Method and system for measuring volume of fluid drained from an air conditioning service unit

Patent metadata

Field	Value
Publication number	US-9823001-B2
Application number	US-201514964822-A
Country	US
Kind code	B2
Filing date	Dec 10, 2015
Priority date	Dec 14, 2014
Publication date	Nov 21, 2017
Grant date	Nov 21, 2017

Abstract

An air conditioning service system includes an accumulator defining an accumulator chamber, a pressure transducer operably connected to the accumulator chamber, a drain valve operably connected to the accumulator chamber, and a controller operably connected to the pressure transducer and the drain valve. The controller includes a processor configured to execute program instructions stored in a memory to determine a volume of liquid drained from the accumulator by: determining a volumetric flow rate of liquid through the drain valve by controlling the drain valve with the controller to an open position for a predetermined period of time; detecting an increased rate of pressure reduction while the drain valve is open; and determining an amount of liquid drained through the drain valve based upon the volumetric flow rate and a total time elapsed between opening the drain valve and the increased rate of pressure reduction.

First claim

The invention claimed is:

1. An air conditioning service system comprising:
an accumulator defining an accumulator chamber;
a pressure transducer operably connected to the accumulator chamber;
a drain valve operably connected to the accumulator chamber; and
a controller operably connected to the pressure transducer and the drain valve, the controller including a processor configured to execute program instructions stored in a memory to determine a volume of liquid drained from the accumulator by:
determining a volumetric flow rate of liquid through the drain valve by controlling the drain valve with the controller to an open position for a predetermined period of time,
detecting an increased rate of pressure reduction while the drain valve is controlled to the open position, and
determining an amount of liquid drained through the drain valve based upon the determined volumetric flow rate and a total time elapsed between controlling the drain valve to the open position and the detected increased rate of pressure reduction.

2. The system of claim 1 , wherein the controller is configured to execute the program instructions to determine the volumetric flow rate by:
obtaining a first signal from the pressure transducer associated with a first pressure within the accumulator chamber prior to controlling the drain valve to the open position; and
obtaining a second signal from the pressure transducer associated with a second pressure within the accumulator chamber after the predetermined period of time has elapsed.

3. The system of claim 2 , wherein the controller is configured to execute the program instructions to determine the volumetric flow rate based upon the following equation:

V

2
,
vap

=

P

1
,
vap

⁢

V

1
,
vap

P

2
,
vap

wherein
P 1,vap is the first pressure,
V 1,vap is a first volume of vapor in the accumulator chamber before the drain valve is controlled to an open position,
P 2,vap is the second pressure, and
V 2,vap is a second volume of the vapor in the accumulator chamber associated with the second pressure.

4. The system of claim 3 , wherein the controller is configured to execute the program instructions to determine the volumetric flow rate based upon the following equation:

Q
liq

=

V

2
,
vap

-

V

1
,
vap

t
2

wherein:
t 2 is the predetermined period of time, and
Q liq is the volumetric flow rate.

5. The system of claim 4 , wherein the controller is configured to execute the program instructions to determine the amount of liquid drained through the drain valve based upon the following equation:
V 1,liq =Q liq t T

wherein:
v 1,liq is the amount of liquid drained through the drain valve, and
t T is the total time elapsed between controlling the drain valve to the open position and the detected increased rate of pressure reduction.

6. The system of claim 1 , wherein the controller is configured to execute the program instructions to control the drain valve to a closed position after the detected increased rate of pressure reduction.

7. The system of claim 1 , wherein the predetermined period of time is less than or equal to the total time elapsed between controlling the drain valve to the open position and the detected increased rate of pressure reduction.

8. The system of claim 1 , further comprising:
a first valve operably connected to the accumulator chamber and a source of pressure,
wherein the controller is operably connected to the first valve and is configured to execute the program instructions to control, before determining the volumetric flow rate, the first valve to a first valve open position for a second predetermined time and control the first valve to a first valve closed position after the second predetermined time has elapsed.

9. The system of claim 8 , wherein the source of pressure includes an oil separator filled with compressed refrigerant vapor.

10. The system of claim 1 , wherein the vapor in the accumulator chamber includes a refrigerant and the liquid drained from the accumulator includes an oil.

11. A method of determining a volume of liquid drained from an accumulator chamber defined in an accumulator, comprising:
determining, with a controller, a volumetric flow rate of liquid through a drain valve operably connected to the accumulator chamber by controlling the drain valve to an open position for a predetermined period of time;
detecting, with the controller, an increased rate of pressure reduction while the drain valve is controlled to the open position using a pressure transducer operably connected to the accumulator chamber; and
determining, with the controller, an amount of liquid drained through the drain valve based upon the determined volumetric flow rate and a total time elapsed between controlling the drain valve to the open position and the detected increased rate of pressure reduction.

12. The method of claim 11 , wherein the determining of the volumetric flow rate further comprises:
obtaining a first signal from the pressure transducer associated with a first pressure within the accumulator chamber prior to controlling the drain valve to the open position; and
obtaining a second signal from the pressure transducer associated with a second pressure within the accumulator chamber after the predetermined period of time has elapsed.

13. The method of claim 12 , wherein the determining of the volumetric flow rate is based upon the following equation:

V

2
,
vap

=

P

1
,
vap

⁢

V

1
,
vap

Assignees

• Bosch Automotive Service Solutions Inc
• Bosch Gmbh Robert

Inventors

• Lundberg Dylan M
• Mcmasters Mark W

Classifications

• F25B2345/002

  Collecting refrigerant from a cycle · CPC title

• F25B49/00

  Arrangement or mounting of control or safety devices · CPC title

• G01F1/007

  by measuring the level variations of storage tanks relative to the time · CPC title

• G01F1/34

  by measuring pressure or differential pressure · CPC title

• F25B45/00 Primary

  Arrangements for charging or discharging refrigerant · CPC title