Pressure-limiting valve

Abstract

A pressure-limiting valve has a valve housing, a piston, a pressure-limiting adjustment spring, at least one inlet and at least one outlet. The piston can assume an open position in which the inlet and the outlet are connected to each other and a closed position which separates the inlet and outlet. A first piston ring has a sealing surface and has a small pneumatic active surface relative to a second piston ring. Between the first and second piston rings the piston has a substantially truncated cone-like portion which tapers toward the first piston ring. In the closed position, the sealing surface of the first piston ring is sealingly drawn against a housing collar by a pneumatic force acting counter to the force of the pressure-limiting adjustment spring. A pneumatic passage for creating a safety valve function closable by a spring-loaded safety valve body is provided in the piston.

Claims

1. A pressure-limiting valve comprising a valve housing, a valve piston and a pressure-limiting adjusting spring, wherein at least one valve inlet and at least one valve outlet are provided in the valve housing, wherein the valve piston can assume an open position, in which the valve inlet and the valve outlet are connected to one another, and at least one closed position, in which the valve inlet and the valve outlet are separated from one another, wherein the valve piston has a first piston ring with a sealing face and a second piston ring, the first piston ring has a pneumatic active surface smaller than a pneumatic active surface of the second piston ring, between the first piston ring and the second piston ring the valve piston has a truncated cone-shaped section which tapers in the direction of the first piston ring, in the closed position the sealing face of the first piston ring is pulled in a sealing manner against a housing lip by a pneumatic force acting on the first piston ring and second piston ring against a force of the pressure-limiting adjusting spring, the valve piston includes a pneumatic passage closable by a spring-loaded safety valve body, and wherein the pressure-limiting adjusting spring is set against the second piston ring on a side of the second piston ring opposite from the first piston ring.

2. The pressure-limiting valve as claimed in claim 1, wherein only a portion of a radial face of the first piston ring is guided in the valve housing.

3. The pressure-limiting valve as claimed in claim 2, wherein a sealing face of the first piston ring is arranged in the radial face of the first piston ring.

4. The pressure-limiting valve as claimed in claim 3, wherein the sealing face of the first piston ring is formed by at least one of an O-ring and a vulcanized-on sealing element.

5. The pressure-limiting valve as claimed in claim 4, wherein the second piston ring has a radial face which is guided in the valve housing, and a sealing ring is provided in the radial face of the second piston ring.

6. The pressure-limiting valve as claimed in claim 5, wherein the sealing ring in the radial face of the second piston ring is formed by at least one of an O-ring and a vulcanized-on sealing element.

7. The pressure-limiting valve as claimed in claim 6, wherein the safety valve body is spring-loaded by the pressure-limiting adjusting spring.

8. The pressure-limiting valve as claimed in claim 7, wherein when in a closed position, the safety valve body bears in a sealing manner against the sealing ring of the second piston ring.

9. The pressure-limiting valve as claimed in claim 8, wherein the safety valve body is guided in the valve housing.

10. The pressure-limiting valve as claimed in claim 1, wherein the safety valve body is arranged in an interior of the valve piston.

11. The pressure-limiting valve as claimed in claim 10, wherein the safety valve body has a safety valve body sealing ring configured to close in a sealing manner the pneumatic passage when the safety valve body is in a closed position.

12. The pressure-limiting valve as claimed in claim 11, wherein the safety valve body has a safety valve body spring which biases the safety valve body against the pneumatic passage when the safety valve body is in a closed position.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a schematic sectional drawing of a first embodiment of an embodiment according to the invention of a pressure-limiting valve.

(2) FIG. 2 shows a schematic sectional drawing of a second embodiment of an embodiment according to the invention of a pressure-limiting valve.

(3) FIG. 3 shows a schematic sectional drawing of a third embodiment of an embodiment according to the invention of a pressure-limiting valve.

DETAILED DESCRIPTION OF THE DRAWINGS

(4) FIG. 1 shows a sectional illustration of a first embodiment of a pressure-limiting valve 10 according to the invention.

(5) The pressure-limiting valve 10 is a pressure-limiting valve 10 in accordance with the pulling shut principle.

(6) The pressure-limiting valve 10 has a valve housing 12 comprising a radially arranged valve inlet 14, a valve outlet 16 and a valve piston 18.

(7) The valve outlet 16 is axially arranged and, in the closed position shown of the pressure-limiting valve 10, closed by a portion of the valve piston 18, specifically by the first piston ring 20.

(8) In addition to the first piston ring 20, the valve piston 18 has a second piston ring 22.

(9) The second piston ring 22 has, by way of one of its axial faces, specifically the axial face which faces the first piston ring 20, a pneumatically active face. For its part, this axial face is, in the open position of the pressure-limiting valve 10, also provided for moving toward the housing lip 24, as a result of which the maximum opening of the valve outlet 16 is defined.

(10) A pneumatic passage 26, which is formed by as a centrally arranged passage bore, is provided in the valve piston 18.

(11) The spring force of a pressure-limiting adjusting spring 28, the upper end of which is set against the second piston ring 22, acts on the valve piston 18.

(12) The pressure-limiting adjusting spring 28 is therefore set against the second piston ring 22 on that side of the second piston ring 22 which is averted from the first piston ring 20.

(13) The valve housing 12 has an outer stop 30 which is formed by an outer housing face and the inner edge of which jointly delimits the valve outlet 16.

(14) In the interior of the valve piston 18, a safety valve body 32 is guided in a recess 38, it being possible to close the pneumatic passage 26 by said safety valve body.

(15) In this recess 38, the valve body 18 also has a guide 34 into which a portion of the safety valve body 32 can engage. In the embodiment shown in FIG. 1 and in the position shown, the safety valve body 32 engages into the guide 34 or is guided in said guide.

(16) The safety valve body can be a rotary part which is composed of plastic.

(17) The recess 38 is closed by a stopper 35 at that end of the valve piston 18 which faces the pressure-limiting adjusting spring 28. This stopper 35 has through-passages 36 which serve to allow compressed air to pass through in connection with the safety valve function.

(18) A sealing face 40 of the first piston ring 20 is arranged in the radial face of the first piston ring 20. The sealing face 40 of the first piston ring 20 can be formed by an O-ring (as shown) or by a vulcanized-on sealing element.

(19) The second piston ring 22 has a radial face which is guided in the valve housing 12. A sealing ring 42 is provided in this radial face of the second piston ring 22.

(20) As shown in FIG. 1, the sealing ring 42 can be formed by an O-ring or by a vulcanized-on sealing element.

(21) In the position shown in FIG. 1, the valve outlet 16 is closed in a leaktight manner, specifically by the first piston ring 20 and the sealing face 40 of said first piston ring.

(22) Only a portion of the radial face of the first piston ring 20 is guided in the valve housing 12, specifically that portion of the radial face of the first piston ring 20 which faces the valve housing. In the closed position, the sealing face 40 moves toward stop 30.

(23) The sealing face 40 with a round or, for example, alternatively an oval cross section, formed either by an O-ring or by a vulcanized-on sealing element, is pulled toward the stop 30 in such a way that the gap which is located between the valve housing 12 and the first piston ring 20 is securely closed in a leaktight manner.

(24) This is additionally further assisted by the elastic deformation of the sealing face 40.

(25) The shaping of the sealing face 40 with the round or oval cross section also assists in the sealing face 40 bearing cleanly against the stop 30.

(26) The annular space which is formed between the first piston ring 20 and the second piston ring 22 is sealed off in relation to the pressure-limiting adjusting spring 28 by the sealing ring 42.

(27) Furthermore, the safety valve body 32 has a safety valve body sealing face 44 which, together with the safety valve body 32, closes off the pneumatic passage 26 in a sealing manner in the closed position. The safety valve body 32 therefore has a safety valve body sealing ring by which the pneumatic passage 26 can be closed off in a sealing manner or is closed off here, in the closed position shown.

(28) The safety valve body 32 is spring-loaded by a spring 46 guided through the stopper 35 by way of one of its ends and through a recess 38 in the safety valve body 32 by way of its other end.

(29) The spring 46 is a separate safety valve body spring 33 which sets the safety valve body 32 against the pneumatic passage 26 in a closed position of the safety valve body 32.

(30) The valve piston 18 is of truncated cone-like design between the first piston ring 20 and the second piston ring 22, that is to say it has a substantially truncated cone-like section here.

(31) This truncated cone-like section tapers starting from the second piston ring 22 in the direction of the first piston ring 20.

(32) Owing to this increase in diameter, the first piston ring 20 acquires a smaller pneumatic active face than the second piston ring 22.

(33) The through-passages 36 are connected to a safety valve outlet 48, not shown in any detail, which is located in the region of the pressure-limiting adjusting spring 28.

(34) The functioning of the pressure-limiting valve 10 can be described as follows:

(35) In the open state of the pressure-limiting valve 10 (not shown), compressed air, for example, flows across the valve inlet 14. The force which engages on the first piston ring 20 and the spring force of the pressure-limiting adjusting spring 28 ensure that the valve piston 18 is pushed against the housing lip 24 by way of the second piston ring 22 and as a result the valve inlet 14 is connected to the valve outlet 16.

(36) If the compressed air flowing in across the valve inlet 14 exceeds a certain presettable limit pressure (the limit pressure being adjustable by the pressure-limiting adjusting spring 28 and, for example, a known adjusting element, such as an adjusting screw (not illustrated in any detail)), the resulting force produced from the different sizes of the pneumatically active faces of the first piston ring 20 and of the second piston ring 22 and also from the spring of the pressure-limiting adjusting spring 28 pushes the valve piston 18 against the direction of the spring force of the pressure-limiting adjusting spring 28, counter to the pneumatic force which acts on the pneumatically active face of the first piston ring 20 owing to the action of the compressed air. As a result, the sealing face 40 of the first piston ring 20 is pushed in a sealing manner against the stop 30 and the valve outlet 16 is closed in this way. As a result, the pressure on the other side of the valve outlet is limited to the limit pressure to which the pressure-limiting valve 10 is adjusted.

(37) If, for example in the event of a fault, the pressure on the valve outlet side now exceeds a prespecified safety pressure, the safety function of the pressure-limiting valve 10 comes into effect. In this case, the applied pneumatic pressure pushes open the safety valve body 32, which is spring-loaded by the spring 46, and in this way opens the pneumatic passage 26. The compressed air can escape across the safety valve outlet 48 via the through passages 36.

(38) FIG. 2 shows a further embodiment of a pressure-limiting valve 10 according to the invention.

(39) The pressure-limiting valve 10 substantially exhibits all of the structural and functional features of the pressure-limiting valve 10 shown in FIG. 1 and described above, however with the exception of the differences described below.

(40) Identical elements are therefore identified by identical reference symbols.

(41) However, the pressure-limiting valve 10 shown in FIG. 2 has the following differences:

(42) A safety valve body 32 in the form of a sealing plate is provided instead of the stopper 35 and the separate spring 46.

(43) The safety valve body 32 is directly spring-loaded by the pressure-limiting adjusting spring 28 and adjusted toward the second piston ring 22. Therefore, the safety valve body 32 is spring-loaded by the pressure-limiting adjusting spring 28.

(44) In addition, the safety valve body 32 is guided in the valve housing 12.

(45) Here, the second piston ring 22 also has a guide 34 in which a circumferential guide ring 35 is guided.

(46) In this case, the safety valve body 32 is set against the second piston ring 22 in such a way that it can also be set directly against the sealing ring 42 at the same time in order to be able to close the pneumatic passage 26 in a sealing manner.

(47) Therefore, in a closed position, the safety valve body 32 bears against the sealing ring 42 of the second piston ring 22 in a sealing manner.

(48) FIG. 3 shows a further embodiment of a pressure-limiting valve 10 which is virtually identical to the embodiment of the pressure-limiting valve 10 shown in FIG. 2.

(49) The pressure-limiting valve 10 therefore exhibits substantially all of the structural and functional features of the pressure-limiting valve 10 and, respectively, 10 shown in FIGS. 1 and 2 and described above, however with the exception of the differences described below.

(50) Here, an additional sealing ring 50 is additionally provided on the circumferential guide ring 35, said additional sealing ring sealing the safety valve body 32 against the second piston ring 22.

(51) It is also conceivable in principle that the sealing ring 50 is held in the second piston ring 22.

(52) The sealing ring 50 can be formed by an O-ring or by a vulcanized-on sealing element.

(53) The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.

LIST OF REFERENCE NUMERALS

(54) 10 Pressure-limiting valve 10 Pressure-limiting valve 10 Pressure-limiting valve 12 Valve housing 14 Valve inlet 16 Valve outlet 18 Valve piston 20 First piston ring 22 Second piston ring 24 Housing lip 26 Pneumatic passage 28 Pressure-limiting adjusting spring 30 Stop 32 Safety valve body 32 Safety valve body 32 Safety valve body 34 Guide 34 Guide 35 Stopper 35 Circumferential guide ring 36 Through-passage 38 Recess 40 Sealing face 42 Sealing ring 44 Safety valve body sealing face 46 Spring 48 Safety valve outlet 50 Sealing ring