Abstract: A method and a control unit for starting a compressor (3) in a refrigeration system (1) further comprising a condenser (2) and an evaporator (4). If an attempt to start-up the compressor (3) is unsuccessful a condenser cooling means, e.g. a fan, is started in order to provide cooling for the condenser (2). Thereby, if the temperature of the condenser is sufficiently high to cause an increased pressure on the condenser side of the compressor (3), cooling is provided for the condenser (2) in order to ensure a reliable start-up of the compressor (3). On the other hand, if the temperature of the condenser (2) is sufficiently low to ensure a reliable start-up of the compressor (3), cooling is not provided, thereby saving power while ensuring reliable start-up of the compressor (3).

Abstract: The invention relates to a cylinder head arrangement for a piston compressor, particularly for a hermetically enclosed refrigerant compressor, with a valve plate, a suction gas channel, a discharge chamber and a retainer element for a discharge valve. It is endeavoured to improve the efficiency of the piston compressor. For this purpose, it is ensured that the suction gas channel and the discharge chamber are arranged on different sides of the retainer element.

Abstract: A method and a control unit (4) for controlling a supply of power to an electrical circuit comprising a switch (3). An output voltage of a first power source (5), which is connected to the circuit, is measured and compared to a predefined threshold voltage. If the measured voltage is smaller than the threshold value it is determined that the switch (3) is in a closed state, and if the voltage is larger than the threshold value it is determined that the switch (3) is in an open state. The supply of power is controlled in accordance with the open/closed state of the switch (3). Preferably, the electrical circuit is connected to a second power source (9) when the switch (3) is in a closed state. Power is conserved while it is ensured that sufficient power is available when needed. The invention is very suitable for supplying power to a lamp (1) positioned inside a refrigeration compartment (2), especially when the system is battery powered.

Abstract: A method and a control unit for controlling a power level being drawn from a power source (26). Based on a determined rate of change of a measured voltage (1) an estimated remaining runtime is calculated. The estimated remaining runtime represents a time where specific run criteria will no longer be fulfilled if the present power level is maintained. The estimated remaining runtime is compared to a threshold value, and in case the estimated remaining runtime is shorter than the threshold value, the power drawn from the power source (26) is decreased. Thereby the runtime for the power source (26) is maximised. This is particularly useful if the power source is a limited power source, such as a battery (26), e.g. for running a compressor (27) for a movable refrigeration system (24). The invention is suitable for automotive applications.

Abstract: The present invention provides to a rotor having a short circuit ring of an electrically conductive material. The short circuit ring has a curved outer surface whereby the eddy-current braking effect on the rotor caused by the stray field from the stator is reduced. The curved surface leads to an improved efficiency of an associated electrical motor. The invention further provides a motor with such a rotor and to the use of a rotor in an electrical motor.

Abstract: A method and a control system for starting a motor (19), in particular a motor (19) for driving a compressor. The rotational speed (24) of the motor (19) is measured and compared to a minimum value. In the case that ?motor (24) is smaller than the minimum value after a predefined time interval has lapsed, the motor (19) is stopped, and the maximum current level to be supplied by the power source (18) is changed, preferably increased, before a new attempt to start the motor (19) is initiated. Preferably, the voltage (22) supplied to an electronic unit (21) is also measured, and in the case that it drops below a minimum voltage level, the motor (19) is stopped, and the maximum current level is changed, preferably decreased, before a new start attempt is initiated. It is possible to adjust the supplied current level in such a way that power is conserved while sufficient lubricated of the moving parts of the compressor is ensured.

Abstract: The invention relates to a rotor for an electric motor, particularly an electric line-start motor, comprising axially accommodating spaces (4 to 6) for conductor rods, and axially extending receiving spaces (10, 11) for permanent magnets (14, 15), which are-designed and located in such a way that they generate a permanent magnet field with a magnet axis (22) and a neutral axis (23). The aim of the invention is to ensure that the rotor runs as regularly as possible during the operation of the electric motor. To this end, the diameter of the rotor along the magnet axis is larger than that along the neutral axis (23).

Abstract: The invention concerns a linear compressor (1), particularly a refrigerant compressor, with a linear motor (4), which comprises an outer stator (18), an inner stator (20) and an armature (22) located in a gap (21) between outer stator (18) and inner stator (20), and a compression unit (3), which has a cylinder (8) and a piston (16) reciprocating in the cylinder (8) and being connected to the armature (22). It is endeavoured to simplify the design of the compressor. For this purpose, the inner stator (20) and the outer stator (18) are held and positioned in relation to each other at both axial ends by means of motor covers (29).

Abstract: The invention concerns a linear compressor (1), particularly a refrigerant compressor, with a first component group comprising a stator (18, 20) of a linear motor (4) and a cylinder (8, 10), a second component group comprising a reciprocating piston (16) and an armature (22) of the linear motor (4) as well as a piston rod (28) connecting the armature (22) to the piston (16), an oil sump in a housing (2) and an oil pump (38), the second component group being movable in relation to the first component group. It is endeavoured to provide a simple design ensuring a lubrication of the linear compressor. For this purpose, the oil pump (38) has a pump housing (40) that is permanently connected to the piston rod (28), the pump housing (40) immersing with at least one suction opening (43; 43a, 43b) into the oil sump (41), the oil pump (38) supplying oil to the inside of the piston rod (28).

Abstract: The invention concerns a linear compressor (1), particularly a refrigerant compressor, with a compression unit (3) having a cylinder (8) and a piston (16) reciprocating in the cylinder (8), and a linear motor (4) having an outer stator (18), an inner stator (20) and an armature (22) located in a gap (21) formed between the outer stator (18) and the inner stator (20), the armature (22) being connected to the piston (16) via a piston rod (28). It is endeavoured to design such a linear compressor in a simple manner with the smallest possible dimensions. For this purpose, it is ensured that the armature (22) is connected to the piston rod (28) inside the axial length of the inner stator (20).

Abstract: The invention concerns a linear compressor, particularly a refrigerant compressor, with a housing (2, 2?) and a compression unit, which comprises a compressor with a piston and a cylinder as well as a linear motor driving the piston in relation to the cylinder along a movement axis, the compression unit (30) being connected to the housing (2) via a spring arrangement (7). It is endeavoured to provide a space saving support of the compression unit (30) in the housing that enables good vibration suppression. For this purpose, the spring arrangement comprises a spring (6, 7), which is curved in the circumferential direction in relation to the movement axis (50), said spring surrounding the compression unit (3-5) on at least a share of its circumference.

Abstract: The invention concerns a linear compressor (1) with a piston (16) reciprocating in a cylinder (8), a linear motor acting upon the piston (16) and a resonance spring arrangement (5) connected with the piston (16). It is endeavoured to reliably avoid damaging the compressor during operation. For this purpose, the resonance spring arrangement (5) has a fixed stop (48) allocated to the upper dead point of the piston (16).

Abstract: A method for starting a battery driven motor, wherein an input voltage is measured continuously. In case the input voltage becomes smaller than a predefined minimum voltage the attempt to start the motor is stopped and the maximum permitted current level to be supplied from the battery to an electronic unit of the motor is lowered before the next attempt. This is repeated until the input voltage is larger than the minimum voltage and the motor is no longer in start-up mode. The method protects the battery from collapsing. The method is suitable for starting battery driven motors for driving compressors. The number of attempted start-up sequences may be counted and on the basis of this it may be determined that the battery is weak or that the wiring is misdimensioned. Furthermore, a control system for controlling starting of a motor.

Abstract: The invention concerns a piston arrangement having a piston with a piston head and a piston skirt with a circumferential surface, and a connecting rod, which is connected with the piston via a ball joint comprising a ball, and penetrated by an oil supply channel, which is connected with a bearing surface of the ball joint.

Abstract: The invention concerns a method for controlling a direct voltage source with a first direct voltage source (2) and a voltage monitoring device (24), which monitors an output voltage of the first direct voltage source (2) and acts upon a control device (31), the control device (31) controlling the working state of the first direct voltage source (2). Further, the invention concerns a voltage supply device (22) with which the method can be used. In this connection it is endeavoured to reduce the risk of an increase in voltage in a circuit with several direct voltage sources. For this purpose, a second direct voltage source (3) produces a voltage change at the voltage monitoring device (24).

Abstract: The invention concerns a piston arrangement having a piston with a piston head and a piston skirt and a connecting rod, which is connected with the piston via a ball joint arrangement comprising a ball, the ball being held in the piston by means of a safety element.

Abstract: The invention concerns a compressor crankshaft (1), particularly a refrigerant compressor crankshaft, with a hollow shaft element (2), a crank pin (3) arranged eccentrically to the shaft element (2) and a transition element (4) between the shaft element (2) and the crank pin (3). It is endeavoured to reduce the manufacturing costs. For this purpose, the shaft element (2) has at least two shaft sections (5, 6) joined in a telescope-like manner, which engage in each other in an overlapping area (7).

Abstract: The invention concerns a stator for a line-start electric motor, with a rotor accommodating chamber, in which a rotor is accommodated to be rotatable, and which has accommodating chambers for conducting rods and accommodating chambers for permanent magnets, and with a stator winding comprising several windings, which, during operation of the line-start electric motor under the influence of the rotor, generate a magnetic field with a main axis. In order to increase the efficiency of the line-start electric motor, the rotor accommodating chamber has no constant inner radius, but, in the area of a vertical to the main axis, has a larger inner radius than in the adjacent areas.

Abstract: The invention concerns a method for mounting a drive shaft (19) of a compressor, particularly a hermetical refrigerant compressor, which has a motor with a stator (1) and a rotor (23), connected with the drive shaft (19) and located in a rotor opening (4) of the stator (1), a first bearing support (8) and a second bearing support (29) being connected with the stator (1), a first bearing (15) for the drive shaft (19) being mounted in the first bearing support (8) and a second bearing (28) for the drive shaft (19) being mounted in the second bearing support (29). It is endeavoured to provide a method for mounting a drive shaft, in which the use of components with relatively large manufacturing tolerances will still result in a good alignment of the drive shaft in relation to the stator. For this purpose, at least the first bearing support (8) is provided with a positioning stop for the first bearing (15) after mounting the first bearing support (8) on the stator (1).

Abstract: The invention relates to a rotor for an electric motor, especially an electric line-start motor, comprising spaces (4 to 7) which receive permanent magnets (10 to 13) and extend in an axial direction, and spaces (20 to 25) that accommodate conductor rods and extend in an axial direction. In order for the rotor to run as regularly as possible, the spaces (20 to 25) accommodating the conductor rods are provided with a substantially elongate cross-section in at least one sector of the rotor while being embodied in a curved manner along the longitudinal axis thereof in said sector when viewed from a cross-sectional perspective.