JPH08303821A - Pressure regulating mechanism for engine heat pump - Google Patents

Abstract

PURPOSE: To increase cooling efficiency without increasing the capacities of a compressor and an outdoor fan, prevent the chattering and the like of a valve, which are caused in the solenoid valve control upon pressure equibrium, and control the retaining of a low pressure or a difference between high pressure and low pressure upon cooling nicely when an outdoor air temperature is low, in an outdoor machine for an engine heat pump. CONSTITUTION: The liquid level in a liquid receiver 9 is controlled so as to be a position coinciding with the half of the upper and lower widths of a heat dissipating tube of an outdoor heat exchanger 6 while the refrigerant tube is constituted so as to be introduced into the lower part of the liquid receiver 9. Upon finishing pressure equilibrium treatment, valves are closed in the sequence of a four-way valve, a solenoid valve for hot gas bypass passage, and the other solenoid valves while the control of retension of low pressure of a refrigerant or a pressure difference between a high and a low pressures are effected in relation to the control of number of revolution of an outdoor fan, the control of the opening degree of an electronic expansion valve and the control of opening and closing of a solenoid valve for a modulated bypass passage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerant system pressure adjusting mechanism for an engine heat pump.

[0002]

2. Description of the Related Art In an outdoor unit of an engine heat pump, the positional relationship between the liquid receiver and the outdoor heat exchanger has conventionally been such that the entire liquid receiver is placed below the outdoor heat exchanger (for example, JP-A-5-306851). ),
Also, when the liquid receiver cannot be arranged below the outdoor heat exchanger, the refrigerant hose end from the outdoor heat exchanger is introduced from the upper side of the liquid receiver. The liquid refrigerant smoothly flows into the outdoor heat exchanger.

Similarly, in an outdoor unit, a discharge circuit for discharging high-pressure gas refrigerant from the compressor and a low-pressure gas refrigerant after circulating through the refrigerant system are sucked into the compressor between the compressor and a four-way valve for switching between heating and cooling. Although a suction circuit is provided, it has been publicly known that a bypass circuit starting from a high-pressure discharge circuit is provided for various pressure adjustment control. First, when the operation is stopped, a pressure equalizing bypass circuit (hot gas bypass) is provided between the discharge circuit and the suction circuit so as to quickly equalize the pressure of the discharge circuit and the suction circuit. Also, the suction circuit of the compressor is designed to allow a low-pressure refrigerant of a certain level or more to flow in so that the refrigerant does not have a low pressure such that the refrigerant freezes in the heat exchanger of the indoor unit. If the capacity of the indoor unit is low and a low pressure above a certain level cannot be obtained by controlling the compressor capacity alone, send high-pressure gas from the discharge circuit to the suction circuit in order to make the suction side above a certain pressure. A bypass circuit for pressure regulation is used.

As another bypass circuit, a heat radiation circuit is provided in the outdoor heat exchanger from the discharge circuit in order to reduce the pressure of the discharged gas refrigerant that becomes too high due to the reduction of the indoor unit capacity during heating. There is. Further, when the degree of condensation of the refrigerant that has passed through the outdoor heat exchanger is insufficient, such as when the outdoor air temperature is low, the high pressure liquid refrigerant is sent from the discharge circuit to allow the high pressure liquid refrigerant to flow into the outdoor heat exchanger of the outdoor unit. A pressure adjusting bypass circuit (modulated bypass) is provided from the discharge circuit to the liquid receiver.

Among these, as for the pressure equalizing bypass circuit, the solenoid valves of the bypass circuit are opened, and the other solenoid valves in the refrigerant system in the outdoor unit are simultaneously opened to prevent back pressure. It is configured to do.

Further, in the outdoor unit, a configuration is known in which the outdoor fan for cooling the outdoor heat exchanger is finely driven and controlled by an inverter type.

[0007]

Originally, the refrigerant condensation in the outdoor heat exchanger is due to the heat radiation of the outdoor fan.
When the condensed liquid refrigerant is retained at the outlet side of the refrigerant pipe from the outdoor heat exchanger, the refrigerant in the heat exchanger further improves the condensation effect due to the cooling effect generated by the accumulated liquid refrigerant. However, as in the conventional case, in a configuration in which the liquid refrigerant smoothly flows into the liquid receiver, this effect cannot be expected, and if a location for retaining the liquid refrigerant is provided in this manner, the compressor will be compressed. The capacity must be increased, and there is a high possibility that the compression capacity will exceed the capacity limit and the cost will increase.

Among the bypass circuits in the outdoor unit, first, in the pressure equalizing bypass circuit arranged from the discharge circuit to the suction circuit, the solenoid valve of the pressure equalizing bypass circuit and all other components in the refrigerant system are stopped together with the operation stop. It is well known that the solenoid valves are simultaneously opened, but when the pressure is equalized and the solenoid valves of the pressure equalizing bypass circuit are closed, the other solenoid valves are also closed simultaneously. At this time, the back pressure is applied to the other solenoid valves to cause hunting, vibration noise is generated, and the durability of the solenoid valves is reduced. Further, opening and closing of the four-way valve causes large fluctuations in pressure, but since this was done after the solenoid valve was closed, hunting of the solenoid valve also occurred.

Further, when the cooling operation is carried out when the outside air temperature is low, there is a problem that the low pressure refrigerant on the suction side of the compressor is too low and the indoor unit freezes. Even if the high-pressure refrigerant in the discharge circuit is sent to the suction circuit in the bypass circuit,
If the liquid refrigerant flowing into the outdoor heat exchanger of the outdoor unit is not maintained at a high pressure above a certain level, the high-low pressure difference of the refrigerant required for cooling cannot be obtained. When the difference between the high pressure and the low pressure is small, in the vane type compressor, the vanes chatter, which causes a problem of poor compression. Therefore,
In order to keep the high-pressure side at a certain level or higher, the rotation speed of the outdoor fan is reduced to prevent condensation in the outdoor heat exchanger, and a high-pressure gas refrigerant from the discharge circuit to the liquid receiver in the pressure-adjusting bypass circuit. By increasing the pressure in the sending and liquid kit receivers, the refrigerant pressure at the outlet side of the outdoor heat exchanger is increased to improve the condensation pressure, and at the outlet side of the outdoor heat exchanger, the liquid refrigerant is usually fully opened. The bypass circuit was closed to allow passage through the electronic expansion valve and the bypass circuit, but it was sent to the electronic expansion valve with a reduced opening, but these controls are independent of each other and are independent. However, when the outdoor fan control is switched to the electronic expansion valve control, for example, the refrigerant pressure fluctuates abruptly and the control becomes difficult to perform. Therefore, it is desirable to build an automatic control system that correlates these controls.

[0010]

The present invention uses the following means in order to solve the above problems. That is, in the outdoor unit of the engine heat pump, the liquid level in the liquid receiver is set at a position where the liquid level in the liquid receiver overlaps with the middle part of the vertical width of the heat dissipation pipe of the heat exchanger, and the refrigerant pipe extending from one end of the heat exchanger is used as the liquid receiver. Introduced at the bottom of.

Further, in the outdoor unit of the engine heat pump, when the solenoid valves are opened in the pressure equalizing bypass circuit provided in the suction circuit from the compressor discharge circuit, all other solenoid valves in the refrigerant system are opened and closed. The four-way valve, the solenoid valve of the pressure equalizing bypass circuit, and all the other solenoid valves were provided with a time difference in this order.

Further, in the outdoor unit of the engine heat pump, a pressure regulating bypass circuit is provided between the discharge circuit of the compressor and the liquid receiver to control the rotation speed of the heat exchanger cooling fan and the opening degree of the electronic expansion valve. By controlling the opening and closing of the solenoid valve in the pressure regulating bypass circuit,
The low pressure refrigerant pressure of the compressor suction circuit required for cooling and the high and low pressure difference of the refrigerant between the compressor discharge circuit and the suction circuit are obtained.

[0013]

[Operation] When there is a margin in the compressor pumping capacity,
By arranging the liquid receiver so that the liquid level inside is within the range of the vertical width of the outdoor heat exchanger, refrigerant retention occurs at the outlet side of the outdoor heat exchanger, and liquid that accumulates in the liquid receiver The degree of supercooling of the refrigerant can be increased, and as a result, the refrigerating effect is increased and the cooling capacity is improved.

Further, with the opening of the solenoid valve in the pressure equalizing bypass, all the solenoid valves in the other bypasses are also opened, and then the valve is first closed by the four-way valve in which the pressure fluctuation is severe.
At this time, all solenoid valves are open, so no back pressure is applied. Next, the pressure-equalizing solenoid valve, which has the most pressure fluctuations next to the four-way valve, is closed, but at this time, all the other solenoid valves are open and no back pressure is applied. In this way, since the other solenoid valves are closed after the pressure is equalized, all the solenoid valves and the four-way valve can be closed in a state where no back pressure is applied to any solenoid valve.

Further, in order to keep the low pressure on the suction side at a certain level or more and to keep the high-low pressure difference of the refrigerant at a certain level or more during cooling in a state where the outside air temperature is low, the inverter control of the outdoor fan, the electronic expansion valve, and the By associating it with the on-off valve control of the bypass circuit for pressure regulation, and making it one automatic control system,
Fine-tuned operation is possible, and it is possible to save the trouble of performing pressure adjustment control by performing different controls separately.

[0016]

Embodiments of the present invention will now be described with reference to the accompanying drawings. FIG. 1 is a front view showing an arrangement positional relationship between an outdoor heat exchanger and a liquid receiver according to the present invention, FIG. 2 is a schematic front view showing a positional relationship between a liquid level in the liquid receiver and the outdoor heat exchanger, and FIG. 2 A graph showing the refrigerant capacity ratio CP, the degree of supercooling ΔT, and the refrigerant high pressure PH for each liquid level height shown in FIG. 4, and FIG. 4 shows the arrangement structure of the conventional liquid receiver, which is arranged below the outdoor heat exchanger. Fig. 5 is a diagram showing a refrigerant pipe introduced from the outdoor heat exchanger from above, Fig. 6 is a refrigerant system diagram of an engine heat pump at the time of pressure equalizing treatment, and Fig. 7 is a front sectional view of a solenoid valve SV. Figure, Figure 8
Is O of each solenoid valve at the time of pressure equalization processing due to system stop
9 is a time chart showing N / OFF timing, FIG. 9 is a time chart showing ON / OFF timing of each conventional solenoid valve, FIG. 10 is a refrigerant system diagram of an engine seat pump during cooling, and FIG. 11 is during cooling. Electronic expansion valve for increasing refrigerant high pressure and refrigerant system diagram of engine heat pump during modulated bypass control,
FIG. 12 is a flow chart of the refrigerant low pressure holding control and the refrigerant high pressure holding control during cooling, FIG. 13 is a diagram showing a rotation speed step of the outdoor fan 5, and FIG. 14 is a diagram showing an opening step of the electronic expansion valve 8. 16 is a graph showing the difference between high pressure and low pressure on the discharge side and the suction side of the compressor, FIG. 16 is a refrigerant system diagram of the engine heat pump during heating, and FIG. 17 is a refrigerant system diagram of the engine heat pump during defrosting in the outdoor heat exchanger during heating 18 is a refrigerant system diagram of the engine heat pump when the heat radiation circuit is opened during heating, FIG.
9 is a side view of the pressure regulating valve PV, FIG. 20 is a plan view of the same, and FIG.
1 is a graph showing the displacement of the refrigerant high pressure with respect to the outside air temperature when the room temperature is kept at 30 ° C., and FIG. 22 is a graph showing the displacement of the blowout temperature in the indoor unit with respect to the refrigerant high pressure.

The refrigerant system of the engine heat pump according to the embodiment of the present invention will be described with reference to FIGS. 6, 10 and 16. The engine heat pump of the present embodiment is one in which a plurality of indoor units B, B ... Is connected to one outdoor unit A. In the outdoor unit A, a compressor 1 and a four-way valve 3 driven by an engine are provided. In between, the suction circuit C2 via the accumulator 10 and the discharge circuit C1 via the oil separator 2 are connected. The compressor 1 is a multi-compressor in which a plurality of compressors are combined so that the width of the pumping capacity can be widened. In addition to the discharge circuit C1 and the suction circuit C2, the four-way valve 3 circulates in the outdoor unit A to generate the indoor units B and B.
The circulation circuit C3 connected to the liquid refrigerant circuit C5 in ... And the input / output circuit C4 connected to the gas refrigerant circuit C6 in the indoor units B and B are connected without circulating in the outdoor unit A. Has been done.

Looking at the configuration of the circulation circuit C3 in the outdoor unit A from FIG. 10 along the flow of the refrigerant during cooling, first, the waste heat recovery unit 4 is provided, and the waste heat recovery is performed. After passing through the heat exchanger 4, the outdoor heat exchangers 6 and 6 which radiate heat by the outdoor fans 5 and 5 are arranged in parallel. After passing through both the outdoor heat exchangers 6 and 6, they join again to form the site. After passing through the glass 7 (for visually recognizing whether the refrigerant condensed in the outdoor heat exchanger 6 due to the overfilling of the refrigerant does not have a foaming phenomenon or a liquid compression), this time it is branched into three. Two of these are provided with electronic expansion valves 8 and 8, and the other is an electrically operated valve bypass BP4 with an electromagnetic valve SV4. These three circuits join again, go out of the outdoor unit A via the liquid receiver 9, and are connected to the liquid refrigerant circuit C5.

On the indoor unit side B, the liquid refrigerant circuit C
5. The gas refrigerant circuit C6 is branched for each indoor unit B, introduced into each indoor unit B, and connected to the indoor heat exchanger 13, and in each indoor unit B, the liquid refrigerant circuit C5 An indoor electronic expansion valve 12 is provided in the room.

In the schematic configuration of such a refrigerant system, at the time of cooling, as shown in FIG. 10, in the four-way valve 3, the discharge circuit C1 and the circulation circuit C3 are connected, and the suction circuit C2 and the inlet / outlet circuit C4 are connected. The refrigerant circulates along the thick line with an arrow in the figure. More specifically, the high-pressure gaseous refrigerant discharged from the compressor 1 flows into the circulation circuit C3 through the discharge circuit C1, the four-way valve 3 and the like, first passes through the waste heat recovery unit 4, and then the outdoor heat exchangers 6 and 6 ( In this case, heat is sufficiently dissipated in the condenser) to be condensed into a liquid refrigerant, and after passing through the sight glass 7, the electronic expansion valves 8 and 8 are fully opened and the solenoid valve SV is opened.
4 is opened, the refrigerant passes through the electronic expansion valve 8.8 and the motor-operated valve bypass BP2, and then the liquid receiver 9
Liquid refrigerant circuit C after entering and storing and exiting outdoor unit A
5, the indoor electronic expansion valve 12 reduces the pressure in each indoor unit B, and the indoor heat exchanger 1 is easily vaporized.
3 (in this case, the evaporator) takes heat of vaporization from the room to evaporate. The interior of the room is cooled as the refrigerant vaporizes. The low-pressure gas refrigerant thus passing through the indoor heat exchanger 13 is sucked into the compressor 1 from the suction circuit C2 via the gas refrigerant circuit C6, the inlet / outlet circuit C4 in the outdoor unit A, and the four-way valve 3.

Next, the flow of the refrigerant during heating will be described with reference to FIG. At the time of heating, in the four-way valve 3, the discharge circuit C1 and the inlet / outlet circuit C4 are connected, and the suction circuit C2 and the circulation circuit C3 are connected, and the high-pressure gas refrigerant discharged from the compressor 1 is discharged into the discharge circuit C1. After passing through the four-way valve 3 and the inlet / outlet circuit C4, first, the gas refrigerant circuit C
6 is introduced into each indoor unit B, and each indoor heat exchanger 1
3 (in this case, the condenser) is radiated, condensed, and liquefied. When the refrigerant is condensed, heat is radiated into the room to heat the room. The liquid refrigerant liquefied in the indoor heat exchanger 13 is transferred from the liquid refrigerant circuit C5 to the outdoor unit A
It is introduced into the circulation circuit C3 in the inside, first through the liquid receiver 9, this time, the electric valve bypass BP4 in which the solenoid valve SV4 is closed does not pass, and the pressure is reduced through the electronic expansion valve 8. The outdoor heat exchanger 6
At 6 (in this case, the evaporator), the heat of vaporization from the outside is vaporized, and further at the waste heat recovery unit 4, the heat is completely vaporized to become a low-pressure gas refrigerant, and the four-way valve 3 is turned on. Through the suction circuit C2, the air is sucked into the compressor 1.

In the above refrigerant system, the positional relationship between the liquid receiver 9 and the outdoor heat exchanger 6 in the outdoor unit A will be described with reference to FIGS. 1 to 3. As shown in FIG. 10 and the like, the liquid receiver 9 is arranged between the evaporator and the condenser (the outdoor heat exchanger 6 and the indoor heat exchanger 13) for adjusting the supply and demand of the refrigerant in the evaporator. It is a thing. That is, the evaporator (in the case of cooling, the indoor heat exchanger 1
3. At the time of heating, an electronic expansion valve 12 or 8 is provided on the upstream side of the outdoor heat exchanger 6) to keep the temperature of the refrigerant returning to the compressor 1 constant according to the change in the load of the evaporator. Therefore, although the flow rate of the refrigerant is adjusted, the liquid kit receiver 9 stores a certain amount of liquid refrigerant and eliminates the deterioration of the capacity due to the discrepancy between the changes in the condensation amount and the evaporation amount at this time. The refrigerant is supplied to the electronic expansion valve 12 or 8.

This liquid receiver 9 has a conventional positional relationship with the outdoor heat exchanger 6 as shown in FIG. 4 and FIG.
As described above, the liquid refrigerant is allowed to smoothly flow in from the outdoor heat exchanger 6 that serves as a condenser during cooling, thereby avoiding an increase in the pumping capacity of the compressor 1. In the present embodiment, since the compressor 1 has a sufficient pumping capacity, the outdoor heat exchanger 6 is set by allowing the liquid refrigerant to stay at the inlet portion of the liquid receiver 9.
In the heat radiation circuit 6a of the outdoor heat exchanger 6
To increase the cooling effect of the refrigerant in the heat dissipation circuit 6a, that is, to accelerate the condensation. In order to cause this retention, as shown in FIG. The heat exchanger 6 is positioned between the upper and lower widths, that is, the liquid surface and the chamber extending in the upper and lower width H are in the heat exchanger 6.
And the refrigerant pipe from the outdoor heat exchanger 6 is introduced to the lower side of the liquid receiver 9.

Liquid receiver 9 arranged in this way
The cooling effect caused by the above will be described with reference to FIGS. 2 and 3. In FIG. 2, the liquid surface height in the liquid receiver 9 is divided into five stages of to, and the compressor 1 discharge pressure PH at each stage, the degree of supercooling ΔT at the outlet of the heat radiation circuit 5a, and the cooling capacity ratio CP (%). And are shown in FIG. The cooling capacity ratio CP represents the cooling capacity at 100% of the cooling capacity at the liquid level and the cooling capacity of the cooling capacity.

From FIG. 3, it can be seen that the supercooling degree ΔT increases as the liquid level rises to, and the cooling capacity ratio CP also increases accordingly. For example, at the liquid level, the degree of supercooling ΔT is larger than that at the liquid level, that is, the refrigerant in the heat dissipation circuit 5a is cooled and condensed as compared with the liquid level. The cooling capacity ratio CP is 110% or more. At the liquid level, the supercooling degree ΔT further increases,
The cooling capacity ratio is about 114%. It can be seen that the discharge pressure of the compressor 1, that is, the refrigerant high pressure PH is also increased as the liquid level rises. However, the maximum discharge pressure PH _max ′ in this case can also be sufficiently expressed within the discharge capacity range of the compressor 1 which is the multi-compressor of this embodiment (below the maximum allowable refrigerant high pressure PH _max ).

Refrigerant-based outdoor unit A constructed as described above
In order to adjust various pressures, the low pressure side (suction circuit C side) of the compressor 1 is higher than the high pressure side (discharge circuit C1 side).
2 side), a plurality of bypass circuits are disposed, and each bypass circuit is provided with a solenoid valve that can be opened and closed. These bypass circuits will be described.

First, as shown in FIG. 6, a hot solenoid valve SV1 is provided between the lower side of the oil separator 2 in the discharge circuit C1 and the upper side of the accumulator 10 of the suction circuit C2, that is, from the discharge circuit C1 to the suction circuit C2. A gas bypass (pressure equalizing bypass circuit) BP1 is provided. This bypass sends the high-pressure gas refrigerant in the discharge circuit C1 to the suction circuit C2 to lower the pressure of the high-pressure refrigerant in the discharge circuit C1 and increase the pressure of the low-pressure refrigerant in the suction circuit C2. The low pressure of the low pressure refrigerant in the suction circuit C2 is too low or the high pressure refrigerant in the discharge circuit C1 is too high due to the reason that the capacity of the indoor unit is small in addition to the pressure equalization processing of the refrigerant system at the time of operation stop. The valve is also opened when pressure is adjusted. FIG. 6 shows a solenoid valve SV
1 shows the flow of refrigerant from the discharge circuit C1 to the suction circuit C2 in the hot gas bypass BP1 when the valve 1 is opened. The hot gas bypass BP1 is provided with a capillary tube CT, which is a throttling mechanism provided to prevent the pressure on the inlet side of the bypass from becoming lower than the pressure on the outlet side. It is also installed in the bypass BP5.

Here, the switching timing of the solenoid valve and the four-way valve when the solenoid valve SV1 is opened, that is, during the pressure equalizing process will be described with reference to FIG. First, when the system is stopped (engine, compressor operation stopped), in order to prevent the refrigerant from being sent to each heat exchanger during the next operation,
In order to equalize the high pressure side and the low pressure side of the compressor 1, the solenoid valve SV1 is automatically opened (ON) so that the refrigerant flows through the hot gas bypass BP1 from the high pressure side to the low pressure side. If the solenoid valves SV2 to SV6 in the other bypasses BP2 to BP6 are closed (OFF), reverse pressure is applied to these solenoid valves, causing hunting, which leads to damage of the valves. Therefore, the solenoid valve SV1 is opened at the same time. The other solenoid valves SV2 to SV6 are also open (ON). The solenoid valve SV1 and other solenoid valves SV2 to
There is a case where any one of the SV6 is turned on is shown by an arrow before the operation stop time. In addition, the solenoid valve S
V (electromagnetic valves SV1 to SV6) has a structure as shown in FIG.

When the pressure is almost equalized, the four-way valve 3 is first closed. Since the four-way valve 3 has a large amount of refrigerant passing therethrough, and therefore the switching thereof causes a large change in the refrigerant flow,
Even though the pressure equalization has advanced, the solenoid valve S
When V1 to SV6 are closed, back pressure is applied. Therefore, first, the four-way valve 3 is closed. Next, the solenoid valve SV1 is closed (OFF), but conventionally, as shown in FIG. 9, since the other solenoid valves SV2 to SV6 are simultaneously closed (OFF), the other solenoid valves SV2 to SV6 are In the embodiment of FIG. 8, the solenoid valve SV1 is closed (OFF).
After that, the other solenoid valves SV2 to SV6 are closed (OF
F) Yes. That is, at the time when the solenoid valve SV1 is closed and the hot gas bypass BP1 is closed, even if the refrigerant backflows to the other bypasses, the solenoid valves SV2 to SV6 are opened (ON to prevent hunting due to backpressure). ), The pressures of the other bypasses are eventually equalized, and when the reverse pressure is not applied even if the valve is closed, the other solenoid valve SV2
The SV6 is closed (OFF).

The hot gas bypass BP1 is as described above. Next, the injection bypass BP2 used in the pressure equalizing process will be described with reference to FIG. The injection bypass BP2 includes a liquid receiver 9 and an electronic expansion valve 8.8 in the circulation circuit C3.
In the circuit that allows the liquid refrigerant to flow into the outlet portion of the hot gas bypass BP1 from between the (motor valve bypass BP4), the expansion valve 11 is interposed in addition to the solenoid valve SV2 to reduce the pressure of the liquid refrigerant. When the system operation is stopped, the hot gas bypass BP1 is opened to equalize the pressures on the discharge side and the suction side of the compressor 1, but it is necessary to recover the liquid refrigerant in the circulation circuit C3. The outlet of the hot gas bypass BP1 has an accumulator 1 in the suction circuit C2.
Since it is on the good side of 0, the liquid refrigerant that has flowed into the hot gas bypass BP1 through the injection bypass BP2 is recovered by the accumulator 10. By the action of the expansion valve 11, the liquid refrigerant is vaporized to some extent, and is further introduced into the high-pressure gas refrigerant in the hot gas bypass BP1 to further promote the vaporization and collect the liquid refrigerant in the accumulator 10. The amount is being reduced.

Next, the bypass circuit used during cooling will be described. First, as described above, the motor-operated valve bypass BP4 is a bypass that allows the liquid refrigerant to pass smoothly during cooling, and opens (ON) the solenoid valve SV4 during cooling (see FIG. 1).
0), the valve is closed (OFF) during heating, and the electronic expansion valve 8
The liquid refrigerant that has flowed in from the indoor unit B is passed through 8 to reduce the pressure and send it to the outdoor heat exchanger 5 (FIG. 1).
6). Even when cooling, when high pressure on the discharge side of the compressor 1 cannot be obtained, the solenoid valve SV7 is closed to obtain the high pressure in the discharge circuit C1, and the electric valve bypass BP is closed.
The flow of the refrigerant into No. 4 is suppressed (Fig. 11, detailed later).

Modulated bypass (pressure-adjusting bypass circuit) BP5 provided with the solenoid valve SV5 shown in FIG.
Is a circuit for injecting a high-pressure gas refrigerant into the liquid receiver 9 from the discharge circuit C1 (on the lower side of the oil separator 2), and is provided to avoid a sudden high pressure rise in the discharge circuit C1. The valve opening control is performed in conjunction with the rise control of the compressor 1 discharge pressure (refrigerant high pressure PH) by adjusting the opening degree of No. 8, but this will be described later in the automatic pressure adjustment control during cooling shown in FIGS. 11 to 15. I will explain in detail.

Next, the bypass used during heating will be described. The defrost bypass BP3 provided with the solenoid valve SV3 shown in FIG. 17 includes an outdoor heat exchanger 6 and an electronic expansion valve 8.8 (motor-operated valve bypass) in the circulation circuit C3 from the discharge circuit C1 (oil separator 2 lower side). BP
4) is a circuit that allows high-pressure gas refrigerant to pass between
When the outside air temperature is low and frost is formed on the fins of the outdoor heat exchangers 6 and 6, the high pressure gas refrigerant from the defrost bypass BP3 is added to the depressurized liquid refrigerant that is flowed in from the electronic expansion valve 8 and 8. The outdoor heat exchanger 6
To melt the frost in.

The heat radiation circuit BP6 provided with the solenoid valve SV6 shown in FIG. 18 passes through a part of the outdoor heat exchanger 6 from the discharge circuit C1 (on the lower side of the oil separator 2) and the circulation circuit C.
3 is communicated with a portion near the connection to the liquid refrigerant circuit C5, and a solenoid valve SV6 and a pressure regulating valve PV are provided on the lower side of the outdoor heat exchanger 6. Refrigerant high pressure PH
When the refrigerant discharge pressure in the discharge circuit C1 becomes excessively high (when the heating operation is performed in a state where the capacity of the indoor unit is very small,
This situation is likely to occur. ), When the refrigerant high pressure PH cannot be reduced only by suppressing the capacity of the compressor 1, the solenoid valve SV6 is opened (ON) to allow the high pressure gas refrigerant in the discharge circuit C1 to flow into the heat dissipation circuit BP6. The heat is condensed by passing through the outdoor heat exchanger 6 on the way. Therefore, the bypassed refrigerant is liquefied at the outlet of the heat dissipation circuit BP6, while the liquid refrigerant from the indoor unit B is flowing into the circulation circuit C3 at the portion near the connection to the liquid refrigerant circuit C5. Then, the liquid refrigerant from the heat dissipation circuit BP6 is added to this liquid refrigerant and allowed to flow into the circulation circuit C3.

Here, the heat dissipation circuit BP6 will be described in detail. The high-pressure gas refrigerant can be bypassed from the discharge circuit C1 by using the hot gas bypass BP1, but this bypasses a large amount of the gas refrigerant from the high-pressure side to the low-pressure side at once, and thus a violent bypass noise is generated. In other words, there is an adverse effect that the high / low pressure difference between the discharge side and the suction side is sharply reduced and the vane of the compressor chatters. The hot gas bypass BP1 is effective in rapidly equalizing the discharge side and the suction side of the compressor 1 when the operation is stopped, but in order to suppress the refrigerant high pressure PH during the heating operation, the gas refrigerant bypasses at once. Therefore, in this case, the above-mentioned harmful effects do not occur by appropriately suppressing the high pressure by using the heat radiation circuit BP6 that can slowly bypass the refrigerant from the high pressure side to the high pressure side.

Further, in the heat radiation circuit BP6, only the solenoid valve SV6 is conventionally interposed and only the opening / closing control is possible. However, by providing the pressure regulating valve PV to this, the refrigerant flow rate is adjusted, The refrigerant high pressure PH can be kept constant. The pressure regulating valve PV is as shown in FIGS. 19 and 20, and by adjusting the power element 14 with the adjusting screw 17, the refrigerant entering from the inlet pipe 15 can be throttled to an appropriate flow rate and flow out from the outlet pipe 16. .

Refrigerant bypass by this heat radiation circuit BP6,
And the effect of adjusting the bypass amount by the pressure regulating valve PV,
Verification will be made from the graphs of FIGS. 21 and 22. FIG. 21 is a graph showing the refrigerant high pressure PH when operating to maintain the room temperature of 30 ° C. with the displacement of the outside air temperature when the indoor unit capacity is the minimum and the pumping capacity of the compressor 1 is the minimum. , PH1 is the refrigerant high pressure when the heat radiation circuit is closed, that is, when the compressor 1 is only set to the minimum capacity, PH2
Is the high pressure of the refrigerant when the electromagnetic valve SV6 is opened and the heat radiation circuit BP6 is opened (the compressor 1 has the minimum capacity),
PH3 is the high pressure of the refrigerant when the pressure is further adjusted by the pressure adjusting valve PV.

As can be seen from PH1 in FIG. 21, when the heating operation is performed when the capacity of the indoor unit is minimum, the high pressure PH of the refrigerant becomes extremely high, and even if the compressor 1 has a minimum pumping capacity, it cannot be dealt with. For example, in the engine heat pump of the present embodiment, the refrigerant high pressure PH1 at the maximum outside air temperature 26 ° C capable of heating operation is (a) in the figure, and exceeds the maximum allowable refrigerant high pressure PH _max in normal operation. In order to reduce it to normal operation can refrigerant pressure range, which bypasses at radiator circuit BP6, refrigerant pressure PH2 when opening the heat dissipation circuit BP6, at maximum ambient temperature, the maximum allowable refrigerant pressure PH _{ma x} The temperature has dropped to less than (below (b) in the figure), and when the outside air temperature is below the maximum outside temperature, PH2 <
Since it is PH _max, normal operation is possible. In the engine heat pump of this embodiment, the compressor 1 has the minimum capacity, and the refrigerant high pressure PH is the maximum allowable refrigerant high pressure PH _max.
An automatic control mechanism is provided so that the solenoid valve SV6 is automatically turned on when the following conditions are not met.

However, when the heat radiation circuit BP6 is opened, the amount of heat radiation becomes too large when the outside air temperature is low, and the refrigerant high pressure PH becomes too low. This leads to a decrease in the blowing temperature BT in the indoor unit. As mentioned above
Refrigerant high pressure PH1 when the compressor 1 has the minimum capacity
Is less than the maximum allowable refrigerant high pressure PH _max , the heat dissipation circuit BP6 is automatically opened, so that the outside air temperature is about 3
Even in the case of ° C, PH1 = PH _max, so the heat dissipation circuit BP
6 is opened, and the refrigerant high pressure PH2 at this time is significantly lower than the minimum allowable refrigerant high pressure PH _min ((c) in FIG. 21), and as a result, the blowout temperature BT decreases (FIG. 2).
In the middle of 2 (d), the result is that a person in the room feels a lot of cold wind. Therefore, when the outside air temperature is low, a decrease in the refrigerant high pressure is suppressed by throttling the pressure regulating valve PV so that an appropriate outlet temperature can be obtained, and the refrigerant high pressure is adjusted so as not to fall below the minimum allowable refrigerant high pressure PH _min. are doing. For example, when the outside air temperature is also 3 ° C., the minimum allowable refrigerant high pressure PH _min can be secured by setting the pressure regulating valve PV to a constant opening ((b) in FIG. 21), and the high blowout temperature BT. Is obtained ((e) in FIG. 22).

In the outdoor unit A having the bypass circuit as described above, finally, the automatic control mechanism for holding the refrigerant low pressure (PL) and the high / low pressure difference (PH to PL) will be described with reference to FIGS. More will be described. The compressor 1 of the present embodiment is capable of finely adjusting the number of rotations by inverter control, and the outdoor fan 5 is also finely controlled by inverter control as shown in FIG. 13 in n stages (2.5 Hz to K).
The rotation speed can be adjusted to (Hz) and the inverter is controlled to keep the room temperature constant. By the way, the compressor 1 is a vane type, and the refrigerant high pressure P on the discharge side is provided.
If the difference between H and the suction-side refrigerant low pressure PL (high / low pressure difference) is not sufficiently taken, the vane causes chattering and compression failure occurs. Therefore, the refrigerant high pressure PH is maintained so that the high / low pressure difference can be maintained above a certain level. Control is required to increase the

When the cooling operation is performed under low temperature outside air,
In particular, when the capacity of the indoor unit is small, the indoor unit freezes and the refrigerant low pressure PL on the suction side of the compressor 1 becomes lower than the required low pressure. At this time, there is a method of sending high-pressure refrigerant on the discharge side to the suction side (for example, using the hot gas bypass BP1 described above) in order to raise the refrigerant low pressure PL in the compressor 1 suction circuit C2. The high pressure PH of the refrigerant on the discharge side is insufficient, and even if this measure is used, the required low pressure PL of the refrigerant cannot be obtained, and the high-low pressure difference is further reduced, and the above-mentioned harmful effect in the compressor 1 also occurs. In order to obtain the required low-pressure refrigerant PL, the high-low pressure difference must be maintained above a certain level, and therefore, the control for increasing the high-pressure refrigerant PH is required as described above.

Here, the value of the refrigerant high pressure PH required for maintaining the high / low pressure difference will be verified with reference to FIG. In order to obtain the required high / low pressure difference according to the transition of the refrigerant low pressure PL, f
It must be ₁ (PL) <PH <f ₂ (PL) (f ₁ (PL) and f ₂ (PL) are numerical values obtained from an equation with the refrigerant low pressure PL as a variable). When the refrigerant high pressure PH is held in this (stable zone SZ), stable cooling operation can be obtained, and when the refrigerant high pressure PH becomes lower than the stable zone SZ, a predetermined high-low pressure difference cannot be obtained. Therefore, the high pressure securing operation described below must be performed. Further, when the refrigerant high pressure PH is higher than that in the stable zone SZ, the condensation pressure of the high pressure gas refrigerant is too strong and conversely the refrigerating capacity decreases, so the refrigerant high pressure PH must be reduced.

The engine heat pump of this embodiment has a structure shown in FIG. 12 in order to maintain the refrigerant low pressure PL and the high and low pressure difference.
An automatic control mechanism such as This will be described.
First, if possible, the capacity control of the compressor 1, which is a multi-compressor, is used (1). That is, the engine speed is adjusted from the minimum speed to the maximum speed, and further, the operating number of compressors in a multi-compressor in which two compressors are combined is adjusted to one or two, and the refrigerant is The high pressure PH and the refrigerant low pressure PL are properly maintained. When the low-pressure refrigerant PL is low,
The pumping capacity is reduced in order to reduce the amount of refrigerant condensation in the outdoor heat exchanger 6.

The holding control of the refrigerant low pressure PL will be described. When the refrigerant low pressure PL is reduced in combination with the capacity control of the compressor 1, the solenoid valve SV1 is turned on and the hot gas bypass BP1 is opened (2). As a result, the high-pressure gaseous refrigerant on the discharge side is caused to flow into the suction side to raise the refrigerant low-pressure PL, but the refrigerant low-pressure PL does not fall again as soon as the solenoid valve SV1 is turned off. After raising to a certain position, turn off the solenoid valve SV1
To do. At the same time, the outdoor fan control (3) ′ is performed to increase the high pressure of the refrigerant on the discharge side to the suction side. In this case, the step of the fan speed divided into the n stages is It shall be adjusted by changing it step by step. When the outdoor fan control (3) 'is insufficient, the electronic expansion valve and the modular bypass control (4)'
However, since this is an application of the electronic expansion valve and the modulated bypass control (4) described later, a high pressure securing control for securing the next high / low pressure difference will be described.

The high pressure ensuring control will be described. Even if the compressor 1 is in the minimum capacity operation and the solenoid valve SV1 of the hot gas bypass BP1 is turned on, if the refrigerant low pressure PL is low, the refrigerant high pressure PH may be lowered. In order to secure the refrigerant high pressure PH at a certain level or higher, in the outdoor heat exchanger 6, condensation due to heat dissipation is suppressed, and the refrigerant in the high pressure gas state is passed through.
Further, the passage of the refrigerant on the outlet side is narrowed down. First, in order to suppress heat radiation, control is performed to reduce the rotational speed step of the outdoor fan 5 (3). In this outdoor fan control, unlike the above, the refrigerant high pressure PH
Since it is necessary to rapidly increase the temperature to within the stable zone SZ, as shown in FIG. 16, based on how much the difference ΔP ₁ between the actual refrigerant high pressure and the minimum refrigerant high pressure f ₁ (PL) is, The fan step is the minimum f of the refrigerant high pressure at a stretch.
_To increase to ₁ (PL), increase the fan rotation speed step
As shown in the table, it is performed by changing a plurality of values at the same time.

On the contrary, if the refrigerant high pressure PH is too high and exceeds the refrigerant high pressure maximum f ₂ (PL),
In order to decrease the refrigerant high pressure PH at once, similarly, an operation of simultaneously changing a plurality of steps is performed based on the difference ΔP ₂ between the actual refrigerant high pressure and the maximum refrigerant pressure high limit f ₂ (PL) (FIG. 15).

Even if the rotation speed of the outdoor fan 5 is reduced and the minimum step (2.5 HZ) shown in FIG. 13 is reached, the refrigerant high pressure P
When H is lower than the stable zone SZ, or when the cooling water temperature exceeds a predetermined temperature while the rotation speed is decreasing, the outdoor fan control is at the limit, and the next outdoor heat exchanger 6 outlet side The control shifts to the control for restricting the refrigerant passage, that is, the electronic expansion valve and the modulated bypass control (4). First, the solenoid valve SV4 is closed, the electric bypass BP4 is closed, and the refrigerant from the outdoor heat exchanger 6 is passed only to the electronic expansion valve 8/8. As shown in FIG. 14, the electronic expansion valve 8 has m steps of opening steps, but initially, as the cooling specification, the electronic expansion valves 8 and 8 are fully opened. When the high pressure holding control shifts to the electronic expansion valve control, the opening step of the electronic expansion valves 8 and 8 is reduced, that is, the opening is reduced so that the refrigerant does not flow smoothly, and the refrigerant high pressure PH on the discharge side of the compressor 1 is reduced. Increase. At this time, since the outlet side is throttled by the electronic expansion valve 8.8, the outdoor heat exchanger 6
In the above, due to the retention of the refrigerant, the condensation is promoted, the amount of the liquid refrigerant increases, and the passage of the high-pressure gas refrigerant from the discharge circuit C1 is narrowed by the outdoor heat exchanger 6, so that the refrigerant high pressure PH is further increased. Bring about a synergistic effect of promotion.

In addition to this electronic expansion valve control, the electronic expansion valve 8
・ If a high pressure is applied to the liquid receiver 9 on the outlet side of 8, the pressure will be applied more than on the outlet side of the outdoor heat exchanger 6, and the tendency of the refrigerant to accumulate will further increase.
Further promotes high pressure. Therefore, in order to suck the high-pressure gas refrigerant in the discharge circuit C1 from above the liquid receiver 9, the solenoid valve SV5 of the modulated bypass (pressure adjusting bypass circuit) BP5 is opened. However, if the refrigerant is passed through the modulated bypass BP5 while the opening degree of the electronic expansion valve 8 is not narrowed too much, the refrigerant high pressure PH rises sharply, and the temperature rises above the stability zone SZ in FIG. turn into. On the contrary, it is known that the rapid increase in the refrigerant pressure can be avoided by opening the modulated bypass BP5 in a state where the opening is equal to or less than a certain degree.
Therefore, the modular bypass control is added to the electronic expansion valve control when the opening of the electronic expansion valve 8 is the intermediate opening m ₁ (* in FIG. 14).

Due to these controls, the refrigerant high pressure PH increases, the refrigerant low pressure PL also becomes a value above a certain pressure while maintaining the high / low pressure difference, and the refrigerant high pressure PH becomes stable zone SZ in FIG.
When it comes to shift in the inside, the motorized valve bypass BP again
4 is opened and the electronic expansion valves 8 and 8 are fully opened to switch to the cooling operation specification.

[0050]

Since the present invention is configured as described above, it has the following effects. That is, since it is configured as in claim 1, a pressure due to the liquid refrigerant accumulated in the liquid receiver is generated from the liquid kit receiver side toward the outdoor heat exchanger, a cooling effect of the liquid refrigerant is exerted on the outdoor heat exchanger, and the refrigerant is condensed. Since it is further promoted, the cooling effect can be improved without increasing the compressor capacity or the outdoor fan rotation speed, which contributes to cost reduction. However, the condition is that the high pressure of the refrigerant on the discharge side of the compressor can be allowed to rise.

Since the four-way valve is closed, the most pressure fluctuation occurs when switching the four-way valve, but the solenoid valve of the pressure equalizing bypass and all the other solenoid valves are open. , When no back pressure is applied and the solenoid valve of the pressure equalizing bypass is closed next to stop the pressure equalization, all the other solenoid valves are open and the solenoid valve of the pressure equalizing bypass is closed. Pressure fluctuation due to valve closing, that is, back pressure is not applied, then all other solenoid valves are closed.When closing the four-way valve and all solenoid valves, back pressure is applied to all valves. Without taking
Avoids chattering of the valve, enables long-time valve specifications, and reduces maintenance work.

Further, according to the third aspect of the present invention, during cooling under low temperature outside air, etc., the low pressure of the refrigerant on the compressor suction side can be promptly improved to avoid freezing of the indoor unit and to perform favorable cooling. In addition, it is possible to keep the high and low pressure difference between the compressor discharge side and the suction side, and it is possible to prevent chattering of vanes in the compressor and the outdoor fan.

[Brief description of drawings]

FIG. 1 is a front view showing an arrangement positional relationship between an outdoor heat exchanger and a liquid receiver according to the present invention.

FIG. 2 is a schematic front view showing the positional relationship between the liquid level height and the outdoor heat exchanger in the liquid receiver.

FIG. 3 is a graph showing the refrigerant capacity ratio CP, the degree of supercooling ΔT, and the refrigerant high pressure PH for each liquid level height shown in FIG.

FIG. 4 is a view showing an arrangement structure of a conventional liquid receiver, which is arranged below an outdoor heat exchanger.

FIG. 5 is a view showing a refrigerant pipe introduced from the outside of the outdoor heat exchanger in the same manner.

FIG. 6 is a refrigerant system diagram of an engine heat pump during pressure equalization processing.

FIG. 7 is a front sectional view of a solenoid valve SV.

FIG. 8 is a time chart showing the ON / OFF timing of each solenoid valve during the pressure equalization process associated with the system stop.

FIG. 9 is a time chart diagram showing ON / OFF timing of each conventional solenoid valve.

FIG. 10 is a refrigerant system diagram of the engine seat pump during cooling.

FIG. 11 is a refrigerant system diagram of an electronic expansion valve for increasing the refrigerant high pressure during cooling and an engine heat pump during modulated bypass control.

FIG. 12 is a flowchart of refrigerant low pressure holding control and refrigerant high pressure holding control during cooling.

FIG. 13 is a diagram showing rotation speed steps of the outdoor fan 5.

FIG. 14 is a diagram showing an opening step of the electronic expansion valve 8.

FIG. 15 is a graph showing a high / low pressure difference between a discharge side and a suction side of a compressor.

FIG. 16 is a refrigerant system diagram of the engine heat pump during heating.

FIG. 17 is a refrigerant system diagram of the engine heat pump during defrosting processing in the outdoor heat exchanger during heating.

FIG. 18 is a refrigerant system diagram of the engine heat pump when the heat radiation circuit is opened during heating.

FIG. 19 is a side view of the pressure regulating valve PV.

FIG. 20 is a plan view of the same.

FIG. 21 is a graph showing the displacement of the refrigerant high pressure with respect to the outside air temperature when the room temperature is maintained at 30 ° C.

FIG. 22 is a graph showing the displacement of the blowing temperature in the indoor unit with respect to the high pressure of the refrigerant.

[Explanation of symbols]

A Outdoor unit B Indoor unit PH Refrigerant high pressure PL Refrigerant low pressure BP1 Hot gas bypass (equal pressure equalizing bypass circuit) BP4 Electric valve bypass BP5 Modulated bypass (pressure regulating bypass circuit) SV1 to SV6 Solenoid valve 1 Compressor 3 Four-way valve 5 Outdoor fan 6 Outdoor heat exchanger 8 Outdoor electronic expansion valve 9 Liquid receiver

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor, Haya Nakamura 1-32, Chayamachi, Kita-ku, Osaka, Osaka Prefecture Yanmar Diesel Co., Ltd. (72) Inventor, Takahiko Masuda 1-32, Chaya-machi, Kita-ku, Osaka-shi, Osaka Yanmar Diesel Co., Ltd.

Claims (3)

[Claims] 1. In an outdoor unit of an engine heat pump, a refrigerant pipe extending from one end of the heat exchanger at a position where the liquid level in the liquid receiver is superposed on the middle part of the vertical width of the heat radiating pipe of the heat exchanger. A pressure regulating mechanism for an engine heat pump, which is installed under the liquid receiver. 2. A pressure equalizing mechanism for opening all other solenoid valves in a refrigerant system when an solenoid valve is opened in a pressure equalizing bypass circuit communicating from a compressor discharge circuit to an intake circuit in an outdoor unit of an engine heat pump. , Valve closing
A pressure regulating mechanism for an engine heat pump, wherein a time difference is provided in the order of a four-way valve, a solenoid valve of the pressure equalizing bypass circuit, and all other solenoid valves. 3. In an outdoor unit of an engine heat pump, a bypass circuit for adjusting pressure is provided between a discharge circuit of a compressor and a liquid receiver, and a rotation speed control of a heat exchanger cooling fan and an opening degree control of an electronic expansion valve are performed. By controlling the opening and closing of the solenoid valve in the pressure regulating bypass circuit, the low pressure refrigerant pressure of the compressor suction circuit required for cooling, and
A pressure regulating mechanism for an engine heat pump, characterized in that a high-low pressure difference of refrigerant is obtained between a compressor discharge circuit and a suction circuit.