JP2015175326A - Engine system and air conditioning device including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve net thermal efficiency of an engine at the time when the temperature of exhaust gas or the temperature of engine oil is within a specific temperature range.SOLUTION: An engine system includes cooling water target temperature adjustment means S3 that switches and adjusts a first target temperature as a target temperature in rating operation operating an engine 10 at a rating and a second target temperature as a target temperature at the time when an oil temperature measured by engine oil temperature measurement means T2 is lower than that in the rating operation or at the time when an exhaust gas temperature measured by exhaust gas temperature measurement means is lower than that in the rating operation, in a mode where the second target temperature is higher than the first target temperature.

Description

  The present invention relates to an engine that compresses and burns an air-fuel mixture in a combustion chamber and outputs shaft power, and a coolant temperature measured by a coolant temperature measuring means that measures the temperature of engine coolant that cools the engine. The present invention relates to an engine system provided with a coolant temperature control means for controlling to a target temperature.

Conventionally, as a gas engine heat pump system (hereinafter, abbreviated as GHP) as an air conditioner that operates a heat pump by driving a compressor with axial power of a gas engine, a technique shown in Patent Document 1 is known.
Usually, in this technology, the engine speed and torque are changed with respect to the air conditioning load, and an operation suitable for the air conditioning load is performed. The operating range of the engine is determined by the compressor specifications of the air conditioner and the air conditioning load, and generally takes the operating range shown in FIG. 6. Normally, the operating range shown in FIG. In the range), control is performed so that the coolant temperature of the engine is kept constant.

JP 2013-068405 A

  The inventors of the present invention control the engine coolant temperature when the engine operates in the operating range shown in FIG. 6, particularly when the exhaust gas temperature or the engine oil temperature is in a specific temperature range. Thus, we have learned that the net thermal efficiency of the engine can be improved.

  The present invention has been made in view of the above-mentioned knowledge, and an object thereof is an engine system capable of improving the net thermal efficiency of an engine when the temperature of exhaust gas or the temperature of engine oil is in a specific temperature range, and It is providing the air conditioner provided with.

In order to achieve the above object, the characteristic configuration of the engine system of the present invention is as follows:
An engine that compresses and burns the air-fuel mixture in the combustion chamber and outputs shaft power;
In an engine system comprising cooling water temperature control means for controlling a cooling water temperature measured by cooling water temperature measurement means for measuring a temperature of engine cooling water for cooling the engine to a target temperature,
The first target temperature as the target temperature of the coolant temperature during rated operation for operating the engine at a rated value, and when the oil temperature measured by the engine oil temperature measuring means is lower than that during the rated operation or exhaust gas temperature measurement The second target temperature as the target temperature of the cooling water temperature when the exhaust gas temperature measured by the means is lower than that during the rated operation is set to be higher than the first target temperature. In the form, it is provided with a cooling water target temperature adjusting means for switching adjustment.

  According to the above characteristic configuration, when the oil temperature is lower than that during rated operation or when the exhaust gas temperature is lower than that during rated operation, the ratio of mechanical loss to the engine shaft power and the increase in pump loss due to the throttle throttle cause the net When the thermal efficiency may be lowered, the net thermal efficiency of the engine can be improved by setting the target temperature of the cooling water temperature to the second target temperature higher than the first target temperature. Note that the net thermal efficiency can be improved in this way, as shown in the graph in the middle of FIG. 2, by increasing the cooling water temperature, the peak value of the heat generation rate dq / dθ in the vicinity of the top dead center is obtained. It is considered that one of the factors is to advance the angle, that is, to accelerate the heat generation that seems to be retarded.

A further characteristic configuration of the engine system of the present invention is as follows.
Oil temperature threshold setting means for setting an oil temperature lower limit threshold in the lower limit region of the engine oil temperature range that does not affect the net thermal efficiency,
When the oil temperature measured by the engine oil temperature measuring unit is lower than the oil temperature lower limit threshold, the cooling water target temperature adjusting unit changes the target temperature of the cooling water temperature from the first target temperature to the second target temperature. The point is to switch to the target temperature.

The inventors of the present invention have further found that the net thermal efficiency can be improved by adjusting the cooling water temperature even when the oil temperature is in a temperature range that does not affect the net thermal efficiency.
That is, according to the above characteristic configuration, the cooling water target temperature adjusting means is configured so that the oil temperature measured by the engine oil temperature measuring means is set to the lower limit region of the engine oil temperature range that does not affect the net thermal efficiency. Since the target temperature of the cooling water temperature is switched from the first target temperature to the second target temperature when the temperature falls below the lower limit threshold, the cooling water temperature is not affected by the net thermal efficiency when viewed from the oil temperature side. By changing the target temperature from the first target temperature to the second target temperature, the net thermal efficiency of the engine can be improved.
Note that the lower limit region of the temperature range of the engine oil that does not affect the net thermal efficiency means that the net thermal efficiency is maintained substantially constant when the relationship between the engine oil temperature and the net thermal efficiency is as shown in FIG. In this example, the oil temperature lower limit threshold is, for example, a range from 55 ° C. to 65 ° C. (indicated by an arrow in FIG. 4). It is assumed that it is set to a value in the range indicated by β.
The oil temperature lower limit threshold varies depending on engine specifications (for example, rated output, engine type, etc.) and parameters such as excess air ratio λ during operation. Based on these parameters, the oil temperature lower limit threshold is appropriately set.

A further characteristic configuration of the engine system of the present invention is as follows.
The cooling water target temperature adjusting means increases from the first target temperature to the second target temperature as the oil temperature measured by the engine oil temperature measuring means deviates to a side lower than the oil temperature lower limit threshold. The temperature range is changed to the larger side.

According to the above characteristic configuration, the cooling water target temperature adjusting means is such that the oil temperature measured by the engine oil temperature measuring means deviates to a lower side than the lower limit of the oil temperature, that is, the oil temperature is lowered and the top dead As the peak value of the heat generation rate near the point is retarded, the temperature increase range from the first target temperature to the second target temperature is changed to the larger side, so the heat generation rate near the top dead center The peak value can be advanced. Thereby, net heat efficiency can be improved in the form which accelerates | stimulates heat generation.
Further, according to this configuration, when it can be estimated that the oil temperature is high and the engine is likely to be warmed up, the temperature of the engine cooling water is adjusted to the low side. Can be avoided appropriately.

A further characteristic configuration of the engine system of the present invention is as follows.
An exhaust gas temperature threshold setting means for setting an exhaust gas temperature lower limit threshold as a determination index for determining that the exhaust gas temperature is lower than that during the rated operation;
The cooling water target temperature adjusting means is configured to switch from the first target temperature to the second target temperature when the exhaust gas temperature measured by the exhaust gas temperature measuring means is lower than the exhaust gas temperature lower limit threshold.

According to the above characteristic configuration, the cooling water target temperature adjusting means adjusts the cooling water temperature when the exhaust gas temperature falls below the exhaust gas temperature lower limit threshold as a determination index for determining that the exhaust gas temperature is lower than during rated operation. The net thermal efficiency of the engine can be improved by changing the target temperature from the first target temperature to the second target temperature.
The exhaust gas temperature lower limit threshold as a determination index for determining that the exhaust gas temperature is lower than that during rated operation is the ratio of the mechanical loss to the engine shaft power and the throttle throttle when the exhaust gas temperature falls below the lower exhaust gas temperature lower threshold. In FIG. 5 showing the exhaust temperature defined by the engine speed and the torque, for example, the threshold value (300 ° C.) indicated by a thick line is used. Since the threshold value varies depending on engine specifications (for example, rated output, engine type, etc.) and parameters such as the excess air ratio λ during operation, in the present invention, the exhaust gas temperature threshold value setting means A configuration in which an exhaust gas temperature lower limit threshold is appropriately set based on parameters is adopted.

A further characteristic configuration of the engine system of the present invention is as follows.
The cooling water target temperature adjustment means sets the set temperature between the first target temperature and the second target temperature as the exhaust gas temperature measured by the exhaust gas temperature measurement means deviates to a side lower than the exhaust gas temperature lower limit threshold. The width is changed to the larger side.

According to the above characteristic configuration, the cooling water target temperature adjusting means is such that the exhaust gas temperature measured by the exhaust gas temperature measuring means deviates to the lower side than the lower limit value of the exhaust gas temperature, that is, the exhaust gas temperature decreases, and the top dead center. As the peak value of the heat generation rate in the vicinity is retarded, the temperature increase range from the first target temperature to the second target temperature is changed to the larger side, so the peak of the heat generation rate in the vicinity of the top dead center Can advance the value. Thereby, net heat efficiency can be improved in the form which accelerates | stimulates heat generation.
Furthermore, when the exhaust gas temperature is high and it can be estimated that the engine is likely to have a high temperature, the engine cooling water temperature is adjusted to the low side. Can be avoided appropriately.

The characteristic configuration of the air conditioner for achieving the above object is as follows:
It has a compressor that compresses refrigerant as a heat pump system,
The shaft power of the engine is used as a drive source for the compressor.

Recent air conditioners display performance based on the year-round energy consumption efficiency (Annual Performance Factor: abbreviated as APF hereinafter) close to the actual operating state. Since the APF is the energy consumption efficiency of the air conditioner throughout the year, increasing the thermal efficiency throughout the year leads to improved performance.
According to the above characteristic configuration, as described above, since the air conditioner is operated using the engine that can improve the net thermal efficiency when the exhaust gas temperature and the oil temperature of the engine are in a specific temperature range, An air conditioner that can be improved can be realized.

Schematic configuration diagram of the engine system according to the first embodiment The graph which shows the change tendency of the parameter of the heat release rate in the vicinity of the top dead center when the cooling water temperature is switched in the engine system according to the first embodiment The graph which shows the net thermal efficiency for every NOx density | concentration in 1st cooling water temperature and 2nd cooling water temperature Graph showing the relationship between net thermal efficiency and oil temperature The graph which shows the relationship between the engine speed and torque of the exhaust gas temperature of the engine system which concerns on 2nd Embodiment. Graph showing the relationship between engine speed and torque in the engine operating range

The engine system 100 and the air conditioner 200 of the present invention can improve the net thermal efficiency (higher heating value: hereinafter abbreviated as HHV) of the engine 10 when the temperature of the exhaust gas E or the temperature of the engine oil is in a specific temperature range. About things.
Hereinafter, embodiments of an engine system 100 and an air conditioner 200 according to the present invention will be described with reference to the drawings.

<First Embodiment>
As shown in FIG. 1, an engine system 100 includes an engine 10 that compresses and burns an air-fuel mixture M in a combustion chamber 11 to output shaft power, a control device S that controls the output of the engine 10 according to a load, and the like. The air conditioner 200 includes a compressor 41 that uses the axial power of the engine 10 as a drive source, a heat pump circuit C1 that circulates refrigerant that is compressed by the compressor 41, and the like. .

Connected to the combustion chamber 11 of the engine 10 are an intake passage 20 for taking in the air-fuel mixture M and an exhaust passage 25 through which the exhaust gas E flows.
A fuel supply path 21 for supplying a fuel gas G such as a natural gas city gas is connected to the intake path 20 via a venturi mixer 23, and a supply amount of the fuel gas G is connected to the fuel supply path 21. A fuel flow rate adjustment valve 22 that can adjust the air-fuel ratio, which is the ratio between the fuel gas G and the combustion air A taken into the intake passage 20, is adjusted. A throttle valve 24 capable of adjusting the intake amount of the air-fuel mixture M flowing through the intake passage 20 is provided on the downstream side of the venturi mixer 23 in the intake passage 20.
Thereby, the fuel gas G supplied from the fuel supply passage 21 in a state where the opening of the fuel flow rate adjustment valve 22 is adjusted is mixed with the combustion air A by the venturi mixer 23 and adjusted to a desired air-fuel ratio. The air-fuel mixture M is taken into the combustion chamber 11 with the intake air amount adjusted by the throttle valve 24.
The sucked air-fuel mixture M is compressed in the combustion chamber 11 and ignited by a spark plug (not shown) to be combusted and expanded, whereby the crankshaft 35 is rotated and shaft power is output. The generated exhaust gas E is exhausted through the exhaust passage 25. That is, the engine 10 is configured as a normal four-cycle engine.

  The engine 10 includes an oil temperature sensor T2 (an example of an oil temperature measuring unit) that measures the oil temperature of an oil pan (not shown) in which engine oil is stored, and is measured by the oil temperature sensor T2. The oil temperature is sequentially acquired by the oil temperature threshold setting means S1 as the control device S.

The engine 10 includes a cooling water circulation path C2 that circulates the engine cooling water JW, a circulation pump P1 that pumps the engine cooling water JW through the cooling water circulation path C2, and a cylinder head and a cylinder block around the combustion chamber 11. A cooling water jacket 52 for allowing the cooling water JW to flow therethrough and a radiator 51 for radiating the heat of the engine cooling water JW are provided.
The cooling water circulation path C2 is provided with a cooling water temperature sensor T1 (an example of cooling water temperature measuring means) that measures the temperature of the engine cooling water JW at the outlet of the cooling water jacket 52. The water temperature control means S4 is configured to control the rotational speed of the heat dissipation fan 51a of the radiator 51 so that the temperature of the engine cooling water JW measured by the cooling water temperature sensor T1 becomes a desired target temperature. It has been adopted.

The shaft power of the engine 10 is transmitted to the compressor 41 of the heat pump system 40 by the power transmission mechanism 30.
The power transmission mechanism 30 includes an engine-side pulley 31 fixed to the crankshaft 35 of the engine 10, a compressor-side pulley 33 connected to a drive shaft 34 of the compressor 41 via an electromagnetic clutch (not shown), A cogged belt 32 wound around the engine side pulley 31 and the compressor side pulley 33 is provided.

The heat pump system 40 includes a heat pump circuit C1 that circulates refrigerant, a compressor 41 that compresses the refrigerant that circulates through the heat pump circuit C1, an outdoor heat exchanger 42 that exchanges heat between outdoor air and the refrigerant, and indoor air and refrigerant. Are configured by an indoor heat exchanger 44 for exchanging heat with each other, an expansion valve 43 for expanding the refrigerant, and a four-way valve 45 for switching the refrigerant circulation direction in the heat pump circuit C1.
When the air conditioner 200 that performs air conditioning by transmitting the shaft power of the engine 10 to the heat pump system 40 performs a cooling operation, the four-way valve 45 is a refrigerant of the compressor 41 as shown by a solid line in FIG. The discharge side is connected to the outdoor heat exchanger 42 and the refrigerant inflow side to the compressor 41 is switched to a state of being connected to the indoor heat exchanger 44.
Thus, the refrigerant circulating in the heat pump circuit C1 is guided to the condenser as the outdoor heat exchanger 42 in a state where the refrigerant is compressed and heated by the compressor 41, and the outdoor air is exchanged with the outdoor air in the condenser as the outdoor heat exchanger 42. After condensing and radiating heat in the form of heat exchange and passing through the expansion valve 43, it is led to the evaporator as the indoor heat exchanger 44, and after evaporating in the form of heat exchange with room air to cool the room air, The refrigerant is returned to the refrigerant inflow side of the compressor 41.
On the other hand, when the air conditioner 200 performs the heating operation, the four-way valve 45 connects the refrigerant discharge side of the compressor 41 to the indoor heat exchanger 44 as shown by a broken line in FIG. It switches to the state which connects the refrigerant | coolant inflow side of 41 to the outdoor heat exchanger 42. FIG.
As a result, the refrigerant circulating in the heat pump circuit C1 is guided to the condenser as the indoor heat exchanger 44 in a state where the refrigerant is compressed and heated by the compressor 41, and the indoor air is exchanged with the indoor air in the condenser as the indoor heat exchanger 44. After condensing in the form of heat exchange and heating the indoor air and passing through the expansion valve 43, it is led to the evaporator as the outdoor heat exchanger 42 and evaporated in the form of heat exchange with the outdoor air to heat from the indoor air Is recovered and then returned to the refrigerant inflow side of the compressor 41.

  The inventors of the present invention have found that the net thermal efficiency of the engine 10 can be improved by controlling the temperature of the engine cooling water JW when the temperature of the engine oil is in a specific temperature range. Hereinafter, a description will be added regarding the configuration for improving the net thermal efficiency of the engine 10 based on the knowledge.

The control device S includes a first target temperature (for example, 70 ° C.) as a target temperature of the coolant temperature JW during rated operation in which the engine 10 is operated at a rated value, and an oil temperature measured by the oil temperature sensor T2. Switching adjustment in a form in which the second target temperature (for example, 80 ° C.) as the target temperature of the coolant temperature JW when the temperature is lower than the rated operation is set to be higher than the first target temperature. Cooling water target temperature adjusting means S3 is provided.
The control device S includes an oil temperature threshold setting unit S1 that sets an oil temperature lower limit threshold as an index for determining whether or not the oil temperature measured by the oil temperature sensor T2 is lower than that during rated operation. . The oil temperature threshold setting means S1 is configured to be able to variably set the oil temperature lower limit threshold based on the specifications of the engine 10 (for example, rated output, engine type, etc.) and parameters such as the set excess air ratio λ. Has been. In the first embodiment, the oil temperature threshold setting means S1 employs an engine 100 with a rated output of 15 kW, and the excess air ratio λ = 1.55 is set as shown in FIG. Furthermore, the lower limit region (the temperature range indicated by the arrow β in FIG. 4) of the engine oil temperature range (the range on the higher temperature side than the straight line α in FIG. 4) that does not affect the net thermal efficiency (HHV: higher heating value): The oil temperature lower limit threshold is set in the temperature range of 56 ° C to 65 ° C.
That is, when the oil temperature measured by the oil temperature sensor T2 is equal to or higher than the oil temperature lower limit threshold set by the oil temperature threshold setting means S1, the cooling water target temperature adjusting means S3 is the first target temperature as the target temperature. (For example, 70 ° C.) is set, and when the oil temperature measured by the oil temperature sensor T2 is lower than the oil temperature lower limit threshold, the second target temperature (for example, 80 ° C.) is set as the target temperature.
The control device S is provided with a storage unit S2 that stores the first target temperature and the second target temperature, and the cooling water target temperature adjusting unit S3 receives the first target temperature and the target temperature from the storage unit S2. The target temperature is switched in the form of reading the second target temperature.
The cooling water temperature control means S4 is arranged so that the cooling water temperature measured by the cooling water temperature sensor T1 provided in the cooling water circuit C1 becomes the second target temperature switched by the cooling water target temperature adjusting means S3. That is, the rotational speed of the heat dissipating fan 51a of the radiator 51 is controlled to the lower side so that the cooling water temperature rises.

Next, the oil temperature measured by the oil temperature sensor T2 is 62.4 ° C. in a state where the rotational speed of the engine 10 is maintained at 550 min ⁻¹ , the torque is 50 to 55 Nm, and the excess air ratio λ is 1.55. Table 1, FIG. 2 and FIG. 3 show the results when the target temperature of the engine coolant JW is changed from the first target temperature (70 ° C.) to the second target temperature (80 ° C.).

As shown in Table 1, when the cooling water temperature is raised from the first target temperature (70 ° C.) to the second target temperature (80 ° C.), the net thermal efficiency (HHV) is 26.4% to 26.9. It can be seen that the mechanical efficiency is also improved from 80. 0% to 80.3%.
Here, paying attention to the oil temperature, when the temperature of the engine coolant JW is maintained at the first target temperature (70 ° C.), the oil temperature that is 62.4 ° C. becomes the second target temperature (80 ° C.). When changed, the temperature is raised to 68.5 ° C. Referring to FIG. 4, it can be seen that these oil temperatures are all in a temperature region that does not affect the net thermal efficiency (HHV) (a region on the higher temperature side than the straight line α in FIG. 4). From this and the results shown in Table 1, even when the oil temperature is in a temperature range that does not affect the net thermal efficiency (HHV), the temperature of the engine coolant JW is changed from the first target temperature (70 ° C.) to the second target temperature. It turns out that a net thermal efficiency (HHV) can be improved by switching to temperature (80 degreeC).

  Thus, regarding the reason why the net thermal efficiency (HHV) can be improved, as shown in the graph of FIG. 2, the temperature of the engine coolant JW is set to the first target temperature (70 ° C.) and the second target temperature (80 C.), the heat generation rate dq / dθ is also faster, and it can be said that the combustibility of the air-fuel mixture M in the combustion chamber 11 is higher, which increases the net thermal efficiency (HHV). It is thought that there is.

In the air conditioner 200 including the gas engine heat pump system, it is preferable to reduce the concentration of NOx contained in the exhaust gas E. With respect to this point of view, FIG. 3 is a graph in which the cooling water temperature is the first target temperature (70 ° C.) when the horizontal axis represents the NO2 emission value converted to O2 and the vertical axis represents the net thermal efficiency (HHV). And a graph in which the cooling water temperature is the second target temperature (80 ° C.). From the graph of FIG. 3, when the NOx emission amount is the same, the NOx emission amount (O ₂ ) is greater when the cooling water temperature is set to the second target temperature (80 ° C.) than the first target temperature (70 ° C.). In this sense, it can be said that the environmental load can be reduced.

Second Embodiment
In the engine system 100 and the air conditioner 200 according to the first embodiment, the cooling water target temperature adjusting unit S3 adjusts the target temperature of the engine cooling water JW based on the measured temperature of the oil temperature sensor T2. Indicated.
In the engine system 100 and the air conditioner 200 according to the second embodiment, the cooling water target temperature adjusting unit S3 measures an exhaust gas temperature sensor (not shown) that measures the temperature of the exhaust gas E flowing through the exhaust passage 25. It is characterized in that the target temperature of the engine coolant W is adjusted based on the temperature. Since the configuration other than the feature is not different from the first embodiment, the schematic configuration diagram of the apparatus is omitted, and the same configuration as the first embodiment is denoted by the same reference numeral as the first embodiment. I will do it.

The air conditioner 200 according to the second embodiment includes an exhaust gas temperature sensor (not shown) that measures the temperature of the exhaust gas E in the exhaust passage 25, and the control device S has a rated operation that operates the engine 10 at a rated value. As the target temperature of the cooling water temperature JW when the exhaust gas temperature measured by the exhaust gas temperature sensor is lower than that during rated operation, the first target temperature (for example, 70 ° C.) as the target temperature of the cooling water temperature JW at the time The second target temperature (for example, 80 ° C.) is provided with cooling water target temperature adjusting means S3 for switching and adjusting the second target temperature to be higher than the first target temperature.
The control device S includes exhaust gas temperature threshold setting means for setting an exhaust gas temperature lower limit threshold as an index for determining whether or not the exhaust gas temperature measured by the exhaust gas temperature sensor is lower than during rated operation. The exhaust gas temperature threshold setting means is configured to be able to variably set the exhaust gas temperature lower limit threshold based on the specifications of the engine 10 (for example, rated output, engine type, etc.) and parameters such as the set excess air ratio λ. ing.
In the second embodiment, an engine 100 with a rated output of 15 kW is adopted, and the excess air ratio λ = 1.55 is set. In this case, the exhaust gas temperature is as shown in FIG. Showing change. In the second embodiment, the exhaust gas temperature threshold value setting means, as shown in FIG. 5, is an exhaust gas temperature lower limit threshold value (threshold value indicated by a thick line in FIG. , 300 ° C.).
That is, when the exhaust gas temperature measured by the exhaust gas temperature sensor is equal to or higher than the exhaust gas temperature lower limit threshold set by the exhaust gas temperature threshold setting unit, the cooling water target temperature adjusting unit S3 uses the first target temperature (for example, , 70 ° C.), and when the exhaust gas temperature measured by the exhaust gas temperature sensor is lower than the exhaust gas temperature lower limit threshold, a second target temperature (for example, 80 ° C.) is set as the target temperature.
As in the first embodiment, the control device S is provided with a storage unit S2 that stores the first target temperature and the second target temperature, and the cooling water target temperature adjusting unit S3 stores the storage target S3. The target temperature is switched in such a manner that the first target temperature and the second target temperature are read from the part S2.
The cooling water temperature control means S4 is arranged so that the cooling water temperature measured by the cooling water temperature sensor T1 provided in the cooling water circuit C1 becomes the second target temperature switched by the cooling water target temperature adjusting means S3. That is, the rotational speed of the heat dissipating fan 51a of the radiator 51 is controlled to the lower side so that the cooling water temperature rises.

<Another embodiment>
(1) In the above embodiment, an example in which the first target temperature and the second target temperature are set to 70 ° C. and 80 ° C., respectively, is shown as the target temperature of the engine coolant JW. Is an example, and can be appropriately changed as long as the second target temperature has a higher relationship than the first target temperature.
If description is added, in the said embodiment, each of 1st target temperature and 2nd target temperature as target temperature of engine cooling water JW shows the example which is a fixed value memorize | stored in memory | storage part S2. It was.
However, the first target temperature and the second target temperature may be variably set according to the measurement result of the oil temperature sensor T2 or the measurement result of the exhaust gas temperature sensor (not shown). .
For example, the cooling water target temperature adjusting means S3 detects the exhaust gas measured by the exhaust gas temperature sensor (not shown) as the oil temperature measured by the oil temperature sensor T2 deviates to the side lower than the oil temperature lower limit threshold. You may employ | adopt the structure which changes and sets the setting temperature width of 1st target temperature and 2nd target temperature to the large side, so that temperature deviates to the side lower than an exhaust gas temperature lower limit threshold value.
Thereby, when it is estimated that the temperature of the engine 10 is low and the amount of decrease in the net thermal efficiency of the engine 10 is large, by shifting the temperature of the engine coolant JW led to the engine 10 to the high temperature side, The effect of improving the net thermal efficiency can be expected.

(2) In the second embodiment, the exhaust gas temperature threshold setting means has shown an example in which the exhaust gas temperature lower limit threshold is set to 300 ° C. However, also in the second embodiment, the exhaust gas temperature lower limit threshold is It is preferable to configure so as to variably set based on specifications (for example, rated output, engine type, etc.) and parameters such as a set excess air ratio λ.

  An engine system of the present invention and an air conditioner equipped with the engine system can improve the net thermal efficiency of the engine when the temperature of exhaust gas or the temperature of engine oil is in a specific temperature range, and the air conditioner equipped with the same As such, it can be used effectively.

10: Engine 11: Combustion chamber 40: Heat pump system 41: Compressor 100: Engine system 200: Air conditioner E: Exhaust gas JW: Engine cooling water S1: Oil temperature threshold setting means S3: Cooling water target temperature adjusting means S4: Cooling water Temperature control means T1: Cooling water temperature sensor T2: Oil temperature sensor

Claims (6)

An engine that compresses and burns the air-fuel mixture in the combustion chamber and outputs shaft power;
In an engine system comprising cooling water temperature control means for controlling a cooling water temperature measured by cooling water temperature measurement means for measuring a temperature of engine cooling water for cooling the engine to a target temperature,
The first target temperature as the target temperature of the coolant temperature during rated operation for operating the engine at a rated value, and when the oil temperature measured by the engine oil temperature measuring means is lower than that during the rated operation or exhaust gas temperature measurement The second target temperature as the target temperature of the cooling water temperature when the exhaust gas temperature measured by the means is lower than that during the rated operation is set to be higher than the first target temperature. An engine system comprising cooling water target temperature adjusting means for switching and adjusting in a form. Oil temperature threshold setting means for setting an oil temperature lower limit threshold in the lower limit region of the engine oil temperature range that does not affect the net thermal efficiency,
When the oil temperature measured by the engine oil temperature measuring unit is lower than the oil temperature lower limit threshold, the cooling water target temperature adjusting unit changes the target temperature of the cooling water temperature from the first target temperature to the second target temperature. The engine system according to claim 1, wherein the engine system is switched to a target temperature.   The cooling water target temperature adjusting means increases from the first target temperature to the second target temperature as the oil temperature measured by the engine oil temperature measuring means deviates to a side lower than the oil temperature lower limit threshold. The engine system according to claim 2, wherein the temperature range is changed and set to a larger side. An exhaust gas temperature threshold setting means for setting an exhaust gas temperature lower limit threshold as a determination index for determining that the exhaust gas temperature is lower than that during the rated operation;
The cooling water target temperature adjusting means switches from the first target temperature to the second target temperature when the exhaust gas temperature measured by the exhaust gas temperature measuring means is lower than the exhaust gas temperature lower limit threshold. The engine system described.   The cooling water target temperature adjustment means sets the set temperature between the first target temperature and the second target temperature as the exhaust gas temperature measured by the exhaust gas temperature measurement means deviates to a side lower than the exhaust gas temperature lower limit threshold. The engine system according to claim 4, wherein the width is changed and set to a larger side. It has a compressor that compresses refrigerant as a heat pump system,
The air conditioner according to any one of claims 1 to 5, wherein shaft power of the engine is used as a drive source of the compressor.

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