JP2605927B2 - Proportional flow control valve - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve for controlling a flow rate of a fluid in proportion to an output of a drive source, and particularly to a vicinity of a throttle valve of an intake pipe in an internal combustion engine. This is useful as a proportional flow control valve for adjusting the amount of intake air, which is disposed in a bypass passage provided in the apparatus.

2. Description of the Related Art Conventionally, an electronically controlled fuel injection engine in which a bypass passage is provided in the vicinity of a throttle valve of an intake pipe and the amount of intake air of the engine is adjusted by opening and closing the bypass passage has been known. is there.

FIG. 4 shows an example of a proportional flow control valve used for opening and closing the bypass passage. Reference numeral 1 denotes a solenoid device, and a fixed
Are arranged. A cylindrical case 3 is mounted on the inner periphery of the solenoid device 1, and a movable iron core 4 serving as a flow rate adjusting means is disposed at a position facing the fixed iron core 2, and a return spring 5 Is interposed.

An electromagnetic coil 6 is disposed on the inner peripheral surface of the case 3 via an insulating material 3a, and a bobbin around which the electromagnetic coil 6 is wound.
A pipe 7 is mounted on the inner peripheral surface of 6a, and the fixed iron core 2 and the movable iron core 4 are disposed inside the pipe 7. The return spring 5 is provided in a space between the fixed iron core 2 and the movable iron core 4 via a spring holder 5a, and the movable iron core 4 is moved in a direction against the electromagnetic attraction force of the electromagnetic coil 6 by the return spring 5. Has been energized. That is, by the return spring 5,
A force pressing leftward in FIG. 4 always acts on the movable core 4. A lead wire 6b extending to the outside is connected to the electromagnetic coil 6.

A spring 8 is disposed on the side of the movable core 4 opposite to the return spring 5. The spring 8 is attached between a spring 4 and a stepped portion 4a whose diameter is reduced near the tip (left end in FIG. 4) of the movable iron core 4. The spring holder 9 is fixed to the tip of an adjusting screw 10. ing.

The tip of the movable core 4 including the step 4a, the spring 8,
The spring holder 9 and the adjusting screw 10 are located in the empty chamber 11b inside the proportional flow control valve main body 11 connected to the solenoid device 1. The proportional flow control valve body 11 has a fluid introduction passage 11a near the end on the solenoid device 1 side.
In the vicinity of the tip (the left end in FIG. 4), there is provided a fluid outlet passage 11c that opens to the empty chamber 11b. The tip of the pipe 7 (the left end in FIG. 4) is a cushioning material.
The support chamber 13 is held via a support member 13 fixed in the proportional flow control valve main body 11, whereby the empty chamber 11 b of the proportional flow control valve main body 11 is partitioned from the fluid introduction passage 11 a side.

The adjusting screw 10 is screwed to the proportional flow control valve body 11 in a direction from the distal end side where the fluid outlet passage 11c is provided to the movable iron core 4 side. The movable core 4 is constantly urged in the rightward direction in FIG. 4, that is, in the direction in which the electromagnetic attraction force is exerted, by the spring 8 held by the spring holder 9 fixed to the adjusting screw 10.

A fluid flow hole 7a of a predetermined size communicating with the fluid introduction passage 11a of the proportional flow control valve body 11 is formed near the tip of the pipe 7. The fluid flow hole 7a is provided at a position closed by the outer peripheral surface of the movable core 4 when the electromagnetic coil 6 is not energized.

In order to balance the pressure on the side of the vacant chamber 11b communicating with the fluid lead-out passage 11c and the pressure in the space formed between the movable core 4 and the fixed core 2, the shaft core of the movable core 4 is provided. A conduction hole 4b is provided.

The spring 8, which is mounted between the spring holder 9 and the step 4 a of the movable core 4 and biases the movable core 4 in the direction in which the attraction force of the electromagnetic coil 6 works, the biasing force of the spring 8 is adjusted in advance by an adjusting screw 10. Thereby, the position of the movable iron core 4 is set.

In the proportional flow control valve having such a configuration, when the electromagnetic coil 6 is energized and the electromagnetic coil 6 is excited,
The movable core 4 is attracted to the fixed core 2 side against the pressing force of the return spring 5. At this time, the spring 8 acting in the suction direction extends as the movable iron core 4 moves.

When the movable core 4 is sucked toward the fixed core 2 as described above, the fluid flow hole 7a of the pipe 7 is opened, and the fluid (air) diverted from the intake pipe to the bypass passage is supplied to the fluid introduction passage 11a, The fluid flows into the fluid outlet passage 11c through the space 11b between the fluid passage hole 7a of the pipe 7 and the spring 8, and flows through the bypass passage to join the flow of the intake pipe.

In this type of proportional flow control valve, in order to reduce the hysteresis due to the frictional resistance of the sliding part,
Duty control to intermittently energize the electromagnetic coil at a certain frequency and change the ratio of ON time and OFF time to make the movable core finely slide, or to set a constant current value (DC) Dither control is generally used in which the movable iron core is slightly slid with variation (AC component).

By the way, the proportional flow control valve shown in FIG.
Since the valve is a spool type valve, fluid leaks from the clearance between the movable iron core 4 forming the spool and the pipe 7 forming the sleeve. Therefore, when the control duty is set to zero as shown in FIG. But the flow did not go to zero. However, in the control of the bypass air flow rate of the internal combustion engine, when it is not necessary to flow the bypass air in the idle operation state, it is desirable to reduce the amount of leakage from the bypass passage and reduce the engine speed to save fuel. In particular, in a vehicle with a small displacement, the absolute value of the air flow required for the idle operation itself is small, so that the idle rotation of the engine may be secured only by the amount of leakage from the throttle valve alone. In order to improve the fuel consumption rate by reducing the amount of leakage from the bypass passage as described above to prevent the engine idle speed from unnecessarily increasing, the relationship between the grade of the vehicle and the fuel consumption rate is considered. It is something that is strongly desired.

As for a spool type valve, a type in which a stopper is provided so as to come into contact with the tip of a control spool (movable iron core) when the electromagnetic coil is not energized has been known (see Japanese Utility Model Laid-Open No. 63-145078). In the proportional flow control valve having the structure as shown in FIG. 4, such a stopper also functions as a valve seat, which may improve the sealing performance. However, in this type of proportional flow control valve, as described above, in order to reduce the hysteresis due to the frictional resistance of the sliding portion, duty control or dithering for interrupting the energization of the electromagnetic coil at a certain frequency. Since the control is generally performed, if the valve seat is provided, the flow rate adjusting means constituted by the movable iron core collides with the valve seat each time the seating and the seating are repeated, thereby generating a tapping sound. As shown in FIG. 6, an abnormal phenomenon occurs in the flow characteristics. It is also conceivable to provide an elastic body such as rubber on the contact surface of the flow rate adjusting means or the valve seat in order to avoid such a tapping sound or an abnormal phenomenon, but in that case, the intended purpose is sufficiently achieved. For this purpose, it is necessary to make the elastic body relatively small in hardness so that the elastic body can be easily conformed. In such a case, the contact position and the contact load between the flow rate adjusting means and the valve seat are varied, and as a result, the valve opening timing is reduced. A problem that variation is increased occurs.

The above situation is the same in the case of a poppet valve.
In the case of a poppet valve, the sealing performance is easily improved due to its structure, but on the other hand, the above-described tapping sound and abnormal phenomena of the flow characteristics are apt to occur.

In order to solve such a problem, as described in Japanese Patent Application Laid-Open No. 63-243582, a valve body made of a hard resin material having a bellows integrally formed on a side portion is moved by a leaf spring. While being loosely fitted into the core (movable core), the displacement of the valve body toward the valve seat is restricted by the locking piece, and an elastic body is arranged between the valve body and the movable core. There has been proposed a poppet valve configured to press a valve body against a locking side with a predetermined urging force.

[Problem to be Solved by the Invention] When a proportional spool control valve for opening and closing a passage bypassing a throttle valve of an internal combustion engine is constituted by a conventional spool type valve, as described above, the movable member forming the spool is movable. There is a leakage from the clearance between the iron core and the sleeve (cylindrical member), which causes a problem that the flow rate cannot be completely reduced to zero even in an operation region where the flow rate is desired to be zero. In addition, if a valve seat is provided, when duty control or dither control is performed, a tapping sound may be generated when the flow rate adjusting means is separated from or seated on the valve seat, or an abnormal phenomenon may occur. If an elastic body is provided on the seating portion in order to avoid noise and abnormal phenomena, there arises a problem that variations in the valve opening timing are increased due to variations in the contact position and the contact load.

In the poppet type valve, as described above, a valve body made of a hard resin material integrated with the bellows is loosely fitted into the movable iron core held by a leaf spring, and the valve body is pressed to the locking side by an elastic body. There is an example that attempts to solve the above problem by doing so. However, in this example, it is necessary to combine two or more types of coil springs, leaf springs, bellows, and the like, and to determine the operation characteristics based on the balance between the attraction and the attractive force of the electromagnetic coil. However, there is a problem that it is difficult to make adjustments because the variation easily occurs. Further, in the above example, if the pressures are not balanced by conducting each space between the valve element and the holding plate, between the holding plate and the magnet plate, between the movable core and the fixed core (stator core), a damper effect occurs. It will not be possible to obtain fast operation. for that reason,
A plurality of conducting spaces are required, and the possibility of blocking of the conducting space due to the invasion of foreign matters is large. If the conducting spaces are blocked, normal flow characteristics cannot be obtained.

The present invention has been made in order to solve such a problem, and it is possible to make the amount of leakage at the time of fully closing almost zero, and at the time of uncoupling and seating the flow rate adjusting means with respect to the valve seat. To provide a highly reliable proportional flow control valve that does not generate a tapping sound or an abnormal phenomenon of flow characteristics, is easy to adjust, and can always obtain normal flow characteristics. With the goal.

Means for Solving the Problems In a proportional flow control valve according to the present invention, a valve seat is provided on a proportional flow control valve main body, a reduced diameter portion is provided at an end of a movable iron core, and sliding is performed on the reduced diameter portion. A valve that is freely extrapolated and whose contact diameter with the valve seat is approximately equal to the sliding diameter of the movable core is provided, and this valve is urged in the direction toward the valve seat by an elastic body provided between the valve and the movable core. And
In addition, a holder for restricting the movement of the valve in the direction toward the valve seat by the elastic body is provided integrally with the reduced diameter portion, and a valve assembly including the movable iron core, the valve, the elastic body, and the holder is provided with a return spring. And slidably supported by the cylindrical member.

At least one of the sliding portions of the reduced diameter portion and the valve may be coated with a resin having a low friction coefficient.

[Operation] In the present invention, the valve assembly including the movable iron core, the valve, the elastic body and the holder is configured such that the elastic body stretches the movable iron core and the valve with a predetermined urging force, and the return spring applies a predetermined force to the valve seat. Abutting force. For this reason, the elastic body absorbs the repulsive force generated by the collision with the valve seat when the valve assembly is separated or seated due to the minute vibration of the valve assembly during the flow control by the duty control or the dither control. Therefore,
Prevents the impact sound caused by the collision between the valve and the valve seat,
It is possible to prevent an abnormal phenomenon from occurring in the flow characteristics.

In addition, the contact diameter between the valve seat and the valve is substantially equal to the sliding diameter of the movable iron core, and a conductive hole is provided in the shaft core of the movable iron core. Even if pressure is applied to the valve assembly, the forces applied to the valve assembly from the left and right through the through holes are balanced and a stable state is maintained.

Further, by applying a resin coating having a low friction coefficient to the sliding portion between the reduced diameter portion and the valve, the frictional force of the sliding portion is reduced, and the generation of wear powder is suppressed.
Sliding clearance can be reduced, and malfunctions caused by intrusion of minute foreign matter, relative fall of the movable iron core with the valve, and the like can be prevented.

FIG. 1 is a longitudinal sectional view of an embodiment of a proportional flow control valve according to the present invention, and FIG. 2 is an enlarged view of a main part thereof. Here, the same or corresponding parts as in the conventional example of FIG. 4 are denoted by the same reference numerals.

Reference numeral 1 denotes a solenoid device, and a fixed iron core 2 is disposed in the center of the solenoid device in the longitudinal direction. A cylindrical case 3 is mounted on the inner periphery of the solenoid device 1, and a movable core 4 is disposed at a position facing the fixed core 2, and a return spring 5 is interposed therebetween.

The movable iron core 4 has a reduced diameter portion 4c which is a guide portion.
A valve 14 is slidably fitted in 4c. And
A spring 15 is provided on the outer periphery of the reduced diameter portion 4c so as to urge the valve 14 toward the distal end, and a holder 16 for regulating the movement of the valve toward the distal end is provided at the distal end of the reduced diameter portion 4c.
Has been fixed. The spring 15 causes the valve 14 and the movable iron core 4 to project from each other, and causes the valve 14 to abut on the holder 16. Thus, the movable core 4 and the valve
The valve assembly 18 is constituted by the spring 14, the spring 15, and the holder 16.

An electromagnetic coil 6 is disposed on the inner peripheral surface of the case 3 via an insulating material 3a, and a bobbin around which the electromagnetic coil 6 is wound.
A pipe 7 is mounted on the inner peripheral surface of 6a, and the fixed iron core 2 and the movable iron core 4 are disposed inside the pipe 7 so as to face each other. The return spring 5 is provided in a space between the fixed iron core 2 and the movable iron core 4 via a spring holder 5a, and the movable iron core 4 is moved in a direction against the electromagnetic attraction force of the electromagnetic coil 6 by the return spring 5. Has been energized. That is, a force pressing the movable iron core 4 leftward in FIG. 1 is constantly applied by the return spring 5. A lead wire 6b extending to the outside is connected to the electromagnetic coil 6.

A spring 8 is disposed on the side of the movable iron core 4 opposite to the return spring 5. The spring 8 is mounted between the holder 16 fixed to the distal end of the reduced diameter portion 4c of the movable core 4 and the spring holder 9, and the spring holder 9 is provided with a proportional flow control valve body.
It is fixed to the tip of an adjusting screw 10 screwed to 11.

The proportional flow control valve main body 11 is provided with a fluid introduction passage 11a near the end on the solenoid device 1 side, and a fluid outlet passage 11c at the front end (the left end in FIG. 1).

The solenoid device 1 and the proportional flow control valve body 11
The proportional flow control valve main body 11 is fitted to the rib-shaped guide portion 19a of the guide member 19 fitted to the end of the solenoid device 1, and is fitted and fixed to each other without play. The guide member 19 holds one end of the pipe 7 that slidably supports the movable iron core 4. A valve seat 13 is fitted to the proportional flow control valve body 11 at a position opposite to the valve assembly 18, whereby an empty chamber 11b communicating with the fluid outlet passage 11c is partitioned from the fluid introduction passage 11a. Have been.

The adjusting screw 10 is screwed from the distal end side of the proportional flow control valve main body 11 where the fluid outlet passage 11c is provided to the movable iron core 4 side. The spring 8 held by the spring holder 9 fixed to the adjusting screw 10 constantly urges the movable iron core 4 in the same direction as the direction in which the electromagnetic attraction acts.

The valve assembly 18 assembled as described above receives the urging force of the spring 8 and the return spring 5 and pushes the movable iron core 4 against the valve seat 13 in a state where the collapse caused by the clearance with the pipe 7 is allowed. Can be touched. Here, the urging force of the spring 8 attached between the holder 16 and the spring holder 9 is adjusted in advance by the adjusting screw 10, whereby the urging force of the valve assembly 18 toward the valve seat 13 is reduced. Adjusted.
At this time, the contact load between the valve 14 and the valve seat 13 is smaller than the contact load between the valve 14 and the holder 16 due to the spring 15, and a gap between the valve 14 and the holder 16 when fully closed. Settings that do not occur are performed.

Further, the seat surface of the valve seat 13 is tapered (conical), and the contact surface of the valve 14 with respect thereto is spherical. Here, the diameter of the contact circle between the tapered sheet surface and the spherical contact surface is, for example, 11 mm, and is set to substantially match the sliding diameter between the movable iron core 4 and the pipe 7. . The valve seat 13 and the valve 14 can be made of, for example, polybutylene terephthalate (PBT).

The pressure of the vacant chamber 11b side communicating with the fluid outlet passage 11c, the movable core 4 and the fixed core 2
A conduction hole 4b is provided in order to balance the pressure of the space formed between them. The conduction hole 4b has a maximum diameter of 3 mm or more.

In the proportional flow control valve having such a configuration, when the electromagnetic coil 6 is energized, the movable iron core 4 is attracted to the fixed iron core 2 against the pressing force of the return spring 5, and the valve assembly 18 moves to open the valve. I do. Here, when using this proportional flow control valve to control the flow rate by duty control or dither control, the repulsive force generated by a collision at the time of uncoupling or sitting due to minute vibration of the valve assembly 18 due to these controls is , The spring for biasing the valve 14
Absorbed by 15. As a result, as shown in FIG. 3, the sealing performance when the duty is zero is ensured, and a flow characteristic free from abnormal phenomenon is obtained.

Further, in this embodiment, since the solenoid device 1 and the proportional flow control valve main body 11 are fitted without looseness by the guide member 19 as described above, the contact portion between the valve assembly 18 and the valve seat 13 is formed. The gap is between the movable core 4 and the pipe 7
The clearance between the valve assembly 18 and the valve seat 18 is only caused by the clearance, and the seat surface of the valve seat 13 is tapered as described above, and the contact surface of the valve 14 with respect to the tapered surface is spherical. Even if there is, the sealing property is ensured by contacting with a contact circle having a predetermined diameter.
The sliding clearance between the movable core 4 and the pipe 7 is 0.
02 to 0.2 mm, and the ratio L / D of the sliding length L to the sliding diameter D is
1.5 or more.

Further, in this embodiment, as described above, the valve seat 13
When the negative pressure in the intake pipe is applied to the fluid outlet passage 11c when no current is supplied, the diameter of the contact hole is substantially equal to the diameter of the contact circle between the valve 14 and the valve 14. The forces applied to the valve assembly 18 from the left and right via 4b are balanced, and a stable state is maintained.

By the way, according to the above structure, when the valve 14 and the valve seat 13 collide, the valve 14 moves while the spring 15 absorbs the repulsive force applied to the valve. In this case, the valve 14 and the movable core 4 The valve 14 moves on the reduced diameter portion 4c of the movable core 4 due to the generation of wear powder on the sliding surface with the reduced diameter portion 4c, the penetration of minute foreign matter, and the relative fall of the valve 14 and the movable core 4. If it does not slide smoothly, the following inconvenient phenomenon occurs. That is, when the valve 14 and the movable iron core 4 cannot be slid in a stretched state, the repulsive force due to the collision between the valve 14 and the valve seat 13 cannot be absorbed, and the tapping sound and abnormal flow characteristics occur. I do. If the spring 15 cannot be slid in a state of being compressed to some extent, the valve 14 will remain open even if the drive source is turned off, and in the worst case, the engine will overrun, There is a risk of runaway. Therefore, in this embodiment, the reduced diameter portion 4c of the movable iron core 4 is used.
At least one of the sliding portions of the valve and the valve 14 is coated with a resin having a low coefficient of friction such as Teflon (trade name). The thickness of this coating is 10-30μm
Degree. A similar coating may be applied to the sliding portion of the movable iron core 4 with the pipe 7, and in that case,
For example, a method of performing coating by spraying while rotating the movable core 4 as an object can be used. The method of coating by spraying has advantages such as a uniform film thickness and the elimination of coating on unnecessary portions as compared with coating by immersion. Further, if the same coating is applied to the reduced diameter portion 4c, which is the sliding portion of the movable iron core 4 with the valve 14, and the sliding portion with the pipe 7, it is not necessary to perform the masking process, and the process is improved accordingly. Leads to.

As described above, by applying a coating having a low friction coefficient to the sliding portion between the valve 14 and the movable iron core 4, the frictional force of these sliding portions is reduced, and generation of wear powder can be prevented.
In addition, since the sliding clearance can be reduced by reducing the frictional force, it is possible to prevent the invasion of minute foreign matter, and to surely prevent the malfunction due to falling down.

The holder 16 can be fixed to the movable iron core 4 by press-fitting, and can also be fixed by bonding or caulking. Further, a smaller diameter portion may be provided at the tip of the reduced diameter portion 4c of the movable core 4 to fix the holder.

The contact portion between the valve 14 and the valve seat 13 is provided with a multi-stage conical contact surface on the valve 14 side.
The surface of the sheet may be spherical.

[Effects of the Invention] As described above, according to the present invention, a valve assembly is constituted by a movable iron core, a valve, an elastic body, and a holder, and is urged by a return spring and slidably supported by a cylindrical member. As a result, the sealing performance can be ensured by eliminating leakage when fully closed, and when the flow rate is controlled by duty control or dither control, rebound due to a collision at the time of uncoupling or sitting due to these controls. A highly reliable proportional flow control valve with a fully-closed function that absorbs force, eliminates tapping noise and abnormal phenomena of flow characteristics, is easy to adjust, and can always maintain normal flow characteristics. Is obtained. In addition, by applying a resin with a low friction coefficient to at least one of the sliding parts of the movable core and the valve, the frictional force of the sliding part between the valve and the movable core is reduced to prevent the generation of wear powder. In addition, since the sliding clearance can be reduced, malfunctions due to invasion or falling down of minute foreign matter can be prevented, and the reliability of the proportional flow control valve with the fully closed function can be further improved. Furthermore, when the same coating is applied to the sliding portion of the movable iron core with the valve and the sliding portion with the cylindrical member, it is possible to improve the process by eliminating the need for masking processing at the time of coating.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of one embodiment of a proportional flow control valve according to the present invention, FIG. 2 is an enlarged view of a main part thereof, FIG. 3 is a flow characteristic diagram thereof, and FIG. FIG. 5 is a vertical sectional view of a control valve, FIG. 5 is a flow characteristic diagram thereof, and FIG. 6 is a typical flow characteristic diagram of a conventional poppet type valve. In the figure, 1 is a solenoid device, 2 is a fixed iron core, 3 is a case, 4 is a movable iron core, 4c is a reduced diameter portion, 5 is a return spring, 6 is an electromagnetic coil, 7 is a pipe (cylindrical member), 11
Is a proportional flow control valve body, 11a is a fluid introduction passage, 11c is a fluid outlet passage, 13 is a valve seat, 14 is a valve, 15 is a spring (elastic body), 16 is a holder, 18 is a valve assembly,
19 is a guide member. In the drawings, the same reference numerals indicate the same or corresponding parts.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-266377 (JP, A) JP-A 61-87275 (JP, U) JP-A 63-51977 (JP, U) JP-A 60-87 2071 (JP, U) Japanese Utility Model 2-21379 (JP, U) Japanese Utility Model Application No. 54-39625 (JP, U)

Claims (2)

(57) [Claims] An electromagnetic coil wound so as to form a magnetic field by applying a current; a case of a magnetic body into which the electromagnetic coil is inserted; a fixed iron core forming a magnetic circuit together with the case; A movable core that is swingably disposed so as to be attracted in a direction toward the fixed iron core by an electromagnetic attraction force of an electromagnetic coil, and a return spring that biases the movable iron core in a direction opposite to the electromagnetic attraction force. A proportional flow control valve for controlling a flow rate of a fluid flowing from a fluid introduction passage of a proportional flow control valve body to a fluid discharge passage by sliding of the movable iron core, wherein a valve seat is provided on the proportional flow control valve body. ,
A diameter-reduced portion is provided at an end of the movable core, and a valve is provided which is slidably externally inserted into the diameter-reduced portion and whose contact diameter with the valve seat is substantially equal to the sliding diameter of the movable core. A holder that urges the valve in a direction toward the valve seat by an elastic body provided between the movable iron core and a holder that regulates movement of the valve in a direction toward the valve seat by the elastic body. The movable iron core, the valve, the elastic body, and the holder constitute a valve assembly that is slidably supported by the return spring, and is provided integrally with the reduced diameter portion. A proportional flow control valve, wherein a conduction hole for balancing a pressure between the movable iron core and the fixed iron core with a pressure on the fluid outlet passage side is provided in a core portion. 2. The proportional flow control valve according to claim 1, wherein at least one of the reduced diameter portion and the sliding portion of the valve is coated with a resin having a low coefficient of friction.