JPH09113059A - Engine-driven air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control an engine to target number of revolutions corresponding to air conditioning load by providing a controller for controlling the engine to the target number of revolutions corresponding to the air conditioning load after the capacity of a compressor is switched to a partial load state when the load is reduced during operating of the compressor in the full-load state. SOLUTION: When the control is started, the air conditioning load is calculated, and whether the load state required for a compressor is full or partial load is decided based on the load. When the partial load is decided, the compressor is set to the partial load state, and the number of revolutions of the engine is controlled to the number of revolutions corresponding to the load. When the full load is decided, the compressor is set to the full-load state, and the number of revolutions of the engine is controlled to the target number of revolutions corresponding to the load. When the partial load state is required due to the decrease in the load during the full-load operating, the compressor is switched to the partial load state, and the number of revolutions of the engine is raised. When the engine becomes the target number of revolutions corresponding to the load, the number of revolutions is maintained.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an air conditioner having a compressor driven by an engine.

[0002]

2. Description of the Related Art An example of a conventional air conditioner of this type is shown in FIG. When the compressor 2 with the capacity control mechanism 2A is driven by the engine 1 during the cooling operation, the gas refrigerant discharged from the compressor 2 passes through the four-way valve 3 to the outdoor heat exchanger 4 as shown by the solid arrow. It enters and condenses into liquid by radiating heat to the outside.

This liquid refrigerant is adiabatically expanded in the process of passing through the throttling mechanism 5, and then enters the indoor heat exchanger 6, where it evaporates and evaporates by cooling the indoor air. Then, the gas refrigerant returns to the compressor 2 via the four-way valve 3.

During the heating operation, the four-way valve 3 is switched in the opposite direction, and the refrigerant discharged from the compressor 2 has the four-way valve 3, the indoor heat exchanger 6, the throttle mechanism 5, and the outdoor as shown by the broken line arrow. After passing through the heat exchanger 4 and the four-way valve 3 in this order, the compressor 2
Return to

The engine 1 according to the air conditioning load of the air conditioner
The number of revolutions and the capacity of the compressor are controlled.

[0006]

In the conventional air conditioner described above, when the air conditioning load decreases during operation with the capacity of the compressor 2 set to the full load state by the capacity control mechanism 2A, the rotational speed of the engine 1 is changed. Since the capacity of the compressor 2 is switched to the partial load state, there is a problem that the air conditioning capacity temporarily becomes larger than the air conditioning load at this time.

[0007]

SUMMARY OF THE INVENTION The present invention has been invented to solve the above problems, and its gist is to provide a compressor with a capacity control mechanism and an engine for directly driving the compressor. In an engine-driven air conditioner that controls the rotational speed of the engine and the capacity of the compressor according to the air conditioning load, when the air conditioning load decreases while the compressor is operating in a full load state, An engine-driven air conditioner is provided with a control device for controlling the engine to a target speed corresponding to an air conditioning load after switching the capacity to a partial load state.

[0008]

DETAILED DESCRIPTION OF THE INVENTION One embodiment of the present invention is shown in FIGS. As shown in FIG. 1, a compressor 2, a four-way valve 3, an outdoor heat exchanger 4, a throttle mechanism 5, an indoor heat exchanger 6
A refrigerating cycle is constituted by the above, and the refrigerant circulates as indicated by the solid arrow during the cooling operation and circulates as indicated by the broken arrow during the heating operation.

Then, the rotation speed of the engine 1 and the compressor 2
Is provided with a control device 22 for controlling the capacity of the
The air conditioning load 21 is input to 22. The control device 22 outputs to a speed change mechanism 1A such as a governor of the engine 1 and a capacity control mechanism 2A such as a bypass method of the compressor 2.

Therefore, as shown in FIG.
When Q ₁ , the compressor 2 is in the full load state NF, and the engine 1 is rotating at the rotation speed NF ₁ .

When the air conditioning load is reduced to Q ₂ , first,
Output to the capacity control mechanism 2A of the compressor 2 and switch this to the partial load state NP. As a result, the operating point shifts from NF ₁ to NP ₁ as shown by the dashed arrow. After that, the speed is output to the speed change mechanism 1A of the engine 1 and the rotation speed is switched to the target rotation speed NP ₂ corresponding to the air conditioning load.

FIG. 3 shows a control flowchart of the control device 22. When the control starts, the air conditioning load is calculated, and then it is determined whether the load condition required for the compressor 2 is full load or partial load based on this air conditioning load.

When the partial load is determined, the compressor 2 is set to the partial load state, and the rotation speed of the engine 1 is controlled to rotate at the target rotation speed corresponding to the air conditioning load. When the full load is determined, the compressor 2 is set to the full load state, and the rotation speed of the engine 1 is controlled to be the target rotation speed corresponding to the air conditioning load.

When the partial load state is required due to the reduction of the air conditioning load during the full load operation, the compressor 2 is switched to the partial load state, and then the rotation speed of the engine 1 is increased. Then, when the target rotational speed corresponding to the air conditioning load is reached, the rotational speed is held at this target rotational speed.

[0015]

According to the present invention, when the air conditioning load decreases while the compressor is operating at full load, the capacity of the compressor is switched to the partial load state, and then the engine is set to the target speed corresponding to the air conditioning load. Therefore, the air conditioning capacity can be prevented from becoming larger than the air conditioning load.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between an air conditioning load and an engine speed in the above embodiment.

FIG. 3 is a control flowchart of the above embodiment.

FIG. 4 is a system diagram of a conventional engine-driven air conditioner.

[Explanation of symbols]

 1 engine 1A speed change mechanism 2 compressor 2A capacity control mechanism 4 outdoor heat exchanger 5 throttling mechanism 6 indoor heat exchanger 22 controller 21 air conditioning load

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Minor Hanai No. 1 Takamichi, Iwazuka-cho, Nakamura-ku, Nagoya-shi, Nagoya Research Laboratory, Mitsubishi Heavy Industries, Ltd. (72) Michio Yoneda No. 1 Takamichi, Iwatsuka-machi, Nakamura-ku, Nagoya (72) Inventor Tadahiro Kato, Asahi-cho 3-chome, Nishibiwajima-cho, Nishikasugai-gun, Aichi Prefecture Mitsubishi Heavy Industries, Ltd.

Claims (1)

[Claims] 1. An engine-driven air conditioner comprising a compressor with a capacity control mechanism and an engine for directly driving the compressor, and controlling the number of revolutions of the engine and the capacity of the compressor according to an air conditioning load, When the air conditioning load decreased while the compressor was operating under full load, a control device was provided for controlling the engine to a target speed corresponding to the air conditioning load after switching the capacity of the compressor to the partial load state. An engine-driven air conditioner characterized by the above.