JPS6283573A - Switching valve device - Google Patents

Abstract

PURPOSE:To reduces the occurrence of hysteresis, by a method wherein a plunger return spring is disposed between a plunger and an inner core to energize the plunger in a direction in which the plunger is separated from the inner core, and the spring is so positioned as to exert an energizing force directly on a valve body. CONSTITUTION:A plunger return spring 25, having its one end locked to an inner core 20, is disposed on a shaft 24 extended between the inner core 20 of a switching valve device 10 and a plunger 23. During energization of a solenoid coil 21, the plunger 23 is energized in a direction extending against attraction to the inner core 20. A valve body 16 is directly energized in a closed and an opening direction through the force of first and second spings 27 and 17, respectively. This enables decrease of the weight of a moving part and slide resistance through sensing of temperature and permits decrease of the occurrence of hysteresis.

Description

DETAILED DESCRIPTION OF THE INVENTION OBJECTS OF THE INVENTION (Industrial Field of Application) The present invention relates to a switching valve device, and more particularly, to a switching valve device that controls switching of a fluid passageway in response to both an input current signal and an ambient temperature. This invention relates to a switching valve device that controls the opening and closing of a switching valve.

In particular, the device of the present invention is a so-called carburetor outer vent device for preventing fuel gas generated in the carburetor float chamber from being released into the atmosphere in an automobile engine.

(Prior art) A conventional device of this type is disclosed in Japanese Patent Application Laid-Open No. 60-60382.
There was one disclosed in the Japanese Patent Publication No. 2003-110003 and shown in FIG. This conventional device 30 includes an outer yoke 40 made of a magnetic material and fixed to the right end of the body 31 in the figure. An inner core 43 disposed on the central axis within the outer yoke. The inner core 43
A bobbin 44 made of a non-magnetic material is inserted and fixed on the outer periphery of the bobbin 44.
A solenoid coil 47 wound on the bobbin. a plunger 49 disposed coaxially with and opposite the inner core 43 so as to be movable in the axial direction; An electromagnetic mechanism is formed by a shaft 51 having one end fixed to the plunger and the other end facing the valve body 36, and the valve body 36 being made of a shape memory alloy and expanding into a memorized shape at high temperatures in the valve opening direction. a second spring 54 . Valve body 3
6 is provided with a temperature-sensing function mechanism formed by a first spring 37 that biases the valve in the valve-closing direction.

When the ignition switch is turned on, the solenoid coil 47 is energized regardless of the temperature change in the capretor float chamber, the plunger 49 is attracted to the inner core 43, and the shaft 51 fixed to the plunger 49 pulls the second spring 54. The valve body 36 contracts and moves to the right in the figure.
Since the valve body 36 is separated from the valve body 36, the valve body 36 comes into contact with the seat member 38 due to the biasing force of the first spring 37, thereby blocking communication between the inlet port 32 and the outlet port 33.

When the ignition switch is off (OF The body 36 is biased in the opening direction.

At this time, since the load is set to be larger than the first spring 37, the valve body 36 is separated from the seat member 38, and the inlet port 32 and the outlet port 33 are communicated with each other.

When the caplet float chamber temperature is low, the valve body 36 and the valve body 3 are biased by the biasing force on the right side in the figure of the first spring 37 whose load is set larger than that of the second spring 54.
6, the shaft 51 and plunger 49 are moved until the second spring 54 is contracted and the valve body 36 comes into contact with the seat member 38. Communication between the inlet port 32 and the outlet port 33 is thereby cut off.

(Problems to be Solved by the Invention) In the conventional device shown in FIG. 2 described above, when the ignition switch is OFF, the valve body moves from the valve open position due to a temperature change in the caplet float chamber. When moving to the valve closing position, the force of the second spring that biases the valve element in the valve opening direction is applied to the valve element via the shaft.
In order to move the valve body to the closed position by the biasing force of the spring, the shaft and plunger must also move together with the valve body, and as shown in Figure 3, there is a large hysteresis in the valve opening and closing temperatures. (approximately 10°C). As a result, a problem occurred in that the engine restartability after being left unused for a long period of time deteriorated.

Therefore, the technical object of the present invention is to reduce the hysteresis by reducing the weight of the movable part and the sliding resistance due to temperature sensing.

[Structure of the invention]

(Means to solve the problem) The technical measures taken to solve the above technical problem are:
A plunger return spring is disposed between the plunger and the inner core to urge the plunger in a direction away from the inner core. The second springs are arranged so that their biasing forces act directly on the valve body.

(Function) When the solenoid coil is de-energized, the plunger and shaft are returned to the direction opposite to the suction direction to the inner core by the plunger return spring provided between the plunger and the inner core, and the shaft that was in contact with the valve body is Move away from the valve body. Thereby, the valve body can be moved into the first position without being interfered with by the shaft. Only by balancing the biasing force of the second spring, the caplet valve moves to the open and closed positions in accordance with the temperature of the caplet float chamber independently of the shaft.

As a result of the above action, the only movable member for temperature sensing is the valve body, and since there are no sliding parts, there is no sliding resistance, making it possible to reduce the hysteresis of the valve opening and closing temperatures. be.

(Example) Hereinafter, an example embodying the present invention will be described based on FIG. 1.

A body 11 of a switching valve device 10 according to the present invention is provided with an inlet port 12 communicating with a carburetor float chamber and an outlet port 13 communicating with a canister in a carburetor outer vent control device. Both bows) 12.13 communicate with each other via a fluid passage 14.15 formed in the body, and a valve body 16 is disposed between the passages 14.15. -12.13 is controlled to open and close.

The left end of the body 11 in the figure is made of a magnetic material.

An outer peripheral yoke 18 and a yoke plate 19 are fixed, and an inner core 20 is disposed on a central axis within the outer peripheral yoke 18 and yoke plate 19. A bobbin 22 made of a non-magnetic material is inserted and fixed on the outer periphery of the inner core 20, and a solenoid coil 21 is wound on the bobbin 22. Both ends of the solenoid coil 21 are appropriately connected to a power source via a terminal 26. A plunger 23 is arranged between the inner side of the left end surface of the bobbin 22 and the left end surface of the inner core 20 so as to be displaceable in the axial direction, coaxially with the inner core 20 and facing the core 20. be done. A shaft 24, one end of which is fixed to the plunger 23, passes through the hollow portion of the inner core 20, and the other end protrudes from the right end of the inner core 20 in the drawing. A plunger return spring 25 is mounted on the shaft 24 between the inner core 20 and the plunger 23 with one end connected to the inner core 2.
0, and urges the plunger 23 in a direction against attraction to the inner core 20 when the solenoid coil 21 is energized.

A first spring 27, one end of which is engaged with the yoke plate 19, biases the valve body 16 directly in the right direction in the figure, that is, in the valve closing direction where it comes into contact with the valve seat surface 11a. Further, the second spring 17 whose one end is locked to the body 11 urges the valve body 16 in the valve opening direction against the urging force of the first spring 27 . The second spring 17 is made of a shape memory alloy, and when the temperature is low, the load of the first spring 27 is set to be larger than that of the second spring 17, and the valve body 16 is held at the valve closing position. At high temperatures (approximately 50"C or higher), the second spring 17 is configured to expand to a previously memorized shape, so at this time the second spring 17
The load of the first spring 27 is set to be greater than that of the first spring 27, and the valve body 16 is held in the open position.

Note that by forming a ring-shaped yoke plate 19 from a heat insulating material and fixing it on the inner core so as to be adjacent to the body 11 and the bobbin 22, the solenoid coil 21 and the second
The spring 17 is thermally isolated, and the influence of heat generated by the coil 21 is prevented from reaching the second spark ring 17.

Next, the operation of the above configuration will be explained. First, when the ignition switch is OFF and the solenoid coil 21 is not energized, the valve body 16 moves due to the balance of the urging forces of the first spring 27 and the second spring 17. When the temperature of the caplet float chamber is low, the rightward biasing force of the first spring 27, whose load is set larger than that of the second spring 17, causes the valve body 16 to
is directly biased in the valve closing direction by the first spring 27, comes into contact with the valve seat surface 11a of the body 11, and is held in the valve closing position. Therefore, since both ports 12 and 13 are cut off, communication between the canister and the carburetor float chamber is closed.

Further, when the temperature of the caplet float chamber is high (506C or higher), the second spring 17 expands to a previously memorized shape, and the load is greater than that of the first spring 27. Due to the biasing force, the valve body 16 is separated from the valve seat surface 11a and held in the valve open position, resulting in communication between the side ports 12 and 13.

At this time, even if the temperature is low or high, plunger 2
3 and the shaft 24 are positioned on the left side in the figure by the plunger return spring 25, and the protrusion 24a of the shaft 24 does not contact the valve body 16, so the only movable part is the valve body 16, and the valve body 16 is 1st. Since it is held by the second spring 27.17, the sliding resistance is completely equal to 1°. Therefore, as shown by the dashed line in FIG. 3, the hysteresis is greatly reduced (about 5° C.).

Next, when the ignition switch is turned on and the solenoid coil 21 is energized, the excitation action of the coil 21 causes the inner core 20 and the magnetic outer yoke 18. A magnetic circuit is formed between the yoke plates 19, and a plunger 23 located in the magnetic circuit is attracted to the inner core 20. As a result, the shaft 24 whose one end is fixed to the plunger 23 moves to the right in the figure together with the plunger 23, so that the protrusion 24a comes into contact with the valve body 16, causing the valve body 1
6 is pressed against the seat surface 11a of the body 11 and held in the closed position. In this way, when the coil 21 is energized, the valve body 16 is held in the closed position regardless of the temperature change in the carburetor float chamber, and the ports 12 and 13 are cut off, so communication between the carburetor float chamber and the canister is closed. It will be done.

〔Effect of the invention〕

In the present invention, by reducing the weight and sliding resistance of the moving parts by temperature sensing, the hysteresis of the switching temperature between valve opening and closing can be reduced and suppressed, which reduces engine startability after being left unused for a long time. There isn't.

Furthermore, since the only movable part that detects temperature is the valve body, the load on the spring made of shape memory alloy is increased. That is, there is no need to increase the amount of strain in the shape memory alloy, and the durability of the shape memory alloy spring is improved.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of a switching valve device according to the present invention, FIG. 2 is a sectional view showing a conventional switching valve device, and FIG. 3 is a sectional view of the switching valve shown in FIGS. 1 and 2. FIG. 3 is a characteristic diagram of the temperature hysteresis of the opening/closing valve of the device.

Claims (1)

[Claims] A body including an inlet port and an outlet port, a fluid passage formed in the body and communicating between the two ports, a valve body for controlling opening and closing of the fluid passage, and an outer periphery made of a magnetic material fixed to one end of the body. a yoke, an inner core disposed on a shaft within the outer yoke; a bobbin made of a non-magnetic material inserted and fixed on the outer periphery of the inner core; wound on the bobbin to form a magnetic circuit together with the outer yoke and the inner core; a solenoid coil, a plunger located in the magnetic circuit, coaxially disposed on one end surface of the inner core, and attracted to the inner core when the solenoid coil is energized; one end fixed to the plunger; a shaft whose other end abuts the valve body and holds it in the closed position when suction is applied to the inner core; a first spring which biases the valve body in the closing direction; In the switching valve device, the switching valve device has a second spring that biases the body in the opening direction, the second spring is made of a shape memory alloy, and expands to a memorized shape at high temperatures, wherein the plunger and the inner core are connected to each other. A switching valve, wherein a plunger return spring is disposed in between to bias the plunger in a direction away from the inner core, and the first and second springs are disposed so that biasing forces act directly on the valve body. Device.