CN102359411B - Inlet and exhaust heat control device and method for realizing HCCI combustion of gasoline engine - Google Patents

Abstract

The invention discloses an air intake and exhaust thermal control system for implementing HCCI (homogeneous charge compression ignition) combustion of a gasoline engine. The system comprises an air intake pipeline, an air exhaust pipeline and an air exhaust-intake heat exchanger, wherein the heat exchanger is filled with heat storage materials; the air intake pipeline, the air exhaust pipeline and a bypass are respectively provided with an electrically operated valve; the pipelines are provided with a plurality of temperature sensors; the electrically operated valves and the temperature sensors are connected with a controller; and the controller comprises a signal conditioning circuit and a driving circuit which are connected with a singlechip and are used for implementing the thermal control of air intake and air exhaust. The device provided by the invention has the heat storage capability of the heat exchanger, reasonable storage and release of air exhaust heat can be realized. When the gasoline engine operates at medium and large load, the storage and accumulation of surplus air exhaust heat in the heat exchanger can be realized, and the device is used for heating the intake air when the gasoline engine operates at low load, the problem that the air exhaust heat is insufficient to heat the intake air at low load is solved, the requirement of air exhaust-intake heat exchange efficiency is lowered, and the device can be practically applied to the HCCI combustion of the gasoline engine.

Description

Inlet and exhaust heat control device and method for realizing HCCI combustion of gasoline engine

technical field

The invention relates to an intake and exhaust heat control system of a gasoline engine, in particular to an intake and exhaust heat control system for realizing HCCI combustion of a gasoline engine.

Background technique

The use of Homogeneous Charge Compression Ignition (HCCI) on gasoline engines has higher fuel economy and lower NO _X emission potential. In order to realize the homogeneous compression ignition combustion method of the gasoline engine, it is necessary to compress the oil-air mixture in the cylinder to a high temperature of 1000K near the compression top dead center. Under the condition of not making major changes to the engine body and maintaining the compression ratio of conventional gasoline engines, heating the intake air of the engine is a main way to realize HCCI combustion of gasoline engines. Since the exhaust gas of the engine has relatively high heat, a heat exchanger is used to realize the heat exchange between the exhaust gas and the intake air, so as to increase the temperature of the intake air of the engine, which becomes a better way to realize HCCI combustion of gasoline engines without additional energy consumption plan.

In the document SAE2000-01-2869, the Lawrence Livermore National Laboratory of the United States used the exhaust-intake heat exchanger to meet the requirements of HCCI combustion on the intake air temperature under the premise of using the intake boost to increase the temperature. On the one hand, the system relies on the temperature increase brought about by the air intake boost. On the other hand, the test system cannot achieve rapid adjustment of the intake air temperature, that is, it cannot realize the operation of the engine under HCCI combustion transient conditions. Ford Motor Company of the United States used exhaust-intake heat exchange to increase the intake air temperature in documents SAE2002-01-2832, SAE2006-01-1082 and patents US6675579-B1 and US2006150952-A1, and modified the engine intake system to have The cold and hot intake pipes are used to mix the cold and hot intake air in proportion before entering the cylinder to obtain the required intake air temperature and finally achieve HCCI combustion. However, since the exhaust-intake heat exchange capacity is limited by the low efficiency of the air-air heat exchanger, in the actual test process, it will encounter the problem that the heat exchange heat is difficult to meet the intake temperature rise demand, and electric heating must be used device to help increase the intake air temperature. In addition, the HCCI engine of the Ford company mentioned above adopts an unconventional and relatively high compression ratio, which is also to solve the contradiction of insufficient heat exchange heat to heat the intake air to the required temperature to a certain extent. Lund University in Sweden, in the SAE document 2004-01-0943, has built an exhaust-intake thermal management system similar to that of Ford Motor Company in the United States in the research of gasoline engine HCCI combustion, and also expects to use exhaust-intake heat exchange To realize the heating of the intake air of the engine, but also encountered the problem of insufficient heat exchange capacity of the heat exchanger. In the actual test, an electric heating device was also used to increase the intake air temperature.

From the current research status of using exhaust-intake heat exchange to realize gasoline engine HCCI combustion, it can be seen that under the conventional gasoline engine compression ratio, gasoline engine HCCI combustion has a higher demand for intake air temperature, and the exhaust-intake heat exchange Higher requirements are placed on the heat exchange efficiency of the device. As shown in Figure 1, when the engine is working in HCCI mode, the exhaust temperature of the gasoline engine, the intake air temperature that can be achieved after heat exchange, and the intake air temperature required to achieve HCCI combustion are schematic diagrams. It can be seen from Figure 1 that when the gasoline engine is under medium and small loads, especially at low loads, the exhaust temperature of the engine is low, but the intake air temperature required to realize the HCCI combustion mode is higher, and it is difficult for conventional heat exchangers to Make the intake air temperature after heat exchange meet the intake air temperature requirements of HCCI combustion; while in the middle and high load of the gasoline engine, the exhaust temperature of the engine is high, and the temperature requirement for HCCI combustion is low, so the exhaust heat is exchanged with the intake air. There will be more surplus after the heat. It can be seen from the above analysis that if the gasoline engine is to achieve HCCI combustion under all operating conditions, the intake air temperature must meet the intake air temperature requirements of HCCI combustion under various operating conditions. However, when the exhaust gas temperature is low and the load is low, even under the auxiliary effect of the cooling water-intake heat exchange on the intake air temperature, the exhaust-intake heat exchanger must achieve extremely high heat transfer. ability to meet the gasoline engine to achieve HCCI combustion. However, the gas-air heat exchanger itself has the disadvantage of low heat transfer efficiency. It is difficult to optimize the structural parameters of the heat exchanger to greatly improve its heat transfer efficiency. At the same time, it will also bring about negative effects such as increased airflow resistance and increased size. , such a contradiction has led to the fact that the exhaust-intake heat exchanger is difficult to be practically applied to gasoline engine HCCI combustion.

Contents of the invention

In view of the above prior art, the present invention provides an intake and exhaust heat control device and method for realizing HCCI combustion of a gasoline engine. By controlling the intake and exhaust heat of the engine, the exhaust-intake heat exchange can be easily satisfied under various working conditions. Gasoline engine HCCI combustion needs the intake air temperature, especially to solve the problem that the exhaust heat is not enough to heat the intake air to the required temperature when the gasoline engine is lightly loaded, so as to realize the practical application of exhaust-intake heat exchange in gasoline engine HCCI combustion.

In order to solve the above-mentioned technical problems, the technical solution of the intake and exhaust thermal control device for the HCCI combustion of gasoline engines in the present invention is to include exhaust pipelines, intake pipelines and exhaust-intake heat exchangers, and the exhaust pipelines are equipped with There is an exhaust bypass passing through the exhaust-intake heat exchanger, and an intake bypass passing through the exhaust-intake heat exchanger is provided on the intake pipeline; The gas heat exchanger is filled with heat storage material; the exhaust pipeline, the exhaust bypass, the intake pipeline and the intake bypass are respectively provided with an electric valve; the exhaust pipeline is , and an exhaust temperature sensor is arranged upstream of the exhaust bypass, an intake air temperature sensor is arranged on the intake pipeline and downstream of the intake bypass, and the exhaust-intake The heat exchanger is provided with a temperature sensor inside the heat exchanger; the above electric valves, the exhaust temperature sensor, the intake temperature sensor and the internal temperature sensor of the heat exchanger are all connected to a controller; A signal conditioning circuit and a drive circuit, wherein the signal conditioning circuit is connected to the exhaust gas temperature sensor, the intake air temperature sensor and the internal temperature sensor of the heat exchanger, and the signal conditioning circuit is used to process the temperature sensor signal; The drive circuit is connected to the above-mentioned electric valves, and the drive circuit is used to drive the electric valves; the single-chip microcomputer is used for data calculation and logic judgment, that is, the single-chip microcomputer is used for processing according to the processing obtained from the signal conditioning circuit. As a result, the opening and closing and opening states of the above-mentioned electric valves are adjusted, so as to realize the heat control of intake and exhaust.

The present invention realizes the intake and exhaust heat control method of gasoline engine HCCI combustion and comprises the following steps:

Step 1. Perform functional testing on each temperature sensor and each electric valve;

Step 2. Set the intake air temperature corresponding to the current engine working condition according to the map table;

Step 3: The signal conditioning circuit obtains the temperature at the upstream position of the exhaust pipe through the exhaust temperature sensor, and the single-chip microcomputer judges whether the temperature is higher than the temperature of the heat storage material in the exhaust-intake heat exchanger. If "Yes", then The single-chip microcomputer sends an instruction to the drive circuit to open the electric valve on the exhaust bypass and close the electric valve on the exhaust pipeline at the same time; otherwise, vice versa;

Step 4: The signal conditioning circuit obtains the actual temperature at the downstream position of the intake pipe through the intake air temperature sensor, and judges whether the actual temperature meets the set value of the intake air temperature. If "Yes", return to step 2; otherwise, calculate The difference between the actual temperature and the set value, and then use the PID algorithm to obtain the duty ratio required to drive the electric valve of the intake pipeline and the intake bypass, and then the drive circuit drives the intake pipeline and the intake valve according to the above duty ratio. The electric valve of the air bypass acts to make the actual temperature tend to the set value of the intake air temperature;

Step 5, judging whether the system performs the next thermal control cycle, if "yes", return to the above step 2, otherwise, end the thermal control.

Compared with prior art, the beneficial effect of the present invention is:

Compared with the prior art, the present invention adopts a heat exchanger containing heat storage material on the basis of realizing the utilization of exhaust heat and rapid adjustment of intake air temperature, so that the heat exchanger has the ability to store heat , and use the exhaust pipeline and bypass electric valve to adjust whether the exhaust gas flows through the heat exchanger, so as to realize the retention and accumulation of exhaust heat in the heat exchanger, especially in the heavy load condition of the gasoline engine, it can realize the The heat of the gas is accumulated in the heat exchanger; at the same time, the flow of the intake air through the heat exchanger is adjusted through the intake pipeline and the bypass electric valve, which realizes the selective and appropriate utilization of the heat in the heat exchanger, especially in gasoline engines. When the load is small, the heat accumulated in the heat exchanger when the load is large can be fully released and utilized.

It can be seen that due to the heat storage capacity of the heat exchanger, the present invention can realize reasonable storage or release of exhaust heat. In this way, when the gasoline engine is working at a large load, the excess exhaust heat can be stored in the heat exchanger and used for intake air heating at a small load, solving the problem that the exhaust heat is not enough to heat the intake air at a small load, reducing the The demand for exhaust-intake heat exchange efficiency is satisfied, so that the exhaust-intake heat exchange scheme can be practically applied to gasoline engine HCCI combustion.

Description of drawings

Fig. 1 is the schematic diagram of conventional exhaust gas temperature, the intake air temperature after conventional heat exchange and the required intake air temperature for realizing HCCI combustion of gasoline engine under HCCI combustion mode in the prior art;

Fig. 2 is a schematic structural diagram of an intake and exhaust heat control device for realizing gasoline engine HCCI combustion in the present invention;

Fig. 3 is a block diagram of the flow chart of the intake and exhaust heat control method for realizing HCCI combustion of a gasoline engine according to the present invention.

In the picture:

1——heat storage material 2——exhaust-intake heat exchanger

3, 4, 11, 12 - electric valve 5 - exhaust temperature sensor

6——Engine 7——Intake air temperature sensor

8——Intake Electric Heater 9——Internal Temperature Sensor of Heat Exchanger

10 - Controller

Detailed ways

The present invention will be further described in detail below in combination with specific embodiments.

The basic idea of the present invention is to use an exhaust-intake heat exchanger containing heat storage materials, and to install electric valves on the exhaust and intake pipes, and realize the heat transfer in the exhaust by opening and closing the electric valves of the exhaust pipes. Accumulation and storage in the heat exchanger, at the same time, through the adjustment of the opening of the intake pipeline and the bypass electric valve, the intake air can use the heat in the heat exchanger in an appropriate amount.

As shown in Fig. 2, the present invention realizes the intake and exhaust heat control device of gasoline engine HCCI combustion, comprises exhaust pipeline, intake pipeline and exhaust-intake heat exchanger 2, and described exhaust pipeline is provided with a through The exhaust bypass of the exhaust-intake heat exchanger, the intake pipeline is provided with an intake bypass through the exhaust-intake heat exchanger; the exhaust-intake heat exchange The heat storage material 1 is filled in the container 2, and the heat storage material 1 can adopt a high-temperature-resistant sensible heat storage material. Since the phase-change heat storage material can achieve a higher heat storage density, in order to make the exhaust-intake exchange The volume of the heater 2 is small, and the heat storage material 1 is preferably a solid-liquid phase change heat storage material with a phase transition temperature of 400 to 700 degrees, for example, a phase change heat storage material such as Al-Si alloy can be used. The exhaust pipeline, the exhaust bypass, the intake pipeline and the intake bypass are respectively provided with an electric valve; the exhaust pipeline is located upstream of the exhaust bypass An exhaust gas temperature sensor 5 is provided at the intake pipe, an intake air temperature sensor 7 is provided on the intake pipeline and downstream of the intake bypass, and a heat exchange sensor 7 is installed in the exhaust-intake heat exchanger 2 The internal temperature sensor 9 of the device; the above-mentioned electric valves 3, 4, 11, 12 and the exhaust temperature sensor 5, the intake air temperature sensor 7 and the internal temperature sensor 9 of the heat exchanger are all connected to a controller 10; the controller 10 It includes a signal conditioning circuit and a driving circuit connected to a single-chip microcomputer, and the single-chip microcomputer can adopt Infineon's TC1766/TC1793. For the selection of the single-chip microcomputer in the controller, the composition of the signal conditioning circuit and the driving circuit, and the relationship between the three The connection relationships of all belong to the common knowledge known to those skilled in the art, and will not be repeated here. Wherein, the signal conditioning circuit is connected with the exhaust gas temperature sensor 5, the intake air temperature sensor 7 and the internal temperature sensor 9 of the heat exchanger, and the signal conditioning circuit is used for processing the temperature sensor signal; the driving circuit is connected with the The above-mentioned electric valves are connected, and the drive circuit is used to realize the driving of each electric valve; the single-chip microcomputer is used for data calculation and logic judgment, that is, the single-chip microcomputer is used for the above-mentioned electric valves according to the processing results obtained from the signal conditioning circuit. The opening and closing of the valve and the opening state are adjusted to realize the thermal control of the intake and exhaust.

In addition, for the extreme situation that may occur, that is, the engine works under low load conditions for a long time so that the exhaust heat in the heat exchanger is insufficient, it can be located on the intake bypass road and located in the exhaust-intake exchange The downstream of the heater 2 is provided with an intake electric heater 8 . Its main purpose is to turn on the intake electric heater 8 at this moment in order to make the intake air temperature of the engine meet the demand of HCCI combustion under the current working condition when the heat provided by the heat storage heat exchanger is insufficient, and the intake air after heat exchange Carry out heating again to make it meet the intake air temperature requirement of HCCI combustion.

As shown in Fig. 3, the control method using the above-mentioned intake and exhaust heat control device for realizing HCCI combustion of a gasoline engine includes the following steps. Here, a single-cylinder gasoline engine is taken as an example to specifically describe the intake and exhaust heat control:

Step 1. Perform functional testing on each temperature sensor and each electric valve;

Step 2. Set the intake air temperature corresponding to the current engine working condition according to the map table. For example, if the current engine is working at a load whose IMEP is 4bar, check the table and know that the intake air temperature required for the current engine working condition is 230°C;

Step 3: The signal conditioning circuit obtains the temperature at the upstream position of the exhaust pipeline through the exhaust temperature sensor 5, and it can be known that the exhaust temperature is 400°C, and at this time the temperature acquired by the heat storage internal temperature sensor 9 of the heat exchanger is 350°C , the single-chip microcomputer judges that at this time the exhaust gas temperature is higher than the temperature of the heat storage material 1 in the exhaust-intake heat exchanger 2, then the single-chip microcomputer sends a signal to the drive circuit to open the electric valve on the exhaust bypass and close the said exhaust bypass at the same time. The command of the electric valve on the exhaust pipeline makes the engine exhaust flow through the exhaust-intake heat exchanger, so that the exhaust heat is accumulated and stored in the heat exchanger;

Step 4: The signal conditioning circuit obtains the actual temperature at the downstream position of the intake pipe through the intake air temperature sensor 7 as 220°C. The single-chip microcomputer judges that the actual temperature does not meet the set value of the intake air temperature of 230°C, and calculates the actual temperature and The difference between the set values is -10°C, and then use the PID algorithm to obtain the duty ratio required to drive the electric valve of the intake pipeline and the intake bypass, and then the drive circuit drives the intake pipeline according to the above duty ratio. The action of the electric valve and the electric valve of the intake bypass makes the opening of the electric valve of the intake bypass increase appropriately and the opening of the electric valve of the intake pipeline decrease appropriately, so that the actual temperature tends to the set value of the intake air temperature;

Step 5, judging whether the system performs the next heat control cycle, if "yes", return to the above step 2, and continue the heat control, otherwise, end the heat control.

Although the present invention has been described above in conjunction with the drawings, the present invention is not limited to the above-mentioned specific embodiments, and the above-mentioned specific embodiments are only illustrative, rather than restrictive. Under the inspiration, many modifications can be made without departing from the gist of the present invention, and these all belong to the protection of the present invention.

Claims (1)

1. intake and exhaust heat control method of realizing Gasoline Engine HCCI Combustion, the heat control device structure of utilizing is as follows:

Comprise gas exhaust piping, air inlet pipeline and exhaust-air inlet heat exchanger (2), described gas exhaust piping is provided with a discharge bypass through described exhaust-air inlet heat exchanger, and described air inlet pipeline is provided with an air inlet bypass through described exhaust-air inlet heat exchanger; Be filled with heat storage material (1) in described exhaust-air inlet heat exchanger (2); Be provided with respectively a mortor operated valve in described gas exhaust piping, described discharge bypass, described air inlet pipeline and the described air inlet bypass; On the described gas exhaust piping and the upstream end that is positioned at described discharge bypass be provided with exhaust gas temperature sensor (5), on the described air inlet pipeline and the downstream part that is positioned at described air inlet bypass be provided with intake air temperature sensor (7), be provided with heat exchanger internal temperature sensor (9) in described exhaust-air inlet heat exchanger (2); Above-mentioned each mortor operated valve (3,4,11,12) is connected 5 with exhaust gas temperature sensor), intake air temperature sensor (7) and heat exchanger internal temperature sensor (9) all be connected with a controller (10);

Described controller (10) comprises signal conditioning circuit and the drive circuit that is connected with a single-chip microcomputer, wherein, described signal conditioning circuit links to each other with described exhaust gas temperature sensor (5), intake air temperature sensor (7) and heat exchanger internal temperature sensor (9), and described signal conditioning circuit is used for that temperature sensor signal is carried out filtering to be processed; Described drive circuit links to each other with above-mentioned each mortor operated valve, and described drive circuit is used for realization to the driving of each mortor operated valve; Described single-chip microcomputer is used for data calculating and logic is judged, namely described single-chip microcomputer is adjusted switching and the aperture state of above-mentioned each mortor operated valve according to the processing result of obtaining from described signal conditioning circuit, thereby realizes the heat control of intake and exhaust;

It is characterized in that:

Realize the intake and exhaust heat control of Gasoline Engine HCCI Combustion, may further comprise the steps:

Step 1, each temperature transducer and each mortor operated valve are carried out functional detection;

Step 2, set the corresponding intake temperature of present engine operating mode according to the arteries and veins stave;

Step 3, signal conditioning circuit obtain the temperature of gas exhaust piping upstream position by exhaust gas temperature sensor (5), single-chip microcomputer judges whether this temperature is higher than the temperature of exhaust-interior heat storage material of air inlet heat exchanger (2) (1), if "Yes", then single-chip microcomputer sends the instruction that the mortor operated valve of opening on the described discharge bypass also cuts out mortor operated valve on the described gas exhaust piping simultaneously to drive circuit; Otherwise, otherwise;

Step 4, signal conditioning circuit are obtained the true temperature of air inlet pipeline downstream position by intake air temperature sensor (7), judge whether this true temperature satisfies the setting value of intake temperature, if "Yes" is then returned step 2; Otherwise, then calculate the difference of true temperature and setting value, and then utilize pid algorithm to obtain driving into the required dutycycle of mortor operated valve of air pipe and air inlet bypass, moved according to the mortor operated valve that above-mentioned dutycycle drives into air pipe and air inlet bypass by drive circuit again, make the setting value of true temperature trend intake temperature;

Step 5, judge whether system carries out next heat control circulation, if "Yes" is returned above-mentioned steps two, otherwise, finish heat control.

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