Linear compressor, cooling system, and household appliance

Abstract

Disclosed is a linear compressor 100' comprising a piston 5', a cylinder component 3' whose cylinder wall 3w' at least partially encompasses the piston 5', and a linear motor 1' configured to linearly reciprocate the cylinder component 3' relative to the piston 5'. Therein, a compression space P' formed between the cylinder component 3' and the piston 5' is augmentable by an inner space of at least one release channel C' running through the cylinder wall 3w' and adapted to be alternatively opened or closed at a periphery of the cylinder component 3'. Further disclosed are a cooling system and a household appliance respectively comprising such linear compressor.

Description

[0001] The present invention concerns a linear compressor. The invention further is directed to a cooling system and a household appliance respectively comprising such linear compressor.

[0002] According to conventional standard construction, a linear compressor typically comprises a piston and a cylinder component which together enclose a compression space at a bottom of the cylinder component. A linear motor is configured to linearly reciprocate the piston and cylinder component relative to each other in a direction of a centre axis of the cylinder component, to vary a volume of the compression space. Therein, a radial diameter of the cylinder space (measured orthogonally to the centre axis) and a piston rest position (at which the compression space is minimised) induce, along with further parameters such as respective spring stiffnesses or masses, a mass flow rate achievable with the linear compressor.

[0003] To increase the mass flow rate, the alternating current driving the linear motor is typically supplemented by a direct current, whereby an asymmetric current is generated. Thereby, however, the efficiency of the whole system is reduced, and the linear motor of the compressor may be caused to overheat.

[0004] It is an object of the present invention to provide an improved linear compressor, an improved cooling system, and an improved household appliance.

[0005] The objects are achieved with a linear compressor according to claim 1, with a cooling system according to claim 7, and with a household appliance according to claim 8. Advantageous embodiments are disclosed in the dependent claims, the description, and the figures.

[0006] A linear compressor according to the present invention comprises a piston and a cylinder component whose cylinder wall at least partially encompasses the piston, wherein a compression space is formed between the cylinder component and the piston. The linear compressor further comprises a linear motor configured to linearly reciprocate the cylinder component relative to the piston. A cylinder wall of the cylinder component exhibits at least one release channel running through the cylinder wall and adapted to alternatively be opened or closed at a periphery (thus, at an outer surface) of the cylinder component. By thus closing the at least one release channel, the compression space can be augmented by an inner space of the at least one release channel.

[0007] Thereby, the present invention facilitates optionally increasing a mass flow rate of the compressor even when driving the linear motor with a symmetric current, thus a without direct current (DC) offset. The thus increased mass flow rate thus can be achieved while avoiding asymmetric current and, therewith, the disadvantages of reduced efficiency and danger of overheating the asymmetric current implies.

[0008] According to advantageous embodiments, the linear compressor according to the present invention comprises at least one control mass which is axially movable along the periphery of the cylinder wall and which is configured to alternatively open or close the at least one release channel by unblocking or covering, respectively, a peripheral mouth of the at least one release channel; as is to be noted, the term "axial" and its derivatives in this document relate to a centre / cylinder axis of the cylinder component.

[0009] The at least one control mass may preferably be supported in axial direction by at least one spring. Such embodiments provide for alternatively closing or opening the at least one release channel with a mechanism of particularly low complexity. In particular, the at least one control mass may be supported, by means of the accordingly tuned spring, so as to automatically open and close, respectively, the at least one release channel responsive to a frequency at which the linear motor reciprocates the cylinder component relative to the piston.

[0010] In particular, the cylinder wall of the cylinder component may advantageously have various release channels running therethrough and adapted to alternatively be opened or closed at a periphery of the cylinder wall, thereby serving to augment the compression space by the respective inner space of the release channels. Thereby, a particularly large extra volume for augmentation of the compression space and thus an especially significant extension of a mass flow rate of the linear compressor may be provided. The various release channels may advantageously be closable by a common control mass being axially movable along the periphery of the cylinder wall. Thereby, a particularly compact and simple mechanism is provided to alternatively augment the compression space by the extra volume of the various release channels.

[0011] The at least one release channel may preferably be inclined to a centre axis of the cylinder component. In particular, following a direction from the cylinder component's centre axis outwards, the at least one release channel may preferably approach a bottom end of the cylinder component. Such embodiments facilitate an advantageous (unaugmented) volume of the compression space in situations in which the at least one release channel is opened at the periphery of the cylinder component, the compression space in this case excluding the inner space of the at least one release channel and being determined by the piston closing the at least one release channel at an inner mouh thereof, i.e., within an inner space of the cylinder component.

[0012] According to advantageous embodiments, the linear compressor is included or configured to be included in a cooling system. A cooling system according to the present invention comprises a linear compressor according to an embodiment of the present invention. In these cases, the linear compressor may in particular be configured to compress a refrigerant within its compression space. In particular, the cooling system may form part of a refrigerator, a freezer, or an air conditioner.

[0013] A household appliance according to the present invention comprises a linear compressor according to an embodiment of the present invention. In particular, the household appliance may comprise a cooling system according to the present invention. As specific examples, the household appliance may be a refrigerator, a freezer, or an air conditioner.

[0014] In what follows, preferred embodiments of the present invention are explained with respect to the accompanying drawings. As is to be understood, the various elements and components are depicted as examples only, may be facultative and / or combined in a manner different than that depicted.

[0015] Shown is schematically in Fig. 1:a longitudinal section of a linear compressor according to the prior art; Fig. 2.a concept of generating an asymmetric current conventionally used for driving a linear compressor in high-power mode; and Fig. 3:a longitudinal section of a linear compressor according to an exemplary embodiment of the present invention

[0016] In Figure 1, a compressor 100 according to the prior art is depicted. The compressor 100 comprises a linear motor 1, a housing 2, a cylinder component 3, springs 4a, 4b elastically supporting the cylinder component 3 in the housing 2, and a piston 5 being stationary to the linear motor 1 and extending into an inner space of the cylinder component 3.

[0017] Therein, Figure 1 shows the compressor 100 in a sectional view along a centre axis X of the cylinder component 3.

[0018] The linear motor 1 comprises a stator with winding 10, a magnet component 20, and a yoke 30 coupled to the magnet component 20 and attached to the cylinder component 3.

[0019] The magnet component 20 and the yoke 30 each have an annular shape and are arranged, coaxial to each other and to a solenoid coil of the stator 10, around the centre axis X of the cylinder component 3.

[0020] The stator 10, the magnet component 20 and the yoke 30 together form a magnetic circuit. In consequence of alternating electric power input to the solenoid coil, a magnetic flux thus is generated and produces a linearly reciprocating motion of the magnet component 20, with the yoke 30 coupled thereto, relative to the stator 10 and in a direction parallel to the centre axis X mentioned above. As a consequence, the cylinder component 3 attached to the yoke 30 is reciprocated, within the housing 2, relative to the piston 5.

[0021] A compression space P is formed between a bottom 3 b of the cylinder component 3 and the piston 5. According to advantageous embodiments, in which the linear compressor 100 forms part of a cooling system, the compression space P may in particular contain a refrigerant (not shown in the figures) which may be compressed, by the movement of the cylinder component 3 relative to the piston 5, before being conveyed, through respective valves, out of the compression space P.

[0022] In the situation depicted in Figure 1, the piston 5 is in a piston rest position in which the piston 5 has a minimal distance d from the bottom 3 b of the cylinder component 3. Accordingly, the compression space P in this situation is compressed as much as possible. The distance d, a diameter D of the cylinder component's 3 inner space and further parameters (such as stiffnesses of the springs 4a, 4b or involved masses, for instance) determine a mass flow rate achievable by the linear compressor 100 when the linear motor 1 is driven with a symmetric alternating current (whose maxima and minima have equal absolute values).

[0023] To increase the mass flow rate (such as, if applicable, in order to increase a cooling power of a cooling system the linear compressor 100 may form part of), the linear motor 1 is typically driven by an asymmetric current applied to the solenoid coil of its stator 10, whereby an offset of the piston's 5 movement is introduced.

[0024] This concept is illustrated in Figure 2 showing the current I as a graph over the time t, wherein a direct current offset I 0 (illustrated in the middle of Figure 2) is added to the symmetric current (illustrated at the left) to generate the asymmetric current (illustrated at the right of Figure 2). As mentioned above, applying such asymmetric current reduces an efficiency of the system and bears the risk of an overheating of the linear compressor 100.

[0025] Figure 3 illustrates a linear compressor 100' according to an embodiment of the present invention. The linear compressor 100' comprises a linear motor 1', a housing 2', a cylinder component 3', springs 4a', 4b', and a piston 5' which are arranged analogous to the respective components of the linear compressor 100 shown in Figure 1 and described above.

[0026] However, contrary to the cylinder component 3 of the conventional linear compressor shown in Figure 1, the cylinder component 3' of the linear compressor 100' according to the exemplary embodiment of the present invention as depicted in Figure 3 forms a plurality of release channels C' respectively running, inclined to the centre axis X, through a cylinder wall 3 w ' of the cylinder component 3'. Therein, following a direction from the centre axis X outwards, the release channels C' approach a bottom 3 b ' of the cylinder component 3'.

[0027] At the periphery of the cylinder component 3', the release channels C' can alternatively be opened or closed by a common annular control mass 6' which is supported by a spring 7' and movable relative to the cylinder component 3' and parallel to the centre axis X thereof. Depending on its position relative to the cylinder component 3', the control mass 6' covers or unblocks a respective peripheral mouth of the release channels C'. Thereby, the compression space P' is augmentable by a respective inner space of the release channels C'.

[0028] In particular, the control mass 6' and the spring 7' are tuned such that, in a first mode (of normal mass flow operation), the release channels C' are mostly opened during compression. Therein, the compression space P' is determined by the volume between the cylinder component 3' and the piston 5' in a situation in which the piston 5 covers the release channels C'.

[0029] However, when a higher mass flow is intended to be generated, a working frequency of the system is changed such that the control mass 6' covers the release channels C' during a compression phase. Thereby, a compressed volume increases, and the mass flow of the compressor is increased even if the current flowing through the motor is symmetric without direct current offset.

[0030] Disclosed is a linear compressor 100' comprising a piston 5', a cylinder component 3' whose cylinder wall 3w' at least partially encompasses the piston 5', and a linear motor 1' configured to linearly reciprocate the cylinder component 3' relative to the piston 5'. Therein, a compression space P' formed between the cylinder component 3' and the piston 5' is augmentable by an inner space of at least one release channel C' running through the cylinder wall 3 w ' and adapted to be alternatively opened or closed at a periphery of the cylinder component 3'.

[0031] Further disclosed are a cooling system and a household appliance respectively comprising such linear compressor.Reference signs

[0032] 1, 1'linear motor 2, 2'housing 3, 3'cylinder component 3 b , 3 b 'bottom of cylinder component 3 w 'cylinder wall of cylinder component 4a, 4b, 4a', 4b'springs 5, 5'piston 6'control mass 7'spring 10stator 20magnet component 30yoke 100, 100'linear compressor C'release channel dminimal distance of piston and bottom of cylinder component Dinner diameter of cylinder component P, P'compression space Xcentre axis

Claims

1. Linear compressor (100') comprising - a piston (5'), - a cylinder component (3') whose cylinder wall (3w') at least partially encompasses the piston (5'), and - a linear motor (1') configured to linearly reciprocate the cylinder component (3') relative to the piston (5'), wherein a compression space (P') formed between the cylinder component (3') and the piston (5') is augmentable by an inner space of at least one release channel (C') running through the cylinder wall (3w') and adapted to be alternatively opened or closed at a periphery of the cylinder component (3').

2. Linear compressor according to claim 1 further comprising at least one control mass (6') which is axially movable along the periphery of the cylinder wall (3w') to alternatively open or close the at least one release channel (C') by unblocking or covering, respectively, a peripheral mouth of the at least one release channel (C').

3. Linear compressor according to claim 2, wherein the at least one control mass (6') is axially supported by at least one spring (7').

4. Linear compressor according to one of claims 2 or 3, wherein the at least one control mass (6') is adapted to commonly release or cover a respective mouth of various release channels (C') running through the cylinder wall (3w').

5. Linear compressor according to one of the preceding claims, wherein the at least one release channel (C') is inclined to a centre axis (X) of the cylinder component (3').

6. Linear compressor according to claim 5, wherein following a direction from the centre axis (X) outwards, the at least one release channel (C') approaches a bottom (3b') of the cylinder component.

7. Cooling system comprising a linear compressor (100') according to one of the preceding claims.

8. Household appliance comprising a linear compressor (100') according to one of claims 1 to 6.

9. Household appliance according to claim 8, which is a refrigerator, a freezer, or an air conditioner.

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