Mobile crane with a telescopic boom and a safety and locking unit

Abstract

A mobile crane (1) with a telescopic boom (2), comprising a base box (10) with extendable and retractable inner boxes (20, 30, 40) and a safety and locking unit (8) comprising a first actuating cylinder (51) and a second actuating cylinder (52), each designed as a single-acting hydraulic cylinder with a first spring element (53) and a second spring element (54) as well as a first line (81) and a second line (82), wherein the first actuating cylinder (51) moves locking bolts (21, 31, 41) between operating states unbolted and bolted, and the second actuating cylinder (52) moves drive bolts (8a) between operating states secured and unlocked, characterized in that in the event of a malfunction, the first actuating cylinder (51) moves into the operating state bolted and the second actuating cylinder (52) into the operating state unlocked.

Description

[0001] The invention relates to a mobile crane with a telescopic boom, comprising a base box with retractable and extendable inner boxes and a securing and locking unit which comprises a first actuating cylinder and a second actuating cylinder, which are each designed as single-acting hydraulic cylinders with a first spring element and a second spring element as well as a first line and a second line, wherein the first actuating cylinder moves locking bolts between the operating states unbolted and bolted and the second actuating cylinder moves driving bolts between the operating states secured and unlocked.

[0002] A locking device for a telescopic boom of a mobile crane is already known from German patent DE 10 2018 117 630 B4. The telescopic boom typically consists of a base box that accommodates several telescopically arranged inner boxes that can be extended and retracted hydraulically via a telescopic cylinder. The locking device, also frequently referred to as a securing and bolting unit, is arranged at a free end of a cylinder housing of the telescopic cylinder. The telescopic cylinder itself rests on a base end of the base box with its piston rod. The locking device essentially consists of a first hydraulic actuating cylinder for a driving pin, a second hydraulic actuating cylinder for a locking pin, and a control device for hydraulically controlling the two actuating cylinders.The two actuating cylinders have springs on the rod side of the cylinder and are connected to the hydraulic supply at the base. The control device draws hydraulic energy from a rod-side cylinder chamber of the telescoping cylinder, which is temporarily stored in a high-pressure accumulator in the control device. The locking device can be connected to a retractable or extendable inner box via the driver pin. The locking pin arranged on the respective inner box has the task of bolting an inner box to an adjacent base box or inner box in a desired extended or retracted position. The two actuating cylinders draw their actuating energy from the high-pressure accumulator as required via corresponding first and second two-way valves.In the unactuated, idle state, and thus also in the event of a fault, the two two-way valves separate the actuating cylinders from the high-pressure accumulator, and the first and second two-way valves connect the actuating cylinders to the telescoping cylinder via a return line. A bypass line runs parallel to the return line, which is closed during normal operation via a third two-way valve. In the unactuated, idle state, and thus also in the event of a fault, this third two-way valve in the bypass line connects the rod-side cylinder chamber of the telescoping cylinder to the actuating cylinder of the driving pin via the first two-way valve. In the event of a fault in the control device, the three two-way valves assume their rest position, in which the first and second two-way valves connect the actuating cylinders to the return line, and the third two-way valve opens the bypass line.If, at the time of the malfunction, the telescopic cylinder is in a difficult-to-access operating position and, for example, the drive pin is connected to one of the inner boxes via the associated actuating cylinder, the telescopic cylinder can be pressurized when a preset switching pressure is reached, releasing the drive pin from the inner box via the bypass line. The telescopic cylinder can then be retracted into an inspection or repair position. If the preset switching pressure is not reached, the telescopic cylinder simply retracts without releasing the actuating cylinder for the drive pin via the bypass line.

[0003] Because the locking mechanism, control device, and actuating cylinders are located at the upper end of the telescopic cylinder, they are difficult to access in the event of a malfunction during operation of the telescopic boom. This can cause problems when retracting the telescopic boom and even its recovery, which requires considerable effort.

[0004] Another locking unit for a telescopic cylinder of a mobile crane with a telescopic boom, comprising a base box and several inner boxes, is known from utility model DE 20 2018 102 111 U1. The locking unit consists of a housing and at least one cylinder lock that can be moved linearly within the housing for locking and unlocking the locking unit. In the event of an emergency, this cylinder lock is unlocked via a manually operable switching valve so that the telescopic cylinder, which is thereby decoupled from the inner boxes, can be retracted for repair.

[0005] Furthermore, German patent application DE 10 2010 022 865 A1 discloses a locking head which is attached in the usual way to a telescopic cylinder of a telescopic boom of a mobile crane. This locking head comprises a first actuating cylinder, referred to as the telescopic locking body, and two second actuating cylinders, referred to as cylinder locks. The first actuating cylinder can be moved hydraulically against a spring force from a bottom or unbolted operating state to an top or bolted operating state. The second actuating cylinders can also be moved hydraulically against a spring force from an unlocked or unsecured operating state to a locked or secured operating state. In the event of a malfunction, the first actuating cylinder moves to the bolted operating state and the second actuating cylinders each move to the secured operating state.

[0006] The present invention is based on the object of creating a mobile crane with a telescopic boom and an improved securing and locking unit. In particular, the securing and bolting unit should enable emergency operation.

[0007] According to the invention, in a mobile crane with a telescopic boom, comprising a base box with retractable and extendable inner boxes and a securing and locking unit, which comprises a first actuating cylinder and a second actuating cylinder, which are each designed as a single-acting hydraulic cylinder with a first spring element and a second spring element as well as a first line and a second line, wherein the first actuating cylinder moves locking bolts between the operating states of unbolted and bolted and the second actuating cylinder moves driving bolts between the operating states of secured and unlocked, an improvement of the securing and locking unit is achieved bythat in the event of a malfunction, the operating state "bolted" and the operating state "unlocked" are automatically set, or in the event of a malfunction, the first actuating cylinder moves to the operating state "bolted" and the second actuating cylinder moves to the operating state "unlocked". This inventive control and design of the first and second actuating cylinders ensures that in the event of a malfunction, the actuating cylinders always assume preselected safe operating states. In the context of the present invention, "automatic" is understood to mean that the first and second actuating cylinders each move to their preselected safe operating states without any power supply and without any signal supply. In the present case, this meansthat the first and second actuating cylinders move into the bolted or unlocked operating state without pressure or in a low-pressure state. In the bolted operating state, the base box or the inner boxes are always bolted to the next larger inner box. In the context of the present invention, a malfunction is understood to mean at least a failure of the supply of energy, in particular hydraulic energy, to the first actuating cylinder and / or the second actuating cylinder. Possible causes include faults in the hydraulic supply (e.g., defective hydraulic line), electrical control of the valves (e.g., cable break), faults in the electromagnetic drive of the valves (e.g., magnet burned out), or a mechanical blockage of a valve adjustment (e.g., valve body jammed).which predominantly occurs in a non-energized rest position. Because the two actuating cylinders are in the bolted and unlocked operating states, it is guaranteed that the telescoping device can continue to be extended and retracted. Since the securing and locking unit, including the first and second actuating cylinders and usually the first and second valves, is extended with the telescoping device, better accessibility is provided in the event of a malfunction by retracting the telescoping device. In the event of a malfunction, the first and second actuating cylinders are then controlled by a so-called emergency operation, to the extent that this is necessary for the various embodiments proposed below.

[0008] It is particularly advantageous that in the event of a fault, the first actuating cylinder moves into the bolted operating state via the first spring element and the second actuating cylinder moves into the unlocked operating state via the second spring element.

[0009] A structurally advantageous solution is considered that the first spring element is assigned to a bottom side of the first actuating cylinder, the second spring element is assigned to a bottom side of the second actuating cylinder, the first line is connected only to one rod side of the first actuating cylinder and the second line is connected only to one rod side of the second actuating cylinder.

[0010] Typically, a first valve arranged in the first line and a second valve arranged in the second line are provided to control the first and second actuating cylinders. In the event of a fault, these valves automatically move to their rest position, causing the first actuating cylinder to move into the bolted operating state and the second actuating cylinder to move into the unlocked operating state. In the context of the present invention, “automatic” means that the first and second valves each move to their preselected rest position without the supply of energy and / or without the supply of a signal. In the present case, this means that the first and second actuating cylinders then move into the bolted and unlocked operating states, respectively.These movements of the first actuating cylinder into the locked operating state and the second actuating cylinder into the unlocked operating state occur immediately without any further signal or power supply. In the rest position, the rod chamber of the actuating cylinder is then connected to the low-pressure line in the usual way.

[0011] In a particular alternative embodiment, the first spring element has a higher force level than the second spring element, so that with a medium pressure applied to the second line, the second actuating cylinder moves from the unlocked operating state to the locked operating state, and with a high pressure applied to the first line, the first actuating cylinder moves from the bolted operating state to the unbolted operating state. Thus, via a common line for the hydraulic oil, a targeted control of the first and second actuating cylinders can be achieved by varying the pressure levels.

[0012] It has proven to be particularly simple in terms of construction that the first valve and the second actuating cylinder are mechanically locked via a locking element in such a way that the first valve is locked for movement into its rest position as long as the second actuating cylinder is in the unlocked operating state.

[0013] Typically, the mobile crane is provided with a telescopic device, the first line and the second line are connected to a common seventh line, and the seventh line is passed through the telescopic device.

[0014] In an independently inventive manner, it is provided that the mobile crane has a telescopic device in which the first line and the second line are each passed separately through the telescopic device.

[0015] It is particularly advantageous for the mobile crane to have an upper carriage and for the first and second valves to be located in the upper carriage. Since the first and second valves, and thus the associated hydraulic block, are no longer located on the telescoping cylinder but are installed in the upper carriage, the first and second valves can be easily serviced and repaired there at any time. Since the first and second actuating cylinders are equipped with spring elements, two lines are sufficient as oil supplies - for example, an internal oil feedthrough in the telescoping cylinder, energy chain, or hose reel - to move the actuating cylinders into any desired position. If the spring elements in the actuating cylinder are also set to different force levels, even a single line is sufficient for the oil supply. As previously described, any desired position can then be achieved using different pressure levels.

[0016] An embodiment of the invention is explained in more detail in the following description. It shows: Fig. 1 a schematic view of a mobile crane, Fig. 2 a schematic plan view of a telescopic boom in section in a basic state, Fig. 3 a schematic plan view according to Fig. 2 in a first extended state, Fig. 4 a schematic plan view according to Fig. 2 in a second extended state, Fig. 5 a schematic hydraulic plan for an operating state according to a first embodiment, Fig. 6 a schematic hydraulic diagram of an operating state according to a second embodiment, Fig. 7a to 7c show schematic hydraulic diagrams for different operating states according to a third embodiment and Fig. 8 is a schematic hydraulic diagram of an operating state according to a fourth embodiment.

[0017] The Fig. 1 shows a schematic view of a mobile crane 1 which can be moved on public roads, which is parked on a horizontal surface U and comprises a telescopic boom 2 which, in a transport position, extends parallel to a horizontal direction with its longitudinal direction L. The telescopic boom 2 with its head end 2a and a telescopic boom head as well as a foot end 2b is shown only schematically. The mobile crane 1 has an undercarriage 3 which, in the example shown here, has a wheeled chassis 4 comprising a total of six axles, each with at least two spaced-apart, rubber-tired wheels 5 rotatably mounted on these axles. Arranged on the undercarriage 3 is an upper carriage 6 which supports the telescopic boom 2 and can be pivoted relative to the undercarriage 3 about a pivot axis S running parallel to a vertical direction.The telescopic boom 2 is articulated via its base end 2b about a horizontal luffing axis W on the superstructure 6 and opposite a counterweight on the superstructure 6.

[0018] The telescopic boom 2 has a base box 10 which is luffably hinged to the superstructure 6 and which contains a plurality of inner boxes 20, 30, 40. Due to their stepped and coordinated and essentially rectangular cross-sections, the first to third inner boxes 20, 30, 40 are arranged one inside the other and within the base box 10 in such a way that they can be linearly displaced in the longitudinal direction L of the telescopic boom 2, in particular can be hydraulically extended and retracted. The telescopic boom 2 can be luffed or almost vertically erected via at least one linear drive acting between the base box 10 and the superstructure 6, in the form of a luffing cylinder 9. At the free end of the telescopic boom 2 and thus at the telescopic boom head of the innermost third inner box 40, a load-handling device is usually suspended via a hoist rope (not shown), in order to be able to lift and lower a load.The load-handling device is preferably designed as a load hook with a bottom block for rope reeving.

[0019] The Fig. 2 shows a schematic top view of a telescopic boom 2 in section. With a horizontally oriented telescopic boom 2, the section plane is approximately halfway up the height of the telescopic boom 2 and runs centrally through its left and right side walls. Correspondingly, the section also runs through bolting holes 12, 22, 32 conventionally arranged in the side walls of the base box 10 and the first and second inner boxes 20, 30, which are each arranged along the base box 10 and the inner boxes 20, 30 in a retracted position A, a first extended position B, a second extended position C, and a third extended position D. No bolting holes are provided in the innermost third inner box 40, since the innermost third inner box 40 is bolted to the bolting holes 32 of the outwardly adjacent second inner box 30.In principle, it is conceivable that further bolting holes are arranged on the third inner box 40 in order to accommodate further inner boxes not shown.

[0020] For the telescopic boom 2, the retracted position A and the extended positions B, C, and D are each assigned to specific and equal extension lengths of the inner boxes 20, 30, 40, for example, with the values ​​of 0%, 45%, 90%, and 100% extension length. Since the locking bolts 21, 31, 41 protrude inward at the base ends of the inner boxes 20, 30, 40, the next inner inner box 20, 30, 40 cannot be fully retracted. The bolt holes 12, 22, 32 are provided with reference numbers at the first extended position B only as an example and can of course also be found at all other extended positions C, D and the retracted position A.

[0021] Furthermore, the Fig. 2 that the first locking bolt 21 is arranged inside at the foot end 2b of the first inner box 20, the second locking bolt 31 is arranged inside at the foot end 2b of the second inner box 30, and the third locking bolt 41 is arranged inside at the foot end 2b of the third inner box 40. The base box 10 and the inner boxes 20, 30, 40 are designed as tubular bodies with a substantially rectangular cross-section, and the locking bolts 21, 31, 41 are each arranged laterally - relative to the top or bottom of the base box 10 or inner box 20, 30, 40 - and inside on one of the two side walls of the base box 10 or inner box 20, 30, 40.The locking bolts 21, 31, 41 can also be moved transversely to the longitudinal direction L of the telescopic boom 2 and horizontally - with respect to a telescopic boom 2 aligned horizontally in the longitudinal direction L - from a bolted position to an unbolted position by a so-called securing and locking unit 8. In the bolted position, the respective locking bolts 21, 31, 41 connect the inner box 20, 30, 40, on which they are arranged, to the next outermost inner box 20, 30 or base box 10 by being moved into corresponding bolting holes 12, 22, 32. A retraction and extension movement in the longitudinal direction L of the respective inner boxes 20, 30, 40 is thus blocked by the respective locking bolt 21, 31, 41 in the bolted position. In the unbolting position, the locking bolts 21, 31, 41 release the bolting hole 12, 22, 32 of the next outer inner box 20, 30 or base box 10.

[0022] In principle, it is also conceivable that the bolting holes 12, 22, 32 are arranged in the upper or lower side of the base box 10 or inner box 20, 30, 40.

[0023] In the usual way, to change the length of the telescopic boom 2, the inner boxes 20, 30, 40 are individually and successively extended and retracted linearly from the base box 10 or the next outermost inner box 20, 30 by means of a telescoping device 7. The telescoping device 7 is designed in the usual way as a hydraulic cylinder with a piston rod 7a and a cylinder housing 7b and is arranged centrally in the telescoping boom 2. The telescoping device 7 is supported with a free end of its piston rod 7a in the area of ​​a foot connection 15 of the base box 10. The telescoping device 7 also extends with its longitudinal extent in the longitudinal direction L of the telescoping boom 2. The securing and locking unit 8 is arranged on the thus extendable cylinder housing 7b of the telescoping device 7, in particular on its lower end of the cylinder housing 7b facing the piston rod 7a.Via the securing and locking unit 8, the telescoping device 7 can be secured via driving pins 8a for extending and retracting the respective inner box 20, 30, 40 with first, second, or third recesses 23, 33, 43 arranged there in the region of the respective foot ends 2b by moving the driving pins 8a into the recess 23, 33, 43 and can be released by moving the driving pins 8a out of the recess 23, 33, 43. Thus, the operating states "secured" and "unsecured" are present with respect to the driving pins 8a.On the other hand, the securing and locking unit 8 also has the task of detaching the respective inner box 20, 30, 40 to be extended or retracted from the next outermost inner box 20, 30 or base box 10 by moving locking bolts 21, 31, 41 from a bolted position to an unbolted position before the securing and locking unit 8 is extended or retracted, or of connecting it to the next outermost inner box 20, 30 or base box 10 after the securing and locking unit 8 is extended or retracted by moving the respective locking bolt 21, 31, 41 from its unbolted position to its bolted position.By means of the locking bolts 21, 31, 41 inserted into or pulled out from the respective bolt holes 12, 22, 32, adjacent base boxes 10 and inner boxes 20, 30, 40 can be connected to or detached from one another in the usual way in the retracted position A, the first extended position B, the second extended position C and the third extended position D. For each locking bolt 21, 31, 41 on the inner box 20, 30, 40, the corresponding bolting hole 12, 22, 32 is located in the next outermost base box 10 or inner box 20, 30. For this purpose, the locking bolts 21, 31, 41 are each arranged stationary and inside at the foot ends of the inner boxes 20, 30, 40 and are each pushed into the bolting position in the respective bolting hole 12, 22, 32 by a spring force.It is also conceivable for the locking bolts 21, 31, 41 to be forced into the respective bolting holes 12, 22, 32 via a locking mechanism such as a ball-type locking bolt. To actuate the locking bolts 21, 31, 41, actuating elements 8b are arranged on the securing and locking unit 8, with which the inwardly projecting ends of the locking bolts 21, 31, 41 can be grasped and pulled inward out of the respective bolting holes 12, 22, 32. Thus, the operating states "bolted" and "unbolted" are present for the locking bolts 21, 31, 41.

[0024] In addition to the previously described driving pins 8a and actuating elements 8b, the securing and locking unit 8 also has a first actuating cylinder 51 and a second actuating cylinder 52, which subsequently lead to the Fig. 5 to 8. The driving pins 8a and the actuating elements 8b are moved between the respective operating states "secured" and "unsecured" or the respective operating states "bolted" and "unbolted" via the hydraulically driven first and second actuating cylinders 51, 52. A transmission mechanism (not described in detail) is arranged between the first and second actuating cylinders 51, 52 and the driving pins 8a and the actuating elements 8b, which transmission mechanism is preferably a conventionally used link with corresponding guide paths and drivers. The transmission mechanism transmits, on the one hand, the linear movement of the first and second actuating cylinders 51, 52 to the driving pins 8a and the actuating elements 8b, and on the other hand, a mechanical locking mechanism can also be provided, so that the "unbolted" operating state is only possible when the "secured" operating state is present.

[0025] Normally, the driving pins 8a and actuating elements 8b are located one above the other in the same plane relative to the longitudinal direction L of the telescopic boom 2. Fig. 2, these were shown one after the other in the longitudinal direction L of the telescopic boom 2 to achieve a better clarity. Furthermore, the above description has only been related to one side of the telescopic boom 2 and thus only to one driving pin 8a, one actuating element 8b, one bolt hole 12, 22, 32 and an associated recess 23, 33, 43. From the Fig. 2, however, it can be seen that a driving pin 8a, an actuating element 8b, a bolting hole 12, 22, 32 and an associated recess 23, 33, 43 are each arranged opposite one another with respect to the longitudinal direction L of the telescopic boom 2.

[0026] The Fig. 2 shows the telescopic boom 2 and the associated base and inner boxes 10, 20, 30, 40 in the fully retracted basic state, as it is also shown in the Fig. 1. In this basic state, the inner boxes 20, 30, 40 are in the "bolted" operating state and the driving pin 8a is in the "unlocked" operating state, ie the fully retracted telescopic device 7 is released from the inner boxes 20, 30, 40.

[0027] The Fig. 3 shows the schematic top view according to Fig. 2, whereby the telescopic boom 2 is opposite Fig. 2 is in a first extended state with respect to a planned extension of the third inner box 40. The telescoping device 7 is slightly extended, so that the securing and locking unit 8, viewed in the longitudinal direction L of the telescopic boom 2, is at the level of the recess 43 in the innermost third inner box 40 and at the level of the third locking pins 41. After the travel movement of the telescoping device 7, the two driving pins 8a are then moved in opposite directions from the "unlocked" operating state to the "locked" operating state. The driving pins 8a are now in engagement with the third recesses 43 in the third inner box 40. The third inner box 40 can then be released from the second inner box 30 from the “bolted” operating state to the “unbolted” operating state by pulling the third locking pins 43 out of the bolting holes 32 in the second inner box 30.Now the third inner box 40 is ready to be extended.

[0028] In the Fig. 4 is another schematic plan view according to Fig. 2, but the telescopic boom 2 is opposite Fig. 3 is in a second extended state. The telescopic device 7 together with the third inner box 40 is now extended so far that the third inner box 40 can be moved from the Fig. 3 shown retracted position A into the second extended position C on the second inner box 30. In the extended position C, the locking bolts 41 on the third inner box 40 are located in the longitudinal direction L of the telescopic boom 2 at the level of the bolt holes 32 in the second inner box 30. During and after the travel movement of the telescoping device 7, the two driving bolts 8a continue to be in the "secured" operating state. In a first step, only by releasing the actuating elements 8b are the locking bolts 43 moved from the "unbolted" operating state to the "bolted" operating state, and thus the locking bolts 43 are located as shown in the Fig. 4, in the bolt holes 32 in the second inner box 30. Only then are the drive pins 8a moved from the "locked" operating state to the "unlocked" operating state. The telescoping device 7 is thus released from the third inner box 40.

[0029] In a next step, the telescopic device 7 can now be retracted again in order to Fig. 2. The extension process previously described in connection with the third inner box 40 can now be repeated with regard to the first inner box 20 and the second inner box 30. Any extension positions can be selected from the possible extension positions B, C, D. This is repeated until the desired extension sequence of the inner boxes 20, 30, 40 is reached. At the end, the telescoping device 7 is retracted again or can remain in the respective extended position if necessary. It should be noted that you always start with the smallest of the inner boxes 20, 30, 40 that is to be moved. The retraction or telescoping then takes place in the same way in reverse order. You must start with the largest of the inner boxes 20, 30, 40 that is to be moved.

[0030] The Fig. Figure 5 shows a schematic hydraulic diagram according to a first embodiment, wherein the first actuating cylinder 51 is in the "bolted" operating state and the second actuating cylinder 52 is in the "unlocked" operating state. Each of the two hydraulic actuating cylinders 51, 52 is operated with hydraulic oil, has a base side 51a, 52a and a rod side 51b, 52b in the usual way, and is designed as a single-acting hydraulic cylinder. Correspondingly, a first spring element 53 is installed in a housing of the first actuating cylinder 51 on its base side 51a, and a second spring element 54 is installed in a housing of the second actuating cylinder 52 on its base side 52a. The spring elements 53, 54 have almost the same force level, so that adjustment of the spring elements 53, 54 can be effected using a comparable pressure.A first line 81 is connected to the rod side 51b of the first actuating cylinder 51, and a second line 82 is connected to the rod side 52b of the second actuating cylinder 52. Via the spring elements 53, 54, the first actuating cylinder 51 or the second actuating cylinder 52 moves into its spring-loaded and extended rest position in a depressurized state or at low pressure ND in the lines 81, 82. The pressure acting on the piston of the actuating cylinder 51, 52 is lower than the calculated pressure of the spring element 53, 54 in the extended state. The depressurized, extended first actuating cylinder 51 is assigned to the "bolted" operating state of the associated actuating element 8b or the locking bolt 21, 31, 41. Whereas the second actuating cylinder 52, which is extended without pressure, is to be assigned to the “unlocked” operating state of the associated driving pin 8a.In the present case, the low pressure (LP) is below 40 bar and the high pressure (HP) is between 60 and 120 bar. The force levels of the first and second spring elements 53, 54 are then 4000 + / - 2000 N. A distance of 20 bar between the low pressure (LP) and the high pressure (HP) was chosen in order to obtain clear switching states of the actuating cylinders 51, 52 via an appropriate pressure specification. It is of course for a specialist to find suitable values ​​for the low pressure (LP), high pressure (HP) and spring force in a suitable respective relationship to one another in order to be able to reliably switch and achieve the desired movement of the actuating cylinders 51, 52 between their respective operating states. It is of course clear that, depending on the design of the mobile crane and its hydraulic system, the values ​​for the low pressure (LP), high pressure (HP) and spring force may therefore deviate from the aforementioned exemplary value ranges.

[0031] In principle, it is also conceivable that in the first and second actuating cylinders 51, 52, the respective spring element 53, 54 is not assigned to the base side 51a, 52a but to the rod side 51b, 52b. Accordingly, the lines 81, 82 would then not be assigned to the rod side 51b, 52b but to the base side 51a, 52a. In order to achieve the "bolted" and "unlocked" operating states in a pressure-free or current-free state, according to the invention, the first and second actuating cylinders 51, 52 would then have to be connected to the driving pins 8a and the actuating elements 8b via suitable guides or deflection elements. This statement applies to all of the embodiments described here.

[0032] In addition, the Fig. 5 schematically shows a first pressure source 61 with a low pressure ND and a second pressure source 62 with a high pressure HD, which can each be, for example, a hydraulic buffer that can be supplied with hydraulic energy via an open or closed hydraulic circuit of the mobile crane 1 or on the rod side or bottom side from the telescoping device 7. The first pressure source 61 is connected via a third line 83 with low pressure ND to a first valve 71 for the first actuating cylinder 51 and in parallel to a second valve 72 for the second actuating cylinder 52. In a corresponding manner, the second pressure source 62 is also connected via a fourth line 84 with high pressure HD to the first valve 71 for the first actuating cylinder 51 and in parallel to the second valve 72 for the second actuating cylinder 52.The first and second valves 71, 72 are each designed as electromagnetically actuated two-way valves, the so-called working connection of which is de-energized and thus connected to the third line 83 with low pressure ND in the rest position of the first and second valves 71, 72. Therefore, in a de-energized state, such as in the event of a fault, the valves 71, 72 move to their rest position and connect the first pressure source 61 with low pressure ND to the first and second actuating cylinders 51, 52. In an actuated or energized state, the valves 71, 72 connect the fourth line 84 with high pressure HD to the first and second actuating cylinders 51, 52, respectively. Thus, during normal operation, the first and second actuating cylinders 51, 52 can be moved via the valves 71, 72 into the desired operating states and in the desired sequence.

[0033] In order to move the actuating cylinders 51, 52 in an emergency operation from the operating states "bolted" and "unlocked", which automatically occur when there is no pressure or no current, to the operating states "unbolted" and "locked" for retracting the telescopic cylinder 2 in a selected sequence, a third valve 73 and a fourth valve 74 are arranged in the first line 81 and the second line 82, respectively, between the first actuating cylinder 51 and the second actuating cylinder 52, respectively, and the first valve 71 and the second valve 72, respectively. These third and fourth valves 73, 74 are also each designed as two-way valves, but are hydraulically actuated and depressurized in the rest position, and connect their working connection to the third line 83 with low pressure ND.In the pressureless state, the third valve 73 connects the first actuating cylinder 51 via the first valve 71 to the first pressure source 61 and the fourth valve 74 connects the second actuating cylinder 52 via the second valve 72 to the second pressure source 62. The third and fourth valves 73, 74 assume this position in normal operation.

[0034] For emergency operation, a fifth line 85 with high pressure HD and a sixth line 86 with high pressure HD are connected to the third valve 73 and the fourth valve 74, on the one hand to an inlet of the respective third and fourth valve 73, 74 and on the other hand to a hydraulic control inlet of the third and fourth valve 73, 74. By applying high pressure HD to the fifth line 85 or the sixth line 86, in a first step, the respective third or fourth valve 73, 74 is moved from a rest position to its operating position, as a result of which the fifth line 85 is then connected to the first actuating cylinder 51 and the sixth line 86 is connected to the second actuating cylinder 52. In emergency operation, the first and second actuating cylinders 51, 52 can thus be moved into the desired operating states in the desired sequence by specifically applying pressure to the fifth or sixth line 85, 86.The third and fourth valves 73, 74 also have the task of isolating the first and second actuating cylinders 51, 52 for emergency operation from the normal supply via the third and fourth lines 83, 84.

[0035] It is also conceivable to connect the fifth and sixth lines 85, 86 only to the third and fourth valves 73, 74 at their hydraulic control inputs and to provide additional lines (not shown) with high pressure HD, which are coupled to the first and second lines 81, 82 between the first and second actuating cylinders 51, 52 and the third and fourth valves 73, 74, in order to then move the actuating cylinders 51, 52 in the desired manner via a pressurization, after the first and second lines 81, 82 are separated from the third and fourth lines 83, 84 of normal operation via the third and fourth valves 73, 74.

[0036] All valves 71, 72, 73, and 74 are located in the telescopic boom 2. Corresponding hydraulic buffers for the first and second pressure sources 61, 62 are also located in the telescopic boom 2, and the coupling points for the fifth and sixth lines 85, 86 are located on the telescopic boom 2.

[0037] In the Fig. 6 is a schematic hydraulic diagram of an operating state of the first and second actuating cylinders 51, 52 according to a second embodiment, wherein the first and second actuating cylinders 51, 52 are connected as before to the Fig. 5 are designed in detail, and the first actuating cylinder 51 is in the "bolted" operating state and the second actuating cylinder 52 is in the "unlocked" operating state. Here, too, in a low-pressure or pressureless state, which also occurs in the event of a malfunction, the "bolted" and "unlocked" operating states of the first and second actuating cylinders 51, 52 are always automatically set in accordance with the invention.

[0038] As a significant difference to the first embodiment according to Fig. 5, the spring elements 53, 54 of the first and second actuating cylinders 51, 52 have different force levels, i.e., the first spring element 53 is harder than the second spring element 54. Thus, the two actuating cylinders 51, 52 can be supplied with hydraulic oil via a first line 81 and a second line 82, respectively, which then flow into a common seventh line 87. The seventh line 87 is connected to a fifth pressure source 65, which can variably supply the seventh line 87 with a low pressure ND, a medium pressure MD, and a high pressure HD for switching the two actuating cylinders 51, 52.The interaction of the pressure states in the seventh line 87 and the mutually different force levels of the first spring element 53 and the second spring element 54 results in the "unbolted" and "locked" operating states of the two actuating cylinders 51, 52 in a high-pressure state HD in the seventh line 87, and in the "bolted" and "locked" operating states in the seventh line 87 in a medium-pressure state MD. With this configuration, by applying a medium pressure MD to the seventh line 87, the second actuating cylinder 52 retracts and the first actuating cylinder 51 does not.

[0039] In this second embodiment, all operating states of the two actuating cylinders 51, 52 can be achieved with only a single seventh line 87 through the different force levels of the spring elements 53, 54.

[0040] In the present case, the low pressure ND is below 10 bar, the medium pressure MD is between 20 and 60 bar, and the high pressure HD is between 80 and 120 bar. The force level of the first spring element 53 is then 7000 N + / - 2000 N and that of the second spring element 54 is 3000 N + / - 1000 N. A distance of 10 bar or 20 bar between the low pressure ND and the medium pressure MD, as well as between the medium pressure MD and the high pressure HD, was chosen in order to obtain clear switching states of the actuating cylinders 51, 52 via a pressure specification in the seventh line 87. It is of course for a specialist to find suitable values ​​for the low pressure ND, medium pressure MD, high pressure HD, and the two spring forces in a suitable ratio to one another in order to be able to reliably switch and achieve the desired movement of the actuating cylinders 51, 52 between their respective operating states.It goes without saying that, depending on the design of the mobile crane and its hydraulic system, the values ​​for low pressure ND, medium pressure MD, high pressure HD and the spring forces may therefore deviate from the aforementioned exemplary value ranges.

[0041] The fifth pressure source 65 has been described above as variable in order to supply the seventh line 87 with a low pressure ND, a medium pressure MD or a high pressure HD for switching the two actuating cylinders 51, 52. This variable pressure source 65 can, for example, be designed as an open hydraulic circuit with a hydraulic pump 66 with a constant delivery rate, first and second valves 71, 72, first and second pressure relief valves 75, 76 and a reservoir 67 for the hydraulic oil return. The hydraulic pump 66 is connected on the output side to the seventh line 87. Within the fifth pressure source 65, the seventh line 87 for providing the high pressure HD is connected to the hydraulic pump 66 and in parallel to the first pressure relief valve 75, which is connected to the reservoir 67 via a third return line 93.The high pressure HD in the seventh line 87 is adjusted via the first pressure relief valve 75 in interaction with the hydraulic pump 66. Furthermore, the seventh line 87, for providing the medium pressure MD, is connected in parallel to the first valve 71, which is connected on the output side to the second pressure relief valve 76 and is connected to the reservoir 67 via a second return line 92. Furthermore, the seventh line 87, for providing the low pressure ND, is in turn connected in parallel to the second valve 72, which is connected on the output side to the reservoir 67 via a first return line 91.

[0042] The low-pressure state ND or a pressureless state is also established here according to the invention when the power or pressure supply fails, as occurs, for example, in the event of a malfunction, and the first and second valves 71, 72 move to their rest position, thereby automatically setting the "bolted" and "unlocked" operating states for the first and second actuating cylinders 51, 52. The seventh pressure line 87 is then connected to the container 67 via the second valve 72 and the first return line 91.

[0043] During normal operation, by switching the first and second valves 71, 72 to their rest position, a low pressure ND is established in the seventh line 87, causing the first and second actuating cylinders 51, 52 to move into the “bolted” and “unlocked” operating states. The hydraulic oil then flows into the reservoir 67 via the first return line 91. To actuate the second actuating cylinder 52 from its “unlocked” operating state to the “locked” operating state, the second valve 72 is closed, and a medium pressure MD is established in the seventh line 87 via the connection of the seventh line 87 via the first valve 71 and the second pressure relief valve 76, as well as the second return line 92, to the reservoir 67 in the seventh line 87. This is essentially due to the appropriately adjusted second pressure relief valve 76 and the force level of the second spring element 54, which is matched to the medium pressure MD.If the first valve 71 is now also closed, the first pressure relief valve 75 determines the pressure in the seventh line 87, which then adjusts to high pressure (HD). This then moves the first actuating cylinder 51 from the "locked" operating state to the "unlocked" operating state.

[0044] Alternatively, the fifth pressure source 65 can be equipped with an adjustable hydraulic pump 66 with an internal pressure regulator. Accordingly, the valves 71, 72 and the pressure relief valves 75, 76 can then be omitted.

[0045] For emergency operation, the seventh pressure line 87 can then be supplied with low pressure ND, medium pressure MD or high pressure HD via an alternative pressure source to switch the first and second actuating cylinders 51, 52.

[0046] All valves 71, 72 and pressure relief valves 75, 76 are located in the superstructure 6. Only the two actuating cylinders 51, 52 and the associated seventh pressure line 87 are located in the telescopic boom 2. The seventh line 87 runs between the superstructure 6 and the securing and locking unit 8, at least partially through an oil passage in the piston rod 7a of the telescoping device 7. This allows for easy local access to the valves 71, 72 and pressure relief valves 75, 76 in the event of a malfunction. Therefore, emergency operation is actually not necessary, since the valves 71, 72 and the pressure relief valves 75, 76 are easily accessible in the event of a malfunction in the superstructure 6.

[0047] The Fig. 7a to 7c each show a schematic hydraulic plan according to a third embodiment, wherein the first and second actuating cylinders 51, 52 are each in different operating states and, as before, to the Fig. 5. The spring elements 53, 54 have almost the same force level, so that an adjustment of the spring elements 53, 54 can be effected by a comparable pressure. Fig. 7a schematically shows a fifth pressure source 65, which can be, for example, a hydraulic buffer that can be supplied with hydraulic energy via an open or closed hydraulic circuit of the mobile crane 1 or on the rod side or bottom side of the telescoping device 7. This variable fifth pressure source 65 provides, in addition to a low pressure ND, a single further preselected pressure level in the form of a high pressure HD. Regarding values ​​for pressures and spring forces, please refer to the description of Fig. 5. The aforementioned fifth print source 65 can be interpreted in accordance with the Fig. 6, and a seventh line 87 is connected to the first actuating cylinder 51 via a first valve 71 and a first line 81, and to the second actuating cylinder 52 via a second valve 72 and a second line 82. The first and second valves 71, 72 are each designed as electromagnetically actuated two-way valves that are open when de-energized and, when energized, have a check valve that blocks the actuating cylinder 51, 52 but allows any pressure built up in the first and second actuating cylinders 51, 52 to be reduced in the direction of the fifth pressure source 65. Therefore, in a de-energized state, such as in the event of a fault, the valves 71, 72 move to their rest position and connect the fifth pressure source 65 to the first and second actuating cylinders 51, 52.It follows from this that, in the manner according to the invention, in a low-pressure state ND or a pressureless state, which also occurs in the event of a fault, the operating states “bolted” and “unlocked” with respect to the first and second actuating cylinders 51, 52 are always set automatically.

[0048] In the Fig. 7b, the first actuating cylinder 51 remains in the "bolted" operating state and the second actuating cylinder 52 remains in the "secured" operating state. This switching state can be achieved with the single seventh line 87 by mechanically locking the first valve 71 in its rest position by means of a locking element 55 while the second actuating cylinder 52 is in its "unlocked" operating state, i.e., the first valve 71 can only be moved into its operating position once the second actuating cylinder 52 has moved into its "secured" operating state against the force of the second spring element 54. Only then does the locking element 55 allow the first valve 71 to move into its operating position.

[0049] By energizing the second valve 72 and moving the second valve accordingly into its operating position, the second actuating cylinder 52 is now retracted. This results in the operating states "bolted" and "secured" for the first and second actuating cylinders 51, 52.

[0050] If the first valve 71 is now moved from its rest position to its operating position after the mechanical locking by the locking element 55 has been released, the first actuating cylinder 51 can now also be supplied with high pressure HD and thus moved in its operating state “unbolted”. The corresponding Fig. 7c.

[0051] Here too, emergency operation is not necessary, since in the currentless or pressureless operating state, the operating states "bolted" and "unlocked" are automatically set according to the invention and simply by providing the seventh line 87 with hydraulic oil at high pressure HD or alternatively via a backup source, a controlled and sequential switching of the first and second actuating cylinders 51, 52 can take place. Fig. The operating states “Secured” and “Bolted” shown in Figure 7b will only occur for a short period of time, since the first valve 71 will immediately move automatically into its rest position after being released by the locking element 55 and will thus also supply the seventh line 87 with high pressure HD to the first actuating cylinder 51, thus reaching the operating state “Unbolted”.

[0052] The mechanical locking element 55 can be a component of a transmission mechanism present between the first and second actuating cylinders 51, 52 and the driver pins 8a and the actuating elements 8b, which transmission mechanism is preferably a link with corresponding guide paths and drivers that is usually used for this purpose or is constructed in parallel according to a comparable mechanical principle.

[0053] The Fig. Figure 8 shows a schematic hydraulic diagram according to a fourth embodiment, wherein the first and second actuating cylinders 51, 52 are connected as before to the Fig. 5 in detail, and the first actuating cylinder 51 is in the "bolted" operating state and the second actuating cylinder 52 is in the "unlocked" operating state. Here, too, in accordance with the invention, in a low-pressure state ND or a pressureless state, which also occurs in the event of a malfunction, the "bolted" and "unlocked" operating states of the first and second actuating cylinders 51, 52 are always automatically set. The spring elements 53, 54 have virtually the same force level, so that adjustment of the spring elements 53, 54 can be effected using a comparable pressure.

[0054] A first line 81 is connected to the rod side 51b of the first actuating cylinder 51, and a second line 82 is connected to the rod side 52b of the second actuating cylinder 52. Via the spring elements 53, 54, the first actuating cylinder 51 or the second actuating cylinder 52 moves into its spring-loaded and extended rest position in a depressurized state or at low pressure ND in the lines 81, 82. The pressure acting on the piston of the actuating cylinder 51, 52 is lower than the calculated pressure of the spring element 53, 54 in the extended state. The first actuating cylinder 51, when extended without pressure, is assigned to the "bolted" operating state. Whereas the second actuating cylinder 52, when extended without pressure, is assigned to the "unlocked" operating state. Regarding the values ​​for pressures and spring forces, please refer to the description of Fig. 5.

[0055] In addition, the Fig.8 schematically shows a first pressure source 61 for a low pressure ND in the form of a return line into a container 67 and a second pressure source 62 in the form of a hydraulic pump 66 with a high pressure HD. The container 67 is connected via a third line 83 with low pressure ND to a first valve 71 for the first actuating cylinder 51 and in parallel to a second valve 72 for the second actuating cylinder 52. In a corresponding manner, the hydraulic pump 66 is also connected via a fourth line 84 with high pressure HD to the first valve 71 for the first actuating cylinder 51 and in parallel to the second valve 72 for the second actuating cylinder 52. Also arranged between the third and fourth lines 83, 84 is a first pressure relief valve 75 via which the high pressure HD can be adjusted.The first and second valves 71, 72 are each designed as electromagnetically actuated two-way valves, in which, in the de-energized state, their working connection is connected to the third line 83 with low pressure LP. Therefore, in a de-energized state, such as in the event of a malfunction, the valves 71, 72 move to their rest position and connect the container 67 with low pressure LP to the first and second actuating cylinders 51, 52. In an actuated or energized state, the valves 71, 72 connect the fourth line 84 with high pressure HD to the first and second actuating cylinders 51, 52, respectively. Thus, during normal operation, the first and second actuating cylinders 51, 52 can be moved via the valves 71, 72 into the desired operating states and in the desired sequence.

[0056] All valves 71, 72 are located in the superstructure 6. Only the two actuating cylinders 51, 52 and the associated first and second lines 81, 82 are located in the telescopic boom 2. The first and second lines 81, 82 run between the superstructure 6 and the securing and locking unit 8, at least partially through two oil passages in the piston rod 7a of the telescoping device 7. This allows for easy local access to the valves 71, 72 and pressure relief valves 75, 76 in the superstructure 6 in the event of a malfunction. This actually eliminates the need for emergency operation, since the valves 71, 72 and pressure relief valves 75, 76 are easily accessible in the event of a malfunction in the superstructure 6.

[0057] The arrangement of two oil passages in the piston rod 7a of the telescoping device 7 of a telescopic boom 2 is considered to be an independent inventive idea. List of reference symbols 1 mobile crane 2 telescopic booms 2a Head end 2b Foot end 3 undercarriage 4 wheel chassis 5 wheel 6 superstructures 7 Telescopic device 7a Piston rod 7b Cylinder housing 8 Securing and locking unit 8a Driving pin 8b Actuating element 9 rocker cylinders 10 basic boxes 12 first bolting hole 15 Foot connection 20 first inner box 21 first locking bolt 22 second bolting hole 23 first recess 30 second inner box 31 second locking bolt 32 third bolting hole 33 second recess 40 third inner box 41 third locking bolt 43 third recess 51 first actuating cylinder 51a Bottom side of the first actuating cylinder 51b Rod side of the first actuating cylinder 52 second actuating cylinder 52a Bottom side of the second actuating cylinder 52b Rod side of the second actuating cylinder 53 first spring element 54 second spring element 55 Locking element 61 first print source 62 second pressure source 63 third pressure source 64 fourth pressure source 65 fifth pressure source 66 Hydraulic pump 67 containers 71 first valve 72 second valve 73 third valve 74 fourth valve 75 first pressure relief valve 76 second pressure relief valve 81 first line 82 second line 83 third line 84 fourth line 85 fifth line 86 sixth line 87 seventh line 91 first return line 92 second return line 93 third return line A retraction position B first extended position C second extended position D third extended position HD high pressure MD medium pressure ND low pressure Underground L longitudinal direction S swivel axis W rocker axle

Claims

[1] Mobile crane (1) with a telescopic boom (2), comprising a base box (10) with retractable and extendable inner boxes (20, 30, 40) and a securing and locking unit (8) which comprises a first actuating cylinder (51) and a second actuating cylinder (52), each designed as a single-acting hydraulic cylinder with a first spring element (53) and a second spring element (54) as well as a first line (81) and a second line (82), wherein the first actuating cylinder (51) moves locking bolts (21, 31, 41) between the operating states of unbolted and bolted and the second actuating cylinder (52) moves driving bolts (8a) between the operating states of secured and unlocked, characterized by that in the event of a fault, the first actuating cylinder (51) moves into the bolted operating state and the second actuating cylinder (52) moves into the unlocked operating state. [2] Mobile crane (1) according to claim 1, characterized bythat in the event of a fault, the first actuating cylinder (51) moves into the bolted operating state via the first spring element (53) and the second actuating cylinder (52) moves into the unlocked operating state via the second spring element (54). [3] Mobile crane (1) according to claim 1 or 2, characterized by that the first spring element (53) is assigned to a bottom side (51a) of the first actuating cylinder (51), the second spring element (54) is assigned to a bottom side (52a) of the second actuating cylinder (52), the first line (81) is connected only to one rod side (51b) of the first actuating cylinder (51) and the second line (82) is connected only to one rod side (52b) of the second actuating cylinder (52). [4] Mobile crane (1) according to one or more of claims 1 to 3, characterized bythat a first valve (71) is arranged in the first line (81), a second valve (72) is arranged in the second line (82) and the first and second valves (71, 72) move automatically into their rest position in the event of a fault and as a result the first actuating cylinder (51) moves into the bolted operating state and the second actuating cylinder (52) moves into the unlocked operating state. [5] Mobile crane (1) according to one or more of claims 1 to 4, characterized by that the first spring element (53) has a higher force level than the second spring element (54), so that with a medium pressure (MD) applied to the second line (82), the second actuating cylinder (52) moves from the unlocked operating state to the secured operating state and with a high pressure applied to the first line (81), the first actuating cylinder (51) moves from the bolted operating state to the unbolted operating state. [6] Mobile crane (1) according to claim 4 or 5, characterized by that the first valve (71) and the second actuating cylinder (52) are mechanically locked via a locking element (55) in such a way that the first valve (71) is locked for movement into its rest position as long as the second actuating cylinder (52) is in the unlocked operating state. [7] Mobile crane (1) according to one or more of claims 1 to 6, characterized by that the mobile crane (1) has a telescopic device (7), the first line (81) and the second line (82) are connected to a common seventh line (87) and the seventh line (87) is passed through the telescopic device (7). [8] Mobile crane (1) according to one or more of claims 1 to 6, characterized bythat the mobile crane (1) has a telescopic device (7) and the first line (81) and the second line (82) are each passed separately through the telescopic device (7). [9] Mobile crane (1) according to one or more of claims 4 to 8, characterized by that the mobile crane (1) has a superstructure (6) and the first and second valves (71, 72) are arranged in the superstructure (6).

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