JPH0719096A - Auxiliary flow rate control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To secure a control flow rate almost close to a required maximum flow rate even when operating voltage is changed. CONSTITUTION:A valve body 45 to open and close an orifice 44 is held in an almost intermediate position of the whole opening and closing operation strokes of the valve body 45 by relative pressure of front and rear plunger spring 38 and valve spring 48, and a valve opening electromagnetic coil 28 and a valve closing electromagnetic coil 29 to attract the valve body 45 in the opening and closing direction through a plunger 34, are housed in a solenoid casing 23 of a solenoid valve 21, and a control circuit is arranged to impress relatively antiphase control currents upon both electromagnetic coils 28 and 29 according to a temperature condition of an engine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an auxiliary flow rate control device for an internal combustion engine, which is provided, for example, in an intake system of the internal combustion engine to stabilize the idling speed.

[0002]

2. Description of the Related Art Conventionally, as an auxiliary flow rate control device for an automobile gasoline engine, for example, an idle speed control device as shown in FIG. 3 is known (Japanese Patent Laid-Open No. 57-938).
No. 0 publication). The outline will be described. A valve housing 5 of an electromagnetic valve 4 is provided in a bypass passage 3 that connects an upstream side and a downstream side of a throttle valve 2 provided in the middle of the intake passage 1.
And a solenoid casing 6 fixed to the side of the valve housing 5 is interposed. This solenoid casing 6 is provided with a connector 7 at its outer end, has one electromagnetic coil 8 inside, and is slidably accommodated in the electromagnetic coil 8 and has a drive rod 9 at its tip. And a plunger 10. On the other hand, in the valve housing 5, an air introduction chamber 11 that constitutes a part of the bypass passage 3, an annular valve seat 12 that defines the air introduction chamber 11, and one end slides in the guide portion 13. A valve body 15 connected to the tip of the drive rod 9 via a moving sliding shaft 14 is housed.

The valve body 15 is seated on and off the valve seat 12 to open and close the orifice 12a at the center of the valve seat 12, and is attached in the closing direction by a spring 17 mounted on the adjusting end wall 16 side on the other end side. It is energized. The spring force of the spring 17 is the spring force of the coil spring 18 on the proximal end side of the plunger 10 at the position where the valve surface 15a of the valve body 15 is seated on the seat surface 12b of the valve seat 12 and closes the orifice 12a. It is set to balance with.

Then, a control current (duty control current) is output from the controller (not shown) to the electromagnetic coil 8 to move the plunger 10 and the drive rod 9 in the axial direction to open and close the valve body 15, It is designed to control the total flow of auxiliary air.

That is, when the cold engine is started, the large magnetic force of the electromagnetic coil 8 attracts the plunger 10 to the right in the figure, and the valve body 15 opens the orifice 12a widely so that the auxiliary air flow rate is about 50 liters / min according to the duty. To about 800 liters / min. This increases the idling speed and warms up. After the completion of warming up, the amount of electricity to the electromagnetic coil 8 is reduced by duty control to control the opening amount of the valve body 15 to be small, and the auxiliary air amount is reduced to about 300 liters / min.

[0006]

However, in the above-described conventional idle speed control device, when the electromagnetic coil 8 is de-energized after the engine is stopped, the valve element 15 causes the spring force of both coil springs 17 and 18 to be increased. By valve seat 12
Is always seated on the seat surface 12b, that is, in the normally closed state. Therefore, the valve body 15 and the valve seat 12
There is a possibility that the valve mist 15 may stick to the valve seat 12 due to solidification of oil mist, carbon, or the like that has adhered to the valve seat 12.

Further, the valve body 15 is provided by one electromagnetic coil 8.
Since the opening operation control is performed by moving the entire stroke of the engine, when the voltage of the battery power source is lowered, for example, when the engine is started at a low temperature, the energization amount to the electromagnetic coil 8 is reduced to the plunger 10. Insufficient suction power. Therefore, the amount of opening of the orifice of the valve element 15 becomes smaller than the required amount of opening, and a sufficient amount of auxiliary air cannot be obtained. As a result, the startability of the engine may deteriorate.

Further, when the internal resistance of the electromagnetic coil 8 increases due to heat transfer from the engine or self-heating, the plunger 10
Insufficient suction force was obtained, and in this case too, the required air amount could not be obtained, and idling rotation became unstable.

The present invention has been made in view of such conventional problems, and an internal combustion engine capable of ensuring a control flow rate that is substantially close to the required maximum flow rate even when the operating voltage changes. It is an object of the present invention to provide an auxiliary flow rate control device.

[0010]

In order to solve the above problems, the present invention provides a bypass passage bypassing a gas passage of an internal combustion engine and an air flow rate flowing through an orifice of a valve seat in the bypass passage. In an auxiliary flow rate control device for an internal combustion engine equipped with a solenoid valve controlled via a valve body, the valve body is held at both ends in the operating direction of the valve body at an intermediate position of the opening and closing operation full stroke by opposing spring force. A pair of spring members are provided, and a pair of front and rear electromagnetic coils for opening and closing the valve element are housed in the solenoid casing of the electromagnetic valve, and the electromagnetic coils having opposite phases relative to each other are provided according to the state of the engine. It is characterized in that a control circuit for applying a control current is provided. Further, the valve body secures a predetermined opening degree in the orifice when the solenoid valve is not energized.

[0011]

In the above construction, the two electromagnetic coils attract the valve bodies in mutually opposite directions, so that both electromagnetic coils can share the total stroke amount of the valve body in the opening / closing direction. That is, since the valve body is held by the spring force of both spring members at a substantially intermediate position of the entire stroke from the predetermined opening position close to the fully closed position to the fully open position, one electromagnetic coil has an intermediate position of the valve body. The stroke from the position to the opening position close to the fully closed position can be shared, and the other electromagnetic coil can share the stroke from the intermediate position to the fully open position of the valve body. Therefore, even when the supply voltage to each electromagnetic coil is insufficient, the opening / closing stroke amount of the valve body by both electromagnetic coils can be secured, and the control flow rate close to the required maximum flow rate can be secured.

If the valve body secures a predetermined opening degree in the orifice when the solenoid valve is not energized,
When the electromagnetic coil is not energized when the engine is stopped, the valve body is kept in non-contact with the valve seat.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an idle speed control device according to the auxiliary flow rate control device of the present invention.
Is a bypass passage for bypassing the throttle valve 2 of the intake passage 1 which is a gas passage of the internal combustion engine, and 21 is a solenoid valve provided in the middle of the bypass passage 20.
1 is a proportional solenoid type, which is a valve housing 2
2 and a cylindrical solenoid casing 23 with a lid provided at one end of the valve housing 22 via a seal ring 24.

The solenoid casing 23 has an outer end closed by a cap 25, and a pair of bobbins 26 and 27 provided at axially inner front and rear positions and a pair of two electromagnetic valves for opening and closing. The coils 28 and 29 are wound. Further, a cylindrical plunger guide 30 is provided between the thin cylindrical portions of both bobbins 26, 27, and a pair of first core 31 and second core 32 are provided on the inner peripheral side of the cylindrical portions. Is provided. Also, both electromagnetic coils 28, 2
A ring-shaped yoke 33 is interposed between the nine. Further, on the inner circumference of the plunger guide 30, a plunger 34 having a tip end connected to a drive rod 35 is provided slidably in the axial direction. The drive rod 35 is slidably guided by a rod guide 36 held on the inner circumference of the second core 32 on the front side.

In the first and second cores 31 and 32, the inner peripheral surfaces 31a and 32a of the inner end portions facing each other are formed into conical tapered surfaces, while the plunger 34 has the inner end surfaces 31a and 32a. The outer peripheral surfaces 34a of the front and rear ends facing the
34b is formed on the conical taper surface having the same taper angle. Further, between the spring retainer 37 provided inside the first core 31 and the plunger 34, a plunger spring 38 for urging the plunger 34 in the right direction in the drawing is mounted. In the figure, 39 is an O-ring for sealing between the front end wall 23a of the solenoid casing 23 and the bobbin 27, and 40 is the solenoid casing 23.
It is an O-ring that seals between the rear end portion and the cap 25.

On the other hand, the valve housing 22 has an outer end portion closed by an adjusting end wall 41, and an air introduction chamber 42 having a substantially inverted U-shaped cross section which forms a part of the bypass passage 20 is formed inside. There is. Also, this air introduction chamber 4
2 is provided with an annular valve seat 43, and is seated on and off the valve seat 43.
A valve body 45 that opens and closes the central orifice 44 is provided.

The valve body 45 includes a columnar portion 45a and a large-diameter seating portion 45b which is provided at one end of the columnar portion 45a and which is seated on and separated from the valve seat 43. The column portion 4
The outer diameter of 5b is formed to be slightly smaller than the inner diameter of the orifice 44, and the outer diameter of the conical portion 45c at one end of the columnar portion 45b is gradually reduced toward the plunger 34 side. That is, the opening area of the orifice 44 in the columnar portion 45a is close to almost completely closed, and the opening area of the orifice 44 is gradually increased from one end edge of the conical portion 45c on the columnar portion 45a side to the other end edge so that the orifice 44 is near the other end edge. Is formed so as to be fully opened. Further, the valve body 45 has a central guide hole 4 of the adjusting end wall 41 on the seating portion 45b side.
1a is provided with a guide shaft 46 that is slidably guided, and a slide shaft 47 that is slidably guided in the valve guide 36 is provided at the front end portion. It is connected.

Further, the valve body 45 is provided with the adjusting end wall 4
While being urged in the direction of closing the orifice 44 by a valve spring 48 elastically mounted between
The plunger spring 38 causes the orifice 44
Is urged in the direction of opening. That is, the valve element 45 is
By the relative pressure between the spring force of the plunger spring 38 and the spring force of the valve spring 48 that opposes the spring force,
The intermediate position of all strokes in the opening / closing direction, that is, the vicinity of the boundary between the columnar portion 45a and the conical portion 45c is located at the inner peripheral edge of the orifice 44 as shown in the figure, and the orifice 44 is held at an opening position where it is slightly opened. Has been done. Therefore,
The valve seat 43 and the valve body 45 are not in contact with each other and are held at a substantially intermediate position of the entire opening / closing stroke of the valve body 45.

A control current (duty signal) of opposite phase is applied to the two electromagnetic coils 28 and 29 in the solenoid casing 23 from a control circuit (not shown). That is, when the control circuit increases the ON (H level) duty signal for the valve opening electromagnetic coil 28, the control circuit decreases the ON duty signal for the valve closing electromagnetic coil 29, and vice versa. O for coil 29
When the N duty signal is increased, the ON duty signal is decreased with respect to the valve closing electromagnetic coil 28.

Therefore, according to this embodiment, when the internal combustion engine is started at a low temperature, the valve opening electromagnetic coil 28 is moved from the control circuit.
The ON duty signal that is applied to the valve closing electromagnetic coil 29 is increased, and a sufficiently smaller ON duty signal than the valve opening electromagnetic coil 28 is applied to the valve closing electromagnetic coil 29. For this reason,
The plunger 34 is sucked rightward in the figure and pushes out the drive rod 35 in the same direction. As a result, the valve element 45 moves in the same direction from the intermediate position shown in the figure against the spring force of the valve spring 48, so that the opening area of the orifice 44 is increased by the conical portion 45c, and the flow rate of air flowing therethrough is increased. It will be maximum. As a result, the warm-up operation is promptly performed.

When the warm-up progresses and the engine temperature rises, the valve-opening electromagnetic coil 2 applied from the control circuit this time.
While the ON duty signal to 8 gradually decreases, the ON duty signal to the valve closing electromagnetic coil 29 relatively gradually increases. Therefore, the plunger 34 moves leftward in the drawing against the spring force of the plunger spring 38, and the valve body 45 further moves leftward from the intermediate position shown in the drawing. Therefore, as the warm-up progresses, the seating portion 45b approaches the seat surface 43a to gradually reduce the opening area of the orifice 44, and when the warm-up is completed, the opening area is minimized to compensate for the passage of a predetermined air flow rate. become.

As described above, in this embodiment, the two electromagnetic coils 28 and 29 are used to attract the valve element 45 at the intermediate position of the stroke in the opening direction or the closing direction. The supply voltage is generated due to the increase of the coil resistance value at cold start or high temperature start, and the plunger 3
Even if the suction force with respect to 4 is reduced, the opening / closing stroke amount of the valve element 45 can be sufficiently secured. As a result, the air flow rate can be controlled with high precision, and in particular, the air flow rate at the time of cold start can be sufficiently secured as shown in FIG.

Hereinafter, based on FIG. 3, as in this embodiment, 2
The air flow rate characteristics at the time of high engine temperature when one electromagnetic coil 28, 29 is used and when one electromagnetic coil is used as in the conventional case will be described.

That is, assuming that the temperature at high temperature is T1 (° C.), the resistance value of the electromagnetic coil at room temperature (20 ° C.) is R ₂₀ (Ω), and the resistance value of the electromagnetic coil at high temperature is R1 (Ω). , R1
Is expressed by the R1 = R ₂₀ × [1 + 0.000393 × (T1-20)] (Omega). The applied voltage is V (constant).

The opening area of the orifice that determines the air flow rate is proportional to the opening / closing stroke of the valve body, and the stroke of the valve body is proportional to the attraction force of the electromagnetic coil. Then, this attractive force is proportional to the value of the current flowing through the electromagnetic coil.

Therefore, the air flow rate Qα, the electromagnetic flow I = (V / R) flowing in the electromagnetic coil, the current I1 flowing in the electromagnetic coil at T1 at high temperature is: I1 = V / R ₂₀ × [1 + 0.0000393 × (T1 -2
0)] ... (1), whereby the coil current ratio P% at room temperature is

[Equation 1] Becomes

Further, the flow rate gradient (ΔQ / Δduty) of the air flow rate characteristic at high temperature is united in both the simple electromagnetic coil type and the two electromagnetic coil types by the current change rate (according to the equation (1)). Determined and both are equivalent.

In the single electromagnetic coil type, one electromagnetic coil changes the air flow rate from 0% duty (valve position when non-energized = reference) to 100% duty. Therefore, the flow rate characteristics at high temperature are in the region controlled by one electromagnetic coil (Δ duty = 100-0 = 1
00) (in the steady state characteristic), the air flow rate value (Q2) of the duty value (D) obtained by multiplying the coil current ratio P at high temperature has a characteristic of shifting to the duty 100% point (broken line in FIG. 3).

On the other hand, in this embodiment, the valve closing electromagnetic coil 29 has a duty of 0 to 50% and the valve opening electromagnetic coil 2 has a duty of 0 to 50%.
8 shares the change of the air flow rate with the duty of 50 to 100%. Therefore, the air flow rate characteristic duty 5 at high temperature
Based on 0%, on the low duty side, △ duty =
The air flow rate value (Q1) having a duty value (D2) obtained by multiplying 50-0 = 50 by P has a characteristic of shifting to the duty 0% point. On the high duty side, Δduty = 1
The air flow rate value Q3 of the duty value D1 obtained by multiplying 00-50 = 50 by P has a characteristic of shifting to the duty 100% point (see the dashed line in FIG. 3).

In summary, when two electromagnetic coils 28 and 29 are used, the air flow rate characteristics at high temperature are 2
Since the air flow rate control duty region shared by Nos. 8 and 29 is halved as compared with the single electromagnetic coil type, the reduction amount of the air flow rate with a duty of 100% is halved.

Moreover, in this embodiment, when the engine is stopped, that is, when the electromagnetic coils 28 and 29 are not energized, the valve body 4 is
The spring force of both springs 38 and 48 causes the valve 5 to return from the opening position close to the fully closed position of the orifice 44 to the middle opening position (the position shown in FIG. 2), and the valve seat 43 is brought into a non-contact state. Therefore, even if carbon or the like adheres to the valve element 45 or the like during engine operation, it is possible to reliably prevent sticking due to solidification on the valve seat 43 when stopped. In addition, the outer peripheral surfaces 34a, 34 of the front and rear end portions of the plunger 34
Since b and the inner peripheral surfaces 31a and 32a of both cores 31 and 32 are tapered, the stroke width of the plunger 34 can be increased. As a result, the control width of the opening area of the orifice 44 by the valve body 45 becomes large,
Highly accurate air flow rate control is possible.

Both springs 38, 48 of the valve body 45 are
Accurate positioning to the intermediate position by means of can be done by the adjusting end wall 41. Furthermore, the valve element 45 does not necessarily have to be held at the substantially intermediate position of the entire stroke by the both springs 38 and 40, but may be at a position where it is not in contact with the valve seat 43.

Further, although the present invention has been described by taking the case where the present invention is used for the idle speed control device as an example, the present invention can also be used as a torque control device at the time of lean burn control, for example. is there.

[0034]

As described above, according to the present invention, when the engine is started at a low temperature, the valve element held at the intermediate opening position is provided with the two electromagnetic coils to which the control signals having the opposite phases are input. Since the opening / closing control is performed, a sufficient opening / closing stroke amount of the valve body can be obtained as compared with the case where a single electromagnetic coil is used even if the supply voltage is lowered due to high temperature or the like. Therefore, it is possible to prevent the maximum control flow rate from excessively decreasing, and it is possible to secure a control flow rate that is substantially close to the required maximum flow rate.

If the valve body secures a predetermined opening degree in the orifice when the solenoid valve is not energized,
When the electromagnetic coil is not energized when the engine is stopped, the valve body is kept in a non-contact state with the valve seat. Therefore, it is possible to prevent the stick due to the dirt attached between the valve body and the valve seat.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an idle speed control device according to an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a comparison between a duty ratio and an air flow rate of the present embodiment and a conventional one.

FIG. 3 is a vertical sectional view of a conventional idle speed control device.

[Explanation of symbols]

 1 Intake Passage 2 Throttle Valve 20 Bypass Passage 21 Electromagnetic Valve 22 Valve Housing 23 Solenoid Casing 28 Valve Opening Electromagnetic Coil 29 Valve Closing Electromagnetic Coil 38 Plunger Spring (Spring Member) 43 Valve Seat 44 Orifice 45 Valve Body 48 Valve Spring (Spring) Element)

Claims (2)

[Claims] 1. An auxiliary engine for an internal combustion engine, comprising: a bypass passage for bypassing a gas passage of the internal combustion engine; and a solenoid valve for controlling the flow rate of air flowing through an orifice of a valve seat in the bypass passage through a valve element. In the flow control device,
A pair of spring members that hold the valve element in the intermediate position of the entire stroke are provided on both ends in the operating direction of the valve element by opposing spring force, and the valve element is opened and closed in the solenoid casing of the solenoid valve. An auxiliary flow rate control device for an internal combustion engine, characterized in that a control circuit for accommodating a pair of front and rear electromagnetic coils and applying a control current of a relatively opposite phase to the both electromagnetic coils according to the state of the engine is provided. . 2. The auxiliary flow rate control device for an internal combustion engine according to claim 1, wherein the valve body secures a predetermined opening degree in the orifice when the solenoid valve is not energized.