Patent Application
20240125059
This application claims foreign priority benefits under 35 U.S.C. § 119(a)-(d) to European patent application number EP 22201075.3, filed Oct. 12, 2022, which is incorporated by reference in its entirety.
The disclosure relates to a road making machine in the form of a road finishing machine for producing a paving layer, or of a charger vehicle for conveying laying material to a road finishing machine, and to a method for operating a system for heating at least one first component of a road making machine in the form of a road finishing machine for producing a paving layer, or of a charger vehicle for conveying laying material to a road finishing machine.
U.S. Pat. No. 5,096,331 discloses a pre-heating system for primary and finishing screeds in which a pressure drop of a circulating high-pressure liquid caused by an opening leads to a heating of a liquid whereby the screed is heated. U.S. Pat. No. 5,899,630 discloses a heat exchange system which is able to transfer heat from a waste gas system of an asphalt paving machine to the screed of the asphalt paving machine. In DE 198 36 650 A1, the principle of liquid friction for screed heating is used.
Road finishing machines are employed for applying a pavement of mixed laying material or laying material or mixed asphalt material, for example of concrete, bituminous mixed laying material, or asphalt, onto a place, a path, or a road. Such a road finishing machine usually has a material bunker for storing a certain amount of mixed laying material, and a screed fastened to a machine frame of the tractor of the road finishing machine in a height-adjustable manner for compacting and profiling the pavement to be installed. Charger vehicles are used for conveying laying material to road finishing machines and usually include a front-side material bunker and a conveying device by means of which, corresponding to the demand of the road finishing machine, laying material is conveyed from the material bunker to the rear and discharged into the material bunker of the road finishing machine.
To prevent mixed asphalt material from adhering to the screed or screed plates and compacting units (tampers and pressing ledges) of the screed, electrical heating systems are usually integrated in these units of the road finishing machine. There are also other components or working units of a road finishing machine and a charger vehicle and their material bunker and/or conveying system which can also be integrated with an electric heating system. At a performance of the screed heating of, e.g., 10 kW and an operating time of about 50%, around 50 kWh of electric energy are required on a 10-hours working day. This causes considerable energy costs. Furthermore, the electric heating of the working units, e.g., the screed, in electrically driven road making machines results in a higher accumulator capacity being required, for example in the range of 2001 or more. Accordingly, the construction of the road making machine would have to be adapted which in turn causes costs.
It is an object of the disclosure to provide a road making machine in the form of a road finishing machine or a charger vehicle for a road finishing machine with a heating system improved with respect to the above mentioned problems.
The disclosure relates to a road making machine in the form of a road finishing machine for producing a paving layer, or in the form of a charger vehicle for conveying laying material to a road finishing machine, wherein the road making machine includes a tractor, a primary drive source, a chassis, and a material bunker and a heating system. According to the disclosure, the heating system includes a heat pump. A heat pump can be a machine which takes up thermal energy at a low temperature and transfers it as usable heat—together with the driving energy—to a system or apparatus to be heated at a higher temperature. The advantage of a heating system with a heat pump is the improvement of the efficiency or thermal efficiency of the heating system. This can lead to a reduction of the energy costs for the heating system. A further advantage of the disclosure for an electrically driven road making machine is that the accumulator capacity required for the heating, and accordingly the installation space required for the accumulator, do not have to be enlarged. The heat pump can be, e.g., an air-fluid heat pump or a fluid-fluid heat pump. The primary drive source can, e.g., be an electric motor, a hydrogen engine, an internal combustion engine and/or a hybrid engine. To improve efficiency, a heat pump could be driven, e.g., by the electric energy by means of an electric motor or generator, operated by an internal combustion engine. Thereby, e.g., an efficiency of the screed heating of about 300-500% could be reached.
The heat pump can include at least one evaporator, one liquefier, one compressor, and/or one expansion valve. In a circuit of the heat pump, a working medium can be circulated, for example. The evaporator can be configured to withdraw heat from ambient air or a heat source of the road making machine and to evaporate a working medium or liquid located within the evaporator and bring it into a gaseous state. The compressor can be configured to compress the gaseous working medium and thereby increase the temperature level and the pressure level of the gaseous working medium. The liquefier can be configured to condense the gaseous working medium so that it dissipates its heat to the environment. By the expansion valve, the pressure level of the liquefied working medium can be reduced whereby the working medium cools down again. The heat pump or the compressor and/or the expansion valve of the heat pump can be operated with a drive or with a motor, respectively. The compressor and the motor can be designed separately or as a unit. The evaporator, the liquefier, the compressor and the expansion valve can be arranged in a housing of the heat pump. The motor can be arranged in the housing of the heat pump. The heat pump or the motor of the heat pump, respectively, can be electrically connected with an energy storage (e.g., battery) of the road making machine or with a current inverter connected with the energy storage. The energy storage can be chargeable with an external power source. The energy storage can electrically feed a primary drive source of the road making machine. The power source of the heat pump can, e.g., be an electric generator driven by the primary drive source, or a battery chargeable by the generator.
It is an advantage for the heating system to be configured to utilize heat from ambient air and/or from a heat source of the road making machine for heat recovery. Ambient air can be supplied into the heat pump by means of an air heat exchanger. As a heat source, waste heat of a cooling system of the road making machine can be provided, for example. The cooling system can be provided for cooling an energy storage (e.g., battery) or the accumulator of the road making machine, respectively, or a primary energy source of the road making machine. The cooling system can include a cooler or a heat exchanger. A working medium or a heat transfer medium of the heating system can flow through the cooler to transfer the waste heat of the energy storage or another apparatus of the road making machine to the heat pump.
It is particularly energy-efficient for the system to be configured to heat at least one first component of the road making machine, and to cool down at least one second component of the road making machine. The system can be configured to heat at least the first component of the road making machine, and to simultaneously cool down at least the second component of the road making machine. The first component of the road making machine in the form of a road finishing machine can be the screed or a part of the screed, or another apparatus of the road finishing machine. The second component of the road making machine in the form of a road finishing machine can, e.g., be an energy storage (e.g., battery) or an accumulator, or the primary energy source.
It is particularly advantageous for the heating system to include a first working medium circulating in a first circuit of the system, and/or a second working medium circulating in a second circuit of the system, and/or a third working medium circulating in a third circuit of the system. The first circuit can be closed or open. In a closed circuit, the same working medium can be circulated. In an open circuit, the circulating working medium can be replaced, for example, the working medium can be sucked into the first circuit and be pumped out of the first circuit after one circulation. The second circuit can be closed. The third circuit can be closed or open. The first working medium and/or the third working medium can contain a gaseous or liquid cooling medium or heat transfer medium, respectively. The second working medium can contain a liquid cooling medium or a heat transfer medium, respectively. The first working medium and/or the third working medium can be water, air, or a mixture of these two. The ambient air as the first working medium can be supplied into the first circuit by means of an airflow machine or a fan. The ambient air can be supplied into a first air conduction conduit of the first circuit by means of the fan. The first air conduction conduit can be connected to the evaporator or to a housing of the evaporator, respectively, so that the first working medium is in heat-exchanging contact with the evaporator or with the second working medium located in the evaporator. The first air conduction conduit can be part of a tube of the first circuit. The first working medium can be circulated in the tube, wherein the tube is partially wound around the evaporator or around a housing of the evaporator, respectively, so that the first working medium is in heat-exchanging contact with the evaporator. The first working medium can be circulated in the first circuit by means of the airflow machine or a pump, for example a circulation pump. The first working medium or ambient air, respectively, can be dissipated again to the environment from a second airflow conduit of the first circuit. The second working medium can be circulated in the second circuit by means of a pump, for example by means of a circulation pump. The second circuit can be arranged in the housing of the heat pump. The third working medium can be circulated in the third circuit by means of a pump, for example by means of a circulation pump. The third working medium can be circulated in a tubing, the tubing being partially wound around the liquefier or a housing of the liquefier. The tubing can be connected to the housing of the heat pump by means of a pressure-resistant tube coupling.
It is an advantage for the heat pump to be configured to increase a first temperature of the second working medium to a second temperature. Thereby, one component of the road making machine is particularly efficiently heated.
It is an advantage for a temperature of the third working medium circulating in the third circuit to be between 75° C. and 200° C., preferably between 100° C. and 150° C. The temperature of the third working medium can be between 125° C. and 175° C. The temperature of the third working medium can be lower than 125° C. This heat can be used for heating the screed of the road finishing machine. A pressure value of the third working medium circulating in the third circuit can be, e.g., between 1 bar to 3 bar. The second pressure value can be 2 bar.
It is particularly efficient for the first working medium to be in heat-exchanging contact at least with one cooling apparatus or a cooler of an energy storage (e.g., battery) of the road making machine. The cooler can, e.g., be a heat exchanger. The cooler can be a part or a component of the heating system. The cooler can be connected to the first circuit, so that the first working medium flows through the cooler. The cooler can be a plate heat exchanger or a tubing. The cooler can be arranged at the energy storage or be integrated in the energy storage. The first working medium can be circulated around the evaporator in its heated state in the tube to evaporate the second working medium therein. The first working medium can be supplied further to the cooler in its cooled-down state in the first circuit and be heated by the waste heat of the energy storage. Thereby, the waste heat of the energy storage is transferred to the evaporator of the heat pump and is used for generating heat.
It would also be conceivable for the first circuit to be open. Here, ambient air can be supplied into the air conduction conduit of the first circuit by means of the fan. A first quantity of the first working medium can be, after a circulation around the evaporator, dissipated to the environment in a cooled-down state from a second air conduction conduit of the first circuit. A second quantity of the first working medium can be further circulated in the first circuit in a cooled-down state and flow through the cooler.
It is advantageous for the third working medium to be in heat-exchanging contact with the first component of the road making machine. The third working medium can be in heat-exchanging contact with a plurality of components of the road making machine. The third working medium can be in heat-exchanging contact with a heat exchanger which is configured to heat at least the first component or a part of the first component. The third working medium can flow through the heat exchanger. At least one heat exchanger can be integrated in the first component or in a part of the first component. The heat exchanger can be a plate heat exchanger or a tubing. The heat exchanger can be attached, e.g., to a screed plate and/or a tamper and/or a pressing ledge. The third working medium can be supplied to the first component of the road making machine in the tubing which is arranged at the housing of the heat pump in a pres sure-resistant manner.
The heating system is even more reliable if the first working medium and/or the second working medium and/or the third working medium contains an antifreeze. The antifreeze can contain, e.g., glycerin and/or ethylene glycol and/or ethanol.
In one embodiment, the heat pump or the housing of the heat pump, respectively, is arranged at the tractor. The motor of the heat pump can be arranged in the housing of the heat pump. The airflow machine can be arranged directly at the housing of the heat pump or at another point of the tractor.
In a particularly space-saving embodiment, the heat pump or the housing of the heat pump, respectively, is arranged at the first component. This has the advantage to shorten a supply path of the third working medium from the heat pump to the first component or the heat exchanger arranged at the first component, respectively. This can reduce or prevent a heat loss along the supply path.
In one embodiment, the road making machine is a road finishing machine, wherein the first component is a screed of the road finishing machine. The screed can be fastened to a machine frame of the tractor of the road finishing machine. The heating system can be configured to heat at least a portion of the screed and/or at least another component of the road finishing machine and a material bunker and a conveying device. The component of the screed can be a screed plate and/or a tamper and/or a pressing ledge. The heat exchanger can be attached on the screed plate and/or a tamper and/or a pressing ledge of a basic screed body or a screed extension part of the screed. The heat exchanger can be a tubing or a plate heat exchanger. The heat exchanger can be arranged at the screed such that it comes into contact with the laying material. The heat exchanger can be integrated in the screed plate and/or in the tamper and/or in the pressing ledge of a basic screed body or a screed extension part of the screed.
As an alternative, the road making machine can be a charger vehicle. The heating system can be configured to heat at least a component of the charger vehicle and a material bunker and/or a conveying device.
The disclosure furthermore relates to a method for operating a heating system of a road making machine in the form of a road finishing machine for producing a paving layer, or in the form of a charger vehicle for conveying laying material to a road finishing machine, wherein the road making machine includes a tractor, a primary drive source, a chassis, and a material bunker, wherein the heating system includes a heat pump, wherein the method comprises the following procedure steps: circulating a first working medium in a first circuit, transferring heat from the first working medium to a second working medium circulating in a second circuit, increasing a first temperature of the second working medium to a second temperature by compressing the second working medium, transferring heat from the second working medium to a third working medium circulating in a third circuit, transferring heat from the third working medium to a first component of the road making machine. All features disclosed above in connection with the heating system of the road making machine can be employed individually or together in this method, or vice versa.
The disclosure furthermore relates to a use of ambient air heat and/or waste heat of a cooling system of a road making machine in the form of a road finishing machine or a charger vehicle for heating a working unit of the road making machine. All features disclosed above in connection with the heating system of the road making machine or with the method for heating a component of a road making machine can be employed individually or together in this use, or vice versa.
Embodiments according to the disclosure are shown in the following figures. In the drawings:
The heat of the ambient air evaporates a second working medium 28, 28′ circulating in a second circuit 27, 27′ of the heating system 11, 11′ in the evaporator 15, 15′. The second working medium 28, 28′ is supplied to the compressor 17, 17′ in a gaseous state and compressed by means of the compressor 17, 17′ and thereby heated. Here, a first temperature T1, T1′ of the second working medium 28, 28′ is increased to a second temperature T2, T2′. In the liquefier 16, 16′, the second working medium 28, 28′ is condensed, so that the heat of the second working medium 28, 28′ is dissipated to the environment. The second working medium 28, 28′ is further supplied to the expansion valve 18, 18′ in a liquid state. By means of the expansion valve 18, 18′, a pressure level of the second working medium 28, 28′ is reduced, and the second working medium 28, 28′ is further cooled down.
The electric motor 19, 19′ is electrically powered by a current inverter W, W′ of an energy storage 29, 29′ (e.g., battery) of the road finishing machine 2.
In a third circuit 30, 30′ of the heating system 11, 11′, a third working medium 31, 31′ or a liquid, respectively, comprising, for example, water and antifreeze, is circulated in a tubing 32, 32′, for example by means of a pump (not shown). A portion of the tubing 32, 32′ is wound around the liquefier 16, 16′. One portion of the tubing 32, 32′ is located outside the housing 20, 20′, and one portion of the tubing 32, 32′ is fastened to the housing 20, 20′. The second working medium 28, 28′ in the liquefier 16, 16′ transfers its heat partially to the third working medium 31, 31′ and thereby cools down. The heated third working medium 31, 31′ is supplied to a heat exchanger 33, 33′. The third working medium 31, 31′ is caused to flow through the heat exchanger 33, 33′, and the component 12, 12′ is heated. The heat exchanger 33 can be arranged at the first component 12 of the road finishing machine 2, for example at a screed plate 34 of the screed 8. The heat exchanger 33′ can be arranged at the first component 12′ of the charger vehicle 13, for example at the material bunker 5′. Subsequently, the third working medium 31, 31′ is discharged to the liquefier 16, 16′ and heated again there. A temperature T of the third working medium circulating in the third circuit can reach up to 125° C.
| Number | Date | Country | Kind |
|---|---|---|---|
| 22201075.3 | Oct 2022 | EP | regional |
