JPH01237372A - Supercharging compressor - Google Patents

Abstract

PURPOSE:To improve the volume efficiency in the whole operation range by operating an inlet tube length selecting device based on the rotating speed of a compressor, and setting the inlet tube length so that the primary mode column frequency in the inlet tube is tuned with the rotating speed of the compressor. CONSTITUTION:A length selecting passage 22 to which an inlet tube length changing device 14 is spirally wound is provided with communicating port. A communicating port selecting plate 23 is provided with a communicating port 24 so that a plurality of ports are not communicated each other simultaneously on one side of a divisional plate 26. The communicating port selecting plate 23 is rotated by a motor 25 through a shaft 28. Then, the motor 25 is provided with a rotating angle position detector to correspond the rotating angle position to the inlet tube length in 1:1. Based on the rotating speed of the compressor, an equivalent inlet tube length is determined so as to tune the operational frequency of the compressor with the primary mode column frequency. Thereafter, the nearest inlet tube length, namely the rotating angle position of the motor 25 is selected.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a rotary compressor used in refrigerators, air conditioners, etc., and is particularly suitable for improving the performance of the compressor over the entire operating range. Regarding an inertial supercharging mechanism.

[Conventional technology]

A conventional device of this kind, as described in Japanese Utility Model Application Publication No. 57-40679, has a sliding mechanism for both the suction pipe of the compressor and the pipe on the outlet side of the evaporator in order to change the length of the suction pipe. The U-shaped suction pipes were fitted together in a freely movable manner and were moved by a drive device.

[Problem to be solved by the invention]

The above conventional technology has a structure in which the U-shaped suction pipe is taken in and out, so the length of the suction pipe cannot be shortened, and an inertia supercharging function on the high-speed side cannot be expected. There were problems in that a seal was required and precision in machining the suction pipe, etc. was required.

When the rotation speed of the compressor is controlled using an inverter, the volumetric efficiency decreases in the high-speed operating range due to pressure loss on the suction side, etc., as shown in FIG. Therefore, in order to obtain the necessary amount of refrigerant circulation, it is necessary to increase the theoretical capacity of the compressor or to increase the speed of the compressor. If you increase the theoretical volume, you will be able to operate at a lower speed on the low speed side,
A problem arises in which volumetric efficiency decreases due to leakage. or,
Operating the compressor at higher speeds shortens the life of the bearings, which poses problems in terms of bearing reliability. Conventional technology does not take these points into consideration, and if the sealing problem is solved and the volumetric efficiency is improved in the entire operating range of the compressor, the compressor can be made smaller and the above problems can be solved. .

An object of the present invention is to improve the volumetric efficiency in the entire operating range of the compressor.

[Means to solve the problem]

To achieve the above object, the present invention provides a supercharging compressor that includes a compression mechanism, a buffer space container provided on the suction side of the compression mechanism, and a suction pipe, in which the filling efficiency of the compressor is 1. The cross-sectional area of the suction pipe is determined so as to satisfy the flow resistance coefficient μ of the suction pipe and the inertial supercharging characteristic number zo in the range exceeding This is achieved by providing a device for varying the length of the suction tube.

[Effect]

The rotational speed of the compressor is detected, and the means for varying the length of the suction pipe is controlled so that the air column frequency of the first mode of the suction pipe and the rotational speed of the compressor are synchronized. At this time, since the cross-sectional area of the suction pipe is determined so that the filling efficiency of the compressor exceeds 1, the volumetric efficiency of the compressor can be improved.

〔Example〕

On the suction side of the rotary compressor, as shown in FIG. 4, an accumulator 10 is provided to prevent liquid refrigerant from being sucked into the compressor. It consists of a suction pipe 12 that connects the accumulator outlet to the compressor suction port, a compression mechanism section 3, and the like.

Inside the casing 1 is a motor section 2. Cylinder 5. Upper bearing 6
．． Lower bearing 7° roller 8. The discharge ports 9 are arranged as shown in the figure. Inverter driven bag [1] shown in Figure 6
5 drives the compressor, and when the shaft 5 rotates, the volume of the suction chamber changes as shown in FIG. 7 during the suction stroke. When entering the suction stroke, the pressure in the suction chamber decreases, so the refrigerant gas in the suction pipe begins to accelerate toward the compression mechanism. When gas flows, friction occurs on the inner surface of the pipe. The accelerated refrigerant gas is given an inertial force, and the gas once sucked into the compression mechanism acts like a gas spring. Different. where, , p (O) is the pressure inside the cylinder. If we make this dimensionless, we get Also, it is. Here, As is the cross-sectional area of the pipe, Vh is the rotational angular velocity of the shaft, (2) (θ) is the cylinder volume on the suction side at the rotational angle θ, and a(+ is the speed of sound).

The inertial supercharging effect is a phenomenon in which the accelerated gas at the end of the suction stroke is pushed in by inertia force that overcomes the gas spring action and frictional force, resulting in an improvement in the filling efficiency of the compressor. However, in order to maximize its effect, it is necessary to
must be large. Figure 8 shows the calculation results obtained by solving the above equation. As the flow resistance coefficient μ increases, the inertial force itself decreases, so the effect of inertial supercharging disappears. Therefore, the flow resistance coefficient must be made as small as possible, and the effect can be expected when the filling efficiency q exceeds 1 and μ is less than 0.5. For example, when μ=0.5, the charging efficiency q does not exceed 1 by increasing the inertial supercharging characteristic number Zo.

Further, the range of the inertial supercharging characteristic number Zo, which has an inertial supercharging effect, may be set to about 0.6 or more.

Therefore, the cross-sectional area of the suction pipe is As, the resistance coefficient at the entrance and exit of the pipe is λ, and the coefficient of friction of the pipe is ν. Therefore,
As the tube cross-sectional area As becomes smaller, μ increases monotonically, and only one tube cross-section Asz can be determined with μ=0.5. Also, 7. Pipe cross-sectional area AS with o = 0, 6
2 becomes . From the above, the cross-sectional area of the intake pipe is selected to be in the range As1<As<As2.

However, this alone is not sufficient to obtain the inertial supercharging effect, and as can be seen from the experimental results shown in Figure 9, the conditions under which the volumetric efficiency η7 peaks with respect to the inertial supercharging characteristic number Zo are There is. In other words, in order to obtain a sufficient inertial supercharging effect, it is necessary to increase the pressure fluctuations in the pipe that occur due to periodic fluctuations in the suction stroke, and to use this together with the pulsation effect to increase the confining pressure at the end of the suction stroke. There is. The m-th natural frequency f1 of the intake pipe system is Lv, where Lv (Lv=Ls+Vh-As) is the equivalent pipe length that takes into account the stroke volume, and aO is the speed of sound. Letting the operating frequency of the compressor be n, the ratio is defined as the frequency ratio, and the experimental data in Figure 9 for the first mode of m = 1 is organized with respect to the frequency ratio, as shown in Figure 10. It can be seen that this is effective when the frequency ratio is near 1.

In this way, in order to obtain the inertial supercharging effect, (1) the flow resistance coefficient μ should be less than 0.5, (2) the inertial supercharging characteristic number Zo should be 0.6 or more, and (3) the resonance of the pipe system should be adjusted. It is necessary to keep the ratio of the primary mode of frequency and the operating frequency of the compressor close to 1.

Embodiments of the present invention will be described below with reference to FIGS. 1 to 3.

The present invention is applicable to rolling piston type rotary compressors, ranging from small compressors with a stroke volume of about 3 d/rev used in refrigerators to 50 cxl used in air conditioners.
Normally applied to medium-sized compressors up to about /rev. Further, as for gas, refrigerant R-12 is usually used in refrigerators, and refrigerant R-22 is used in air conditioners.

As mentioned above, the structural requirements for carrying out the present invention are as follows.
The cross-sectional area of the suction pipe is determined so that the filling efficiency exceeds 1, and the length of the suction pipe is switched one after another to tune the resonance frequency of the first mode by detecting the rotational speed and sound velocity of the compressor. The purpose of the present invention is to provide a suction pipe length variable device structure that can shorten the suction pipe length so as not to lose its effect even in a high speed range.

In the embodiment shown in FIG. 1, a communication hole is provided between each turn of the length switching passage 22 formed by spirally winding the suction pipe length variable device 14, and a partition plate is provided at the same time as the communication hole switching plate 23. 26
On one side of the connecting hole 2, make sure that two or more holes do not communicate with each other.
Place 4.

This communication hole switching plate 23 is rotated around a shaft 28 by rotating the motor 25. Further, the partition plate 26 is configured to communicate with the communication hole 24 and the suction port communication hole 27 in the axial direction at a rotational position of the motor 25 where the communication hole 24 and the suction port communication hole 27 do not communicate with each other.

Although not shown, the motor 25 is provided with a rotational angular position detector, so that the rotational angular position of the motor 25 and the length of the suction pipe correspond one-to-one. As mentioned above, it would be best if the speed of sound could be detected, but if a refrigerant is used,
Since the conditions on the suction side do not change greatly depending on the rotational speed of the compressor, and the speed of sound does not change greatly, it may be stored in the computer as data.

When the compressor is operated, the equivalent suction pipe length at which the operating frequency of the compressor and the air column frequency of the first mode are synchronized can be calculated from the signal from the rotation speed detection circuit of the compressor or the speed command signal using the above formula. calculate.

Based on this calculation result, the closest suction pipe length, that is, the rotational angular position of the motor 25 is selected, and a command is issued to the motor drive device 19 to make corrections by comparing it with the signal from the rotational angular position detector. It has become.

In the embodiment shown in FIGS. 2 and 3, the length switching passage 2
A partition wall is provided between the same circular walls to communicate with the outer passage only at some places to form a single continuous passage, and an inlet communication hole 27 is provided in the center of the partition wall. There is. A partition plate 26 is attached to the side opposite to the suction port communication port 27, and a communication hole switching plate 23 rotated by a motor 25 is installed outside of the partition plate 26. The communication hole switching plate 23 has communication holes 24 formed in a row from the center to the outside as shown in FIG. The holes are opened in such a way that they communicate with the hole 27 through only one communication hole, so that the length of the suction pipe and the rotational angular position of the motor correspond one-to-one.

With this structure, the length of the suction pipe can be made variable as in the embodiment shown in FIG.
The space where the is stored can be used as an accumulator.

With the above configuration, the length of the suction pipe can be set from short to long, and refrigerant leakage can be prevented at low cost. As a result, inertial supercharging can be performed in the entire operating range of the compressor, so that the volumetric efficiency of the compressor can be improved in the entire operating range.

〔Effect of the invention〕

According to the present invention, the volumetric efficiency of the compressor can be significantly improved over the entire operating range, particularly in the high-speed operating range. As a side effect, the compressor can be made smaller and the maximum rotational speed of the compressor can be lower than when inertial supercharging is not applied, which not only improves the reliability of the compressor but also allows it to operate in a region with better overall cross-sectional thermal efficiency. Therefore, compressor input can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of main parts of a supercharging mechanism according to an embodiment of the present invention;
Figure 3 is a cross-sectional view and a plan view of main parts of a supercharging mechanism of another embodiment, Figure 4 is a longitudinal cross-sectional view of the compressor, and Figure 5 shows changes in efficiency with respect to rotational speed of the compressor. 6 is a diagram showing the structure of the cycle, FIG. 7 is a diagram showing the volume change of the suction chamber, FIG. 8 is a diagram showing the relationship between the inertial supercharging characteristic number and charging efficiency, and FIG. The figure is a diagram showing the relationship between the inertial supercharging characteristic number and the volumetric efficiency, and FIG. 10 is a diagram showing the relationship between the frequency ratio and the volumetric efficiency. DESCRIPTION OF SYMBOLS 1...Casing, 2...Electric motor part, 3...Compression mechanism part, 4...Cylinder, 5...Toya shaft, 6...
Upper bearing, 7... Lower bearing, 8... Roller, 9...
Discharge chamber, 10... Accumulator, 11... Discharge pipe, 12... Suction pipe, 13... Rotary compressor, 14... Suction pipe length variable device, 15... Inverter drive device, 16 ... Motor drive device, 17... Rotation speed detector, 18... Four-way valve, 19... Condenser,
2o...Evaporator, 21...Expansion valve, 22...Length switching passage, 23...Communication hole switching plate, 24...Communication hole, 25...Motor, 26... Partition plate, ゝ・, - 1st cause 2nd mouth];su... 3rd ri 4 6 - 辷, Hiko f Naka Yugomi? °A Ken ± Gorge A 9△Ganneyi X''IIa Taki Q1 difference

Claims (3)

[Claims] 1. In a supercharging compressor comprising a compression mechanism section, a buffer space container provided on the suction side of the compression mechanism section, and a suction pipe, a means for detecting the rotation speed of the compressor, and a means for detecting the rotation speed signal based on the detected rotation speed signal. A supercharging compressor, characterized in that the length of the suction pipe is set by a suction pipe length switching device so that the first mode air column vibration frequency in the intake pipe and the rotational speed of the compressor are synchronized. 2. When the suction pipe length switching device is used at the same motor rotation angle as the plurality of communication holes provided in the spiral suction pipe, two or more passages are formed between the compressor suction port side and the suction pipe side of the partition plate. 2. The supercharging compressor according to claim 1, wherein the supercharging compressor is formed from a communication hole switching plate provided with communication holes to prevent the air from being damaged. 3. A length switching passage in which the suction pipe length switching device is provided with a partition wall so as to communicate with an outer passage at only one location of the concentric passage to form a single continuous passage; At the same motor rotation angle, there are two partitions between the suction port communication hole, which communicates with the compressor suction port provided at the center of the length switching passage, and the suction pipe side. The supercharged compressor according to claim 1, characterized in that it is formed from a communication hole switching plate provided with communication holes so that the above passages are not formed.