Locking device for telescopic cylinder

Abstract

Locking device (10) for the telescopic cylinder of a telescopic boom comprising a plurality of telescopic stages. The locking device comprises a housing (12), at least one bolt (20) displaceably mounted in the housing for locking the telescopic cylinder with a telescopic stage, a yoke (30) displaceably mounted in the housing, which is movable into an unlocking position for releasing a locking bolt of the telescopic boom, and at least one blocking element (35), which blocks a movement of the bolt into its unlocking position when the yoke is in the unlocking position. The at least one bolt is preloaded into a locking position via at least one bolt return element (22) and can be displaced via at least one bolt actuator (24) into an unlocking position releasing the telescopic stage lock. The blocking element and the bolt can be at least partially displaced into a common insertion space of the housing. According to the invention, the bolt is preloaded into the locking position via at least two bolt return elements, wherein the blocking element is arranged between the bolt return elements as seen in the displacement direction of the yoke. The invention further relates to an implement, in particular a mobile crane, having a locking device according to the invention.

Description

[0001] The invention relates to a locking device for the telescoping cylinder of a telescopic boom comprising several telescopic sections according to the preamble of claim 1 and to a working device, in particular a mobile crane, with such a device.

[0002] Telescopic booms consist of an outer telescopic section (also called the base section or pivot section) and one or more inner telescopic sections that are slidably mounted within it. Such telescopic booms are used, for example, in mobile cranes. Especially with larger telescopic booms, a hydraulic telescoping cylinder is typically used to extend and retract the telescopic sections, sequentially extending and retracting the inner sections. For this purpose, part of the telescoping cylinder, typically its piston rod, is connected to the base of the outer telescopic section, while the other part, typically the cylinder itself, extends and retracts relative to the outer telescopic section by pressurizing the corresponding pressure chamber.

[0003] To move the individual telescopic sections, the telescoping cylinder must be temporarily connected to them. The typical solution for this involves a locking device (also called a locking head) on the telescoping cylinder, particularly at its piston rod end or collar. This locking device engages with several spring-loaded bolts that engage from the inside of the inner telescopic section to be extended, so that the telescopic section extends together with the telescoping cylinder.

[0004] The individual telescopic sections can also be locked to each other in defined extension positions by means of spring-loaded locking bolts on the telescopic sections. To unlock or lock the locking bolts for extending or retracting the telescopic sections, they can be engaged by the locking device and moved into an unlocked position. For this purpose, the locking device typically has a spring-returned yoke which can be engaged by pull tabs on rods of the locking bolts that project inwards into the telescopic sections.

[0005] The movement of the bolts and the yoke against the restoring forces into the respective unlocked position is effected, as is typical, by hydraulic actuators. Safety latches integrated into the yoke mechanism ensure that, in the unlocked position of the yoke, the bolts cannot be retracted simultaneously, thus holding the free or unlocked telescopic section in place by the telescoping cylinder. This is typically achieved by the safety latches blocking the travel of the bolts. When the yoke is in the locked position, the travel of the bolts is free, and they can be moved into the unlocked position by applying pressure to the corresponding actuators. The prior art document DE 20 2015 1010 45 U1 discloses the preamble of claim 1.

[0006] In devices of this type, the yoke is slidably mounted and guided within a housing of the locking device by means of several guide elements. In some known solutions, these guide elements are arranged outside the central plane defined by the longitudinal axes of the lateral bolts and the direction of movement of the yoke, while the locking bolts lie within this central plane. However, this requires a relatively large installation space and can lead to the yoke jamming in the housing. If the guide elements are to be relocated within the aforementioned central plane, a spatial conflict arises with the actuation and return mechanism of the bolts, which are typically pre-tensioned by centrally located return springs. Therefore, the return springs of the yoke must be arranged outside the central plane, which again requires a larger installation space.

[0007] The present invention therefore aims to avoid the disadvantages of the prior art and to develop it further in an advantageous manner. In particular, a locking device of this type for telescopic booms is intended to ensure good guidance of the yoke within the housing while making optimal use of the available space.

[0008] This problem is solved by a locking device having the features of claim 1. Advantageous embodiments of the invention are described in the dependent claims and the following description.

[0009] Accordingly, a locking device for the telescoping cylinder of a telescopic boom is proposed, comprising several telescopic sections mounted to slide within one another. The locking device includes a housing, at least one bolt slidably mounted within the housing for locking the telescoping cylinder to a telescopic section, a yoke slidably mounted within the housing which can be moved into an unlocking position to release a locking bolt of the telescopic boom, and at least one blocking element which blocks movement of the bolt into its unlocking position when the yoke is in the unlocking position. The at least one bolt is pre-tensioned into a locking position by at least one bolt return element and can be moved into an unlocking position that releases the telescopic section locking mechanism by at least one bolt actuator.The locking element and the bolt can be moved, at least partially, into a common insertion space in the housing.

[0010] The at least one locking element prevents both the yoke and the at least one bolt from being in the unlocked position simultaneously. This ensures that either all telescopic sections are locked together via one or more locking bolts, or that the locking device is locked to one of the inner telescopic sections, which is therefore held or secured by the telescoping cylinder. The yoke and the at least one bolt thus block each other, so that each of these elements can only be moved into the unlocked position when the other element is in the locked position.

[0011] According to the invention, the bolt is pre-tensioned into the locking position by means of at least two bolt return elements, with the blocking element being arranged between the bolt return elements when viewed in the direction of displacement of the yoke. The latter can also include the case where the blocking element is offset from the bolt return elements but arranged between their extended longitudinal axes. Preferably, however, the bolt return elements are actually arranged around the blocking element.

[0012] This configuration enables a compact design of the locking device, since the space previously occupied by the central bolt return spring in the area of ​​the bolt's longitudinal axis is now free and used for the blocking element. In contrast, known solutions required the locking bolts to be provided with special recesses, as the locking bolts and the central bolt return springs interfered with each other. In particular, the arrangement according to the invention makes it possible to position a yoke return element in the area of ​​the at least one blocking element, thereby achieving a very compact design.

[0013] At the same time, the configuration is very easy to assemble. Individual parts can be advantageously pre-assembled.

[0014] The bolt return elements are preferably springs or compression springs. These can be guided by spring pins. It is also conceivable that the springs can be pre-tensioned by screws before installation. This allows for safe assembly and maintenance of the system.

[0015] In In one possible embodiment, the at least one locking element is simultaneously designed as a guide element over which the yoke is guided in the housing. Preferably, the locking element has a guide section which is slidably mounted and guided in a guide in the housing. The guide section is preferably cylindrical.

[0016] The at least one locking element thus performs a dual function: on the one hand, it guides the yoke within the housing, and on the other hand, it blocks the unlocking movement of the bolts when the yoke is in the unlocked position. This combined function eliminates the need for any additional guide elements, apart from the at least one locking element, to support or guide the yoke within the housing. This results in a smaller footprint within the locking device.

[0017] Furthermore, the actuators for moving the yoke into the unlocked position (yoke actuators) can be arranged in the same plane as the locking element, which acts as a guide element. In contrast, prior art often provides an arrangement of the locking bolt and / or yoke actuators on the one hand and the guide elements on the other that is offset in the direction of displacement of the bolt. This results in improved guidance of the yoke in the housing, as no additional torque is introduced into the device that would reduce the smooth operation of the yoke.

[0018] The yoke actuators can, for example, be designed as plunger cylinders. Likewise, return elements that pre-tension the yoke in the locking device (yoke return elements), such as compression springs, do not in themselves constitute guide elements within the meaning of the invention. Rather, the guide elements of the locking device according to the invention primarily serve to guide the yoke precisely within the housing during movement from the locked position to the unlocked position and vice versa.

[0019] In another possible embodiment, the bolt return elements are arranged perpendicular to the longitudinal axis of the locking element. In particular, the bolt return elements are oriented parallel to the longitudinal axis or direction of displacement of the bolt.

[0020] Alternatively or additionally, the bolt return elements can extend at least partially within the insertion space. The at least one locking element can be at least partially surrounded by the bolt return elements, or the latter can be arranged on both sides of the locking element within the insertion space.

[0021] In another possible embodiment, the bolt is pre-tensioned into the locking position by means of at least two, preferably exactly four, bolt return elements. Preferably, the bolt return elements are arranged symmetrically to the longitudinal axis of the bolt or to a plane passing through the longitudinal axis of the bolt.

[0022] Alternatively or additionally, the bolt return elements are arranged symmetrically to the longitudinal axis of the locking element when viewed in the direction of displacement of the bolt. This includes the case where the bolt return elements are arranged symmetrically to a plane containing the longitudinal axis of the locking element, in particular symmetrically to a plane spanned by the longitudinal axis of the locking element and the longitudinal axis of the bolt.

[0023] In another possible embodiment, the yoke is pre-tensioned into a locking position by at least one yoke return element and is preferably displaceable into the unlocking position against the pre-tensioning force of the yoke return element by at least one yoke actuator. The yoke actuator can be configured to push the yoke into the unlocking position or to pull the yoke into the unlocking position. The yoke return element can be a compression spring.

[0024] InIn another possible embodiment, the locking element has a blocking section that, in the unlocked position of the yoke, projects into a travel path of the bolt in the insertion chamber and blocks movement of the bolt into its unlocked position. When the yoke is in the locked position, the blocking section lies outside the bolt's travel path. Preferably, the blocking section has no recess and / or a constant width when viewed from the side along the bolt's travel path.

[0025] The locking element preferably further comprises a contact section that is connected to or contacted by the at least one yoke actuator. The contact section preferably extends transversely to the longitudinal axis of the locking element. The locking element is connected to the yoke, such that pushing down (in the case of a "pushing" yoke actuator) or pulling down (in the case of a "pulling" yoke actuator) the contact section causes the yoke to move into the unlocked position. The contact section is preferably located above (if the side of the locking device on which the yoke is located is considered "above") the locking section.

[0026] In another possible embodiment, two yoke actuators are provided, which are preferably arranged symmetrically to the locking element when viewed in the direction of displacement of the bolt. Thus, the yoke actuators are located on both sides of the locking element when viewed in the direction of displacement of the bolt and are equidistant from it. This advantageously ensures that no additional torque is introduced into the locking element via the yoke actuators.

[0027] In another possible embodiment, the yoke return element is a compression spring arranged coaxially to the locking element. This results in a particularly space-saving arrangement, in which the compression spring acts axially on the locking element and is located within the insertion space between the bolt return elements. In particular, unlike in the prior art, it is not necessary to arrange several compression springs spaced apart from the locking element, which would increase the required installation space. Preferably, the compression spring is partially received in a spring receptacle of the locking element. The spring receptacle of the locking element can be realized by a recess open downwards (i.e., facing away from its attachment to the yoke), in which the compression spring sits.

[0028] Alternatively or additionally, the compression spring can be mounted or guided on a spring mandrel connected to the housing. Ideally, the compression spring can be pre-tensioned for easy installation using a pre-tensioning element, such as a threaded spindle. However, conventional installation is also possible.

[0029] In another possible embodiment, the yoke return element is arranged at least partially within the insertion space, with the bolt preferably having a recess on an end face facing the yoke return element. This recess, in the bolt's unlocked position, at least partially encloses or surrounds the yoke return element. Thus, the yoke return element itself does not block the bolt's movement into the unlocked position. The bolt's recess is particularly U-shaped and engages the yoke return element in the unlocked position. The locking element is preferably designed such that it cannot be engaged by the bolt's recess in the yoke's unlocked position; that is, it is wider than the recess. Alternatively, the locking section of the locking element can also block the bolt at a different location, for example, laterally to the recess.

[0030] Preferably, the recess or the locking element is designed such that the bolt, in its unlocked position, blocks the insertion of the locking element and thus a movement of the yoke into its unlocked position.

[0031] In another possible embodiment, the yoke actuator comprises or is a hydraulic cylinder, in particular a plunger cylinder. A plunger is particularly suitable for a space-saving arrangement within the structure of the locking device. In particular, it can be easily arranged above the insertion area, for example perpendicular to the bolt. Preferably, the locking element is actuated by two plungers.

[0032] In another possible embodiment, the bolt actuator comprises or is a hydraulic cylinder, in particular a plunger cylinder. Preferably, several plungers are provided for moving the bolt. Advantageously, the plungers are arranged symmetrically to the longitudinal axis of the locking element when viewed in the direction of displacement of the bolt. This includes the case where the plungers are arranged symmetrically to a plane containing the longitudinal axis of the locking element, in particular symmetrically to a plane spanned by the longitudinal axis of the locking element and the longitudinal axis of the bolt. This results in a smooth movement of the bolt without the generation of additional torques.

[0033] In another possible embodiment, two bolts are provided for locking the telescoping cylinder with a telescoping section, each bolt being associated with at least one locking element which, viewed in the direction of displacement of the yoke, is arranged between its bolt return elements. The bolts are located, in particular, on opposite sides of the locking device, while the yoke is arranged on its upper side. The preceding descriptions of possible configurations of the yoke, the bolts, the locking element, and the various return elements and actuators apply analogously to an embodiment with two bolts.

[0034] In particular, exactly one locking element is provided for each bolt. Preferably, the yoke is thus pre-tensioned into the locking position by a total of two yoke return elements and can be moved into the unlocking position by at least four, in particular exactly four, yoke actuators. Each of the two bolts is held in the locking position by a locking element when the yoke is in the unlocking position.

[0035] The two blocking elements also function as guide elements, as described above. In In one embodiment, apart from the two guide elements formed by the locking elements, no further guide elements are provided, so that the yoke is mounted and guided in the housing by exactly two guide elements. These two guide elements are located, in particular, within a central plane running through the middle of the yoke, in which the longitudinal axes of the bolts preferably also lie.

[0036] In In an alternative embodiment, exactly two locking elements are provided, which function as guide elements, with an additional guide element being provided so that the yoke is guided in the housing by a total of three guide elements. The additional guide element is preferably arranged outside a central plane defined by the longitudinal axes of the locking elements. The additional guide element particularly comprises a guide rod connected to the yoke or to an underside of the yoke, which is slidably mounted and guided in a guide in the housing.

[0037] In principle, however, it is also conceivable that more than one additional guide element is provided, so that the yoke, including the two blocking elements acting as guide elements, is mounted and guided in the housing by a total of four, five or more guide elements.

[0038] In another possible embodiment, the locking elements are arranged centrally on opposite sides of the yoke, with the longitudinal axes of the locking elements preferably lying in a common plane with the longitudinal axes of the bolts.

[0039] In another possible embodiment, exactly four yoke return elements are provided, which are arranged axially symmetrically to a central plane spanned by the longitudinal axes of the blocking elements and preferably axially symmetrically to a plane perpendicular to it.

[0040] In a top view of the locking device, preferably four yoke return elements are provided, forming the corners of a rectangle.

[0041] In a view along the direction of movement of the bolts, preferably two or four bolt return elements are provided, forming the corners of a rectangle.

[0042] In a view along the direction of movement of the bolts, preferably four bolt actuators are provided, forming the corners of a rectangle.

[0043] In another possible embodiment, an end section of the locking element, projecting into the stroke or travel path of the bolt within the insertion space, has an opening at its end face that is completely enclosed by a wall. This end section can form a locking section of the locking element, as described above. The end section therefore does not have a recess open on one side, such as a C-shaped section when viewed from the side. The opening is preferably circular. Preferably, the opening serves to receive the yoke return element, so that it projects from the insertion space through the opening into, or is received in, a spring receptacle of the locking element. The spring receptacle can, in particular, be enclosed by the aforementioned wall, or at least a portion of it.

[0044] In another possible embodiment, a mandrel receiving chamber is provided adjacent to the spring receptacle, with the mandrel receiving chamber being formed within the locking element. The mandrel receiving chamber is designed such that a spring mandrel extending within the insertion chamber, on which the yoke return element is mounted, projects into the mandrel receiving chamber in an unlocked position of the yoke (in which the locking element blocks the stroke or travel of the bolt), so that it is at least partially located within the locking element in the aforementioned mandrel receiving chamber. Furthermore, the spring receptacle and the mandrel receiving chamber are designed such that the yoke return element is always located outside the mandrel receiving chamber, i.e., it does not project into the mandrel receiving chamber in any position of the yoke or the locking element. Preferably, the mandrel receiving chamber has a smaller diameter than the spring receptacle.The thorn receiving space can have a circular cross-section.

[0045] The present invention further relates to a work device, in particular a mobile crane, with a telescopic boom comprising several telescopic sections slidably mounted within one another, a hydraulic telescoping cylinder for extending and retracting at least one inner telescopic section, and a locking device according to the invention connected to the telescoping cylinder. The same properties and advantages are evident as with the locking device according to the invention, which is why a repetitive description is omitted here.

[0046] Further features, details and advantages of the invention will become apparent from the exemplary embodiments explained below with reference to the figures. The figures show: Figure 1: a first embodiment of the locking device according to the invention in a perspective view; Figures 2a-b: the locking device according to Figure 1 in a frontal view and in a frontal sectional view through the two locking elements; Figure 3: a top view of the locking device according to Figure 1 in a section through the bolts at the level of the bolt return elements; Figures 4a-b: the locking device according to Figure 1Figures 5a-b: a second embodiment of the locking device according to the invention in a frontal sectional view through the two locking elements and in a top view; and Figures 6a-c: a third embodiment of the locking device according to the invention in a frontal sectional view through the two locking elements, in a side sectional view through a locking element and in a perspective close-up view of one of the locking elements.

[0047] In the Figure 1Figure 1 shows a first embodiment of the locking device 10 according to the invention in a perspective view. The locking device 10 represents a locking head of the telescoping cylinder of a telescopic boom with several telescopic sections slidably mounted within one another. This can be the telescopic boom of a mobile crane. The locking head 10 serves to lock the telescopic sections to one another and to lock the telescoping cylinder to an inner telescopic section as described above. The telescoping cylinder and the telescopic sections are not shown here.

[0048] For locking the locking device 10 with a telescopic bolt, bolts 20 (also referred to as drive bolts) are provided on opposite sides of the locking device 10, which are slidably mounted in a housing 12 of the locking device 10 (see figure). Fig. 2aThe longitudinal axes of the bolts 20 are arranged collinearly. The bolts 20 can engage in corresponding recesses of a telescopic section to be moved and move it along with an extension or retraction movement of the telescoping cylinder.

[0049] As shown in the frontal view of the locking device 10 of the Figure 2a As can be seen, the housing 12 has a central opening or recess 11 in which the telescoping cylinder (not shown here) is received. Above the recess 11 on the top of the locking device 10, a clamp-shaped yoke 30 (also called a pull yoke) is arranged, which is open at the top. The yoke 30 serves to grip and pull a locking bolt in order to release the locking of two telescoping sections against each other.

[0050] The Figure 2bFigure 1 shows a section through the locking device 10 perpendicular to the central recess 11 along the longitudinal axes of the bolts 20 (frontal view), thus revealing the interior of the locking device 10. A section along the central recess 11 through the bolts 20 (top view) is shown in Figure 2. Figure 3 depicted.

[0051] Like the double arrows in the Figure 2a As indicated, the yoke 30 can move perpendicular to the direction of displacement of the bolts 20. The yoke 30 is pressed upwards into a locking position or pre-tensioned by two yoke return elements 32 designed as compression springs. The compression springs 32 are arranged diametrically opposite each other on opposite sides of the yoke 30, as seen in a top view (see figure). Fig. 3) in a line with the longitudinal axes of the bolts 20. The longitudinal axes of the compression springs 32 and the longitudinal axes of the bolts 20 are perpendicular to each other and lie in a common median plane 50, which in particular runs through the yoke center.

[0052] To pull a locking bolt and thus release the locking of two telescopic sections, the embodiment shown here provides four hydraulic yoke actuators 34 in the form of plungers, arranged in pairs on opposite sides of the yoke 30 in the area of ​​the compression springs 32. By pressurizing the plungers 34, which are slidably mounted in plunger housings 31 adjacent to the yoke 30, the yoke 30 can be pressed downwards (i.e., towards the recess 11) into an unlocked position against the spring forces of the compression springs 32. As soon as the plungers 34 are no longer pressurized, the compression springs 32 automatically push the yoke 30 back into the locked position.

[0053] The bolts 20 are also pre-tensioned into their locking position by means of bolt return elements 22 in the form of compression springs. InIn the embodiment shown here, exactly four compression springs 22 are provided for each bolt 20, which push the respective bolt 20 outwards (i.e., away from the recess 11). Alternatively, only two compression springs can be provided. Hydraulic bolt actuators 24 can move the bolts 20 against the force applied by the compression springs 22 towards the central recess 11 and thus into an unlocking position.

[0054] For safety reasons, it is essential to prevent the yoke 30 and the bolts 20 from being in their unlocked positions simultaneously, so that the telescopic sections are locked either to each other or to the locking device 10 at all times. A safety mechanism is provided for this purpose, which only allows the bolts 20 to move into their unlocked positions when the yoke 30 is in the locked position, and vice versa. The safety mechanism comprises two blocking elements 35, which are arranged diametrically opposite each other on opposite sides of the yoke 30 and coaxially with the yoke return elements or compression springs 32.

[0055] The Figure 4a Figure 10 shows the locking device 10 in a side view looking at one of the lateral bolts 20, while in the Figure 4b A section perpendicular to the longitudinal axis of the bolt through the housing 12 in the area of ​​one of the locking elements 35 (side view) is shown.

[0056] The locking elements 35 are rigidly connected to the yoke 30 at their upper end regions. For this purpose, the yoke 30 has laterally projecting connection areas 18 to which the locking elements 35 are attached (in particular by a screw connection, although other fastening means are of course also conceivable). The locking elements 35 extend inwards into the housing 12 parallel to the direction of movement of the yoke 30. The locking elements 35 have downwardly open recesses that form spring receptacles 39 in which the compression springs 32 are received. The compression springs 32 are mounted on spring mandrels 33 (see figure). Fig. 2b and 4b ) or guided, which are attached to housing 12.

[0057] The spring pins 33 or the compression springs 32 run through an insertion space 14 inside the housing 12, into which the bolts 20 are also pushed when they move into the unlocking position (see figure). Figs. 2b and 3The lower sections of the locking elements 35 form locking sections 37, which are located above the bolts 20 when the yoke 30 is in the locking position. In this state, the locking sections 37 do not protrude into the insertion spaces 14 of the bolts 20.

[0058] Due to their central arrangement, the compression springs 32 would block any inward movement of the bolts 20. Therefore, the bolts 20 each have a U-shaped recess 26 (in plan view) on their end faces facing the compression springs 32, the width of which is greater than the diameter of the compression spring 32 (see figure). Fig. 3 The recesses 26 are therefore designed such that when the bolts 20 are moved into the unlocking position, they engage the compression springs 32, but the bolts 20 do not collide with the compression springs 32, so that the compression springs 32 are received in the recesses 26 in the unlocking position.

[0059] If, on the other hand, the yoke 30 is in the unlocked position, the blocking sections 37 project into the insertion spaces 14 and block the movement of the bolts 20 into the unlocked position. For this purpose, the recesses 26 are designed such that they do not encompass the blocking sections 37 of the blocking elements 35, i.e., they have a narrower width than the blocking sections 37 (see figure). Fig. 3 Conversely, in their unlocked position, the bolts 20 block the retraction of the locking elements 35, so that in this state the yoke 30 cannot move into the unlocked position.

[0060] Above the blocking sections 37, the blocking elements 35 each have a laterally projecting contact section 38, which in the Figure 4bThe contact section 38 comprises two contact surfaces projecting perpendicularly to the longitudinal axis of the corresponding locking element 35, which are connected to the plungers 34 or are contacted by them from above. By extending the plungers 34, the locking element 35 and thus the yoke 30 connected to it are moved downwards into the unlocking position.

[0061] In the embodiment shown here, the plungers 34 and the locking element 35 are arranged in a common plane on each side of the yoke 30, i.e., they are not offset in the direction of movement of the bolts 20. This allows for a compact design of the locking device 10 and avoids introducing additional moments into the locking elements 35. However, it is also possible, in principle, to arrange the plungers 34 offset from the locking elements 35 in the direction of movement of the bolts 20.

[0062] The central arrangement of the compression springs 32 and the locking elements 35 with respect to the bolts 20 is achieved by the fact that, in contrast to the prior art, the bolts 20 are not each supported by a spring arranged centrally, i.e., along the longitudinal axis of the bolt. Instead, each bolt 20 is pre-tensioned by several (in the present embodiment four) compression springs 22, which are located laterally next to the locking elements 35. As in the Figures 3 and 4bAs can be seen, the compression springs 22 are arranged in pairs on both sides of the compression springs 32, aligned with the direction of displacement of the bolts 20. The space freed up in the area of ​​the bolt's longitudinal axis is occupied by the compression springs 32 and the locking elements 35. This results in a particularly compact design for the locking device 10. The possibility of dispensing with separate compression springs and instead arranging them coaxially with the locking elements 35 also ensures a simpler design for the locking elements 35.

[0063] At the ends facing the locking elements 35, the bolts 20 have laterally projecting contact sections 28. Compression springs 22 are attached to these contact sections 28 on the side of each bolt 20 facing the insertion chamber 14; that is, the compression springs 22 are arranged within the insertion chamber 14. The compression springs 22 may be mounted on spring mandrels. On the side of the contact sections 28 of each bolt 20 facing away from the insertion chamber 14 are the bolt actuators 24, which in this embodiment are also designed as plunger cylinders 24. By extending the plungers 24, the bolts 20 are pressed towards the compression springs 32 and thus moved into the unlocking position.

[0064] In the embodiment shown here, four plungers 24 are provided per bolt 20, which can also be arranged in pairs on both sides of the compression springs 32 or the locking elements 35, viewed along the direction of displacement of the bolts 20. Alternatively, only two plungers 24 or more than two plungers 24 per bolt 20 can be provided.

[0065] The locking elements 35 simultaneously serve as guide elements for the yoke 30 within the housing 12, ensuring stable movement of the yoke 30. For this purpose, the locking elements 35 each have a guide section 36, preferably cylindrical, above the contact sections 38. The locking elements 35 are slidably mounted and guided in guides or through-holes in the housing 12 of the locking device 10 via the guide sections 36.

[0066] In the embodiment shown here, the locking elements 35 are guided by recesses in the plunger housings 31, which are arranged laterally next to the yoke 30 and which essentially have a square U-shape. The locking elements 35 are arranged between the two plungers 34. The actual guides for the guide sections 36 of the locking elements 35 can be arranged in the middle sections of the plunger housings 31, in the housing 12 below, or in both.

[0067] The plunger housings 31 can be considered part of the housing 12.

[0068] Compared to prior art solutions where several separate piston rods are provided for guiding the yoke, the locking elements 35 thus perform a dual function, also acting as guide elements for the yoke 30. Separate piston rods can therefore be omitted, resulting in a particularly compact design. Furthermore, the arrangement of the locking elements 35 according to the invention ensures that, in the embodiment shown here, the yoke 30 is guided by only two guide elements arranged in the central plane 50, which reduces the likelihood of the yoke 30 jamming and increases its smooth operation.

[0069] The blocking, contact and guide sections 36, 37, 38 of the blocking elements 35 are preferably formed in one piece.

[0070] An alternative solution according to a second embodiment is described in the Figures 5a-b depicted. The Figure 5aThe locking device 10 is shown in a frontal sectional view through the two blocking elements 35 and the Figure 5b Figure 10 shows a top view of the locking device. Reference numerals used in the first embodiment denote the same components.

[0071] The locking device 10 according to the second embodiment differs from the first embodiment in that, in addition to the two locking elements 35, a third guide element 40 is provided, so that the yoke 30 is mounted and guided in the housing 12 by a total of three guide elements 35, 40, i.e., by a tripod. The further guide element 40 comprises a guide rod 42 connected to the underside of the clamp-shaped yoke 30, which is slidably mounted and guided in a corresponding guide or passage in the upper region of the housing 12. The guide or passage is thus located below the yoke 30.

[0072] As in the Figure 5bAs can be seen, in the embodiment shown here, the further guide element 40 is arranged off-center with respect to the yoke 30, i.e., it is located outside the central plane 50 defined by the longitudinal axes of the bolts 20 and the locking elements 35, as well as outside the plane perpendicular to the central plane 50 passing through the center of the yoke 30. The guide elements 35 and 40 thus form the vertices of an irregular triangle. This results in the aforementioned tripod mounting of the yoke 30.

[0073] Alternatively, a tripod bearing could also be achieved by arranging the additional guide element 40 outside the central plane 50 but within the plane running perpendicular to the central plane 50 through the center of the yoke 30, thus forming an isosceles triangle. It is also conceivable to provide more than one additional guide element 40.

[0074] The Figures 6a-cshow a third embodiment of the locking device 10 according to the invention. Figure 6a The locking device 10 is shown in a frontal sectional view through two blocking elements 35, which Figure 6b shows the locking device 10 in a side sectional view (90° to the view of the Figure 6a rotated) by one of the blocking elements 35 and the Figure 6c Figure 1 shows a perspective view of one of the blocking elements 35 of this embodiment.

[0075] The locking device 10 according to the third embodiment differs from the first two embodiments in that the yoke return elements or compression springs 32 are mounted in a shallow spring receptacle 39 at the end section of the respective locking element 35 and not on the top of a bore extending through a substantial part of the locking element 35.

[0076] As in the Figure 6cAs can be seen, the locking element 35 of this embodiment has a circular opening 60 on its end face facing away from the yoke 30, which is surrounded by a wall 62. The recess formed by the wall 62 constitutes the spring receptacle 39 for the compression spring 32, which is supported by an annular projection extending radially inwards from the wall 62. The projection transitions into a cylindrical bore extending within the locking element 35 towards the yoke 30, forming a mandrel receptacle 66. The mandrel receptacle 66 has a smaller diameter than the spring receptacle 39, so that the compression spring 32 never enters the mandrel receptacle 66 in any position of the locking element 35.

[0077] As in the Figures 6a and 6bAs can be seen, in the position where the yoke 30 is in the locking position, the compression springs 32 do not extend (far) inside the locking elements 35, but are supported at their end sections in the spring receptacles 39. In the unlocked position of the yoke 30, where the locking sections 38 of the locking elements 35 project into the travel paths of the bolts 20, the compression springs 32 are compressed and the spring pins 33 project through the openings 60 into the pin receptacles 66 (not shown).

[0078] To ensure sufficient length of the compression springs 32 despite their support being located further down in the area of ​​the bolt return elements 22 on the locking element 35, the bearing points of the spring mandrels 33 on the housing 12 of the locking device 10 are offset downwards (i.e., away from the yoke 30) in this embodiment. For this purpose, cup-shaped mandrel bearing sections 64 are provided on the housing 12, to the bases of which the spring mandrels 33 are attached.

[0079] As in the Figure 6cAs shown, the blocking elements 35 can have reinforcing sections 68 on the sides where the wing-shaped projections of the contact sections 38 for the yoke actuators 34 are located. These reinforcing sections extend in the area of ​​the blocking sections 37 and can be connected to the wall of the blocking element 35 or formed integrally with it. This allows the forces of the yoke actuators 34 to be transferred more effectively into the blocking elements 35 and reinforces the latter in these areas.

[0080] The locking elements 35 can also have a shape in the first two embodiments, or more generally, that corresponds to that of Figure 6c, apart from the flat front spring receptacle 39 and the narrower mandrel receptacle 66. In particular, in the first two embodiments, the locking elements 35 also have circular openings 60 on the end faces of the end sections or locking sections 37 for the compression springs 32, which project into the interior of the locking elements 35 and are supported therein. The reinforcement sections 68 shown can also be provided as an option. Reference symbol list:

[0081] 10 Locking device (locking head) 11 Recess 12 Housing 14 Insertion space 16 Screw 18 Connection area 20 Bolt 22 Bolt return element (spring) 24 Bolt actuator (plunger) 26 Recess 28 Contact section 30 Yoke 31 Plunger housing 32 Yoke return element (spring) 33 Spring mandrel 34 Yoke actuator (plunger) 35 Blocking element 36 Guide section 37 Blocking section 38 Contact section 39 Spring receptacle 40 Additional guide element 42 Guide rod 50 Center plane 60 Opening 62 Wall 64 Mandrel bearing section 66 Mandrel receptacle 68 Reinforcement section

Claims

1. Locking device (10) for the telescopic cylinder of a telescopic boom comprising a plurality of telescopic stages, comprising: - a housing (12), - at least one bolt (20) displaceably mounted in the housing (12) for locking the telescopic cylinder with a telescopic stage, wherein the bolt (20) is preloaded into a locking position by means of at least one bolt return element (22) and is displaceable into an unlocking position by means of at least one bolt actuator (24), - a yoke (30) displaceably mounted in the housing (12), which can be moved into an unlocking position to release a locking bolt of the telescopic boom, - at least one blocking element (35) which blocks a displacement of the bolt (20) into its unlocking position when the yoke (30) is in the unlocking position, wherein the blocking element (35) and the bolt (20) are at least partially displaceable into a common insertion space (14) of the housing (12), wherein the bolt (20) is preloaded into the locking position by means of at least two bolt return elements (22), characterised in that the blocking element (35) is arranged between the bolt return elements (22) in the direction of displacement of the yoke (30).

2. Locking device (10) according to claim 1, wherein the at least one blocking element (35) is also designed as a guide element, by means of which the yoke (30) is guided in the housing (12), wherein the blocking element (35) preferably has a guide section (36) which is displaceably mounted and guided in a guide of the housing (12).

3. Locking device (10) according to any one of the preceding claims, wherein the bolt return elements (22) extend perpendicularly to the longitudinal axis of the blocking element (35) and / or at least partially within the insertion space (14).

4. Locking device (10) according to any one of the preceding claims, wherein the bolt (20) is preloaded into the locking position by means of at least two bolt return elements (22) and / or wherein the bolt return elements (22) are arranged symmetrically with respect to the longitudinal axis of the blocking element (35), as seen in the direction of displacement of the bolt (20).

5. Locking device (10) according to any one of the preceding claims, wherein the yoke (30) is preloaded into a locking position by means of at least one yoke return element (32) and is preferably displaceable into the unlocking position by means of at least one yoke actuator (34), wherein the blocking element (35) preferably has a blocking section (37) which, in the unlocking position of the yoke (30), projects into a travel path of the bolt (20) within the insertion space (14), wherein the blocking element (35) preferably further has a contact section (38) which is connected to or contacted by the at least one yoke actuator (34), and wherein preferably two yoke actuators (34) are provided, which are preferably arranged symmetrically with respect to the blocking element (35), as seen in the direction of displacement of the bolt (20).

6. Locking device (10) according to claim 5, wherein the yoke return element (32) is a compression spring which is arranged coaxially to the blocking element (35) and is preferably partially accommodated in a spring receptacle (39) of the blocking element (35) and / or is mounted on a spring mandrel (33) connected to the housing (12).

7. Locking device (10) according to claim 5 or 6, wherein the yoke return element (32) is arranged at least partially in the insertion space (14), wherein the bolt (20) preferably has, on an end face facing the yoke return element (32), a recess (26), in particular U-shaped, which, in the unlocking position of the bolt (20), at least partially encloses the yoke return element (32).

8. Locking device (10) according to any one of claims 5 to 7, wherein the yoke actuator (34) and / or the bolt actuator (24) comprises or represents a hydraulic cylinder, in particular a plunger cylinder.

9. Locking device (10) according to any one of the preceding claims, wherein two bolts (20) are provided for locking the telescopic cylinder with a telescopic stage, wherein each bolt (20) is associated with at least one blocking element (35), in particular exactly one blocking element (35), which is arranged between its bolt return elements (22), as seen in the direction of displacement of the respective bolt (20).

10. Locking device (10) according to claim 9 and developed with the features of claim 2, wherein exactly two blocking elements (35) are provided, which function as guide elements, and wherein a further guide element (40) is provided, so that the yoke (30) is guided in the housing via a total of three guide elements (35, 40), wherein the further guide element (40) is preferably arranged outside a centre plane (50) defined by the longitudinal axes of the blocking elements (35) and in particular comprises a guide rod (42) connected to the yoke (30), which guide rod is displaceably mounted and guided in a guide of the housing (12).

11. Locking device (10) according to claim 9 or 10, wherein the blocking elements (35) are arranged centrally on opposite sides of the yoke (30), wherein the longitudinal axes of the blocking elements (35) are preferably arranged in a common plane with the longitudinal axes of the bolts (20).

12. Locking device (10) according to any one of the preceding claims and developed with the features of claims 5 and 9, wherein exactly four yoke return elements (32) are provided, which are arranged axially symmetrically with respect to a centre plane (50) defined by the longitudinal axes of the blocking elements (35), and preferably with respect to a plane perpendicular thereto.

13. Locking device (10) according to any one of the preceding claims, wherein an end section of the blocking element (35) projecting into a travel path of the bolt (20) within the insertion space (14) has, on its end face, an opening (60) completely enclosed by a wall (62), wherein the yoke return element (32) preferably projects from the insertion space (14) through the opening (60) into a spring receptacle (39) of the blocking element (35) enclosed in particular by the wall (62).

14. Locking device (10) according to the preceding claim, wherein the spring receptacle (39) is followed by a mandrel receiving space (66) formed inside the blocking element (35), which is designed such that a spring mandrel (33) extending in the insertion space (14), on which the yoke return element is mounted, projects into the mandrel receiving space (66) in an unlocking position of the yoke (30), wherein the yoke return element (32) is always located outside the mandrel receiving space (66), wherein the mandrel receiving space (66) preferably has a smaller diameter than the spring receptacle (39).

15. Work implement, in particular a mobile crane, comprising a telescopic boom comprising a plurality of telescopic stages displaceably mounted inside one another, a hydraulic telescopic cylinder for extending and retracting at least one inner telescopic stage, and a locking device (10) according to any one of the preceding claims connected to the telescopic cylinder.

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