JPH01193565A - Heat pump type cooling/heating device - Google Patents

Abstract

PURPOSE:To perform the operation control during the transitional phase where the output of a stirling engine becomes high enough by closing the unloading valve when the speed of the stirling engine becomes higher by a preset value than the speed at which the engine can run stably, and opening the unloading valve when the speed becomes lower by a preset value than this speed. CONSTITUTION:When the speed of a stirling engine 1 becomes the speed NU which is higher by a preset value of alpha than the speed NO at which the operation can be stable, a control device 20 closes the unloading valve 13. Since the output of the stirling engine 1 is not sufficient at this point, its speed tends to drop. As the speed drops to the level of ND which is lower than NO by a preset value of beta, the control device 20 again opens the unloading valve 13 to increase the engine speed. When it reaches NU, the unloading valve 13 is closed. By repeating such operation control, the output of the stirling engine 1 rises gradually, and, as it reaches a sufficient level in some time, the speed NO becomes constant. By setting alpha>=beta, a stable startup operation control becomes possible with experiencing a breakdown before stabilizing.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a heat pump type air-conditioning device using a Stirling engine as a power source, and in particular, to a heat pump type air-conditioning device using a Stirling engine as a power source. The present invention relates to a device that performs operation control during startup.

(Prior Art) Since the Stirling engine is an external combustion engine, there is a delay in output rise at startup due to the heat capacity of the heating section. Therefore, in an air-conditioning system that uses a Stirling engine as a power source to drive a heat pump compressor, after the Stirling engine starts heating, the engine starter is started when the output has increased sufficiently, and then the engine speed reaches an acceptable level. Control is performed by turning on the clutch provided between the engine's output shaft and the compressor before the value is exceeded.

However, with this operation control method, if the engine output at the time the clutch is turned on is not greater than the required output when the compressor is fully loaded, the engine will break down. To avoid this, it is necessary to use a large, high-output engine that is not needed during steady operation.

As a method to solve such problems, "Research and development and research results of general-purpose Stirling engines in 1985" (
There is an operation control method described in the New Energy Development Organization).

In this method, three unload valves with different flow rates (flow rate ratio 4:2:1) are installed in parallel with the heat pump compressor, that is, between the suction side and the discharge side, and the engine output at startup is As it rises, the unloading ratio of these unloading valves is sequentially 7/7, 6/7°5/7.4/7.3/7.
The opening/closing is controlled to change in 8 steps: 2/7.1/7.0/7.

However, this system uses three unload valves, which not only complicates the refrigeration cycle and lowers reliability, but also increases cost and increases the size and weight of the device.

(Problems to be Solved by the Invention) In this way, in the conventional heat pump air-conditioning system using a Stirling engine as a power source, the refrigeration cycle becomes complicated because multiple unload valves are used to control the operation at startup. There were problems in that the reliability decreased, the cost increased, and the device became larger and heavier.

The present invention adds a single unload valve to the compressor in a heat pump powered by a Stirling engine,
It is an object of the present invention to provide a heat pump type air-conditioning device that can control the operation until the output of the Stirling engine is sufficiently increased by controlling the opening and closing of the unload valve.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a method for reducing compression in a heat pump when the rotational speed of a Stirling engine reaches a rotational speed NO higher by a predetermined value α than a rotational speed NO at which stable operation of the engine is possible. The present invention is characterized by comprising a control means for closing an unloading valve added in parallel to the machine and opening the unloading valve when the rotational speed ND has decreased to a predetermined value β lower than NO.

Further, the relationship between α and β is selected to be α≧β.

(Function) After the Stirling engine has been started, for example, if a clutch installed between the output shaft of the engine and the compressor is turned on while the unload valve is open, the engine speed will be equal to the load on the compressor. It decreases once and then increases again. When the unload valve is closed when this rotational speed reaches NO-NO+α, the engine rotational speed decreases again. Therefore, when the unload valve is opened when the engine speed has decreased to ND-NO-β, the engine speed will rise again. As these operations are repeated, the engine output increases to the level required when the compressor is fully loaded, and stable operation becomes possible.

(Example) Hereinafter, the present invention will be described in detail with reference to the drawings. In FIG. 1, a Stirling engine 1 includes a burner 2 and a heater 3 that heats working gas using the combustion heat of the burner 2.
, a cooler 4 that cools the working gas, and a rotational motion converter 5 that converts energy accompanying movement of the working gas into rotational motion.
It is composed of. A gear 7 is connected to the output shaft 6 of the Stirling engine 1 provided in the rotational motion converter 5, and a starter 8 is connected to the gear 7 only when a starting command is given. This starter 8 is for providing the rotational force necessary for starting the rotational motion converting section 5.

The output shaft 6 of the Stirling engine 1 is further connected to a rotation speed detector 9 and an input side of a clutch 10. The output side of the clutch 10 is connected to a rotating shaft of a compressor 12 in a heat pump 11 .

The heat pump 11 is a well-known refrigeration cycle composed of a compressor 12, a four-way valve 14, an outdoor heat exchanger 15, an expansion valve 16, a connection valve 17, an indoor heat exchanger 18, and a connection valve 19. It differs from a general heat pump in that it uses a Stirling engine 1 as a source.

- unload valves 13 are provided in parallel with the compressor 12, that is, between the suction side and the discharge side of the compressor 12. This unload valve 13 is controlled by a control device 20 based on the detection result of the rotation speed detector 9.

Next, the operation control at the time of startup of the air conditioning system configured as described above will be explained with reference to the time chart shown in FIG. 2. Note that whether to perform the cooling operation or the heating operation is selected by the four-way valve 14. When the four-way valve 14 is in the connection state shown in the figure, the cooling operation is performed, and when the connection state is shifted by 90 degrees, the heating operation is performed. Each will be done.

First, when a start command is given to the control device 20 at time t-tl, the control device 20 ignites the burner 2 and controls the cooling water supply valve (not shown) to the cooler 4 to open. When the burner 2 starts a combustion operation, the temperature of the heater 3 increases and the working gas is heated.

Then, when the wall temperature of the heater 3 rises to a temperature at which the engine 1 can generate power for self-sustaining operation, the control device 20 operates the starter 8 and moves the starter 8 to the gear 7.
It is connected to the output shaft 6 of the Stirling engine 1 via (t-t2). As a result, the Stirling engine 1 is started. Note that at this point, the clutch 10 is off,
The unload valve 13 is in an open state.

Next, the control device 20 turns on the clutch 10 when the rotation speed detected by the rotation speed detector 9 reaches a predetermined value below the allowable upper limit, that is, when the output of the Stirling engine 1 reaches a certain value. state (t-t3). When the clutch 10 is turned on, the compressor 12 is connected to the output shaft 6 of the Stirling engine 1 as a load, so the rotation speed decreases, but since the unload valve 13 is open, the load is small and the Stirling engine 1 There's no stopping it. Therefore, the rotational speed of the Stirling engine 1 starts to increase again as the output increases.

Then, when the rotational speed of the Stirling engine 1 exceeds the rotational speed NO that allows stable operation and reaches the rotational speed NU higher than NO by a predetermined value α, the control device 20 closes the unload valve 13 (t-t4).

When the unload valve 13 is closed, the compressor 12 becomes fully loaded, but since the output of the Stirling engine 1 is not sufficient at this point, its rotational speed begins to decrease.

Therefore, when the rotation speed of the Stirling engine 1 decreases to the rotation speed ND which is lower than NO by a predetermined value β, the control device 2
0 opens the unload valve 13 again ((t-t5). This reduces the load on the Stirling engine 1, so its rotation speed starts to rise again. Then, when the rotation speed reaches NU, the full load valve 13 is opened again (t-t5). 13 is closed.

By repeating such operation control, the output of the Stirling engine 1 gradually increases and eventually reaches a sufficient value, and its rotational speed becomes constant at NO (t-t6).

Thereafter, the unload valve 13 remains closed, and the compressor 12
Cooling or heating operation is performed by operating the Stirling engine 1 as a power source.

Note that if β>α in the above embodiment, the rotational speed ND of the Stirling engine 1 when switching the unload valve 13 from closed to open may have to be set below the breakdown rotational speed.

In such a case, the Stirling engine 1 will break down during the operation control at startup.

By setting α≧β, ND can be set to a value higher than the breakdown rotation speed of the Stirling engine 1, so stable startup operation control is possible without causing breakdown midway.

[Effects of the Invention] According to the present invention, by controlling the opening and closing of a single unload valve provided in parallel with the compressor, it is possible to stably start a heat pump type air-conditioning system powered by a Stirling engine. . Therefore, by using only a single unloading valve, the configuration of the refrigeration cycle becomes simpler and reliability is improved, and costs can be reduced, as compared to conventional systems that use multiple unloading valves. It has the advantage of being smaller and lighter.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a heat pump air-conditioning system according to an embodiment of the present invention, and FIG. 2 is a time chart for explaining the operation of the embodiment at startup. 1... Stirling engine, 6... Output shaft, 8...
... Starter, 9 ... Rotation speed detector, 10 ... Clutch, 11 ... Heat pump, 12 ... Compressor, 1
3... Unload valve, 20... Control device. Applicant's agent Patent attorney Takehiko Suzue

Claims (2)

[Claims] (1) In a device that performs heating and cooling operation by driving a compressor in a heat pump using a Stirling engine as a power source, an unload valve provided in parallel with the compressor and a detection unit that detects the rotational speed of the Stirling engine. means, when the rotational speed of the Stirling engine detected by this means reaches a rotational speed NU higher by a predetermined value α than the rotational speed NO at which stable operation of the engine is possible, the unloading valve is closed; and a control means for opening the unloading valve when the rotational speed has decreased to a low rotational speed ND. (2) The heat pump type air-conditioning device according to claim 1, characterized in that α≧β.