DE102004057367A1 - axial piston - Google Patents

Abstract

Axial piston compressor (1) comprising a housing (2), a cylinder block (3), at least one piston reciprocating axially in the cylinder block (3), a cylinder head (4), a suction chamber chamber (5) arranged essentially in the cylinder head (4). a suction gas inlet (6) in the compressor and a drive shaft (7), wherein the drive shaft (7) between the suction chamber (5) and the Sauggaseintritt (6) is sealed to the outside (shaft seal 8).

Description

The The invention relates to an axial piston compressor, in particular a Compressor for the air conditioning system of a motor vehicle, according to the preamble of the claim 1.

Such compressors are for example from the DE 196 47 861 , of the EP 0 688 953 , of the EP 0 838 590 , of the EP 0 911 517 , of the US 5,704,769 , as well as the US 5,733,107 known. The above-cited references relate to compressors with a non-variable displacement, ie the tilt angle of the piston driving the swash plate is not changeable. Furthermore, such and in particular the compressor described in the cited documents often double or double-acting piston. In such constructions, usually the engine as well as a surrounding engine compartment with respect to the axial extent are arranged centrally. To this end, two cylinder blocks are usually connected on both sides, in each of which one end of the two piston ends of the piston is guided. Usually are in these constructions usually three double-acting pistons.

considered If such a double-acting piston, so if the one piston end in its associated cylinder block or the associated cylinder bore is in the top dead center, the other end of the piston in its associated cylinder block or the associated cylinder bore in the bottom dead center. As usual with all compressors of this type, the cylinder blocks, more precisely said the cylinder bores, completed by a valve plate assembly, which usually consists of a valve plate, suction valves, pressure valves and valve stops consists.

At the assembly of the valve plate in turn joins a cylinder head, which separates a suction chamber from a pressure gas chamber. Due to the explained Compressor design are cylinder block, valve plate assembly as well as the cylinder head in pairs.

at the mentioned Compressors there are only two pressure levels, namely the pressure in the intake state the compressor (suction pressure), as well as the pressure after the compression process (Compression pressure). There are none between these two pressures further pressure position. A in the engine caused by leakage gas (piston) Pressure greater than the suction pressure (and less than the compression pressure) is by a short circuit or prevents a connection to the suction side.

at one over the tilt angle of the swash plate adjustable compressor, however, the swashplate tilt angle is through Variation of pressure in the engine room changed. The pressure in the engine room can on pressures between the high pressure level (i.e., the compression pressure) and the low pressure level (suction pressure) can be varied.

The Compressor according to the state The technology is usually by a led out of the compressor housing shaft end driven. For this example, magnetic clutches and pulleys used, over which is the compressor with the engine speed can be driven.

Since in a construction based on the concept of a double-acting piston assembly two cylinder heads must be used, the shaft must be guided out of the compressor housing through a central bore of a cylinder head. For driving, as already mentioned above, usually a magnetic coupling is used. As a shaft seal, L13 primarily uses lip seals in one to several stages. Axial slip ring seals are still under discussion, in particular with the desire to further reduce leaks for the refrigerant R134a or for the application of CO ₂ as a refrigerant. It should be noted at this point that lip seals are also under discussion in connection with CO ₂ as the refrigerant.

Usually Corresponds to compressors with a double-acting piston assembly the shaft seal, independent of which type it is, with the lower pressure level. For this purpose, the engine including drive shaft and shaft seal with subjected to the suction pressure. The impingement of the engine (despite any leaks) with the suction pressure is, as already stated above, through a short between Engine chamber and suction chamber achieved.

at the above closer described compressors includes the shaft seal-containing Cylinder head about in concentric arrangement a shaft seal chamber, as well as an annular Suction chamber and an annular pressure chamber.

In contrast, for example, the Zexel Corporation "DKS-15" series compressor has a construction in which the shaft seal is integrated directly in the centrally located suction chamber, in other words, that the shaft seal chamber located in the center is equipped with Accordingly, the. is an annular suction chamber coincides Pressure gas chamber arranged concentrically and annularly around the suction chamber around.

Such an arrangement is for example also from the EP 0 838 590 known while according to the DE 196 47 861 , of the EP 0 911 517 , of the US 5,704,769 and the US 5,733,107 , as well as the EP 0 688 953 a division of the cylinder head takes place in three chambers.

Similar compressor designs with respect to a division of the cylinder head into two chambers, for example, from EP 1 164 289 , of the EP 1 233 180 , of the EP 1 239 154 and the DE 102 06 748 known. The compressors described in these publications are essentially controllable with respect to their piston stroke compressor, in which the pistons are effective on one side.

As already mentioned, the shaft seals are usually in the central position Suction chamber arranged. For compressors whose piston stroke can be regulated is, the shaft seal is usually in the axial direction on the cylinder head opposite lying side.

A Arrangement of the shaft seal, in particular a mechanical Axial mechanical seal in the cylinder head or in the suction chamber has the advantage that the Shaft seal on the one hand comparatively well by in the Suction gas chamber located suction gas can be cooled and on the other hand acted upon by the lowest pressure within the compressor (as is the case with uncontrolled compressors).

A disadvantage of the objects of EP 1 164 289 , of the EP 1 233 180 , of the EP 1 239 154 as well as the DE 102 06 748 is that the oil supply to the shaft seal is not optimally solved in operation, the refrigerant can be comparatively little cooling effect that the shaft seal, in particular the sealing gap, are in a kind of dead space (poor oil circulation) and that at compressor standstill no oil reservoir on the sealing rings can be present (oil flows away from the sealing gap), which inevitably leads to leaks in long downtimes.

outgoing from this prior art, it is an object of the present invention specify a compressor in which the oil supply both at longer downtime as well as in the operation of the compressor and the suction gas cooling of the shaft seal are improved.

These The object is achieved by a compressor having the features of the patent claim 1 solved, where preferred developments and embodiments are described in the subclaims.

One inventive compressor includes a Casing, a cylinder block, at least one axially in the cylinder block and herbeweglichen piston and a cylinder head. A suction chamber is arranged substantially in the cylinder head, and the compressor has furthermore a suction gas inlet and a drive shaft. One essential point of a compressor according to the invention is that the drive shaft between the suction chamber and the Sauggaseintritt outward is sealed, through a shaft seal. This ensures that that the oil supply the shaft seal even with longer Downtimes and in the operation of the compressor is optimized because the oil is not flow out of the chamber can (internal sealing element or oil level protection), while the suction gas cooling the Shaft seal also reached an optimum level.

In a preferred embodiment is the shaft seal within a separate shaft seal chamber arranged, making a mounting and maintenance friendly (e.g. when installing the shaft seal from the outside) Axial piston compressor arises. The shaft seal chamber is preferably between the suction chamber and the Sauggaseintritt arranged, which is a structurally small Effort ensures. In a further preferred embodiment is between the peripheral wall of the shaft seal chamber and at least a part of the shaft seal arranged therein an annular space limited, in which opens the suction gas inlet. The annulus preferably communicates with an axial gap between the end face of the shaft seal and the side wall of the shaft seal chamber facing this end face. The width of the annular space and / or the axial gap is approximately between 1.5 mm and 5.0 mm. The above-mentioned embodiments represent structurally simple variants of a compressor according to the invention which is characterized by the fact that the mean diameter of the Shaft seal chamber not significantly larger than the mean diameter the shaft seal itself is the advantage that is achieved in the Refrigerant flow entrained oil or the in the refrigerant flow entrained oil tends to is larger than at a relatively sprawling Shaft seal chamber. Furthermore, the flow velocity of the refrigerant is comparatively larger and the cooling effect through Turbulence and the corresponding forced convection greater than in a compressor with a larger shaft seal chamber.

In a further preferred embodiment, the cylinder head is integrally formed, which ei ensures low production costs. An alternative embodiment is characterized in that the cylinder head is made in two parts. The components of the cylinder head may consist of the same materials, for example aluminum, or of different materials, for example of aluminum and steel. Components containing large cavities can be constructed of a solid material (this is particularly advantageous for the use of CO ₂ as a refrigerant), while the component that incorporates the shaft seal is made of a material that has good thermal conductivity. is trained. A possible material for this is aluminum, which is distinguished not only by its good thermal conductivity but also by its low weight. This ensures sufficient heat dissipation to the environment.

A Preferably connected to the drive shaft rotatably connected pulley flow elements on, which cause an air flow upon rotation of the same, the on the cylinder head and the shaft seal receiving Component of the compressor, so for example the shaft seal chamber, are directed. The pulley is at the suction chamber arranged facing side of the compressor. In addition to their functionality regarding the drive of the compressor according to the invention takes over the pulley therefore a second function, namely, the Cool compressor accordingly. This is an optimal heat dissipation with low constructive means reached. In a further preferred embodiment, the shaft sealing chamber is such trained that at a standstill of the compressor held an oil original in the same becomes. This provides an optimal oil supply safely, preferably in the shaft seal chamber for holding the oil template an oil barrier and / or a labyrinth seal and / or a sealing lip arranged is or are. The seal in the shaft allows a optimal oil supply, the preferred embodiments are easy and inexpensive to produce in terms of the type of seal.

The oil template preferably reaches at least the lower edge of a sealing gap the shaft seal. This implies that in the shaft seal chamber premier Suction gas inlet and the outgoing from this suction gas outlet (in Direction to the suction chamber) with respect to the installation position of the compressor are arranged so that they by no means located at the bottom of the shaft seal chamber or are arranged so that a complete emptying the chamber is made possible, for example, at compressor standstill. In an advantageous embodiment are all openings and recesses of the shaft seal chamber, in particular the openings for the Connections between the shaft seal chamber and the suction gas inlet or the shaft seal chamber and the suction chamber above the lower edge of the sealing gap of the shaft seal. This will a leakage of the oil, that form the oil original should, especially in a compressor standstill, effective prevented. The opening in the shaft sealing chamber for the connection between shaft seal chamber and Sauggaseintritt is arranged so that they between lower edge and upper edge of the sealing gap. This poses efficient cooling for sure. Preferably, the opening is located for the Connection between shaft seal chamber and suction gas inlet centrally between the lower edge and the upper edge of the sealing gap.

In a further embodiment are the openings for the Connections between the shaft seal chamber and the Sauggaseintritt or the shaft seal chamber and the suction chamber also on one different level arranged in the shaft seal chamber. Also by the arrangement at different heights, the cooling function improved. Also another preferred embodiment of a compressor according to the invention promotes an optimal cooling function for the Compressor: In said embodiment the suction duct is designed such that from this emerging suction gas or the entire of this emerging suction mainly the Area of the sealing gap of the shaft seal flows against and / or is turned around the shaft seal. By such Construction also a kind of "dead space" is avoided with respect to the cooling.

As already stated above, should the shaft seal in a compressor according to the invention not only cooled essentially by the suction gas and the entrained oil, but also by a heat dissipation outward, i.e. So a heat dissipation to the environment, which can be done directly or indirectly via the housing parts. To is in a preferred embodiment the cylinder head formed at least two parts, with between at least two components of said cylinder head a thermal Insulation is arranged so that in the area of the shaft seal a comparatively cool one Component is located, in particular of a thermally highly conductive material such as aluminum is made. The thermal insulation comprises preferably a steel sheet which is on one or both sides, i. So on a cylinder block facing side of the steel sheet and / or on a side facing away from the cylinder block of the steel sheet elastomer coated.

The Shaft seal included in a particular embodiment a lip seal or an axial mechanical seal. This poses a structurally easily executable embodiment a compressor according to the invention for sure. Furthermore, in a further preferred embodiment on the cylinder head cooling fins arranged, which for a good heat dissipation to care.

to increase the security is preferably in or at the connection between Suction gas inlet and shaft seal chamber a check valve arranged.

The Invention will be described below with regard to further advantages and Features by way of example and with reference to the enclosed Drawings described. The drawings show in:

1 a preferred embodiment of a compressor according to the invention in cross section;

2 a simplified representation of the 1 with an enlarged detail view of a shaft seal chamber in cross section along a sectional plane II and as a schematic representation;

3 again a simplified representation of 1 with a detailed representation of an internal sealing element (a) and a detailed view of a bearing (b) of the drive shaft (in each case in sectional view); and

4 again a simplified sectional view of a compressor according to the 1 with a detail view of the shaft sealing chamber (in cross section, along a sectional plane II (a)), and a schematic view of the shaft seal (b).

Such as the 1 can be seen, has the preferred embodiment of the compressor according to the invention 1 a housing 2 , a cylinder block 3 and a cylinder head 4 on. In the cylinder block 3 seven pistons (not shown) are mounted axially reciprocable. A suction chamber 5 is essentially in the cylinder head 4 arranged and communicates with a suction gas inlet 6 in connection. The compressor is powered by a pulley 12 by means of a drive shaft 7 driven. The present compressor is a variable piston stroke compressor with the piston stroke being defined by a pressure differential between the suction gas side and an engine chamber 7a prevails, is regulated. Depending on the size of the pressure difference is a swivel or swash plate 7b more or less deflected or pivoted from its vertical position. The larger the resulting swing angle, the larger the piston stroke, and accordingly, the higher the pressure at the outlet side of the compressor (DP) is provided.

A sealing of the drive shaft to the outside by a shaft seal 8th , said shaft seal 8th between the suction chamber 5 and the suction gas inlet 6 within a separate shaft seal chamber 9 is arranged. The shaft seal chamber 9 is in its entire dimensions between the suction chamber 5 and the suction gas inlet 6 arranged. Between a peripheral wall of the shaft seal chamber 9 and the shaft seal disposed therein 8th is an annulus 10 limited, in which the suction gas inlet 6 empties. The annulus 10 is doing with an axial gap 11 provided, which between an end face of the shaft seal 8th and the side wall of the shaft seal chamber facing this end face 9 is arranged. The width of the annulus 10 or the axial gap 11 is about 3.0 mm, it should be noted at this point that a width of about 1.5 mm and 5.0 mm can affect the flow conditions in the compressor low.

The cylinder head 4 The present preferred embodiment is formed in two parts and consists of two components 4a and 4b as well as an insulation 16 together. This ensures that parts which are subject to a high load or are exposed to high pressure, made of a correspondingly tough material (steel) are made (part 4b ), while parts subject to lower loads (part 4a ), but are optimized for heat dissipation, are made of a lighter, thermally highly conductive material (aluminum). The two parts are through the thermal insulation 16 separated from each other. This consists of a steel sheet which has a thickness of approximately 0.3 mm and is elastomer coated on both sides. Of course, steel sheets are conceivable, which are elastomer-coated on one side only. If both sides are mentioned, then the two sides are meant, which are the cylinder block 3 facing or the cylinder block 3 are averted. As mentioned, the component 4a which is the shaft seal 8th absorbs, because of the required good heat dissipation made of aluminum, while the component 4b which is the suction chamber 5 and especially the compressed gas outlet (DP) accommodated, is made of steel.

The drive shaft 7 is with the pulley 12 rotatably connected, the pulley 12 at the suction chamber 5 facing side of the compressor 1 is arranged. The pulley has flow elements 31 on, the rotation of the same one on the cylinder head 4 , ie into the special on the component 4a the cylinder head, which includes the shaft seal, directed air flow (indicated by the arrows 32a and 32b ) cause.

The shaft seal chamber 9 is designed such that at a standstill of the compressor 1 an oil template 14 in the shaft seal chamber 9 is held (see this 2 ). From the schematic representation in 2 It can also be seen that in one connection 33 between suction gas inlet 6 and shaft seal chamber 9 a check valve 15 is arranged. The connection between shaft seal chamber 9 and suction chamber 5 is with the reference numeral 34 characterized.

How out 3 , in particular from the detail drawing (a) in the 3 it can be seen is on the drive shaft 7 a sealing lip 17 arranged, which seals the engine chamber against the pressurized components of the compressor. To the sealing lip 17 Then there is a warehouse 35 (see also 3 (b)).

The oil original in the shaft seal chamber 9 exceeds how out 2 combined with 4 (especially 4 (a)), a lower edge 36 a sealing gap of the shaft seal 8th , In detail, the emergence of said gap in 4 shown. In a simplified representation, the sealing or sealing ring geometry consists of a ring 38 that with the cylinder head 4 connected, and a ring 39 which rotates with the shaft and is biased by a spring. From the detailed drawing of the chamber 9 in 4 are the bottom edge 36 the sealing gap as well as the top edge 37 the sealing gap visible. Further, the compounds 33 and 34 drawn, the connection 33 as mentioned above, the one between the shaft seal chamber 9 and suction gas inlet 6 is, and the connection 34 the one between shaft seal chamber 9 and the suction chamber 5 is. To hold the oil reservoir securely in the shaft seal chamber 9 arranged openings for the compounds 33 and 34 above the lower edge 36 the sealing gap of the shaft seal 8th arranged. The opening for the connection 33 is arranged such that it is centered between the lower edge 36 and top edge 37 the sealing gap is located. In order to have ideal flow conditions and an ideal cooling effect, the openings for the connections 33 and 34 that are in the shaft seal chamber 9 are arranged at a different level in the shaft seal chamber 9 arranged (see again 4 (A)). The suction channel 13 is further formed such that the suction gas, which emerges from the suction gas channel, on the one hand, the region of the sealing gap of the shaft seal 8th flows on the other hand to the shaft seal 8th is turned around. This ensures ideal flow conditions. Finally, it should be noted that the cylinder head 4 cooling fins 30 are arranged.

Even though the invention with reference to an embodiment is described with a fixed combination of features, but it includes also the conceivable further advantageous combinations of these features, such as in particular, but not exhaustively, by the subclaims are. All Features disclosed in the application documents are considered to be essential to the invention as far as they are individually or in combination with respect to the state new to the technology.

1

compressor

2

casing

3

cylinder block

4

cylinder head

4a

Component of the cylinder head 4 which includes the shaft seal

4b

Component of the cylinder head 4 that the suction chamber and the outlet for

compressed gas (DP)

5

Sauggaskammer

6

suction gas

7

drive shaft

7a

Engine compartment

7b

swash plate

8th

shaft seal

9

Shaft seal chamber

10

annulus

11

axial gap

12

pulley

13

suction gas

14

oil receiver

15

check valve

16

insulation

17

sealing lip

30

cooling fin

31

flow elements

32a

arrow

32b

arrow

33

Connection shaft sealing chamber 9 - Suction gas inlet 6

34

Connection shaft sealing chamber 9 - Suction chamber 5

35

camp

36

lower edge sealing gap

37

top edge sealing gap

38

ring

39

ring

Claims (24)

Axial piston compressor ( 1 ) with a housing ( 2 ), a cylinder block ( 3 ), at least one im Cylinder block ( 3 ) axially reciprocable piston, a cylinder head ( 4 ), one essentially in the cylinder head ( 4 ) arranged suction chamber chamber ( 5 ), a suction gas inlet ( 6 ) in the compressor and a drive shaft ( 7 ), characterized in that the drive shaft ( 7 ) between the suction chamber ( 5 ) and the suction gas inlet ( 6 ) is sealed to the outside (shaft seal 8th ). Compressor ( 1 ) according to claim 1, characterized in that the shaft seal ( 8th ) within a separate shaft seal chamber ( 9 ) is arranged. Compressor ( 1 ) according to claim 2, characterized in that the shaft sealing chamber ( 9 ) between the suction chamber ( 5 ) and the suction gas inlet ( 6 ) is arranged. Compressor ( 1 ) according to claim 2 or 3, characterized in that the shaft sealing chamber ( 9 ) and the suction chamber ( 5 ) are arranged in the axial extension of the compressor longitudinal axis one behind the other or strung together. Compressor ( 1 ) according to one of claims 2 to 4, characterized in that between the peripheral wall of the shaft sealing chamber ( 9 ) and at least part of the shaft seal ( 8th ) an annulus ( 10 ), in which the suction gas inlet ( 6 ) opens. Compressor ( 1 ) according to one of claims 2 to 5, characterized in that the or an annular space ( 10 ) with an axial gap ( 11 ) between an end face of the shaft seal ( 8th ) and this end face facing side wall of the shaft seal chamber ( 9 ) communicates. Compressor ( 1 ) according to claim 5 or 6, characterized in that the width of the annular space ( 10 ) and / or axial gap ( 11 ) is between about 1.5 mm and 5.0 mm. Compressor ( 1 ) according to one of the preceding claims, characterized in that the cylinder head ( 4 ) is formed in one piece. Compressor ( 1 ) according to one of claims 1 to 7, characterized in that the cylinder head ( 4 ) is formed in several parts, in particular in two parts. Compressor ( 1 ) according to claim 9, characterized in that the component which seals the shaft ( 8th ) comprises, from a material having a good thermal conductivity, in particular of aluminum, is formed. Compressor ( 1 ) according to one of the preceding claims, characterized by a with the drive shaft ( 7 ) rotatably connected pulley ( 12 ), which are connected to the suction chamber ( 5 ) facing side of the compressor ( 1 ), and the flow elements ( 31 ), which upon rotation of the pulley ( 12 ) one on the cylinder head ( 4 ) and the shaft seal ( 8th ) receiving component of the compressor ( 1 ) directed air flow ( 32a . 32b ) causes. Compressor ( 1 ) according to one of claims 2 to 11, characterized in that the shaft sealing chamber ( 9 ) is designed such that when the compressor ( 1 ) an oil template ( 14 ) in the shaft seal chamber ( 9 ) is held. Compressor ( 1 ) according to claim 12, characterized in that the shaft sealing chamber ( 9 ) for holding the oil template ( 14 ) an oil barrier wall and / or a labyrinth seal and / or a sealing lip ( 17 ) having. Compressor ( 1 ) according to claim 12 or 13, characterized in that the oil original ( 14 ) at least the lower edge ( 36 ) a sealing gap of the shaft seal ( 8th ) reached. Compressor ( 1 ) according to one of claims 2 to 14, in particular according to claim 14, characterized in that all openings and recesses of the shaft sealing chamber ( 9 ), in particular the openings for the connections ( 33 . 34 ) between shaft seal chamber ( 9 ) and suction gas inlet ( 6 ) or shaft sealing chamber ( 9 ) and suction chamber ( 5 ) above the lower edge ( 36 ) of the sealing gap of the shaft seal ( 8th ) are arranged. Compressor ( 1 ) according to one of claims 2 to 15, characterized in that the opening for the connection ( 33 ) between shaft seal chamber ( 9 ) and suction gas inlet ( 6 ) is arranged in the shaft seal chamber such that it is between lower edge ( 36 ) and top edge ( 37 ) of the sealing gap is located. Compressor ( 1 ) according to claim 16, characterized in that the opening for the connection ( 33 ) in the middle between lower edge ( 36 ) and top edge ( 37 ) of the sealing gap is located. Compressor ( 1 ) according to one of claims 2 to 17, characterized in that the openings for the connections ( 33 . 34 ) between shaft seal chamber ( 9 ) and suction gas inlet ( 6 ) or shaft sealing chamber ( 9 ) and suction chamber ( 5 ) at a different level in the shaft seal chamber ( 9 ) are arranged. Compressor ( 1 ) according to one of the preceding claims, characterized in that the Suction channel ( 13 ) is formed such that the suction gas issuing from the same mainly the / a region of the / a sealing gap of the shaft seal ( 8th ) and / or around the shaft seal ( 8th ) is turned around. Compressor ( 1 ) according to one of claims 9 to 19, characterized in that between at least two components of the cylinder head ( 4 ) a thermal insulation ( 16 ) is arranged. Compressor ( 1 ) according to claim 20, characterized in that the thermal insulation ( 16 ) comprises a steel sheet, which on one or both sides, ie on a cylinder block ( 3 ) facing side and / or on a cylinder block ( 3 ) facing away side, elastomer coated. Compressor ( 1 ) according to one of the preceding claims, characterized in that the shaft seal ( 8th ) comprises a lip seal or a Axialgleitringdichtung. Compressor ( 1 ) according to one of the preceding claims, characterized in that on the cylinder head ( 4 ) Cooling fins ( 30 ) are arranged. Compressor ( 1 ) according to one of claims 2 to 23, characterized in that in or on the compound ( 33 ) of suction gas inlet ( 6 ) and shaft seal chamber ( 9 ) a check valve ( 15 ) is arranged.