 will be explained with reference to FIG. 2, which shows a cross-sectional view thereof. The linear solenoid valve 10 includes an electromagnetic drive unit 10
A and a flow control valve section 10B.

The electromagnetic drive section 10A is configured with a cylindrical coil 39, a core section 40 provided inside the coil 39, a plunger 31, and an output shaft 38 fixed to the plunger 31 as main elements. The coil 39 is housed within the coil case 30.

Further, the flow rate control valve part JOB includes a flow path 41 forming a part of the purge path 8 and a plurality of orifices 4 in the middle of the flow path 41.
2. The main element is a valve body 37 that changes the opening area of the orifice 42. The flow path 41 and orifice 42 are provided in a valve case 32 coupled to the coil case 30. The valve body 37 is provided on the same axis as the output shaft 38, and is normally urged in the valve closing direction by the return spring 36.

In the linear electromagnetic valve 10, when a predetermined input current is applied to the coil 39, the output shaft 38 strokes by an amount proportional to the input current. This mechanical output of the output shaft 38 moves the valve body 37 and changes the opening area of the orifice 42. This provides a controlled flow rate proportional to the input current.

An input current (driving current) to the coil 39 of the linear solenoid valve IO is input by the control device 18. Specifically, in the control device 18, the central processing unit (C
PU) outputs a pulse signal for duty control to a solenoid drive circuit that outputs the drive current (input current). At this time, by changing the on/off pulse width of the signal, the on/off time width of the voltage output from the solenoid drive circuit changes. Therefore, if the on-time width is increased, the average voltage output from the solenoid drive circuit becomes higher, and the input current flowing to the coil 39 becomes larger, so the opening degree of the valve body 37 of the linear solenoid valve 10 becomes larger. . Furthermore, if the on-time width is made smaller, the input current flowing through the coil 39 becomes smaller, contrary to the above, so that the opening degree of the valve body 37 of the linear electromagnetic valve 10 becomes smaller.

Therefore, by changing the time width between on and off of the pulse signal for duty control output from the CPU, the input current flowing to the coil 39 can be changed, and the opening degree of the valve body 37 can be controlled. . Note that the coil 3
The time period for energizing the circuit 9 can be switched at a fast speed of, for example, about 250 to 300 Hz.

In the canister purge control device equipped with the above-described linear electromagnetic valve lO, fuel vapor generated in the fuel tank 15 passes through the vapor passage 14 and is adsorbed by the activated carbon 11 in the canister 9.

The control device 18 is activated when the ignition key switch is turned on (starting the engine 1). Then, while the air-fuel ratio of the air-fuel mixture supplied to the engine l is being feedback-controlled by the control device 18, an input current is input to the coil 39 of the linear solenoid valve 10 by the control device 18, and the current is The opening degree of the valve body 37 is controlled approximately proportionally. Depending on this opening degree, the fuel vapor adsorbed on the activated carbon 11 is purged into the intake passage 5 due to the pressure difference between the intake pressure (negative pressure) of the intake manifold 4 and the atmospheric pressure of the canister 9. As a result, fluctuations in the air-fuel ratio due to purged fuel vapor are compensated for by the feedback control, and regardless of changes in the amount of fuel vapor purge, the engine l
The air-fuel ratio of the air-fuel mixture supplied to the engine is maintained approximately at the target air-fuel ratio.

According to the linear solenoid valve 10 provided as a valve device in the middle of the purge passage 8, unlike conventional duty solenoid valves, the opening degree of the valve body 37 is continuously changed, and at the same time, the purge of fuel vapor is The purge is performed almost continuously with continuous changes in the amount of purge. Therefore, the noise caused by the operating sound of the valve body 37 and the popping sound of the purge air is reduced compared to the conventional one.

In addition, since the purge air flows almost continuously into the intake passage 5 of the engine 1, the air-fuel ratio can be controlled accurately through feedback control, reducing variations in the air-fuel ratio and increasing purge efficiency, resulting in a small capacity and compact size. canister 9 can be adopted.

[Second Embodiment] Next, a second embodiment of the present invention will be described with reference to the drawings. Note that this example is a modification of the linear solenoid valve 10 in the first example, so only the solenoid valve will be described. In FIG. 3, which shows a cross-sectional view of the linear solenoid valve, the linear solenoid valve 50 includes an electromagnetic drive section 50A and a flow control valve section 50B.

The electromagnetic drive unit 50A includes a coil 59 wound around a cylindrical bobbin 53, fixed iron cores 60 and 61 provided on both end surfaces of the coil 59, and a coil cover 6 housing the coil 59.
2, a plunger 51 disposed within the bobbin 53, and an output shaft 58 fixed to the plunger 51 as main elements. The plunger 51 is supported by two holding springs 54 without sliding on the bobbin 53 and on the same axis. Note that the holding spring 54 is
As shown in the front view in the figure, a substantially spiral gap 54a is formed inside the circular plate spring material. Third
In the figure, the outer circumferential portion of the holding spring 54 corresponds to the fixed iron core 6.
They are attached to the cover member 66 or the fixed iron core 61 attached to the base plate 0 by caulking, respectively. Further, the inner peripheral portion of the holding spring 54 is sandwiched between the plunger 51 and the output shaft 58 connected thereto, or between the plunger 51 and the protruding shaft 65 connected thereto. Also, the protruding shaft 65 and the cover member 66
A return spring 56 is interposed between the screw 66a and the screw 66a.

The flow rate control valve section 50B is configured mainly of a flow path 67 forming a part of the purge passage 8, a valve seat 62 in the middle of the flow path 67, and a valve body 57 that opens and closes the valve seat 62. Channel 6
7 and the valve seat 62 are provided in a valve case 52 coupled to the fixed iron core 61. The valve body 57 is provided on the same axis as the output shaft 58, and is normally urged in the valve closing direction by the return spring 56.

In the linear solenoid valve 50, when a predetermined input current is applied to the coil 59, the output shaft 58 strokes by an amount proportional to the input current. This mechanical output of the output shaft 58 moves the valve body 57 and changes the distance between the valve body 57 and the valve seat 62. This provides a controlled flow rate proportional to the input current. Also, the plunger 51 is held by the holding spring 5.
4 allows the plunger 51 to stroke without sliding on the bobbin 53, allowing the plunger 51 to move smoothly without sliding resistance.

The canister purge control device equipped with the above-described linear solenoid valve 50 also provides the same effects as those of the first embodiment.

Note that the present invention is not limited to the above-mentioned embodiments, and modifications can be made without departing from the gist of the present invention.

[Effects of the Invention] According to the present invention, a linear solenoid valve is provided as a valve device disposed in the middle of a purge passage, and the linear solenoid valve is operated approximately according to an input current from a control device that feedback controls the air-fuel ratio of the air-fuel mixture. Since the control is carried out proportionally, the noise caused by the operating sound of the valve body and the popping sound of the purge air is reduced compared to conventional ones.

In addition, since purge air flows almost continuously into the engine's intake passage, the air-fuel ratio can be controlled accurately through feedback control, reducing variations in the air-fuel ratio, and increasing purge efficiency, so even small capacity It becomes possible to use a small canister.

[Brief explanation of drawings]

1 and 2 show a first embodiment of the present invention, in which FIG. 1 is a schematic configuration diagram of a canister purge control device, and FIG. 2 is a sectional view of a linear solenoid valve. 3.4 shows a second embodiment of the present invention, FIG. 3 is a sectional view of the linear solenoid valve, and FIG. 4 is a front view of the retaining spring. 1...Engine 8...Purge passage 9...Canister 10.50...Linear solenoid valve 18...Control device 19...02 Sensor (exhaust gas sensor)

Claims (1)

[Scope of Claims] A control device that feedback-controls the air-fuel ratio of a mixture supplied to an engine based on a signal generated by an exhaust gas sensor that detects the concentration of exhaust components in exhaust gas, and a control device that adsorbs fuel vapor from a fuel tank. a purge passage for purging the fuel vapor adsorbed in the canister to the intake passage of the engine; and a purge passage provided in the middle of the purge passage for controlling the purge amount of the fuel vapor flowing through the passage according to the input current from the control device. A canister purge control device equipped with a linear solenoid valve that proportionally controls the canister purge.