JPH07145873A - Solenoid valve - Google Patents

Abstract

PURPOSE:To provide a solenoid valve which is constituted to regulate a flow rate with high precision without increasing the generation of working noise during opening of a valve. CONSTITUTION:A solenoid valve comprises a valve seat 11c arranged to the opening end part of a fluid passage; a valve body 8 to seat the valve seat to close a fluid passage; a coil spring 6 through the force of which the valve body 8 is energized in a closing direction; and an electromagnetic solenoid 1 to energize the valve body 8 in an opening direction against the force of the coil spring and open a fluid passage. The valve body 8 has a protrusion part 8a arranged in the fluid passage and when the protrusion part 8a is positioned in the passage, the area of the fluid passage is reduced by the protrusion part 8a, whereby a flow rate is reduced. Namely, since the decrease of the area of the passage before the valve body seats results in the decrease of a flow rate, there is no need to effect the instantaneous change of a current during closing of the valve and thus, linearity of the rise characteristics of a Duty flow rate can be improved without increasing the generation of working noise.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solenoid valve arranged in a fluid passage for controlling the flow rate of fluid passing through the fluid passage.

[0002]

2. Description of the Related Art A conventional solenoid valve is shown in FIG. The solenoid valve shown in FIG. 10 is for a vehicle and is applied to purge evaporated fuel generated from a fuel tank and passing through a canister to an engine by using intake pressure. In the figure, reference numeral 1 denotes an electromagnetic solenoid, which includes a coil 2, a yoke 3, a magnetic plate 4 and a fixed iron core 5. A movable body 7 is opposed to the fixed iron core 5 with a space in the axial direction. The movable body 7 is composed of a movable iron core 9, a leaf spring 10, and a valve body 8 made of an elastic body such as a rubber material. There is. The valve body 8 is attached to the central portion of the leaf spring 10, and the peripheral portion of the leaf spring 10 is sandwiched between the cover 11 and the coil bobbin 12. Therefore, the movable body 7 is held by the leaf spring 10. The outer circumference of the movable iron core 9 is movable in the axial direction by having a gap with the inner circumference of the coil bobbin 12, that is, the bearing portion 12a. The spring 6 biases the movable body 7 and the fixed iron core 5 in a direction to separate them from each other.

A cover 11 is connected to the electromagnetic solenoid 1 via a yoke 3. The cover 11 is integrally provided with ports 11a and 11b, and one port 11a is provided with a valve seat 11c with which the valve body 8 is brought into contact with and separated from the valve seat 8. When the valve body 8 is separated from the valve seat 11c, the ports 11a and 11b are electrically connected, and when the valve body 8 is seated on the valve seat 11c, the communication between the ports 11a and 11b is cut off. Reference numeral 16 is a seal member for maintaining airtightness, and 17 is a connector portion for connecting the coil 2 and the power source.

The solenoid valve having the above structure operates as follows. When the coil 2 of the electromagnetic solenoid 1 is energized, the movable body 7 is attracted to the fixed iron core 5 side. Then, the movable body 7 starts moving when the attraction force of the electromagnetic solenoid 1 overcomes the spring 6 that biases the movable body 7 itself toward the valve seat 11c, that is, when the coil current reaches the operation start current. Movable body 7
When the valve body 8 and the valve seat 11c are separated due to the movement of, the fluid passages 13, 14 and 15 are electrically connected and the fluid flows.

After that, when the coil 2 of the electromagnetic solenoid 1 is cut off and the value of the coil current falls below the urging force of the spring 6 (the current at this time is referred to as the recovery start current), the movable body 7 is attached with the spring 6. Separated from the fixed iron core 5 by force,
The valve body 8 is seated on the valve seat 11c, the fluid passages 13 and 14 are blocked, and the flow of fluid is stopped. The flow rate of the fluid in the fluid passage described above depends on the ratio of the opening / closing time of the valve body 8, and the flow rate can be adjusted by changing this ratio (hereinafter referred to as “Duty ratio”). it can.

The circuits for energizing the coil to operate the solenoid valve as described above are shown in FIGS. 11 and 12 (hereinafter referred to as "circuit A" and "circuit B", respectively).
Can be applied. The circuit A uses a Zener diode or the like so that the current waveform can be changed instantaneously when the valve is closed. On the other hand, the circuit B is designed so that the current waveform can be changed gently when the valve is closed. Note that FIG. 11 and FIG.
2, 201 and 203 are transistors, 202 is a Zener diode, 204 is a diode, and 205 is a coil indicating a solenoid valve.

[0007]

The operation of the solenoid valve when the circuits A and B are applied to change the current waveform when the valve is closed instantaneously or gently is shown in FIG.
It will be described based on 3. Note that FIG. 13 shows the operation when the same drive voltage shown in (a) is applied to both circuits, and the dashed line in (b) to (c) shows the case where the circuit A is applied. , Solid line corresponds to the one to which the circuit B is applied.

When the circuit A is applied, after the drive voltage shown in (a) is turned off, the current shown in (b) can be rapidly cut off. Therefore, as shown in (c), The valve can be closed promptly without delay. Therefore, as shown in (d), the flow rate does not increase, and
As shown in (1), since the duty ratio-flow rate characteristic is linear, the flow rate can be adjusted accurately.

However, in the case where the current waveform is instantaneously changed when the valve is closed as described above, there is a problem that the operating noise when the valve is closed becomes loud. On the contrary,
When circuit B is applied, the operating noise at the time of valve closing is reduced, but as shown in FIG. 13 (c), the valve closing time is long because the valve closing delay occurs with respect to the drive voltage. Become. Then, for the one that closes the valve instantly, as shown in FIG.
The flow rate increases by the amount indicated by the shaded area S in (d), and as shown in FIG. 14, the Duty ratio-flow rate characteristic becomes non-linear near the rising edge, so that the flow rate cannot be adjusted accurately. At this time, Ia in FIG. 13 (b) is the above-mentioned operation start current, Ib is the recovery start current, and Ix is the current required to fully lift the valve body 8, and this current is called the operation end current. Further, t indicates a closing delay time. In addition, in FIG.
The flow rate becomes zero until the ty ratio reaches the predetermined value Da because the operation start current Ia is not reached at a duty ratio lower than this.

Therefore, an object of the present invention is to accurately adjust the flow rate without increasing the operating noise when the valve is closed.

[0011]

To achieve the above object, the present invention provides a fluid passageway having a valve seat formed at an open end, and a valve body seated on the valve seat and closing the fluid passageway. ,
An urging member that urges the valve body in the valve closing direction, and an electromagnetic solenoid that urges the valve body in the valve opening direction against the urging force of the urging member and opens the fluid passage, The valve body has a pedestal that is seated on the valve seat, and a protrusion that is disposed in the fluid passage in a state where the pedestal is seated on the valve seat.

[0012]

According to the above construction, when the protrusion of the valve body is located in the fluid passage, the area of the fluid passage is reduced by this protrusion, and the flow rate at that time is
Will be reduced. That is, according to the present invention, since the fluid passage area is reduced before the valve body is seated and the flow rate when the valve is closed is reduced, it is necessary to instantaneously change the current when the valve is closed to prevent the flow rate from increasing. Therefore, the linearity in the rising characteristic of the duty-flow rate characteristic can be improved without increasing the operating noise.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The solenoid valve of the present invention will be described based on an embodiment applied as a purge control valve for a vehicle. Since the purge control system itself is not the subject of the present invention,
An outline thereof is shown in FIG. 1, and a detailed description will be omitted and simply described. That is, the purge control system is the fuel tank 100.
Fuel 101 generated in
Is to open and close the solenoid valve V to purge according to the engine load condition by using the intake negative pressure, and to prevent the vaporized fuel from being released to the atmosphere.

A solenoid valve according to an embodiment of the present invention will be described with reference to FIGS. 2 to 9. FIG. 2 shows a sectional view of the entire solenoid valve. Note that, in FIG. 2, the configuration other than the shape of the valve body, which is a feature of the present invention, is the same as that of the above-described conventional technique. In the figure, the same parts as those in the conventional technique are designated by the same reference numerals, and detailed description thereof will be omitted. As shown in FIGS. 1 and 2, the valve body 8 has a protrusion 8a and a pedestal 8b which is seated on the valve seat 11c. As shown in FIGS. 2 and 3, the protrusion 8a is formed integrally with the pedestal 8b.

The operation of the solenoid valve is as follows, as described in the section of the prior art, except for the operation by using the valve body with a protrusion. That is, when the electromagnetic solenoid 1 is energized, the movable body 7 is attracted to the fixed iron core 5 side. The movable body 7 starts to move when the attraction force that overcomes the spring 6 that biases the movable body 7 toward the valve seat 11c, that is, the operation start current is reached. When the movable body 7 is sucked, the valve body 8 and the valve seat 11c are separated from each other, the fluid passages 13, 14 and 15 are conducted, and the fluid flows.

On the contrary, by de-energizing the electromagnetic solenoid 1, the movable body 7 attracted to the fixed iron core 5 side is separated from the fixed iron core 5 by the urging force of the spring 6, and the cover 1
By closing the valve seat 11c formed in 1, the fluid passages 13 and 14 are shut off to stop the flow of fluid. The operation of providing the valve body 8 with the protrusion will be described in detail below. As shown in FIG. 4, this solenoid valve controls the lift amount and lift time of the valve body 8 by controlling the ratio of the ON time and the OFF time of the voltage waveform (a) based on the pulse signal to control the flow rate. To do. For example, a pulse signal of 10
When given in Hz, the ON time is 30 m at 30% ON time
s, the operation is repeated at the OFF time of 70 ms.

When the control is performed as described above, the delay in reaching the recovery start current Ib with respect to the voltage OFF signal is the closing delay of the valve body 8 and the flow rate is the amount shown by the shaded portions S1 and S2 in FIG. 4 (d). Too many. This excessive flow rate is constant regardless of the lift time when the valve body 8 closes from the full lift Lf. That is, the current O reaching the end-of-operation current Ix that can fully lift the valve body 8
Excessive flow rate is constant over N hours tf. However, in the ON time band where the operation end current Ix does not reach, a region where the valve body 8 does not reach the full lift Lf occurs,
The excessive flow rate S1 at this time is not constant but changes depending on the ON time. For example, in the region where the ON time is shorter than the above tf, the flow rate excess S1 increases until the ON time reaches tf. When this is made to correspond to the Duty ratio-flow rate characteristics of FIG. 5, the areas where the excessive flow rates S1 and S2 occur correspond to the areas of the C section and the D section, respectively. The portion C is called a stroke dead zone, and the latter portion D is called a full stroke area. Note that the above phenomenon is the cause of non-linearity near the rising edge in the duty ratio-flow rate characteristic in the conventional technique shown by the solid line in FIG.

Here, when the time until the valve end 8 reaches the operation end current Ix after reaching the full lift Lf is t2,
Obviously, t1 <t2 between the time t1 when the operation end current Ix is reached when the valve body 8 does not reach the full lift Lf.
The relationship is established. The present invention reduces the above S1 and S2 by providing the valve body 8 with the protrusion 8a. The amount of this decrease corresponding to the lift amount of the valve body 8 is indicated by the hatched area S3 in FIG. The solid line in FIG. 6 is the flow rate characteristic when the valve body 8 of the present invention is used, and the broken line is the flow rate characteristic when the conventional valve body is used, both of which are when driven by the circuit B. Is a characteristic of. When the valve body 8 of the present invention is used, the excessive flow rate can be reduced by the area S in FIG. Therefore, ON
The ratio of time, that is, the duty ratio-flow rate characteristic is the same characteristic as that when the conventional valve body is driven by using the circuit A as shown in FIG. Note that the horizontal axis in FIG. 8 indicates the ratio of ON time (Duty ratio = Duty ratio, 0 to 100).
%), The vertical axis represents the average flow rate at each ON time, the solid line is the flow rate characteristic when the valve body 8 of the present invention is used, and the broken line is the flow rate characteristic when the conventional valve body is used. Circuit B together
It is the characteristic when driven by.

As described above, in the pulse control solenoid valve of the present invention, the tip of the valve body 8 is changed from the conventional shape shown in FIG. 10 to the throttle shape shown in FIGS. 2 and 3. Fig. 6 shows the flow rate characteristics in the low lift region based on the flow rate characteristics with respect to the valve lift without changing the flow rate when fully opened.
By making it non-linear as shown by the solid line in FIG. 3, the average flow rate for the same lift and lift time is reduced, and as a result, the excessive flow rate due to the valve body closing delay is reduced.

The above-mentioned valve body is made of rubber or the like and has a protruding portion 18
Although the pedestal 18 and the pedestal 19 are integrally molded, the projection 18 and the pedestal 19 may be formed separately and combined as shown in FIG. 9, and the material of the projection 18 and the pedestal 19 at that time is a rubber material. Not limited to these, other solid materials such as resin and metal may be used, and they may be arbitrarily combined.
Furthermore, as a method of connecting the protrusion 18 and the pedestal 19, insertion, press fitting, adhesion, or the like can be applied.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a purge control system for a vehicle.

FIG. 2 is a sectional view showing an embodiment of a solenoid valve of the present invention.

FIG. 3 is a perspective view showing a valve body of the above embodiment.

FIG. 4 is a characteristic diagram used to explain the operation of the solenoid valve, in which (a) shows voltage, (b) shows current, (c) shows valve lift, and (d) shows flow characteristics. It is a characteristic diagram.

FIG. 5 is a characteristic diagram showing a characteristic of a flow rate with respect to a duty ratio.

FIG. 6 is a characteristic diagram showing a characteristic of a flow rate with respect to a valve lift amount.

FIG. 7 is a characteristic diagram used for explaining the effect of the present invention,
(A) is voltage, (b) is current, (c) is valve lift,
(D) is a characteristic diagram showing each characteristic of the flow rate.

FIG. 8 is a characteristic diagram used for explaining the effect of the present invention,
It is a characteristic view which shows the characteristic of the flow volume with respect to a duty ratio.

FIG. 9 is a cross-sectional view showing another example of the valve body.

FIG. 10 is a cross-sectional view showing a conventional solenoid valve.

FIG. 11 is a circuit diagram for driving.

FIG. 12 is a circuit diagram for driving.

FIG. 13 is a characteristic diagram used to explain the operation of a conventional solenoid valve, where (a) is voltage, (b) is current, (c) is valve lift, and (d) is flow rate characteristics. It is a characteristic view to show.

FIG. 14 is a characteristic diagram showing a characteristic of a flow rate with respect to a duty ratio of a conventional solenoid valve.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electromagnetic solenoid 6 Spring 8 Valve body 11c Valve seat 13,14,15 Fluid passage 18 Protrusion 19 Base

Claims (1)

[Claims] 1. A fluid passageway having a valve seat formed at an open end, and a valve body seated on the valve seat and closing the fluid passageway,
An urging member that urges the valve body in the valve closing direction, and an electromagnetic solenoid that urges the valve body in the valve opening direction against the urging force of the urging member and opens the fluid passage, The solenoid valve is characterized in that the valve body has a base seated on the valve seat, and a protrusion arranged in the fluid passageway in a state where the seat seats on the valve seat.