WO2012163619A1 - Compressor having pressure limitation - Google Patents

Abstract

The invention relates to a compressor unit in a portable compressed air source, comprising a reciprocating compressor that is powered by way of a slider crank mechanism having a piston that is oscillatingly moved in a cylinder and defines a compressing chamber. On the output side, the cylinder is closed by way of a cylinder head having an exhaust valve. In the pressure-means supply line to the compression chamber, a valve is arranged, by way of which the input cross section of the pressure-means supply line can be adjusted subject to the pressure generated in the compression chamber.

Description

 description

Compressor with pressure limitation

The invention relates to a compressor unit in a portable compressed air source, which one driven by a sliding crank drive or a sliding crank gear

Reciprocating compressor having a piston oscillating in a cylinder and a compression space bounding piston, wherein the cylinder is the output side closed by a cylinder head with exhaust valve

Such compressor units are z. B. with or as part of devices for sealing and inflating inflatable objects, in particular for sealing and inflation of motor vehicle tires needed (breakdown sets).

These portable and lightweight devices include the compressor unit as

Compressed gas source further comprise a sealant container for a fillable in the inflatable article of automatic sealant, a valve and distributor unit for sealant and compressed gas and are provided with a connectable to the compressed gas source inlet line and connectable to the inflatable object outlet. In such devices, the maximum pressure in the system is determined either by the maximum achievable pressure of the compressor, the maximum pressure then depends significantly on the design of the so-called "dead volume" of the cylinder, or is determined by a pressure relief valve

Limiting valves open on the high pressure side and allow a volume flow on the high pressure side to exit the system. An essential disadvantage here is that when initiated by opening the pressure relief valve Occurrence of such a flow rate during the pumping of sealant to a small extent to a reflux of tire sealant may come in the subsequent to the compressor lines. By this reflux then either the pressure gauge function or the exhaust valve of the compressor can be impaired in its function

A similar solution shows the DE 44 29 097 AI. There, a compressor unit or a piston compressor is disclosed with a conventional in the art exhaust valve, which is also the only "pressure relief valve" for the interior of the compressor Such a discharge valve consists of a spring-loaded disc which covers an outlet bore of the compression chamber in the cylinder and Apart from the fact that such an outlet valve for very high opening frequencies, ie for very fast moving reciprocating compressors with short stroke, is only suitable to a limited extent, it is necessary here, a certain pipe distance to the sealant container or for This will increase the overall size of devices for sealing and inflating inflatable objects A 1 discloses a control of the oil flow rate in a hydraulic supply by means of a suction-controlled

Feed pump. In this case, a valve in a supply line to the feed pump is switched so that at low pressure requirement in the system, a small volume flow is provided by the feed pump and at high pressure requirement a high

Volume flow. A pressure limit in the true sense does not take place here.

Commercially available puncture kits for tire sealing, which have a small compressor, with the help of tires can be used, so use to limit the maximum pressure either the exhaust valve in the compression chamber or a valve downstream in the flow direction of the compression chamber Lines, z. B. in the subsequent distribution unit, which thus between

Exhaust valve and tire valve or between compressor and pressure gauge is arranged.

The practice is evident in these embodiments that - as already described - when pumping sealant pressure conditions can arise, which lead to the fact that it comes to an undesirable Dichtmittelrückfluß, which makes the compressor useless. On the other hand prevents a pressure relief valve in the subsequent distribution unit between exhaust valve and tire valve also that with the compressor off with the integrated pressure gauge, the existing pressure remains measurable. Accordingly, an additional check valve between compressor and pressure gauge does not solve the problem satisfactorily.

For the invention therefore had the task of providing a pressure relief valve, which ensures the limitation of the maximum pressure in the compression chamber while avoiding Dichtmittelrückfluß, avoids a sudden on the high pressure side emerging from the system flow and thus increases the overall service life and reliability of the compressor.

This object is achieved by the features of the main claim. Further advantageous embodiments are disclosed in the subclaims.

It is in the pressure medium supply line to the compression chamber a valve for the

Compression space arranged through which the inlet cross section of the

Pressure medium supply depending on the pressure generated in the compression space, i. from the pressure on the high pressure side of the compressor, is variable and which thus provides a kind of suction control for controlling and limiting an overpressure. The valve should be near the cylinder head or in the cylinder head.

By such a construction according to the invention, it is possible to reduce dead volume of the cylinder and thereby significantly increase the efficiency of the compressor at low pressures. It is therefore essential for the embodiment according to the invention that a pressure limitation of the system is achieved without a volume flow having to be made on the high-pressure side to the outside. This is achieved, on the one hand, by the fact that the inlet valve of the compressor is located on the cylinder and not, as in many other designs, on the piston. The core idea is to dynamically limit the intake air flow during operation so that a certain selected pressure is not exceeded on the high-pressure side of the compressor. An advantageous development is that the valve is pressure-controlled and the pressure generated in the compression chamber acts as a control pressure on the pressure-controlled valve. This is an easy to implement and very effective control of the pressure relief without special additional control, actuators or sensors. Advantageously, the valve is upstream of the inlet valve for the flow direction

Compression space arranged so that there is a simple construction of the leads to the cylinder and standard components can be used.

A further advantageous embodiment in this sense is that the control line for the control pressure of the valve is connected directly to the outlet of the compression chamber.

Another and especially for the protection of the compression space in front of a

Return flow of conveying / sealing means advantageous embodiment is that the control line for the control pressure in the flow direction behind the outlet valve is connected to the outlet of the compression chamber.

A further advantageous embodiment is that the valve has a spring-loaded and the inlet cross-section changing sliding throttle body, wherein the control pressure shifts the throttle body to reduce the inlet cross-section against the spring force, in particular in combination with a further advantageous Training, which consists in that the throttle body is designed as a displaceable throttle piston.

Here, a piston / slide is mounted on the inlet side in front of the inlet valve, which can close the inlet channel and reopen. This pressure regulating piston is connected directly to the high pressure area on the other side. A spring ensures that the piston is retracted at low pressure and the flow on the inlet side is not affected. Depending on the diameter of the piston or

Spring stiffness of the spring used, this piston will now move with increasing pressure in the inlet channel and close this part. This will reduce the efficiency of the compressor and the pressure will not exceed a certain one

Maximum pressure rise. If the pressure in the system drops, the control piston becomes the

Release inlet duct again

Particularly suitable is such a compressor unit for use with a

Device for sealing and inflating inflatable objects, in particular for sealing and inflating motor vehicle tires.

Reference to an embodiment of the invention will be explained in more detail. Show it

Fig. 1 shows the cylinder head of a compressor unit according to the invention with a valve in the pressure medium supply line whose inlet cross section is variable depending on the pressure generated in the compression chamber, here with the valve open

 Fig. 2 shows the cylinder head of a compressor unit of FIG. 1, here with partially closed valve / throttled cross-section

Fig. 1 shows the cylinder head 1 of a compressor unit according to the invention with a valve 2 in the pressure medium supply line 3, through which the inlet cross section 4 of the pressure medium supply line 3 depending on the pressure generated in the compression chamber 5 is changeable. Fig. 1 shows the valve 2 in the open state.

The cylinder head 1 is provided with an exhaust valve 6 and with an intake valve 7 for the compression space 5. The compression space 5 is formed here and limited by the cylinder or cylinder head 1 and the piston 11th

The valve 2 is thus arranged on or in the pressure medium supply line 3 to the compression chamber 5, here immediately following the cylinder head 1. The valve 2 is arranged in the flow direction before the actual inlet valve 7 for the compression chamber 5

The control line 8 for the control pressure of the valve 2 is connected behind the outlet valve 6 to the outlet 9 of the compression chamber 5. The pressure generated in the compression chamber 5 thus acts as a control pressure on the pressure-controlled valve 2.

The valve 2 has a spring-loaded and the inlet cross section 4 changing sliding throttle body 10, wherein the control pressure shifts the throttle body to reduce the inlet cross-section against a spring force of a spring not shown here. The throttle body 10 is formed as a displaceable throttle piston.

Fig. 2 shows the cylinder head with partially closed valve / throttled

Inlet cross section 4 of the pressure medium supply line 3. The valve 2 thus acts like a

Pressure relief valve, but by a control or regulation of

Pressure medium supply, ie a regulation of the intake volume. LIST OF REFERENCE NUMBERS

(Part of the description)

1 cylinder head

2 valve

 3 pressure medium supply line

4 inlet cross section

5 compression space

6 exhaust valve

7 inlet valve

8 control line

9 outlet pipe

10 throttle body

11 pistons

Claims

claims 1. Compressor unit in a portable compressed air source, which one over a  Thrust crank driven reciprocating compressor with a piston oscillating in a cylinder and a compression chamber (5) limiting piston (11), the cylinder is on the output side by a cylinder head (1) with outlet valve (6) is closed, characterized in that in the pressure medium supply line (3 ) to the compression space (5) a valve (2) is arranged, through which the inlet cross-section (4) of the pressure medium supply line (3) is variable depending on the pressure generated in the compression space (5). 2. Compressor unit according to claim 1, wherein the valve (2) in the flow direction in front of the inlet valve (7) for the compression space (5) is arranged 3. Compressor unit according to claim 1 or 2, wherein the pressure in the compression space (5) generated as a control pressure on a pressure-controlled valve (2) acts. 4. Compressor unit according to claim 3, wherein the control line (8) for the  Control pressure of the valve (2) on the outlet line (9) of the compression chamber (5) is connected. 5. Compressor unit according to claim 4, wherein the control line (8) for the  Control pressure downstream of the outlet valve (6) at the  Outlet line (9) of the compression chamber (5) is connected. 6. A compressor unit according to any one of claims 1 to 5, wherein the valve (2) has a spring loaded and the inlet cross section changing displaceable Has throttle body (10), wherein the control pressure the throttle body (10) for Reduction of the inlet cross-section (4) against the spring force shifts. 7. Compressor unit according to claim 6, wherein the throttle body (10) as  slidable throttle piston is formed. 8. Apparatus for sealing and inflating inflatable articles,  in particular for sealing and inflating motor vehicle tires, with a compressor unit according to claims 1 to 7.