The invention relates to an air conditioning compressor for air conditioning systems in motor vehicles, wherein the air conditioning compressor comprises a check valve and a pressure control device at the high pressure outlet.
Compressors of this type are known. The integration of the check valve is required to improve the starting behavior of the displacement-adjustable compressor and to safeguard the coupling-free drive of the compressor for the switched-off air conditioning operation. This check valve is installed in the high pressure region of the system and, at least in the case of a pressure gradient counter to the throughput direction of the check valve in the high pressure side, divides the high pressure side into two partial regions.
Furthermore, according to the state of the art, a pressure control valve is integrated on the high pressure side in the air conditioning compressor, the valve being disposed downstream in front of the check valve. This means that in the event of a pressure gradient at the check valve counter to the throughput direction of the check valve, which is to say during a pressure increase in the remaining high pressure region of the air conditioning system, the high pressure cannot be relieved via the pressure control valve.
It is therefore the object of the invention to implement an air conditioning compressor and/or an air conditioning system, which are not associated with these problems.
The task is solved by an air conditioning compressor for air conditioning systems in motor vehicles, wherein the air conditioning compressor comprises a check valve and a pressure control device on the high pressure outlet, for example a pressure control valve or a bursting disk, wherein the pressure control device is disposed downstream behind the check valve and wherein a differential pressure control device is disposed in parallel to the check valve. Preferably an air conditioning compressor is used, wherein the differential pressure control device acts in both flow directions, which is to say both in the flow direction from the air conditioning compressor into the air conditioning system, and also in the opposite flow direction. This has the advantage that even if a check valve is used, pressure control is guaranteed for the entire high pressure region of the air conditioning system upstream and downstream of the check valve.
In addition, an air conditioning compressor is preferred, wherein the differential pressure control device is a valve device, which is to say a device that is reversible and reusable.
Furthermore, an air conditioning compressor is preferred, wherein the differential pressure control device is a bursting disk.
A further air conditioning compressor according to the invention is characterized in that the bursting disk is integrated in the check valve. Also preferred is an air conditioning compressor, wherein the pressure differential for triggering the bursting disk is greater than the pressure differential for the check valve. This has the advantage that first a pressure increase beyond the maximum pressure can act at the compressor outlet via the check valve onto the pressure control valve disposed downstream thereof. Only if the check valve jams or fails will the differential pressure control be triggered and connect the elevated pressure at the compressor outlet to the pressure control valve in the other part of the high pressure line of the air conditioning system.
Furthermore, a compressor is preferred, wherein the differential pressure control device on the high pressure side of the air conditioning system connects the air conditioning compressor and the remaining high pressure part of the air conditioning system, which is to say both system parts, to the actual pressure control valve.
The invention will be explained on the basis of the figures.
FIG. 1 is a schematic illustration of the high pressure region of an air conditioning system, comprising an air conditioning compressor having a differential pressure control device.
FIG. 2 shows the high pressure region of an air conditioning system comprising a differential pressure control valve.
FIG. 3 shows the high pressure region of an air conditioning system comprising a bursting disk integrated in a check valve as the differential pressure control.
FIG. 1 shows the high pressure region of an air conditioning system, including an air conditioning compressor 1. The air conditioning compressor 1 takes in coolant, compresses it, and then pumps it via a check valve 3 into an outlet line 11, where the outer high pressure part of the air conditioning system beings. Starting at the outlet line 11, the coolant first flows via a gas cooler 5, then via an inner heat exchanger 7, until it reaches the expansion valve 9, where the coolant is expanded at lower pressure. The high pressure region of the air conditioning system thus transitions into the low pressure region, which is not described here. The compressor 1 comprises a housing 13, in which both the check valve 3 and a pressure control device 15 and a differential pressure control device 17 are disposed. The check valve 13 is required in order to improve the starting behavior of the displacement-adjustable compressor 1 and to safeguard the coupling-free drive of the compressor 1 for the switched-off air conditioning compressor operation. As a result of the check valve 3, which can have an opening pressure of 2 bar, for example, directly upon starting a certain pressure level builds in the compressor 1, which ensures swiveling of the compressor power unit and therefore immediate operation of the air conditioning compressor 1. Downstream, behind the check valve 3, a pressure control device 15, for example in the form of a pressure control valve or a bursting disk, is disposed, which opens, for example, when a maximum pressure of about 160 bar is exceeded and prevents further increase in pressure. This pressure control device 15 thus also safeguards the maximum pressure of the compressor 1 and the remaining high pressure part of the air conditioning system to the expansion valve 9 by means of the check valve 3. However, in the event that the check valve 3 should jam or fail due to any kind of system malfunction, a differential pressure control device 17 can become active, which, for example at a differential pressure of 10 bar in both directions, connects the air conditioning compressor 1 and the remaining high pressure region of the air conditioning system with each other.
FIG. 2 shows such a differential pressure control device configured as a differential pressure valve in a schematic illustration. In parallel to the check valve 3, a check valve 19 acting in the same flow direction and a check valve 21 acting in the opposite direction are provided. The valves 19 and 21, for example, have an opening pressure of 10 bar, so that in the case of a pressure differential between the air conditioning compressor and the remaining high pressure region 23 of the air conditioning system both system parts can be connected to each other at a pressure differential of 10 bar, and consequently also to the pressure control valve 15. Advantageously, the opening pressure of the differential pressure control device, for example 10 bar, is greater than the differential pressure of the check valve 3 because in normal operation the valve also fulfills the safety function with the pressure control valve 15 disposed downstream thereof, both for the compressor 1 and for the high pressure region 23 of the air conditioning system.
The higher pressure differential is particularly necessary for safeguarding the differential pressure in the event a bursting disk 25 is used within the check valve 29, as is shown in FIG. 3, because the bursting disk 25 is not supposed to be destroyed during normal operation, but instead the check valve 29 with the opening pressure of about 2 bar is required for the starting and swiveling of the compressor 1 and is supposed to connect the compressor 1 to the high pressure region 23 of the air conditioning system. The use of a bursting disk 25 within the piston 31 of the check valve 29 offers the special advantage that no additional space is required for the differential pressure control element because it can be integrated in the existing check valve. During normal operation, the piston 31 of the check valve 29 inside the valve housing 33 is pushed into the valve seat 37 by a helical spring 35, wherein the helical spring 35 keeps the valve 29 closed at a prestressing force up to an opening pressure of about 2 bar. After the check valve 29 is open, the coolant can be conducted from the compressor 1 via the line 39 to the outlet line 11 of the air conditioning compressor into the high pressure region 23 of the air conditioning system. In the event that the pressure differential of, for example, 10 bar on the bursting disk 25 is exceeded in one or the other direction, the bursting disk 25 will break, thereby activating the line 41 between the air conditioning compressor 1 and the high pressure region 23 of the air conditioning system. Due to the differential pressure device in the form of the bursting disk 25, thus both system parts on the high pressure side are connected to the pressure control valve 15, and thereby secured, in the event the check valve 29 jams or fails.
LIST OF REFERENCE NUMERALS
1 Air conditioning compressor
3 Check valve
5 Gas cooler
7 Inner heat exchanger
9 Expansion valve
11 Outlet line
13 Compressor housing
15 Pressure control device
17 Differential pressure control device
19 Check valve
21 Check valve
23 High pressure region of the air conditioning system
25 Bursting disk
29 Check valve
31 Piston of the check valve 29
33 Valve housing
35 Helical spring
37 Valve seat
39 Line to the outlet line 11
41 Line between the air conditioning compressor 1 and the high pressure region 23
Patent Application
20080282716
