JP2008038782A - Engine stall preventive control device of engine-driven type heat pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an engine stall, when a user starts operation of an engine-driven type heat pump. <P>SOLUTION: The engine-driven type heat pump 1 has: a fuel quantity adjusting valve 65 adjusting a fuel gas flow rate; a throttle valve 66 adjusting an air-fuel mixture flow rate of air and fuel gas supplied to an engine combustion chamber 51a; and a clutch 9 engaging-disengaging an engine 18 and a compressor 10. A predetermined opening increasing signal is outputted to the throttle valve 66 synchronously with outputting of a connecting signal of the engine 18 and the compressor 10 by the clutch 9. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a configuration and control technology of an engine stall prevention device for an engine-driven heat pump.

Conventionally, an engine-driven heat pump that is one of air conditioners and configured to drive a compressor with an engine is known. The compressor is connected to the engine via a clutch. The compressor is configured such that the power of the engine is turned on and off by turning the clutch on and off.
In the engine-driven heat pump, for example, when the clutch is turned on at the time of startup, engine stall occurs if the engine torque is insufficient. Here, the cause of insufficient engine torque is an increase in rotational inertia mass due to connection with the compressor.
For example, Patent Document 1 discloses a control configuration that prevents engine stall of an engine-driven heat pump. The control configuration of Patent Document 1 attempts to prevent engine stall by increasing the engine speed by increasing the amount of gas mixture to the engine based on the refrigerant pressure when the compressor is connected.
JP 2003-314323 A

However, the control configuration of Patent Document 1 assumes only when driving a second compressor in an engine-driven heat pump equipped with two compressors. That is, the engine-driven heat pump cannot be applied at the start of operation when the refrigerant pressure does not rise.
Therefore, the problem to be solved is to prevent engine stall at the start of operation of the engine-driven heat pump.

  The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

  That is, in claim 1, a fuel metering valve for adjusting a fuel gas flow rate, a throttle valve for adjusting a mixed gas flow rate of air and fuel gas supplied to the engine combustion chamber, and the engine and the compressor An engine-driven heat pump having a clutch mechanism for connecting and disconnecting, wherein a predetermined opening increase signal is output to the throttle in synchronization with a connection signal between the engine and the compressor being output by the clutch mechanism It is.

  According to a second aspect of the present invention, in the engine-driven heat pump according to the first aspect, the predetermined opening degree increase signal indicates a throttle opening degree necessary for returning a decrease in the engine speed due to the connection between the compressor and the engine. This is determined in advance based on the actual measurement result of the increase.

  According to a third aspect of the present invention, in the engine-driven heat pump according to the first aspect, the predetermined opening increase signal is based on a prediction of a decrease in the engine speed due to the connection of the compressor and a speed fluctuation characteristic due to a combustion characteristic of the engine. It is calculated.

  As effects of the present invention, the following effects can be obtained.

  According to the first aspect of the present invention, the engine speed is forcibly increased by increasing the amount of gas mixture into the combustion chamber by a predetermined increase in throttle opening in synchronization with clutch engagement. In this way, it is possible to absorb a drop in engine speed due to an increase in compressor rotational inertia mass when the clutch is engaged. That is, the engine stall can be prevented by reducing the decrease in the engine speed transient that cannot be followed by the conventional engine speed control that is feedback control.

  According to the second aspect, the increase in the throttle opening is determined in advance by experiment. In this way, in addition to the effect of the first aspect, the excess or deficiency of the gas mixture increase due to the increase in the throttle opening can be minimized.

  According to the third aspect of the present invention, the amount of increase in the throttle opening is determined in advance according to the combustion characteristics (used fuel or air-fuel ratio) of the engine. In this way, in addition to the effect of the first aspect, excess and deficiency for the increased amount of air-fuel mixture can be minimized. Further, the actual man-hours can be omitted.

Next, embodiments of the invention will be described.
FIG. 1 is a refrigerant circuit diagram showing an overall configuration of an engine-driven heat pump according to an embodiment of the present invention, FIG. 2 is a schematic diagram showing the configuration of an intake / exhaust system of the engine, and FIG. FIG. 5 is a graph showing an engine speed N.
4 is a block diagram showing the engine stall prevention device, FIG. 5 is a graph showing the engine speed N when the clutch is turned on by engine stall prevention control, and FIG. 6 is a table showing the throttle opening increase ΔP for each model. It is.
FIG. 7 is a table showing the throttle opening increase ΔP for each fuel used, and FIG. 8 is a table showing the throttle opening increase ΔP for the fuel used and the air-fuel ratio.

First, the refrigerant circuit configuration of an engine-driven heat pump 1 that is an embodiment of the present invention will be described in detail with reference to FIG.
As shown in FIG. 1, the engine-driven heat pump 1 is an air conditioner including an outdoor unit 2 and an indoor unit 3. The engine driven heat pump 1 drives the compressor 10 by the engine 8. Connection / disconnection of power to the compressor 10, that is, switching of operation / stop of the compressor 10 is performed by ON / OFF of the clutch 9.
The engine-driven heat pump 1 includes a compressor 10 that obtains power from an engine 8 as a drive source and compresses refrigerant, and a four-way valve that is connected to the discharge side of the compressor 10 and switches the refrigerant flow during cooling and heating. 18, an outdoor heat exchanger 5 to which discharged refrigerant is supplied from the compressor 10 via the four-way valve 18 during cooling, an outdoor fan 11 that exchanges heat between the outdoor heat exchanger 5 and outdoor air, and a compressor during heating An indoor heat exchanger 6 to which discharged refrigerant is supplied from 10 through a four-way valve 18, an indoor fan 12 for exchanging heat between the indoor heat exchanger 6 and indoor air, an outdoor heat exchanger 5 and an indoor heat exchanger 6 And an expansion valve 15 for an outdoor heat exchanger disposed between the two.

  The compressor 10 sucks and compresses the gas refrigerant from the suction side, and discharges the high-temperature and high-pressure gas refrigerant. A four-way valve 18 is connected to the discharge side of the compressor 10 via a discharge path 31. The refrigerating machine oil contained in the gas refrigerant is separated into the discharge path 31 and returned to the suction side of the compressor 10. An oil separator 21 is provided. That is, the gas refrigerant discharged from the compressor 10 flows into the four-way valve 18 through the oil separator 21 and is guided in a predetermined direction by the four-way valve 18. Further, since the gas refrigerant sucked into the compressor 10 is also guided by the four-way valve 18, the refrigerant suction side of the compressor 10 and the four-way valve 18 are connected by the suction path 30.

The four-way valve 18 is connected to one end side of the outdoor heat exchanger 5, and the receiver 20 is connected to the other end side of the outdoor heat exchanger 5. On the other hand, the indoor heat exchanger 6 has one end connected to the receiver 20 via the liquid path 32 and the other end connected to the four-way valve 18.
The waste heat recovery unit 7 branches from between the outdoor heat exchanger expansion valve 15 and the receiver 20 and is provided in a waste heat recovery path 33 connected to the suction path 30. The waste heat recovery path 33 is connected in series in the order of the waste heat recovery unit expansion valve 17, the supercooling heat exchanger 4, and the waste heat recovery unit 7 toward the suction path 30.

  The Electronic Control Unit (hereinafter referred to as ECU 40) controls the engine 8, the clutch 9, each expansion valve, and each electromagnetic valve based on each pressure sensor and temperature sensor to perform cooling or heating operation of the engine-driven heat pump 1. . In this embodiment, it should be noted that an outdoor temperature sensor 29 provided for suction of the outdoor unit 2 and an indoor temperature sensor 28 provided for suction of the indoor unit 3 are connected to the ECU 40.

Next, the engine 8 that is a drive source of the engine-driven heat pump 1 will be described in detail with reference to FIG.
As shown in FIG. 2, the engine 8 is a so-called gas engine using a gaseous fuel such as natural gas, and includes a cylinder block 51, a spark plug 52, an intake valve 53, an exhaust valve 54, a piston 55, a crankshaft 56, A rotary pickup (rotational speed detection means) 57 is provided.
The cylinder block 51 is a member that forms the structure of the engine 8. The combustion chamber 51 a is a space for burning the mixed gas, is formed at the top of the cylinder head 50 and the piston 55 above the cylinder block 51, and can communicate with the intake pipe 41 and the exhaust pipe 43.
The intake pipe 41 is a pipe for taking in air from the outside and supplying the mixed gas generated by mixing the air and fuel by a mixer 60 described later to the engine 8. One end of the intake pipe 41 is provided with an air cleaner 42 for removing dust and the like contained in the air introduced into the intake pipe 41, and the other end of the intake pipe 41 is the intake air above the cylinder block 51 of the engine 8. Connected to the manifold.
The exhaust pipe 43 is a pipe for discharging the exhaust gas generated when the mixed gas burns in the combustion chamber 51 a to the outside of the engine 8. One end of the exhaust pipe 43 is connected to an exhaust manifold above the cylinder block 51 of the engine 8 and the other end is connected to a muffler (not shown).

The spark plug 52 is provided in the cylinder head 50, and the tip thereof is disposed inside the combustion chamber 51a. The spark plug 52 burns the mixed gas supplied to the combustion chamber 51a by generating a spark.
The intake valve 53 is a valve provided in the middle of the intake pipe 41 and the combustion chamber 51a in the cylinder head 50, and connects or closes the intake pipe 41 and the combustion chamber 51a by performing an opening / closing operation.
The exhaust valve 54 is a valve provided in the middle of the exhaust pipe 43 and the combustion chamber 51a in the cylinder head 50, and connects or closes the exhaust pipe 43 and the combustion chamber 51a by performing an opening / closing operation.
The piston 55 is a member that reciprocates by sliding in an airtight manner on the inner peripheral surface of the combustion chamber 51a. The piston 55 slides downward (the direction in which the volume of the combustion chamber 51a increases) when the mixed gas supplied to the combustion chamber 51a burns and expands.
The crankshaft 56 is a shaft pivotally attached to the piston 55 via a connecting rod, and converts the reciprocating motion of the piston 55 into rotational motion.
The rotary pickup 57 is a rotational speed detection means for detecting the rotational speed of the crankshaft 56, that is, the rotational speed of the engine 8.

Next, the mixer 60 which is the fuel mixing means of the engine 8 will be described in detail with reference to FIG.
The mixer 60 is a mixing unit that generates a mixed gas having a desired air-fuel ratio and supplies the mixed gas to the engine 8. The mixer 60 mainly includes a venturi 63, a fuel supply pipe 44, a fuel metering valve 65, and a throttle valve 66.
The venturi 63 is provided on the inner surface of the intake pipe 41 and at a connection portion between the intake pipe 41 and the fuel supply pipe 44. The venturi 63 reduces the pressure of the air passing through the portion where the venturi 63 is provided, thereby generating a differential pressure with the fuel in the fuel supply pipe 44, and sucking the fuel from the fuel supply pipe 44. Supply to the pipe 41. As a result, a mixed gas is generated.
The fuel metering valve 65 is provided in the middle of the fuel supply pipe 44, and the amount of fuel that passes through the fuel supply pipe 44 by changing the opening degree arbitrarily between 0% and 100%, and hence the mixed gas Is a valve that adjusts the amount of fuel contained in the fuel.
The throttle valve 66 is provided in the middle of the intake pipe 41 on the downstream side of the portion where the venturi 63 is provided, and the opening degree is arbitrarily changed between 0% and 100% to the engine 8. This is a valve for adjusting the supply amount of the mixed gas.
In this specification, the “valve opening” is 0% when the valve is closed, and when the valve is fully open, that is, the flow rate of fluid such as gas or liquid passing through the valve is maximum. When it becomes, it is set as 100%.
The ECU 40 adjusts the mixed gas supplied to the combustion chamber 51a by controlling the throttle valve 66 and the fuel metering valve 65 so that the engine speed N detected by the rotary pickup 57 approaches the target speed.

Next, changes in the engine speed N before and after the clutch 9 is connected will be described with reference to FIG.
FIG. 3 shows time-series changes in ON / OFF of the clutch 9, the throttle opening P, and the engine speed N when the engine 8 is started. Here, in FIG. 3, the horizontal axis indicates the time axis, the vertical axis indicates the engine speed N, the opening degree P of the throttle valve 66, and the ON / OFF of the clutch 9.
First, at t0, the engine 8 is started by a cell motor (not shown). Next, at t1, the throttle valve 66 is opened, the mixed gas is sent to the combustion chamber 51a, the spark plug 52 is sparked at a predetermined timing, and the engine 8 starts to rotate independently. Then, at t2, the engine speed N is temporarily increased due to the resistance due to the connection of the clutch 9, the resistance due to the start of compression work in the compressor 10, or the increase of the rotational inertia mass due to the connection with the compressor 10. It decreases (A shown in FIG. 3).
The decrease in the engine speed N after the clutch 9 is connected causes an engine stall (engine stall). At this time, the throttle valve 66 follows the decrease in the engine speed N by feedback control, but cannot follow the transient decrease.

Here, the engine stall prevention device 70 according to the present invention will be described in detail with reference to FIG.
As shown in FIG. 4, the engine stall prevention device 70 is configured to be added to an engine speed control device 71 which is a conventional technique.
The engine speed control device 71 arranges the throttle opening degree calculation means 76, the throttle valve 66 and the engine 8 in the output signal path, the rotary pickup 57 in the feedback path, and the target speed setting means 77 in the input path. It is supposed to be configured.
The engine stall prevention device 70 is arranged so that the output of the throttle opening increase amount setting means 75 intervenes between the throttle opening calculation means 76 and the throttle valve 66 in the output signal path of the engine speed control device 71. It is said that. The throttle opening increase amount setting means 75 operates when a clutch ON signal is input.
With such a configuration, the engine speed N is detected by the rotary pickup 57, and the throttle is set so that the deviation between the engine speed N and the target speed Nm set by the engine target speed setting means 77 becomes small. The throttle opening P is calculated by the opening calculation means 76, and the throttle opening increase amount ΔP preset by the throttle opening increase amount setting means 75 is added to the throttle opening P and adjusted by the throttle valve 66. The mixed gas is sent to the fuel chamber 51a to drive the engine 8.
That is, the throttle opening increase amount ΔP is added to the throttle opening P as feedforward control.

Next, the engine stall prevention control by the engine stall prevention apparatus 70 will be described in detail with reference to FIG.
FIG. 5 shows time-series changes in ON / OFF of the clutch 9, the throttle opening P, and the engine speed N when the engine 8 is started using the engine stall prevention device 70. In FIG. 5, the horizontal axis and the vertical axis are the same as those in FIG.
Here, the process from t0 to t1 is the same as in FIG.
Next, at t2, an increase signal corresponding to the throttle opening increase amount ΔP is output to the throttle opening P in synchronization with the output of the connection signal of the clutch 9. As a result, since the mixed gas is sent to the fuel chamber 51a by the opening amount of ΔP, a decrease in the engine speed N is reduced.
In this way, by adding the throttle opening increase amount ΔP in synchronization with the engagement of the clutch 9, it is possible to reduce the transient decrease in the engine speed N that occurs when the clutch 9 is engaged. That is, the engine stall can be prevented. That is, the engine stall can be prevented by reducing the decrease in the transient of the engine speed N that cannot be followed by the conventional engine speed controller 71 that is feedback control by controlling in advance by the feedforward control.

Here, the throttle opening increase amount setting means 75 will be described.
The throttle opening increase amount setting means 75 is a setting means for setting a throttle opening increase amount ΔP provided in the ECU 40. This throttle opening increase amount ΔP is a value obtained in advance by experiments. The throttle opening increase amount setting means 75 stores at least one optimum value in the throttle opening increase amount setting means 75. In the engine stall prevention control, it is possible to obtain an optimal mixed gas increase amount by storing in consideration of an element correlated with the mixed gas increase amount.
Hereinafter, three embodiments of the throttle opening increase amount setting means 75 will be described.

First, the throttle opening increase amount setting means 75a will be described as a first embodiment with reference to FIG.
The engine-driven heat pump 1 has a different rated output for each model. The rated output is the output of the compressor 10, that is, the output of the engine 8. Therefore, in the engine stall prevention control, the amount of gas mixture to be increased is correlated with the model.
As shown in FIG. 6, the throttle opening increase amount setting means 75a has a throttle opening increase amount ΔP for each model of the engine-driven heat pump 1, that is, for each rated output. The throttle opening increase amount setting means 75a acquires a model from the ECU 40 and calculates a throttle opening increase amount ΔP corresponding to the model. The model is set by a setting switch or the like when the engine-driven heat pump 1 is manufactured.
In this way, the throttle opening increase amount ΔP can be determined for each rated output, and the excess or deficiency of the mixed gas increase amount can be minimized.

Next, the throttle opening increase amount setting means 75b will be described as a second embodiment with reference to FIG.
Usually, the fuel used varies depending on the environment in which the engine-driven heat pump 1 is installed. In addition, the amount of heat generated varies depending on the type of fuel used. For example, when the calorific values of the fuels shown in FIG. 8 are compared, natural gas <city gas (13A) <propane <butane in order of increasing calorific value. Therefore, in the engine stall prevention control, the amount of gas mixture to be increased is correlated with the fuel used.
As shown in FIG. 7, the throttle opening increase amount setting means 75 b has a throttle opening increase amount ΔP for each fuel used in the engine-driven heat pump 1. The throttle opening increase amount setting means 75b acquires the fuel used from the ECU 40 and calculates a throttle opening increase amount ΔP corresponding to the fuel used. The fuel used is set with a setting switch or the like when the engine-driven heat pump 1 is installed.
In this way, the throttle opening increase ΔP is determined for each fuel used, and the excess or deficiency of the mixed gas increase can be minimized.

Next, the throttle opening increase amount setting means 75c will be described as a third embodiment with reference to FIG.
The throttle opening increase amount setting means 75c is a setting means in which the throttle opening increase amount setting means 75b is further set for each fuel ratio at the air-fuel ratio.
In the engine 8, the fuel metering valve 65 is an opening valve that determines the ratio of air to fuel (air-fuel ratio) in the mixed gas (see FIG. 2). Therefore, in the engine stall prevention control, the amount of gas mixture to be increased is correlated with the fuel metering valve 65.
In addition, each fuel used has a different combustion range (a mass of fuel combusted when the air mass is 100% in the air). For example, LP gas has a combustion range of about 1.8% to about 9.5%, and city gas (13A) has a combustion range of about 5.0% to about 15.0%. Therefore, in the engine stall prevention control, the amount of gas mixture to be increased is correlated with the fuel used and the opening of the fuel metering valve 65.
As shown in FIG. 8, the throttle opening increase setting means 75c shows each fuel of the engine-driven heat pump 1 as a column, shows every opening of the fuel metering valve 65 as a row, and increases each throttle opening. It has a quantity ΔP. The throttle opening increase amount setting means 75c acquires the opening of the fuel metering valve 65 from the ECU 40, and calculates the throttle opening increase ΔP corresponding to the opening.
In this manner, the throttle opening increase ΔP is determined for each fuel and air-fuel ratio, and the excess or deficiency of the mixed gas increase can be minimized.

The refrigerant circuit figure which showed the whole structure of the engine drive type heat pump which concerns on the Example of this invention. The schematic diagram which similarly showed the structure of the intake-exhaust system of an engine. The graph which showed the engine speed N at the time of clutch ON. The block diagram which showed the engine stall prevention apparatus. The graph which showed the engine speed N at the time of clutch ON by engine stall prevention control. The table figure which showed throttle opening increase amount (DELTA) P for every model. The table figure which showed the throttle opening increase amount (DELTA) P for every use fuel. The table figure which showed the throttle opening increase amount (DELTA) P by use fuel and an air fuel ratio.

Explanation of symbols

1 Engine Driven Heat Pump 8 Engine 9 Clutch 10 Compressor 65 Fuel Metering Valve 66 Throttle Valve 75 Throttle Opening Increase Setting Unit

Claims (3)

A fuel metering valve for adjusting the fuel gas flow rate;
A throttle valve that adjusts the flow rate of the mixture of air and fuel gas supplied to the engine combustion chamber;
In an engine-driven heat pump having a clutch mechanism for connecting and disconnecting the engine and the compressor,
An engine-driven heat pump, wherein a predetermined opening increase signal is output to the throttle in synchronization with a connection signal between the engine and the compressor output by the clutch mechanism. The engine-driven heat pump according to claim 1,
The predetermined opening increase signal is determined in advance based on an actual measurement result of an increase in the throttle opening required to restore a decrease in the engine speed due to the connection between the compressor and the engine. Engine-driven heat pump. The engine-driven heat pump according to claim 1,
The engine-driven heat pump, wherein the predetermined opening increase signal is calculated on the basis of an engine speed reduction prediction due to connection of the compressor and a speed fluctuation characteristic due to combustion characteristics of the engine.