VEHICLE LIFTING PLATFORM

Abstract

In order to improve the safety of a lifting platform with respect to risk of a vehicle falling, provision is made, in a lifting platform having carrying arms, which can be vertically adjusted by a lifting mechanism, for raising the vehicle and having carrying plates, which are arranged at a free end of the carrying arms, for carrying the vehicle to be lifted, for a sensor arrangement having a plurality of pressure sensors which are arranged distributed over a bearing surface of the carrying plates to be installed on each of the carrying plates and for a display which displays a pressure distribution over the bearing surface of the respective carrying plate to be associated with each carrying plate.

Claims

1. A lifting platform for vehicles, the lifting platform comprising: a lifting mechanism (1, 2); carrying arms (3, 4, 5, 6), which are vertically adjustable by the lifting mechanism (1, 2), for raising the vehicle, the carrying arme including carrying plates (3a, 4a, 5a, 6a; 10), which are respectively arranged at a free end of each of the carrying arms (3, 4, 5, 6), for carrying the vehicle to be lifted, the carrying plates (3a, 4a, 5a, 6a; 10; 100) comprise a weight force sensor arrangement (14, 20) that records a weight force which acts on the carrying plates (10; 100); the sensor arrangement (10, 20) comprises a plurality of pressure sensors (141) which are arranged distributed over a bearing surface of the carrying plates (3a, 4a, 5a, 6a; 10; 100) installed on each of the carrying plates (3a, 4a, 5a, 6a; 10; 100); and a respective display (15; 151) which displays a pressure distribution over the bearing surface of each of the respective carrying plates (3a, 4a, 5a, 6a; 10; 100) is associated with each said carrying plate (3a, 4a, 5a, 6a; 10; 100).

2. The lifting platform as claimed in claim 1, wherein the respective displays (15; 151) which are associated with each said carrying plate (3a, 4a, 5a, 6a; 10; 100) are arranged on a bottom side of the associated carrying plate or on a bottom side of the carrying arm (3, 4, 5, 6) which is associated with the associated carrying plate (3a, 4a, 5a, 6a; 10, 100).

3. The lifting platform as claimed in claim 1, wherein the displays (15; 151) comprise illuminated displays.

4. The lifting platform as claimed in claim 1, wherein the displays (15; 151) comprise light-emitting diodes.

5. The lifting platform as claimed in claim 1, wherein each said sensor arrangement (14) comprises a matrix sensor (20) having a large number of sensor cells which are arranged in a matrix.

6. The lifting platform as claimed in claim 5, wherein each said display (15) has multicolor lighting, and the lighting is arranged in the matrix sensor (20) of corresponding matrix form.

7. The lifting platform as claimed in claim 6, wherein the sensor cells comprise piezoresistive sensors.

8. The lifting platform as claimed in claim 1, wherein the sensor arrangement (14) comprises a film-type sensor (20) which comprises at least two films (21, 22) to which conductor tracks (23) are applied, and the conductor tracks (23) of the two films (21, 22) cross over each other at crossover points, and the crossover points form sensor cells.

9. The lifting platform as claimed in claim 1, wherein the carrying plates (3a, 4a, 5a, 6a; 10; 100) each have a plate-shaped carrying structure (11; 110) and a rubber-elastic support (13; 130) is arranged above said carrying structure, and the sensor arrangement (151) is configured to detect a deformation of the elastic support (13; 130) under application of force.

10. The lifting platform as claimed in claim 9, further comprising a metal element (132) embedded into the elastic support of each of the carrying plates (3a, 4a, 5a, 6a; 10, 100), and the sensor arrangement (141) is configured to detect a change in distance between the element (132) and the carrying structure (100) under application of force.

11. The lifting platform as claimed in claim 9, wherein the sensor arrangement (141) is arranged between the elastic support (130) and the carrying structure (110).

12. The lifting platform as claimed in claim 10, wherein the sensor arrangement (141) has at least one coil and a measuring device (152) is provided for measuring a change in an inductance of the coil (141) due to a change in distance between the coil (151) and the metal element (132).

13. The lifting platform as claimed in claim 12, wherein the sensor arrangement comprises a plurality of said coils (141) which are arranged offset in a circumferential direction, and the coils (141) are printed onto a printed circuit board (140) which is arranged between the elastic support (130) and the carrying structure (110).

14. The lifting platform as claimed in claim 1, wherein the sensor arrangements (14; 141) and associated displays (15; 151) of the carrying plates (3a, 4a, 5a, 6a; 10; 100) are battery-operated.

15. The lifting platform as claimed in claim 1, wherein a total weight force which is applied to the associated carrying plate (3a, 4a, 5a, 6a; 10; 100) is ascertained from signals generated by the sensor arrangements (14; 141).

16. The lifting platform as claimed in claim 15, wherein the signals are adapted to be wirelessly transmitted to a central control arrangement.

17. A carrying plate (10; 100) for a vehicle lifting platform comprising a weight force sensor arrangement (14; 141) for recording a weight force which acts on the carrying plate (10; 100), the sensor arrangement (14; 141) comprising a plurality of pressure sensors arranged distributed over a bearing surface of the carrying plate (10; 100), and a display (15; 151) associated with the carrying plate (10; 100), said display being arranged on a bottom side of said carrying plate and being configured to display a pressure distribution over the bearing surface of the carrying plate (10; 100).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Further properties and advantages of the invention are described on the basis of the exemplary embodiments and the appended drawings, in which:

[0042] FIG. 1 shows a 2-pillar lifting platform having four carrying arms, at the free ends of each of which a carrying plate is arranged,

[0043] FIG. 2 shows a section through a carrying plate in a first exemplary embodiment, which carrying plate can be used in the lifting platform in FIG. 1,

[0044] FIG. 3 shows a basic drawing of a pressure-sensitive film-type sensor, as can be used in a carrying plate,

[0045] FIG. 4 shows a section through a carrying plate in a second exemplary embodiment,

[0046] FIG. 5 shows a section through an elastomer support for the carrying plate from FIG. 4,

[0047] FIG. 6 shows an isometric view of the elastomer support from FIG. 5, and

[0048] FIG. 7 shows a block diagram of a sensor arrangement, display device and associated control circuit.

DETAILED DESCRIPTION

[0049] FIG. 1 illustrates a lifting platform having two lifting pillars 1, 2, to each of which two carrying arms 3, 5 and, respectively, 4, 6 are pivotably articulated. The carrying arms 3, 4, 5, 6 are vertically adjustable, that is to say they can be raised and lowered. The lifting driving inside the lifting pillar 1, 2 is carried out in a manner known per se, for example by means of cylinder/piston assemblies, by means of a threaded spindle or by means of a chain drive. The present invention is not restricted to two pillar lifting platforms, but rather can be used in all types of lifting platforms with carrying arms, such as 4-pillar lifting platforms or post-type lifting platforms.

[0050] The carrying arms 3, 4 form a front carrying arm pair, that is to say serve for raising the front half of the vehicle, and the carrying arms 5, 6 form a carrying arm pair for the rear half of the vehicle. The carrying arms 3 and 5 of the left-hand vehicle side are arranged in a mirror-inverted manner with respect to the carrying arms 4, 6 of the right-hand vehicle side. The carrying arms are each pivotably mounted on their associated lifting pillar 1, 2 via a pivot bearing 3a, 4a, 5a, 6a, with the result that they can be pivoted beneath a vehicle parked between the lifting pillars 1, 2 and can be moved to the holding points on the bottom of the vehicle.

[0051] Carrying plates 3b, 4b, 5b, 6b are arranged at the free ends of the carrying arms 3, 4, 5, 6 and come into contact with the vehicle as the carrying arms are raised. The carrying plates 3b, 4b, 5b, 6b can also be vertically adjustable to a certain extent with respect to the associated carrying arms 3, 4, 5, 6 by means of a thread.

[0052] FIG. 2 illustrates, by way of example, a carrying plate 10. Said carrying plate comprises a plate-like carrying structure 11 which is fastened in a corresponding holder to a carrying arm by means of a pin or threaded bolt 12 which is arranged on the bottom side of said carrying structure. A cover 13 with a top side 13a with slip-resistant structuring is located on the top side of the carrying structure 11. The cover 13 is screwed to the carrying structure 11. Said cover is composed of a rubber-elastic material which ensures secure bearing on a vehicle. A sensor arrangement 14 in the form of a film-type sensor having a large number of pressure-sensitive sensor cells which are distributed over the sensor surface is located between the support 13 and the carrying structure 11. The film-type sensor 14 allows the measurement of a pressure force distribution over the bearing surface of the carrying plate 10. An illuminated display 15, which serves to show and display a mirror-inverted image of the pressure distribution which is measured by the film-type sensor 14, is located on the bottom side of the carrying structure 11.

[0053] In the exemplary embodiment, the illuminated display 15 consists of a large number of individual lighting points in the form of multicolor light-emitting diodes and extends over the entire available bottom side of the carrying plate (that is to say apart from that area which is taken up by the pin). The lighting points can be individually controlled depending on the pressure force measured directly across them. Control is performed by means of an evaluation electronics system, not shown in any detail here, which can be accommodated, for example, inside a cavity in the pin or bolt 12.

[0054] Showing the pressure force distribution which is measured over the supporting surface of the carrying plate 10 by means of an illuminated display 15 allows an operator to check, before he steps beneath a raised vehicle, whether the vehicle has been correctly held at the support points. If the supporting force is concentrated in a region at the edge of the carrying plate 10 for example, the vehicle could slip and fall while work is being performed. A situation of this kind can be easily identified and corrected in order to avoid accidents. In this manner, measuring and showing the pressure force distribution on the individual carrying plates 10 contributes to increasing the operational safety.

[0055] In addition, a battery-assisted power supply for autonomously operating the illuminated display and also a compact transmitter, with which measured pressure force signals can be transmitted to a central control arrangement in order to in this way allow the loading on the individual carrying arms to be compared, can be accommodated in the bolt or pin 12.

[0056] In the exemplary embodiment, the carrying arms of the rear pair of carrying arms are designed, without the invention being restricted to this, as double-jointed arms, whereas the carrying arms 3, 4 of the front pair of carrying arms are embodied as conventional, rigid carrying arms. Therefore, the carrying arms 3, 4 can be pivoted only about their respective articulation point 3a, 4a on the pillars 1, 2 and can also be telescopically adjusted in terms of length (2-fold telescopically length-adjustable). The rear two carrying arms 5, 6 are provided with an additional bending joint 51, 61, with the result that the respective carrying arm 5, 6 can be bent in its pivot plane which is defined by the pivot joint 5a, 6a. The rear carrying arms 5, 6 are also likewise telescopically length-adjustable. This arrangement renders it possible to hold vehicles in a highly variable manner and, in particular, to hold vehicles of different vehicle lengths.

[0057] The film-type sensor 14 which is arranged beneath the plastic part which forms the cover 13 of the carrying plate 10 serves to identify and, respectively, to measure the point loading over the supporting surface of the carrying plate. An example of a film-type sensor of this kind is schematically illustrated in FIG. 3. The film-type sensor 20 shown in said figure consists of two thin polyester films 21, 22 onto which conductor tracks 23 are printed. In the respective measurement region 24 of the films 21, 22, the conductor tracks 23 are fanned out and run perpendicular in relation to one another, that is to say in the longitudinal direction on the film 21 and in the lateral direction on the film 22, with the result that a matrix arrangement is created between the films 21, 22 which are laid one on the other.

[0058] A pressure-sensitive, in particular piezoresistive, coating 25 is applied along the conductor tracks 23 on the inside of the two films 21, 22. On account of this coating, there is a pressure force-dependent variable resistance at the crossing points of the matrix between the conductor tracks 23 which cross each other. Each crossing point of the matrix therefore forms a sensor cell or a sensor element (pressure force sensor). By means of a processor-controlled multiplexer, each crossing point of the matrix can be wired and the cell resistance thereof can be measured. The wiring by means of the evaluation electronics system prevents the cells from influencing one another. The shape and the matrix geometry of the film-type sensor 20 can be matched to the respective application. For application in the carrying plate 10, the conductor tracks can also run, for example, in the form of concentric rings on one film and radiantly in the radial direction on the other film. The sensor density can be prespecified by means of the distance between the printed conductor tracks 23. The number of sensor cells distributed over the sensor matrix can be several hundred to several (tens of) thousand sensors.

[0059] The lighting points of the illuminated display 15 are arranged on the bottom side of the carrying plate in accordance with the distribution of the sensor cells over the film-type sensor 14, with the result that each sensor cell corresponds to a lighting point. However, it is likewise also possible to combine a plurality of sensor cells and assign them to one lighting point given a corresponding high cell density. For simplification purposes, the illuminated display 15 can also be subdivided into segments and controlled segment by segment. Due to the optical indication of the pressure force distribution over the holding surface of the carrying plate, the operator is able to check for correct holding of the raised vehicle at any time. Summing over the pressure force which is measured by the individual sensor cells allows a weighing function of the load which is absorbed overall by the carrying plate. This value can be wirelessly transmitted to a base station for the purpose of comparing the loads resting on the various carrying arms.

[0060] In a development of the invention, the pressure distribution displayed on the display or the values for the surface loading, which values are ascertained by the sensor arrangement 15, can be stored and saved in the form of a log for a certain period of time. This renders it possible to subsequently comprehend the holding situation of a vehicle in the event of a fault or an accident. It is likewise possible for the signals which are measured by the sensor arrangement 15 or derived therefrom to be transmitted to a central point and further processed or buffer-stored there. The transmission can be carried out, in particular, via a wireless interface. The operating state of the lifting platform can be monitored and operating and operator-control parameters can be recorded and logged in the central point.

[0061] A further exemplary embodiment of the invention is shown in FIGS. 4 to 7. The carrying plate 100 shown in section in FIG. 4 has a plate-like carrying structure 110 which is referred to as a holding plate. A threaded bolt 120 (for example M42x3) is centrally fastened to the bottom side of said holding plate. For the purpose of telescopic vertical adjustment, said threaded bolt is inserted into a threaded bushing 121 which in turn has an external thread (for example M56x3) by way of which it is screwed into a telescopic bushing 122 with a corresponding internal thread. The telescopic bushing 122 is provided with a protective cap 123 on the bottom side. A disk 124 which is screwed against the bottom side of the threaded bolt 120 secures the threaded bolt in the lower, radially extended region of the threaded bushing 121, with the result that the threaded bolt 120 can be screwed out or in with respect to the threaded bushing 121 in terms of height only within the permissible adjustment range, but cannot be removed. FIG. 4 illustrates the maximum upwardly screwed-out position of the threaded bolt 120 in the threaded bushing 121.

[0062] An elastomer support 130 is arranged on the top side of the holding plate 110 and engages around the edge of the holding plate 110 and is screwed to the holding plate 110 from the top side by means of two countersunk screws 133. The elastomer support 130 has, on the top side, slip-resistant profiling in the form of segmented stepped rings 131 which become higher toward the outside and the arrangement of which can be seen more clearly in FIG. 6.

[0063] In the exemplary embodiment, without the invention being restricted to this, the elastomer support consists of acrylonitrile-butadiene rubber (NBR) which is also known by the trade name Perbunan. This synthetic rubber is extremely resistant to the effect of fuels and oils, in particular hydraulic oils, greases and other aliphatic hydrocarbons, acids and alkalis. Good physical values, such as high abrasion resistance and stability and a favorable temperature resistance of 25 C. to +100 C. for example, make the material ideally suitable for use in automotive workshops and here, in particular, for a support element for holding heavy motor vehicles. Further materials which come into consideration for said use are, for example, HNBR (hydrogenated NBR) or Viton (fluorinated rubber).

[0064] The elastomer support shown has a Shore hardness (Shore A) of 705 Shore. Given a load of 1250 kg and a diameter of the carrying plate of 120 mm, a change in distance in the region of 5% results in this case. This provides a good basis for an inductive distance measurement with a sufficient change in measurement value even given relatively small loads.

[0065] The carrying plate 100 comprises a first printed circuit board 140, which is arranged between the elastomer support 130 and the holding plate 110, and a second printed circuit board 150 which is fitted to the bottom side of the holding plate 110. A transparent cover 160 protects the lower printed circuit board 150 and its components from mechanical influences and dirt. The printed circuit boards 140 and 150 are connected to one another in terms of signaling by means of a printed circuit board connector or plug-in connector which is routed through an elongate hole in the carrying structure 110. The printed circuit board 140 is composed of a conventional printed circuit board material FR4, a composite material comprising epoxy resin and glass-fiber fabric. Due to the large supporting surface and the printed circuit board material used, the supporting force can be transferred without problems by means of the printed circuit board 140. The printed circuit board 140 comprises a sensor arrangement for measuring a pressure force distribution. The second printed circuit board 150 contains, firstly, an evaluation electronics system and power supply for the sensor arrangement which is located on the upper printed circuit board 140, and secondly a display in the form of a plurality of two-color light-emitting diodes 151.

[0066] The measurement principle underlying the second exemplary embodiment is based on the elastomer support 130 being more or less deformed by a load. In the second exemplary embodiment, the invention makes use of the deformation being dependent on the applied pressure force on account of the material composition. Therefore, the sensor arrangement is designed to measure the deformation of the elastomer support 130. This can be performed capacitively or, as in the present exemplary embodiment, inductively.

[0067] A metal intermediate sheet 132 is embedded in the interior of the elastomer support 130. The intermediate sheet 132 ensures, firstly, a planar pressure distribution over the holding plate 110. The intermediate sheet 132 also serves as a reference point for a distance measurement. The material of the elastomer support which is located between the carrying structure 110 of the carrying plate and the intermediate sheet 132 is deformed depending on an applied force. For measurement purposes, the change in distance between the carrying structure 110 and the intermediate sheet 132 under the action of force, that is to say the change in thickness of the elastomer layer located therebetween, is measured. The change in the distance has an effect on the inductance of a coil which in turn can be evaluated in electrical terms. The sensor arrangement and the evaluation electronics system are illustrated in FIG. 7.

[0068] A total of eight printed coils 141 are applied with a circular arrangement to the upper printed circuit board 140. Said printed coils are connected to the evaluation electronics system 152, which is located on the lower printed circuit board 150 and can be realized in the form of integrated circuits, by means of the plug-in connection (not shown) which runs through the carrying plate 110. A total of eight two-color light-emitting diodes 151 are also located with a likewise circular arrangement on the lower printed circuit board 150. Each of the light-emitting diodes 151 is assigned to one of the printed coils 141 and serves as a display for the supporting force which is ascertained by means of this coil. The pressure force is therefore measured and displayed by means of eight sectors which correspond to the segmentation of the stepped rings 131 of the elastomer support 130.

[0069] The evaluation electronics system 152 comprises a microcontroller 153, an integrated control module with an analog switch and a binary counter, an integrated control module with shift registers, an acceleration sensor 156, a transmitter/receiver module 157 for wireless data transmission, for example according to the Bluetooth or Zigbee standard, and a programming interface 158 according to the JTAG and/or UART standard.

[0070] The inductance of the coils 141 is controlled or measured by means of the analog switch module 154 which also comprises binary counters, with the aid of which a signal frequency can be measured by counting over defined time intervals. The LEDs 151 are controlled in a multiplexed manner, that is to say with a time delay by means of the shift registers 155 which serve as port extenders.

[0071] The power supply 159 is provided by means of two batteries 159a, 159b, for example 3 V lithium button cells, one 159a of which serves for supplying the evaluation electronics system 152 and the other 159b of which serves for supplying the LEDs 151 since the latter have the highest power consumption during operation. Each of the batteries has a controlled DC/DC converter 159a, 159b in order to reduce the voltage to a lower value of, for example, 2 V. The DC/DC converters 159a, 159b are likewise controlled by the microcontroller 153 which measures the respective battery voltage and accordingly controls the associated DC/DC converter 159a, 159b.

[0072] The printed coils 141 which change their inductance depending on the distance from the intermediate sheet 132 in the support 130 are used for signal recording purposes. A modified Colpitts oscillator is used in order to measure the change in inductance. In order to keep the circuit complexity and the required number of components and signal lines low, four coils are connected to the oscillator by means of the analog switch 154. This also makes it possible to prevent the coils 141 from influencing each other. In order to be able to evaluate the sensor signal as easily as possible with the microcontroller 153, use is made of a counter module 154 which measures the oscillator oscillations. The output signal from the counter module 154 can be directly evaluated using an input capture of the microcontroller 153. The acceleration sensor 156 is used in order to identify a movement and therefore to start the force measurement. This acceleration sensor 156 can also be used to identify the position and therefore, for example, to also identify whether the carrying plate 110 is installed horizontally.

[0073] One of the two-color LEDs 151 is used for each sector for display purposes. In order to save pins on the microcontroller 153, shift registers 155 are used as port extenders for control purposes. Since the voltage supply 159 cannot drive much current, only one of the LEDs 151 should always be active and the control should therefore be performed in a multiplexed manner. This extends the service life of the battery 159b. The intensity of the LEDs can be reduced by means of additional PWM control.

[0074] The applied-load-dependent measurement values which are ascertained for each sector can be transmitted to a central computer via the radio interface 157 or can be transmitted to remote servers via a network, where the measurement values are further evaluated and stored.