RU2718556C1 - Thermal control system for internal combustion engines based on self-regulating electric heaters - Google Patents

Abstract

FIELD: engine building.

SUBSTANCE: invention relates to engine building, namely, to auxiliary systems for thermal action on fuel and engine oil during operation of internal combustion engines in conditions of low ambient temperatures, and can be used in stationary and transport power plants with internal combustion engines to facilitate start-up. Thermal control system for internal combustion engines based on self-regulating heaters, comprising nanomodified polymers, which heating elements are located in the oil crankcase and the fuel supply system and are connected to the electric accumulator. Heating elements comprise carbon nanotubes distributed in a flexible polymer matrix, heating elements are electrically connected to each other by a mixed parallel-series method and are fixed on the heated surface with an adhesive electric thermal conductive compound containing carbon nanotubes. Heating elements are made in the form of sheets of silicone rubber with carbon nanotubes distributed in them. Carbon nanotubes are contained in amount of 3 to 15 wt%.

EFFECT: invention provides thermal control of fuel and engine oil under conditions of low temperatures, heating fuel and engine oil before starting under low temperatures, maintaining engine oil temperature during prolonged stops, maintaining constant temperature of fuel in tank in order to prevent condensation of moisture.

3 cl, 5 dwg

Description

The invention relates to engine building, and in particular to auxiliary systems for the thermal effect on fuel and engine oil during operation of internal combustion engines at low ambient temperatures and can be used in stationary and transport power plants with internal combustion engines to facilitate starting.

A known diesel fuel heating system, which contains a fuel tank with a heater, a pressure fuel pipe, a submersible tubular electric fuel heater, which is installed in the fuel intake grid and connected to an electronic control device. The second main heater is installed in the fuel line in front of the fine fuel filter and is connected to an electronic control device, which, in turn, is equipped with a temperature sensor. The third tubular electric heater for heating the coolant is installed in the pipe between the engine and the interior heating radiator and is equipped with an electric pump with connection to an electronic control device (see RF Patent No. 2177071 F02M 31/125, publ. 2000).

The disadvantage of the presented system is the one-sided adaptability to heating without precise temperature control at low ambient temperatures, and the fact that the effect of heat is directed exclusively to fuel, although engine oil also requires preliminary thermal preparation.

A device is known for prestarting heating of crankcase oil of an internal combustion engine, which comprises a crankcase and, mounted on its wall, heating means connected to a power source and including a housing, and heating elements for heating the crankcase oil are made of lavsan threads with resistive silver sputtering and are placed on external lateral generatrices of cylindrical recesses of the bottom of the oil pan with a height of at least 5 diameters, with decentrally located heating elements. The oil located in the cylindrical cavities of the crankcase is heated and ejected under the influence of gravitational forces; instead, cold oil enters the cylindrical cavity, which is again heated and rises. The heating of the entire volume of oil occurs due to the repetition of the above cycles. On the outside, the crankcase with heating devices installed on it is protected by a thermally insulated casing, which is made of dense material and is insulated from the inside. (RF patent for ПМ №121864 F01M 5/02, publ. 2012).

The disadvantage of this utility model is the complexity of manufacturing an ICE crankcase for installing the proposed electric heaters, as well as the complete thermal insulation of the ICE crankcase, which prevents heat exchange with the environment during the operation of ICE at positive temperatures, causing overheating of the entire ICE design.

A device is known for facilitating the starting of automobile internal combustion engines at low air temperatures in winter, which comprises a hollow body connected to a cover and an electric heating element connected to an electric cord for connecting to a power source, characterized in that the body is made with grooves - front a groove for installation in a cylinder block of an internal combustion engine and a rear groove for installing a housing cover, wherein the housing cover located in its rear part, extruded in the rear housing and the bore therein is provided with holes for the passage of the tubular electric heater tubes which are sealingly crimped in the lid with sleeves and a tubular heater with an electrical cord connected through the soldered joint, the solder joint space filled polymeric insulating mass. This heater has a small power consumption (0.6-0.7 kW), while the use of an additional temperature controller is not required (RF Patent for utility model No. 1121717, F02N 19/10, publ. 2011).

The disadvantage of this device is the need to change the design of the engine to ensure the installation of the device in the housing of the engine block.

Known electric heater of the internal combustion engine, which contains a housing with nozzles, a lid and a thermal electric heater located inside the housing, moreover, the heater housing is made in the form of a cylindrical glass with three holes, two of which are arranged coaxially on the side wall of the glass and are provided with opposite branch pipes. The hole located at the end of the housing is equipped with a flange made with the possibility of connection with the cover. The lid is provided with a plate mounted between the lid and the housing, on which an electric heater is mounted, made in the form of a tubular spiral with a resistive element inside. The spiral is located inside the heater body, so that the axis of the side holes of the body passes through the hole of the tubular spiral, with one pipe connecting the heater to the lower cavity of the engine cooling jacket, and another pipe with the engine radiator, in addition, the heater can be equipped with a temperature controller installed between the cover and a metal plate. When voltage is applied to the electric heater, the liquid heats up and moves upward, through the heater pipe and through the pump enters the engine cooling jacket, cold liquid drops down through the pump and pipe, where it is heated by the electric heater. The effect of two in-line thermosiphon liquid circulation through one pipeline occurs naturally without forcibly turning off the electric heater (RF Patent for Utility Model No. 77361, IPC F02N 17/06, publ. 2008).

The disadvantage of this invention is the need for a temperature controller that prevents overheating of the electric heater.

A device for facilitating the starting of an internal combustion engine is known, which comprises a main self-regulating heating element installed in the oil pan, and additional elements located in the cavity between the filter element bodies. On the fuel line, the thermistor is installed in the form of a cable with a contact along its length. A thermistor is installed on the fuel intake pipe along its generatrix surface with the possibility of fixation (see RF Patent No. 2267645 F02N 17/04, publ. 2005.11.03).

The disadvantage of this device is that the use of ceramic self-regulating heating elements leads to a decrease in the heating rate caused by a decrease in the temperature head when approaching the switch point of the heater, which leads to a wide variation in the temperatures to which the fuel and engine oil are heated, as well as the appearance of high starting currents when turned on.

A known temperature control system for fuel and motor oil in internal combustion engines (RF Patent No. 2398126, IPC F02M 31/125, publ. 2010.27.08). The temperature control system of fuel and motor oil in internal combustion engines, consisting of heating elements located in the oil sump and fuel supply system, in which the oil sump is connected by supply and exhaust pipelines to a tank containing thermally accumulating nanomodified material and heating elements, while in the supply pipe there is pump, and in the discharge pipe valve. The heating elements are made of thermoelectric modules, which are pressed on one side of the junctions to a heat exchanger connected by a supply and outlet pipe to a heat exchanger on the fuel line, and on the other side of the junctions, to a radiator with a fan, and there is a pump in the inlet pipe and a valve in the outlet pipe in this case, to the heat exchanger with the thermoelectric module through the inlet pipe with the valve and the outlet pipe is connected a tank containing a thermally accumulating nanomodified material, which is connected through an inlet and outlet pipe with valves to a heat exchanger on the fuel line, while thermoelectric modules, valves, and pumps are connected to an electronic control system.

The main disadvantage of the presented device is the use of additional automation elements, which reduces the reliability of the device and complicates installation on the elements of an internal combustion engine. In this case, it is worth considering the fragility of the Peltier elements and the fact that thermal regulation with decreasing temperature is not always required.

The closest analogue is an autonomous system for maintaining the starting temperature of a diesel engine of a vehicle at low temperatures (PM No. 188 976, IPC: F02N 19/02 (2010.01), F01M 5/02 (2006.01), published: April 30, 2019).

The system contains electric oil heaters, a battery, a fuel filter, temperature sensors for engine oil and the environment, electric heaters and sensors are connected to a microprocessor control unit equipped with a display unit. Each electric heater is a rigid prepreg housing, exactly repeating in shape the outer surface of the heated oil pan, engine, filter and battery, with heating elements sealed inside in the form of a conductive fabric; the conductive fabric of the oil pan of the crankcase is made of two sectors, one of which is soldered to the bottom of the pan, the second to its side walls; sections of thermoelectric modules are tightly fixed on the outer surface of each electric heater; and the standard engine oil filter is also equipped with an electric heater.

This device is also characterized by the same drawbacks: the use of additional automation elements in the form of relays and microprocessors and thermoelectric modules, which reduces the reliability of the device and complicates installation on the elements of an internal combustion engine.

The technical result consists in increasing the energy efficiency and reliability of the means designed to stabilize the thermophysical state of the fuel and engine oil in internal combustion engines in the temperature range, including low ambient temperatures.

The technical result is achieved by the fact that the temperature control system for internal combustion engines contains nanomodified polymers, the electric heating elements of which are located in the oil sump and fuel supply system and are connected to an electric battery, according to the invention, the heating elements contain carbon nanotubes distributed in a flexible polymer matrix, heating elements electrically interconnected in a mixed parallel-serial way and mounted on the heated surface with an adhesive electro-heat-conducting compound containing carbon nanotubes.

The heating elements are made in the form of sheets of silicone rubber with carbon nanotubes distributed in them. Carbon nanotubes are contained in an amount of from 3 to 15 masses. % The use of carbon nanotubes distributed in a flexible polymer matrix as heating elements ensures uniform heating and eliminates overheating during operation. The operation of the heating element is as follows: when a constant or alternating electric current is applied, heat energy is released, which is set at a certain temperature level, depending on the mass content of carbon nanotubes. This ensures efficient use and safe operation.

The electrical connection of the heating elements to each other in a mixed parallel-serial way ensures the dosed heating of individual structural elements of the internal combustion engine and allows the use of a unified series of heaters.

Fixing the heaters to the heated surface with an adhesive electrically heat-conducting compound containing carbon nanotubes provides effective heat removal from the heaters to the heated nodes.

The implementation of the heating elements in the form of sheets of silicone rubber with carbon nanotubes distributed in them provides ease of installation and efficient heat supply due to the tight fit to the heated surface.

The selected content of carbon nanotubes in an amount of from 3 to 15 mass. % is determined experimentally: at a concentration of less than 3%, the operation of the heater is unstable and the heating intensity is insufficient. With an increase in the content of nanotubes above 15%, the heating intensity does not increase, and the cost of nanomaterials makes the heater uncompetitive.

Examples of the proposed device are illustrated by the drawings shown in FIG. 1, 2 and 3.

In FIG. 1 shows a general view of a temperature control system for internal combustion engines based on self-regulating electric heaters.

The list of positions:

1 heating element on the fuel line after the fuel filter;

2 fuel filter;

3 heating element on the fuel line to the fuel filter;

4 heating element on a fuel tank;

5 fuel tank;

6 heating elements located on the oil sump;

7 oil sump;

8 internal combustion engine;

9 heating element on a flat pallet;

10 protective cover;

11 heating element on a flat part of the pan;

12 heating element on the side of the pallet;

The described system performs the following functions: thermoregulation of fuel and engine oil at low temperatures, as well as the loads of the internal combustion engine; warming up fuel and engine oil before starting at low temperatures; maintaining engine oil temperature during long-term parking; maintaining a constant temperature of the fuel in the tank in order to prevent moisture condensation.

The temperature control system for internal combustion engines (Fig. 1) contains a heating element based on an electric heater with the effect of self-regulation 1 installed in the fuel line after the fuel filter 2; heating element 3 - in the fuel line in front of the fuel filter 2; heating element 4 - on the fuel tank 5 on its outer surface near the filler neck; heating element 6 - on the bottom of the oil sump 7 of the internal combustion engine 8. In FIG. 2 shows the placement of the heating element 9 on a flat pallet, with a protective casing 10 protecting the heating element from mechanical damage. In FIG. 3 - placement of the heating elements 11 on the flat part of the pallet and the heating elements 12 on the side of the pallet.

The temperature control system for internal combustion engines based on self-regulating electric heaters works as follows.

Separate electric heaters 1, 3, 4, 6 are supplied with electrical voltage, which leads to their heating. As the temperature of the heated filter or crankcase rises, the heating rate decreases and the consumed electric energy decreases. The maximum power of heat generation corresponds to the moment of initial inclusion.

The operation of electric heaters is as follows: when a constant or alternating electric current is applied, thermal energy is released, which is set at a certain temperature level, depending on the mass content of carbon nanotubes. With the simultaneous inclusion of all heating elements on their surface, the same thermal energy is released, as they heat up, i.e. modules that have already entered the balance mode - reduce energy consumption, due to successive switching on, the power is redistributed to modules that require a large consumption of electric current from the power supply network. The presented effect is related to the temperature dependence of the resistance of FIG. 4. At positive ambient temperatures, the heat dissipation of the heaters due to the self-regulation effect becomes small, which is confirmed by the thermal imaging survey of FIG. 5. The invention provides thermoregulation of fuel and engine oil at low temperatures, as well as the loads of the internal combustion engine; warming up fuel and engine oil before starting at low temperatures; maintaining engine oil temperature during long-term parking; maintaining a constant temperature of the fuel in the tank in order to prevent moisture condensation.

Claims (3)

1. The temperature control system for internal combustion engines based on self-regulating electric heaters, containing nanomodified polymers, the heating elements of which are located in the oil sump and fuel supply system and are connected to an electric battery, characterized in that the heating elements contain carbon nanotubes distributed in a flexible polymer matrix, this heating elements are electrically interconnected by a mixed parallel-serial method and epleny on the heated surface of the adhesive elektroteploprovodyaschim compound containing carbon nanotubes. 2. The temperature control system according to claim 1, characterized in that the heating elements are made in the form of sheets of silicone rubber with carbon nanotubes distributed in them. 3. The temperature control system according to claim 1 or 2, characterized in that the carbon nanotubes are contained in an amount of from 3 to 15 wt.%.

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