HEATER WITH PLASTIC CONNECTIONS

Description

[0001] The invention relates to heating appliances for space heating and / or hot water preparation with hydraulic modules made of plastic and to the design of the connecting pieces made of plastic for connecting the channels of the hydraulic modules to the stationary housing lines.

[0002] The development of heating systems, especially boilers for space heating and hot water preparation in apartments, has focused in recent years, among other things, on equipping heating systems with compact hydraulic modules whose components are designed using lightweight construction.

[0003] Particularly important is the inexpensive lightweight construction of the wall-mounted boilers, which have now become standard.

[0004] The hydraulic module typically consists of several separately manufactured structural connecting parts, preferably made of plastic composite materials instead of the previously used metal alloys (mostly brass), which are expensive and have a significantly higher weight.

[0005] Commonly used composite materials include, in particular, polyamide (PA), polypropylene (PP) or glass fiber (GF) modified polyphthalamide (PPA) in various compositions, which are designated, for example, by the following names: PA66+30%GF, PA66+35%GF, PA66+40%GF, PP+40%GF or PPA+40%GF, although this list of used composite materials is not exhaustive.

[0006] Patent application EP 1 408 292 A1 discloses a heating device for central heating systems with a modular hydraulic block structure. The application describes the use of injection-molded plastic parts. The modules are preferably connected by click or clamp connections, which ensure quick assembly and high mechanical stability. The application describes how the pipe connections are attached to a mounting plate using sockets. For this purpose, the sockets have grooves and lugs that correspond to recesses in a pocket on the mounting plate that is open at the side. During assembly, the sockets can be inserted laterally into the pockets and are held in place there.

[0007] A similarly constructed hydraulic module is described in detail in document WO2018 / 202436 A1. This document describes the hydraulic module as a structural unit consisting of three separately manufactured parts. In its assembled state, the hydraulic module contains, in addition to the circulation pump and the secondary plate heat exchanger, all other hydraulic components, in particular valves and sensors for the physical parameters of the heating system. The four connecting channels for the heat transfer fluid between the hydraulic module and the stationary domestic circuits for space heating and domestic hot water preparation are circular in cross-section and point downwards. During installation, they are routed to the circular holes in the mounting plate. The installation of a boiler with such a hydraulic unit proceeds as follows: The hydraulic module is mounted on the mounting plate with the four channels pointing towards the prepared holes, or the module is attached near the holes on the mounting plate by a suitable detachable connection (e.g.The mounting plate is secured with mounting screws. A brass coupling nipple with a hexagonal flange is inserted from the underside of the mounting plate into each connection channel to create a hydraulically tight connection between the two pipes. The coupling nipple must have an external seal (O-ring) and a groove for clipping the hydraulic module into place on the hydraulic unit side. The nipple has an external thread on the stationary pipe side for screwing the pipe to the unit using a threaded nut. The hexagonal flange is engaged with a wrench to apply the necessary torque to create a tight screw connection during boiler installation.

[0008] It is the installer's responsibility to determine whether the stationary pipes have been tightened with sufficient torque. Insufficient tightening torque, and therefore inadequate fastening, can lead to leakage of the heat transfer fluid. When installing heating appliances on stationary pipes, a high torque is generally required to ensure a reliable connection between the heating appliances and the building's electrical system.

[0009] Since brass nipples are expensive, there is a natural tendency to replace them with plastic ones. However, in many cases, installers do not use the correct equipment (torque wrench) and may apply a higher than required torque during installation, which can damage the threads and other plastic parts.

[0010] The task is to provide a suitable solution for connecting the heating device to the stationary pipes using plastic connectors, ensuring that this connection is protected against possible damage from excessive torque.

[0011] This task is solved as follows. The connector for the connection between the heating unit's hydraulic module and the stationary pipes is made of suitable plastic. The connector is equipped with an external seal (O-ring) and a groove for clamping the hydraulic module on the hydraulic module side. On the stationary pipe side, the connector has an external thread for screwing the pipe to a threaded nut. The connector features a molded flange with lugs. A mating piece with grooves, made of the same plastic or another material (e.g., metal), is used to secure the connector. The shape of the grooves corresponds to the shape of the lugs, allowing the lugs to be inserted into the grooves. The connector and mating piece are positively engaged before forming a hydraulically tight connection with the stationary pipe.

[0012] If a torque higher than the limit is applied to the thread, the connector begins to rotate around its own axis, indicating to the installer that the required torque has been reached and the connection is secure. The value of the limit torque depends on the shape of the lugs on the plastic connectors and the corresponding design of the locking mechanism. The mating component need not be a separate part but can advantageously be designed as a hole in a mounting plate that is part of the heating device.

[0013] In the stress-strain analysis, components were tested that can be subjected to static or dynamic loads or other environmental stresses such as tension, torque, pressure, vibration, or temperature. The proposed connector was tested, and it was found that when made of PA66+30%GF composite material, the connector begins to rotate at a torque between 6.4 Nm and 10.8 Nm (depending on the specific design of the lugs and grooves). Thus, even higher applied torques have no deformation effect on the connector. Depending on the coefficient of friction between the components, a torque of 57 Nm to 160 Nm is required to destroy or damage the plastic connector. Due to its low-friction design, the engineered plastic connector is resistant to damage even at higher torques.

[0014] The technical solution is explained in more detail using the illustrations, but is not limited to them: Figure 1 shows a connector for connecting a hydraulic module to stationary lines, Figure 2 shows the counterpart to the connector made of Figure 1 , Figures 3 and 4 show two views of the form connection of the connector and the counterpart, Figure 5 shows a mounting plate in a heating appliance with integrated protrusions, Figure 6 shows part of a heating device, namely the underside of the mounting plate.

[0015] The heating unit comprises a hydraulic module with a plastic component featuring four connection channels for guiding the heat transfer fluid circulating between the hydraulic module and the stationary domestic circuits for space heating and hot water preparation. The channels can be arranged differently within the hydraulic module; therefore, a suitable mounting plate 50 with holes is required on the heating unit to establish the connections to the surroundings.

[0016] The heating device is provided with a mounting plate 50 for connecting the heating device to the stationary housing lines, the mounting plate 50 being located on the underside of the heating device.

[0017] In another embodiment, the mounting plate 50 can be arranged on the rear of the heating device, wherein the hydraulic module has connection channels running perpendicular to the underside of the heating device.

[0018] In Figure 6Figure 1 shows a bottom view of part of the heating unit with the mounting plate 50; examples include a connector that can be connected to the domestic hot water circuit 60 (return) and a connector that can be connected to the heating water circuit 70 (return).

[0019] The mounting plate 50 is provided with integrated counterparts 20 in the form of bores 5 with detents 41 provided on the bore circumference. A detents 41 consist of a recess 43 with projections 42 located downstream in the direction of rotation. Figure 2 .

[0020] The connection channels for guiding the heat transfer fluid on the hydraulic module are equipped with connectors 10.

[0021] Each connector 10 has a clamp connection 1 for hydraulically tight connection to the connection channel of the hydraulic module, a threaded connection 3 for connection to the stationary line and a molded flange 2 with lugs 40.

[0022] The hydraulic module is connected to the mounting plate 50 such that, in the pre-assembled state, the lugs 40 of each connector 10 engage in the recesses 43 of the detents 41 in the bores 5 of the corresponding counterpart 20, forming a positive connection 30. The body of the connector 10 is rotatable about its axis. The hydraulic module is firmly attached to the mounting plate 50 by means of fastening screws (not shown). During rotation, the lugs 40 and the corresponding detents 41, in particular the recesses 42 with the adjacent protrusions 43, interact in such a way that, when the thread is tightened and the limit torque is exceeded, the lugs 40 overcome the protrusions 42. The audible disengagement signal to the assembler that the limit torque has been reached. Furthermore, the torque collapses as the detents are overcome, thus protecting the components from overload.

[0023] The plastic connectors 10 are designed so that they cannot be damaged or destroyed by the torque applied to the threaded connection 3 when connecting the heating device to the stationary lines. If a torque exceeding the limit is applied, the connector 10 rotates about its axis, creating a hydraulically tight connection between the respective channel of the hydraulic module and the stationary line.

[0024] Depending on the material of the connector and the design of the lugs 40 on the plastic flange 2 of the connector 10 and the detents 41 on the bores 5 of the counterpart 20, the torque limit is between 6.4 Nm and 10.8 Nm.

[0025] The heating device for space heating and / or domestic hot water preparation with a hydraulic module with a component made of plastic has inventive form connections for connecting the inlets and outlets of the hydraulic modules to fixed housing lines, which are not damaged even in the event of improper installation if the installer applies too little torque to the screw connection. Reference symbol list

[0026] 1 Clamp connection 2 Form flange 3 Threaded connection 5 Bore 10 Connector 20 Counterpart 30 Form connection 40 Nose 41 Detent 42 Raised section 43 Recess 50 Mounting plate 60 Domestic hot water circuit (return) 70 Heating water circuit (return)

Claims

1. Heating appliance for installation in a dwelling with stationary dwelling pipes for a heat transfer fluid heated by the heating appliance, with a mounting plate (50) for connecting the heating appliance to the stationary domestic pipes, with a hydraulic module comprising a plastic structure with connecting channels for the heat transfer fluid between the hydraulic module and the stationary domestic pipes, each channel being provided with a connector (10), wherein the connector (10) has a clamp connection (1) for hydraulically tight connection to the connection channel of the hydraulic module, a threaded connection (3) for connection to the stationary pipe and a moulded flange (2) with lugs (40), characterised in that that the mounting plate (50) is provided with integrated counterparts (20) in the form of bores (5) provided with detents (41) with projections (42) and recesses (43), that the hydraulic module is designed to be fastened to the mounting plate (50) in such a way that the lugs (40) of each connector (10) engage in the recesses (43) of the detents (41) on the holes (5) of the corresponding integrated bore in the counterpart (20) and form a form-fit connection (30), and that the connector (10) is pivotally connected to the hydraulic module by means of a clamp connection (1) and to the mounting plate (50) by means of a form connection (30) to enable rotation of the connector (10) upon application of a torque limit value ( ).

2. Heating appliance according to claim 1, characterised in that the lugs (40) and detents (41) are designed such that, during assembly, when the connector (10) is rotated relative to the counterpart (20) and the specified torque limit value is exceeded, the lugs (4) overcome the resistance of the projections (42) of the detents (41).

3. Heating appliance according to one of claims 1 or 2, characterised in that the specified torque limit value is in the range from 6.4 Nm to 10.8 Nm.