EP2661559B1 - Double-action refrigerant compressor - Google Patents

Description

The invention relates to a double-acting refrigerant compressor.

In the field of recycling of refrigerants from refrigeration systems, especially from air conditioning systems, the use of external compressors is required, which are able to pump under the conditions prevailing at the site of the air conditioning conditions, the refrigerant from the refrigeration system and transfer to a corresponding transport container.

The required compressors must in this case generate a gas pressure in the bottle, which is above the vapor pressure of the refrigerant at the respective ambient temperatures. This gas pressure can exceed significantly in extreme cases which exceed 30 bar, so that for the further assumptions of a working pressure up to 40bar is assumed.

In known recycling devices for transferring the refrigerant from a refrigeration system into a recycling container, the recycling device is provided with a compressor and a compressor bypassing the bypass line. The compressor line and the bypass line are each provided with valves, wherein initially the pressurized refrigerant flows through the bypass line into the recycling container. After pressure equalization between recycling container and refrigeration system, the remaining refrigerant is transferred via the compressor of the recycling device in the recycling container, the bypass line is closed.

DE 101 25 420 C1 describes a pneumatic piston compressor with a compressor piston driven by a drive motor via a crankshaft.

WO 02/40867 A1 to which the preamble of claim 1 refers describes a reciprocating compressor for cooling an electric motor having a variable clearance as a pressure and suction chamber, which is adapted to suck cold air from outside through a suction bore and an inlet check valve and into the interior of the electric motor to cool the engine. The free space over the interior of the electric motor is always connected to the atmosphere.

The invention has for its object to provide a refrigerant compressor with simple and inexpensive construction and with the required for the refrigerant recovery high compression performance.

The refrigerant compressor according to the invention is defined by the features of claim 1. Accordingly, the refrigerant compressor is a double-acting refrigerant compressor having a piston guided freely on two opposite cylinder portions. The cylinder sections are relative not movable with each other. The piston has an inside through the piston extending through the flow channel. Each cylinder section and the piston have at least one check valve along the flow channel, wherein the flow directions of the check valves are rectified.

The cylinder sections may be components of a one-piece cylinder or separate components. It is crucial that the cylinder sections are not movable relative to each other and that the piston in the cylinder sections freely, that is without a connection with other components, such. B. piston rods, and is sealingly guided. Through the piston is an internal flow channel from the one piston end to the opposite end of the piston completely passed. The piston has at least one check valve in the region of the flow channel. Each cylinder section also has at least one check valve. Preferably, the flow channel is formed along a straight longitudinal axis, along which the check valves are arranged. The flow directions of the check valves are rectified, that is, when flowing through the piston by a refrigerant in a first flow direction, the check valves are open and flow through the piston in a second, opposite to the first flow direction through the check valves lock.

In this way it is possible that under high pressure of z. B. 40 bar standing refrigerant a refrigerant system can be transferred to a recycling container with lower pressure without a separate bypass line is required. When pressure equalization between the refrigerant system and the recycling container, the piston sucks refrigerant from the refrigerant system in the direction of the recycling container through the check valve of the cylinder section facing the refrigerant system during a stroke movement. In the subsequent opposite stroke movement of the piston from the recycling container in the direction of the refrigerant system opens the check valve of the piston and the previously sucked from the refrigerant refrigerant flows through the inner flow channel through the piston through its opposite, the recycling container side facing. Upon renewed reversal of the stroke movement, the check valve of the piston locks and the piston presses the refrigerant through the check valve of the cylinder portion, which faces the recycling container, through and in the direction of the recycling container.

The advantage of the refrigerant compressor according to the invention is that a separate bypass line for removing refrigerant from a refrigerant system into a recycling container is not required until pressure equalization. The interior Flow channel can easily, z. B. by a bore. By virtue of the piston guided freely in the cylinder sections, seals for connecting an external mechanism to the piston through the cylinder are not required. The only seals are to be provided in the area of the check valves and the contact areas between the piston and cylinder sections.

In the case of rotationally symmetrical cylinder sections and piston with check valves and flow channel on the central longitudinal axis production of the refrigerant compressor according to the invention by turning and drilling is particularly simple.

Preferably, such a distance is provided between the cylinder sections, that a region of the piston is freely accessible from the outside, to allow access to the piston to drive it without passing seals through the cylinder sections.

The piston is provided between its two end-side compression surfaces with an auxiliary compression surface which forms an auxiliary volume together with one of the two cylinder sections, which generates a driving force counteracting a restoring force during a stroke movement of the piston by a driving force.

It is particularly advantageous if at least one of the two cylinder sections is guided as an inverse piston in the piston, so that the piston surrounds the respective cylinder section on the outside and there, z. B. to its drive, is freely accessible. In particular, both cylinder sections can be guided as inverse pistons in the piston, wherein the two cylinder sections are immovable relative to each other and only the piston performs a movement.

The piston can be touchless by two counter-rotating electromagnets, for. B. as a flat armature drive or as Tauchankerantrieb be driven. In the case of the flat armature drive, the armature plate advantageously protrudes into the magnetic field generated by the electromagnets through the distance between the two cylinder sections. In theory, it is theoretically conceivable to replace one of the two electromagnets by a spring drive. In the case of the plunger armature drive, the piston can be completely guided as a plunger anchor inside a one-piece cylinder.

Alternatively, could be connected by the distance between the two cylinder sections an eccentric guide of a crank mechanism with the piston or engage a rotary drive with a nose in an 8-shaped slide track on the surface of the piston.

Fig. 1

ein erstes Ausführungsbeispiel in einem ersten Betriebszustand,

Fig. 2

das erste Ausführungsbeispiel in einem zweiten Betriebszustand,

Fig. 3

ein zweites Ausführungsbeispiel in einem ersten Betriebszustand,

Fig. 4

das zweite Ausführungsbeispiel in einem zweiten Betriebszustand,

Fig. 5

ein drittes Ausführungsbeispiel in einem ersten Betriebszustand,

Fig. 6

das dritte Ausführungsbeispiel in einem zweiten Betriebszustand,

Fig. 7

ein Ausführungsbeispiel, das nicht Teil der Erfindung ist, in einem ersten Betriebszustand,

Fig. 8

das Ausführungsbeispiel nach Fig. 7 in einem zweiten Betriebszustand,

Fig. 9

ein weiteres Ausführungsbeispiel, das nicht Teil der Erfindung ist,

Fig. 10

ein weiteres Ausführungsbeispiel, das nicht Teil der Erfindung ist,

Fig. 11

ein weiteres Ausführungsbeispiel, das nicht Teil der Erfindung ist,

Fig. 12

ein weiteres Ausführungsbeispiel, das nicht Teil der Erfindung ist, und

Fig. 13

ein weiteres Ausführungsbeispiel, das nicht Teil der Erfindung ist.

Bei dem Kältemittelkompressor des in den Figuren 1 und 2 dargestellten ersten Ausführungsbeispiels besteht das Kompressorsystem aus dem gestuften Zylinder 1 in dem der Kolben 7 mit dem zentralen Überströmkanal 9 in axialer Richtung geführt wird. Der Zylinder ist durch die Einlass-Ventilplatte 2 und die Auslass-Ventilplatte 3 abgeschlossen, in denen das Einlassventil 10 und das Auslassventil 12 eingesetzt ist. Der Überströmkanal 8 wird auf der dem Auslass zugeordneten Seite mit einem weiteren Ventil 11 abgeschlossen.
Hierbei bildet der linke Abschnitt mit vergrößertem Durchmesser des gestuften Zylinders 1 den ersten Zylinderabschnitt 41 und der rechte Abschnitt mit vermindertem Durchmesser den zweiten Zylinderabschnitt 42. Die beiden Zylinderabschnitte 41 und 42 sind also einstückig miteinander verbunden und bilden den Zylinder 1.
Die Grundfunktion des doppeltwirkenden Inline-Freikolbenkompressors wird folgendermaßen beschrieben:
Der Kolben wird durch einen hier noch nicht dargestellten Antrieb in eine lineare Schwingungsbewegung gebracht. Das kann als Resonanzschwingung oder als erzwungene Schwingung geschehen.
Funktionell hat der Kompressor drei charakteristische Volumen, die die Arbeit des Systems beeinflussen und den Kraftverlauf bestimmen:

• das Niederdruck-Arbeitsvolumen 4
• das Hochdruck-Arbeitsvolumen 6
• das Hilfsvolumen 5, welches beim Steuern des Kolbens hilft (am besten mit Bypass zu links vor dem Ventil 10, oder zu rechts vor dem Ventil 12)

Bewegt sich der Kolben 7 nach links, wird im Niederdruck-Arbeitsvolumen 4 das Medium verdrängt. Da das Ventil 10 durch den Druckanstieg schließt, wird das Medium über den Überströmkanal 8 und das Überströmventil 11 in das sich vergrößernde Hochdruck-Arbeitsvolumen 6 gedrückt. Hierdurch wird eine Vorkompression des Mediums erreicht, wobei die Vorkompression näherungsweise vom Verhältnis der Zylinderquerschnitte des Niederdruck-Arbeitszylinders 4 zum Querschnitt des Hochdruck-Arbeitszylinders 6 bestimmt ist.
Hat der Kolben seinen linken Wendepunkt erreicht, kehrt die Bewegung um. Das Medium wird nun aus dem Hochdruck-Arbeitsvolumen 6 verdrängt und gelangt über das Auslassventil 12 in den Auslass. Gleichzeitig vergrößert sich das Niederdruck-Arbeitsvolumen 4. Der Druckabfall im Niederdruck-Arbeitsvolumen 4 und der Druckanstieg im Hochdruck-Arbeitsvolumen 6 führen zum Schließen des Überströmventils 11. Gleichzeitig wird durch das Einlassventil 10 das Medium aus dem Einlass angesaugt.
Hat der Kolben den rechten Wendepunkt erreicht, kehrt die Bewegung wieder um und der Prozess wiederholt sich.In the following, embodiments of the invention will be explained in more detail with reference to FIGS. Show it:

Fig. 1

a first embodiment in a first operating state,

Fig. 2

the first embodiment in a second operating state,

Fig. 3

a second embodiment in a first operating state,

Fig. 4

the second embodiment in a second operating state,

Fig. 5

a third embodiment in a first operating state,

Fig. 6

the third embodiment in a second operating state,

Fig. 7

an embodiment, which is not part of the invention, in a first operating state,

Fig. 8

the embodiment according to Fig. 7 in a second operating state,

Fig. 9

another embodiment, which is not part of the invention,

Fig. 10

another embodiment, which is not part of the invention,

Fig. 11

another embodiment, which is not part of the invention,

Fig. 12

a further embodiment, which is not part of the invention, and

Fig. 13

another embodiment, which is not part of the invention.

In the refrigerant compressor in the Figures 1 and 2 shown first embodiment, the compressor system consists of the stepped cylinder 1 in which the piston 7 is guided with the central overflow channel 9 in the axial direction. The cylinder is closed by the inlet valve plate 2 and the outlet valve plate 3 in which the inlet valve 10 and the outlet valve 12 are inserted. The overflow channel 8 is closed on the outlet side associated with another valve 11.
Here, the left-hand enlarged-diameter portion of the stepped cylinder 1 constitutes the first cylinder portion 41 and the right-hand reduced diameter portion constitutes the second cylinder portion 42. The two cylinder portions 41 and 42 are integrally connected with each other to form the cylinder 1.
The basic function of the double-acting in-line free-piston compressor is described as follows:
The piston is brought by a drive not shown here in a linear oscillatory motion. This can be done as a resonance vibration or as a forced vibration.
Functionally, the compressor has three characteristic volumes that influence the work of the system and determine the force distribution:

• the low-pressure working volume 4
• the high pressure working volume 6
• the auxiliary volume 5, which helps to control the piston (best with bypass to the left in front of the valve 10, or to the right in front of the valve 12)

If the piston 7 moves to the left, the medium is displaced in the low-pressure working volume 4. Since the valve 10 closes due to the increase in pressure, the medium is forced into the increasing high pressure working volume 6 via the overflow channel 8 and the overflow valve 11. As a result, a precompression of the medium is achieved, wherein the precompression is approximately determined by the ratio of the cylinder cross-sections of the low-pressure working cylinder 4 to the cross section of the high-pressure working cylinder 6.
When the piston reaches its left turning point, the movement reverses. The medium is now displaced from the high pressure working volume 6 and passes through the outlet valve 12 in the outlet. At the same time, the low-pressure working volume 4 increases. The pressure drop in the low-pressure working volume 4 and the pressure increase in the high-pressure working volume 6 lead to the overflow valve 11 closing. At the same time, the medium is sucked out of the inlet by the inlet valve 10.
When the piston reaches the right turning point, the movement reverses again and the process repeats itself.

In the coolant recycling mode, the design has the advantage of providing passive pressure equalization between the inlet and the outlet. In use, the bypass conventionally required by the prior art may be eliminated. The design of the double-acting in-line free-piston compressor, the medium through the inlet valve 10, the spill valve 11 and the outlet valve 12 directly overflow. This can be done both as a liquid and as a gaseous fraction.

After pressure equalization is in the low-pressure working volume 4 and in the high-pressure working volume 6, the vapor pressure of the coolant, which is presently assumed to be 40 bar exist. Due to the pressure in the secondary volume 5, the force-displacement behavior of the system is now significantly influenced. Version 1: The volume is vented to the environment. The pressure is therefore always normal pressure 1 bar. Variant 2: The volume is gas-tight and is designed with a constant pre-pressure p ₀ as a gas spring. Variant 3: The volume is connected to the inlet line so that the inlet pressure is equal to the working pressure in the cooling system. Variant 4: The volume is connected to the outlet line so that the secondary pressure in the secondary volume equals the working pressure in the recycling container.

A modification of the first embodiment results from the opening of the cylinder in the middle, so that as a second embodiment of a design according to the FIGS. 3 and 4 arises, in which the first cylinder portion 41 is spaced from the second cylinder portion 42. By the division of the cylinder into two spaced-apart cylinder sections 41, 42 is a direct mechanical access to the piston and thus also allows a drive using positive locking.

From a further modification, the third embodiment results in the FIGS. 5 and 6 with inverse compression chamber. The compressor with inverse compression chamber consists of the piston 25 with the overflow channel 8, the intermediate valve 11 and the inverse compression chamber 6. The piston 25 runs in the cylinder 24, which is closed with the inlet valve plate 2. In the intake valve plate 2, the intake valve 10 is installed. Intake valve plate 2, cylinder 24 and piston 25 form the low-pressure compression volume 4.

In the inverse compression chamber 6, the fixed inverse piston 23 with the outlet channel and the outlet valve 12 is inserted. Cylinder 24 and inverse piston 23 are fixedly connected to each other via a frame, not shown here, and form the stationary system of the compressor.

An advantage of this arrangement is the direct mechanical access to the piston while maintaining the inline flow of the medium, so that on the one hand the drive of the piston can be done with a forced operation, for example with a crank mechanism, and on the other hand, the medium directly from the inlet through all the valves through to the outlet can flow.

In the fourth embodiment in the FIGS. 7 and 8 both cylinder sections 41 and 42 are guided as inverse pistons in the piston 25.

The fifth embodiment according to Fig. 9 shows a flat armature drive for driving the piston. The piston, which itself may be made of a material that is not relevant to the drive, is mechanically connected to the armature plate 52 made of magnetically soft iron. On both sides in each case a pot magnet consisting of the iron core 50 or 54 and the electric coil 51 and 53 is arranged. By alternating energizing the coils is each generates a magnetic field between the pot magnet and the anchor plate, which puts the anchor in the appropriate movement. To control the current flow position sensors for the piston are required. In the simplest case, this can be a slide switch which switches the current lead to the other coil when a predetermined end position is reached.

Other concepts can use additional electronic elements that not only realize the switching position-dependent, but also include, for example, the speed and the load in the control. An advantage of the drive is that the flat armature has a force-displacement curve that can be well adapted to that of the compressor. With decreasing air gap between armature and magnet, the force increases disproportionately, so that in particular the high forces can be applied in the Kolbenendlagen.

In the sixth embodiment in Fig. 10 a magnetic spring drive is used for the piston. The operating principle is a spring-mass oscillator, wherein the piston is excited as mass to an oscillating motion. The work that the machine is supposed to deliver acts as cushioning and must be applied as a synchronous excitation by the magnet. The principle is very effective for smaller work loads. For a vibration to actually take place, the kinetic or potential energy stored in the spring-mass system must be greater than the work to be delivered.

In the seventh embodiment in Fig. 11 a plunger armature is used as a drive for the piston. The coils mutually generate a magnetic flux in the left or in the right area of the plunger coil. The anchor is then pulled each time in the appropriate end position. Here, too, it depends on an optimized control of the coil in order to avoid unrestrained striking of the armature. The control of the coils is carried out in the same manner as in the flat armature drive.

According to the embodiment Fig. 12 the piston 7 is driven via an eccentric 61 with a shaft 60 by a conventional crank mechanism. The symmetrically arranged shaft 60 of the rotary drive can be converted via known methods into a positively driven oscillation. The method can be used for both normal construction and inverse compression chamber design. The advantage here is the use of normal rotary drives and the positive control of the way.

Alternatively, as a conventional drive, a rotary drive 71 as in Fig. 13 , whose axis of rotation corresponds to the central longitudinal axis of the piston 7, serve to engage with an inner nose 72 in a arranged on the outer peripheral surface of the piston 7 slide track 73 in the form of an "8" to rotate the rotary drive 71, the piston 7 in a to offset oscillating stroke movement.

Claims (8)

1. A double-acting refrigerant compressor comprising a piston (7) freely guided on two cylinder portions (41,42) arranged opposite to each other and being immobile relative to each other, said piston comprising a flow channel (8) extending internally through the piston (7), each cylinder portion (41,42) and the piston (7) comprising, along the flow channel (8), respectively at least one back-check valve (10,11,12), wherein the back-check valves (10,11,12) are arranged in such a manner that their flow directions are unidirectional, wherein the piston (7) on an end side thereof comprises a low-pressure compression face adjacent to a compressible low-pressure working volume (4), and on the opposite side thereof comprises a high-pressure compression face adjacent to a compressible high-pressure working volume (6), said high-pressure compression face being smaller than the low-pressure compression face, wherein the compressible low-pressure working volume (4) is formed between the low-pressure compression face, an inlet valve plate (2) comprising a first back-check valve (10) as an inlet valve, and a first cylinder portion (41), and wherein the compressible high-pressure working volume (6) is formed between the high-pressure compression face, an outlet valve plate (3) comprising a second back-check valve (11) as an outlet valve, and a second cylinder portion (42),
   characterized in
   that that the piston (7) comprises, between the low-pressure compression face and the high-pressure compression face, an auxiliary compression surface which together with the first cylinder portion (41) forms an auxiliary volume (5) that is designed, in case of a stroke movement of the piston caused by a drive force, to generate a restoring force acting against the drive force and thereby to assist in the control of the piston in that the auxiliary volume (5)

   - can be brought into a first state in which the auxiliary volume (5) is vented toward the ambience of the refrigerant compressor so that an atmospheric normal pressure is caused to prevail in the auxiliary volume,

   - can be brought into a second state in which the auxiliary volume (5), while being gas-tight and having a constant pre-pressure p0, is operative as a gas pressure spring,

   - can be brought into a third state in which the auxiliary volume (5) is connected to an inlet line connected to a refrigerating system so that the pre-pressure in the auxiliary volume (5) is equal to the working pressure in the refrigerating system, and

   - can be brought into a fourth state in which the auxiliary volume (5) is connected to an outlet line connecting to a recycling bin so that the pre-pressure in the auxiliary volume is equal to the working pressure in the recycling bin.
2. The double-acting refrigerant compressor according to claim 1, characterized in that the piston (7) and the cylinder portions (41,42) are formed with rotational symmetry, wherein the back-check valves (10, 11,12) and the flow channel (8) are arranged on the central longitudinal axis of the piston (7) and the cylinder portions (41,42).
3. The double-acting refrigerant compressor according to claim 1 or 2, characterized in that the cylinder portions (41,42) are spaced from each other in such a manner that a region of the piston (7) is freely accessible from outside the cylinder portions (41,42).
4. The double-acting refrigerant compressor according to any one of the preceding claims, characterized in that the valve of the piston (7) is formed in the high-pressure compression face.
5. The double-acting refrigerant compressor according to any one of the preceding claims, characterized in that at least one cylinder portion (41,42) is guided as an inverse piston (23) in the piston (7).
6. The double-acting refrigerant compressor according to any one of claims 1 to 5, characterized in that the piston (7) is driven in a contactless manner by two solenoids operating in opposite senses.
7. The double-acting refrigerant compressor according to any one of claims 1 to 5, characterized in that the piston (7) is guided by a crank drive via an eccentric guide arrangement (61).
8. The double-acting refrigerant compressor according to any one of claims 1 to 5, characterized in that the piston (7) is provided with an "8"-shaped sliding track (73) engaged by a nose (72) of a rotary drive (71) for driving the piston (7).

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