JP2007270781A - Engine and heat pump system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine which is capable of altering a shaft output efficiently in wide range for coping with sharp lowering of engine load while constraining increase in pumping loss, and a heat pump system which is capable of operating with high COP by being provided with such an engine. <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 make it possible to change the number of strokes 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 adding by one or more of rest strokes which makes a piston reciprocate without combustion to four strokes in one cycle. The engine controls the number strokes in one cycle based upon the engine load in mode which performs the four stroke cycle operation if engine load is in rated load region and performs the increased stroke cycle operation if engine load is in partial load region. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to 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, and a compressor that uses the shaft output of the engine as a drive source. The present invention relates to a heat pump system including a compression heat pump circuit.

  As a conventional engine, the closing timing of the intake valve in the intake stroke is advanced or retarded with respect to the bottom dead center, and the closing timing of the intake valve is controlled based on the engine load so-called early closing of the intake valve. Or what performs late closing control is known (for example, refer to patent documents 1 and 2).

  An engine that performs such early closing or late closing control of the intake valve, when the engine load is in a partial load region lower than the high load region, reduces the throttle valve opening in order to reduce the intake amount to the combustion chamber. Since it is not necessary to squeeze, it is possible to operate with high efficiency while suppressing an increase in pumping loss.

  In addition, in a heat pump system equipped with an engine and a compression heat pump circuit that uses its shaft output as a drive source for the compressor, the engine can be operated with high efficiency even when the engine load is in the partial load region as described above. However, it is desired to improve COP (coefficient of performance: ratio of heat energy generated in the heat pump circuit to operating energy in the engine).

JP-A-63-76517 JP 2001-659335 A

However, in the engine, when the engine load is in a partial load region that is significantly lower than the rated load region, it is necessary to greatly reduce the intake air amount, but only the early closing or late closing control of the intake valve as described above. In some cases, however, the intake volume could not be reduced significantly in line with a significant decrease in engine load due to improvements in intake charge efficiency in the high engine speed range and restrictions on intake valve closing timing. .
Therefore, in order to be able to change the shaft output over a wide range in response to a significant decrease in engine load, it is necessary to reduce the opening of the throttle valve in addition to the early or late closing control of the intake valve. Therefore, an increase in pumping loss could not be sufficiently suppressed.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an engine capable of changing the shaft output in a wide range and with high efficiency in response to a large decrease in engine load while suppressing an increase in pumping loss. And a heat pump system that includes such an engine and can be operated at a high COP.

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 that operates without adding a stroke different from the four strokes in the one cycle, and a pair of pauses that reciprocate the piston in the one cycle without combustion separately from the four strokes In the form of selectively switching between the increased stroke cycle operation that operates by adding one or more strokes, the number of strokes included in the one cycle is configured to be changeable,
The four-stroke cycle operation is performed when the engine load is in the rated load region, and the increased stroke cycle operation is performed when the engine load is in the partial load region lower than the rated load region. There is a control means for controlling the number based on the engine load.
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 first characteristic configuration, in one cycle including the four strokes of intake, compression, combustion, and exhaust, apart from the four strokes, a pair of pause strokes for reciprocating the piston without combustion is performed. If one or more are added, the number of one-stroke strokes, which is the number of strokes in one cycle, can be set to a state in which the increased stroke cycle operation is increased to an even number greater than 4, and such an increased stroke cycle operation can be performed. As compared with the case where the four-stroke cycle operation is performed, the shaft output can be reduced by adding one or more pairs of pause strokes that do not generate a shaft output in one cycle.
Therefore, by controlling the number of one-stroke processes based on the engine load by the control means, the shaft output can be changed in accordance with the engine load without adjusting the opening of the throttle valve, and the pumping loss It is possible to change the shaft output over a wide range and with high efficiency in response to a large decrease in engine load while suppressing an increase in the engine load.
That is, even when the engine load is in a low partial load range, the shaft output can be sufficiently reduced by performing an increase stroke cycle operation in which the number of stroke cycles is increased to an even number greater than 4, and the throttle valve It is not necessary to reduce the intake air amount due to a decrease in the opening degree of the valve, and an increase in pumping loss can be suppressed.
On the other hand, even when the engine load fluctuates from the partial load range to the high rated load range, by performing the 4-stroke cycle operation with the minimum number of 1-cycle strokes, the shaft output can be increased and the shaft output can be increased over a wide range. The output can be changed.

  According to a second characteristic configuration of the engine of the present invention, the control means sets the closing timing of the intake valve in the intake stroke to a bottom dead center as the engine load decreases within a range not accompanied by a change in the load range. On the other hand, the closing timing of the intake valve is controlled based on the engine load in the form of advance or retard.

If the number of strokes per cycle is controlled by the control means based on the engine load, the shaft output can be changed in a wide range according to the fluctuation of the engine load. However, it is difficult to change the shaft output smoothly with a small width. is there.
Therefore, according to the second characteristic configuration, the control means causes the intake air to decrease as the engine load decreases within a range that does not involve a change in the load range, in other words, within a range that does not involve a change in the number of strokes. Since the closing timing of the intake valve in the stroke is advanced or retarded with respect to the bottom dead center, the shaft output can be smoothly changed even with a small change in the engine load without changing the load range.

  According to a third characteristic configuration of the engine according to the present invention, the pair of pause 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 raised in the same sealed state. It is in the point which consists of a process.

  According to the third characteristic configuration, a pair of resting strokes that are added one or more in one cycle are the sealed down stroke and the sealed up stroke, and the intake valve and the exhaust valve are closed during the rest stroke. Thus, an inappropriate flow of gas in the intake passage and the exhaust passage, such as when the air-fuel mixture is discharged to the exhaust passage without being combusted or the exhaust gas flows backward to the intake passage, can be prevented. Further, in the closed down stroke, the piston is lowered in the closed state, so that the shaft output is consumed in order to make the combustion chamber have a negative pressure. In the next closed up stroke, the negative pressure in the combustion chamber is changed to the piston. As a result, the shaft output substantially corresponding to the consumed shaft output is generated, and the reduction in efficiency due to the addition of the pause process can be suppressed.

  A fourth characteristic configuration of the engine according to the present invention is such that, in the increase stroke cycle operation, one or more of the pair of pause strokes are added between the exhaust stroke and the intake stroke. is there.

  According to the fourth feature configuration, if the pair of pause strokes are added between the exhaust stroke and the intake stroke, there is no mixture or exhaust gas in the combustion chamber in the pause stroke. It is possible to prevent excessive heating due to unforeseen combustion or retention of exhaust gas.

A fifth characteristic configuration of the engine according to the present invention includes the four-stroke cycle operation, the six-stroke cycle operation as the increased stroke cycle operation in which one pair of pause strokes is added in the one cycle, and the The number of 1-cycle strokes can be switched between 4, 6, and 8 by selectively switching between the 8-stroke cycle operation as the increased stroke cycle operation in which two pairs of pause strokes are added within one cycle. Configured,
The control means performs the 4-stroke cycle operation when the engine load is in a rated load range, and performs the 6-stroke cycle operation when the engine load is in a medium load range lower than the rated load range, In the form in which the 8-stroke cycle operation is performed when the engine load is in a low load range lower than the medium load range, the number of 1-cycle strokes is controlled based on the engine load.

According to the fifth characteristic configuration, if the number of one-stroke strokes is increased to 6, a shaft output that is theoretically reduced to about 2/3 with respect to the four-stroke cycle operation can be stably output. If the number of one-stroke strokes is increased to eight, the shaft output that is theoretically reduced to about ½ of the four-stroke cycle operation can be stably output.
Therefore, when the engine load is in the rated load range within the range from the maximum load corresponding to the maximum shaft output of the engine to about 2/3 of the maximum load, it is relatively high by performing the four-stroke cycle operation. A shaft output can be output, and when the engine load is in a medium load range within a range from about 2/3 to about 1/2 of the maximum load, for example, by performing a six-stroke cycle operation, A shaft output slightly lower than that in the above four-stroke cycle operation can be output without an increase in pumping loss, and the engine load is low, for example, in the range from about 1/2 of the maximum load to the minimum load. If it is within the range, the 8-stroke cycle operation is performed, and the shaft output is slightly lower than the 4-stroke cycle operation or the 6-stroke cycle operation without increasing the pumping loss. It is possible to force.
Therefore, it is possible to change the shaft output over a wide range and with high efficiency by performing 6-stroke cycle operation in response to a slight decrease in engine load and further performing 8-stroke cycle operation in response to a significant decrease in engine load. Engine can be realized.

  The characteristic configuration of the heat pump system according to the present invention includes an engine having any of the characteristic configurations described so far, and a compression heat pump circuit having a compressor using a shaft output of the engine as a drive source. Yes, as explained so far, a heat pump system that can be operated with high COP by providing an engine that can change shaft output in a wide range and with high efficiency in response to a significant decrease in engine load while suppressing pumping loss Can be realized.

  An embodiment of an engine and a heat pump system according to the present invention will be described based on the drawings.

〔engine〕
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 to 4 are explanatory diagrams schematically illustrating various operating states of the engine, and FIG. 5 is an explanatory diagram schematically illustrating a load control state. .
2 to 4 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 valve and exhaust valve “O” as an open / close state indicates an open state, “C” as an open / close state of the intake and exhaust valves indicates a closed state, and “° BBDC” as a crank angle indicates a crank angle before bottom dead center. .

  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 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 cycle operation.

Further, 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. The valve mechanism 20 is provided with a variable valve timing mechanism 21 capable of adjusting at least the closing timing of the intake valve 1 by changing the phase of cam rotation or periodic operation of the actuator.
Then, by this valve timing variable mechanism 21, 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 from the bottom dead center in the intake stroke. If the valve is closed early or late, the intake air amount, which is the amount of the air-fuel mixture I taken into the combustion chamber 10, is reduced, and as a result, the shaft output is reduced.
Therefore, the engine 50 causes the valve timing variable mechanism 21 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 changed.

  Next, the engine 50 is operated by increasing the number of strokes included in one cycle and increasing the number of strokes included in one cycle to a value larger than 4, specifically, Can change the number of one-cycle strokes by switching between a six-stroke cycle operation that increases the number of one-cycle strokes to six and an eight-stroke cycle operation that increases the number of one-cycle strokes to eight. It is configured. Hereinafter, the detailed detailed structure for performing each driving | operation is demonstrated based on FIGS.

(4-stroke cycle operation)
When performing the above four-stroke cycle operation, the engine 50 performs only the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke in accordance with the reciprocation between the TDC and BDC of the piston as shown in FIG. It operates by repeating one cycle including the order.
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 perform a six-stroke cycle operation in which the number of one-stroke strokes is six as the increased stroke cycle stroke.
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 down stroke and a closed lift 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 both the above-described sealed down stroke and the above-described closed up stroke, both the intake valve 1 and the exhaust valve 2 are closed, and the piston is lowered while preventing inappropriate flow of gas in the intake passage 13 and the exhaust passage 14. And a lift process to raise.
In the closed down stroke, the combustion chamber 10 is in a sealed state, and therefore the combustion chamber 10 is in a negative pressure state as the piston 4 is lowered from TDC to BDC, thereby lowering the piston 4. Some axis output is consumed.
On the other hand, in the above-described hermetic ascent stroke, the combustion chamber 10 is in a hermetically sealed state with a negative pressure state. Therefore, in the ascending operation of the piston 4 from BDC to TDC, the negative pressure state is eliminated. Thus, a shaft output substantially corresponding to the amount consumed in the above-described hermetic lowering process is generated.

  In addition, a pair of pause strokes of the closed down stroke and the closed up stroke are added between the exhaust stroke and the intake stroke, and the mixture I and exhaust gas E exist in the combustion chamber 10 during the pause stroke. Therefore, an unexpected temperature increase due to unexpected combustion of the air-fuel mixture I or retention of the exhaust gas E is prevented.

  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.

(8-stroke cycle operation)
Further, as shown in FIG. 4, the engine 50 is configured to be able to execute an eight-stroke cycle operation in which the number of one-stroke strokes is eight as the increasing stroke cycle stroke.
That is, when performing the 8-stroke cycle operation, the engine 50 separates the above-described four strokes in one cycle, and performs a sealed down stroke and a closed lift as a pair of pause strokes in which the piston is reciprocated without combustion. Two strokes are added between the exhaust stroke and the intake stroke, and one cycle consisting of these eight strokes is operated repeatedly.
The pair of resting strokes of the sealed down stroke and the sealed up 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.

  In this 8-stroke cycle operation, the number of stroke cycles is 8 (8 strokes), and in one expansion stroke in the 8 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 ½ relative to the four-stroke cycle operation.

It should be noted that a pair of pause strokes of the closed down stroke and the closed up stroke are not added between the exhaust stroke and the intake stroke, but, for example, the mixture I or the exhaust gas E exists in the combustion chamber 10. Can be added between the intake stroke and the compression stroke, or between the expansion stroke and the exhaust stroke, the sealing up stroke and the sealing down stroke can be added in this order.
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 above is the detailed configuration for performing each operation in the engine 50. The control device 30 provided in the engine 50 uses such a configuration, and performs the four-stroke cycle operation when the engine load is in the rated load range. And a control means for performing load control for controlling the number of one-stroke processes based on the engine load in a form in which the increased stroke cycle operation is performed when the engine load is in a partial load range lower than the rated load range. A detailed configuration for performing such load control will be described below with reference to FIG.

(Load control)
In the load control, the control device 30 performs the above-described four-stroke cycle operation when the engine load is in the rated load region, and when the engine load is in the middle load region as a partial load region lower than the rated load region. In the form of performing the above-described 8-stroke cycle operation when the above-described 6-stroke cycle operation is performed and the engine load is in a low load range as a partial load range lower than the middle load range, the number of 1-stroke strokes is 4 and 6. 8 is configured to control based on the engine load in such a manner that it is switched to one of the two.

  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.

The control device 30 is configured to perform such load control so as to change the shaft output of the engine 50 in accordance with the fluctuation of the engine load and stabilize the rotational speed of the crankshaft 9.
That is, when the engine load drops to the rated load range, the medium load range, and the low load range, the control device 30 sequentially switches to the 4-stroke cycle operation, the 6-stroke cycle operation, and the 8-stroke cycle operation in the load control. Thus, by increasing the number of one-stroke processes from 4 to 2, the shaft output can be sequentially decreased according to the decrease in the engine load, and the shaft output can be changed over a wide range in accordance with the variation in the engine load. Further, since the shaft output is reduced only by increasing the number of one-stroke strokes without reducing the intake air amount due to a decrease in the opening of the throttle valve or the like as in the prior art, an increase in pumping loss can be suppressed.

  In the 6-stroke cycle operation, the shaft output is about 2/3 relative to the 4-stroke cycle operation, and in the 8-stroke cycle operation, the shaft output is 1 / relative to the 4-stroke cycle operation. Therefore, the rated load range is set in a range from the maximum load corresponding to the maximum shaft output of the engine 50 to about 2/3 of the maximum load, and the medium load range is 2/2 of the maximum load. The low load range is set in the range from about 1/2 of the maximum load to the minimum load.

Further, the engine 50 uses the variable valve timing mechanism 21 to advance or retard the closing timing of the intake valve 1 in the intake stroke with adjustment of the advance or retard amount with respect to 0 ° BBDC. Can be changed.
Then, using such a configuration, the control device 30 sets the intake valve closing timing in the intake stroke as the engine load decreases in the above-described load control within a range not accompanied by the change of the load range described above. The closing timing of the intake valve 1 is controlled on the basis of the engine load in a form of advance or advance with respect to 0 ° BBDC.

  That is, when the engine load drops in any one of the rated load range, the medium load range, and the low load range in the load control, the control device 30 has the number of one-cycle strokes described so far. Without changing the shaft output accompanying the change, the valve timing variable mechanism 21 is operated to advance or retard the closing timing with respect to 0 ° BBDC, so that the shaft output is increased in accordance with a decrease in engine load. It can be smoothly reduced with high responsiveness, and furthermore, since the intake air amount is not reduced due to a decrease in the opening of the throttle valve or the like as in the prior art, an increase in pumping loss can be suppressed.

[Heat pump system]
An embodiment of a heat pump system according to the present invention will be described with reference to FIG.
FIG. 6 is a schematic configuration diagram of the heat pump system.

As shown in FIG. 6, the heat pump system 100 includes an engine 50 that has been described so far, and a compression heat pump circuit 60 that uses the shaft output of the engine 50 as a drive source of a compressor 61 that compresses refrigerant. The control device 30 is configured to control the operation of various supplementary notes of the heat pump circuit 60 in addition to the engine 50. Note that the configuration of the engine 50 is the same as that described so far, so a detailed description may be omitted.
Then, by operating the compressor 61 by the engine 50 and operating the compression heat pump circuit 60, it is possible to effectively use the shaft output of the engine 50 to obtain cold or warm heat in the compression heat pump circuit 60.

The compression heat pump circuit 60 includes a compressor 61, an outdoor unit 62, an expansion valve 63, and an indoor unit 64, and further four-way switching for switching the refrigerant delivery direction of the compressor 61 to the indoor unit 64 and the outdoor unit 62. A valve 65 is provided. In the cooling state shown in FIG. 1, that is, in the state where the four-way switching valve 65 is switched so that the discharge side of the compressor 61 is directed to the outdoor unit 62 and the inflow side is directed to the indoor unit 64, the evaporated refrigerant vapor is The high-temperature and high-pressure state is compressed in the compressor 61, and then the high-temperature and high-pressure state refrigerant vapor dissipates heat and condenses in the outdoor unit 62, and then the condensed refrigerant liquid is expanded in the expansion valve 63. The refrigerant liquid expands to a low temperature and low pressure state, and then the refrigerant liquid in the low temperature and low pressure state absorbs heat and evaporates in the indoor unit 64, and the evaporated refrigerant vapor is supplied to the compressor 61 again. It is configured as follows.
The compression heat pump circuit 60 uses the heat radiation of the refrigerant vapor in the outdoor unit 62 for heating hot water or heating in the form of heating the outside air or hot water, while the indoor unit 64 uses the refrigerant liquid. This heat absorption can be utilized for cooling or the like in the form of cooling indoor air or cooling water.
When heating is performed by the compression heat pump circuit 60, the four-way switching valve 65 is switched so that the discharge side of the compressor 61 is directed to the indoor unit 64 and the inflow side is directed to the outdoor unit 62. At 64, warm heat can be generated.

Further, when the compression heat pump circuit 60 is operated, the shaft output of the engine 50 is transmitted to the compressor 61 through a belt transmission unit 70 including a belt and a pulley and a compressor clutch 71. That is, the compressor 61 is configured to operate as a fluid pump that compresses the refrigerant vapor by using the shaft output of the engine 50 as a drive source.
In addition, the shaft output for driving the compressor 61 includes the temperature of the outside air that is the heat radiation destination of the refrigerant vapor in the outdoor unit 62, the temperature of the indoor air that is the heat absorption source of the refrigerant liquid in the indoor unit 64, and the refrigerant It corresponds to the thermal load required from the pressure state and flow rate state. That is, a load corresponding to the compression load of the operating compressor 61, that is, the heat load of the compression heat pump circuit 60, is applied to the crankshaft 9 of the engine 50 through the belt transmission portion 70 and the like. .

The compressor-type heat pump circuit 60 includes three compressors 61a, 61b, and 61c arranged in parallel, and the shaft output of the engine 50 is compressed separately for each of the compressors 61a, 61b, and 61c. It is transmitted through the machine clutches 71a, 71b, 71c.
Accordingly, the control device 30 is operated by transmitting and receiving the shaft output of the engine 50 among the three compressors 61a, 61b, and 61c by turning on and off the compressor clutches 71a, 71b, and 71c. The number of can be changed.
Although a plurality of the compressors 61 are specifically provided, the number of the compressors 61 can be appropriately changed. Further, when only one compressor 61 is provided, the compressor 61 is always operated, so the compressor clutch 71 may be omitted.

Further, the heat pump system 100 is provided with a generator 80 that uses the shaft output of the engine 50 as a drive source, and the shaft output of the engine 50 is transmitted to the generator 80 through a generator clutch 81.
The power for driving the generator 80 is in accordance with the power generation load of the generator 80. That is, the shaft output of the generator 80, that is, a load corresponding to the power generation load is applied to the crankshaft 9 of the engine 50 through the generator clutch 81 and the like.

Therefore, the engine load corresponding to the sum of the heat load in the compression heat pump circuit 60 and the power generation load of the generator 80 is added to the crankshaft 9 of the engine 50.
When power generation by the generator 80 is not necessary, the generator 80 can be stopped without disconnecting the generator clutch 81 and transmitting the shaft output of the engine 50 to the generator 80.
Of course, this generator 80 may be omitted, and when the generator 80 is omitted, the engine load applied to the engine 50 corresponds to the heat load of the compression heat pump circuit 60. .

  As described above, in the load control of the engine 50, the control device 30 performs the four-stroke cycle operation when the engine load is in the rated load region, and performs the six-stroke cycle operation when the engine load is in the medium load region. When the engine load is in a low load range, the eight-stroke cycle operation is performed, and the number of one-stroke strokes is controlled based on the engine load.

That is, in the load control, the control device 30 first detects the heat load in the compression heat pump circuit 60, that is, the sum of the compression load of the working compressor 61 and the power generation load of the generator 80 as the engine load, and the engine load It is determined whether the vehicle is a high load region, a medium load region, or a low load region, and switching between the four-stroke cycle operation, the six-stroke cycle operation, and the eight-stroke cycle operation is performed according to each load region. .
In addition, when the power generation load of the generator 80 is substantially constant, switching between the 4-stroke cycle operation, the 6-stroke cycle operation, and the 8-stroke cycle operation according to only the thermal load of the compression heat pump circuit 60 may be performed. I do not care.

Moreover, the control apparatus 30 performs the operation | movement compressor control which reduces the number of operation | movement compressors which operate | moves among the three compressors 61a, 61b, 61c, so that the thermal load of the compression heat pump circuit 60 falls. At the same time, the number of one-stroke cycles can be changed according to the number of operating compressors.
That is, when the heat load of the compression heat pump circuit 60 is high and the engine load is in a high load range, the control device 30 causes the three compressors 61 to be operating compressors and causes the engine 50 to be operated in a four-stroke cycle. When the heat load of the compression heat pump circuit 60 is reduced and the engine load is in the middle load range, the two compressors 61 are used as operating compressors and one compressor 61 is stopped, and the engine 50 is operated for six strokes. When the cycle operation is performed and the heat load of the compression heat pump circuit 60 is further reduced and the engine load is in a low load range, the one compressor 61 is used as an operating compressor and the two compressors 61 are stopped, and the engine 50 is cycled for 8 strokes. In this way, by changing the number of one-stroke cycles according to the number of working compressors, the number of revolutions of the working compressor is always kept high, and a reduction in engine efficiency due to a reduction in the number of revolutions of the engine 50 is prevented. be able to.

  In the case where such an operation compressor control is not executed, when the number of one-stroke cycles is increased in the load control, the engine speed is prevented from decreasing due to the decrease in the rotational speed of the compressor 61. The shaft output of 50 may be configured to be transmitted to the compressor 61 via a transmission, and the rotational speed of the engine 50 may be constantly maintained at a high level by the transmission.

  The engine according to the present invention can be effectively used as an engine capable of changing the shaft output in a wide range and with high efficiency in response to a large decrease in engine load while suppressing an increase in pumping loss. Such a heat pump system can be effectively used as a heat pump system that includes such an engine and can be operated at a high COP.

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 Explanatory diagram schematically showing the state of 8-stroke cycle operation Explanatory diagram schematically showing the state of load control Schematic configuration diagram of heat pump system

Explanation of symbols

1: intake valve 4: piston 10: combustion chamber 21: variable valve timing mechanism 30: control device 50: engine 60: compression heat pump circuits 61, 61a, 61b, 61c: compressor 100: heat pump system

Claims (6)

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 load is in the rated load region, and the increased stroke cycle operation is performed when the engine load is in the partial load region lower than the rated load region. An engine comprising control means for controlling the number based on the engine load.   In the form in which the control means advances or retards the closing timing of the intake valve in the intake stroke with respect to the bottom dead center as the engine load decreases within a range not accompanied by a change in load range, The engine according to claim 1, wherein the closing timing of the intake valve is controlled based on the engine load.   3. 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 lifting stroke in which the piston is lifted in the same sealed state. engine.   The engine according to any one of claims 1 to 3, wherein in the increase stroke cycle operation, one or more of the pair of pause strokes are added between the exhaust stroke and the intake stroke. . The four-stroke cycle operation, the six-stroke cycle operation as the increased stroke cycle operation that operates by adding one pair of pause strokes in the one cycle, and two pairs of pause strokes in the one cycle In the form of selectively switching the 8-stroke cycle operation as the increased stroke cycle operation, the number of 1-cycle strokes can be switched between 4, 6, and 8.
The control means performs the 4-stroke cycle operation when the engine load is in a rated load range, and performs the 6-stroke cycle operation when the engine load is in a medium load range lower than the rated load range, 5. The number of one-stroke processes is controlled based on the engine load in a form in which the eight-stroke cycle operation is performed when the engine load is in a low load area lower than the medium load area. The engine according to one item.   A heat pump system comprising: the engine according to any one of claims 1 to 5; and a compression heat pump circuit having a compressor using a shaft output of the engine as a drive source.

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