Pulse wiper and wiper arrangement

Description

[0001] The invention relates to an impulse wiper according to the preamble of claim 1 and a wiper arrangement with such an impulse wiper.

[0002] Such an impulse wiper is known, for example, from GB 473 449 A.

[0003] Wipers are established in many areas of technology and are primarily used to remove dirt, chips, moisture, and other foreign particles from pistons or piston rods before they retract into the cylinder. This prevents contamination of the bearing gap between the components or the hydraulic medium, as well as damage to guides, seals, and other components of the wiper assembly. Such wiper assemblies are critical components in hydraulic systems of cranes and other construction machinery, for example. So-called double or tandem wipers with two or more wiper lips are also available on the market. These can have the same or opposite main directions of action.

[0004] The aforementioned wipers must exhibit favorable friction properties and the greatest possible wear resistance when combined with the material to be wiped. The wipers used in practice may not be able to remove strongly adhering foreign particles, particularly ice or dried-on contaminants, from the piston rod, or may only do so incompletely. In this case, the contaminants may be introduced into the bearing gap.

[0005] The one-piece metal wiper disclosed in GB 473 449 A has an outer wiper lip and two inner wiper lips, each of which is separated from the other by an annular groove therebetween.

[0006] It is therefore the object of the invention to provide a wiper and a wiper arrangement in which problematic foreign bodies that adhere strongly to the mating surface of a machine part to be wiped off can be wiped off more reliably.

[0007] The object concerning the wiper is achieved according to the invention by an impulse wiper according to claim 1. The wiper arrangement has the features specified in claim 10. Further advantages of the invention will become apparent from the description and the drawing.

[0008] The impulse wiper according to the invention is intended for removing a foreign body from the counter-running surface of a machine part, in particular a piston rod, and comprises a holding section for mounting the impulse wiper in / on a holding structure, in particular a holding groove, of a machine part. The impulse wiper further comprises a wiper lip with a wiper edge circumferentially extending relative to the central axis of the impulse wiper for dynamically contacting and removing the foreign body from the counter-running surface of another machine part.

[0009] According to the invention, the wiper lip is elastically deformable and has one or more annular grooves on its circumferential side facing away from the holding section, each of which defines a desired bending zone of the wiper lip, wherein the wiper lip itself forms a functional axial stop for a longitudinal segment of the wiper lip arranged distal to the axial stop.

[0010] If, during operation of the impulse wiper - derived from the (return stroke) movement of the piston rod - a foreign body adhering to the piston rod is guided against the wiper edge of the impulse wiper, this causes an axial deformation or deflection movement of the wiper lip, which is suddenly limited or inhibited by the axial stop. This allows a mechanical wiper impulse or breakaway force to be exerted on the foreign body by means of the wiper lip. This wiper impulse or breakaway force can remove even problematic foreign bodies that adhere particularly strongly to the piston rod, such as ice, dried-on dirt or the like, even more reliably from the piston rod, i.e. wipe them off. During a return stroke movement of the piston rod, the unwanted entry of such foreign bodies into the bearing gap can be prevented even more reliably.This is beneficial overall for the functionality and longevity of a wiper assembly equipped with an impulse wiper. This makes the impulse wiper particularly suitable for critical applications where malfunctions of the wiper assembly, which could potentially result in personal injury or property damage, must be prevented at all costs, such as in construction machinery, cranes, and the like.

[0011] The scraper edge can in particular be made of a material with a Shore hardness between 80 Shore A and 70 Shore D.

[0012] According to a particularly preferred embodiment of the invention, the wiper lip has a plurality of annular grooves arranged at a distance from one another in an axial direction relative to the central axis of the pulse wiper. The annular grooves can have a depth and / or axial width that increases with increasing distance of the respective annular groove from the wiper edge.

[0013] According to a particularly preferred embodiment of the invention, each annular groove of the wiper lip tapers or narrows radially toward the retaining section. This allows the response of the wiper lip to be adjusted particularly easily and reliably when subjected to an axial force acting on the wiper edge.

[0014] To further improve the scraping performance of the impulse wiper, the scraping edge can be designed with a corrugated or serrated design along its circumference. This minimizes the contact area of ​​the scraping edge with a foreign body and allows for particularly high scraping forces to be applied.

[0015] The impulse wiper can further comprise a second wiper lip, which has either a main direction of action that coincides with the first wiper edge or a direction opposite to the first wiper edge. In the former case, the wiping effect of the impulse wiper can be increased in the main direction of action of the first wiper edge. In the latter case, it can retain foreign bodies that have already penetrated the bearing gap, or even the lubricant located in the bearing gap.

[0016] If there is an annular free space extending radially between any two of the pulse wiper's wiper lips, foreign objects and the like can become trapped there. A free space is defined as a volume in which no component of the pulse wiper is located.

[0017] The wiper lip can further comprise a support element arranged axially spaced from the wiper edge and extending radially from the wiper lip. Such a support element allows the impulse wiper to bear against the counter-running surface, thus counteracting an undesirable tilting moment acting on the impulse wiper. The support element is preferably integrally formed with the wiper lip. Particularly preferably, the support element has a spherical cross-sectional shape.

[0018] The wiper arrangement according to the invention comprises a first machine part in the form of a piston or a piston rod and a second machine part, preferably in the form of a cylinder, which encompasses the first machine part. The two machine parts are arranged at a distance from one another, forming a bearing gap, and are movable relative to one another along a movement axis. One of the two machine parts has a sliding or counter-running surface, and the other of the two machine parts has a holding structure, in particular in the form of a holding groove, in which the holding section of an impulse wiper explained above is arranged and held. The wiper lip of the impulse wiper rests at least partially against the counter-running surface of one machine part (circumferentially).

[0019] If the wiper lip has one or more of the aforementioned annular grooves, a forward stroke of one machine part can cause a lubricant located in the bearing gap to be drawn into each of the weakened areas of the material. A return stroke of the machine part causes friction-induced deformation of the wiper lip, resulting in the lubricant being forced out of each annular groove of the wiper lip radially toward the counter-running surface. Each annular groove therefore has a dual function.

[0020] The invention is explained in more detail below with reference to exemplary embodiments illustrated in the drawings. The embodiments shown and described are not to be understood as an exhaustive list, but rather as examples for describing the invention.

[0021] The drawing shows: Fig. 1 shows a scraper arrangement with a piston rod and a machine part encompassing the piston rod, here a cylinder, as well as with an impulse scraper for the piston rod arranged between the two machine parts, wherein the impulse scraper has a circumferential material weakening in the form of an annular notch (= annular groove), through which a desired bending point of the scraper lip and a stop for the longitudinal segment of the scraper lip arranged distal to the annular notch are defined, in a partial sectional view; Fig. 2 shows an impulse scraper which differs from the one in Fig. 1 shown impulse wiper essentially in that it has several spaced-apart material weakenings in the form of annular notches on the circumference, which differ from one another in size; Fig. 3 shows a further (not claimed) impulse wiper, in which the wiper lip has a support element with an exponentially progressive spring characteristic, in a partial sectional view; Fig. 4 shows a further (not claimed) impulse wiper, in which the wiper lip has two wiper edges with opposing main directions of action and a support element with an exponentially progressive spring characteristic, in a partial sectional view; Fig.5 shows a further (unclaimed) impulse wiper, in which the wiper lip is attached to the holding section solely via a support element, wherein the holding element has an exponentially progressive spring characteristic and forms a functional stop for an axial deflection movement of the support element hinged to the holding section and of the wiper lip; Fig. 6 shows a further (unclaimed) impulse wiper, in which the wiper lip is attached to the holding section solely via a support element, wherein the holding element has an exponentially progressive spring characteristic and forms a functional stop for an axial deflection movement of the support element hinged to the holding section and of the wiper lip, in a partial sectional view; Fig. 7 shows a notched wiper edge of an impulse wiper in a perspective detailed view; Fig.8 shows a wave-shaped scraper edge of an impulse wiper in a perspective detailed view; and Fig. 9 shows an exponentially progressive spring characteristic of a holding element according to . Fig. 5 or a supporting element according to the Fign. 3 , 4 and 6 .

[0022] Fig. 1 shows a first embodiment of a wiper arrangement according to the invention 10. The scraper arrangement 10 comprises a first machine part 12, here exemplified in the form of a piston rod, and a second machine part surrounding the piston rod 14, here, for example, in the form of a cylinder. The two machine parts 12, 14 are arranged to form a bearing gap between the two machine parts 12, 14 16 arranged at a distance from each other. The wiper arrangement 10 and the bearing gap 16 have an outer side N and an inside HIn the bearing gap 16, a lubricant (in Fig. 1 not shown). The first machine part 12 is arranged along a movement axis L reciprocating relative to the second machine part 14. A forward stroke movement of the piston rod is V and a return stroke of the piston rod is possible with R designated.

[0023] The second machine part 14 has a holding structure 18 , which is designed here as a retaining groove. A pulse wiper is used to remove impurities or foreign bodies adhering to the piston rod 19. 20.

[0024] The impulse wiper 20 has a mounting or holding section 22 which is arranged in the holding groove of the second machine part 14. A wiper lip extends from the holding section 22 24in a direction axial to the central axis Z of the impulse wiper 20. The wiper lip 24 is provided here with a single circumferentially closed wiper edge of the impulse wiper 20. 26 which allows dynamic contact and wiping of the counter surface 28 the piston rod. The scraper edge 26 has an edge angle pointing in the axial direction towards the outside N a between 50° and 75° and an edge angle pointing in the axial direction to the inside H β between 15 and 45°. The main functional direction of the scraper edge is indicated by the arrow 30 designated.

[0025] According to Fig. 1 the wiper lip 24 has on its circumferential side facing away from the holding section 22, ie here radially inward 32 a single ring-shaped material weakening in the form of an annular groove 34 The annular groove 34 has an axial width band a radial depth t of at least 30% of the local thickness d the wiper lip 24.

[0026] This material weakening or annular groove 34 has three functions: If, during operation, a foreign body 19 adhering to the counter-running surface of the piston rod, such as snow, chips, ice, dirt, and the like, is guided against the wiper lip during a return stroke of the piston rod, an axial force FA is exerted on the wiper lip. The material weakening serves as a desired bending zone. 36 the wiper lip 24. This axial force FA causes an elastic deformation (= compression) of the wiper lip 24 in the axial direction as well as a bending (kinking) of the wiper lip 24 primarily in the area of ​​the desired bending zone 36.

[0027] Secondly, due to the weakening of the material, an integral stop 38for the distal, ie axially in the main direction of action of the associated scraper edge, arranged longitudinal segment 24a the wiper lip 24. The integral stop 38 is formed by the first groove flank facing the outer side N 34a the annular groove 34. If the distal longitudinal segment 24a of the wiper lip 24 strikes the second groove flank facing the bearing gap 16 34b on the opposite first groove flank 34a, this counteracts further axial deformation of the wiper lip 24. Due to the sudden increase in resistance to further deformation, a stripping impulse or a breakaway force derived from the return stroke movement R of the piston rod acts on the wiper edge 26. The sealing lip deforms upon detachment of the foreign body 19 or several foreign bodies 19 in its Fig. 1 The piston rod suddenly returns to the normal operating state shown in the radial / axial direction. Overall, foreign bodies 19 on the piston rod can be wiped off particularly effectively in this way. This reliably counteracts the unwanted ingress of foreign particles 19 into the bearing gap 16 and the associated risks of damage to other components of the wiper arrangement 10.

[0028] Thirdly, the material weakening can act as a lubricant reservoir 40serve. During a forward stroke movement V of the piston rod, lubricating fluid adhering to the piston rod can be introduced or drawn into the material weakening or annular groove 34. During a return stroke movement R of the piston rod, at least part of the lubricating fluid stored in the material weakening can be released back to the piston rod. This is particularly the case when the wiper lip 24 is deformed in the axial direction due to friction between the wiper edge 26 and the counter-running surface 28 of the piston rod, thereby reducing the axial width b of the material weakening, i.e. squeezing the lubricating fluid out of the material weakening. During a subsequent forward stroke movement V, the material weakening is then filled with lubricant again. This enables even better all-round lubrication of the piston rod or the wiper lip.Undesirable adhesion of rust and the like as well as corrosion of the piston rod itself can thus be counteracted particularly reliably even when the piston rod is extended from the second machine part 14.

[0029] It should be noted that the impulse wiper 20 has a support section 42 which is arranged at a distance from the scraper edge 26 in the axial direction and which (at least temporarily) bears against the counter-running surface 28. During operation, the support section 42 can be supported on the counter-running surface 28 and thus counteract a tilting moment acting on the impulse wiper 20. The support section 42 is designed here purely by way of example as a spherical annular bead which has no sealing effect and may well have one or more axial passages in the circumferential direction. Other geometric designs of the support section are readily conceivable.

[0030] The wiper lip 24 of the impulse wiper 20 can be arranged according to the Fig. 2 In the illustrated embodiment, the wiper lip 24 can also have a plurality of material weakenings arranged at a distance from one another in the axial direction. Each of the material weakenings is preferably designed as an annular groove 34 and has the functional advantages explained above. Each material weakening or annular groove 34 of the wiper lip 24 can narrow in the radial direction during normal operation of the impulse wiper 20. The depth t of the material weakenings can increase with increasing distance of the respective material weakening from the wiper edge 26.

[0031] It should be noted that the material weakening can also be formed or filled with a highly compressible soft material with a low modulus of elasticity compared to the rest of the wiper lip 24. An open-pore elastomer foam is particularly suitable for this purpose.

[0032] According to the Fig. 3 In the embodiment shown (not claimed), the wiper lip 24 of the impulse wiper 20 is arranged held on a support element 44. The support element 44 can be designed as a reinforcement insert of the wiper lip 24. The wiper lip can in particular be injection-molded onto the support element. The support element 44 extends here from the holding section 22 in a radial direction up to the level or almost to the level of the wiper edge 26. It should be noted that the material of the support element 44 can have a greater modulus of elasticity than the material of the remaining wiper lip 24. The support element 44 can comprise metal 25, plastic and / or a composite material or consist of one of these materials. The support element 44 is inherently resiliently deformable and has an exponentially progressive spring characteristic with regard to its axial deformation, see also the following explanations regarding Fig. 8 The support element 44 thus serves as a spring-elastic energy storage device with a progressive spring characteristic. In other words, the axial force FA required for deformation of the support element in the axial direction increases abruptly with increasing deformation of the support element. This functionally creates an axial stop for the axial deformation of the support element 44 and thus an axial deflection movement of the wiper lip 24 toward the inner side H, through which a wiper impulse or breakaway torque can be exerted on a foreign body adhering to the piston rod—derived from the return stroke movement of the piston rod.

[0033] If the spring force of the support element 44 exceeds the axial force FA at the time of stripping (detaching) the foreign body 19 adhering to the piston rod, the wiper lip 24 springs axially in the direction of the outer side N into its Fig. 3 shown operating position.

[0034] The scraper edge 26 can have a convex curved line shape towards the outside in cross section and in the normal operating state shown can form an angle with the counter surface 28 of the piston rod y with preferably 60° ≤ y ≤ 80°.

[0035] In the Fig. 4 In the detailed section of a (not claimed) impulse wiper 20 in the assembled state shown, the support element 44 is also designed as a resiliently deformable reinforcing insert of the viscoelastic material of the wiper lip 24. The support element 44 is designed here with an arcuately curved cross-sectional shape in cross section. The wiper lip 24 has a second wiper edge 26, which is arranged axially offset from the first wiper edge 26 in the direction of the inner side H. Both wiper edges 26 are made of the same material. The second wiper edge 26 has an inwardly directed main direction of action opposite to the outwardly directed main direction of action 30 of the first wiper edge 26. 30' on.

[0036] It should be noted that the support element 44 itself has an effective edge 46with a wiping function. The effective edge 46 preferably does not touch the counter-running surface 28 during normal operation in order to avoid damage to the counter-running surface. In this respect, the effective edge is preferably provided with only a small distance (in Fig. 4 The wiper lip 24 is arranged at a distance of less than 1 millimeter, for example, from the counter-running surface 28. This makes it possible to more reliably counteract the entry of larger, particularly hard, foreign bodies 19 adhering to the first machine part 12 (= piston rod) into the bearing gap 16. If the wiper lip 24 has a free space 48 formed between the first and second wiper edges 26, such foreign bodies 19 that have overcome the first wiper edge 26, as well as lubricant, can be absorbed or deposited there.

[0037] In Fig. 5 a further (not claimed) impulse wiper 20 is shown, in which the wiper lip 24 is held by a support element 44. The support element 44 is articulated at one end to the holding section 22 of the impulse wiper 20 in a spring-elastic manner. The support element 44 can be designed to be rigid, ie essentially non-deformable, against the axial forces FA occurring during operation of the impulse wiper or according to the method described in connection with Fig. 4 explained embodiment have an exponentially progressive spring characteristic. Here, the holding section 22 is in any case elastically deformable and has an exponentially progressive spring characteristic with respect to deformation. Fig. 5 In the embodiment shown, the axial stop of a (deflection) movement of the wiper lip in the axial direction is thus functionally effected by the holding section 22. The holding section 22 can in particular comprise or consist of an elastomer.

[0038] The wiper lip 24 can have a first and a second wiper edge 26, whose main directions of action 30, 30' can be opposite to each other. The impulse wiper is thus designed as a so-called double wiper. The wiper lip 24 and preferably also the holding section are made of a rubber-elastic or viscoelastically deformable material. The Shore hardness of the soft material can be, in particular, between 80 Shore A and 70 Shore D.

[0039] The support element 44 extends in the radial direction into a free space 48 formed between the two scraper edges 26 to such an extent that the support element 44 almost touches the counter-running surface 28 of the piston rod.

[0040] If, in this impulse wiper 20, a foreign body 19 adhering to the counter-running surface 28 is guided against the externally arranged wiper edge 26 / wiper lip 24 during a return stroke movement R of the piston rod, this results in an axial force FA acting on the wiper edge 26. This axial force FA causes an elastic deflection of the support element together with the wiper lip 24 relative to the holding section 22. As a result, the wiper edge 26 is pivoted more strongly against the counter-running surface 28. When the functional stop is reached, i.e. there is a sudden increase in the force required to deform the holding element, a wiper pulse or a breakaway force is exerted on the foreign body 19 by means of the wiper lip 24.If the spring force of the holding element 22 exceeds the axial force FA at the moment the foreign body 19 breaks away from the counter-running surface 28, the support element 44 together with the wiper lip 24 springs back in the axial direction into its position shown in . Fig. 5 Return to the starting position shown.

[0041] In the Fig. 6 In the embodiment shown (not claimed), the support element 44, which here is in a form similar to that shown in Fig. 4 The stripping lip 24 is designed in an arcuate manner corresponding to the exemplary embodiment shown and serves as a resiliently deformable reinforcing insert for the stripping lip 24. The stripping lip 24 can be made of metal, a viscoelastic hard plastic, or a composite material. The Shore hardness of the material of the support element 44 can be, for example, between 95 Shore A and 70 Shore D. The stripping lip 24 here has three stripping edges 26, which are arranged spaced apart from one another in the axial direction and have opposing main directions of action 30, 30'. The material of the stripping lip is preferably softer or viscoelastically deformable compared to the support element.

[0042] According to the Fign. 7 and 8 The scraper edge 26 of the scraper lip 24 can be notched or wave-shaped and recesses 50This allows the wiping function of the wiping lip 24 to be further improved, particularly with regard to particularly hard foreign bodies or those that adhere particularly firmly to the counter-running surface.

[0043] Fig. 9 shows an example of an exponentially progressive characteristic curve K of the spring-elastic support element 44 according to the Fign. 3 , 4 and 6 or the spring-elastic holding section 22 according to Fig. 5 , through which the functional stop described above 38 caused or formed.

Claims

1. An impulse scraper (20) for scraping a foreign particle (19) off the mating running surface (28) of a machine part, comprising a holding section (22) for mounting the impulse scraper (20) in a holding structure (19) of a machine part (12, 14), and a scraper lip (24), extending away from the holding section (22) in an axial direction with respect to the central axis (Z) of the impulse scraper (20), with a scraper edge (26), extending around the central axis (Z) of the impulse scraper (20), for dynamically contacting and scraping the foreign particle (19) off the mating running surface (28) of another machine part (12, 14), wherein the scraper lip (24) is intrinsically elastically deformable and, on its radial inner peripheral side facing away from the holding section (22), has one or more, preferably ring-shaped circumferential, annular groove(s) (34), characterized in that the annular groove(s) (34) each define a predetermined bending zone (36) of the scraper lip (24), and the first groove flank (34a) of the annular groove (34) which faces the scraper edge (26) forms an axial stop (38) for the opposite second groove flank (34b) of the annular groove (34) of a longitudinal segment (24a, 24b) of the scraper lip (24) arranged distally with respect to the axial stop (38), such that an axial force (FA) which acts on the scraper lip (24) in the axial direction towards the holding section (22) and is caused by a foreign particle (19) adhering to the mating running surface (28), leads to a deflection of the scraper lip (24) primarily in the region of the predetermined bending zone (36) until the second groove flank (34b) abuts the first groove flank (34a).

2. The impulse scraper as claimed in claim 1, characterized in that the scraper edge (26) consists of a material with a hardness of between 80 Shore A and 70 Shore D.

3. The impulse scraper as claimed in any one of the preceding claims, characterized in that the scraper edge (26) is of wavy or serrated design.

4. The impulse scraper as claimed in any one of the preceding claims, characterized in that the impulse scraper (20) has a plurality of scraper lips (24) and / or scraper edges (26).

5. The impulse scraper as claimed in claim 4, characterized in that a first and a second scraper lip (24) have mutually opposite main directions of action (30, 30').

6. The impulse scraper as claimed in claim 1, characterized in that the scraper lip (24) has a plurality of annular grooves (34), which are arranged spaced apart in the axial direction.

7. The impulse scraper as claimed in claim 6, characterized in that each annular groove (34) of the scraper lip (24) narrows in a radial direction.

8. The impulse scraper as claimed in claim 7, characterized in that the annular grooves (34) each have a radial depth (t) which increases with increasing distance from the scraper edge (26).

9. The impulse scraper as claimed in any one of the preceding claims, characterized in that the impulse scraper (20) has a supporting section (42) arranged at an axial distance from the scraper edge (26) in order to counteract a tilting moment acting on the impulse scraper (20) while being supported on the mating running surface (28) during the operational use of the impulse scraper (20).

10. A scraper arrangement (10) comprising a first machine part (12) and a second machine part (14) which fits around the first machine part (12), which machine parts (12, 14) are arranged spaced apart, forming a bearing gap (16), wherein one of the two machine parts (12, 14) has a holding structure (18) in which an impulse scraper (20) as claimed in any one of the preceding claims is arranged in such a way as to be held, and wherein the at least one scraper lip (24) of the impulse scraper (20) rests against the mating running surface (28) of the respective other machine part (12, 14) while making dynamic contact, wherein a foreign particle (19) adhering to the mating running surface (28) causes an axial force (FA) acting on the scraper lip (24), which leads to deformation and / or deflection of the scraper lip (24) in the axial direction relative to the holding section (22) until a mechanical scraping impulse acting on the foreign particle (19) can be brought about by the axial stop (38) in order to scrape the foreign particle (19) off the mating running surface.

11. The scraper arrangement (10) as claimed in claim 10, characterized in that the annular groove (34) of the scraper lip (24) serves as a lubricant reservoir (40) and, owing to friction, a deformation or compression of the scraper lip (24) and, associated with this, pressing of the lubricant out of the annular groove (34) radially in the direction of the machine part (12, 14) that has the mating running surface (28) is brought about during a relative movement of the two machine parts (12, 14).