JPH06117568A - Proportional solenoid control valve - Google Patents

Abstract

PURPOSE:To improve the flow rate characteristic by resiliently urging a valve element in a direction in which it is lifted from a valve seat provided in a flow passage, and by providing an auxiliary valve element which is positioned in an opening of the valve seat in a loosely fitted condition during deenergization of a solenoid, on one end side of the valve element. CONSTITUTION:A valve body 20 adapted to be seated on a valve seat 15 provided in a passage part 13 in a housing 11, is urged leftward by a spring 22 held between a cap 18 and the valve body 20, and the valve body 20 is composed of a poppet-like valve body 20c and a relatively small diameter auxiliary valve body 20d which is formed at the front end part of the valve element 20 and which is located in a loosely fitted condition in an opening of the valve seat 15 during deenergization of a solenoid device 12. Further, at an initial position, a flow rate of leakage which is determined by a gap area therebetween. When a solenoid device 12 is energized so as to move the valve body 20 leftward, a maximum flow rate is obtained at a position where the auxiliary valve element 20d is completely lifted from the valve seat 15, and thereafter, the flow rate is gradually decreased, and the valve element 20c is completely seated on the valve seat 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic proportional control valve,
More specifically, it relates to an improvement of an electromagnetic proportional control valve suitable for controlling the auxiliary air flow rate of an internal combustion engine for a vehicle.

[0002]

2. Description of the Related Art Various flow control valves are used in an internal combustion engine for a vehicle for the purpose of adjusting the amount of intake air during start-up warm-up operation and stabilizing idle speed against load fluctuation. Has been. As a control valve for performing such an auxiliary air flow rate control, there is a control valve that uses a proportional solenoid to continuously and variably adjust the auxiliary air flow rate. FIG. 4 shows a schematic structure of the valve body portion, in which the poppet-shaped valve body 1 is fitted into the passage opening 2 with a predetermined gap C at the valve closing position. A proportional solenoid (not shown) is connected to the valve body 1 to open and close it.

The proportional solenoid is supplied with a pulsed signal whose on / off time ratio changes from 0% to 100%, and the valve body 1 is moved to the left side in the figure according to the time ratio (duty ratio). By making the stroke to, the opening area of the opening 2, that is, the air flow rate can be proportionally controlled between the minimum flow rate (leakage flow rate) Qd and the maximum flow rate Qa as shown in FIG. . (As a known document of this type of proportional control valve, for example, JP-A-57-93
See Japanese Patent Publication No. 80. )

[0004]

By the way, in such an electromagnetic control valve used for controlling the intake air flow rate of an internal combustion engine, the valve body 1 is fully closed by a spring so that the flow rate does not increase in the event of a failure such as disconnection. The valve body 1 is always positioned at the fully closed position where the valve body 1 is fitted into the opening 2 when the engine is stopped when no current is supplied. Therefore, if the gap C between the opening 2 and the valve body 1 is reduced in order to suppress the leakage flow rate Qd, the outer peripheral portion of the valve body 1 and the inner peripheral portion of the opening 2 due to oil and impurities in the intake air during the stop. May cause so-called sticking, which results in a lightly adhered state, and as a result, there is a risk that the device will not operate smoothly even when electricity is applied.

Further, as a characteristic of the solenoid for driving the valve body 1, since the stroke amount decreases when the temperature rises due to the influence of heat from the engine, the maximum flow rate as a control valve as shown by the broken line in FIG. The value Qa has dropped,
There is also a problem that the required flow rate characteristics cannot be obtained.

The present invention has been made in view of such conventional problems, and an object thereof is to prevent sticking of a valve body when the proportional control valve is not energized and to improve temperature characteristics.

[0007]

In order to achieve the above object, the present invention provides a proportional control valve having a proportional electromagnetic solenoid for opening and closing a valve body for opening and closing a flow path based on a control current, in which the valve body is provided. Is elastically biased in a direction away from a valve seat interposed in the middle of the flow path, and is loosely fitted to the opening of the valve seat on one end side of the valve body in a non-energized state of the solenoid. An auxiliary valve body was provided.

[0008]

[Function] When the solenoid is in the non-energized state, the valve element is elastically biased to the initial position. At this time, the auxiliary valve element is fitted with the valve seat opening. Is regulated.

When a control signal is supplied to the solenoid from this initial position to drive the valve body to the point where the auxiliary valve body comes out of the valve seat opening, the opening area and flow rate of the valve seat opening become maximum. When the stroke amount of the valve body is further increased, the opening area gradually decreases due to the proximity of the valve body and the valve seat.
When the stroke amount is controlled to the point where the valve body is seated on the valve seat, the control valve is fully closed.

Thus, even if the valve stroke amount at the same control signal value decreases due to the temperature characteristic change of the solenoid since the stroke position where the maximum flow rate is generated is at the intermediate position between the initial position and the maximum stroke position, It is possible to secure the maximum flow rate or the target flow rate by correcting the control signal value in the stroke increasing direction by an appropriate amount.

On the other hand, since the minimum flow rate can be controlled to a minimum of zero in accordance with the distance between the valve body and the valve seat in the maximum stroke region, the gap between the auxiliary valve body and the valve seat opening at the initial position can be controlled. Can be set to a relatively large value, whereby the sticking phenomenon of the valve element due to the adhesion of impurities and the like can be avoided.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 11 denotes a control valve housing,
Reference numeral 12 is a proportional solenoid device attached to one end thereof.

The housing 11 has a cylindrical passage portion 13
And the passage portion 14 are formed so as to intersect each other, and the annular valve seat 1 fitted in the middle of one passage portion 13
The passage connection port 1 is provided in each of the passage portions 13 and 14 with the passage 5 interposed therebetween.
3a and 14a are formed. Passage connection port 13a, 1
4a is connected to the inlet side and the outlet side of an auxiliary air passage formed so as to bypass the intake throttle valve of the internal combustion engine, for example.

The passage portion 13 penetrates the housing 11 and is a cylindrical bearing 1 fitted in a through hole 16 on the left side of the drawing.
7, and the valve body 20 is supported via a cap 18 screwed into the opening 13b on the right side.

The valve body 20 is fixed to a valve shaft 21 whose front end is supported by a bearing portion 18a formed inside the cap 18, and the sliding portion 20a formed at the base end thereof and the above bearing. Through the fitting portion with 17 and the fitting portion with the tip end portion of the valve shaft 21 and the bearing portion 18a, the valve seat 15 is penetrated and supported slidably in the axial direction.

The valve body 20 is constantly urged to the left side in the figure based on the tension of the spring 22 interposed between the seat portion 20b formed on the tip end side and the cap 18.

On the other hand, the solenoid device 12 includes a cylindrical casing 24 attached to the housing 11 through a flange 23 so as to face the through hole 16 thereof, and a hollow bobbin 25 housed inside the casing 24. , A plunger 26 slidably accommodated inside the bobbin 25
And a solenoid coil 27 and the like wound around the bobbin 25.

A push rod 28 is attached to the tip of the plunger 26.
Is supported so as to be axially slidable with the plunger 26 via a bearing 29 fixed to the casing 24 so as to be coaxial with the through hole 16.

A balancing spring 30 having a tension smaller than that of the spring 22 is provided behind the plunger 26. The tip of the push rod 28 is connected to the valve shaft 21 by the tension of the springs 22 and 30. The valve main body 20 is positioned at the initial position according to the balance that is brought into contact with the base end portion and is adjusted according to the screwing amount of the cap 18 with respect to the housing 11.

FIG. 2 shows the details of the valve main body 20. As shown in the drawing, a poppet-like valve body 20c having a small diameter portion facing the operating direction (right side in the figure) and the tip thereof are formed. An auxiliary valve body 20d having a relatively small diameter is formed.

The dimensions are set such that the outer diameter of the valve body 20c is larger and the outer diameter of the auxiliary valve body 20d is smaller than that of the opening of the annular valve seat 15. FIG. 1 shows a state in which the valve body 20 is in the initial position. At this time, the auxiliary valve body 20d is fitted into the opening of the valve seat 15, and the valve body 20c is located behind it.

When a pulsed control current is supplied to the solenoid coil 27 in the above structure, the plunger 26 moves to the right as the ON time ratio (duty ratio) increases, and the spring 22 passes through the push rod 28. The valve body 20 is driven to the right while resisting.

FIG. 3 is a flow rate characteristic diagram when the valve body 20 is actuated from the initial position in this way. The solid line shows the characteristic under the reference condition of a relatively low temperature, and the broken line shows the heat resistance at a relatively high temperature. The characteristics are shown respectively.

When the duty ratio of the control signal is zero, the valve body 20 is in the initial position, and since the auxiliary valve body 20d is fitted in the opening of the valve seat 15 at this time, the flow rate depends on the mutual clearance area. The determined leak amount is Qb.

When the duty ratio is increased from this state, the auxiliary valve body 20d comes out of the valve seat 15 as the valve body 20 moves to the right, so that the flow rate gradually increases and the auxiliary valve body 20d is completely removed from the valve seat 15. The maximum flow rate Qa is reached when it escapes to.

When the duty ratio is further increased, the taper surface of the valve body 20c comes closer to the opening of the valve seat 15, so that the flow rate decreases in proportion to the stroke amount of the valve body 20 until finally. The valve body 20c is seated on the valve seat 15 and is in a fully closed state. The flow rate at this time is theoretically zero, but in reality, some leakage Qd occurs.

By the way, since the valve stroke position at which the maximum flow rate Qa is obtained occurs at the intermediate position between the initial position and the maximum stroke position, the same duty due to the temperature characteristic change of the solenoid device 12 as shown by the broken line. Even if the valve stroke amount in the ratio decreases, it is possible to secure the maximum flow rate by correcting the duty ratio by an appropriate amount in the stroke increasing direction, and maintain high resolution even during such heat resistance. The target flow rate can be obtained with high accuracy. In FIG. 3, Qc represents the minimum flow rate during heat resistance.

Further, since the flow rates are small Qb and Qd at both ends of the initial position and the maximum stroke position of the valve body 20, the duty ratio of the control signal is fixed to zero or 100% due to the failure of the control circuit. Even if it happens, excess air will not be supplied to the engine, and therefore it is possible to avoid an increase in engine rotation at the time of a circuit failure.

Furthermore, the minimum flow rate Qd can be controlled to a minimum of about zero according to the distance between the valve body 20c and the valve seat 15 in the maximum stroke region, so that the auxiliary valve body 20d and the valve seat 15 at the initial position are controlled. The gap between the opening and the opening can be set to be large to some extent, whereby the sticking phenomenon of the valve body due to the adhesion of impurities and the like can be avoided.

[0031]

As described above, according to the present invention, the valve body for controlling the flow rate is elastically urged in the direction of separating from the valve seat, and the valve seat opening is opened at the initial position where the solenoid is not energized. An auxiliary valve body to be fitted is provided, and the maximum flow rate is obtained when the valve body is stroked from the initial position by a predetermined amount according to the control current to the solenoid, and the flow rate is gradually reduced as the stroke increases thereafter. Therefore, the maximum flow rate can be reliably ensured by correcting the stroke amount regardless of changes in the temperature characteristics of the solenoid. Further, not only the maximum flow rate but also the desired opening degree and flow rate can be obtained accurately and surely by such stroke correction.

On the other hand, the minimum flow rate of the control valve is not limited to the gap between the auxiliary valve body and the valve seat opening portion at the initial position, but is the minimum according to the distance between the valve body and the valve seat in the maximum stroke range. Since it can be set to zero, it is possible to improve the flow rate controllability together with the effect of improving the above resolution, and even if the stroke position of the valve body is fixed at either the maximum or minimum position due to circuit abnormality etc. Since the flow rate at that position is small, there is an advantage that it has little influence on the engine operation.

Further, since the minimum flow rate can be set on the basis of the relationship between the valve body and the valve seat as described above, the auxiliary valve body and the valve seat opening portion for restricting the leakage flow rate when not energized. It is possible to secure a sufficient gap between the and, and as a result, it is possible to avoid the sticking phenomenon and always secure smooth operability.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an embodiment of the present invention.

FIG. 2 is an enlarged view of a valve body portion of the embodiment.

FIG. 3 is a flow rate characteristic diagram showing a relationship between a control signal and a flow rate according to the embodiment.

FIG. 4 is a schematic view of a valve body part of a conventional example.

FIG. 5 is a flow rate characteristic diagram showing a relationship between a control signal and a flow rate in a conventional example.

[Explanation of symbols]

 11 Control Valve Housing 12 Proportional Solenoid Device 15 Valve Seat 20 Valve Body 20c Valve Body 20d Auxiliary Valve Body 22 Spring 27 Solenoid Coil

Claims (1)

[Claims] 1. A proportional control valve provided with a proportional electromagnetic solenoid for opening / closing a valve body for opening / closing a flow path based on a control current, wherein the valve body is separated from a valve seat interposed in the middle of the flow path. Electromagnetic proportional control valve, which is elastically biased in a direction and is provided with an auxiliary valve body that is loosely fitted to the opening of the valve seat at one end of the valve body when the solenoid is not energized. .