This invention relates to a quick coupler, particularly to quick couplers with safety system, and even more particularly to quick couplers with safety system intended for excavators.

It is well known that a coupler has a hydraulically operated latching hook to engage with the pins of an accessory, for example a bucket, to the arm of an excavator. Such couplers usually include a safety mechanism to prevent the accessory from being disengaged from the coupler in the event of hydraulic failure.

The patent KR101777739 describes a drive system that locks the front and rear pins by means of latches connected to each other, this connection being made by means of spring-actuated arms. This system has the disadvantage that the safety of the system resides only in the force of the said mechanical spring.

The patent EP2161378 discloses a coupler which is actuated by means of the hydraulic cylinders of the front and rear locks, but it has no mechanical locking in case of failure of one cylinder, e.g. if a cylinder breaks. The present invention differs from the said disclosure since it achieves the goal of mechanical locking by means of the front latch (6) and the locking plate (11).

It is an objective of this invention to provide an improved alternative safety mechanism, by providing the quick couplers of the excavating machines with a simple and effective safety system, thus presenting the advantage of eliminating human intervention on the coupler and eliminating the possibility of the quick coupler releasing the accessory after the safety system is activated, i.e., by activating the locking plate (11) the rear latch (7) is prevented from retracting. The rear latch (7) holds the rear pin (5) of the accessory (3) and prevents it from being released. The front latch (6) is then operated, thus locking the front pin (4) on the accessory (3). The rear latch (7) has a retaining element (13) which is welded to it, preventing the locking plate (11) from proceeding with its movement, latching it.

(1)

coupler;

(2)

excavator;

(3)

accessory;

(4)

front pin;

(5)

rear pin;

(6)

front latch;

(7)

rear latch;

(8)

hydraulic drive cylinder;

(9)

hydraulic safety cylinder;

(10)

connecting bar;

(11)

locking plate;

(12)

warning device.

Figure 1 - cross-section view of the present invention where the following components and their spatial relationship can be observed: coupler (1); front pin (4); rear pin (5); front latch (6); rear latch (7); hydraulic drive cylinder (8); hydraulic safety cylinder (9) and connecting bar (10).

Figure 2 - rear view of the present invention.

Figure 3 - top view of the present invention.

Figure 4 - perspective view of the present invention, where the following components and their spatial relationship can be observed: coupler (1); front pin (4); rear pin (5); front latch (6); rear latch (7); hydraulic drive cylinder (8); hydraulic safety cylinder (9); connecting bar (10); locking plate (11) and warning device (12) .

Figure 5 - cross-section view of the present invention and in the position where the pins (4) (5) of an accessory (3) are not locked by the front (6) and rear (7) latches respectively.

Figure 6 - cross-section view of the present invention and in the position where the pins (4) (5) of an accessory (3) are locked by the front (6) and rear (7) latches respectively.

Figure 7 - Representation of a machine (2) with the quick coupler (1) which is the object of this invention, and of an accessory (3) with front (4) and rear pins (5).

This invention relates to a coupler (1) for accessories (3) of machines (2) such as, for example excavators, the said accessories comprising coupling pins. The coupler (1), for this purpose, has at least two hydraulic cylinders, one hydraulic drive cylinder (8) and one hydraulic safety cylinder (9). These cylinders are responsible for moving two latches (5)(6), one front safety latch (6) and one rear safety latch (7), which are connected by at least one connecting arm (10). One can say that the front (6) and rear (7) latches are the retention system of this invention.

The said connecting arm (10), in its turn, comprises two hinged bars, one of them having a right-angled geometry and which, at one end, the front one, is provided with means of articulation with the other hinged bar of the connecting arm (10) and, at the other end, the rear one, a locking plate (11).

The hydraulic cylinders (8) (9) are driven by a hydraulic non-return valve (not illustrated herein) that controls the inlet and the outlet, opening the oil outlet when there is pressure at the inlet, and which, in case a tube of one of the cylinders bursts, causes it to not move back, since the hydraulic non-return valve keeps the oil inside the cylinders.

The hydraulic cylinders (8) (9), when actuated, move the connecting arm (10), which closes the latches (6) (7), locking the two pins (4) (5) of the accessory (3), respectively, with the said locking occurring simultaneously.

The hydraulic drive cylinder (8) starts its linear displacement and on an axis perpendicular to the one of the safety cylinder (9), and when doing so, it actuates both the front (6) and rear (7) latches. Simultaneously to this movement, the hydraulic safety cylinder (9) acts promoting the movement of the connecting arm (10) until the locking plate (11) is positioned where the front (5) and rear (6) latches are mechanically locked. This mechanical locking is achieved through a retaining element (13), welded to the rear lock (7), which prevents the locking plate (11) from continuing the movement, that is, it latches the locking plate (11). In this position, even if the cylinders (8) (9) are not actuated, the safety system does not allow the latches (6)(7) to be deactivated.

Thus, when positioning the quick coupler (1) on at least two pins (4) (5) of an accessory (3) of a machine (2), the rear latch (7) holds the rear pin (5) of the accessory (3) thus preventing it from being released. The front latch (6) is then actuated, locking the front pin (4) on the accessory.

The latches (6) (5) also serve as a visual alert to the machine operator, since it is possible to view the latches engaging in the pins (4) (5). However, in a preferred embodiment of the invention, it comprises a warning device (12), which is aimed at warning the operator about the status of the quick coupler (1). This warning device (12) is attached to the shaft that connects to the hydraulic cylinder (9) and is solidary with it, i.e., the shaft rotation movement causes the warning device (12) to move.