Compressor for a heat pump circuit

Abstract

The compressor (1) proposed here for a heat pump circuit has an electric drive configured such that an increased torque is transmitted in the region of a fluid outlet (3) of the compressor (1). Thus, compared to a homogeneous torque application to the shaft of the compressor (1) distributed evenly around the circumference, a larger proportion of the total torque to be transmitted can be introduced in the region of the fluid outlet (3) of the compressor (1). Advantageously, for example, a bending stress on the shaft caused by the increased load in the region of the fluid outlet (3) by the drive can be compensated for.

Description

[0001] The invention relates to a compressor for a heat pump circuit and a heat pump system.

[0002] Heating systems with a heat pump extract heat from an ambient medium (air, water, ground) and make it available for use, for example by transferring it to drinking water as part of hot water preparation or by transferring it to a heating circuit to heat living spaces.

[0003] The heat pump is usually integrated into a heat pump circuit (also known as a refrigerant circuit) that transports the heat energy from the heat pump to at least one consumer, such as a heat exchanger. The refrigerant circuit contains a refrigerant that frequently undergoes a phase change to transfer heat, releasing heat through condensation and absorbing heat through evaporation.

[0004] To ensure a pressure differential for a phase change in the condenser or evaporator, heat pump circuits have a compressor (often also called a compressor). The compressor is essentially responsible for the energy consumption of a heat pump heating system.

[0005] Various types of compressors are known. Heat pump systems frequently use compressors where the compression work is performed by a rotary motion and which have a fluid inlet for an uncompressed fluid and an outlet for a compressed fluid. The fluid inlet and outlet are often located at the circumference of the rotary motion. Such a compressor can, for example, be called a rotary piston compressor.

[0006] However, it has been shown that with the arrangement described above, an inhomogeneous load on the compressor, particularly on the shaft and housing, can occur, since significantly greater forces act in the area of ​​the outlet compared to the fluid inlet. This inhomogeneous load on the compressor reduces its efficiency and also shortens its service life.

[0007] In this context, DE 197 33 147 C1 proposes designing the winding of the electric motor, which is effective for the motor torque, unevenly around its bore circumference, in order to create a pump drive adapted to the load torque and thus free from torque fluctuations. However, adapting the winding of the electric motor adversely increases the manufacturing costs of the electric motor.

[0008] US patent 2017 / 0117762 A1 proposes an electric motor whose inner rotor has a concave circumferential section in which the gap between a stator tooth and the rotor is larger than in the outer circumferential regions. This solution also requires significant structural modifications to the electric motor, resulting in increased manufacturing effort.

[0009] Based on this, the object of the invention is to propose a compressor for a heat pump circuit that at least partially overcomes the disadvantages of the prior art. In particular, service life and efficiency are to be increased without increasing the complexity of the compressor.

[0010] These problems are solved by the features of the independent claims. Further advantageous embodiments of the solution proposed here are specified in the independent claims. It should be noted that the features listed in the dependent claims can be combined with one another in any technologically meaningful way and define further embodiments of the invention. Furthermore, the features specified in the claims are further specified and explained in the description, which also presents further preferred embodiments of the invention.

[0011] A heat pump cycle, in this context, refers to a refrigeration cycle, or at least one that includes a heat pump, for example, for heating a building. The heat pump cycle circulates a refrigerant for heat transfer, with the refrigerant often undergoing a phase change from liquid to gaseous to absorb and release heat. A compressor is typically used in the heat pump cycle.

[0012] The compressor is usually driven by an electric motor. The compressor and electric motor can be connected, for example, via a shaft. The construction of an electric motor is known from the prior art. Typically, several coils are arranged concentrically around a shaft on a stator, and a corresponding number of permanent magnets or coils are located on a rotor. During operation, for example, coils arranged on the stator can be energized with an electric current such that the resulting magnetic field interacts with the permanent magnets on the rotor, thereby transmitting torque to the rotor and generating a rotary motion. The permanent magnets can also be coils, which would then likewise be energized with an electric current. The assignment to the rotor or...The stator can also be reversed, meaning the coils can also be located in the rotor, and permanent magnets or coils can also be in the rotor.

[0013] The compressor proposed here for a heat pump circuit has at least one electric drive comprising coils, which is configured such that an increased torque is transmitted in a circular sector containing a fluid outlet of the compressor, wherein in the circular sector containing the fluid outlet the coils have a denser arrangement than in the other circular sectors of the compressor and / or have a higher power than other coils of the electric drive of the compressor.

[0014] In other words, the electric drive of the compressor is configured (set up or designed) such that, compared to a homogeneous torque application evenly distributed around the circumference of the compressor shaft, a larger proportion of the total torque to be transmitted is introduced in the area of ​​the compressor's fluid outlet. This advantageously allows, for example, the increased load in the outlet area by the drive to compensate for bending stress on the shaft.

[0015] This solution is particularly suitable for compressors in which a fluid inlet and a fluid outlet are arranged in the region of the circumference of a shaft performing the compression work. Preferably, the proposed compressor can be a rotary piston compressor or a multi-cell compressor. According to an alternative embodiment, the compressor can also be a screw compressor, a Roots compressor, or a liquid ring compressor.

[0016] In this compressor, it is particularly advantageous that the rotor is arranged inside and the stator outside. This allows for the advantageous realization of a compressor with reduced installation space requirements.

[0017] The compressor drive comprises several coils. The coils in the area of ​​a fluid outlet of the compressor can be closer together than in other areas of the compressor. This area can be understood here as a circular sector.

[0018] The designation indicating that the coils in the fluid outlet area of ​​the compressor are closer together means, in particular, that more coils per angle (for example, per revolution of a rotary piston in a rotary piston compressor) are arranged in the outlet area. In other words, more coils can be arranged in a circular sector encompassing the fluid outlet than in an equally sized circular sector in another area, such as the fluid inlet.

[0019] When considering the distances between the coils, it is particularly assumed that the coils have a largely identical power output, i.e., they generate a largely identical magnetic field.

[0020] It is understood that the desired effect of an increased torque to be transmitted in the area of ​​the fluid outlet can alternatively or cumulatively also be achieved by using coils of higher power in the area of ​​the fluid outlet.

[0021] According to a preferred embodiment, the density of the arranged coils can be continuously increased (and thus the distance between the coils reduced) starting from the fluid inlet in the direction of rotation of the compressor. Particularly preferably, the density of the coils can be increased proportionally to the pressure increase of the fluid in the compressor. This advantageously results in a particularly homogeneous load and stress distribution in the compressor.

[0022] The area (i.e., the angle or circular sector) containing the fluid outlet in which an increased torque is to be transmitted should encompass the compressor's fluid outlet and, in particular, the area (immediately or adjacent to) the fluid outlet when viewed in the direction of rotation. The size of the circular sector in which an increased torque is to be transmitted can correspond, in particular, to the size of one or two compressor chambers (for example, of a multi-cell compressor).

[0023] According to a preferred embodiment, coils adjacent to the fluid outlet can be positioned around the fluid outlet. In other words, compared to a uniform distribution of coils, the coils in the vicinity of the fluid outlet can be moved closer to it. Preferably, 2 to 6, 2 to 5, 2 to 4, or 3 coils are moved from their position corresponding to a uniform distribution towards the fluid outlet to a (spatially) denser arrangement of coils there.

[0024] Alternatively or cumulatively, in addition to an even distribution of coils across the circular cross-section of the compressor, extra coils can be provided in the fluid outlet area to achieve increased torque transmission in the fluid outlet area.

[0025] According to another preferred embodiment, the compressor drive is a brushless DC motor, which can, for example, ensure long service life with low energy consumption.

[0026] According to a further preferred embodiment, the coils can be arranged in the stator of the compressor drive. Permanent magnets or coils can also be arranged in the rotor.

[0027] Another aspect is the proposal for a heat pump system with a compressor as suggested here, whereby the heat pump system can include a heat pump and a heat pump circuit.

[0028] This document describes a compressor for a heat pump circuit and a heat pump system that at least partially solves the problems described with reference to the state of the art. In particular, the compressor and the heat pump system each contribute to increasing the mechanical stability and durability of a compressor in a heat pump circuit.

[0029] Furthermore, compared to a compressor for a heat pump system, only minor modifications are required, and the complexity of the compressor proposed here has not increased.

[0030] The invention and its technical context are explained in more detail below with reference to the accompanying figure. It should be noted that the invention is not intended to be limited by the exemplary embodiments shown. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the facts illustrated in the figure and combine them with other components and findings from the present description. It should be emphasized that the figure, and especially the depicted dimensions, are only schematic. It shows: Fig. 1: a schematic representation of a compressor proposed here.

[0031] Fig. 1Figure 1 shows a proposed compressor 1 for a heat pump circuit. The compressor 1 can have a drive with a rotor 4 and a stator 6. Coils 5 can be arranged on the stator 6. Permanent magnets 7 can be attached to the rotor 6, with one permanent magnet and one permanent magnet being alternately oriented with their south pole towards the coils 5 and the other with their north pole towards the coils 5.

[0032] In normal operation, the coils 5 are switched by control electronics so that torque is transmitted to the rotor 4. Rotation of the rotor 4 draws in a refrigerant from a fluid inlet 2, compresses it, and expels it through a fluid outlet 3. Due to the eccentric arrangement of the rotor 4 within the compressor housing 9, which forms the stator 6, the volume within a compressor chamber 8 decreases as the rotor 4 rotates in a direction 10. This allows the fluid entering the compressor chamber 8 through the fluid inlet 2 to be moved to a fluid outlet 3 and compressed in the process.

[0033] The proposed compressor 1 can have a denser arrangement 51 of coils 5 in the region of the outlet 3. For this purpose, for example, three coils that are spatially closest to the fluid outlet 3 in an evenly distributed arrangement of coils 5 can be combined to form a dense arrangement 51 in the region of the fluid outlet 3.

[0034] Preferably, a circular sector 13 (circular segment) enclosed by the dense arrangement 51 can be positioned such that at least half, preferably between half and three quarters of the angle of the enclosed circular sector 13, viewed in the direction of rotation 10, lies in front of the fluid outlet 3.

[0035] The denser arrangement 51 advantageously reduces bending stresses on the rotor 4 and, consequently, also reduces loads on the rotor 4 bearings. The resulting improved running characteristics of the compressor 1 can also lead to an improvement in the efficiency of the compressor 1. Reference symbol list

[0036] 1 Compressor 2 Fluid inlet 3 Fluid outlet 4 Rotor 5 Coil 51 Close arrangement of coils 6 Stator 7 Permanent magnet 8 Compressor chamber 9 Compressor housing 10 Direction of rotation 13 Circular sector

Claims

1. Compressor (1) for a heat pump circuit, having at least one electric drive comprising coils (5), characterized in that the electric drive is configured such that an increased torque is transmitted in a circle sector (13) containing a fluid outlet (3) of the compressor (1), wherein the coils (5) in the circle sector (13) containing the fluid outlet (3) have a more compact arrangement (51) than in other circle sectors of the compressor (1) and / or the coils (5) in the circle sector (13) containing the fluid outlet (3) have a higher output than other coils (5) of the electric drive of the compressor (1).

2. Compressor (1) according to any one of the preceding claims, wherein the coils (5) are arranged at least in the rotor (4) or in the stator (6) of the electric drive.

3. Compressor (1) according to any one of the preceding claims, wherein the coils (5) in the circle sector (13) containing the fluid outlet (3) are arranged at a smaller distance from one another than in the case of a uniform distribution of the coils (5).

4. Compressor (1) according to any one of the preceding claims, wherein additional coils (5) are provided in the circle sector (13) containing the fluid outlet (3).

5. Compressor (1) according to any one of the preceding claims, wherein the compressor (1) has an externally arranged stator (6) and an internally arranged rotor (4).

6. Heat pump system, comprising a compressor (1) according to any one of the preceding claims.

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