The present invention relates to a device for ventilation of a chamber according to the independent patent claim.

In hydraulic or pneumatic systems where one or more cylinders are employed, parts ' or portions of the individual cylinder will not be pressurised during operation, nor will the same parts or portions be directly located in the open air. Where the non- pressurised part is an enclosed chamber, it will be necessary to make a ventilation passage to atmosphere in order to prevent the chamber from being pressurised by movement of parts passing through the chamber, such as the movement of a cylinder piston. In addition, the ventilation passage must be provided in such a manner that contamination is prevented from entering the chamber.

The device according to the invention will preferably be employed for ventilation of a chamber such as that described herein, but as a person skilled in the art will appreciate, it may also be employed for other types of chambers or compartments where there is a need for ventilation. The device will therefore be employed for applications where it is desirable to obtain free passage of air, while at the same time it is desirable to prevent contamination from penetrating the chamber concerned.

According to the prior art a device for ventilation is provided by a nipple device comprising a drainage nipple, which is provided with a ventilation duct and a drainage nipple sleeve designed with a duct to atmosphere. The nipple device is mounted in the wall of the chamber and the ventilation duct and the atmosphere duct arrange for a connection between the interior and the exterior of the chamber. The ventilation duct and the atmosphere duct are displaced relative to each other . and if water is splashed in from the outside it has to pass through a labyrinth of passages in order to be able to infiltrate the chamber. Furthermore, a collecting compartment is provided in the drainage nipple sleeve where the water splashed into the atmosphere duct is collected before running out again through the atmosphere duct. The nipple device is illustrated in figure 1 and will be explained further in the detailed description of the invention.

This known nipple device is encumbered with a number of drawbacks. Due to the • design of the collecting pocket, the device has to be mounted in the correct position with regard to what is up and down in order for the collecting pocket to be placed in the correct position. A device that includes a component such as a nipple device is mechanically vulnerable, and improper handling can therefore cause the nipple device to be damaged and to break off. A further disadvantage of the device is that there are many parts to install. There are high costs involved in production and assembly and the device requires a relatively large amount of space. There is also a risk of swarf being released during assembly. This known valve or nipple device furthermore helps to cause pressure difference. It should also be mentioned that the use is known in the prior art of a porous body as an alternative to the nipple device.

Thus it is an object of the present invention to provide a device that is simple and consists of few components, is inexpensive to manufacture, takes up little space and where the risk of assembly error is minimised.

The device according to the invention aims to remove the nipple device and instead provide a solution which employs a ventilation passage provided directly in the chamber wall and a blocking body. Two alternative embodiments are further indicated for how the device can be implemented by being mounted in the chamber wall.

The device according to the independent patent claim comprises a through-going passage constructed in the chamber wall and providing communication between the interior and the exterior of the chamber. The passage comprises a ventilation duct extending from the interior of the chamber and communicating with a discharge duct leading to the outside of the chamber. The ventilation duct has an opening to a cavity provided in the chamber wall and the cavity has an opening to the outside of the chamber. The device is characterised in that it comprises a blocking body mounted in the cavity. The blocking body is secured in the cavity by a portion of the blocking body being received in a holding opening provided in connection with the cavity. Furthermore, the discharge duct is positioned in the wall of the chamber in such a manner that when the device's components are brought into operational position, the outlet of the discharge duct is positioned lower than the cavity's opening to the outside of the chamber. The term operational position here refers to the position adopted by the device when the chamber is in use.

The blocking body, the cavity and the holding opening will preferably be designed with a tolerance deviation that permits a press fit connection to be achieved when a portion of the blocking body is received in the holding opening. Additional support will also preferably be provided for securing the blocking body in the cavity, with the blocking body abutting against at least one of the cavity's wall portions.

The easiest way of producing the duct and the cavity in which the blocking body is secured is by providing bores in the chamber wall.

In a first embodiment of the invention the cavity and the discharge duct are composed of a two-part bore. A bore forming the cavity and an additional bore forming the discharge duct are positioned parallel to each other and opened towards each other in the transition between the two bores with a common opening extending in the bores' longitudinal direction. A portion of this transition between the two bores forms the holding opening. When the blocking body is received in the holding opening, a portion of the blocking body protrudes into the additional bore that forms the discharge duct, with the result that a sufficient clearance is obtained between the blocking body and the additional bore's wall portion for the passage of air.

According to a further version of this first embodiment of the invention, the blocking body is located in the cavity/bore in such a manner that it offers protection against the intrusion of contamination into the ventilation duct leading directly to the interior of the chamber.

By means of the same positioning of the blocking body the object is also achieved that a collecting pocket is formed in the cavity between the blocking body and the ventilation duct. When water and other contamination infiltrate through the discharge duct/the additional bore, they will not reach further in than the collecting pocket which is designed and positioned so that the contamination does not pass any further into the ventilation duct. After being collected in the collecting pocket, the contamination will run out through the discharge duct due to the device's sloping position in the chamber wall.

According to a second embodiment of the invention an auxiliary duct is provided in the device which is located between the ventilation duct and the discharge duct. According to this second embodiment the discharge duct and the cavity in which the blocking body is secured are not positioned closely together, but due to the provision of the auxiliary duct, they are arranged so that there is a space between them. The holding opening for receiving a portion of the blocking body is provided between the cavity, the ventilation duct and the auxiliary duct, or alternatively between the cavity and the ventilation duct, or the cavity and the auxiliary duct.

The auxiliary duct will preferably be provided with an opening to the outside of the chamber, the opening being sealed by a plug, which preferably may be spherical.

The blocking body will preferably be in the form of a sphere, but other shapes may also be appropriate here. It is left to the skilled person to decide which shape will be most advantageous, depending on factors such as the shape of the holding opening, the tolerance deviation required to obtain sufficient hold in the press fit, etc.

Examples of the two alternative embodiments of the invention will now be described with reference to the figures, in which Figure 1 is a sectional view from the side of a device according to the prior art. Figure 2a is a sectional view from the side of a first embodiment of the invention. Figure 2b is a plan view of the first embodiment of the invention without blocking body. Figure 3 is a sectional view from the side of a second embodiment of the invention. Figure 1 illustrates a nipple device according to the prior art. It can be seen from figure 1 that a drainage nipple 1 is fixed in a recess 21 provided in a chamber wall 20. A duct 3 arranges for communication between the chamber and the recess 21. The drainage nipple 1 is provided with a through- going ventilation duct 2. A drainage nipple sleeve 23 which is attached to the drainage nipple 1 is provided with a collecting compartment 5 and a duct 4 to atmosphere. By means of the nipple device, therefore, a passage is provided between the chamber and the outside of the chamber, for discharging air from the chamber. It can be seen from figure 1 that the chamber is protected against contamination such as, for example, splashes of water, by the duct 4 to atmosphere being displaced relative to the ventilation duct 2. Water which then splashes into the atmosphere duct 4 from the outside has to pass through a kind of labyrinth between the duct to the atmosphere 4 and the ventilation duct 2 in order to reach the chamber. By means of this configuration the object is achieved that the water is not splashed right into the ventilation duct 2, but is collected in the collecting compartment 5. Since the nipple device is mounted at an angle in the chamber wall, a tilt is also obtained on the collecting compartment, and the water collected herein will run out again through the duct 4 to atmosphere.

It can be seen that the invention as illustrated in figures 2a, 2b and 3 is comprised of a device that is much simpler and composed of fewer parts than the known device illustrated in figure 1.

Figure 2a illustrates a first embodiment of the invention. A cavity in the form of a bore 7 is provided in the chamber wall with an opening to the outside of the chamber. There is further illustrated a discharge opening in the form of an additional bore 8, which is positioned parallel to the bore 7. The additional bore 8 is open in towards the bore 7 in the bores' 7, 8 longitudinal direction and a portion of this open area acts as a holding opening for a blocking body. The blocking body is depicted here as a sphere 6 and is designed so that it can be pressed to fit in the holding opening and the bore 7. A portion of the sphere 6 then protrudes into the bore 8, and the bore's 7 wall portions provide additional support for the sphere 6. A press fit connection is thereby obtained between the sphere 6 and the bores 7, 8. The sphere is held in place in this manner without the sphere having to be supported against a shoulder in the bottom and the material around swaged.

The sphere 6 in secured position is located in such a manner that a clearance is obtained between the sphere 6 and the wall portions in the bore 8. The sphere's 6 position in the bore 7 at a distance from the ventilation duct 22 provides a compartment that can be used as a collecting pocket 5 for the contamination introduced through the additional bore 8.

Venting can be undertaken by air flowing from the chamber through the ventilation duct 22, on through the additional bore 8 and out to the outside of the chamber. In the event of splashing such as splashes of water from the outside towards the additional bore's 8 opening, the sphere 6 ensures that the ventilation duct 22 is protected against direct water penetration. There is a possibility, however, that water may penetrate the additional bore 8 and continue to the collecting pocket 5. When the device illustrated in figure 2a is in use, i.e. when the device's components are in operational position, the additional bore's 8 outlet to the outside of the chamber will be located lower than the cavity's opening to the outside of the chamber. This causes water that enters the collecting pocket 5 to run out again through the additional bore 8. •

Figure 2b illustrates how the bore 7 and the additional bore 8 are positioned relative to each other. In this case the sphere 6 is not located in the bore 7.

Figure 3 illustrates a second embodiment of the invention. In figure 3 it can be seen that an auxiliary duct 11 arranges for communication between the ventilation duct 22 and the discharge duct, which is provided here as an additional bore 10. The auxiliary duct's 11 opening to the outside of the chamber is shown sealed by a plug 12, for example a press fit sphere. The cavity for securing the sphere 6 is depicted in the form of a bore 7. It can be seen that the bore 7 and the additional bore 10 are located at a distance from each other. This positioning is made possible by the provision of the auxiliary duct 11. Thus the bores do not assume the form of a two- part bore as is the case in the embodiment illustrated in figures 2a and 2b. Instead, the bore 7 is provided with a holding opening for the sphere 6 in towards the ventilation duct 22 and the auxiliary duct. A portion of the sphere 6 is received in this holding opening and remaining wall portions in the bore 7 provide further support for the sphere 6. In this embodiment the labyrinth function is also maintained. It is also important here that the additional bore's 11 outlet to the outside is located lower than the cavity's opening to the outside of the chamber when the device's components are in operational position.

All the ducts illustrated in figures 2a, 2b and 3 are preferably in'the form of bores. Furthermore, the chamber wall will preferably be made of aluminium and the blocking body of a harder material such as, for example, stainless steel. With the invention as described herein the object is achieved that all the functions are fulfilled. In addition the number of parts is reduced, nor is there any risk that rough treatment of the device will damage the drainage system.