JP2011085111A - Engine and engine generator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology capable of preventing the deterioration of engine operation efficiency such as fuel consumption efficiency while shortening a period of warm-up operation until the engine is brought into a normal operating state. <P>SOLUTION: In the engine which repeats and operates one cycle containing four strokes of intake, compression, expansion and exhaust, it is configured so as to change the number of strokes in one cycle, i.e. the number of strokes included in one cycle which alternatively selects four-stroke cycle operation which operates without adding a stroke different from four cycles in one cycle and increased stroke cycle operation which operates by being added with one or more of rest strokes which makes a piston reciprocate without combustion to four strokes in one cycle. A control means is provided which allows the four stroke cycle operation when the engine is started, and controls the number of strokes in one cycle based on the temperature of the engine so as to change the operation to the increased stroke cycle operation when the temperature of the engine reaches a predetermined value at which the completion of the warm-up operation of the engine is determined. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an engine that repeatedly operates in one cycle including four strokes including an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke, and an engine power generator including a generator driven by the engine.

As a conventional engine, depending on the engine load, it is operated by adding one or more of a four-stroke cycle operation that operates in the above four strokes and a pair of pause strokes that reciprocate the piston without performing combustion separately from the four strokes. An increase stroke cycle operation that can be selectively switched is disclosed (for example, see Patent Document 1).
In the engine disclosed in Patent Document 1, in a steady operation state, a four-stroke cycle operation is performed when the engine load is in the rated load region, and an increased stroke is performed when the engine load is in a partial load region lower than the rated load region. It is configured to perform cycle operation.

  Thus, by controlling the engine operation based on the engine load, the shaft output can be changed in a wide range and with high efficiency in response to a significant decrease in the engine load.

JP 2007-270781 A

In the engine disclosed in Patent Document 1, the shaft output can be changed with high efficiency in response to a decrease or increase in engine load by switching the engine operation state based on the engine load in a steady operation state. During the warm-up operation from when the engine is started to when the engine is in the steady operation state, the operation state of the engine has not been switched.
Temporarily, in an engine capable of switching the operation state disclosed in Patent Document 1, when the engine is operated in an increased stroke cycle operation with a low shaft output during warm-up operation, the amount of heat generated from the engine per unit time is small, A very long time is required until the temperature of the engine rises to an appropriate temperature, and there is a problem that the operating efficiency of the engine such as fuel consumption efficiency may be lowered.

  The present invention has been made in view of the above problems, and an object of the present invention is to prevent a decrease in engine operating efficiency such as fuel consumption efficiency while minimizing the warm-up operation until the steady operation state is reached. Is to provide a technology that can.

In order to achieve the above object, an engine according to the present invention is an engine that repeatedly operates in one cycle including four strokes including an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke. A four-stroke cycle operation in which one stroke is operated without adding a stroke different from the four strokes, and a pair of pause strokes in which the piston is reciprocated without combustion in the one cycle separately from the four strokes. The number of one-stroke strokes, which is the number of strokes included in the one cycle, can be changed by selectively switching between one or more additional stroke cycle operations that are operated in addition, and the four strokes are started when the engine is started. Cycle operation is performed, and the engine can be switched to the increase stroke cycle operation when the temperature of the engine reaches a predetermined temperature at which it can be determined that the warm-up operation of the engine has ended. In the form of a, there the number of one cycle stroke in that a control means for controlling, based on a temperature of the engine.
In the above four-stroke cycle operation, the operation without adding a stroke different from the four strokes in one cycle means that only four strokes consisting of an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke are repeated in order. Indicates driving in an operating form.

According to the above characteristic configuration, the control means can perform the four-stroke cycle operation when starting the engine, and can switch to the increased stroke cycle operation when the engine temperature reaches a predetermined temperature at which it can be determined that the engine warm-up operation has been completed. In this embodiment, the number of one-stroke processes is controlled based on the engine temperature. Therefore, when the engine temperature is relatively low (warm-up operation state), the engine temperature can be increased more quickly. When the cycle operation is performed and the engine temperature reaches a predetermined temperature (steady operation state), it is possible to perform an increased stroke cycle operation that can realize an efficient operation of the engine. As a result, in the warm-up operation state, it is possible to prevent the increase stroke cycle operation in which the shaft output is low and it is difficult to raise the engine temperature early, and the warm-up operation time can be shortened as much as possible. By shortening the time, it is possible to prevent a decrease in engine operating efficiency such as fuel consumption efficiency.
Here, the increase stroke cycle operation is a pair of pauses in which the piston is reciprocated without expansion (combustion) in one cycle including four strokes of intake, compression, expansion, and exhaust, separately from the four strokes. One or more strokes are added. Thus, for example, after the engine temperature reaches a predetermined temperature (steady operation state), the number of strokes in one cycle, which is the number of strokes in one cycle, is set to an even number greater than 4 in response to a decrease in engine load. It can be set as the state which performs the increase stroke cycle operation which increased. In this way, if the increased stroke cycle operation is performed in the steady operation state, the engine load is increased by adding one or more pairs of pause strokes that do not generate shaft output in one cycle, compared to the case where the four stroke cycle operation is performed. The shaft output can be reduced corresponding to the decrease in the engine, and the engine can be operated efficiently.
Therefore, during the warm-up operation, the control means controls the number of one-cycle strokes based on the engine temperature, thereby shortening the warm-up operation until the steady operation state is as short as possible and operating the engine such as fuel consumption efficiency. A decrease in efficiency can be prevented.

  In a further characteristic configuration of the engine according to the present invention, when the control means controls the number of one-cycle strokes based on the temperature of the engine, when the oil temperature in the engine becomes a predetermined temperature, It is determined that the engine temperature has reached the predetermined temperature at which it can be determined that the warm-up operation of the engine has been completed.

  According to the above characteristic configuration, the control means uses the oil temperature in the engine that represents the engine temperature and is easy to measure, and the warm-up operation is terminated when the oil temperature in the engine reaches a predetermined temperature. The number of one-stroke processes can be easily controlled.

  A further characteristic configuration of the engine according to the present invention is that, when the control means controls the number of one-cycle strokes based on the temperature of the engine, an elapsed time from the start of the engine reaches a predetermined time. In addition, it is determined that the temperature of the engine has reached the predetermined temperature at which it can be determined that the warm-up operation of the engine has been completed.

  According to the above characteristic configuration, regardless of whether or not the control means measures the engine temperature, the engine temperature ends the warm-up operation when the elapsed time from the start of the engine reaches a predetermined time. Therefore, the number of one-stroke processes can be controlled more easily. Note that the relationship between the elapsed time from the start of engine start and the engine temperature (particularly the elapsed time until the engine temperature reaches the predetermined temperature) can be measured in advance.

  According to a further characteristic configuration of the engine according to the present invention, the pair of resting strokes includes a sealed lowering stroke in which the piston is lowered in a sealed state in which the intake valve and the exhaust valve are closed, and a sealed lift in which the piston is lifted in the same sealed state. It is in the point which consists of a process.

  According to the above characteristic configuration, a pair of resting strokes to be added one or more in one cycle are a sealed down stroke and a sealed up stroke, and a closed state in which the intake valve and the exhaust valve are closed during these pause strokes. Inappropriate gas flow in the intake passage and exhaust passage, such as when the air-fuel mixture is discharged to the exhaust passage without being combusted or exhaust gas flows backward to the intake passage, can be prevented.

  In order to achieve the above object, a characteristic configuration of an engine power generator according to the present invention includes: a generator driven by an engine having any one of the above characteristic configurations; and power generated by the generator connected to a commercial power system. And an electric heater capable of converting the electric power generated from the generator supplied via the inverter into heat, and the control means finishes the warm-up operation of the engine from the time of starting the engine. Up to, the engine cooling water or the oil circulation circuit for operating the electric heater using the surplus power of the generated power supplied from the generator to the power load and flowing the cooling water circulation circuit to cool the engine It is the point which heats the engine oil which flows through and is supplied into the engine.

According to the above characteristic configuration, when the engine temperature from the start of the engine to the end of the engine warm-up operation is a relatively low temperature (warm-up operation state), the control means The electric heater is operated using surplus electric power that is not consumed by the electric power load among the generated electric power, and engine cooling water for cooling the engine or engine oil supplied into the engine is heated. Thus, in the warm-up operation state, in addition to performing the four-stroke cycle operation that can quickly increase the temperature of the engine, further, through engine cooling water or engine oil heated by an electric heater, more The amount of heat can be supplied to the engine, and the temperature of the engine can be raised more quickly and efficiently.
Therefore, during the warm-up operation, the warm-up operation until the steady operation state is achieved can be further shortened, and the generated power from the generator can be effectively utilized.

Schematic configuration diagram of the engine Explanatory diagram schematically showing the state of 4-stroke cycle operation Explanatory diagram schematically showing the state of 6-stroke cycle operation Graph showing the relationship between the elapsed time from the start of engine start and the oil temperature in the engine Schematic configuration diagram of engine power generator Explanatory diagram schematically showing the state of 8-stroke cycle operation

An embodiment of an engine according to the present invention will be described with reference to FIGS.
FIG. 1 is a schematic configuration diagram of the engine, FIGS. 2 and 3 are explanatory diagrams schematically showing various operating states of the engine, and FIG. 4 is a relationship between an elapsed time from the start of engine start and an oil temperature in the engine. FIG.
2 and 3 and the following description, “TDC” as a piston position indicates a top dead center position, “BDC” as a piston position indicates a bottom dead center position, and the intake and exhaust valves are opened and closed. “O” as a state indicates an open state, “C” as an open / close state of the intake valve and the exhaust valve indicates a closed state, and “° BBDC” as a crank angle indicates a crank angle before bottom dead center.

〔engine〕
As shown in FIG. 1, the engine 50 includes a combustion chamber 10 defined by the inner surface of the cylinder 3 and the top surface of the piston 4, an intake passage 13 connected to the combustion chamber 10 via an intake valve 1, An exhaust passage 14 connected to the combustion chamber 10 via the exhaust valve 2 is provided. The engine 50 is provided with a known valve mechanism 20 such as a cam type, an electromagnetic actuator type or a hydraulic actuator type for opening and closing the intake valve 1 and the exhaust valve 2, and controls the operation of the engine 50. It is configured to be controlled by the control device 30 (an example of control means).

  The piston 4 is swingably connected to the connecting rod 8, and the reciprocating motion of the piston 4 is obtained as a rotational movement of one crankshaft 9 by the connecting rod 8, and such a configuration is not different from a normal engine. .

  In the intake passage 13, an air-fuel mixture I of circulating air and fuel that is a natural gas city gas is formed, and the air-fuel mixture I has a crank angle from about TDC (top dead center) to BDC (bottom dead center). In the intake stroke in which the intake valve 1 is opened to the vicinity, the combustion chamber 10 is inhaled.

  The engine 50 compresses the mixture I taken into the combustion chamber 10 by the piston 4 ascending in the compression stroke in which both the intake valve 1 and the exhaust valve 2 are closed. I is ignited by a known ignition method such as spark ignition or compression ignition by an ignition plug (not shown), and further, in the expansion stroke, the piston 4 is pushed down by combustion of the air-fuel mixture I to obtain a shaft output. Has been.

  Further, after the expansion stroke, the exhaust gas E in the combustion chamber 10 is discharged to the exhaust passage 14 in the exhaust stroke in which the exhaust valve 2 is opened from the vicinity of the BDC to the vicinity of TDC.

  The engine 50 includes four strokes including the above-described intake stroke, compression stroke, expansion stroke, and exhaust stroke in one cycle, and is operated without adding a stroke different from the four strokes. It is configured to perform stroke cycle operation.

  Next, the engine 50 is operated by the control device 30 by a four-stroke cycle operation and a six-stroke cycle operation (an increased stroke cycle stroke) in which the number of strokes included in one cycle is increased to six. The number of one-stroke processes can be changed. Hereinafter, the detailed structure for performing each driving | operation is demonstrated based on FIG. 2, FIG.

[4-stroke cycle operation]
When the engine 50 performs a four-stroke cycle operation, as shown in FIG. 2, only the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke are sequentially performed in accordance with the reciprocation between the piston TDC and the BDC. It operates by repeating one cycle including it.
Here, the intake valve 1 is opened near the start of the intake stroke in order to suck the mixture I from the intake passage 13 into the combustion chamber 10 as the piston descends from TDC to BDC during the intake stroke. Closed near the end of the intake stroke. On the other hand, the exhaust valve 2 is opened near the start of the exhaust stroke to discharge the exhaust gas E in the combustion chamber 10 to the exhaust passage 14 in accordance with the upward movement of the piston from BDC to TDC in the exhaust stroke. Closed near the end of
In this four-stroke cycle operation, the number of strokes included in one cycle is four (four strokes), and in one expansion stroke in the four strokes constituting one cycle, the mixture I The piston 4 is pushed down by combustion to generate shaft output.

[6 stroke cycle operation]
As shown in FIG. 3, the engine 50 is configured to be able to execute a six-stroke cycle operation in which the number of one-stroke strokes is six as an increased stroke cycle operation.
That is, when performing such a six-stroke cycle operation, the engine 50 separates the above four strokes within one cycle and performs a sealed up stroke and a sealed down stroke as a pair of pause strokes in which the piston reciprocates without combustion. One stroke is added, and one cycle consisting of these six strokes is repeated to operate.
In this six-stroke cycle operation, a pause stroke without combustion is added in one cycle, so that the amount of heat generated by the engine 50 per unit time is reduced compared to the four-stroke cycle operation. For example, if the time required to perform one cycle is about 1.5 times as long as the pause stroke is added in the six-stroke cycle operation compared to the four-stroke cycle operation, the unit time is determined by the four-stroke cycle operation. The amount of heat generated per unit time by the six-stroke cycle operation is about 2/3 of the amount of heat generated per hit.

In both the sealed up stroke and the sealed down stroke, both the intake valve 1 and the exhaust valve 2 are closed, and the piston is raised and lowered while preventing inappropriate flow of gas in the intake passage 13 and the exhaust passage 14. This is a pause process.
In the hermetic ascending stroke, the combustion chamber 10 is in a hermetic state, and the piston 4 is raised from BDC to TDC.
On the other hand, in the closed down stroke, the combustion chamber 10 is in a closed state, and the piston 4 is lowered from TDC to BDC.

In addition, a pair of rest strokes of the sealed up stroke and the sealed down stroke are added between the intake stroke and the compression stroke. In such a resting stroke, the air-fuel mixture I taken in by the intake stroke is present in the combustion chamber 10, and the pressure is higher than that in the case where the air-fuel mixture I does not exist in the combustion chamber 10. Ascending and descending operations can be easily performed, and it is prevented that the engine is difficult to operate.
In this six-stroke cycle operation, the number of one-stroke strokes is 6 (six strokes), and in one expansion stroke in the six strokes constituting one cycle, the piston 4 is pushed down by the combustion of the air-fuel mixture I and the shaft output is reduced. As a result, the shaft output is reduced to about 2/3 relative to the four-stroke cycle operation.

The detailed configuration for performing each operation in the engine 50 has been described above. The control device 30 provided in the engine 50 is based on the oil temperature in the engine 50 (an example of the temperature of the engine 50). Control is performed to appropriately switch the operating state of the engine 50 between a warm-up operation state until a predetermined temperature at which it can be determined that the operation has ended and a steady-state operation state where the warm-up operation has ended.
Details of the switching control by the control device 30 will be described below.

[Warm-up operation]
In the warm-up operation, which is the operation from the start of the engine 50 until the oil temperature in the engine 50 reaches a predetermined temperature, the control device 30 performs a four-stroke cycle operation with a relatively high shaft output and a large amount of generated heat per unit time. Control to execute is performed. Here, as shown in FIG. 1, in the engine 50, an oil temperature sensor 41 capable of measuring the temperature (oil temperature) of the oil flowing in the engine 50 is disposed at the lower portion of the cylinder 3, and the oil temperature sensor 41. The temperature of the engine 50 is output to the control device 30 by the temperature detection unit 40 as a temperature signal, so that the control device 30 can grasp the temperature of the engine 50.
Specifically, as shown in FIG. 4, the control device 30 determines that the oil temperature is a predetermined temperature (for example, from the start of the engine 50) based on the oil temperature in the engine 50 output from the temperature detection unit 40. , About 60 ° C.), a warm-up operation is performed in a four-stroke cycle operation (shown by a solid line in FIG. 4). It is configured. That is, the control device 30 controls the number of one-stroke processes so that the four-stroke cycle operation is performed in the warm-air operation state and the six-stroke cycle operation is not performed.
Thus, by performing the 4-stroke cycle operation with a large calorific value per unit time in the warm-up operation and not performing the 6-stroke cycle operation, the time until the warm-up operation is completed can be shortened. For example, as shown in FIG. 4, when a four-stroke cycle operation is performed (indicated by a solid line in FIG. 4), the oil temperature becomes a predetermined temperature 40 minutes after the start of the operation, and the warm-up operation ends. When the operation is performed (indicated by a broken line in FIG. 4), it takes about 60 minutes until the warm-up operation is completed.
Accordingly, in the warm-up operation state, it is possible to prevent the six-stroke cycle operation in which the shaft output is low and it is difficult to raise the temperature of the engine 50 at an early stage, and the warm-up operation time can be shortened as much as possible. By shortening the time, it is possible to prevent a reduction in operating efficiency of the engine 50 such as fuel consumption efficiency.

(Steady operation)
When the oil temperature in the engine 50 reaches a predetermined temperature and is in steady operation (warm-up operation is completed), the control device 30 performs control to switch the operation state of the engine 50 based on the engine load.
That is, in the steady operation, the control device 30 performs a four-stroke cycle operation when the engine load is in the rated load region, and performs six strokes when the engine load is in a partial load region (low load region) lower than the rated load region. It is configured to control the number of one-stroke processes based on the engine load in a form of selectively switching so as to perform cycle operation. In steady operation, the oil temperature in the engine 50 is equal to or higher than a predetermined temperature (for example, about 60 ° C.).
The engine load refers to the amount of work applied to the crankshaft 9 of the engine 50, while the shaft output refers to the amount of work output from the crankshaft 9 of the engine 50. The engine load can be derived from the torque related to the crankshaft 9 and the rotational speed of the crankshaft 9. For example, a generator or a compressor is driven by the shaft output of the crankshaft 9. In that case, a power generation load added to the generator or a compression load added to the compressor may be handled as the engine load.

And the control apparatus 30 is comprised so that the shaft output of the engine 50 may be changed according to the fluctuation | variation of engine load, and the rotation speed of the crankshaft 9 is stabilized.
That is, the control device 30 switches from the four-stroke cycle operation to the six-stroke cycle operation and increases the number of one-stroke strokes from four to two when the engine load decreases from the rated load region to the low load region in the steady operation state. By setting the value to 6, the shaft output can be sequentially decreased in accordance with the decrease in the engine load, and the shaft output can be changed in a wide range in accordance with the variation in the engine load.
In the above six-stroke cycle operation, the shaft output is about 2/3 relative to the four-stroke cycle operation, so the rated load range is from the maximum load corresponding to the maximum shaft output of the engine 50 to the maximum load. The range is set to about 2/3, and the low load range is set to the range from about 2/3 of the maximum load to the minimum load.

  As described above, when the control device 30 performs the six-stroke cycle operation in the steady operation state, one or more pairs of pause strokes that do not generate the shaft output in one cycle as compared with the case where the four-stroke cycle operation is performed. As a result, the shaft output can be reduced in response to a reduction in engine load without changing the fuel consumption, and the engine 50 can be operated efficiently.

[Another embodiment]
(1) In the above embodiment, the engine load that is the target for which the shaft output of the engine 50 of the present application is used is not specified, but the shaft output of the engine 50 of the present application is used as the generator 81 driven by the engine 50. It can also be applied to an engine power generation device 80 equipped with
Specifically, as shown in FIG. 5, the engine power generation device 80 includes an engine 50, a generator 81 driven by the engine 50, and an inverter that interconnects the generated power of the generator 81 to the commercial power system 90. 82 and an electric heater 83 that can convert the generated power from the generator 81 supplied through the inverter 82 into heat. The engine power generation device 80 includes a converter 84 between the generator 81 and the inverter 82.
The generator 81 is a permanent magnet type 20-pole three-phase AC generator that is connected to the output shaft of the engine 50 and generates AC power by driving the engine 50, and the converter 84 is AC power output from the generator 81. Is converted into DC power, and the inverter 82 converts DC power output from the converter 84 into AC power. The commercial power system 90 is electrically connected to a power load 91 such as a television, a refrigerator, or a washing machine via a first power supply line 92. The inverter 82 converts the DC power from the converter 84 into AC power that matches the frequency and voltage of the commercial power system 90, thereby connecting the power generation output of the generator 81 to the commercial power system 90.
The inverter 82 is electrically connected to the first power supply line 92 via the second power supply line 85, and is configured to be able to supply the generated power from the generator 81 to the power load 91. Although not shown, the first power supply line 92 is provided with power load measuring means for measuring the load power of the power load 91, and this power load measuring means is opposite to the current flowing through the first power supply line 92. It is also configured to detect whether or not a tidal current occurs. And the electric power supplied to the 1st electric power supply line 92 from the generator 81 is controlled by the inverter 82 so that a reverse power flow may not occur, and the surplus electric power of the generated electric power is an electric heater that can convert the surplus electric power into heat. 83 to be supplied.
The electric heater 83 converts the generated power from the generator 81 (particularly, the surplus power) into heat, and freely provides engine cooling water C for cooling the engine 50 flowing through the cooling water circulation circuit 86. It has been. The coolant circulation circuit 86 circulates the engine coolant C between the engine 50 and the exhaust heat recovery heat exchanger 93 by the operation of the coolant pump 87. The electric heater 83 can adjust the heating amount of the engine cooling water C according to the amount of surplus power so that the power consumption increases and the heating amount of the engine cooling water C increases as the amount of surplus power increases. It is configured. The heat exchanger 93 for exhaust heat recovery is a heat exchanger that heats the hot water H with the engine cooling water C by exchanging heat with the hot water H flowing through the hot water passage 94 with the engine cooling water C. The hot water flow path 94 is, for example, a circuit through a hot water storage tank (not shown) provided in the cogeneration system, so that the hot water H supplied from the hot water storage tank has exhaust heat of the engine 50. The heat of the engine cooling water C can be recovered and used.
In such a configuration, the control device 30 performs the four-stroke cycle operation during the warm-up operation in the same manner as in the above embodiment, and further, the power consumed by the power load 91 based on the measurement result of the power load measuring unit. When it is determined that surplus power that is a surplus of the power generated by the generator 81 with respect to the power load 91 has occurred, this surplus power is supplied to the electric heater 83 via the inverter 82. Thus, in the warm-up operation state, in addition to performing the four-stroke cycle operation that can quickly raise the temperature of the engine 50, the engine 50 is further increased through the engine coolant C heated by the electric heater 83. The amount of heat can be supplied to the engine 50, and the temperature of the engine 50 can be raised more quickly and efficiently.
Therefore, during the warm-up operation, the warm-up operation until the steady operation state is achieved can be further shortened, and the generated power from the generator 81 can be effectively utilized.
In the above description, the configuration in which the engine coolant C flowing through the coolant circulation circuit 86 is heated by the electric heater 83 has been described. Although not shown, for example, during the warm-up operation, the engine 50 is passed through the oil circulation circuit. A configuration in which the engine oil supplied inside is heated by the electric heater 83 can also be adopted. In this case, in the warm-up operation state, in addition to performing the four-stroke cycle operation that can quickly raise the temperature of the engine 50, a larger amount of heat is further supplied through the engine oil heated by the electric heater 83. It can be supplied to the engine 50, and the temperature of the engine 50 can be raised more quickly and efficiently.

(2) In the above embodiment, when determining that the temperature of the engine 50 has reached a predetermined temperature at which it can be determined that the warm-up operation of the engine 50 has been completed, the temperature is measured by the oil temperature sensor 41 and output by the temperature detector 40. Although the temperature of the oil in the engine 50 is used, it is not particularly limited to this configuration as long as it can be determined that the temperature of the engine 50 is a predetermined temperature.
For example, when the elapsed time from the start of engine 50 reaches a predetermined time, control device 30 determines that the temperature of engine 50 has reached a predetermined temperature at which it can be determined that the warm-up operation of engine 50 has ended. It can also be configured.
That is, regardless of whether or not the control device 30 measures the temperature of the engine 50, when the elapsed time from the start of the engine 50 reaches a predetermined time (for example, 40 minutes have elapsed in the example shown in FIG. 4). It is determined that the temperature of the engine 50 in the four-stroke cycle operation has reached a predetermined temperature (for example, about 60 ° C.) at which it can be determined that the warm-up operation has ended. Thereby, the number of one-stroke processes can be controlled more easily. The relationship between the elapsed time from the start of the start of the engine 50 and the temperature of the engine 50 (particularly, the elapsed time until the temperature of the engine 50 reaches a predetermined temperature) is measured and stored in the control device 30 in advance, for example. Things can be used.

(3) In the above embodiment, the engine load for which the shaft output of the engine 50 of the present application is used is not specified, but the shaft output of the engine 50 of the present application is used as a drive source of a compressor that compresses the refrigerant. The present invention can also be applied to a heat pump system having a compression heat pump circuit to be used.
In this case, by operating the compressor by the engine 50 and operating the compression heat pump circuit, the shaft output of the engine 50 can be effectively used to obtain cold or warm heat in the compression heat pump circuit. The engine load applied to the engine 50 corresponds to the heat load of the compression heat pump circuit.
Specifically, in a steady operation state, the control device 30 first detects a thermal load in the compression heat pump circuit as an engine load, and determines whether the engine load is in a rated load range or a low load range. Thus, it is possible to adopt a configuration in which switching between the 4-stroke cycle operation and the 6-stroke cycle operation is performed according to each load region.

(4) In the above embodiment, in the steady operation state, the six-stroke cycle operation is performed to appropriately reduce the shaft output in response to the decrease in the engine load. 1 cycle which has been described so far by providing a valve timing variable mechanism in the valve mechanism 20 for opening and closing the exhaust valve 1 and the exhaust valve 2 and changing the phase of the cam rotation or the periodic operation of the actuator. It is also possible to adjust at least the closing timing of the intake valve 1 without changing the shaft output accompanying changing the number of strokes.
As a result, by this valve timing variable mechanism, the closing timing of the intake valve 1 is advanced or retarded with respect to 0 ° BBDC (bottom dead center), so that the intake valve 1 is moved earlier than the bottom dead center in the intake stroke. Or if it closes late, the amount of intake air which is the amount of the air-fuel mixture I taken into the combustion chamber 10 will decrease, and as a result, the shaft output will decrease. Therefore, the engine 50 uses this valve timing variable mechanism to advance or retard the closing timing of the intake valve 1 in the intake stroke with adjustment of the advance amount or the retard amount with respect to 0 ° BBDC. The shaft output can be configured to be changeable as it falls within a range not accompanied by a change in the load range.

(5) In the above-described embodiment, the six-stroke cycle operation is performed as the increased stroke cycle operation. However, the eight-stroke cycle operation in which the number of one-cycle strokes is eight, which is a more efficient operation in the steady operation state. It can also be configured to be executable.
That is, as shown in FIG. 6, when performing such an 8-stroke cycle operation, the engine 50 is a pair of pause strokes in which the piston is reciprocated without combustion in addition to the above-described 4 strokes in one cycle. It is also possible to add two sealed up strokes and closed down strokes between the intake stroke and the compression stroke, and to operate by repeating one cycle consisting of these eight strokes.
Note that the pair of rest strokes of the sealed up stroke and the sealed down stroke added here are the same strokes as the pause stroke added in the above-described six-stroke cycle operation, and detailed description thereof will be omitted.
Specifically, the control device 30 selectively switches the operation state of the engine 50 in the steady operation state between a four-stroke cycle operation, a six-stroke cycle operation, and an eight-stroke cycle operation. The number can be switched between 4, 6 and 8, and the 4-stroke cycle operation is performed when the engine load is in the rated load range, and the 6-stroke cycle when the engine load is in the middle load range lower than the rated load range. It is also possible to control the number of one-stroke processes based on the engine load in the form of performing the eight-stroke cycle operation when the operation is performed and the engine load is in a low load range lower than the medium load range.
As a result, if the number of one-stroke strokes is increased to 6, the shaft output that is theoretically reduced to about 2/3 of the four-stroke cycle operation can be stably output. If it is increased to 8, the shaft output that is theoretically reduced to about 1/2 of the four-stroke cycle operation can be stably output.

(6) In the above embodiment, a pair of rest strokes of a sealed up stroke and a sealed down stroke are added between the intake stroke and the compression stroke. However, the location where the pause stroke is added is not particularly limited. For example, when it is permissible that the exhaust gas E exists in the combustion chamber 10, it is also possible to add a sealed up stroke and a sealed down stroke between the expansion stroke and the exhaust stroke.
Further, the pair of resting strokes does not form a sealed state in which the intake valve 1 and the exhaust valve 2 are closed when the inflow of the air-fuel mixture I into the combustion chamber 10 and the backflow of the exhaust gas E do not matter. For example, one or both of the valves 1 and 2 may be opened to make the piston reciprocate.

  The engine according to the present invention can be effectively used as a technique that can prevent a decrease in the operating efficiency of the engine such as fuel consumption efficiency while shortening the warm-up operation until the steady operation state is as short as possible.

1: Intake valve 2: Exhaust valve 30: Control device (control means)
40: Temperature detector 41: Oil temperature sensor 50: Engine 80: Engine power generation device 81: Generator 82: Inverter 83: Electric heater 86: Cooling water circulation circuit 90: Commercial power system 91: Electric power load C: Engine cooling water

Claims (5)

An engine that operates by repeating one cycle including four strokes including an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke,
A four-stroke cycle operation that operates without adding a stroke different from the four strokes in the one cycle, and a pair of pause strokes in which the piston reciprocates without combustion in the one cycle separately from the four strokes. The number of strokes included in the one cycle can be changed in a form that is selectively switched between the increased stroke cycle operation in which one or more are added and operated,
The four-stroke cycle operation is performed when the engine is started, and when the engine temperature reaches a predetermined temperature at which it can be determined that the warm-up operation of the engine has been completed, the one-cycle can be switched to the increased stroke cycle operation. An engine comprising control means for controlling the number of strokes based on the temperature of the engine.   When the control means controls the number of one-cycle strokes based on the temperature of the engine, when the oil temperature in the engine reaches a predetermined temperature, the engine temperature has ended the warm-up operation of the engine. The engine according to claim 1, wherein it is determined that the predetermined temperature has been reached.   When the control means controls the number of one-stroke processes based on the temperature of the engine, when the elapsed time from the start of the engine reaches a predetermined time, the temperature of the engine becomes the warm-up operation of the engine. The engine according to claim 1, wherein the engine is determined to have reached the predetermined temperature at which it can be determined that has been completed.   The pair of rest strokes includes a hermetic lowering stroke for lowering the piston in a sealed state with the intake valve and the exhaust valve closed, and a hermetic ascent stroke for raising the piston in the same sealed state. The engine according to one item. A generator driven by the engine according to any one of claims 1 to 4, an inverter connected to a commercial power system of power generated by the generator, and the power generation supplied via the inverter Equipped with an electric heater that can convert the generated power from the machine into heat,
The control means operates the electric heater using surplus power of the generated power supplied from the generator to the power load from the start of the engine to the end of the warm-up operation of the engine, and a cooling water circulation circuit An engine power generator that heats engine oil supplied through the engine cooling water or oil circulation circuit for flowing through and cooling the engine.

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