JP2014181658A - Engine drive-type air conditioning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an engine drive-type air conditioning device capable of reducing a discharge amount of NOx to the external in changing a combustion state from lean burn to stoichiometric combustion.SOLUTION: Before changing a combustion state of an air-fuel mixture in a combustion chamber 101a of an engine 10 from lean burn to stoichiometric combustion, engine output is lowered. Accordingly, the combustion state is changed from lean burn to stoichiometric combustion in a state of lowering the engine output. By lowering the engine output, an amount of NOx discharged from the combustion chamber 101a can be reduced, thus the amount of NOx discharged to the external can be reduced. Further a discharge amount of NOx to the external can be also reduced in changing a combustion state from lean burn to stoichiometric combustion, even in using an engine in which a fuel and air are mixed by a mixer and an opening of a fuel valve is adjusted by a fuel valve motor.

Description

  The present invention relates to an engine-driven air conditioner.

  Generally, the combustion state of the air-fuel mixture in the combustion chamber of an engine used in an engine-driven air conditioner is changed according to the air conditioning load. When the air conditioning load is small, the combustion state is lean burn (lean combustion), and when the air conditioning load is large, the combustion state is stoichiometric combustion. The engine operation when the combustion state is lean burn is called lean operation, and the engine operation when the combustion state is stoichiometric combustion is called stoichiometric operation.

  By the way, a three-way catalyst is often used as a catalyst for purifying exhaust gas from an engine. When the three-way catalyst is used, the NOx purification rate in the exhaust gas during the stoichiometric operation is high, but the NOx purification rate in the exhaust gas during the lean operation is low. However, the amount of NOx originally discharged during lean operation is small.

  Further, since the excess air ratio λ of the air-fuel mixture in the combustion chamber is high during the lean operation, a large amount of oxygen is contained in the exhaust gas. Oxygen in the exhaust gas is temporarily stored in the three-way catalyst. When the combustion state is changed from lean burn to stoichiometric combustion in a state where oxygen is temporarily stored in the three-way catalyst, the stored oxygen prevents the NOx reduction action. For this reason, immediately after switching from lean burn to stoichiometric combustion, the amount of NOx emission temporarily increases.

  Patent Documents 1 and 2 describe a technique for switching from lean burn to fuel-rich combustion and then switching to stoichiometric combustion when changing the combustion state of the air-fuel mixture in the combustion chamber of the vehicle engine from lean burn to stoichiometric combustion. Disclose. When switching from lean burn to fuel rich combustion, the amount of HC and CO contained in the exhaust gas increases. Oxygen stored in the three-way catalyst during lean operation is consumed by the increased HC and CO. NOx is reduced by the amount of oxygen consumed. That is, when the combustion state is changed from lean burn to stoichiometric combustion, the amount of oxygen stored in the three-way catalyst is reduced by temporarily creating a fuel-rich state. For this reason, more NOx is reduced by the three-way catalyst. As a result, NOx emissions are reduced.

JP-A-10-103130 JP 2002-97978 A

(Problems to be solved by the invention)
Since the vehicle engine described in Patent Documents 1 and 2 supplies fuel by an injector and the fuel supply amount can be changed instantaneously, the combustion state of the air-fuel mixture in the combustion chamber is instantaneously changed from lean burn to fuel rich combustion. Can be changed. On the other hand, when a mixer is used for mixing fuel and air, the fuel supply amount is changed by changing the opening degree of the fuel valve interposed in the fuel supply pipe with the fuel valve motor. When the operating speed of the fuel valve motor is made very fast, problems such as step-out and hunting of the engine speed are induced, so the fuel valve motor cannot be operated so fast. For this reason, it takes time to change from lean burn to stoichiometric combustion (or fuel-rich combustion).

  FIG. 13 is a graph showing changes in the NOx and CO purification rates with respect to the excess air ratio λ when a three-way catalyst is used. The horizontal axis in FIG. 13 is the excess air ratio λ, and the vertical axis is the purification rate (%). In FIG. 13, the graph represented by the curve C1 is a graph showing the change in the NOx purification rate, and the graph represented by the curve C2 is a graph showing the change in the CO purification rate. In addition, the hatched region in the graph represents a region where the NOx and CO purification rates of the three-way catalyst are both high, that is, a region where the effect of using the three-way catalyst is noticeable. As shown in FIG. 13, when the excess air ratio λ is about 1.5, that is, when the combustion state is lean burn, the NOx purification rate is low as represented by the point P1 in FIG. However, in this case, the amount of NOx discharged from the combustion chamber is small (for example, 500 ppm). On the other hand, when the excess air ratio λ is in the vicinity of 1.0, that is, when the combustion state is stoichiometric combustion, the NOx purification rate is very high as represented by the point P2 in FIG. Therefore, in any case, the amount of NOx discharged to the outside is small.

  When an engine of a type in which the fuel supply amount is changed by driving the fuel valve motor is used, as described above, since the time until the combustion state is changed from lean burn to stoichiometric combustion is long, the excess air ratio λ However, the combustion time (hereinafter referred to as “intermediate combustion”) in a state where the excess air ratio is lower than that during lean burn and higher than the excess air ratio during stoichiometric combustion is also long. The NOx purification rate during intermediate combustion is represented, for example, at the position of point P3 in FIG. At the point P3, the NOx purification rate is quite low. In addition, since a relatively large amount of fuel is supplied to the combustion chamber during intermediate combustion, the amount of NOx discharged from the combustion chamber is considerably larger than that during lean operation (for example, 2500 ppm). In other words, during intermediate combustion, the amount of NOx discharged from the combustion chamber is large and the NOx purification rate by the three-way catalyst is low, so the amount of NOx discharged to the outside is very large.

  According to Patent Documents 1 and 2 described above, since the fuel supply amount is controlled by the injector, when the combustion state is changed from lean burn to stoichiometric combustion, the period during which the combustion state is intermediate combustion is very short. . However, when the fuel supply amount is controlled by a fuel valve motor or the like, since the period during which the combustion state is intermediate combustion is long as described above, a large amount of NOx is discharged during this period.

  An object of the present invention is to provide an engine-driven air conditioner that reduces the amount of NOx discharged to the outside when the combustion state is changed from lean burn to stoichiometric combustion.

(Means for solving the problem)
The present invention includes a compressor that sucks refrigerant and compresses and discharges the sucked refrigerant, and a combustion chamber formed therein, in which fuel is supplied and a mixture of the supplied fuel and air is supplied in the combustion chamber. An engine configured to be able to operate the compressor by burning, a control device for controlling the combustion state of the air-fuel mixture in the combustion chamber by controlling the amount of fuel supplied to the engine, The control device includes a combustion state change determining unit that determines whether or not to change the combustion state of the air-fuel mixture in the combustion chamber from lean burn to stoichiometric combustion, and the combustion state change determining unit determines whether the combustion state is changed from lean burn. When it is decided to change to stoichiometric combustion, an output control unit that controls the engine output so that the engine output decreases, and after the engine output is reduced by the output control unit Combustion state has a fuel supply amount controller for controlling the supply amount of the fuel supplied to the engine so as to be changed from the lean-burn to the stoichiometric combustion, to provide an engine-driven air conditioning system.

  In this case, the engine includes a fuel supply pipe for supplying fuel to the combustion chamber, an exhaust pipe for exhausting exhaust gas generated in the combustion chamber, and a fuel valve with a variable opening interposed in the middle of the fuel supply pipe. A fuel valve motor connected to the fuel valve and configured to change the opening degree of the fuel valve, and a three-way catalyst provided in the middle of the exhaust pipe may be provided. The fuel supply amount control unit may control the amount of fuel supplied to the engine by driving the fuel valve motor to control the opening of the fuel valve.

  According to the present invention, when the combustion state in the combustion chamber of the engine is changed from lean burn to stoichiometric combustion, the engine output is reduced in advance. Therefore, the combustion state is changed from lean burn to stoichiometric combustion while the engine output is reduced. For this reason, the engine output is low during intermediate combustion until the combustion state shifts from lean burn to stoichiometric combustion. Here, there is a correlation between the engine output and the amount of NOx discharged from the combustion chamber, that is, the lower the engine output, the smaller the amount of NOx discharged. Therefore, by reducing the engine output, the amount of NOx discharged from the combustion chamber during intermediate combustion can be reduced, and therefore the amount of NOx discharged outside during intermediate combustion is also reduced. Therefore, even when using an engine that controls the fuel supply amount by adjusting the opening of the fuel valve by driving the fuel valve motor, NOx is discharged outside when the combustion state is changed from lean burn to stoichiometric combustion. The amount can be reduced.

  The output control unit reduces the output of the engine by reducing the power of the compressor when the combustion state change determining unit determines to change the combustion state from lean burn to stoichiometric combustion. There should be. By reducing the power of the compressor, the output of the engine that operates the compressor is also reduced. For this reason, the amount of NOx discharged to the outside when the combustion state is changed from lean burn to stoichiometric combustion can be reduced.

  Further, the engine-driven air conditioner of the present invention has a condenser that flows in the refrigerant discharged from the compressor, condenses the refrigerant that has flowed in, a condenser fan that blows air to the condenser, and an air flow rate of the condenser fan. It is good to provide the ventilation volume change apparatus comprised so that it could change, and the discharge flow rate change means comprised so that the discharge flow volume of the refrigerant | coolant which a compressor discharges could be changed. When the combustion state change determining unit determines that the combustion state is to be changed from lean burn to stoichiometric combustion, the output control unit controls the blower amount changing device so that the blower amount of the condenser fan is increased, and discharge is also performed. It is preferable to reduce the engine output by controlling the discharge flow rate changing means so that the flow rate decreases.

  According to this, the condensation of the refrigerant in the condenser is promoted by increasing the air flow rate of the condenser fan. When the condensation of the refrigerant is promoted, the amount of the phase change of the refrigerant from gas to liquid increases, so that the volume of the refrigerant decreases. Reducing the volume of the refrigerant reduces the refrigerant pressure, resulting in a reduction in compressor power. Further, by reducing the flow rate (discharge flow rate) of the refrigerant discharged from the compressor, the load acting on the compressor is reduced and the compressor power is reduced. Since the compressor power is thus reduced, the engine output is also reduced.

  In this case, the output control unit, after the combustion state change determining unit determines to change the combustion state from lean burn to stoichiometric combustion, after controlling the air flow amount changing device so that the air flow rate of the condenser fan is increased, It is preferable to control the discharge flow rate changing means so that the discharge flow rate increases. It takes some time for the compressor power to be reduced due to the increase in the blower volume of the condenser fan. On the other hand, if the discharge flow rate of the compressor is reduced, the compressor power is immediately reduced. Therefore, the compressor power can be sufficiently reduced when the combustion state is changed by increasing the air flow rate of the condenser fan first.

  In addition, when the combustion state change determining unit determines that the combustion state is to be changed from lean burn to stoichiometric combustion, the control device sets the ignition timing so that the ignition timing for the air-fuel mixture in the combustion chamber is delayed from the normal ignition timing region. It is preferable to have an ignition timing control unit that changes the angle to the retard side. The fuel supply amount control unit determines that the combustion state change determination unit changes the combustion state from lean burn to stoichiometric combustion, and after the ignition timing control unit changes the ignition timing to the retard side, the combustion state changes to lean burn. It is preferable to control the amount of fuel supplied to the engine so as to change from stoichiometric combustion to stoichiometric combustion. It is known that when the ignition timing for the air-fuel mixture in the combustion chamber of the engine is changed to the retard side than usual, the NOx emission amount decreases. For this reason, according to the present invention, when the combustion state is changed from lean burn to stoichiometric combustion, the amount of NOx emission can be further reduced.

  In the above invention, the “normal ignition timing” is an ignition timing when ignition of the air-fuel mixture in the combustion chamber is controlled so that the efficiency (COP or APF) of the engine-driven air conditioner is improved. For example, the ignition timing during stoichiometric operation is 13 ° to 30 °, and the ignition timing during lean operation is 22 ° to 30 °. Therefore, in the present invention, the ignition timing is preferably less than 13 °, for example, about 8 °.

  In addition, the control device includes a rotation speed setting unit that changes the rotation speed of the engine to a predetermined rotation speed when the combustion state change determination unit determines to change the combustion state from lean burn to stoichiometric combustion. Is good. When the combustion state change determining unit determines that the combustion state is to be changed from lean burn to stoichiometric combustion, the ignition timing control unit determines whether the ignition timing is changed after the engine speed is changed to the set engine speed. It is preferable to change the ignition timing to the retarded angle side so that the ignition timing is delayed from the normal ignition timing region. In this case, the set rotational speed does not cause engine stall when the ignition timing is changed to an ignition timing later than the normal ignition timing region by the ignition timing control unit, and the combustion state is changed from lean burn to stoichiometric combustion. It is preferable that the engine speed be a predetermined speed so that the engine speed does not become too high and abnormal vibration occurs.

  According to this, when changing the combustion state from lean burn to stoichiometric combustion, the engine speed is controlled to the set speed. Therefore, it is possible to prevent engine stall when the ignition timing is controlled so as to delay the ignition timing after that, and after that, the combustion state is changed from lean burn to stoichiometric combustion, resulting in an increase in the fuel ratio. Is blown up to increase the engine speed, thereby preventing abnormal vibrations.

It is the schematic which shows the structure of the engine drive type air conditioner which concerns on embodiment of this invention. It is a figure which shows schematic structure of an engine. It is a block diagram which shows a part of functional structure of a control apparatus. It is a flowchart showing the combustion state change determination process routine which a combustion state change determination part performs. It is a flowchart showing the output control processing routine which an output control part performs. It is a flowchart showing the rotation speed control processing routine which a rotation speed setting part performs. It is a flowchart showing the ignition timing control processing routine which an ignition timing control part performs. It is a flowchart showing the fuel supply amount control processing routine which a fuel supply amount control part performs. It is a flowchart showing the stoichiometric return control processing routine which a stoichiometric return control part performs. It is a graph which shows the relationship between the engine output of an engine, and the density | concentration of NOx exhausted. It is a graph which shows the time change of the NOx density | concentration discharged | emitted outside when changing a combustion state from lean burn to stoichiometric combustion. It is the schematic which shows the structure of the engine drive type air conditioner which concerns on a modification. It is a graph which shows the change of the purification rate of NOx and CO with respect to excess air ratio (lambda) in the case of using a three way catalyst.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram illustrating a configuration of an engine-driven air conditioner 1 according to the present embodiment. As shown in FIG. 1, the engine-driven air conditioner 1 includes an engine 10, a compressor 12, an indoor heat exchanger 13 installed indoors, an outdoor heat exchanger 14 installed outdoor, and a refrigerant. An expansion valve 15, an oil separator 16, a four-way switching valve 17, an accumulator 18 for separating the refrigerant into gas and liquid, indoor fans 131 and 131, indoor fan motors 132 and 132, outdoor fans 141 and 141, The outdoor fan motors 142 and 142 and the control device 20 are provided.

  The compressor 12 operates by receiving power from the engine 10. The compressor 12 has a suction port 12a and a discharge port 12b. When operated, the compressor 12 sucks refrigerant from the suction port 12a and compresses the sucked refrigerant and discharges it from the discharge port 12b.

  One end of the refrigerant discharge pipe 121 is connected to the discharge port 12 b of the compressor 12. Further, one end of the refrigerant suction pipe 122 is connected to the suction port 12 a of the compressor 12. The other end of the refrigerant discharge pipe 121 is connected to the refrigerant inlet 16 a of the oil separator 16. The oil separator 16 separates the lubricating oil from the flowing refrigerant. The separated oil flows out of the oil separator 16 from the oil discharge port 16 b and flows into the oil discharge pipe 161. The oil discharge pipe 161 is connected to the refrigerant suction pipe 122. The refrigerant from which the oil is separated by the oil separator 16 is discharged from the refrigerant discharge port 16c.

  One end of the first pipe 31 is connected to the refrigerant discharge port 16 c of the oil separator 16. The other end of the first pipe 31 is connected to the four-way switching valve 17. As shown in FIG. 1, the four-way switching valve 17 has four ports (a first port 171, a second port 172, a third port 173, and a fourth port 174). The four-way switching valve 17 includes a heating connection state in which the first port 171 is connected to the second port 172 and the third port 173 is connected to the fourth port 174, the first port 171 is connected to the third port 173, and The connection state can be switched to the cooling connection state in which the second port 172 is connected to the fourth port 174. The first pipe 31 is connected to the first port 171 of the four-way switching valve 17. One end of the second pipe 32 is connected to the second port 172. One end of the third pipe 33 is connected to the third port 173, and one end of the fourth pipe 34 is connected to the fourth port 174.

  The indoor heat exchanger 13 is connected to the other end of the second pipe 32. The outdoor heat exchanger 14 is connected to the other end of the third pipe 33. The indoor heat exchanger 13 and the outdoor heat exchanger 14 are connected by an intermediate pipe 35. The indoor heat exchanger 13 allows the refrigerant to flow into the inside from the second pipe 32 or the intermediate pipe 35, and causes the refrigerant and the ambient air to exchange heat. The outdoor heat exchanger 14 allows the refrigerant to flow into the inside from the intermediate pipe 35 or the third pipe 33, and allows the refrigerant and the outside air to exchange heat. As can be seen from FIG. 1, the expansion valve 15 is interposed in the middle of the intermediate pipe 35. The expansion valve 15 expands the refrigerant passing therethrough.

  The other end of the fourth pipe 34 is connected to the refrigerant inlet 181 of the accumulator 18. The accumulator 18 gas-liquid separates the refrigerant that has flowed from the refrigerant inlet 181 and discharges the separated gas refrigerant from the refrigerant outlet 182. The other end of the refrigerant suction pipe 122 is connected to the refrigerant discharge port 182.

  The indoor fans 131 and 131 are disposed close to the indoor heat exchanger 13 so that the air can be blown to the indoor heat exchanger 13. The outdoor fans 141 and 141 are disposed in the vicinity of the outdoor heat exchanger 14 so as to blow air to the outdoor heat exchanger 14. By blowing air from each fan to each heat exchanger, heat exchange of the refrigerant in each heat exchanger is promoted. Indoor fan motors 132 and 132 are connected to the indoor fans 131 and 131. When the indoor fan motors 132 and 132 are driven, the indoor fans 131 and 131 rotate. The indoor fan motors 132 and 132 are configured so as to be able to change the rotational speed (air flow rate) of the indoor fans 131 and 131. In addition, outdoor fan motors 142 and 142 are connected to the outdoor fans 141 and 141. The outdoor fan motors 142 and 142 are configured so as to be able to change the rotational speed (air flow rate) of the outdoor fans 141 and 141.

  A discharge temperature sensor 41 and a high pressure sensor 42 are attached to the refrigerant discharge pipe 121. The discharge temperature sensor 41 detects the temperature of the refrigerant discharged from the compressor 12 and flowing through the refrigerant discharge pipe 121 (refrigerant discharge temperature Td). The high pressure sensor 42 detects the pressure of the refrigerant flowing through the refrigerant discharge pipe 121 (discharge pressure Pd). An intake temperature sensor 43 and a low pressure sensor 44 are attached to the refrigerant intake pipe 122. The suction temperature sensor 43 detects the temperature of the refrigerant (refrigerant suction temperature Ts) that flows through the refrigerant suction pipe 122 and is sucked into the compressor 12. The low pressure sensor 44 detects the pressure (suction pressure) Ps of the refrigerant that flows through the refrigerant suction pipe 122 and is sucked into the compressor 12. Further, the first heat exchange temperature sensor 45 is attached to a portion near the indoor heat exchanger 13 in the middle of the second pipe 32, and a portion connected to the indoor heat exchanger 13 in the middle of the intermediate pipe 35. The second heat exchange temperature sensor 46 is attached between the portion where the expansion valve 15 is interposed. The first heat exchange temperature sensor 45 detects the temperature (temperature Th1) of the refrigerant (gas refrigerant) flowing into the indoor heat exchanger 13 during heating and flowing out of the indoor heat exchanger 13 during cooling. The second heat exchange temperature sensor 46 detects the temperature (temperature Th2) of the refrigerant (liquid refrigerant) that flows out of the indoor heat exchanger 13 during heating and flows into the indoor heat exchanger 13 during cooling. In addition, a temperature sensor and a pressure sensor may be attached to other parts.

  Further, one end of a bypass pipe 123 is connected to the compressor 12. The other end of the bypass pipe 123 is connected to the refrigerant suction pipe 122. A flow rate control valve 124 having a variable opening is interposed in the middle of the bypass pipe 123. Therefore, the flow rate of the refrigerant flowing in the bypass pipe 123 can be adjusted by changing the opening degree of the flow control valve 124.

  Here, in the present embodiment, a scroll compressor is used as the compressor 12. As is well known, the scroll compressor includes a fixed scroll and a turning scroll inside, and the turning scroll rotates eccentrically without rotating with respect to the fixed scroll. At this time, the volume of the compression chamber formed between the fixed scroll and the orbiting scroll is gradually reduced and moved closer to the center of rotation. Then, the compressed refrigerant is discharged from the discharge port through the discharge hole provided in the bottom plate near the center of the fixed scroll.

  Further, the bypass pipe 123 is connected to the compressor 12 so as to communicate with a compression chamber in the first half of the compression chambers in the scroll compressor. Since the bypass pipe 123 communicates with the refrigerant suction pipe 122, when the flow control valve 124 is open, the compression chamber with which the bypass pipe 123 communicates is not compressed. The compression is not started until the communication between the compression chamber and the bypass pipe 123 is cut off. For this reason, when the flow control valve 124 is opened, substantially a part of the refrigerant that is about to be compressed is returned to the suction port 12a.

  That is, the volume of the refrigerant compressed by the compressor 12 is changed by opening and closing the flow control valve 124. Further, as the opening degree of the flow control valve 124 is increased, the flow rate of the refrigerant returned to the suction port 12a through the bypass pipe 123 increases, and thus the flow rate of the refrigerant discharged from the discharge port 12b decreases. On the contrary, the smaller the opening degree of the flow rate control valve 124, the smaller the flow rate of the refrigerant returned to the suction port 12a through the bypass pipe 123, so the flow rate of the refrigerant discharged from the discharge port 12b increases. To do. That is, the bypass pipe 123 and the flow rate control valve 124 are configured so that the discharge flow rate of the refrigerant discharged from the compressor 12 can be changed.

  The control device 20 is configured by a microcomputer having a CPU, a ROM, a RAM, and the like, and performs control related to the operation of the engine-driven air conditioner 1 (for example, the rotational speed control of the engine 10). The control device 20 is electrically connected to each of the sensors described above and the indoor temperature sensor 47 that detects the indoor temperature, and inputs information detected by these sensors. The control device 20 is electrically connected to the flow control valve 124, and controls the opening degree of the flow control valve 124 by outputting a control signal related to the opening degree to the flow control valve 124. Further, the control device 20 is electrically connected to the indoor fan motors 132 and 132 and the outdoor fan motors 142 and 142, and outputs a control signal related to the air volume to these motors, thereby reducing the energization amount to these motors. Control.

  Next, the air conditioning operation (heating operation, cooling operation) of the engine-driven air conditioner 1 will be briefly described. First, the heating operation will be described. During heating, the four-way switching valve 17 is brought into a heating connection state. When the engine 10 is driven and the compressor 12 is activated during heating, the compressor 12 sucks in the low-pressure gas refrigerant mixed with lubricating oil from the suction port 12a and compresses the gas refrigerant inside. At this time, the lubricating oil lubricates the compressor 12. Then, the compressed high-pressure gas refrigerant is discharged from the discharge port 12b together with the lubricating oil.

  The high-pressure gas refrigerant and lubricating oil discharged from the discharge port 12 b flow through the refrigerant discharge pipe 121 and further flow into the oil separator 16 from the refrigerant inlet 16 a of the oil separator 16. The oil separator 16 separates the lubricating oil from the high pressure gas refrigerant. The lubricating oil separated by the oil separator 16 flows into the oil discharge pipe 161 from the oil discharge port 16b of the oil separator 16, and further flows into the refrigerant suction pipe 122. Then, the air is sucked into the compressor 12 again from the suction port 12 a of the compressor 12. In this way, the lubricating oil repeatedly lubricates the compressor 12.

  The high-pressure gas refrigerant from which the lubricating oil is separated by the oil separator 16 exits the oil separator 16 from the refrigerant discharge port 16 c and flows through the first pipe 31, and enters the four-way switching valve 17 from the first port 171 of the four-way switching valve 17. . During heating, the first port 171 of the four-way switching valve 17 is connected to the second port 172, and the second port 172 is connected to the second pipe 32, so that the four-way switching valve 17 enters from the first port 171. The high-pressure gas refrigerant exits the four-way switching valve 17 from the second port 172, flows through the second pipe 32, and further flows into the indoor heat exchanger 13 ahead. The high-pressure gas refrigerant that has flowed into the indoor heat exchanger 13 is condensed by discharging heat to the indoor air while flowing through the indoor heat exchanger 13. At this time, the indoor air is warmed by the heat discharged from the high-pressure gas refrigerant, and the room is heated.

  The refrigerant that has exhausted heat to the indoor air and has condensed is partially liquefied and flows out of the indoor heat exchanger 13 and flows through the intermediate pipe 35. Then, after being expanded by the expansion valve 15, the pressure is reduced so as to be easily evaporated, and then flows into the outdoor heat exchanger 14. The refrigerant flowing into the outdoor heat exchanger 14 evaporates by taking heat from the outside air while flowing through the outdoor heat exchanger 14.

  A part of the refrigerant evaporated by taking the heat of the outside air is vaporized and flows out of the outdoor heat exchanger 14 and flows through the third pipe 33. Then, the four-way switching valve 17 enters from the third port 173. During heating, the third port 173 of the four-way switching valve 17 is connected to the fourth port 174, and the fourth port 174 is connected to the fourth pipe 34, so that the four-way switching valve 17 enters the third port 173. The refrigerant flows from the fourth port 174 through the four-way switching valve 17 to the fourth pipe 34. The refrigerant flowing through the fourth pipe 34 is introduced into the accumulator 18 from the refrigerant inlet 181 of the accumulator 18. In the accumulator 18, the refrigerant is separated into a liquid refrigerant and a low-pressure gas refrigerant. Only the low-pressure gas refrigerant is discharged from the refrigerant discharge port 182 of the accumulator 18 and flows to the refrigerant suction pipe 122. The refrigerant in the refrigerant suction pipe 122 merges with the lubricating oil flowing from the oil discharge pipe 161, and is sucked into the compressor 12 from the suction port 12a of the compressor 12 together with the lubricating oil.

  Next, the cooling operation will be described. During cooling, the four-way switching valve 17 is brought into a cooling connection state. When the engine 10 is driven during cooling and the compressor 12 is operated, the compressor 12 sucks low-pressure gas refrigerant mixed with lubricating oil from the suction port 12a and compresses the gas refrigerant inside. At this time, the lubricating oil lubricates the compressor 12. Then, the compressed high-pressure gas refrigerant is discharged from the discharge port 12b together with the lubricating oil.

  The high-pressure gas refrigerant and lubricating oil discharged from the discharge port 12 b flow through the refrigerant discharge pipe 121 and further flow into the oil separator 16 from the refrigerant inlet 16 a of the oil separator 16. Lubricating oil separated by the oil separator 16 flows into the oil discharge pipe 161 from the oil discharge port 16b of the oil separator, and further flows into the refrigerant suction pipe 122. Then, the air is sucked into the compressor 12 again from the suction port 12 a of the compressor 12.

  The high-pressure gas refrigerant from which the lubricating oil is separated by the oil separator 16 exits the oil separator 16 from the refrigerant discharge port 16 c and flows through the first pipe 31, and enters the four-way switching valve 17 from the first port 171 of the four-way switching valve 17. . During cooling, the first port 171 of the four-way switching valve 17 is connected to the third port 173, and the third port 173 is connected to the third pipe 33, so that the four-way switching valve 17 enters the first port 171. The gas refrigerant exits the four-way switching valve 17 from the third port 173, flows through the third pipe 33, and further flows into the outdoor heat exchanger 14 ahead. The high-pressure gas refrigerant that has flowed into the outdoor heat exchanger 14 is condensed by discharging heat to the outside air while circulating in the outdoor heat exchanger 14.

  A part of the refrigerant condensed by exhausting heat to the outside air is liquefied and flows out of the outdoor heat exchanger 14 and flows through the intermediate pipe 35. Then, the pressure is reduced so as to be easily evaporated by expansion by the expansion valve 15, and then flows into the indoor heat exchanger 13. The refrigerant flowing into the indoor heat exchanger 13 takes the heat of the indoor air and evaporates while circulating in the indoor heat exchanger 13. At this time, the refrigerant removes heat from the room air, thereby cooling the room air and cooling the room.

  The refrigerant that has evaporated the heat of the indoor air partially vaporized and flows out of the indoor heat exchanger 13 and flows through the second pipe 32. Then, the four-way switching valve 17 enters from the second port 172. During cooling, the second port 172 of the four-way switching valve 17 is connected to the fourth port 174, and the fourth port 174 is connected to the fourth pipe 34, so that the four-way switching valve 17 enters the third port 173. The refrigerant flows from the fourth port 174 through the four-way switching valve 17 to the fourth pipe 34. The refrigerant flowing through the fourth pipe 34 is introduced into the accumulator 18 from the refrigerant inlet 181 of the accumulator 18. In the accumulator 18, the refrigerant is separated into a liquid refrigerant and a low-pressure gas refrigerant. Only the low-pressure gas refrigerant is discharged from the refrigerant discharge port 182 of the accumulator 18 and flows to the refrigerant suction pipe 122. The refrigerant in the refrigerant suction pipe 122 merges with the lubricating oil flowing from the oil discharge pipe 161, and is sucked into the compressor 12 from the suction port 12a of the compressor 12 together with the lubricating oil.

  Thus, during heating, the indoor heat exchanger 13 flows in the refrigerant discharged from the compressor 12 and condenses the refrigerant flowing in, and during cooling, the outdoor heat exchanger 14 converts the refrigerant discharged from the compressor 12 into the refrigerant. It flows in and condenses the refrigerant that flows in. That is, the indoor heat exchanger 13 serves as a condenser during heating, and the outdoor heat exchanger 14 serves as a condenser during cooling. In addition, the flow path through which the refrigerant discharged from the compressor 12 during the air-conditioning operation is sucked into the compressor 12 is referred to as a refrigerant circuit.

  FIG. 2 is a diagram illustrating a schematic configuration of the engine 10. As shown in FIG. 2, the engine 10 is generated in an engine body 101 that forms a combustion chamber 101a therein, an intake pipe 102 that supplies a mixture of fuel and air into the combustion chamber 101a, and a combustion chamber 101a. An exhaust pipe 103 for exhausting exhaust gas, a fuel supply pipe 116 for supplying fuel to the combustion chamber 101a, an air pipe 109 for supplying air to the combustion chamber 101a, a fuel valve 104, a fuel valve motor 105, and a throttle valve 106, a throttle valve motor 107, a mixer 108, and a catalyst device 111. The combustion chamber 101a is formed by a space surrounded by the engine main body 101 and a piston 101b disposed in the engine main body 101 so as to be able to reciprocate. In the present specification, the “engine” includes not only the engine body but also peripheral components around it.

  Fuel (for example, LPG) is supplied to the fuel supply pipe 116 from a fuel supply source (not shown). Further, the fuel supply pipe 116 and the air pipe 109 are merged, and the mixer 108 is provided at the merged portion. In the mixer 108, for example, fuel is mixed with air by the venturi effect. The air-fuel mixture mixed by the mixer 108 is guided to the combustion chamber 101a of the engine body 101 through the intake pipe 102.

  A fuel valve 104 having a variable opening degree is interposed in the middle of the fuel supply pipe 116. A fuel valve motor 105 is connected to the fuel valve 104. The fuel valve motor 105 is configured to change the opening degree of the fuel valve 104. By driving the fuel valve motor 105 and adjusting the opening of the fuel valve 104, the amount of fuel contained in the air-fuel mixture introduced into the combustion chamber 101a is controlled. Therefore, the excess air ratio λ is adjusted by adjusting the opening of the fuel valve 104.

  In addition, a throttle valve 106 having a variable opening degree is interposed in the intake pipe 102. A throttle valve motor 107 is attached to the throttle valve 106. The throttle valve motor 107 is configured to change the opening degree of the throttle valve 106. By controlling the opening degree of the throttle valve 106 by driving the throttle valve motor 107, the flow rate of the air-fuel mixture supplied to the combustion chamber 101a is controlled. The rotational speed of the engine 10 is controlled by controlling the flow rate of the air-fuel mixture.

  An air filter 110 is interposed in the middle of the air pipe 109. Air taken in the air pipe 109 is cleaned by the air filter 110.

  A catalyst device 111 is interposed in the middle of the exhaust pipe 103. A three-way catalyst 111 a is provided in the catalyst device 111. The exhaust flowing through the exhaust pipe 103 is purified by the three-way catalyst 111a. An oxygen sensor 112 is attached to a portion in the middle of the exhaust pipe 103 and upstream of the catalyst device 111. The oxygen sensor 112 detects the oxygen concentration in the exhaust gas flowing into the catalyst device 111. The detected oxygen concentration is input to the control device 20.

  A spark plug 113 is attached to the engine body 101 so that the tip of the combustion chamber 101a is exposed. The spark plug 113 is electrically connected to the control device 20 via an ignition coil 114 and an igniter 115.

  Further, as shown in FIG. 2, the fuel valve motor 105 and the throttle valve motor 107 are electrically connected to the control device 20, and the control device 20 operates the motors, that is, the opening degree of the fuel valve 104 and the throttle valve. The opening degree of the valve 106 is controlled.

  In the engine 10 having such a configuration, the fuel flowing through the fuel supply pipe 116 and the air flowing through the air pipe 109 are mixed by the mixer 108 to generate an air-fuel mixture. The generated air-fuel mixture is guided from the intake pipe 102 to the combustion chamber 101a. The air-fuel mixture is combusted when the spark plug 113 ignites the air-fuel mixture in the combustion chamber 101a. The piston 101b reciprocates due to the energy generated when the air-fuel mixture burns. The reciprocating motion of the piston 101b is converted into a rotational motion. This rotational motion is transmitted to the compressor 12 so that the compressor 12 operates. Further, the exhaust gas generated by the combustion of the air-fuel mixture passes through the exhaust pipe 103 and is purified by the three-way catalyst 111a in the catalyst device 111 and then released to the outside.

  FIG. 3 is a block diagram illustrating a part of the functional configuration of the control device 20. In FIG. 3, only functions necessary for describing the present embodiment are displayed. The control device 20 may be configured to have functions other than the functions shown in FIG.

  As shown in FIG. 3, the control device 20 includes a combustion state determination unit 21, a combustion state change determination unit 22, an output control unit 23, a rotation speed setting unit 24, an ignition timing control unit 25, and a fuel supply amount. A control unit 26 and a stoichiometric return control unit 27 are provided. The combustion state determination unit 21 leans the combustion state of the air-fuel mixture in the combustion chamber 101a of the engine 10 based on information detected by each sensor, the operating capacity calculated based on each detection information, and various other conditions. Decide on burn or stoichiometric combustion. Generally, when the operating capacity is small, that is, when the air conditioning load is small, the combustion state is lean burn, and when the operating capacity is large, that is, when the air conditioning load is large, the combustion state is stoichiometric combustion. The combustion state determination unit 21 outputs a signal S representing the determined combustion state to the combustion state change determination unit 22.

  The combustion state change determination unit 22 performs the combustion state change determination process at predetermined minute intervals when the engine-driven air conditioner 1 is performing the air conditioning operation, thereby mixing the air-fuel mixture in the combustion chamber 101a. It is determined whether or not to change the combustion state from lean burn to stoichiometric combustion. FIG. 4 is a flowchart showing a combustion state change determination processing routine executed by the combustion state change determination unit 22. When the routine shown in FIG. 4 starts, the combustion state change determination unit 22 first inputs a signal S representing the combustion state from the combustion state determination unit 21 in step 11 (hereinafter, step is abbreviated as S) in FIG. To do. Next, it is determined whether or not the combustion state represented by the input signal S is stoichiometric combustion (S12). When it is not stoichiometric combustion, that is, when it is lean burn (S12: No), the combustion state change determining unit 22 ends this routine.

  On the other hand, when the combustion state represented by the input signal S is stoichiometric combustion (S12: Yes), the combustion state change determination unit 22 proceeds to S13, and acquires the signal S_old input last time. Next, it is determined whether or not the combustion state represented by the previously input signal S_old is lean burn (S14). When the combustion state represented by the signal S_old input last time is stoichiometric combustion (S14: No), the combustion state change determining unit 22 determines that the stoichiometric combustion is continuing. In this case, the combustion state change determination unit 22 sets the input signal S to S_old (S17), and thereafter ends this routine.

  When the combustion state represented by the signal S_old input last time is lean burn (S14: Yes), the combustion state change determination unit 22 changes the combustion state determined by the combustion state determination unit 21 from lean burn to stoichiometric combustion. Judge that it has changed. In this case, the combustion state change determining unit 22 proceeds to S15 and determines whether or not the change flag F is set to 0. The change flag F is a flag indicating whether or not the process of changing the combustion state of the engine 10 from lean burn to stoichiometric combustion is being performed. When it is set to 1, the process of changing the combustion state Is being executed, and when it is set to 0, it indicates that the process for changing the combustion state is not being executed. When it is determined in S15 that the change flag F is set to 1 (S15: No), the combustion state change determining unit 22 ends this routine. On the other hand, when the change flag F is set to 0, that is, when the process for changing the combustion state is not yet executed (S15: Yes), the combustion state change determination unit 22 changes the combustion state from lean burn to stoichiometric combustion. Decide to change to. And the signal S1 showing changing a combustion state from lean burn to stoichiometric combustion is output to the output control part 23 (S16). Thereafter, the combustion state change determination unit 22 ends this process.

  When the signal S1 indicating that the combustion state is changed from lean burn to stoichiometric combustion is input, the output control unit 23 executes the output control process so that the output of the engine 10 decreases so that the output of the engine 10 decreases. To control. FIG. 5 is a flowchart showing an output control processing routine executed by the output control unit 23. When the output control routine shown in FIG. 5 is started, the output control unit 23 sets the change flag F to 1 in S21 of FIG. Next, counting by the timer T is started in S22. Next, it is determined whether the current air conditioning operation is a heating operation or a cooling operation (S23). In the case of the heating operation, the output control unit 23 advances the process to S24, and in order to increase the air volume of the indoor fans 131, 131, the indoor fan motors 132, 132 have the maximum air volume of the indoor fans 131, 131. Output a control signal. On the other hand, in the case of the cooling operation, the output control unit 23 advances the process to S25, and in order to increase the air volume of the outdoor fans 141, 141, the outdoor fan motor 142, A control signal is output to 142. Here, the indoor fans 131 and 131 function as a condenser during heating, and the outdoor fans 141 and 141 function as a condenser during cooling. That is, the air flow rate of the fan that blows air to the condenser is increased by the processes of S24 and S25.

  When the amount of fan blown to the condenser is increased by executing the processes of S24 and S25, heat exchange in the condenser is promoted. When heat exchange in the condenser is promoted, liquefaction of the refrigerant is promoted in the condenser. When the refrigerant changes phase from gas to liquid, the volume is greatly reduced, and the pressure is also greatly reduced. That is, when heat exchange in the condenser is promoted, the refrigerant pressure in the refrigerant circuit decreases as a whole. This decrease in pressure can be detected as a decrease in the refrigerant discharge pressure Pd, for example.

  Next, the output control unit 23 determines whether or not 10 seconds have elapsed since the start of the processing of S24 or S25 (S26), and when 10 seconds have elapsed (S26: Yes), the flow control valve 124 is opened. In order to increase the degree, a control signal is output to the flow control valve 124 so that the opening degree of the flow control valve 124 is fully opened (S27). Thereby, the opening degree of the flow control valve 124 is fully opened.

  When the opening degree of the flow control valve 124 increases, the flow rate of the refrigerant returned from the compressor 12 to the suction port 12a of the compressor 12 through the bypass pipe 123 increases. In other words, the flow rate of the refrigerant discharged from the compressor 12 decreases. That is, the process of S27 is a process of controlling the flow control valve 124 so that the discharge flow rate of the refrigerant discharged from the compressor 12 decreases. When the flow rate of the refrigerant discharged from the compressor 12 decreases, the flow rate of the refrigerant flowing through the refrigerant circuit decreases. For this reason, the refrigerant | coolant pressure in a refrigerant circuit falls entirely. This decrease in pressure can be detected as a decrease in the refrigerant discharge pressure Pd, for example.

  That is, the refrigerant pressure in the refrigerant circuit is reduced by executing the processes of S24 and S25 and executing the process of S27. When the refrigerant pressure decreases, the compression work of the compressor 12 decreases, so the compressor power decreases. Since the engine 10 transmits the output commensurate with the compressor power to the compressor 12, when the compressor power decreases, the output of the engine 10 also decreases. That is, the processes of S24, S25, and S27 are processes that reduce the output of the engine 10 by reducing the pressure in the refrigerant circuit.

  Subsequently, the output control unit 23 determines whether or not 10 seconds have elapsed since the start of the process of S27 (S28). When 10 seconds have elapsed (S28: Yes), the output control unit 23 ends the counting by the timer T (S29). Next, an output control completion signal S2 indicating that the output control is completed is output to the rotation speed setting unit 24 (S30). Thereafter, the output control unit 23 ends this routine.

  When the output control completion signal S2 is input from the output control unit 23, the rotational speed setting unit 24 executes the rotational speed setting process, thereby setting the engine rotational speed R of the engine 10 to a preset rotational speed R1. change. FIG. 6 is a flowchart showing a rotation speed setting process routine executed by the rotation speed setting unit 24. When the rotation speed setting process routine shown in FIG. 6 is started, the rotation speed setting unit 24 starts counting by the timer T in S31 of FIG. Next, the rotational speed setting unit 24 outputs a control signal to the throttle valve motor 107 so that the engine rotational speed R of the engine 10 matches the predetermined rotational speed R1 (S32). The throttle valve motor 107 operates in response to a control signal to adjust the opening of the throttle valve 106. As a result, the engine speed R is set to the set speed R1. Here, the set rotational speed R1 means that the engine rotational speed does not stall due to engine ignition timing retarding processing, which will be described later, and the engine rotational speed is the upper limit rotational speed when the combustion state is changed from lean burn to stoichiometric combustion. The number of rotations does not increase above and is determined in advance by experiments or the like. For example, when the engine ignition timing retard processing described later increases the possibility of engine stall at an engine speed of 500 rpm or less, and the upper limit engine speed is 3000 rpm, the set speed R1 can be set to 1200 rpm.

  Next, the rotation speed setting unit 24 determines whether or not 10 seconds have elapsed since the start of the process of S32 (S33). When 10 seconds have elapsed (S33: Yes), the rotation speed setting unit 24 determines that the rotation speed R is set to the set rotation speed R1, and ends the counting by the timer T (S34). Next, a rotation speed setting completion signal S3 indicating that the engine rotation speed R has been set to the set rotation speed R1 is output to the ignition timing control unit 25. Thereafter, the rotation speed setting unit 24 ends this routine.

  The ignition timing control unit 25 executes the ignition timing control process when the rotation number setting completion signal S3 is input from the rotation number setting unit 24, so that the ignition timing to the air-fuel mixture in the combustion chamber is greater than the normal ignition timing region. The ignition timing is changed to the retarded side so that it is also delayed. FIG. 7 is a flowchart showing an ignition timing control processing routine executed by the ignition timing control unit 25. When the ignition timing control processing routine shown in FIG. 7 is started, the ignition timing control unit 25 executes engine ignition timing retardation processing in S41 of FIG. This process is a process for delaying the ignition timing (engine ignition timing) of the air-fuel mixture in the combustion chamber 101a by the spark plug 113. In this embodiment, the ignition timing control unit 25 outputs a control signal to the igniter 115 so that the ignition timing becomes 8 ° in S41. In the present specification, the ignition timing is determined based on an angle corresponding to the position of the piston 101b that reciprocates within the engine body 101. Specifically, when the piston 101b is located at the bottom dead center, the angle is defined as 180 °, and when the piston 101b is located at the top dead center, the angle is defined as 0 °. From 0 to 0 °. Therefore, when the engine ignition timing is 8 °, it is the position immediately before the piston reaches the top dead center from the bottom dead center.

  Incidentally, in both the lean operation and the stoichiometric operation, the ignition timing is advanced (early) than 8 °. The ignition timing range during lean operation is, for example, 18 ° to 30 °, and the ignition timing range during stoichiometric operation is, for example, 13 ° to 25 °. Therefore, the process of S41 is control to make the ignition timing as late as possible. If the ignition timing is made too late, an engine stall occurs regardless of the engine speed. Therefore, in S41, the ignition timing is delayed as much as possible within a range where such an engine stall does not occur.

  In S41, the igniter 115 is controlled so that the change rate of the ignition timing is 1 ° / 10 seconds. That is, the ignition timing changes to the retard side by 1 ° over 10 seconds. In this way, the ignition timing is gradually changed.

  Next, the ignition timing control unit 25 determines whether or not the process of S41 is completed (S42). When the process of S41 is completed (S42: Yes), the ignition timing control unit 25 outputs an ignition timing control completion signal S4 indicating that the control of the ignition timing is completed to the fuel supply amount control unit 26 (S34). . Thereafter, the ignition timing control unit 25 ends this routine.

  When the fuel supply amount control unit 26 receives the ignition timing control completion signal S4 from the ignition timing control unit 25, the fuel supply amount control unit 26 executes the fuel supply amount control process so that the combustion state is changed from lean burn to stoichiometric combustion. The amount of fuel supplied to the engine is controlled. FIG. 8 is a flowchart showing a fuel supply amount control processing routine executed by the fuel supply amount control unit 26. When the fuel supply amount control processing routine shown in FIG. 8 is started, the fuel supply amount control unit 26 starts counting by the timer T in S51 of FIG. Next, the control signal is sent to the fuel valve motor 105 with reference to the base map of the opening at the time of stoichiometric operation so that the opening of the fuel valve 104 is changed from the opening used at the lean operation to the opening used at the stoichiometric operation. (S52). Here, the opening degree of the fuel valve 104 during the lean operation is smaller than the opening degree of the fuel valve 104 during the stoichiometric operation. Therefore, in S41, the fuel valve motor 105 is controlled so that the opening degree of the fuel valve 104 is increased.

  Next, the fuel supply amount control unit 26 determines whether or not 5 seconds have elapsed since the start of the processing of S52 (S53), and when 5 seconds have elapsed (S53: Yes), the fuel supply amount control unit 26 Then, it is determined that the excess air ratio λ has decreased to the excess air ratio during stoichiometric operation. Thereafter, the fuel supply amount control unit 26 refers to the base map of the opening degree of the fuel valve 104 used during the stoichiometric operation, and determines the opening degree of the fuel valve 104 based on the required air conditioning load and the detected value of each sensor. Feedback control is performed (S54).

  After executing the process of S54, the fuel supply amount control unit 26 advances the process to S55 to finish the count by the timer T, and subsequently outputs an opening change completion signal S5 to the stoichiometric return control unit 27. Thereafter, the fuel supply amount control unit 26 ends this routine.

  The stoichiometric return control unit 27 executes a stoichiometric return control process when the opening change completion signal S5 is input from the fuel supply amount control unit 26. FIG. 9 is a flowchart showing a stoichiometric return control processing routine executed by the stoichiometric return control unit 27. When the stoichiometric return control processing routine shown in FIG. 9 is started, the stoichiometric return control unit 27 starts control of the engine speed according to the requested air conditioning load (S61), and according to the requested air conditioning load. Control of the air volume of the condenser fan is started (S62), and the opening degree control of the flow control valve 124 according to the requested air conditioning load is started (S63). That is, control of engine rotation, the fan air volume of the condenser, and the opening degree of the flow control valve 124, which are fixed to a predetermined size, is started.

  Next, the stoichiometric return control unit 27 changes the ignition timing from 8 ° to the ignition timing during the stoichiometric operation (S64). As described above, the ignition timing during the stoichiometric operation is 18 ° to 30 °. Therefore, in the process of S64, the ignition timing is changed to the advance side. At this time, the ignition timing is changed so as to change by 1 ° every 10 seconds.

  Subsequently, the stoichiometric return control unit 27 determines whether or not the change of the ignition timing is completed (S65). When the change of the ignition timing is completed (S65: Yes), the stoichiometric return control unit 27 sets the change flag F to 0 (S66). Thereafter, the stoichiometric return control unit 27 ends this routine.

  As described above, in this embodiment, when the combustion state of the air-fuel mixture in the combustion chamber 101a of the engine 10 is changed from lean burn to stoichiometric combustion, the output control unit 23 executes output control processing in advance. To do. In this process, the flow rate of the condenser fan is maximized in S24 or S25 of FIG. 5, and the opening of the flow control valve 124 is fully opened in S27, thereby reducing the refrigerant pressure in the refrigerant circuit. . As a result, the refrigerant discharge pressure Pd also decreases, and the compressor power of the compressor 12 decreases. As the compressor power decreases, the engine output of the engine 10 is reduced.

  FIG. 10 is a graph showing the relationship between the engine output of the engine 10 and the concentration of exhausted NOx. As shown in FIG. 10, it can be seen that the concentration of exhausted NOx decreases as the engine output decreases. Therefore, when the engine output of the engine 10 is reduced by executing the processes of S24, 25 and S27, the concentration of exhausted NOx is reduced.

  In the present embodiment, the fuel supply amount control unit 26 executes the fuel supply amount control process in a state where the concentration of NOx is reduced. By executing this process (particularly, the process of S52 in FIG. 8), the opening of the fuel valve 104 is changed (increased) to the opening used during the stoichiometric operation. In this case, the combustion state passes the intermediate combustion state as described above before switching from lean burn to stoichiometric combustion. Further, when the fuel supply amount is controlled by mixing the fuel and air using the mixer 108 and adjusting the opening degree of the fuel valve 104 by the fuel valve motor 105 as in this embodiment, the combustion is performed. The time during which the state is an intermediate combustion state is long. Conventionally, the amount (concentration) of NOx discharged from the combustion chamber during intermediate combustion is large, but according to the present embodiment, NOx discharged from the combustion chamber even during intermediate combustion is reduced by reducing the engine output. The amount (concentration) of can be reduced. For this reason, even when the purification rate of NOx by the three-way catalyst 111a is low, the amount of NOx discharged is small, so the amount of NOx discharged to the outside is reduced as compared with the conventional case.

  When the fuel supply amount control unit 26 changes (increases) the opening of the fuel valve 104 in S52, the engine speed increases because the combustion state changes from lean burn to stoichiometric combustion. Therefore, when the engine speed R immediately before changing the opening degree of the fuel valve 104 is high, for example, when the engine speed R is near the rated speed, the engine is changed (increased) by changing (increasing) the opening degree of the fuel valve 104. It may also occur when the rotational speed R exceeds the upper limit rotational speed. In such a case, the engine 10 vibrates abnormally. In this regard, according to the present embodiment, before the fuel supply amount control unit 26 changes (increases) the opening degree of the fuel valve 104, the rotation number setting unit 24 executes the rotation number setting process to execute the engine. The rotation speed R is fixed to the set rotation speed R1. Therefore, even when the opening degree of the fuel valve 104 is subsequently changed, it is possible to avoid a situation in which the engine speed R becomes too high and exceeds the upper limit speed and abnormal vibration occurs.

  Further, before the fuel supply amount control unit 26 changes (increases) the opening degree of the fuel valve 104 in S52, the ignition timing control unit 25 executes the ignition timing control process to delay the ignition timing as much as possible. Yes. It is known that when the ignition timing is delayed, the NOx emission amount decreases. As a result, the amount of NOx discharged to the outside when the opening of the fuel valve 104 is changed can be further reduced.

  FIG. 11 is a graph showing the change over time in the concentration of NOx discharged to the outside when the combustion state is changed from lean burn to stoichiometric combustion. FIG. 11A shows the NOx concentration when the output control process, the rotation speed control process, and the ignition timing control process described above are executed before the combustion state is changed from lean burn to stoichiometric combustion (that is, this embodiment). FIG. 11 (b) shows the time change of the NOx concentration when the output control process, the rotation speed control process and the ignition timing control process are not executed before the combustion state is changed from lean burn to stoichiometric combustion. . In FIG. 11, the change of the combustion state is started at time 0. As can be seen from FIG. 11A, according to this embodiment, the maximum concentration of NOx discharged to the outside when changing the combustion state is 806 ppm, and the average concentration is 276 ppm. On the other hand, as shown in FIG. 11B, when the output control process is not executed, the maximum concentration of NOx discharged to the outside when changing the combustion state is 2113 ppm, and the average concentration is 800 ppm. As can be seen from this result, according to the present embodiment, the amount of NOx discharged to the outside when the combustion state is changed from lean burn to stoichiometric combustion is greatly reduced.

  As described above, the engine-driven air conditioner 1 according to the present embodiment includes the compressor 12 that sucks the refrigerant and compresses and discharges the sucked refrigerant, and the combustion chamber 101a, and is supplied with fuel. The engine 10 is configured so that the compressor 12 can be operated by burning the mixture of fuel and air supplied together with the air in the combustion chamber 101a, and the amount of fuel supplied to the engine 10 is as follows. And a control device 20 that controls the combustion state of the air-fuel mixture in the combustion chamber 101a. The control device 20 includes a combustion state change determination unit 22 that determines whether or not to change the combustion state of the air-fuel mixture in the combustion chamber 101a from lean burn to stoichiometric combustion, and the combustion state change determination unit 22 makes the combustion state lean. When it is decided to change from burn to stoichiometric combustion, the output control unit 23 controls the output of the engine 10 so that the output of the engine 10 decreases, and the combustion state after the output of the engine 10 is reduced by the output control unit 23 And a fuel supply amount control unit 26 that controls the supply amount of fuel supplied to the engine 10 so as to change from lean burn to stoichiometric combustion.

  Further, the engine 10 has a fuel supply pipe 116 that supplies fuel to the combustion chamber 101a, an exhaust pipe 103 that exhausts exhaust gas generated in the combustion chamber 101a, and an opening degree that is provided in the middle of the fuel supply pipe 116 is variable. A fuel valve 104, a fuel valve motor 105 connected to the fuel valve 104 and configured to change the opening of the fuel valve 104, and a three-way catalyst 111 a provided in the middle of the exhaust pipe 103. Prepare. The fuel supply amount control unit 26 controls the amount of fuel supplied to the engine 10 by driving the fuel valve motor 105 to control the opening degree of the fuel valve 104.

  According to the present embodiment, the engine output is reduced before the combustion state of the air-fuel mixture in the combustion chamber 101a of the engine 10 is changed from lean burn to stoichiometric combustion. Therefore, the combustion state is changed from lean burn to stoichiometric combustion while the engine output is reduced. For this reason, the engine output is low during intermediate combustion between lean burn and stoichiometric combustion. By reducing the engine output in this way, the amount of NOx discharged from the combustion chamber 101a during intermediate combustion can be reduced, and therefore the amount of NOx discharged to the outside is also reduced. Therefore, even when an engine in which the fuel supply amount is controlled by mixing the fuel and air by the mixer 108 and controlling the opening degree of the fuel valve 104 by the fuel valve motor 105, the combustion state is made lean. The emission amount of NOx to the outside when changing from burn to stoichiometric combustion can be reduced.

  Further, when the combustion state change determining unit 22 determines to change the combustion state from lean burn to stoichiometric combustion, the output control unit 23 reduces the engine output by reducing the power of the compressor 12. By reducing the compressor power, the output of the engine 10 that operates the compressor 12 is also reduced. For this reason, the amount of NOx discharged to the outside when the combustion state is changed from lean burn to stoichiometric combustion can be reduced.

  The engine-driven air conditioner 1 of the present embodiment also includes a condenser that flows in the refrigerant discharged from the compressor 12 and condenses the refrigerant that flows in (the indoor heat exchanger 13 during heating, and the outdoor during cooling. The heat exchanger 14), the condenser fan that blows air to the condenser (the indoor fans 131 and 131 when heating, the outdoor fans 141 and 141 when cooling), and the air flow rate of the condenser fan can be changed. It is possible to change the discharge flow rate of the refrigerant discharged from the compressor 12 and the blower amount changing device (the indoor fan motors 132 and 132 when heating, the outdoor fan motors 142 and 142 when cooling). Discharge flow rate changing means (bypass piping 123 and flow rate control valve 124) configured as described above. When the combustion state change determination unit 22 determines that the combustion state is changed from lean burn to stoichiometric combustion, the output control unit 23 executes output control processing so that the blower amount of the condenser fan increases. The engine output is reduced by controlling the air flow rate changing device (S24, S25) and controlling the discharge flow rate changing means so as to reduce the discharge flow rate (S27).

  According to this, condensing of the refrigerant in the condenser is promoted by increasing the amount of air blown by the condenser fan, and the flow rate (discharge flow rate) of the refrigerant discharged from the compressor 12 is decreased to the compressor. By reducing the acting load, the compressor power is reduced. Since the compressor power is thus reduced, the engine output is also sufficiently reduced.

  Further, the output control unit 23 controls the air flow rate changing device so that the air flow rate of the condenser fan is increased in S24 or S25 in FIG. 5, and then discharges so that the discharge flow rate is increased in S27 in FIG. The flow rate changing means (the opening degree of the flow rate control valve 124) is controlled. It takes some time for the refrigerant pressure in the refrigerant circuit to decrease after the air flow of the condenser fan increases. Therefore, the compressor power can be sufficiently reduced when the combustion state is changed by increasing the air flow rate of the condenser fan first and then increasing the discharge flow rate from the compressor 12.

  The control device 20 includes an ignition timing control unit 25. When the combustion state change determining unit 22 determines that the combustion state is changed from lean burn to stoichiometric combustion, the ignition timing control unit 25 executes an ignition timing control process, and the ignition timing is delayed from the normal ignition timing region. Thus, the ignition timing is changed to the retard side. Thereafter, the fuel supply amount control unit 26 executes a fuel supply amount control process, and the combustion state is changed from lean burn to stoichiometric combustion. In this way, by changing the ignition timing to the retard side rather than normal, the NOx emission amount can be further reduced.

  In addition, the control device 20 includes a rotation speed setting unit 24. When the combustion state change determining unit 22 determines that the combustion state is to be changed from lean burn to stoichiometric combustion, the rotational speed setting unit 24 executes a rotational speed control process to determine the rotational speed R of the engine 10 in advance. Change to set rotational speed R1. After that, the ignition timing control unit 25 executes an ignition timing control process to change the ignition timing to the retard side. Here, the set rotational speed R1 is set so that the engine does not stall when the ignition timing is changed to an ignition timing slower than the normal ignition timing region by the ignition timing control unit, and the combustion state changes from lean burn to stoichiometric combustion. The engine speed is set to a predetermined speed so that the engine speed does not become too high when the change is made and abnormal vibration occurs.

  According to this, by setting the engine speed R to the set speed R1 as described above, it is possible to prevent engine stall when the ignition timing is controlled so as to delay the ignition timing thereafter. In addition, the combustion state is changed from lean burn to stoichiometric combustion and the fuel ratio increases, so the engine blows up, and as the engine blows up, the engine speed becomes too high and abnormal vibration occurs. Can be prevented.

  As mentioned above, although embodiment of this invention was described, this invention should not be limited to the said embodiment. For example, in the above-described embodiment, the bypass pipe 123 is connected in the middle of the compressor 12, but the refrigerant discharge pipe connected to the discharge port 12b of the compressor 12 as in the modification shown in FIG. 121 and a refrigerant suction pipe 122 connected to the suction port 12a of the compressor 12 may be connected by a bypass pipe 123, and a flow rate control valve 124 may be interposed in the bypass pipe 123. As the compressor, a compressor other than the scroll compressor can be used. Moreover, you may comprise so that the discharge flow volume of the refrigerant | coolant discharged from a compressor may be changed by using the electric compressor which operate | moves with an electric motor and controlling the energization amount to an electric motor. Further, the present invention is preferably applied to an engine of a type in which fuel and air are mixed using a mixer and the opening degree of the fuel valve is adjusted by a fuel valve motor. However, the present invention is applied to an engine using an injector. May be. Thus, the present invention can be modified without departing from the gist thereof.

DESCRIPTION OF SYMBOLS 1 ... Engine-driven air conditioner, 10 ... Engine, 101 ... Engine main body, 101a ... Combustion chamber, 102 ... Intake piping, 103 ... Exhaust piping, 104 ... Fuel valve, 105 ... Fuel valve motor, 106 ... Throttle valve, 107 ... Throttle valve motor, 108 ... mixer, 109 ... air piping, 111 ... catalyst device, 111a ... three-way catalyst, 113 ... ignition plug, 115 ... igniter, 116 ... fuel supply piping, 12 ... compressor, 123 ... bypass piping (discharge) (Flow rate changing means), 124 ... flow control valve (discharge flow rate changing means), 13 ... indoor heat exchanger (condenser), 131 ... indoor fan (condenser fan), 132 ... indoor fan motor (air flow rate changing device), DESCRIPTION OF SYMBOLS 14 ... Outdoor heat exchanger (condenser), 141 ... Outdoor fan (condenser fan), 142 ... Outdoor fan motor (air flow rate changing device), 20 ... Control Device: 21 ... Combustion state determination unit, 22 ... Combustion state change determination unit, 23 ... Output control unit, 24 ... Revolution setting unit, 25 ... Ignition timing control unit, 26 ... Fuel supply amount control unit, 27 ... Stoichiometric return control Part, R1 ... set rotation speed

Claims (6)

A compressor that sucks in the refrigerant and compresses and discharges the sucked refrigerant;
An engine having a combustion chamber formed therein, configured to be able to operate the compressor by burning fuel in the combustion chamber and a mixture of the supplied fuel and air;
A control device that controls the combustion state of the air-fuel mixture in the combustion chamber by controlling the amount of fuel supplied to the engine,
The control device includes a combustion state change determining unit that determines whether or not to change the combustion state of the air-fuel mixture in the combustion chamber from lean burn to stoichiometric combustion, and the combustion state change determining unit determines whether the combustion state is lean burned. When it is decided to change from stoichiometric combustion to an stoichiometric combustion, an output control unit that controls the output of the engine so that the output of the engine decreases, and the combustion state after the output of the engine is reduced by the output control unit A fuel supply amount control unit for controlling a supply amount of fuel supplied to the engine so as to change from lean burn to stoichiometric combustion. The engine-driven air conditioner according to claim 1,
The output control unit reduces the engine output by reducing the power of the compressor when the combustion state change determining unit determines to change the combustion state from lean burn to stoichiometric combustion. Driven air conditioner. The engine-driven air conditioner according to claim 1 or 2,
A condenser that flows in the refrigerant discharged from the compressor and condenses the refrigerant that flows in;
A condenser fan that blows air to the condenser;
An air flow rate changing device configured to be able to change the air flow rate of the condenser fan;
A discharge flow rate changing means configured to be able to change the discharge flow rate of the refrigerant discharged from the compressor,
When the combustion state change determining unit determines that the combustion state is changed from lean burn to stoichiometric combustion, the output control unit controls the air supply amount changing device so that the amount of air blown from the condenser fan is increased. In addition, an engine-driven air conditioner that reduces the output of the engine by controlling the discharge flow rate changing means so that the discharge flow rate decreases. The engine-driven air conditioner according to any one of claims 1 to 3,
When the combustion state change determining unit determines that the combustion state is to be changed from lean burn to stoichiometric combustion, the control device causes the ignition timing to the air-fuel mixture in the combustion chamber to be delayed from a normal ignition timing region. Having an ignition timing control unit for changing the ignition timing to the retard side;
The fuel supply amount control unit determines that the combustion state change determination unit changes the combustion state from lean burn to stoichiometric combustion, and after the ignition timing control unit changes the ignition timing to a retarded side, An engine-driven air conditioner that controls the amount of fuel supplied to the engine so that the state is changed from lean burn to stoichiometric combustion. The engine-driven air conditioner according to claim 4,
The control device includes a rotation speed setting unit that changes the rotation speed of the engine to a predetermined rotation speed when the combustion state change determination section determines to change the combustion state from lean burn to stoichiometric combustion. Have
When the ignition timing control unit determines that the combustion state change determination unit changes the combustion state from lean burn to stoichiometric combustion, after the engine speed setting unit changes the engine speed to the set engine speed, An engine-driven air conditioner that changes the ignition timing to a retard side so that the ignition timing is delayed from a normal ignition timing region. The engine-driven air conditioner according to any one of claims 1 to 5,
The engine includes a fuel supply pipe for supplying fuel to the combustion chamber, an exhaust pipe for exhausting exhaust gas generated in the combustion chamber, and a fuel valve having a variable opening interposed in the middle of the fuel supply pipe. A fuel valve motor connected to the fuel valve and configured to change the opening of the fuel valve, and a three-way catalyst provided in the middle of the exhaust pipe,
The fuel supply amount control unit controls an amount of fuel supplied to the engine by driving the fuel valve motor and controlling an opening degree of the fuel valve.

Images