How to adjust the temperature of the screed plate of a road paving machine's screed.

Abstract

To provide a method of heating a paving screed that reduces the number of constituent features to be used so as to reduce the possibility of malfunction.SOLUTION: A method of adjusting temperature of a screed plate of a paving screed (101) of a road paving machine (100), the paving screed being provided with a heating element (113) for heating the screed plate (111) and a temperature sensor (114) for measuring the temperature of the screed plate for a certain period of time, and the road paving machine being provided with a control unit (130) for adjusting the target temperature of the heating element (113) in accordance with the temperature profile of the screed plate.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for adjusting the temperature of the screed plate of a road paving machine described in the preamble of claim 1, a method for adjusting the temperature of the screed plate of a road paving machine described in the preamble of claim 5, and a road paving machine for laying material on a subgrade. [Background technology]

[0002] Road paving machines and the corresponding methods for regulating the temperatures of the paving screed and screed plate, which are typically equipped with them, are well known in the prior art. Such methods are usually used to ensure the temperature of the screed plate, thereby ensuring that the paving material for the road is laid properly while preventing the material from overheating.

[0003] For example, DE102018127353A1 discloses a system for controlling the heating of a screed plate, in which the temperature of the material along the feed path from the material hopper to the pavement screed is measured. Using this temperature, which corresponds to the actual temperature of the pavement material, as a reference, the control unit operates the heater while comparing it with a temperature value measured by a separate temperature sensor for the screed plate, thereby maintaining the temperature of the screed plate within a temperature variation range relative to a separately estimated pavement material temperature.

[0004] The method disclosed in this document enables the estimation of pavement material temperature and, consequently, the precise control of the heater control device within a closed loop by incorporating various sensors. However, the need to use so many sensors increases the likelihood of malfunction if one or more sensors fail. Furthermore, the sensors that measure the pavement material temperature are independent of the sensors that measure the screed plate temperature, and since both temperature measurements are required for operation, these sensors lack redundancy. Therefore, if even one of each type of sensor fails, the method cannot be performed.

[0005] Furthermore, because control units must receive and process a very large number of inputs, they have many interfaces, and therefore are complex. [Overview of the Initiative]

[0006] Based on known prior art, the technical challenge to be addressed appears to be a method for heating the screed plate of a road paving machine's screed, which aims to reduce the number of components used while minimizing the possibility of malfunction.

[0007] This problem is solved by the method described in claim 1, the method described in claim 5, and the road paving machine described in claim 11. Other preferred developments of the present invention are specified in the dependent claims.

[0008] The method for adjusting the temperature of the screed plate of a road paving machine according to the present invention is characterized in that the road paving screed includes a heating element for heating the screed plate and a temperature sensor for measuring the temperature of the screed plate over a certain time interval, and the road paving machine includes a control unit that adjusts the target temperature of the heating element according to the time profile of the temperature of the screed plate.

[0009] Preferably, this method does not require the use of a sensor that directly measures the temperature of the material applied to the subgrade by the paving screed of a road (road surface) paving machine. This means that there is no need to have a sensor specially configured to measure the temperature of the material. The present invention envisions a system in which the temperature characteristics of the screed plate change in accordance with the material temperature due to heat exchange between the screed plate and the material heated by the screed plate, thereby making it possible to derive a determination regarding the material temperature as long as the temperature of the screed plate is known. Therefore, the desired target temperature of the screed plate, and consequently the heating force, can be adjusted in a preferred manner without the need to accurately determine the temperature of the material, resulting in a reduction in the number of required components.

[0010] According to one embodiment, the screed plate may be heated to a first temperature by a heating element, after which the heating element may be stopped, the screed plate comes into contact with the material laid on the subgrade, and after the heating element is stopped, the material temperature is determined by a control unit based on the time profile of the screed plate temperature, and the target temperature is determined according to the material temperature.

[0011] This embodiment utilizes the fact that when a screed plate is heated to a high temperature, it cools down upon contact with the material. Since this cooling occurs according to known physical laws, if the temperature of the screed plate is known, it becomes possible to determine the temperature of the material. Therefore, even in this case, the temperature of the material does not need to be determined using sensors or other means.

[0012] According to another embodiment, the heating element may heat the screed plate to a heating temperature lower than the material temperature of the material laid on the roadbed. Subsequently, the screed plate may contact the material while the heating element is heating the screed plate. With the screed plate being heated by the heating element and in contact with the material, the material temperature is determined by the control unit based on the time profile of the temperature of the screed plate, and the target temperature is determined according to the material temperature.

[0013] In this embodiment, it is possible to clarify in the time profile of the temperature of the screed plate the point that no new heat transfer from the material to the screed plate occurs because the temperature of the screed plate is higher than the temperature of the material. This enables a determination regarding the temperature of the material, and thereby, in turn, enables the determination of the target temperature of the heater even when the material temperature is not precisely known.

[0014] According to one embodiment, the control unit determines the target temperature from the material temperature by raising the material temperature by a differential value. This ensures that the temperature of the screed plate always exceeds the determined material temperature. This is particularly important when the heating of the screed operates in a periodic mode. Thus, the screed plate is not heated periodically. In this case, the control unit stops the heating element when the target temperature of the screed plate is reached and supplies power to the heating element again after the screed plate has cooled down to the material temperature.

[0015] Since the differential value can be regarded as an "offset", this can be utilized to, for example, maintain the temperature of the screed always higher than or at least equal to the material temperature as much as possible. This prevents unwanted adhesion of the paving material.

[0016] An alternative method of adjusting the temperature of the screed plate of a paving screed of a road paver is characterized in that the paving screed comprises a heating element for heating the screed plate, the road paver comprises a control unit, and the control unit determines a target temperature of the screed plate taking into account the operating parameters of the road paver and / or the surroundings and / or the road surface.

[0017] The term "operating parameters" of the road paver, the surroundings or the road surface refers to values that have already been determined during the normal operation of the road paver, such as the road surface temperature, the temperature of the material at the time of input, etc. For example, when the road is scanned behind the road paver, it is customary to record the surface temperature of the road on which the material is being laid, and in particular the temperature of the material laid on the ground. Usually, appropriate means are provided regardless of the sensors of the paving screed. In order to determine the required temperature of the screed plate, for example, the temperature of the material before laying and while the material is in contact with the screed plate of the paving screed is taken into account, taking into account that it is slightly higher than the temperature of the material that has already been laid. By taking this into account, it becomes possible to utilize the temperature determined for the laid material, which is measured during the scan. In particular, for the sake of simplicity of calculation, here it can be assumed that the temperature of the laid material (determined by the scan) is equal to the material temperature T in the area of the paving screed, especially when in contact with the screed plate. mat And the target temperature of the screed plate of the paving screed can be defined as the value T mat +ΔT, where ΔT > 0 K can be the temperature offset set to prevent the material from adhering to the paving screed.

[0018] Using each operating parameter to determine the target temperature makes it possible to provide a smaller-scale system with respect to hardware requirements, since there is no need to equip it with new sensors.

[0019] Taking operating parameters into account, in contrast to the embodiments described above, may allow for the elimination of a wider range of calculations. However, it should be understood here that this means it may be possible to determine the material temperature directly from the values ​​described as "operating parameters" throughout the process, and then determine the target temperature of the screed plate based on this (for example, by adding a temperature offset as described above).

[0020] According to one embodiment, the road surface operating parameters include the surface temperature of the road surface determined during the temperature scan. The surface temperature of the road surface may be measured particularly behind the vehicle and in the direction of the vehicle's movement, thus indicating the temperature of the newly laid material. This temperature is as already described above, and thus the material temperature can be determined (within certain limits or with certain precision).

[0021] This enables a preferred modification of this embodiment, and assuming that the temperature remains constant from contact with the screed plate until measurement at the rear of the vehicle, it becomes possible to directly determine the material temperature, thus making it economically possible to directly determine the required computational power.

[0022] The operating parameters of a road paving machine include information about the material temperature at the time of input, and this information may also be input into the control unit.

[0023] When a material, such as asphalt, is loaded onto a truck, it is usually already heated to a specific temperature. This temperature is specified within a loading range and can be provided to the control unit, for example, by manually entering it into the control unit by the operator or by scanning loading instructions. This is also an "operating parameter" because it identifies the state of the material at the time of loading. If the control unit knows this temperature, the heating force of the heating element can be controlled so that the temperature of the screed plate is preferably within a range around the material temperature, and / or, knowing this temperature, it will be possible to estimate the temperature the material will still have when it reaches the screed plate. As already explained above, this material temperature can be offset, i.e., ΔT>0K, to ensure that the material does not adhere to the screed plate.

[0024] The surrounding operating parameters may also include ambient temperature.

[0025] The ambient temperature, i.e., the temperature of the air, may, for example, be incorporated into the determination of the target temperature of the screed plate, and since this temperature is usually already determined by the road paving machine, no new components are required.

[0026] According to one embodiment, the control unit determines the material temperature of the material that will reach the screed plate from the material temperature at the time of input and the ambient temperature, and the control unit adjusts the target temperature according to the determined material temperature.

[0027] This combines the embodiments already described in a preferred manner.

[0028] To determine the target temperature, the control unit may utilize information stored in its memory.

[0029] These information items may, for example, relate to the temperature required for a particular material, and they may differ between one material and the next, thus providing the control unit with the necessary information.

[0030] A road paving machine according to the present invention, used for laying material on a subgrade, comprises a material hopper, a paving screed, and a feeding system for feeding material from the material hopper to the paving screed, wherein the paving screed is configured to lay material on a subgrade, and the paving screed comprises a screed plate and a heating element for heating the screed plate, and the road paving machine comprises a temperature sensor for measuring the temperature of the screed plate and a control unit configured to control the temperature of the heating element, and the road paving machine is configured to perform a method according to one of the embodiments described above.

[0031] The road paving machine can realize the preferred features of the method described in the above-mentioned embodiment. [Brief explanation of the drawing]

[0032] [Figure 1] This is a schematic diagram of a road paving machine according to one embodiment. [Figure 2] This is a flowchart of a method according to one embodiment. [Figure 3] This is a flowchart of a method according to another embodiment. [Figure 4] This is a flowchart of another embodiment. [Modes for carrying out the invention]

[0033] Figure 1 shows a road paving machine 100 according to one embodiment of the present invention. In this embodiment, the road paving machine is configured to substantially comprise a vehicle portion (also referred to as a tractor unit) 102 and a paving screed 101.

[0034] In the embodiments shown herein, the vehicle portion 102 includes, in particular, a driver's cab 124 where, for example, the driver of the road paving machine 100 can sit. The driver's cab may also be provided with operating elements, for example, so that the driver can operate the road paving machine.

[0035] Furthermore, the road paving machine 100 is equipped with a material hopper 122, also called a material container, in the vehicle section 102. The materials 123, such as asphalt to be laid on the road, are stored in the hopper so that they can be used for further transport or use elsewhere.

[0036] Not described in detail in this specification is the loading system, which is configured in the vehicle section 102 and loads material from the material hopper 122 (or material container) into the pavement screed 101.

[0037] The paving screed 101 is connected to the vehicle section 102 via a connection (usually a towing bar) 125, which is widely known in the prior art (the connection may be mounted on both sides of the vehicle section 102), and may be supported in a specific orientation relative to the subgrade 103 on which the road paving machine runs, for example, via one or more leveling cylinders (not shown herein).

[0038] Furthermore, the vehicle section 102 typically includes a drive unit 121, which may be configured in the form of a chain drive, for example, so that the road paving machine 100 can move on the roadbed 103.

[0039] The road paving machine 100 is typically equipped with an auger 112 in front of the paving screed 101, and this auger is used to apply material to the subgrade 103. Since this auger belongs to the vehicle section 102, it is not structurally part of the subsequent paving screed. Along with this, the paving screed comprises one or more screed plates 111, and the paving screed, by its own weight, has the effect of smoothing and compressing the material applied to the subgrade 103.

[0040] All parts of the road paving machine 100 described so far may be provided in this form or a modified form, and should be understood as merely examples of the present invention. According to the present invention, the road paving machine 100 comprises at least one paving screed having a screed plate and a control unit.

[0041] To prevent material from adhering to the screed plate and consequently negatively affecting the paving results, the screed plate is connected to a heating element 113 according to the present invention. This heating element is configured to heat the screed plate and to be intentionally adjusted to a specific temperature by supplying heat in particular.

[0042] Furthermore, the screed plate 111 is connected to a temperature sensor 114, which can measure the temperature of the screed plate.

[0043] Since the heating element typically supplies heat to the screed plate, the temperature of the screed plate cannot be determined solely based on the amount of heat that is thought to be known. This is because the temperature is also affected by other factors, such as heat transfer from the screed plate to the material applied to the subgrade 103. If this material has already cooled substantially, for example, through contact with the subgrade 103 or the surrounding air, or at least is at a temperature lower than the temperature of the screed plate, then with a certain amount of heat supplied, the screed plate can reach a variety of temperatures depending on the temperature of the material and the associated heat transfer from the screed plate to the material, or vice versa. However, in order to effectively prevent the material from adhering to the screed plate, the temperature of the screed plate must always be higher than, or at least the same as, the temperature of the material.

[0044] For these reasons, a temperature sensor 114 is provided to measure the temperature of the screed plate. This temperature sensor may be, for example, an electrically operated sensor or any suitable temperature sensor.

[0045] According to the present invention, a control unit 130 is additionally provided. The control unit is located in the vehicle section 102, for illustrative purposes only herein, and is connected to both the sensor 114 and the heating element (e.g., by cable and / or by wireless communication means) for data exchange.

[0046] According to the present invention, in some embodiments, the temperature sensor 114 may measure the temperature of the screed plate over a specific period of time (with the heating element 113 switched on or off), and the control unit 130 may later (particularly after the temperature of the material 131 has been determined) control the heating element 113 so that the screed plate is heated to a desired target temperature and, in particular, maintained at the target temperature (for example, if the heating unit 113 operates periodically, an allowable temperature range may be considered).

[0047] Alternatively, the control unit may take into account one or more (additional) operating parameters considered when determining the target temperature of the screed plate, such as ambient temperature, the temperature of the material 123 at the time of input, or the surface temperature of the road surface.

[0048] Particularly preferred are embodiments in which, in order to carry out the method disclosed by the present invention according to one of the embodiments not yet described, it is not necessary to modify an existing road paving machine with respect to the sensors used. In particular, in order to implement the method according to the present invention, it is intended to provide the possibility of modifying a road paving machine even without a sensor to measure the temperature of the material itself by providing the control unit 130 with an appropriate control program.

[0049] A preferred embodiment of this method is shown as a flowchart in Figures 2 to 4 and will be described in more detail below.

[0050] Figure 2 shows an embodiment in which the determination of the material temperature is derived from the cooling behavior of the screed plate.

[0051] This method begins with activating a heating element to heat the screed plate. This is preferably done before any material is laid on the subgrade or comes into contact with the screed plate. In step 202, the screed plate is first heated to a temperature T1 higher than the temperature of the material to be laid on the subgrade. However, the temperature T1 of the material is higher than the temperature of the material. mat This is not yet known in step 202. Therefore, the screed plate is heated to a temperature T at least higher than the maximum mixing temperature (material temperature) of approximately 180°C. 1、 In other words, the process can be carried out until T1 = 200°C. This means that the temperature T1 of the screed plate in process 202 is equal to the material temperature T, regardless of the actual material temperature. mat It will definitely be higher than that.

[0052] In step 203, the heating element is stopped so that when temperature T1 is reached, no further heat is supplied from the heating element to the screed plate, and the screed plate begins to cool down.

[0053] However, since the material has already been poured into the pavement screed 101 at this point, the material also comes into contact with the screed plate, and the screed plate dissipates heat into the material. In this way, the screed plate cools down.

[0054] Material temperature T mat If we simply assume that remains constant (i.e., that the material can be considered a heat storage object with a constant temperature), then the following applies to the change in heat Q transferred to the material over time t:

[0055]

number

[0056] However, the following applies to heat flow over any given time period:

[0057]

number

[0058] In the formula, T1 and T2 are the temperatures of the objects involved in heat exchange.

[0059] Finally, this has the effect that the following applies with respect to the temperature of the screen plate as a function of time.

Number

[0060] The constant B is not important here, but is conditioned by the characteristics of the material, such as the characteristics of the screen plate (especially its size and contact area with the mixture) and the characteristics of the material and the mixture respectively.

[0061] Thereby, the temperature T of the material mat can be at least roughly determined.

[0062] For this purpose, the temperature of the screen plate is measured over a specific time Δt. Next, using the characteristics of the curve, a determination can be made regarding the material temperature T mat which is calculated later in step 205.

[0063] Once this temperature is known, in the next step 206, the desired target temperature T of the screen plate soll can be determined. This target temperature is used to control the heating element in a later step 207.

[0064] In step 206, the determination of the target temperature T soll is that the temperature of the screen plate is at least slightly higher than the material, T soll >T matIt can be executed in a way that allows selection. For example, the temperature of the screed plate may be about 10K higher than the actual material temperature. When determining or confirming the target temperature of the screed plate in step 206, a temperature range may be specified as the "target temperature". For example, the screed plate temperature may not be adjusted to a specific temperature value, and the (maximum) target temperature T soll From the actual material temperature T mat It is possible that the temperature range is adjusted to a certain extent so that the temperature of the screed plate will be within this range anyway.

[0065] In step 207, the control unit then controls the heating elements (for example, by supplying some power or by activating and / or deactivating the heating elements) so that the temperature of the screed plate matches the target temperature or is within a specific temperature range of the screed plate. This prevents the mixture from adhering to the screed plate.

[0066] This is preferably carried out within the framework of a closed-loop control cycle known in the prior art. In this closed-loop control cycle, the control unit controls the heating element 113 based on the measured temperature value of the screed plate (a temperature sensor 114 may be used as an example for this purpose), the temperature is then measured again by the temperature sensor 114, the heating element is controlled again, and so on.

[0067] This makes it possible to reliably control the temperature of the screed plate, particularly by setting boundary conditions that maintain the temperature within a specific temperature range between the maximum target temperature and the material temperature.

[0068] Figure 2 illustrates an embodiment in which the initial temperature of the screed plate is higher than the temperature of the material.

[0069] However, it is conceivable that in some embodiments, the initial temperature (when the temperature measurement of the screed plate over a specific time interval is initiated) may be lower than the temperature of the material.

[0070] Here, an embodiment of this type will be explained in Figure 3.

[0071] In the embodiment shown in Figure 3, the heating element operates first in step 301, just as in step 201.

[0072] However, the heating stage of this screed plate is at temperature T2 <T mat The process is only performed up to a certain point, after which the temperature of the screed plate T over a specific time interval Δt is reached in step 303. G The measurement will begin.

[0073] In this situation, the material can be considered a high-temperature heat source, and the heating element can be considered a second constant-temperature heat source, the screed plate. In this case, the temperature of the heating element and the heat it generates must exceed the temperature of the material, and in particular, the temperature of the heating element must be higher than that of the material.

[0074] Similar to the calculation above, each additional step that adds heat transfer performed by both the material and the heating element results in a time dependence of temperature. However, in this case,

[0075]

number

[0076] In this relationship, it is preferable to be able to utilize the fact that a change in sign occurs immediately when T1 changes from a temperature lower than T2 to a temperature higher than T2. ​​In the embodiment described here, the following applies to the thermal change over time.

[0077]

number

[0078] T mat This refers to the material temperature, T His the temperature of the heating element, and T is the temperature of the screed plate over time. The amounts of a and b are constant. Temperature T mat and T H In this case, it can be considered constant with respect to time.

[0079] T mat <T H Therefore, the temperature T of the screed plate G The material temperature T mat Beyond a certain point, problems immediately arise in the time profile of the heat energy (especially its derivative). This is because, from that moment onward, the material stops releasing heat to the screed plate, while the screed plate begins releasing heat to the material.

[0080] From this equation, if a jump is detected in the derivative at this point, the material temperature T can be determined by measuring the temperature of the screed plate over a specific period of time. mat This allows us to determine the material temperature T mat The target temperature T of the screed plate soll This defines the parameters, and accordingly, the output variables can be reconfigured in steps 304-306 to control the heating elements by the control unit.

[0081] The operation process in steps 304-306 corresponds to the operation process in steps 205-207. Therefore, the equation solved according to Figure 3 is used in place of the equation shown for Figure 2.

[0082] However, the remaining operating steps are the same here. In particular, in this case, to prevent the material from adhering to the screed plate, the temperature of the screed plate is set to the material temperature T. mat In some cases, the heating element may be controlled in an appropriate manner to achieve a target temperature that is higher than or at least within the range of the maximum target temperature to the material temperature.

[0083] Even in this case, a suitable control loop may be used to induce closed-loop temperature control by controlling the heating element so that the temperature remains within the desired range.

[0084] The embodiments in Figures 2 and 3 may be used competitively. For example, if the material temperature is unknown, the screed plate may first be heated to temperature T0. Then, if the temperature drops as a reaction occurs after the heating element is stopped, the temperature is T0 > T mat This can be clarified, and the method shown in Figure 2 can be implemented. If it is found that the temperature of the screed plate continues to rise as a reaction when the heating element is stopped, the temperature is T0 <T mat Therefore, the method shown in Figure 3 can be implemented.

[0085] In another embodiment shown in Figure 4, which is an alternative to the method described above, the material temperature in the screed plate region is determined based on at least one operating parameter and / or one operating parameter representing ambient characteristics and / or one operating parameter representing road surface characteristics in order to perform control of the heating element.

[0086] To that end, Figure 4 initially shows two methods, which are interchangeable or can be used in parallel. In the first method, a road surface scan is performed in step 401 after the material has been laid. A method corresponding to this is a known one, which includes, among other things, the measurement of the subgrade temperature, thereby from the scan of the road surface 401 performed behind the road paving machine, the road surface temperature T in step 403. S This can be determined. In the final analysis, this road surface temperature is the temperature of the laid material.

[0087] Alternatively, or in addition to this, the control unit may, for example, access a temperature sensor typically provided for measuring ambient temperature, thereby measuring the ambient temperature at a particular moment and / or obtaining a value indicating it.

[0088] Next, the road surface temperature T S The ambient temperature, or either of these, is used to determine the material temperature T obtained in step 404 when the material is fed into the road paving machine. mat This value can be matched, but it is not mandatory, and the material temperature T at the time of input is also important. matIt is sufficient to consider only this in a different way. Alternatively, the road surface temperature measured in process 401 is the material temperature T mat By assuming that it is equal to, the road surface temperature T S material temperature T mat It can also be used as an indicator.

[0089] The material temperature at the time of loading may be entered, for example, into a loading instruction sheet, and then provided to the control unit by the operator via an appropriate input unit, such as a keyboard. Alternatively, or in addition to the above, the temperature in question may also be read (without error) using a barcode scanner or QR code® scanner, which has the ability to detect each code listed on the loading instruction sheet, in which the temperature is encoded and available for use by the control unit.

[0090] Next, from the material temperature at the time the material is introduced (into the material container of the road paving machine), the material temperature in the screed plate region can be estimated. Road surface temperature T from process 403 S If the ambient temperature from process 402 is available, this estimation can be made with high accuracy, as the cooling behavior of the material can be revealed with relatively precise terms. Alternatively, it is possible to assume that the input temperature is, in principle, equivalent to the temperature of the material as it passes through the screed plate. Thus, it is sufficient to know the material temperature and assume that the target temperature is equal to or slightly higher than the material temperature.

[0091] If the material temperature at the time of input is unknown, i.e., if process 404 cannot be performed because the information is unavailable or is not intended to be performed, a “standard value” assumed as the material temperature at the time of input can be used for calculations. Nevertheless, the ambient temperature from process 402 and / or the road surface temperature T from process 403 can be used. s Taking this into consideration, it becomes possible to make an approximate determination regarding the material temperature in the screed plate region.

[0092] This material temperature T can be determined in step 405 according to the embodiment described immediately above. mat Based on this, the next step is to determine the target temperature T of the screed plate. soll This is determined in step 406. The target temperature can be specified, in the same way as in the embodiments described above, such that it is higher than the estimated material temperature (e.g., 10K, 15K, or 20K), and / or the temperature of the screed plate is between the maximum target temperature and the estimated material temperature.

[0093] Based on this target temperature or a range corresponding to the temperature of the screed plate, the heating element is then controlled by the control unit in step 407 according to the control loop already described.

[0094] In all of the embodiments described above, further information may be taken into consideration to determine the target temperature of the heating element. For example, to determine the target temperature, the type of material layer applied to the subgrade, such as a binder layer or a surface layer, may be taken into consideration, and the target temperature can be adjusted accordingly. This is because different materials may create different requirements regarding the maximum heat supplied to them, or they should not be heated beyond a critical temperature. Therefore, in this embodiment, it is preferable to adjust the temperature to be slightly higher than the estimated material temperature in order to avoid the material adhering to the screed plate and to avoid overheating of the material. Such information can be made available to the control unit via memory, which can be located in the control unit. This information is stored in this memory in the form of one or more data structures, such as a table, and can be retrieved by the control unit when determining the target temperature.

[0095] For example, the formulas of the individual mixtures may be specified as relevant information, or the target temperature of the screed plate may be determined by specifying the maximum temperature range over which the temperature of the mixtures in the screed plate region can change.

[0096] Although the embodiments shown in Figures 2 to 4 are described in a manner that is substantially interchangeable with each other, at least the embodiments in Figures 2 and 3 may be combined with the embodiment in Figure 4.

[0097] In the embodiment shown in Figure 4, the final result allows for specifying a target temperature for the screed plate and then controlling the heating element later, without having to measure the temperature of the screed plate to achieve the desired temperature.

[0098] If the temperature sensor that measures the screed plate temperature according to the embodiments of Figures 2 and 3 fails, the method described in Figure 4 may be used without a control loop. In this case, for example, the control unit uses information stored in memory and information about the amount of heat required to heat the screed plate to a specific temperature to control the heating element 113 in an appropriate manner without a downstream control loop that can verify whether that temperature has actually been reached (see Figure 1). The heating element may be controlled to output an approximate amount of heat that is usually sufficient to adjust the temperature of the screed plate to, for example, 155°C (likewise, any other value relative to the target temperature may be used). Therefore, in order to prevent material from adhering to the screed plate, if the temperature sensor fails, the target temperature of the screed plate can be controlled at least roughly, i.e., less precisely than in the embodiments of Figures 2 and 3. Thus, the functionality of the road paving machine can be maintained by combining the embodiments in this way, even if any temperature sensors that may be present fail.

Claims

1. A method for adjusting the temperature of a screed plate of a road paving machine, comprising: heating the screed plate with a heating element of the road paving screed; measuring the temperature of the screed plate over a certain time interval using a temperature sensor of the screed plate to obtain a time profile of the screed plate temperature over time intervals; obtaining the material temperature of the material in contact with the screed plate according to the time profile of the screed plate temperature using the control unit of the road paving machine; and adjusting the target temperature of the heating element to a temperature higher than the material temperature using the control unit. A method characterized in that the heating element heats the screed plate to a heating temperature lower than the material temperature of the material laid on the subgrade, and thereafter the screed plate comes into contact with the material while the heating element is heating the screed plate, and while the screed plate is heated by the heating element and in contact with the material, the material temperature is determined by the control unit based on the time profile of the temperature of the screed plate, and the target temperature is determined according to the material temperature.

2. The method according to claim 1, wherein the screed plate is heated to a first temperature by the heating element, thereafter the heating element is stopped, the screed plate comes into contact with the material laid on the subgrade, and after the heating element is stopped, the material temperature is determined by the control unit based on the time profile of the temperature of the screed plate, and the target temperature is determined according to the material temperature.

3. The method according to claim 2, wherein the control unit determines the target temperature from the material temperature by raising the material temperature by a difference amount.

4. A method for adjusting the temperature of a screed plate of a road paving machine, characterized in that the screed plate is heated by a heating element of the road paving screed, the control unit of the road paving machine obtains the material temperature of the material in contact with the screed plate according to the time profile of the temperature of the screed plate, a target temperature of the heating element is determined to be higher than the material temperature, taking into account the operating parameters of the road paving machine and / or the surroundings and / or the road surface, the control unit uses information stored in the memory of the control unit to determine the target temperature, the information includes the material temperature at the time of loading, the material temperature is input by an operator via an input unit for providing the material temperature to the control unit, and / or the material temperature is read by a barcode scanner or two-dimensional code scanner that detects a code encoded in a loading instruction sheet and makes available to the control unit.

5. The method according to claim 4, wherein the operating parameters of the subgrade include the surface temperature of the road surface determined during a temperature scan.

6. The method according to claim 4 or 5, wherein the operating parameters of the road paving machine include information about the material temperature at the time of input, and the information is input to the control unit.

7. The method according to any one of claims 4 to 6, wherein the ambient operating parameters include ambient temperature.

8. The method according to claim 6 or 7, wherein the control unit determines the material temperature of the material to reach the screed plate from the material temperature at the time of input and the ambient temperature, and the control unit adjusts the target temperature of the heating element according to the determined material temperature.

9. A road paving machine for laying material on a subgrade, comprising a material hopper, a paving screed, and a feeding system for feeding material from the material hopper to the paving screed, wherein the paving screed is configured to lay the material on the subgrade, the paving screed comprises a screed plate and a heating element for heating the screed plate, the road paving machine comprises a temperature sensor for measuring the temperature of the screed plate and a control unit configured to control the temperature of the heating element, and the road paving machine is configured to perform the method according to any one of claims 1 to 8.

Images