ES2981313T3 - Semi-hermetic refrigerant compressor - Google Patents

Abstract

The invention relates to a semi-hermetic refrigerant compressor comprising a reciprocating compressor, an electric motor, a complete housing having a motor housing section for the electric motor and a compressor housing section for the reciprocating compressor, a suction-side refrigerant circuit leading from a suction connection on the complete housing to an inlet chamber of the reciprocating compressor, and a pressure-side refrigerant circuit leading from an outlet chamber of the reciprocating compressor to a pressure connection on the complete housing. The aim of the invention is to improve such a refrigerant compressor so that it operates more efficiently. This is achieved in that the electric motor is designed as a synchronous motor, the rotor of which is equipped with permanent magnets for synchronous operation of the electric motor and a squirrel cage for starting the electric motor in asynchronous operation. (Automatic translation with Google Translate, no legal value)

Description

DESCRIPTION

Semi-hermetic refrigerant compressor

The invention relates to a refrigerant compressor, which comprises a reciprocating compressor and an electric motor, a general housing, a suction-side refrigerant path leading from a suction connection in the general housing to an inlet chamber of the reciprocating compressor, and a pressure-side refrigerant path leading from an outlet chamber of the reciprocating compressor to a pressure connection in the general housing, wherein the electric motor is designed as a synchronous motor, in whose rotor permanent magnets for synchronous operation of the electric motor and a short-circuit cage for starting the electric motor in asynchronous operation are arranged, the permanent magnets extending parallel to a rotor axis of the rotor, the permanent magnets being designed as plate bodies whose flat sides extend in a longitudinal direction and a transverse direction running transversely to the longitudinal direction, wherein the permanent magnets designed as plate bodies have a different magnetic polarity on their flat sides opposite each other, of which one is oriented towards the rotor axis and the other is oriented opposite to the rotor axis.

Refrigerant compressors with the above-mentioned characteristics are known from US 6,547,538 B1.

US 6,547,538 B1 discloses a single-cylinder hermetic compressor with a synchronous motor according to the above-mentioned characteristics.

US 2,007,388 A describes a refrigerant compressor with an "unloader device" which is controlled so as to operate the refrigerant compressor under predetermined load conditions.

Document DE 102008 045 103 A1 discloses a semi-hermetic reciprocating compressor with an electric motor arranged within an outer casing which drives a cylinder unit arranged in the outer casing.

The general problem is to design a refrigerant compressor so that it can operate more energy efficiently.

This object is achieved according to the invention by a refrigerant compressor of the type described above in that the refrigerant compressor is a semi-hermetic refrigerant compressor having the general housing as an outer housing, in that the general housing has a motor housing section for the electric motor, which represents an outer housing of the electric motor, and a compressor housing section for the reciprocating compressor, which represents an outer housing of the reciprocating compressor, wherein in the compressor housing section which represents the outer housing and forms at least one cylinder housing at least one reciprocating compressor cylinder is provided, which has a piston which can move in a cylinder bore formed in the compressor housing section, a valve plate which closes the cylinder bore and a cylinder head which overlies the valve plate and forms a part of the compressor housing section, in that a cylinder head has an inlet chamber and an outlet chamber for a cylinder bank comprising at least two cylinders, and in that the permanent magnets are designed such that consecutive permanent magnets in a direction of rotation about the rotor axis have on their sides facing the rotor axis a piston which is movable in a cylinder bore formed in the compressor housing section, a valve plate which closes the cylinder bore and a cylinder head which overlies the valve plate and forms a part of the compressor housing section, in that a cylinder head has an inlet chamber and an outlet chamber for a cylinder bank comprising at least two cylinders, and in that the permanent magnets are designed such that the permanent magnets which are consecutive in a direction of rotation about the rotor axis have on their sides facing the rotor axis a piston which is movable in a cylinder bore formed in the compressor housing section, a valve plate which closes the cylinder bore and a cylinder head which overlies the valve plate and forms a part of the compressor housing section, in that a cylinder head has an inlet chamber and an outlet chamber for a cylinder bank which comprises at least two cylinders, and in that the permanent magnets are designed such that the permanent magnets which are consecutive in a direction of rotation about the rotor axis have on their sides facing the rotor axis a piston which is movable in a cylinder bore formed in the compressor housing section, and in that the permanent magnets are designed such that the pistons which are movable in a cylinder bore formed in the compressor housing section have a piston which is movable in a cylinder bore formed in the compressor housing section, rotor shaft in each case an alternating polarity, so that the rotor as a whole has alternating magnetic poles in the direction of rotation due to the permanent magnets.

The advantage of the solution according to the invention can be seen in the fact that such an electric motor for driving a semi-hermetic refrigerant compressor has a higher energy efficiency, in particular at full load and also at partial load. Furthermore, the advantage of such an electric motor can be seen in that, due to synchronous operation, the conveying volume is constant even in the high load range.

The semi-hermetic refrigerant compressor has the general housing as an outer housing, with the electric motor in particular being arranged in the refrigerant atmosphere. The semi-hermetic refrigerant compressor is not provided with an outer encapsulation which completely encloses the reciprocating compressor and the electric motor as a whole, but the compressor housing itself which forms the at least one cylinder housing represents the outer housing.

The solution according to the invention provides that the permanent magnets extend parallel to a rotor axis.

Furthermore, according to the invention it is provided that the permanent magnets are designed as plate bodies, the flat sides of which extend in a longitudinal direction and a transverse direction running transversely to the longitudinal direction.

Furthermore, the solution according to the invention provides that the permanent magnets, which are designed as plate bodies on their flat sides opposite each other, one of which is oriented towards the rotor axis and the other is oriented away from the rotor axis, have a different magnetic polarity, so that the flat poles on the rotor are simply available for synchronous operation of the electric motor. In this case, the permanent magnets are expediently arranged on the rotor such that they extend parallel to the rotor axis in their longitudinal direction in each case.

Furthermore, the permanent magnets are preferably arranged in the rotor such that their transverse directions extend along the outer edges of a geometric polygon symmetrical with respect to the rotor axis.

Details on the magnetization of permanent magnets have not yet been provided.

In principle, the electric motor can be cooled in various ways.

An advantageous solution provides that the coolant path on the suction side passes through the motor housing to cool the electric motor.

In addition to the above-described features of the semi-hermetic refrigerant compressor, a further solution according to the invention provides that the refrigerant compressor is provided with an externally controllable or controlled mechanical power control unit.

Such an externally controlled power control unit creates the possibility of controlling the flow rate of a semi-hermetic refrigerant compressor by means of the mechanical power control unit without a frequency converter for the electric motor, which is economical and efficient, and also, in particular, opens up the possibility of reducing the mechanical loads on the reciprocating compressor.

In particular, it is provided in this respect that the mechanical power control unit connects the coolant path on the outlet side with the coolant path on the inlet side in order to reduce the power in at least one cylinder.

This creates the possibility of operating at least one cylinder so that it does not contribute to the compressor flow.

This solution has the advantage that the mechanical load on the components of the reciprocating compressor is low when there is a reduction in power, since the refrigerant at a pressure level close to the inlet side returns from the outlet side to the inlet side and in this respect in the reciprocating compressor there are no large pressure fluctuations or even pressure and temperature peaks, which in particular also reduce performance when the power is reduced.

As regards the arrangement of the mechanical power control unit, a wide variety of possible solutions are conceivable.

An advantageous solution provides for the mechanical power control unit to be arranged in the cylinder head, which has the advantage that the mechanical power control unit can easily cooperate with at least one of the cylinders.

It is particularly advantageous if the mechanical power control unit is at least partially integrated into at least one cylinder head.

In order to be able to cooperate as optimally as possible with at least one cylinder, it is preferably provided that the mechanical power control unit connects an outlet chamber in the cylinder head to an inlet chamber in the cylinder head via a connecting channel for power reduction.

This makes it possible for the power control unit to cooperate directly with the at least one cylinder assigned to the cylinder head, so that with a power control unit mounted in this way a compact design of the refrigerant compressor can be achieved.

It is particularly advantageous that the connection channel is arranged integrated into the cylinder head, so that the space required for the cooperation of the power control unit with the inlet chamber and the outlet chamber can also be optimised.

In particular, it is provided that the outlet chamber in the cylinder head is arranged directly adjacent to at least one outlet opening for the respective cylinder in the valve plate and thus in particular the outlet chamber also directly adjoins the valve plate and the outlet opening, in particular the outlet valve.

Furthermore, it is preferably provided that the inlet chamber in the cylinder head is arranged immediately adjacent to an inlet opening for the respective cylinder in the valve plate, so that the inlet chamber also directly adjoins the valve plate and the inlet opening.

As regards the way in which the mechanical power control unit opens or closes the connecting channel between the outlet chamber and the inlet chamber, a wide variety of possibilities are conceivable.

For example, it would be conceivable to use conventional sliding designs.

A particularly advantageous solution provides that the mechanical power control unit has a closing piston for closing the connection channel.

Such a closing piston creates the possibility of opening or closing the connection channel, in particular with the shortest possible reaction time.

For a secure seal, the closing piston is preferably guided by a sealing ring in a guide hole, in particular in the cylinder head.

In particular, it is provided that the closing piston can be placed on a sealing seat to close the connecting channel, which runs around the connecting channel, so that when the closing piston is placed on the sealing seat, the connecting channel is interrupted, while when the closing piston is lifted from the compression seat, the connecting channel opens again.

In order to achieve a permanently reliable seal, it is preferably provided that a sealing area of the sealing piston that can be placed on the sealing seat is made of a metal that has a lower hardness than a metal from which the sealing seat is made, or vice versa.

In this respect, the sealing seat can be arranged in various ways.

A particularly advantageous and compact solution provides for the sealing seat to be arranged in a wall section of the cylinder head that separates the inlet chamber from the outlet chamber.

In this respect, the sealing seat may be configured as part of the wall section or may be formed by a component inserted into the wall section of the cylinder head.

In this case, the sealing seat is preferably arranged such that it is arranged in a wall section that runs above the valve plate and above the inlet chamber and, in particular, the sealing seat thus simultaneously represents a mouth opening for the inlet chamber opposite the valve plate.

Furthermore, it is preferably also provided that the sealing seat simultaneously represents a mouth opening for the outlet chamber, so that a direct transition from the outlet chamber to the inlet chamber is achieved via the sealing seat.

For a spatially compact arrangement, it has proven particularly advantageous that the sealing seat is arranged on one side of the inlet chamber opposite the valve plate.

A quick change of the closing piston between the closed and open position is preferably possible if the stroke of the closing piston starting from the sealing seat is in the range from one quarter to one half of the mean diameter of the connecting channel.

As regards the assignment of the mechanical power control unit to each cylinder, no details have been provided in relation to the above explanation of each of the embodiments.

One solution provides for the mechanical power control unit to be assigned to one cylinder and for several mechanical power control units to be provided for several cylinders, if necessary, without necessarily assigning a mechanical power control unit to each cylinder.

A favourable solution provides for a cylinder head to have an inlet chamber and an outlet chamber for a cylinder bank consisting of at least two cylinders.

In this case, several cylinders are combined to form a cylinder bank.

Advantageously, in such a solution it is provided that the respective mechanical power control unit is assigned to a cylinder bank, in particular to at least two cylinders.

In the case of a refrigerant compressor with several cylinder banks, for example N cylinder banks, it is preferably provided that at least N-1 cylinder banks are assigned a mechanical power control unit.

However, in order to be able to optimally reduce the power of the refrigerant compressor, it is preferably provided that a mechanical power control unit is assigned to each cylinder bank.

In order to prevent a backflow of high-pressure refrigerant and thus a pressure drop at the output connection element when the power is reduced, a non-return valve is provided in the compressor housing section which follows the refrigerant paths that can be influenced by the mechanical power control unit.

Furthermore, it is preferably provided that the non-return valve has an outlet opening provided in the valve plate and a valve element cooperating with the valve plate, so that the valve plate can also be used to arrange and configure the non-return valve.

In particular, it is provided that the valve element is clamped on the valve plate, so that the valve plate is used not only for configuring the inlet and outlet valves, but also for holding the valve element of the non-return valve.

As regards the operation of the closing piston, no details have been provided in relation to the previous explanation of the different embodiments.

An advantageous solution provides that a compression spring biases the closing piston in the direction of its position cooperating with the sealing seat, so that the compression spring ensures that the closing piston closes the connecting channel by the action of the compression spring, for example when the refrigerant compressor is not running.

Furthermore, it is preferably provided that the closing piston can be actuated via a pressure chamber, to which suction pressure or high pressure can be applied depending on the external control of the power control unit, the closing piston moving into its open position when suction pressure is applied to the pressure chamber and when high pressure is applied to the pressure chamber the closing piston is biased in the direction of its closed position in addition to the action of the compression spring.

A volume of the pressure chamber is in particular so small that in the open position of the closing piston it is less than a third, better less than a quarter, even better less than a fifth, advantageously less than a sixth and especially advantageously less than a seventh and even more advantageously less than an eighth of the maximum volume of the pressure chamber in the closed position of the closing piston.

This dimensioning of the pressure chamber allows for rapid switching between the closed and open position, since the pressure in only a small volume needs to be changed between suction pressure and high pressure. To apply high pressure or suction pressure to the pressure chamber, a control unit is preferably provided, which is included in the power control unit and can be used to control the pressure application of the closing piston.

In order to carry out the power control of the refrigerant compressor, a power control is preferably provided which controls the at least one power control unit according to a required compressor flow rate. In particular, in this regard, the power control is connected to a higher-level installation control and receives information about the required compressor flow rate from the installation control.

Based on this information about the required compressor flow rate, the power control then controls the at least one or more power control units such that the refrigerant compressor provides the required compressor flow rate, but does not provide any unnecessarily high compressor flow rate.

For this purpose, the refrigerant compressor is designed so that its maximum compressor flow rate is sufficient for the maximum compressor flow rate required by the system control, and lower compressor delivery powers are achieved by reducing the power using the at least one power control unit.

Furthermore, a start control unit is preferably provided for the refrigerant compressor, in particular the refrigerant compressor is provided with a start control unit which controls a start of the electric motor, which in the solution according to the invention starts as an asynchronous motor until the synchronous speed is reached and then continues as a synchronous motor.

In this regard, the starter control unit can control the operation of the refrigerant compressor in different ways to start the electric motor appropriately.

In particular, the starter control unit operates in such a way that it operates the electric motor for starting with a starting current-reducing winding connection.

This could be achieved, for example, by changing from a star connection during startup to a delta connection after startup.

An advantageous solution provides that the starter control unit first applies current to a first partial winding and then to a second partial winding in a stator of the electric motor in order to start the electric motor.

Starting the electric motor with a partial first winding has the advantage that it enables the starting current to be reduced and thus, for example, prevents a heavy load on the power supply network due to an excessively high starting current.

Alternatively or additionally, the start control unit is configured such that it controls the power control during start-up of the electric motor in such a way that the reciprocating compressor only operates with a reduced compressor output during start-up of the electric motor.

It is particularly beneficial for starting the electric motor if the start control controls the power control in such a way that the reciprocating compressor operates with the lowest possible compressor flow during starting of the electric motor.

In this respect the smallest possible compressor flow rate may be a compressor flow rate at which one or more cylinders are still running.

A particularly advantageous embodiment provides that the output of the reciprocating compressor can be controlled in such a way that, with the lowest possible compressor flow rate, none of the cylinders compresses any more refrigerant, so that the torque required to start the reciprocating compressor is minimal.

Furthermore, an advantageous solution provides that the start control controls the power control in such a way that after achieving synchronous operation of the electric motor, the compressor output is gradually increased, for example by additionally switching on another cylinder or an additional cylinder bank or, if appropriate, by additional, if appropriate, successive switching on of additional cylinders or additional cylinder banks.

With regard to the operating states of the reciprocating compressor, no details were provided in relation to the solution according to the invention.

In principle, the reciprocating compressor according to the invention can be operated with all refrigerants customary in semi-hermetic refrigerant compressors.

However, the solution according to the invention creates special advantages for the operation of the reciprocating compressor, in particular for the damage-free operation of the reciprocating compressor when the reciprocating compressor is operated with a suction pressure in the range of 10 bar to 50 bar.

Furthermore, the solution according to the invention is also particularly advantageous with respect to the mechanical load on the reciprocating compressor when the reciprocating compressor operates at a high pressure in the range of 40 bar to 160 bar.

In particular, the refrigerant compressor according to the invention can be used with particular advantage if the reciprocating compressor is operated with carbon dioxide as refrigerant and is designed in particular for operation with carbon dioxide as refrigerant.

Other features and advantages of the invention are the subject of the following description and the graphic representation of some embodiments.

In the drawing, they show:

Figure 1 a side view of an exemplary embodiment of a refrigerant compressor according to the invention;

Figure 2 a top view in the direction of arrow A of Figure 1 of the refrigerant compressor according to the invention;

Figure 3 a front view of the exemplary embodiment of the refrigerant compressor according to the invention; Figure 4 a section offset to one side along line 4-4 of Figure 2;

Figure 5 a longitudinal section through the refrigerant compressor according to the invention; Figure 6 a section along line 6-6 of Figure 7;

Figure 7 a section along line 7-7 of Figure 6 with a closed connecting channel between the inlet chamber and the outlet chamber;

Figure 8 a section similar to Figure 7 with the connecting channel open between the outlet chamber and the inlet chamber;

Figure 9 a section along line 9-9 of Figure 5 through an electric motor rotor;

Figure 10 a schematic representation of an electric motor starter, and

Figure 11 a section similar to Figure 7 through a second embodiment.

An exemplary embodiment of a semi-hermetic refrigerant compressor according to the invention, shown in Figures 1 to 5, comprises a general housing 10 in which a reciprocating compressor 12 and an electric motor 14 are arranged.

The overall housing 10 preferably comprises a compressor housing section 22, which represents an outer housing of the reciprocating compressor 12, and a motor housing section 24, which represents an outer housing of the electric motor 14.

The overall housing 10 is preferably formed by a one-piece housing body 26, which extends parallel to a central axis 28, explained in detail below, and which is closed at the ends on the sides of the compressor housing section 22 by a bearing cover 32 and in the area of the motor section 24 is closed at the ends with a closing cover 34.

In the compressor housing section 22, a compressor shaft designated as a whole with 42 extends coaxially to the central axis 28 between a first shaft bearing 44 arranged in the bearing cover 32 and a second shaft bearing 46 arranged between the reciprocating compressor 12 and the electric motor 14, where the second shaft bearing 46 is held in an intermediate wall 48 molded in the housing body 26, which delimits a drive space 52 located between the bearing cover 32 and the intermediate wall 48, through which the compressor shaft 42 extends and in which the eccentrics 54 and 56 of the compressor shaft 42 are arranged, where on each of the eccentrics 54 and 56 two connecting rods 621 and 622, or 641 and 642 are arranged, where the connecting rods 621 and 641 the pistons 661 and 662 are connected to the pistons 663 and 664. 681 and connecting rods 622 and 642 actuate pistons 662 and 682.

The pistons 66 and 68 are guided in cylinder bores 72 and 74, which are formed by cylinder housings 76, 78, which are molded into the compressor housing section 22, in particular molded in one piece.

Each cylinder housing 76, 78 with the cylinder bore 72, 74 and the piston 66, 68 guided therein forms a cylinder 82, 84 in each case.

The first two cylinders 821 and 841 formed in the compressor housing section 22 form a first cylinder bank 861, while the two cylinders 822 and 842 formed in the compressor housing section 22 form a second cylinder bank 862.

In each of the cylinder banks 861 and 862, the respective cylinder bores 721 and 741 or 722 and 742 are closed by a common valve plate 881 or 882, which rests hermetically sealed on the respective cylinder housings 761 and 781 or 762 and 782 and thus delimit the compression space enclosed by the respective valve plate 881 or 882 and the respective piston 661 and 681 or 662 and 682 and the cylinder bores 721 and 741 or 722 and 742.

Valve plates 881 and 882 are in turn covered by cylinder heads 921 or 922.

In each of the cylinder heads 921 and 922, as shown in Figures 6 to 8, an inlet chamber 94 and an outlet chamber 96 are arranged in each case, which are assigned to the two cylinders 82 and 84 of the respective cylinder bank 86.

In particular, the inlet chamber 94 is located above the inlet openings 102 and 104 of the cylinder 82 and the inlet openings 106 and 108 of the cylinder 84.

Furthermore, the outlet chamber 96 is located above the outlet openings 112 and 114 of the cylinder 82 arranged in the valve plate 88, as well as outlet openings 116 and 118 of the cylinder 84, which are provided with outlet valves 113, 115, 117, 119 seated in the valve plate 88, and in particular directly adjoin it.

As shown in Figures 6 to 8, each cylinder head 92 comprises an outer body 122, which overlies the respective valve plate 88 and encloses the inlet chamber 94 and the outlet chamber 96, which in turn are separated from each other by a separator body 124 running within the outer body 122, wherein the separator body 124 rises from the respective valve plate 88 and extends over the inlet chamber 94 overlapping it.

Thus, the outlet chamber 96 is located laterally adjacent to the inlet chamber 94 in the area of the valve plate 88 and, however, extends between the outer body 122 and the separator body 124 at least in regions above the inlet chamber 94.

For power control, i.e. control of the compressor flow rate of the refrigerant compressor, each cylinder head 92 is assigned a mechanical power control unit 142 which is actively controlled by a power control 138, with which a connecting channel 144 between the outlet chamber 96 and the inlet chamber 94 can be opened or closed, wherein the cylinders 82, 84 assigned to the cylinder head 92 compress refrigerant at full power when the connecting channel 144 (FIG. 7) is closed and do not compress refrigerant when the connecting channel is open, since the refrigerant flows in the reverse direction from the outlet chamber 96 to the inlet chamber 94.

The connecting channel 144 runs through an insert 146 inserted into the separating body 124, which forms a sealing seat 148 that faces the outlet chamber 96 and adjoins a part of the outlet chamber 96 that surrounds the sealing seat 148 and is connected to it.

Furthermore, the sealing seat 148 faces a closing piston 152, which can be positioned on the sealing seat 148, for example, with a metallic sealing region 154 for hermetically sealing the connection channel 144, and which can be lifted from the sealing seat 148 to such an extent that the sealing region 154 is spaced apart from the sealing seat 148 and thus coolant can overflow from the outlet chamber 96 into the inlet chamber 94.

Preferably, the closing piston 152 is guided coaxially to the insert 146 with the sealing seat 148 and is sealed by means of a segment 153 in a guide hole 156, which is formed by a guide sleeve body 158 of the cylinder head 92, which is formed in the outer body 122.

Preferably, the closing piston 152 itself or at least the sealing area 154 is made of a metal, for example a non-ferrous metal, which has a lower hardness than the metal of the sealing seat 148, which is made for example of steel, in particular hardened steel.

In order to allow a rapid movement of the closing piston 152, in particular a stroke of the closing piston 152 between a closed position and an open position is situated in the range between a quarter and a half of the average diameter of the connecting channel 144.

The closing piston 152 delimits a pressure chamber 162, which is arranged on a side of the closing piston 152 facing away from the sealing region 154 and is closed by a closing body 164 on the side facing away from the closing piston 152.

The volume of the pressure chamber 162 is in particular so small that in the open position of the closing piston it is less than a third, better less than a quarter, even better less than a fifth, advantageously less than a sixth and even more advantageously less than an eighth of the maximum volume of the pressure chamber 162 in the closed position of the closing piston 152.

Furthermore, a compression spring 166 is arranged in the pressure chamber 162, which on the one hand rests on the closing body 164 and, on the other hand, acts on the closing piston 152 in the direction of its closed position, which sits on the sealing seat 148.

Depending on the application of pressure in the pressure chamber 162, the closing piston 152 can be moved to its open position shown in Figure 8 or to its closed position shown in Figure 7.

For this purpose, the closing piston 152 is traversed by a throttle channel 172, which extends from the pressure chamber 162 via the closing piston 152 to a mouth opening which is arranged radially outside the sealing region 154 on a side facing the sealing seat 148, but because this is located radially outside the sealing element 154, in the closed position of the closing piston 152, coolant under pressure is allowed to enter the outlet chamber 96 and flow around the sealing seat and is fed into the pressure chamber 162 in a throttled manner.

Furthermore, a relief channel 176 leads to the pressure chamber 162, for example via the closing body 164, which can be connected to a pressure relief channel 184, which is connected to the inlet chamber 94, via a solenoid valve designated in conjunction with 182.

For example, the solenoid valve 182 is designed such that it has a valve body 186 with which the connection between the pressure relief channel 184 and the relief channel 176 can be interrupted or established.

If the connection between the relief channel 176 and the pressure relief channel 184 is established, the suction pressure predominates in the pressure chamber 162, while in the outlet chamber 96 the closing piston 152 is pressured on its side facing the outlet chamber 96 and thus moves into its open position.

However, if the connection between the pressure relief channel 184 and the relief channel 176 is interrupted by the valve body 186, the compression spring 166 presses the closing piston 152 onto the sealing seat 148 and additionally high pressure flows through the throttle channel 172 into the pressure chamber 162, so that a high pressure is generated in the pressure chamber 162 which, in addition to the action of the compression spring 166, presses the closing piston 152 with the sealing element 154 onto the sealing seat 148.

In particular, the closing piston 152 is configured so that it extends radially beyond the sealing seat 148, so that even when the closing piston 152 is in the closed position, the piston surface located radially outside the sealing seat 148 and subjected to high pressure causes the closing piston 152 to move against the force of the compression spring 166 towards the open position, shown in Figure 5, whenever the valve body 186 of the magnetic valve 182 establishes the connection between the relief channel 176 and the pressure relief channel 184, leading to a suction pressure being established in the pressure chamber 162.

The refrigerant supply under suction pressure takes place via a supply channel 202 molded into the compressor housing section 22, which leads to an inlet opening 204 leading to the valve plate 88, through which refrigerant flows under suction pressure to a through opening 206 in the valve plate 88 and through this into the inlet chamber 94.

Furthermore, as shown in Figures 7 and 8, the outlet chamber 96 leads to an outlet opening 212 arranged in the valve plate 88 through which the refrigerant under pressure in the outlet chamber 96 passes into an outlet channel 214 provided in the compressor housing section 22 and can flow to an outlet connection element 216.

In particular, a non-return valve 222 is assigned to the outlet opening 212 of the valve plate 88, which is fastened to the valve plate 88, and a valve element 224 is arranged on one side of the valve plate 88 facing the outlet channel 214, which ensures that in the open position of the closing piston 152 and thus in the event of coolant overflowing from the outlet chamber 96 into the inlet chamber 94, the pressure in the outlet channel 214 does not drop, but is maintained by the non-return valve 222.

Preferably, the non-return valve 222, together with a retaining element 226 assigned thereto, is held by a clamping element 228 on the valve plate 88 and seals against the valve plate 88.

The refrigerant compressor according to the invention is designed as a semi-hermetic compressor, so that via an inlet connection element 232 arranged in the closing cover 34, refrigerant is supplied under suction pressure to an engine compartment 234 and flows through the electric motor 14 in the direction of the central wall 48 and from the engine compartment 234 into the supply channel 202, so that the refrigerant supplied on the suction side cools the electric motor 14 in the engine compartment 234.

The electric motor 14 in turn comprises a stator 252 which is firmly held in the motor housing section 24 with a stator winding 254, which has, for example, two partial windings 256 and 258 which are used to magnetize a laminated stator core 262.

The stator 252 surrounds a rotor designated in conjunction with 272, in whose laminated rotor core 274 there is arranged, as shown in Figure 9, on the one hand a short-circuit cage 276, which comprises short-circuit bars 278 which run parallel to a rotor shaft 282 and which are electrically conductively connected to one another in a circumferential direction at their ends.

Furthermore, plate-shaped permanent magnets 292 are inserted into the laminated core 274, the flat sides 294 of which extend on one side with a longitudinal direction 296 parallel to the rotor axis 282 and with a transverse direction 298 extend transversely to the rotor axis 282 such that the transverse directions 298 form a geometric polygon running around the rotor axis 282 as an axis of symmetry.

The permanent magnets 292 are further configured such that in a direction of rotation 302 about the rotor axis 282, the consecutive permanent magnets 292 each have an alternating polarity on their sides facing the rotor axis 282 in each case, so that the rotor 272 generally has alternating magnetic poles in the direction of rotation by means of the permanent magnets 292.

An electric motor 14 provided with said rotor 272 operates as a synchronous motor in normal operation due to the permanent magnets 292 provided in the rotor 272, wherein said synchronous motor has advantageous energy efficiency and increased coolant flow rate due to the permanent magnets 292.

The rotating field generated by the stator 252 rotates at a defined frequency due to a supply of the stator winding 254, which is produced, for example, because the stator winding 254 is supplied by an alternating current network.

To enable a start with a rotating field of the stator 252 rotating at a constant frequency, the rotor 272 is provided with the short-circuit cage 276, which creates the possibility for the electric motor 14 to initially start as an asynchronous motor until it has reached the speed corresponding to the rotating field of the rotating stator winding and then rotate as a synchronous motor due to the magnetic poles caused by the permanent magnets 292.

Therefore, a refrigerant compressor with such an electric motor can be operated from a standard alternating current network, since it starts like an asynchronous motor.

However, it is also possible to operate such a refrigerant compressor with a frequency converter.

In order to facilitate the starting of the electric motor 14, there is also the possibility of initially applying current only to one of the partial windings 256 or 258 by means of a starting control 312 assigned to the refrigerant compressor - as shown in Figure 10 - to reduce the starting current and then, after a brief starting phase of the electric motor 14 as an asynchronous motor, switching the other of the partial windings 258, 256.

If the refrigerant compressor according to the invention is used for large pressure differences, for example as a CO2 compressor, the start control 312 intervenes in the power control 138 provided for active control of the power control units 142 and causes at least one cylinder bank 86, preferably both cylinder banks 861 and 862, to be deactivated so that when at least one cylinder bank 86 is deactivated, the torque required by the reciprocating compressor 12 is reduced, and when both cylinder banks 861 and 862 are deactivated, the torque required by the reciprocating compressor 12 is reduced because no refrigerant compression is performed, so that on the one hand, the starting current of the electric motor 14 is kept low and on the other hand, it switches very quickly from its operation as an asynchronous motor to operation as a synchronous motor in which the entire torque is available, so that the cylinder banks 861 and 862 are deactivated. 862 can be activated simultaneously or successively (figure 10).

In a second exemplary embodiment, shown in Figure 11, those parts that are identical to those of the first exemplary embodiment are provided with the same reference numbers, so that reference can be made in their entirety to the embodiments of the first exemplary embodiment.

In contrast to the first exemplary embodiment, the retaining element 226' of the non-return valve 222' is configured in the compressor housing section 22, for example by means of a recess on the side of the outlet channel 214, which limits the possible travel of the valve element 224' between its closed position supported on the valve plate 88 and the fully open position.

Such a check element 226' can generally be provided in all compressor housing sections 22 of all refrigerant compressors of the same module, regardless of whether or not they are provided with a non-return valve 222', so that a refrigerant compressor can easily be retrofitted with a non-return valve 222' and in particular with at least one mechanical power control unit 142 according to the invention together with such a non-return valve 222'.

Claims (16)

1. A semi-hermetic refrigerant compressor, comprising a reciprocating compressor (12) and an electric motor (14), a general housing (10), a suction-side refrigerant path leading from a suction connection (232) in the general housing (10) to an inlet chamber (94) of the reciprocating compressor (12), and a pressure-side refrigerant path leading from an outlet chamber (96) of the reciprocating compressor (12) to a pressure connection (216) in the general housing (10), wherein the electric motor (14) is configured as a synchronous motor, in whose rotor (272) permanent magnets (292) are arranged for synchronous operation of the electric motor (14) and a short-circuit cage (276) for starting the electric motor (14) in asynchronous operation, wherein the permanent magnets (292) extend parallel to a rotor axis (282) of the rotor (272), wherein the permanent magnets (292) extend parallel to a rotor axis (282) of the rotor (272), wherein the permanent magnets (292) are arranged ... (292) are designed as plate bodies, the flat sides (294) of which extend in a longitudinal direction (296) and a transverse direction (298) running transversely to the longitudinal direction, wherein the permanent magnets (292) designed as plate bodies on their opposite flat sides (294), of which one is oriented towards the rotor axis (282) and the other is oriented away from the rotor axis (282), have a different magnetic polarity (N, S), characterized in that the refrigerant compressor is a semi-hermetic refrigerant compressor having the general housing (10) as an outer housing, in that the general housing (10) has a motor housing section (24) for the electric motor (14) representing an outer housing of the electric motor (14), and has a compressor housing section (22) for the reciprocating compressor (12), which represents an outer housing of the reciprocating compressor (12), wherein in the compressor housing section (22) representing the outer housing of the reciprocating compressor (12) 1. A compressor housing section (22) comprising a cylinder (82, 84) of the reciprocating compressor (12) having a piston (66, 68) movable in a cylinder bore (72, 74) formed in the compressor housing section (22), a valve plate (88) closing the cylinder bore (72, 74) and a cylinder head (92) overlying the valve plate (88) and forming a part of the compressor housing section (22), in that a cylinder head (92) has an inlet chamber (94) and an outlet chamber (96) for a cylinder bank (86) comprising at least two cylinders (82, 84), and in that the permanent magnets (292) are configured such that in a direction of rotation (302) about the rotor axis (282), consecutive permanent magnets (292) each have a piston (66, 68) movable in a cylinder bore (72, 74) formed in the compressor housing section (22), a valve plate (88) closing the cylinder bore (72, 74) and a cylinder head (92) overlying the valve plate (88) and forming a part of the compressor housing section (22), alternating polarity on its sides facing the rotor axis (282), so that in general the rotor (272) by means of the permanent magnets (292) has alternating magnetic poles in the direction of rotation. 2. Refrigerant compressor according to claim 1, characterized in that the permanent magnets (292) in each case extend with their longitudinal direction (296) parallel to the rotor axis (282) and in that in particular the permanent magnets (292) extend with their transverse directions (298) along the outer edges of a geometric polygon symmetrical to the rotor axis (282). 3. Refrigerant compressor according to one of the preceding claims, characterized in that the refrigerant path on the suction side passes through the motor housing section (24) to cool the electric motor (14). 4. Refrigerant compressor according to one of the preceding claims, characterized in that the refrigerant compressor is provided with an externally controlled mechanical power control unit (142). 5. Refrigerant compressor according to one of the preceding claims, characterized in that the mechanical power control unit (142) connects the refrigerant path on the outlet side with the refrigerant path on the inlet side for power reduction in at least one cylinder (82, 84). 6. Refrigerant compressor according to claim 4 or 5, characterized in that the mechanical power control unit (142) is arranged in the at least one cylinder head (92) and in particular the mechanical power control unit (142) is at least partially integrated in the at least one cylinder head (92). 7. Refrigerant compressor according to one of claims 4 to 6, characterized in that the mechanical power control unit (142) for power reduction connects an outlet chamber (96) in the cylinder head (92) with an inlet chamber (94) in the cylinder head (92) by means of a connection channel (144), in particular the connection channel (144) is arranged in an integrated manner in the cylinder head (92), in particular the outlet chamber (96) in the cylinder head (92) is arranged immediately adjacent to at least one outlet opening (112, 114, 116, 118) for the respective cylinder (82, 84) in the valve plate (88) and in particular the inlet chamber (94) in the cylinder head is arranged immediately adjacent to an inlet opening (102, 104, 106, 108) for the respective cylinder (82, 84) in the valve plate (88). (82, 84) of the valve plate (88). 8. Refrigerant compressor according to one of claims 4 to 7, characterized in that the mechanical power control unit (142) for closing the connection channel (144) has a closing piston (152), in that in particular the closing piston (152) for closing the connection channel (144) can be placed on a sealing seat (148) running around the connection channel (144), in that in particular a sealing area (154) of the closing piston (152) is made of a metal having a lower hardness than a metal from which the sealing seat (148) is made, and/or in that in particular the sealing seat (148) is arranged in a wall section (124) of the cylinder head (92) separating the inlet chamber (94) from the outlet chamber (96), and/or in that in particular the sealing seat (148) is arranged in a wall section (124) which is connected to the cylinder head (92) and ... The sealing seat (148) is arranged on a side of the inlet chamber (94) opposite to the valve plate (88) and/or in particular starting from the sealing seat (148), a stroke of the closing piston (152) is in the range of a quarter to a half of an average diameter of the connecting channel (144). 9. Refrigerant compressor according to one of the preceding claims, characterized in that the respective mechanical power control unit (142) is assigned to a cylinder bank (86), in that in particular in the case of N-cylinder banks (86) of the refrigerant compressor a mechanical power control unit (142) is assigned in particular to at least N-1 cylinder banks (86), and/or in that in particular a mechanical power control unit (142) is assigned to each cylinder bank (86). 10. Refrigerant compressor according to one of the preceding claims, characterized in that a non-return valve (222) is provided in the compressor housing section (22) downstream of the refrigerant paths that can be influenced by the mechanical power control unit (142), in particular the non-return valve (222) has an outlet opening (212) provided in the valve plate (88) and a valve element (224) cooperating with the valve plate (88), in particular the valve element (224) is held on the valve plate (88). 11. Refrigerant compressor according to one of claims 8 to 10, characterized in that a compression spring (166) biases the closing piston (152) in the direction of its position cooperating with the sealing seat (148), in particular that the closing piston (152) can be actuated by a pressure chamber (162), to which suction pressure or high pressure can be applied depending on the external control of the power control unit (142), in particular that the pressure chamber (162) in the open position of the closing piston (152) has a volume which is less than one third, better less than one quarter, of the maximum volume of the pressure chamber (162) in the closed position. 12. Refrigerant compressor according to one of claims 4 to 11, characterized in that a control unit (182) is provided, which is included in the power control unit (142), with which the application of pressure to the closing piston (152) can be controlled. 13. Refrigerant compressor according to one of claims 4 to 12, characterized in that a power control (138) is provided which controls the at least one mechanical power control unit (142) according to the required compressor flow rate. 14. Refrigerant compressor according to one of the preceding claims, characterized in that a start control unit (312) is provided which controls a start of the electric motor (14), in particular the start control unit (312) operates the electric motor (14) for starting with a starting current-reducing winding connection, and/or in particular the start control unit (312) for starting the electric motor (14) applies current initially to a first partial winding (256) and then to a second partial winding (258) in a stator (252) of the electric motor (14), and/or in particular the start control unit (312) controls the power control (138) during the start of the electric motor (14) so that the reciprocating compressor (12) only operates with reduced compressor flow during the start of the electric motor (14), in particular the start control unit (312) controls the power control (138) such that the reciprocating compressor (12) operates with the lowest possible compressor flow rate during the start-up of the electric motor (14). 15. Refrigerant compressor according to one of the preceding claims, characterized in that the reciprocating compressor (12) operates with a suction pressure in the range of 10 bar to 50 bar and/or in particular that the reciprocating compressor (12) operates with a high pressure in the range of 40 bar to 160 bar. 16. Refrigerant compressor according to one of the preceding claims, characterized in that the reciprocating compressor (12) operates with carbon dioxide as refrigerant and is designed in particular for operation with carbon dioxide as refrigerant.