ANTI-ICE VALVE

Abstract

The invention relates to a solenoid valve or an aircraft anti-ice system. The solenoid valve comprises: a solenoid; a yoke arranged to be actuated by the solenoid between a first yoke position and a second yoke position; and a plunger arranged to be actuated between a first plunger position and a second plunger position to control fluid flow between fluid channels. The plunger comprises a magnetic element proximate the yoke. There is a gap between the plunger and the yoke when the yoke is in the second yoke position, so that magnetic force acting on the magnetic element of the plunger urges the plunger to the second plunger position.

Claims

1. A solenoid valve for an aircraft anti-ice system comprising: a solenoid; a yoke arranged to be actuated by the solenoid between a first yoke position and a second yoke position; and a plunger arranged to be actuated between a first plunger position and a second plunger position to control fluid flow between fluid channels; wherein the plunger comprises a magnetic element proximate the yoke; and wherein there is a gap between the plunger and the yoke when the yoke is in the second yoke position, so that magnetic force acting on the magnetic element of the plunger urges the plunger to the second plunger position.

2. A solenoid valve as claimed in claim 1, comprising a biasing mechanism arranged to urge the yoke to the first yoke position.

3. A solenoid valve as claimed in claim 1 wherein the yoke urges the plunger to the first plunger position when the yoke is in the first yoke position.

4. A solenoid valve as claimed in claim 1, wherein the solenoid is operable to make the magnetic element of the plunger magnetic.

5. A solenoid valve as claimed in claim 1 wherein the yoke contacts the solenoid in the second yoke position.

6. A solenoid valve as claimed in claim 5, wherein the solenoid comprises opposed, angled faces arranged to contact the yoke when the yoke is in the second yoke position.

7. A solenoid valve as claimed in claim 1 wherein the magnetic force between the plunger and the yoke is less than the magnetic force between the yoke and solenoid.

8. A solenoid valve as claimed in claim 1, wherein the yoke comprises a socket arranged to receive at least a portion of the plunger.

9. A solenoid valve as claimed in claim 1, wherein the plunger comprises a fluid control portion disposed within a pneumatic portion of the solenoid valve, and comprises an elongate bridge portion between the fluid control portion and the yoke.

10. A solenoid valve as claimed in claim 1 wherein the solenoid valve is arranged so that the yoke is actuated to the second yoke position when the solenoid is energised.

11. A solenoid valve as claimed in claim 1, wherein when the solenoid is energised the magnetic element of the plunger is attracted to the yoke with enough force to maintain the plunger in the second plunger position against vibrations up to 20 g acceleration.

12. A solenoid valve as claimed in claim 1, wherein in the first plunger position, the plunger allows fluid communication between a first fluid channel and a second fluid channel, and wherein in the second plunger position the plunger allows fluid communication between the first fluid channel and a third fluid channel.

13. An anti-ice system for an aircraft comprising: the solenoid valve of claim 1.

14. A method of controlling fluid flow between fluid channels of an aircraft anti-ice system, the method comprising: actuating a plunger between a first plunger position and a second plunger position; and maintaining the plunger in the second plunger position using magnetic force acting on a magnetic element on the plunger.

15. A method as claimed in claim 14, wherein the solenoid valve includes: a solenoid; a yoke arranged to be actuated by the solenoid between a first yoke position and a second yoke position; and a plunger arranged to be actuated between a first plunger position and a second plunger position to control fluid flow between fluid channels; wherein the plunger comprises a magnetic element proximate the yoke; and wherein there is a gap between the plunger and the yoke when the yoke is in the second yoke position, so that magnetic force acting on the magnetic element of the plunger urges the plunger to the second plunger position

Description

BRIEF DESCIPTION OF THE DRAWINGS

[0035] Certain preferred embodiments of the invention are described in detail below by way of example only and with reference to the drawings in which:

[0036] FIG. 1 shows a cross-section of a solenoid valve;

[0037] FIG. 2 shows a cross-section of the solenoid valve of FIG. 1 in perspective;

[0038] FIG. 3A shows a schematic of a portion of the solenoid valve of FIGS. 1 and 2 in a first configuration; and

[0039] FIG. 3B shows the schematic of FIG. 3A in a second configuration.

DESCRIPTION

[0040] FIG. 1 shows a cross-section of a solenoid valve 100, comprising a solenoid 110, a yoke 120, and a plunger 130. The plunger 130 comprises a magnetic element in the form of a magnetic cap 132 on the end of the plunger 130 proximate the yoke 120.

[0041] The solenoid valve 100 comprises a pneumatic portion 140, in which is defined a plurality of fluid channels 142, 144, 146. The plunger 130 comprises a fluid control portion in the form of a ball-head 134 disposed on a distal end of the plunger 130, opposite the magnetic cap 132. The plunger 130 is actuated to control fluid communication between the fluid channels 142, 144, 146 by the ball had 134 opening and closing those channels. The plunger 130 also comprises an elongate bridge portion 136 separating the opposite ends of the plunger 130 i.e. separating the magnetic cap 132 and the ball head 134. The plunger 130 is therefore disposed partially within the pneumatic portion 140 of the valve 100.

[0042] The yoke 120 is movable between a first yoke position (leftmost in the orientation of FIG. 1) and a second yoke position (rightmost in the orientation of FIG. 1). In FIG. 1, the yoke 120 is shown in the first yoke position. A proximal end of the plunger 130 comprising the magnetic cap 132 is disposed within a socket 124 of the yoke 120 and bears against a surface of the yoke 120 so that when the yoke 120 is in the first yoke position the plunger 130 is in a first plunger position (leftmost in the orientation of FIG. 1). A biasing mechanism in the form of a spring 160 is provided to bias the yoke 120 to the first yoke position, and thereby also to bias the plunger 130 to the first plunger position.

[0043] FIG. 2 shows a cross-section of the solenoid valve 100 of FIG. 1 in perspective. The yoke 120 is shown in the first yoke position and the plunger 130 is shown in the first plunger position.

[0044] FIGS. 3A and 3B show a schematic of the operation of the solenoid valve 100. FIG. 3A shows the yoke 120 in the first yoke position and the plunger 130 in the first plunger position when the solenoid 110 is not energised. The spring 160 urges the yoke 120 towards the first yoke position, and the yoke 120 thereby bears against the magnetic cap 132 at the proximal end of the plunger 130 and urges the plunger 130 the first plunger position.

[0045] In the first plunger position, the ball head 134 of the plunger 130 is spaced from a first fluid channel 142 thereby allowing fluid communication between the first fluid channel 142 and a second fluid channel 144. Force from the spring 160 keeps the ball head 134 seated in firm contact with an opening of a third fluid channel 146, thereby closing the third fluid channel 146 and preventing fluid communication between the third fluid channel 146 and either or both of the first fluid channel 142 or the second fluid channel 144.

[0046] FIG. 3B shows the yoke 120 in the second yoke position and the plunger 130 in a second plunger position. To move the solenoid valve 100 to its second configuration, the solenoid 110 is energised and the yoke 120 is moved by magnetic force from the solenoid 110 to the second yoke position (rightmost in the orientation shown in FIG. 3B). Magnetic force from the solenoid 110 acting on the yoke 120 is indicated schematically by the arrows 114 in FIG. 3B. Initially, the magnetic cap 132 of the plunger 130 is held against the yoke 120 by magnetic attraction thereto. However, once the ball head 134 contacts in opening of the first fluid channel 142 further movement of the plunger 130 is prevented. The solenoid 110 applies a greater magnetic force to the yoke 120 than exists between the yoke 120 and the magnetic cap 132, and the yoke 120 is therefore pulled away from the magnetic cap 132 and a gap 150 is formed between the yoke 120 and the magnetic cap 132 of the plunger 130. When the yoke 120 is in the second yoke position, the magnetic cap 132 of the plunger 130 is attracted to the yoke 120 by magnetic force and is therefore urged to and held in the second plunger position.

[0047] In the second plunger position the ball head 134 of the plunger 130 seals the opening of the first fluid channel 142, thereby preventing fluid communication between the first fluid channel 142 and either or both of the second fluid channel 144 and the third fluid channel 146. Movement of the plunger 130 to the second plunger position opens the third fluid channel 146 so that it may fluidly communicate with the second fluid channel 144. Therefore movement of the plunger 130 between the first plunger position and the second plunger position controls fluid communication between the fluid channels 142, 144, 146 within the solenoid valve 100.

[0048] The yoke 120 moves a greater distance between the first yoke position and the second yoke position than the plunger 130 moves between the first plunger position and the second plunger position. The gap 150 is therefore created between the plunger 130 and the yoke 120. Magnetic force acting on the magnetic cap 132 of the plunger 130 urges the plunger 130 into the gap 150, though movement of the plunger 130 into the gap 150 is prevented by the ball head 134 held against the opening of the first fluid channel 142.

[0049] The solenoid 110 may exert a magnetic force on the magnetic cap 132 as well as on the yoke 120, thereby helping to urge the magnetic cap 132 to move the plunger 130 to the second plunger position. The arrows 116 in FIG. 3B schematically show the magnetic force from the solenoid 110 acting on the magnetic cap 132.

[0050] The magnetic cap 132 may or may not be a permanent magnet, and it may therefore be a magnetically susceptible element which becomes magnetic only in the presence of an electromagnetic field from the solenoid 110. Alternatively, the magnetic element may be a permanent magnet and may permanently be attracted to the yoke 120.

[0051] The yoke 120 comprises the socket 124 into which the proximal end of the plunger 130 is inserted. The magnetic cap 132 is disposed partially within the socket 124 of the yoke 120 in both the first and second configurations of the solenoid valve 100 (i.e. when the plunger 130 is in both the first plunger position and the second plunger position). The gap 150 is created within the socket 124 of the yoke 120 when the yoke 120 is in the second yoke position. The plunger 130 is freely movable within the socket 124 of the yoke 120 but is not mechanically coupled to the yoke 120 so that small movements of the plunger 130 relative to the yoke 120 are possible. The plunger 130 may therefore move to firmly seat the ball head 134 in the opening of the first fluid channel 142 to close that channel.

[0052] The gap 150 also serves to insulate the yoke 120 and the solenoid 110 from the extreme temperatures experienced by the plunger 130. Mass fluid flow through the fluid channels 142, 144, 146 can reach temperatures of around 650 C. or higher and it is well known that high temperatures cause degradation of electrical and/or magnetic components. The free movement of the plunger 130 in the socket 124 of the yoke 120, and the gap 150, help prevent conductive heat transfer from the plunger 130 to the electronic components (e.g. the yoke 120 and the solenoid 110) of the solenoid valve 100, thereby improving durability and longevity of the solenoid valve 100. This contrasts with solenoid valves in which the plunger is mechanically and rigidly coupled to the yoke.

[0053] The gap 150 is arranged so that the plunger 130 is constantly urged into the second plunger position e.g. at the proximate end of the plunger 130 furthest from the pneumatic portion 140. The gap 150 is therefore arranged in the direction in which the plunger 130 is urged to move by magnetic attraction to the yoke 120. Some surfaces of the plunger 130 may be adjacent surfaces of the yoke 120 in both the first and second configurations of the solenoid valve 100 e.g. the sides of the plunger 130 within the socket 124 of the yoke 120.

[0054] From FIGS. 3A and 3B it can be seen that the plunger 130 is held in the second plunger position by magnetic force acting on the magnetic cap 132 pulling the plunger 130 towards the solenoid 110. When the solenoid is de-energised the spring 160 urges the yoke 120 and the plunger 130 to their respective first positions, and thereby pushes the ball head 134 of the plunger 130 against the opening of the third fluid channel 146 in order to close that channel.

[0055] The solenoid 110 comprises opposed angled faces 112 (e.g. forming a recessing with the solenoid) arranged to contact corresponding opposed faces 122 of the yoke 120 when the yoke 120 is in the second yoke position. The faces 112 and 122 are angled with respect to the direction of movement of the yoke 120. Contact between the solenoid 110 and the yoke 120 provides a good pathway for magnetic flux so that the solenoid 110 may be operated in a steady-state using a relatively low current, and the yoke 120 and plunger 130 may be held in their respective second positions efficiently. This contrasts with solenoid valves in which e.g. the solenoid and the yoke are separated in all configurations. The transmission of magnetic flux through the yoke 120 also increases the magnetic force experienced by the magnetic cap 132. The angled faces 112 and 122 increase the contact surface area between the solenoid 110 and the yoke 120, increasing the energy efficiency of the solenoid valve 100. The angled faces 112 and 122 of the solenoid 110 yoke 120 also work together with the free movement of the plunger 130 in the socket 124 to allow small position adjustments to help correctly locate and securely seat the ball head 134 of the plunger 130 in the second plunger position.

[0056] The solenoid valve 100 is configured for use in extreme environments. The solenoid valve 100 may be exposed to high vibrational accelerations (e.g. 20 g or more), high pneumatic mass flow temperatures (e.g. about 650 C. or more), and or high environmental temperatures (e.g. 150 C. or more). As such, it is necessary for the solenoid valve 100 to be extremely durable and highly robust. The solenoid valve 100 has a simple construction on the pneumatic side 140, which side is predominantly exposed the highest temperatures due to the high temperature mass flow therein. For example, the solenoid valve 100 does not include a spring or the like on the pneumatic side 140 of the solenoid valve 100 to return the plunger 130 to a preferred position, which springs are notoriously prone to failure e.g. because of exposure to extreme temperatures. As such the solenoid valve 100 is less susceptible to component wear, fatigue and/or failure than other valves.

[0057] The design of the solenoid valve herein ensures a mutual force is continuously shared between the plunger 130 and the yoke 120. The design avoids any rigid mechanical contact between the parts. When coils of the solenoid 110 are de-energized, the spring 160 compresses the yoke 120 and the plunger 130. When the solenoid is in an energized state, the magnetic flux ensures a pulling force is directly transferred to the plunger 130.