EP2984347B1 - Device for conserving power in a piston compressor - Google Patents

Description

The invention relates to a device for power saving in a reciprocating compressor, in particular for compressed air generation in a motor vehicle, with a piston arranged axially movable in a cylinder for generating compressed air, which passes through at least one intake valve for compressing into a compression chamber of the cylinder, wherein the intake valve with pressure-controlled means for power saving cooperates.

The field of application of the invention extends primarily to reciprocating compressors for motor vehicle construction, in particular commercial vehicle construction, which are primarily used for generating compressed air for compressed air systems in the motor vehicle.

To control the flow rate of such reciprocating compressors and to regulate the pressure in downstream consumers, such as a brake system, devices for power saving are well known. These encounter the intake valve of the reciprocating compressor when a predetermined pressure is reached and this acts as a control pressure on a mechanical actuator for the regurgitation of the intake valve. Such devices are well known as so-called "governor" devices.

From the DE 33 29 790 A1 Alternatively, a technical solution emerges, according to which the suction plate of the compressor by means of a guided in the valve carrier actuating piston parallel to the valve support level between pump position and Neutral position is shifted, wherein in the working position, the suction ports of the compressor are in overlap with the suction plate, while at least partially exposed in the idle or shutdown position. In this position, the piston of the still running compressor pumps empty, so it is so sucked air from the suction chamber of the cylinder head through the at least partially exposed suction openings into the compression space and pushed back through the suction openings in the suction chamber. At the same time, however, some compression work is still done to push a small amount of air during the compression stroke through the open opposite the compression space pressure openings in the pressure chamber, the pressure valve opens at the top of the valve plate as before at a certain pressure level. Compressed air enters the pressure regulator from the pressure chamber where it is blown off to the atmosphere via a relief valve.

This means that a portion of the air sucked in during the suction cycle leaves the cylinder space through the suction openings, while a still existing proportion of the air is pushed out through the pressure openings.

During this operating condition, the lubricating oil present in the crankcase has an increased tendency to creep upwardly along the piston rings due to the reduced pressure level in the compression space, so that the lubricating oil can eventually enter the compression space and contribute to an increased accumulation in the air with lubricating oil , With prolonged operation at high temperatures, consequently, increased carbon accumulation is to be accepted.

When the intake valve is open, that is, in the idling position located Sauglamelle, continues to perform Saugarbeit during ongoing operation for the reciprocating compressor, so it is sucked air via the suction line, the open suction port and the suction valve located in neutral position in the compression chamber of the compressor and is at least partially in the Suction line pushed back again when the piston of the compressor performs compression work. The air drawn into the compression chamber is laden with oil particles which creep in the direction of the compressor chamber as a result of the reduced pressure level in the cylinder chamber along the piston rings. This fraught with oil particles air is at least partially pushed out again by the suction line, the lubricating oil is cumulative and then occurs later like a surge when switching to the conveying operation in the pressure line over.

If a turbocharger connected to the suction line parallel to the reciprocating compressor, which generates a certain negative pressure within the suction line by its suction, then there is also the danger that the oil particles of the air located in the suction line enter the turbocharger and contribute there to strong coking. Of course, such coking is highly undesirable.

In the FR 1 098 045 A a reciprocating compressor is described, the suction valve has a serving to hold open the same actuating mechanism. This is a plunger which acts on the suction valve and carries a piston which can be acted upon by the pressure of the pressure vessel connected to the compressor, such that the plunger is displaced through the piston when a pressure threshold is exceeded and the suction valve is accordingly opened. Outside of the reciprocating compressor, a check valve is provided in the suction line thereof, which opens when a negative pressure in the suction line, to suck air into the reciprocating compressor. The pressure valve of the reciprocating compressor is unaffected by the operation of the suction valve, which is constantly in the ready state, so that even in idle position of the suction valve always a certain compression work is done. As in the case of the prior art solution discussed above, the pressure valve opens at a certain pressure level, thereby performing compressor work. As a result of reduced in idle position pressure levels in the compression chamber is also in constructions of this kind the Problem that the lubricating oil along the piston rings can go up, ie in the compression space and thus enriching the air with lubricating oil is given. In addition, due to the non-return valve throttle losses, which adversely affect the efficiency of the compressor. Based on this, the object of the present invention is to provide a device for power saving in a reciprocating compressor with which as complete as possible power savings is achieved in the shutdown or idling phase, and that unnecessarily reach lubricating oil from the crankcase in the compression chamber and there An oil enrichment of the air in the suction line can contribute.

The object is achieved on the basis of a device according to the preamble of claim 1 in conjunction with its characterizing features. The following dependent claims give advantageous developments of the invention.

The invention includes the technical teaching that the actuating means the suction plate of the valve plate so coordinated actuated that it at least partially closes the at least one pressure valve opening in the valve plate or a comparable component in the idle position and simultaneously releases adjacent Saugventilquerschnitte and the suction port on the cylinder head cover or a shut off comparable component by means of a slider or the like to form an increased harmful space in the region of the cylinder head.

By performing in idle position adjustment of the suction lamella in the open position and by the simultaneously executing, at least partially closing the suction port on the cylinder head cover by means of the slide within the cylinder head optimization of the power saving is achieved. In the idling phase is through the adjustable suction plate in combination ensured with the slide that the suction line and possibly connected to the suction line filter and compressor systems are unaffected by the further idling of the piston. Due to the simultaneous, at least partially completed closure of the at least one pressure valve cross-section of the reciprocating compressor is also achieved that no unnecessary blowing off of air takes place. As a result, it is only necessary to suck a small volume corresponding to the leakage losses via a check valve, which is preferably located on the slide, when the piston of the compressor performs a suction movement in the idling position of the suction lamella. When the pressure openings of the compressor are completely closed, the additional amount of air to be sucked in from the suction line is reduced to the actually existing leakage volume, also called blow-by, in the compression chamber of the cylinder.

The suction blade can be moved as a sliding or rotary blade by means of the actuating means under control of a pressure regulator or otherwise provided control signal from its working position to the idle position, in which the at least one suction port is either partially or completely exposed, such that the in the air sucked in the compression chamber can flow back into the suction chamber. The achievable power savings is on the order of about 60%.

The solution according to the invention ensures that no unnecessary volume of air is displaced on the pressure side of the compressor. It is also prevented in particular in parallel to the suction line of the reciprocating compressor turbochargers or compressors that occur in these by sucking air laden with lubricating oil under the action of high temperatures coking. Furthermore, the efficiency of the compressor in the delivery phase is not adversely affected by the inventive solution, so it throttle losses are avoided.

The suction lamella is designed so that it works without friction. As a result, no wear between the suction plate and the valve plate occurs even with very little lubricating oil in the compression chamber. This design is therefore particularly suitable for oil-reduced compressors as well as for oil-free compressor types.

Advantageously, the suction plate is formed so that in the idle phase, the pressure openings are completely or partially closed as needed. An unnecessary displacement of a volume fraction of air in the pressure chamber therefore does not take place. Only if a certain amount of residual air to avoid icing or contamination is desired, a partial opening of the pressure openings in the valve plate is set. In addition, by closing the suction port creates a certain back pressure in the compression chamber, which helps that the lubricating oil is retained from the crankcase. The partial or complete covering of the suction openings thus contributes to a further optimization in the achievable power saving.

The actuating means, which are preferably pneumatically actuated for adjusting the suction lamella and the slide, act in a preferred embodiment of the invention substantially parallel to the plane of the valve plate and have an actuating piston which can be acted upon by a control pressure. The actuating piston can be guided in a bore of the cylinder head cover, which can be formed by casting in the cylinder head cover.

Preferably, the actuating piston acts by means of a driving pin extending through the bore, both on an actuating member rotating the suction lamella between the working and idle position and on the slide closing the suction connection.

The closing the suction port in the cylinder head cover slide is designed according to a preferred embodiment as a hinged thereto pivoting slide and lies within the cylinder head cover.

The slider is furthermore preferably provided with a minimum air valve in the region closing off the suction connection. According to a preferred embodiment, the minimum air valve acting as a check valve is a lamellar valve which consists of a minimum air valve catcher with a valve lamella cooperating therewith as a breakthrough on one end side of the pusher.

According to a preferred embodiment of the invention, the plurality of suction openings formed in the valve plate are arranged in a circular ring and can be closed with a disk-shaped as a rotary blade with openings and recesses formed suction lamella. In addition, a plurality formed in the valve plate pressure valve cross-sections can be arranged in an annular shape, which open inside the cylinder cover in a pressure chamber with connection to the pressure line, which are alternately closed with the disc-shaped suction plate. These pressure valve cross-sections interact with a pressure-valve unit arranged inside the cylinder head, preferably consisting of pressure-valve catch, pressure-valve spring and pressure-valve lamella.

Figur 1

eine schematische Darstellung eines Kolbenverdichters mit hiermit zusammenwirkender Einrichtung zur Leistungseinsparung,

Figur 2

eine perspektivische Ansicht eines aus Ventilplatte und Zylinderkopfdeckel bestehenden Zylinderkopfes des Kolbenverdichters mit integrierter Einrichtung zur Leistungseinsparung,

Figur 3

eine perspektivische Ansicht von mit der Ventilplatte (geschnitten dargestellt) zusammenwirkenden Betätigungsmitteln der Einrichtung zur Leistungseinsparung (von unten),

Figur 4

eine perspektivische Ansicht von mit der Ventilplatte (geschnitten dargestellt) zusammenwirkenden Betätigungsmitteln der Einrichtung zur Leistungseinsparung (von oben),

Figur 5

eine Draufsicht auf die Ventilplatte mit Betätigungsmitteln für die Einrichtung zur Leistungseinsparung in Arbeitsstellung,

Figur 6

eine Draufsicht auf die Ventilplatte mit Betätigungsmitteln für die Einrichtung zur Leistungseinsparung in Leerlaufstellung,

Figur 7

eine Schnittdarstellung von Linie V-V gemäß Figur 6 mit Darstellung von sich innerhalb des Zylinderkopfes befindlichen Betätigungsmitteln in der Leerlaufstellung,

Figur 8

eine Schnittdarstellung von Linie IV-IV gemäß Figur 5 mit Darstellung von sich innerhalb des Zylinderkopfes befindlichen Betätigungsmitteln in der Arbeitsstellung, und

Figur 9

eine schematische Darstellung einer Zweizylinderbauweise eines Kolbenverdichters mit hiermit zusammenwirkender Einrichtung zur Leistungseinsparung.

Further measures improving the invention will be described in more detail below together with the description of a preferred embodiment of the invention with reference to FIGS. It shows:

FIG. 1

a schematic representation of a reciprocating compressor with hereby cooperating device for power saving,

FIG. 2

a perspective view of a valve plate and cylinder head cover existing cylinder head of the reciprocating compressor with integrated device for power saving,

FIG. 3

a perspective view of with the valve plate (shown in section) cooperating actuating means of the device for power saving (from below),

FIG. 4

a perspective view of with the valve plate (shown in section) cooperating actuating means of the device for power saving (from above),

FIG. 5

a top view of the valve plate with actuating means for the device for saving power in working position,

FIG. 6

a top view of the valve plate with actuating means for the device for power saving in neutral position,

FIG. 7

a sectional view of line VV according to FIG. 6 with representation of actuating means located inside the cylinder head in the neutral position,

FIG. 8

a sectional view of line IV-IV according to FIG. 5 with representation of itself located within the cylinder head actuating means in the working position, and

FIG. 9

a schematic representation of a two-cylinder design of a reciprocating compressor with hereby cooperating device for power saving.

According to FIG. 1 For example, a piston compressor for producing compressed air essentially consists of a piston 100, which is articulated to a driven crankshaft 300 via a connecting rod 200. The crankshaft 300 is rotatably mounted in a crankcase 400. The crankcase 400 includes a cylinder which together with the piston 100 forms a compression space 500, which is provided on the front side with a cylinder head 600, which is shown here only schematically, with a power saving device integrated therein.

The cylinder head 600 comprises a slide 7 which functions as a 2/2-way valve and activates a suction connection 1 of the reciprocating compressor with integrated minimum air valve 8. The ambient air sucked in via the suction connection 1 passes via the slide 7 within the cylinder head 600 into a dead space formed therein and switchable Serving suction chamber 18. Direction of compression chamber 500, the suction chamber 18 opens in the cylinder head 600 via a - not shown - valve plate in trained suction openings. 3

The suction openings 3 are controlled via a 2/2-Wegeventilbeschaltung designed as a suction plate 4 to prevent in the valve position shown, which corresponds to the working position of the compressor via a check valve function, a return flow of compressed air into the suction chamber 18 and the generated compressed air over at least a likewise formed in the valve plate pressure bore 5 with downstream pressure valve unit 9 eject. Specifically, without a voltage applied to the actuating means for the device for power saving control pressure S - as shown here - the mechanism is pressed by the spring force of a return spring 12 in the working position. When the control pressure S is applied, the pressure bores 5 are at least partially closed and the suction openings 3 are opened - in the other switching position of the suction lamella 4, not shown here. The piston 100 then only compresses into the now closed suction chamber 18.

Any, for example, the piston 100 passing leakage losses are compensated by the check valve function of the minimum air valve 8. The minimum air valve 8 of the slide 7 also serves to ensure a reduced flow rate in the case of a blocked in the closed position mechanism and thus constitutes a safety function.

According to FIG. 2 the cylinder head 600 in the outer view essentially consists of a valve plate 2, on which an intermediate plate 20 is placed for extended placement of the device for power saving, which is followed by a cylinder head cover 21. In the cylinder head cover 21, there is disposed an opening for supplying the control pressure S for the power saving device to be accommodated inside the cylinder head 600.

At the bottom of the valve plate 2, the disc-shaped designed as a rotary blade suction plate 4 is arranged. The Sauglamelle 4 is here in the working position, wherein - in accordance with FIG. 1 - Which are arranged annularly arranged in the valve plate 2 introduced pressure holes 5, while here - not recognizable - covered by the suction plate 4 and also annularly arranged in the valve plate 2 suction ports 3 are covered.

The FIG. 3 11 illustrates, in contrast to the external view described above, a partial sectional bottom view of the power saving device with omission of the intermediate plate 20 and cylinder head cover 21, showing in detail the actuating means for the power saving device in the working position.

The pneumatically actuated actuating means comprise a parallel to the plane of the valve plate 2 guided and acted upon by the control pressure S actuating piston 11. The actuating means are in the control pressure-less Starting position. Here, a coupled to the actuating piston 11 driving pin 17 acts via a rotary lever 10 with a rotary lever axis 14 for actuation on the suction plate 4, to switch them between working and idle position. At the same time, the driving pin 17 of the actuating piston 11 actuates the slide 7 serving to actuate the suction port 1 (not shown), which is articulated via a pivot bearing 13 and designed as a pivoting slide. The slide 7 is provided in the region closing off the suction connection 1 with a minimum air valve 8a, 8b.

In the illustrated working position, the suction lamella 4 closes the suction openings 3 formed in the valve plate, while at the same time adjacent pressure valve cross sections 5 are released via openings 6 in the suction lamella 4. The pressure valve cross sections 5 cooperate with a pressure valve unit 9a-9c, which form a check valve to the delivery side.

The FIG. 4 is a top view of the in the FIG. 3 shown mechanism, the above in connection with the FIG. 3 used reference numerals apply using the above detailed description. Illustrated by way of illustration here is the functional position of the actuating means of the device for power saving. In addition, it can be seen that the slide 7 is provided at the end, which is not shown here - the suction connection 1, with a minimum air intake opening 15 of the minimum air valve 8 (not shown here).

According to FIG. 5 the device for power saving using the component designation according to the preceding detailed description is shown in the working position. Here, the attached to the valve plate 2 suction plate 4 covers the introduced into the valve plate 2 suction ports 3 and the adjacent pressure valve cross sections 5 of the valve plate 2 are opened via the openings 6 in the suction plate 4. At the same time, the suction port 1 is not in - further illustrated - cylinder head because of the pivoted away therefrom slide 7 in the open position. This working position is achieved in the control-pressure-free state of the actuating piston 11, which is pressed by a return spring 12 in the starting position.

In the FIG. 6 on the other hand, the actuating piston 11 is tax-pressurized, so that the device for power saving is in the neutral position. Here, the suction openings 3 of the valve plate 2 are opened by recesses 16 of the suction plate 4, whereas the pressure valve cross-sections 5 are closed, since they are not in accordance with the corresponding openings 6 in the suction plate 4. At the same time, the suction port 1 in the cylinder head (not shown here) is closed by the end of the slide 7, so that air can only flow via the minimum air valve 8 through the minimum air intake 15 into the suction chamber 18 (not shown here).

The FIG. 7 is a sectional view of line VV FIG. 6 and illustrates the device for power saving in neutral position. Evidently, the actuating piston 11 of the actuating means for the power-saving device in a corresponding bore 22 in the cylinder head cover 21 is guided to form a piston-cylinder unit, which is acted upon by the control pressure. The driving pin 17 arranged on the outer circumference of the actuating piston 11 extends through an oblong hole-shaped recess in the cylinder head cover 21 into the slide 7 designed as a pivoting lever.

About the driving pin 17, the rotary lever 10 is further actuated, which actuates the suction blade 4 via the rotary lever axis 14. The pressure valve unit cooperating with the pressure valve cross sections 5 in the valve plate 2 consists of a pressure valve catch 9a, a pressure valve spring 9b and a pressure valve cam 9c, which is arranged here in the region of the intermediate plate 20 of the cylinder head. in the Otherwise, the above detailed description applies with regard to the remaining reference numbers.

The FIG. 8 is a sectional view of line IV-IV in FIG. 4 and illustrates the device for power saving in the working position. Incidentally, the above detailed description also applies here with regard to the reference numbers used.

The FIG. 9 shows a two-cylinder construction of a reciprocating compressor, in which the same suction space is used by both cylinders. The slider 7 'is present only once, since there is only one suction port 1 in this embodiment. Each compression chamber 500 and 500a is associated with its own rotatable suction plate 4 and 4a. In the idle phase then pushes a piston 100, the air via the suction chamber 18 in the other compression chamber 500a at 180 ° stroke displacement at this moment just a downwardly moving piston 100a has, so sucks. Due to the large cross-sectionally open suction openings 3, 3a and the freely flow through the suction chamber 18, only very small throttling losses occur. Again, the cylinder pressure on the size of the approved Saugkanalquerschnitte interpret so that enough back pressure to avoid oil leakage remains.

LIST OF REFERENCE NUMBERS

1

suction

2

valve plate

3

suction opening

4

suction plate

5

Pressure valve area

6

breakthrough

7

pusher

8th

Minimum air valve

9

Pressure valve unit

10

lever

11

actuating piston

12

Return spring

13

pivot bearing

14

Pivot lever axis

15

Mindestluftansaugöffnung

16

recess

17

driving pin

18

suction

19

Pressure chamber (delivery side)

20

intermediate plate

21

Cylinder head cover

22

drilling

100

piston

200

pleuel

300

crankshaft

400

crankcase

500

compression chamber

600

cylinder head

S

control pressure

Claims (10)

1. Device for conserving power in a piston compressor, in particular for generating compressed air in a motor vehicle, having a piston (100), which delimits a compression chamber (500), for generating compressed air, which, originating from the ambient environment, enters the compression chamber (500) for compression via at least one suction port (1) formed on a cylinder head cover (21) and via an intake valve array arranged on a valve plate (2), wherein, for the purpose of conserving power, a pressure-dependently acting idling device is provided for the intake valve array, which is provided with an associated suction lamella (4), wherein the suction lamella (4) can be rotated by actuating means between a working position overlapping at least one suction opening (3) and an idling position exposing, at least in part, the at least one suction opening (3), characterised in that the actuating means actuate the suction lamella (4) in a coordinated manner in such a way that, in the idling position, said lamella (4) exposes the at least one suction opening (3) in the valve plate (2) while simultaneously closing adjacent pressure valve cross-sections (5), at least partially, and blocks the suction port (1) on the cylinder head cover (21) by means of a slider (7) in order to form an increased dead space in the region of the cylinder head (600).
2. Device according to claim 1,
   characterised in that the pneumatically controlled actuating means have an actuating piston (11), which is guided substantially parallel to the plane of the valve plate (2) in the region of the cylinder head cover (21) and can be subjected to a control pressure.
3. Device according to claim 2,
   characterised in that the actuating piston (11) is guided in a bore (22) in the cylinder head cover (21).
4. Device according to claim 2,
   characterised in that the pneumatic actuating piston (11) that can be subjected to control pressure can be moved into an initial position free from control pressure, corresponding to the working position, by a return spring (12).
5. Device according to claims 2 and 3,
   characterised in that the actuating piston (11) acts by means of a driver pin (17) coupled thereto on a rotary lever spindle (14), which rotates the suction lamella (4) between the working position and the idling position, and also on the slider (7), which closes the suction port (1).
6. Device according to claim 1,
   characterised in that the slider (7), which closes the suction port (1), is designed as a pivoted slider attached to the cylinder head cover (21).
7. Device according to claim 1,
   characterised in that the slider (7) is provided with a minimum air valve (8a, 8b) in the region that closes the suction port (1).
8. Device according to claim 7,
   characterised in that the minimum air valve (8a, 8b), which is designed as a check valve, is a reed valve, which comprises a minimum air valve stop, formed as an aperture (8a) at the end of the slider, with a valve reed (8b) interacting therewith.
9. Device according to claim 1,
   characterised in that a plurality of suction openings (3) formed in the valve plate (2) are arranged in a circular ring shape and interact with a suction lamella (4) designed as a disc-shaped rotary lamella having apertures (6) and openings (16).
10. Device according to claim 9,
    characterised in that a plurality of pressure valve cross-sections (5) formed in the valve plate (2) are furthermore arranged in a circular ring shape and interact alternately with the disc-shaped suction lamella (4) in the manner of a valve.

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