Patent Description:
The use of quick coupling assemblies suitable for connecting pressurized hydraulic lines is widespread in the agricultural machinery industry.

The quick coupling assembly comprises a female coupling and a male coupling, wherein the male coupling is suitable for fitting into the female coupling which is associated with a machine, e.g., a tractor, while the male coupling is associated with a piece of equipment, e.g., a weeder, to be connected to the machine.

When the machine is on, there is a minimum pressure (about <NUM> bar) in the hydraulic system of the machine, and thus in the female coupling. For safety reasons, regulations require that it is not allowed to connect the male coupling to the female coupling with said or higher pressure because otherwise said pressure would be transmitted to the equipment, which could move inadvertently.

For example, when the machine is off, the system pressure remains below <NUM> bar. In said case, the connection between the male coupling and female coupling is allowed.

<CIT> describes a quick coupling assembly comprising a female coupling and a male coupling, wherein the male coupling is suitable for being inserted into the female coupling making a pressurized hydraulic connection between the female coupling and the male coupling.

The female coupling comprises an external body fixed to a machine, e.g., a tractor, and an internal body sliding axially into a cavity in the external body.

The female coupling comprises a head, in which the connection to the male coupling occurs, and a back, in which connection to the machine occurs.

The female coupling further comprises a piston suitable for moving radially, i.e. in a direction orthogonal to the axis of the quick coupling assembly along which the connection movement between the female coupling and the male coupling takes place.

The piston is suitable for moving between a first position, in which the connection between the female coupling and the male coupling is permitted, and a second position, in which said connection is prohibited.

The piston comprises a head and a stem. A hole passing along the axis of the piston, i.e. in said radial direction of the assembly, passes through both the head and the stem. There are two gaskets between the piston and the side walls of its seat, one on the head and one on the stem. The through-hole puts the cavity of the female coupling into fluid communication with a chamber located above the piston head.

With reference to the axis of the quick coupling assembly, the piston head is wider than the stem. Under the head, around the upper end of the piston stem, there is a spring which acts in the direction of the piston axis, in particular, it biases the piston to move towards the outside of the female coupling, i.e. it tends to reduce the protrusion of the lower end of the piston stem into the cavity of the female coupling.

A pressure exhaust channel is in communication with the bottom of the piston head, where the spring is located.

The piston moves along its axis as a function of the difference in force induced by the spring (outward thrust) and the hydraulic pressure (inward thrust) on the piston head.

The spring is calibrated so that beyond a pressure threshold value in the female coupling cavity, the piston moves into the second position, i.e. towards the inside, preventing the sliding of the internal sliding body of the female coupling; the connection between the female coupling and the male coupling cannot take place.

If the pressure in the female coupling cavity is below said threshold value, the piston is in said first position; the connection between the female coupling and the male coupling can take place.

Disadvantageously, the calibration of the spring is very complex; the dimensions of the stem and the head must be taken into account with accuracy.

Furthermore, the spring seat is very small because the female coupling cavity must have sufficient space for the internal body of the female coupling to slide. Consequently, it is not possible to mount springs with excessive load, i.e. the piston can remain in a useful position for connection only for low pressure values, lower than <NUM> bar of normal use.

Finally, two gaskets must be provided, one on the head and one on the stem: disadvantageously, wear rapidly reduces the precision of the piston actuation. The replacement of the gaskets and the spring is very complicated.

It is the object of the present invention to make a quick coupling assembly suitable for connecting hydraulic lines under pressure, comprising a female coupling and a male coupling suitable for inserting into the female coupling, wherein a piston is provided which prohibits the connection in case of pressure exceeding a threshold value, wherein said piston moves in a radial direction, i.e. orthogonally relative to the axial direction of connection between the female coupling and the male coupling, wherein the piston can be easily associated with the female coupling.

It is a further object of the present invention for the piston to be easy to actuate and maintain the actuating threshold value over time.

It is yet another object of the present invention that the piston seat is non-invasive, i.e., easily integrated into the female coupling without forcing complicated and costly design changes to the female coupling.

According to the invention, said and further objects are achieved by a quick coupling assembly as defined in claim <NUM>.

Advantageously, the hydraulic pressure which pushes the full piston into the second position, the locked position, acts in only one direction, completely over the full piston head. Only the spring acts in the opposite direction.

The sizing of the full piston and spring is simple, having to consider in practice only the dimensions of the full piston in its radial seat.

Maintenance is simplified because there is a single gasket on the full piston, which is the gasket on the external edge of the head.

These and other features of the present invention will become further apparent from the following detailed description of practical embodiments thereof illustrated by way of non-limiting example in the accompanying drawings, in which:.

A quick coupling assembly <NUM> suitable for connecting pressurized hydraulic lines according to the present invention comprises a female coupling <NUM> and a male coupling <NUM> which can be connected to the female coupling <NUM> (<FIG>).

The female coupling <NUM> is associated with a machine (not shown), e.g., a tractor, while the male coupling <NUM> is associated with a piece of working equipment, e.g., a weeder.

With particular reference to <FIG>, the female coupling <NUM> comprises an external part <NUM> integral with the machine, and an internal part <NUM> sliding along a connection axis X inside the external part <NUM>.

The external part <NUM> of the female coupling <NUM> comprises a junction <NUM> for connecting to the machine, a female body <NUM> and a ring nut <NUM> integral with each other.

The internal part <NUM> of the female coupling <NUM> comprises a sliding body <NUM>, a shutter <NUM>, a ring nut holder <NUM> suitable for containing balls <NUM> in a locking seat <NUM> (<FIG>), and a pin <NUM> integral with the sliding body <NUM> with which a pressure exhaust valve <NUM> is also associated.

The shutter <NUM> has a head <NUM> and a stem <NUM>, wherein the head <NUM> is in one piece with the stem <NUM>. The head <NUM> comprises a flat end <NUM> facing the male coupling <NUM>; the head <NUM> expands radially toward the flat end <NUM>.

A spring <NUM> is provided between the external portion <NUM> and the internal portion <NUM> suitable for keeping the female coupling <NUM> in the rest position when it is separated from the male coupling <NUM>.

A cup <NUM>, which is held in place by a spring <NUM>, is suitable for sliding inside the ring nut holder <NUM>. The cup <NUM> comprises a thrust portion <NUM> (<FIG>) suitable for moving the balls <NUM> into an exhaust seat <NUM> of the ring nut <NUM> (<FIG>).

The internal portion <NUM> also comprises a sleeve <NUM> through which the stem <NUM> of the coupling <NUM> passes. The sleeve <NUM> is suitable for sliding axially, i.e. along the connection axis X, relative to both the sliding body <NUM> and the coupling <NUM>.

The sleeve <NUM> has an end <NUM> which interacts in a sealing manner with the head <NUM> of the shutter <NUM>, wherein a spring <NUM> is suitable for forcing said seal. The sleeve <NUM> comprises a radial shim <NUM> suitable for receiving in abutment a complementary shim <NUM> of the cup <NUM>, which is suitable for canceling the seal of the sleeve <NUM> on the shutter <NUM>, as will be explained in greater detail below.

The pressure exhaust valve <NUM> is associated with a back <NUM> of the sliding body <NUM>, wherein said back <NUM> is elastically associated with a spring <NUM> to a rear end <NUM> of the coupling <NUM> by means of a guide body <NUM> integral with the shutter <NUM>.

The external part <NUM> and the internal part <NUM> are shaped to form a single chamber <NUM>, in which the hydraulic pressure generated by the machine, of at least roughly <NUM> bars, is present.

Said single chamber <NUM> comprises (<FIG>) a head chamber <NUM> about the shutter <NUM> (partly inside the sleeve <NUM>), two first oblique chambers <NUM> suitable to take the working pressure outside the internal part <NUM>, an external chamber <NUM> between the junction <NUM> and the female body <NUM>, two second oblique chambers <NUM> and a rear chamber <NUM>.

The second oblique chambers <NUM> connect the external chamber <NUM> to the rear chamber <NUM>, which is connected to the machine.

Observing <FIG>, from right to left, i.e. from the head to the back of the female coupling <NUM>, the first oblique chambers <NUM> diverge relative to the connection axis X, while the second oblique chambers <NUM> converge relative to the same connection axis X.

The first oblique chambers <NUM> pass through both the sliding body <NUM> and the junction <NUM>, which is also crossed by the second oblique chambers <NUM>.

The external chamber <NUM> is in communication with a through chamber <NUM> of a sleeve <NUM> integral with the junction <NUM>, which provides a radial seat <NUM> for a full piston <NUM> (<FIG>).

It is worth noting that radial means a direction orthogonal to that of the connection axis X.

The sleeve <NUM> is suitable for making an upper limit stop of the full piston <NUM>.

The full piston <NUM> comprises a head <NUM> and a stem <NUM>.

Full piston <NUM> means a piston with a full head and stem, i.e. without through cavities, in particular without a through cavity along the radial direction in which the piston moves, between the head of the piston and the bottom of the stem.

A spring <NUM>, inserted into a chamber <NUM>, is suitable for pushing the full piston <NUM> into a stop towards the sleeve <NUM>.

An upper surface <NUM> of the head <NUM> of the full piston <NUM> faces the through chamber <NUM> of the sleeve <NUM>.

The head <NUM> of the full piston <NUM> (<FIG>) provides a lateral seat <NUM> for a gasket <NUM> suitable for ensuring sealing between the through chamber <NUM>, i.e., the single chamber <NUM>, and the chamber <NUM> of the spring <NUM>, wherein said radial seat <NUM> is in hydraulic connection with an exhaust duct <NUM> formed in the junction <NUM>.

As mentioned above the full piston <NUM> has no through cavities, i.e. there is a pressure seal between the single chamber <NUM> and exhaust duct <NUM>.

The exhaust duct <NUM> is hydraulically connected to a pressure exhaust chamber <NUM> which faces the back of the internal portion <NUM> in which the pressure exhaust valve <NUM> is provided.

The exhaust duct <NUM> (<FIG>) comprises an axial oriented channel <NUM> parallel to the connection axis X, and a radial oriented channel <NUM> orthogonal to said axial oriented channel <NUM>.

The radial channel <NUM> is adapted to guide a bottom <NUM> of the stem <NUM>.

The pin <NUM> has a longitudinal development in the axial direction and is suitable for sliding in the axial oriented channel <NUM>. Through the radial oriented channel <NUM>, the stem <NUM> of the full piston <NUM> is suitable for flowing into the axial oriented channel <NUM> at a junction <NUM>. The axial oriented channel <NUM> comprises a portion of the head <NUM> adjacent to the junction <NUM>.

The full piston <NUM> is suitable for sliding between a first position (<FIG>), in which the piston head <NUM> abuts the limit stop on the sleeve <NUM> and the bottom <NUM> of the stem <NUM> is completely within the radial oriented channel <NUM>, i.e., does not protrude into the axial oriented channel <NUM> at the junction <NUM>, and a second position, in which the bottom <NUM> protrudes from the radial oriented channel <NUM> into the axial oriented channel <NUM> at the junction <NUM>. <FIG> shows the bottom <NUM> which connects to a seat <NUM> arriving at a lower limit stop; a portion of the stem <NUM> obstructs the axial oriented channel <NUM> in the junction <NUM>.

The pin <NUM>, guided by the sliding body <NUM>, is suitable for sliding between a first position (<FIG>), in which a free end <NUM> of the pin <NUM> is completely inside the head portion <NUM> of the axial oriented duct <NUM>, and a second position (<FIG>) in which the free end <NUM> protrudes from the head portion <NUM> in the junction <NUM>.

If the full piston <NUM> is in the second position, the free end <NUM> of the pin <NUM> cannot enter the junction <NUM>, i.e., its axial movement toward the junction <NUM> is limited by the stem <NUM> of the full piston <NUM>, which then obstructs the junction <NUM>.

The male coupling <NUM> (<FIG>) comprises a male body <NUM>, a shutter <NUM> sliding axially into the male body <NUM>, and a junction <NUM> suitable for connecting to a piece of equipment (not shown).

The shutter <NUM> is also suitable for sliding relative to an internal body <NUM> housed in and integral with the male body <NUM>.

A spring <NUM> holds a head <NUM> of the shutter <NUM> in a sealing manner on the male body <NUM>, while an internal valve <NUM> is suitable for putting the male coupling <NUM> into fluid communication with the equipment (not shown).

The radial ends of the shutter <NUM> and the male body <NUM> of the male coupling <NUM> form a flat face of the male coupling <NUM>.

The ends of the shutter <NUM> and the cup <NUM> of the female coupling <NUM> form a flat face of the female coupling <NUM>.

By observing the <FIG> in sequence, it is possible to understand how the connection occurs if the pressure in the single chamber <NUM> is below a threshold value, e.g., when the machine is off, namely in the case in which connection between the female coupling <NUM> and the male coupling <NUM> is allowed.

The threshold value preferably coincides with the operating pressure of the machine, typically <NUM> bar.

Highlighting that a flat-face type assembly <NUM> is being described, when the flat face of the male coupling <NUM> is pushed (by an operator) against the flat face of the female coupling <NUM>, the two shutters <NUM>, <NUM> come into contact as well as the male body <NUM> with the cup <NUM> (<FIG>).

The male body <NUM> axially pushes the cup <NUM> backwards (towards the bottom of the female coupling <NUM>, i.e., leftwards when looking at the figures), which moves the balls <NUM> from their locking seat <NUM> to the exhaust seat <NUM> of the ring nut <NUM> (<FIG>).

The cup <NUM>, by means of the balls <NUM> which move the ring nut holder <NUM>, also pushes back the sliding body <NUM> which is integral with the ring nut holder <NUM>; in the absence of overpressure beyond the defined threshold value, the pin <NUM> can move axially in the junction <NUM>, under the full piston <NUM> stopped in the first position (<FIG>, <FIG>).

The thrust of the cup <NUM> is opposed to a ring nut spring <NUM> which acts on the ring nut holder <NUM> through a shim <NUM> (<FIG>). Once the balls <NUM> are in the exhaust seat <NUM> of the ring nut <NUM>, the ring nut holder <NUM> is in a stable position in which the forward thrust (to the right as seen in <FIG>) of the ring nut spring <NUM> is balanced by the contrast applied by the exhaust seat <NUM> of the ring nut <NUM>.

Continuing the insertion of the male body <NUM> into the female coupling <NUM>, in particular sliding inside the ring nut <NUM> (<FIG>), the radial shim <NUM> of the cup <NUM> comes into contact with the radial shim <NUM> of the sleeve <NUM>, which retracts thus opening the hydraulic line between the female coupling <NUM> and the male coupling <NUM>. The balls <NUM> from the exhaust seat <NUM> of the ring nut <NUM>, pushed by the ring nut spring <NUM>, are inserted into an external seat <NUM> of the male body <NUM> thus making the connection stable (<FIG>). The sliding body <NUM>, fed by the ring nut holder <NUM>, is moved forward again (rightwards observing the figures) thus freeing the junction <NUM> from the pin <NUM> again.

In the absence of pressure above the threshold value in the single chamber <NUM>, the full piston <NUM> is held in the first position without interfering with the connection between the female coupling <NUM> and the male coupling <NUM>.

If the pressure in the single chamber <NUM> is higher than the threshold value (<FIG> and <FIG>), again starting from a situation of a male coupling <NUM> separated from the female coupling <NUM> as in <FIG>, even before starting the connection attempt, the full piston <NUM> slides into the second position obstructing the axial oriented channel <NUM> at the junction <NUM>.

Consequently, if the operator tries to force the insertion of the male coupling <NUM> into the female coupling <NUM>, at a given point it will find a block generated by the pin <NUM> which abuts the side of the stem <NUM> of the full piston <NUM>, thus occluding the axial oriented channel <NUM>.

As the sliding body <NUM> cannot retract further, the cup <NUM> does not interact with the sleeve <NUM> (<FIG>), which thus remains sealed to the head <NUM> of the shutter <NUM>.

If the overpressure in female coupling <NUM> is not relieved, e.g., by switching off the machine, the connection between the male coupling <NUM> and the female coupling <NUM> cannot take place.

Advantageously, the pressure which pushes the full piston <NUM> into the second position, the locked position, acts in only one direction, completely on the upper surface <NUM> of the head <NUM> of the full piston <NUM>.

Only the spring <NUM> acts in the opposite direction.

The sealing between the chamber <NUM> of the spring <NUM> and the single chamber <NUM> is guaranteed by the gasket <NUM> on the side edge of the head <NUM> alone.

Advantageously, the sizing of the full piston <NUM> and spring <NUM> is simple, because in practice only the dimensions of the full piston <NUM> in its radial seat <NUM> need to be considered, with no through cavities complicating design calculations.

The use of oblique channels <NUM>, <NUM> allows easily taking the pressure outside the sliding body <NUM> without needing to pierce the full piston <NUM>, which is, therefore, more solid, stable and responsive to overpressure.

Advantageously, the full piston <NUM> moves by even intersecting the connection axis X without limiting the stroke of the sliding body <NUM>. A wall for the pressure exhaust valve <NUM> is provided between the radial seat <NUM> of the full piston <NUM> and the sliding body <NUM>.

The radial seat <NUM> of the full piston <NUM> can be enlarged to use heavily loaded springs <NUM>.

Claim 1:
A quick coupling assembly (<NUM>) suitable for connecting hydraulic lines under pressure, comprising a female coupling (<NUM>) and a male coupling (<NUM>), which is connectable to the female coupling (<NUM>), wherein the female coupling (<NUM>) is associable with a machine suitable for generating hydraulic pressure, while the male coupling (<NUM>) is associable with an equipment,
wherein the female coupling (<NUM>) comprises an external part (<NUM>) which is fixable to the machine, a piston (<NUM>) and an internal part (<NUM>) sliding along a connection axis (X) inside the external part (<NUM>), wherein the connection axis (X) defines an axial direction,
the external part (<NUM>) and the internal part (<NUM>) are shaped so as to create a single chamber (<NUM>) suitable for maintaining the hydraulic pressure generated by the machine,
wherein the external part (<NUM>) comprises a radial seat (<NUM>) for the piston (<NUM>) suitable for moving radially between a first position in which the connection between the female coupling (<NUM>) and the male coupling (<NUM>) is allowed, and a second position, in which the connection between the female coupling (<NUM>) and the male coupling (<NUM>) is forbidden due to the interference between the internal part (<NUM>) and the piston (<NUM>),
wherein the piston (<NUM>) assumes the second position when in the female coupling (<NUM>) there is a hydraulic pressure equal to or greater than a threshold value,
wherein the piston (<NUM>) comprises a head (<NUM>) and a stem (<NUM>), wherein the head (<NUM>) provides a lateral seat (<NUM>) for a gasket (<NUM>) suitable for guaranteeing the seal between the single chamber (<NUM>) and a chamber (<NUM>) housing a spring (<NUM>) suitable for forcing the piston (<NUM>) into the first position, wherein the chamber (<NUM>) housing the spring (<NUM>) is in hydraulic connection with an exhaust duct (<NUM>),
characterized in that
the piston (<NUM>) is a full piston without through cavities.