JP2008121572A - Engine start device and engine start method for cogeneration system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine start device and an engine start method for a cogeneration system capable of smoothly starting an engine by decompressing the inside of a combustion chamber without adding a mechanical decompression device. <P>SOLUTION: This device is provided with the engine 2 including the combustion chamber 20, an intake air passage 3 supplying mixed gas containing air and fuel into the combustion chamber 20, a throttle valve 31 provided in the intake air passage 3 in such a manner that the valve can be opened and closed and adjusts the supply quantity of mixed gas into the combustion chamber 20, an ignition device 4 igniting mixed gas in the combustion chamber 20, and a motor generator 5 supplying torque to the engine 2 during start and generating electric power outputted by the rotary drive of the engine 2 by the combustion of mixed gas in the combustion chamber 20 during normal operation. A throttle valve 31 fully closes the intake air passage when torque supply from the motor generator 5 to the engine 2 is started. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cogeneration system that outputs electric power energy and thermal energy, and relates to an engine starting method and an engine starting device of a cogeneration system that starts cranking by obtaining rotational torque from a motor generator at the time of starting.

  The cogeneration system is a system that generates power by converting the driving force of an engine into electric power by a motor generator, and recovers exhaust heat generated by the power generation and effectively uses it as thermal energy. This cogeneration system has attracted attention in recent years from the viewpoint of effective use of energy.

  When starting the engine, since the gas in the combustion chamber is compressed, a high load is applied to the motor generator functioning as the engine starting device. For this reason, a great amount of power is consumed at the time of starting. In order to eliminate this drawback, conventionally, the combustion chamber of the engine has been decompressed (decompressed) at the time of starting.

  As a technique related to decompression, for example, in Patent Document 1, the operation of a decompression switch causes the motor to rotate clockwise and the rocker arm to rotate via a pinion, decompression gear, and decompression shaft. Thereby, the opening / closing timing of the intake valve / exhaust valve is varied to bring the combustion chamber into a decompressed state. When the engine speed increases after starting, it is necessary to cancel the decompression state and return to normal operation. In this case, the current generated from the motor generator is caused to flow through the decompression switch, and the decompression switch is operated on the side opposite to that at the start. In this case, the DC motor rotates in the reverse direction, and the rocker arm rotates in the reverse direction to return to the normal operation.

Moreover, in patent document 2, the sickle-shaped weight is attached to the cam shaft of a rocker arm so that rocking is possible. The sickle-shaped weight is swung by centrifugal force when the engine speed reaches a predetermined speed, and the decompressed state is automatically released to the compressed state.
Japanese Examined Patent Publication No. 52-7103 Japanese Utility Model Publication No.59-43603

  However, in Patent Document 1, a mechanical decompression device dedicated to decompression, such as a DC motor, decompression gear, and decompression shaft, is required to bring the combustion chamber into a decompressed state. Patent Document 2 also provides a sickle-shaped weight for switching from the decompressed state to the compressed state. For this reason, in Patent Documents 1 and 2, a separate mechanical decompression device is added to the original engine mechanism, leading to an increase in cost.

  The present invention has been made in view of such circumstances, and provides an engine start method and an engine start device for a cogeneration system that can smoothly start the engine by reducing the pressure in the combustion chamber without adding a mechanical decompression device. It is something to be offered.

  A first means for solving the above problems includes an engine having a combustion chamber, an intake passage for supplying a mixed gas containing air and fuel into the combustion chamber, and an openable and closable opening in the intake passage. A throttle valve that adjusts the supply amount, an ignition device that ignites the gas mixture in the combustion chamber, a motor generator that supplies rotational torque to the engine at the start and generates electric power by being rotated by the engine during normal operation; In the engine starting method of the cogeneration system comprising: when starting the supply of rotational torque from the motor generator to the engine, the intake passage is fully closed by the throttle valve.

  In the first means, the intake passage is fully closed by the throttle valve when the supply of rotational torque from the motor generator to the engine is started. For this reason, the supply of air can be cut off, and the combustion chamber of the engine can be in a decompressed (decompressed) state. Therefore, the rotation of the engine can be started with a small rotational torque.

  Further, since the intake passage is closed by the throttle valve, the supply of air to the combustion chamber is cut off, unlike the case where the intake passage is slightly opened. For this reason, the mixed gas is not sucked from the intake passage at the time of the intake stroke, and is decompressed to a vacuum pseudo state close to a vacuum state. Therefore, at the time of the next compression stroke, the suction force due to the vacuum pseudo state is also applied, and the engine can start rotating with a very small torque.

  The second means is that after starting the supply of rotational torque from the motor generator to the engine, when the engine reaches a rotational speed at which the mixed gas in the combustion chamber can be ignited, the ignition device Ignit the gas mixture in the combustion chamber. When the mixed gas in the combustion chamber is ignited when the number of revolutions at which the engine can be ignited is reached, the mixed gas is combusted by ignition and the engine starts to rotate. For this reason, a rotational driving force can be generated by the engine. Here, the rotational speed at which the mixed gas in the combustion chamber can be ignited refers to the engine rotational speed at which the mixed gas can be ignited and started to burn without being misfired when ignited by the ignition device.

  The third means stops the supply of rotational torque from the motor generator to the engine when the engine reaches a rotational speed at which the engine can be rotationally driven by combustion of the mixed gas. When the engine reaches a rotational speed at which it can be rotationally driven by combustion of the mixed gas, it can be rotationally driven by the engine alone without the supply of rotational torque from the motor generator. For this reason, when the rotation speed is reached, the supply of the rotational torque from the motor generator is stopped, whereby the entire rotational driving force received by the motor generator from the engine can be output to the outside as electric power. Here, the term “rotation drive by itself” means that the engine alone is driven to rotate without supply of rotation torque from the motor generator.

  The fourth means is an engine having a combustion chamber, an intake passage for supplying a mixed gas containing air and fuel into the combustion chamber, and an openable / closable opening in the intake passage to adjust the supply amount of the mixed gas into the combustion chamber. A cogeneration system comprising: a throttle valve; an ignition device that ignites a gas mixture in the combustion chamber; and a motor generator that supplies rotational torque to the engine at the start and generates electric power by being rotated by the engine during normal operation In the engine starter of the system, the throttle valve is set so that the intake passage is fully closed when the supply of rotational torque from the motor generator to the engine is started.

  The fourth means fully closes the intake passage by the throttle valve when starting the supply of rotational torque from the motor generator to the engine. For this reason, the supply of the mixed gas containing air and fuel can be cut off, and the combustion chamber of the engine can be in a decompressed state. Therefore, the rotation of the engine can be started with a small rotational torque.

  According to the engine starting method and the engine starting device of the cogeneration system of the present invention, the intake passage is fully closed by the throttle valve when starting the supply of rotational torque from the motor generator to the engine. For this reason, the supply of the mixed gas containing air and fuel can be cut off, and the combustion chamber of the engine can be in a decompressed state. Therefore, the rotation of the engine can be started with a small rotational torque.

  Thus, the combustion chamber can be brought into a decompressed state by fully closing the opening of the throttle valve, which has been conventionally used, at the time of starting. For this reason, it is not necessary to newly add a mechanical decompression device, and an increase in cost can be suppressed.

  As described above, according to the present invention, it is possible to provide an engine starting method and an engine starting device for a cogeneration system that can smoothly start an engine by reducing the pressure in a combustion chamber without adding a mechanical decompression device. Can do.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, the engine starter 1 of the cogeneration system of this example includes an engine 2 having a combustion chamber 20, an intake passage 3 that supplies a mixed gas containing air and fuel into the combustion chamber 20, A throttle valve 31 is provided in the passage 3 so as to be openable and closable, and adjusts the supply amount of the mixed gas into the combustion chamber 20; an ignition device 4 for igniting the mixed gas in the combustion chamber 20; And a motor generator 5 that generates electric power by being rotated and driven by the engine 2 during normal operation. The throttle valve 31 is set so that the intake passage 3 is fully closed when the supply of rotational torque from the motor generator 5 to the engine 2 is started.

  In addition to the engine starter 1, the cogeneration system has an exhaust passage 6 and an exhaust heat recovery unit 7 for heat output.

  The motor generator 5 is connected to the engine 2 and is connected to a domestic commercial power system 59. When the engine is started, the motor generator 5 receives electric power from the commercial power system 59 and supplies rotational torque to the engine 2. During normal operation, the motor generator 5 receives the rotational driving force from the engine 2, converts the rotational driving force into electric power, and outputs the electric power to the commercial power system 59. Since the electric power generated by the motor generator 5 is a three-phase alternating current, it is once converted into direct current by the inverter 58 and further converted into a single-phase alternating current and output to the commercial power system 59.

  The engine 2 starts to rotate by receiving the supply of rotational torque from the motor generator 5 at the start, and is rotated by combustion of a mixed gas containing fuel and air supplied from the intake passage 3 during normal operation. The engine 2 includes a main body 21, a cylindrical combustion chamber 20 formed inside the main body 21, a piston 22 that moves up and down in the combustion chamber 20 in the axial direction, and a crank connected to the motor generator 5. The shaft 24 is connected to the piston 22 and the crankshaft 24, and has a connecting rod 23 that converts the reciprocating motion of the piston 22 into a rotational motion and transmits it to the crankshaft 24. In the upper part of the combustion chamber 20, an intake port 203 connected to the intake passage 3 and an exhaust port 206 connected to the exhaust passage 6 are opened, and an ignition plug 41 constituting the ignition device 4 is mounted. Yes. The intake port 203 and the exhaust port 206 are provided with an intake valve 204 and an exhaust valve 207, respectively, that can be opened and closed. The intake valve 204 and the exhaust valve 207 are connected to the crankshaft 24 of the engine 2 and open and close in synchronization with the rotation of the crankshaft 24. The engine 2 is a four-cycle gas engine, and the intake valve 204 and the exhaust valve 207 are opened and closed in the same manner as before in each stroke of intake, compression, combustion, and scavenging. Further, the engine 2 is provided with a water jacket 27 for cooling water to flow and cool the engine.

  The intake passage 3 is a passage for supplying a mixed gas containing air and fuel to the combustion chamber 20 of the engine 2. The intake passage 3 includes an air passage 32 for supplying air, a fuel passage 34 for supplying fuel, a mixed gas passage 30 through which a mixed gas of air and fuel flows by joining the air passage 32 and the fuel passage 34. It has. The mixed gas passage 30 is provided with a throttle valve 31 that adjusts the amount of the mixed gas supplied to the combustion chamber 20.

  The throttle valve 31 is a valve body provided in the mixed gas passage 30 so as to be openable and closable, and is a stepping motor that is operated by an electric signal received from the control unit 811. The throttle valve 31 is in a slightly open state when the engine is stopped. When the engine start is instructed, the throttle valve 31 is set to be in a fully closed state from a slightly opened state by the rotation of the motor. The opening and closing of the throttle valve 31 is controlled by a control unit 811 described later so that a desired opening degree is obtained in each stroke.

  The air passage 32 is provided with an air cleaner 33 for removing dust contained in the air. The upstream side of the fuel passage 34 is connected to a fuel supply source 35 that supplies fuel gas. In the middle of the fuel passage 34, gas electromagnetic valves 361, 362, a governor 37, a buffer tank 38, and a fuel valve 39 are provided in this order from the upstream side. The gas solenoid valves 361 and 362 start and stop the supply of fuel from the fuel supply source 35. The governor 37 is a pressure adjusting valve, and adjusts the fuel supply amount so that the pressure of the fuel gas becomes atmospheric pressure. A part of the fuel is stored in the buffer tank 38, and the wave in the fuel passage 34 at the time of start-up is absorbed and suppressed by the fuel in the tank. The opening / closing amount of the fuel valve 39 is adjusted by a stepping motor that is operated by an electric signal from the control unit 811. The fuel valve 39 is provided in the vicinity of the junction 320 with the air passage 32, and adjusts the mixing ratio with air so that the concentration becomes optimum for combustion according to the type of fuel used.

  A fuel gas such as city gas or propane gas is used as the fuel.

  The ignition device 4 includes an ignition plug 41 provided in the upper portion of the combustion chamber 20 and an igniter 42 that converts supply power into a high voltage so that a spark is generated from the ignition plug 41.

  Exhaust gas discharged from the exhaust port 206 of the combustion chamber 20 passes through the exhaust passage 6. The exhaust passage 6 is provided with a gas heat exchanger 611, an exhaust silencer 612, and a drain trapper 613 in order from the upstream side. The gas heat exchanger 611 exchanges heat of exhaust gas passing through the exhaust passage 6 with cooling water flowing through the cooling water passage 73. The exhaust silencer 612 gradually reduces the pressure and temperature of the exhaust gas to near the state of the outside air to reduce the exhaust noise. The drain trapper 613 collects the liquid contained in the exhaust gas. A drain passage 62 is connected to the gas heat exchanger 611, the exhaust silencer 612, and the drain trapper 613, and the drain generated from the exhaust gas is recovered. The drain passage 62 is provided with a neutralizer 621 for neutralizing the drain. The collected drain is neutralized by the neutralizer 621 and discharged to the outside.

  The exhaust heat recovery unit 7 includes a cooling water passage 73 through which cooling water for cooling the combustion chamber flows, and a hot water passage 74 through which hot water heated by heat exchange with the cooling water flows.

  The cooling water passage 73 includes a pump 731 that circulates the cooling water, and a water heat exchanger 732 that performs heat exchange between the cooling water flowing through the cooling water passage 73 and the hot water flowing through the hot water passage 74. The pump 731 circulates the cooling water through the water jacket 27, the gas heat exchanger 611, and the water heat exchanger 732 of the engine 2. The cooling water passage 73 is connected to the surplus water passage 734. The surplus water passage 734 has a reserve tank 735 for storing the amount of overflow of the cooling water during operation and a radiator cap 736 for adjusting the water pressure of the cooling water.

  Thermistors 730 and 733 are mounted near the inlet to the engine 2 and near the outlet of the gas heat exchanger 611 in the cooling water passage 73, respectively. The thermistors 730 and 733 detect the temperature of the cooling water and send a detection signal to the pump 731. The pump 731 receives the detection signals from the thermistors 730 and 733 and adjusts the flow rate of the cooling water so that the cooling water falls within a predetermined temperature range. In this manner, the thermistors 730 and 733 and the pump 731 are adjusted so that the cooling water falls within a predetermined temperature range.

  The cooling water passage 73 has a heat exchange passage 737 provided with a water heat exchanger 732 and a bypass passage 738 provided with no water heat exchanger 732. A thermo valve 739 is provided at a branch point between the heat exchange passage 737 and the bypass passage 738. The thermo valve 739 closes the heat exchange passage 737 and opens the bypass passage 738 when the coolant at the time of starting the engine is at a low temperature. In this case, the cooling water passes through the bypass passage 738 without passing through the heat exchange passage 737. Thereby, the temperature drop of the cooling water by the water heat exchanger 732 is prevented, and the engine 2 is warmed up early. When the temperature of the cooling water rises by driving the engine and reaches a predetermined temperature or higher (during normal operation), the thermo valve 739 opens the heat exchange passage 737 and closes the bypass passage 738. In this case, the cooling water passes through the heat exchange passage 737. As a result, the exhaust heat generated in the engine 2 is output to the hot water passage 74 via the cooling water passage 73 and the water heat exchanger 732.

  The hot water passage 74 is a passage through which hot water flows, and is provided with a pump 741 that transports the hot water and a hot water storage tank 742 that stores the transported hot water. The temperature of the hot water flowing through the hot water passage 74 is generally lower than that of the cooling water flowing through the cooling water passage 73. For this reason, the hot water flowing through the hot water passage 74 receives heat by heat exchange with the cooling water when passing through the water heat exchanger 732. The hot water passage 74 has a tank passage 743 in which the hot water storage tank 742 is provided, and a bypass passage 744 in which the hot water storage tank 742 is not provided. A three-way switching valve 745 is provided at a branch point between the tank passage 743 and the bypass passage 744. The three-way switching valve 745 stops hot water from flowing into the hot water storage tank 742 by flowing hot water into the bypass passage 744 when the hot water at the time of starting the engine is low, and the tank when the hot water becomes higher than a predetermined temperature. It switches so that hot water may flow into the passage 743.

  Therefore, when the pumps 731 and 741 are driven during normal engine operation, the exhaust heat of the engine is recovered as hot water in the hot water storage tank 742 via the cooling water passage 73 and the hot water passage 74. Hot water stored in the hot water storage tank 742 is used in a bath, kitchen, or the like.

  The cogeneration system is divided into an engine unit 81 that houses the engine starter 1, the exhaust passage 6 and the cooling water passage 73, and a hot water storage unit 82 that contains a hot water storage tank 742. The engine unit 81 and the hot water storage unit 82 are connected by a hot water passage 74 of the exhaust heat recovery unit 7.

  The engine unit 81 and the hot water storage unit 82 are equipped with control units 811 and 821, respectively. The control units 811 and 821 receive instructions by operating either the bath remote controller 83 or the kitchen remote controller 84 that are remotely installed. The control unit 811 is an electronic control circuit, receives detection signals from a sensor that detects the engine speed in the engine unit 81, a sensor that detects the motor generator speed, and the thermistors 731 and 733, and receives these detection signals. Based on this, control signals for controlling various devices in the engine unit 81 including the motor generator 5, the ignition device 4, the fuel valve 39, the gas electromagnetic valves 361 and 362, the throttle valve 31, and the pumps 731 and 741 are created. The generated control signal is transmitted to the various devices. The control unit 821 is an electronic control circuit, receives a detection signal from a temperature sensor that detects the temperature of the hot water passage 74 and the hot water storage tank in the hot water storage unit 82, and in the hot water storage unit 82 based on this detection signal. A control signal for controlling various devices in the hot water storage unit 82 including the three-way switching valve 745 and the pump 741 is created, and the created control signal is transmitted to the various devices.

  The cogeneration system of this example is equipped with a self-supporting power generation unit (not shown). In the event of a power failure, the self-sustaining power generation unit starts the engine by supplying power required for starting with an emergency battery.

  Next, the engine starting method of the cogeneration system of this example will be described with reference to FIGS.

(T1: Driving instruction)
The bath remote controller 83 or the kitchen remote controller 84 instructs to start the cogeneration system. Then, in accordance with an instruction from the control unit 811, the throttle valve 31 provided in the intake passage 3 is fully closed, and the supply of the mixed gas to the combustion chamber 20 is cut off. Further, the fuel valve 39 provided in the fuel passage 34 is opened. Thus, a standby state is established so that fuel is immediately supplied to the combustion chamber 20 in preparation for the opening of the throttle valve 39. At this time, the piston 22 of the engine 2 may be located at the bottom dead center, the top dead center, or an intermediate point between the bottom dead center and the top dead center, but is located near the top dead center for load reduction. It is preferable. Both the intake valve and the exhaust valve are closed.

(T2: Start cranking)
When the standby state of the fuel valve 39 is ready, the motor generator 5 starts supplying rotational torque (cranking) to the engine 2. At this time, the throttle valve 3 is still fully closed. When cranking starts, the engine 2 starts to rotate by the rotational torque received from the motor generator 5. The rotational torque to be supplied is gradually increased. Eventually, when the rotational torque that can be rotated is reached, the crankshaft 24 of the engine 2 starts to be rotated by the motor generator 5. In accordance with this rotation, the opening and closing of the intake valve 204 and the exhaust valve 207 and the vertical movement of the piston 22 are started.

  The operation timing of opening and closing of the intake valve 204 and the exhaust valve 207 and the vertical movement of the piston 22 is the same operation timing as intake, compression, combustion, and exhaust during normal operation. 1) Intake valve open, exhaust valve close, piston lowering 2) Intake valve closing, exhaust valve closing, piston raising, 3) Intake valve closing, exhaust valve closing, piston lowering, 4) Intake valve closing, exhaust valve opening, piston raising process are repeated. While the strokes 1) to 4) are being performed, when the intake valve 204 of 1) is opened, the throttle valve 31 is in a fully closed state, so that the mixed gas is not supplied from the intake port 203 to the combustion chamber 20. For this reason, the inside of the combustion chamber 20 is decompressed to a state close to a vacuum by the lowering of the piston 22. In the next stroke 2), the piston 22 moves up in the combustion chamber 20 in the decompressed state. For this reason, the piston 22 can ascend in the combustion chamber 20 with a low supply torque without receiving a compression resistance from a rare gas in a decompressed state in the combustion chamber 20.

(T3: ignition start)
After the engine 2 starts to rotate due to the rotational torque supplied from the motor generator 5, it is confirmed that the engine 2 has reached a predetermined rotational speed a (1000 rpm in this example). The predetermined rotational speed a is when the engine 2 reaches a rotational speed at which rotational torque can be generated by combustion. When the predetermined rotational speed a is reached, the ignition device 4 starts ignition of the gas in the combustion chamber 20. The ignition operation timing is the step 3). After the ignition is started, the engine speed is maintained when the predetermined speed is reached until the next fuel supply start stroke. This is to wait until the engine 2 rotates smoothly.

(T4: Start fuel supply)
After starting ignition, the gas solenoid valves 361 and 362 are opened, and the throttle valve 31 is gradually opened from the fully closed state. As a result, a mixed gas containing fuel and air is sucked into the combustion chamber 20 via the intake port 203. Since the combustion chamber 20 has already been ignited by the ignition plug 41, the mixed gas sucked into the combustion chamber 20 is ignited and burned. Due to the combustion, the piston 22 starts to drive itself with the help of the supply torque from the motor generator 5.

  Here, in this example, the throttle valve is opened after a predetermined time has elapsed after the ignition is started, and the mixed gas is supplied into the combustion chamber. This is for suppressing unburned fuel. From the viewpoint of suppressing power consumption at start-up, as long as cranking is started, the throttle valve may be opened at any time to supply the mixed gas to the combustion chamber, or at the same time as the start of ignition. But you can.

  The opening speed of the throttle valve is about 20% of the full opening in 10 seconds, that is, 2% in 1 second in this example. The valve opening speed is preferably 0.5 to 6% / s. Thereby, it can ignite quickly, suppressing unburned fuel.

(T5: Start of engine start)
After the fuel supply is started, it is confirmed that the engine speed increases and reaches a predetermined speed b (1500 rpm in this example). At this time, even if the rotational torque is not received from the motor generator 5, the engine is in a state where it can be rotationally driven by the combustion of the mixed gas by itself. Therefore, when it is confirmed that the predetermined rotational speed has been reached, the supply of rotational torque from the motor generator 5 to the engine 2 is stopped. Thereby, even if there is no supply of rotational torque from the motor generator 5, the engine alone is driven to rotate. Further, since the supply of rotational torque from the motor generator 5 to the engine 2 is stopped, the rotational torque used in the motor generator 5 is reduced. For this reason, at the same time as the supply of rotational torque to the engine 2 is stopped, the rotational speed and power output of the motor generator 5 increase. Further, by reducing the opening degree of the fuel valve 39, the blending ratio of air is lowered to the normal operation level. At this stage, the throttle valve 31 is about 50% fully open.

  Further, the pump 731 of the cooling water passage 73 and the pump 741 of the hot water passage 74 start to operate. Thereby, the cooling water circulates around the water jacket 27 and the gas heat exchanger 611 around the combustion chamber of the engine 2 to perform heat exchange. Further, the cooling water and the hot water exchange heat in the water heat exchanger 732 and are output as hot water.

(T6: Power generation instruction)
When the completion of warm-up is confirmed after the engine start is confirmed, the motor generator 5 is instructed to output electric power. As a result, electric power is output from the motor generator 5 to the commercial power grid 59, and normal (load following) operation is started. The generated power from the motor generator 5 is 750-1500W.

  For a while after the power generation instruction, the opening of the throttle valve 31 gradually increases. The engine speed and the motor generator speed increase or decrease according to the opening of the throttle valve 31. Thereafter, the event control mode is set, and the outputs of the engine 2 and the motor generator 5 are adjusted by changing the opening of the throttle valve in accordance with the degree of power demand and heat demand.

  FIG. 3 shows the required time, electric power and fuel consumption in the engine starting process.

  In this example, the intake passage 3 is fully closed by the throttle valve 31 when the supply of rotational torque from the motor generator to the engine is started in the stroke t2 (start of cranking). For this reason, the supply of air can be cut off, and the combustion chamber of the engine can be in a decompressed (decompressed) state. Further, since the supply of air to the combustion chamber is interrupted, the combustion chamber can be brought into a vacuum state at the time of suction 1). For this reason, in the next stroke 2), the suction force due to the vacuum state in the combustion chamber is also applied, and the piston 22 can start to rise with a very small force. Therefore, the engine can be started to rotate with a very small rotational torque. Therefore, as shown in FIG. 3, the amount of electric power consumed at the time of starting can be kept low.

  Moreover, the combustion chamber is in a decompressed state by fully closing the opening of the throttle valve that has been conventionally used. For this reason, it is not necessary to newly add a mechanical decompression device, and an increase in cost can be suppressed.

  The engine of the cogeneration system of this example is a four-cycle engine, but can be applied to a two-cycle engine and a rotary engine. Furthermore, although the gas engine is started in this example, the present invention can also be applied to an engine driven by liquid fuel such as gasoline, light oil, and kerosene.

  The cogeneration system of this example is for general households, but the present invention can also be applied to business use.

It is an operation principle figure of the cogeneration system of the present invention. It is a graph which shows the engine starting method and operating state of the cogeneration system of this invention. It is explanatory drawing which shows the required time of each process at the time of engine starting of this invention, power consumption, and fuel consumption.

Explanation of symbols

1 is an engine starter, 2 is an engine, 20 is a combustion chamber, 203 is an intake port, 204 is an intake valve, 206 is an exhaust port, 207 is an exhaust valve, 22 is a piston, 3 is an intake passage, 30 is a mixed gas passage, 31 is a throttle valve, 32 is an air passage, 33 is an air cleaner, 34 is a fuel passage, 361 and 362 are gas solenoid valves, 37 is a governor, 38 is a buffer tank, 39 is a fuel valve, 4 is an ignition device, and 41 is an ignition plug Reference numeral 5 denotes a motor generator, 6 denotes an exhaust passage, 7 denotes an exhaust heat recovery unit, 71 denotes an exhaust gas passage, 73 denotes a cooling water passage, 74 denotes a hot water passage, and 742 denotes a hot water storage tank.

Claims (4)

An engine having a combustion chamber, an intake passage for supplying a mixed gas containing air and fuel into the combustion chamber, and a throttle valve that is provided in the intake passage so as to be openable and closable and adjusts the supply amount of the mixed gas into the combustion chamber A cogeneration system that ignites the gas mixture in the combustion chamber and a motor generator that supplies rotational torque to the engine at the start and generates electric power by being rotated by the engine during normal operation In the system engine starting method,
An engine starting method for a cogeneration system, wherein when the supply of rotational torque from the motor generator to the engine is started, the intake passage is fully closed by the throttle valve.   After starting the supply of rotational torque from the motor generator to the engine, when the engine reaches a rotational speed at which the mixed gas in the combustion chamber can be ignited, the ignition device 2. The engine starting method for a cogeneration system according to claim 1, wherein the mixed gas in the combustion chamber is ignited.   The supply of rotational torque from the motor generator to the engine is stopped when the engine reaches a rotational speed at which the engine can be rotationally driven by combustion by the mixed gas. The engine starting method of the cogeneration system according to claim 2. An engine having a combustion chamber, an intake passage for supplying a mixed gas containing air and fuel into the combustion chamber, and a throttle valve provided in the intake passage so as to be openable and closable to adjust the supply amount of the mixed gas into the combustion chamber An ignition device that ignites the gas mixture in the combustion chamber, and a motor generator that supplies rotational torque to the engine at the start and generates electric power by being rotated by the engine during normal operation. In the engine starter of the generation system,
The engine starter of a cogeneration system, wherein the throttle valve is set to fully close the intake passage when starting to supply rotational torque from the motor generator to the engine.

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