Counterbalance forklift truck with a lift height measuring system

Abstract

A counterbalance forklift (1) with a lifting mast (10) and a load handling device (11) arranged on the lifting mast (10) that can be raised and lowered, wherein a lifting height measuring system is provided for detecting the lifting height of the load handling device (11), wherein the lifting height measuring system is designed as a cable length sensor (S) comprising a measuring cable (M) that can be unwound on a cable drum (40) against the force of a reset device (41) and a sensor device for detecting the rotational movement of the cable drum (40), wherein the cable length sensor (S) is arranged on the lifting mast (10) such that the measuring cable (M) leading out of the measuring cable outlet (42) is arranged within the longitudinal extent (L) of the lifting mast (10) over the entire measuring range, characterized in that the lifting mast (10) is arranged at least partially within two front drive wheels (7) of the counterbalance forklift (1), wherein the The rope length sensor (S) has a closed flat housing (F),in which the cable drum (40) is arranged and which is provided with a measuring cable outlet (42) arranged vertically spaced from the cable drum (40), wherein a bellows (46) with a wiper nozzle (47) is arranged at the measuring cable outlet (42) of the flat housing (F), through which the measuring cable (M) is guided, and wherein a nozzle guard (50) is arranged on the flat housing (F), which forms a stop for the bellows (46) provided with the wiper nozzle (47) when the measuring cable (M) is pulled out of the flat housing (F).

Description

[0001] The invention relates to a counterbalance forklift truck with a lifting mast and a load handling device arranged on the lifting mast that can be raised and lowered, wherein a lifting height measuring system is provided for detecting the lifting height of the load handling device, wherein the lifting height measuring system is designed as a rope length sensor comprising a measuring rope that can be unwound on a rope drum against the force of a reset device and a sensor device for detecting the rotational movement of the rope drum, wherein the rope length sensor is arranged on the lifting mast in such a way that the measuring rope leading out of the measuring rope exit is arranged within the longitudinal extent of the lifting mast over the entire measuring range.

[0002] For measuring the lifting height of industrial trucks, lifting height measuring systems are already known in which a sensor interacts with a movable part of the lifting mast by means of a friction wheel. An industrial truck with a friction wheel as a lifting height measuring system is known from DE 197 31 687 A1. Furthermore, non-contact lifting height measuring systems for industrial trucks are already known, which operate on the basis of optical measuring methods, for example, laser beams, or on the basis of ultrasound. Industrial trucks with such lifting height measuring systems are known, for example, from DE 10 2006 037 928 A1, DE 10 2008 020 170 A1, and DE 32 08 747 A1. However, such measuring methods cannot be used satisfactorily under harsh or dusty environmental conditions where high levels of contamination occur.

[0003] From EP 1 203 743 B1, a warehouse stacker, for example a reach truck, high-bay stacker or high-bay order picker, is known in which the lifting height measuring system is designed as a cable length sensor. Such warehouse stackers are used within a warehouse in an enclosed storage area.

[0004] Unlike warehouse forklifts, counterbalance forklifts are operated outdoors and are exposed to weather conditions such as rain or ice. They can also operate on unpaved surfaces, resulting in shocks, vibrations, and jolts. Furthermore, counterbalance forklifts are used in dusty and dirty production facilities with high levels of contamination, such as foundries, cement plants, fertilizer factories, and port facilities. Due to these specific operating conditions, the cable length encoders used in warehouse forklifts are not suitable for use in counterbalance forklifts.

[0005] A counterbalance forklift of this type is known from US Patent 5,749,696 A.

[0006] The DE 20 2004 018 643 U1 reveals a rope length transmitter.

[0007] From DE 10 2005 037 575 A1 a lifting frame of an industrial truck with an endless traction element guided over two deflection rollers as a lifting height measuring system is known.

[0008] DE 100 05 958 A1 discloses a device for determining the height position of the fork of a forklift truck, comprising a coupling element wound on a winding device and designed as a wire, which is attached to the fork of the forklift truck.

[0009] From DE 20 2004 014 184 U1 a device for cleaning a measuring rope in a rope length transmitter is known.

[0010] The present invention is based on the objective of providing a counterbalance forklift of the type mentioned at the outset, which is equipped with a robust and reliably operating lifting height measuring device that is adapted to the operating conditions of a counterbalance forklift.

[0011] This problem is solved according to the invention by arranging the lifting frame at least partially within two front drive wheels of the counterbalance forklift, wherein the rope length sensor has a closed flat housing in which the rope drum is arranged and which is provided with a measuring rope outlet arranged vertically spaced from the rope drum, wherein a bellows with a wiper nozzle is arranged at the measuring rope outlet of the flat housing, through which the measuring rope is guided, and wherein a nozzle guard is arranged on the flat housing, which forms a stop for the bellows provided with the wiper nozzle when the measuring rope is pulled out of the flat housing.

[0012] The rope length sensor according to the invention, used as a lifting height measuring system for a counterbalance forklift, has a flat housing that is elongated in the vertical direction and narrow in the axial direction of the rope drum. This housing contains the mechanical components of the rope length sensor. The flat housing is equipped with the rope drum containing the measuring rope and an upward-facing measuring rope outlet, spaced vertically, particularly downwards, from the rope drum. The measuring rope can be pulled upwards out of the flat housing from this outlet. Due to this housing design, the rope length sensor with the flat housing can be mounted at an optimal location on the counterbalance forklift to achieve a visibility-optimized arrangement on or in the lifting mast, where the rope length sensor obstructs the operator's view through the lifting mast as little as possible.The installation of the cable drum within the enclosed flat housing provides a protected arrangement for the cable drum and allows for the integration of appropriate cleaning devices on or within the housing to minimize malfunctions in the mechanical components caused by moisture, ice, or dirt. Furthermore, the vertical positioning of the measuring cable exit from the cable drum enables the measuring cable to be guided across the entire lifting range of the load-handling device and thus across the entire measuring range within the longitudinal extension of the lifting frame in the vehicle's longitudinal direction.This provides protected guidance for the measuring cable as it unwinds from the cable drum and exits the measuring cable outlet. This prevents the measuring cable from protruding in front of or behind the lifting frame, thus protecting it from external damage, for example, when approaching a shelf or load with the front edge of the lifting frame. This mounting position allows for simple protection of the measuring cable against external damage.

[0013] According to the invention, a bellows with a wiper nozzle is arranged at the measuring cable outlet of the flat housing, through which the measuring cable is guided. With this wiper nozzle, which the measuring cable passes through as it enters and exits the flat housing, coarse dirt, water droplets, or ice adhering to the measuring cable can be easily wiped off, thus achieving a preliminary cleaning of the measuring cable. Such a wiper nozzle can therefore effectively reduce wear and increase the service life of the measuring cable, while also effectively reducing the ingress of dirt, water, or ice into the flat housing of the cable length sensor. The arrangement and mounting of the wiper nozzle on a bellows allows for easy guidance and thus movement of the wiper nozzle.In conjunction with the bellows, the wiper nozzle can adapt to the path of the measuring cable and enables a large cable exit angle from the flat housing. In the cable length sensor according to the invention, tolerances and wear of the lifting frame, as well as deflections of the lifting frame, which occur particularly under load at high lifting heights, influence the path angle of the measuring cable. By arranging the wiper nozzle in the bellows, it is easily achieved that the wiper nozzle can adapt to the path of the measuring cable and that the measuring cable can move freely. The bellows reduces the friction between the wiper nozzle and the measuring cable, thus further reducing wear and increasing the service life of the measuring cable.

[0014] According to the invention, a nozzle guard is further arranged on the flat housing, which forms a stop for the bellows equipped with the wiper nozzle when the measuring cable is pulled out of the flat housing. When used in a counterbalance forklift, the measuring cable can become stuck in the wiper nozzle due to coarse dirt or freezing water. The stop for the wiper nozzle easily prevents the wiper nozzle from being torn off the cable length sensor when the measuring cable is pulled out.When a measuring rope becomes stuck in the wiper nozzle, the wiper nozzle, located in the bellows, comes into contact with the stop when the measuring rope is pulled out of the rope length sensor. This stop prevents further movement of the wiper nozzle, ensuring that the wiper nozzle remains stationary as the rope is pulled out further. This allows the measuring rope to run freely, removing coarse contaminants from the wiper nozzle or breaking up frozen water. The stop thus provides effective protection against the measuring rope freezing in the wiper nozzle, for example, in a counterbalance forklift parked overnight, or against the measuring rope becoming jammed in the wiper nozzle by trapped dirt particles. The stop reliably prevents the wiper nozzle from being torn off the flat housing when the measuring rope is pulled out if it becomes jammed.The robustness and reliability of the rope length sensor according to the invention can be further increased with such a stop for the wiper nozzle.

[0015] Particular advantages arise when, according to a further development of the invention, a sensor housing of the sensor device can be flanged to the flat housing. The cable length encoder according to the invention, as a lifting height measuring system for a counterbalance forklift, thus has a two-part modular design consisting of the vertically elongated flat housing and a flanged sensor housing with the sensor device. The flat housing contains the mechanical components. The sensor housing with the sensor device, which can be flanged to the flat housing, contains the electronic components. This modular design allows for easy replacement of the corresponding module in the event of wear-related malfunctions, defects, or damage to the relevant components resulting from the operating conditions of the counterbalance forklift, thereby reducing operating costs for the cable length encoder.

[0016] According to a first embodiment of the invention, the lifting mast is designed as a multi-lift mast with a fixed mast and at least one extension mast. At least one lifting cylinder assembly is provided for raising the extension mast, and the load-handling device can be raised by means of a traction element via the lifting cylinder assembly. The cable length sensor is arranged in the upper region of the fixed mast, and the measuring cable is connected to the extension mast. In such a multi-lift mast, where the load-handling device is simultaneously raised via the traction element when the extension mast is raised by the lifting cylinder assembly, the arrangement of the flat housing in the upper region of the fixed mast and the coupling of the measuring cable to the extension mast result in a visually optimized mounting of the cable length sensor. Due to the connection of the measuring cable to the extension mast, the lifting height of the load-handling device is measured indirectly by the movement of the extension mast.In such lifting masts, the load-handling device and the measuring cable move in a 2:1 ratio. The lifting height of the load-handling device thus corresponds to twice the unwound length of the measuring cable supplied by the sensor device of the cable length encoder. Furthermore, if the cable length encoder is located on the inside of a lifting mast profile of the support mast, the cable length encoder and the measuring cable are protected from external damage in a transverse direction within the lifting mast.

[0017] According to a further embodiment of the invention, the lifting frame is designed as a multi-lifting frame with a fixed mast and at least one extension mast. At least one lifting cylinder assembly is provided for raising the extension mast, and the load-handling device can be raised by means of a free-lift cylinder assembly. The cable length sensor is located at least partially in the space between the fixed mast and the drive wheel in the lower region of the fixed mast, and the measuring cable is connected to the load-handling device. In such a lifting frame, where the load-handling device can be raised independently of the extension masts by means of the free-lift cylinder assembly, the lifting height of the load-handling device can be easily determined by connecting the measuring cable to the load-handling device. The lifting height of the load-handling device corresponds to the value of the unwound measuring cable length supplied by the sensor assembly of the cable length sensor.The rope length sensor must be positioned at a lower point on the mast to determine the lifting height across the entire lifting range of the load-handling device. The flat design of the rope length sensor according to the invention, with a narrow flat housing and a measuring rope exit spaced vertically from the rope drum, allows for optimized visibility and protection from external damage when installing the rope length sensor on the outside of the mast between the drive wheel and the mast.

[0018] Particular advantages arise when the rope length sensor is mounted under a protective housing on the mast. With such a roof-like protective housing, preferably a metal one, the rope length sensor can be easily protected from damage caused by external mechanical influences, such as falling loads. Such a protective housing can thus easily extend the service life of a rope length sensor when used on a counterbalance forklift.

[0019] In a preferred embodiment of the invention, when the cable length sensor is arranged in the lower section of the support mast, a protective rail is provided on the mast to protect the measuring cable. The lower section of the support mast is a vulnerable area. By using a protective rail, preferably a metal one, the measuring cable, which extends from the flat housing, can be easily protected against external damage in the lower section of the mast, thereby increasing the service life and lifespan of the measuring cable.

[0020] To minimize obstruction of the view of the load-handling device due to the guard rail's placement, the guard rail is equipped with viewing openings for improved visibility of the load-handling device. Appropriate viewing openings, such as slotted or oblong cutouts, in the guard rail allow for a simple and optimized design that optimizes visibility.

[0021] According to a preferred embodiment of the invention, a deflection pulley is arranged in the flat housing, over which the measuring rope is guided. The deflection pulley is positioned in the measuring rope direction between the rope drum and the measuring rope exit and is rotatably mounted in the flat housing. With such a deflection pulley, which is arranged at least partially below the measuring rope exit in the vertical direction, the measuring rope unwound downwards from the rope drum is deflected upwards to the measuring rope exit in the rope length sensor according to the invention. This allows for the simple vertical separation of the measuring rope exit from the rope drum. The integration and mounting of the deflection pulley in the flat housing results in an arrangement of the deflection pulley that is protected against external damage and contamination, leading to a high degree of robustness in the rope length sensor according to the invention.Furthermore, integrating the deflection pulley into the flat housing allows for a high tolerance between the pulley, the measuring cable exit, and the attachment of the measuring cable to the load-handling device or the extension mast. This ensures that tolerances of the lifting frame have no negative impact on the position of the deflection pulley or on the cable guidance of the measuring cable over the pulley. The inventive integration and mounting of the deflection pulley in the flat housing thus also results in reduced wear and an increased service life for both the measuring cable and the deflection pulley.

[0022] A particular advantage is that the deflection pulley is arranged vertically downwards from the cable drum, especially at least partially below the measuring cable exit, and the flat housing between the cable drum and the deflection pulley is designed as a cable guide channel. With such an arrangement of the deflection pulley, it can be easily achieved that, in the cable length sensor according to the invention, the measuring cable exit is positioned vertically below the cable drum, so that the cable length sensor can be mounted on the lifting frame in the manner according to the invention. Furthermore, the design of the flat housing between the deflection pulley and the cable drum as a cable guide channel allows corresponding additional components, for example, a cleaning device for the measuring cable, to be arranged within the flat housing in a space-saving and protected manner.

[0023] Advantages arise with regard to the slim design of the flat housing if the cable drum is arranged axially immovably within the flat housing. In a cable length sensor according to the invention, it must be ensured that the measuring cable is wound and unwound in a single layer on the cable drum in order to determine a clear and precise stroke height signal by measuring the rotational movement of the cable drum. Due to the vertically spaced arrangement of the deflection pulley from the cable drum, a corresponding distance can be achieved in the cable length sensor according to the invention between the deflection pulley and the axially fixed cable drum. This ensures that the measuring cable experiences only a small angular deflection between the deflection pulley and the cable drum during winding and unwinding, and that, with an axially fixed cable drum, the single-layer winding of the cable drum is reliably and reliably achieved.

[0024] According to a preferred embodiment of the invention, the nozzle guard has a fork shape with a fork opening formed by the fork, wherein the measuring cable is guided through the fork opening and the fork forms a stop that interacts with the wiper nozzle. A stop for the wiper nozzle arranged in the bellows can be easily formed with, for example, a two-pronged fork, whereby the measuring cable can run freely through the fork opening.

[0025] The robustness and reliability of the rope length sensor according to the invention can be further increased by arranging a cleaning device for the measuring rope in the form of a rope cleaning brush within the flat housing. The measuring rope thus passes through the rope cleaning brush before being wound onto the rope drum. The rope cleaning brush reliably removes dirt and water adhering to the measuring rope, thereby extending its service life and reducing wear. Furthermore, the rope cleaning brush reliably prevents the measuring rope from freezing to the drum, further enhancing the robustness and reliability of the rope length sensor according to the invention.

[0026] The rope cleaning brush can be formed by several longitudinal brushes directed towards the measuring rope passing through it, encircling the measuring rope in a ring or star shape. According to a preferred embodiment of the invention, the rope cleaning brush is formed by a spirally wound brush with inwardly directed bristles, the measuring rope passing centrally through the brush. With such a spirally or helically wound brush, which preferably has several turns through which the measuring rope passes before being wound onto the rope drum, the passing measuring rope can be reliably cleaned from all sides, with only minimal losses of tensile force due to low friction.

[0027] Preferably, the rope cleaning brush is arranged between the rope drum and the deflection pulley in the rope guide channel of the flat housing. Due to the design of the vertically elongated flat housing with the existing rope guide channel between the rope drum and the deflection pulley, the rope cleaning brush can be arranged in a space-saving manner within the rope guide channel. The rope cleaning brush can be easily positioned and secured in this area of ​​the flat housing, for example, by inserting the spirally wound brush between upper and lower stops located on the flat housing, with the flat housing at least partially enclosing or holding it.

[0028] Particular advantages can be achieved if the flat housing is equipped with a drain opening in its lower section to allow dirt and water to drain away. Such a drain opening in the flat housing ensures that water and dirt that have entered the housing of the cable length sensor or been brushed off the measuring cable by the cable cleaning brush can drain away in the lower section of the housing. This further increases the reliability of the cable length sensor.

[0029] According to a preferred embodiment of the invention, the flat housing has a two-part structure consisting of a shell-shaped base and a shell-shaped cover. The base contains the cable drum with the return mechanism, the cable cleaning brush, and the measuring cable outlet, while the deflection pulley is cantilevered within the base. This design simplifies the assembly of the flat housing with its mechanical components. The cable drum with the return mechanism, the measuring cable, the cable cleaning brush, and the bellows with the wiper nozzle at the measuring cable outlet can be mounted in the base, and the flat housing can then be closed by placing and securing the cover.

[0030] It is advantageous for the base to be fitted with the nozzle guard. If both the lid and base are made of plastic, the nozzle guard can easily be manufactured as a single piece on the base.

[0031] With regard to the flat design of the rope length sensor according to the invention, further advantages arise if, according to a further development of the invention, the return mechanism is designed as a drive spring, in particular a coil spring, which is arranged within the axial installation space of the rope drum. The return mechanism thus requires no additional installation space in the axial direction of the flat housing and therefore of the rope length sensor.

[0032] The sensor housing with the sensor device can be easily arranged on the flat housing and attached in a suitable manner if, according to an advantageous embodiment of the invention, the lid part of the flat housing is provided with a centering flange for the sensor housing.

[0033] The centering flange is preferably formed by an annular centering neck of the cover part, into which the sensor housing of the sensor device can be inserted with an annular centering extension. Such a centering flange can be easily manufactured using the centering neck and the centering extension and allows for simple mounting of the sensor housing to the flat housing via a flange connection.

[0034] If, according to an advantageous embodiment of the invention, the centering flange is arranged in an axially inwardly directed bulge of the cover part of the flat housing, advantages arise with regard to a small axial extent and flat design of the flat housing, since the centering flange can be arranged within the axial extent of the flat housing.

[0035] In the rope length sensor according to the invention, the sensor assembly is coupled to the rope drum in a rotationally fixed manner in order to accurately detect the rotational movement of the rope drum with the measuring rope. According to a preferred embodiment, the sensor assembly comprises a sensor input shaft rotatably mounted in the sensor housing, which can be coupled to the rope drum in a rotationally fixed manner by means of a shaft coupling device, wherein the shaft coupling device and the centering flange are arranged to overlap axially. By axially superimposing the centering flange and the shaft coupling device in the same cross-sectional plane, the axial installation space requirement of a rope length sensor according to the invention can be further reduced, since the shaft coupling device and the centering flange utilize the same installation space in the axial direction and are preferably arranged within the axial extent of the flat housing.

[0036] Particular advantages arise when the shaft coupling device is formed by two interlocking toothed sections, one toothed section being integrally formed on the cable drum and the other on the sensor input shaft. By axially superimposing the shaft coupling device with the centering flange, a simple shaft coupling device can be formed using a plug-in coupling consisting of two interlocking toothed sections, thus facilitating the joining of the sensor housing to the flat housing. During assembly, the two toothed sections engage and create a positive-locking connection between the cable drum and the sensor input shaft.Since the axial superimposition of the shaft coupling device with the centering flange obscures the view of the two toothed sections during assembly of the sensor housing, the toothing is designed such that the toothed sections can be connected at the corresponding shaft ends without visual contact. The one-piece formation of the toothed section on the cable drum further reduces the axial dimensions of the cable length sensor according to the invention. Moreover, the one-piece formation of the toothed section on the cable drum enables cost-effective manufacturing with high tolerance accuracy. Preferably, the cable drum with the molded-on toothed section is designed as a plastic component.

[0037] Preferably, the first toothed section is designed as an external toothing on an axial shaft extension of the cable drum, and the second toothed section as an internal toothing in an axial bore of the sensor input shaft. An external toothing on a shaft extension of the cable drum can be easily manufactured. The same applies to an internal toothing arranged in an axial bore of the sensor input shaft.

[0038] The reliability and robustness of the cable length sensor according to the invention are further increased if the sensor housing is designed as a sealed sensor housing, with a shaft sealing device assigned to the sensor input shaft. By designing the corresponding toothed section of the shaft coupling device as an internal toothing on the sensor input shaft, the sensor input shaft can be easily sealed with a shaft sealing device, for example, a shaft seal ring. The shaft sealing device can be arranged in the axial plane of the two toothed sections, so that the shaft sealing device does not require any additional installation space in the axial direction of the cable length sensor.The design of the sensor housing as a sealed enclosure allows for a moisture- and dirt-protected, tightly sealed arrangement of the sensor electronics within an electronics installation space that is sealed off from the environment. This contributes to a long service life for the electronics.

[0039] Preferably, the shaft sealing device is arranged in the area of ​​the centering extension of the sensor housing. A shaft seal ring can be easily installed on the inner circumference of the annular centering extension of the sensor housing.

[0040] A sealed installation space for the electronics of the sensor housing can be achieved with minimal construction effort if, according to a preferred embodiment of the invention, the sensor housing has a two-part structure consisting of a base part and a cover part, wherein the base part is sealed against the cover part by means of a sealing device, in particular an O-ring, and forms a sealed electronics installation space.

[0041] Preferably, the ring-shaped centering process is formed on the base part.

[0042] According to a preferred embodiment of the invention, the sensor device is designed as an absolute sensor device. With an absolute sensor device, the lifting height of the load-handling attachment can be measured after commissioning of the counterbalance forklift without reference runs or sensor calibration. The elimination of reference runs subject to tolerances or sensor calibrations leads to increased operational reliability of the cable length sensor according to the invention.

[0043] Preferably, the absolute sensor device comprises a sensor which is connected to the sensor input shaft via a reduction gear located in the sensor housing, particularly in the electronics installation space. The use of such a reduction gear makes it easy to convert several revolutions of the cable drum into a single revolution on a measuring shaft of the sensor, thus ensuring a sensor that measures the stroke height absolutely. The arrangement of the reduction gear in the sealed electronics installation space provides protection against environmental influences and moisture, allowing the reduction gear to be designed for a long service life with minimal construction effort.

[0044] If, according to an advantageous further development of the invention, the absolute sensor device comprises a redundant structure with two sensors, each of which is connected to the sensor input shaft via an intermediate reduction gear arranged in the sensor housing, in particular in the electronics installation space, a high operational reliability of the rope length encoder can be achieved, which meets the highest safety requirements.

[0045] Preferably, the sensor system has a fully redundant design downstream of the sensor input shaft, comprising two separate sensor circuits. Each circuit includes a reduction gear, a sensor, electronics, and a measurement signal output for connection to the counterbalance forklift's control electronics, as well as an electrical power supply. The measured lifting height of the load-handling attachment can be displayed to the operator on a display device of the counterbalance forklift. Additionally or alternatively, the measured lifting height of the load-handling attachment can be further processed within the counterbalance forklift, for example, to meet safety requirements. The redundant design of the sensor system ensures a high level of operational reliability.

[0046] According to a preferred embodiment of the invention, the sensor is designed as a Hall sensor. Hall sensors enable contactless and therefore wear-free measurement, thus further increasing the robustness and reliability of the rope length sensor according to the invention. Furthermore, if the Hall sensor is designed as a differential Hall sensor, the sensor signals remain stable when exposed to external magnetic fields, and external magnetic fields do not affect the measurement results of the rope length sensor.

[0047] According to a preferred embodiment, in the rope length sensor according to the invention, the measuring rope is designed as a steel rope, in particular a stainless steel rope, with a plastic coating. The plastic coating of the steel rope effectively reduces dirt adhesion to the measuring rope, thus further increasing the reliability, robustness, and service life of the rope length sensor.

[0048] Further advantages and details of the invention are explained in more detail with reference to the exemplary embodiments shown in the schematic figures. Here, it is shown that Fig. 1 a counterbalance forklift truck according to the invention in a side view, Fig. 2 a lifting frame in a perspective view with a first embodiment of a rope length transmitter attached according to the invention, Fig. 3 a section of the lifting frame of the Fig. 2 in a cross-sectional view in the longitudinal direction of the vehicle, Fig. 4 the Fig. 3 in one the direction of view of an operator, Fig. 5 a lifting frame in a perspective view with a second embodiment of a rope length transmitter attached according to the invention, Fig. 6 a section of the lifting frame of the Fig. 5 in a cross-sectional view in the longitudinal direction of the vehicle, Fig. 7 the Fig. 6 with drive wheel removed, Fig. 8 a rope length encoder according to the invention in a side view, Fig. 9 a cut along line BB of the Fig. 8, Fig. 10 a cut along line CC of the Fig. 8, Fig. 11 the rope length sensor in the lower vertical area in an enlarged view, Fig. 12 the rope length encoder in the area of ​​the joint between the sensor housing and the flat housing in a resolved representation and Fig. 13 the sensor housing with the reduction gear of the sensor device.

[0049] In the Fig. Figure 1 shows a side view of a counterbalance forklift truck 1 according to the invention. The counterbalance forklift truck 1 comprises, in a central section, a vehicle body 5 formed by a frame 2, a counterweight 3, and a driver's overhead guard 4. A driver's workstation 6 is located within the driver's overhead guard 5.

[0050] Below the driver's workstation 6, a power unit compartment is provided, housing the components of the forklift truck's drive system 1. In an internal combustion engine drive system, an internal combustion engine and the components of the drive system and working hydraulics driven by the internal combustion engine can be arranged below the driver's workstation 6. In a battery-electric drive system, a battery compartment is provided below the driver's workstation 6 to accommodate a power supply unit, for example, a battery pack, which supplies the drive system and the working hydraulics with electrical energy.

[0051] In the Fig. Figure 1 shows wheels in the front area of ​​the counterbalance forklift truck, which are designed as drive wheels 7, and a steering axle 9 with steered wheels 8 in the rear area.

[0052] In the front area of ​​the industrial truck 1, a lifting frame 10 is arranged, on which a load handling device 11 can be raised and lowered.

[0053] The lifting frame 10 comprises a support mast 10a, which is formed by two vertical lifting frame profiles arranged laterally and spaced apart in the transverse direction of the vehicle. The support mast 10a is mounted on the vehicle body 5 so that its inclination can be adjusted by means of a tilting drive 13, which is formed by tilting cylinders.

[0054] The lifting frame 10 is designed as a multi-lifting frame, comprising one or more upwardly extending masts 10b guided in the upright mast 10a, in which the load-handling device 11 is guided in a height-adjustable manner. The load-handling device 11 is preferably designed as a fork carriage on which a load fork 12 formed by two fork tines is arranged. The lifting frame 10 is arranged transversely to the vehicle between the drive wheels 7.

[0055] In order to minimize the frontal dimension, the lifting frame 10, consisting of the upright mast 10a and the extension masts 10b, is arranged partially within the extent of the two front drive wheels 7 of the counterbalance forklift 1 when viewed in the longitudinal direction of the vehicle.

[0056] In the Fig. 2, Fig. 3 to Fig. Figure 4 shows a first embodiment of a lifting frame 10 with a rope length encoder S according to the invention as a lifting height measuring system.

[0057] The lifting frame 10 according to the Fig. 2, Fig. 3 to Fig. 4. The upright mast 10a is designed as an outer mast, within which an extendable mast 10b, designed as an inner mast, is arranged. The load-handling device 11, formed by the fork carriage, is arranged in the extendable mast 10b in a way that allows it to be raised and lowered. The upright mast 10a and the extendable mast 10b are each formed by two lateral, vertical lifting frame profiles spaced apart in the transverse direction of the vehicle, which form a left and right lifting frame column of the lifting frame 10.

[0058] To raise the extendable mast 10b, a lifting cylinder assembly 15 consisting of two lifting cylinders is provided. Each lifting cylinder is attached to the corresponding lifting frame profile of the upright mast 10a by means of a cylinder tube housing and each has an extending and retracting piston rod connected to an upper cross brace 16 of the extendable mast 10b, which connects the two lifting frame profiles of the extendable mast 10b. To raise the load-handling device 11, a traction element 17, for example a lifting chain, is provided. The first end of the traction element is attached to the upright mast 10a, guided downwards over a deflection pulley 18 located at the upper end of the extendable mast 10b, and the second end is attached to the load-handling device 11 in a manner not shown in detail. With such a lifting frame 10, when the lifting cylinders extend, the extendable mast 10b is raised and simultaneously the load-handling device 11 is raised via the traction element 17.In the illustrated embodiment, a traction element 17 is arranged on the outside of each of the right and left lifting frame columns.

[0059] According to the invention, the lifting height measuring system formed by the cable length sensor S is attached to the upper region of the support mast 10a or to the upper region of a lifting cylinder 15. The cable length sensor S is preferably arranged on the inside of a lifting mast column, thus achieving a protected arrangement of the cable length sensor S between the right and left lifting mast columns. A measuring cable M, which can be pulled upwards vertically from the cable length sensor S, can be attached to a corresponding attachment point 19 on the extension mast 10b, which is designed as an inner mast. Preferably, the attachment point 19 is arranged on the upper cross member 16 of the extension mast 10b.

[0060] As from the Fig. 2, Fig. 3 to Fig. As can be seen in Figure 4, the cable length sensor S is mounted on the support mast 10a in a way that optimizes visibility in the longitudinal direction of the vehicle behind the lifting frame profiles of the lifting frame 10, so that the operator's view through the two lifting frame columns is minimally obstructed by the cable length sensor S. The measuring cable M, which is led upwards out of the cable length sensor S, is connected here – as with the Fig. 3 clearly shows - arranged over the entire lifting range within the longitudinal extent L of the lifting frame 10 in the longitudinal direction of the vehicle.

[0061] In the Fig. 5, Fig. 6 to Fig. Figure 7 shows a second embodiment of a lifting frame 10 with a cable length encoder S according to the invention as a lifting height measuring system. With regard to the construction of the upright mast 10a as the outer mast and the at least one extendable mast 10b as the inner mast, the lifting frame 10 is similar to the lifting frame 10 of the Fig. 2 and Fig. 4 identical.

[0062] The lifting frame 10 of the Fig. 5, Fig. 6 to Fig. 7 is designed as a so-called free-lift mast, in which the lifting cylinders arranged on the upright mast 10a, which are not shown in detail, lift the extension mast 10b and a free-lift cylinder 20 is provided in the extension mast 10b for lifting or lowering the load-handling device 11 which is arranged in the extension mast 10b, the extendable piston rod of which is connected to the load-handling device 11 via a traction element 21, for example a lifting chain.

[0063] The lifting frame 10 of the Fig. 5, Fig. 6 to Fig. 7 The rope length sensor S is located in the lower part of the support mast 10a, the so-called mast base. The measuring rope M, which can be pulled out vertically upwards from the rope length sensor S, is attached to the load-bearing device 11 via a suitable attachment point 25.

[0064] As from the Fig. 5, Fig. 6 to Fig. As can be seen in Figure 7, the cable length sensor S is arranged on the outside of a lifting frame profile of the support mast 10a and is positioned, at least partially, in the space between the lifting frame 10 and the adjacent drive wheel 7 in the transverse direction of the vehicle. This allows for a visibility-optimized mounting of the cable length sensor S on the support mast 10a, minimizing obstruction of the operator's view through the two lifting frame columns. The measuring cable M, which can be pulled upwards out of the cable length sensor S, is also arranged along the entire lifting range within the longitudinal extent L of the lifting frame 10 in the longitudinal direction of the vehicle.

[0065] In order to protect the rope length sensor S from falling load parts in both lifting frame variants, a corresponding protective housing 30, preferably designed as a metal housing, is arranged on the support mast 10a, under which the rope length sensor S is arranged.

[0066] In the case of the free-lift scaffold according to the Fig. 5, Fig. 6 to Fig. 7. To protect the measuring cable M connected to the load-handling device 11, a protective rail 31, preferably designed as a metal rail, is provided. This rail is attached to the support mast 10a and extends over the lower section of the support mast 10a, which is vulnerable to collision. The protective rail 31 has, for example, an angled or U-shaped cross-section to provide lateral protection for the measuring cable M. To minimize obstruction of the view of the load-handling device 11, the protective rail 31 is designed to optimize visibility and is provided with viewing openings 32 along its length, which may, for example, have an elongated shape.

[0067] For those in the Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6 to Fig. For the mounting positions of the cable length sensor S shown in Figure 7, a flat design of the cable length sensor S in the axial direction is required. The design of the cable length sensor S according to the invention is described below with reference to the Fig. 8, Fig. 9, Fig. 10, Fig. 11, Fig. 12 to Fig. 13 illustrates this.

[0068] The rope length encoder S according to the invention has a two-module structure consisting of a closed, vertically elongated flat housing F in which the mechanical components of the rope length encoder S are arranged, and a sensor device arranged in a sealed sensor housing G, which can be flanged to the flat housing F in the upper area.

[0069] In the upper region of the flat housing F, a cable drum 40 is rotatably and axially fixedly arranged, on which the measuring cable M can be unwound against the force of a return mechanism 41, for example, a drive spring, in particular a coil spring. The return mechanism 41 generates a return torque on the cable drum 40 for winding up the measuring cable M. In the cable length sensor S according to the invention, the measuring cable M is formed of a stainless steel cable with a plastic sheath.

[0070] A measuring cable outlet 42, pointing upwards, is arranged on the flat housing F at a downward vertical distance from the cable drum 40. The measuring cable M exits vertically upwards from this outlet. The flat housing F is slightly inclined between the upper area containing the cable drum 40 and the lower area containing the measuring cable outlet 42, so that the measuring cable outlet 42 – in the longitudinal direction of the plane of the drawing – Fig. 8 seen - in front of the upper one, in the Fig. 8 right area of ​​the flat housing F lies and the measuring cable M within the axial extent A of the flat housing F upwards at the upper and front, in the Fig. 8. The measuring cable M can be pulled out of the cable length sensor S past the right area of ​​the flat housing F, in which the cable drum 40 is arranged. The measuring cable M is then pulled out of the cable length sensor S, as shown in the Fig. 8 and Fig. 10 is evident - from the rope drum 40 at the rear, in the Fig. The measuring cable M is unwound downwards from the left side of the flat housing F and guided upwards via a deflection pulley 43, which is rotatably mounted in the lower part of the flat housing F, to the vertically upward-pointing measuring cable outlet 42. The deflection pulley 43 is located at least partially below the measuring cable outlet 42. The deflection pulley 43 has a circumferential groove on its outer circumference in which the measuring cable M is arranged. The deflection pulley 43 is arranged in the flat housing F such that the measuring cable M is guided straight downwards to the deflection pulley 43 in the plane of the first turn 44 on the cable drum 40. The deflection pulley 43 is slightly inclined with respect to its axis of rotation, so that the measuring cable outlet 42 is located in the axial direction A in the central part of the flat housing F.

[0071] The area of ​​the flat housing F, which is arranged between the rope drum 40 and the deflection pulley 43 and is slightly inclined towards the front, is designed as a rope guide channel 45 in which a cleaning device R for the measuring rope M, which will be described later, is arranged.

[0072] In the area of ​​the measuring rope exit 42, a bellows 46 is arranged on the flat housing F, which holds a wiper nozzle 47 through which the measuring rope M is guided.

[0073] A nozzle guard 50 is also arranged on the flat housing F, which forms a stop for the wiper nozzle 47 arranged in the bellows 46, in case the measuring rope M gets stuck in the wiper nozzle 47 and is pulled upwards with the measuring rope M, in order to prevent the bellows 46 or the wiper nozzle 47 from being torn off the flat housing F.

[0074] The nozzle guard 50 is formed by a two-pronged fork 51, the prongs of which define a fork opening 52 that is guided upwards by the measuring cable M. The fork opening 52 is dimensioned such that the fork 51 forms a stop on its underside that interacts with the wiper nozzle 47, which is movable upwards in the bellows 46.

[0075] The cleaning device R, arranged in the rope guide channel 45 between the rope drum 40 and the deflection pulley 43, is formed by a rope cleaning brush 60 that runs centrally through the measuring rope M. The rope cleaning brush 60 is designed as a spirally wound brush with bristles directed radially inwards towards the measuring rope M. The rope cleaning brush 60 is inserted in the flat housing F between two axial stops 61, 62. Furthermore, support strips 63, 64 are formed circumferentially on the flat housing F for the rope cleaning brush 60. These support strips extend longitudinally along the rope cleaning brush 60 and the brush rests on them to ensure the rope cleaning brush 60 is centrically aligned with the path of the measuring rope M in the guide channel 45.

[0076] To allow dirt and water cleaned from the measuring rope M by the rope cleaning brush 60 to drain from the flat housing F, a drain opening 65 is provided in the lower area of ​​the flat housing F. The drain opening 65 is formed by a corresponding opening in a wall area of ​​the flat housing F, with the wall area of ​​the flat housing F forming a labyrinthine drain channel 66 that prevents direct water ingress during external cleaning of the rope length sensor S by a water jet directed at the rope length sensor S.

[0077] In the illustrated embodiment, the flat housing F has a two-part structure consisting of a shell-shaped base part FB and a shell-shaped cover part FD, which can be connected to each other, for example by corresponding screw connections 68. The base part FB contains – as shown in the Fig. As can be seen in Figure 11, which shows the flat housing F without the cover part FD, the cable drum 40 with the return mechanism 41, the axial stops 61, 62, and the circumferential support rails 63, 64 for the cable cleaning brush 60, as well as the measuring cable outlet 42, are arranged. A bearing journal 69 is also formed in the base part FB, on which the deflection pulley 43 is cantilevered. The nozzle guard 50, formed by the fork 51, is also arranged on the base part FB of the flat housing F. Furthermore, the drain opening 65 with the drain channel 66 is formed in the base part FB.

[0078] The cover part FD of the flat housing F is provided on the upper side in the area of ​​the rope cleaning brush 60 with a preferably circular in cross-section bulge 67 in order to enable, in conjunction with the support strips 63, 64 arranged in the longitudinal direction of the rope cleaning brush 60, the circumferential support of the rope cleaning brush 60 and the centric alignment of the rope cleaning brush 60 to the measuring rope M.

[0079] In the Fig. Figure 9 shows an axial section through the vertical upper section of the rope length encoder S with the rope drum 40 and the sensor housing G flanged to the flat housing F in the area of ​​the cover part FD.

[0080] For the rotatable mounting of the cable drum 40, the base section FB and the cover section FD of the flat housing F are each designed as bearing plates in which the axially fixed cable drum 40 is rotatably mounted by means of corresponding bearings 70, 71. The return mechanism 41, designed as a drive spring, is arranged completely within the axial installation space of the cable drum 40 in the base section FB. For this purpose, the cable drum 40 is provided with a disc-shaped central section 40c arranged axially on one side between a radially inner shaft section 40a, which serves for the rotatable mounting of the cable drum 40 in the flat housing F by means of the bearings 70, 71, and a radially outer circumferential section 40b, on which the measuring cable M can be wound. This disc-shaped central section forms an annular receiving space 72 in which the return mechanism 41 is arranged radially and axially.The return mechanism 41 is supported at one end on the cable drum 40 in the area of ​​the shaft section 40a and at a second end on a corresponding stop 73 on the base FB of the flat housing F. Furthermore, shaft shoulders are formed on the radially inner shaft section 40a of the cable drum to ensure that the cable drum 40 is fixed in the axial direction.

[0081] To flange the sensor housing G to the flat housing F, a centering flange Z is formed between the cover part FD of the flat housing F and the sensor housing G of the sensor device. The centering flange Z is – as in connection with the Fig. 9 and Fig. As can be seen in Figure 12, the centering neck 80 of the cover part FD of the flat housing F is formed by an annular centering neck 80 of the cover part FD of the flat housing F, which is arranged concentrically to the shaft section 40a of the cable drum 40, and a concentrically arranged annular centering extension 81 on the sensor housing G of the sensor device, wherein the sensor housing G with the centering extension 81 can be inserted into the centering neck 80 of the flat housing F. To facilitate the alignment of the sensor housing G during assembly, a recess 82 for a guide pin 83 formed on the centering extension 81 is provided on the circumference of the centering neck 80. The centering neck 80 of the cover part FD is arranged in an annular, inwardly directed inner recess 85 of the cover part FD, so that the centering flange Z can be arranged within the axial extent A of the flat housing F.

[0082] For the rotationally fixed coupling of the sensor device in the sensor housing G with the cable drum 40 rotatably arranged in the flat housing F, a shaft coupling device W is formed between the shaft section 40a of the cable drum 40 and a sensor input shaft 90 rotatably arranged in the sensor housing G. To save axial installation space, the shaft coupling device W overlaps the centering flange Z in the axial direction and is thus arranged together with the centering flange Z within the axial extent A of the flat housing F.

[0083] The shaft coupling device W is designed as a plug-in coupling with two interlocking toothed sections 91, 92. The first toothed section 91 is integrally formed on the shaft section 40a of the cable drum 40 and is designed as an external toothing. The second toothed section 92 is designed as an internal toothing and is arranged in an axial bore 93 of the sensor input shaft 90.

[0084] To seal the sensor housing G, a shaft sealing device 95, formed by a shaft seal ring, is arranged between the sensor input shaft 90 and the sensor housing G. The shaft sealing device 95 is located in the region of the annular centering extension 81 of the sensor housing G. Due to the internal toothing on the sensor input shaft 90, the shaft sealing device 95 can be arranged to overlap the shaft coupling device W in the axial direction, so that the shaft sealing device 95 does not create any additional space in the axial direction of the cable length sensor S.

[0085] The sensor housing G has a two-part structure consisting of a base part GB and a cover part GD, which can be connected to each other, for example by appropriate screw connections 96, which are shown in the Fig. 12 are shown in more detail. Between the base part GB and the cover part GD, a sealing device 100 formed by an O-ring is arranged, which forms a sealed electronics installation space E inside the sensor housing G in which the sensor device is arranged.

[0086] For the rotatable mounting of the sensor input shaft 90, the base part GB and the cover part GD of the sensor housing G are each designed as bearing shields in which the sensor input shaft 90 is rotatably mounted by means of corresponding bearings 105, 106.

[0087] The annular centering extension 81 is formed on the base part GB of the sensor housing G. The can-shaped cover part GD of the sensor housing G is provided with a circumferential skirt 107 around its outer edge, which, when the sensor housing G is flanged, engages in a receiving groove 108 on the cover part FD of the flat housing F. The skirt 107 prevents a water jet from being directed onto the sealing device 100 during external cleaning of the cable length sensor S. The skirt 107, together with the receiving groove 108, forms a labyrinth seal through which water located in the space between the cover part FD of the flat housing F and the base part GB of the sensor housing G can drain away.

[0088] The sensor housing G is preferably attached to the flat housing F via suitable connections, for example screw connections 110, and support pins 111 arranged on the cover part FD of the flat housing F.

[0089] The sensor device arranged in the sealed electronics installation space E is designed as an absolute sensor device.

[0090] The absolute sensor device comprises a sensor arranged on a circuit board P located in the electronics installation space E, which is connected to the sensor input shaft 90 via an intermediate reduction gear U located in the electronics installation space E.

[0091] The reduction gear U is designed as a multi-stage spur gear transmission comprising an input gear 115 meshing with the sensor input shaft 90, an intermediate gear 116 meshing with the input gear 115, and a sensor gear 117 meshing with the intermediate gear 116, the rotation angle of which can be measured with a corresponding sensor. The gears 115, 116, and 117 are arranged in a recess 118 of the base GB of the sensor housing G and are rotatably mounted on the base GB of the sensor housing G. Fig. Figure 13 shows a view of the sensor housing G onto the electronics installation space E with the reduction gear U, with the base part GB not shown.

[0092] The absolute sensor device has a fully redundant design with two separate sensor strings downstream of the sensor input shaft 90. For this purpose, two sensors are arranged in the electronics installation space E, each of which is assigned a corresponding reduction gear U1, U2.

[0093] The sensors are preferably designed as Hall sensors, for example Hall differential sensors, each comprising a sensor chip C1, C2 arranged on the circuit board P with associated electrical voltage supply and each comprising an electronic control unit M for outputting a corresponding measurement signal.

[0094] The use of non-contact Hall sensors as sensors in conjunction with the reduction gears U1, U2 also results in a flat design of the sensor housing G in the axial direction of the rope length encoder S.

[0095] A connector 120 is also provided on the cover part GD of the sensor housing S, by means of which the cable length sensor S can be connected to an electronic vehicle control system of the counterbalance forklift 1. The measurement signal of the lifting height of the load-handling attachment supplied by the cable length sensor S can be displayed on a display device and / or used to influence vehicle characteristics in order to meet safety requirements.

[0096] The protective cover 30 of the Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6 to Fig. 7 is designed such that the vertically upper area of ​​the rope length transmitter S with the flat housing F, the flanged sensor housing G and the plug connection 120 are arranged under the protective housing 30.

[0097] In the rope length encoder S according to the invention, the flat housing F, the sensor housing G, the rope drum 40, the deflection pulley 43 and the gears of the reduction gears U can be manufactured as plastic components.

[0098] The rope length encoder S according to the invention has a number of advantages which are conducive to a flat design and a robust and reliably operating design of the rope length encoder S in order to adapt the rope length encoder S for the operating conditions of a counterbalance forklift truck 1.

[0099] The axially flat and vertically elongated design of the rope length encoder S according to the invention, with the flat housing F and the similarly flat, flange-mountable sensor housing G, enables a visually optimized mounting on the lifting frame 10 in the upper area of ​​the support mast 10a ( Fig. 2, Fig. 3 to Fig. 4) or at the lower part of the support mast 10a in the space between the support mast 10a and the drive wheel 7 ( Fig. 5, Fig. 6 to Fig. 7).

[0100] The modular design of the rope length encoder S, consisting of the flat housing F and the flange-mountable sensor housing G, enables cost-effective replacement of the corresponding module in case of damage.

[0101] The integration of the deflection pulley 43 into the flat housing F enables high tolerance accuracy in the cable guidance, ensuring a single-layer winding of the measuring cable M on the cable drum 40, where tolerances of the lifting frame 10 have no influence on the cable guidance. Furthermore, the deflection pulley 43 is protected from external contamination and damage within the flat housing F.

[0102] The nozzle guard 50 on the flat housing F easily prevents the wiper nozzle 47 from being torn off if the measuring rope M is frozen or jammed. In conjunction with the bellows 46, a large rope exit angle can be achieved, allowing the measuring rope M, which can be pulled out of the rope length sensor S, to adapt to changes in the angle of travel resulting from mast deflection, mast wear or mast tolerances.

[0103] The installation of the rope cleaning brush 60 in the flat housing F, in conjunction with the drain opening 65, enables the safe cleaning of the measuring rope M from adhering protective coatings and water or ice, as well as the drainage of the cleaned water and dirt from the flat housing F. This effectively prevents the measuring rope M from freezing to the rope drum 40.

[0104] The inventive design of the centering flange Z and the shaft coupling device W, designed as a plug-in coupling, results in an axially compact and low-profile design of the rope length sensor S and enables simple flange mounting of the two modules. The design of the toothed section 91 on a shaft extension or the shaft section 40a of the rope drum 40 enables cost-effective manufacturing of the toothed section 91 with high tolerance accuracy.

[0105] The sealed electronics installation space E in the sensor housing G results in a long service life for the sensor device.

[0106] The use of an absolute sensor device results in increased operational reliability of the lifting height measurement, as reference runs or sensor calibrations after commissioning of the counterbalance forklift truck can be omitted.

[0107] The use of non-contact Hall sensors results in a wear-free measuring sensor system. Combined with the redundant design featuring two separate sensor strings, this further increases the operational reliability of the S-type cable length encoder.

Claims

[1] Counterbalance forklift truck (1) with a lifting mast (10) and a load handling device (11) arranged on the lifting mast (10) that can be raised and lowered, wherein a lifting height measuring system is provided for detecting the lifting height of the load handling device (11), wherein the lifting height measuring system is designed as a cable length sensor (S) comprising a measuring cable (M) that can be unwound on a cable drum (40) against the force of a reset device (41) and a sensor device for detecting the rotational movement of the cable drum (40), wherein the cable length sensor (S) is arranged on the lifting mast (10) such that the measuring cable (M) leading out of the measuring cable outlet (42) is arranged within the longitudinal extent (L) of the lifting mast (10) over the entire measuring range, characterized by, that the lifting frame (10) is arranged at least partially within two front drive wheels (7) of the counterbalance forklift (1), wherein the rope length sensor (S) has a closed flat housing (F) in which the rope drum (40) is arranged and which is provided with a measuring rope outlet (42) arranged vertically spaced from the rope drum (40), wherein a bellows (46) with a wiper nozzle (47) is arranged at the measuring rope outlet (42) of the flat housing (F) through which the measuring rope (M) is guided, and wherein a nozzle guard (50) is arranged on the flat housing (F) which, when the measuring rope (M) is pulled out of the flat housing (F), forms a stop for the bellows (46) provided with the wiper nozzle (47). [2] Counterbalance forklift truck according to claim 1, characterized by , that a sensor housing (G) of the sensor device can be flanged to the flat housing (F). [3] Counterbalance forklift truck according to claim 1 or 2, characterized by , that the lifting frame (10) is designed as a multi-lifting frame with a fixed mast (10a) and at least one extension mast (10b), wherein at least one lifting cylinder assembly (15) is provided for lifting the extension mast and the load handling device (11) can be lifted by means of a traction element (17) through the lifting cylinder assembly (15), wherein the rope length sensor (S) is arranged in the upper area of ​​the fixed mast (10a) and the measuring rope (M) is connected to the extension mast (10b). [4] Counterbalance forklift truck according to claim 1 or 2, characterized by, that the lifting frame (10) is designed as a multi-lifting frame with a fixed mast (10a) and at least one extension mast (10b), wherein at least one lifting cylinder device (15) is provided for lifting the extension mast and the load handling device (11) can be lifted by means of a free lifting cylinder device (20), wherein the rope length sensor (S) is arranged at least partially in the space between the fixed mast (10a) and the drive wheel (7) in the lower area of ​​the fixed mast (10a), and the measuring rope (M) is connected to the load handling device (11). [5] Counterbalance forklift truck according to any one of claims 1 to 4, characterized by , that the rope length sensor (S) is arranged under a protective housing (30) on the support mast (10a). [6] Counterbalance forklift truck according to claim 4 or 5, characterized by , that a protective rail (31) is arranged on the support mast (10a) as rope protection for the measuring rope (M). [7] Counterbalance forklift truck according to claim 6, characterized by, that the guard rail (31) is provided with viewing openings (32) for improved visibility of the load-bearing device (11). [8] Counterbalance forklift truck according to any one of claims 1 to 7, characterized by , that a deflection pulley (43) is arranged in the flat housing (F), over which the measuring rope (M) is guided, wherein the deflection pulley (43) is arranged in the measuring rope direction between the rope drum (40) and the measuring rope exit (42) and is rotatably mounted in the flat housing (F). [9] Counterbalance forklift truck according to claim 8, characterized by , that the deflection pulley (43) is arranged vertically downwards from the rope drum (40), in particular at least partially below the measuring rope exit, and the flat housing (F) between the rope drum (40) and the deflection pulley (43) is designed as a rope guide channel (45). [10] Counterbalance forklift truck according to any one of claims 1 to 9, characterized by, that the rope drum (40) is arranged axially immovably in the flat housing (F). [11] Counterbalance forklift truck according to any one of claims 1 to 10, characterized by , that the nozzle guard (50) has a fork shape with a fork opening (52) formed by a fork (51), wherein the measuring rope (M) is guided through the fork opening (52) and the fork (51) forms a stop cooperating with the wiper nozzle (47). [12] Counterbalance forklift truck according to any one of claims 1 to 11, characterized by , that a rope cleaning brush (60) is arranged in the flat housing (F). [13] Counterbalance forklift truck according to claim 12, characterized by , that the rope cleaning brush (60) is formed by a spirally wound brush with inwardly directed bristles, wherein the measuring rope (M) passes centrally through the rope cleaning brush (60). [14] Counterbalance forklift truck according to claim 12 or 13, characterized by, that the rope cleaning brush (60) is arranged between the rope drum (40) and the deflection pulley (43) in the rope guide channel (45) of the flat housing (F). [15] Counterbalance forklift truck according to any one of claims 1 to 14, characterized by , that the flat housing (F) is provided in a lower area with a drain opening (65) for dirt and water drainage. [16] Counterbalance forklift truck according to any one of claims 12 to 15, characterized by , that the flat housing (F) has a two-part structure consisting of a shell-shaped base part (FB) and a shell-shaped cover part (FD), wherein the rope drum (40) with the resetting device (41), the rope cleaning brush (60) and the measuring rope outlet (42) are arranged in the base part (FB) and the deflection pulley (43) is cantilevered in the base part (FB). [17] Counterbalance forklift truck according to claim 16, characterized by , that the bottom part (FB) is equipped with the nozzle guard (50). [18] Counterbalance forklift truck according to any one of claims 1 to 17, characterized by , that the return device (41) is designed as a drive spring, in particular a spiral spring, which is arranged within the axial installation space of the rope drum (40). [19] Counterbalance forklift truck according to any one of claims 2 to 18, characterized by , that a centering flange (Z) for flange mounting the sensor device is formed between the flat housing (F), in particular the cover part (FD), and the sensor housing (G) of the sensor device. [20] Counterbalance forklift truck according to claim 19, characterized by , that the centering flange (Z) is formed by an annular centering neck (80) of the cover part (FD), into which the sensor housing (G) of the sensor device can be inserted with an annular centering extension (81). [21] Counterbalance forklift truck according to claim 19 or 20, characterized by, that the centering flange (Z) is arranged in an inwardly facing recess (85) of the cover part (FD) of the flat housing (F). [22] Counterbalance forklift truck according to any one of claims 19 to 21, characterized by , that the sensor device comprises a sensor input shaft (90) rotatable in the sensor housing (G), which can be coupled to the rope drum (40) in a rotationally fixed manner by means of a shaft coupling device (W), wherein the shaft coupling device (W) and the centering flange (Z) are arranged overlapping in the axial direction. [23] Counterbalance forklift truck according to claim 22, characterized by , that the shaft coupling device (W) is formed by two intersecting toothed sections (91, 92), wherein a first toothed section (91) is formed in one piece on the rope drum (40) and a second toothed section (92) is formed on the sensor input shaft (90). [24] Counterbalance forklift truck according to claim 23, characterized by, that the first toothing section (91) is formed as external teeth on an axial shaft extension (40a) of the rope drum (40) and the second toothing section (92) is formed as internal teeth in an axial bore (93) of the sensor input shaft (90). [25] Counterbalance forklift truck according to any one of claims 22 to 24, characterized by , that the sensor housing (G) is designed as a sealed sensor housing, wherein a shaft sealing device (95), in particular a shaft seal ring, is associated with the sensor input shaft (90). [26] Counterbalance forklift truck according to claim 25, characterized by , that the shaft sealing device (95) is arranged in the area of ​​the centering extension (81) of the sensor housing (G). [27] Counterbalance forklift truck according to any one of claims 2 to 26, characterized by, that the sensor housing (G) has a two-part structure consisting of a base part (GB) and a cover part (GD), wherein the base part (GB) is sealed against the cover part (GD) by means of a sealing device (100), in particular an O-ring, and forms a sealed electronic installation space (E). [28] Counterbalance forklift truck according to claim 27, characterized by , that the ring-shaped central process (81) is formed on the base part (GB). [29] Counterbalance forklift truck according to any one of claims 1 to 28, characterized by that the sensor device is designed as an absolute sensor device. [30] Counterbalance forklift truck according to any one of claims 22 to 29, characterized by , that the absolute sensor device comprises a sensor which is connected to the sensor input shaft (90) by means of a reduction gear (U) arranged in the sensor housing (G), in particular in the electronics installation space (E). [31] Counterbalance forklift truck according to claim 30, characterized by , that the absolute sensor device comprises a redundant structure with two sensors, each of which is connected to the sensor input shaft (90) via an intermediate reduction gear (U) arranged in the sensor housing (G), in particular in the electronics installation space (E). [32] Counterbalance forklift truck according to claim 30 or 31, characterized by that the sensor is designed as a Hall sensor. [33] Counterbalance forklift truck according to any one of claims 1 to 32, characterized by , that the measuring cable (M) is designed as a steel cable with a plastic coating.

Images