JPH089575Y2 - Refrigerant compression heat pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a refrigerant compression heat pump having two compressors that are selectively operated.

(Prior Art) An example of a conventional truck refrigerator is shown in FIGS. 4 and 5.

In FIG. 4, 1A and 1B are compressors, 2 is a condenser, 3 is a liquid receiver, 4 is an expansion valve, and 5 is an evaporator.

The compressors 1A and 1B are installed in parallel in the refrigerant circuit, the compressor 1A is driven by the running engine when the truck is running, and the compressor 1B is for precooling or keeping cold in the refrigerator when the truck is stopped. It is driven by a motor to which commercial power is supplied.

During operation of the compressor 1A, the refrigerant gas discharged from the compressor 1A passes through the check valve 6A and enters the condenser 2 where it condenses therein, as shown by the solid line arrow, and then is not condensed in the receiver 3 again. Separate condensed gas. Then, after being adiabatically expanded by the expansion valve 4, it enters the evaporator 5 where it is evaporated. After that, the common suction pipe 7,
It returns to the compressor 1A via the branch suction pipe 8A and the oil trap 9A interposed therein.

During operation of the compressor 1B, the refrigerant, as shown by the dashed arrow,
Check valve 6B, condenser 2, liquid receiver 3, expansion valve 4, evaporator 5,
It circulates to the compressor 1B via the common suction pipe 7, the branch suction pipe 8B, and the oil trough 9B interposed therebetween.

The oil traps 9A and 9B are for preventing refrigerating machine oil from accumulating in the compressor 1A or 1B at rest.

(Problems to be solved by the invention) In many cases, a refrigerant R502 is enclosed in the refrigerant circuit of this type of low temperature refrigerator, but since this refrigerant R502 does not dissolve the refrigerating machine oil, the evaporator 5 to the compressor 1A , Suction pipe 7 leading to 1B,
A gas-phase refrigerant and a liquid-phase refrigerating machine oil flow as a two-phase flow in 8A and 8B.

Then, the evaporator 5 improves the temperature distribution in the refrigerator,
Since the compressors 1A and 1B are installed in the upper part of the inside of the refrigerator, and the compressors 1A and 1B are installed below for convenience of installation, the two-phase flow composed of the vapor phase refrigerant and the liquid phase refrigeration oil is directed toward the compressors 1A and 1B. It flows downward.

Then, during operation of the compressor 1B, as shown in FIG.
Most of the refrigerating machine oil flowing downward through the common suction pipe 7 is sucked into the compressor 1B through the branch suction pipe 8B together with the refrigerant gas, but a part of the refrigerating machine oil is directed to the inner wall surface 10 of the branch portion. Collide with and lose its kinetic energy, which is pressed by the static pressure converted from this kinetic energy, and the branch suction pipe immediately after the bifurcation
A trapezoidal oil sump 11 having a predetermined height is formed in 8A and flows into the compressor 1A through a branch suction pipe 8A.

If this state continues or is intermittent and a long period of time elapses, the amount of refrigerating machine oil in the compressor 1B in operation decreases, and a problem such as poor lubrication of the compressor 1B occurs.

To deal with this, the branch suction pipe 8A immediately after the branch,
8B was provided with oil traps 9A and 9B, but if the pressure at the branch part suddenly increased during defrosting operation, the refrigerator oil accumulated in oil trap 9A or 9B would be pushed into the dormant compressor. there were.

(Problems to be Solved by the Invention) The present invention has been proposed to solve the above-mentioned problems, and the gist thereof is that a gas-phase refrigerant and a liquid-phase refrigerating machine oil pass through a common suction pipe. In a refrigerant compression heat pump that is branched into a branch point and then is sucked into either one of two compressors that are selectively operated via a branch suction tube, the common suction tube immediately before the branch point The branch suction pipe immediately after the branch point is provided with rising portions, and the rising portions are provided at the upper ends of the rising portions from the branch point, respectively, and the height corresponding to the dynamic pressure of the refrigerating machine oil contained in the refrigerant gas is set. A refrigerant compression heat pump is characterized by being set higher than the pressure height.

(Operation) In the present invention, since the refrigerating machine oil has the above-mentioned configuration, most of the refrigerating machine oil flowing upward in the common suction pipe accompanied by the refrigerant gas is branched at the branch portion and passed through the branch suction pipe. Inhaled by the compressor during operation. At that time, a part of the refrigerating machine oil flows through the branch portion into the branch suction pipe communicating with the idle compressor. However, since it cannot pass through the rising portion of the refrigerating machine oil, it is dropped and sucked into the operating compressor.

(Embodiment) One embodiment of the present invention is shown in FIGS. 1 and 2.

As is apparent from FIG. 2, the common suction pipe 7 is directed upward just before the branch point 20, and the branch suction pipes 8A and 8B immediately after the branch point 20 are connected to the dynamic pressure of the refrigerating machine oil contained in the refrigerant gas. It rises diagonally higher than the corresponding static pressure height l, and thus, in the vicinity of the branch point 20, a Y shape is formed by the upward portion 21 of the common suction pipe 7 and the rising portions 22 and 23 of the branch suction pipes 8A and 8B. I am configuring.

Other configurations are similar to those of the conventional one shown in FIG. 4, and corresponding members are designated by the same reference numerals.

Then, during operation of the compressor 1B, most of the refrigerant gas in the gas phase and the refrigerating machine oil in the liquid phase enter the rising portion 23 from the upward portion 21 via the branch point 20 and pass through the branch suction pipe 8B. Sucked into compressor 1B. At this time, a part of the refrigerant gas tries to flow into the rising portion 22, but since the refrigerant gas in the rising portion 22 is stationary, it is held near the branch point 20. Further, since a part of the refrigerating machine oil has a large kinetic energy, it enters the rising portion 22 and rises to a static pressure height 1 corresponding to the kinetic energy, but since it cannot cross the rising portion 22, it rises to a static pressure height l. Immediately after that, the oil drops 24 or adheres to the inner surface of the rising portion 22 as oil drops 24. Then, the oil droplets 24 eventually descend to the branch point 20 due to gravity and are sucked into the compressor 1B in operation along with the refrigerant gas flowing into the rising portion 23.

In the above embodiment, the refrigerant suction pipe is Y-shaped in the vicinity of the branch point, but it is U-shaped as shown in FIG. 3 (A), or as shown in FIG. 3 (B). It can also be U-shaped.

(Effect of the Invention) In the present invention, the common suction pipe immediately before the branch point is provided with the upward portion, and the branch suction pipe immediately after the branch point is provided with the rising portions, and the branch points at the upper ends of these rising portions are provided. Since the height from above is set higher than the static pressure height corresponding to the dynamic pressure of the refrigerating machine oil contained in the refrigerant gas, a part of the refrigerating machine oil flowing upwards with the refrigerant gas in the common suction pipe is branched. After that, it flows into a branch suction pipe that communicates with the compressor that is not operating, but since it cannot go beyond the rising portion, it drops and is sucked into the operating compressor. As a result, since the refrigerating machine oil does not flow into the compressor that is not operating, it is possible to prevent the operating compressor from being poorly lubricated or damaged due to lack of refrigerating machine oil.

[Brief description of drawings]

1 and 2 show an embodiment of the present invention. FIG. 1 is a refrigerant circuit diagram and FIG. 2 is a partially enlarged sectional view of a refrigerant suction pipe. FIGS. 3A and 3B are schematic side views showing modified examples of the refrigerant suction pipe. 4 and 5 show an example of a conventional refrigerant compression heat pump, FIG. 4 is a refrigerant circuit diagram, and FIG. 5 is a partially enlarged sectional view of a refrigerant suction pipe. Compressor …… 1A, 1B, common suction pipe …… 7, upward part …… 21,
Branch point …… 20, branch suction pipe …… 8A, 8B, rising part…
… 22, 23

Claims (1)

[Scope of utility model registration request] 1. One of two compressors that are selectively operated via a branch suction pipe after a gas-phase refrigerant and a liquid-phase refrigeration oil are branched at a low branch through a common suction pipe. In the refrigerant compression heat pump sucked in, the common suction pipe immediately before the branch point is provided with an upward portion, and the branch suction pipe immediately after the branch point is provided with a rising portion, and the upper end of the rising portion is A refrigerant compression heat pump, wherein a height from a branch point is set higher than a static pressure height corresponding to a dynamic pressure of refrigerating machine oil contained in a refrigerant gas.