DE20111182U1 - Spring element for a piston - Google Patents

Description

ALCAN BDW GmbH Attorney file: 26093

D-85570 Markt Schwaben

German utility model

Spring element for a piston

DESCRIPTION:

The present invention relates to a spring element for a piston, in particular for a piston compressor for gaseous media, with a spring body with an outer circumference and an opening formed centrally in the spring body for receiving a connecting element for connecting a valve plate to a piston plate, wherein the spring element has a curved cross-section and rests with its convex underside on the piston plate in the region of the opening and is held with its concave upper side in the region of the opening by a central part of the valve plate, wherein the upwardly curved outer circumference of the spring body rests against an annular piston head and the piston head is designed to be movable against the piston plate.

Such spring elements are well known. They are placed between a piston plate and a corresponding piston head or valve plate and are intended to provide so-called start-up protection. This means that the spring elements must create an initial pressure equalization when a piston starts to run against pressure. In particular, it must be ensured that the motor current of the motor driving the piston does not become too high when the piston starts to run against the pressure. If the motor current exceeds a certain limit, the

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predetermined value, the motor driving the piston is automatically switched off via fuses.

The disadvantage of the known spring elements, however, is that these spring elements cannot be permanently loaded and lose their spring effect. In particular, the spring effect or spring tension is lost when the spring element and the other piston elements are attached using a corresponding connecting element, such as a rivet, screw or similar, or when the contact and effective surface of the spring element acts on the spring element.

It is therefore an object of the present invention to provide a spring element of the type mentioned above which can be permanently loaded and at the same time ensures a reliable spring effect.

This problem is solved by a spring element with the features of claim 1.

Advantageous embodiments are described in the subclaims.

In a spring element according to the invention, a spring body has at least one recess spaced from a central opening, the distance between the recess and the opening being selected such that the recess is arranged outside a support and active surface of a connecting element or borders on it or partially overlaps it. Such a design of the spring element ensures that at least a partial area of the spring element or the spring body is not influenced and pressed down by the connecting element for connecting a valve plate to a piston plate or its support and active surface. In the spring element areas located outside the support and active surface of the connecting element, which are also advantageously separated from the support and active surface by at least one recess, the spring effect is reliably maintained, so that the long-term load capacity of the spring element is guaranteed.

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In an advantageous embodiment of the invention, the recess is designed as an opening that penetrates the spring body. However, it is also possible for the recess to be designed as a groove that does not penetrate the spring body. The first embodiment ensures simple production of the spring element, e.g. by means of a punching process. The last embodiment advantageously offers the option of making the recess on the top or bottom of the spring body, i.e. on the concave or convex side of the spring body.

&iacgr;&ogr; In a further advantageous embodiment of the invention, the recess is semicircular, rectangular, square, wedge-shaped or round. Other shapes of the recess are also conceivable.

In a further advantageous embodiment of the spring element according to the invention, at least two recesses are arranged symmetrically around the central opening. The symmetrical arrangement of several recesses around the central opening advantageously ensures an even distribution of the spring effect.

In a further advantageous embodiment of the invention, the outer circumference of the spring element rests against an annular inner groove of the piston head. This ensures that the spring element sits firmly on the piston head.

Further details, features and advantages of the invention emerge from the following description of an embodiment shown in the figures. They show:

Figure 1 is a schematic sectional view of a piston with a

spring element according to the invention;

Figure 2 is a schematic sectional view of a portion of the piston according to Figure 1; and

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Figure 3 is a schematic representation of the spring element according to the invention.

Figure 1 shows a schematic representation of a piston 44 with a spring element 10. The spring element 10 has a ring- and disk-shaped spring body 12 with an outer circumference 20 and an opening 14 formed centrally in the spring body 12 for receiving a connecting element 22. The connecting element 22 is shown in the embodiment as a rivet and serves to connect a valve plate 24 to a piston plate 34 and to fasten

Î on the piston rod 36. Other connecting elements such as screws or similar are also conceivable. It is also possible for the piston rod 36 to have a corresponding nose on the side facing the piston 44, which protrudes through an opening 46 in the valve plate 24, the opening 14 in the spring element 10 and an opening 42 in the valve plate 24. On the side facing the valve plate 24, this nose can achieve the corresponding connecting effect by means of a fastening element or by riveting.

It can be seen that the spring element 10 has a curved cross-section and rests with a convex underside on the piston plate 34 in the area of the opening 14 (see also Figure 2). The concave upper side of the spring element 10 is held in the area of the opening 14 by a central part of the valve plate 24. It can also be seen that the upwardly curved outer circumference 20 of the spring body 12 rests against an annular piston head 28. The piston head 28 is designed to be movable against the piston plate 34. An annular seal 32 is formed between the piston head 28 and the valve plate 24. The valve plate 24 also has several passage openings 26 for the passage of a gaseous medium.

At the end opposite the piston 44, a bearing 40 is formed on the piston rod 36, which serves for connection to a drive device (not shown), in particular an electric motor.

Figure 2 shows a portion of the piston 44 according to Figure 1. It can be seen that the spring body 12 has at least one recess 16 spaced from the central opening 14. The distance between the recess 16 and the opening 14 is selected such that the recess 16 is arranged outside a support and active surface 38 of the connecting element 22. However, it is also possible for the recess to border on the support and active surface 38 or to partially overlap it. In the exemplary embodiment, the recess 16 is designed as an opening penetrating the spring body 12. It is clear from Figure 2 that the outer circumference 20 of the spring element 10 rests against an annular inner groove 30 of the piston head 28. In the exemplary embodiment, the piston head 28 is annular and formed as a single piece. However, it is also possible for a two-part piston head to be used.

Figure 3 shows a schematic representation of a spring element 10 with two semicircular recesses 16, 18 arranged symmetrically around the central opening 14. The recesses 16, 18 are in turn designed as openings penetrating the disk-shaped spring body 12. However, it is also possible for the recesses to be designed as grooves that do not penetrate the spring body. The shape of the recesses can also be varied. It is possible to use rectangular, square, wedge-shaped or round recesses. The spring element 10 is made of metal, a metal alloy or plastic.

Claims (8)

1. Spring element for a piston, in particular for a piston compressor for gaseous media, with a spring body ( 12 ) with an outer circumference ( 20 ) and an opening ( 14 ) formed centrally in the spring body ( 12 ) for receiving a connecting element ( 22 ) for connecting a valve plate ( 24 ) to a piston plate ( 34 ), wherein the spring element ( 10 ) has a curved cross-section and rests with its convex underside on the piston plate ( 34 ) in the region of the opening ( 14 ) and is held with its concave upper side in the region of the opening ( 14 ) by a central part of the valve plate ( 24 ), wherein the upwardly curved outer circumference ( 20 ) of the spring body ( 12 ) rests against an annular piston head ( 28 ) and the piston head ( 28 ) is designed to be movable against the piston plate ( 34 ), characterized that the spring body ( 12 ) has at least one recess ( 16 , 18 ) spaced from the central opening ( 14 ), wherein the distance between the recess ( 16 , 18 ) and the opening ( 14 ) is selected such that the recess ( 16 , 18 ) is arranged outside a support and active surface ( 38 ) of the connecting element ( 22 ) or borders on this or partially overlaps this. 2. Spring element according to claim 1, characterized in that the recess ( 16 , 18 ) is designed as an opening penetrating the spring body ( 12 ). 3. Spring element according to claim 1, characterized in that the recess ( 16 , 18 ) is designed as a groove which does not penetrate the spring body ( 12 ). 4. Spring element according to one of the preceding claims, characterized in that the recess ( 16 , 18 ) is semicircular, rectangular, square, wedge-shaped or round. 5. Spring element according to one of the preceding claims, characterized in that the at least two recesses ( 16 , 18 ) are arranged symmetrically around the central opening ( 14 ). 6. Spring element according to one of the preceding claims, characterized in that the spring body ( 12 ) is designed as an annular disk. 7. Spring element according to one of the preceding claims, characterized in that the outer circumference ( 20 ) of the spring element ( 10 ) rests against an annular inner groove ( 30 ) of the piston head ( 28 ). 8. Spring element according to one of the preceding claims, characterized in that the spring element ( 10 ) consists of metal, a metal alloy or plastic.