JP2002206813A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high efficient air conditioner capable of accommodating for a variation in a requisite air conditioning capability without changing a number of rotation of a prime mover, capable of restricting a reduction in thermal efficiency of the prime mover caused by changing-over the number of operating compressors and further capable of expanding a minimum region of operating capacity. SOLUTION: This air conditioner comprises a prime mover (1) acting as a driving machine for the air conditioner; a plurality of compressors (2), (3) driven by the prime mover (1); a transferring mechanism (4) for transmitting a rotating output of the prime mover (1) to the plurality of compressors (2), (3); and a transmission means (5) installed at any one of an output shaft (11) of the prime mover (1), input shafts (6), (7) of the compressor and the transferring mechanism (4). Any one (2) of the plurality of compressors (2), (3) is constituted such that it is always driven during an air conditioning operation. The other compressor (3) is constituted such that it is operated only in the case that a capability more than a predetermined air conditioning capability is required during an air conditioning operation. The transmission means (5) controls a rate of increasing speed to cause a torque of the prime mover (1) to become constant when the number of operating compressors is changed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for driving one or more compressors by a motor to perform air conditioning.

[0002]

2. Description of the Related Art Conventionally, an input shaft of a single compressor and an output shaft of a prime mover (for example, a gas prime mover) are directly connected via a transmission mechanism such as a belt and a pulley, and a speed increase ratio is also fixed. Met. On the other hand, when the required air-conditioning capacity is low, the number of rotations of the compressor is reduced, and the number of rotations of the gas motor is reduced when the speed increase ratio is fixed as described above. There was a problem.

In order to cope with this, a plurality of (for example, two) compressors can be driven to rotate by one motor, and when the required air conditioning capacity is low, only one compressor is operated. That is being done.

However, when the number of operating compressors is switched from two to one, the torque of the prime mover is reduced, and the thermal efficiency of the prime mover is also reduced, leading to a decrease in the efficiency of the entire apparatus.

[0005]

SUMMARY OF THE INVENTION The present invention has been proposed in view of the above problems, and can cope with a change in required air-conditioning capacity without changing the rotation speed of a prime mover. It is an object of the present invention to provide a high-efficiency air conditioner that suppresses a decrease in thermal efficiency of a prime mover due to switching and expands a minimum operation capacity region.

[0006]

An air conditioner according to the present invention comprises a prime mover (1) as a drive source of the air conditioner, a plurality of compressors (2, 3) driven by the prime mover (1), and a prime mover. (1)
A transmission mechanism (4) for transmitting the rotational output of the motor to a plurality of compressors (2, 3), an output shaft (11) of a motor (1) and input shafts (6, 7) of the compressors (2, 3). Transmission means (5) interposed in any of the transmission mechanisms (4), and one of the plurality of compressors (2, 3) is always operated during air-conditioning operation. And other compressors (3)
The transmission means (5) is configured to operate only when the air-conditioning operation requires a predetermined air-conditioning capacity or more.
Is configured to control the speed increase ratio so that the torque of the prime mover (1) becomes constant when the number of operating compressors is switched (claim 1, FIG. 1 to FIG. 6).

Here, the rejected volume of the compressor (2), which is always operated when the air conditioner is operated, is smaller than that of the other compressor (3), which is operated only when a predetermined air conditioning capacity or more is required. It is preferable that the volume is set to be smaller than the exclusion volume (claim 2, FIG. 1 to FIG. 5, FIG. 7).

It is preferable that the transmission means (5) controls the speed increase ratio so that the torque of the prime mover (1) does not fluctuate when switching the number of the compressors (2, 3). Item 3, FIG. 1 to FIG. 5, FIG. 8).

Alternatively, it is preferable that the speed change means (5) controls the speed increase ratio so that the number of rotations of the prime mover (1) does not fluctuate when switching the number of the compressors (2, 3) ( Claim 4, FIG. 1 to FIG. 5, FIG. 9).

Here, the prime mover (1) is not limited to an internal combustion engine such as a gas engine or a combustion engine.
An electric motor, another electric motor, or the like is applicable, and is not particularly limited.

The transmission mechanism (4) for transmitting the rotation output of the prime mover to a plurality of compressors includes winding transmission of belts and pulleys, chains and sprockets, gear transmission mechanisms, and other means for reliably transmitting rotational power to the compressor. Any mechanism can be used as long as the mechanism can be transmitted.

Further, the transmission means (5) may be a continuously variable transmission mechanism such as a so-called "CVT" or a stepped transmission mechanism constituted by a gear mechanism or the like.

According to the present invention having such a configuration, by controlling the speed increase ratio in accordance with the required air conditioning capacity, the required air conditioning capacity can be changed without changing the rotation speed of the prime mover. I can deal with it.

Further, since the speed increase ratio is controlled so that the torque of the prime mover becomes constant when the number of compressors is switched, the thermal efficiency of the prime mover is not reduced by switching the number of compressors. .

In practicing the present invention, the rejected volume of the compressor which is always operated during the air-conditioning operation is smaller than the rejected volume of the other compressor which is operated only when a predetermined air-conditioning capacity or more is required. Is preferably set to be small.

With this setting, it is possible to increase the ratio between the maximum air-conditioning capacity and the minimum air-conditioning capacity (so-called "turndown").

Here, having a plurality of compressors (for example, two compressors) having different displacement volumes is based on the fact that the present invention has the above-mentioned transmission means. In a conventional motor-equipped air conditioner having a fixed speed increase ratio between a motor output shaft and a compressor input shaft, a plurality of air conditioners (for example, 2
This is because, if the compressor is provided, an inoperable region may be generated between the minimum air-conditioning capacity and the maximum air-conditioning capacity.

[0018]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, the air conditioner comprises an outdoor unit indicated by A in its entirety and an indoor unit indicated by B in its entirety.

The outdoor unit A includes a prime mover 1, a first compressor 2 and a second compressor 3 driven by the prime mover 1,
A transmission mechanism 4 including a pulley and a belt for transmitting the rotational force of the prime mover 1 to the first compressor 2 and the second compressor 3,
It includes a continuously variable transmission (hereinafter, a continuously variable transmission is referred to as a CVT hereinafter) 5, a condenser 10 including a condenser 10a and an electric fan 10b, and a piping group for a refrigerant described later. .

Here, the CVT 5 is interposed between the prime mover 1 and the transmission mechanism 4, and is configured so that the speed increase ratio can be appropriately changed in response to a cooling load condition. In FIG. 1, reference numeral 11 indicates an output shaft of the prime mover 1.

On the other hand, a plurality of indoor units B (two
) Expansion valve 20 and a plurality (two in the figure) of evaporators 2
1 and a piping group for a refrigerant described later.

Transmission mechanism 4 comprising pulley and belt
Is a pulley 41 fixed to the output shaft 51 of the continuously variable transmission 5.
A second pulley 42 connected to the input shaft 6 of the first compressor 2 and a third pulley 43 connected to the input shaft 7 with the clutch 8 of the second compressor 3 interposed therebetween. And a belt 44. The torque of the prime mover 1 is transmitted to the pulley 41 via the continuously variable transmission 5, and the torque of the pulley 41 is further transmitted to the second pulley 42 and the third pulley 43 by the belt 44. ing.

The clutch 5 connects and disconnects the rotational force from the prime mover to the second compressor depending on the required cooling load.

The connection relationship between the air-conditioning unit and the air-conditioning pipes is as follows from the outdoor unit A side in the connection order from the first compressor 2 to the first pipe L.
1 is connected to a second pipe L2 provided in the second compressor 3, the second pipe L2 is connected to a third pipe L3 via a switching valve 9, and the third pipe L3 is connected to a condenser. 10a.

From the condenser 10a, a fourth pipe L4 is connected to a fifth pipe L5 provided with the expansion valve 20 on the indoor unit B side, and the fifth pipe L5 is connected to the evaporator 21. .

From the evaporator 21, a sixth pipe L6 is connected to a seventh pipe L7, the seventh pipe L7 is connected to an eighth pipe L8 via the switching valve 9, and an eighth pipe L8 is connected to the eighth pipe L8. The air conditioning unit is connected to the first compressor 2, and all the pipes communicate with the air conditioning unit. When the refrigerant circulates, cooling / heating is performed by transferring heat inside and outside the room.

The switching valve 9 is a valve (9 in the figure).
(0 degree) By rotating, the flow path of the refrigerant is changed, and switching between cooling and heating is performed.

With respect to the change of the required cooling load and the switching of the number of operating compressors (operating method), which are the characteristics of the present invention, the relationship between the motor speed and the motor torque (FIG. 2), the motor speed and the compressor speed , The relationship between the compressor torque and the prime mover torque (FIG. 4), and the relationship between the compressor torque and the compressor rotation speed (FIG. 5), including comparison with the prior art.

For the sake of simplicity, the prior art uses two compressors with an excluded volume of 200 cc / rev, and in the present invention, the excluded volumes of the first and second compressors are respectively set to 100 c / rev.
The transition of operation will be described on the assumption that c / rev is 300 cc / rev (the total cooling capacity is equal in the conventional technology and the present invention), and the room temperature gradually increases and the required cooling load increases.

Referring first to FIG. 2 (see also FIGS. 3 to 5), the operation according to the prior art is a thick broken line connecting A, B, C and D (discontinuous between B and C) according to the present invention. The operation is indicated by a thick solid line connecting a, e, b, c, f, d, g, and j.

In the prior art, the required cooling load is initially small,
The operation of only one compressor starts with the rotation speed of the prime mover at 800 rpm (point A). As the room temperature rises, the rotation speed is increased while maintaining the torque of the prime mover at a constant torque (42 Nm), and the rotation point is reached (1600 rpm). , 2 by connecting the clutch
The second compressor also operates at the same time (jumps from point B to point C).

In the figure, the output of the prime mover is 3.7 kW at point A when one vehicle is operating, as can be read from the iso-power line of the prime mover indicated by the broken line and the isothermal efficiency line indicated by the two-dot chain line.
From the point B at the start of operation of the two units to 11 kW, which is the maximum air-conditioning capacity, at 18 points. On the other hand, the thermal efficiency is less than 20% for the operation of one unit (point A). ) To about 21% (point B).
It changes from 4% (C point) to 28.7% (D point). The speed increase ratio of the two compressors to the prime mover was 1.
This is a fixed value of 45 (see FIG. 3).

On the other hand, according to the system of the present invention, the point a (the prime mover speed is 800 rpm, the prime mover torque is 18 Nm, the prime mover output is 1.44 kW) at the time of the operable minimum air-conditioning capacity having a smaller required cooling load than the point A. Starts the operation with only the first compressor 2 and changes the rotation speed of the prime mover 1 to 800 rpm
m and points a and b (motor torque 75 Nm,
The motor output is 6 kW and the compressor speed is 4000 rpm (see FIG. 3).
) And the compressor torque of 15 Nm (see FIG. 5)) to increase or decrease the speed increase ratio of the continuously variable transmission (CVT) 5 to adjust the air conditioning load.

In FIGS. 3 and 4, the broken lines are equal speed ratio diagrams, and the numbers attached to the right shoulder indicate the speed increase ratio.
Shows the relationship between the rotation speed of the prime mover and the rotation speed of the compressor. Whereas the prior art has a constant gear ratio in all operating ranges, the present invention provides that the prime mover rotation speed is constant when one compressor is operating and two units are operating with a light load, and ,
It is shown that the speed of the compressor is increased by changing the speed ratio of the CVT, and the speed ratio of the CVT is constant and the rotation speed of the prime mover is changed when the load is high and the two units are operated.

FIG. 5 is a graph showing the relationship between the torque of the compressor and the number of revolutions. The torque of one compressor of the present invention during operation of one compressor is smaller than that of the prior art, but the width of the number of revolutions is small. It can be seen that it is easy to deal with especially small required air-conditioning load. In addition, the broken line in FIG. 5 shows an iso-consumption horsepower diagram of the compressor. Here, the same reference numerals are used in FIGS.

As the room temperature rises, point c (the number of motor rotations of 8
00rpm, motor torque 75Nm, motor output 6k
w, compressor speed 1350 rpm (see FIG. 3), compressor torque 60 Nm (see FIG. 5)), the clutch 5 is engaged, the second compressor 3 is also operated, and the prime mover speed is 800
While maintaining the rpm, the speed increase ratio of the CVT 5 is controlled in a range where the motor torque does not exceed 100 Nm (point d).

If the air conditioning load further increases, the CVT
By keeping the speed increase ratio of 5 constant, increasing the number of revolutions of the prime mover 1 and controlling the vehicle to reach the maximum air conditioning capacity via the point G, the required cooling load can be met. In addition,
The point G represents the same output point as the output of the prime mover at point B and point C in the prior art, and does not indicate a singular point in operation.

The comparison between the thermal efficiency of the prime mover of the present invention and that of the prior art is carried out for a rotational speed of 800 rpm or more, which consumes the most energy.

In the prior art, as described above, the thermal efficiency in a single-unit operation is reduced from less than 20% (point A) to about 21% (point B).
However, 28.4% (point C) to 28.7% for two-unit operation
(Two points). On the other hand, in the present invention, the two-vehicle operation is performed in the above-mentioned operation range, and 28.3% (d point) decreases
Up to 9.7% (H point), surpassing the conventional technology. (See Fig. 2)

As shown in FIG. 6, the relationship between the heat efficiency of the prime mover and the air conditioning capacity is improved in the entire air conditioning capacity area of the present invention as compared with the prior art. ) In the low to medium capacity range. The reference numerals in FIG. 6 correspond to those in FIGS. 2 to 5.

As described above, the displacement volume 30 of the second compressor 30
For 0 cc / rev, the displacement volume of the first compressor is 1
By using a lower value of 00 cc / rev and using it from low to high speeds, the turndown (the ratio of the maximum air-conditioning capacity to the minimum air-conditioning capacity) can be increased, and in addition to meeting the needs of finer air conditioning, It also achieves energy savings.

The control flow for operating at each point shown in FIGS. 2 to 5 will be described with reference to FIG. 7 (also referring to FIG. 1).

After starting, in step S1, it is determined whether or not the air-conditioning load is to be varied. If it is not necessary to do so (NO in step S1), step S1 is performed.
Repeat 1. If it is necessary to change (step S1
YES at step S2), and proceeds to step S2.

In step S2, it is determined whether or not the number of revolutions of the compressor is between the lower limit value and the upper limit value. If not, (NO in step S2), the process proceeds to step S3.
Disconnects and connects the clutch 8, switches the number of operating compressors,
Proceed to step S4. If there is an interval (YES in step S2), the process proceeds to step S4.

In step S4, it is determined whether or not the speed increase ratio of the CVT is between the lower limit value and the upper limit value. If not, the process proceeds to step S5 and proceeds to step S5. If (YES in step S4), the process proceeds to step S6.

In step S6, the speed increase ratio of the CVT is changed to a predetermined value according to a database (not shown) while keeping the rotation speed of the prime mover, and the process proceeds to the next step S7 to determine whether or not the air conditioning capacity is the predetermined. If it is not the predetermined air conditioning capacity (NO in step S7), the process returns to step S6, and if it is the predetermined capacity (YE in step S7).
S), returning to step S1.

In step S5, while the speed increase ratio of the CVT is kept constant, the rotation speed of the prime mover is changed, and the process proceeds to the next step S8.

In step S8, it is determined whether the air conditioner has the predetermined air conditioning capability. If the air conditioner is not the predetermined air conditioner (NO in step S8), the process returns to step S5, and if the air conditioner has the predetermined air conditioner (YES in step S8). , Step S
1 and the above flow is repeated.

According to the present invention having such a configuration, by controlling the speed increase ratio in accordance with the required air conditioning capacity, the required air conditioning capacity can be changed without changing the rotation speed of the prime mover. I can deal with it.

Here, the apparatus itself is the same as in the first and second embodiments (see FIG. 1), but when switching the number of operating compressors (corresponding to a point between point d and point G in FIG. 2). )
In order to prevent the torque of the motor 1 from fluctuating, the CVT 5
It is also possible to configure so as to control the speed increase ratio. The control flow in this case will be described with reference to FIG. 8 (see also FIGS. 1 and 2).

After starting, in step S21,
It is determined whether or not to switch the number of operating compressors based on the required air-conditioning capacity, and if there is no need to switch (step S21)
In step S21, if step S1 is repeated and it is necessary to switch (YES in step S21), the process proceeds to step S22.

In step S22, the torque of the prime mover 1 is detected, and the speed increase ratio is determined from this torque value, and the CVT is determined.
5 is changed (step S23), and step S24 is changed.
Proceed to.

In step S24, it is determined whether or not a predetermined speed increase ratio has been reached. If the predetermined speed increase ratio has not been reached (NO in step S24), step S23 is executed.
And if the predetermined speed increase ratio has been reached (step S24).
Is YES), the process returns to step S21, and the same control is repeated thereafter.

When the number of operating compressors is switched, the speed increase ratio is controlled so that the torque of the prime mover is constant, so that the thermal efficiency of the prime mover does not decrease by switching the number of operating compressors.

Further, the apparatus itself is the same as that shown in FIG. 1, but when switching the number of operating compressors (FIG. 2).
(Corresponding to a point between point f and point d)), the speed increase ratio of the CVT 5 may be controlled so that the rotation speed of the prime mover 1 does not fluctuate. The control flow in this case will be described with reference to FIG. 9 (see also FIGS. 1 and 2).

After starting, in step S31,
It is determined whether or not to switch the number of operating compressors based on the required air-conditioning capacity, and if there is no need to switch (step S31)
In step S31, if step S31 is repeated (YES in step S31), the process proceeds to step S32.

In step S32, the rotation speed of the prime mover 1 is detected, the speed increase ratio is determined, the speed increase ratio of the CVT 5 is changed (step S33), and the process proceeds to step S34.

In step S34, it is determined whether or not a predetermined speed increase ratio has been reached. If the predetermined speed increase ratio has not been reached (NO in step S34), step S33 is executed.
And if the predetermined speed increase ratio has been reached (step S34).
Is YES), the process returns to step S31, and the same control is repeated thereafter.

According to the air conditioner of the present invention having such a configuration, by controlling the speed increase ratio in accordance with the required air conditioning capacity, the required air conditioning capacity can be maintained without changing the rotation speed of the prime mover. Can be dealt with. With this configuration, the thermal efficiency of the prime mover does not decrease due to the switching of the number of operating compressors.

Furthermore, if the excluded volume of the compressor that is always operated during the air-conditioning operation is set smaller than the excluded volume of other compressors that are operated only when a predetermined air-conditioning capacity or more is required, It is possible to increase the ratio between the maximum air conditioning capacity and the minimum air conditioning capacity (so-called “turndown”).

[0062]

As described above, according to the present invention, the following excellent effects can be obtained. (A) By controlling the speed increase ratio in accordance with the required air-conditioning capacity, it is possible to cope with the required change in the air-conditioning capacity without changing the rotation speed of the prime mover, thereby improving the efficiency of the prime mover. (B) There is no decrease in the thermal efficiency of the prime mover due to switching of the number of operating compressors. (C) Since the rejection volume of the compressor that is constantly operated is set to be smaller than the rejection volume of other compressors that operate only when a predetermined air conditioning capacity or more is required, the maximum air conditioning capacity And the minimum air-conditioning capacity (so-called “turndown”) can be increased, or the air-conditioning needs can be finely adjusted. (D) Energy saving can be achieved.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an air conditioner according to a first embodiment and a second embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between the rotation speed of the prime mover and the torque at a predetermined operation point of the prime mover for GHP.

FIG. 3 is a diagram showing a relationship between a prime mover rotational speed and a compressor rotational speed at an operation point of a GHP prime mover.

FIG. 4 is a diagram showing the relationship between compressor torque and prime mover torque at operating points of the GHP prime mover.

FIG. 5 is a diagram showing a relationship between compressor torque and compressor rotation speed at an operation point of the GHP prime mover.

FIG. 6 is a graph showing the relationship between the air conditioning capacity and the heat efficiency of the prime mover.

FIG. 7 is a flowchart showing an operation control flow of the GHP prime mover according to the present invention.

FIG. 8 is a flowchart showing operation control when changing the number of operating compressors of the GHP prime mover according to the present invention, the control being performed to keep the prime mover torque constant.

FIG. 9 is a flowchart showing operation control when changing the number of operating compressors of the GHP prime mover according to the present invention, the control being performed to keep the prime mover rotational speed constant.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... 1st compressor 3 ... 2nd compressor 4 ... Transmission mechanism 5 ... Transmission means (continuously variable transmission) 6 ... Input shaft 8 ...・ Clutch 9 ・ ・ ・ Switching valve 10 ・ ・ ・ Condenser A ・ ・ ・ Outdoor unit B ・ ・ ・ Indoor unit

Claims (4)

[Claims] 1. A motor as a driving source of an air conditioner, a plurality of compressors driven by the motor, a transmission mechanism for transmitting rotation output of the motor to the plurality of compressors, an output shaft of the motor and a compressor , And transmission means interposed in any of the transmission mechanisms, and one of the plurality of compressors is configured to always operate during the air-conditioning operation, and the other compressors The air conditioner is configured to operate only when a predetermined air conditioning capacity or more is required during the air conditioning operation, and the transmission means controls the speed increase ratio so that the torque of the prime mover becomes constant when the number of operating compressors is switched. An air conditioner characterized by having the following configuration. 2. The rejection volume of the compressor that is constantly operated during the air-conditioning operation is set to be smaller than the rejection volume of the other compressors that operate only when a predetermined air-conditioning capacity or more is required. The air conditioner of claim 1, wherein: 3. The speed changer according to claim 1, wherein, when switching the number of the compressors, the speed changer controls the speed increase ratio so that the torque of the prime mover does not fluctuate.
The described air conditioner. 4. The apparatus according to claim 1, wherein the speed change means controls a speed increase ratio so that the number of rotations of the prime mover does not fluctuate when switching the number of the compressors.
The described air conditioner.