Method for controlling the refrigerant pressure in an ambient heat exchanger of a refrigerant circuit

• US 9,821,632 B2
• Filed: 04/21/2015
• Issued: 11/21/2017
• Est. Priority Date: 10/22/2012
• Status: Active Grant

• Current Assignee: Bayerische Motoren Werke AG
• Original Assignee: Bayerische Motoren Werke AG
• Inventors: Wiedemann, Stefan, Horn, Oliver, Knott, Martin
• Primary Examiner(s): Ali, Mohammad M
• Application Number:
  US14/692,261
• Publication Number:
  US 20150224852A1
• Time in Patent Office: 945 Days
• Field of Search: 62 80, 62 98, 62244
• CPC Class Codes: B60H 1/00785 by the detection of humidity or frost
• CPC Class Codes: B60H 1/00899 Controlling the flow of liquid in a heat pump system controlling the properties of the refrigerant liquid, e.g. pressure or temperature, B60H1/3204
• CPC Class Codes: B60H 1/321 for preventing the freezing of a heat exchanger
• CPC Class Codes: B60H 2001/00961 comprising means for defrosting outside heat exchangers
• CPC Class Codes: B60H 2001/224 automatic operation, e.g. control circuits or methods
• CPC Class Codes: B60H 2001/2271 Heat exchangers, burners, ignition devices
• CPC Class Codes: B60H 2001/2296 integration into fluid/air heat exchangers
• CPC Class Codes: B60H 2001/3245 of air
• CPC Class Codes: B60H 2001/3258 of the air at a condensing unit
• CPC Class Codes: B60H 2001/3261 of the air at an evaporating unit
• CPC Class Codes: B60H 2001/3272 to control the revolving speed of a compressor
• CPC Class Codes: B60H 2001/3277 to control the air flow
• CPC Class Codes: B60H 2001/3282 to control the air flow
• CPC Class Codes: B60H 2001/3285 related to an expansion unit

Abstract

A method of controlling the refrigerant pressure in an ambient heat exchanger of a refrigerant circuit, particularly a heat pump circuit, for vehicles, in which the current temperature and the current humidity of the ambient air is measured, the current dew point temperature of the ambient air is determined from the measured temperature and humidity, and if the ambient air temperature is below 0° C. the refrigerant pressure in the refrigerant circuit is controlled by adjusting the rotational speed of a refrigerant compressor of the refrigerant circuit, the flow cross-section of a controllable expansion element of the refrigerant circuit and/or the ambient air volume flow flowing around or through the ambient heat exchanger, such that the temperature of the ambient heat exchanger is greater than the dew point temperature.

Claims

1. A method of controlling a refrigerant pressure in an ambient heat exchanger of a refrigerant circuit for vehicles, comprising the acts of:

measuring a current ambient air temperature with a temperature sensor;

measuring a current ambient air humidity with a humidity sensor;

determining a current ambient air dew point temperature from the current ambient air temperature and the current ambient air humidity;

if the current ambient air temperature is less than 0°

C., adjusting the refrigerant pressure in the refrigerant circuit such that a temperature of the ambient heat exchanger is greater than the current ambient air dew point temperature by adjusting at least one of

a rotational speed of a refrigerant compressor of the refrigerant circuit,

a flow cross-section of a controllable expansion element of the refrigerant circuit, and

an ambient air volume flow flowing around or through the ambient heat exchanger.

2. The method according to claim 1, wherein the humidity sensor measures a relative moisture of the ambient air.

3. The method according to claim 1, wherein the humidity sensor measures an absolute humidity of the ambient air.

4. The method according to claim 1, wherein the ambient air volume flow is adjusted by controlling at least one of a rotational speed of a fan assigned to the ambient heat exchanger and a position of at least one air guiding element assigned to the ambient heat exchanger.