FOREIGN PRIORITY

This application claims priority to European Patent Application No. 19305588.6, filed May 9, 2019, and all the benefits accruing therefrom under 35 U.S.C. § 119, the contents of which in its entirety are herein incorporated by reference.

BACKGROUND

The present disclosure relates to a solenoid valve and a method for making a solenoid valve.

Solenoid valves are commonly used in fluid flow applications such as refrigeration circuits. Solenoid valves typically contain a solenoid portion that contains a coil of wire, and a valve portion that is connected to the solenoid portion. A pin part of the valve portion extends inside the coil of wire. Controlling the magnetic field generated by passing a current though the coil allows control of the valve portion. Often the valve portion is fluidly isolated from the solenoid portion. The magnetic field from the solenoid penetrates into the pin part and is used to move internal parts within the pin, wherein said parts are for controlling fluid flow through the valve portion. In one known solenoid valve, described in detail below, the pin part is held in the solenoid portion by a resilient locking device that releasably holds the pin. The solenoid portion and valve portion must be pulled apart with some force (in one example, 120N of force) to release the grip of the resilient locking device upon the pin and thereby separate the two portions.

One such solenoid valve is called the “Fast Lock Coil” manufactured by Castel. Other solenoid valves (with different locking mechanisms for holding the parts together) are disclosed in U.S. Pat. Nos. 5,895,026 and 9,982,797.

Refrigeration circuits, particularly refrigeration circuits installed on vehicles, may often be subject to vibrations. For example, the refrigeration unit of a refrigerated truck will be subject to vibrations generated while driving along a road. Sudden bumps (e.g. from hitting a pothole or a rock) may provide sufficient force to pull the solenoid portion apart from the valve portion of a solenoid valve. This could potentially not damage either part, but still cause the solenoid valve to cease functioning properly if the pin is thus improperly positioned with respect to the solenoid's magnetic field, such that the solenoid no longer properly controls the internal parts of the valve portion.

SUMMARY

According to a first aspect, the present disclosure provides a solenoid valve comprising: a valve portion having a pin, the pin having a groove; a solenoid portion having an aperture configured to receive the pin; and a resilient locking device in the aperture, the resilient locking device configured to engage the groove when the pin has been inserted into the aperture to releasably hold the pin in the aperture; and characterised by a movable cap having a first and second position wherein, in the first position the movable cap does not abut the resilient locking device and wherein, in the second position, the movable cap abuts the resilient locking device so as to prevent movement of the resilient locking device out of the groove.

The movable cap may ensure that the resilient locking device cannot lose its grip on the groove of the pin. Thus, the solenoid valve may be more resistant to the valve portion and solenoid portion coming apart, e.g. due to vibrations or shocks.

As is known in the art, the solenoid portion may contain a solenoid coil. A magnetic field generated by the solenoid coil may move one or more parts of the valve portion that are located inside the pin, wherein movement of said part(s) controls fluid flow through the valve portion. Various different arrangements of parts internal to the pin are known in the art.

The resilient locking device may be a spring wire forming a whole or partial annulus. The spring wire may be forced to expand around a portion of the pin before coming into alignment with the groove and, due to the resiliency of the spring wire, it springs into the groove and thereby locks the pin in position. Spring wire may be cheap and simple to install in the aperture.

The aperture may have a first section and a second section, wherein the first section has a first diameter and extends from an outer surface of the solenoid portion; and wherein the second section is located at an end of the first section away from the outer surface, wherein the second section has a second diameter, larger than the first diameter; and the resilient locking device may be located in the second section.

The second section may thus provide a cavity for containing the resilient locking device.

The resilient locking device may have an annular shape that extends between an inner surface and an outer surface, wherein the inner surface has a diameter smaller than the first diameter, and wherein the outer surface has a diameter larger than the first diameter and smaller than the second diameter, such that a radially extending gap is formed between the outer surface of the resilient locking device and a radially outermost surface of the second portion.

When the outer surface of the resilient locking device has a diameter greater than the diameter of the first portion, the resilient locking device cannot easily fall out of the aperture. The radially extending gap provides space for the resilient locking device to expand into when the pin is being inserted through the resilient locking device.

The movable cap may comprise at least one leg, wherein when the movable cap is in the second position, the at least one leg at least partially fills the radially extending gap.

Thus, the leg may prevent the radially-outward movement of the resilient locking device that is required for the resilient locking device to disengage from the groove.

A third section of the aperture may be defined adjacent the second section, opposite the first section, the third section having a third diameter that is smaller than the second diameter. That is, this third section is defined beyond the second section, outward from the first section in the direction extending away from the solenoid portion. Having a smaller diameter for the third section may assist in keeping the resilient locking device correctly located in the second section.

A radially-inwardly facing screw thread may be defined in the aperture and a corresponding screw thread may be defined in a radially-outwardly facing surface of the or each leg, such that the movable cap may be screwed into the solenoid portion to move the movable cap from the first position to the second position.

This provides a mechanism for securing the movable cap in the second position. While the second cap remains in the second position, the resilient locking device cannot disengage from the groove and thus the valve portion and solenoid portion cannot be separated from one another.

In addition, or alternatively, the movable cap may comprise a plurality of legs, wherein each leg is a resilient leg having a radially-outwardly extending flange; wherein the resilient legs are positioned on the movable cap such that a diameter defined by the radially outward most extent of the flanges is greater than the third diameter.

In this example, the resilient legs must bend inwards to get past the third section and into the second section.

The third section may define an annular lip at an end of the second section, wherein in the second position, the flanges engage with the lip to inhibit movement of the movable cap away from the second position.

This provides another mechanism for securing the cap in the second position. The flanges on the legs prevent the movable cap, once installed in the second position, from being easily moved back to the first position. In some examples, the movable cap can be removed using sufficient force (e.g. by levering the cap off with a screwdriver or other tool). Further, depending on the design (e.g. the material used, the resiliency of the legs etc.), this may involve breaking the movable cap or may leave the movable cap intact.

The movable cap may be made of plastic or metal or any suitable material.

Alternatively or additionally, one or more axially extending grooves may be formed in the third section, said grooves configured to receive the or each flange in a first orientation of the movable cap such that the movable cap may move from the first position to the section position; and wherein, in the second position, the movable cap may be rotated away from the first orientation such that the one or more flanges are not aligned with the one or more grooves.

In this example, the movable cap is held in a first orientation where the flanges are aligned with the axially extending grooves and the cap is slid from the first position to the second position. The cap is then turned so that the flanges sit underneath the lip and are not aligned with the grooves. Thus, the moveable cap may be held by a mechanism including a bayonet fit type arrangement. As such, the cap cannot be removed from the second position without first realigning the flanges with the axially extending grooves.

In another aspect, there is provided a method of connecting a valve portion of a solenoid valve to a solenoid portion of the solenoid valve, the method comprising: inserting a pin of the valve portion into an aperture of the solenoid portion, wherein the pin has a groove formed therein; engaging the groove of the pin with a resilient locking device located in the aperture to inhibit movement of the pin out of the solenoid portion; and moving a movable cap from a first position to a second position in the solenoid portion, wherein, in the second position, the movable cap abuts the resilient locking device so as to prevent movement of the resilient locking device out of the groove.

This method means that the valve portion cannot be separated from the solenoid portion while the movable cap is at the second position. This may make the solenoid valve more resistant to shocks and vibrations that would otherwise lead to the valve and solenoid portions disconnecting from each other.

In the step of moving the movable cap from the first position to the second position, the resilient legs of the movable cap may be deformed elastically inwardly until the legs pass a lip in the aperture, at which point, the legs return to an unstressed position abutting the resilient locking device and a flange of each of the resilient legs is located underneath the lip.

The resilient legs may allow the movable cap to easily moved from the first position to the second position, but make it difficult to move the cap back from the second position.

Alternatively or additionally the movable cap may have a screw thread and a section of the aperture may have a corresponding screw thread; wherein, in the step of moving the movable cap from the first position to the second position, the movable cap may be screwed into the aperture to secure the movable cap at the second position.

This provides an alternative or additional feature by which the movable cap is moved into and secured at the second position.

The movable cap may comprise one or more legs each having a radially extending flange, and the aperture may comprise one or more corresponding axially extending grooves; and wherein in the step of moving the movable cap from the first position to the second position, the flanges may slide along the axially extending grooves and, once in the second position, the movable cap may be rotated such that the flanges are not aligned with the axially extending grooves.

This places the flanges out of alignment with the grooves such that the movable cap cannot be removed from the second position without first rotating the movable cap to a position where the flanges are aligned with the axially extending grooves. This provides another mechanism by which the movable cap may be secured at the second position.

