Control unit for reducing operating noise by suppressing a defined speed range of an electric refrigerant compressor

Abstract

Electronic control unit (4) for reducing the operating noise of an electric refrigerant compressor (1) comprising an electric speed-controlled compressor motor (9) of an air conditioning system in an electrified motor vehicle with a function module (10) such that the control of the compressor motor (9) is masked out in at least one defined speed range (dn) characterized in that, under certain conditions, depending on certain acoustically relevant input information (v, P, TWD), the masking (A) of the defined speed range (dn) can be switched off.

Description

[0001] The invention relates to a control unit for reducing operating noise of an electric refrigerant compressor in an electrified motor vehicle, in which the refrigerant compressor is elastically coupled to an electric drive unit.

[0002] Air conditioning systems in motor vehicles typically have a refrigerant circuit in which the refrigerant is compressed, condensed, expanded, and evaporated. The refrigerant circuit includes a compressor, which draws in cold gaseous refrigerant and compresses it. A condenser is also provided, in which the refrigerant gas is cooled and condenses, releasing heat energy to the environment. In an evaporator, the refrigerant evaporates, absorbing heat energy from the environment.

[0003] Particularly in electric vehicles with at least one purely electric drive unit (especially high-voltage electric motor, also called e-motor for short), the refrigerant compressor is typically operated electrically by speed control of a compressor motor ((low-voltage) electric motor).

[0004] For example, DE 10 2010 008 899 A1 discloses a control unit for controlling a fan in a motor vehicle with an air conditioning system. The air conditioning system comprises an electric refrigerant compressor with an electric compressor motor, which is acoustically noticeable due to its operating noise. Therefore, according to DE 10 2010 008 899 A1, the fan is driven depending on the current power or motor speed of the electric refrigerant compressor in such a way that the operating noise of the electric refrigerant compressor is at least partially masked.

[0005] Further examples of control units for controlling a fan in a motor vehicle are disclosed, for example, in DE 103 36 498 A1, DE 10 2004 027 000 A1, DE 10 2015 218 825 A1, DE 10 2016 206 337 A1, DE 10 2017 107 538 A1, DE 11 2017 000 915 T5, GB 2 255 421 A, US 10 551 086 B2 or EP 3 017 982 B1.

[0006] The disadvantage of this known solution is that the fan emits additional, increased noise, even if this may be less noticeable psychoacoustically.

[0007] The object of the invention is to reduce the acoustic conspicuity of an electric refrigerant compressor without masking it with other disturbing noises.

[0008] This problem is solved by the features of patent claim 1. Advantageous further developments are the subject matter of the dependent patent claims.

[0009] The invention relates to an electronic control unit for reducing the operating noise of an electric refrigerant compressor comprising a compressor motor. The electric refrigerant compressor is part of an air conditioning system of an electrified motor vehicle, which is used both for heating (heat pump operation) and for cooling the vehicle interior. The electric refrigerant compressor is also used for cooling a high-voltage storage unit.

[0010] According to the invention, an electronic control unit for reducing an operating noise of an electric refrigerant compressor of an air conditioning system in an electrified motor vehicle, said compressor motor comprising an electric speed-controlled compressor motor, comprises a functional module which is designed (in particular by means of a corresponding software program and a characteristic curve) in such a way that the control of the compressor motor is suppressed in at least one defined speed range.

[0011] The invention is based on the following considerations: Due to superimposed excitations in the entire vehicle, an acoustically noticeable and sometimes disturbing noise level occurs at a specific controlled speed range of an electric refrigerant compressor ("eKMV"), along with additional vibrations in the vehicle interior. The present invention contributes to a significant reduction in this acoustic disturbance and to the reduction or prevention of vibrations.

[0012] Currently, multi-bearing systems for decoupling acoustic transmission are particularly well known, but these are expensive and complex.

[0013] In particular, the invention proposes suppressing a specific speed range when controlling the compressor motor, preferably via characteristic curve control. In one specific embodiment, for example, the speed range between 19% and 31% of a compressor motor adjustable from 0% to 100% has proven particularly advantageous.

[0014] The operating noise of the electric refrigerant compressor is perceived as more disturbing the more it is amplified by another background noise, such as the rotating noise of the electric motor. This is due to the fact that the operating noise of the electric refrigerant compressor in a hybrid or electric vehicle is a less familiar noise than the generally familiar noises of conventional components in a vehicle with a combustion engine, and is therefore acoustically much more noticeable. This can go so far that the vehicle occupant assumes a vehicle defect based on the noise or vibration of the refrigerant compressor, even though there is actually no defect.

[0015] The invention is based on an electric refrigerant compressor that is acoustically coupled to components that also generate structure-borne sound vibrations in such a way that the noise generated by the refrigerant compressor is sometimes even amplified. In particular, the electric motor and the vehicle body are such components.

[0016] The invention is based on the finding that in at least one defined speed range of the compressor motor, which must be determined empirically beforehand, the noise of the refrigerant compressor is particularly amplified by the excitations of the electric motor. Therefore, the invention proposes that, within the framework of temperature control by the refrigerant compressor, this defined speed range be skipped to control the compressor motor upwards and / or downwards.

[0017] Here, the temperature control is converted into a temperature control; ie a deviation of the actual temperature from the target temperature is permitted until control outside the defined speed range is possible again.

[0018] In an advantageous development of the invention, the temperature deviation during the suspension of temperature control can be at least partially compensated by another temperature-influencing variable. In particular, this variable can be the control signal of a chiller valve and / or a water-cooled condenser (WCC) in the overall thermal management circuit of an electric vehicle.

[0019] To control the compressor motor, the speed to be masked is preferably retrieved from a characteristic curve stored in the control unit (e.g., in the form of a look-up table). The characteristic curve is preferably determined empirically in advance.

[0020] When empirically determining the speed range to be suppressed, acoustic measurements or acoustic simulations are performed to determine the speed range in which the operating noise of the refrigerant compressor is amplified by acoustic excitations from other components. The speed range to be suppressed is thus determined such that a certain volume of the superimposed operating noise occurs, or at least that no amplification of the operating noise occurs due to vibration excitations from other components, in particular the electric motor and the vehicle body.

[0021] Details of the invention are described with reference to the accompanying drawings using an exemplary embodiment. It shows Fig. 1 schematically shows an overview of important components in an electric vehicle that are affected by the invention, Fig. 2 a schematic example of a characteristic curve for suppressing the defined speed range and Fig. 3 the acoustic effect of the invention.

[0022] Fig. 1 schematically shows a section of a possible overall heat management system for an electric vehicle, comprising an electronic control unit 4, a refrigerant compressor 1 of an air conditioning system in a first heat circuit / refrigeration circuit 6, and a chiller 8 in a second heat circuit / refrigeration circuit 7. The heat circuits 6 and 7 pass through a heat exchanger 5. For example, a water-cooled condenser 11 can also be arranged in the heat circuit 6. The refrigerant compressor 1 comprises an electric, speed-controlled compressor motor 9 and is connected, for example, by screws via a holder and comparatively simple bearings 3 to the housing of an electric machine 2. This arrangement can also include sound insulation as an acoustic shell for the refrigerant compressor 1.The holder, the refrigerant compressor 1, the bearings 3, the screws, and the sound insulation are then preferably attached to the electric drive unit via an additional screw connection (not shown in detail). As a result, the refrigerant compressor 1 is acoustically coupled to the electric motor 2 in such a way that the operating noise of the compressor motor 9 is at least within a defined speed range dn (see also . Fig. 2), which is to be determined empirically, is amplified by vibration excitations of the electric motor and / or by other acoustically relevant components (e.g. steering wheel assistance, chassis excitations, etc.).

[0023] According to the invention, an electronic control unit 4 is provided, which can be, for example, the control unit of the air conditioning system or the electric motor 2, and which contains a functional module 10 such that the control of the compressor motor 9 is suppressed in at least one defined speed range dn. This can be achieved by a characteristic curve, as shown in Fig. 2 is shown schematically, are controlled by the function module 10. In Fig. Figure 2 shows a speed characteristic curve of the compressor motor 9, which is generally adjustable between 0% and 100%. According to the invention, the defined speed range dn, here, for example, between 19% and 31%, is avoided and skipped either upwards or downwards. In other words, a speed suppression A occurs.

[0024] In Fig.3, the volume L in [dB] of a noise measured in the vehicle, which is based in particular on the speed-dependent operating noise of the compressor 1, is plotted against the speed n of the compressor motor 9. Such a measurement can be used to empirically determine the defined speed range dn to be masked out.

[0025] Preferably, during the suppression A of the defined speed range dn, the usual temperature control by the compressor motor 9 is suspended, and the resulting deviation of the actual temperature from the target temperature T_soll is at least partially compensated, for example, by the chiller 8 and / or the water-cooled condenser 11. A valve of the chiller 8 can be "digitally" opened or closed to achieve the respective counteraction of a reduced cooling or heating due to the suppression A.

[0026] In an advantageous development of the invention, the masking A can also be deactivated under certain conditions. For this purpose, the control unit 4 can evaluate certain acoustically relevant input information, such as the vehicle speed v, the interior fan power P, and / or the drive type (all-wheel drive FWD or single-axle drive TWD). Such conditions can preferably be the following: - The vehicle speed v is above a first defined threshold S1, whereby the operating noise of the compressor 1 in the vehicle interior is masked by rolling noise from the wheels. - The interior fan power P is above a second defined threshold S2, whereby the operating noise of compressor 1 in the vehicle interior is masked by fan noise. - In a vehicle with which a road-coupled all-wheel drive (FWD) is possible, the vehicle temporarily switches to a single-axle drive (TWD), whereby the electric motor 2, which is acoustically coupled to the compressor 1, is located on the switched-off axle and is thus temporarily switched off.

[0027] The above reduction of the noise of the electric refrigerant compressor thus represents a defined speed masking A in contrast to the prior art, from which only a speed adjustment for masking or for reducing the power of the refrigerant compressor is known.

Claims

[1] Electronic control unit (4) for reducing the operating noise of an electric refrigerant compressor (1) of an air conditioning system in an electrified motor vehicle, comprising an electric speed-controlled compressor motor (9), having a functional module (10) such that the control of the compressor motor (9) is suppressed in at least one defined speed range (dn) characterized by that under certain conditions, depending on certain acoustically relevant input information (v, P, TWD), the suppression (A) of the defined speed range (dn) can be switched off. [2] Electronic control unit (4, 10) according to claim 1, characterized by that the speed range (dn) to be suppressed is determined in such a way that a certain speed-dependent noise level (L) and / or the transmission of vibrations in the vehicle interior is / are prevented. [3] Electronic control unit (4, 10) according to claim 1, characterized by that the speed range (dn) to be suppressed is determined in such a way that at least no amplification of the operating noise occurs due to vibration excitations of another component, in particular the electric motor (2) and the vehicle body. [4] Electronic control unit (4, 10) according to one of the preceding claims, characterized by that during the suppression (A) of the defined speed range (dn) the usual temperature control by the compressor motor (9) is suspended and the resulting deviation of the actual temperature from the target temperature (T_soll) is at least partially compensated by another temperature-influencing variable. [5] Electronic control unit (4, 10) according to the preceding claim, characterized bythat another temperature-influencing variable is the control signal of a chiller (8) and / or the control signal of a water-cooled condenser (11) in the overall heat management (6, 7) of the electric vehicle. [6] Electronic control unit (4, 10) according to claim 1, characterized by that certain conditions for eliminating the masking (A) are as follows: - the vehicle speed (v) is above a first defined threshold (S1) and / or - the interior fan power (P) is above a second defined threshold (S2) and / or - a vehicle capable of road-coupled all-wheel drive (FWD) will temporarily switch to single-axle drive (TWD).

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