Landing gear with a force measuring element

Description

[0001] The invention relates to a landing gear with a force measuring element according to the features in the preamble of claim 1.

[0002] Such landing gears are often attached to semi-trailers or trailers in general and support them on the ground, particularly when uncoupled from the towing vehicle. This ensures that the semi-trailer remains stable in its parked position and can be approached for re-coupling by a towing vehicle. In other applications, the landing gears are mounted at the rear of silo vehicles and are extended to stabilize the vehicle before the tipping process begins. EP-A-3293062 discloses such a landing gear.

[0003] DE 10 2005 036 139 A1 discloses a landing gear with a pressure element and a support load indicator, which indicates to the operator that the landing gear is secure when the landing gear is extended. The pressure element comprises a spring element and a interacting switching element in the form of a mechanical button, wherein the spring element is arranged between a spindle stop ring fixedly arranged on the spindle and the spindle bearing plate. During the extension of the landing gear, if the ground is stable, the spindle moves against the spindle bearing plate, causing the spring element to deform and actuate the switching element. The switching element, in turn, is connected to an indicator element that indicates to the operator that the landing gear is loaded.However, it has proven disadvantageous that the spring element does not provide reproducible values ​​after frequent load changes, thus triggering the switching element even with insufficient force. Furthermore, the support load indicator does not provide a quantitative statement about the forces transmitted by the landing gear.

[0004] Consequently, the object of the invention was to provide a support winch that enables a quantitative and reproducible measurement of the forces transmitted from the support winch to the ground.

[0005] The object is achieved according to the invention with the features of claim 1. A force measuring element integrated into the support component can be used to determine whether a trailer to be uncoupled is parked securely and, particularly in the case of a semi-trailer, whether the landing gear has firm ground contact. In addition to this qualitative determination, a quantitative determination of the load acting on the landing gear is also performed. This, together with the recording of the axle loads, makes it possible to determine the total weight of the trailer and thus detect potential overloading or uneven load distribution.

[0006] A force measuring element is a sensor that generates a signal proportional to the applied force from a deformation of the supporting component. Piezoelectric sensors, for example, detect the change in electrical polarization and thus the occurrence of an electrical voltage in solid bodies when they are elastically deformed. Alternatively, capacitive sensors can be used as force measuring elements.

[0007] The force measuring element is attached to the support component, with attachment of the force measuring element within the support component or on the surface of the support component being preferred. What all attachment positions have in common is that the force measuring element is connected to the support component in such a way that it detects its deformation as precisely as possible. A force-fitting, material-fitting, and / or form-fitting connection is suitable, in particular by means of a precisely fitting clamping or adhesive bond.

[0008] Conveniently, a spindle thrust bearing is located beneath the spindle bearing plate. The thrust bearing surrounds the spindle and ensures rotatable support of the spindle while simultaneously supporting the spindle, which is subject to pressure, in the axial direction against the spindle bearing plate. Radial support of the spindle, however, is provided by the spindle opening in the spindle bearing plate.

[0009] According to a particularly useful embodiment, the axial bearing rests with its upper bearing section against the underside of the support component, at least when the spindle is under load. The upper bearing section of the axial bearing is thus fixed to the support component, at least under load.

[0010] According to a first preferred embodiment, the support component is the spindle bearing plate. Alternatively, the support component can also be a measuring plate arranged between the upper bearing section of the axial bearing and the spindle bearing plate. The measuring plate is formed, for example, as a measuring ring that coaxially surrounds the spindle.

[0011] Preferably, the measuring plate is mounted in a rotationally fixed manner with respect to the outer pipe. This results in the advantage that a connecting line can be installed stationary.

[0012] The measuring plate can, in particular, have a concave or bridge-like shape with external support sections facing the spindle bearing plate and a cantilevered section arranged between them. Due to this shape, there is always a free installation space in the area of ​​the cantilevered section to the spindle bearing plate, in which, for example, a force measuring element can be inserted in a particularly protected manner. Furthermore, the concave or bridge-like shape of the measuring plate ensures greater deformation of the measuring plate in the area of ​​the cantilevered section when force is introduced from the axial bearing, which introduces an axially directed force centrally onto the cantilevered section, thus enabling a relatively large deformation and, consequently, more precise force measurement.

[0013] The axial bearing can, in particular, rest with its lower bearing section against a spindle stop ring that is firmly connected to the spindle. The lower bearing section is thus arranged so that it can rotate relative to the support component and is stationary relative to the spindle. When the spindle is loaded, the support component presses against the lower bearing section from below and pushes the axial bearing with the upper bearing section against the support component, which deforms as a result of the applied load.

[0014] It makes sense to position the force measuring element above the axial bearing, at least partially within its projected area. In this area, the load is introduced into the supporting component via the axial bearing, and the deformation measurable by the force measuring element is at its greatest, enabling a particularly precise and reproducible determination of the introduced force.

[0015] According to a further embodiment of the invention, the force measuring element is expediently pin-shaped and inserted into a complementarily shaped recess of the support component without play or under prestress.

[0016] A particularly useful embodiment is one in which the pin-shaped force measuring element is a measuring dowel. A measuring dowel is a transverse force-sensitive sensor, typically cylindrical in shape, that is inserted into a complementarily shaped measuring dowel bore in the component to be measured, always fitting precisely and / or under preload, or at least when the expected operating load is present. The preload of the measuring dowel is achieved, for example, by means of a clamping device integrated into the measuring dowel.

[0017] Preferably, the recess is a measuring dowel bore formed in the support component, into which the measuring dowel is inserted. The diameter of the measuring dowel bore is typically 6.00 mm to 10.00 mm, particularly preferably 8 mm.

[0018] The measuring dowel bore in the support component can, for example, be aligned radially to the spindle. Preferably, the measuring dowel bore is also arranged orthogonally to an adjacent wall of the outer tube, thereby minimizing the length of the measuring dowel bore and thus the material weakening of the support component.

[0019] Advantageously, the measuring dowel bore extends at least partially over the axial bearing, offset in the axial direction. This makes it possible to position the measuring dowel above the axial bearing in an area of ​​maximum force application.

[0020] For practical purposes, the measuring dowel bore is designed as a blind hole, and the measuring dowel is inserted into the deepest part of the blind hole. This results in a particularly protected mounting position for the measuring dowel.

[0021] According to another alternative embodiment, the force measuring element is a strain gauge application. The strain gauge application is used to detect stretching and compressive deformations of the supporting component. It changes its electrical resistance even at small deformations and is used as a strain sensor. Typically, the strain gauge application is glued to the supporting component, which deforms minimally under load. Its deformation (strain) under load then leads to a change in the electrical resistance of the strain gauge application.

[0022] Preferably, the strain gauge application is mounted on the top and / or bottom of the support component. This offers the advantage that no weakening of the support component is required through drilling or milling, and that maximum strain or compression is present on the top and bottom of the support component, thus enabling particularly precise and reproducible measurement values.

[0023] Advantageously, the force measuring element is a pressure sensor arranged between the measuring plate and the spindle bearing plate. A pressure sensor belongs to the group of pressure measuring devices, which, as the first link in a measuring chain, convert the physical quantity of pressure (force per area) into an electrical output value as a measure of the pressure. Piezoresistive or piezoelectric, capacitive, or inductive pressure sensors, as well as pressure sensors with a Hall element, are particularly suitable.

[0024] A particularly useful embodiment of the invention can provide for the pressure sensor to be arranged on the self-supporting section of the concave or bridge-shaped measuring plate in such a way that a force shunt is transmitted via the pressure sensor to the spindle bearing plate. This results in the advantage that the pressure sensor does not have to transmit the entire force flow of the landing gear and is thus largely protected from overload. Furthermore, the spectrum of forces to be transmitted is narrow, allowing the use of a pressure sensor with a narrower measuring range, which in turn provides more precise measured values.

[0025] For a better understanding, the invention is explained in more detail below with reference to nine figures. Fig. 1: a longitudinal section through a support winch according to a first embodiment with a pin-shaped force measuring element in a spindle bearing plate; Fig. 2: a cross-section through the landing gear according to Fig. 1 in the section plane CC; Fig. 3: an enlarged section of detail X in Fig. 2 ; Fig. 4: a longitudinal section through the upper section of a support winch according to a second embodiment with a pin-shaped force measuring element in the spindle bearing plate; Fig. 5: a longitudinal section through a schematically illustrated landing gear with a strain gauge application as a force measuring element on the spindle bearing plate; Fig. 6: a longitudinal section through a schematically illustrated support winch with a pin-shaped force measuring element in a measuring plate; Fig. 7: a longitudinal section through a schematically illustrated landing gear with a strain gauge application as a force measuring element on a measuring plate; Fig. 8: a longitudinal section through a schematically shown landing gear with a concave or bridge-like measuring plate and a force measuring element inserted therein and Fig. 9: a longitudinal section through a schematically illustrated support winch with a concave or bridge-like measuring plate and a pressure sensor arranged between the cantilevered section and the spindle bearing plate.

[0026] The Fig. 1 shows a longitudinal section of a landing gear with an outer tube 20 in the form of a square profile and an inner tube 30 guided axially therein. Due to the complementary profile shape of the outer and inner tubes 20, 30, the inner tube 30 is held in the outer tube 20 in a rotationally fixed manner in the circumferential direction.

[0027] To attach the landing gear to a vehicle, a mounting flange plate 28 protrudes on both sides of the outer tube 20, in which mounting holes 29 are provided at discrete intervals. The inner tube 30 carries a support foot 32 at its lower end, with which the landing gear rests on the ground when the inner tube 30 is extended.

[0028] Arranged in the outer tube 20 is a gear arrangement 40 comprising a spindle 42 rotatably mounted relative to the outer tube 20 and a gear 41 which is connected to the spindle 42 in a rotationally fixed manner at an upper end portion thereof. The gear arrangement 40 is in particular Fig. 4 illustrated gear set 49 and a transmission input shaft 47. Rotation of the spindle 42 causes a spindle nut 31, which is firmly attached to an upper section 33 of the inner tube 30, to move either upwards or downwards, depending on the direction of rotation. When the spindle nut 31 moves downwards, it pushes the inner tube 30 and the support foot 32 attached to it toward the ground, and the landing gear is extended. When the spindle nut 31 moves upwards, it lifts the inner tube 30 and the support foot 32, and the landing gear is retracted.

[0029] The spindle 42 passes through a spindle bearing plate 21 arranged below the gear 41, which is formed with a spindle opening 24 whose inner diameter is selected to be only slightly larger than the outer diameter of the spindle 42. The spindle 42 is mounted in its radial direction with the aid of the spindle bearing plate 21 and the spindle opening 24. The spindle bearing plate 21 is firmly connected to the inner wall of the outer tube 20 on at least three sides, preferably on four sides. The spindle bearing plate 21 is aligned essentially orthogonally to the extension of the outer tube 20. The spindle 42 and the associated spindle opening 24 in the spindle bearing plate 21 are accommodated centrally in the outer tube 20.

[0030] An axial bearing 43 is pushed onto the spindle 42 beneath the spindle bearing plate 21, which in turn is adjacent to a spindle stop ring 46. As soon as the support foot 32 rests on the ground, the spindle stop ring 46 pushes the axial bearing 43 upward until it rests against an underside 23 of the spindle bearing plate 21.

[0031] In the spindle bearing plate 21, a recess 25, in particular a measuring dowel bore 25, is introduced, which is aligned transversely to the spindle 42 and which also extends through the outer tube 20 at its end facing away from the spindle 42. The recess 25 is in the same type of landing gear in Fig. 2 as a view onto the section plane CC according to Fig. 1 and in enlarged view in Fig. 3 This can be seen particularly clearly. In the exemplary embodiment, the recess 25 is designed as a blind hole 26, the deepest part 27 of which is located in the spindle bearing plate 21 in close proximity to the spindle opening 24. In this exemplary embodiment, the recess 25 runs parallel to the mounting flange plates 28 and is thus oriented in or against the direction of travel when the landing gear is mounted on a vehicle.

[0032] A pin-shaped force measuring element 10, in particular in the form of a measuring dowel 11, is fixedly inserted into the recess 25 and clamped within the measuring dowel bore 25 relative to the spindle bearing plate 21. The position of the measuring dowel 11 shown as an example is located in the region of the borehole depth 27 and thus in a projected area above the axial bearing 43. With the inner tube 30 extended relative to the outer tube 20 and the support foot 32 resting on the ground, a force flow occurs from the support foot 32 via the inner tube 30, the spindle nut 31, the spindle 42 and the axial bearing 43 into the spindle bearing plate 21.Since the spindle bearing plate 21 is non-positively connected to the outer tube 20 at its edge region, the relatively greatest deformation occurs in the region of the spindle bearing plate 21 above the axial bearing 43 and thus the most precise measurement of this deformation occurs by means of the measuring dowel 11, the measured value of which can be assigned to a corresponding support load.

[0033] The measuring dowel bore 25, arranged as an example within the spindle bearing plate 21, also continues in an aligned extension into the outer tube 20. A transition coupling 13 is inserted into an open end of the measuring dowel bore 25, with the aid of which the measuring dowel bore 25 is closed to the outside and through which only a connecting cable 14 is led out of the measuring dowel bore 25. Via the connecting cable 14, the measuring dowel 11 is electrically connected to an on-board network of a vehicle (not shown here), from which the measuring dowel 11 is supplied with electrical power. Furthermore, the measuring dowel 11 provides the vehicle with force measurement signals via the connecting cable 14.

[0034] In Fig. 4 an alternative embodiment is shown in which the measuring dowel bore 25 is arranged offset by 90° in the spindle bearing plate 21 and the outer tube 20 and breaks through the outer tube 20 at the rear, between the mounting flange plates 28.

[0035] For extension or retraction, the landing gear has a gear input shaft 47, to which a crank (not shown) can be connected in a rotationally fixed manner. Using the crank, an operator can rotate the gear input shaft 47, whereby the inner tube 30 with the support foot 32 can be extended or retracted as required, depending on the direction of rotation. In the illustration of the Fig. 4 the inner tube 30 is in a retracted position relative to the outer tube 20.

[0036] The transmission input shaft 47 transmits the torque to the gear set 49, which meshes with the gear 41 of the transmission assembly 40 and also engages a transmission output shaft 48. The transmission input shaft 47 and the transmission output shaft 48 are aligned axially parallel to each other. The recess 25 or measuring dowel bore 25 also runs parallel to the transmission input shaft 47 and the transmission output shaft 48.

[0037] The axial bearing 43 of the spindle 42 is constructed in two parts and comprises an upper bearing section 44, which is arranged adjacent to the underside 23 of the spindle bearing plate 21. When the inner tube 30 is retracted into the outer tube 20, a gap may form between the upper bearing section 44 and the underside 23 of the spindle bearing plate 21 due to the weight of the inner tube 30 and the support foot 32, since in this retracted position the spindle 42 is supported by its securing bolt 42a, suspended from an upper side 22 of the spindle bearing plate 21.

[0038] With the inner tube 30 extended and a support foot 32 resting on the ground, the spindle 42 is pushed upward, and the spindle stop ring 46, which is fixedly formed on the spindle 42, abuts against a lower bearing section 45 of the axial bearing 43. With the help of the axial bearing 43, force is transmitted to the upper bearing section 44, which is pressed against the underside 23 of the spindle bearing plate 21 and rests against it. At the same time, the axial bearing 43 allows further rotation of the spindle 42 even when the support jack is subjected to compressive loads.

[0039] The measuring dowel bore 25, which runs radially towards the spindle 42, is aligned and dimensioned such that the measuring dowel 11 clamped therein is arranged above the axial bearing 43 and thus as close as possible to the force introduction point of the forces transmitted from the spindle 42 into the spindle bearing plate 21.

[0040] The Fig. 5 represents an alternative embodiment with a force measuring element 10 in the form of a strain gauge application 12. The strain gauge application 12 is applied to the upper side 22 of the spindle bearing plate 21 and overlaps at least partially with the axial bearing 43 arranged underneath, via which a compressive force is transmitted in the direction of the arrow to the spindle bearing plate 21 when a support foot 32 rests on the ground. As a result, a large part of the deformation of the spindle bearing plate 21 takes place in an area of ​​the strain gauge application 12, which enables particularly precise force measurement.

[0041] The strain gauge application 12 can be connected to the energy and data system of a vehicle by means of a connecting cable 14.

[0042] In the Fig. 6 A further embodiment is shown, in which a measuring plate 15 is inserted between the axial bearing 43 of the spindle 42 and the spindle bearing plate 21 fastened to the outer tube 20. The measuring plate 15 is provided with a central bore for receiving the spindle 42 and is designed with a closed ring shape. When the support jack is extended and loaded, the measuring plate 15 experiences a compressive force from the spindle 42 moving upwards in the direction of the arrow, which presses the measuring plate 15 via the spindle stop ring 46 and the axial bearing 43 against the underside 23 of the spindle bearing plate 22. The spindle bearing plate 22 ensures force transmission to the outer tube 20 and from there via the mounting flange plate 28 (see Fig. 1 ) on the vehicle.

[0043] The measuring plate 15 has a recess 25, in particular a measuring dowel bore 25, into which a pin-shaped force measuring element 10, in particular a measuring dowel 11, is inserted as the force measuring element 10. The recess 25 is aligned radially to the spindle 42, and the pin-shaped force measuring element 10, in particular the measuring dowel 11, is located above the axial bearing 43 of the spindle 42, which transmits the forces to the measuring plate 15 when the support winch is loaded.

[0044] To prevent the measuring plate 15 from rotating together with the spindle 42, the measuring plate 15 is connected to the spindle bearing plate 21 in a rotationally fixed manner via a measuring plate holder 16. As a result, the measuring plate 15 is held in a rotationally fixed manner relative to the outer tube 20, and the connecting line 14 can be led out of the outer tube 20 at a predetermined position without having to install movable cables.

[0045] The Fig. 7 shows a further embodiment with a measuring plate 15 provided with a strain gauge application 12. The measuring plate 15 is designed with a concave or bridge-like shape and, when loaded, is supported only in its lateral edge region by means of support sections 17 on the underside 23 of the spindle bearing plate 21. The self-supporting section 18 located between the support sections 17 is always arranged at a distance from the underside 23 of the spindle bearing plate 21, regardless of the load on the axial bearing 43, and carries the strain gauge application 12, which cannot collide with the spindle bearing plate 21 due to this installation location.

[0046] It is also possible to configure the measuring plate 15 with the force measuring element 10 as a particularly thin measuring foil. Here, too, the measuring plate 15 is located in the force flow between the axial bearing 43 and the outer tube 20 in order to be able to measure any forces there.

[0047] The Fig. 8 shows a further embodiment with a concave or bridge-like shape of the measuring plate 15, whose upstanding support sections 17 protrude in the direction of the spindle bearing plate 21 relative to the cantilevered section 18 arranged therebetween. A recess 25 tapering radially toward the spindle 42 is formed in the measuring plate 15, in particular a measuring dowel bore 25, into which a pin-shaped force measuring element 10, in particular a measuring dowel 25, is inserted. The force measuring element 10 is located in an area of ​​the cantilevered section 18 of the measuring plate 15, which, when loaded by the support winch, is subject to a greater, reversible deformation than the support sections 17 and enables particularly precise measurement.

[0048] In the Fig. 9 1 shows a landing gear according to the invention in an alternative embodiment with a likewise concave or bridge-like measuring plate 15. However, a pressure sensor 19 is used as the force measuring element 10, which is arranged on a side of the self-supporting section 18 facing the spindle bearing plate 21. The pressure sensor 19 terminates on its upper side with the support sections 17 of the measuring plate 15 and, when the landing gear is loaded, rests together with the support sections 17 on the underside 23 of the spindle bearing plate 21, so that a force shunt exists and the pressure sensor 19 is subjected to only a portion of the total force transmitted from the axial bearing 43 to the spindle bearing plate 21. Bezugszeichenliste

[0049] 10Force measuring element 11Pin-shaped force measuring element, measuring dowel 12Strain gauge application 13Transition coupling 14Connecting cable 15Measuring plate 16Measuring plate holder 17Support section(s) measuring plate 18Cantilever section measuring plate 19Pressure sensor 20Outer tube 21Spindle bearing plate 22Top of spindle bearing plate 23Bottom of spindle bearing plate 24Spindle opening of spindle bearing plate 25Recess, measuring dowel hole 26Blind hole 27Deepest blind hole 28Mounting flange plate 29Mounting holes 30Inner tube 31Spindle nut 32Support foot 33Upper section of inner tube 40Gear assembly 41Gear 42Spindle 42aSecuring bolt 43Spindle thrust bearing 44Upper bearing section 45Lower bearing section 46Spindle stop ring 47Gear input shaft 48Gear output shaft 49Gear set

Claims

1. A landing gear having a force-measuring element (10), the landing gear comprises an outer tube (20), an inner tube (30) movably mounted in the outer tube (20), and a transmission assembly (40) comprising at least one spindle (42) driven by a gear (41), wherein the spindle (42) is fed through a spindle opening (24) in a spindle bearing plate (21) which is in contact with the outer tube (20), and a spindle nut (31) fastened to the inner tube (30) is held on the spindle (42), characterized in that the force-measuring element (10) is mounted on a support component (15, 21) disposed in the force flow between the spindle (42) and the outer tube (20).

2. The landing gear according to claim 1, characterized in that a force is detected by means of the force-measuring element (10) as a function of the deformation of the support component (15, 21).

3. The landing gear according to claim 1 or 2, characterized in that a thrust bearing (43) of the spindle (42) is arranged under the spindle bearing plate (21).

4. The landing gear according to claim 3, characterized in that the thrust bearing (43) is supported under load with its upper bearing section (44) on the underside (23) of the support component (15, 21).

5. The landing gear according to one of claims 1 to 4, characterized in that the support component (15, 21) is the spindle bearing plate (21).

6. The landing gear according to claim 4, characterized in that the support component (15, 21) is a measuring plate (15) arranged between the upper bearing section (44) of the thrust bearing (43) and the spindle bearing plate (21).

7. The landing gear according to claim 6, characterized in that the measuring plate (15) is mounted in a rotationally fixed manner with respect to the outer tube (20).

8. The landing gear according to claim 6 or 7, characterized in that the measuring plate (15) has a concave or bridge-like shape with external support sections (17) facing the spindle bearing plate (21) and a cantilever section (18) arranged between them.

9. The landing gear according to one of claims 3 to 8, characterized in that the thrust bearing (43) rests with its lower bearing section (45) on a spindle stop ring (46) which is firmly connected to the spindle (42).

10. The landing gear according to one of claims 3 to 9, characterized in that the force-measuring element (10) is arranged above the thrust bearing (43) at least partially in its projected surface.

11. The landing gear according to one of claims 1 to 10, characterized in that the force-measuring element (10) is pin-shaped and is inserted into a complementary shaped recess (25) of the support component (15, 21) without play or under tension.

12. The landing gear according to claim 11, characterized in that the pin-shaped force-measuring element (10) is a measuring dowel (11).

13. The landing gear according to claim 11 and 12, characterized in that the recess (25) is a measuring dowel bore (25) formed in the support component (15, 21), into which the measuring dowel (11) is inserted.

14. The landing gear according to claim 13, characterized in that the measuring dowel (11) is mechanically braced in the measuring dowel bore (25).

15. The landing gear according to claim 13 or 14, characterized in that the measuring dowel bore (25) is aligned radially to the spindle (42).

16. The landing gear according to one of claims 1 to 10, characterized in that the force-measuring element (10) is a strain gauge application (12).

17. The landing gear according to claim 16, characterized in that the strain gauge application (12) is applied to an upper surface and / or an underside (22, 23) of the support component (15, 21).

18. The landing gear according to one of claims 6 to 8, characterized in that the force-measuring element (10) is a pressure sensor (19) arranged between the measuring plate (15) and the spindle bearing plate (21).

19. The landing gear according to claim 18 as far as referred to claim 8, characterized in that the pressure sensor (19) is arranged at the cantilever section (18) of the measuring plate (15) in such a way that a force shunt occurs via the pressure sensor (19) onto the spindle bearing plate (21).