DE102011009368B4 - Rope length sensor - Google Patents

Abstract

Cable length sensor (S) with 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) has a two-module structure consisting of a closed flat housing (F), in which the cable drum (40) and the reset device (41) are arranged and which is provided with a measuring cable outlet (42), and a sensor housing (G) of the sensor device, wherein the sensor housing (G) can be flanged to the flat housing (F) and is designed as a sealed sensor housing (G) that has a sealed electronics installation space (E) in which the sensor device is arranged, characterized in that the measuring cable outlet (42) is formed on the flat housing (F) at a distance from the cable drum (40) downwards in the vertical direction and pointing upwards, wherein a deflection roller (43) is arranged in the flat housing (F), via which the measuring cable (M) is guided, wherein the deflection roller (43) is arranged in the measuring cable direction between the cable drum (40) and the measuring cable outlet (42) and is rotatably mounted in the flat housing (F), wherein the deflection roller (43) is arranged vertically downwards from the cable drum (40) in the flat housing (F), in particular is arranged at least partially below the measuring cable outlet, and the flat housing (F) is designed as a cable guide channel (45) between the cable drum (40) and the deflection roller (43).

Description

The invention relates to a cable length sensor with a measuring cable that can be unwound on a cable drum against the force of a reset device and a sensor device for detecting the rotational movement of the cable drum, wherein the cable length sensor has a two-module structure consisting of a closed flat housing in which the cable drum and the reset device are arranged and which is provided with a measuring cable outlet, and a sensor housing of the sensor device, wherein the sensor housing can be flanged to the flat housing and is designed as a sealed sensor housing that has a sealed electronics installation space in which the sensor device is arranged.

Such rope length sensors are used as rope pull position sensors in work machines, for example industrial trucks, construction machinery, cranes or agricultural equipment.

From the EP 1 203 743 B1 A warehouse technology forklift truck, for example a reach truck, high-bay forklift truck or high-bay order picker, is known in which a cable length sensor is used as a lifting height measuring system for detecting the lifting height of a load-handling device that can be raised and lowered.

From the DE 195 20 388 C2 A generic cable length sensor with the features of the preamble of patent claim 1 is known.

Due to the rotating cable drum and the high number of actuation cycles of the reset device, generic cable length sensors are subject to high levels of mechanical wear, which is further increased by the operating conditions. If the cable length sensor is operated outdoors, it is also exposed to the effects of the weather, such as moisture or ice. If the measuring cable is frozen solid, the formation of ice can cause the cable to break. If the cable length sensor is used in work machines, such as industrial trucks, that are used in production facilities under dusty, dirty and possibly damp conditions where there is a high level of contamination, such as in a foundry, the cement industry, the fertilizer industry or in port facilities, the increased contamination also increases wear on the measuring cable and the cable drum. Due to the high susceptibility to wear, a wear-resistant design of the cable length sensor is therefore desired in order to keep wear from the operating conditions as low as possible. In addition, a maintenance-friendly design is required that allows the replacement and exchange of worn components with little maintenance effort in the event of servicing.

For corresponding applications of a rope length sensor of this type, a flat design with compact dimensions in the axial direction of the rope drum is also required. In particular, when using a rope length sensor as a lifting height measuring system in industrial trucks, the obstruction to the view of the load-carrying device can be kept to a minimum by using a flat design of the rope length sensor.

The EN 10 2005 037 862 B3 discloses a measuring cable position sensor.

The DE 103 61 699 B3 reveals a measuring cable displacement sensor with a spring in the cable drum.

From the DE 298 03 061 U1 and the DE 297 07 253 U1 Rope length sensors are known.

The EN 10 2005 037 626 A1 reveals a rope scraper.

The DE 20 2004 014 184 U1 discloses a device for cleaning a measuring cable in a cable length sensor.

From the DE 299 21 114 U1 A stripping device for a cable length sensor is known.

The present invention is based on the object of providing a cable length sensor of the type mentioned at the outset, which enables a flat construction and a wear-resistant construction and requires little maintenance effort in the event of maintenance.

This object is achieved according to the invention in that the measuring cable outlet is formed on the flat housing at a vertical distance downwards from the cable drum and pointing upwards, wherein a deflection roller is arranged in the flat housing, over which the measuring cable is guided, wherein the deflection roller is arranged in the measuring cable direction between the cable drum and the measuring cable outlet and is rotatably mounted in the flat housing, wherein the deflection roller is arranged in the flat housing at a vertical distance downwards from the cable drum, in particular is arranged at least partially below the measuring cable outlet, and the flat housing is designed as a cable guide channel between the cable drum and the deflection roller.

The cable length sensor according to the invention thus has a two-part modular design consisting of a preferably elongated in the vertical direction and flat in the axial direction of the cable drum The flat housing and a flange-mounted sensor housing with the sensor device. The flat housing contains the mechanical components, which are formed by the cable drum with the measuring cable that can be unwound or wound onto it and the measuring cable outlet. The installation of the cable drum and the reset device in the closed flat housing results in a protected arrangement of the cable drum and, by integrating the reset device, enables the cable length sensor to be constructed flat in the axial direction. It also makes it possible to provide appropriate cleaning devices on or in the flat housing in order to minimize malfunctions and wear in the mechanical components caused by moisture, ice or dirt. The sensor housing with the sensor device that can be flanged onto the flat housing contains the electronic components. The design of the sensor housing as a sealed sensor housing with a sealed electronics installation space for the sensor device also enables the sensor device to be protected from moisture and dirt and tightly sealed in an electronics installation space that is sealed from the environment. This way, a long service life for the electronics can be achieved. This modular design consisting of the flat housing with the mechanical components and the sensor housing with the sensor device enables the corresponding module to be easily replaced in the event of wear-related faults, defects or damage to the corresponding components resulting from the operating conditions of the cable length sensor, which results in low maintenance costs and low operating costs for the cable length sensor. The encapsulation of the sensor device in the electronics installation space of the sealed sensor housing makes it easier to replace the sensor housing with the sensor device or the flat housing with the mechanical components, since no dirt or moisture can enter the electronics installation space with the sensor device when installing a new sensor housing or a new flat housing.

According to the invention, the measuring cable outlet is spaced vertically downwards from the cable drum and is formed on the flat housing so as to point upwards, with a deflection roller being arranged in the flat housing, over which the measuring cable is guided, and the deflection roller being arranged in the measuring cable direction between the cable drum and the measuring cable outlet and being rotatably mounted in the flat housing. With such a deflection roller, which is arranged at least partially below the measuring cable outlet in the vertical direction, the cable length sensor according to the invention deflects the measuring cable unwound downwards from the cable drum upwards to the measuring cable outlet, whereby the measuring cable outlet can be spaced apart from the cable drum in a simple manner. The integration and mounting of the deflection roller in the flat housing results in an arrangement of the deflection roller that is protected from external damage and contamination, which leads to a high level of robustness of the cable length sensor according to the invention. By integrating the deflection pulley into the flat housing, a high tolerance can also be achieved between the cable pulley, the measuring cable outlet and the fastening of the measuring cable to the load-carrying device or the extension mast. When using a cable length sensor according to the invention as a lifting height sensor in an industrial truck, tolerances in the lifting frame have no negative influence on the position of the deflection pulley and on the cable guidance of the measuring cable over the deflection pulley. With the integration and storage of the deflection pulley in the flat housing according to the invention, wear is reduced and the service life of the measuring cable and the deflection pulley is increased.

According to the invention, the deflection roller is arranged vertically downwards from the cable drum in the flat housing, in particular arranged at least partially below the measuring cable outlet, and the flat housing between the cable drum and the deflection roller is designed as a cable guide channel. With such an arrangement of the deflection roller, it can be achieved in a simple manner that the measuring cable outlet is positioned vertically below the cable drum in the cable length sensor according to the invention. The design of the flat housing between the deflection roller and the cable drum as a cable guide channel also enables corresponding additional components, for example a cleaning device for the measuring cable, to be arranged in the area of the cable guide channel in a space-saving and protected manner within the flat housing.

According to a preferred embodiment of the invention, the sensor housing has a two-part structure comprising a base part and a cover part, wherein the base part is sealed from the cover part by means of a sealing device, in particular an O-ring, and the sealed electronics installation space is formed between the base part and the cover part. By forming the sensor housing from a base part and a cover part, a sealed electronics installation space for the sensor device can be formed in a simple manner.

The sensor housing with the sensor device can be arranged on the flat housing in a simple manner and fastened in a suitable manner if, according to an expedient development of the invention, a centering flange for flanging the sensor housing is formed between the flat housing and the sensor housing of the sensor device.

Particular advantages arise when the centering flange according to a preferred embodiment of the invention is formed by an annular centering neck of the flat housing arranged within the axial extension of the flat housing, into which the sensor housing of the sensor device can be inserted with an annular centering extension. Such a centering flange can be produced in a simple manner by means of the centering neck and the centering extension and enables the sensor housing to be easily mounted on the flat housing by means of a flange connection. By arranging the centering flange within the axial extension of the flat housing, a flat structure in the axial direction of the cable length sensor is achieved, in which the centering flange does not require any additional installation space in the axial direction.

If, according to an advantageous embodiment of the invention, the centering flange is arranged in a bulge of the flat housing facing inwards in the axial direction, advantages arise with regard to a small axial extension and flat construction of the flat housing, since the centering flange can be arranged within the axial extension of the flat housing.

In the cable length sensor according to the invention, the sensor device is to be coupled to the cable drum in a rotationally fixed manner in order to be able to precisely detect the rotational movement of the cable drum with the measuring cable. According to a preferred development, the sensor device comprises a sensor input shaft which is rotatably mounted in the sensor housing and which can be coupled to the cable 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 in the axial direction. The axial superposition of the centering flange and the shaft coupling device in the same cutting plane allows the axial installation space requirement of a cable length sensor according to the invention to be further reduced, since the shaft coupling device and the centering flange use the same installation space in the axial direction and are preferably arranged within the axial extension of the flat housing.

Particular advantages arise here if the shaft coupling device is formed by two interlocking toothed sections, one toothed section being integrally formed on the cable drum and a second toothed section being formed on the sensor input shaft. Due to the axial overlap of the shaft coupling device with the centering flange, a plug-in coupling of two interlocking toothed sections can be used to form a simply constructed shaft coupling device, which makes it easier to join the sensor housing to the flat housing. When joining, the two toothed sections engage with each other and create a positive connection between the cable drum and the sensor input shaft. Since the axial overlap of the shaft coupling device with the centering flange means that the two toothed sections cannot be seen when joining the sensor housing, the toothing is designed in such a way that the toothed sections can be connected to the corresponding shaft ends without being visible. The one-piece design of the toothed section on the cable drum also leads to a reduction in the axial dimensions of the cable length sensor according to the invention. In addition, the one-piece design of the toothed section on the cable drum enables production at low manufacturing costs with a high level of tolerance accuracy. The cable drum with the molded toothed section is preferably designed as a plastic component.

Preferably, the first toothing section is designed as an external toothing on an axial shaft extension of the cable drum and the second toothing section is designed as an internal toothing in an axial bore of the sensor input shaft. An external toothing can be produced in a simple manner on a shaft extension of the cable drum. The same applies to an internal toothing arranged in an axial bore of the sensor input shaft.

According to an advantageous development of the invention, a shaft sealing device is 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 sealing 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 shaft sealing device can be used to easily seal the electronics installation space in the area of the shaft inlet of the sensor input shaft.

Preferably, the shaft sealing device is arranged in the region of the centering extension of the sensor housing. A shaft sealing ring can be easily installed on the inner circumference of the annular centering extension of the sensor housing.

Preferably, the annular centering extension is formed on the bottom part of the sensor housing.

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-carrying device can be measured without reference runs or sensor calibration after the counterbalance forklift truck has been put into operation. The elimination of tolerance-related reference runs or sensor calibrations leads to increased operational reliability of the cable length sensor according to the invention.

The absolute sensor device preferably comprises a sensor which is connected to the sensor input shaft via a reduction gear arranged in the electronics installation space of the sensor housing. The use of a corresponding reduction gear makes it easy to convert several revolutions of the cable drum into a single revolution on a measuring shaft of the sensor in order to ensure a sensor that measures the lifting height absolutely. The arrangement of the reduction gear in the sealed electronics installation space results in an arrangement of the reduction gear that is protected from environmental influences and moisture, so that the reduction gear can be designed for a long service life with little construction effort.

If, according to an advantageous 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 the interposition of a reduction gear arranged in the electronics installation space of the sensor housing, a high level of operational reliability of the cable length sensor can also be achieved, which satisfies the highest safety requirements.

Preferably, the sensor device has a completely redundant structure with two separate sensor strands after the sensor input shaft, each of which has a reduction gear, a sensor, electronics and a measurement signal output as well as an electrical power supply. When using a cable length sensor according to the invention as a lifting height measuring system of an industrial truck, the determined lifting height of the load-carrying device can be displayed to the operator on a display device of the industrial truck. Additionally or alternatively, the determined lifting height of the load-carrying device can be further processed in the industrial truck, for example in order to meet safety requirements. The redundant structure of the sensor device with two separate sensor strands leads to a high level of operational reliability.

According to a preferred embodiment of the invention, the sensor is designed as a Hall sensor. Hall sensors enable contactless and thus wear-free measurement, so that the robustness and reliability of the cable length sensor according to the invention can be further increased. If the Hall sensor is designed as a differentially measuring Hall sensor, it is also achieved that the sensor signals are stable when exposed to external magnetic fields and external magnetic fields do not influence the measurement results of the cable length sensor.

With regard to a flat or narrow structure in the axial direction of the flat housing, there are advantages if the cable drum is arranged axially immovably in the flat housing. With a cable length sensor according to the invention, it must be ensured that the measuring cable is wound up or unwound on the cable drum in a single-layer winding in order to be able to determine a clear and exact length signal by measuring the rotational movement of the cable drum. By arranging the deflection pulley vertically spaced from the cable drum, a corresponding distance can be achieved between the deflection pulley and the axially fixed cable drum in the cable length sensor according to the invention, which ensures that the measuring cable between the deflection pulley and the cable drum only experiences a small angular deflection when winding up or unwinding and that with an axially fixed cable drum, the single-layer winding of the cable drum is possible safely and without disruption.

With regard to a flat design of the cable length sensor according to the invention, further advantages arise if, according to a further development of the invention, the reset device is designed as a drive spring, in particular a spiral spring, which is arranged within the axial installation space of the cable drum in the flat housing. The reset device therefore does not require any additional installation space in the axial direction of the flat housing and thus of the cable length sensor.

According to a preferred development of the invention, a bellows with a scraper nozzle is arranged at the measuring cable outlet of the flat housing, through which the measuring cable is guided. With a A scraper nozzle through which the measuring cable passes when entering and exiting the flat housing can easily remove coarse dirt and water drops or ice adhering to the measuring cable and provide a rough pre-cleaning of the measuring cable. A scraper nozzle of this type can thus 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 or mounting of the scraper nozzle on a bellows enables easy guidance and thus mobility of the scraper nozzle. In conjunction with the bellows, the scraper nozzle can adapt to the course of the measuring cable and enables a large cable exit angle from the flat housing. When the cable length sensor according to the invention is used as a lifting height measuring system for an industrial truck, tolerances and wear of the lifting mast as well as deflections of the lifting mast, which occur particularly under load at high lifting heights, influence the angle of the measuring cable. The arrangement of the scraper nozzle in the bellows makes it easy for the scraper nozzle to adapt to the course of the measuring cable and for the measuring cable to move freely. The bellows reduce the friction between the scraper nozzle and the measuring cable, so that a further reduction in wear and an increase in the service life of the measuring cable can be achieved.

Particular advantages can be achieved if a nozzle guard is arranged on the flat housing, which forms a stop for the bellows provided with the wiper nozzle when the measuring cable is pulled out of the flat housing. When using a cable length sensor according to the invention in dusty, dirty or damp ambient conditions or outdoors under the influence of the weather, the measuring cable can get stuck in the wiper nozzle due to coarse dirt or freezing water. With the stop for the wiper nozzle, it is easy to prevent the wiper nozzle from being torn off the cable length sensor when the measuring cable is pulled out of the cable length sensor. If a measuring cable gets stuck in the wiper nozzle, the wiper nozzle arranged in the bellows comes into contact with the stop when the measuring cable is pulled out of the cable length sensor, which prevents further movement of the wiper nozzle. This means that when the measuring cable is pulled out further from the cable length sensor, the wiper nozzle remains stationary and the measuring cable can run freely, pulling coarse dirt out of the wiper nozzle and breaking frozen water. The stop can therefore provide effective protection against the measuring cable freezing in the wiper nozzle, for example in the case of a counterbalance forklift truck that has been parked overnight, or against the measuring cable jamming in the wiper nozzle due to jammed dirt particles. The stop reliably prevents the wiper nozzle from being torn off the flat housing when the measuring cable is pulled out if the measuring cable gets stuck in the wiper nozzle. The robustness and reliability of the cable length sensor according to the invention can be further increased with such a stop for the scraper nozzle.

According to a preferred embodiment of the invention, the nozzle guard has a fork shape with a fork opening formed by a fork, wherein the measuring cable is guided through the fork opening and the fork forms a stop that interacts with the wiper nozzle. With a fork with two prongs, for example, a stop can be formed in a simple manner for the wiper nozzle arranged in the bellows, wherein the measuring cable can run freely through the fork opening.

The robustness, reliability and wear resistance of the cable length sensor according to the invention can be further increased if a cleaning device for the measuring cable in the form of a cable cleaning brush is arranged in the flat housing. The measuring cable thus passes through the cable cleaning brush before being wound onto the cable drum. The cable cleaning brush can be used to safely remove dirt and water adhering to the measuring cable, so that the service life of the measuring cable can be further increased and wear on the measuring cable can be reduced. In addition, the cable cleaning brush reliably prevents the measuring cable wound onto the cable drum from freezing, which further increases the robustness and reliability of the cable length sensor according to the invention.

The rope cleaning brush can be formed by several longitudinal brushes directed at the measuring rope running through it, which enclose 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 inward-facing bristles, with the measuring rope running centrally through the brush. With such a spiral or helically wound brush, which preferably has several turns through which the measuring rope runs before being wound onto the rope drum, the measuring rope running through it can be safely cleaned from all sides, with only low traction losses occur due to low friction.

The rope cleaning brush is preferably 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 is arranged in a space-saving manner in the area of the rope guide channel. The rope cleaning brush can be arranged and fastened in this area of the flat housing in a simple manner, for example by inserting the spirally wound brush between an upper and lower stop arranged on the flat housing and by the flat housing at least partially enclosing or holding it around the circumference.

Particular advantages can be achieved if the flat housing is provided with a drain opening in a lower area to drain dirt and water. With such a drain opening formed on the flat housing, it can be easily ensured that water and dirt that have penetrated into the flat housing of the cable length sensor or that have been brushed off the measuring cable by the cable cleaning brush can flow away in the lower area of the flat housing. The reliability and wear resistance of the cable length sensor according to the invention is thus further increased.

According to a preferred embodiment of the invention, the flat housing has a two-part structure consisting of a bowl-shaped base part and a bowl-shaped cover part, with the cable drum with the reset device, the cable cleaning brush and the measuring cable outlet being arranged in the base part and the deflection roller being mounted in a floating manner in the base part. With such a structure, the assembly of the flat housing with the mechanical components contained therein is simplified. The cable drum with the reset device, the measuring cable, the cable cleaning brush and the bellows with the scraper nozzle arranged at the measuring cable outlet can be mounted in the base part and the flat housing can then be closed by placing and fastening the cover part.

The base part is conveniently provided with the nozzle guard. If the cover part and the base part are made of plastic, the nozzle guard can easily be manufactured as a single piece on the base part.

The invention further relates to an industrial truck, in particular a counterbalance forklift truck, with a cable length sensor as a lifting height measuring system of a load-carrying device. With the cable length sensor according to the invention, which has a wear-resistant structure and is easy to maintain by replacing the corresponding module in the event of a component defect due to the modular structure of the sensor housing and the flat housing, a reliable lifting height measuring system can be formed in an industrial truck that works safely even in dusty, dirty and damp ambient conditions and when used outdoors under the influence of the weather. The flat design with small dimensions in the axial direction of the cable drum enables the cable length sensor according to the invention to be installed on a lifting frame of the industrial truck with minimal impairment of an operator's view of the load-carrying device.

• 1 einen erfindungsgemäßen Seillängengeber in einer perspektivischen Darstellung,
• 2 den Seillängengeber der 1 in einer Seitenansicht,
• 3 eine Schnitt entlang der Linie B-B der 2,
• 4 einen Schnitt entlang der Linie C-C der 2,
• 5 den Seillängengeber im vertikal unteren Bereich in einer vergrößerten Darstellung,
• 6 den Seillängengeber im Bereich der Fügestelle zwischen dem Sensorgehäuse und dem Flachgehäuse in einer aufgelösten Darstellung,
• 7 das Sensorgehäuse mit dem Untersetzungsgetriebe der Sensoreinrichtung,
• 8 ein Flurförderzeug mit einem erfindungsgemäßen Seillängengeber in einer Seitenansicht,
• 9 ein Hubgerüst in einer perspektivischen Darstellung mit einer ersten Anbauvariante des Seillängengebers,
• 10 einen Ausschnitt des Hubgerüstes der 9 in einer Queransicht in Fahrzeuglängsrichtung,
• 11 die 9 in einer die Blickrichtung einer Bedienperson,
• 12 ein Hubgerüst in einer perspektivischen Darstellung mit einer zweiten Anbauvariante des Seillängengebers,
• 13 einen Ausschnitt des Hubgerüstes der 12 in einer Queransicht in Fahrzeuglängsrichtung und
• 14 die 13 mit abgebautem Antriebsrad.

Further advantages and details of the invention are explained in more detail with reference to the embodiments shown in the schematic figures.

• 1 a rope length sensor according to the invention in a perspective view,
• 2 the cable length sensor of the 1 in a side view,
• 3 a section along the line BB of the 2 ,
• 4 a section along the line CC of the 2 ,
• 5 the rope length sensor in the vertical lower area in an enlarged view,
• 6 the cable length sensor in the area of the joint between the sensor housing and the flat housing in a exploded view,
• 7 the sensor housing with the reduction gear of the sensor device,
• 8th an industrial truck with a rope length sensor according to the invention in a side view,
• 9 a lifting frame in a perspective view with a first mounting variant of the cable length sensor,
• 10 a section of the lifting frame of the 9 in a transverse view in the longitudinal direction of the vehicle,
• 11 the 9 in the viewing direction of an operator,
• 12 a lifting frame in a perspective view with a second mounting variant of the cable length sensor,
• 13 a section of the lifting frame of the 12 in a transverse view in the vehicle’s longitudinal direction and
• 14 the 13 with the drive wheel removed.

The cable length sensor S according to the invention has a two-module structure consisting of a closed, vertically elongated and axially narrow flat housing F in which the mechanical components of the cable length sensor S are arranged, and a sealed, also flat sensor housing G with a sensor device that can be flanged to the flat housing F in the upper area. The structure of the cable length sensor is described below using the 1 to 7 described.

In the upper area of the flat housing F, a cable drum 40 is arranged so as to be rotatable and axially fixed, on which a measuring cable M can be unwound against the force of a reset device 41 formed, for example, as a drive spring, in particular a spiral spring. The reset device 41 generates a reset moment 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 from a stainless steel cable with a plastic coating.

An upward-facing measuring cable outlet 42 is arranged on the flat housing F, spaced vertically downwards from the cable drum 40, from which the measuring cable M exits vertically upwards. The flat housing F is designed to be slightly slanted between the upper area with the cable drum 40 located therein and the lower area with the measuring cable outlet 42, so that the measuring cable outlet 42 - in the longitudinal direction of the plane of the drawing of the 2 seen - in front of the upper, in the 2 right area of the flat housing F and the measuring cable M is within the axial extension A of the flat housing F upwards at the upper and front, in the 2 right area of the flat housing F, in which the cable drum 40 is arranged, can be pulled out of the cable length sensor S. The measuring cable M is - as shown in the 2 and 4 can be seen - from the cable drum 40 at the rear, in the 2 left-hand area is unwound downwards and is guided upwards via a deflection roller 43 which is rotatably mounted in the lower area of the flat housing F to the measuring cable outlet 42 which points vertically upwards. The deflection roller 43 is arranged at least partially below the measuring cable outlet 42. The deflection roller 43 has a circumferential groove on the outer circumference in which the measuring cable M is arranged. The deflection roller 43 is arranged in the flat housing F in such a way that the measuring cable M is guided in a straight line downwards to the deflection roller 43 in the plane of the first winding 44 on the cable drum 40. The deflection roller 43 is slightly inclined with the axis of rotation so that the measuring cable outlet 42 is located in the middle area of the flat housing F in the axial direction A.

The area of the flat housing F, which is arranged between the cable drum 40 and the deflection roller 43 and is slightly bevelled towards the front, is designed as a cable guide channel 45 in which a cleaning device R for the measuring cable M, described later, is arranged.

In the area of the measuring cable outlet 42, a bellows 46 is arranged on the flat housing F, which holds a scraper nozzle 47 through which the measuring cable M is guided.

Furthermore, a nozzle guard 50 is arranged on the flat housing F, which forms a stop for the wiper nozzle 47 arranged in the bellows 46 if the measuring cable M gets stuck in the wiper nozzle 47 and is pulled upwards with the measuring cable M in order to prevent the bellows 46 or the wiper nozzle 47 from being torn off the flat housing F.

The nozzle guard 50 is formed by a two-pronged fork 51, the prongs of which delimit a fork opening 52 which is guided upwards by the measuring cable M. The fork opening 52 is dimensioned such that the fork 51 forms a stop on the underside which cooperates with the scraper nozzle 47 which can be moved upwards in the bellows 46.

The cleaning device R arranged in the cable guide channel 45 between the cable drum 40 and the deflection roller 43 is formed by a cable cleaning brush 60 which runs centrally through the measuring cable M. The cable cleaning brush 60 is designed as a spirally wound brush with bristles directed radially inwards towards the measuring cable M. The cable cleaning brush 60 is inserted in the flat housing F between two axial stops 61, 62. On the flat housing F, support strips 63, 64 are also formed on the circumference of the cable cleaning brush 60, which extend in the longitudinal direction of the cable cleaning brush 60 and on which the cable cleaning brush 60 rests in order to achieve the central alignment of the cable cleaning brush 60 to the cable path of the measuring cable M in the guide channel 45.

In order to be able to remove dirt and water from the measuring cable M by means of the cable cleaning brush 60 from the flat housing F, A drain opening 65 is formed in the lower region of the flat housing F as a dirt and water drain. The drain opening 65 is formed by a corresponding opening in a wall region of the flat housing F, wherein the wall region of the flat housing F forms a labyrinth-like drain channel 66 which prevents direct penetration of water when the cable length sensor S is cleaned externally by a water jet directed at the cable length sensor S.

In the embodiment shown, 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 one another, for example by means of corresponding screw connections 68. In the base part FB - as in the 5 can be seen, in which the flat housing F is shown without the cover part FD - the cable drum 40 with the reset device 41, the axial stops 61, 62 and the circumferential support strips 63, 64 for the cable cleaning brush 60 as well as the measuring cable outlet 42 are arranged. In the base part FB there is also a bearing pin 69 on which the deflection roller 43 is mounted in a floating manner. The nozzle guard 50 formed by the fork 51 is also arranged on the base part FB of the flat housing F. In addition, the drain opening 65 with the drain channel 66 is formed in the base part FB.

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

In the 3 is an axial section through the vertical upper section of the cable length sensor S with the cable drum 40 and the sensor housing G flanged to the flat housing F in the area of the cover part FD.

For the rotatable mounting of the cable drum 40, the base part FB and the cover part FD of the flat housing F are each designed as a bearing plate in which the axially fixed cable drum 40 is rotatably mounted by means of corresponding bearings 70, 71. The reset device 41 designed as a drive spring is arranged completely within the axial installation space of the cable drum 40 in the base part FB. For this purpose, the cable drum 40 is provided with a disk-shaped middle part 40c arranged on one side in the axial direction 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 peripheral part 40b, on which the measuring cable M can be wound, so that the cable drum 40 forms an annular receiving space 72 in which the reset device 41 is arranged radially and axially. The return device 41 is supported at a first end on the cable drum 40 in the region of the shaft section 40a and at a second end on a corresponding stop 73 on the base part FB of the flat housing F. Shaft shoulders are also formed on the radially inner shaft section 40a of the cable drum in order to make the cable drum 40 stationary in the axial direction.

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 3 and 6 can be seen - 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. In order to facilitate the alignment of the sensor housing G during joining, a recess 82 for a guide pin 83 formed on the centering extension 81 is formed on the circumference of the centering neck 80. The centering neck 80 of the cover part FD is arranged in an annular, inward-facing inner bulge 85 of the cover part FD, so that the centering flange Z can be arranged within the axial extension A of the flat housing F.

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. In order to save axial installation space, the shaft coupling device W is arranged in an axial direction overlapping the centering flange Z and thus together with the centering flange Z within the axial extension A of the flat housing F.

The shaft coupling device W is designed as a plug-in coupling with two toothed sections 91, 92 that can be pushed into one another. The first toothed section 91 is formed in one piece 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 which is arranged in an axial bore 93 of the sensor input shaft 90.

To seal the sensor housing G, a shaft sealing device 95 formed by a shaft sealing ring is arranged between the sensor input shaft 90 and the sensor housing G. The shaft sealing device 95 is arranged in the area of the annular centering extension 81 of the sensor housing G. Due to the design of the internal toothing on the sensor input shaft 90, the shaft sealing device 95 can be arranged in an axial direction overlapping the shaft coupling device W, so that the shaft sealing device 95 does not cause any additional installation space in the axial direction of the cable length sensor S.

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 means of corresponding screw connections 96, which are provided in the 6 can be seen in more detail. A sealing device 100 formed by an O-ring is arranged between the base part GB and the cover part GD, which forms a sealed electronics installation space E within the sensor housing G, in which the sensor device is arranged.

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 a bearing shield in which the sensor input shaft 90 is rotatably mounted by means of corresponding bearings 105, 106.

The ring-shaped 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 an apron 107 running around the outer edge, which, when the sensor housing G is flanged on, engages in a receiving groove 108 on the cover part FD of the flat housing F. The apron 107 prevents a water jet from being directed directly at the sealing device 100 when cleaning the outside of the cable length sensor S. The apron 107 forms a labyrinth seal with the receiving groove 108, 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 flow away.

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.

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

The absolute sensor device comprises a sensor arranged on a circuit board P arranged in the electronics installation space E, which is connected to the sensor input shaft 90 via the interposition of a reduction gear U arranged in the electronics installation space E.

The reduction gear U is designed as a multi-stage spur gear, which comprises 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 angle of rotation of which can be measured with a corresponding sensor. The gears 115, 116, 117 are arranged in a recess 118 in the base part GB of the sensor housing G and are rotatably mounted on the base part GB of the sensor housing G. In the 7 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 is shown.

The absolute sensor device has a completely redundant structure with two separate sensor strands after 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.

The sensors are preferably designed as Hall sensors, for example Hall difference sensors, each of which comprises a sensor chip C1, C2 arranged on the circuit board P with an associated electrical voltage supply and each comprising an electronic control device M for outputting a corresponding measuring signal.

The use of contactless Hall sensors as sensors in conjunction with the reduction gears U1, U2 also leads to a flat design of the sensor housing G in the axial direction of the cable length sensor S.

Furthermore, a plug connection 120 is arranged 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 control system of a working machine. The cable length sensor S according to the invention is preferably used in an industrial truck as a lifting height measuring system of a load-carrying device. The measuring signal for the lifting height of the load-carrying device supplied by the cable length sensor S can be displayed on a display device. displayed and/or used to influence vehicle characteristics in order to meet safety requirements.

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

With the rope length sensor S according to the invention, a wear-resistant and reliable lifting height measuring system can be used on an industrial truck, which requires little maintenance.

Based on 8 to 14 The installation of a cable length sensor S according to the invention as a lifting height measuring system in an industrial truck 1 designed, for example, as a counterbalance forklift truck is to be described. In the 1 an industrial truck 1 is shown in a side view. The industrial truck 1 comprises a middle section of a vehicle body 5 formed by a frame 2, a counterweight 3 and an overhead guard 4. A driver's workplace 6 is located within the overhead guard 5.

Below the driver's workplace 6 there is an aggregate compartment in which the components of the drive system of the forklift truck 1 are located.

In the 8th Furthermore, in the front area of the industrial truck 1 designed as a counterbalance forklift truck, wheels are shown which are designed as drive wheels 7, and in the rear area a steering axle 9 provided with steered wheels 8.

In the front area of the industrial truck 1, a lifting frame 10 is arranged, on which a load-handling device 11 is arranged so as to be able to be raised and lowered.

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

The lifting frame 10 is designed as a multiple lifting frame, which has one or more masts 10b guided in the stationary mast 10a and extending upwards, in which the load-carrying means 11 is guided in a height-adjustable manner. The load-carrying means 11 is preferably designed as a fork carrier on which a load fork 12 formed by two fork tines is arranged. The lifting frame 10 is arranged between the drive wheels 7 in the transverse direction of the vehicle.

In order to minimize the front dimension, the lifting frame 10, consisting of the stationary mast 10a and the extending masts 10b, is arranged partially within the extension of the two front drive wheels 7 of the counterbalance forklift truck 1, viewed in the longitudinal direction of the vehicle.

In the 9 to 11 a first embodiment of a lifting frame 10 with a cable length sensor S according to the invention as a lifting height measuring system is shown.

For the lifting frame 10 according to the 9 to 11 the stationary mast 10a is designed as an external mast, within which an extending mast 10b designed as an internal mast is arranged. The load-carrying means 11 formed by the fork carrier is arranged in the extending mast 10b so that it can be raised and lowered. The stationary mast 10a and the extending mast 10b are each formed by two lateral vertical mast profiles arranged at a distance in the transverse direction of the vehicle, which form a left and right mast column of the mast 10.

A lifting cylinder device 15 formed by two lifting cylinders is provided for lifting the extending mast 10b. The lifting cylinders are each attached to the corresponding lifting frame profile of the standing mast 10a with a cylinder tube housing and each have an extending and retracting piston rod which is connected to an upper cross brace 16 of the extending mast 10b, which connects the two lifting frame profiles of the extending mast 10b to one another. A traction device 17, for example a lifting chain, is provided for lifting the load-carrying device 11, which is attached at a first end to the standing mast 10a, is guided downwards via a deflection roller 18 arranged in the upper region of the extending mast 10b and is attached at the second end to the load-carrying device 11 in a manner not shown in detail. In such a lifting frame 10, the extension mast 10b is raised when the lifting cylinder is extended and at the same time the load-carrying device 11 is raised via the traction means 17. In the illustrated embodiment, a traction means 17 is arranged in the area of the right and left lifting frame columns on their outside.

The lifting height measuring system formed by the cable length sensor S is attached to the upper part of the mast 10a or to the upper part of a lifting cylinder 15 in the lifting frame 10 shown. The cable length sensor S is preferably arranged on the inside of a lifting frame column so that a protected arrangement of the cable length sensor S between the right and left mast columns. A measuring cable M that can be pulled out vertically upwards from the cable length sensor S can be attached to a corresponding attachment point 19 on the extension mast 10b designed as an inner mast. The attachment point 19 is preferably arranged on the upper cross brace 16 of the extension mast 10b.

As can be seen from the 9 to 11 As can be seen, the cable length sensor S is mounted on the mast 10a in a way that is optimized for visibility in the longitudinal direction of the vehicle behind the mast profiles of the mast 10, so that the operator's view through the two mast columns is minimally obstructed by the cable length sensor S. The measuring cable M leading upwards out of the cable length sensor S is - as with the 10 becomes clear - over the entire lifting range within the longitudinal extension L of the lifting frame 10 in the vehicle's longitudinal direction.

In the 12 to 14 a second embodiment of a lifting frame 10 with a cable length sensor S according to the invention as a lifting height measuring system is shown. With regard to the structure of the standing mast 10a as an outer mast and the at least one extension mast 10b as an inner mast, the lifting frame 10 is connected to the lifting frame 10 of the 9 and 11 identical.

The lifting frame 10 of the 12 to 14 is designed as a so-called free-lift frame, in which the lifting cylinders (not shown in detail) arranged on the standing mast 10a raise the extension mast 10b and, for raising or lowering the load-carrying means 11 arranged in the extension mast 10b so that it can be raised and lowered, a free-lift cylinder 20 is provided in the extension mast 10b, the extendable piston rod of which is connected to the load-carrying means 11 via a traction means 21, for example a lifting chain.

For the lifting frame 10 of the 12 to 14 the cable length sensor S is arranged in the lower area of the mast 10a, the so-called mast base. The measuring cable M, which can be pulled out vertically upwards from the cable length sensor S, is attached to the load-carrying device 11 via a suitable attachment point 25.

As can be seen from the 12 to 14 As can be seen, the cable length sensor S is arranged on the outside of a lifting frame profile of the stationary mast 10a and is arranged 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 makes it possible to achieve a visibility-optimized attachment of the cable length sensor S to the stationary mast 10a, in which the operator's view through the two lifting frame columns is minimally obstructed by the cable length sensor S. The measuring cable M, which can be pulled out upwards from the cable length sensor S, is also arranged over the entire lifting range within the longitudinal extension L of the lifting frame 10 in the longitudinal direction of the vehicle.

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

The protective cover 30 of the 9 to 14 is designed such that the vertically upper region of the cable length sensor S with the flat housing F, the flanged sensor housing G and the plug connection 120 are arranged under the protective housing 30.

For the free lift mast according to the 12 to 14 To protect the measuring cable M connected to the load-carrying device 11, a protective rail 31, preferably designed as a metal rail, is provided, which is attached to the mast 10a and extends over the lower area of the mast 10a that is at risk of collision. The protective rail 31 has, for example, an angular or U-shaped cross-section in order to enable lateral protection of the measuring cable M. In order to impair the view of the load-carrying device 11 as little as possible, the protective rail 31 is designed to be visually optimized and is provided with viewing openings 32 over the height extension, which can, for example, have a slot-like shape.

The rope length sensor S according to the invention has a number of advantages.

The axially flat and vertically elongated design of the cable length sensor S according to the invention with the flat housing F and the also flat, flange-mountable sensor housing G enables a visually optimized installation on the lifting frame 10 in the upper area of the mast 10a ( 9 until 11 ) or at the lower part of the mast 10a in the space between the mast 10a and the drive wheel 7 ( 12 to 14 ).

The modular design of the cable length sensor S consisting of the flat housing F and the flange-mounted sensor housing G as two separately replaceable modules enables cost-effective replacement of the corresponding module in the event of damage.

The integration of the deflection roller 43 in the flat housing F enables a high tolerance Accuracy in the cable guide in order to ensure a single-layer winding of the measuring cable M on the cable drum 40, in which tolerances of the lifting frame 10 have no influence on the cable guide. In addition, the deflection roller 43 is arranged in the flat housing F, protected from external contamination and damage.

The nozzle protection 50 on the flat housing F prevents the scraper nozzle 47 from breaking off in a simple manner if the measuring cable M is frozen or jammed. In conjunction with the bellows 46, a large cable exit angle can be achieved, at which the measuring cable M, which can be pulled out of the cable length sensor S, can adapt to changes in the angle of travel resulting from mast deflection, mast wear or mast tolerances.

The installation of the rope cleaning brush 60 in the flat housing F in conjunction with the drain opening 65 enables the measuring rope M to be safely cleaned of adhering protection and water or ice and the cleaned water and dirt to be drained out of the flat housing F. The measuring rope M can therefore be effectively prevented from freezing onto the rope drum 40.

The inventive design of the centering flange Z and the shaft coupling device W designed as a plug-in coupling leads to an axially compact and flat construction of the cable length sensor S and enables the two modules to be easily flanged. The design of the toothed section 91 on a shaft extension or the shaft section 40a of the cable drum 40 enables the toothed section 91 to be manufactured cost-effectively with a high tolerance accuracy.

The sealed electronics installation space E in the sensor housing G leads to a long service life of the sensor device.

The use of an absolute sensor device results in increased operational reliability of the lifting height measurement, since reference runs or sensor calibrations after commissioning of the industrial truck 1 can be omitted.

The use of contactless Hall sensors results in a wear-free sensor device. In conjunction with the redundant design with two separate sensor strands, the operational reliability of the rope length sensor S is further increased.

Claims (27)

Cable length sensor (S) with 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) has a two-module structure consisting of a closed flat housing (F), in which the cable drum (40) and the reset device (41) are arranged and which is provided with a measuring cable outlet (42), and a sensor housing (G) of the sensor device, wherein the sensor housing (G) can be flanged to the flat housing (F) and is designed as a sealed sensor housing (G) that has a sealed electronics installation space (E) in which the sensor device is arranged, characterized in that the measuring cable outlet (42) is formed on the flat housing (F) at a distance from the cable drum (40) downwards in the vertical direction and points upwards, wherein a deflection roller (43) is arranged in the flat housing (F), via which the measuring cable (M) is guided, wherein the deflection roller (43) is arranged in the measuring cable direction between the cable drum (40) and the measuring cable outlet (42) and is rotatably mounted in the flat housing (F), wherein the deflection roller (43) is arranged vertically downwards from the cable drum (40) in the flat housing (F), in particular is arranged at least partially below the measuring cable outlet, and the flat housing (F) between the cable drum (40) and the deflection roller (43) is designed as a cable guide channel (45). Rope length sensor according to Claim 1 , characterized in that the sensor housing (G) has a two-part structure comprising a base part (GB) and a cover part (GD), wherein the base part (GB) is sealed relative to the cover part (GD) by means of a sealing device (100), in particular an O-ring, and the sealed electronics installation space (E) is formed between the base part (GD) and the cover part (GD). Rope length sensor according to Claim 1 or 2 , characterized in that a centering flange (Z) for flanging the sensor housing (G) is formed between the flat housing (F) and the sensor housing (G) of the sensor device. Rope length sensor according to Claim 3 , characterized in that the centering flange (Z) is formed by an annular centering neck (80) of the flat housing (F) arranged within the axial extension (A) of the flat housing (F), into which the sensor housing (G) of the sensor device with an annular centering extension (81). Rope length sensor according to Claim 3 or 4 , characterized in that the centering flange (Z) is arranged in the axial direction in an inwardly facing bulge (85) of the flat housing (F). Rope length sensor according to one of the Claims 1 until 5 , characterized in that the sensor device comprises a sensor input shaft (90) which is rotatable in the sensor housing (G) and which can be coupled in a rotationally fixed manner to the cable drum (40) 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. Rope length sensor according to Claim 6 , characterized in that the shaft coupling device (W) is formed by two toothed sections (91, 92) which can be pushed into one another, wherein a first toothed section (91) is formed integrally on the cable drum (40) and a second toothed section (92) is formed on the sensor input shaft (90). Rope length sensor according to Claim 7 , characterized in that the first toothing section (91) is designed as an external toothing on an axial shaft extension (40a) of the cable drum (40) and the second toothing section (92) is designed as an internal toothing in an axial bore (93) of the sensor input shaft (90). Rope length sensor according to one of the Claims 1 until 8th , characterized in that the sensor input shaft (90) is assigned a shaft sealing device (95), in particular a shaft sealing ring. Rope length sensor according to Claim 9 , characterized in that the shaft sealing device (95) is arranged in the region of the centering extension (81) of the sensor housing (G). Rope length sensor according to one of the Claims 4 until 10 , characterized in that the annular centering extension (81) is formed on the bottom part (GB) of the sensor housing (G). Rope length sensor according to one of the Claims 1 until 11 , characterized in that the sensor device is designed as an absolute sensor device. Rope length sensor according to Claim 12 , characterized in that the absolute sensor device comprises a sensor which is connected to the sensor input shaft (90) via the interposition of a reduction gear (U) arranged in the electronics installation space (E) of the sensor housing (G). Rope length sensor according to Claim 12 or 13 , characterized in that the absolute sensor device comprises a redundant structure with two sensors, each of which is connected to the sensor input shaft (90) via the interposition of a reduction gear (U; U1, U2) arranged in the electronics installation space (E) of the sensor housing (G). Rope length sensor according to Claim 13 or 14 , characterized in that the sensor is designed as a Hall sensor. Rope length sensor according to one of the Claims 1 until 15 , characterized in that the cable drum (40) is arranged axially immovably in the flat housing (F). Rope length sensor according to one of the Claims 1 until 16 , characterized in 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 cable drum (40) in the flat housing (F). Rope length sensor according to one of the Claims 1 until 17 , characterized in that a bellows (46) with a scraper nozzle (47) through which the measuring cable (M) is guided is arranged at the measuring cable outlet (42) of the flat housing (F). Rope length sensor according to Claim 18 , characterized in that a nozzle guard (50) is arranged on the flat housing (F), which forms a stop for the bellows (46) provided with the scraper nozzle (47) when the measuring cable (M) is pulled out of the flat housing (F). Rope length sensor according to Claim 19 , characterized in that the nozzle guard (50) has a fork shape with a fork opening (52) formed by a fork (51), wherein the measuring cable (M) is guided through the fork opening (52) and the fork (51) forms a stop which cooperates with the scraper nozzle (47). Rope length sensor according to one of the Claims 1 until 20 , characterized in that a rope cleaning brush (60) is arranged in the flat housing (F). Rope length sensor according to Claim 21 , characterized in that the rope cleaning brush (60) is formed by a spirally wound brush with inwardly directed bristles wherein the measuring cable (M) passes centrally through the cable cleaning brush (60). Rope length sensor according to Claim 21 or 22 , characterized in that the rope cleaning brush (60) is arranged between the rope drum (40) and the deflection roller (43) in the rope guide channel (45) of the flat housing (F). Rope length sensor according to one of the Claims 1 until 23 , characterized in that the flat housing (F) is provided in a lower region with a drain opening (65) as a dirt and water drain. Rope length sensor according to one of the Claims 1 until 24 , characterized in that the flat housing (F) has a two-part structure consisting of a bowl-shaped base part (FB) and a bowl-shaped cover part (FD), wherein the cable drum (40) with the reset device (41), the cable cleaning brush (60) and the measuring cable outlet (42) are arranged in the base part (FB) and the deflection roller (43) is cantilevered in the base part (FB). Rope length sensor according to Claim 25 , characterized in that the base part (FB) is provided with the nozzle protection (50). Industrial truck, in particular counterbalance forklift truck, with a rope length sensor according to one of the preceding claims as a lifting height measuring system of a load handling device.

Images