JPH0318690Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a purge valve that controls when vaporized fuel adsorbed on a carbon canister is discharged into an intake pipe of an internal combustion engine.

(Prior Art) A carbon canister is used in which fuel vapor evaporating from a gasoline tank or the like of an internal combustion engine is adsorbed onto an adsorbent such as activated carbon, and then released into an intake pipe during engine operation. An example is shown in FIG. Fuel vapor evaporated from the gasoline tank 50 is transferred to a container 32 containing the adsorbent 33 of the carbon canister 30.
through the introduction pipe 31 to be adsorbed. In the carbon canister 30, the purge valve 34 opens during engine operation, and the atmosphere is introduced from the air intake port 32a of the container 32 to desorb the adsorbed fuel.
The fuel vapor is released from the engine to the downstream side of the throttle valve 52 of the intake pipe 51 of the engine. A conventional purge valve 34 has a valve body 40 fixed to a diaphragm 39 that covers a pipe end opening 35a of a discharge pipe 35, as shown in FIG. The purge valve 34 is divided by a diaphragm 39 into an upper negative pressure chamber 41 and a lower purge chamber 45 communicating with the container 32. A coil spring 42 is disposed inside the negative pressure chamber 41, and a coil spring 42 is disposed in the negative pressure chamber 41. The body 40 presses and closes the opening 35a of the discharge pipe in the purge chamber 45. Negative pressure chamber 41 communicates with the upstream side of throttle valve 52. Also coil spring 4
2, the starting and ending ends of the coil are 42 in Figure 5 A and B.
They are installed at diametrically opposite positions like a and 42b.

(Problems to be Solved by the Invention) In the conventional purge valve 34 as described above, the throttle valve 52 is closed during idle operation, so that no negative pressure acts on the negative pressure chamber 41 and the negative pressure chamber 41 is closed. On the other hand, an intake pipe negative pressure of about 500 to 600 mmHg is acting inside the discharge pipe 35. When the throttle valve 52 opens and the negative pressure in the intake pipe reaches the negative pressure chamber 41, the purge valve 34 suddenly opens, and the negative pressure in the discharge pipe 35 impulsively propagates to the purge chamber 45 and further inside the container 32. It extends to. At this time, the valve body 40 separates from the opening 35a all at once, so air impact noise (air bones) is generated and accompanied by vibrations. Further, in the fully open position, the valve body 40 collides with the stopper 44 to generate a collision sound (solid bone) and vibration.

(Means for solving the problem) The purge valve of this invention is designed so that the starting and ending positions of the coil of the coil spring are set so that their center angles are within 90° when projected in the axial direction of the coil. The spring force is stronger on one side of the circumference including the starting and ending ends than on the other side, so that an uneven load is applied to the valve body.

(Function) In the purge valve of this invention, the pressing force of the coil spring acts as an unbalanced load on the valve body, so negative pressure acts on the negative pressure chamber, causing the diaphragm to rise and the valve body to move to the end of the discharge pipe. When leaving the opening, the side with the weaker load, where the starting and ending ends of the coil spring are not located, rises first without opening all at once. Therefore, as the valve body tilts and peels off, the opening area gradually expands, so the negative pressure in the discharge pipe begins to propagate to the purge chamber from the constricted passage, generating air impact noise and vibrations. I won't let you.
Also, since the valve does not open all at once, the valve opening speed is slowed down.
The speed at which the valve body collides with the stopper when the valve body rises to the fully open position also decreases. Therefore, collision noise and vibration are reduced.

The above action changes the starting and ending positions of the coil spring to the center angle at the projected position.
This is because they are brought closer to each other within 90 degrees, preferably coincident, to produce an unbalanced load. This was discovered experimentally, but
This is thought to be due to the fact that the center part of the wire of the coil spring is more easily distorted by twisting or bending.

(Example) An example of this invention will be described. In the purge valve 1 shown in FIG. 1, the inside of the valve casing 2 is divided into an upper negative pressure chamber 5 and a lower purge chamber 6 by a diaphragm 4 to which a plate-shaped valve body 3 is fixed. A discharge pipe 7 is provided, with its pipe end opening 7a facing the valve body 3. The negative pressure chamber 5 communicates with the upstream side of the throttle valve 52 (see FIG. 3) of the engine intake pipe, and a coil spring 8 is disposed therein to press the valve body 3 toward the opening 7a via a retainer 9. . coil spring 8
is the position where the starting end and the ending end 8a, 8b of the coil are projected in the axial direction as shown in Fig. 2 A and B, and the central angle α is
It is set to be ≦90°. Purge valve 1
Similar to the purge valve 34 in FIG. 3, the purge chamber 6 communicates with the container 32 containing the adsorbent 33, and the other end of the discharge pipe 7 is connected to the downstream side of the throttle valve 52 of the intake pipe 51.

When the engine is operated, intake pipe negative pressure is transmitted to the discharge pipe 7. When the throttle valve 52 opens, negative pressure is generated in the negative pressure chamber 5, overcoming the pressing force of the coil spring 8 and causing the diaphragm 4 to rise. At this time, the negative pressure acts evenly on the diaphragm 4, but the coil spring 8 has an unbalanced load on the circumference, and the pressing force on the side where there is no starting end or end is weak, so the valve body 3 tilts first from that side. It leaves the opening 7a.
This allows the valve to open at a slower speed, and air impact noise and vibrations do not occur when the valve is opened. Also, when the cylinder rises and collides with the stopper 10 on the upper surface of the negative pressure chamber, the collision noise and vibrations are reduced.

The purge valve 1 illustrated above is attached integrally to the adsorbent container of the carbon canister, but it is also separate from the adsorbent container, and the purge chamber and the adsorbent container are connected by a pipe. It may be connected. The effect of this is similar to the previous example.

(Effect of the invention) In the purge valve of this invention, the coil spring that presses the valve body has an unbalanced load on its circumference, so when opening the valve, the valve body does not tilt and open all at once. . Therefore, there is no air impact noise or vibration when the valve is opened, and the impact noise or vibration that occurs when the valve hits the stopper when the valve is fully opened is also alleviated.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing an embodiment of this invention, Figure 2 is a sectional view showing an embodiment of this invention.
Figure A is a plan view of a coil spring in an embodiment of this invention, and Figure 2B is a side view thereof. Third
The figure shows the installed state of the purge valve, Figure 4 is a sectional view showing the conventional purge valve, and Figure 5 A is a plan view of the coil spring of the conventional purge valve.
FIG. 5B is a side view thereof. 3...Valve body, 4...Diaphragm, 5...Negative pressure chamber, 6...Purge chamber, 7...Discharge pipe, 7a...
...Opening, 8...Coil spring, 30...Canister, 33...Adsorbent.

Claims (1)

[Scope of utility model registration request] The inside of the casing is divided into a negative pressure chamber and a purge chamber by a diaphragm, and a discharge pipe is provided in the purge chamber that communicates with the container containing the adsorbent. In a carbon canister purge valve in which a disposed coil spring presses a valve body fixed to a diaphragm to close the pipe end opening, the positions of the coil start and end of the coil spring are aligned in the axial direction of the coil. When projected onto , its central angle is
A purge valve characterized by being set within 90°.