This application claims foreign priority benefits under 35 U.S.C. §119(a)-(d) to European patent application number EP 16 167 878.4, filed May 2, 2016, which is incorporated by reference in its entirety.
The disclosure relates to a paving screed.
Paving screeds to be applied in road pavers are known from practical use. They are used for laying road surfaces that can consist for example of bituminous asphalt. Therein, they are used for smoothening and compacting the road surface. As the road surface material is laid in a hot state, paving screeds are sometimes equipped with heating elements that heat up for example screed plates that slide over the material during installation.
As is for example known from the DE 20 219 641 U1, heating elements can be clamped against a screed plate by means of screws. This fastening method comes with the disadvantage that the heating elements might be damaged in case of too strong tightening of the screws.
An object of the disclosure is to provide a paving screed that enables safe but still simple mounting of heating elements by modifications that are as structurally simple as possible.
The paving screed according to the disclosure for a road paver comprises a screed plate, a heating element and a fastening device for pressing the heating element onto the screed plate. The paving screed according to the disclosure is characterized in that the fastening device comprises an actuating member and an elastic element wherein the actuating member is configured to by its operation deflect the elastic element directly or indirectly by a predetermined amount whereby the elastic element applies a predetermined force directly or indirectly onto the heating element and biases said heating element against the screed plate. The elastic element is preferably a linear elastic element. Deflection and/or deflecting shall in particular be understood in the present application as compression or stretching of an elastic element. In general, however, any geometrical modification of the elastic element, which leads to the exercise of a force by the elastic element, shall be accounted for. Preferably, every geometrical modification of the elastic element according to the disclosure can be associated with a specific force, which is exercised by the elastic element, so that a specific geometrical modification reliably leads to the application of a force that is associated to such a modification.
The actuating member can comprise for example a thread and/or a cam. A possible example for an actuating member comprising a thread is a screw. An actuating member having a cam can for example be an eccentric lever. However, any suitable actuating member, whose operation leads to a defined geometrical displacement, is conceivable. Possible variants of the elastic element are the following ones: a spring, e.g., a coil spring, a helical spring, a spring plate, a disc spring, a bending spring a leaf spring and/or a torsion spring.
It is advantageous for the fastening device to have in addition an alignment aid that is configured to align the actuating member to an engagement location. As elastic elements can evade into undesired directions due to their elasticity and depending on the contact point of a structure acting on them, the alignment of the actuating member with an engagement location intended for this purpose can be particularly important. Depending on the design of the fastening device, the engagement location can be situated for example on the elastic element. However, it is also possible for the engagement location, to which the actuating member will be aligned by the alignment aid, to be situated on a further component, for example if the elastic element is deflected indirectly by a predetermined amount through operation of the actuating member. Any appropriate types of guidings are conceivable as alignment aids.
It is expedient for the amount by which the elastic element can be deflected by the actuating member to be limited to the predetermined amount. This way, operating errors can be avoided as there is no possibility for the elastic element to be deflected by a too large amount. For the case of the actuating member being a screw, for example the thread length is a suitable parameter to limit the amount as desired. Also the length from the beginning of the thread to the head is a suitable parameter to limit the amount by which the elastic element can be deflected by the actuating member. In case of actuating members with a cam, said cam can be formed in a way that the maximum deflection corresponds to the predetermined amount in case of any operation. It is particularly advantageous for the actuating member to be only movable in a direction that is opposite to the initial actuation direction upon achieving the predetermined amount.
It can be expedient to provide a positioning aid that is configured to arrange and/or to hold the heating element in a predetermined position. Such a positioning aid can for example be configured to guide the heating element on the screed plate when it is arranged in the position intended for this purpose and therefore to facilitate correct mounting for the operator. The positioning aid can also be configured to hold the heating element in the predetermined position and to prevent for example that it moves out of this position due to vibrations. Different click-on connections, snap-lock connections, guidings and/or end stops are possible for this purpose.
In addition, it can be advantageous for the fastening device to comprise a clamping device that transfers the force exercised through the elastic element to the heating element. This is in particular advantageous in cases where the form of the heating element and the form of the elastic element deviate from one another. The clamping device can for example be adapted to the form of the heating element or have one or multiple contact points for the elastic element or for further components actuated by said elastic element. The clamping device can for example have a clamping plate.
In a further variant, the fastening device can have a clamping device that transfers the force exercised by the elastic element to the heating element and on which a positioning aid is provided that is configured to arrange and/or to hold the heating element in a position. In this variant, the functions of the previously described clamping device and the equally previously described positioning aid are provided in one and the same component and/or in one and the same module so that their advantages are consequently combined.
It is conceivable that a clamping device positioning aid is provided, which is configured in a way so as to arrange and/or to hold the clamping device in a predetermined position. The clamping device positioning aid can have similar functionalities and/or structures as the previously described positioning aid for the heating element.
It can be advantageous if a magnetic element is provided, which is configured to mount the heating element on the screed plate by magnetic force or to arrange and/or to hold the heating element in a predetermined position. The magnetic element can for example have an electromagnet and/or a permanent magnet. Besides and/or in addition, the magnetic element can be provided as a positioning aid.
It is also conceivable to provide a hook-and-loop fastener that is configured to mount the heating element on the screed plate or to arrange and/or to hold the heating element in a predetermined position.
In a further variant, the heating element can be arranged between the screed plate and a clamping element, in particular, a clamping plate, wherein the screed plate and the clamping plate can be connected to tension springs that can be biased by the arrangement of the heating element between the clamping element and the screed plate and thereby press the heating element onto the screed plate.
The disclosure also relates to a road paver that comprises a tractor and a paving screed of the previously described type.
In addition, the disclosure also relates to a construction machine with an asphalt recycling vehicle and a paving screed of the type described before.
Fastening of heating elements on screed plates can also be based on other operating principles. It is for example possible that a heating element can be fastened on a screed plate by magnetic forces, for example applied by permanent magnets or electromagnets, without the fastening device according to the disclosure. Also, fastening without the fastening device according to the disclosure is conceivable by means of a Hook-and-loop fastener.
Also fastening types in which a heating element is disposed between the screed plate and a clamping element, e.g., a clamping plate, are possible, wherein the screed plate and the clamping element are connected to tension springs that are biased by the arrangement of the heating element between the clamping element and the screed plate and consequently press the heating element onto the screed plate. Also this fastening type can be provided without the fastening device according to the disclosure.
In the following, embodiments according to the disclosure will be explained in greater detail with reference to the attached drawings.
As required, detailed embodiments are disclosed herein. However, it is to be understood that the disclosed embodiments are merely exemplary and that various and alternative forms may be employed. The figures are not necessarily to scale. Some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art.
The paving screed 4 is used in particular, for smoothing the paving material.
The heating element 11 can be pressed onto the screed plate 9 by means of a fastening device 12. In the present embodiment, the fastening device 12 comprises an actuating member 13 in form of a screw 13a, an elastic element 14 in form of a bending plate 14a, an alignment aid 15 and a clamping device 16 in form of a clamping plate 16. By operating the actuating member 13, in the present embodiment by means of screwing the screw 13a into a thread provided in the frame 10, the elastic element 14, i.e., the bending plate 14a in the present embodiment, is deflect-ed. Through the connection of the elastic element 14, i.e., of the bending plate 14 in the present embodiment, to the clamping device 16, i.e., the clamping plate 16 in the present embodiment, a force can be applied on the heating element 11 so that the heating element 11 can be biased against the screed plate 9. The fastening device 12 can thereby be designed in a way that the clamping device 16 acts onto the heating element 11 with a predetermined force. This force can be chosen in a way that a damage of all components of the smoothing unit 8 and in particular, a damage of the heating element 11 is prevented reliably whereas safe clamping of the heating element 11 is still ensured. The predetermined force that should be applied to the heating element 11 can be associated to a predetermined deflection of the elastic element 14, i.e., of the bending plate 14a in the present embodiment. Accordingly, the fastening device 12 can be designed in a way that this predetermined deflection is not exceeded during operation of the actuating member 13, i.e., in the present embodiment through screwing in of the screw 13a. In the present embodiment, for example the length of the screw 13a can be chosen in a way that a screw head 17 of the screw 13a hits the frame 10 exactly when the screw 13a has deflected the bending plate 14 by the predetermined amount.
In the embodiment shown in
The cam 13b is shown in the present embodiment as a body with an oval cross-section that is rotatable around a rotary axis 20. Even if the boundary of the cross-section of the cam 13b in the present embodiment is similar to an ellipse with a major and a minor axis, oval as used previously shall be understood in the mathematical sense, i.e., as a closed convex curve, which is continuously differentiable twice, in a plane. Event this broad description, however, shall only be regarded as exemplary for the form of the cam. In the presently described example of an elliptical cross-section of the cam 13b, the length of the semimaj or-axis of the ellipse corresponds to the predetermined amount by which the elastic elements 14, 14b, 14c should be deflected. Therefore, the deflection of the elastic elements 14, 14b, 14c is limited to this predetermined amount. In the pre-sent embodiment, the rotary axis 20 around which the cam 13b is rotated is perpendicular to the deflection direction of the elastic elements 14, 14b, 14c. However, it is equally possible that the rotary axis 20 is parallel to the deflection direction in any other direction.
In addition, a clamping device positioning aid 22 is provided in
Further embodiments for snap-in bodies 23 are displayed in the
The following paragraph describes the case in which
The following paragraph, it shall be the assumed that
The previously described embodiments represent different possible variants of the disclosure and of features of the disclosure. They are described in different combinations. However, the skilled reader will recognize that the disclosure is not limited to the combinations of features shown in the exemplary embodiments. Rather, all described features and embodiments of said features can be combined in any possible way. In particular, different variants of the same functionality can be substituted at random among the embodiments.
While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms according to the disclosure. In that regard, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the disclosure. Additionally, the features of various implementing embodiments may be combined to form further embodiments according to the invention.
Number | Date | Country | Kind |
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16167878.4 | May 2016 | EP | regional |