EP2876303B1 - Lifting gripper for a valve element of a compressor valve - Google Patents

Description

The invention relates to a lift-off gripper for a valve element of a compressor valve, comprising a number of gripper fingers made of a first material and a carrier bush made of a second material, and a method for producing a same Abhebergreifers.

Lifting grippers are known in a variety of designs and are used to control plate and ring valves for compressors and the like. Lifting grippers are basically used to prevent the closing of the corresponding valve and thus to allow the backflow of the medium to be compressed from the compressor chamber, usually in the suction chamber. By permanently holding open the promotion of the compressor can be stopped, or the idling of the compressor can be realized. Furthermore, the lifting of valve elements is often used to start the compressor with minimal load, or to realize a continuous control of the compressor.

Due to the high load and the high dynamics, most grippers are made from solid. By turning, milling and sawing operations more than 80% of the starting material is machined. The solid-made grippers are sturdy and highly resistant to vibration but, due to the high material and manufacturing costs, they are very expensive.

As a cheaper variant shows, for example, the DE15 03 426 A1 a Abhebegreifer, which consists of a metallic bush, concentric gripper rings, star-shaped ribs and, cooperate with a valve plate, gripper fingers. The bush is manufactured in a conventional manner by turning or casting. The concentric gripper rings carry, cooperating with the valve plate, metallic gripper fingers and are connected by the star-shaped ribs with each other, as well as with the socket. The cohesion of the individual components is ensured by welded joints. To ensure accessibility during the joining process, only a small number of star-shaped ribs is continuous, from the outermost gripper rings to the socket executed. Nevertheless, to ensure sufficient rigidity, the outer gripper rings are connected by additional, short ribs.

A disadvantage is to be considered that for the production of a wealth of welding operations, with a high expenditure of time, are necessary. Furthermore, it should be noted that the bush must be made of a metallic material, which allows welding by welding. Thereon based on the sliding properties can be based on a non-optimal material pairing between the socket and the associated guide pin on the valve based. This disadvantage is particularly relevant in dry running applications where lubrication can not be performed for a variety of reasons. The thermal distortion in the course of joining may require reworking of the bushing, in particular the guide surfaces. Since all components of the Abhebegreifers are made of metal, further results in a correspondingly high weight, whereby the possible dynamics is limited accordingly.

The EP 0 686 770 B1 shows a lift-off gripper for compressor valves with a carrier, and a number of gripper fingers mounted thereon. The gripper fingers are equipped on their, the carrier-facing side, with a form-fitting cooperating with the carrier holding element. This holding element has a positioning element, as well as a snapping in the mounting position fixing. The center of the carrier is formed as a bushing, through which the carrier is guided on a guide sleeve. In order to improve the leadership, or to reduce the friction losses, slip rings are provided within the guide sleeve.

A disadvantage is the complex design of the guide area in order to ensure also in dry running applications for correspondingly positive sliding conditions. The limited choice of material for the gripper fingers, which must have both sufficient strength for the operation, as well as a corresponding elasticity for the snap connection is to be regarded as disadvantageous. Compared to the variant described above in which the gripper is made from solid, although the material cost is significantly reduced by the multi-part structure may result from the burden of the gripper fingers play, especially at the contact surfaces between the gripper fingers and the carrier. Although is compared to the mentioned DE15 03 426 A1 The weight is reduced to a small extent, yet the massive metallic carrier and the bushing formed on it also due to its weight also only a limited dynamics.

The EP 1 936 194 A1 shows a lifting gripper, which is equipped with a non-rotating and concentrically arranged anti-rotation sleeve with a non-circular outer contour.

An object of the present invention is to be able to produce for a valve element of a compressor valve a lifting gripper of the type mentioned in reducing the weight as inexpensively as possible and to avoid wear, such as the occurrence of play between gripper fingers and their support structure.

This object is achieved by means of a lift-off gripper according to claim 1, characterized in that the gripper finger is made of a first material and is connected to a valve member facing the central region with a power transmission ring, wherein the carrier bush made by a casting process from a second material is and the gripper fingers, and the power transmission ring are at least partially encapsulated by the material of the carrier bushing. Due to the multi-part structure and at least partially pouring the gripper finger can the Abhebegreifer be manufactured with minimal material costs. Due to the fact that the gripper finger is at least partially cast into the carrier bushing, the occurrence of play between the gripper finger and the carrier structure in the form of the carrier bush is virtually eliminated. The casting technique allows further, a material-reduced design, which effectively weight can be saved. Depending on the choice of material, this effect can be even greater.

An advantageous embodiment provides that the carrier bush has a guide area for guiding the lift-off gripper. The guide area is therefore already made when casting the carrier bush and the subsequent introduction of any bushings or slip rings is not necessary. As a result, the number of components and the assembly cost is reduced, which in turn saves costs.

It is advantageously provided that the guide region is arranged on the radially inner circumferential surface of the carrier bush. This allows a simple and space-saving design, in which the Abhebegreifer, for example, is guided on a central guide pin.

An advantageous embodiment provides that the carrier bushing is made of plastic or fiber-reinforced plastic. This allows a construction with the lowest weight but still high strength. This, compared to metallic materials, low weight allows a high operating dynamics. If, as already stated, the guide region is formed by the carrier bushing, excellent sliding conditions result, especially in dry running applications. Therefore, can be dispensed with the use of sliding elements on a guide pin of the lift-off gripper, whereby the construction is simplified accordingly.

It is the gripper finger connected to a, the valve element facing the central region with a power transmission ring. As a result, the forces acting on the gripper fingers are not discharged directly into the carrier bushing. The power transmission ring thus gives the lift-off gripper additional stability and rigidity.

An advantageous embodiment provides that the gripper finger on its the valve element facing the central region has a groove and that the gripper finger is hooked by means of the groove at a first contact point between the power transmission ring and gripper fingers in the power transmission ring. By hooking on the first contact point between the power transmission ring and gripper finger on the power transmission ring of the gripper fingers is positioned accordingly without fixing or connecting elements such as screws or the like are necessary. Will the cast elements such as screws or the like are necessary. If the casting process for the production of the carrier bushing is carried out after the hooking, and the already positioned power transmission ring, at least partially encapsulated.

An advantageous embodiment provides that the gripper finger is connected to a, the valve element facing away from the axial end with a cover ring. The forces occurring at the gripper fingers are discharged via the, the valve element facing away from the axial end in the closing ring. As a result, the bush is relieved and the Abhebegreifer is given additional, additional stability.

It is advantageously provided that the gripper finger has a recess at its axial end facing away from the valve element, that the end ring has a circumferential projection as a second contact point between the end ring and gripper finger on its outer or inner radial peripheral surface, which with respect to the recess of the gripper finger cooperates, that the gripper finger engages with its recess in the circumferential projection and thus in the end ring. The hooking is an easy way to position the end ring and fix without having to provide appropriate fixing elements, such as screws or the like. Other components are therefore eliminated, which reduces costs. Aligning any through holes or tapped holes, as would be necessary when using screws for fixing, is eliminated.

An advantageous embodiment provides that the gripper finger and the power transmission ring at least at the first contact point between the power transmission ring and gripper fingers and / or the gripper fingers and the end ring at least at the second contact point between the end ring and gripper fingers are at least partially encapsulated by the material of the carrier bushing. This ensures a secure cohesion of all components in a simple manner.

A further advantageous embodiment provides that the carrier bushing has a section with non-circular cross-section. Since the gripper fingers are guided through corresponding slots in the valve seat, which are interrupted by radial webs, it is basically necessary to prevent the gripper fingers, as a result of rotation, coming into contact with the radial webs of the valve seat. This would lead to undesirable wear on the valve seat and the gripper fingers, possibly both damage or a possible malfunction, due to increased friction, the result. By a non-circular cross-section can be effectively prevented when using a correspondingly shaped, with respect to the valve seat, rotationally fixed counterpart twisting.

A common, multi-part design, for example by screwed onto the valve seat plastic blocks caused, in contrast, significant additional costs and increased assembly costs.

An advantageous embodiment provides that the guide region of the carrier bush is designed as a non-circular section. This is in combination with a corresponding guide pin, which is provided for guiding the Abhebegreifers, realized in accordance with a corresponding cross section, in addition to the guide and a rotation.

• Fig.1 eine Schnittdarstellung des erfindungsgemäßen Abhebegreifers,
• Fig.2 eine Schnittdarstellung des vorteilhaft ausgeführten, vormontierten Abhebegreifers,
• Fig.3 einen Schnitt entlang der Linie III-III in Figur 2,
• Fig.4 eine Schnittdarstellung des fertig ausgeführten Abhebegreifers in einer vorteilhaften Ausgestaltung,
• Fig.5 einen Schnitt entlang der Linie V-V in Figur 4,
• Fig.6 eine perspektivische Ansicht des Abhebegreifers in Kombination mit einem Verdichterventil,
• Fig.7 den Abhebegreifer, aufgesetzt auf ein Verdichterventil, in einer Draufsicht nach Ansicht A in Figur 6,
• Fig.8 den Abhebegreifer innerhalb eines Kolbenverdichters.

The subject invention will be described below with reference to the FIGS. 1 to 8 explained in more detail, the exemplary, schematic and not limiting advantageous embodiments of the invention show. It shows

• Fig.1 a sectional view of the unloading gripper according to the invention,
• Fig.2 a sectional view of the advantageous executed, preassembled lift-off gripper,
• Figure 3 a section along the line III-III in FIG. 2 .
• Figure 4 a sectional view of the completed Abhebegreifers in an advantageous embodiment,
• Figure 5 a section along the line VV in FIG. 4 .
• Figure 6 a perspective view of the lift-off gripper in combination with a compressor valve,
• Figure 7 the lift-off gripper, mounted on a compressor valve, in a plan view according to view A in FIG. 6 .
• Figure 8 the lift-off gripper within a reciprocating compressor.

FIG. 1 shows a Abhebegreifer invention 1. In the illustrated embodiment, a plurality of gripper fingers 2, for example, six, apply. By a casting process, such as die casting or injection molding, a carrier bushing 14 is formed, wherein the gripper fingers 2 are at least partially encapsulated by the material of the carrier bushing. The material from which the carrier bushing 14 is cast does not necessarily have to be the same material from which the gripper fingers 2 are made, although this possibility is of course not excluded.

For the gripper fingers 2, a metallic material, such as a steel alloy may be provided, which has corresponding durability and wear resistance, with other materials are not excluded. Metallic materials may also be provided for the carrier bushing 14, preferably with good sliding properties, such as bronze alloys, ie alloys with a high copper and tin content, since these alloys have good sliding properties and high resistance to material fatigue. In order to achieve the lowest possible total weight, the use of plastics, such as polyamides, which may additionally be made fiber-reinforced, is possible, in particular for the carrier bush 14. These have high strength, rigidity and also toughness with good sliding properties. Of course, other materials or material combinations can be used.

FIG. 2 shows an advantageous embodiment of the lifting gripper 1 according to the invention in a pre-assembled stage. In the illustrated embodiment, the gripper fingers 2 with one, a in FIG. 6 shown valve member 30 facing the central region 3 with a power transmission ring 6 at the first contact points 7 between the power transmission ring 6 and gripper fingers 2 connected (see also FIG. 3 ). The power transmission ring is preferably made of metal. The first contact points 7 between the power transmission ring 6 and gripper fingers 2 are executed on the power transmission ring 6 in the form of contact surfaces 8. Furthermore, each gripper finger 2 has at its central region 3 a groove 5, whose depth and width to the contact surfaces 8 of the power transmission ring 6 is designed to fit.

The gripper fingers 2 are hooked by means of their grooves 5 at each one of the first contact points 7 between the power transmission ring 6 and gripper fingers 2 and are positioned over the contact surfaces 8. Due to the fact that the bottom of the grooves 5 comes to rest on the upper side of the power transmission ring 6 facing away from the valve element 30, which also constitutes a contact surface 8, the axial position of the gripper fingers 2 is fixed. By hooking the gripper fingers 2 are positioned on the power transmission ring 6 in position.

Each gripper finger 2 is further, at its, the valve member 30 facing away from, axial end 4, connected to a cover ring 10. For this purpose, the gripper fingers 2 at their axial end 4 at a second contact point 11 between the closing ring 10 and gripper fingers 2 each have a recess 9, for example, an inwardly or outwardly facing groove on. The end ring 10 has at the second contact points 11 between the end ring 10 and gripper fingers 2 at its inner or outer radial peripheral surface on a circumferential projection 12, which with respect to the recess 9 of each gripper finger 2 to the effect cooperates, that the gripper fingers 2 engage with their recesses 9 in the circumferential projection 12 and thus in the end ring 10.

Of course, a design in which is dispensed to the power transmission ring 6 and / or on the end ring 10, conceivable. If the force transmission ring 6 is dispensed with, the central area 3 of the gripper finger 2 does not have to have a groove 5, as is also the case in FIG FIG. 1 is shown. If the terminating ring 10 is dispensed with, the gripper finger 2 at its axial end 4 facing away from the valve element 30 does not have to have a recess 9 on its inner or outer radial peripheral surface, as already described in FIG FIG. 1 is shown.

As already mentioned, the gripper fingers 2 are already positioned by hooking on the power transmission ring 6 in a certain position. As a result of the recess 9, the wall thickness of the gripper fingers 2 is reduced at the second contact point 11 between the end ring 10 and gripper fingers 2, which allows a certain elastic deformation. This allows the closing ring 10 to snap in at the second contact point 11 between the closing ring 10 and the gripper finger 2.

That way, in FIG. 2 shown, preassembled lifting gripper 1 already has a certain cohesion of the individual components, which facilitates the handling of the not yet fully developed Abhebegreifers 1 in the following step.

The illustrated embodiment of the first contact point 7 between the power transmission ring 6 and gripper fingers 2 and the second contact point 11 between the end ring 10 and gripper fingers 2 represents a simple variant that can be produced with low manufacturing costs and allows quick and easy installation. Of course, other positive and / or non-positive embodiments in the configuration of the first contact point 7 between the power transmission ring 6 and gripper fingers 2 and the second contact point 11 between the end ring 10 and gripper fingers 2, for example by appropriate thread, other forms of connectors or the like possible.

FIG. 3 shows a section along the line III-III in FIG. 2 , By way of example, the power transmission ring 6 is designed for six gripper fingers 2 with corresponding contact surfaces 8 in a regular arrangement.

The power transmission ring 6 is performed, for example, at the first contact point 7 between the power transmission ring 6 and gripper fingers 2 by groove-shaped recesses 12 on the outer and / or inner peripheral surface of the power transmission ring 6. The resulting contact surfaces 8 are formed in the bottom of the groove-shaped recesses 12, and at the top of the power transmission ring 6. At the edges formed on the groove bottom of groove-shaped recesses 12 which adjoin the contact surfaces 8, arcuate recesses 13 are provided through which free spaces 19 between the power transmission ring 6 and the central portion 3 of the gripper fingers 2 are formed at the first contact point 7 between the power transmission ring 6 and gripper fingers 2. The advantage of the arcuate recesses 13 and the spaces 19 formed by them will become apparent in the following description FIG. 4 detailed. The gripper fingers 2 are hooked into the power transmission ring 6, so that the inner surfaces of the grooves 5 abut against the contact surfaces 8 and the gripper fingers 2 are positioned in the radial and axial directions.

FIG. 4 shows a sectional view of a completed Abhebegreifers 1 in an advantageous embodiment. As already at FIG. 1 is described by a casting process, such as die casting or injection molding, in which the already described, located in a preassembled stage Abhebegreifer 1 after FIG. 2 is introduced into a corresponding mold, the carrier bush 14 formed. The gripper fingers 2, the power transmission ring 6 and the end ring 10 are at least partially encapsulated by the material of the support sleeve 14. Through the encapsulation of the individual components, the secure cohesion of the individual components is ensured, wherein the forces acting on the gripper fingers 2 during operation of the lift-off gripper 1 are absorbed primarily by the force-transmitting ring 6 and the closing ring 10. In order to ensure the best possible integration of the gripper fingers 2 in the support sleeve 14, at least one breakthrough 16 may be provided in those areas of the gripper fingers 2, which is 14 flows through and filled in the course of the casting of the support sleeve. As in FIG. 1 However, a presence of a breakthrough 16 is not necessarily recognizable.

The already at FIG. 3 described, arcuate recesses 13 at the, formed on the groove bottom, inner edges of the groove-shaped recesses 12, which adjoin the contact surfaces 8, allow the material of the support sleeve 14, the central region 3 of the gripper fingers 2 and the power transmission ring 6 at the first contact point 7 between the power transmission ring 6 and gripper fingers 2 to flow well during the casting and also, the valve element 30 facing the underside of the power transmission ring 6 to at least partially encapsulate. As a result, any loosening of the power transmission ring 6, during operation, effectively prevented and in turn ensures a secure cohesion of all components.

For the same reason, the second contact point 11 between the end ring 10 and gripper fingers 2 is at least partially encapsulated by the material of the carrier bush 14. In order to ensure a better cohesion between the carrier bushing 14 and the end ring 10, at the outer radial peripheral surface of the end ring at least partially circumferential grooves or grooves 15 are provided, which are at least partially encapsulated by the material of the carrier bush 14.

The carrier bush 14 has at its radially inner peripheral surface a guide region 17, which in combination with a guide pin 32 (as in FIG. 6 shown) for guiding the Abhebegreifers 1 is used. By way of example, the carrier bush 14 is made of plastic or fiber-reinforced plastic, preferably a tribologically favorable plastic, which results in excellent sliding conditions on the guide region 17, especially in dry-running applications. The use of sliding elements on the guide pin 32 of the Abhebegreifers 1 can therefore be dispensed with, whereby the construction is simplified accordingly.

FIG. 5 shows a section along the line VV in FIG. 4 , FIG. 5 basically shows the already in FIG. 3 shown construction, but in the finished situation. In this case, the free spaces 19 are poured out at the first contact point 7 between the power transmission ring 6 and gripper fingers 2 through the material of the carrier bushing 14. As a result, no relative movement is possible between the central region 3 of the gripper fingers 2 and the power transmission ring 6. The gripper fingers 2 are free of play and without the use of any fixing elements, such as screws or the like, connected to the power transmission ring 6. The same naturally also applies to the second contact point 11 between the closing ring 10 and gripper fingers 2.

Basically, as already in the description of FIG. 2 mentioned, other possibilities in the formation of the first contact point 7 between the power transmission ring 6 and gripper fingers 2 possible. For example, with a corresponding embodiment of the first contact points 7 between the power transmission ring 6 and gripper fingers 2, also a subsequent, so after completion of casting process, screwing the power transmission ring 6 in the central region 3 of the gripper fingers 2 and 14 in the carrier bush conceivable.

FIG. 6 shows a perspective view of the lift-off gripper 1 in combination with a compressor valve 40 as it finds application, for example, in reciprocating compressors. A compressor valve 40 usually consists of valve seat 20, valve element 30 and valve catcher 31. The gripper fingers 2 are guided through corresponding slots 21 in the valve seat 20, which are interrupted by radial webs 22. It is fundamentally advantageous to prevent the gripper fingers 2 from coming into contact with the radial webs 22 of the valve seat 20 as a result of rotation. This would lead to undesirable wear on the valve seat 20 and the gripper fingers 2, possibly both damage or have a possible malfunction due to increased friction result. The carrier bushing 14 may therefore have a section 18 of non-circular cross-section, which exemplifies with the Guide area 17 coincides. The radial peripheral surface of the guide pin 32 is made equal to the non-circular cross section of the guide portion 17 of the bushing 14, wherein the guide pin 32 is rotationally fixed with respect to the compressor valve 40. Due to the interaction of the circumferential surface of the guide pin 32 and the non-circular cross-section of the portion 18 of the support sleeve 14, a rotation of the Abhebegreifers 1 relative to the valve seat 20 is prevented. Section 18 may also be formed with its non-circular cross-section at a different location of the radially inner peripheral surface of the support bush and does not necessarily coincide with the guide portion 17.

FIG. 7 shows the lift-off gripper 1, placed on the compressor valve 40, in a plan view according to view A in FIG. 6 , The gripper fingers 2 are guided through the slots 21 through the valve seat. The non-circular cross-section of the portion 18, which, as in FIG. 6 explained, an undesired rotation of the Abhebegreifers 1 relative to the valve seat 20 and thus prevents contact of the gripper fingers 2 with the radial webs 22 is clearly visible in the center of the carrier bushing 14.

FIG. 8 shows the lifting gripper 1 in the activated position, when it is used in a reciprocating compressor 50, which consists of at least one compressor valve (40) with at least one valve element (30) and which is shown only schematically. The gripper fingers 2 protrude through the valve seat 20 and push the valve member 30 against the spring force of the springs 33 against the valve catcher 31. Only schematically, the actuator 34 is shown via which the Abhebegreifer 1 is operated.

As a result of the illustrated, activated position of the lifting gripper 1, a compression medium is pushed back, for example in the suction chamber 36 by the upward movement of the piston 35. This has the consequence that the delivery rate and thus also the power consumption of the reciprocating compressor 50 is reduced, this effect can be used, for example, in the course of idle control or during startup with minimal load.

Claims (12)

1. Unloader (1) for a valve element (30) of a compressor valve (40), comprising at least one unloader finger (2) being fabricated of a first material and a carrier bushing (14) being fabricated of a second material, characterized in that the unloader finger (2) is joined to a force transmitting ring (6) at a central area (3) that faces the valve element (30), wherein the carrier bushing (14) is fabricated using a casting method, and the unloader finger (2) as well as the force transmitting ring (6) are at least in part mould in with the material of the carrier bushing (14).
2. Unloader (1) in accordance with claim 1, characterized in that the carrier bushing (14) has a guide area (17) for guiding the unloader (1).
3. Unloader (1) in accordance with claim 2, characterized in that the guide area (17) is arranged on the radially interior circumferential surface of the carrier bushing (14).
4. Unloader (1) in accordance with any of claims 1 through 3, characterized in that the carrier bushing (14) is fabricated from plastic or fiber-reinforced plastic.
5. Unloader (1) in accordance with any of claims 1 through claim 4, characterized in that the unloader finger (2) has a groove (5) on its central area (3) that faces the valve element (30) and that the unloader finger (2) is hooked by means of the groove (5) to a first contact point (7) between force transmitting ring (6) and unloader finger (2) in the force transmitting ring (6).
6. Unloader (1) in accordance with any of claims 1 through 5, characterized in that at least one axial end (4) that faces away from the valve element (30) the unloader finger (2) is joined to a connection ring (10).
7. Unloader (1) in accordance with claim 6, characterized in that at its axial end (4) that faces away from the valve element (30) the unloader finger (2) has a recess (9) and in that the connection ring (10) has as a second contact point (11) between connection ring (10) and unloader finger (2) on its exterior or interior radial circumferential surface a circumferential projection (12) that cooperates with the recess (9) of the unloader finger such that the recess (9) of the unloader finger engages in the circumferential projection (12) and thus in the connection ring (10).
8. Unloader (1) in accordance with at least one of claims 5 or 7, characterized in that the unloader finger (2) and the force transmitting ring (6) are mould in at least at the first contact point (7) between force transmitting ring (6) and unloader finger (2) and/or the unloader finger (2) and the connection ring (10) are mould in at least at the second contact point (11) between connection ring (10) and unloader finger (2), at least in part, with the material of the carrier bushing (14).
9. Unloader (1) in accordance with at least one of claims 1 through 8, characterized in that the carrier bushing (14) has a segment (18) with a non-circular cross-section.
10. Unloader (1) in accordance with claim 9, characterized in that the guide area (17) of the carrier bushing (14) is embodied as a non-circular segment (18).
11. Method for fabricating a unloader (1) for a valve element (30) of a compressor valve (40), comprising at least one unloader finger (2) being fabricated of a first material and a carrier bushing (14) being fabricated of a second material, characterized in that the unloader finger (2) is joined to a force transmitting ring (6) at a central area (3) that faces the valve element (30) and that the carrier bushing (14) is fabricated using a casting method and the unloader finger (2) and force transmitting ring(6) are at least in part mould in with the material of the carrier bushing (14).
12. Reciprocating compressor (50) comprising at least one compressor valve (40) having at least one valve element (30) and one unloader (1) cooperating therewith, characterized in that the unloader (1) is embodied in accordance with at least one of claims 1 through 10.

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