SWITCH HEATING DEVICE WITH INTEGRATED CONTROL

Description

Technical field

[0001] The invention relates to a switch heating device with integrated control. State of the art

[0002] Switch heating devices for preventing the freezing of moving parts of switches in rail-bound transport systems by heating the switches are known. These devices typically employ electric heating elements with connection heads on the switch rails. The electric switch heaters are usually switched on and off manually or by a central control system as needed. The central control system switches multiple switches, each with several heating elements, on or off.

[0003] Such switch heating devices are known, for example, from WO 2019 / 075248A1, WO 2020 / 053842A2, or DE102014113541A1. A disadvantage of these conventional switch heating devices with manual activation or central control is that the central control switches all connected heating elements on and off together, or in groups, without knowing the exact thermal condition of each individual heating element. The activation is generally determined by the thermal condition at the most exposed switch, which leads to unnecessary power consumption, as individual heating elements heat the rail to a higher temperature than required. Such heating systems are also prone to malfunctions if, for example, the power output is too low to reach the required rail temperature.Furthermore, the known control elements are designed in such a way that, due to their size and nature, they cannot be directly attached to a rail. Object of the invention

[0004] The present invention is based on the objective of providing a switch heating device which consumes little energy, is resistant to malfunctions, enables good load management, and is small and compact so that it can be attached to a rail in the area of ​​a switch. Description of the invention

[0005] This task is accomplished by a switch heating device with an integrated control unit. The switch heating device, for heating and mounting on a switch for a rail-bound transportation system, comprises a heating element, a connection head with a housing attached to the heating element, a temperature sensor located outside the connection head, and a connecting cable leading from the connection head. A control unit is located inside the housing of the connection head and thermally connected to an inner surface of the housing. The control unit has a circuit board with a processor and a power switch for controlling the heating element, and a heat transfer element is thermally connected between the power switch and the inner surface of the housing. Furthermore, the connection head with the inserted control unit is completely sealed with sealing elements.

[0006] The advantage of such a switch heating device with integrated, independent control is that the device can react precisely and independently to the local thermal situation, even without a central control unit. This leads to a significant reduction in energy consumption and a reduction in malfunctions. The invention enables individual control of all heating elements without the need for additional cabling. In the switch heating device according to the invention, each element is aware of its own thermal situation and is able to react independently when the rail temperature exceeds or falls below a setpoint.

[0007] The control unit's circuit board preferably includes a processor for processing the control data, which is preferably programmed with a temperature setpoint. Depending on whether the setpoint is above or below the value measured by the temperature sensor, a signal is sent from the processor to the power switch, and the heating element is switched on or off.

[0008] The circuit breaker is preferably a power semiconductor. In another embodiment, the circuit breaker can also be a relay or a power controller.

[0009] The control unit is thermally connected to an inner surface of the housing by means of a heat transfer element thermally connected between the circuit breaker and the inner surface of the housing. The heat transfer element is an element that transports energy in the form of heat across at least one thermodynamic system boundary and is preferably made of metal, thermal paste, thermal gel, or a thermally conductive potting compound.

[0010] The control unit is capable of communicating with a higher-level control system, preferably via control wires or a wireless connection. The control unit can receive instructions from the higher-level control system and return status messages and temperature values. Should the higher-level control system fail, the control unit can detect this and independently assume control functions. Additionally, a higher-level control system can issue a command to each individual switch heating element to switch it on or off. This allows for load distribution, preventing all switch heating elements from switching on or off simultaneously. This results in intelligent load management, where power is distributed across different switches to prevent excessive power consumption. This, in turn, reduces the susceptibility to malfunctions because not all switch heating devices are connected at the same time.

[0011] The heating element is preferably an electric heating element, particularly preferably a resistive heating element. The heating element is, for example, a heating rod or a mineral-insulated heating element. Preferably, the heating element is a heating rod. Depending on its arrangement on the rail, the heating rod preferably has one or more bends and is up to 12 meters long, preferably 0.5 to 8 meters long.

[0012] The terminal head of the present invention must be small enough to be mounted on a DIN rail. Small terminal heads with integrated electronics are prone to overheating. By using and specifically arranging the heat transfer element between the circuit breaker and the inner wall of the housing, it is possible to dissipate the heat generated inside the terminal head by the circuit breaker to the outside. Despite its compact size, the housing has a sufficiently large surface area to dissipate heat to the surroundings via convection, thermal radiation, and conduction. As a result, the terminal head of the present invention is small, compact, and yet completely sealed, and can be mounted directly on a DIN rail.

[0013] The connection head preferably has a cylindrical shape with a housing and two end pieces, the first end piece preferably being a cable gland and the second end piece preferably a housing closure on the heating element side. One or more connection cables and preferably a sensor cable connected to the temperature sensor pass through the cable gland. The cable gland preferably functions as a cable gland, providing a particularly good seal for a cable, wire, or insulated conductor as it passes through a housing wall. The heating element is guided through the housing closure. The housing closure preferably has the form of a crimp or screw-in nipple, more preferably a screw-in nipple, preferably soldered to the heating element, and closes the heating element-side end piece of the connection head.The housing of the preferably cylindrical housing preferably has an annular recess on its outer surface for receiving mounting clips for attaching the switch heating device to a rail. The connection head, including the housing, cable gland, and housing closure, is preferably made of stainless steel, preferably chromium-nickel steel. The connection head is completely sealed with sealing elements to prevent the ingress of external influences such as moisture or dirt. The cable gland is sealed with a first sealing element, preferably a compressible rubber plug with through-holes for the cables, and compression and sealing are achieved by tightening a union nut. The housing closure is sealed with a second sealing element.The second sealing element is preferably an O-ring or a flat gasket, but can also be designed to be metal-to-metal or liquid-to-liquid sealing.

[0014] The connecting cable leading from the connection head has power conductors for transmitting current from a power source to the connection head with control unit and to the heating element. In a further embodiment, the connecting cable has at least one, preferably two or three additional conductors, so-called control conductors, for transmitting control data in order to communicate with an external higher-level control system. In a further embodiment, communication with the external higher-level control system can also take place wirelessly. If a higher-level control system is present, the higher-level control system can give instructions to the control unit of the switch heating device according to the invention. Conversely, the control unit can return status and temperature data to the higher-level control system.The higher-level control system, for example, specifies a target temperature and compares it to a value measured by the local temperature sensor. It then switches the heating element on if the measured value is below the target value and switches it off if the measured value is above the target value. This external higher-level control system can be located at a specific point along the track and control multiple switches simultaneously.

[0015] The switch heating device with integrated control unit in the connection head and external local temperature sensor is thus able to switch the heating elements on or off as needed via a predefined internal setpoint or to follow a setpoint specified by an external, higher-level control system. The predefined internal setpoint can be individually programmed on the processor of each control unit.

[0016] The temperature sensor, located outside the connection head, is preferably connected to the control unit inside the connection head via a sensor cable. In another embodiment, the temperature sensor is connected to the control unit inside the connection head via a wireless connection. The temperature sensor is preferably located on a rail near the connection head, preferably less than 3.5 meters away, thus keeping the sensor cable length short. This increases the robustness of the switch heating device.

[0017] Preferably, the switch heating device has a power supply, preferably an electronic power supply or a transformer, to generate the low electrical voltage.

[0018] In a preferred embodiment, a pressure element is arranged between the control unit and the inner surface of the housing to hold the control unit in position and to improve heat transfer. Preferably, the pressure element is arranged between the circuit board and the inner surface of the housing on the side of the circuit board opposite the circuit breaker. In a further embodiment, the pressure element is arranged between the circuit board and the circuit breaker. In a further embodiment, the switch heating device comprises two pressure elements: one between the circuit board and the circuit breaker, and a second between the side of the circuit board opposite the circuit breaker and the inner surface of the housing. The pressure element can be flexible or rigid and made of metal, for example in the form of a spring, or of plastic.

[0019] The present switch heating device is small and compact, fully sealed, and can be mounted directly on a rail in the area of ​​a switch. Each heating element can control itself according to an internal or external setting, thus switching on or off. Preferably, each switch is equipped with several switch heating devices, which are preferably attached to both the stock rail and the switch rail. In one embodiment, for example, each switch rail and stock rail of a switch each has two switch heating devices.

[0020] In addition, the present invention relates to a method for heating switches for a rail-bound transport system with a switch heating device according to the invention, wherein the control unit compares a setpoint pre-programmed in the control unit with a value measured by the temperature sensor in order to control the heating element or to switch it on or off.

[0021] In another embodiment, the method includes specifying an external setpoint to an external higher-level control system and comparing this setpoint with a value measured by the local temperature sensor to switch the heating element on or off.

[0022] Furthermore, the invention relates to the use of a switch heating device according to the invention for heating a switch for a rail-bound transport system.

[0023] Combinations of two or more of the above-listed designs and variants are conceivable and claimed.

[0024] Further advantages of the invention will follow from the description below, in which the invention is explained in more detail with reference to exemplary embodiments shown in the drawings. Brief description of the characters

[0025] They show: Fig. 1 a switch heating device in schematic representation, Fig. 2A a connection head in perspective view from the side, Fig. 2B a cross-section through the connection head of Figure 2A along line CC, Fig. 3A a switch heating device attached to a rail in perspective view, Fig. 3B a cross-section through a Figure 3A The shown switch heating device is attached to a rail. Fig. 4 a schematic representation of a railway switch with several switch heating devices, and Fig. 5a schematic representation of four switch heating devices connected to a higher-level control system.

[0026] The same reference symbols are used for the same elements in the figures, and explanations for a particular reference symbol apply to all figures unless explicitly stated otherwise. Exemplary embodiments of the invention

[0027] Figure 1 Figure 1 shows a schematic representation of a switch heating device 1 with a heating element 2, a connection head 3 connected to the heating element, and a temperature sensor 4, which is connected to the connection head 3 via a sensor cable 15. A connection cable 11 with several power conductors (not shown) and one or more control conductors (not shown) leads from the side of the connection head 3 opposite the heating element 2 and is connected to a power source and, if desired, to an external control system.

[0028] Figure 2A Figure 1 shows a perspective view of the outside of a connection head 3. The connection head 3 has a housing 9 with a cylindrical housing shell 32 and two end pieces, the first end piece 14 being a cable gland 21 and the second end piece 19 being a housing closure 20 on the heating element side. The connecting cable 11 leads from the cable gland 21, and the heating element 2 leads from the housing closure 20. The housing shell 32 of the cylindrical housing 9 has an annular recess 33 on its outside for receiving mounting clips (18, not shown).

[0029] Figure 2B shows a cross-section along line CC through the connection head 3 of the Figure 2AThe terminal head 3 has a housing 9 with an inner surface 17 and a cable gland 21 at a first terminal end 14 and a housing closure 20 at a second terminal end 19. A control unit 5, comprising a circuit board 10, a processor 6, and a power switch 7, is arranged within the housing 9 of the terminal head 3 for controlling, i.e., switching on and off, the heating element 2. The control unit 5 has a circuit board 10 with a processor 6 and a power switch 7 for controlling, i.e., switching on and off, the heating element 2. The processor 6 is soldered to the circuit board 10. The power switch 7 can be designed, for example, as a power semiconductor, relay, or power controller and is connected to the circuit board 10.A heat transfer element 8 is thermally conductively attached between the circuit breaker 7 and the inner surface 17 of the housing 9 to conduct heat generated by the circuit breaker 7 directly from the circuit breaker 7 to the housing 9 of the terminal head 3. The heat transfer element 8 is a metal element, a thermal paste, a thermally conductive gel, or a thermally conductive potting compound and is in direct contact with the inner surface 17 of the housing 9, or in contact with it via a thermally conductive compound. A clamping element 16 is preferably arranged between the control unit 5 and the inner surface 17 of the housing 9 to hold the control unit 5 in position. The control unit 5, with the circuit board 10 and the circuit breaker 7, is attached to the inner surface 17 of the housing 9 either via the heat transfer element 8 and, if necessary, a thermally conductive compound, for example, by gluing, or is pressed against the inner surface 17 of the housing 9 by a clamping element 16.

[0030] The heating element 2 extends through the housing closure 20 of the second end 19 of the connection head 3 into the connection head 3. The heating element 2 preferably has two connection pins 23 (only one is visible in the side view). The two connection pins 23 are electrically connected to the circuit board 10 via two cables. To hold the circuit board 10 in position, a retaining element 22 is arranged on the housing closure 20, with a central recess for the passage of the connection pins 23, so that the circuit board 10 does not rotate when the housing 9 is screwed onto the housing closure 20.

[0031] The connecting cable 11 and the sensor cable 15, both connected to the circuit board 10, pass through the cable gland 21. The sensor cable transmits data from the temperature sensor (not shown) to the control unit 5. The connecting cable 11 includes power conductors (not shown) to supply the control unit 5 with electrical power, which is switched by the power switch 7 and subsequently required to heat the heating element 2. If desired, the connecting cable 11 also includes one or more control conductors for transmitting control data, preferably via a bus protocol, to communicate with a higher-level controller.

[0032] The connection head 3 with the inserted control unit 5 is completely sealed with sealing elements to prevent the ingress of external influences such as moisture or dirt. The cable gland 21 is sealed with a first sealing element 12, preferably a compressible rubber plug with through-holes for the cables, wherein compression and sealing are achieved by tightening a union nut, and the housing closure 20 is sealed with a second sealing element 13. The second sealing element 13 is preferably an O-ring or a flat gasket, but can also be designed to be metal-to-metal or liquid-tight.

[0033] In Figure 3AA rail 24 with an attached switch heating device 1 is shown. The switch heating device 1 has a connection head 3, a heating element 2 extending from the housing closure 20 of the connection head 3, preferably a heating rod with a bend, a temperature sensor 4 arranged on the rail with sensor cable 15, and a connection cable 11, wherein the sensor cable 15 and the connection cable 11 extend from the side of the connection head 3 opposite the housing closure 20 through the cable gland 21. The connection head 3 is fastened to the rail 24 by means of a fastening element 25, preferably a fastening clip 18.

[0034] Figure 3B shows a cross-section through a rail 24 and a connecting head 3, as in Figure 3A The connecting head 3 is shown, with the connecting head being attached to the rail 24 via the fastening element 25. The fastening element 25 comprises a fastening clip 18.

[0035] Figure 4Figure 1 shows a schematic representation of a turnout with a first stock rail 26, a second stock rail 26', a first switch rail 27 and a second switch rail 27'. Two turnout heating devices 1, 1', 1" are arranged on each of the stock rails 26, 26' and the switch rails 27, 27', which can each switch on and off independently, depending on the rail temperature measured by the temperature sensor and the temperature setpoint specified by the control unit or a higher-level control system.For example, it is possible that the first switch heating device 1" on the first switch rail 27 switches off because it is in contact with the first stock rail 26, which is heated by the first switch heating device 1, and thus sufficient heat is available. However, the first switch heating device 1' of the second switch rail 27', which is not in contact with the heated second stock rail 26', switches on because the second switch rail 27' is cooled from all sides and therefore has a higher heat requirement. It is also possible that if a switch is exposed to sunlight, less heat is required than for an adjacent switch that is in the shade. The heating elements of the sunlit switch will switch off temporarily with the switch heating device of the invention because the target temperature has been reached thanks to the solar radiation. The same applies to switches with more or less significant wind exposure.It is possible for all switch heaters of one switch to be switched on, while those of the adjacent switch are switched off. This results in considerable energy savings, as not all switch heaters are constantly heated. Additionally, a higher-level control system can send a command to each individual switch heater to switch on or off. This allows the load to be distributed so that not all switch heaters are switched on or off simultaneously.

[0036] Figure 5Figure 1 shows a schematic representation of four switch heating devices 1, each with a connection head 3, a heating element 2, a temperature sensor 4 with sensor cable 15, and a connection cable 11. The connection cable 11 of the four switch heating devices 1 is connected via a control wire to a higher-level control unit 28. The higher-level control unit 28 is connected to a weather sensor 29, a temperature sensor 30, and a rain sensor 31 and can, as needed, supply control data to the control unit (5, not shown) located in the connection head 3 and switch the switch heating device 1 on or off. In one embodiment, the control unit (5, not shown) located in the connection head 3 has a pre-programmed setpoint temperature and compares this value with a value measured by the respective temperature sensor 4. If the value of the temperature sensor 4 is below the pre-programmed setpoint, the heating element 2 is switched on.If the value of temperature sensor 4 exceeds the pre-programmed setpoint, the heating element 2 is switched off. In another embodiment, the higher-level control unit 28 can specify a temperature setpoint for the switch heating device 1, which it has calculated, for example, from weather data. The control unit 5 compares this setpoint with a value measured by the local temperature sensor 4 and automatically switches the respective heating element 2 on or off so that the setpoint temperature is maintained at the rail. Reference symbol list

[0037] 1, 1', 1" Switch heater 2 Heating element 3 Connection head 4 Temperature sensor 5 Control unit 6 Processor 7 Circuit breaker 8 Heat transfer element 9 Housing 10 Circuit board 11 Connection cable 12 First sealing element 13 Second sealing element 14 First head end 15 Sensor cable 16 Pressure element 17 Inner surface of housing 18 Mounting clip 19 Second head end 20 Housing closure 21 Cable gland 22 Retaining element 23 Connection pin 24 Rail 25 Mounting element 26, 26' Jaw rail 27, 27' Tongue rail 28 Higher-level control 29 Weather sensor 30 Temperature sensor 31 Rain sensor 32 Housing jacket 33 Ring-shaped recess

Claims

1. A switch heating device (1)for heating and mounting to a switch for a rail-bound transport system, comprising a heating element (2), a connection head (3) with a housing (9) arranged at the heating element (2), a temperature sensor (4) arranged outside the connection head (3) and a connection cable (11) leading out of the connection head (3), characterized in that a control unit (5) is arranged inside the housing (9) of the connection head (3) and is thermally conductively connected to an inner surface (17) of the housing (9), wherein the control unit (5) has a printed circuit board (10) with a processor (6) and a circuit breaker (7) for controlling the heating element (2), and wherein a heat transfer element (8) is thermally conductively connected to the circuit breaker (7) and the inner surface (17) of the housing (9), and wherein the connection head (3) with the inserted control unit (5) is sealed with sealing elements (12, 13).

2. The switch heating device (1) according to claim 1, characterized in that the heat transfer element (8) is made of metal, a thermal paste, a thermal gel or a thermally conductive potting compound and provides the thermally conductive connection of the control unit to the housing.

3. The switch heating device (1) according to any one of the preceding claims, characterized in that the connection cable (11) has power wires for transmitting power from a power source to the connection head (3) and at least one control wire for transmitting control data from a higher-level control system to the control unit (5).

4. The switch heating device (1) according to any one of the preceding claims, characterized in that the temperature sensor (4) arranged outside the connection head (3) is connected to the control unit (5) by means of a sensor cable (15).

5. The switch heating device (1) according to any of the preceding claims, characterized in that a pressure element (16) is arranged between the control unit (5) and the inner surface (17) of the housing (9) to hold the control unit (5) in position.

6. The switch heating device (1) according to claim 5, characterized in that the contact element (16) is of metal or plastic.

7. The switch heating device (1) according to any one of the preceding claims, characterized in that the housing (9) is cylindrical.

8. A method for heating switches for a rail-bound transport system with a switch heating device (1) according to any one of claims 1 to 7, characterized in that the control unit (5) compares a setpoint value preprogrammed in the control unit (5) with a value measured by the temperature sensor (4) in order to switch the heating element (2) on and off.

9. A method for heating switches for a rail-bound transport system with a switch heating device (1) according to any one of claims 1 to 7, characterized in that the control unit (5) compares a setpoint value specified by a superordinate control system (28) with a value measured by the temperature sensor (4) in order to switch the heating element (2) on and off.

10. Use of the switch heating device (1) according to any one of claims 1 to 7 for heating a switch for a rail-bound transport system.