WO2007098995A1

WO2007098995A1 - Linear drive and linear compressor with adaptable output

Info

Publication number: WO2007098995A1
Application number: PCT/EP2007/050597
Authority: WO
Inventors: Johannes Reinschke
Original assignee: BSH Bosch und Siemens Hausgeräte GmbH
Priority date: 2006-02-28
Filing date: 2007-01-22
Publication date: 2007-09-07
Also published as: EP1991782A1; DE102006009256A1; CN101395371A; US20090304525A1; RU2008136733A; RU2435072C2

Abstract

The invention relates to an apparatus (1) comprising a linear drive (2) which has a stator (4) and a rotor (5) movable in a reciprocating manner therein along a drive axis (9) between a first (11) and a second (12) rotor reversal point about a rotor zero position (13), and/or comprising a linear compressor (3) which has a piston housing (7) and a compressor piston (6) which is movable in a reciprocating manner therein along a piston axis (8) and a first (21) and a second (22) piston reversal point about a piston zero position (23) and can be driven by the linear drive (2), wherein either the rotor zero position (13) or the piston zero position (23) is adjustable and/or at least one spring element (14, 15) acts on the rotor (5) or on the compressor piston (6), the length of which can be varied, in particular shortened, and/or the spring constant of which can be changed, in particular increased; and a method for cooling commodities (27) or for compressing a fluid (18). The invention is distinguished by the fact that adaptation of the output delivered by the apparatus has no substantial effect on the electromechanical efficiency of the apparatus, as a result of which a linear drive (2) and a linear compressor (3) can be constructed in an especially cost-effective manner, since the diversity of the products can be considerably reduced.

Description

Linear drive and linear compressor with adjustable performance

The invention relates to a device with a linear drive, which has a stator and a rotor along a drive axis between a first and a second rotor inversion point about a rotor zero position reciprocally movable rotor, and / or with a linear compressor, a piston housing and a along a Piston axis between a first and a second piston reversal point about a piston zero position reciprocally movable, drivable by the linear drive compressor piston, and a method for cooling a product and / or for compressing a fluid.

Currently, linear compressors for household refrigerators, such. As refrigerators and / or freezers or air conditioning systems developed. Such compressors are needed in different performance classes, eg. For example, with 7 cooling capacities of 40 W, 70 W, 80 W, 100 W, 120 W, 140 W and 160 W. Here, the compressors for the various power classes are designed so that they achieve optimum efficiency for the respective cooling capacity. In known linear compressors, a special design of the linear compressor for the individual cooling capacities is required. Such a design is complex, expensive and considerably increases the spectrum of required components and spare parts.

It is therefore an object of the present invention to provide a linear drive and a linear compressor, which is comparatively easy to manufacture in series and operates reliably and energy-efficient. In addition, it is an object to provide a method for cooling goods or for compressing a fluid, which can be used for different cooling capacities and works reliably and energy-efficiently.

This object is achieved by the device and by the method as indicated in the independent claims. Further advantageous embodiments and developments, which can be applied individually or combined with each other, are the subject of the respective dependent claims.

The device according to the invention with a linear drive, which has a stator and a drive shaft between a first and a second runner along a drive axis. has a reciprocating point about a rotor back and forth movable rotor, and / or with a linear compressor having a piston housing and therein along a piston axis between a first and a second piston reversal point about a piston zero position reciprocally movable, driven by the linear drive compressor piston sees in a first variant, that the rotor zero position or the piston zero position is adjustable.

The device according to the invention with a linear drive, which has a stator and a rotor movable back and forth along a drive axis between a first and a second rotor inversion about a rotor zero position, and / or with a linear compressor comprising a piston housing and a piston axis along it In a second variant, at least one spring element acts on the rotor or on the compressor piston, the length of which is changed, in particular shortened, being a first and a second piston reversal point around a piston zero position movable reciprocally movable, driven by the linear drive compressor piston can.

The device according to the invention with a linear drive, which has a stator and a rotor movable back and forth along a drive axis between a first and a second rotor inversion about a rotor zero position, and / or with a linear compressor comprising a piston housing and a piston axis along it In a third variant, at least one spring element acts on the rotor or on the compressor piston, whose spring constant can be changed or increased, for example, in a third variant, a first and a second piston reversal point about a piston zero position movable reciprocally movable, driven by the linear drive compressor piston ,

The device according to the invention with a linear drive, which has a stator and a rotor movable back and forth along a drive axis between a first and a second rotor inversion about a rotor zero position, and / or with a linear compressor comprising a piston housing and a piston axis along it A first and a second piston reversal point about a piston zero position movable back and forth, can be driven by the linear drive compressor piston, provides in a fourth variant, that from the linear compressor or from the linear compressor in particular from a normalized nominal power value of 1 to 0.6, preferably from a normalized nominal power value of 1 to 0.5, the electromechanical efficiency in the change of the mechanical power always being greater than 60%, in particular greater than 70%, preferably greater than 80%.

The device according to the invention with a linear drive, which has a stator and a rotor movable back and forth along a drive axis between a first and a second rotor inversion about a rotor zero position, and / or with a linear compressor comprising a piston housing and a piston axis along it In a fifth variant of the invention, in a fifth variant of the invention, the electromechanical efficiency with a reduction of the mechanical power for a normalized nominal power value from 1 to 0.6 on average, provides for a first and a second piston reversal point about a piston zero position reciprocating, drivable by the linear drive compressor piston with a pitch <0.8, in particular with a pitch <0.5, preferably with a pitch <0.2, particularly preferably with a pitch <0.1 falls.

The five variants of the invention are juxtaposed, but can be combined with one another in any desired manner. With the device according to the invention in the various variants, it is possible to build one or two constructive different types of linear or linear compressors that are hardware and software so adjustable that hereby all power classes over a factor of 4 in performance, for example between 40 W and 160 W, can be covered. The spectrum of instrument parts needed to cover all performance classes is significantly reduced overall, reducing the cost of a linear compressor for a single performance class.

The linear drive according to the invention is particularly suitable and determined for a linear compressor.

While in known linear drives or linear compressors a change in the control of the linear drive or of the linear compressor required for the change of a cooling capacity leads to a considerable reduction of the electromechanical effect. - A -

grades led, the device of the invention works in the specified variants even with change or adaptation of the cooling capacity with a high efficiency.

The rotor or the compressor piston performs a reciprocating motion between two respective reversal points at which the direction of movement changes. In this case, the rotor or the compressor piston oscillates about a respective zero position. The respective zero positions are predetermined by the mechanical vibration system of the linear drive or the linear compressor. In a symmetrical design of the linear drive or the linear compressor, the zero position is located centrally between the two reversal points.

If a cooling capacity level is changed, the rotor or the compressor piston usually performs a different stroke.

When reducing the cooling capacity of a linear compressor, for example, the amplitude of a piston stroke is reduced. In order to operate the linear compressor particularly efficiently, it is advantageous to reduce a dead volume in the piston housing. If the linear compressor operates at a lower piston stroke, its efficiency is reduced, either by increasing the dead volume or by reducing the electro-mechanical motor efficiency.

It has been recognized that a deterioration of the electromechanical motor efficiency when changing the piston stroke and maintaining the lowest possible dead volume in known devices has its origin in that in the changed second reversal point, a spring is less biased, so it contains less energy, so that a missing spring (-energie) must be additionally supplied electrically in the compression half-wave. An unequal between compression and expansion half-wave electrical energy supply deteriorates the electromagnetic efficiency. In addition, further adverse effects may occur: If the second reversal point is raised so far that the spring energy at the second reversal point is less than the sum of spring energy in the first reversal point and residual gas energy (due to the non-vanishing dead volume at the first reversal point), must be electrically braked during the expansion half-wave become. The electric Braking leads to a further loss of energy and a reduction in the efficiency of the linear compressor or the linear drive.

By adapting the rotor zero position or by adjusting the piston zero position, the mechanical system is adapted to the changed conditions and the linear drive or the linear compressor can continue to work despite their power class close to their maximum efficiency.

The change he rotor zero or the piston zero position can be effected by changing the length of a spring element used. Under spring elements are all springs, such. As membrane or coil springs and corresponding composite spring packages to understand. By changing the length of the spring element, the piston zero position can be shifted so that the linear drive or the linear compressor can work with high efficiency.

However, by changing the length of the spring element or the spring constant of the spring element, without changing the rotor zero position or the piston zero position, the natural frequency of the mechanical system can be shifted so much that the linear drive or the linear compressor operates at a correspondingly changed frequency. whereby also the performance of the linear drive or the linear compressor can be influenced.

Depending on the design of the linear compressor or the linear drive, it may be cheaper to change the length of the spring element or the spring strength of the spring element. For this purpose, on the one hand, the spring can be shortened as such, d. H. The length of the spring in the relaxed state is changed by, for example, changing the suspension of the spring, but the spring can also be compressed more, which changes the length of the spring element in the installed state in the linear compressor or in the linear drive. A change in the spring constant can be effected for example by adding reinforcing elements to the spring. The shortening of the spring can be irreversible, for example, to cut off a part of the spring.

By changing the rotor zero or the piston zero position and / or by changing the length of the spring element and / or by changing the spring constant the spring element, the linear drive or linear compressor can be operated at its optimum distribution point. In this way it can be ensured that the electro-mechanical efficiency is always greater than 80% given a change in the mechanical power from a normalized nominal power value of 1 to 0.6. The nominal power value of a linear compressor or a linear drive corresponds to the maximum power output of the linear compressor or the linear drive provided in continuous operation. The achievable mechanical power is related to this nominal power value.

For example, if a linear compressor is designed for 32 W, a normalized nominal power value of 0.6 means that the linear compressor operates at 0.6 x 32 = 19.2 W. The electromechanical efficiency is defined by

⁷ I ₁ 'I Imech

P mech + P ohm

where P _{mech is} the mechanical power performed on the linear compressor and P _{ohm is} the ohmic power dissipation. The electromechanical efficiency thus represented merely approximates the actual electromechanical efficiency, since it does not take account of the electronics losses for position measurement, processor and drive coil current regulator (Mosfett bridge).

The electromechanical efficiency advantageously falls with a reduction of the mechanical power from a normalized nominal power value of 1 to 0.6 on average with a slope <0.1. With a suitable dimensioning of the spring elements, the moving masses and the reversal points or zero positions, the electromechanical efficiency can essentially be maintained despite changing the mechanical power performed by the linear drive or the linear compressor. This is in contrast to known solutions, in which a significantly reduced electro-mechanical efficiency had to be accepted if the delivered mechanical power was reduced by more than 10%.

By the invention, an energy-saving, efficient and reliable operation of the linear drive or the linear compressor is also possible when the power level the linear drive or the linear compressor is changed. As a result, the production of a set of different linear compressors or linear drives for different power levels is simplified and cheaper. With the specified linear compressor or linear drive, it is possible to cover all power levels, in particular all refrigeration capacity classes of linear compressors from 40 W to 160 W, with only two structurally different linear compressors or linear drives. For this purpose, a linear compressor or a linear drive to a maximum power level, z. B. a maximum cooling capacity of 160 W, designed and can be lowered in half, for example, to about 80 W cooling capacity, without structural changes to the linear compressor are required. A second linear compressor or a second linear drive is designed for the maximum cooling capacity of 80 W and can be lowered to approx. 40 W cooling capacity. Even if such a linear compressor operated below the maximum power stage or its electrical design (eg the drive coils or the drive coil current circuit) is somewhat oversized, the savings effects due to the drastically reduced variety and, consequently, the increase in the product unit number are advantageous.

In addition, the possibility of adapting the zero positions, the spring constants or the spring lengths can also be used to finely tune the mechanical vibration system at the usual manufacturing tolerances, in particular to adjust the natural frequency precisely. A method for tuning the natural frequency of a linear drive, and / or with a linear compressor, is particularly advantageous.

In one embodiment of the invention, a drive coil, which acts with an electromagnetic force on the rotor or on the compressor piston, and a means for controlling the drive coil is provided, wherein the means of the position of the first rotor reversal point and the first piston reversal point is adjustable.

With the aid of the means, the control side, e.g. on the software side, the position of the first rotor reversal point or the first piston reversal point are adjusted.

The drive of the drive coil can also be carried out in the context of a control in which sensors are provided which detect the position of the rotor or the position of the compressor piston and based on the position information a corresponding Actuation of the drive coil is effected. The reciprocating motion of the rotor or the compressor piston can thus be both controlled and regulated.

In a particularly advantageous embodiment, the rotor zero position relative to the first rotor reversal point or the piston zero position relative to the first piston reversal point is adjustable so that the rotor or the compressor piston can perform a substantially symmetrical oscillation to the adjusted zero position when changing the reversal point.

By adapting the zero positions to the respective changed reversal points, the control or regulation-related desired movement can be made to coincide with the natural movement of the physical vibration system. As a result, a high efficiency of the linear compressor or the linear drive is achieved.

By adjusting the natural frequency of the mechanical vibration system, the output power can be influenced and the efficiency can be optimized.

In a particularly advantageous embodiment of the invention, the rotor and / or the compressor piston between a working-side spring element and a spring element opposite thereto are clamped.

Working side here means the side at which the work is to be done. In a piston rod which connects the linear drive with the linear compressor, the working side points towards the compressor piston. The opposite side points to the runner. By clamping a particularly stable reciprocating motion is effected.

In a special embodiment of the invention, the spring elements have different spring constants and / or different spring lengths.

The spring elements are advantageously for each position of the rotor or the compressor piston under tension and have in the clamped state to a length which is less than 95% of the unpressed spring element length, in particular less than 90% of the unpressed spring element length. This ensures that both spring elements For each runner or compressor piston position elements have a state of stress, which also serves a stable reciprocating motion.

In order to prevent impact, it is advantageous that the spring elements for each position of the rotor or the compressor piston have a length which is greater than 40% unpressed spring element length, in particular greater than 50% of the unpressed spring element length. This avoids that the spring elements are never compressed so far that touch the individual spring connections. As a result, a hard striking is effectively avoided.

In a special embodiment of the invention, at least one of the following features (α1) to (α6) is fulfilled.

(α1) the working-side spring element (14) has a spring constant in the range of 1 N / mm to 5 N / mm, in particular in the range of 1, 8 N / mm to 3.6 N / mm, preferably in the range of 2.3 N / mm to 2.9 N / mm, on;

(α2) The opposing spring element (15) has a spring constant in the range of 4 N / mm to 12 N / mm, in particular in the range of 6.5 N / mm to 9.5 N / mm, preferably in the range of 7.5 N / mm to 8.5 N / mm, on;

(α3) the working-side spring element (14) has an unpressed spring length in the range of 40 mm to 60 mm, in particular in the range of 48 mm to 62 mm;

(α4) the opposite spring element (15) has an unpressed spring length in the range of 25 mm to 40 mm, in particular in the range of 30 mm to 36 mm;

(α5) the stroke of the rotor (5) or of the compressor piston (6) is between 10 mm and 30 mm, in particular between 12 mm and 20 mm;

(α6) the first rotor turning point (11) or the first piston turning point (21) can be displaced by at least 5 mm, in particular by at least 10 mm, preferably by 20 mm.

A combination of the features (α1) to (α6) is particularly advantageous, but the individual features can be used individually or combined with each other as desired. Furthermore, it is advantageous if the second rotor inversion point and / or the second piston inversion point are fixed. As a result, it can be ensured, for example in the case of linear compressors, that the dead volume in the piston housing is kept as low as possible, which improves the efficiency of the linear compressor.

The device according to the invention can be designed as a cooling device, in particular as a refrigerator and / or freezer or as an air conditioner.

Although the different variants of the invention have been discussed separately above, the variants can also be combined with one another as desired. The variants are partially overlapping, partially overlapping next to each other.

The inventive method for cooling a product and / or for compressing a fluid uses the device according to the invention. Due to the high efficiency of the linear drive or the linear compressor, the high reliability and energy efficiency, goods can be cooled quickly, reliably and energy-efficiently or a fluid can be compressed reliably and efficiently, even when it is necessary to work with different power levels.

Further advantageous details and special features will be explained in more detail with reference to the following drawing, which is not intended to limit the present invention but merely to illustrate it by way of example.

They show schematically:

1 shows a device according to the invention in a sectional view.

FIG. 2 shows a refrigerator with a device according to FIG. 1; FIG.

Fig. 3 is a graph in which the electromechanical efficiency of a device according to the invention and a known device against a power output caused thereby applied. 1 shows a device 1 according to the invention in a sectional view with a linear drive 2 and a linear compressor 3. The linear drive 2 has a stator 4, in which a rotor 5 moves back and forth along a drive axis 9. The rotor 5 is driven by means of a drive coil 16, which is aufschlagt with a drive coil current from a means 17 for driving the drive coil 16. The rotor 5 oscillates between a first rotor turning point 1 1 and a second rotor turning point 12 and passes through a rotor zero position 13. The movement of the rotor 5 is detected by means of a position sensor 25, which passes the position information to the means 17 for driving the drive coil 16, so that a total of a control loop for the movement of the rotor 5 is realized.

The linear compressor 3 has a piston housing 7, in which a compressor piston 6 oscillates back and forth along a piston axis 8 between a first piston reversal point 21 and a second piston reversal point. During its reciprocation, the compressor piston 6 compresses a fluid 18, which is sucked in via a suction port 18 and expelled via a pressure port 29. The suction and ejection of the fluid 18 is switched by means of a valve plate 30. The compressor piston is mounted without contact in the piston housings 7 through a housing wall 20 having openings 19. With the aid of a supply 31, fluid 18 is forced through the openings 19, so that a gas cushion between the housing wall 20 and the compressor piston 6 is constructed, whereby a gas pressure bearing is effected.

The rotor 5 is connected to the compressor piston 6 via a piston rod 24, which has two couplings 26 for receiving bending forces. The zero positions 13, 23 are defined by the arrangement of spring elements 14, 15. The compressor piston 6 is clamped between a working-side spring element 14 and a spring element 15 opposite thereto. The working-side spring element has a length L1 and the opposite spring element 15 has a length L2. The unpressed spring length of the working-side spring element is 59 mm. The unpressed spring length of the opposite spring element 15 is 33 mm. The zero positions 13, 23 can be adjusted by means of an adjusting means 34. The linear compressor operates at a nominal power value of 80 W. If the nominal power value is to be reduced to 40 W, the spring elements 14, 15 are compressed by the adjusting means 34 and the drive of the drive coils is adapted by the means 17, so that the driving vibration on the coil 16 approximately coincides with the natural physical movement. As a result, braking of the linear drive 2 is avoided and a particularly high efficiency is achieved even when the linear compressor 3 is operated at 40 W.

2 shows a refrigerator 10 with a device 1 according to the invention, with which goods 27 can be cooled rapidly, efficiently and energy-efficiently. For a product range of 7 refrigerators with different power levels from 40 W to 160 W, only two different linear compressor designs are required, which reduces the production costs of a single refrigerator. Due to the high efficiency, an efficient and energy-saving cooling of the goods 27 is possible.

3 shows the electromechanical efficiency of the linear compressor according to the invention (see curve 33) and the efficiency for a known linear compressor (see curve 32) as a function of the respective power output by the linear compressors. The electromagnetic efficiency is defined as

p mech lellmech p _ι D mech ohn

The power delivered is normalized to the nominal power, i. the maximum achievable in continuous operation of the refrigerator power. It can be seen that in known linear compressors, the efficiency depends substantially linearly on the power output, while in the linear compressor according to the invention the electromagnetic efficiency for output powers of 100% to 50% remains substantially constant.

The invention relates to a device 1 with a linear drive 2, which has a stator 4 and a therein along a drive axis 9 between a first 1 1 and a second 12 rotor inversion point about a rotor zero position 13 back and forth movable rotor 5, and / or with a linear compressor 3, which has a piston housing 7 and therein along a piston axis 8 and a first 21 and a second piston reversal point about a piston zero position 23 back and forth, driven by the linear drive 2 compressor piston 6, wherein either the rotor zero position 13 and the Piston zero position 23 is adjustable and / or at least one spring element 14, 15 acts on the rotor 5 and on the compressor piston 6 whose length changed, in particular can be shortened, and / or changed its spring constant, in particular can be increased; and a method for cooling goods 27 and for compressing a fluid 18, respectively.

The invention is characterized in that an adaptation of the output from the device power has no significant effect on the electromechanical efficiency of the device, whereby a linear drive 2 and a linear compressor 3 can be built particularly cost, since the variety of component parts can be significantly reduced ,

Bezugszeichenhste

contraption

linear actuator

linear compressor

stator

runner

pistons compressor

piston housing

piston axis

drive axle

Refrigeration device first rotor reversal point second rotor reversal point

Runner zero position work side spring element opposite spring element

drive coil

Means for driving the drive coil 16

fluid

openings

Housing wall first piston reversal point second piston reversal point

Piston zero position

piston rod

position sensor

clutch

Would

suction

pressure connection

valve plate

feed

Efficiency without zero position adjustment 33 Efficiency with zero position adjustment

34 adjusting means

L1 length of the working-side spring element 14

L2 length of the opposite spring element 15th

Claims

claims

1. A device (1) with a linear drive (2), a stator (4) and one therein along a drive axis (9) between a first (11) and a second (12) rotor reversal point about a rotor zero position (13) back and forth movable rotor (5), and / or with a linear compressor (3) having a piston housing (7) and therein along a piston axis (8) between a first (21) and a second (22) piston reversal point about a piston zero position (23 ) to and fro, from the linear drive (2) drivable compressor piston (6), characterized in that the rotor zero position (13) and the piston zero position (23) is adjustable.

2. A device (1) with a linear drive (2), a stator (4) and one therein along a drive axis (9) between a first (11) and a second (12) rotor inversion point about a rotor zero position (13) back and forth movable rotor (5), and / or with a linear compressor (3) having a piston housing (7) and therein along a piston axis (8) between a first (21) and a second (22) piston reversal point about a piston zero position (23 ) has reciprocating, of the linear drive (2) drivable compressor piston (6), characterized in that at least one spring element (14, 15) on the rotor (5) or on the compressor piston (6) acts whose length ( L1, L2), in particular shortened, can be and / or its spring constant changed, in particular increased, can be.

3. Device (1) with a linear drive (2), which has a stator (4) and a drive shaft (9) arranged therein between a first (11) and a second (12) running 5), and / or with a linear compressor (3), which has a piston housing (7) and a piston axis (8) between a first (21) and a piston axis (8) second (22) piston reversal point about a piston zero position (23) reciprocally movable, from the linear drive (2) drivable compressor piston (6), characterized in that by the linear compressor (3) and the linear drive (2) verrichtbare mechanical power reduced can be, in particular from a normalized nominal power value of 1 to 0.6, preferably from a normalized nominal power value of 1 to 0.5, the electromechanical efficiency in the change of mechanical power always greater than 60%, in particular greater than 70%, preferably greater than 80%, and / or wherein the electromechanical efficiency with reduction of mechanical power from a normalized nominal power value v on 1 to 0.6 on average with a slope less than 0.8, in particular with a slope less than 0.5, preferably with a slope less than 0.2, particularly preferably with a slope less than 0.1 falls.

4. Device (1) according to claim 1, 2 or 3, characterized in that a drive coil (16) which acts with an electromagnetic force on the rotor (5) or on the compressor piston (6), and a means (17 ) are provided for controlling the drive coil (16), wherein the means (17), the position of the first rotor inversion point (1 1) and the first piston reversal point (21) is adjustable.

5. Device (1) according to one of the preceding claims, characterized in that the rotor zero position (13) relative to the first rotor turning point (1 1) or the piston zero position (23) relative to the first piston reversal point (21) is adjustable such that the rotor (5) or the compressor piston (6) upon change of the reversal point (1 1, 21) can perform a substantially symmetrical vibration about the adjusted zero position (13, 23).

6. Device (1) according to one of the preceding claims, characterized in that the rotor (5) and / or the compressor piston (6) is clamped between a working side spring element (14) and a spring element (15) opposite thereto.

7. Device (1) according to claim 6, characterized in that the spring elements (14, 15) have different spring constants and / or different spring lengths (L1, L2).

8. Device (1) according to claim 6 or 7, characterized in that the spring elements (14, 15) for each position of the rotor (5) and the compressor piston (6) have a length which is less than 95% of the unpressed spring element length , in particular less than 90% of the unpressed spring element length.

9. Device (1) according to claim 6, 7 or 8, characterized in that the spring elements (14, 15) for each position of the rotor (5) and the compressor piston (6) has a length (L1, L2), the greater than 40% of the unpressed spring element length, in particular greater than 50% of the unpressed spring element length.

10. Device (1) according to one of claims 6 to 9, characterized by at least one of the following features (α1) to (α6):

(α4) the opposite spring element (15) has an unpressed spring length in the range of 25 mm to 40 mm, in particular in the range of 30 mm to 36 mm; (α5) the stroke of the rotor (5) or of the compressor piston (6) is between 10 mm and 30 mm, in particular between 12 mm and 20 mm;

(a6) the first rotor inversion point (11) or the first piston inversion point (21) can be displaced by at least 5 mm, in particular by at least 10 mm, preferably by 20 mm.

1 1. Device (1) according to one of the preceding claims, characterized in that the second rotor reversal point (12) and / or the second piston reversal point (22) is fixed.

12. Device (1) according to one of the preceding claims, characterized in that it is designed as a cooling device (20), in particular as a refrigerator and / or freezer or as air conditioning.

13. Device (1) according to claim 1 in conjunction with one of claims 2 to 12 comprising the features of claim 2 and / or claim 3.

14. A method for cooling a product (17) and / or compressing a fluid (18), characterized in that the method uses a device (1) according to one of claims 1 to 13.