The present invention relates to a filtering apparatus comprising a vertical filter vessel, a cover and fastening means for fastening or clenching the cooperating contact surfaces of the vessel and the cover to each other for the closing of the cover, whereby the cover is connected to an arm which is rotatably mounted to the filter vessel and by means of which the cover can be lifted from the filter vessel and swung aside.

Such a filtering apparatus is known.

With the known filtering apparatus in or at the arm a pneumatic or hydraulic cylinder is provided, by the operation of which the arm lifts the cover from the vessel and lowers it. After the lifting of the cover the arm swings the cover sideways, after which the vessel is accessible.

With the known filtering apparatus the drawback occurs, that in the case of a malfunction in the hydraulic or pneumatic system the cover can suddenly fall a bit downwards, which can lead to an accident.

It is an object of the present invention to obviate this drawback of the known filtering apparatus.

The filtering apparatus according to the invention to that end is characterized in that the cover is connected to the arm by means of a supporting part which is fixedly connected to the arm and which is provided with a supporting plate having an opening through which a rod shaped part is led which rod shaped part at its bottom outer end is fixedly connected to the cover and with its upper outer end is fixedly connected to a holder plate provided above the supporting plate, while in the space between the supporting plate and the holder plate a spring is provided with a lead- through for the part, which spring at its" 'bottom side leans on the supporting plate and at its upper side leans against the holder plate, in such a way, that when the cover is moved downwards, towards the vessel, the part pulls the holder plate towards the supporting plate and makes the space or distance between the holder plate and the supporting plate smaller such that the spring is compressed, in such a way, that the moving towards each other of the cover and the vessel for the closing of the cover has to take place against spring force, while, when the fastening means are loosened for the opening of the cover, the cover is lifted from the vessel by the spring force.

According to a characteristic of the filtering apparatus according to the invention the supporting part is formed by a cylinder which at its upper side is covered by the supporting plate and in which cylinder the rod shaped part is slidable up and down, whereby a lower part of the rod shaped part is formed by a pipe connected at its bottom outer end to the cover and an upper part of the rod shaped part is formed by a pin connected at its upper outer end to the holder plate, whereby the diameter of the pipe is larger than the diameter of the opening in the supporting plate and whereby the diameter of the pin is smaller than the diameter of the opening in the supporting plate, such, that the path of movement of the pipe upwards in the cylinder is limited by the supporting plate, while the pin protrudes through the opening in the supporting plate and the lead-through in the spring means and is movable up and down therein.

According to a further characteristic of the filtering apparatus according to the invention the spring is enclosed in a sleeve provided around the holder plate and the supporting plate.

In an advantageous embodiment of the filtering apparatus according to the invention the spring is formed by a rubber spring.

With the apparatus according to the invention it is to a large extent prevented that the cover will suddenly fall downwards in case of a malfunction during the operation as a result of for instance a power failure or a defect in a cylinder.

The invention will now be described further with reference to the drawings of an example of an embodiment of the apparatus according to the invention. Figure 1 is a side view in section of a part of the filtering apparatus according to the invention.

Figure 2 is a side view partly in section of a part of the filtering apparatus according to the invention.

Figure 3 shows a detail Z of the apparatus shown in figure 2.

As can be seen in figure 1 the filtering apparatus 1 comprises a filter vessel 2, a cover 3 and cooperating contact surfaces 4, 5 of the vessel and the cover which can be fastened or clenched to each other by in itself known fastening means (not shown in the figure) for the closing of the cover 3 on the vessel 2. The cover 3 is connected to an arm 6 which is rotatably mounted to the filter vessel 2 and by means of which the cover 3 can be lifted from the filter vessel 2 and can be swung aside. As can be seen in the figures 1 and 2 the cover 3 is connected to the arm 6 by means of a supporting part, in this example of an embodiment a cylinder 7, which is laterally fixedly connected to the arm 6. The cylinder 7 at its upper side is covered by a supporting plate 8. The supporting plate 8 is provided with an opening 9 through which a rod shaped part 10 is led. In the example of the embodiment shown a lower part of the rod shaped part 10 is formed by a pipe 11 connected at its bottom outer end 12 to the cover 3 and an upper part of the rod shaped part 10 is formed by a pin 13 fixedly connected at its upper outer end 14 to a holder plate 15 provided above the supporting plate 8. In the space 16 between the supporting plate 8 and the holder plate 15 a rubber spring 17 is provided with a lead-through 18 for the pin 13. The diameter of the pipe 11 is larger than the diameter of the opening 9 in the supporting plate 8 while the diameter of the pin 13 is smaller than the diameter of the opening 9 in the supporting plate 8, such, that the path of movement of the pipe 11 upwards in the cylinder 7 is limited by the supporting plate 8. The pin 13 protrudes through the opening 9 in the supporting plate 8 and the lead-through opening 18 in the rubber spring 17 and is movable up and down therein. In the example of the embodiment shown the spring 15 is enclosed in a sleeve 19 provided around the holder plate 15 and the supporting plate 8. When the filtering apparatus 1 is being closed the cover 3 is pushed downwards towards the vessel 2 and the cooperating contact surfaces 4, 5 are clenched to each other by the fastening means. The pipe 11 mounted to the cover 3 with the pin 13 mounted to the holder plate 15 thereby draw the holder plate 15 in the direction towards the supporting plate 8, which causes the space 16 between the holder plate 15 and the supporting plate 8 to become smaller and which causes the spring 17 to be compressed. The closing of the cover 3 on the vessel 2 in this manner has to take place against spring force. When the fastening means are locked the cover 3 is secured to the vessel 2 and during the period of time that the vessel is closed the spring 17 will retain its compressed form under the holding power of the fastening means. When, on opening of the vessel 2, the fastening means are loosened again, the spring 17 will resume its original shape and the cover 3 is lifted by the spring force from the vessel 2.