Filter for internal combustion engines

A filter for internal combustion engines of vehicles, comprising: an external casing (11) and an upper closing cover (12), which close an internal chamber (13) having an inlet for the liquid to be filtered and an outlet for filtered liquid; a filter cartridge (20) having a tubular filter means (21) located internally of the internal chamber (13) which separates the chamber (13) into a first zone communicating with the inlet and a second zone communicating with the outlet, and a lower plate (22) joined to a lower end of the filter means (21); the filter means being removably fixed to the casing (11) such as to remain internally of the casing when the casing is separated from the cover; the lower plate comprising hooking teeth (31), developing axially and having an elastic action in a radial direction; the base of the casing comprising a generally cylindrical surface sub-divided into a number of sectors which is equal to a number of hooking teeth (31), each sector defining a hooking zone (43) for axially constraining the hooking teeth (31) in a snap-fastening.

TECHNICAL FIELD

The invention relates to a filter for liquids for internal combustion engines of vehicles, in particular oil and diesel.

BACKGROUND ART

For some years filters have been made having an external casing and an upper closing cover, which define an internal chamber having an inlet for the liquid to be filtered and an outlet for the filtered liquid, and a filter cartridge having a tubular filter means, located internally of the internal chamber, which separates the chamber into a first zone communicating with the inlet and a second zone communicating with the outlet.

The filter cartridge is constrained to the upper cover by means of an upper plate joined to the upper end of the filter means and, when it is worn out and needs to be replaced, is separated from the cover and replaced with a new cartridge.

The filters are favoured at present because there is no need to dispose of and destroy the whole filter but only the worn-out filter cartridge.

The accessibility of the cartridge is also facilitated by the fact that as it is constrained to the closing cover of the casing, when the casing is opened the cartridge follows the cover, exiting from the fluid it is immersed in without there being any need to access it with tools and without any need to shake it or unblock it, causing dirt to detach from it, which is always damaging.

To constrain the cartridge and the cover to one another, it is known to realise first hooking elements and second hooking agents to realise a reciprocal snap-fastening, where the first hooking elements (or the second hooking elements) are joined to the cover and project axially towards the inside of the chamber and, vice versa, the second hooking elements (or the first hooking elements) are joined to the upper plate and project axially towards the upper cover.

A drawback connected to these filters is that since the used filter cartridge, impregnated with liquid, is attached to the cover, when the external casing is removed, separating it from the cover, the liquid drips from the cartridge, fouling not only the operator but also the surrounding environment and parts of the engine.

The aim of the present patent is to obviate the above-described drawback.

Disclosure of Invention

The aim is attained by a filter having the characteristics recited in claim1.

Primarily the objective is attained by making the cartridge removably fastened to the casing such as to remain internally of the casing when the casing is separated from the cover.

The invention further comprises advantageous means for removably fastening the cartridge to the bottom of the cover, such as to facilitate the engaging/disengaging rapidly and securely.

The invention is based on the fact that it comprises first hooking elements which are solidly constrained to the casing and exhibiting hooking teeth, developing axially and having an elastic action in a radial direction, and second hooking elements which are solidly constrained to the cartridge, which have a generally cylindrical surface that is subdivided into a number of equal sectors which is equal to the hooking teeth, where each sector defines a hooking zone for axially constraining the hooking teeth in a snap-fastening arrangement, and a disengaging zone, located by a side of the hooking zone, destined to free the hooking teeth from the constraint with the hooking zone following a rotation, over a limited angle, of the cartridge with respect to the casing.

BEST MODE FOR CARRYING OUT THE INVENTION

The filter comprises an external casing11, in particular a generally cylindrical casing, superiorly open and having an upper closing cover12, which closes an internal chamber13, generally cylindrical.

The cover12comprises threaded means120for coupling with means present on the casing, as well as abutting elements121and sealing elements122for defining the exact position and realising a hydraulic seal between the cover and the casing thanks to the gasket122.

The chamber13affords an inlet130for the liquid to be filtered which, in the embodiment illustrated in the figures is located laterally, on the cover, and an outlet131for the filtered liquid which, once more with reference to the embodiment illustrated in the figures, is located on the upper cover12.

A filter cartridge20is located internally of the chamber13, which filter cartridge20has a tubular filter means21located internally of the internal chamber13which separates the chamber into a first zone communicating with the inlet130and a second zone communicating with the outlet131.

The cartridge20further comprises a lower plate22, in the form of a circular plate, which entirely and snugly covers the flat and annular lower surface of the filter means21and is solidly joined thereto. The cartridge20finally comprises an upper plate23, in the form of a circular ring, which entirely and snugly covers the flat and annular upper surface of the filter means21and is solidly joined thereto.

In the embodiment illustrated in the figures, the cover12comprises an axial tube17which passes through an opening afforded in the centre of the upper plate23. A gasket231provides a hermetic seal between the plate23and the tube17.

The tube17communicates, through the cover, with the inlet conduit130of the liquid to be filtered.

The filter further possesses first hooking elements and second hooking elements combining with one another to realise a reciprocal snap-fastening.

In the embodiment illustrated in the figures, the first hooking elements30are joined to the casing11, at the base thereof, forming a single body with the wall of the casing, and axially extend upwards internally of the chamber13, while the second hooking elements40are joined in a single body to the lower plate22and axially project downwards, towards the base of the casing.

In the invention, the first hooking elements comprise two or more hooking teeth31, having axial direction and elastic action in a radial direction, while the second hooking elements comprise a tubular body41having an external surface which is generally cylindrical and sub-divided into a number of sectors which is the same as the number of hooking teeth31.

Each sector of the cylindrical surface defines a hooking zone43(FIG. 3) for axially constraining the hooking teeth31in a snap-fastening, and a disengaging zone44, located by the side of the hooking zone, destined to free the hooking teeth31from the engaging with the hooking zone43following a rotation, through a limited angle, of the cartridge20with respect to the upper cover12.

In particular, each hooking zone43defines (FIG. 6) in transversal section a second hooking tooth complementary to the first hooking teeth31and destined to receive and engage the first hooking teeth31in a snap-fastening following reciprocal nearing in an axial direction.

In more detail, the hooking zone43includes a slightly inclined upper portion43a, a radius of which increases in a downwards direction, followed by a lower gully43bwhich forms an edge43dhaving a saw-tooth shape, destined to capture a first hooking tooth31.

The disengaging zone44comprises a portion of entirely smooth cylindrical surface44a, and a strip of arched surface44bwhich forms a connecting ramp that lowers continuously, along the circumference of the gully43btowards the surface portion44a, which ramp is destined to transfer the hooking teeth from the gully43bto the smooth cylindrical surface44a.

Preferably the toothed gully43band the strip of surface44bextend at a constant axial distance with respect to the hooking zone43, such that the hooking tooth can slide along it without there being any need for any axial movement of the cartridge20.

Further, a straight rib45located on the other side of the hooking zone43separates the hooking zone43of a sector from the disengaging zone44of the other sector, and projects radially externally with respect to the surrounding zones43, and44.

When the hooking teeth31engage with the respective edges43d, they strike against the lower surface of the plate22; thanks to this striking, the filter cartridge20is kept at the exact desired axial distance from the cover12; further, the constraint between the hooking teeth31and the cylindrical body41is rendered completely free of play, as the edges43dand the edges of the hooking teeth31are kept pushed against one another.

Four equidistant abutments110project from the base of the casing, which abutments110function as guides and radial constraints for the cartridge20.

In use, to couple the filter cartridge20to the casing11, the cartridge is inserted in the casing in an axial direction, by placing the hooking zones43onto the hooking teeth31; the reciprocal coupling is achieved by snap-fastening of the projections of the teeth31in the gullies43b.

The two hooking zones43function, together with the guide action produced by the ribs45, as entry lanes for the hooking teeth31, and enable secure pressure-fastening, without any need for excessive force to be used.

The rotation of the cartridge on the axis thereof during the application of pressure enables secure insertion into the entry slots.

The hooking is confirmed and indeed heard by a click of the teeth31in the gullies43b.

From this stable position, the cartridge20cannot further move unless a correct disengaging action is exerted thereon.

The edge43dprevents any unhooking of the cartridge20due to the forces generated by the pressure hikes internally of the complete filter group.

The separation of the cartridge20from the casing11is performed by a movement made up of two stages; in the first stage the cartridge20is rotated with respect to the casing (a relatively small torque is required) through a brief angle such as to cause the edges of the teeth31to slide on the respective connecting ramps (44b) with a consequent separating of the teeth31themselves) up to when the edges are on the smooth surface portions44a.

As the toothed gullies43band the surface strips44bextend at a constant axial distance with respect to the hooking zones43, the hooking teeth31slide along them without any need for axial movement of the cartridge20.

At this point, by pulling the cartridge20axially away from the casing11, the teeth31detach from the tubular body41and the cartridge is separated from the casing.

In this way the filter means21can be gently separated from the filter casing without using force at the moment of the disengaging and therefore preventing exit of liquid and splashing of the liquid to the outside.

In a further embodiment (FIGS. 8, 9, 10), the hooking zone143exhibits an upper portion143awhich is slightly inclined, the radius of which increases in a downwards direction, followed by a lower cylindrical gully143bwhich forms an edge143dhaving a sawtooth shape, destined to spear a first hooking tooth31. The disengaging zone144comprises a portion of smooth cylindrical surface144a, and an arched inclined gully144bthe base of which drops to the base of the gully143b, and is destined to transfer the hooking teeth from the gully143bto the smooth cylindrical surface144a.

The gully144bextends at least partially at a variable axial distance with respect to the hooking zone143, such as to distance the filter cartridge20from the casing11during the unhooking rotation of the cartridge.

The gullies143band144bpreferably extend at least partially helically with respect to the position of the hooking zone143.

With the aim of guaranteeing distancing of the filter cartridge20from the casing11during the disengaging rotation of the cartridge, a ramp150is provided between the base of the toothed gully143band the base of the gully144b, which ramp150is used for the sliding of the hooking tooth31.

Further, on the other side of the hooking zone143there is a straight ribbing145which separates the hooking zone143of a sector from the disengaging zone144of the other sector, and projects radially externally with respect to the surrounding zones143,144.

In use, in order to couple the filter cartridge20to the casing11, the cartridge is inserted in the casing in an axial direction, causing the hooking zones143to encounter the hooking teeth31; the reciprocal coupling is done by snap-insertion of the projections in the teeth31of the gullies143b.

The two hooking zones143function, together with the guide action produced by the ribbings145, as entry lanes for the hooking teeth31, and enable a pressure-fit that is secure and which does not require excessive force.

The rotation of the cartridge on the axis thereof during the application of the pressure means that the entry lanes can be encountered securely.

The engagement is completed, and can be heard, by a snap entry of the teeth31in the gullies143b.

From this stable position, the cartridge20cannot further move unless the correct disengaging movement is exerted thereon.

The edge143dprevents any unhooking of the cartridge20as a result of the forces generated by pressure peaks internally of the complete filter group.

The separation of the cartridge20from the casing11is done by a two-step movement: in the first step the cartridge20is rotated with respect to the casing (a relatively small torque is required) over a small angle such as to case the edges of the teeth31to slide on the respective ramps provided by the gully144b(with a consequent separation of the teeth31themselves) up until the edges become arranged on the smooth portions of surface144a, and at the same time the filter cartridge20distances from the casing11during the unhooking rotation of the cartridge.

The toothed gully143band the gully144bpreferably extend at least partially helically with respect to the position of the hooking zone143.

With the aim of ensuring the distancing of the filter cartridge20from the casing11during the unhooking rotation of the cartridge, the ramp150is provided adjacent to the toothed gully143band the arched surface144b, which ramp150enables the sliding of the hooking tooth31.

At this point, by axially pulling the cartridge20away from the casing11, the teeth31detach from the tubular body41and the cartridge is separated from the casing.

In this way the filter means21can be gently separated from the filter casing without any great force on unhooking, preventing exit of liquids and projection thereof to the outside.

Obviously numerous modifications of a practical-applicational nature can be brought to the invention without its forsaking the ambit of protection as claimed herein below.